EWI and Ohio State Center for Automotive Research to Host
COLUMBUS, Ohio, April 18, 2012 /PRNewswire-USNewswire/ -- EWI and the Ohio State Center for Automotive Research (CAR) are hosting the 2012 Battery Symposium: Life, Reliability and Manufacturing on May 2-3, 2012 in Columbus. It is the third time the organizations have joined forces to share battery technology knowledge and innovation with industry in a 2-day, convention-style format.
During the event, EWI will present the latest trends in advanced Canon LP-E6 battery assembly (manufacturing/joining), including material selection, joint design, welding, nondestructive evaluation, and design for disassembly. Results from Department of Energy-sponsored research and other recent studies will be shared. Speakers from Ohio State and CAR Technologies will discuss the links between characterization, testing, and lifetimes of batteries. Talks will range from the nanoscale materials, to total battery systems, to environmentally-safe disposal. Keynote speakers from Ford and IHS Automotive will also be featured.
Along with attending more than a dozen technology presentations, symposium attendees will have the opportunity to tour the laboratories of EWI and OSU CAR where energy storage innovation is taking place. They will also see OSU's land-speed record-setting Buckeye Bullet electric race car and EcoCar 2 firsthand. Meals and an evening reception on May 2nd are included. Pre-registration is required. Visit http://www.battery-store.co.uk/ for details and to register.
About EWI
EWI is an international thought-leader on materials joining and allied technologies. It uses manufacturing technology innovation to increase the competitiveness of over 2,700 member locations of global leaders in the advanced energy, aerospace, automotive, government/defense, heavy manufacturing, oil and gas, and consumer products industries. EWI also operates a variety of technology-based centers and consortia to further increase U.S. manufacturing innovation. To learn more, visit http://www.buy-laptop-battery.org/, email info@ewi.org, or call 614.688.5000.
SOURCE EWI
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iPad 2 Foldable Leather Case Built-in Bluetooth Keyboard + Battery
2012-04-19
Canon PowerShot Elph 520 HS..
Canon PowerShot Elph 520 HS Review: Ultracompact Camera With 12X Optical Zoom
Pocket-megazoom cameras have been around for a few years now, but you probably haven't seen one as small or as simple as the Canon PowerShot Elph 520 HS ($300 as of April 7, 2012). In a way, it represents a new breed of basic compact camera: Rather than cramming more megapixels into a tiny sensor, the 10-megapixel PowerShot Elph 520 HS keeps the pixel count relatively sane and jacks up the optical zoom to 12X (28mm to 336mm), an impossible-sounding level for a camera of this size.
This tiny little camera can fit comfortably in a shirt or pants pocket; at just 0.76 inch deep, it's the size of a deck of playing cards, and it's a pocket megazoom that's even smaller than many of today's 3X-optical-zoom cameras. The trade-offs for the tiny size start with the camera's manual controls for shutter and aperture--there aren't any--but this model does offer Canon's latest auto-exposure functions, scene modes, and in-camera effects.
Regrettably, this camera is a disappointing performer, at least if you're used to the generally excellent output of Canon's PowerShot line. Our review unit made everything look a bit soft, and the PowerShot Elph 520 HS will leave many owners wanting bigger buttons, better Sony NP-F550 Battery life, and more fine-tunable control. For casual shooters who just want as much optical zoom as possible in a pocket camera, it's still a good option.Performance, Image Quality, and Video Quality
Getting a razor-sharp shot with this camera may prove to be a challenge, but if you do snap one, it should look great. In PCWorld Labs subjective tests for image and video quality, the PowerShot Elph 520 HS scored very well in most categories, but image sharpness was a major weak spot that brought down its overall score.
Although we didn't see a lot of chromatic abberation or fringing in our test shots, everything looked slightly fuzzy. Unfortunately, it's easier to fix exposure and color problems during the editing process than it is to sharpen up a soft image.
As a result, our judges gave the PowerShot Elph 520 HS a sharpness score of Poor in our tests, but its ratings for exposure quality, color accuracy, and lack of distortion were among the best we've tested in the world of point-and-shoots over the past year. Held back by the disappointing sharpness scores, its overall imaging score fell at the low end of our Very Good range.
Video performance was also a bit of a letdown, given Canon's consistently high scores for video-capture quality. Still, the PowerShot Elph 520 HS netted a video-quality score of Good. Again, fuzziness was an issue, and colors in our test footage looked a bit too vibrant to seem "real," but the camera did an admirable job of brightening up video that we shot in low light.
Another issue: This model's Canon EOS 550D battery life falls well short of the 300-plus shots we look for in a point-and-shoot camera. The PowerShot Elph 520 HS is rated at just 190 shots per charge of its tiny, ChapStick-size lithium ion battery, a score that falls in our Fair range.
Elph 520 HS: Wide-angle
Elph 520 HS: Full telephotoAs with many long-zoom cameras, the 12X-optical-zoom (28mm to 336mm) PowerShot Elph 520 HS's major drawback is its narrow maximum aperture of F3.4 at wide angle. This camera doesn't have full manual controls or aperture- and shutter-priority modes, either, although it does provide a long-shutter scene mode that lets you dial in shutter speeds from 1 second to 15 seconds.
To the left are sample shots that showcase the camera's field of view at wide-angle and full telephoto. When zooming quickly from wide-angle to full telephoto, the camera's autofocus system searches a tiny bit from midrange to full zoom, but generally locks focus on faraway subjects within a second. The camera's optical stabilization system works well in steadying shots, as long as it's dealing with a relatively normal amount of hand shakiness. You'll need to at least attempt to hold the camera steady; using a flat surface or a tripod, if possible, is always a good idea.
Elph 520 HS: Low-Light ModeThe camera can extend beyond its 12X optical zoom range to a simulated 21X digital zoom, although you will see a loss of detail and paintlike pockmarking at larger sizes in shots taken with the digital zoom enabled.
The PowerShot Elph 520 HS also has a Program mode that lets you set ISO (100 to 3200), white balance presets, and light-metering presets (evaluative, centered, and spot metering), as well as Canon's full boat of specialized shooting modes. You can preview and apply a few fun filter effects as you're shooting, such as a tilt-shift-simulating Miniature Mode, a Toy Camera filter, and a fish-eye lens effect.
lph520 HS: Color Accent ModeElph 520 HS: Color Swap ModeTo eke the most out of the PowerShot Elph 520 HS's 10-megapixel backside-illuminated CMOS sensor, you can turn to a couple of low-light scene modes available in the camera's menus. Handheld Night Scene mode stacks three shots taken in rapid succession at different exposure settings to create an HDR-like photo that brings out detail in darker scenes. Low-Light mode jacks up the ISO and uses pixel binning to increase light sensitivity while reducing resolution to 2.5 megapixels.
Of those two modes, Handheld Night Scene performed much better in my hands-on tests, producing more-accurate white balance and sharper contrast in low-light scenes. That said, both modes' images suffered from noise and a decrease in detail when we viewed the results at larger sizes (you can see sample shots taken in each mode above).
Other scene-mode highlights include Canon's Color Accent and Color Swap modes, which let you bring out a single color in an otherwise black-and-white photo or swap instances of colors in a photo, respectively. You can see examples of those modes in action to the left; in Color Accent mode, red is the only color visible, and in Color Swap mode, I switched all the red objects in the frame to yellow.
Like other recent Canon cameras, the CMOS-sensored PowerShot Elph 520 HS also has a high-speed still-shooting mode (about 7 shots per second at a reduced 2.5-megapixel resolution) and a superslow-motion movie mode that records 320-by-240 footage at 240 frames per second or 640-by-480 footage at 120 fps.
The PowerShot Elph 520 HS also performs well in macro mode, with the ability to capture a clear close-up shot when you position the lens less than an inch away from the subject. All in all, despite the lack of manual exposure controls, the in-camera settings cover a wide array of photo options.
Although the camera doesn't offer a raised handgrip, it is small enough, and light enough, to hold comfortably with an index finger around the edge. The control scheme is a departure from most Canon PowerShots, which have all of their controls handled by tiny buttons on the back and top of the camera rather than the usual directional pad or scrollwheel.
A 3-inch-diagonal LCD screen and seven small buttons, each of which is about the size of a piece of confetti, dominate the back of the camera. You get a dedicated video-record button; a diamond-shaped arrangement of four buttons that let you navigate menus and supply quick access to exposure compensation, macro mode, flash, and display settings; and two buttons below that let you select a function and access the in-camera menu.
On the top of the camera are the expected shutter button/zoom control, the power button, a toggle switch for selecting between Auto mode and the camera's program and scene modes, and a playback button. Three doors cover ports on the camera, consisting of one for the Charger for Fujifilm FinePix J30 port and another for the MicroSD card slot on the bottom of the camera, plus a plasticky door on the side of the camera that covers both a Mini HDMI connection and a Mini-USB port. You get a tripod mount on the bottom of the camera as well.If you're eyeing this camera, that MicroSD card is something to think about. It may not be a huge deal for anyone who plans to buy a camera and a storage card in one trip to the store, but anyone who owns a full-size SD/SDHC/SDXC card that they were hoping to use with this camera is out of luck. Many MicroSD cards come with a MicroSD-to-SD-Card converter, which you may need to use to offload photos and video to your computer, although connecting the camera via USB will work for that, too.
The major issues are the less-than-sharp images, the disappointing Canon NB-5L battery life, Canon's space-saving decision to use a MicroSD card for storage, and the lack of manual controls. It's a small camera, too, which offers benefits in terms of sheer portability but also means it has tiny buttons (so it may be a challenge for larger-handed users to operate). Overall, the Canon PowerShot Elph 520 HS disappoints in photo quality and performance, but as a simple, pocketable camera that offers impressive optical reach for its size, it should do the trick for many casual photographers.
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Pocket-megazoom cameras have been around for a few years now, but you probably haven't seen one as small or as simple as the Canon PowerShot Elph 520 HS ($300 as of April 7, 2012). In a way, it represents a new breed of basic compact camera: Rather than cramming more megapixels into a tiny sensor, the 10-megapixel PowerShot Elph 520 HS keeps the pixel count relatively sane and jacks up the optical zoom to 12X (28mm to 336mm), an impossible-sounding level for a camera of this size.
This tiny little camera can fit comfortably in a shirt or pants pocket; at just 0.76 inch deep, it's the size of a deck of playing cards, and it's a pocket megazoom that's even smaller than many of today's 3X-optical-zoom cameras. The trade-offs for the tiny size start with the camera's manual controls for shutter and aperture--there aren't any--but this model does offer Canon's latest auto-exposure functions, scene modes, and in-camera effects.
Regrettably, this camera is a disappointing performer, at least if you're used to the generally excellent output of Canon's PowerShot line. Our review unit made everything look a bit soft, and the PowerShot Elph 520 HS will leave many owners wanting bigger buttons, better Sony NP-F550 Battery life, and more fine-tunable control. For casual shooters who just want as much optical zoom as possible in a pocket camera, it's still a good option.Performance, Image Quality, and Video Quality
Getting a razor-sharp shot with this camera may prove to be a challenge, but if you do snap one, it should look great. In PCWorld Labs subjective tests for image and video quality, the PowerShot Elph 520 HS scored very well in most categories, but image sharpness was a major weak spot that brought down its overall score.
Although we didn't see a lot of chromatic abberation or fringing in our test shots, everything looked slightly fuzzy. Unfortunately, it's easier to fix exposure and color problems during the editing process than it is to sharpen up a soft image.
As a result, our judges gave the PowerShot Elph 520 HS a sharpness score of Poor in our tests, but its ratings for exposure quality, color accuracy, and lack of distortion were among the best we've tested in the world of point-and-shoots over the past year. Held back by the disappointing sharpness scores, its overall imaging score fell at the low end of our Very Good range.
Video performance was also a bit of a letdown, given Canon's consistently high scores for video-capture quality. Still, the PowerShot Elph 520 HS netted a video-quality score of Good. Again, fuzziness was an issue, and colors in our test footage looked a bit too vibrant to seem "real," but the camera did an admirable job of brightening up video that we shot in low light.
Another issue: This model's Canon EOS 550D battery life falls well short of the 300-plus shots we look for in a point-and-shoot camera. The PowerShot Elph 520 HS is rated at just 190 shots per charge of its tiny, ChapStick-size lithium ion battery, a score that falls in our Fair range.
Shooting Modes and Features
Elph 520 HS: Wide-angleElph 520 HS: Full telephotoAs with many long-zoom cameras, the 12X-optical-zoom (28mm to 336mm) PowerShot Elph 520 HS's major drawback is its narrow maximum aperture of F3.4 at wide angle. This camera doesn't have full manual controls or aperture- and shutter-priority modes, either, although it does provide a long-shutter scene mode that lets you dial in shutter speeds from 1 second to 15 seconds.To the left are sample shots that showcase the camera's field of view at wide-angle and full telephoto. When zooming quickly from wide-angle to full telephoto, the camera's autofocus system searches a tiny bit from midrange to full zoom, but generally locks focus on faraway subjects within a second. The camera's optical stabilization system works well in steadying shots, as long as it's dealing with a relatively normal amount of hand shakiness. You'll need to at least attempt to hold the camera steady; using a flat surface or a tripod, if possible, is always a good idea.
Elph 520 HS: Low-Light ModeThe camera can extend beyond its 12X optical zoom range to a simulated 21X digital zoom, although you will see a loss of detail and paintlike pockmarking at larger sizes in shots taken with the digital zoom enabled.
The PowerShot Elph 520 HS also has a Program mode that lets you set ISO (100 to 3200), white balance presets, and light-metering presets (evaluative, centered, and spot metering), as well as Canon's full boat of specialized shooting modes. You can preview and apply a few fun filter effects as you're shooting, such as a tilt-shift-simulating Miniature Mode, a Toy Camera filter, and a fish-eye lens effect.
lph520 HS: Color Accent ModeElph 520 HS: Color Swap ModeTo eke the most out of the PowerShot Elph 520 HS's 10-megapixel backside-illuminated CMOS sensor, you can turn to a couple of low-light scene modes available in the camera's menus. Handheld Night Scene mode stacks three shots taken in rapid succession at different exposure settings to create an HDR-like photo that brings out detail in darker scenes. Low-Light mode jacks up the ISO and uses pixel binning to increase light sensitivity while reducing resolution to 2.5 megapixels.
Of those two modes, Handheld Night Scene performed much better in my hands-on tests, producing more-accurate white balance and sharper contrast in low-light scenes. That said, both modes' images suffered from noise and a decrease in detail when we viewed the results at larger sizes (you can see sample shots taken in each mode above).
Other scene-mode highlights include Canon's Color Accent and Color Swap modes, which let you bring out a single color in an otherwise black-and-white photo or swap instances of colors in a photo, respectively. You can see examples of those modes in action to the left; in Color Accent mode, red is the only color visible, and in Color Swap mode, I switched all the red objects in the frame to yellow.
Like other recent Canon cameras, the CMOS-sensored PowerShot Elph 520 HS also has a high-speed still-shooting mode (about 7 shots per second at a reduced 2.5-megapixel resolution) and a superslow-motion movie mode that records 320-by-240 footage at 240 frames per second or 640-by-480 footage at 120 fps.
The PowerShot Elph 520 HS also performs well in macro mode, with the ability to capture a clear close-up shot when you position the lens less than an inch away from the subject. All in all, despite the lack of manual exposure controls, the in-camera settings cover a wide array of photo options.
Hardware and Design
There is only one word to describe the PowerShot Elph 520 HS's physical build, and that word is boxy. It's a solid deck of cards, with sharp corners and few protrusions aside from the shutter button/zoom control on the top of the camera.Although the camera doesn't offer a raised handgrip, it is small enough, and light enough, to hold comfortably with an index finger around the edge. The control scheme is a departure from most Canon PowerShots, which have all of their controls handled by tiny buttons on the back and top of the camera rather than the usual directional pad or scrollwheel.
A 3-inch-diagonal LCD screen and seven small buttons, each of which is about the size of a piece of confetti, dominate the back of the camera. You get a dedicated video-record button; a diamond-shaped arrangement of four buttons that let you navigate menus and supply quick access to exposure compensation, macro mode, flash, and display settings; and two buttons below that let you select a function and access the in-camera menu.On the top of the camera are the expected shutter button/zoom control, the power button, a toggle switch for selecting between Auto mode and the camera's program and scene modes, and a playback button. Three doors cover ports on the camera, consisting of one for the Charger for Fujifilm FinePix J30 port and another for the MicroSD card slot on the bottom of the camera, plus a plasticky door on the side of the camera that covers both a Mini HDMI connection and a Mini-USB port. You get a tripod mount on the bottom of the camera as well.Bottom Line
It's best to think of this camera as a solid, basic point-and-shoot that happens to have a particularly long lens. If you're a fan of Canon's older, easy-to-use PowerShot SD series, the PowerShot Elph 520 HS basically adds a lot of zoom to that line.The major issues are the less-than-sharp images, the disappointing Canon NB-5L battery life, Canon's space-saving decision to use a MicroSD card for storage, and the lack of manual controls. It's a small camera, too, which offers benefits in terms of sheer portability but also means it has tiny buttons (so it may be a challenge for larger-handed users to operate). Overall, the Canon PowerShot Elph 520 HS disappoints in photo quality and performance, but as a simple, pocketable camera that offers impressive optical reach for its size, it should do the trick for many casual photographers.
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2012-04-16
Analysis to explore the solar cell phone lithium-ion battery charger
The emergence of the energy crisis and the worsening environmental pollution, solar energy as a clean renewable energy countries in the world attach great importance. With the development of solar technology in recent years, ultra-thin, ultra-light photovoltaic cells in portable electronic devices has also been a great development. The solar cell phone lithium battery charger to get rid of the shackles of the traditional charging power supply, energy saving and environmental protection, and has good development prospects. [1]
Output power of photovoltaic cells by light, temperature and other environmental factors, a solar charger to the AC mains charger for lithium-ion battery for safe and fast charging, but also address the following issues [1]: ① The how changes in environmental temperature, light intensity and other external conditions into the charge control method; ② charge controller topology; ③ how to maximize the photovoltaic cell output power. In response to these issues, this paper analyzed three commonly used cell phone lithium battery charger topology and control method, pointed out that there are some limitations in the use of solar energy battery-powered. And designed a BUCK converter constitutes pulse charging control, solar cell phone lithium battery charger based on microprocessor controlled through computer simulation to verify the validity of this charger.
Analysis of a cell phone lithium battery charger Business phone lithium-ion battery charger has three types: linear chargers, pulse chargers and switch mode charger [2]. Table 1, these three charger circuit topology and charge control methods for comparison.
Advantages and disadvantages of the three types of chargers, linear chargers, linear regulator for the charging current and voltage regulation, adjust the tube's power-hungry, need to take effective measures to solve the heat problem can be seen from Table 1. Switch-mode charger by changing the switch turn-off duty cycle to achieve a constant current and constant voltage, the switch in the switch state, the loss is small, but the circuit is more complex. The pulse charger both the advantages of both, but the charger itself does not regulate the current, so a limit of the flow pattern between the power adapter used in conjunction with
In Table 1 The features and structures of three The types chargers
Charger type
Main circuit structure
Charging process
Charge termination method to judge
Charging current control mode
Advantage
Shortcoming
Linear type
Linear regulator, the linear charge control circuit
The prefilled → constant current → constant pressure
The minimum charge current, time
Linear adjustment tube to adjust
Circuit is simple, small size, low cost
Loss, low efficiency, severe fever
Pulse
Switch tubes, pulsed charge control circuit
Prefilled → fast → pulse
Ton / the Toff ratio
Rely on external current limiting power adapter
Circuit is simple, small size, low power consumption, high efficiency
Be current-limited power adapter
Switch-
DC / DC converter, PWM charge control circuit
The prefilled → constant current → constant pressure
The minimum charge current, time
Adjust the duty cycle of the DC / DC converter
Low power consumption, high efficiency, the charge current, wide input voltage range
Large volume, high cost of
The following analyzes the applicability of the above three chargers when the charger to provide power from photovoltaic cells.
(1) solar charger should be a DC / DC converter topology. The output characteristics of photovoltaic cells has a strong nonlinearity, the output of the influence of ambient temperature, light intensity and load. Can be seen from Figure 1, the output power of photovoltaic cells increased with increasing light intensity, and decrease with increasing ambient temperature. When light and temperature changes, real-time adjustment of the operating voltage of the photovoltaic cell allows it to operate near the maximum power point is the maximum power point tracking (maximum power point of tracking, MPPT) [3]. Therefore, in order to improve the output power of photovoltaic cells, the charger can adjust the input voltage to adjust the operating point of the photovoltaic cells. Linear and pulse charger input voltage is determined by the external power supply and therefore can not achieve the maximum power point tracking function. Switch-mode charger input voltage can be achieved by adjusting the duty cycle D BUCK converter input and output voltage relationship: Vo = D * Vin (Vo lithium Acer Aspire 5720 Battery terminal voltage Vin is the solar cell output voltage). Lithium battery voltage change is slow, so change the switch duty cycle D can be changed Vin in order to achieve the MPPT function.
Figure 1 photovoltaic cells under different illumination (a) and temperature (b) the P-V curve
Fig.1 The PV curves of the PV module with varying irradiation (a) and temperature (b)
(2) The solar charger should be used to pulse charge termination judgment method. Linear and switching charge mode commonly used in the two control algorithms to determine if the Panasonic Nv-ds27 Battery is full, the first detection of the minimum charge current law, the second timing method. As mentioned earlier, the output of the photovoltaic cell by the external environment. In the process of charging, due to changes in the weather or changes in the environment around the charge current drops, and drop to set the termination charge current value below the detection error minimum current law terminates the charge. Long is difficult to predict, therefore, from time to time terminate the charging method can not guarantee full of battery due to charging of the battery charge of the current instability. Pulse charging curve shown in Figure 2, the pulse charging when the battery voltage is below 4.2V turn-on switch tube to charge the battery, turn off the switch to stop charging when the battery voltage exceeds 4.2V, when Ton / Toff value below the set value that the battery is full and terminates the charge. If the charge current drops due to changes in the external environment, the battery voltage corresponding decline in Ton / the Toff value increases only when the Apple Macbook 13-Inch mb061b/A Battery is full of Ton, / the Toff will be below the set value, it will not cause the miscarriage of justice.
Fig.2 The curves of The pulse mode charge
By the above analysis, the lithium battery charger is basically a prerequisite for stable power supply design, by solar power can not be well adapted to light, temperature and other environmental changes.
2 solar cell phone lithium-ion battery charger
2.1 System Architecture
This paper, the design of the solar cell phone lithium-ion Acer Aspire 6920 Battery charger system block diagram shown in Figure 3. The charger consists of three parts: photovoltaic cells, the MCU controller with a step-down DC-DC converter.
Fig.3 of The system architecture
BUCK converter's main function is to: output a small current in the pre-charge stage Imin; solar cell maximum power point tracking in the fast-charge phase, when the current reaches Imax limit the current to the constant current charging; pulse charging the battery voltage value output current or stop output. MCU functions are: the acquisition of lithium-ion Acer Aspire 5720 Battery voltage Vbatt current Ibatt, the temperature Tbatt and solar cell voltage Vpv current Ipv; charger controlled by a software program to convert between different charge states; in a different state of charge calculate the duty cycle D, output PWM drive pulse according to the control objectives.
2.2 charging control method
In this paper, the design of the solar charge controller is a multi-objective control system [4], control the duty cycle of the target is also different in different stages of charging, the charging state transitions shown in Figure 4.
Fig. 4 of The change of charge the state
Conversion conditions: 1: Vbatt <Vmin and; 2, (3): Vbatt ≥ Vmin and; ④: Ibatt ≥ Imax; ⑤ The: Ibatt <Imax; ⑥, ⑦: Vbatt ≥ Vmax of; ⑧: Ton / the Toff ≤ settings.
(1) pre-charge: When the lithium battery into the charger, the Canon mv600 battery voltage is below the set threshold Vmin and the microcontroller on the duty cycle of the control objectives is to output a very narrow PWM pulse, a small current of the converter output Imin, over-discharge of lithium-ion battery repair and charging; if the battery voltage ≥ Vmin and can skip the pre-charge stage and go straight to the fast charge stage.
(2) fast charge: When the battery current Ibatt ≥ Imax, microcontroller-controlled constant current PWM pulse width converter output; when the output power of solar cells fall in Ibatt <Imax, then transferred to the maximum power point tracking state to adjust the duty photovoltaic cells than to change the BUCK input voltage in the vicinity of the maximum power point, back and forth to the size of the charger according Ibatt conversion MPPT with constant current between the two states until Vbatt ≥ Vmax of (4.2V), transferred to pulse charging phase.
(3) Pulse Charging: at this stage converter intermittent, constant current output, from time to time ΔT to judge the battery voltage value, if Vbatt <Vmax of output constant current to charge the battery; Vbatt ≥ Vmax of, then stop charge the HP Compaq Business Notebook NX6110 Battery. The switch drive pulse diagram shown in Figure 5. Ton is the time of the output PWM drive pulse, the Toff to stop charging time. Ton during the switch duty cycle D conduction and turn-off to the constant current control, D = ton / ts. Cycle ts determined by the switching frequency and magnitude in μs. Ton and Toff is an integer multiple of ΔT, ΔT ms order of magnitude. The beginning of the pulse charging, Ton / the Toff ratio larger, longer and longer as the battery is gradually filled, Toff Ton / the Toff is less than the set value, the battery is full, the charge termination.
Fig. 5 The drive pulse of the MOSFET
When the voltage reaches Vmax pulse charger is still applied to the lithium high-current charging pulses slightly exceeds the Vmax of the battery voltage during the pulse, but this does not prevent the battery from premature aging. On the contrary, the pulse charging can reduce the impact of polarization in the process of charging, effectively increase the charge capacity, improve the charging efficiency [5].
3 simulation results
In order to verify the feasibility of the solar cell phone lithium Acer Aspire 3682wxmi Battery charging method using matlab simulink toolbox to build a system simulation model [6-8], Simulink simulation model shown in Figure 6. Shown in the PV array output power is 5W, the lithium-ion battery rated capacity of 850mAh. Precharge, the MPPT, CC, Pulse module to achieve pre-charge, the maximum power point tracking constant current pulse charging function, multi-channel switch controlled by the Control module to convert. Maximum power point tracking PV array output power results directly change the duty cycle of DC / DC converter mountaineering method [9]. By changes in light intensity of the signal module signal1 simulation. Pre-charge voltage threshold is set to 2.9V, precharge flow Imin is set to 0.1C (C is the rated capacity of the lithium battery). Constant current charging current is set to 1C, taking into account the influence of the inductor current ripple, set MPPT with constant-current conversion threshold 0.95Imax. ΔT is set to 64ms, Ton / the Toff is less than 1/256 that the battery is fully charged.
Fig. 6 the System simulation model in. Simulink
Figure 7 shows the light intensity, the simulation results shown in Figure 8 (a) as shown. Conversion in Figure 8 (c) can be seen from the charging status when the illumination changes of the 1000s and 2000s, the charger can automatically switch between the constant current with MPPT charge optimization charging current Ibatt of. Pulse charging stage, when the light shines in the 4000s at the drop, the charger continues charging until Ton / the Toff is less than the set value, the battery is full. By amplification of the current waveform in Figure 8 (b) can be seen as the charging time of growth Toff progressively larger process. Voltage Vbatt curve in line with the charging characteristics of lithium batteries, the Apple a1280 Battery is full after the voltage is maintained at 4.2V.
Figure 9 Simulation results when the charger does not have the MPPT function in the same light. Be seen from the graph the charging current when the fall of the 1000s-2000s light was significantly lower than the current 8 (a), the lithium battery voltage increases slowly, resulting in the total charging time of about 400s.
Figure 10 Figure 6 Pulse module with a constant voltage module instead of the simulation results, the minimum detectable current method (less than 0.1C) for charge termination. Into the constant voltage charging phase, the decline of the 4000s at the light charger immediately stop charging, however, the current decline is due to external factors, not the battery is fully charged, the lithium battery voltage quickly decreased.
4 Conclusion
In this paper, the design of solar cell phone lithium battery charger with DC / DC converter topology to achieve the maximum power point tracking, to maximize the efficiency of photovoltaic cells, charge termination judgment, taking into account the light intensity, ambient temperature and other factors on The lithium Canon Bp-2l12 battery charging curve, accurate charge termination judgment, so that the lithium battery rated capacity.
Fig.7 Change of the irradiation
Figure 8 (a) The pulse rechargeable lithium battery voltage, current waveform diagram (b) enlarged map (c) charge state transition diagram
Fig.8 (a) Voltage and current wave of the Li-ion battery in the pulse charge mode (b) local zoom (c) The change of charge state
Fig.9 Voltage and current wave of the Li-ion Acer Aspire 5740 Battery without the MPPT
Fig.10 Voltage and current wave of the Li-ion battery in the CC-CV charge mode
Output power of photovoltaic cells by light, temperature and other environmental factors, a solar charger to the AC mains charger for lithium-ion battery for safe and fast charging, but also address the following issues [1]: ① The how changes in environmental temperature, light intensity and other external conditions into the charge control method; ② charge controller topology; ③ how to maximize the photovoltaic cell output power. In response to these issues, this paper analyzed three commonly used cell phone lithium battery charger topology and control method, pointed out that there are some limitations in the use of solar energy battery-powered. And designed a BUCK converter constitutes pulse charging control, solar cell phone lithium battery charger based on microprocessor controlled through computer simulation to verify the validity of this charger.
Analysis of a cell phone lithium battery charger Business phone lithium-ion battery charger has three types: linear chargers, pulse chargers and switch mode charger [2]. Table 1, these three charger circuit topology and charge control methods for comparison.
Advantages and disadvantages of the three types of chargers, linear chargers, linear regulator for the charging current and voltage regulation, adjust the tube's power-hungry, need to take effective measures to solve the heat problem can be seen from Table 1. Switch-mode charger by changing the switch turn-off duty cycle to achieve a constant current and constant voltage, the switch in the switch state, the loss is small, but the circuit is more complex. The pulse charger both the advantages of both, but the charger itself does not regulate the current, so a limit of the flow pattern between the power adapter used in conjunction with
In Table 1 The features and structures of three The types chargers
Charger type
Main circuit structure
Charging process
Charge termination method to judge
Charging current control mode
Advantage
Shortcoming
Linear type
Linear regulator, the linear charge control circuit
The prefilled → constant current → constant pressure
The minimum charge current, time
Linear adjustment tube to adjust
Circuit is simple, small size, low cost
Loss, low efficiency, severe fever
Pulse
Switch tubes, pulsed charge control circuit
Prefilled → fast → pulse
Ton / the Toff ratio
Rely on external current limiting power adapter
Circuit is simple, small size, low power consumption, high efficiency
Be current-limited power adapter
Switch-
DC / DC converter, PWM charge control circuit
The prefilled → constant current → constant pressure
The minimum charge current, time
Adjust the duty cycle of the DC / DC converter
Low power consumption, high efficiency, the charge current, wide input voltage range
Large volume, high cost of
The following analyzes the applicability of the above three chargers when the charger to provide power from photovoltaic cells.
(1) solar charger should be a DC / DC converter topology. The output characteristics of photovoltaic cells has a strong nonlinearity, the output of the influence of ambient temperature, light intensity and load. Can be seen from Figure 1, the output power of photovoltaic cells increased with increasing light intensity, and decrease with increasing ambient temperature. When light and temperature changes, real-time adjustment of the operating voltage of the photovoltaic cell allows it to operate near the maximum power point is the maximum power point tracking (maximum power point of tracking, MPPT) [3]. Therefore, in order to improve the output power of photovoltaic cells, the charger can adjust the input voltage to adjust the operating point of the photovoltaic cells. Linear and pulse charger input voltage is determined by the external power supply and therefore can not achieve the maximum power point tracking function. Switch-mode charger input voltage can be achieved by adjusting the duty cycle D BUCK converter input and output voltage relationship: Vo = D * Vin (Vo lithium Acer Aspire 5720 Battery terminal voltage Vin is the solar cell output voltage). Lithium battery voltage change is slow, so change the switch duty cycle D can be changed Vin in order to achieve the MPPT function.
Figure 1 photovoltaic cells under different illumination (a) and temperature (b) the P-V curve
Fig.1 The PV curves of the PV module with varying irradiation (a) and temperature (b)
(2) The solar charger should be used to pulse charge termination judgment method. Linear and switching charge mode commonly used in the two control algorithms to determine if the Panasonic Nv-ds27 Battery is full, the first detection of the minimum charge current law, the second timing method. As mentioned earlier, the output of the photovoltaic cell by the external environment. In the process of charging, due to changes in the weather or changes in the environment around the charge current drops, and drop to set the termination charge current value below the detection error minimum current law terminates the charge. Long is difficult to predict, therefore, from time to time terminate the charging method can not guarantee full of battery due to charging of the battery charge of the current instability. Pulse charging curve shown in Figure 2, the pulse charging when the battery voltage is below 4.2V turn-on switch tube to charge the battery, turn off the switch to stop charging when the battery voltage exceeds 4.2V, when Ton / Toff value below the set value that the battery is full and terminates the charge. If the charge current drops due to changes in the external environment, the battery voltage corresponding decline in Ton / the Toff value increases only when the Apple Macbook 13-Inch mb061b/A Battery is full of Ton, / the Toff will be below the set value, it will not cause the miscarriage of justice.
Fig.2 The curves of The pulse mode charge
By the above analysis, the lithium battery charger is basically a prerequisite for stable power supply design, by solar power can not be well adapted to light, temperature and other environmental changes.
2 solar cell phone lithium-ion battery charger
2.1 System Architecture
This paper, the design of the solar cell phone lithium-ion Acer Aspire 6920 Battery charger system block diagram shown in Figure 3. The charger consists of three parts: photovoltaic cells, the MCU controller with a step-down DC-DC converter.
Fig.3 of The system architecture
BUCK converter's main function is to: output a small current in the pre-charge stage Imin; solar cell maximum power point tracking in the fast-charge phase, when the current reaches Imax limit the current to the constant current charging; pulse charging the battery voltage value output current or stop output. MCU functions are: the acquisition of lithium-ion Acer Aspire 5720 Battery voltage Vbatt current Ibatt, the temperature Tbatt and solar cell voltage Vpv current Ipv; charger controlled by a software program to convert between different charge states; in a different state of charge calculate the duty cycle D, output PWM drive pulse according to the control objectives.
2.2 charging control method
In this paper, the design of the solar charge controller is a multi-objective control system [4], control the duty cycle of the target is also different in different stages of charging, the charging state transitions shown in Figure 4.
Fig. 4 of The change of charge the state
Conversion conditions: 1: Vbatt <Vmin and; 2, (3): Vbatt ≥ Vmin and; ④: Ibatt ≥ Imax; ⑤ The: Ibatt <Imax; ⑥, ⑦: Vbatt ≥ Vmax of; ⑧: Ton / the Toff ≤ settings.
(1) pre-charge: When the lithium battery into the charger, the Canon mv600 battery voltage is below the set threshold Vmin and the microcontroller on the duty cycle of the control objectives is to output a very narrow PWM pulse, a small current of the converter output Imin, over-discharge of lithium-ion battery repair and charging; if the battery voltage ≥ Vmin and can skip the pre-charge stage and go straight to the fast charge stage.
(2) fast charge: When the battery current Ibatt ≥ Imax, microcontroller-controlled constant current PWM pulse width converter output; when the output power of solar cells fall in Ibatt <Imax, then transferred to the maximum power point tracking state to adjust the duty photovoltaic cells than to change the BUCK input voltage in the vicinity of the maximum power point, back and forth to the size of the charger according Ibatt conversion MPPT with constant current between the two states until Vbatt ≥ Vmax of (4.2V), transferred to pulse charging phase.
(3) Pulse Charging: at this stage converter intermittent, constant current output, from time to time ΔT to judge the battery voltage value, if Vbatt <Vmax of output constant current to charge the battery; Vbatt ≥ Vmax of, then stop charge the HP Compaq Business Notebook NX6110 Battery. The switch drive pulse diagram shown in Figure 5. Ton is the time of the output PWM drive pulse, the Toff to stop charging time. Ton during the switch duty cycle D conduction and turn-off to the constant current control, D = ton / ts. Cycle ts determined by the switching frequency and magnitude in μs. Ton and Toff is an integer multiple of ΔT, ΔT ms order of magnitude. The beginning of the pulse charging, Ton / the Toff ratio larger, longer and longer as the battery is gradually filled, Toff Ton / the Toff is less than the set value, the battery is full, the charge termination.
Fig. 5 The drive pulse of the MOSFET
When the voltage reaches Vmax pulse charger is still applied to the lithium high-current charging pulses slightly exceeds the Vmax of the battery voltage during the pulse, but this does not prevent the battery from premature aging. On the contrary, the pulse charging can reduce the impact of polarization in the process of charging, effectively increase the charge capacity, improve the charging efficiency [5].
3 simulation results
In order to verify the feasibility of the solar cell phone lithium Acer Aspire 3682wxmi Battery charging method using matlab simulink toolbox to build a system simulation model [6-8], Simulink simulation model shown in Figure 6. Shown in the PV array output power is 5W, the lithium-ion battery rated capacity of 850mAh. Precharge, the MPPT, CC, Pulse module to achieve pre-charge, the maximum power point tracking constant current pulse charging function, multi-channel switch controlled by the Control module to convert. Maximum power point tracking PV array output power results directly change the duty cycle of DC / DC converter mountaineering method [9]. By changes in light intensity of the signal module signal1 simulation. Pre-charge voltage threshold is set to 2.9V, precharge flow Imin is set to 0.1C (C is the rated capacity of the lithium battery). Constant current charging current is set to 1C, taking into account the influence of the inductor current ripple, set MPPT with constant-current conversion threshold 0.95Imax. ΔT is set to 64ms, Ton / the Toff is less than 1/256 that the battery is fully charged.
Fig. 6 the System simulation model in. Simulink
Figure 7 shows the light intensity, the simulation results shown in Figure 8 (a) as shown. Conversion in Figure 8 (c) can be seen from the charging status when the illumination changes of the 1000s and 2000s, the charger can automatically switch between the constant current with MPPT charge optimization charging current Ibatt of. Pulse charging stage, when the light shines in the 4000s at the drop, the charger continues charging until Ton / the Toff is less than the set value, the battery is full. By amplification of the current waveform in Figure 8 (b) can be seen as the charging time of growth Toff progressively larger process. Voltage Vbatt curve in line with the charging characteristics of lithium batteries, the Apple a1280 Battery is full after the voltage is maintained at 4.2V.
Figure 9 Simulation results when the charger does not have the MPPT function in the same light. Be seen from the graph the charging current when the fall of the 1000s-2000s light was significantly lower than the current 8 (a), the lithium battery voltage increases slowly, resulting in the total charging time of about 400s.
Figure 10 Figure 6 Pulse module with a constant voltage module instead of the simulation results, the minimum detectable current method (less than 0.1C) for charge termination. Into the constant voltage charging phase, the decline of the 4000s at the light charger immediately stop charging, however, the current decline is due to external factors, not the battery is fully charged, the lithium battery voltage quickly decreased.
4 Conclusion
In this paper, the design of solar cell phone lithium battery charger with DC / DC converter topology to achieve the maximum power point tracking, to maximize the efficiency of photovoltaic cells, charge termination judgment, taking into account the light intensity, ambient temperature and other factors on The lithium Canon Bp-2l12 battery charging curve, accurate charge termination judgment, so that the lithium battery rated capacity.
Fig.7 Change of the irradiation
Figure 8 (a) The pulse rechargeable lithium battery voltage, current waveform diagram (b) enlarged map (c) charge state transition diagram
Fig.8 (a) Voltage and current wave of the Li-ion battery in the pulse charge mode (b) local zoom (c) The change of charge state
Fig.9 Voltage and current wave of the Li-ion Acer Aspire 5740 Battery without the MPPT
Fig.10 Voltage and current wave of the Li-ion battery in the CC-CV charge mode
2012-04-13
2012-04-05
UF tight end A.C. Leonard pleads no contest to battery
GAINESVILLE - A judge gave A.C. Leonard, a sophomore tight end on the Florida football team, six months of probation on Wednesday after he pleaded no contest to a charge of compaq presario cq60 battery against his girlfriend.
Leonard’s non-jury trial was supposed to start Wednesday on the misdemeanor count, which stemmed from his arrest in February after police said he shoved his girlfriend, knocking her to the ground and causing her head to hit a dog cage.
State Attorney’s Office spokesman Spencer Mann said Leonard changed his plea from not guilty to no contest and that the judge withheld adjudication, meaning Leonard won’t have a criminal conviction on his record if he completes his probation.
Leonard, 20, whose full name is Alcorus De Vonte Leonard, will also have to pay court fines and costs, complete anger-management counseling and stay away from the victim, Mann said.
Leonard’s attorney, Huntley Johnson, who represents many UF athletes who have been arrested, said in an interview that in making the decision to change pleas, “we took her situation and his situation into consideration,” speaking of Leonard and his girlfriend.
Johnson said the experience had a “positive impact” on his client and that Johnson had noticed a change in his attitude over the last few months.
“I think he’s gotten the message that he needs to fly straight,” Johnson said.
On Feb. 15, Leonard and his girlfriend were arguing at The Polos apartments on Southwest Williston Road. Leonard “shoved her forcibly with both hands in her chest/neck area,” according to a Gainesville Police Department arrest report. “The force of the shove knocked her down to the ground, causing her head to strike a dog cage that was behind her.”
GAINESVILLE - A judge gave A.C. Leonard, a sophomore tight end on the Florida football team, six months of probation on Wednesday after he pleaded no contest to a charge of Acer aspire 5732z battery against his girlfriend.
Leonard’s non-jury trial was supposed to start Wednesday on the misdemeanor count, which stemmed from his arrest in February after police said he shoved his girlfriend, knocking her to the ground and causing her head to hit a dog cage.
State Attorney’s Office spokesman Spencer Mann said Leonard changed his plea from not guilty to no contest and that the judge withheld adjudication, meaning Leonard won’t have a criminal conviction on his record if he completes his probation.
Leonard, 20, whose full name is Alcorus De Vonte Leonard, will also have to pay court fines and costs, complete anger-management counseling and stay away from the victim, Mann said.
Leonard’s attorney, Huntley Johnson, who represents many UF athletes who have been arrested, said in an interview that in making the decision to change pleas, “we took her situation and his situation into consideration,” speaking of Leonard and his girlfriend.
Johnson said the experience had a “positive impact” on his client and that Johnson had noticed a change in his attitude over the last few months.
“I think he’s gotten the message that he needs to fly straight,” Johnson said.
On Feb. 15, Leonard and his girlfriend were arguing at The Polos apartments on Southwest Williston Road. Leonard “shoved her forcibly with both hands in her chest/neck area,” according to a Gainesville Police Department arrest report. “The force of the shove knocked her down to the ground, causing her head to strike a dog cage that was behind her.”
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