Design PWM to cope with supercapacitor and battery(help)

In summary, the conversation discusses the need to design an electric circuit that uses PWM to alternate between the battery and supercapacitor to supply current to the loads. The circuit goes through three stages, with the supercapacitor and battery taking turns supplying current as their voltages change. The conversation also mentions a problem with the switch and PWM not functioning properly, and the suggestion of using comparators instead.
  • #1
shanver
4
0
I need to design an electric circuit which require PWM to let the battery and supercapacitor take turn to supply current to the loads.

stage1: battery charge up supercap and supply current to the load

stage2: supercap voltage increase to a certain level, battery current is cut, supercap supply current to the loads

stage3: voltage of supercap decrease to certain level, again, battery supply current to load and supercap.
http://www.freeimagehosting.net/3eguo

image http://www.freeimagehosting.net/3eguo

my pwm and switch is not functioning well,
the positive input signal undergoes damping oscillation
and the switch (nmos) does not switch off as Vs>Vg

can anyone help me in this project? I will provide any information if require to..
 
Last edited:
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  • #2
http://img43.imageshack.us/img43/8094/projecto.png

here is the problem circuits
 
Last edited by a moderator:
  • #3
shanver said:
I need to design an electric circuit which require PWM to let the battery and supercapacitor take turn to supply current to the loads.

stage1: battery charge up supercap and supply current to the load

stage2: supercap voltage increase to a certain level, battery current is cut, supercap supply current to the loads

stage3: voltage of supercap decrease to certain level, again, battery supply current to load and supercap.
http://www.freeimagehosting.net/3eguo

image http://www.freeimagehosting.net/3eguo

my pwm and switch is not functioning well,
the positive input signal undergoes damping oscillation
and the switch (nmos) does not switch off as Vs>Vg

can anyone help me in this project? I will provide any information if require to..

shanver said:
http://img43.imageshack.us/img43/8094/projecto.png

here is the problem circuits

You mention using an nmos FET, but your schematic shows a pmos FET...
 
Last edited by a moderator:
  • #4
berkeman said:
You mention using an nmos FET, but your schematic shows a pmos FET...

thank for correcting , should be nmos as in schematic,
it would be fine for pmos/nmos as long as 1 of them are functioning
 
  • #5
I'm thinking of replacing pwm to comparators.. any suggestion?
 

1. How do I design a PWM (Pulse Width Modulation) system to work with both a supercapacitor and a battery?

To design a PWM system for a supercapacitor and battery, you will need to determine the appropriate duty cycle and frequency for the PWM signal. This can be done by considering the voltage and current characteristics of both the supercapacitor and battery, as well as the load requirements. You will also need to ensure that the PWM system is able to switch between the two power sources seamlessly and efficiently.

2. Can I use the same PWM design for both the supercapacitor and battery?

It is possible to use the same PWM design for both the supercapacitor and battery, but it may not be the most optimal solution. Since the characteristics of these two power sources differ, it is recommended to design a PWM system that can adapt to the specific needs of each source. This will ensure maximum efficiency and performance.

3. How do I determine the appropriate duty cycle for the PWM signal?

The duty cycle of the PWM signal can be determined by considering the voltage and current requirements of the load, as well as the voltage and current characteristics of the supercapacitor and battery. A higher duty cycle will result in a longer ON time for the PWM signal, providing more power to the load. However, it is important to ensure that the duty cycle does not exceed the capabilities of the supercapacitor or battery.

4. What is the role of PWM in a system with a supercapacitor and battery?

PWM is used in this type of system to control the amount of power that is delivered to the load. By adjusting the duty cycle and frequency of the PWM signal, the system can efficiently switch between the supercapacitor and battery to provide the necessary power to the load. This helps to extend the lifespan of the supercapacitor and battery, as well as improve the overall performance of the system.

5. Are there any special considerations when designing a PWM system for a supercapacitor and battery?

Yes, there are a few things to keep in mind when designing a PWM system for a supercapacitor and battery. These include selecting the appropriate components, optimizing the duty cycle and frequency, and ensuring that the system can handle the switching between the two power sources. It is also important to consider the cooling requirements, as supercapacitors can generate a lot of heat during charging and discharging.

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