How to short circuit using PWM

[Alexcampel]

Hi,

I have a requirement to short circuit two terminals of a small generator using PWM signal. My requirement is explained in detail bellow.

1. I have small permanent magnet generator. Max power generation is about 40W. Open cct voltage is about 50V and short circuit current is about 3.5A per winding.
2. Generator has 2 separate windings at 180degree angle
3. I need to short-circuit each winding separately while the generator is running. (two separate circuits short-circuited at same time)
4. Short circuit needed to be achieved via PWM control signal (or analog voltage proportional to PWM duty cycle)
5. PWM frequency should be at least 15kHz. (56kHz preferred) I will use 0 to 100% duty cycle. PWM duty cycle will be updated by my controller at 1kHz rate.

I looked at SSR and their switching frequencies are in the range of 60Hz and too slow for my work.

Using some H-bridge motor driver (L298 like) was looked at. I thought to short circuit motor terminals of the motor driver and connect the motor power source to a winding of my generator. But the problem is when the short occurs, the voltage across winding reach zero. At this point, can the motor driver maintain short circuit?

Please give me possible solutions.

Thanks in advance.

 

[rakeshkatkuri]

Hi,
can you post the schematic of L293D so that i can answer you

 

[Alexcampel]

I dont have specic schematic diagram to do this task. I'm looking for options.

 

[ads-ee]

I dont have specic schematic diagram to do this task. I'm looking for options.

Requests for consultants should be opened in the jobs section.

 

[rakeshkatkuri]

you give your exact requirement with specifications so that i can provide the schematic

 

[Alexcampel]

Specifications are given in my first post. Think it as a black box. I will connect output of my generator to the black box and give PWM signal to black box at frequency of 15kHz. I can supply external power to the box. The box should short circuit two coil termainals from generater at duty cycle of PWM signal.

 

[chuckey]

When your short circuit comes of the windings (current goes from max to min) there will be a very large spike of back EMF. Just something to consider.
Frank