I'm trying to get an h bridge circuit working using PWM and a dsPIC33F. This is an existing design, which I am trying to get working using a different approach.
In the schematic, you can see PWM1H and PWM2L are driving the top half bridge. PWM2H and PWM1L are driving the bottom half.
I modified this circuit so that PWM1H and PWM1L are driving the top half and PWM2H and PWM2L are driving the bottom half. I am trying to use a complementary PWM signal with some dead time.
I'm using a dead time of around 1.7us. When I test the circuit with a low frequency of 20Hz, it seems to work, and I can get a voltage of 12V on the output with 50% duty cycle. However, I want to use a higher frequency so the output is not as choppy. I tried using 20kHz, but my current limit on my power supply keeps triggering, so I think something is shorting (current limit set to 250mA).
I tried increasing the dead time even further but it still did not help. I also noticed that the voltage at TP13 (gate drive voltage) was quite distorted at high frequencies, but normal at low frequencies.
I can't seem to figure out what's going on. Does anyone have advice for this?
Thanks.
In the schematic, you can see PWM1H and PWM2L are driving the top half bridge. PWM2H and PWM1L are driving the bottom half.
I modified this circuit so that PWM1H and PWM1L are driving the top half and PWM2H and PWM2L are driving the bottom half. I am trying to use a complementary PWM signal with some dead time.
I'm using a dead time of around 1.7us. When I test the circuit with a low frequency of 20Hz, it seems to work, and I can get a voltage of 12V on the output with 50% duty cycle. However, I want to use a higher frequency so the output is not as choppy. I tried using 20kHz, but my current limit on my power supply keeps triggering, so I think something is shorting (current limit set to 250mA).
I tried increasing the dead time even further but it still did not help. I also noticed that the voltage at TP13 (gate drive voltage) was quite distorted at high frequencies, but normal at low frequencies.
I can't seem to figure out what's going on. Does anyone have advice for this?
Thanks.
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