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I want to design a circuit to dissipate the reverse energy from BLDC motor, can I use PWM control technique in voltage sense circuit in order to switch on the power circuit?

In detail : In my application the motor is operating at 48 V , during deceleration the voltage rises to 52-55 V, this change in voltage has to be sensed by voltage sense circuit and it has to generate the pulse to activate the power circuit. ( The power circuit consist of N-channel Power Mosfet and braking resistor).

Without the help of any external circuit how can I generate PWM pulses from voltage sense circuit? Can I use SG3525 IC for this?

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  • \$\begingroup\$ Very broad, and very open question. Yes, you can use PWM to control regenerative braking. As for the component you're talking about, it might be OK, but depends on the power, voltage, current and application of your system. In short: we need more information. \$\endgroup\$ – Puffafish Apr 4 at 9:23
  • \$\begingroup\$ @Puffafish , Thanks for the reply, I have posted my question in detail, please check once. \$\endgroup\$ – Pavan Kumar Apr 4 at 9:45
  • \$\begingroup\$ Why PWM? You can use a comparator with hysteresis. Also a voltage rise from 48V to 55V isn't such high to require a braking resistor, IMO. \$\endgroup\$ – Marko Buršič Apr 4 at 9:53
  • \$\begingroup\$ @Marko .. Earlier I have used the comparator ( LM324N) with hysteresis for the same applicaion. As the duty cycle is high in my application I would like to use PWM control technique for efficient operation. Can you please suggest is it right ?\ \$\endgroup\$ – Pavan Kumar Apr 4 at 10:12
  • \$\begingroup\$ What benefit you get using PWM? What is the duty cycle of the braking MOSFET then? If you put enough small resistor with MOSFET + comparator you get the best result - if the DC link voltage is above ON threshold then MOSFET conducts, when the DC link voltage falls below OFF threshold the MOSFET stops conducting. Can't be faster than that. \$\endgroup\$ – Marko Buršič Apr 4 at 10:17

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