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I'm a student and I'm attempting to study how to use two different PWM signals to continuously drive and brake a brushed 12 V motor from an microcontroller.

First frequency will be around 4 kHz (for drive, red) and the second will be ten times the first, so around 40 kHz (for brake, green).

My idea is braking during low (or zero) side of the main power signal, using a NOR or NAND gate to make sure you don't destroy the two MOSFETs

Also, motor need to spin in only one direction, so there is no request for a full bridge.

Is this possible? I read around about Locking Anti-Phase, but it doesn't seems like my idea.

  • \$\begingroup\$ Why use PWM for brake? \$\endgroup\$
    – Andy aka
    Aug 30, 2021 at 15:05
  • 2
    \$\begingroup\$ Welcome to the site. Can you post some drawings of your idea, please? \$\endgroup\$
    – jay
    Aug 30, 2021 at 15:05
  • \$\begingroup\$ I want to use PWM for brake to modulate braking force \$\endgroup\$
    – Papuan
    Aug 30, 2021 at 15:14
  • \$\begingroup\$ Place a TR, IGBT, or FET across the motor. Drive it using "/PWM_4K and PWM_40K". That will short-circuit the BEMF, effectively brakes. \$\endgroup\$
    – jay
    Aug 30, 2021 at 15:43
  • \$\begingroup\$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. \$\endgroup\$
    – Community Bot
    Aug 30, 2021 at 18:50

1 Answer 1



simulate this circuit – Schematic created using CircuitLab

$$V_m= D_{M_1}\cdot V_{bat}=(1-D_{M_2})\cdot V_{bat}$$ $$V_m= I_a\cdot R_a + \dfrac{dI_a}{dt}L_a + E_a$$

M1 and M2 are synchronous switching, i.e when the one turns ON, the other turns OFF. D is the duty ratio of the upper switch M1, while 1-D is the duty ratio of the lower switch M2.

If the motor BEMF voltage Ea is lower than applied motor voltage, then it is motor mode. If the motor BEMF voltage Ea is higher than applied voltage Vm, then it becomes a generator - regenerative braking.


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