Using h-bridge to regulate battery voltage

I have some 12 volt motors and want to run them off a battery that when fully charged is higher than 12V. In the past I’ve used a voltage regulator to drop the battery volts to whatever the motors need and then used PWM to control the speed such that the motors run at full speed when the PWM duty cycle gets to 100%

Now I’m thinking to skip the voltage regulator. Let’s say the battery is 16 volts. As long as I limit the PWM duty cycle to 75% I should be good. I could have software monitor the battery voltage and compute the limiting PWM output. So in effect I’m using an H-bridge as both a motor control and a battery voltage regulator.

Anyone see a problem (other than a software bug could fry the motor.)

Why? Reduce hardware parts count and complexity. Also regulators are maybe 85% efficient so I hope to recover some of that 15% wasted power.


Your plan sounds fine to me. Since your motor is an inductive load, it will smooth out the applied PWM voltage, so limiting the duty cycle of your PWM signal will effectively limit the voltage the motor sees.

- Grant