Hi Jason, At high frequencies and <<50% duty cycle, yes, the ON/Hi-Z cycle will avera= ge 0 volts. It depends on duty cycle, your PWM frequency and the motor inductance. The motor is an imperfect inductor. But generally what you say is entirely accurate. Friendly regards, Bob ________________________________________ From: piclist-bounces@mit.edu on behalf of Jason = White=20 Sent: Tuesday, July 3, 2018 12:48 PM To: Microcontroller discussion list - Public. Subject: [EE] DC Motor PWM, Average Voltage? Hello PICList! I am currently design my first piece of avionics hardware. For my application I am driving a DC motor with an H-Bridge. I aim to (very loosely) regulate the average voltage supplied to the motor to 20V over a supply voltage of 20V to 40V using open-loop PWM. I would like to know if my thinking is correct. The H-Bridge contains two "Off" states: High impedance and braking. With a 40V supply: If I PWM the H-Bridge between "on" and high impedance at a 50% duty cycle the average voltage will not be 20V because of the back emf of the DC motor. Instead to achieve an average of 20V with a 50% duty cycle the H-Bridge must be toggled between "on" and braking. This will eliminate the effect of back-EMF on the average applied motor voltage. Correct thinking? Thanks, Jason White --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .