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role of inductor in dc motor

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aishamaryum

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hi
I am using PWM to control hbridge which ultimately drives the dc motor. What will happen when PWM switches off.
Inductor resists change in current.
Does inductor forces the current of dc motor to zero?
I will appreciate if u explain it with current wave forms of motor.
Thanks in advance
 

When you switch off H Bridge, current in inductors starts to delay in reverse direction. Thats why you see those reverse clamped diode to prevent MOSFET reverse breakdown.

Forgot to mention role of inductor is to create magnetic flux to rotate the rotor not to decay current!!
 
You get a triangular curent waveform. di/dt respectively current ripple depends on the inductance. With high inductance values, yuo get effectively constant DC current.
 
what will happen to the waveform of inductor current when we drive dc motor in net negative direction.
 

It can be expected to change polarity at times, but still keeps the triangular shape. Connsider, that the current of a DC
motor basically represents the torque, not the speed. So current and motor voltage can have opposite polarity, during
brake and generatoric operation.

If you have difficulties to imagine the current waveforms for different operation conditions or to visualize them by
pencil-and-paper method, you can use a free circuit simulator to simulate a H bridge.
 

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