Imagine i want to drive a DC motor with a typical H bridge using the normal PWM techniques. The motor is mounted a short distance away from the controller, and linked by wires. With no additional inductance (other than the parasitic bits) between the bridge outputs and the motor, those wires see a dV/dT equivalent to the switching rise times multiplied by the supply voltage. So, if we switch in say 1us, and we switch 10v, then that's 10MV/sec, and because the waveform is likely to be very "square" we will get a large harmonic content potentially radiating out up to a significantly higher frequency?
So, in order to minimise radiated EMC, installing some small amount of additional inductance on the controller, will tend to round off the voltage waveform and push it towards a more sinusoidal shape, with slower edges, and hence cut the radated energy?
If i followed that inductance by a small amount of capacitance to the H bridge Ground (or supply, or both) then i would provide a local HF return path for current, ie a snubber, say something like a 10Nf cap with a 50 ohm resistor (to prevent high freq oscillation)
Am i wide of the mark here? I'm not worried about cost or efficiency etc. Some basic simulation suggests matching the motors inductance gives the best result?
Any traps "for young players" lurking??