Speed control for high power DC brushed motor

Question

I am going to drive and bi-directionally control the speed of some 12V/24V, 100W to 300W DC brushed motors.

I have some experience in controlling small DC motors (6V/9V/12V, 0.5A to 2A) with PWM signal from an Arduino and a L298N dual H-Bridge Shield. However, for the relatively high power DC brushed motors that I am preparing to drive, I have no such experience and am wondering what methods and chips should I use.

PWM is the method of choice when controlling speed for small current motors. Is this still the method of choice for higher power DC brushed motors ?

For 100W to 300W motors, the operating current may be as high as 10A to 25A, and may get even higher if once the motor is stalled. The L298N dual H-Bridge could not be used in such a high current environment. Assuming that the maximum current is below 100A if the motor is stalled, What chips and circuit should I use in these cases ?

Could I use PWM signal to switch a "solid state relay" / "optical coupler" to control the speed of these higher power DC motors ?

How could I handle the case that the motor is overloaded and is stalled, and the current gets much higher to impose danger ?

Answer 1

The "problem" is that you probably have not speed CONTROLLED your small motors, you have probably 'speed altered' them.

If you had no feedback (either tacho of some sort or back emf related) then scaling it up to the kW range is liable to produce interesting but not necessariy useful results. There are MANY DC motor control circuits / pages / papers on web. Any serious ones will have some form of speed feedback. Searching for eg : high power dc motor speed controller : Will produce zillions of hits. Including:

• This facebook page appears to have cpied copyright material from SIlicon Chip - if you use it send them the cost of a magazine.

• This commercial one rated at 50A for $60 here (http://www.canakit.com/50a-dc-pwm-motor-speed-controller.html )

• And a vast range of maybe-relevant images, here .