Treadmill Motor power supply PWM verses SCR Pros & Cons ?

Thread Starter

rmartini

Joined Dec 4, 2016
27
Treadmill Motor power supply PWM verses SCR Pros & Cons ?

I have a 90+ VDC treadmill motor and need a power supply controller for it.

I've read just about every thread here in this forum regarding the subject.

It looks like there are 2 basic choices. One being a circuit using PWM and the other a SCR Triac circuit.

I'm sure both will work for my needs but what exactly are the Pro's and Con's of each type of control?

I would be building my own power supply speed control and I see one advantage to the SCR design is that it would be easier to build. Where the PWM design requires more parts and a more complicated circuit design.
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
19,731
The PWM is considered the better choice, this is why they cost more!;)
The SCR type suffers a little from noise at lower RPM's, and control is a little rougher.
In the Picmicro app notes I have used for PWM control, they recommend a minimum of 5khz switch rate, to avoid the 'buzz' issue.
This freq. produces a failry smooth current waveform through the motor which is represented by a mean level saw tooth.
The down side of course is that PWM requires a fairly hefty power supply and large capacitors, increasing the design and cost.
Max.
 
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