Have you noticed that there are many, many suppliers for VFDs and 3-phase motors, but precious few for DC motors?
Indeed.
So why the interest in brushed DC motors?
IF you get an industrial brushed DC motor, such as a Baldor, you will find it far more powerful and far more reliable than you ever thought. Mine is technically rated at 2 - 3 amps, but it cheerfully survived a slight programming error (ahem) while drilling 6 mm holes in 6Al4V titanium. I hit the Stop button when I saw the current meter on the spindle hitting 8 amps. Eh, no worry, that did not hurt the motor. It is big and heavy and has much thermal mass.
I have been using a PWM KBWT-26 from KB for it, but it died recently. The +15 V rail went down to +0.060 V. I emailed KB asking for help, but they were somewhat reluctant to supply any circuitry for debugging. I could buy another one, but I dislike vendors who sell quite old technology with no support.
Alternatives from other American vendors seemed to be very limited, bulky, expensive, and antique. OK, they have existing customers who just want more of the same.
So I searched on ebay, and found the HQ-SXPWM-X PWM driver.
Pick your input voltage (110 or 220, etc) and your output: mine was 0-200 V and 0-8 A off the 220 V version.
It's a small unit with multiple control inputs (0-5V, 0-10V, PWM, potentiometer) in a nice little screened case.
And it IS a PWM unit rather than a noisy SCR job. The SCR units are cheap and versatile, but they put lots of mains-frequency power on the motor, which then runs very noisily. Trashes the bearing in the long run.
Cost: US$60 + US$10 postage. Amazing!
Extra features they don't tell you about: internal 7-segment display showing current and voltage output, or error messages. Adjustable ramp up/down time, etc. Several other adjustments too.
The secret sauce is, I suspect, that it uses a tiny microprocessor as the controller, unlike the extensive analog components on other older devices.
I bought mine from nanma0910 on ebay, and he was quite helpful. Yes, there IS a manual, abeit Chinglish, for it. The manual is 'adequate', but to the point.
Cheers
Roger