PWM speed input

Discuss Brushless DC Motor Speed Control Systems or AC Motor Speed Control systems and related Accessories here.
dan300
Posts: 3
Joined: Thu Aug 04, 2016 10:29 am

PWM speed input

Postby dan300 » Thu Aug 04, 2016 10:32 am

Can I use a PWM for speed control on a BLH450KC-A?
PWM frequency is about 8KHz.

om_tech_support_JS
Posts: 149
Joined: Tue May 10, 2016 4:48 pm

Re: PWM speed input

Postby om_tech_support_JS » Fri Aug 19, 2016 12:57 pm

Hi dan300,

The BLH450KC-A is one of our packaged Brushless DC motors which requires a 24 VDC power supply. The motor will need to be connected to the driver (speed controller) in order to operate properly. The BLH450KC-A can have its speed controlled via the internal potentiometer, an external potentiometer (sold separately), or via an external DC input.

dan300
Posts: 3
Joined: Thu Aug 04, 2016 10:29 am

Re: PWM speed input

Postby dan300 » Tue Aug 23, 2016 7:33 am

Yes, understand all of that. My question is whether the DC input can be in the form of a PWM signal of about 8kHz. I have tried it and it seems to function OK. Is there any filtering going on at the speed control input? The PWM is from a microcontroller and is 0 to 5 volts.

om_tech_support_JS
Posts: 149
Joined: Tue May 10, 2016 4:48 pm

Re: PWM speed input

Postby om_tech_support_JS » Tue Aug 23, 2016 1:41 pm

Hi dan300,

The manual requires a 0-5 VDC input from a PLC. Therefore, as long as the signal is stable, then it should work. Unfortunately there is no information on the filter. Is there any specific concerns that you have for the filtering at the input? Also, please be advised that the target speed set by the frequency may differentiate slightly from the achieved output speed of the motor.

dan300
Posts: 3
Joined: Thu Aug 04, 2016 10:29 am

Re: PWM speed input

Postby dan300 » Wed Aug 24, 2016 7:57 am

Respectfully, I think you need to Google PWM (pulse width modulation). I'm not trying to control the speed by frequency change. The frequency of my speed signal input is constant at 8kHz, the duty cycle of the square wave varies to simulate a variable DC voltage.


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