The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> PLL Motor Control Design Question
https://designers-guide.org/forum/YaBB.pl?num=1174053121

Message started by elec_eng on Mar 16^th, 2007, 6:52am

Title: PLL Motor Control Design Question
Post by elec_eng on Mar 16^th, 2007, 6:52am

Hi.

I was wondering if anyone could help me.

I need to use the Phase Locked Loop (PLL) technique to control the speed of a DC Motor. I have to use the LM565 chip. The data sheet can be found at http://www.national.com/ds/LM/LM565.pdf . I have attached the circuit confguration i plan to use below.

I will be using the 741 op-amp for the Low Pass Filter.

Is this configuration suitable?

If not, what changes would need to be made.

Any ideas or advice would be really useful.

Thank you for your time.

Title: Re: PLL Motor Control Design Question
Post by Jess Chen on Mar 16^th, 2007, 9:19am

Why are you driving the motor with a VCO? In motor analogies of PLLs, I believe the motor REPLACES the VCO. Also, the way you've configured your system, I think you need to detect shaft angle, not motor speed.

However, if you swap the positions of your VCO and motor, I suppose you could drive the VCO with a signal proportional to the speed of the rotor. The VCO would serve as a gain element.

-Jess

Title: Re: PLL Motor Control Design Question
Post by HFG on Mar 16^th, 2007, 1:55pm

jess is correct, the output of the loop controller (aka loop filter) will drive the motor. If you are using something such as a ac syncro motor then you would use the VCO to generate the motor drive signal.

Title: Re: PLL Motor Control Design Question
Post by elec_eng on Mar 17^th, 2007, 10:15am

Jess Chen wrote on Mar 16^th, 2007, 9:19am:

Thanks, i'll give that a go and see whats happens. 8-)