Measuring PWM voltage

Status
Not open for further replies.
G

grrr_arrghh

New Member
Hi.

Using PWM to control a motor has the same affect as lowering the voltage, and I wondered if any one could think of a way of measuring (in the circuit) the 'apparent' voltage - i.e. the voltage that would be needed to make the motor spin at that speed.

Or measure when the duty cycle went beyond a trigger point.

Not for any particular project, just thought process going around in my head.

Cheers,

Tim
 
just measure it with your digital voltmeter, it will give the average voltage
 
oh really? ok, then, but I don't want to know the actual voltage, but I want to measure it with something like an op-amp, to compare the voltage. Would the op-amp measure the average voltage, or would it operate too fast and keep changing?
 
Tim,

Using PWM to control a motor has the same affect as lowering the voltage said:
Actually PWM is much better than lowering the voltage, you get a significantly higher torque from the motor and better control of the rpm.

Ante :roll:
Click to expand...
 

at the expense of torque-ripple.
 
Styx,

I did not say it was perfect (even the sun have spots) only much better, and it is!

Tim,

You can set up the op-amp to measure the average voltage if needed.

Ante :roll:
 
ante said:
Styx,

I did not say it was perfect (even the sun have spots) only much better, and it is!

Tim,

You can set up the op-amp to measure the average voltage if needed.

Ante :roll:
Click to expand...

and i didn't say PWM was bad. In fact it is very good. Only way to control anything with real power and due to it has cause Sycronous machine to start making headway into what was Induction machine areas (nasty things)
 


what you want to do is use a low-pass filter to average out what teh voltage is. You will need to buffer the PWM signal first to stop the low-pass filters imedance messing with the PWM. The cutoff freq of yr low-pass will be based upon what your switching-freq is
 
Status
Not open for further replies.

Similar threads

V
  • Question
Logging Voltage
2
Replies
22
Views
2K
Voltmanbucks
V
  • Question
No contact AC voltage sensing
Replies
15
Views
2K
lilimike
G
  • Question
Voltage follower with feedback resistor?
2
Replies
32
Views
4K
Diver300
D
  • Question
Cable for RF (high voltage) instrument
Replies
1
Views
793
rjenkinsgb
G
  • Question
A/D converter reference voltage on negative terminal
Replies
19
Views
1K
gjoo
G
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…