In most of the voltage control loop applications, the input variables to a PI controller are reference voltage and actual voltage and the output is usually a current signal. How the controller converts the difference of two voltage signals to current signal?
Dear Colleagues,
Good Day,
Try and see the attachments, please, they are very useful....
https://www.researchgate.net/post/Why_can_voltage_error_be_converted_to_current_using_a_PID_controller
https://www.allaboutcircuits.com/textbook/semiconductors/chpt-8/voltage-to-current-signal-conversion/
With a current driving power stage.
I mean, if you have a control system,
(1.) You have some error signal pickup, say position signal.
- This can be either voltage or current. In optical disc, eg, error signal is derived
from photocurrents, and they are currents.
- The input signal is translated to voltage (if it was a current) with a transimpedance
amplifier or something else.
(2.) You have a controller
- Can be digital or analog. Nowadays more and more digital. Means
input signal is converted by an A/D convertor to digital, control loop is
executed in digital domain, output signal is converted to analog by means
of an D/A convertor.
- You can also do digital, integrated (I dont think this still exists), or with op-amps,
or whatever.
(3.) You have an output stage.
- Simplest form is class-B power amplifier, (take any power op-amp).
Current drive means the op-amp senses the current through the actuator, and
the feedback is such that the op-amp will equal the current to the input signal.
- You can also have more complicated power stage, eg H-bridge PWM drive.
This has higher efficiency, but I think this is most of the time voltage drive.
Best Regards,
Henri.
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