Hello,
I have written a program that takes a reference signal, and then uses a
proportional control to synthesize a similar signal in a wire coil. I
modulate the duty cycle of the counters of a PCI 6224 card. One counter
goes to the positive side of an H Bridge, and the other to
the negative. I'm getting decent results for reference frequencies of
about a hz, but if I go below that I start seeing more interesting wave
forms (the funkiness appears when the waveform crosses zero). I am
questioning whether adding integral or differential controls are liable
to improve matters given the time dependence of the system, and how to
best apply them if appropriate.
Attached are my program and the results it gives for several
frequencies. Most of the missing VIs are those that record the data to
file. The other is the proportional controller from the PWM Counter
Output example, taking the reference signal as its setpoint. (It also
adds .5 to the duty cycle from the P output. If at the setpoint, I want
the current in the coil to remain constant)
Thanks,
Elliot
