Modeling motor control

[Al Skierkiewicz]

Originally Posted by EricVanWyk

That is to say that for a given frequency and duty cycle, there is a minimum average current to establish continuous current control. For a Jaguar, this is a few amps. For a Victor, this is a few hundred.

Erik, can you explain this?

Ether, in the graphs you posted for a locked rotor CIM it appears that the Victor has a distinctive current inductance charge/discharge curve while the Jaguar does not. The inductance charge is much more pronounced in the Jag due it's higher frequency. The charge current rise is very long compared to the pulse width at 15kHz. Using the values R=.090 and L=200uH, the time constant is 2.2msec or full current will only be achieved through the motor in 11 msec.
At 150 Hz and 5% duty cycle that is an ON time pulse width of .33msec so the current will reach 18.35 amps by the end of the pulse for a Victor. At 15kHz and 5% duty cycle that is an ON time pulse width of 3.3usec and the current will only reach 0.199 amps by the end of the pulse for the Jaguar. Neither controller provides a discharge path during the OFF period. It is this phenomena that gives the Jag it's apparent linear response.