I was doing some research about the Prius inverter for my ECEN 370 class and I found this:
VH boost
Quote:
Interesting things happen in the 30 - 40 MPH region, especially in EV mode.
I know from some other observations that the inverter drive signals for MG2
move from a multiple-kilohertz PWM regime into simply switching 3-phase square
waves at the motor's native electrical rotation speed, because it's more
efficient and the motor is turning fast enough to smooth out any torque ripple
that would produce. But overall applied motor current can still be regulated
smoothly! How? By using a variable boost voltage. In this speed range I see
VH rising and falling corresponding to my go-pedal demand, with its lowest
baseline creeping up a bit as I head toward 40 MPH and MG2's own peak output
rises sufficiently. It's almost like having the switching behave like a
brush commutator, simply leading the electrical rotation angle by 60 or more
degrees, and regulating motor speed via applied voltage like it was a big ol'
toy-train rheostat.
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I find that quite interesting, but then again, I have a big interest in power electronics. And my best friend Allie Moore said that I would be the next Nikola Tesla...