I'd like to experiment with SPWM, as used in motor control applications. But instead of modulating the duty cycle with a single frequency, I'd like to use a mix of frequencies.
I've been searching for a examples of this and a place to start, but I haven't been able to find any. In fact, I'm not even sure what terminology to use. Internet searches presented me with many examples which use the PWM output of a microcontroller, but I think they wouldn't have the power needed to create a mixed signal. A DSP chip like the Microchip dspic33 series seems like a good possibility, but that would present me with a steep learning curve of learning DSP programming.
I think the place I would like to start is generating the signal in analog form and then converting that to SPWM. It would kind of be like an FM signal generator, where the input signal modulates the frequency of the carrier, but in my case it would be the duty cycle of a square wave. But...I can't find any examples of that to study, and I don't even know if that's possible or if anyone has done it.
Does anyone have any thoughts on this, or can point me to some examples? Would my analog-first idea even work, or is DSP the way to go? Or are there other ways?