Hi Driftboat,
A few things to consider:
Heat dissipation:
If you are only pushing 7 amps, MosFets might be more appropriate. You control a MosFet the same way as an IGBT, but the power-dissipation operates differently. An IGBT will have approximately .6 volts across it when ON, whereas a Mosfet will have a voltage based on its ON resistance (ohm's law). So at lower currents, the dissipation in the switch will be lower in a MosFet than in an IGBT, and at higher currents, the dissipation will be lower in an IGBT than in a MosFet. Also, as the current increases, dissipation increases linearly in an IGBT and exponentially in a MosFet.
Radiated noise:
You will get switching noise with any high-power PWM topology. How much you (and your neighbors) can tolerate will dictate many design parameters. You can minimize EMI by switching your drive-stage slower, but that will generate more heat as the switches will spend more time in their linear (unsaturated) region. With PWM, there has always been that heat/noise trade-off. Be prepared to add chokes, for controlling both noise and current-ripple (which will heat the motor), if your motor does not have high-inductance.
Bus voltage:
You do not mention where your single-phase is from. Is it 110 or 220? This will proportionately influence both noise and current-ripple, but will mainly influence cost. Unless I'm designing for 400 volts or more, I stick with 600 volt Mosfets or IGBTs. Of course, the reverse-recovery diodes are important to keep the switching transients from exceeding that voltage. Faster is better, with a current-rating better than your peak motor current. Keeping the transients low in amplitude helps with reducing EMI.
Keep in mind that driving a motor is no trivial task. Be prepared to do multiple iterations of your power circuit.
