High-performance permanent magnet (PM) motors must be designed with a consideration of the capabilities of the voltage source inverters that will control them. Both motor and drive are operating at the limits of their capabilities and require accurate estimation of expected performance and losses to enable a successful design. The effect of rotor design choices on VSI performance is shown via the modification of the motor d-q equivalent circuits. The inclusion of this coupled effect is shown to be of critical importance in accurately predicting rotor losses during operation.