Paper reports the development of a complete loss model for vector controlled low-voltage ac drives, which includes all converter and motor loss components. Using this loss model, an algorithm is implemented to run detailed loss evaluations in the entire constant-torque zone. Four ac drives of 4 kW, 11 kW, 55 kW and 110 kW are evaluated considering switching frequencies of 1 kHz, 2 kHz, 4 kHz and 8 kHz. Results confirm that reducing the switching frequency from 8 kHz to 2 kHz produce interesting power savings, while keeping a low level of harmonic content and a safe operation of the ac drive.