Power feed-back during controller failure in inverter fed permanent magnet synchronous motor drives with flux weakening

When permanent magnet synchronous motors are operated in the flux weakening region, the internal voltage can be much larger than the DC link voltage. If the switching signals are blocked, the freewheeling diodes act as a rectifier, and the motor will feed power back into the inverter. The magnitude of the feedback power during such controller failure is investigated. Simulations and approximate analyses are used to obtain descriptive and comparative curves. Measurements verify the computer results but also show that nonlinear effects could have significant influence