Braking algorithm considering voltage limit condition for surface mounted PM synchronous motor

A braking algorithm considering voltage limit condition for a PM synchronous motor at high speeds is presented. The phase resistors of stator windings are used as the braking resistors to dissipate the mechanical energy stored in the rotor. The dq current trajectory for maximum braking torque is analyzed under three constraints, the power limit, the current limit, and the voltage limit conditions. The dq currents available at high speed are restricted by the power limit and voltage limit conditions.