Electric motor drive system and winding switching method

An electric motor drive system comprising:

• an electric motor including windings of a plurality of phases, each winding for a separate one of the plurality of phases including a center tap, a winding start terminal, a winding end terminal, a winding used for a low-speed rotation located between the center tap and the winding start terminal, and a winding used for a high-speed rotation located between the center tap and the winding end terminal;
• an inverter configured to supply an inverter electric current with a variable frequency to the winding of each phase of the electric motor;
• a first winding switch portion configured to open and close connection between the inverter and the winding start terminal of the winding of each phase, and a second winding switch portion configured to open and close connection between the inverter and the center tap of the winding of each phase;
• and
• a controller configured or programmed to control opening and closing of each of the first and second winding switch portions;
• wherein
• the controller is configured or programmed to include a mode in which the second winding switch portion is caused to shift from an open state to a closed state before the first winding switch portion is caused to shift from the closed state to the open state.