Electric motor driving system and method

An electric motor driving system to control driving of a motor that includes multiple windings of two or more phases each having open ends, the electric motor driving system comprising:

• a first inverter connected to a first power supply at a first end of the first inverter to receive a direct current power from the first power supply, the first inverter including at least two switching elements connected to the open ends of the windings at a second end of the first inverter, respectively;
• a second inverter connected to a second power supply at a first end of the second inverter to receive a direct current power from the second power supply, the second inverter including at least two switching elements connected to the open ends of the windings at a second end of the second inverter, respectively;
• and
• a main control unit including:
• a first inverter control circuit to receive a torque instruction from an outside of the electric motor driving system and generate a first voltage instruction based on the torque instruction, the first voltage instruction being output to the first inverter,
• a second inverter control circuit to receive a torque instruction from an outside of the electric motor driving system and generate a second voltage instruction based on the torque instruction, the second voltage instruction being output to the second inverter, and
• an electric power controller included in at least one of the first inverter control circuit and the second inverter control circuit to receive a target electric power instruction from an outside of the electric motor driving system,
• wherein the electric motor system controls a current vector of each of the first and second inverters to be common, the current vector being composed of a current amplitude and a current phase,
• wherein the electric power controller changes voltage vectors of the first and second inverters while maintaining the sum of the voltage vectors and a total electric power generated in the first and second inverters per torque instruction to control sharing of the electric power supplied from the first power supply and the second power supply between the first inverter and the second inverter in accordance with the target electric power instruction,
• wherein one of the first inverter control circuit and the second inverter control circuit including the electric power controller acts as an electric power supervising circuit and the other one of the first inverter control circuit and the second inverter control circuit excluding the electric power controller acts as an electric power non-supervising circuit,
• wherein each of the first inverter control circuit and the second inverter control circuit generates dq-axes voltage instructions based on the torque instruction to respectively control the first and second inverters, and
• wherein the electric power controller included in the inverter control circuit acting as the electric power supervising circuit adjusts only the dq-axes voltage instructions generated in the electric power supervising circuit based on the dq-axes voltage instructions generated in each of the first inverter control circuit and the second inverter control circuit.