A method for operating switching elements of an inverter of a vehicle that is driven by way of a three-phase synchronous machine. The inverter has a series circuit of switching elements for the phases. When the vehicle brakes, the synchronous machine is used to set a cycle rate for the operation of the switching elements depending on a frequency of AC phase currents of the synchronous machine. The electrical energy provided by the synchronous machine is fed to a DC voltage intermediate circuit. The cycle rate is set according to the frequency of the AC phase currents, such that it corresponds to the frequency of the respective AC phase currents of the synchronous machine. Zero points of the AC phase currents are determined, and the switching elements are operated to set a predefined phase difference between the respective AC phase current and a respectively associated AC phase voltage.

A motor is stably driven under an extremely low temperature. A control unit controls an inverter to extract a pulse-like direct current from a battery, in case where a temperature Temp of the battery is below a predetermined value TH at which a power that can drive a motor is continuously extractable, by cyclically repeating an on-period to extract the direct current that can drive the motor from the battery and an off-period in which, after the on-period, the power is not extracted from the battery until the direct current that can drive the motor becomes extractable from the battery again. The inverter converts, to a phase current, the direct current extracted from the battery in the on-period.

A motor is stably driven under an extremely low temperature. A control unit controls an inverter to extract a pulse-like direct current from a battery, in case where a temperature Temp of the battery is below a predetermined value TH at which a power that can drive a motor is continuously extractable, by cyclically repeating an on-period to extract the direct current that can drive the motor from the battery and an off-period in which, after the on-period, the power is not extracted from the battery until the direct current that can drive the motor becomes extractable from the battery again. The inverter converts, to a phase current, the direct current extracted from the battery in the on-period.

A method for controlling an electric motor is described herein. The method comprises setting a current limit, a speed limit and a torque limit. The method also comprises sensing a DC link current, comparing the sensed DC link current with the current limit and adjusting the torque limit based on the comparison with the current limit to provide an adjusted torque limit. The method also comprises sensing the speed of the electric motor, comparing the speed with the speed limit and further adjusting the adjusted torque limit based on the comparison with the speed limit.

A method for controlling an electric motor is described herein. The method comprises setting a current limit, a speed limit and a torque limit. The method also comprises sensing a DC link current, comparing the sensed DC link current with the current limit and adjusting the torque limit based on the comparison with the current limit to provide an adjusted torque limit. The method also comprises sensing the speed of the electric motor, comparing the speed with the speed limit and further adjusting the adjusted torque limit based on the comparison with the speed limit.

A direct current traction motor control system includes plural motors of with each of the motors configured to be coupled with a different axle of a vehicle and to rotate the axle to propel the vehicle. The motors are coupled with a DC bus and configured to receive DC via the DC bus to power the motors. The system also includes plural switch assemblies with each of the switch assemblies having an H-bridge circuit coupled with a different motor of the motors to control rotation of the motor. The system includes a controller configured to communicate control signals to the switch assemblies to individually control the H-bridge circuits to control one or more of torques output by the motors or rotation directions of the motors.

A method of controlling an electric motor to optimize system efficiency of an electric motor operable in a pulsed mode and a continuous mode is disclosed herein. The method includes receiving a requested torque for the electric motor, calculating a pulsed system efficiency, calculating a continuous system efficiency, and operating the electric motor in the pulsed mode when the pulsed system efficiency is greater than the continuous system efficiency. The pulsed system efficiency is calculated for delivering the requested torque from the electric motor in a plurality of torque pulses greater than the requested torque. The continuous system efficiency is calculated for delivering the requested torque from the electric motor as a continuous torque. The system efficiency may be at least partially based on a battery efficiency and a motor efficiency.

A method of controlling an electric motor to optimize system efficiency of an electric motor operable in a pulsed mode and a continuous mode is disclosed herein. The method includes receiving a requested torque for the electric motor, calculating a pulsed system efficiency, calculating a continuous system efficiency, and operating the electric motor in the pulsed mode when the pulsed system efficiency is greater than the continuous system efficiency. The pulsed system efficiency is calculated for delivering the requested torque from the electric motor in a plurality of torque pulses greater than the requested torque. The continuous system efficiency is calculated for delivering the requested torque from the electric motor as a continuous torque. The system efficiency may be at least partially based on a battery efficiency and a motor efficiency.

An illustrative dual power inverter module includes a detection circuit configured to detect loss of low voltage DC electrical power supplied to a controller for a first power inverter and a second power inverter of a drive unit for an electric vehicle. A first backup power circuit is associated with the first power inverter and a second backup power circuit is associated with the second power inverter. Each backup power circuit is configured to convert high voltage DC electrical power to low voltage DC electrical power responsive to detection of loss of low voltage DC electrical power supplied to the controller. Three-phase short circuitry is configured to apply a same fault action to the first power inverter and the second power inverter responsive to detection of loss of low voltage DC electrical power supplied to the controller, wherein the same fault action includes applying equalized torque to each axle operatively coupled to the drive unit.

An illustrative dual power inverter module includes a detection circuit configured to detect loss of low voltage DC electrical power supplied to a controller for a first power inverter and a second power inverter of a drive unit for an electric vehicle. A first backup power circuit is associated with the first power inverter and a second backup power circuit is associated with the second power inverter. Each backup power circuit is configured to convert high voltage DC electrical power to low voltage DC electrical power responsive to detection of loss of low voltage DC electrical power supplied to the controller. Three-phase short circuitry is configured to apply a same fault action to the first power inverter and the second power inverter responsive to detection of loss of low voltage DC electrical power supplied to the controller, wherein the same fault action includes applying equalized torque to each axle operatively coupled to the drive unit.