Pulsed control of electric motors, and more particularly, to selectively adjusting one or more of a pulsing frequency, an amplitude of the pulses and/or a duty cycle of the pulses for reducing Noise, Vibration and Harshness (NVH) while maintaining high levels of operating efficiency.

Control of an AC motor includes rotation over an operating speed range with the output from an inverter by operating the inverter at switching frequencies that vary in proportion to rotor speed. The operating speed range is parsed into a plurality of speed regions and the switching frequencies within each operating speed region may correspond to a respective pulse ratio that is different from the respective pulse ratio corresponding to an adjacent speed region.

A variety of methods, controllers, and electric machine systems are described that facilitate pulsed control of multiple electric machines (e.g., electric motors and generators) to improve the machine's energy conversion efficiency. Under selected operating conditions, the electric machine is intermittently driven (pulsed). The pulsed operation causes the output of the electric machine to alternate between a first output level and a second output level that is lower than the first output level. The output levels are selected such that at least one of the electric machines and a system that includes the electric machine has a higher energy conversion efficiency during the pulsed operation than the electric machine would have when operated at a third output level that would be required to drive the electric machine in a continuous manner to deliver the desired output. In some embodiments, the second output level is zero torque.

A motor driving control method for controlling a motor speed so that a speed measured value of a motor follows a speed command value is provided. The method includes driving the motor by repeating an on section where a torque is generated in the motor and an off section where a torque is not generated in the motor at a regular period, based on the speed command value, wherein the driving includes applying a phase voltage to only one of multiple phases of the motor in the on section by a pulse width modulation scheme.

A motor driving control method for controlling a motor speed so that a speed measured value of a motor follows a speed command value is provided. The method includes driving the motor by repeating an on section where a torque is generated in the motor and an off section where a torque is not generated in the motor at a regular period, based on the speed command value, wherein the driving includes applying a phase voltage to only one of multiple phases of the motor in the on section by a pulse width modulation scheme.

Modulated pulse control of electric machines to deliver a desired output in a more energy efficient manner by either (a) operating the electric machine in a continuous mode when a requested torque demand is greater than the peak efficiency torque of the electric machine or (b) in a pulsed modulation mode when the requested torque demand is less than the peak efficiency torque of the electric machine. When operating in the pulsed modulation mode, the inverter may be deactivated to further improve the system efficiency when field weakening is not required to mitigate or eliminate generation of a retarding torque in situations when Back Electromagnetic Force (BEMF) exceeds a supply voltage for the inverter of the machine.

Modulated pulse control of electric machines to deliver a desired output in a more energy efficient manner by either (a) operating the electric machine in a continuous mode when a requested torque demand is greater than the peak efficiency torque of the electric machine or (b) in a pulsed modulation mode when the requested torque demand is less than the peak efficiency torque of the electric machine. When operating in the pulsed modulation mode, the inverter may be deactivated to further improve the system efficiency when field weakening is not required to mitigate or eliminate generation of a retarding torque in situations when Back Electromagnetic Force (BEMF) exceeds a supply voltage for the inverter of the machine.

A random value integration unit 175 outputs a random value output from a random value generation unit 174 in a diffusion width Rand output from a diffusion width generation unit 173 by a product of an output of the random value generation unit 174 and an output of the diffusion width generation unit 173. A triangular wave signal generation unit 176 generates a triangular wave signal corresponding to a second carrier frequency fc2 which is obtained by adding the random value output from the random value integration unit 175 to a first carrier frequency fc1 which is an output of a carrier frequency setting unit 171. That is, a frequency obtained by increasing the diffusion width of the first carrier frequency fc1 is used as the second carrier frequency fc2, and the second carrier frequency is used as the carrier frequency.

A system for managing motor torque in a vehicle determines a stall metric corresponding to motor speed and determines a torque limit based on the stall metric. The system determines a desired torque value, and determines whether to generate a modification to one or more baseline torque commands based on the desired torque value and the torque limit. If the baseline torque command is not to be modified, the system generates the one or more baseline torque commands corresponding to one or more motors. If the baseline torque is to be modified, the system generates one or more modified torque commands corresponding to the one or more motors based on the modification and on the one or more baseline torque commands. The modified torque command may include a minimum value that is less than the torque limit and a maximum value that corresponds to a wheel slip torque.

A system for managing motor torque in a vehicle determines a stall metric corresponding to motor speed and determines a torque limit based on the stall metric. The system determines a desired torque value, and determines whether to generate a modification to one or more baseline torque commands based on the desired torque value and the torque limit. If the baseline torque command is not to be modified, the system generates the one or more baseline torque commands corresponding to one or more motors. If the baseline torque is to be modified, the system generates one or more modified torque commands corresponding to the one or more motors based on the modification and on the one or more baseline torque commands. The modified torque command may include a minimum value that is less than the torque limit and a maximum value that corresponds to a wheel slip torque.