A method of controlling an electric motor includes pulsing the electric motor and phase shifting the modulation frequency. Pulsing the electric motor at the modulation frequency propels a vehicle to increase efficiency of the electric motor. Phase shifting the modulation frequency includes phase shifting between 0 degrees and 180 degrees to reduce vibrations induced in the vehicle.

A diagnostic system for an inverter module includes a motor control module configured to determine operating characteristics of the inverter module. The operating characteristics include of at least one of a voltage, a current, and a switching frequency associated with operation of the inverter module. A diagnostic module is configured to receive the operating characteristics of the inverter module, estimate at least one junction temperature of a component of the inverter module based on the operating characteristics, calculate a health indicator of the inverter module based on the estimated junction temperature, and selectively output an alert based on the calculated health indicator.

A control circuit for a motor of a compressor includes an inverter control module configured to control power switching devices of an inverter to generate output voltages from a DC power supply. The output voltages are applied to windings of the motor. A current control module is configured to generate voltage signals based on a torque demand. The inverter control module controls the power switching devices according to the voltage signals. A selector is configured to output one of an open loop torque value and a closed loop torque value as the torque demand. An open loop torque module is configured to generate the open loop torque value. The open loop torque module is configured to apply an upper limit to the open loop torque value. The upper limit is based on a voltage of the DC power supply.

A method to reduce acoustic noise in a cooling fan motor is disclosed. The method includes reducing the slew rate of a PWM (pulse width modulation) voltage waveform applied to energize a coil of the fan motor. This slew rate reduction results in lower mechanical vibrations and acoustic noise in the fan motor. In one embodiment, the slew rate reduction is performed during startup of the fan motor, when the motor is spinning slowly and there is little air flow noise. In another embodiment, the slew rate reduction is not performed during high speed operation of the fan motor, when the fan motor is spinning very fast and air flow noise masks the motor noise. In one embodiment, there is variable slew rate control depending on the speed of the fan motor.

A voltage saturation prevention algorithm used as at least part of a method of controlling an electric vehicle, wherein the electric vehicle comprises an electric motor, a controller, and an inverter. The controller receives a control signal with an instruction to operate the electric motor, then sends a switching signal corresponding to the control signal to the inverter, wherein the inverter provides a plurality of output signals for operation of the electric motor. The method includes determining the expected amplitude of the plurality of output signals based on the instruction to operate the electric motor, calculating the amount of modification of the plurality of output signals required to prevent the expected amplitude from reaching a saturation value, and modifying, based on the calculation, the instruction to operate the electric motor to prevent the expected amplitude from reaching the saturation value. The method is implemented in software, without any additional hardware.

A power tool includes a multi-phase BLDC motor, a plurality of switches, an input unit, and a controller. For each phase, the controller operates to vary power output to the motor between a first power and a second power by varying a duty cycle of a PWM signal from 0% to 100% while keeping a conduction band (CB) of corresponding motor switches and/or an advance angle (AA) at a predetermined value when the input unit moves between a first position and a predetermined position between the first and a second position. For each phase, the controller operates to increase the power output by the motor to greater than the second power by increasing the CB/AA to greater than the predetermined value while keeping the duty cycle of the PWM signal at 100% when the input unit moves between the predetermined position and the second position.

An electrical motor controller changes the PWM frequency that is used by a motor driver to form the fundamental frequency and voltage magnitude for the electrical power delivered to an electrical motor. The electrical motor controller compares a signal generated by a first sensor that indicates an output speed of the motor to a predetermined speed threshold and compares a signal generated by a second sensor that corresponds to phase currents in the electrical motor to a predetermined motor power threshold. These comparisons are used to set the PWM frequency for the motor driver. The PWM frequency either corresponds to a frequency in a humanly imperceptible audio range or to a frequency that is in a humanly perceptible audio range.

A motor control system includes: a voltage command module configured to determine a target d-axis voltage for an electric motor and a target q-axis voltage for the electric motor; a target frequency module configured to: selectively set a target switching frequency to a first predetermined switching frequency; and selectively set the target switching frequency to a second predetermined switching frequency that is at least 2 kilohertz (kHz) greater than the first predetermined switching frequency; and a switching module configured to: based on the target d-axis voltage and the target q-axis voltage, determine target pulse width modulation (PWM) duty cycles for phases, respectively, of the electric motor; and switch switches of legs of an inverter module connected to the phases of the electric motor at the target PWM duty cycles, respectively, and the target switching frequency.

A motor control method for controlling a motor by using an applied AC voltage converted from a DC voltage with an inverter driven by a PWM control, the motor control method includes: calculating a voltage command value for the inverter in order to achieve a desired torque output in the motor; calculating a compensation gain configured to maintain a linear relation between the voltage command value and the applied AC voltage according to a modulation factor indicating a ratio of the applied AC voltage to the DC voltage before and after a conversion in the inverter; limiting the compensation gain using an upper limit value; calculating a compensation voltage command value by multiplying the voltage command value by the limited compensation gain; and applying the applied AC voltage to the motor by driving the inverter using the compensation voltage command value; wherein the upper limit value is set so that the upper limit value become smaller when the modulation factor changes significantly.

In some examples, a rotary electric machine includes a stator having a plurality of stator coils arranged in a circular pattern around a central opening configured for receiving a rotor. The rotary electric machine further includes a respective dedicated inverter circuit associated with each respective stator coil. For instance, each respective inverter circuit may be configured to convert direct current power to alternating current power to provide to the respective stator coil.