A method for estimating a magnet temperature of a rotor magnet within a rotary electric machine includes, while a rotor of the electric machine is stationary, injecting a high-frequency voltage component onto a control voltage of the electric machine, via a controller, to generate an adjusted voltage command, and extracting a high-frequency component of a resulting current as an extracted high-frequency component. The method also includes calculating an inductance value of the electric machine using the extracted high-frequency component of the resulting current. The magnet temperature is estimated using the calculated inductance value and an angular position of the rotor. The method includes controlling an operation of the electric machine using the estimated magnet temperature. An electric powertrain uses the electric machine and controller noted above.

A control device for controlling a rotary electric machine, the control device includes a current command unit, a voltage conversion device, a current conversion device, a signal demodulation device, an error compensation unit, an adding device and a position estimation device. The current command unit provides a d-axis current command and a q-axis current command. The current conversion device converts a current of the rotary electric machine to a synchronous reference coordinate current. The signal demodulation device computes a current variation of a high-frequency synchronous reference coordinate current. The error compensation device outputs a first correction value. The adding device adds the current variation of the high-frequency synchronous reference coordinate current and the first correction value to generate a second correction value. Based on the second correction value, the position estimation device adjusts a phase estimation value for the current conversion device and the voltage conversion device.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to apply a drive signal to the power switch circuit to control the supply of power to the brushless motor. The controller is configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor within a variable speed range of zero to at least 15,000 rotations-per-minute (RPM), and control the drive signal based on the detected angular position of the rotor to electronically commutate the motor within a torque range of zero to at least 15 newton-meters (N.m.) and a power output of zero to at least 1500 watts.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. The controller detects an initial sector within which the rotor is located at start-up, apply the drive signal so as to rotate the motor to a parking angle associated with the detected initial sector, and control a commutation sequence to drive the motor beginning at the parking angle.

A power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. If the supply of power to the motor is turned OFF to cause the motor to slow down and is turned back ON while the rotor speed exceeds a speed threshold, the controller electronically brakes the motor for a time interval to measure the phase current of the motor and detects the angular position of the rotor based on the measured phase current.

An inverter control apparatus and a motor drive system includes an inverter main circuit that drives a synchronous motor; an electric-current detector that detects an electric current flowing between the inverter main circuit and the synchronous motor; a command generator that generates an electric-current command value of an output electric current that is output from the inverter main circuit to the synchronous motor, in accordance with a torque command that is supplied externally; and an electric-current controller that generates a voltage command value for the inverter main circuit so that the electric-current command value and a detected electric-current value detected in the electric-current detector are equal to each other. The command generator generates the electric-current command value so that a fundamental wave current that is equal to or greater than a threshold is supplied to the synchronous motor, in driving the inverter main circuit.

A robust starting system and method for an interior permanent magnet synchronous motor, suitable for commercial fan and blower drive applications. A comprehensive starting control process is provided that utilizes control flags to implement closed-loop control accounting for any pre-existing rotor movement, controlling the motor speed from an initial speed to a destination speed. A universal dqController provides selective configurability for collecting information regarding the initial state of the motor, as well as starting and operational motor control. Dynamic high frequency injection enables the use of HFI outside the normal standstill motor speeds by intelligently decoupling the high frequency and rotor movement portions of the stator current response.

The invention relates to a control system and to a method for operating a synchronous machine. In particular, the synchronous machine is controlled on the basis of a rotor angle that was determined by means of a sensorless rotor-angle detection method. In order to check the reliability of the rotor angle determined without sensors, the difference value between the rotor inductances in the q direction and in the d direction is monitored. If said difference value falls below a limit value, this indicates possible instabilities in the determination of the rotor angle.

In one aspect, a system for determining an initial angular position of a rotor of a synchronous machine includes a motor driver module configured to provide a motor driver voltage signal to the synchronous machine, the motor driver voltage signal being sufficient to induce an electrical current in the synchronous machine; and a rotor position determination module configured to receive an indication of the current generated in the machine and to determine the initial position of the rotor based on the indication of the current generated in the machine. The motor driver voltage signal includes at least a first portion, a second portion, and a third portion, the first portion has a first non-zero voltage during a first temporal duration, the second portion has a second non-zero voltage during a second temporal duration, and the third portion has a substantially zero voltage during a third temporal duration, the first portion has a first polarity and the second portion has a second polarity that is opposite to the first polarity, and the first temporal duration and the second temporal duration are different.

A system and method for robust control of a sensorless interior permanent magnet synchronous motor. The system and method includes rotor characteristic detection to detect or estimate rotor position, rotor speed, and rotor magnetic polarity based on rotor magnetic anisotropy or saliency. Detecting rotor magnetic polarity allows determination of orientation of the rotor and, for a rotor in motion, direction of travel. A high frequency injection enables rotor position detection and an alternating carrier method enables detection of rotor magnetic polarity. The system and method can also include closed loop startup control from a standstill condition following detection of rotor characteristics.