A method for controlling the start-up phase of a sensorless permanent magnet synchronous motor, the method including: 1) according to the formula T=K×Iq where T is a torque, K is a coefficient, and Iq is a current on a q-axis of a coordinate system of a motor mathematical model, based on a maximum output torque Tmax of a motor, calculating a maximum current Iq_max on the q-axis, setting the maximum current Iq_max as an upper limit of current on the q-axis, and controlling the motor to run in an open-loop control mode; and 2) when an actual running speed V of the motor reaches a first target speed V_ref1, reducing the maximum current Iq_max to a target current Iq0 on the q-axis corresponding to a target torque T0 set by users, and controlling the motor to run in a closed-loop control mode under the first target speed V_ref1.

A driver unit for an interior permanent magnet motor (IPM) is presented. The driver unit includes sensor electronics configured to sense a phase voltage corresponding to one or more phase terminals of the IPM motor to generate a corresponding phase voltage signal. The driver unit further includes a controller electrically coupled to the sensor electronics and configured to extract one or more triplen harmonics of an order of a ninth harmonic and higher than the ninth harmonic of a fundamental frequency of the phase voltage signal corresponding to the one or more phase terminals. The controller is further configured to determine an angular position of a rotor of the IPM motor based on the extracted one or more triplen harmonics. Related motor assembly and method for controlling the IPM motor are also presented.

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.

A method of starting an integrated starter generator drives a starter generator without using a rotor position sensor to start an engine. The method includes the following steps of: (a) applying a first drive current with a first frequency and a first amplitude to drive the starter generator to reversely rotate in a speed open-loop control mode, and acquiring a first load information according to a drive voltage and the first drive current of the starter generator, (b) confirming whether the first load information meets a heavy load condition, (c) stopping reversely rotating the starter generator when the first load information meets the heavy load condition, and (d) forwardly rotating the starter generator to drive the engine to start.

A power tool includes a housing, a brushless motor received in the housing, a power switch coupled to the housing and actuatable by a user, a controller configured to control power delivery to the motor in response to actuation of the power switch, and an output spindle configured to rotate when the motor is energized. The controller is configured to maintain an amount of current delivered to the motor to be less than or equal to a current limit by turning off or reducing power to the motor for a time period if the current exceeds the current limit and then restarting power delivery to the motor. The time period is greater than the duration of one full current cycle.

A motor driving method includes steps of: at an open loop phase and in response to a motor being operated under a steady-state, calculating an angle difference between an estimation coordinate axis of the motor and an actual coordinate axis by a controller, according to an estimation voltage value, an estimation current value and at least one electrical parameter feedback from the motor and in reference with the estimation coordinate axis of the motor; calculating an actual current value in reference with the actual coordinate axis according to the angle difference by the controller; calculating a load torque estimation value associated with the motor according to the actual current value by the controller; and, in response to the open loop phase being switched to a close loop phase, compensating an output torque of the motor according to the load torque estimation value by the controller.

The present disclosure provides a driving circuit of a fan motor to shorten a start time. The driving circuit drives the fan motor with a sensor. A control logic circuit controls an inverter circuit connected to the fan motor according to a Hall signal that indicates a position of a rotor of the fan motor. When the driving circuit is given an instruction to start a rotation, if the fan motor rotates at a speed lower than a predetermined rotational speed, the drive circuit starts the fan motor by sequentially switching between a second state in which the rotor is fixed at an initial position, a third state in which the fan motor is forcibly and synchronously started, and a fourth state in which the fan motor is Hall-driven.

A motor controller comprises a switch circuit, a driving circuit, and a pulse width modulation circuit. The switch circuit is coupled to a three-phase motor for driving the three-phase motor. The driving circuit generates a plurality of control signals to control the switch circuit. When the three-phase motor is operated in a start state, the motor controller may enable an electric period to be divided into more floating phase time intervals for switching phases, so as to increase the success rate of phase switching. When the three-phase motor is operated in a stable state, the motor controller may enable the electric period to be divided into less floating phase time intervals for switching phases, so as to reduce the noise and vibration of the three-phase motor.

Methods of operating electric motor systems that comprise electric motors comprising a rotor having a magnet mounted thereto. The electric motor is initially operated in an open loop mode in which the rotor angle is estimated based on the input voltage frequency. Once the motor is running at sufficient speed, a transition to closed loop mode operation is performed, wherein the rotor angle is determined using an observed back EMF. To provide a smoother open loop to closed loop transition, the rotor angle is determined during a transition period as a function of both the open loop rotor angle and the closed loop rotor angle.

Methods of operating electric motor systems that comprise electric motors comprising a rotor having a magnet mounted thereto. The electric motor is initially operated in an open loop mode in which the rotor angle is estimated based on the input voltage frequency. Once the motor is running at sufficient speed, a transition to closed loop mode operation is performed, wherein the rotor angle is determined using an observed back EMF. To provide a smoother open loop to closed loop transition, the rotor angle is determined during a transition period as a function of both the open loop rotor angle and the closed loop rotor angle.