A method of determining a position of a rotor of a brushless permanent magnet motor includes measuring phase current flowing through a phase winding of the motor during excitation of the phase winding, and measuring voltage applied to the phase winding of the motor during excitation of the phase winding. The method includes calculating a phase of back EMF induced in the phase winding using the measured phase current and the measured voltage. The method includes determining a zero-crossing point of the back EMF induced in the phase winding using the calculated phase of back EMF induced in the phase winding. The method includes determining an aligned position of the rotor of the brushless permanent magnet motor when the back EMF induced in the phase winding is at the zero-crossing point.

A method of determining a position of a rotor of a brushless permanent magnet motor includes measuring phase current flowing through a phase winding of the motor during excitation of the phase winding, and measuring voltage applied to the phase winding of the motor during excitation of the phase winding. The method includes calculating a phase of back EMF induced in the phase winding using the measured phase current and the measured voltage. The method includes determining a zero-crossing point of the back EMF induced in the phase winding using the calculated phase of back EMF induced in the phase winding. The method includes determining an aligned position of the rotor of the brushless permanent magnet motor when the back EMF induced in the phase winding is at the zero-crossing point.

This present disclosure provides a compressor and a refrigeration device having the compressor. The refrigeration device has a coupling assembly and a frequency converter connected to one end of the coupling assembly. The compressor has a first shell and a permanent magnet motor. The permanent magnet motor is set in the first shell and connected to the other end of the coupling assembly. By designing the relevant parameters of the motor of the compressor, the efficiency of the motor and the compressor can be improved.

This present disclosure provides a compressor and a refrigeration device having the compressor. The refrigeration device has a coupling assembly and a frequency converter connected to one end of the coupling assembly. The compressor has a first shell and a permanent magnet motor. The permanent magnet motor is set in the first shell and connected to the other end of the coupling assembly. By designing the relevant parameters of the motor of the compressor, the efficiency of the motor and the compressor can be improved.

A motor system comprises a motor comprising: a stator with a plurality of subwindings each having a plurality of phase connections for receiving phase voltages, wherein each of the subwindings is electrically insulated from each of the other subwindings; a rotor comprising a plurality of permanent magnets or energisable electromagnets; a controller comprising a plurality of control parts, each control part associated with a respective subwinding, each control part being configured to monitor phase voltages of the associated subwinding, between phase connections. The system further comprises a controller configured to: obtain, from each control part, at set discrete time intervals, a plurality of back measured electromotive force, EMF, readings for each of the respective subwindings; using the plurality of measured back EMF readings and an a priori knowledge of the motor's construction to estimate a commutation event timing.

A motor system comprises a motor comprising: a stator with a plurality of subwindings each having a plurality of phase connections for receiving phase voltages, wherein each of the subwindings is electrically insulated from each of the other subwindings; a rotor comprising a plurality of permanent magnets or energisable electromagnets; a controller comprising a plurality of control parts, each control part associated with a respective subwinding, each control part being configured to monitor phase voltages of the associated subwinding, between phase connections. The system further comprises a controller configured to: obtain, from each control part, at set discrete time intervals, a plurality of back measured electromotive force, EMF, readings for each of the respective subwindings; using the plurality of measured back EMF readings and an a priori knowledge of the motor's construction to estimate a commutation event timing.

Systems and methods described herein provide for controlling a conduction angle applied to a motor, such as a power tool motor. Operations for controlling the conduction angle includes receiving by a motor controller, a desired speed signal, and monitoring a speed of the power tool motor. The operation further includes a motor controller determining an error value between the desired speed signal and the monitored speed and determining a conduction angle signal based on the error value. The operation also includes the motor controller determining whether the conduction angle signal is greater than the error value and increasing a conduction angle of the power tool motor in response to the conduction angle signal being determined to be greater than the error value.

Systems and methods described herein provide for controlling a conduction angle applied to a motor, such as a power tool motor. Operations for controlling the conduction angle includes receiving by a motor controller, a desired speed signal, and monitoring a speed of the power tool motor. The operation further includes a motor controller determining an error value between the desired speed signal and the monitored speed and determining a conduction angle signal based on the error value. The operation also includes the motor controller determining whether the conduction angle signal is greater than the error value and increasing a conduction angle of the power tool motor in response to the conduction angle signal being determined to be greater than the error value.

A method for ascertaining, without an encoder, a rotational angle position of the rotor of a brushless DC motor, includes the steps of: detecting a voltage induced in a stator of the brushless DC motor; checking whether the voltage induced in the stator is lower than a threshold value; and if the induced voltage is lower than the threshold value, then ascertaining an initial rotational angle position of the rotor based on an Indirect Flux detection by Online Reactance Measurement, and subsequently updating the rotational angle position proceeding from the calculated initial rotational angle position using at least one continuous test signal.

A method for ascertaining, without an encoder, a rotational angle position of the rotor of a brushless DC motor, includes the steps of: detecting a voltage induced in a stator of the brushless DC motor; checking whether the voltage induced in the stator is lower than a threshold value; and if the induced voltage is lower than the threshold value, then ascertaining an initial rotational angle position of the rotor based on an Indirect Flux detection by Online Reactance Measurement, and subsequently updating the rotational angle position proceeding from the calculated initial rotational angle position using at least one continuous test signal.