Abstract: To avoid control failure resulting from startup of a PMSM that is windmilling, initial speed and position are determined before startup. A controller uses a FOC routine having a speed PI control loop, field-weaken control, a current PI control loop, and a speed observer. When the controller receives an instruction to start the PMSM, it delays startup and executes an “estimation” stage, in which the controller executes the FOC routine but with the speed PI control loop and the field-weaken control disabled. The estimation stage is repeated multiple times, with estimates converging to actual speed and position through successive iterations. When estimated speed and position values have stabilized, the motor is started using the estimates as initial speed and position for driving the PMSM. The FOC routine, with the speed PI control loop and the field-weaken control enabled, is used to drive the PMSM.

Abstract: To avoid control failure resulting from startup of a PMSM that is windmilling, initial speed and position are determined before startup. A controller uses a FOC routine having a speed PI control loop, field-weaken control, a current PI control loop, and a speed observer. When the controller receives an instruction to start the PMSM, it delays startup and executes an “estimation” stage, in which the controller executes the FOC routine but with the speed PI control loop and the field-weaken control disabled. The estimation stage is repeated multiple times, with estimates converging to actual speed and position through successive iterations. When estimated speed and position values have stabilized, the motor is started using the estimates as initial speed and position for driving the PMSM. The FOC routine, with the speed PI control loop and the field-weaken control enabled, is used to drive the PMSM.

Abstract: The method and circuit for controlling a sensorless single-phase BLDCM having a stator with a winding are proposed. The provided controlling circuit includes a power supply circuit, an inverter coupled to the winding and the power supply circuit, a BEMF detecting circuit coupled to the winding and the inverter and measuring a BEMF of the winding, and a controller coupled to the power supply circuit, the inverter and the BEMF detecting circuit and analyzing a status of the BEMF to control the BLDCM accordingly. The provided method is based on the motor winding time-sharing theory, and the controller controls the inverter to make the winding used as a driving element with loading current when the absolute value of the BEMF is relatively large and as a sensing element when the absolute value of the BEMF is relatively small.

Abstract: A method for starting a motor having a stator, a rotor, a winding and an asymmetrical air gap is accomplished using several steps. The steps include: (a) providing the motor at standstill; (b) exciting the winding for a specific time period with a current impulse having a first amplitude to obtain a first specific position of the rotor with respect to the stator; (c) decreasing the first amplitude down to a second amplitude gradually by a controller to make the rotor to be positioned at a second specific position with respect to the stator after the specific time period, wherein the second amplitude is one of zero ampere and a specific value close to zero ampere, and the rotor is rotating close to the second specific position with an almost zero rotating speed when the second amplitude is reached.

Abstract: The methods for starting a Hall-less single-phase BLDCM having an asymmetrical air gap are proposed. The provided methods are employed to input a specific amount of current impulse and stop the current impulse at a specific time such that the rotor of the single-phase BLDCM having an asymmetrical air gap can be realized to rotate in the pre-determined direction through one of the cogging torque and the rotor inertia after that specific time so as to accomplish the normal starting of a motor without the Hall-effect sensor.

Abstract: The methods for starting a Hall-less single-phase BLDCM having an asymmetrical air gap are proposed. The provided methods are employed to input a specific amount of current impulse and stop the current impulse at a specific time such that the rotor of the single-phase BLDCM having an asymmetrical air gap can be realized to rotate in the pre-determined direction through one of the cogging torque and the rotor inertia after that specific time so as to accomplish the normal starting of a motor without the Hall-effect sensor.

Abstract: The method and circuit for controlling a sensorless single-phase BLDCM having a stator with a winding are proposed. The provided controlling circuit includes a power supply circuit, an inverter coupled to the winding and the power supply circuit, a BEMF detecting circuit coupled to the winding and the inverter and measuring a BEMF of the winding, and a controller coupled to the power supply circuit, the inverter and the BEMF detecting circuit and analyzing a status of the BEMF to control the BLDCM accordingly. The provided method is based on the motor winding time-sharing theory, and the controller controls the inverter to make the winding used as a driving element with loading current when the absolute value of the BEMF is relatively large and as a sensing element when the absolute value of the BEMF is relatively small.

Abstract: The proposed method for starting a motor having a stator, a rotor, a winding and an asymmetrical air gap, comprising the steps of: (a) exciting said winding with a current impulse such that said stator generates a magnetic field and going to one of steps (b) and (d); (b) driving said rotor to rotate in a first direction if a polarity of a portion of a specific tooth of said stator close to said air-gap and a polarity of a specific magnetic pole of said rotor corresponding to said tooth are opposite; (c) stopping said current impulse at a specific moment such that said rotor is rotated in a second direction by a cogging torque and going to step (f); (d) driving said rotor to rotate in a first direction if a polarity of a portion of a specific tooth of said stator close to said air-gap and a polarity of a specific magnetic pole of said rotor corresponding to said tooth are the same; (e) stopping said current impulse at said moment such that said rotor is rotated in a second direction by an inertia; and (f) dete