Method and system for starting a sensorless motor
AssigneeInternational Rectifier Corporation
InventorEddy Ying Yin Ho
Life of this patent
Estimating the term…
Abstract
A motor drive system for a sensorless motor includes a catch start sequencer that controls the motor drive system to robustly start the motor in the event the motor rotor is rotating in forward or reverse direction prior to activating the motor drive system. In particular, the catch start sequencer causes the motor drive system to initially find and track the rotor position, and then determines the speed and possibly the direction of rotation of the rotor. If the rotor is rotating in the reverse direction, the catch start sequencer controls the motor drive system to slow the speed of rotation and to then start the rotor rotating in the forward direction.
Claims25
A method for controlling a motor drive for starting a sensorless motor having a rotor, said method comprising the steps of:
- determining whether the rotor is rotating in a forward or reverse direction;
- if the rotor is rotating in the reverse direction, causing a short circuiting of phase windings of the motor, thereby slowing down the reverse rotation of the rotor;
- removing the short circuiting of the motor phase windings, determining an angle of a rotor magnet by determining a phasing of a short-circuit motor current vector, and causing an open-loop forward rotating current vector to be applied to the motor, thereby causing the rotor to spin in the forward direction to an initial speed;
- and thereafter causing a closed-loop forward rotating current vector to be applied to the motor, thereby causing the rotor to speed up to a set speed.
A catch start sequencer for controlling a motor drive for starting a sensorless motor having a rotor, the motor drive including an inverter for driving the motor, a pulse width modulation module for controlling the inverter, a vector rotator module for controlling the pulse width modulation module, a current regulator configured as a feedback loop between the inverter and the vector rotator module, and a rotor flux estimation module for estimating rotor flux, said catch start sequencer comprising:
- one or more interfaces for interfacing with the current regulator and the rotor flux estimation module, and wherein said catch start sequencer is configured:
- to determine whether the rotor is rotating in a forward or reverse direction;
- to cause a short circuiting of phase windings of the motor if the rotor is spinning in the reverse direction in order to slow down the reverse rotation of the rotor;
- to remove the short circuiting of the motor phase windings and to determine an angle of a rotor magnet by determining a phasing of a short circuit motor current vector, and to cause an open-loop forward rotating current vector to be applied to the motor in order to cause the rotor to spin in the forward direction to an initial speed;
- and to thereafter cause a closed-loop forward rotating current vector to be applied to the motor in order to cause the rotor to speed up to a set speed.
Dependencies are inferred from the claim text.