Method for operating a brushless electric motor
View Patent ↗A method for operating a brushless electric motor, the windings being energized by an inverter with the aid of six switches. A detection unit for detecting defective switches, a unit for measuring voltage at the outputs of the inverter, and a microcontroller for controlling the switch and for generating a pulse width modulated voltage supply for the windings are provided. A short-circuited switch causes a torque in the electric motor opposite the actuating direction of the electric motor. The method proposes that after detecting a short-circuited switch, the windings (U. V. W) are energized to generate a motor torque that is, on the whole, positive. An actuating period of the electric motor is divided into a plurality of sectors, wherein, in accordance with the defective switch, individual sectors are deactivated for the actuation of the windings (U, V, W), while other sectors are used to actuate the windings (V, W).
1. A method for operating a brushless electric motor, the windings (U, V, W) of which are actuated by an inverter by six switches, wherein an identification unit is provided for identifying defective switches, a unit is provided for voltage measurement at the outputs of the inverter and a microcontroller is provided for controlling the switches and for generating a pulse-width-modulated power supply (PWM U , PWM V , PWM W ) for the windings (U, V, W), wherein, after a defectively switched-on switch is identified, the windings (U, V, W) are actuated in such a way that a motor moment which is positive on average is generated, wherein an actuation period of the electric motor is subdivided into a plurality of sectors, wherein, depending on the defective switch, individual sectors for actuating the windings (U, V, W) are deactivated, while the other sectors are used to actuate the windings (V, W).
2. The method as claimed in claim 1 , wherein the actuation period is subdivided into twelve sectors, wherein each sector corresponds to 30°.
3. The method as claimed in claim 1 , wherein the windings (V, W) are actuated in those sectors in which the defectively switched-on switch is also closed in a normal mode.
4. The method as claimed in claim 1 , wherein voltage values (PWM V , PWM W ), which counteract the effects of the defective switch, are applied to the windings (V, W) in the sectors, which are used for the actuation.
5. The method as claimed in claim 1 , wherein the switches are combined into switch pairs, and a switch pair is no longer actuated when a switch of a switch pair is defectively switched on.
6. The method as claimed in claim 1 , further comprising:
identifying a defective switch;
analyzing whether the defective switch is defectively switched on or switched off; and
actuating the windings (U, V, W) sector-by-sector.
7. The method as claimed in claim 6 , wherein the electric motor is switched off after a previously defined time period or once a safe external state is present.