Method and device for controlling a brushless direct-current motor
View Patent ↗Presented in an apparatus for controlling a brushless DC motor with a permanent magnet arranged on a rotor and a stator with windings. The apparatus includes an observer that is adapted to determine an estimated temperature of the permanent magnet as a function of the temperature of the windings, and determine at least one actuating signal for controlling the DC motor as a function of the estimated temperature of the permanent magnet.
1. An apparatus for controlling a brushless DC motor with a permanent magnet arranged on a rotor and a stator with windings, the apparatus comprising:
a winding temperature unit determining a temperature of the windings;
a first observer adapted to determine an estimated temperature of the permanent magnet as a function of the determined temperature of the windings, and determine at least one actuating signal for controlling the DC motor as a function of the estimated temperature of the permanent magnet; and
a second observer adapted to determine an estimated start temperature of the permanent magnet when the DC motor is switched on as a function of a time period since the last time the DC motor was switched off.
2. The apparatus as claimed in claim 1 , wherein the observer comprises a PT 1 element.
3. The apparatus as claimed in claim 2 , wherein at least one parameter of the PT 1 element is dependent on at least one load variable of the DC motor.
4. The apparatus as claimed in claim 3 , wherein the at least one load variable is the rotation speed or the current through the windings.
5. The apparatus as claimed in claim 1 , wherein the winding temperature unit determines the temperature of the windings as a function of the current through the windings.
6. A method for controlling a brushless DC motor with a permanent magnet arranged on a rotor and a stator with windings, the method comprising:
determining a temperature of the windings;
determining, by an observer, an estimated temperature of the permanent magnet as a function of the temperature of the windings;
determining at least one actuating signal for controlling the DC motor as a function of the estimated temperature of the permanent magnet; and
determining by a second observer an estimated start temperature of the permanent magnet when the DC motor is switched on as a function of a time period since the last time the DC motor was switched off.