METHOD FOR THE NOISE-REDUCED OPERATION OF A SWITCHED RELUCTANCE MOTOR

Abstract

A method for the noise-reduced operation of a switched reluctance motor with a reluctance motor assembly. The assembly includes the switched reluctance motor; —a control and evaluation unit; —a data memory; —a current regulator; —a rotor angle sensor; and —a torque evaluator. The switched reluctance motor includes a stator, a rotor and motor coils. The size of the current applied to the motor coils is stored in a value table in the data memory for different rotor angles. An actual torque is detected, and a deviation between a setpoint torque and the determined actual torque is determined. On the basis thereof, the current values are recalculated. The recalculated current values are written into the value table and define the basis of the next run.

Claims

1-2. (canceled)

3. A method for the noise-reduced operation of a switched reluctance motor with a reluctance motor assembly, the method comprising: providing the switched reluctance motor including a stator, a rotor and motor coils; providing the switched reluctance motor assembly with a control and evaluation unit, a data memory, a current regulator, a rotor angle sensor and a torque evaluator; including the following procedural steps: a) defining a value table in the data memory including table points defined by value tuples, each of the value tuples including a pair of values from a setpoint torque, a rotor angle and an assigned setpoint current; b) performing a partial cycle, including the following sub-steps: b1) providing specification of a setpoint torque; b2) detecting a first actual rotor angle with the rotor angle sensor; b3) the control and evaluation unit reading-out the setpoint current which is assigned to a first pair of values from the setpoint torque and the first actual rotor angle by determining the closest table points and calculating a distance of real values of the setpoint torque and of the first actual rotor angle to the table points, determining a setpoint current by bilinear interpolation from respective setpoint currents of four table points; b4) setting the setpoint current with the current regulator; b5) applying current to the motor coils; b6) evaluating actual torque with the torque evaluator; b7) comparing the setpoint torque and the actual torque with the control and evaluation unit for determining a torque deviation; b8) calculating a corrected setpoint current with the control and evaluation unit, on the basis of the torque deviation, for all four table points most recently used as a function of interpolation distance used; b9) entering the calculated values of the corrected setpoint current in four relevant value tuples of the value table with the control and evaluation unit and deleting previous values of the setpoint current; c) repeating performance of the partial cycle until a rotor angle corresponding to a complete motor state is reached for forming a complete cycle; d) repeating performance of a complete cycle.

4. The method for the noise-reduced operation of a switched reluctance motor according to claim 3, wherein the value table is configured for a complete rotor rotation.

Description

[0070] The invention is explained in more detail by way of example with reference to

[0071] FIG. 1 Reluctance motor assembly

[0072] FIG. 2 Schematic flow chart of the method

[0073] FIG. 3 Torque behaviour of the reluctance motor during the application of the method

[0074] FIG. 4 Values, interpolation and calculation of the corrections.

[0075] FIG. 1 shows a schematic structure of the reluctance motor assembly.

[0076] The reluctance motor assembly comprises a control and evaluation unit 2, a data memory 3, a current regulator 4, a rotor angle sensor 5, a torque evaluator 6 and a switched reluctance motor 1.

[0077] The current regulator 4, the rotor angle sensor 5 and the torque evaluator 6 are each connected to the reluctance motor 1 and the control and evaluation unit 2.

[0078] In this embodiment, the data memory 3 with the value table is integrated into the control and evaluation unit 2.

[0079] The switched reluctance motor 1 has a stator 7, a rotor 8 and several motor coils 9.

[0080] The current regulator regulates the setpoint currents for the motor coils to the values transmitted by the control and evaluation unit 2.

[0081] The rotor angle sensor 5 determines the position of the rotor 8 and transmits it to the control and evaluation unit 2 and to the torque evaluator 6.

[0082] The torque evaluator 6 evaluates the actual torque from the parameters applied to the reluctance motor 1, in the embodiment in particular from the actual current, in relation to a specific rotor angle, and also transmits this actual torque to the control and evaluation unit 2. From this value, the control and evaluation unit 2 calculates a torque deviation and, on this basis, optimized setpoint current values and enters them into the value table of the data memory 3 thus deleting the previous setpoint current values.

[0083] FIG. 2 shows a schema of the method for a noise-reduced operation of a switched reluctance motor. The schema gives a summary of all the procedural steps from a) to d), wherein the procedural step b) is shown with all its sub-steps. The partial cycle (procedural step b)) is repeated until the end of the first motor state is reached, and upon reaching the first motor state, it is repeated until the end of the next motor state is reached (procedural step c)). This is a complete cycle.

[0084] The complete cycle is repeated for all motor states until a complete 360° rotation of the rotor is achieved (procedural step d)). Once a complete rotation of the rotor has been terminated, the entire sequence can be repeated as often as required to effect a continuous rotation.

[0085] The value table is continuously updated in step b)9.

[0086] FIG. 3 shows a compilation of graphs to the torque behaviour of the reluctance motor during the application of the method. At the beginning (t=0 or on the left), the switched reluctance motor still shows high torque peaks, also referred to as torque ripples, which are caused by a suboptimal superposition of the partial torques, especially during the transition from one motor state to the next (at the bottom left). After several complete cycles, the torque peaks are significantly reduced (at the bottom right) and the partial torques overlap more advantageously. The torque peaks are responsible for a vibration of the rotor teeth and stator teeth and thus for the loud running noise of the reluctance motor. Hence, the reduction of the torque peaks also reduces the motor noise.

[0087] FIG. 4 shows the interpolation of the values in the coordinate system a) and the calculation of the corrections for the setpoint currents in table b).

[0088] The value interpolation according to procedural step b)3 is represented graphically in the coordinate system a). The control and evaluation unit is given the setpoint torque and the rotor angle sensor provides the actual rotor angle (Θ.sub.ist). The control and evaluation unit determines the four closest table points (P11, P12, P21, P22) and interpolates a setpoint current (I.sub.soll) by bilinear interpolation. The value for a setpoint current (I.sub.soll) obtained in this way by interpolation is set by the current regulator in procedural steps b)4 and b)5 and transmitted to the motor coils.

[0089] In procedural step b)6, the torque evaluator evaluates the actual torque (M.sub.ist) applied and, in procedural step b)7, the control and evaluation unit sets it off against the setpoint torque (M.sub.soll) to obtain a torque deviation (M.sub.soll-M.sub.ist).

[0090] FIG. 4 shows in table b) the calculation formulas for the correction values (according to procedural step b)8) with the torque deviation on the basis of the interpolation distances (h, l) used, a learning constant (K.sub.Lern) and the torque deviation (M.sub.soll-M.sub.ist).

LIST OF REFERENCE NUMERALS

[0091] 1 switched reluctance motor [0092] 2 control and evaluation unit [0093] 3 data memory [0094] 4 current regulator [0095] 5 rotor angle sensor [0096] 6 torque evaluator [0097] 7 stator [0098] 8 rotor [0099] 9 motor coils