Method for operating a drive unit of a hub drive of an electric bicycle

Abstract

The invention relates to a method for operating a drive unit of a hub drive of an electric bicycle, wherein the drive unit comprises a permanent magnet synchronous motor, comprising the steps of: actuating the drive unit by means of an actuation signal which comprises a PWM signal, modifying the PWM signal by means of high-frequency voltage injection, detecting at least two phase currents at different phases of the drive unit, and determining an electrical angle of the drive unit based on the detected phase currents.

Claims

[1] Method for operating a drive unit (1) of a hub drive (10) of an electric bicycle (100), wherein the drive unit (1) comprises a permanent magnet synchronous motor, comprising the steps: - actuating (51) the drive unit (1) by means of an actuating signal (11) which comprises a PWM signal (12), - modifying (52) the PWM signal (12) by means of high-frequency voltage injection, - detecting (53) at least two phase currents on different phases of the drive unit (1), and - Determining (54) an electrical angle of the drive unit (1) based on the detected phase currents. [2] The method according to claim 1, further comprising the step of: adjusting (55) the actuation signal for actuating the drive unit (1) based on the determined electrical angle in such a way as to generate a predetermined motor torque by means of the drive unit (1). [3] Method according to one of the preceding claims, wherein the high-frequency voltage injection is carried out by means of PWM shifting of at least a part of the PWM signal. [4] A method according to any one of the preceding claims, wherein detecting the at least two phase currents comprises measuring the current twice per phase during a single PWM period. [5] Method according to claim 4, wherein the current measurement is carried out at the beginning and in the middle of each PWM period. [6] Method according to one of claims 4 or 5, wherein the determination of the electrical angle of the drive unit (1) is based on a detected current difference between the two current measurements during the individual PWM period. [7] Method according to one of the preceding claims, wherein the PWM signal is generated with a, in particular constant, frequency of at least 10 kHz, preferably at least 14 kHz, particularly preferably 18 kHz. [8] Method according to one of the preceding claims, wherein the high-frequency voltage injection is generated exclusively in a d-current direction of the permanent magnet synchronous motor. [9] Method according to one of the preceding claims, wherein the method is carried out only up to a predetermined maximum speed of the drive unit (1). [10] Method according to one of the preceding claims, wherein a rotor position and / or a rotational speed of the drive unit (1) is determined based on the determined electrical angle of the drive unit (1). [11] Method according to one of the preceding claims, wherein the determination of the electrical angle of the drive unit (1) is carried out completely without angle sensors. [12] Drive arrangement of a hub drive (10) of an electric bicycle (100), comprising: - a drive unit (1), - at least two current sensors (2) and - a control unit (3) which is configured to carry out the method according to one of the preceding claims. [13] Drive arrangement according to claim 12, wherein the current sensors (2) are an integral part of the control unit (3). [14] Drive arrangement according to claim 12 or 13, wherein the drive unit (1) and the control unit (3) are connected by means of a line (4). [15] Electric bicycle, comprising a drive arrangement (20) according to one of claims 12 to 14, wherein the drive unit (1) is arranged on a hub (101) of a wheel (110), in particular a front wheel or rear wheel.

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