Method for correcting the direction of rotation, control unit, and electric motor
The method improves rotor control accuracy and reduces vibrations by calculating and correcting rotational errors in electric motors, enhancing their performance in vehicles and fluid pumps without encoder reliance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-03-14
- Publication Date
- 2026-03-25
AI Technical Summary
Existing electric motor systems struggle with precise and controlled rotational movements, particularly in encoderless operations, leading to vibrations and inaccuracies.
A method for accurately calculating specified rotation angles and correcting rotational direction errors using computational variables and injection signals, enabling precise rotor control without the need for position sensors.
Enhances rotor control accuracy and reduces vibrations, allowing reliable operation of electric motors in vehicles and fluid pumps, with improved durability and reduced noise.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the method according to claim 1. The present invention further relates to a control unit and an electric motor.
Background Art
[0002] WO 2020 / 001681 describes a torque transmission device comprising an electric motor having a stator and a rotor rotatable relative to the stator by rotational movement, and a control unit capable of outputting a current pulse to the electric motor, wherein the current pulse causes a rotational movement of the rotor in a first direction of rotation and at a first rotation angle, whereby an induced voltage is received by the control unit, and based on the induced voltage, the control unit determines the direction of rotation of the rotor relative to the stator and / or the rotor rotation angle.
Summary of the Invention
Problems to be Solved by the Invention
[0003] An object of the present invention is to perform the rotational movement of the rotor more precisely and controllably.
Means for Solving the Problems
[0004] At least one of these objects is achieved by a method having the features according to claim 1. This enables a more accurate and reliable calculation of the specified rotation angle and enables the rotor to perform the desired rotational movement more accurately and controllably. It is possible to reduce the vibrations generated during the operation of the electric motor.
[0005] An electric motor can be placed in the vehicle's drivetrain. The drivetrain can be a hybrid drivetrain. The electric motor can provide the driving force to propel the vehicle. The vehicle can be an automobile. The electric motor can drive a fluid pump. The electric motor can be a pump motor. The fluid pump can be a hydraulic pump.
[0006] Electric motors can be operated without an encoder. This method can be implemented during encoderless operation of an electric motor. Electric motors can be operated exclusively without an encoder. Encoderless operation is understood to mean operation that does not take into account the rotor rotation angle measured by a sensor, such as a position sensor.
[0007] An electric motor can be controlled via at least three motor phases. The electric motor can be a brushless DC motor. The electric motor can also be a permanent magnet synchronous motor.
[0008] This method can be implemented when the rotor begins to rotate, that is, before the rotor has reached the required rotor speed.
[0009] The rotational direction error can be defined as the deviation between the expected direction of rotation of the rotor and the current direction of rotation.
[0010] A first specified rotation angle can set the rotor rotation angle at a first time point. A second specified rotation angle can set the rotor rotation angle at a subsequent second time point. Each specified rotation angle can specify an electrical operating variable for the rotational movement of the rotor. The electrical operating variable can be the phase voltage in at least one motor phase.
[0011] In a preferred embodiment of the present invention, it is advantageous when the calculation variable is a second input rotation angle calculated from a second specified rotation angle. As a result, angle correction can be performed on both the second specified rotation angle as the output of the angle calculation in the second calculation step and the second input rotation angle as the input to the subsequent angle calculation in the subsequent calculation step, thereby allowing the calculation of the subsequent specified rotation angle to be performed more accurately in accordance with the second input rotation angle.
[0012] In an advantageous embodiment of the present invention, a second input rotation angle is defined to be calculated in a second calculation step. The second input rotation angle can be output along with a second specified rotation angle and can be used as input for calculating further specified rotation angles in subsequent calculation steps.
[0013] In certain embodiments of the present invention, it is advantageous that, after the second calculation step, a third calculation step is performed to calculate a third specified rotation angle in accordance with the second input rotation angle corrected by angle correction. The 180° offset corrected by angle correction can be maintained in the specified rotation angle of the subsequent calculation step.
[0014] In a preferred embodiment of the present invention, it is advantageous if the first input rotation angle is calculated in a first calculation step. In the first calculation step, the first input rotation angle can be calculated simultaneously with or with a time delay to the first specified rotation angle.
[0015] In a preferred embodiment of the present invention, the first input rotation angle is defined to be stored for retrieval in a subsequent calculation step. The first input rotation angle can be stored in memory for retrieval.
[0016] In a preferred embodiment of the present invention, the computational variable is an input signal for generating an injection signal, which is applied to an electric motor to determine the rotor rotation angle. The injection signal may include a high-frequency injection voltage in the motor phase to identify the rotor rotation angle. The injection signal can be generated at rotor rotation speeds below the critical speed. If the rotor rotation speed is above the critical speed, the injection signal may not be present.
[0017] The calculation variables can include a second input rotation angle and an input signal. In the angle correction step, both the angle of the second input rotation angle and the angle of the input signal can be corrected by 180° each.
[0018] In certain embodiments of the present invention, it is advantageous if the detection of the rotational direction error is performed before, during, or after the calculation of the second specified rotation angle. The rotational direction error can be detected before, during, or after the calculation of the first specified rotation angle.
[0019] Furthermore, within the context of the present invention, a control unit having the features of claim 9 is proposed to solve at least one of the problems mentioned above. The control unit can be installed in a vehicle.
[0020] Furthermore, within the context of the present invention, an electric motor having the features of claim 10 is proposed to solve at least one of the problems mentioned above. This makes it possible to operate the electric motor more reliably. The durability of the electric motor is increased. In addition, the electric motor produces less annoying noise.
[0021] Further advantages and advantageous embodiments of the present invention will become apparent from the description and drawings.
[0022] The present invention will be described in detail below with reference to the drawings. [Brief explanation of the drawing]
[0023] [Figure 1]Shows a method for correcting the direction of rotation in a specific embodiment of the present invention. [Figure 2] Shows a timing diagram showing the execution of a method for correcting the direction of rotation in a further specific embodiment of the present invention. [Figure 3] Shows a control unit in a specific embodiment of the present invention.
Mode for Carrying Out the Invention
[0024] FIG. 1 shows an electric motor and a method for correcting the direction of rotation in a specific embodiment of the present invention. The method 10 for correcting the direction of rotation is implemented in an electric motor 12 having a stator 14 and a rotor that performs a rotational movement 16 with respect to the stator. When the rotor 18 performs a rotational movement 16 along the first rotational direction 20, thereby performing a rotational movement 16 against the desired second rotational direction 22, the direction correction of the rotation will correct the direction of rotation so that the rotational movement 16 has the desired second rotational direction 22.
[0025] The method 10 includes calculating 24 a first specified rotation angle 26 in a first calculation step 28. The rotor rotation angle 30 of the rotor 18 with respect to the stator 14, which can be changed by the rotational movement 16 of the rotor 18, is set at a first time point 32 according to the first specified rotation angle 26.
[0026] The method 10 further includes calculating 34 a first input rotation angle 36 according to the first specified rotation angle 26. The calculation 34 of the first input rotation angle 36 is preferably performed in the first calculation step 28. The first input rotation angle 36 is stored in the memory 37 for subsequent search by calculation steps.
[0027] Next, in the second calculation step 42, a second specified rotation angle 40 is calculated according to the first input rotation angle 36 38. The first specified rotation angle 26 sets the rotor rotation angle 30 at the first time point 32. The second specified rotation angle 40 sets the rotor rotation angle 30 at the subsequent second time point 43.
[0028] If a rotational directional error 46 of the rotational movement 16 of the rotor 18 is detected 44, the angle 48 of the second specified rotation angle 40 and at least one further calculation variable 50 calculated from the second specified rotation angle 40 are each corrected by 180°. The detection of the rotational directional error 46 44 is performed before, during, or after the calculation 38 of the second specified rotation angle 40.
[0029] The calculation variable 50 is, for example, a second input rotation angle 52 calculated from a second specified rotation angle 40. The second input rotation angle 52 is preferably calculated by calculation 53 in the second calculation step 42 and used 54 to calculate a third specified rotation angle 55 in the subsequent third calculation step 56. As a result, the 180° offset is permanently maintained by the angle correction 48 for all specified rotation angles following the second specified rotation angle 40, in particular until further angle correction 48 is performed.
[0030] The calculation variable 50 can also be an input signal 57 for generating an injection signal 58, which is applied on the electric motor 12 to determine the rotor rotation angle 30.
[0031] Figure 2 shows a timing diagram illustrating the execution of a method for correcting the direction of rotation in a further specific embodiment of the present invention. Figure 2a) shows the time course of a trigger signal 59 that triggers angle correction 48. At time t1, the trigger signal 59 changes from 0 to 1, initiating angle correction 48. The 180° offset performed by angle correction 48 is maintained over time.
[0032] In Figure 2b), the phase voltages are shown in a stator-fixed reference system, in this case the αβ coordinate system. The rotor begins its rotational movement 16 only at time t0. A high-frequency injection signal 58 present in the first phase voltage 62 functions to determine the rotor rotation angle when the rotational movement 16 starts from a stationary state. When the rotational movement 16 occurs, the second phase voltage 64 also has an injection signal 58.
[0033] In Figure 2c), the rotor speed 66 measured here using a position sensor is shown in comparison to the rotor speed 68 calculated in particular by the injection signal 58.
[0034] In Figure 2d), the rotor rotation angle 70 measured here for reference using a position sensor is shown in comparison to the specified rotation angle 72. A hypothetical specified rotation angle 72 offset by 180° can be seen, and the specified rotation angle 72 is adjusted to the existing measured rotor rotation angle 70 by the angle correction 48 at time t1. By simultaneously changing the specified rotation angle 72, here the second specified rotation angle 40 as the specified rotation angle 72 at time t1, and the second input rotation angle, the specified rotation angle 72 can better track the measured rotor rotation angle 70, and damped oscillations in the specified rotation angle 72 can be reduced or prevented.
[0035] After the angle correction 48 is performed, the rotational movement 16 of the rotor changes to the opposite direction of rotation, which can be seen here by the change in the reference sign of the measured rotor speed 66.
[0036] Figure 3 shows a control unit in a particular embodiment of the present invention. The control unit 74 has a computing device 76 for carrying out a method for correcting the direction of rotation, for example, as described in Figure 1. [Explanation of symbols]
[0037] 10 ways 12 Electric motors 14 Stator 16 rotations 18 rotors 20 Direction of the first rotation 22 Direction of the second rotation 24 Calculation 26 First identified rotation angle 28. First calculation step 30 rotor rotation angle 32. First point in time 34 Calculation 36. First input rotation angle 37 memory 38 Calculation 40 Second identified rotation angle 42 Second calculation step 43. Second point in time 44 detected 46 rotational directional error 48 Angle Correction 50 computational variables 52 Second input rotation angle 54 Calculation 55 Third identified rotation angle 56 Third calculation step 57 Input signal 58 Injection signal 59 Trigger signal 62 First phase voltage 64 Second phase voltage 66 Measured rotor speed 68 Calculated rotor speed 70 Measured rotor rotation angle 72 Identified rotation angle 74 Control Unit 76 Computing equipment
Claims
1. A method (10) for correcting the direction of rotation of a rotational movement (16) in an electric motor (12) having a stator (14) and a rotor (18) that performs rotational movement (16) relative to the stator, the method comprising the following steps: In the first calculation step (28), a step (24) is to calculate a first specified rotation angle (26) which sets the rotor rotation angle (30) of the rotor (18) relative to the stator (14), which can be changed by the rotational movement (16) of the rotor (18), A step (34) of calculating a first input rotation angle (36) according to the first specified rotation angle (26), In the second calculation step (42), a step (38) is performed to calculate a second specified rotation angle (40) according to the first input rotation angle (36), If a directional error (46) in the rotational movement (16) of the rotor (18) is detected (44), the method (10) includes the step of correcting the angle (48) of the second identified rotation angle (40) and at least one further calculation variable (50) calculated from the second identified rotation angle (40) by 180° each.
2. The method according to claim 1 (10), characterized in that the calculation variable (50) is a second input rotation angle (52) calculated from the second specified rotation angle (40).
3. The method according to claim 2 (10), characterized in that the second input rotation angle (52) is calculated in the second calculation step (42).
4. The method according to claim 2 or 3 (10), characterized in that, after the second calculation step (42), in a third calculation step (56), a third specified rotation angle (55) is calculated (55) according to the second input rotation angle (52) corrected by angle correction (48).
5. The method according to any one of claims 1 to 4 (10), characterized in that the first input rotation angle (36) is calculated in the first calculation step (28).
6. The method according to any one of claims 1 to 5 (10), characterized in that the first input rotation angle (36) is stored for retrieval in a subsequent calculation step.
7. The method according to any one of claims 1 to 6 (10), characterized in that the calculation variable (50) is an input signal (57) for generating an injection signal (58) which is applied to the electric motor (12) to determine the rotor rotation angle (30).
8. The method according to any one of claims 1 to 7 (10), characterized in that the detection (44) of the rotational direction error (46) is performed before, during, or after the calculation (38) of the second specified rotation angle (40).
9. A control unit (74) having a computing device (76) for carrying out the method (10) according to any one of claims 1 to 8.
10. An electric motor (12) having a stator (14) and a rotor (18) rotatable therewith, wherein the rotational movement (16) of the rotor (18) can be adjusted by the method (10) of any one of claims 1 to 8.