Method and device for synchronizing a servo steering motor with a motor position sensor

Abstract

A method for synchronizing a servo steering motor with a motor position sensor may include: sequentially aligning, by a control device, a rotor of the servo steering motor by sequentially applying preset three-phase current pulses to the servo steering motor, wherein the three-phase current pulses correspond to one electrical angular cycle of the rotor of the servo steering motor; detecting the actual rotational position of the aligned motor by the motor position sensor; determining a zero-point rotational position of the rotor based on the actual rotational position; determining a reference rotational position of the rotor based on the actual rotational position and the number of pole pairs in the servo steering motor; determining an offset rotational position of the rotor based on the actual rotational position and the reference rotational position; and correcting the zero-point rotational position by adding the offset rotational position to the zero-point rotational position.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method and a device for synchronizing a servo steering motor with a motor position sensor and, in particular, a method and a device for synchronizing a rotational position of a rotor of a servo steering motor with a motor position sensor.

[0002] In general, the position of a three-phase, brushless motor in a power steering system must be precisely calculated in order to control the motor.

[0003] The stator of a three-phase brushless motor typically comprises field poles and a frame, with the field poles fixed to the frame by screws or bolts. Furthermore, the rotor of a three-phase brushless motor comprises a permanent magnet in which the N and S poles are repeated.

[0004] For the motor rotor to rotate, successive rotating fields must be generated. To create such successive rotating fields, a current applied to a three-phase coil in a stator winding must be commutated at a specific time. For this commutation to occur at the appropriate time, the rotor's position must be precisely determined. Commutation is an operation to change the direction of the current in the motor stator coil so that the rotor can rotate. For smooth motor operation, the rotor's position must be precisely aligned with a commutation point of a phase current. A motor position sensor is required to detect the rotor's position for this operation.Generally, a Hall sensor is used to detect the position of the rotor, with the Hall sensor having a potential difference that changes in accordance with a change in the magnetic flux.

[0005] However, to detect the rotor position using a motor position sensor such as a Hall sensor, a preliminary operation is required to synchronize the motor's initial rotational position with the sensor. According to a conventional synchronization method, a line voltage induced in a motor's stator winding by an external force is measured and compared to an output pulse from the Hall sensor. An offset between a zero crossing point of the line voltage and a crossover point of the Hall sensor's output pulse is then calculated. Software is then used to correct this offset to zero or subtract it from the motor position sensor's output to achieve synchronization.

[0006] However, because the conventional synchronization method requires a separate drive unit to power the motor and a separate measuring unit to measure the Hall sensor's measuring voltage and output voltage, costs are inevitably higher. Furthermore, any error occurring during measurement will impair control performance. And because the ECU and motor must be separated to measure the Hall sensor's line voltage and output pulse, the manufacturing process, which involves steps of disassembly, measurement, and reassembly, is inevitably inefficient.

[0007] From DE 10 2012 111 799 A1 a system for calibrating an electrically commutated motor is known with a sensor for detecting an angle between a position of the rotor and a position of the stator. SUMMARY OF THE INVENTION

[0008] Embodiments of the present invention relate to a method and a device for synchronizing a servo steering motor with a motor position sensor, in which the manufacturing time can be reduced by removing separate measuring devices that were previously required for an operation to synchronize the initial rotational position of a motor with a motor position sensor and eliminating errors occurring during the measurement, thereby improving the motor control performance.

[0009] The invention is defined by claims 1 and 3. The dependent claims specify advantageous embodiments.

[0010] In one embodiment, a method for synchronizing a servo steering motor with a motor position sensor may comprise: sequentially aligning, by a control device, a rotor of the servo steering motor by sequentially applying preset three-phase current pulses to the servo steering motor, wherein the three-phase current pulses correspond to an electrical angular cycle of the rotor of the servo steering motor, and detecting the actual rotational position of the aligned rotor by the motor position sensor; determining a zero-point rotational position of the rotor based on the actual rotational position; determining a reference rotational position of the rotor based on the actual rotational position and the number of pole pairs in the servo steering motor; and determining an offset rotational position of the rotor based on the actual rotational position and the reference rotational position.and correcting the zero-point rotation position by adding the offset rotation position to the zero-point rotation position.

[0011] When aligning the rotor of the servo steering motor, the control unit can repeatedly detect the actual rotational position of the rotor with a preset number of repetitions when the rotor is aligned, and store the average of the detected actual rotational position values.

[0012] When aligning the rotor of the servo steering motor, one electrical angle cycle can comprise six stages, in which the electrical angle of the rotor is sequentially increased by 60°.

[0013] The alignment of the servo steering motor rotor can be repeated according to the number of pole pairs.

[0014] When determining the zero-point rotational position of the rotor, the control device can determine the zero-point rotational position of the rotor by subtracting a rotational position value corresponding to an electrical angle of 120° from a first actual rotational position from the first to 6nth actual rotational positions, which are determined in accordance with the order of acquiring and storing the actual rotational positions.

[0015] Determining the reference rotational position of the rotor may involve: determining first to 6nth reference rotational positions corresponding to the first to 6nth actual rotational positions based on the first actual rotational position and the number of pole pairs; setting differences between the first to 6nth actual rotational positions and the first to 6nth reference rotational positions to first to 6nth error values; and setting the average of the maximum error value and the minimum error value from the first to 6nth error values ​​to the offset rotational position.

[0016] The procedure may further include determining, by the control device, a hysteresis compensation rotational position based on preset hysteresis information from the motor position sensor and performing hysteresis compensation by adding the hysteresis compensation rotational position to the offset-corrected zero-point rotational position.

[0017] The procedure may further include resetting, by the control unit, the motor position sensor to the hysteresis-compensated zero-point rotation position.

[0018] In another embodiment, a device for synchronizing a servo steering motor with a motor position sensor may comprise: a motor position sensor configured to detect a rotational position of a servo steering motor;and a control device configured to sequentially align a rotor of the servo steering motor by sequentially applying preset, three-phase current pulses to the servo steering motor, wherein the three-phase current pulses correspond to an electrical angular cycle of the rotor in the servo steering motor, and to detect an actual rotational position of the aligned rotor by the motor position sensor, configured to determine a zero-point rotational position of the rotor based on the actual rotational position, configured to determine a reference rotational position of the rotor based on the actual rotational position and the number of pole pairs in the servo steering motor, and to determine an offset rotational position of the rotor based on the actual rotational position and the reference rotational position, and configured to correct the zero-point rotational position by adding the offset rotational position to the zero-point rotational position.

[0019] When aligning the rotor, the control unit can detect the actual rotational position of the rotor with a preset number of repetitions and store the average of the detected actual rotational position values.

[0020] The single electrical angle cycle can comprise six stages, in which the electrical angle of the rotor is sequentially increased by 60°; and the control device can detect and store the actual rotational position of the aligned rotor with a number of repetitions corresponding to the number of pole pairs during an electrical angle cycle.

[0021] The control device can determine the zero-point rotational position of the rotor by subtracting a rotational position value corresponding to an electrical angle of 120° from a first actual rotational position from the first to 6nth actual rotational positions, which are determined in accordance with the order of acquiring and storing the actual rotational positions.

[0022] The control unit can determine first to 6nth reference rotation positions corresponding to the first to 6nth actual rotation positions based on the first actual rotation position and the number of pole pairs, set differences between the first to 6nth actual rotation positions and the first to 6nth reference rotation positions to first to 6nth error values, and set the average of the maximum error value and the minimum error value from the first to 6nth error values ​​to the offset rotation position.

[0023] The control unit can determine a hysteresis compensation rotational position based on preset hysteresis information from the motor position sensor and performs the hysteresis compensation by adding the hysteresis compensation rotational position to the offset-corrected zero-point rotational position.

[0024] The control unit can reset the motor position sensor to the hysteresis-compensated zero-point rotation position. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block configuration diagram showing a device for synchronizing a servo steering motor with a motor position sensor according to an embodiment of the present invention. Fig. 2A is a UVW table that is set in a control unit of the device for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. Fig. 2B is a diagram showing the waveforms of the UVW signals. Fig. Figure 3 is a flowchart showing a method for synchronizing a servo steering motor with a motor position sensor according to an embodiment of the present invention. Fig. Figure 4 is a flowchart showing a step for setting an offset rotational position of the rotor in the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. Fig. Figure 5 is a table that explains a process for performing a synchronization operation by applying the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. DESCRIPTION OF SPECIFIC EXECUTION FORMS

[0025] The following describes embodiments of the invention in detail with reference to the accompanying drawings. It should be noted that the drawings are not necessarily to scale and that the thickness of lines or the size of components may be exaggerated for greater clarity. Furthermore, the terms used here should be interpreted in the context of the invention's functions and may be replaced by other terms familiar to the user. The terms should therefore be interpreted within the context of this description.

[0026] Fig. Figure 1 is a block configuration diagram showing a device for synchronizing a servo steering motor with a motor position sensor according to an embodiment of the present invention. Fig. 2A is a UVW table that is set in a control unit of the device for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. Fig. 2B is a diagram showing the waveforms of the UVW signals.

[0027] As in Fig. As shown in Figure 1, the device for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention can comprise a servo steering motor 10, a motor position sensor 20, and a control unit 30. The control unit 30 can include a UVW signal output unit 31, a motor driver 33, a switching unit 35, and a rotor position correction unit 37.

[0028] The following section describes a UVW signal. The UVW signal is an output signal from the motor position sensor 20, which measures the rotational position of a motor rotor in a state where a control device divides an electrical angle of the rotor into six sectors. Fig. Figure 2A shows the corresponding relationship between the electrical angle of the motor rotor and the U, V, and W outputs of the motor position sensor 20. Specifically, the electrical angle of the rotor can be divided into six sectors in the range of 0° to 360° for one pole pair. That is, each sector corresponds to 60°. If the electrical angle of the rotor is contained within the first sector from 0° to 60°, the U, V, and W outputs of the motor position sensor 20 can be 1, 0, and 1, respectively. And if the electrical angle of the rotor is contained within the second sector from 60° to 120°, the U, V, and W outputs of the motor position sensor 20 can be 1, 0, and 0, respectively. Typically, the control device, such as an ECU, can receive a UVW signal from the motor position sensor 20, with the UVW signal having waveforms as shown in Figure 2A. Fig. As shown in Figure 2B, determine in which sector the electrical angle of the rotor is contained, and apply a three-phase current to the motor in accordance with the received UVW signals to perform commutation control. Fig. Figure 2A shows the corresponding relationship between the electrical angle of the rotor and the U, V and W outputs of the motor position sensor 20.

[0029] The device according to this embodiment can detect the initial rotational position at which the rotor is aligned according to a UVW signal (1, 0, 1) corresponding to an electrical angle of 0°, calculate a zero-point rotational position based on the detected rotational position, determine the end zero point of the rotor by offset and hysteresis correction processes, and reset the motor position sensor 20 in order to synchronize the servo steering motor 10 with the motor position sensor 20.

[0030] For this operation, the device according to this embodiment may, under certain circumstances, not receive a UVW signal from the motor position sensor 20, but instead preset the same UVW signal as an actual UVW signal pattern output by the motor position sensor 20 and apply a three-phase current corresponding to the preset UVW signal to the servo steering motor 10 to detect the rotor's rotational position. The device can repeatedly detect the rotor's rotational position and correct the offset and hysteresis characteristics to improve the accuracy of the operation for synchronizing the servo steering motor 10 with the motor position sensor 20. The operation for detecting the rotor's rotational position can be performed with a number of repetitions corresponding to the six stages of an electrical angular cycle and the number of pole pairs.

[0031] Against the background of the configuration described above and with reference to Fig. 1 The operation of the device for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention is described below.

[0032] The UVW signal output unit 31 can output a preset UVW signal to the motor driver 33, where the UVW signal corresponds to an electrical angular cycle of the rotor in the servo steering motor 10. As shown in Fig. As shown in Figure 2A, UVW signals corresponding to the electrical angles of the rotor can be output sequentially to the motor driver 33. As shown in Fig. As shown in Figure 2A, the UVW signal output unit 31 can store mapping information between the electrical angles of the rotor and the UVW signals as a lookup table. The UVW signal output unit 31 can therefore send a UVW signal, initially set to (1, 0, 1), as three pulse signals to the motor driver 33.

[0033] The motor driver 33 can generate six switching control signals based on the received UVW signal and send each of these signals to six transistors (not shown) of the switching unit 35. Each of the six transistors can be switched on or off in response to the six switching control signals, supplying three-phase control pulses to the servo steering motor 10. The process of outputting the three-phase current pulses via the switching unit 35 with the transistors based on the UVW signal is familiar to those skilled in the art. Therefore, a detailed description of this process is omitted here.

[0034] In this embodiment, the UVW signal output unit 31, the motor driver 33, and the switching unit 35 are configured separately in the control unit 30. In other embodiments, however, the UVW signal output unit 31, the motor driver 33, and the switching unit 35 can also be integrated into a single component within the control unit 30.

[0035] When three-phase current pulses are applied to the servo steering motor 10, or more specifically to the three-phase stator windings of the servo steering motor 10, a static magnetic field can be generated. The rotor can then be aligned to a specific position in accordance with the static magnetic field generated by the stator. The time required to align and stop the rotor at a specific position by the static magnetic field is one second or less, depending on the specifications of the servo steering motor 10, such as the mass of the rotor. This suggests that a predetermined waiting period may be necessary before the motor position sensor 20 detects an actual rotational position of the rotor.

[0036] When the rotor is aligned and stopped at the specific position corresponding to the static magnetic field, the motor position sensor 20 can detect the rotor's rotational position. The sensor for detecting the rotor's rotational position can be a resolution device, an encoder, or a rotary sensor. In this embodiment, the rotary sensor can be used as the motor position sensor 20, although the motor position sensor 20 is not limited to this.

[0037] The rotor position correction unit 37 can detect the actual rotational position of the rotor aligned at the specific position using the motor position sensor 20. The motor position sensor 20, which can be implemented as a rotary sensor, can detect the rotational position of the rotor using a resolution of 14 bits. Therefore, the motor position sensor 20 can detect the rotational position of the motor using a resolution of 2 14To capture. For example, an output from motor position sensor 20 corresponding to a mechanical angle of 360° in the rotor is: 11111111111111. If the output of 11111111111111 is converted to a decimal number, the result is 16384 (=2 14A value corresponding to a mechanical angle of 1° in the rotor is therefore 45.5 (=16384 / 365). A value obtained by converting a 14-bit output from the motor position sensor 20 to a decimal number, such as 16384 or 45.5, is represented by a least significant byte (LSB). The rotor position correction unit 37 can store the actual rotational position of the rotor, as detected by the motor position sensor 20, as an LSB value. If the motor position sensor 20 is implemented as a rotary sensor, the rotary sensor's output can be sent to the rotor position correction unit 37 via a Serial Peripheral Interface (SPI) bus (MISO).

[0038] The 14-bit output of the motor position sensor 20 is, however, only one example to illustrate this embodiment, and the invention is not limited to this. The output of the motor position sensor 20 can also have a different number of bits depending on the resolution and specification of the motor position sensor 20 and is not limited to a binary output.

[0039] If the rotor is not aligned in a specific position, the rotor position correction unit 37 can repeatedly determine the rotor's actual rotational position with a preset number of repetitions and store the average of the acquired actual rotational position values. The process described above can minimize noise generated during the rotor position acquisition process, thereby increasing the accuracy of the rotational position measurement. Furthermore, the process can minimize rotational position measurement errors caused by slight rotor vibrations. Increasing the preset number of repetitions can improve the accuracy of the rotor position acquisition, but it also increases the time required to measure the rotational position. For example, the preset number of repetitions can be set to 1000.

[0040] The process described above can be summarized as follows. The UVW signal output unit 31 can output the initial UVS signal set to (1, 0, 1) to the motor driver 33, and the motor driver 33 can output the switching control signals to the switching unit 35. When the three-phase current pulses are then applied to the servo steering motor 10 via the switching unit 35, a static magnetic field can be generated, and the rotor can be aligned to a specific position corresponding to this static magnetic field. The rotor position correction unit 37 can repeatedly detect the actual rotational position of the rotor with a preset number of repetitions using the motor position sensor 20 and store an average of the detected rotational positions.This process corresponds to a first step of an electrical angular cycle for a pole pair and is repeated 6n times (= number of stages (6) of the electrical angular cycle * number of pole pairs (n)), whereby the UVW signal is varied sequentially and output by the UVW signal output unit 31.

[0041] When the 6n cycles are complete, the rotor position correction unit 37 can store 6n actual rotational positions of the rotor. The rotor position correction unit 37 can store these 6n actual rotational positions in a matrix. However, to distinguish the terms, the 6n actual rotational positions are defined as the first to 6nth actual rotational positions, corresponding to the order in which the actual rotational positions are acquired and stored.

[0042] The rotor position correction unit 37 can determine the zero-point rotational position of the rotor based on the actual rotational position. The first actual rotational position is a rotational position of the rotor corresponding to an electrical angle of 0° in the initial pole pair loop. In principle, the first actual rotational position can be set to the zero-point rotational position of the rotor. However, if the control unit 30 rotates the rotor of the servo steering motor by controlling a commutation via a three-phase current, the control unit 30 must perform a commutation at an electrical angle of 120° prior to the rotational position of the rotor.The control unit 30 can thus determine a rotational position relative to the zero-point rotational position, where the rotational position corresponds to an electrical angle of 120° prior to the position of the rotor aligned at the specific position in accordance with the applied three-phase current pulse, and reset the motor rotation sensor. The rotor position correction unit 37 can determine the zero-point rotational position by subtracting a rotational position value LSB corresponding to an electrical angle of 120° from the first actual rotational position, as expressed by the following equation 1. zeroAngleLSB=segAngleLSB[0]−214n×3

[0043] In equation 1, zeroAngle gives LSB The zero-point rotation position is displayed by segAngle. LSB [0] represents the first actual rotation position and n represents the number of pole pairs.

[0044] In equation 1, there is 2 14 / (n*3) represents a rotational position LSB corresponding to an electrical angle of 120°. That is, a mechanical angle corresponding to the electrical angle of 120° is equal to 120° / n. If a proportional expression of (360°:2 14 = 120° / n:x) is produced to calculate the rotational position LSB corresponding to the mechanical angle of 120° / n, the rotational position LSB corresponding to the electrical angle of 120° can be calculated as follows: 2 14 / (n*3). Therefore, the zero-point rotation position can be determined in accordance with equation 1.

[0045] The rotor position correction unit 37 can determine a reference rotational position of the rotor based on the actual rotational position and the pole pair number n and can determine an offset rotational position for correcting the zero point rotational position based on the actual rotational position and the reference rotational position.

[0046] In particular, the rotor position correction unit 37 can set the first to 6nth reference rotational positions, each corresponding to the first to 6nth actual rotational positions, based on the first rotational position and the number of pole pairs n. The first to 6nth reference rotational positions can specify normal rotational positions of the rotor, which are theoretically acquired during 6n cycles for acquiring the actual rotational position of the rotor. The first to 6nth reference rotational positions can be determined according to Equation 2. refAngleLSB[0…6n−1]=segAngleLSB[0]+214n×6i,i=0…6n−1

[0047] In equation 2, refAngle LSB [0...6n-1] the first to 6nth reference rotation positions, segAngle LSB [0] represents the first actual rotation position and n represents the number of pole pairs.

[0048] The rotor position correction unit 37 can set differences between the first to 6nth actual rotational positions and the first to 6nth reference rotational positions to first to 6nth error values ​​as expressed by the following equation 3. errAngleLSB[0…6n−1]=segAngleLSB[0…6n−1]−refAngleLSB[0…6n−1]

[0049] In equation 3, errAngle gives LSB [0...6n-1] the first to 6nth error values ​​are displayed, segAngle LSB The first to 6nth actual rotation positions are reproduced and refAngle is given. LSB [0 ... 6n-1] the first to 6nth reference rotation positions again.

[0050] The rotor position correction unit 37 can calculate the average between the maximum and minimum error values ​​from the first to 6nth error values ​​for an offset rotational position to correct the zero-point rotational position. By calculating the average between the maximum and minimum error values ​​for the offset rotational position, errors occurring while the rotor is rotated through a mechanical angle of 360° can be distributed symmetrically, thus improving the accuracy of the operation to determine the rotor's rotational position. The offset rotational position can be determined according to the following equation 4. offsetAngleLSB=max(errAngleLSB[…]+min(errAngleLSB[…])2

[0051] In equation 4, offsetAngle is given LSB the offset rotation position is given by ma×(errAngie LSB [...]) returns the maximum error value and gives min(errAngle LSB[...]) the minimum error value again.

[0052] The rotor position correction unit 37 can correct the zero-point rotational position by adding the offset rotational position to the zero-point rotational position. The offset correction can minimize an INL (Integrated Non-Linearity) error that can occur while the motor rotation sensor is sensing a rotational position of the rotor, i.e., an error between a normal sensor output and an actual sensor output.

[0053] The rotor position correction unit 37 can reflect the hysteresis curve of the motor position sensor 20 to precisely correct the zero-point rotational position. The rotational position correction unit 37 can determine a hysteresis compensation rotational position based on preset hysteresis information from the motor position sensor 20 and compensate the hysteresis curve by adding the hysteresis compensation rotational position to the offset-corrected zero-point rotational position. The hysteresis compensation rotational position can be determined according to equation 5. compHystLSB=HystSettingLSB2

[0054] In equation 5, compHyst LSB a hysteresis compensation rotation position is displayed and outputs HystSetting LSB preset hysteresis information is displayed again.

[0055] The final zero-point rotational position of the rotor, obtained by reflecting the offset and hysteresis characteristics, can be determined according to equation 6. zeroAngleCorrLSB=zeroAngleLSB+offsetAngleLSB+compHystLSB

[0056] In equation 6, zeroAngleCorr gives LSB The final zero-point rotational position, obtained by reflecting the offset and hysteresis curves, is given by zeroAngle. LSB The zero-point rotation position is represented by offsetAngle. LSB the offset rotation position is displayed and outputs compHyst LSB the hysteresis compensation rotation position again.

[0057] Equations 1 to 6 are based on the motor position sensor 20, which according to this embodiment has a resolution of 14 bits, wherein the parameters used in equations 1 to 6 can be set variably depending on the resolution and the specification of the motor position sensor 20.

[0058] The rotor position correction unit 37 can reset the motor position sensor 20 to the zero-point rotational position to which the offset and hysteresis characteristics are reflected. The rotor position correction unit 37 can thus definitively set the zero-point rotational position of the rotor of the MDPS motor 10 to the motor position sensor 20. The synchronization operation can then be completed. If the motor position sensor 20 is represented by the rotation sensor described above, the rotor position correction unit 37 can input the initial rotational position of the rotor to the rotation sensor via the SPI bus (MOSI).

[0059] Fig. Figure 3 is a flowchart showing a method for synchronizing a servo steering motor with a motor position sensor according to an embodiment of the present invention. Fig. Figure 4 is a flowchart showing a step for setting an offset rotational position of the rotor in the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention.

[0060] With reference to Fig. 3 and Fig. Section 4 first describes the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. First, in step S10, the control device 30 can sequentially align the rotor by sequentially applying preset three-phase current pulses to the servo steering motor 10, wherein the three-phase current pulses correspond to an electrical angular cycle of the rotor of the servo steering motor, and detect the actual rotational positions of the aligned rotor by means of the motor position sensor 20.

[0061] When the rotor is aligned, the control unit 30 can detect an actual rotational position of the rotor with a preset number of repetitions and store the average of the detected actual rotational position values.

[0062] An electrical angle cycle can comprise six stages, in which the electrical angle of the rotor is sequentially increased by 60°.

[0063] Step S10 can be repeated with the number n of pole pairs in the servo steering motor 10. The process for detecting the actual rotational position of the rotor aligned by the three-phase current pulses can therefore be repeated 6n times in step S20.

[0064] Once the processes for acquiring the 6n actual rotational positions are complete, the control device 30 can determine the zero-point rotational position of the rotor in step S30 by subtracting a rotational position value corresponding to an electrical angle of 120° from a first actual rotational position determined from the first to 6nth actual rotational positions in the order in which the actual rotational positions were acquired. As described above, the zero-point rotational position can be determined according to Equation 1.

[0065] Then, in step S40, the control unit 30 can determine a reference rotational position of the rotor based on the actual rotational position and the number n of pole pairs in the servo steering motor 10, and determine an offset rotational position of the rotor based on the actual rotational position and the reference rotational position.

[0066] In particular, the control unit 30 can determine the first to 6nth reference rotation positions in step S41, corresponding to the first to 6nth actual rotation positions, based on the first rotation position and the pole pair number n. As described above, the reference rotation positions can be determined according to equation 2.

[0067] In step S43, the control unit 30 can set the differences between the first to 6nth actual rotational positions and the first to 6nth reference rotational positions to the first to 6nth error values. As described above, the error values ​​can be determined according to equation 3.

[0068] In step S45, the control unit 30 can calculate an average of the maximum and minimum error values ​​from the first to 6nth error values ​​for the offset rotation position. As described above, the offset rotation position can be determined according to equation 4.

[0069] In step S50, the control unit 30 can correct the zero-point rotation position by adding the offset rotation position to the zero-point rotation position.

[0070] In step S60, the control unit 30 can determine a hysteresis compensation rotary position based on preset hysteresis information from the motor position sensor 20 and correct the hysteresis characteristic by adding the hysteresis compensation rotary position to the offset-corrected zero-point rotary position.

[0071] Then, in step S70, the control unit 30 can reset the motor position sensor 20 to the hysteresis-corrected zero-point rotation position.

[0072] Fig. Figure 5 is a table that describes a process for performing a synchronization operation by applying the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention. With reference to Fig. 5 The process for performing a synchronization operation by applying the method for synchronizing a servo steering motor with a motor position sensor according to the embodiment of the present invention is described in detail below.

[0073] This section describes, as an example, a servo steering motor 10, whose rotor has an eight-pole permanent magnet with four pole pairs, and a motor position sensor 20 with a resolution of 14 bits. Because the number of pole pairs is four, the process for detecting and storing the actual rotational position of the aligned rotor can be repeated four times during one electrical angular cycle. Therefore, a total of 24 actual rotational positions can be detected and stored in the control unit 30. Fig. Figure 5 shows that the rotational positions are expressed as LSB values ​​based on electrical and mechanical angles. Fig. 5 gives segAngle LSB refAngle displays the first to 24th actual rotation positions. LSB first to 24th reference rotation positions and gives errAngle LSB First to 24th error values ​​again.

[0074] The zero-point rotation position can be determined by subtracting one rotation position LSB corresponding to an electrical angle of 120° from the first actual rotation position. Substituting the first actual rotation position of 3761.1 into equation 1, the zero-point rotation position can be set to 2395.8.

[0075] The first to 24th reference rotation positions can be determined according to Equation 2 based on the first actual rotation position and the number of pole pairs, and the first to 24th error values ​​can be determined according to Equation 3. The values ​​are given in the table of Fig. 5 shown.

[0076] Therefore, the offset rotation position can be determined according to equation 4. Because the maximum error value is 23.8 and the minimum error value is -1.4, the offset rotation position can be set to 11.2.

[0077] The hysteresis compensation rotation position can be determined according to equation 5. If the hysteresis information of the motor rotation sensor is assumed to be set to 16, the hysteresis compensation rotation position can be set to 8 according to equation 5.

[0078] Therefore, if the offset and hysteresis characteristics are reflected into the zero-point rotation position, i.e., if the zero-point rotation position, the offset rotation position, and the hysteresis compensation rotation position are added, 2415 can be calculated as the final zero-point rotation position of the rotor. The control device 30 can reset the motor position sensor 20 by setting the final zero-point rotation position of 2415 to the motor position sensor 20. Specifically, the final zero-point rotation position, calculated as an LSB value of 2415, can be set as 14 bits to the motor position sensor via the SPI bus (MOSI).

[0079] Although this embodiment eliminates a multitude of measuring devices for synchronizing the initial rotational position of the servo steering motor with the motor position sensor, the logic for resetting the motor position sensor can be applied by determining the zero-point rotational position of the rotor in the servo steering motor. This reduces manufacturing time and costs and eliminates errors measured during synchronization, thereby improving motor control performance.

Claims

[1] A method for synchronizing a power steering motor (10) with a motor position sensor (20), comprising: sequentially aligning, by a control device (30), a rotor of the power steering motor (10) by sequentially applying preset three-phase current pulses to the power steering motor (10), wherein the three-phase current pulses correspond to an electrical angular cycle of the rotor of the power steering motor (10), wherein the one electrical angular cycle comprises six stages in which the electrical angle of the rotor is sequentially increased by 60°, and wherein the alignment of the rotor of the power steering motor (10) is repeated in accordance with the number n of pole pairs, and detecting the actual rotational position of the aligned rotor by the motor position sensor (20); Determining a zero-point rotational position of the rotor based on the actual rotational position, wherein the control device (30) determines the zero-point rotational position of the rotor by subtracting a rotational position value corresponding to an electrical angle of 120° from a first actual rotational position from the first to 6n-th actual rotational positions determined in accordance with the order of detecting and storing the actual rotational positions; Determining first to 6n-th reference rotational positions corresponding to the first to 6n-th actual rotational positions based on the first actual rotational position and the number n of pole pairs of the power steering motor, setting differences between the first to 6n-th actual rotational positions and the first to 6n-th reference rotational positions to first to 6n-th error values, respectively, and setting the average of the maximum error value and the minimum error value from the first to 6n-th error values ​​to an offset rotational position; Correcting the zero point rotation position by adding the offset rotation position to the zero point rotation position; Determining, by the control device (30), a hysteresis compensation rotational position based on preset hysteresis information of the motor position sensor (20) and performing hysteresis compensation by adding the hysteresis compensation rotational position to the offset-corrected zero-point rotational position; and Resetting, by the control device (30), the motor position sensor (20) to the hysteresis compensated zero point rotation position. [2] The method according to claim 1, wherein, when aligning the rotor of the power steering motor (10), the control device (30) repeatedly detects the actual rotational position of the rotor with a preset number of repetitions when the rotor is aligned and stores the average of the detected actual rotational position values. [3] Device for synchronizing a power steering motor (10) with a motor position sensor (20), comprising: a motor position sensor (20) configured to detect a rotational position of a power steering motor (10); and a control device (30) configured to sequentially align a rotor of the power steering motor (10) by sequentially applying preset three-phase current pulses to the power steering motor (10), the three-phase current pulses corresponding to an electrical angular cycle of the rotor in the power steering motor (10), and to detect an actual rotational position of the aligned rotor by the motor position sensor (20), the one electrical angular cycle comprising six stages in which the electrical angle of the rotor is sequentially increased by 60°, and the control device (30) detects and stores the actual rotational position of the aligned motor with a number of repetitions corresponding to the number n of pole pairs during one electrical angular cycle, wherein the control device (30) is configured to determine a zero-point rotational position of the rotor based on the actual rotational position, wherein the control device (30) determines the zero-point rotational position of the rotor by subtracting a rotational position value corresponding to an electrical angle of 120° from a first actual rotational position from the first to 6n-th actual rotational positions determined in accordance with the order of detecting and storing the actual rotational positions, wherein the control device (30) is configured to determine first to 6n-th reference rotational positions corresponding to the first to 6n-th actual rotational positions based on the first actual rotational position and the number n of pole pairs, to set differences between the first to 6n-th actual rotational positions and the first to 6n-th reference rotational positions to first to 6n-th error values, and to set the average of the maximum error value and the minimum error value from the first to 6n-th error values ​​to an offset rotational position, wherein the control device (30) is configured to correct the zero-point rotation position by adding the offset rotation position to the zero-point rotation position, wherein the control device (30) determines a hysteresis compensation rotational position based on preset hysteresis information of the motor position sensor (20) and performs the hysteresis compensation by adding the hysteresis compensation rotational position to the offset-corrected zero-point rotational position, and wherein the control device (30) resets the motor position sensor (20) to the hysteresis-compensated zero-point rotational position. [4] The apparatus of claim 3, wherein, when the rotor is aligned, the control means (30) detects the actual rotational position of the rotor with a preset number of repetitions and stores the average of the detected actual rotational position values.

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