Motor and control method and device thereof, storage medium and computer program product

Abstract

The invention belongs to the technical field of motors, and discloses a motor and a control method and device thereof, a storage medium and a computer program product, and the method comprises the steps: injecting a set pulse current into a three-phase winding of the motor under the condition that a starting instruction of the motor is received; under the condition that the set pulse current is injected into the three-phase winding of the motor, the three-phase current of the motor is obtained; determining a magnetic field direction angle of a rotor of the motor according to the three-phase current of the motor; and controlling the rotor to rotate according to the magnetic field direction angle of the rotor so as to start the motor. According to the scheme, the pulse current is injected into the three-phase winding of the motor before the motor is started, the magnetic field direction angle of the rotor is determined, the rotor is dragged to rotate at the maximum torque, and the motor is quickly and reliably started.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to a control method, device, motor, storage medium and computer program product of a motor, and more particularly to a method, device, motor, storage medium and computer program product for identifying the magnetic field direction of a permanent magnet motor rotor position. Background Art

[0002] In the control of a motor, in sensorless field-oriented control (FOC), the position of the rotor is estimated by detecting the phase current of the motor and analyzing the back electromotive force information of the motor in the decoupled phase current. However, when the motor starts, since the rotor of the motor is stationary in the initial state, there is no back electromotive force information in the phase current at this time, so the specific position of the motor rotor cannot be estimated, which affects the starting reliability of the motor.

[0003] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The object of the present invention is to provide a control method, device, motor, storage medium and computer program product of a motor, so as to solve the problem that in sensorless FOC of a motor, it is necessary to analyze the back electromotive force information of the motor according to the phase current of the motor to estimate the rotor position, but the rotor is stationary when the motor starts and the rotor position cannot be estimated, which affects the starting reliability of the motor, and achieve the effect of determining the magnetic field direction angle of the rotor by injecting pulsed current into the three-phase windings of the motor before starting the motor, realizing the rotation of the rotor by the maximum torque, and enabling the motor to start quickly and reliably.

[0005] The present invention provides a control method of a motor, the motor has a stator and a rotor, and the stator has three-phase windings; the control method of the motor includes: injecting a set pulsed current into the three-phase windings of the motor when receiving a start instruction of the motor; acquiring the three-phase current of the motor when the set pulsed current has been injected into the three-phase windings of the motor; determining the magnetic field direction angle of the rotor according to the three-phase current of the motor; controlling the rotation of the rotor according to the magnetic field direction angle of the rotor so as to start the motor.

[0006] In some embodiments, injecting a set pulse current into the three-phase windings of the motor includes: injecting a set pulse current into the three-phase windings of the motor at set time intervals within a set detection period; correspondingly, acquiring the three-phase current of the motor includes: acquiring a set of the three-phase current of the motor within a set detection period; determining the magnetic field direction angle of the rotor according to the three-phase current of the motor includes: determining the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor.

[0007] In some embodiments, the drive system of the motor has an IPM; within the set detection period, in the range of the stator current magnetic field direction angles, the number of the stator current magnetic field direction angles is M and they are arranged in ascending order, where M is a positive integer; injecting a set pulse current into the three-phase windings of the motor at set time intervals within a set detection period includes: within the set detection period, sending a first set of PWM signals to control the IPM according to the first stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, so as to inject a set pulse current into the three-phase windings of the motor; when the three-phase current of the motor is acquired for the first time, closing the output of the first set of PWM signals; after the set time interval, sending a second set of PWM signals to control the IPM according to the next stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, so as to inject a set pulse current into the three-phase windings of the motor again; when the three-phase current of the motor is acquired for the second time, closing the output of the second set of PWM signals; cycling in turn until the three-phase current of the motor is acquired for the Mth time, and after obtaining the three-phase current of the motor acquired for the Mth time, closing the output of the Mth set of PWM signals.

[0008] In some embodiments, among the first set of PWM signals to the Mth set of PWM signals, each set of PWM signals includes: six-way PWM signals with a duration of N, where N is a positive integer; acquiring a set of the three-phase current of the motor within a set detection period includes: when a set of PWM signals among the first set of PWM signals to the Mth set of PWM signals is sent to control the IPM according to the next stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, so as to inject a set pulse current into the three-phase windings of the motor again, after all N PWM signals in the set of PWM signals are sent, acquiring the three-phase current of the motor; thus, within a set detection period, the three-phase current of the motor acquired for the first time to the three-phase current of the motor acquired for the Mth time is used as a set of the three-phase current of the motor.

[0009] In some embodiments, the number of PWM signals in each group of PWM signals, the magnitude of the set vector voltage, and the magnitude of the set time interval are all determined according to the period of the PWM signals in each group of PWM signals and the inductance magnitude of the three-phase windings of the motor.

[0010] In some embodiments, within the range of the stator current magnetic field direction angles during the set detection period, the number of the stator current magnetic field direction angles is M, and they are arranged in ascending order, where M is a positive integer; determining the rotor magnetic field direction angle according to a set of the three-phase currents of the motor includes: determining the maximum current in a set of the three-phase currents of the motor, denoted as the maximum current of the motor; within the range of the stator current magnetic field direction angles, determining one of the stator current magnetic field direction angles corresponding to the maximum current of the motor, denoted as the actual stator current magnetic field direction angle; and determining the angle within the set error range of the actual stator current magnetic field direction angle as the rotor magnetic field direction angle.

[0011] Matched with the above method, on the other hand, the present invention provides a control device for a motor. The motor has a stator and a rotor, and the stator has three-phase windings. The control device of the motor includes: a control unit configured to inject a set pulse current into the three-phase windings of the motor when receiving a start instruction of the motor; an acquisition unit configured to acquire the three-phase currents of the motor when a set pulse current has been injected into the three-phase windings of the motor; the control unit is further configured to determine the rotor magnetic field direction angle according to the three-phase currents of the motor; and the control unit is further configured to control the rotation of the rotor according to the rotor magnetic field direction angle so as to start the motor.

[0012] In some embodiments, the control unit injecting a set pulse current into the three-phase windings of the motor includes: injecting a set pulse current into the three-phase windings of the motor at a set time interval during a set detection period; correspondingly, the acquisition unit acquiring the three-phase currents of the motor includes: acquiring a set of the three-phase currents of the motor during a set detection period; and the control unit determining the rotor magnetic field direction angle according to the three-phase currents of the motor includes: determining the rotor magnetic field direction angle according to a set of the three-phase currents of the motor.

[0013] In some embodiments, the drive system of the motor has an IPM; within the set detection period, in the range of the stator current magnetic field direction angles, the number of the stator current magnetic field direction angles is M, and they are arranged in ascending order, where M is a positive integer; the control unit, within the set detection period, injects a set of pulsed currents into the three-phase windings of the motor at set time intervals, including: within the set detection period, according to the first stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, sending out a first set of PWM signals to control the IPM, so as to inject the set pulsed currents into the three-phase windings of the motor; when the three-phase currents of the motor are first acquired, turning off the output of the first set of PWM signals; after the set time interval, according to the next stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, sending out a second set of PWM signals to control the IPM, so as to inject the set pulsed currents into the three-phase windings of the motor again; when the three-phase currents of the motor are second acquired, turning off the output of the second set of PWM signals; cycling in sequence until the three-phase currents of the motor are M-th acquired, after obtaining the three-phase currents of the motor acquired for the M-th time, turning off the output of the M-th set of PWM signals.

[0014] In some embodiments, among the first set of PWM signals to the M-th set of PWM signals, each set of PWM signals includes six PWM signals with a continuous number of N, where N is a positive integer; the acquisition unit, within the set detection period, acquires a set of the three-phase currents of the motor, including: when, according to the next stator current magnetic field direction angle in the range of the stator current magnetic field direction angles and a set vector voltage, any set of PWM signals among the first set of PWM signals to the M-th set of PWM signals is sent out to control the IPM, so as to inject the set pulsed currents into the three-phase windings of the motor again, after all N PWM signals in the any set of PWM signals are sent out, acquiring the three-phase currents of the motor; thus, within the set detection period, the three-phase currents of the motor acquired for the first time to the three-phase currents of the motor acquired for the M-th time are used as a set of the three-phase currents of the motor.

[0015] In some embodiments, the number of PWM signals in each set of PWM signals, the magnitude of the set vector voltage, and the magnitude of the set time interval are all determined by the control unit according to the period of the PWM signals in each set of PWM signals and the inductance magnitude of the three-phase windings of the motor.

[0016] In some embodiments, within the set detection period, among the angular range of the current magnetic field direction of the stator, the number of the angular values of the current magnetic field direction of the stator is M, and they are arranged in ascending order, where M is a positive integer; the control unit determines the magnetic field direction angle of the rotor according to a set of three-phase currents of the motor, including: determining the maximum current in a set of three-phase currents of the motor, denoted as the maximum current of the motor; within the angular range of the current magnetic field direction of the stator, determining one angular value of the current magnetic field direction of the stator corresponding to the maximum current of the motor, denoted as the actual current magnetic field direction angle of the stator; and determining the angular value within the set error range of the actual current magnetic field direction angle of the stator as the magnetic field direction angle of the rotor.

[0017] Matched with the above device, on the other hand, the present invention provides a motor, including: the control device of the motor described above.

[0018] Matched with the above method, on the other hand, the present invention provides a storage medium, where the storage medium includes a stored program, and when the program runs, it controls the device where the storage medium is located to execute the steps of the control method of the motor described above.

[0019] Matched with the above method, on the other hand, the present invention provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the steps of the control method of the motor described above.

[0020] Thus, in the solution of the present invention, before the motor starts, according to the set detection period, within at least one set detection period, a set of PWM signals is sent to the IPM of the motor one by one according to the constant-amplitude vector voltage, the set interval time, and the preset stator current magnetic field direction angle, so as to inject pulsed current into the three-phase windings of the motor; and the vector voltage and the three-phase currents of the motor at each stator current magnetic field direction angle are recorded to obtain a set of three-phase currents of the motor within at least one set detection period; the magnitudes of a set of three-phase currents of the motor are compared, and according to the stator current magnetic field direction angle corresponding to the maximum current in a set of three-phase currents of the motor, the rotor magnetic field direction angle is determined; the rotation of the rotor is controlled according to the rotor magnetic field direction angle to achieve the maximum torque to drive the rotor to rotate, so that the motor starts; thereby, by injecting pulsed current into the three-phase windings of the motor before the motor starts, the rotor magnetic field direction angle is determined, and the maximum torque is used to drive the rotor to rotate, so that the motor starts quickly and reliably.

[0021] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention.

[0022] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Brief Description of the Drawings

[0023] Figure 1 It is a schematic flow chart of an embodiment of the control method of the motor of the present invention; Figure 2 It is a schematic flow chart of an embodiment of injecting a set pulse current into the three-phase windings of the motor in the method of the present invention; Figure 3 It is a schematic flow chart of an embodiment of determining the magnetic field direction angle of the rotor in the method of the present invention; Figure 4 It is a schematic structural diagram of an embodiment of the control device of the motor of the present invention; Figure 5 It is a schematic structural diagram of the drive system of the permanent magnet motor; Figure 6 It is a schematic diagram of the curve of the current of one phase of the motor changing with the angle; Figure 7 It is a schematic diagram of the curve of one path of PWM signal of the motor changing with the angle; Figure 8 It is a schematic diagram of the duty cycle of the PWM signal within one period T; Figure 9 It is Table 1 for presetting the magnetic field direction angle of the stator current; Figure 10 It is Table 2 for presetting the magnetic field direction angle of the stator current.

[0024] In combination with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows: 102 - Acquisition unit; 104 - Control unit. Detailed Embodiments

[0025] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It is considered that in the sensorless FOC of a motor, it is necessary to analyze the back electromotive force information of the motor based on the phase current of the motor to estimate the rotor position. However, when the motor starts, the rotor is stationary and the rotor position cannot be estimated, which affects the starting reliability of the motor. Specifically, due to the inability to accurately determine the position of the rotor, the motor may not be able to effectively establish a rotating magnetic field, resulting in a difficult or abnormal starting process, or there may be a large current impact during starting, causing the motor and the drive system to bear additional pressure, and even may cause damage to mechanical components or overheating of electrical components.

[0027] In addition, before the sensorless motor starts, the specific position of the rotor is unknown, and the angle between the magnetic field generated by the stator and the rotor magnetic field is not optimal. Therefore, the magnetic field generates a relatively small drag torque. To solve this problem, in related solutions, a rotating magnetic field at a certain speed is used to drag the rotor. However: if the speed of the stator rotating magnetic field is too fast, it is easy to have the problem of the rotor getting out of step with the stator rotating magnetic field and starting failure; if the dragging speed is slow, there are problems of long starting time and large dragging current.

[0028] Therefore, the solution of the present invention proposes a control method for a motor, specifically a method for identifying the magnetic field direction of the rotor of a permanent magnet motor. Before the motor starts, a pulsed current is injected into the three-phase windings of the motor to identify the specific position of the rotor, so as to determine the optimal rotating magnetic field angle; at the start of the motor, the rotor can be dragged with a small current at the optimal rotating magnetic field angle to achieve the maximum torque to drag the rotor to rotate, accelerate the rotation speed of the rotor, quickly start the motor, and improve the starting reliability of the motor.

[0029] According to an embodiment of the present invention, a control method for a motor is provided, as Figure 1 shown in the flowchart of an embodiment of the method of the present invention. The motor has a stator and a rotor, and the stator has three-phase windings; in the solution of the present invention, as Figure 1 shown, the control method of the motor includes: step S110 to step S140.

[0030] In step S110, when receiving the start instruction of the motor, that is, when it is necessary to start the motor, a set pulsed current is injected into the three-phase windings of the motor.

[0031] In step S120, when a set pulsed current has been injected into the three-phase windings of the motor, the three-phase current of the motor is acquired.

[0032] In step S130, according to the three-phase current of the motor, the magnetic field direction angle of the rotor is determined.

[0033] In step S140, the rotor is controlled to rotate according to the magnetic field direction angle of the rotor so as to start the motor.

[0034] A rotor position magnetic field direction identification scheme proposed by the solution of the present invention. Before the motor starts, the specific position of the rotor is first identified, and the rotor is dragged at the optimal rotating magnetic field angle to solve the problem that the motor is difficult to start or cannot start normally. The solution of the present invention can not only effectively identify the rotor position accurately in the motor static state and improve the starting reliability of the motor, but also does not need to use Hall effect sensors or encoders to detect the position information of the rotor, thus reducing the cost of the controller.

[0035] In some embodiments, in step S110, injecting a set pulse current into the three-phase windings of the motor includes: injecting a set pulse current into the three-phase windings of the motor at a set time interval within a set detection period.

[0036] Correspondingly, in step S120, obtaining the three-phase current of the motor includes: obtaining a set of the three-phase current of the motor within a set detection period.

[0037] In step S130, determining the magnetic field direction angle of the rotor according to the three-phase current of the motor includes: determining the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor.

[0038] Specifically, in the case of receiving the start instruction of the motor, that is, when it is necessary to start the motor, a set pulse current is injected into the three-phase windings of the motor at a set time interval within a set detection period; wherein, the start instruction of the motor is an instruction for starting the motor. After injecting the set pulse current into the three-phase windings of the motor, the three-phase current of the motor is obtained; thus, a set of the three-phase current of the motor is obtained within a set detection period. The magnetic field direction angle of the rotor is determined according to a set of the three-phase current of the motor. The rotation of the rotor is controlled according to the magnetic field direction angle of the rotor to start the motor.

[0039] The solution of the present invention injects a pulse current into the three-phase windings of the motor in the motor static state, uses the self-inductance coefficient of the motor phase inductance to identify the motor rotor position, accurately obtains the rotor magnetic field direction position information to determine the optimal rotating magnetic field angle; at the beginning of the motor start, the rotor can be dragged at the optimal rotating magnetic field angle with a smaller current, realizing the maximum torque to drag the rotor to rotate, accelerating the rotation speed of the rotor, enabling the motor to start quickly, and realizing a faster and smoother start of the motor. Among them, the injected current and the injected voltage can be equivalent.

[0040] In some embodiments, the drive system of the motor has an IPM; within the set detection period, among the angular range of the current magnetic field direction of the stator, the number of the angular values of the current magnetic field direction of the stator is M, and they are arranged in ascending order, where M is a positive integer.

[0041] In step S110, within the set detection period, at set time intervals, the specific process of injecting a set pulse current into the three-phase windings of the motor is as follows in the following exemplary description.

[0042] The following combines Figure 2 The schematic flowchart of an embodiment of injecting a set pulse current into the three-phase windings of the motor in the method of the present invention shown in the figure further illustrates the specific process of injecting a set pulse current into the three-phase windings of the motor in step S110, including: step S210 to step S230.

[0043] Step S210, within the set detection period, according to the first angular value of the current magnetic field direction of the stator within the angular range of the current magnetic field direction of the stator and according to a set vector voltage, issue a first set of PWM signals to control the IPM (specifically, control the turning on and off of the power transistors in the IPM), so as to realize injecting a set pulse current into the three-phase windings of the motor, in order to: when the set pulse current has been first injected into the three-phase windings of the motor, obtain the three-phase current of the motor for the first time, and get the three-phase current of the motor obtained for the first time; when the three-phase current of the motor has been first obtained, turn off the output of the first set of PWM signals.

[0044] Step S220, after the set time interval, according to the next angular value of the current magnetic field direction of the stator within the angular range of the current magnetic field direction of the stator and according to a set vector voltage, issue a second set of PWM signals to control the IPM (specifically, control the turning on and off of the power transistors in the IPM), so as to realize injecting a set pulse current into the three-phase windings of the motor again, in order to: when the set pulse current has been second injected into the three-phase windings of the motor, obtain the three-phase current of the motor for the second time, and get the three-phase current of the motor obtained for the second time; when the three-phase current of the motor has been second obtained, turn off the output of the second set of PWM signals.

[0045] Step S230, loop in sequence until the three-phase current of the motor has been obtained for the Mth time, and after getting the three-phase current of the motor obtained for the Mth time, turn off the output of the Mth set of PWM signals.

[0046] Figure 5 is a schematic structural diagram of a drive system for a permanent magnet motor. As Figure 5As shown in the figure, in the drive system of a permanent magnet motor, the DC bus voltage Vdc is processed by an Intelligent Power Module (IPM) and then supplies power to the three-phase windings of the motor M (i.e., the winding of phase U, the winding of phase V, and the winding of phase W). The IPM includes a three-phase full-bridge inverter bridge composed of three upper switches (such as power transistor Q1, power transistor Q3, and power transistor Q5) and three lower switches (such as power transistor Q2, power transistor Q4, and power transistor Q6). The control chip of the drive system drives the three upper switches and the three lower switches to act after passing through the drive module. Specifically, for the three upper switches, the drive module outputs signal Up to drive power transistor Q1, outputs signal Vp to drive power transistor Q3, and outputs signal Wp to drive power transistor Q5; for the three lower switches, the drive module outputs signal Un to drive power transistor Q2, outputs signal Vn to drive power transistor Q4, and outputs signal Wn to drive power transistor Q6.

[0047] In Figure 5 In the example shown, the current detection module detects the three-phase current of the motor (such as the current Is of one phase of the motor), and outputs it to the control chip after passing through the phase current processing module. The control chip outputs drive signals according to the three-phase current of the motor, and makes the drive signals drive the three upper switches and the three lower switches to act after passing through the drive module. Among them, a resistor or a current sensor can be used for current detection. Specifically, the current detection module includes a current sensor (such as a current sensor with the model ACS770LCB-100B-P) or a sampling resistor, and a voltage differential amplification circuit and a filtering circuit composed of an operational amplifier (such as an operational amplifier with the model OPA4374AID), resistors, and capacitors. Among them, the phase current processing module includes the amplification, filtering, and transmission of the phase current, and realizes the transmission of the current containing the rotor information to the chip, and the chip extracts the rotor information in the current.

[0048] In the solution of the present invention, combined with Figure 5 the example shown, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor includes: Step 1: When the motor receives a start command, the control chip issues six PWM signals (such as signal Up, signal Un, signal Vp, signal Vn, signal Wp, signal Wn) according to a pre-set stator current magnetic field direction angle (such as Figure 9 Table 1 shown) and a constant amplitude vector voltage Vs(x) to control the on and off of the power transistors of the IPM.

[0049] Figure 6 It is a schematic diagram of the curve of the current of one phase of the motor changing with the angle. Figure 6It can display the variation of the current Is of one phase of the motor with the angle, such as the variation of the current Is of one phase of the motor with angles r = 0°, r = 60°, r = 120°, r = 180°, r = 240°, and r = 300°. Because of the rotor position information implicit in the current Is of one phase of the motor, a constant PWM pulse is injected at a certain angular variation (which can be understood as a voltage with a constant magnitude and a direction that varies with r). Due to the influence of the rotor position, the magnitude of the current Is generated by the injected voltage will vary with the angle r. Through this variation difference of the current, the rotor position information can be extracted.

[0050] Among them, the angle (r / °) specifically refers to the stator current magnetic field angle (i.e., the angle of the stator current magnetic field direction), which is also the rotor rotating magnetic field angle. The magnetic field generated by the stator current: The three-phase currents (U, V, and W phases) in the stator winding respectively generate three magnetic fields with a phase difference of 120°. For example, the phase angle of the U phase is 0°, the phase angle of the V phase is 120°, and the phase angle of the W phase is 240°. The direction of the rotating magnetic field: Due to the phase difference of the three-phase currents, the generated magnetic field will rotate in the counterclockwise direction; if the currents of any two coils are exchanged, the rotating direction of the magnetic field will reverse. The rotating direction of the rotor: The rotating direction of the rotor is the same as the direction of the rotating magnetic field generated by the stator. Therefore, by adjusting the phase difference of the stator current, the rotating direction of the rotor can be controlled. The angle r is the electrical angle, and the electrical angle = the number of pole pairs of the motor * the mechanical angle.

[0051] Figure 7 It is a schematic diagram of the curve of one path of the pulse width modulation (PWM) signal of the motor varying with the angle. Figure 7 It can display the variation of one path of the PWM signal (i.e., the phase PWM) of the motor with the angle, such as the variation of one path of the PWM signal of the motor with angles r = 0°, r = 60°, r = 120°, r = 180°, r = 240°, and r = 300°. The PWM injected into the motor winding is injected in the r-angle direction. The PWM duty cycle can be understood as the voltage magnitude, and the r angle can be understood as the voltage direction. The purpose is to make the generated current affected by the rotor position, so as to extract the rotor position information.

[0052] In the solution of the present invention, the number of PWMs generating the phase current pulses is adjustable. For example, the number of PWMs N = 2 can be adjusted to adapt to motors with different inductances. N represents the duration of the applied voltage. Because for different motors, the winding inductances are different. The smaller the inductance, the faster the current rises. Therefore, for a motor with a small inductance, N should be taken small to avoid magnetic saturation due to excessive current. For a motor with a larger inductance, N should be taken larger because if N is too small, the current will be relatively small and it will be difficult to detect.

[0053] Figure 8It is a schematic diagram of the duty cycle of the PWM signal within one period T. Figure 8 It can display the duty cycle duty of the PWM signal within one period T.

[0054] Step 2: After sending out six-way PWM signals (such as signal Up, signal Un, signal Vp, signal Vn, signal Wp, signal Wn) to control the turning on and off of the power tubes of the IPM, the phase current has become large enough to be detected. The control chip detects the three-phase current of the motor during this process and stores the stored current as shown in Table 1.

[0055] Step 3: After the detection is completed, close the PWM output duration Δt. When the motor winding current drops to 0, then send the PWM of the next angle to control the turning on and off of the IPM.

[0056] Step 4: When the control chip completes the sending of all-angle PWM according to Table 1 and stores the detected motor phase current.

[0057] In the solution of the present invention, a pulsed current is injected into the three-phase windings of the motor. Therefore, at the start of the motor, the rotor can be rotated with a small current and the maximum torque, solving the problem that the rotor position cannot be recognized in the static state of the motor.

[0058] In some embodiments, among the first group of PWM signals to the Mth group of PWM signals, each group of PWM signals includes six-way PWM signals with a continuous number of N, and N is a positive integer.

[0059] In step S120, within the set detection period, obtaining a set of the three-phase current of the motor includes: at the next stator current magnetic field direction angle within the set stator current magnetic field direction angle range and according to the set vector voltage, sending any group of PWM signals from the first group of PWM signals to the Mth group of PWM signals to control the IPM (specifically, controlling the turning on and off of the power tubes in the IPM), to realize injecting the set pulsed current into the three-phase windings of the motor again. After all N PWM signals in the any group of PWM signals are sent, obtaining the three-phase current of the motor; thus, within the set detection period, taking the three-phase current of the motor obtained for the first time to the three-phase current of the motor obtained for the Mth time as a set of the three-phase current of the motor.

[0060] In the solution of the present invention, in combination with Figure 5 As shown in the example, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor further includes: In step 1, within one current detection period (stator current magnetic field direction angle from 0° to 360°), the continuous number N of PMW outputs is constant and cannot be changed. After the IPM is turned on, the magnitude of the motor phase current increases rapidly; after the IPM is turned off, the phase current gradually decreases.

[0061] In step 2, within several consecutive PWMs (such as N PWMs), the phase current has become large enough to be detected. The control chip detects the three-phase current of the motor during this process and stores the stored current as shown in Table 1.

[0062] The solution of the present invention injects pulsed current into the three-phase windings of the motor to accurately identify the position of the rotor magnetic field direction.

[0063] In some embodiments, the number of PWM signals in each group of PWM signals (i.e., the value of N in each group of PWM signals), the magnitude of the set vector voltage, and the magnitude of the set time interval are all determined according to the period of the PWM signals in each group of PWM signals and the inductance magnitude of the three-phase windings of the motor; that is, the value of N, the magnitude of the set vector voltage, and the magnitude of the set time interval are all matched with the period of the PWM signals and the inductance magnitude of the three-phase windings of the motor.

[0064] Referring to the above steps 1 to 4, wherein, the continuous number N of PMW outputs (as Figure 7 shown), the magnitude of the vector voltage Vs(x), and the off-PWM duration Δt can all be adjusted according to the period T of the PWM and the inductance magnitude of the motor, so that the magnitude of the motor phase current can be detected by the control chip without overcurrent occurring. By observing the motor winding current through an oscilloscope or monitoring software, if a PWM is injected and the current generated in the winding is less than the detection threshold value, then the number N needs to be increased or the duty ratio needs to be increased. If the current is greater than the overcurrent protection value, the number N needs to be decreased or the duty ratio needs to be decreased. In the solution of the present invention, the pulse interval time is adjustable to optimize the motor startup noise.

[0065] In some embodiments, within the set detection period, in the range of the stator current magnetic field direction angle, the number of the stator current magnetic field direction angles is M and arranged in ascending order, and M is a positive integer.

[0066] In step S130, the specific process of determining the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor is as follows in the following exemplary description.

[0067] The following combines Figure 3Schematic flowchart of an embodiment for determining the magnetic field direction angle of the rotor in the method of the present invention, further illustrating the specific process of determining the magnetic field direction angle of the rotor in step S130, including: steps S310 to S330.

[0068] Step S310, determine the maximum current among the three-phase currents of a group of the motors, and denote it as the maximum current of the motors.

[0069] Step S320, within the range of the current magnetic field direction angles of the stator, determine a current magnetic field direction angle of the stator corresponding to the maximum current of the motors, and denote it as the actual current magnetic field direction angle of the stator.

[0070] Step S330, determine the angle within the set error range of the actual current magnetic field direction angle of the stator as the magnetic field direction angle of the rotor.

[0071] In the solution of the present invention, in combination with Figure 5 the example shown, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor further includes: In step 4, when the control chip completes the sending of all angle PWMs according to Table 1 and stores the detected motor phase currents. By comparing the magnitudes of the currents at different angles, it is possible to identify at which angle the motor rotor is located, that is, to identify the position of the rotor magnetic field direction. During an injection period, the average value of each phase current is taken; by comparing the magnitudes of the three-phase currents, the rotor position can be determined.

[0072] Figure 9 Table 1 for presetting the current magnetic field direction angles of the stator. As shown in Table 1, in the data table for presetting the current magnetic field direction angles of the stator, the corresponding relationships between the angles (such as angle r), the vector voltages, and the stored currents are stored. For example: when the angle = 0°, the vector voltage is Vs(x), and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x), and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x), and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x), and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x), and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x), and the stored current is Is_300. During one cycle, the magnitude of the vector voltage remains unchanged at Vs(x), but the direction changes according to the angle r.

[0073] For example: The control chip outputs a set number of 6 channels, such as 3 PWM waves, at an angle of 0° and at a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM to turn on and off. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration Δt is turned off. The duration Δt can specifically be two PWM wave periods. It can specifically be determined according to the winding current situation; Δt is equal to or greater than the time when the winding current drops to 0 after the stop injection of the PWM wave. Then the control chip outputs a set number of 6 channels, such as 3 PWM waves, at an angle of 60° and at a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM to turn on and off. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration Δt is turned off. Then, at an angle of 120°, a set number of 6 channels, such as 3 PWM waves, are output at a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM switch. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration Δt is turned off. Similarly, the PWM output and turn-off at angles such as 180°, 240°, and 300° of the motor are completed in the above manner, and the detected current is stored.

[0074] When Figure 9 After all the angles in Table 1 shown are output, the control chip compares the magnitudes of the stored currents Is_0, Is_60, Is_120, Is_180, Is_240, and Is_300. Whichever angle corresponds to the largest current, the rotor magnetic field is within that angle ± a set angle, such as ±30°. For example, if the current Is at 60° is the largest, then the direction of the rotor magnetic field is within the angle range of 60° ± 30°.

[0075] The solution of the present invention realizes the identification of the specific position of the rotor before the motor starts, so that the included angle between the magnetic field generated by the stator and the rotor magnetic field is optimal, and the rotor is rotated with a smaller current and the maximum torque, thereby realizing a fast starting speed and a high starting success rate of the motor, and solving the problems of high starting failure rate, large starting current, large vibration, and long starting time in the related solutions. Because by injecting a pulsed voltage, the position of the rotor is already known through the generated current, which is equivalent to knowing the rotor magnetic field. Then when starting at this time, the magnetic field generated by the winding and the rotor magnetic field can also be known. By making the direction of the magnetic field generated by the winding close to 90° to the rotor magnetic field, the starting torque is the largest and also optimal at this time. The magnetic field generated by the winding is determined by the algorithm in the chip and is also artificially designed.

[0076] In the solution of the present invention, before the motor starts, a pulsed current is injected into the three-phase windings of the motor to decouple the specific position of the rotor, and then the stator starts to drive the rotor at the optimal rotation angle, achieving a large driving torque, thus accelerating the rotation speed of the rotor and solving the problem of too long motor starting time. The solution of the present invention realizes a large starting torque of the motor by precisely controlling the motor starting, reduces unnecessary energy loss, and improves the overall efficiency of the motor and the drive system.

[0077] Figure 10 Table 2 for presetting the angle of the stator current magnetic field direction. As shown in Table 2, in the data table of the preset stator current magnetic field direction angle, there is a corresponding relationship between the angle (such as angle r), the vector voltage, and the stored current. As Figure 10 shown in Table 2, the current magnetic field angle can cycle through multiple periods or be subdivided for the angle. Theoretically, one period is sufficient, but in some cases, to troubleshoot interference, several periods can be detected to observe whether the values obtained from these periods are consistent to ensure that the position is definitely accurate. For example: in one period, when the angle = 0°, the vector voltage is Vs(x) and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x) and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x) and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x) and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x) and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x) and the stored current is Is_300. In the next period, when the angle = 0°, the vector voltage is Vs(x) and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x) and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x) and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x) and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x) and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x) and the stored current is Is_300.

[0078] In the solution of the present invention, there is no need to use a Hall effect sensor or an encoder to detect the position information of the rotor. An algorithm is adopted to realize the identification of the rotor position in the motor stationary state, accurately identify the initial position information of the rotor, and then accurately identify the position of the rotor magnetic field direction, realizing a faster and smoother start of the motor.

[0079] Adopting the technical solution of this embodiment, before the motor starts, according to a set detection period, within at least one set detection period, a group of PWM signals are sent to the IPM of the motor one by one according to a constant-amplitude vector voltage, a set interval time, and a preset stator current magnetic field direction angle, so as to inject pulsed current into the three-phase windings of the motor; and the vector voltage and the three-phase current of the motor are recorded at each stator current magnetic field direction angle, obtaining a group of three-phase currents of the motor within at least one set detection period; comparing the magnitudes of the group of three-phase currents of the motor, and determining the rotor magnetic field direction angle according to the stator current magnetic field direction angle corresponding to the maximum current in the group of three-phase currents of the motor; controlling the rotation of the rotor according to the rotor magnetic field direction angle, realizing the rotation of the rotor driven by the maximum torque, and starting the motor; thus, by injecting pulsed current into the three-phase windings of the motor before the motor starts, determining the rotor magnetic field direction angle, realizing the rotation of the rotor driven by the maximum torque, and enabling the motor to start quickly and reliably.

[0080] According to an embodiment of the present invention, there is also provided a control device for a motor corresponding to the control method of the motor. Refer to Figure 4 The structural schematic diagram of an embodiment of the device of the present invention as shown. The motor has a stator and a rotor, and the stator has three-phase windings; in the solution of the present invention, as Figure 4 shown, the control device of the motor includes: an acquisition unit 102 and a control unit 104.

[0081] Wherein, the control unit 104 is configured to inject a set pulsed current into the three-phase windings of the motor when receiving the start instruction of the motor, that is, when it is necessary to start the motor. For the specific functions and processes of this control unit 104, refer to step S110.

[0082] The acquisition unit 102 is configured to acquire the three-phase current of the motor when a set pulsed current has been injected into the three-phase windings of the motor. For the specific functions and processes of this control unit 104, refer to step S120.

[0083] The control unit 104 is further configured to determine the magnetic field direction angle of the rotor according to the three-phase current of the motor. For the specific functions and processes of this control unit 104, refer to step S130.

[0084] The control unit 104 is further configured to control the rotation of the rotor according to the magnetic field direction angle of the rotor, so as to start the motor. For the specific functions and processes of this control unit 104, refer to step S140.

[0085] A permanent magnet motor rotor position magnetic field direction identification solution proposed by the solution of the present invention. Before the motor starts, the specific position of the rotor is first identified, and the rotor is dragged at the optimal rotating magnetic field angle to solve the problem that the motor has difficulty starting or cannot start normally. The solution of the present invention not only effectively realizes the accurate identification of the rotor position in the static state of the motor, improving the starting reliability of the motor; but also does not require the use of Hall effect sensors or encoders to detect the position information of the rotor, reducing the cost of the controller.

[0086] In some embodiments, the control unit 104 injects a set pulse current into the three-phase windings of the motor, including: the control unit 104 is specifically further configured to inject a set pulse current into the three-phase windings of the motor at set time intervals within a set detection period.

[0087] Correspondingly, the acquisition unit 102 acquires the three-phase current of the motor, including: the acquisition unit 102 is specifically further configured to acquire a set of the three-phase current of the motor within a set detection period.

[0088] The control unit 104 determines the magnetic field direction angle of the rotor according to the three-phase current of the motor, including: the control unit 104 is specifically further configured to determine the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor.

[0089] Specifically: in the case of receiving the start instruction of the motor, that is, when it is necessary to start the motor, within a set detection period, inject a set pulse current into the three-phase windings of the motor at set time intervals; wherein, the start instruction of the motor is an instruction for starting the motor. In the case where a set pulse current has been injected into the three-phase windings of the motor, acquire the three-phase current of the motor; thus, within a set detection period, acquire a set of the three-phase current of the motor. Determine the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor. Control the rotation of the rotor according to the magnetic field direction angle of the rotor to start the motor.

[0090] The solution of the present invention injects a pulse current into the three-phase windings of the motor in the static state of the motor, uses the self-inductance coefficient of the motor phase inductance to identify the position of the motor rotor, accurately obtains the position information of the rotor magnetic field direction, and determines the optimal rotating magnetic field angle; at the beginning of the motor start, it can drag the rotor at a smaller current and at the optimal rotating magnetic field angle, realize the maximum torque to drag the rotor to rotate, make the rotor rotation speed faster, make the motor start quickly, and realize the faster and smoother start of the motor.

[0091] In some embodiments, the drive system of the motor has an IPM; within the set detection period, among the angular range of the stator current magnetic field direction, the number of the stator current magnetic field direction angles is M, and they are arranged in ascending order, where M is a positive integer.

[0092] The control unit 104 injects a set pulse current into the three-phase windings of the motor at set time intervals within the set detection period, including: The control unit 104 is specifically further configured to, within the set detection period, according to the first stator current magnetic field direction angle within the angular range of the stator current magnetic field direction and according to a set vector voltage, issue a first set of PWM signals to control the IPM (specifically, control the turning on and off of the power transistors in the IPM), so as to inject a set pulse current into the three-phase windings of the motor, in order to: when the set pulse current has been first injected into the three-phase windings of the motor, obtain the three-phase current of the motor for the first time, and get the three-phase current of the motor obtained for the first time; when the three-phase current of the motor has been first obtained, turn off the output of the first set of PWM signals. For the specific functions and processing of this control unit 104, refer to step S210.

[0093] The control unit 104 is specifically further configured to, after the set time interval, according to the next stator current magnetic field direction angle within the angular range of the stator current magnetic field direction and according to a set vector voltage, issue a second set of PWM signals to control the IPM (specifically, control the turning on and off of the power transistors in the IPM), so as to inject a set pulse current into the three-phase windings of the motor again, in order to: when the set pulse current has been second injected into the three-phase windings of the motor, obtain the three-phase current of the motor for the second time, and get the three-phase current of the motor obtained for the second time; when the three-phase current of the motor has been second obtained, turn off the output of the second set of PWM signals. For the specific functions and processing of this control unit 104, refer to step S220.

[0094] The control unit 104 is specifically further configured to loop in sequence until the three-phase current of the motor has been obtained for the Mth time, and after getting the three-phase current of the motor obtained for the Mth time, turn off the output of the Mth set of PWM signals. For the specific functions and processing of this control unit 104, refer to step S230.

[0095] Figure 5 is a schematic structural diagram of the drive system of a permanent magnet motor. As Figure 5As shown in the figure, in the drive system of a permanent magnet motor, the DC bus voltage Vdc is processed by an Intelligent Power Module (IPM) and then supplies power to the three-phase windings of the motor M (i.e., the winding of phase U, the winding of phase V, and the winding of phase W). The IPM includes a three-phase full-bridge inverter bridge composed of three upper switches (such as power transistor Q1, power transistor Q3, and power transistor Q5) and three lower switches (such as power transistor Q2, power transistor Q4, and power transistor Q6). The control chip of the drive system drives the three upper switches and the three lower switches to act after passing through the drive module. Specifically, for the three upper switches, the drive module outputs signal Up to drive power transistor Q1, outputs signal Vp to drive power transistor Q3, and outputs signal Wp to drive power transistor Q5; for the three lower switches, the drive module outputs signal Un to drive power transistor Q2, outputs signal Vn to drive power transistor Q4, and outputs signal Wn to drive power transistor Q6.

[0096] In Figure 5 In the example shown, the current detection module detects the three-phase current of the motor (such as the current Is of one phase of the motor), and outputs it to the control chip after passing through the phase current processing module. The control chip outputs drive signals according to the three-phase current of the motor, and makes the drive signals drive the three upper switches and the three lower switches to act after passing through the drive module. Among them, current detection can use a resistor or a current sensor. Specifically, the current detection module includes a current sensor (such as a current sensor of model ACS770LCB-100B-P) or a sampling resistor, and a voltage differential amplification circuit and a filtering circuit composed of an operational amplifier (such as an operational amplifier of model OPA4374AID), resistors, and capacitors.

[0097] In the solution of the present invention, combined with Figure 5 the example shown, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor includes: Step 1: When the motor receives a start command, the control chip issues six PWM signals (such as signal Up, signal Un, signal Vp, signal Vn, signal Wp, signal Wn) according to a pre-set stator current magnetic field direction angle (such as Figure 9 Table 1 shown) and a constant-amplitude vector voltage Vs(x) to control the on and off of the power transistors of the IPM.

[0098] Figure 6 It is a schematic diagram of the curve of the current of one phase of the motor changing with the angle. Figure 6 It can display the change situation of the current Is of one phase of the motor changing with the angle, such as the change situation of the current Is of one phase of the motor at angles r = 0 degrees, r = 60 degrees, r = 120 degrees, r = 180 degrees, r = 240 degrees, and r = 300 degrees.

[0099] Among them, the angle (r / degree) specifically refers to the magnetic field angle of the stator current (i.e., the angle of the stator current magnetic field direction), which is also the rotating magnetic field angle of the rotor. The magnetic field generated by the stator current: The three-phase currents (U, V, and W phases) in the stator winding respectively generate three magnetic fields with a phase difference of 120°. For example, the phase angle of the U phase is 0°, the phase angle of the V phase is 120°, and the phase angle of the W phase is 240°. Direction of the rotating magnetic field: Due to the phase difference of the three-phase currents, the generated magnetic field will rotate in the counterclockwise direction; if the currents of any two coils are exchanged, the rotating direction of the magnetic field will reverse. Rotating direction of the rotor: The rotating direction of the rotor is the same as the direction of the rotating magnetic field generated by the stator. Therefore, by adjusting the phase difference of the stator current, the rotating direction of the rotor can be controlled.

[0100] Figure 7 It is a schematic diagram of the curve of one path of the Pulse Width Modulation (PWM) signal of the motor varying with the angle. Figure 7 It can show the variation of one path of the PWM signal (i.e., the phase PWM) of the motor with the angle, such as the variation of one path of the PWM signal of the motor with angles r = 0 degree, r = 60 degrees, r = 120 degrees, r = 180 degrees, r = 240 degrees, and r = 300 degrees. In the solution of the present invention, the number of PWMs generating the phase current pulses is adjustable. For example, the number of PWMs N can be adjusted to 2 to adapt to different inductance motors.

[0101] Figure 8 It is a schematic diagram of the duty cycle of the PWM signal within one period T. Figure 8 It can show the duty cycle duty of the PWM signal within one period T.

[0102] Step 2: After sending out six paths of PWM signals (such as signal Up, signal Un, signal Vp, signal Vn, signal Wp, and signal Wn) to control the IPM power tubes to turn on and off, the phase current has become large enough to be detected. The control chip detects the three-phase current of the motor during this process and stores the stored current as shown in Table 1.

[0103] Step 3: After the detection is completed, close the PWM output duration Δt. When the motor winding current drops to 0, then send the PWM of the next angle to control the IPM to turn on and off.

[0104] Step 4: When the control chip completes the sending of all angle PWMs according to Table 1 and stores the detected motor phase current.

[0105] In the solution of the present invention, by injecting pulsed current into the three-phase windings of the motor, the rotor can be rotated with a small current and the maximum torque at the start of the motor, solving the problem that the rotor position cannot be recognized in the static state of the motor.

[0106] In some embodiments, among the first group of PWM signals to the Mth group of PWM signals, each group of PWM signals includes six PWM signals with a duration of N, where N is a positive integer.

[0107] The obtaining unit 102 obtains a set of three-phase currents of the motor within a set detection period, including: the obtaining unit 102 is specifically further configured to, at the next stator current magnetic field direction angle within the stator current magnetic field direction angle range and according to the set vector voltage, send any one group of PWM signals among the first group of PWM signals to the Mth group of PWM signals to control the IPM (specifically, control the turning on and off of the power transistors in the IPM), so as to realize injecting a set pulse current into the three-phase windings of the motor again. After N PWM signals in any one group of PWM signals are all sent, the three-phase currents of the motor are obtained; thus, within the set detection period, the first obtained three-phase currents of the motor to the Mth obtained three-phase currents of the motor are used as a set of three-phase currents of the motor.

[0108] In the solution of the present invention, in combination with Figure 5 the example shown, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor further includes: In step 1, within a current detection period (stator current magnetic field direction angle 0° to 360°), the duration number N of the PMW output is constant and cannot be changed. After the IPM is turned on, the magnitude of the motor phase current increases rapidly; after the IPM is turned off, the phase current gradually decreases.

[0109] In step 2, within several consecutive PWMs (such as N PWMs), the phase current has become large enough to be detected, and the control chip detects the three-phase currents of the motor during this process and stores the stored currents as shown in Table 1.

[0110] The solution of the present invention injects pulse currents into the three-phase windings of the motor to accurately identify the magnetic field direction position of the rotor.

[0111] In some embodiments, the number of PWM signals in each group of PWM signals (i.e., the value of N in each group of PWM signals), the magnitude of the set vector voltage, and the magnitude of the set time interval are all determined by the control unit 104 according to the period of the PWM signals in each group of PWM signals and the inductance of the three-phase windings of the motor; that is, the value of N, the magnitude of the set vector voltage, and the magnitude of the set time interval are all matched with the period of the PWM signals and the inductance of the three-phase windings of the motor.

[0112] Referring to the above steps 1 to 4, where the duration number N of the PMW output (such as Figure 7As shown in the figure, the magnitude of the vector voltage Vs(x) and the turn-off PWM duration Δt can both be adjusted according to the period T of the PWM and the inductance of the motor, so that the magnitude of the motor phase current can be detected by the control chip without overcurrent occurring. In the solution of the present invention, the pulse interval time is adjustable to optimize the motor startup noise.

[0113] In some embodiments, within the range of the stator current magnetic field direction angles during the set detection period, the number of the stator current magnetic field direction angles is M, and they are arranged in ascending order, where M is a positive integer.

[0114] The control unit 104 determines the magnetic field direction angle of the rotor based on the three-phase currents of a set of the motors, including: The control unit 104 is specifically further configured to determine the maximum current in a set of the three-phase currents of the motors, denoted as the maximum current of the motors. For the specific functions and processing of this control unit 104, refer to step S310.

[0115] The control unit 104 is specifically further configured to determine, within the range of the stator current magnetic field direction angles, one stator current magnetic field direction angle corresponding to the maximum current of the motors, denoted as the actual stator current magnetic field direction angle. For the specific functions and processing of this control unit 104, refer to step S320.

[0116] The control unit 104 is specifically further configured to determine the angle within the set error range of the actual stator current magnetic field direction angle as the magnetic field direction angle of the rotor. For the specific functions and processing of this control unit 104, refer to step S330.

[0117] In the solution of the present invention, in combination with Figure 5 the example shown, a method for identifying the magnetic field direction of the rotor position of a permanent magnet motor further includes: In step 4, when the control chip completes the sending of all angle PWMs according to Table 1 and stores the detected motor phase currents. By comparing the current magnitudes at different angles, it is possible to identify at which angle the motor rotor is located, that is, to identify the magnetic field direction position of the rotor.

[0118] Figure 9Table 1 for presetting the angle of the stator current magnetic field direction. As shown in Table 1, in the data table for presetting the angle of the stator current magnetic field direction, the corresponding relationships between the angle (such as angle r), the vector voltage, and the stored current are stored. For example: when the angle = 0°, the vector voltage is Vs(x), and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x), and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x), and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x), and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x), and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x), and the stored current is Is_300.

[0119] For example: the control chip outputs 6 sets of a set number of, such as 3, PWM waves at an angle of 0° according to a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM to turn on and off. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration △t is turned off. Then the control chip outputs 6 sets of a set number of, such as 3, PWM waves at an angle of 60° according to a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM to turn on and off. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration △t is turned off. Then, at an angle of 120°, 6 sets of a set number of, such as 3, PWM waves are output according to a set coefficient multiple of the rated vector voltage, such as 0.1 times, to control the IPM switch. During the process, the current values of each phase of the motor are detected and stored, and then the PWM duration △t is turned off. Similarly, the PWM output and turn-off at angles such as 180°, 240°, and 300° of the motor are completed in the above manner, and the detected current is stored.

[0120] When Figure 9 After all the angles in the shown Table 1 are output, the control chip compares the magnitudes of the stored currents Is_0, Is_60, Is_120, Is_180, Is_240, and Is_300. Whichever angle corresponds to the largest current, the rotor magnetic field is within that angle ± a set angle, such as ±30°. For example, if the current Is at 60° is the largest, then the magnetic field direction of the rotor is within the angle range of 60° ± 30°.

[0121] The solution of the present invention realizes the ability to identify the specific position of the rotor before the motor starts, so that the angle between the magnetic field generated by the stator and the rotor magnetic field is optimal, achieving the rotation of the rotor with a smaller current and the maximum torque, thereby realizing a fast starting speed and a high starting success rate of the motor, and thus solving the problems of high starting failure rate, large starting current, large vibration, and long starting time in the related solutions.

[0122] In the solution of the present invention, before the motor starts, pulse current is injected into the three-phase windings of the motor to decouple the specific position of the rotor, and then the stator starts to drive the rotor at the optimal rotation angle, achieving a large driving torque, thus accelerating the rotation speed of the rotor and solving the problem of too long motor startup time. The solution of the present invention realizes a large starting torque of the motor by precisely controlling the motor startup, reduces unnecessary energy loss, and improves the overall efficiency of the motor and the drive system.

[0123] Figure 10 Table 2 for presetting the angle of the stator current magnetic field direction. As shown in Table 2, in the data table of the preset angle of the stator current magnetic field direction, there is a corresponding relationship between the angle (such as angle r), the vector voltage, and the stored current. As Figure 10 shown in Table 2, the current magnetic field angle can cycle in multiple periods or be subdivided for the angle. For example: in one period, when the angle = 0°, the vector voltage is Vs(x), and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x), and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x), and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x), and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x), and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x), and the stored current is Is_300. In the next period, when the angle = 0°, the vector voltage is Vs(x), and the stored current is Is_0; when the angle = 60°, the vector voltage is Vs(x), and the stored current is Is_60; when the angle = 120°, the vector voltage is Vs(x), and the stored current is Is_120; when the angle = 180°, the vector voltage is Vs(x), and the stored current is Is_180; when the angle = 240°, the vector voltage is Vs(x), and the stored current is Is_240; when the angle = 300°, the vector voltage is Vs(x), and the stored current is Is_300.

[0124] In the solution of the present invention, there is no need to use a Hall effect sensor or an encoder to detect the position information of the rotor. An algorithm is adopted to realize the identification of the rotor position in the motor stationary state, accurately identify the initial position information of the rotor, and further accurately identify the position of the rotor magnetic field direction, realizing a faster and smoother startup of the motor.

[0125] Since the processing and functions implemented by the device in this embodiment are basically corresponding to the embodiments, principles, and examples of the foregoing method, for the details not described in the description of this embodiment, reference can be made to the relevant descriptions in the foregoing embodiments, and no further elaboration will be made here.

[0126] According to an embodiment of the present invention, there is also provided a motor corresponding to the control device of the motor. The motor may include: the control device of the motor described above.

[0127] Since the processing and functions implemented by the motor in this embodiment are basically corresponding to the embodiments, principles, and examples of the foregoing device, for the details not described in the description of this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments, and no further elaboration will be provided here.

[0128] According to an embodiment of the present invention, there is also provided a computer program product corresponding to the control method of the motor, including a computer program, and when the computer program is executed by a processor, the steps of the control method of the motor described above are implemented.

[0129] Since the processing and functions implemented by the product in this embodiment are basically corresponding to the embodiments, principles, and examples of the foregoing method, for the details not described in the description of this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments, and no further elaboration will be provided here.

[0130] According to an embodiment of the present invention, there is also provided a storage medium corresponding to the control method of the motor, and the storage medium includes a stored program, wherein when the program runs, the device where the storage medium is located is controlled to execute the steps of the control method of the motor described above.

[0131] Since the processing and functions implemented by the storage medium in this embodiment are basically corresponding to the embodiments, principles, and examples of the foregoing method, for the details not described in the description of this embodiment, reference may be made to the relevant descriptions in the foregoing embodiments, and no further elaboration will be provided here.

[0132] In summary, it is easy for those skilled in the art to understand that, on the premise of no conflict, the above-mentioned advantageous ways can be freely combined and superimposed.

[0133] The above description is only for the embodiments of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A control method for an electric motor, characterized in that, The motor has a stator and a rotor, and the stator has a three-phase winding; the control method of the motor includes: When a start instruction of the motor is received, injecting a set pulse current into the three-phase winding of the motor; When a set pulse current has been injected into the three-phase winding of the motor, acquiring the three-phase current of the motor; Determining the magnetic field direction angle of the rotor according to the three-phase current of the motor; Controlling the rotation of the rotor according to the magnetic field direction angle of the rotor so as to start the motor.

2. The control method of the motor according to claim 1, characterized in that, Wherein, Injecting a set pulse current into the three-phase winding of the motor includes: Injecting a set pulse current into the three-phase winding of the motor at set time intervals within a set detection period; Correspondingly, Acquiring the three-phase current of the motor includes: Acquiring a set of the three-phase current of the motor within a set detection period; Determining the magnetic field direction angle of the rotor according to the three-phase current of the motor includes: Determining the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor.

3. The control method of the motor according to claim 2, characterized in that, The drive system of the motor has an IPM; within the set detection period, in the range of the current magnetic field direction angles of the stator, the number of the current magnetic field direction angles of the stator is M and they are arranged in ascending order, and M is a positive integer; Injecting a set pulse current into the three-phase winding of the motor at set time intervals within a set detection period includes: Within the set detection period, according to the first current magnetic field direction angle of the stator in the range of the current magnetic field direction angles of the stator and according to a set vector voltage, sending a first set of PWM signals to control the IPM to realize injecting a set pulse current into the three-phase winding of the motor; when the three-phase current of the motor is acquired for the first time, closing the output of the first set of PWM signals; After the set time interval, according to the next current magnetic field direction angle of the stator in the range of the current magnetic field direction angles of the stator and according to a set vector voltage, sending a second set of PWM signals to control the IPM to realize injecting a set pulse current into the three-phase winding of the motor again; when the three-phase current of the motor is acquired for the second time, closing the output of the second set of PWM signals; Looping in sequence until the three-phase current of the motor is acquired for the Mth time, after obtaining the three-phase current of the motor acquired for the Mth time, closing the output of the Mth set of PWM signals.

4. The control method of the motor according to claim 3, characterized in that, Among the first set of PWM signals to the Mth set of PWM signals, each set of PWM signals includes: six-way PWM signals with a continuous number of N, and N is a positive integer; Acquiring a set of the three-phase current of the motor within a set detection period includes: When sending any one of the first group of PWM signals to the Mth group of PWM signals to control the IPM according to the next stator current magnetic field direction angle within the stator current magnetic field direction angle range and a set vector voltage, so as to realize injecting a set pulse current into the three-phase windings of the motor again, after N PWM signals in any one of the groups of PWM signals are all sent, obtain the three-phase current of the motor; thus, within a set detection period, use the three-phase current of the motor obtained for the first time to the three-phase current of the motor obtained for the Mth time as a set of the three-phase current of the motor.

5. The control method of the motor according to claim 3, wherein, Wherein, The number of PWM signals in each group of PWM signals, the magnitude of the set vector voltage, and the magnitude of the set time interval are all determined according to the period of the PWM signals in each group of PWM signals and the inductance magnitude of the three-phase windings of the motor.

6. The control method of the motor according to any one of claims 2 to 5, characterized in that Within the set detection period, in the stator current magnetic field direction angle range, the number of stator current magnetic field direction angles is M, and they are arranged in ascending order, where M is a positive integer; Determining the magnetic field direction angle of the rotor according to a set of the three-phase current of the motor includes: Determine the maximum current in a set of the three-phase current of the motor, and denote it as the maximum current of the motor; Within the stator current magnetic field direction angle range, determine a stator current magnetic field direction angle corresponding to the maximum current of the motor, and denote it as the actual stator current magnetic field direction angle; Determine the angle within the set error range of the actual stator current magnetic field direction angle as the magnetic field direction angle of the rotor.

7. A control device for an electric machine, characterized in that, The motor has a stator and a rotor, and the stator has three-phase windings; the control device of the motor includes: A control unit configured to inject a set pulse current into the three-phase windings of the motor when receiving a start instruction of the motor; An acquisition unit configured to obtain the three-phase current of the motor when a set pulse current has been injected into the three-phase windings of the motor; The control unit is further configured to determine the magnetic field direction angle of the rotor according to the three-phase current of the motor; The control unit is further configured to control the rotation of the rotor according to the magnetic field direction angle of the rotor so as to start the motor.

8. A motor, characterized in that, Including: The control device of the motor according to claim 7.

9. A storage medium, characterized in that, The storage medium includes a stored program, wherein when the program runs, it controls the device where the storage medium is located to execute the control method of the motor according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it realizes the steps of the control method of the motor according to any one of claims 1 to 6.

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