Initial State Detection Method for Synchronous Motor and Readable Storage Medium

Abstract

The present invention discloses a method for detecting the initial state of a synchronous motor and a readable storage medium. The initial state detection method includes: dividing a unit cycle of each phase current of the synchronous motor into multiple sub-cycles; constructing a preset rule table, the preset rule table storing the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor; obtaining the initial three-phase current data when the synchronous motor is started; and determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table, the initial state including the rotor angle and rotor direction of the synchronous motor. After obtaining the initial current data, the present application can quickly detect the rotor angle and rotor direction based on the preset correlation between the current data of the three-phase current and the rotor state of the synchronous motor. The initial state detection time is short, and there is no need to specifically find the zero-crossing point of a certain phase current, so the motor state can be quickly identified.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor state detection, and in particular relates to an initial state detection method of a synchronous motor and a readable storage medium. Background Art

[0002] With the development of motor technology, permanent magnet synchronous motors (PMSMs) are increasingly being used. Due to their advantages such as low noise levels, low power consumption, and high efficiency, they are gradually replacing induction motors. They are often used in applications with high noise requirements, such as refrigerator and air conditioner compressors, and electric vehicles.

[0003] When a permanent magnet synchronous motor is running, the precise rotor angle needs to be obtained in advance. Therefore, before the motor starts, the initial state of the motor needs to be detected, and its speed information and rotor position information need to be detected to avoid a series of problems such as current shock and motor vibration after the motor starts.

[0004] The PMSM initial state detection currently used is divided into two types: inductive and non-inductive:

[0005] 1. Inductive type: The current rotor position and speed information is obtained by the sensor, but the cost is high and the reliability is lower than that of the non-inductive type.

[0006] 2. Non-sensitivity: This means that the speed and rotor position information are identified by software algorithms. There are many existing non-sensitivity PMSM initial state detection schemes, such as sampling any phase of the three-phase current to determine whether the current has crossed zero. The disadvantage of this method is that it takes a long time to determine and needs to find the zero crossing point of the current. For another example, six pulses are injected into the three-phase PMSM motor to identify the rotor position. The disadvantage of this method is that it can only identify the rotor position angle when stationary. For another example, the high-frequency injection method is used to identify the rotor speed and angle. It has a wide range of applications and many related patent papers. However, the disadvantage of this method is that it is noisy and the sound quality is not friendly to the PMSM motor in the range hood. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects in the prior art and provide a method for detecting the initial state of a synchronous motor and a readable storage medium.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A method for detecting an initial state of a synchronous motor, the method comprising:

[0010] Dividing a unit cycle of each phase current of the synchronous motor into a plurality of sub-cycles;

[0011] Constructing a preset rule table, wherein the preset rule table stores an association relationship between current data of three-phase currents in each sub-cycle and a rotor state of the synchronous motor;

[0012] Obtain the initial three-phase current data when the synchronous motor starts;

[0013] An initial state of the synchronous motor is determined based on the initial three-phase current data and the preset rule table, where the initial state includes a rotor angle and a rotor direction of the synchronous motor.

[0014] Preferably, before the step of dividing the unit cycle of each phase current of the synchronous motor into a plurality of sub-cycles, the initial state detection method further comprises:

[0015] Obtain the current inflection point of each phase current and the phase difference between the three-phase currents;

[0016] The number of the sub-periods is calculated according to the current inflection point and the phase difference.

[0017] Preferably, the phase current of the synchronous motor is a sinusoidal current, and the step of dividing a single cycle of each phase current of the synchronous motor into a plurality of sub-cycles specifically includes:

[0018] The unit cycle of each phase current of the synchronous motor is divided into four large cycles, and each large cycle is divided into multiple small cycles;

[0019] The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table specifically includes:

[0020] Obtaining the single-phase current magnitude and single-phase current acceleration of each phase according to the initial three-phase current data;

[0021] Determine the major cycle of the synchronous motor's rotor in each phase according to the single-phase current magnitude and the single-phase current addition speed;

[0022] The initial state is determined based on the large cycle, the initial three-phase current data and the preset rule table.

[0023] Preferably, the three-phase current includes A-phase current, B-phase current and C-phase current, and the association relationship includes:

[0024] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0025] If the large cycle to which the AB current belongs is the same as the large cycle to which the B phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the C phase current belongs, then the rotor rotates counterclockwise;

[0026] If the large cycle to which the AB current belongs is the same as the large cycle to which the C phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the B phase current belongs, then the rotor rotates clockwise;

[0027] The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table obtains the rotor rotation direction through the following steps, specifically including:

[0028] The first current and the second current are obtained by lagging any phase current of the synchronous motor by 120° and 240°;

[0029] Based on the association relationship, the first current and the second current are respectively compared with the other two-phase currents of the three-phase current, and the rotor rotation direction is determined according to the comparison results.

[0030] Preferably, the three-phase current includes A-phase current, B-phase current and C-phase current, and the association relationship includes:

[0031] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0032] Traverse i, if A is satisfied bf =A aelay_120 &&A cf =A delay_240 or A bf =A delay240 &&A cf =A delay120 , then A′ af =(A af -1)*3+i+1;

[0033] in,

[0034]

[0035]

[0036]

[0037]

[0038] Among them, A delay_120 is the maximum cycle number of AB current, A aelay_240 is the maximum cycle number of AC current, A1 and A2 are intermediate variables, A af is the maximum cycle number of phase A current, A bf is the maximum cycle number of phase B current, A cfis the number of the large cycle to which the C phase current belongs, i is the large cycle number, the range of i is 0 to m-1, m is the number of small cycles in the large cycle, A′ af is the number of small cycles of phase A current, The range is 1 to 4 meters;

[0039] The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table obtains the rotor angle through the following steps, specifically including:

[0040] Traversing i to determine the target small cycle to which each phase current of the synchronous motor belongs;

[0041] The rotor angle is determined according to the target small period.

[0042] Preferably, the step of obtaining initial three-phase current data when the synchronous motor is started specifically includes:

[0043] Sampling the three-phase current when starting the synchronous motor;

[0044] The sampled three-phase current is filtered based on a first-order low-pass filtering algorithm to obtain the initial three-phase current data.

[0045] Preferably, the initial state monitoring method further includes:

[0046] Get the amplitude of three-phase current;

[0047] The current rotation speed of the synchronous motor is obtained based on the amplitudes of the three-phase currents.

[0048] Preferably, the initial state monitoring method further includes:

[0049] Obtaining the back electromotive force coefficient of the synchronous motor;

[0050] The step of obtaining the current speed of the synchronous motor based on the amplitude of the three-phase current specifically includes:

[0051] The current rotation speed is calculated based on the back electromotive force coefficient and the amplitude.

[0052] Preferably, the current speed is obtained by solving the following formula in the initial state detection method, specifically including:

[0053] K phase_elec *n elec =R*Amplitude

[0054]

[0055]

[0056] I three_phase_max =max(|I af |+|I bf |+|I cf |)

[0057] Among them, K phase_elec is the back electromotive force coefficient, E line_amplitude is the line voltage amplitude, f elec is the electrical frequency, R is the phase resistance, Amplitude is the amplitude of the three-phase current, I af is the A phase current in the three-phase current, I bf is the B-phase current in the three-phase current, I cf is the C phase current in the three-phase current, n elec is the current speed of the synchronous motor.

[0058] A synchronous motor initial state detection system, the initial state detection system comprising:

[0059] A cycle division module, used for dividing a unit cycle of each phase current of the synchronous motor into a plurality of sub-cycles;

[0060] A rule table construction module is used to construct a preset rule table, wherein the preset rule table stores the association relationship between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor;

[0061] The motor current acquisition module is used to obtain the initial three-phase current data of the synchronous motor when it starts;

[0062] An initial state determination module determines an initial state of the synchronous motor based on the initial three-phase current data and the preset rule table, wherein the initial state includes a rotor angle and a rotor direction of the synchronous motor.

[0063] Preferably, the initial state detection system further includes:

[0064] The cycle number determination module is used to obtain the current inflection point of each phase current and the phase difference between the three-phase currents, and calculate the number of the sub-cycles according to the current inflection point and the phase difference.

[0065] Preferably, the phase current of the synchronous motor is a sinusoidal current;

[0066] The cycle division module is used to divide the unit cycle of each phase current of the synchronous motor into four large cycles, and divide each large cycle into multiple small cycles;

[0067] The initial state determination module is specifically used for:

[0068] Obtaining the single-phase current magnitude and single-phase current acceleration of each phase according to the initial three-phase current data;

[0069] Determine the major cycle of the synchronous motor's rotor in each phase according to the single-phase current magnitude and the single-phase current addition speed;

[0070] The initial state is determined based on the large cycle, the initial three-phase current data and the preset rule table.

[0071] Preferably, the three-phase current includes A-phase current, B-phase current and C-phase current, and the association relationship includes:

[0072] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0073] If the large cycle to which the AB current belongs is the same as the large cycle to which the B phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the C phase current belongs, then the rotor rotates counterclockwise;

[0074] If the large cycle to which the AB current belongs is the same as the large cycle to which the C phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the B phase current belongs, then the rotor rotates clockwise;

[0075] The initial state determination module is specifically used for:

[0076] The first current and the second current are obtained by lagging any phase current of the synchronous motor by 120° and 240°;

[0077] Based on the association relationship, the first current and the second current are respectively compared with the other two-phase currents of the three-phase current, and the rotor rotation direction is determined according to the comparison results.

[0078] Preferably, the three-phase current includes A-phase current, B-phase current and C-phase current, and the association relationship includes:

[0079] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0080] Traverse i, if A is satisfied bf =A aelay_120 &&A cf =A delay_240 or A bf =A delay240 &&A cf =A delay120 , then A′ af =(A af -1)*3+i+1;

[0081] in,

[0082]

[0083]

[0084]

[0085]

[0086] Among them, A delay_120 is the maximum cycle number of AB current, A aelay_240 is the maximum cycle number of AC current, A1 and A2 are intermediate variables, A af is the maximum cycle number of phase A current, A bf is the maximum cycle number of phase B current, A cf is the number of the large cycle to which the C phase current belongs, i is the large cycle number, the range of i is 0 to m-1, m is the number of small cycles in the large cycle, A′ af is the number of small cycles of phase A current, The range is 1 to 4 meters;

[0087] The initial state determination module is specifically configured to: traverse i to determine a target small cycle to which each phase current of the synchronous motor belongs;

[0088] The rotor angle is determined according to the target small period.

[0089] Preferably, the motor current acquisition module is used to sample the three-phase current when starting the synchronous motor, and filter the sampled three-phase current based on a first-order low-pass filtering algorithm to obtain the initial three-phase current data.

[0090] Preferably, the initial state monitoring system further includes:

[0091] A current amplitude acquisition module is used to obtain the amplitude of the three-phase current;

[0092] The motor speed determination module is configured to obtain the current speed of the synchronous motor based on the amplitude of the three-phase current.

[0093] Preferably, the initial state monitoring system further includes:

[0094] A back electromotive force coefficient acquisition module, used to obtain the back electromotive force coefficient of the synchronous motor;

[0095] The motor speed determination module is used to calculate the current speed based on the back electromotive force coefficient and the amplitude.

[0096] Preferably, the current speed is obtained by solving the following formula in the initial state detection system, specifically including:

[0097] K phase_elec *n elec =R*Amplitude

[0098]

[0099]

[0100] I three_phase_max =max(|I af |+|I bf |+|I cf |)

[0101] Among them, K phase_elec is the back electromotive force coefficient, E line_amplitude is the line voltage amplitude, f elec is the electrical frequency, R is the phase resistance, Amplitude is the amplitude of the three-phase current, I af is the A phase current in the three-phase current, I bf is the B-phase current in the three-phase current, I cf is the C phase current in the three-phase current, n elec is the current speed of the synchronous motor.

[0102] A computer-readable storage medium stores a computer program, which implements the above-mentioned method for detecting the initial state of a synchronous motor when the program is executed by a processor.

[0103] The positive and progressive effect of the present invention is that: according to the pre-set rule table, that is, the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor, after obtaining the initial current data, the rotor angle and rotor direction can be quickly detected, the initial state detection time is short, there is no need to specifically find the zero crossing point of a certain phase current, the motor state can be quickly identified, and the detection method procedure is simple and does not require complex IGBT control. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 This is a flow chart of a method for detecting an initial state of a synchronous motor according to embodiment 1 of the present invention.

[0105] Figure 2 This is a flowchart of step 13 in the method for detecting the initial state of a synchronous motor according to embodiment 1 of the present invention.

[0106] Figure 3 This is a waveform diagram of a phase current value before and after filtering when the filter coefficient K=0.1 in the initial state detection method of the synchronous motor according to Example 1 of the present invention.

[0107] Figure 4 This is a flow chart of a method for detecting an initial state of a synchronous motor according to embodiment 2 of the present invention.

[0108] Figure 5 Schematic diagram of large cycle division in the method for detecting the initial state of a synchronous motor according to embodiment 2 of the present invention.

[0109] Figure 6 Schematic diagram of the arrangement of the three-phase rotor of a three-phase motor in the initial state detection method of a synchronous motor according to embodiment 2 of the present invention.

[0110] Figure 7 Schematic diagram of the three-phase current phases when the rotor rotates counterclockwise in the initial state detection method of the synchronous motor according to embodiment 2 of the present invention.

[0111] Figure 8 This is a schematic diagram of the three-phase current phases when the rotor rotates clockwise in the initial state detection method of the synchronous motor according to embodiment 2 of the present invention.

[0112] Figure 9 Schematic diagram of small cycle division in the method for detecting the initial state of a synchronous motor according to embodiment 2 of the present invention.

[0113] Figure 10 This is a flow chart of a method for detecting an initial state of a synchronous motor according to embodiment 3 of the present invention.

[0114] Figure 11 Schematic diagram of the waveform of the absolute value addition of three-phase sine waves in the initial state detection method of the synchronous motor according to embodiment 3 of the present invention.

[0115] Figure 12 Schematic diagram of a module of a synchronous motor initial state detection system according to embodiment 4 of the present invention. DETAILED DESCRIPTION

[0116] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0117] Example 1

[0118] A method for detecting the initial state of a synchronous motor, such as Figure 1 As shown, the initial state detection method includes:

[0119] Step 11: Divide the unit cycle of each phase current of the synchronous motor into multiple sub-cycles;

[0120] Step 12: Construct a preset rule table; the preset rule table stores the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor;

[0121] Step 13: Acquire initial three-phase current data when the synchronous motor is started;

[0122] Step 14: Determine the initial state of the synchronous motor based on the initial three-phase current data and a preset rule table; the initial state includes the rotor angle and rotor direction of the synchronous motor.

[0123] In this embodiment, see Figure 1 Before step 11, the initial state detection method further includes:

[0124] Step 101: Obtain the current inflection point of each phase current and the phase difference between the three-phase currents;

[0125] Step 102: Calculate the number of sub-cycles according to the current inflection point and the phase difference.

[0126] Among them, taking the PMSM motor as an example, according to the PMSM three-phase motor principle, in the generator mode, the three-phase voltage is sinusoidal and the phase difference is 120°, that is, the B-phase current and the C-phase current lag the A-phase current by 120° and 240° respectively. In addition, the inflection points of the three-phase current are obtained (the 0-crossing point and the amplitude point), and the following key points are obtained, including 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330° and 360°, and then divided into periods of 30°.

[0127] In this embodiment, Figure 2 As shown, step 13 specifically includes:

[0128] Step 131: sampling the three-phase current when starting the synchronous motor;

[0129] Step 132: Filter the sampled three-phase current based on a first-order low-pass filtering algorithm to obtain initial three-phase current data.

[0130] Among them, before the PMSM motor starts, the PWM of the IGBT (insulated gate bipolar transistor) is turned on (the upper and lower bridge arms of the PWM are complementary, and the duty cycle is appropriately large, so that the lower bridge is turned on for a short time). The two phases of the PMSM motor (the third phase is calculated by formula I a +I b +I c =0 to obtain) / three-phase current is sampled, and then the A, B, and C three-phase currents are filtered using a software first-order low-pass filter to obtain I af , I bf , I cf (The filter coefficient can be selected to be appropriately larger to avoid excessive phase lag). Figure 3 , shows the waveform of a phase current value before and after filtering when the filtering coefficient K=0.1.

[0131] In this embodiment, according to a pre-set rule table, that is, the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor, after obtaining the initial current data, the rotor angle and rotor direction can be quickly detected. The initial state detection time is short, and there is no need to specifically find the zero-crossing point of a certain phase current. The motor state can be quickly identified, and the detection method procedure is simple and does not require complex IGBT control.

[0132] Example 2

[0133] The initial state detection method of the synchronous motor of this embodiment is further improved on the basis of embodiment 1. Taking the PMSM motor as an example, the driving principle of the PMSM motor is to modulate the DC voltage to obtain a three-phase sine wave (with a phase difference of 120°), obtain a voltage vector rotating in space, and form a rotating magnetic field, thereby driving the rotor (permanent magnet) to rotate. That is, the phase current of the synchronous motor is a sine wave current, such as Figure 4 As shown, step 11 specifically includes:

[0134] Step 111: Divide a unit cycle of each phase current of the synchronous motor into four large cycles, and divide each large cycle into multiple small cycles;

[0135] For further information, see Figure 4 , step 14 specifically includes:

[0136] Step 141: Obtain the single-phase current magnitude and single-phase current acceleration of each phase according to the initial three-phase current data;

[0137] Step 142: Determine the large cycle of each phase of the synchronous motor rotor according to the single-phase current magnitude and the single-phase current addition speed;

[0138] For details, see Figure 5 , the sine function is divided into 4 large periods (1 to 4, Area, referred to as A), each area is 90 degrees. When A = 1, the current I> 0, Δ I <0(Δ I =I n+1 -I n ); When A=2, current I<0, Δ I <0;When A=3,current I<0,Δ I >0; when A=4, current I>0, Δ I >0; that is, obtain the three-phase current I af , I bf , I cf After that, we can know the large cycle A of the three-phase current. af 、A bf 、A cf .

[0139] Step 143: Determine the initial state based on the corresponding large cycle, the initial three-phase current data, and the preset rule table.

[0140] In this embodiment, the three-phase current includes phase A current, phase B current, and phase C current, and the association relationship includes:

[0141] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0142] If the large cycle to which the AB current belongs is the same as the large cycle to which the B phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the C phase current belongs, then the rotor rotates counterclockwise;

[0143] If the large cycle to which the AB current belongs is the same as the large cycle to which the C phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the B phase current belongs, then the rotor rotates clockwise;

[0144] According to the principle of PMSM three-phase motor, in generator mode, the three-phase voltage is sinusoidal and the phase difference is 120 degrees. Assuming that the three-phase rotor of the three-phase motor is arranged in a counterclockwise direction, as shown in the following example: Figure 6 When the rotor rotates counterclockwise, according to Faraday's law of electromagnetic induction, the three-phase current phase diagram is shown in Figure 7 When the rotor rotates clockwise instantaneously, according to Faraday's law of electromagnetic induction, the three-phase current phase diagram can be seen as Figure 8 .

[0145] Furthermore, in step 143, the rotor rotation direction is obtained by the following steps, specifically including:

[0146] The first current and the second current are obtained by lagging any phase current of the synchronous motor by 120° and 240°;

[0147] Based on the association relationship, the first current and the second current are respectively compared with the other two-phase currents of the three-phase current, and the rotor rotation direction is determined according to the comparison results.

[0148] In this embodiment, the association relationship also includes:

[0149] Traverse i, if A is satisfied bf =A delay_120 &&A cf =A delay_240 or A bf =A delay240 &&A cf =A delay120 , then A′ af =(A af-1)*3+i+1;

[0150] in,

[0151]

[0152]

[0153]

[0154]

[0155] Among them, Ad elay_120 is the maximum cycle number of AB current, A delay_240 is the maximum cycle number of AC current, A1 and A2 are intermediate variables, A af is the maximum cycle number of phase A current, A bf is the maximum cycle number of phase B current, A cf is the number of the large cycle to which the C phase current belongs, i is the large cycle number, the range of i is 0 to m-1, m is the number of small cycles in the large cycle, A′ af is the number of small cycles of phase A current, The range is 1 to 4 meters;

[0156] Depend on Figure 7 and 8 It can be seen that the three-phase current phase is related to the rotor angle, and the current phase sequence is related to the rotor direction, such as Figure 9 As shown, the entire single-cycle sine function is divided into 12 small cycles (the number of small cycles is 1 to 12), each area is 30°. For the three-phase current, in one cycle, the corresponding relationship between the large cycles of the three phases A, B, and C is shown in Table 1.

[0157] Table 1 Corresponding relationship of the large cycle of phases A, B, and C in the same cycle

[0158]

[0159] Let’s take a specific example to further illustrate this solution:

[0160] Example 1: When A is in the range of 0 to 30°, the calculated A is based on the current amplitude and speed increase. af =1,A bf =3, A cf =2. Then according to the formula:

[0161] Traverse i, when i=0, A delay_120 =3%4=3,A delay_240 =2%4=2. At this time A delay_120 =A bf , Adelay_240 =A cf , then A′ af =(A af -1)*3+i+1=1, which is within the range of 0 to 30°, that is, the first small cycle.

[0162] Example 2: When A is in the range of 150-180°, the calculated A is based on the current amplitude and speed increase. af =2, A bf =1,A cf =4. Then according to the formula:

[0163]

[0164]

[0165] in i=0 / 1 / 2.

[0166] Traverse i, when i=0, A delay_120 =4, A delay_240 =2%4=2. delay_120 ≠A bf , A delay_240 ≠A cf , the prerequisite is not met, continue to judge.

[0167] When i=1, A delay_120 =5%4=1,A aelay_240 =3%4=3. delay_120 ≠A bf , A delay_240 ≠A cf , the prerequisite is not met, continue to judge.

[0168] When i=2, A delay_120 =5%4=1,A delay_240 =4. At this time A delay_120 =A bf , A delay_240 =A cf , then A′ af =(A af -1)*3+i+1=6, which is within the range of 150 to 180°, that is, the 6th small cycle.

[0169] Furthermore, in step 143, the rotor angle is obtained by the following steps, specifically including:

[0170] Traversing i to determine the target small cycle to which each phase current of the synchronous motor belongs;

[0171] The rotor angle is determined according to the target small period.

[0172] This embodiment takes the three-phase sine wave of the PMSM motor as an example and gives a specific example of how to construct a rule table. The construction of the preset rule table is realized through the correlation between the current data of the three-phase current and the rotor state of the synchronous motor, so that the initial state of the motor can be identified in a simpler and faster way during real-time initial state detection.

[0173] Example 3

[0174] The initial state detection method of the synchronous motor of this embodiment is further improved on the basis of embodiment 1. Before the PMSM starts, when there is speed, opening six PWM channels is equivalent to the generator mode. In this mode, the higher the PMSM speed, the greater the three-phase current amplitude. Then, the current speed can be roughly judged by the three-phase current amplitude. Figure 10 As shown, the initial state monitoring method further includes:

[0175] Step 15: Obtain the amplitude of the three-phase current;

[0176] Step 16: Obtain the back electromotive force coefficient of the synchronous motor;

[0177] Step 17: Calculate the current speed based on the back electromotive force coefficient and amplitude.

[0178] In this embodiment, the current speed is obtained by solving the following formula in the initial state detection method, specifically including:

[0179] K phase_elec *n elec =R*Amplitude

[0180]

[0181]

[0182] I three_phase_max =max(|I af |+|I bf |+|I cf |)

[0183] Among them, K phase_elec is the back electromotive force coefficient, E line_amplitude is the line voltage amplitude, f elec is the electrical frequency, R is the phase resistance, Amplitude is the amplitude of the three-phase current, I af is the A phase current in the three-phase current, I bf is the B-phase current in the three-phase current, I cf is the C phase current in the three-phase current, n elecis the current speed of the synchronous motor, where the current speed is part of the initial state of the synchronous motor.

[0184] In practical applications, clamp the oscilloscope voltage probe to any two phase terminals of the PMSM motor, rotate the motor at a constant speed to make it rotate, and then read the line voltage amplitude E line_amplitude and electrical frequency f elec The resistance R is provided by the manufacturer or can be tested by an LCR meter (a tester used to test inductance, capacitance, and resistance).

[0185] For three-phase sinusoidal waveforms, the phases differ by 120° and the amplitudes are the same;

[0186] I af =Amplitude*cos(wt)

[0187] I bf =Amplitude*cos(wt+120°)

[0188] I cf =Amplitude*cos(wt+240°)

[0189] Adding the absolute values of the three-phase currents yields:

[0190] I three_phase =|I af |+|I bf |+|I cf |

[0191] See also Figure 11 As shown in the waveform diagram, when I a When the angle wt is 0°, 60°, 120°, 180°, 240°, 300°,

[0192] I three_phase_max =2*Amplitude

[0193] That is, find I three_phase_max The amplitude of each phase current can be calculated;

[0194] After the current amplitude of each phase is calculated, it can be calculated according to the formula

[0195] K phase_elec *n elec =E phase_amplitude

[0196] E phase_amplitude =L(DI phase / Dt)+R*I phase

[0197] Since the phase current I phase =Amplitude, DIphase / Dt=0, then the formula can be changed to

[0198] K phase_elec *n elec =R*Amplitude

[0199] Then we can find n elec .

[0200] Example 4

[0201] An initial state detection system for a synchronous motor, such as Figure 12 As shown, the initial state detection system includes:

[0202] A cycle division module 1 is used to divide the unit cycle of each phase current of the synchronous motor into multiple sub-cycles;

[0203] A rule table construction module 2 is used to construct a preset rule table, wherein the preset rule table stores the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor;

[0204] The motor current acquisition module 3 is used to obtain the initial three-phase current data when the synchronous motor starts;

[0205] The initial state determination module 4 determines the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table, where the initial state includes the rotor angle and rotor direction of the synchronous motor.

[0206] In this embodiment, see Figure 12 , the initial state detection system further includes:

[0207] The cycle number determination module 5 is used to obtain the current inflection point of each phase current and the phase difference between the three-phase currents, and calculate the number of the sub-cycles according to the current inflection point and the phase difference.

[0208] Among them, taking the PMSM motor as an example, according to the PMSM three-phase motor principle, in the generator mode, the three-phase voltage is sinusoidal and the phase difference is 120°, that is, the B-phase current and the C-phase current lag the A-phase current by 120° and 240° respectively. In addition, the inflection points of the three-phase current are obtained (the 0-crossing point and the amplitude point), and the following key points are obtained, including 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330° and 360°, and then divided into periods of 30°.

[0209] Specifically, the motor current acquisition module 3 is used to sample the three-phase current when starting the synchronous motor, and filter the sampled three-phase current based on a first-order low-pass filtering algorithm to obtain the initial three-phase current data.

[0210] Among them, before the PMSM motor starts, the PWM of the IGBT (insulated gate bipolar transistor) is turned on (the upper and lower bridge arms of the PWM are complementary, and the duty cycle is appropriately large, so that the lower bridge is turned on for a short time). The two phases of the PMSM motor (the third phase is calculated by formula I a +I b +I c =0 to obtain) / three-phase current is sampled, and then the A, B, and C three-phase currents are filtered using a software first-order low-pass filter to obtain I af , I bf , I cf (Among them, the filter coefficient can be selected to be appropriately larger to avoid causing excessive phase lag).

[0211] In this embodiment, a PMSM motor is used as an example. The driving principle of the PMSM motor is to modulate the DC voltage to obtain a three-phase sine wave (with a phase difference of 120°), thereby obtaining a voltage vector that rotates in space, forming a rotating magnetic field, and thereby driving the rotor (permanent magnet) to rotate. That is, the phase current of the synchronous motor is a sinusoidal current.

[0212] The cycle division module 1 is used to divide the unit cycle of each phase current of the synchronous motor into four large cycles, and each large cycle into multiple small cycles;

[0213] The initial state determination module 4 is specifically used for:

[0214] Obtaining the single-phase current magnitude and single-phase current acceleration of each phase according to the initial three-phase current data;

[0215] Determine the major cycle of the synchronous motor's rotor in each phase according to the single-phase current magnitude and the single-phase current addition speed;

[0216] Specifically, the sine function is divided into 4 large periods (1 to 4, Area, referred to as A), each area is 90 degrees. When A = 1, the current I> 0, Δ I <0(Δ I =I n+1 -I n ); When A=2, current I<0, Δ I <0;When A=3,current I<0,Δ I >0; when A=4, current I>0, Δ I >0; that is, obtain the three-phase current I af , I bf , I cfAfter that, we can know the large cycle A of the three-phase current. af 、A bf 、A cf .

[0217] The initial state is determined based on the large cycle, the initial three-phase current data and the preset rule table.

[0218] In this embodiment, the three-phase current includes phase A current, phase B current, and phase C current, and the association relationship includes:

[0219] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0220] If the large cycle to which the AB current belongs is the same as the large cycle to which the B phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the C phase current belongs, then the rotor rotates counterclockwise;

[0221] If the large cycle to which the AB current belongs is the same as the large cycle to which the C phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the B phase current belongs, then the rotor rotates clockwise;

[0222] The initial state determination module 4 is specifically used for:

[0223] The first current and the second current are obtained by lagging any phase current of the synchronous motor by 120° and 240°;

[0224] Based on the association relationship, the first current and the second current are respectively compared with the other two-phase currents of the three-phase current, and the rotor rotation direction is determined according to the comparison results.

[0225] In this embodiment, the three-phase current includes phase A current, phase B current, and phase C current, and the association relationship includes:

[0226] If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively;

[0227] Traverse i, if A is satisfied bf =A delay_120 &&A cf =A delay_240 or A bf =A delay240 &&A cf =A delay120 , then A′ af =(A af -1)*3+i+1;

[0228] in,

[0229]

[0230]

[0231]

[0232]

[0233] Among them, A delay_120 is the maximum cycle number of AB current, A delay_240 is the maximum cycle number of AC current, A1 and A2 are intermediate variables, A af is the maximum cycle number of phase A current, A bf is the maximum cycle number of phase B current, A cf is the number of the large cycle to which the C phase current belongs, i is the large cycle number, the range of i is 0 to m-1, m is the number of small cycles in the large cycle, A′ af is the number of small cycles of phase A current, The range is 1 to 4 meters;

[0234] The initial state determination module 4 is specifically used for:

[0235] Traversing i to determine the target small cycle to which each phase current of the synchronous motor belongs;

[0236] The rotor angle is determined according to the target small period.

[0237] In this embodiment, before the PMSM is started, when there is speed, opening six PWM channels is equivalent to the generator mode. In this mode, the higher the PMSM speed, the greater the three-phase current amplitude, and the current speed can be roughly judged by the three-phase current amplitude.

[0238] See also Figure 12 , the initial state monitoring system further includes:

[0239] Current amplitude acquisition module 6, used to obtain the amplitude of the three-phase current;

[0240] The motor speed determination module 7 is configured to obtain the current speed of the synchronous motor based on the amplitude of the three-phase current.

[0241] In this embodiment, the initial state monitoring system further includes:

[0242] A back electromotive force coefficient acquisition module 8, used to obtain the back electromotive force coefficient of the synchronous motor;

[0243] The motor speed determination module 7 is configured to calculate the current speed based on the back electromotive force coefficient and the amplitude.

[0244] In this embodiment, the current speed is obtained by solving the following formula in the initial state detection system:

[0245] K phase_elec *n elec =R*Amplitude

[0246]

[0247]

[0248] I three_phase_max =max(|I a |+|I b |+|I c |)

[0249] Among them, K phase_elec is the back electromotive force coefficient, E line_amplitude is the line voltage amplitude, f elec is the electrical frequency, R is the phase resistance, Amplitude is the amplitude of the three-phase current, I a is the A phase current in the three-phase current, I b is the B-phase current in the three-phase current, I c is the C phase current in the three-phase current, n elec is the current speed of the synchronous motor, where the current speed is part of the initial state of the synchronous motor.

[0250] In practical applications, clamp the oscilloscope voltage probe to any two phase terminals of the PMSM motor, rotate the motor at a constant speed to make it rotate, and then read the line voltage amplitude E line_amplitude and electrical frequency f elec The resistance R is provided by the manufacturer or can be tested by an LCR meter (a tester used to test inductance, capacitance, and resistance).

[0251] For three-phase sinusoidal waveforms, the phases differ by 120° and the amplitudes are the same;

[0252] I af =Amplitude*cos(wt)

[0253] I bf =Amplitude*cos(wt+120°)

[0254] I cf =Amplitude*cos(wt+240°)

[0255] Adding the absolute values of the three-phase currents yields:

[0256] I three_phase =|Iaf |+|I bf |+|I cf |

[0257] See also Figure 11 As shown in the waveform diagram, when I a When the angle wt is 0°, 60°, 120°, 180°, 240°, 300°,

[0258] I three_phase_max =2*Amplitude

[0259] That is, find I three_phase_max The amplitude of each phase current can be calculated;

[0260] After the current amplitude of each phase is calculated, it can be calculated according to the formula

[0261] K phase_elec *n elec =E phase_amplitude

[0262] E phase_amplitude =L(DI phase / Dt)+R*I phase

[0263] Since the phase current I phase =Amplitude, DI phase / Dt=0, then the formula can be changed to

[0264] K phase_elec *n elec =R*Amplitude

[0265] Then we can find n elec .

[0266] In this embodiment, according to a pre-set rule table, that is, the correlation between the current data of the three-phase current in each sub-cycle and the rotor state of the synchronous motor, after obtaining the initial current data, the rotor angle and rotor direction can be quickly detected. The initial state detection time is short, and there is no need to specifically find the zero-crossing point of a certain phase current. The motor state can be quickly identified, and the detection method procedure is simple and does not require complex IGBT control.

[0267] Example 5

[0268] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the initial state detection method of a synchronous motor described in Examples 1-3.

[0269] The readable storage medium may include, but is not limited to, a portable disk, a hard disk, a random access memory, a read-only memory, an erasable programmable read-only memory, an optical storage device, a magnetic storage device, or any suitable combination thereof.

[0270] In a possible implementation, the present invention can also be implemented in the form of a program product, which includes a program code. When the program product is run on a terminal device, the program code is used to enable the terminal device to execute the initial state detection method of the synchronous motor described in Examples 1-3.

[0271] The program code for executing the present invention may be written in any combination of one or more programming languages, and may be executed entirely on the user device, partially on the user device, as an independent software package, partially on the user device and partially on a remote device, or entirely on the remote device.

[0272] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A method for detecting the initial state of a synchronous motor, characterized in that: The initial state detection method includes: Dividing a unit cycle of each phase current of the synchronous motor into a plurality of sub-cycles; Constructing a preset rule table, wherein the preset rule table stores an association relationship between current data of three-phase currents in each sub-cycle and a rotor state of the synchronous motor; Obtain the initial three-phase current data when the synchronous motor starts; determining an initial state of the synchronous motor based on the initial three-phase current data and the preset rule table, wherein the initial state includes a rotor angle and a rotor direction of the synchronous motor; The phase current of the synchronous motor is a sinusoidal current, and the step of dividing a single cycle of each phase current of the synchronous motor into a plurality of sub-cycles specifically includes: The unit cycle of each phase current of the synchronous motor is divided into four large cycles, and each large cycle is divided into multiple small cycles; The three-phase current includes phase A current, phase B current and phase C current, and the association relationship includes: If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively; Traversal , if satisfied or ,but ; in, in, is the maximum cycle number of AB current, is the maximum cycle number of the AC current, and is an intermediate variable, is the maximum cycle number of phase A current, is the maximum cycle number of phase B current, is the maximum cycle number of phase C current, For a large number of cycles, The range is 0~ , is the number of small cycles within a large cycle, is the number of small cycles of phase A current, The range is 1~ ; The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table obtains the rotor angle through the following steps, specifically including: Traversal , to determine the target small cycle to which each phase current of the synchronous motor belongs; The rotor angle is determined according to the target small period.

2. The method for detecting the initial state of a synchronous motor according to claim 1, wherein: Before the step of dividing the unit cycle of each phase current of the synchronous motor into a plurality of sub-cycles, the initial state detection method further includes: Obtain the current inflection point of each phase current and the phase difference between the three-phase currents; The number of the sub-periods is calculated according to the current inflection point and the phase difference.

3. The method for detecting the initial state of a synchronous motor according to claim 1, wherein: The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table specifically includes: Obtaining the single-phase current magnitude and single-phase current acceleration of each phase according to the initial three-phase current data; Determine the major cycle of the synchronous motor's rotor in each phase according to the single-phase current magnitude and the single-phase current addition speed; The initial state is determined based on the large cycle, the initial three-phase current data and the preset rule table.

4. The method for detecting the initial state of a synchronous motor according to claim 3, wherein: The three-phase current includes phase A current, phase B current and phase C current, and the association relationship includes: If any phase current is phase A current, AB current and AC current are obtained by lagging phase A current by 120° and 240° respectively; If the large cycle to which the AB current belongs is the same as the large cycle to which the B phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the C phase current belongs, then the rotor rotates counterclockwise; If the large cycle to which the AB current belongs is the same as the large cycle to which the C phase current belongs, and the large cycle to which the AC current belongs is the same as the large cycle to which the B phase current belongs, then the rotor rotates clockwise; The step of determining the initial state of the synchronous motor based on the initial three-phase current data and the preset rule table obtains the rotor rotation direction through the following steps, specifically including: Lagging any phase current of the synchronous motor by 120° and 240° to obtain a first current and a second current; Based on the association relationship, the first current and the second current are respectively compared with the other two-phase currents of the three-phase current, and the rotor rotation direction is determined according to the comparison results.

5. The method for detecting the initial state of a synchronous motor according to claim 1, wherein: The step of obtaining the initial three-phase current data when the synchronous motor is started specifically includes: Sampling the three-phase current when starting the synchronous motor; The sampled three-phase current is filtered based on a first-order low-pass filtering algorithm to obtain the initial three-phase current data.

6. The method for detecting the initial state of a synchronous motor according to claim 1, wherein: The initial state monitoring method further includes: Get the amplitude of three-phase current; The current rotation speed of the synchronous motor is obtained based on the amplitudes of the three-phase currents.

7. The method for detecting the initial state of a synchronous motor according to claim 6, wherein: The initial state monitoring method further includes: Obtaining the back electromotive force coefficient of the synchronous motor; The step of obtaining the current speed of the synchronous motor based on the amplitude of the three-phase current specifically includes: The current rotation speed is calculated based on the back electromotive force coefficient and the amplitude.

8. The method for detecting the initial state of a synchronous motor according to claim 7, wherein: The initial state detection method obtains the current speed by solving the following formula: in, is the back electromotive force coefficient, is the line voltage amplitude, is the electrical frequency, is the phase resistance, is the amplitude of the three-phase current, is the A-phase current in the three-phase current, is the B-phase current in the three-phase current, is the C phase current in the three-phase current, is the current speed of the synchronous motor.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method for detecting the initial state of a synchronous motor according to any one of claims 1 to 8 is implemented.

Images