Single-inverter drag-motor starting control method, system, device and medium

Abstract

This application relates to a starting control method, system, device, and medium for a single inverter supporting multiple motors. During the motor starting phase, a high-frequency square wave signal is injected into each motor connected to the single inverter to obtain the response signal of each motor. The response signals of each motor are then separated to obtain a high-frequency response signal for each motor. Phase-locked loop (PLL) per-unit processing is performed on the high-frequency response signals of each motor to obtain the initial rotor position of each motor. A target rotor position difference is determined based on the initial rotor positions of each motor. Based on the target rotor position difference, the rotor positions of each motor are adjusted according to a preset graded adjustment strategy to control the synchronous starting of each motor when their rotor positions are consistent. This solves the problem of low reliability of multi-motor synchronous starting caused by low rotor position identification accuracy and complex system structure in existing related technologies.

Description

Technical Field

[0001] This application relates to the field of motor drive control technology, and in particular to a starting control method, system, device and medium for a single inverter driving multiple motors. Background Technology

[0002] With the rapid development of motor drive technology, single-inverter multi-motor drive systems have become an important development direction for multi-motor drives due to their significant advantages in terms of structural simplification, cost control, and operational stability. However, in practical applications, multi-motor systems inevitably encounter problems such as load differences and motor parameter mismatches during startup and operation, posing challenges to the synchronous startup control of multiple motors. Summary of the Invention

[0003] In view of this, this application provides a control method, system and device for synchronous drive of dual permanent magnet synchronous motors to solve the problem of low reliability of multi-motor synchronous start-up caused by low rotor position identification accuracy and complex system structure in the prior art.

[0004] In a first aspect, embodiments of this application provide a starting control method for a single inverter supporting multiple motors, the starting control method comprising:

[0005] During the motor startup phase, high-frequency square wave signals are injected into each motor connected to the single inverter to obtain the response signals of each motor.

[0006] Signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor;

[0007] The initial rotor position of each motor is obtained by performing phase-locked loop per-unit processing based on the high-frequency response signal of each motor.

[0008] The target rotor position difference is determined based on the initial rotor position of each motor;

[0009] Based on the target rotor position difference, the rotor position of each motor is adjusted according to a preset graded adjustment strategy so as to control the synchronous start of each motor when the rotor positions of each motor are consistent.

[0010] Optionally, the response signal of the motor is a response current signal. The step of injecting high-frequency square wave signals into each motor connected to the single inverter during the motor startup phase to obtain the response signal of each motor includes:

[0011] Determine the rotational speed of each motor connected to the single inverter;

[0012] When the speed of each motor is lower than the preset speed, based on the fundamental frequency of the motor, the high-frequency square wave voltage signal is injected in a two-phase rotating coordinate system through a single inverter, wherein the frequency of the high-frequency square wave signal is greater than the fundamental frequency.

[0013] In a two-phase stationary coordinate system, the response current signal of each motor is extracted.

[0014] Optionally, signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor, including:

[0015] Determine the high-frequency response current characteristics corresponding to the high-frequency square wave signal;

[0016] Based on the high-frequency response current characteristics, the modulation response signal generated by the high-frequency square wave signal under the two-phase stationary coordinates of each motor is extracted from the response signal of each motor.

[0017] For each motor, the modulation response signal is determined as the high-frequency response signal.

[0018] Optionally, the step of performing phase-locked loop per-unit processing based on the high-frequency response signals of each motor to obtain the initial rotor position of each motor includes:

[0019] The high-frequency response signal is input into the rotor position observer;

[0020] The rotor position error information is obtained by calculating the high-frequency response signal using the rotor position observer.

[0021] The rotor position error information is normalized to obtain the initial rotor position of each motor.

[0022] Optionally, the target rotor position difference is determined based on the initial rotor position of each motor, including:

[0023] Determine the number of motors;

[0024] When the number of motors is greater than a preset threshold for the number of motors, the standard deviation of the initial rotor position is determined based on the initial rotor position of each motor.

[0025] The target rotor position difference is determined using the standard deviation of the rotor's initial position.

[0026] Optionally, the target rotor position difference is determined based on the initial rotor position of each motor, including:

[0027] Determine the number of motors;

[0028] When the number of motors is less than the preset motor number threshold, the average value of the initial rotor position of each motor connected to the single inverter is calculated to obtain the average value of the initial rotor position of each motor.

[0029] Based on the average value of the rotor initial position, the target position difference between the rotor initial position and the average value of the rotor initial position for each motor is determined respectively;

[0030] For each motor, the target position difference is determined as the target rotor position difference.

[0031] Optionally, the step of adjusting the rotor position of each motor according to a preset graded adjustment strategy based on the target rotor position difference, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent, includes:

[0032] If the target rotor position difference exceeds the preset rotor position error range, the preset target adjustment parameters corresponding to the graded adjustment strategy are extracted, and the average value of the rotor initial position is calculated based on the initial rotor position of each motor to determine the average value of the rotor initial position.

[0033] Based on the initial rotor position of each motor, combined with the target adjustment parameters and the average value of the initial rotor position, the rotor position of each motor is adjusted according to the graded adjustment strategy, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent.

[0034] The steps of the control method. Secondly, embodiments of this application provide a starting control system for a single inverter supporting multiple motors, comprising: an inverter and at least two motors electrically connected to the inverter; the inverter is configured to implement the starting control method according to any one of claims 1 to 7.

[0035] Thirdly, embodiments of this application provide an electrical device, including: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; the memory is used to store computer programs; and the processor, when executing the computer program stored in the memory, implements the steps of the startup control method as described in any of the first aspects.

[0036] Fourthly, embodiments of this application provide a computer storage medium storing computer-executable instructions for performing the steps of the startup control method as described in any of the first aspects.

[0037] The starting control method, system, device, and medium for a single inverter supporting multiple motors provided in this application embodiment inject high-frequency square wave signals into each motor connected to the single inverter and obtain response signals during the motor starting phase. Signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor. The initial rotor position of each motor is obtained through phase-locked loop per-unit processing. Then, a target rotor position difference is determined based on the initial rotor position. The rotor position is adjusted according to a graded adjustment strategy based on the target rotor position difference until the rotor positions of each motor are consistent, thereby controlling the synchronization of each motor. This achieves precise synchronous starting of multiple motors, simplifies the system structure, reduces costs, and improves the operational reliability during the multi-motor starting phase. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0041] Figure 1 A flowchart illustrating the steps of a single inverter-driven multi-motor start-up control method provided in this application embodiment;

[0042] Figure 2 This application provides a schematic diagram of a phase-locked loop structure as an example;

[0043] Figure 3 A schematic diagram of an equivalent structure of a phase-locked loop is provided as an example of this application;

[0044] Figure 4 This is a schematic diagram illustrating the per-unitization process using a per-unitized phase-locked loop position observer, as provided in an example of this application.

[0045] Figure 5 A schematic diagram illustrating the starting control principle of a single inverter supporting multiple motors, as an example of this application;

[0046] Figure 6 A schematic diagram of the start-up control process of a single inverter supporting multiple motors is provided for an embodiment of this application;

[0047] Figure 7 A structural block diagram of a single inverter-driven multi-motor start-up control system provided in this application embodiment;

[0048] Figure 8 This is a schematic diagram of the structure of an electrical device provided in an embodiment of this application. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0051] The large number of power electronic components in multi-motor drive structures leads to large system size and high hardware complexity, limiting their application. Using a single inverter to connect to a multi-motor drive structure significantly reduces the number of power electronic components, resulting in reduced system cost, size, and dimensions. This simplifies the control system hardware complexity and enables high-precision, stable control during the startup of a single-inverter-driven multi-motor system. However, in actual operation, differences in motor load and inconsistent motor parameters inevitably exist during the startup of a single-inverter-driven multi-motor system, limiting the synchronous startup control of the multi-motor system.

[0052] Initial rotor position identification plays a crucial role in the starting performance of multi-motor systems. Among various rotor position identification methods, the high-frequency injection method based on rotor salient pole characteristics is a widely used and effective method. It does not rely on the motor back EMF, has excellent control performance at zero and low speeds, and is suitable for synchronous starting control of multi-motor systems. However, the traditional high-frequency pulse injection method requires the use of a filter to process the motor response current. This filter causes current phase lag, which in turn affects the accuracy of rotor position identification.

[0053] To accurately identify the initial rotor position, existing technologies primarily utilize encoders and Hall effect sensors to detect the rotor's initial position before motor startup. However, using additional hardware such as encoders and Hall effect sensors to detect rotor position further increases the number of electronic components, leading to problems such as large control system size and high hardware complexity, thus limiting the application of multi-motor drive systems.

[0054] Therefore, optimizing rotor position identification methods, simplifying system structure, and improving the reliability of multi-motor synchronous starting have become urgent problems to be solved in single-inverter multi-motor drive systems.

[0055] Based on the above, this application provides a starting control method, system, device, and medium for a single inverter supporting multiple motors. By injecting a high-frequency square wave signal into the motor windings through a single inverter during motor startup, the initial rotor position is identified using the high-frequency response signal. The target rotor position difference is determined based on the initial rotor positions of each motor. Therefore, the rotor positions of each motor are adjusted according to a preset graded adjustment strategy based on the target rotor position difference. This allows for synchronous starting of all motors when their rotor positions are consistent. This achieves synchronous starting and operation control of multiple motors from a single inverter while ensuring stable starting and rapid response, improving the reliability of synchronous starting of multiple motors, and simplifying the system structure and hardware complexity. This solves the problem of large system size and high hardware complexity caused by using additional sensors to detect rotor positions in existing related technologies.

[0056] In practical implementation, considering that the sinusoidal signal contains only a single frequency component, its response to rotor position changes may not be sensitive enough, and the sinusoidal signal requires a more complex signal processing algorithm; while the high-frequency square wave has rich harmonic components, which can improve detection sensitivity, especially at low speed or zero speed, the harmonic components of the square wave signal are easier to detect, while the fundamental frequency signal of the sine wave may be difficult to extract due to the low speed. Therefore, in the motor start-up stage, the embodiments of this application adopt a high-frequency square wave injection method to realize the initial position identification of the motor rotor, so as to realize the synchronous start-up control of the multi-motor system based on the identified initial position of the motor rotor, thereby improving the operational reliability of the control method in the multi-motor start-up stage.

[0057] Figure 1 This is a flowchart illustrating the steps of a single inverter driving multiple motors, as provided in an embodiment of this application. In specific implementations, the single inverter driving multiple motors starting control method provided in this application can be applied to starting control scenarios where a single inverter drives at least two motors, such as... Figure 1 As shown in the embodiment of this application, the starting control method for a single inverter supporting multiple motors specifically includes the following steps:

[0058] Step 110: During the motor startup phase, a high-frequency square wave signal is injected into each motor connected to the single inverter to obtain the response signal of each motor.

[0059] Specifically, during the motor startup phase, since the rotor position of the motor is unknown, and considering that the back electromotive force signal is weak or even disappears when the motor is at low speed or zero speed, the position cannot be detected by the traditional electromotive force (Back-EMF) method. Therefore, in this embodiment, a high-frequency square wave signal is injected into the motor windings through a single inverter during motor startup, so that the motor response signal includes a high-frequency response signal stream and a fundamental response signal, and the response signal of each motor can be detected in a two-phase stationary coordinate system to obtain the response signal of each motor.

[0060] In motor control, a two-phase stationary coordinate system refers to a two-phase coordinate system in which the three-phase current signal is converted into a two-phase orthogonal signal through Clark transformation. For example, the two-phase coordinate system can be an α-β coordinate system. The motor's response signal can be used to represent the motor's response current. For example, the motor's response signal can be a two-phase current signal of the motor in the α-β coordinate system. These two-phase current signals can be used to represent the current parameters in the α-β coordinate system, specifically the response current iα of the α-axis and the response current iβ of the β-axis.

[0061] For example, under the excitation of a high-frequency square wave signal, the response signal generated by the motor can be the response current signal generated by the motor in the α-β coordinate system. This response current signal can be used to represent the response current, which includes the response current iα of the α axis and the response current iβ of the β axis. Specifically, the response current can include the high-frequency response current corresponding to the high-frequency square wave signal and the fundamental response current corresponding to the fundamental wave signal. Among them, the high-frequency response current can be divided into the high-frequency response current iαh of the α axis and the high-frequency response current iβh of the β axis, and the fundamental response current can be divided into the fundamental response current iαf of the α axis and the fundamental response current iβf of the β axis. It is approximately considered that the response current is the sum of the high-frequency response current and the fundamental response current, i.e., iα = iαh + iαf, iβ = iβh + iβf.

[0062] Step 120: Separate the signals based on the response signals of each motor to obtain the high-frequency response signals of each motor;

[0063] In this embodiment, since the motor's response signal is generated by the motor under high-frequency square wave excitation, the motor's response signal includes a high-frequency response signal stream and a fundamental response signal. It can be approximated as the superposition of the high-frequency response signal and the fundamental response signal. Specifically, after obtaining the motor's response signal, this embodiment can separate the motor's response signal for each motor using a preset separation method. This separates the high-frequency response signal containing rotor position information from the motor's response signal, allowing the rotor position information to be identified based on this high-frequency response signal. Furthermore, the initial rotor position can be determined based on the rotor position information.

[0064] Step 130: Perform phase-locked loop per-unit processing based on the high-frequency response signals of each motor to obtain the initial rotor position of each motor;

[0065] The phase-locked loop (PLL) per-unit scaling process refers to the standardization of the PLL to eliminate its dependence on motor parameters, thereby simplifying the control structure and enhancing its adaptability. In this step, the high-frequency response signal of each motor is input into the per-unit PLL position observer. The observer performs per-unit scaling to obtain the motor's rotor position information, which can then be used to determine the initial rotor position, achieving high-precision identification. The per-unit PLL position observer can be a PLL with per-unit calculation capabilities, enabling it to perform per-unit scaling for error standardization, simplifying the control structure and enhancing its stability.

[0066] Specifically, the open-loop transfer function G based on the phase-locked loop structure OL (s) and closed-loop transfer function G CL (s) Perform stability analysis, such as based on the open-loop transfer function expression of a traditional phase-locked loop structure. Closed-loop transfer function expression of traditional phase-locked loop structure Stability analysis reveals that the phase-locked loop (PLL) error amplification factor is related to the amplitude and frequency of the injected signal and the motor inductance value. The closed-loop characteristics of the system are also related to the motor parameters and the injected signal, making PLL parameter design difficult.

[0067] In the transfer function, 1 / S represents an integral operation, which physically means performing time integration on the input signal. The proportional gain Kp and integral gain Ki are two key parameters in the proportional-integral-derivative (PID) controller and are not affected by other additional parameters. The proportional gain Kp determines the system's response speed to errors, and the integral gain Ki determines the system's ability to eliminate steady-state errors.

[0068] For example, such as Figure 2 As shown, a phase-locked loop (PLL) structure can specifically include: a phase detector (PD), a loop filter (LF), and a voltage-controlled oscillator (VCO). The PD outputs a phase error signal e(t), representing the phase difference between the input signal and the feedback signal. For example, the input signal could be the current parameter of the motor at a certain moment in the α-β coordinate system, which includes the α-axis current parameter i. αθ and β-axis current parameter i βθ The feedback signal can include rotor position information θ output by the VCO. This rotor position information θ can refer to the electrical angle θe or mechanical angle θm of the motor rotor in space. The electrical angle θe reflects the periodic change of the motor's magnetic field. For example, the electrical angle θe can be determined by multiplying the number of pole pairs P of the motor by the mechanical angle θm according to the formula θe=P×θm. The LF can be configured as a low-pass filter (LPF) to smooth the phase error signal e(t), remove high-frequency noise, and output a control quantity to adjust the VCO. For example, the control quantity output by the LF can be the speed ω, which is related to the signal frequency.

[0069] To address the challenge of designing phase-locked loop (PLL) parameters, this embodiment employs error per-unit scaling to simplify the control structure and enhance its stability. Specifically, based on the closed-loop transfer function expression of the PLL... It can be seen that the closed-loop transfer function G CL (s) is derived from the open-loop transfer function G OL (s) is calculated and can be based on the open-loop transfer function expression. Determine the standardization baseline value E, such as Figure 3 As shown, the open-loop transfer function can be used. Dividing by the standardization reference value E, we obtain the target open-loop transfer function between the input signal θr and the output signal θr*. Then the target open-loop transfer function Substitute into the closed-loop transfer function expression By performing calculations, we can obtain the simplified formula for the closed-loop transfer function. Right now Furthermore, it is possible to utilize the simplified closed-loop transfer function expression formula. Construct a per-unit PLL position observer to perform per-unit processing, such as... Figure 4 As shown, the rotor position information θ of the motor can be calculated.

[0070] In this context, the per-unit processing reference value E is equivalent to a coefficient in the phase-locked loop equivalent structure. Specifically, it can be the current reference value divided by the per-unit processing, such as the α-axis current parameter i of the motor in the α-β coordinate system at a certain moment when the input signal is the per-unit processing. αθ and β-axis current parameter i βθ In this case, the current reference value can be

[0071] Based on the simplified closed-loop transfer function expression formula It can be seen that the closed-loop characteristics of the phase-locked loop position observer after per-unit scaling are only related to the proportional gain Kp and integral gain Ki of the system. That is, the closed-loop characteristics of the phase-locked loop position observer after per-unit scaling are only related to the system parameters themselves and are not affected by other additional parameters. Therefore, by standardizing the phase-locked loop position observer, the control structure can be simplified and it can have a strong stability.

[0072] Step 140: Determine the target rotor position difference based on the initial rotor position of each motor;

[0073] The target rotor position difference can refer to the position difference that needs to be adjusted, calculated based on the initial rotor positions of each motor. Specifically, in this embodiment, after determining the initial rotor positions of each motor connected to the single inverter, the rotor position difference between each motor is calculated based on the initial rotor positions of each motor, so as to determine the target rotor position difference that needs to be adjusted at each moment.

[0074] For example, when a single inverter connects two motors, the rotor position difference Δθ between the two motors can be calculated based on the initial rotor positions of the two motors. The rotor position difference can be calculated using a preset bisection method to determine the target rotor position difference that needs to be adjusted at each moment. For example, half of the rotor position difference can be determined as the target rotor position difference, i.e., the target rotor position difference is Δθ / 2.

[0075] For example, when a single inverter is connected to three or more motors, the standard deviation of the rotor position between each motor can be calculated based on the initial rotor position of each motor. The target rotor position difference to be adjusted at each moment can then be determined based on this standard deviation δ. For instance, a pre-defined bisection method can be used to calculate this standard deviation, and half of the standard deviation can be used as the target rotor position difference. Here, the standard deviation of the rotor position between each motor refers to the standard deviation corresponding to the initial rotor position of each motor.

[0076] Step 150: Based on the target rotor position difference, adjust the rotor position of each motor according to a preset graded adjustment strategy so as to control the synchronous start of each motor when the rotor positions of each motor are consistent.

[0077] Specifically, in this embodiment of the application, after obtaining the target rotor position difference, the rotor position of each motor can be adjusted according to the target rotor position difference and a preset graded adjustment strategy. This allows for rapid adjustment of the rotor position of each motor while ensuring stable startup of multiple motors. The rotor position difference between the motors gradually decreases until the rotor positions of all motors are consistent, at which point the adjustment stops and the motors are started synchronously. This achieves synchronous startup of multiple motors.

[0078] In summary, this embodiment of the application, during the motor startup phase, injects high-frequency square wave signals into each motor connected to the single inverter to obtain the response signals of each motor. High-frequency response signals of each motor are then extracted from these response signals. Subsequently, phase-locked loop per-unit processing is performed on the high-frequency response signals of each motor to obtain the initial rotor position of each motor. Compared with existing related technologies, the use of filters is eliminated, thereby eliminating the influence of filters on current phase and current response speed, improving the rotor position identification accuracy during the motor startup phase, resulting in better rotor initial position identification performance. Furthermore, it eliminates the need for additional hardware such as encoders and Hall sensors to detect the initial rotor position. This method effectively reduces the number of power electronic components, thereby reducing system cost, volume, and size. It simplifies the system structure of the multi-motor control system and reduces hardware complexity. Then, based on the initial rotor position of each motor, the target rotor position difference is determined. Based on the target rotor position difference, the rotor position of each motor is adjusted according to a preset hierarchical adjustment strategy. This allows for rapid adjustment of the rotor position of each motor while ensuring stable startup of multiple motors. The rotor position difference between the motors gradually decreases until the rotor positions of all motors are consistent, thus controlling the synchronous startup of each motor. This achieves smooth control of synchronous startup of multiple motors and improves the operational reliability during the startup phase of multiple motors.

[0079] In some optional embodiments of this application, the motor's response signal can be a motor response current signal, which can be used to represent the motor's response current in a two-phase stationary coordinate system. In specific implementations, considering that the high-frequency square wave injection method can still work effectively at low speeds, and that the steep edges of the high-frequency square wave signal can quickly excite the motor's transient response, making it suitable for dynamic position detection, step 110 may optionally include the following sub-steps:

[0080] Sub-step 1101: Determine the rotational speed of each motor connected to the single inverter;

[0081] Sub-step 1102: When the speed of each motor is lower than the preset speed, based on the fundamental frequency of the motor, the high-frequency square wave voltage signal is injected in a two-phase rotating coordinate system through a single inverter, wherein the frequency of the high-frequency square wave signal is greater than the fundamental frequency.

[0082] Sub-step 1103: Extract the response signals of each motor in the two-phase stationary coordinate system.

[0083] The preset speed refers to a pre-set speed threshold. This threshold is used to determine whether the motor has started normally. If the speed of a motor exceeds this threshold, it is considered to have started normally and entered the running state. If the speed of a motor is not greater than the threshold, it is considered to be in the starting stage. For example, the preset speed can be set to zero so that if the motor speed exceeds the threshold, it is considered to be in the running state. The fundamental frequency of the motor can refer to the frequency of the fundamental signal of the motor. The fundamental frequency of the motor can be determined by the fundamental frequency injected into the motor. For example, the fundamental frequency can be set to a frequency much lower than the frequency of a high-frequency square wave signal, and this fundamental frequency can be used to determine the operating frequency of the motor. For example, the operating frequency of the motor can be equal to the fundamental frequency.

[0084] Specifically, in order to acquire the rotor position information of the motor under sensorless control and optimize the control performance of multi-motor synchronous start-up, this embodiment of the application can detect the speed of each motor connected to the single inverter after the motor is powered on, and determine whether the speed of each detected motor exceeds a preset speed. When the speed of each motor is lower than the preset speed, the motor is considered to be in the start-up stage. Then, when the speed of each motor is lower than the preset speed, the frequency of the high-frequency square wave signal is determined according to the fundamental frequency of the motor. Based on the frequency of the high-frequency square wave signal, a high-frequency pulse width modulation signal is generated by digital circuitry. As the high-frequency square wave signal, it is injected into the motor windings of each motor connected to the single inverter in a two-phase rotating coordinate system. This causes each motor to generate a corresponding response current under the excitation of the high-frequency square wave signal. The response current generated by the motor can be collected in a two-phase stationary coordinate system such as the α-β coordinate system, thereby obtaining the response current signal of each motor.

[0085] Among them, the two-phase rotating coordinate system refers to the rectangular coordinate system that rotates synchronously with the rotor flux linkage. For example, the two-phase rotating coordinate system can be the dq coordinate system composed of the direct axis (d-axis) and the quadrature axis (q-axis); the high-frequency square wave signal can be a high-frequency current signal or a high-frequency voltage signal, and the embodiments of this application do not limit it.

[0086] In some optional embodiments of this application, high-frequency square wave signals can be directly generated by simple digital circuits or switching devices. For example, a high-frequency pulse width modulation (PWM) signal can be generated by digital circuits as the injected high-frequency square wave signal. This is simple to implement, has low hardware cost, and does not require complex filtering or modulation circuits. Furthermore, the rising / falling edges and duty cycle changes of the high-frequency square wave signal are easily extracted by simple detection circuits. For example, the rising / falling edge information of the high-frequency square wave signal can be extracted by comparators or zero-point detection, thereby reducing the dependence on signal processing algorithms and making the signal processing algorithms simpler. For example, by detecting the edges (such as rising / falling edges) or zero points of the square wave, the square wave feature information can be directly extracted to determine the motor rotor position based on the extracted square wave feature information. In addition, the rapid changes of the square wave signal are suitable for scenarios that require rapid adjustment. For example, the steep edges of the square wave can provide a faster dynamic response than a sine wave. That is, the rapid changes of the square wave are suitable for scenarios that require rapid adjustment (such as motor transient processes).

[0087] Optionally, in this embodiment of the application, signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor. Specifically, this may include the following sub-steps:

[0088] Sub-step 1201: Determine the high-frequency response current characteristics corresponding to the high-frequency square wave signal;

[0089] Sub-step 1202: Based on the high-frequency response current characteristics, extract the modulation response signal generated by the high-frequency square wave signal in the two-phase stationary coordinates of each motor from the response signal of each motor.

[0090] Sub-step 1203: For each motor, the modulation response signal is determined as the high-frequency response signal.

[0091] The high-frequency response current characteristic refers to the characteristics of the high-frequency response current, specifically representing the characteristic that the amplitude of the high-frequency square wave response current is equal but the direction is opposite. Specifically, since the frequency of the injected high-frequency square wave signal is much greater than the fundamental frequency, the fundamental frequency can be approximated as constant at adjacent sampling times. Based on the characteristic that the amplitude of the high-frequency square wave response current is equal but the direction is opposite, the high-frequency response current characteristic corresponding to the high-frequency square wave signal can be generated. This characteristic represents the characteristic that the amplitude of the high-frequency square wave response current is equal but the direction is opposite. Subsequently, based on this high-frequency response current characteristic, and utilizing the characteristic that the amplitude of the high-frequency square wave response current is equal but the direction is opposite, the modulation response signal generated by the high-frequency square wave signal in the two-phase stationary coordinates of the motor can be extracted from the motor's response signal. The extracted modulation response signal is then identified as the high-frequency response signal corresponding to the high-frequency square wave signal.

[0092] Optionally, embodiments of this application can utilize the characteristic that the amplitudes of the high-frequency square wave response currents are equal but their directions are opposite to determine the current difference between adjacent sampling times as a high-frequency response current characteristic. This allows for the separation of the high-frequency response current and the fundamental response current through the current difference between adjacent sampling times. Furthermore, a high-frequency response current signal can be generated based on the high-frequency response current, and a fundamental response current signal can be generated based on the fundamental response current. For example, based on the characteristic that the fundamental current is approximately constant between adjacent sampling times, and that the amplitudes of the high-frequency square wave response currents are equal but their directions are opposite, the calculation formulas for the high-frequency response current and the fundamental response current can be determined according to the response current calculation formula.

[0093] The formula for calculating the response current is as follows:

[0094] The formula for calculating the high-frequency response current is:

[0095] The formula for calculating the fundamental response current is:

[0096] It should be noted that i α (k) represents the response current along the α axis at time k, i αh (k) represents the high-frequency current along the α axis at time k, i αf (k) represents the fundamental response current along the α axis at time k. βf(k) represents the fundamental response current along the β axis at time k, i βh (k) represents the high-frequency response current of the β axis at time k, k+1 is time k+1, and k+2 is time k+2.

[0097] As can be seen, the embodiments of this application can separate the fundamental frequency response signal and the high frequency response signal of the motor from the current response signal based on the high frequency response current calculation formula and the fundamental frequency response current calculation formula. This is based on the characteristic that the amplitude of the fundamental frequency current signal is different from that of the harmonic current signal, and that the amplitude of the high frequency square wave response current is equal but opposite in direction. This allows the initial position of the motor rotor to be identified based on the high frequency response signal.

[0098] Of course, in addition to using the above-mentioned current signal separation method to separate the high-frequency response signal, other separation methods can also be used in the embodiments of this application to separate the signal, such as Fourier transform, wavelet transform, or orthogonal signal separation method, to separate the high-frequency component signal corresponding to the high-frequency square wave signal, so as to use the separated high-frequency component signal as the high-frequency response signal of the motor for the initial position identification of the motor rotor. The embodiments of this application do not impose specific limitations on this.

[0099] The current separation method is also applicable to deriving current responses in other coordinate systems. For example, the high-frequency excitation corresponding to the high-frequency response current in the α-β coordinate system can be expressed as:

[0100]

[0101] Where iαh and iβh can be used to represent the high-frequency response current generated in the α-β coordinate system, iαh represents the high-frequency response current along the α-axis, iβh represents the high-frequency response current along the β-axis, A(θ) is the coordinate transformation matrix, Ld is the d-axis inductance of the motor, Lq is the q-axis inductance of the motor, and U... dh Let U be the high-frequency stator voltage along the d-axis in the dq coordinate system. qh Let A(θ) be the high-frequency stator voltage along the q-axis in the dq coordinate system. The stator voltage equation can be transformed from the three-phase abc coordinate system to the dq coordinate system using a transformation formula, such as the formula for calculating the coordinate transformation matrix A(θ). Expression for high-frequency square wave signals Substitute into the high-frequency current calculation formula A simplified formula for calculating the high-frequency response signal can be obtained.

[0102] Under high-frequency square wave excitation, when the motor is at low speed or stationary, and the frequency of the injected high-frequency square wave signal is much higher than the fundamental frequency, the effects of back EMF and resistance voltage drop can be ignored, and the simplified high-frequency response signal calculation formula can be used. The motor's response signal can be simplified and converted to the α and β axes to obtain the corresponding high-frequency response currents iαh and iβh under the α and β axes. These currents can then be used as the current parameters to be identified and extracted, and input into a per-unit phase-locked loop position observer for per-unit processing to obtain the initial rotor position of the motor. Here, -1 represents the inverse transformation of the matrix; U h The value represents the injected high-frequency voltage amplitude, and (-1)^k represents the sign of the square wave signal. The expression for the high-frequency square wave signal is... Used to represent the injected high-frequency square wave signal.

[0103] In some optional embodiments of this application, the per-unit phase-locked loop position observer includes a rotor position observer; the rotor position observer functions in two parts: first, it calculates the input two-phase α and β axis high-frequency response currents to decouple and obtain rotor error information; second, it performs phase-locking on the obtained rotor position error information to obtain estimated rotor position information θ. Optionally, step 130 above may specifically include the following sub-steps, including:

[0104] Sub-step 1301: Input the high-frequency response signal into the rotor position observer;

[0105] Sub-step 1302: Calculate the high-frequency response signal using the rotor position observer to obtain rotor position error information;

[0106] Sub-step 1303: Based on the rotor position error information, perform per-unit processing to obtain the initial rotor position of each motor.

[0107] Specifically, after identifying the rotor position information of the motor using high-frequency square wave signals, error normalization processing can be used to construct a rotor position observer. The rotor position observer can then be used to identify and extract the precise initial rotor position, thereby improving the operational reliability of the control method during the multi-motor startup phase.

[0108] As an example of this application, taking the synchronous starting of two motors driven by a single inverter as an example, in the motor three-loop control process, such as Figure 5As shown, during the startup phase, the output signal can be adjusted by combining the proportional (P) and integral (I) terms based on the difference between the reference angular velocity and the measured feedback angular velocity through the speed loop proportional-integral (PI) control. This reduces system errors and improves stability. For example, the adjustment output signal of the first motor can be output through the speed loop PI control based on the difference between the reference angular velocity ωrf1 and the measured feedback angular velocity ωr1, thereby reducing system errors and improving stability. Similarly, the adjustment output signal of the second motor can be output through the speed loop PI control based on the difference between the reference angular velocity ωrf2 and the measured feedback angular velocity ωr2, thereby reducing system errors and improving stability.

[0109] In speed loop control, PI control can be used to adjust the motor's output torque or voltage, enabling the actual speed to quickly follow the target speed and eliminating steady-state errors. This allows for the acquisition of the dq-axis reference current value, which can be subtracted from the actual feedback value. This difference is then processed through the current loop PI control and subsequently through a high-frequency square wave voltage signal, such as... Figure 6 As shown, a high-frequency square wave voltage signal is injected into the motor winding to generate a modulated response current in the α-β coordinate system. Then, the response current signals of each motor can be extracted in the α-β coordinate system. Subsequently, the response current signals are separated to obtain high-frequency response current signals and low-frequency response current signals. Specifically, the high-frequency response current signals and low-frequency response current signals can include: the α-axis high-frequency response current signal iαh and the β-axis high-frequency response current signal iβh in the α-β coordinate system.

[0110] For example, taking the first motor connected to a single inverter as an example, the difference between the d-axis reference current value id1 of the first motor and the first actual feedback value of the first motor can be calculated, such as... Figure 5As shown, after current loop PI control, a first fundamental signal of the first motor in the dq coordinate system is generated. This first fundamental signal is superimposed with the injected first high-frequency square wave signal Uinj1 to generate a first driving voltage signal Ud1 of the first motor. After inverse Park transform, it is converted to the α-β coordinate system to obtain the α-axis voltage response signal Uα1 of the first motor. Furthermore, the difference between the q-axis reference current value iq1 of the first motor and the first actual feedback value of the first motor is calculated. After current loop PI control, a second fundamental signal of the first motor in the dq coordinate system is generated. This second fundamental signal is superimposed with the injected high-frequency square wave signal to generate a second driving voltage signal Uq1 of the first motor. After inverse Park transform, it is converted to the α-β coordinate system to obtain the β-axis voltage response signal Uβ1 of the first motor. The α-axis voltage response signal of the first motor is then... The voltage response signal Uα1 and the β-axis voltage response signal Uβ1 are determined as the response current signals corresponding to the first motor. Then, the response current signals are separated to obtain the α-axis high-frequency response current signal iαh1 and the β-axis high-frequency response current signal iβh1 of the first motor in the α-β coordinate system. The α-axis high-frequency response current signal iαh1 and the β-axis high-frequency response current signal iβh1 of the first motor in the α-β coordinate system can be input into the phase-locked loop for per-unit processing. That is, the α-axis high-frequency response current signal iαh1 and the β-axis high-frequency response current signal iβh1 are input into the rotor position observer in the phase-locked loop to calculate the rotor position error information of the first motor. Based on the rotor position error information, per-unit processing is performed to obtain the initial rotor position θ1 of the first motor.

[0111] For example, the difference between the d-axis reference current value id2 of the second motor and the first actual feedback value of the second motor can be calculated. Figure 5As shown, after current loop PI control, a first fundamental signal of the second motor in the dq coordinate system is generated. This first fundamental signal is then superimposed with the injected second high-frequency square wave signal Uinj2 to generate a first drive voltage signal Ud2 for the second motor. After inverse Park transform, this signal is converted to the α-β coordinate system to obtain the α-axis voltage response signal Uα2 of the second motor. Furthermore, the difference between the q-axis reference current value iq2 of the second motor and the first actual feedback value of the second motor is calculated. After current loop PI control, a second fundamental signal of the second motor in the dq coordinate system is generated. This second fundamental signal is then superimposed with the injected high-frequency square wave signal to generate a second drive voltage signal Uq2 for the second motor. After inverse Park transform, this signal is converted to the α-β coordinate system to obtain the β-axis voltage response signal of the second motor. Uβ2, the α-axis voltage response signal Uα2 and the β-axis voltage response signal Uβ2 of the second motor are determined as the corresponding response signals of the second motor. Thus, the α-axis high-frequency response current signal iαh2 and the β-axis high-frequency response current signal iβh2 of the second motor in the α-β coordinate system can be obtained. Then, the α-axis high-frequency response current signal iαh2 and the β-axis high-frequency response current signal iβh2 of the second motor in the α-β coordinate system can be input into the phase-locked loop for per-unit processing. That is, the α-axis high-frequency response current signal iαh2 and the β-axis high-frequency response current signal iβh2 are input into the rotor position observer in the phase-locked loop to calculate the rotor position error information of the second motor. Based on the rotor position error information, per-unit processing is performed to obtain the initial rotor position θ1 of the second motor.

[0112] Specifically, due to the reluctance effect of motors—that is, the stator windings of a motor have different reluctance at different rotor positions, such as the salient pole effect of a permanent magnet synchronous motor (PMSM)—a high-frequency square wave voltage will generate a modulated response current in the α-β coordinate system, the amplitude and phase of which are related to the rotor position. Therefore, the example in this application can utilize the current response caused by the change in reluctance, such as amplitude modulation or phase shift based on the current signal, to infer the rotor position of the motor. High-frequency components are separated by a filter, and combined with algorithms (such as phase-locked loops, where the core function of the Park transform is to decouple the relationship between the motor's voltage and current, thus simplifying the control problem of a three-phase AC motor into the control of two independent variables, resulting in loop and phase detection) to extract the rotor angle, and then determine the rotor position information of the motor based on the extracted rotor angle.

[0113] Here, Ud is the driving voltage signal along the d-axis, and Uq is the driving voltage signal along the q-axis. After inverse Park transformation, these signals can be converted to an α-β coordinate system. The reference voltage vector (Va, Vb, Vc) can then be adjusted based on the voltage response signal in the α-β coordinate system. After Space Vector Pulse Width Modulation (SVPWM), the voltage can finally be controlled by a transistor such as an Insulated-Gate Transistor. The system uses power devices such as Bipolar Transistors (IGBTs) to control the operation of the drive motor. The next part is the feedback section. The three-phase currents ia, ib, and ic are transformed by Clark to obtain the α-axis current response signal iα and the β-axis current response signal iβ. High-frequency components iαh and iβh are extracted from these signals and processed by a phase-locked loop to obtain the feedback angular velocity ωr. iα and iβ are then transformed by Park to obtain the low-frequency response current signals id and iq, which are also fed back to the system's dq-axis voltage and current. For example, the three-phase currents ia, ib, and ic of the first motor are transformed by Clark to obtain the α-axis current response signal iα1 and the β-axis current response signal iβ1. The high-frequency components iαh1 and iβh1 of the first motor are extracted from these signals and processed by a phase-locked loop. The feedback angular velocity ωr1 of the first motor is obtained through loop processing. The current response signals iα1 on the α axis and iβ1 on the β axis are transformed by Park to obtain the low-frequency response current signals id1 and iq1 of the first motor. Similarly, the three-phase currents ia, ib, and ic of the second motor are transformed by Clark to obtain the current response signals iα2 on the α axis and iβ2 on the β axis. The high-frequency components iαh2 and iβh2 of the second motor are extracted from the current response signals iα2 on the α axis and iβ2 on the β axis, respectively. The feedback angular velocity ωr2 of the second motor is obtained through phase-locked loop processing. The current response signals iα2 on the α axis and iβ2 on the β axis are transformed by Park to obtain the low-frequency response current signals id2 and iq2 of the second motor.

[0114] The core function of the Clark transform is to convert current / voltage signals in a three-phase symmetrical or asymmetrical system into a representation in a two-phase Cartesian coordinate system (α-β), thereby simplifying controller design and improving computational efficiency. The Clark transform is typically a preceding step to the Park transform, converting the three-phase signals to the α-β coordinate system, and then using the Park transform to convert them to the dq-axis coordinate system.

[0115] As can be seen, in this embodiment of the application, when the speed of each motor is lower than the preset speed, a high-frequency square wave signal can be injected into the motor winding of each motor based on the fundamental frequency of each motor to obtain the response signal of each motor. Based on the response signal, signal separation is performed to separate the high-frequency response current and the low-frequency current signal. The high-frequency response signal is used for rotor position identification, which improves the accuracy of rotor position identification. The low-frequency current signal can be used as the fundamental response signal to be connected to the system current loop for normal closed-loop control, thereby realizing system current loop feedback.

[0116] As an example of this application, in a multi-motor synchronous start control system, such as Figure 6 As shown, a high-frequency square wave signal is input to identify the initial rotor position using the high-frequency response current. The fundamental response current can be used to access the system current loop for normal closed-loop control. For example, after extracting the motor's response current signal, the high-frequency response signal and low-frequency current signal can be separated from the motor's response signal current according to a preset signal separation method. That is, the response current signal is separated to obtain the high-frequency response signal and low-frequency current signal. The high-frequency response signal is used for rotor position identification, improving the accuracy of rotor position identification. The high-frequency response current signal is input into the rotor position observer to identify the rotor position information of the two motors, namely, the rotor position information of the first motor and the rotor position information of the second motor. The low-frequency current signal can be used as the fundamental response signal to access the system current loop for normal closed-loop control, realizing system current loop feedback.

[0117] In an optional embodiment of this application, determining the target rotor position difference based on the initial rotor position of each motor includes the following sub-steps:

[0118] Sub-step 1401: Determine the number of motors;

[0119] Sub-step 1402: If the number of motors is greater than a preset threshold for the number of motors, determine the standard deviation of the initial rotor position based on the initial rotor position of each motor.

[0120] Sub-step 1403: Determine the target rotor position difference using the standard deviation of the rotor initial position.

[0121] The number of motors refers to the total number of motors connected to a single inverter. For example, if a single inverter is connected to four motors, the number of motors is four. The preset threshold for the number of motors can be set according to the requirements for stable start-up control of multiple motors, such as three or four. This application does not limit this.

[0122] For example, if the preset motor number threshold is 4, and the number of motors currently connected to the single inverter is 5, it can be determined that the number of motors currently connected to the single inverter exceeds the preset motor number threshold. At this time, the standard deviation can be calculated based on the initial rotor position of each motor connected to the single inverter, and the calculated standard deviation or standard deviation can be determined as the target rotor position difference.

[0123] Optionally, determining the target rotor position difference based on the initial rotor position of each motor in this embodiment may further include: when the number of motors is less than a preset threshold for the number of motors, calculating the average value of the initial rotor position of each motor connected to the single inverter to obtain the average value of the initial rotor position of each motor; based on the average value of the initial rotor position, determining the target position difference between the initial rotor position of each motor and the average value of the initial rotor position; and for each motor, determining the target position difference as the target rotor position difference.

[0124] For example, if the preset motor number threshold is 4, and the number of motors currently connected to the single inverter is 2, it can be determined that the number of motors currently connected to the single inverter does not exceed the preset motor number threshold. At this time, the average value of the rotor initial position can be calculated based on the initial rotor position of each motor connected to the single inverter to determine the average value of the rotor initial position. Then, for each motor, the position difference between the average value of the rotor initial position and the initial rotor position of the motor can be determined as the target rotor position difference for that motor, so that subsequent operations can be based on this target rotor position difference.

[0125] In this embodiment, when the number of motors equals a preset threshold, the average value of the initial rotor position of each motor connected to the single inverter can be calculated to obtain the average value of the initial rotor position of each motor. Then, based on the average value of the initial rotor position, the target position difference between the initial rotor position of each motor and the average value of the initial rotor position can be calculated. For each motor, the target position difference can be determined as the target rotor position difference. Alternatively, the standard deviation of the initial rotor position can be determined based on the initial rotor position of each motor, and the target rotor position difference can be determined using the standard deviation of the initial rotor position. This embodiment does not limit this.

[0126] Specifically, in this embodiment of the application, after determining the target rotor position difference based on the initial rotor position of each motor, the rotor position of each motor can be adjusted according to a preset graded adjustment strategy based on the target rotor position difference of each motor, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent, thereby realizing the synchronous start of multiple motors.

[0127] In some optional embodiments of this application, the target rotor position difference Δθ can be compared with a preset rotor position error range. When the target rotor position difference does not exceed the preset rotor position error range (i.e., when the target rotor position difference Δθ is within the preset rotor position error range), a preset graded adjustment strategy can be used. The position adjustment parameter Δθ / 2 at each moment is calculated using a bisection method, and Δθ / 2 is used as a feedback value for rotor position adjustment. For example, if the initial rotor position θ1 of the first motor is less than the initial rotor position θ2 of the second motor (i.e., θ1 < θ2), the sum of the initial rotor position θ1 of the first motor and the position adjustment parameter Δθ / 2 is used as the initial rotor information for the synchronous start of the first motor. The rotor position of the first motor is then adjusted. The difference between the initial rotor position θ2 of the second motor and the position adjustment parameter Δθ / 2 can be used as the initial rotor information for the synchronous start of the second motor. Thus, rotor position control for synchronous start of the motors can be performed based on the initial rotor information of the two motors, enabling synchronous start of the two motors when their rotor positions are the same, improving the stability and reliability of synchronous start of the two motors. Alternatively...

[0128] When the target rotor position difference exceeds the preset rotor position error range, that is, when the target rotor position difference is not within the preset rotor position error range, the rotor position of the motor can be adjusted multiple times using a small range of position adjustment parameters according to the set graded adjustment strategy until the rotor position difference between the motors becomes zero, that is, when the initial rotor positions of the motors are consistent, the motors are controlled to start simultaneously, so as to complete the synchronous start of the two motors when the rotor positions of the two motors are the same, thereby improving the stability and reliability of the synchronous start of the two motors.

[0129] Optionally, in this embodiment, based on the target rotor position difference, the rotor position of each motor is adjusted according to a preset hierarchical adjustment strategy to control the synchronous start of each motor when the rotor positions of each motor are consistent. Specifically, this may include: when the target rotor position difference exceeds a preset rotor position error range, extracting the preset target adjustment parameters corresponding to the hierarchical adjustment strategy, and calculating the average value of the initial rotor position based on the initial rotor position of each motor to determine the average value of the initial rotor position; adjusting the rotor position of each motor according to the hierarchical adjustment strategy based on the initial rotor position of each motor, combined with the target adjustment parameters and the average value of the initial rotor position, to control the synchronous start of each motor when the rotor positions of each motor are consistent. The preset rotor position error range can be determined by a preset rotor error threshold. For example, if the rotor error threshold is 30°, the rotor error threshold can be used as the maximum sub-error threshold of the rotor position error range, and the negative of the rotor error threshold can be used as the minimum sub-error threshold of the rotor position error range, such that the rotor position error range is (-30°, 30°).

[0130] For example, taking a one-to-two inverter configuration, where one inverter controls the synchronous starting of two motors, such as... Figure 5 and Figure 6 As shown, if the rotor position information θ1 of the first motor and the rotor position information θ2 of the second motor are identified by the rotor position observer, the rotor position information of the two motors can be used to calculate the rotor position difference Δθ between the two motors according to the calculation formula Δθ=θ2-θ1. It can also be determined whether the rotor position difference Δθ exceeds the preset rotor position error range. For example, if the preset rotor position error range is (-30°, 30°), and the rotor position difference Δθ is not large, such as if the rotor position difference Δθ is less than the preset 30° and greater than 0°, then the bisection method can be used to calculate Δθ / 2 at each moment. Δθ / 2 is used as the feedback value to adjust the rotor position until Δθ=0, at which point the motors are controlled to start synchronously.

[0131] If the rotor position difference Δθ between the two motors is large, such as when Δθ is greater than or equal to 60°, the rotor position is adjusted multiple times using a small range corresponding to the preset target adjustment parameter until Δθ = 0, controlling the motors to start synchronously. The target adjustment parameter can represent the rotor position adjustment step size, such as 10° or 5°, and this application does not impose any restrictions on this.

[0132] In its specific implementation, this embodiment, after obtaining the difference between the two rotor positions, uses a weighted adjustment factor to achieve voltage feedback regulation. The difference between the two rotor positions is used as a feedback quantity, fed into the weighted adjustment factor for weighted calculation. The result δ calculated by the weighted calculation model is then used to adjust the reference voltage vector in real time, taking the rotor position adjustment of the first motor as an example. The result δ calculated by the weighted calculation model includes θ1 + Δθ. θ1 + Δθ is used as the initial rotor information for synchronous starting of the two motors, enabling real-time correction of the weighted model of the dual-motor vector control system. This allows the motor rotor position to be adjusted according to the voltage phase. Each adjustment is made based on the rotor position difference, and after multiple adjustments, the motor rotor phases are equal, i.e., Δθ = 0. Then, the two motors can start and operate normally in the same phase, ensuring stable starting and rapid response of multiple motors while controlling the synchronous starting of each motor.

[0133] Compared with the existing related technologies that use the rotor position information of a single motor as a reference to control the rotor position of another motor, the embodiments of this application not only ensure the stability of dual-motor start-up control, but also improve the accuracy and response speed of dual-motor start-up control. It can smoothly achieve the purpose of synchronizing rotor position information during the motor start-up stage, effectively solving the problems of poor motor start-up control stability and motor start-up failure in the multi-motor start-up process of the existing related technologies. Furthermore, it can avoid the problem of the motor entering the running state immediately after start-up due to excessive motor start-up control time, and solve the problem of single motor idling and waiting in the existing related technologies, which results in a single control method.

[0134] like Figure 7 As shown in the figure, this application embodiment also provides a starting control system for a single inverter supporting multiple motors. The starting control system for a single inverter supporting multiple motors includes: an inverter 610 and at least two motors 620 electrically connected to the inverter 610.

[0135] The inverter 6100 is configured to implement the single-inverter multi-motor start-up control method provided in any of the foregoing embodiments of this application. This method allows the single-inverter multi-motor start-up control system to inject high-frequency square wave signals into each motor connected to the single inverter during the motor start-up phase and obtain response signals. Subsequently, signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor. The initial rotor position of each motor is obtained through phase-locked loop per-unit processing. Then, the target rotor position difference is determined based on the initial rotor position, and the rotor position is adjusted according to a graded adjustment strategy based on the target rotor position difference until the rotor positions of each motor are consistent. This controls the synchronization of each motor, thereby achieving precise synchronous start-up of multiple motors, simplifying the system structure, reducing costs, and improving the operational reliability during the multi-motor start-up phase.

[0136] In practical implementation, the single-inverter multi-motor start-up control system provided in this application embodiment can be integrated into electrical equipment as a motor drive control system for the electrical equipment. This allows the electrical equipment to execute the single-inverter multi-motor start-up control method provided in this application embodiment through a control device. It employs a high-frequency square wave signal injection combined with a filterless signal separation method to avoid phase lag caused by traditional filtering. Furthermore, with the phase-locked loop per-unit processing, it can effectively improve the accuracy of rotor initial position identification. It can also design differentiated target rotor position difference calculation methods for different numbers of motors, making synchronous control more suitable for actual application scenarios. Through a graded adjustment strategy, it can take into account the advantages of coarse and fine adjustment, shortening the synchronization time and improving start-up efficiency while ensuring adjustment accuracy.

[0137] like Figure 8As shown in the figure, this application embodiment also provides an electrical device, which includes: a processor 811, a communication interface 812, a memory 813, and a communication bus 814. The processor 811, the communication interface 812, and the memory 813 communicate with each other through the communication bus 814. The memory 813 is used to store computer programs. When the processor 811 executes the computer program stored in the memory 813, it implements the steps of the single inverter driving multiple motors starting control method provided in any of the foregoing embodiments of this application.

[0138] In specific implementations, the electrical equipment in the embodiments of this application may include, but is not limited to, refrigeration equipment such as air conditioners and refrigerators, and may also include other types of electrical equipment such as washing machines. The embodiments of this application do not impose specific limitations on this.

[0139] The circuit, system, and device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0140] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a general-purpose hardware platform, or of course by hardware.

[0141] Based on this understanding, the above technical solutions, or the parts that contribute to the relevant technologies, can be embodied in the form of software products. These computer software products can be stored in computer-readable storage media, such as ROM / RAM, magnetic disks, optical disks, etc., and include several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments.

[0142] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0143] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A starting control method for a single inverter supporting multiple motors, characterized in that, The startup control method includes: During the motor startup phase, high-frequency square wave signals are injected into each motor connected to the single inverter to obtain the response signals of each motor. Signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor; The initial rotor position of each motor is obtained by performing phase-locked loop per-unit processing based on the high-frequency response signal of each motor. The target rotor position difference is determined based on the initial rotor position of each motor; Based on the target rotor position difference, the rotor position of each motor is adjusted according to a preset graded adjustment strategy so as to control the synchronous start of each motor when the rotor positions of each motor are consistent. The step of adjusting the rotor position of each motor according to a preset graded adjustment strategy based on the target rotor position difference, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent, includes: If the target rotor position difference exceeds the preset rotor position error range, the preset target adjustment parameters corresponding to the graded adjustment strategy are extracted, and the average value of the rotor initial position is calculated based on the initial rotor position of each motor to determine the average value of the rotor initial position. Based on the initial rotor position of each motor, combined with the target adjustment parameters and the average value of the initial rotor position, the rotor position of each motor is adjusted according to the graded adjustment strategy, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent.

2. The start-up control method according to claim 1, characterized in that, The response signal of the motor is a response current signal. During the motor startup phase, a high-frequency square wave signal is injected into each motor connected to the single inverter to obtain the response signal of each motor, including: Determine the rotational speed of each motor connected to the single inverter; When the speed of each motor is lower than the preset speed, based on the fundamental frequency of the motor, the high-frequency square wave signal is injected in a two-phase rotating coordinate system through a single inverter, wherein the frequency of the high-frequency square wave signal is greater than the fundamental frequency. In a two-phase stationary coordinate system, the response current signal of each motor is extracted.

3. The start-up control method according to claim 1, characterized in that, Signal separation is performed based on the response signals of each motor to obtain the high-frequency response signals of each motor, including: Determine the high-frequency response current characteristics corresponding to the high-frequency square wave signal; Based on the high-frequency response current characteristics, the modulation response signal generated by the high-frequency square wave signal in the two-phase stationary coordinate system of each motor is extracted from the response signal of each motor. For each motor, the modulation response signal is determined as the high-frequency response signal.

4. The start-up control method according to claim 1, characterized in that, The step of performing phase-locked loop per-unit processing based on the high-frequency response signals of each motor to obtain the initial rotor position of each motor includes: The high-frequency response signal is input into the rotor position observer; The rotor position error information is obtained by calculating the high-frequency response signal using the rotor position observer. The rotor position error information is normalized to obtain the initial rotor position of each motor.

5. The start-up control method according to claim 1, characterized in that, The determination of the target rotor position difference based on the initial rotor position of each motor includes: Determine the number of motors; When the number of motors is greater than a preset threshold for the number of motors, the standard deviation of the initial rotor position is determined based on the initial rotor position of each motor. The target rotor position difference is determined using the standard deviation of the rotor's initial position.

6. The start-up control method according to claim 1, characterized in that, The determination of the target rotor position difference based on the initial rotor position of each motor includes: Determine the number of motors; When the number of motors is less than a preset threshold for the number of motors, the average value of the initial rotor position of each motor connected to the single inverter is calculated to obtain the average value of the initial rotor position of each motor. Based on the average value of the initial rotor position, the target position difference between the initial rotor position and the average value of the initial rotor position for each motor is determined. For each motor, the target position difference is determined as the target rotor position difference.

7. A starting control system for a single inverter supporting multiple motors, characterized in that, include: An inverter and at least two motors electrically connected to the inverter; The inverter is configured to implement the startup control method according to any one of claims 1 to 6.

8. An electrical appliance, characterized in that, include: The system includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus. The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the startup control method as described in any one of claims 1 to 6.

9. A computer storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions are used to perform the steps of the startup control method as described in any one of claims 1-6.

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