Starting control method, system and equipment for multi-motor driven by single inverter and medium

Abstract

The invention relates to a starting control method, system and device for a multi-motor driven by a single inverter and a medium, and the method comprises the steps: injecting a high-frequency square wave signal into each motor connected with the single inverter in a motor starting stage, and obtaining a response signal of each motor; performing signal separation based on the response signal of each motor to obtain a high-frequency response signal of each motor; performing phase-locked loop per unit processing according to the high-frequency response signal of each motor to obtain an initial position of a rotor of each motor; determining a target rotor position difference according to the rotor initial position of each motor; and based on the target rotor position difference, performing rotor position adjustment of each motor according to a preset grading adjustment strategy, so as to control each motor to be synchronously started when the rotor position of each motor is consistent. Therefore, the problem of low reliability of multi-motor synchronous starting caused by low rotor position identification precision and complex system structure in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor drive control, and particularly relates to a single-inverter multi-motor starting control method, system, device and medium. BACKGROUND

[0002] With the rapid development of motor drive technology, single-inverter multi-motor drive system has become an important development direction of multi-motor drive due to its significant advantages in structure simplification, cost control, and operation stability. However, in actual application, there are inevitable problems such as load difference and motor parameter mismatch during the starting and running of the multi-motor system, which leads to challenges in synchronous starting control of the multi-motor. SUMMARY

[0003] Therefore, the present application provides a control method, system and device for synchronous driving of double permanent magnet synchronous motors to solve the problem of low reliability of multi-motor synchronous starting caused by low rotor position recognition accuracy and complex system structure in the prior art.

[0004] In a first aspect, the present application provides a single-inverter multi-motor starting control method, which comprises:

[0005] During the motor starting stage, 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] Phase-locked loop normalization processing is performed according to the high-frequency response signals of each motor to obtain the initial rotor positions of each motor;

[0008] The target rotor position difference is determined according to the initial rotor positions of each motor;

[0009] Based on the target rotor position difference, the rotor position adjustment of each motor is performed according to a preset hierarchical adjustment strategy to control the synchronous starting 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, and the injection of the high-frequency square wave signal into each motor connected to the single inverter during the motor starting stage to obtain the response signal of each motor comprises:

[0011] The rotational speeds of each motor connected to the single inverter are determined respectively;

[0012] In a case that the rotation speeds of the motors are all lower than a preset rotation speed, a high-frequency square wave voltage signal is injected in a two-phase rotating coordinate system by a single inverter based on a fundamental frequency of the motor, wherein a frequency of the high-frequency square wave signal is greater than the fundamental frequency;

[0013] The response current signals of the motors are extracted in a two-phase static coordinate system, respectively.

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

[0015] A high-frequency response current feature corresponding to the high-frequency square wave signal is determined;

[0016] According to the high-frequency response current feature, a modulation response signal generated by the high-frequency square wave signal in a two-phase static coordinate 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, phase-locked loop normalization processing is performed according to the high-frequency response signals of the motors respectively to obtain rotor initial positions of the motors, including:

[0019] The high-frequency response signals are input into a rotor position observer;

[0020] Rotor position error information is obtained by calculating the high-frequency response signals by using the rotor position observer;

[0021] The rotor initial positions of the motors are obtained by normalization processing based on the rotor position error information.

[0022] Optionally, a target rotor position difference is determined according to the rotor initial positions of the motors, including:

[0023] The number of motors is determined;

[0024] In a case that the number of the motors is greater than a preset motor number threshold, a rotor initial position standard deviation is determined according to the rotor initial positions of the motors;

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

[0026] Optionally, a target rotor position difference is determined according to the rotor initial positions of the motors, including:

[0027] The number of motors is determined;

[0028] In a case where the number of motors is less than a preset motor number threshold, an average value is calculated according to the rotor initial positions of each motor connected to a single inverter to obtain an average value of the rotor initial positions corresponding to each motor.

[0029] Based on the average value of the rotor initial positions, a target position difference between the rotor initial position of each motor and the average value of the rotor initial positions is determined.

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

[0031] Optionally, based on the target rotor position difference, rotor position adjustment of each motor is performed according to a preset hierarchical adjustment strategy to control synchronous start of each motor when the rotor positions of each motor are consistent, including:

[0032] In a case where the target rotor position difference exceeds a preset rotor position error range, a preset target adjustment parameter corresponding to the hierarchical adjustment strategy is extracted, and an average value of the rotor initial positions is determined by performing average value calculation according to the rotor initial positions of each motor.

[0033] According to the rotor initial position of each motor, the target adjustment parameter and the average value of the rotor initial positions, rotor position adjustment of each motor is performed according to the hierarchical adjustment strategy to control synchronous start of each motor when the rotor positions of each motor are consistent.

[0034] The steps of the method. In a second aspect, the embodiments of the present application provide a single-inverter multi-motor start control system, including: an inverter and at least two motors electrically connected to the inverter; the inverter is configured to implement the start control method of any one of claims 1 to 7.

[0035] In a third aspect, the embodiments of the present application provide an electrical appliance, including: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete communication with each other through the communication bus; the memory is used to store a computer program; the processor is used to execute the computer program stored on the memory to implement the steps of the start control method of any one of the first aspect.

[0036] In a fourth aspect, the embodiments of the present application provide a computer storage medium storing computer executable instructions, and the computer executable instructions are used to execute the steps of the start control method of any one of the first aspect.

[0037] The single-inverter multi-motor starting control method, system, device and medium provided by the embodiment of the application, by injecting a high-frequency square wave signal into each motor connected to the single inverter and obtaining a response signal during the motor starting stage; signal separation is performed based on the response signal of each motor to obtain the high-frequency response signal of each motor; the initial position of the rotor of each motor is obtained through phase-locked loop normalization processing, and then the target rotor position difference is determined according to the initial position of the rotor, so as to adjust the rotor position based on the target rotor position difference according to the hierarchical adjustment strategy, until the rotor positions of the motors are consistent, and then the motors are controlled to be synchronized, thereby realizing accurate synchronous starting of the multi-motor, simplifying the system structure and reducing the cost, and improving the operation reliability of the multi-motor during the starting stage. BRIEF DESCRIPTION OF DRAWINGS

[0038] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the application and, together with the specification, serve to explain the principles of the application.

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0040] One or more embodiments are exemplarily illustrated by pictures in the drawings corresponding thereto, and these exemplary illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, unless otherwise specified. The drawings in the drawings do not constitute a proportional limitation.

[0041] Figure 1 A step flowchart of a single-inverter multi-motor starting control method provided by the embodiment of the application;

[0042] Figure 2 A structure diagram of a phase-locked loop provided by an example of the application;

[0043] Figure 3 A diagram of an equivalent structure of a phase-locked loop provided by an example of the application;

[0044] Figure 4 A diagram of normalization processing by a normalization phase-locked loop position observer provided by an example of the application;

[0045] Figure 5 A single-inverter multi-motor starting control principle diagram provided by an example of the application;

[0046] Figure 6 A single-inverter multi-motor starting control flowchart provided by the embodiment of the application;

[0047] Figure 7 A structural block diagram of a single-inverter multi-motor starting control system provided for an embodiment of the present application is provided.

[0048] Figure 8 A structural schematic diagram of an electrical appliance provided for an embodiment of the present application is provided. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0050] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplicity, the components and arrangements of the examples, which are depicted in the following disclosure are shown as being in electrical communication or positional relationship with one another. It will be recognized by those skilled in the art that various components and / or devices of the examples can be combined in arrangements different than those shown in the examples without departing from the scope and spirit of the present application. In addition, well-known elements of the application, such as circuits, electrical lines, wiring, etc. are not shown in block diagram form in order to avoid obscuring the examples. It will also be appreciated that the examples can comprise any combination of some or all of the disclosed elements. In addition, various embodiments disclosed herein can be repeated with variations in some or all of the components and / or descriptions of the examples.

[0051] The number of power electronic elements in the multi-motor drive structure is relatively large, resulting in a large system volume and high hardware complexity, which limits the application of the multi-motor drive system. The single-inverter is applied to connect the multi-motor drive structure, the number of power electronic elements is significantly reduced, the system cost, volume and size are also reduced, the hardware complexity of the control system is simplified, and the single-inverter multi-motor system starting can realize high-precision and smooth control. However, in the actual single-inverter multi-motor drive system starting process, there are inevitably differences in motor load and inconsistencies in motor parameters, which limit the synchronous starting control of the multi-motor system.

[0052] The initial position recognition of the motor rotor plays a crucial role in the starting performance of the multi-motor. Among various rotor position recognition methods, the high-frequency injection method based on the rotor salient pole characteristics is a widely used and effective recognition method, which does not depend on the motor back electromotive force, has superior control effect at zero speed, and is suitable for synchronous starting control of the multi-motor system. However, in the traditional high-frequency pulse injection method, a filter is needed to process the motor response current, and the filter will cause the current phase to lag, thereby affecting the rotor position recognition accuracy.

[0053] In order to accurately identify the initial position of the rotor, the prior art mainly uses additional hardware such as an encoder and a Hall sensor to detect the initial position of the rotor before the motor starts. However, if additional hardware such as an encoder and a Hall sensor is used to detect the position of the rotor, the number of electronic components is further increased, resulting in problems such as large size of the control system, high hardware complexity, and the like, which limits the application of the multi-motor drive system.

[0054] Therefore, how to optimize the rotor position identification method, simplify the system structure and improve the reliability of the multi-motor synchronous starting has become a problem to be solved for the single-inverter-driven multi-motor drive system

[0055] Based on the above, the present application provides a single-inverter-driven multi-motor starting control method, system, device and medium. By injecting a high-frequency square wave signal into the motor winding through a single inverter when the motor starts, the initial position of the rotor is identified by using the high-frequency response signal, and the target rotor position difference is determined according to the initial position of the rotor of each motor. Therefore, according to the target rotor position difference, the rotor position of each motor can be adjusted according to the preset hierarchical adjustment strategy, so that the multi-motor synchronous starting can be controlled when the rotor positions of the motors are consistent. Thus, the single-inverter-driven multi-motor synchronous starting operation control can be completed under the premise of ensuring stable starting, fast and timely response of the multi-motor, improving the reliability of the multi-motor synchronous starting, simplifying the system structure and hardware complexity, and solving the problem of large system size and high hardware complexity caused by using additional sensors to detect the rotor position in the prior art.

[0056] In a specific implementation, considering that the sinusoidal signal only contains a single frequency component, the response to the change in the rotor position may not be sensitive enough, and the sinusoidal signal needs to rely on more complex signal processing algorithms. The high-frequency square wave has rich harmonic components, which can improve the detection sensitivity. In particular, at low speed or zero speed, the harmonic components of the square wave signal are easier to be detected, while the fundamental frequency signal of the sinusoidal wave may be difficult to extract due to the low speed. Therefore, in the motor starting stage, the high-frequency square wave injection method is used to identify the initial position of the motor rotor, so as to realize the synchronous starting control of the multi-motor system based on the identified initial position of the motor rotor, and improve the operation reliability of the control method in the multi-motor starting stage.

[0057] Figure 1 A step flowchart of a single-inverter-driven multi-motor starting control method provided by an embodiment of the present application. In a specific implementation, the single-inverter-driven multi-motor starting control method provided by the embodiment of the present application can be applied to the starting control scene of a single-inverter-driven multi-motor drive system, as shown in Figure 1 The single-inverter-driven multi-motor starting control method provided by the embodiment of the present application specifically includes the following steps:

[0058] Step 110, in the motor starting stage, high-frequency square wave signals are injected into each motor connected to the single inverter to obtain the response signals of each motor.

[0059] Specifically, in the motor starting stage, the rotor position of the motor is unknown; considering that the back-EMF signal is weak or even disappears when the motor is at low speed or zero speed, the position cannot be detected by the traditional back-EMF method, therefore, in the motor starting stage, the single inverter injects high-frequency square wave signals into the motor winding, so that the response signal of the motor contains high-frequency response signal flow and fundamental response signal, and the response signal of each motor can be detected in the two-phase stationary coordinate system to obtain the response signal of each motor.

[0060] The two-phase stationary coordinate system refers to a two-phase coordinate system in which three-phase current signals are converted into two-phase signals by Clark transformation in motor control, such as the two-phase coordinate system can be an α-β coordinate system; the response signal of the motor can be used to represent the response current of the motor, such as the response signal of the motor can be the two-phase current signal of the motor in the α-β coordinate system, which can be used to represent the current parameters in the α-β coordinate system, and specifically can be used to represent the response current iα of the α-axis and the response current iβ of the β-axis.

[0061] For example, under the excitation of the 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, which can be used to represent the response current, which contains the response current iα of the α-axis and the response current iβ of the β-axis, and the response current specifically contains the high-frequency response current corresponding to the high-frequency square wave signal and the fundamental response current corresponding to the fundamental signal; wherein 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, and the response current is approximately considered as the sum of the high-frequency response current and the fundamental response current, i.e. iα=iαh+iαf, iβ=iβh+iβf.

[0062] Step 120, respectively based on the response signal of each motor, signal separation is performed to obtain the high-frequency response signal of each motor;

[0063] In the embodiment of the present application, since the response signal of the motor is a signal generated by the motor under excitation of a high-frequency square wave signal, the response signal of the motor contains a high-frequency response signal and a fundamental response signal, and it can be approximately considered that the response signal of the motor is superposition of the high-frequency response signal and the fundamental response signal. Specifically, after obtaining the response signal of the motor, the embodiment of the present application can separate the response signal of the motor by using a preset separation mode for each motor, so as to separate the high-frequency response signal with rotor position information from the response signal of the motor, so that the rotor position information of the motor can be identified according to the high-frequency response signal subsequently, and then the initial position of the rotor of the motor can be determined according to the rotor position information.

[0064] In step 130, phase-locked loop normalization processing is performed on the high-frequency response signal of each motor respectively, to obtain the initial position of the rotor of each motor.

[0065] The phase-locked loop normalization processing refers to normalization processing by using a phase-locked loop (PLL), so as to eliminate the dependence of the PLL on motor parameters by using the normalization processing, thereby simplifying the control structure and making it have the characteristics of strong adaptability. In this step, the high-frequency response signal of each motor can be input into a normalized phase-locked loop position observer respectively, so as to perform normalization processing by using the normalized phase-locked loop position observer, to obtain the rotor position information of the motor, and then the initial position of the rotor of the motor can be determined according to the rotor position information, to realize high-precision identification of the initial position of the rotor. The normalized phase-locked loop position observer can refer to a phase-locked loop with a normalization calculation function, so that the normalized phase-locked loop position observer can perform normalization processing by using the normalization calculation function, to adopt error normalization processing, thereby simplifying the control structure and making it have the characteristics of strong stability.

[0066] Specifically, the stability analysis is performed based on an open-loop transfer function G OL (s) and a closed-loop transfer function G CL (s) of a phase-locked loop structure, such as performing stability analysis according to the expression of the open-loop transfer function of the conventional phase-locked loop structure and the expression of the closed-loop transfer function of the conventional phase-locked loop structure It can be known from the stability analysis that, since the error amplification multiple of the phase-locked loop is related to the amplitude and frequency of the injected signal and the motor inductance value, the system closed-loop characteristics are related to the motor parameters and the injected signal, so the design of the parameters of the phase-locked loop is difficult.

[0067] Wherein, 1 / S in the transfer function represents an integral operation, and its physical meaning is that the input signal is integrated in time; the proportional gain Kp and the 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 response speed of the system to the error, and the integral gain Ki determines the ability of the system to eliminate the steady-state error.

[0068] For example, as shown in Figure 2 The phase-locked loop structure can specifically include a phase detector (PD), a loop filter (LF), and a voltage-controlled oscillator (VCO). The PD is configured to output a phase error signal e(t) representing the phase difference between the input signal and the feedback signal. The input signal can be a current parameter of the motor in the alpha-beta coordinate system at a certain moment, which includes an alpha-axis current parameter i αθ and a beta-axis current parameter i βθ The feedback signal can include rotor position information θ output by the VCO. The rotor position information θ can refer to an electrical angle θe or a mechanical angle θm of the motor rotor in space. The electrical angle θe reflects the periodic change of the motor magnetic field, and can be calculated according to the formula θe=P×θm, that is, the product of the pole pair number P of the motor and the mechanical angle θm. The LF can be a low pass filter (LPF) configured to smooth the phase error signal e(t) and remove high-frequency noise, and output a control quantity for adjusting the VCO. The control quantity output by the LF can be a speed ω related to the signal frequency.

[0069] To solve the problem that the parameter design of the phase-locked loop is difficult, the error normalization processing can be used to simplify the control structure and make it have strong stability. Specifically, according to the closed-loop transfer function expression of the phase-locked loop It can be known that the closed-loop transfer function G CL (s) is calculated from the open-loop transfer function G OL (s), the open-loop transfer function expression The normalization processing reference value E can be determined first, as shown in Figure 3 The open-loop transfer function G is divided by the normalization processing reference value E to obtain the target open-loop transfer function G Then the target open-loop transfer function is substituted into the closed-loop transfer function expression , and calculation is performed to obtain the simplified closed-loop transfer function expression formula , that is Further, the normalized phase-locked loop position observer can be constructed based on the simplified closed-loop transfer function expression formula , and the normalized phase-locked loop position observer is used for normalized processing, as shown in Figure 4 , so that the rotor position information θ of the motor can be calculated.

[0070] The normalized processing reference value E is equivalent to the coefficient in the equivalent structure of the phase-locked loop, and specifically can refer to the current reference value divided by the normalized processing, such as the α-axis current parameter i αθ and the β-axis current parameter i βθ in the α-β coordinate system of the motor at a certain moment. In this case, the current reference value can be

[0071] Based on the simplified closed-loop transfer function expression formula , it can be known that the closed-loop characteristic of the normalized phase-locked loop position observer is only related to the proportional gain Kp and the integral gain Ki of the system, that is, the closed-loop characteristic of the normalized phase-locked loop position observer is only related to the parameters of the system itself and is not affected by other additional parameters. Therefore, by using the normalized phase-locked loop position observer for normalized processing, the control structure can be simplified and has the characteristic of strong stability.

[0072] In step 140, the target rotor position difference is determined according to the initial rotor positions of the motors.

[0073] The target rotor position difference can refer to the position difference required to be adjusted, which is calculated according to the initial rotor positions of the motors. Specifically, after the initial rotor positions of the motors connected by the single inverter are determined, the rotor position difference values between the motors are calculated based on the initial rotor positions of the motors, so that the target rotor position difference required to be adjusted at each moment is determined according to the rotor position difference values between the motors.

[0074] For example, in the case that the single inverter is connected to two motors, the rotor position difference Δθ between the two motors can be calculated based on the initial rotor positions of the two motors, and the target rotor position difference required to be adjusted at each moment can be determined by using the preset dichotomy to calculate the rotor position difference, such as determining half of the rotor position difference as the target rotor position difference, that is, the target rotor position difference is Δθ / 2.

[0075] For example, in the case of three or more motors connected to a single inverter, the standard deviation of the rotor positions between the motors can be calculated based on the initial rotor positions of the motors, and the target rotor position difference at each time can be determined according to the standard deviation of the rotor positions, for example, the standard deviation of the rotor positions can be calculated by using a preset dichotomy method, and half of the standard deviation of the rotor positions can be determined as the target rotor position difference. The standard deviation of the rotor positions between the motors refers to the standard deviation corresponding to the initial rotor positions of the motors.

[0076] At step 150, the rotor positions of the motors are adjusted according to a preset hierarchical adjustment strategy based on the target rotor position difference, so as to control the motors to start synchronously when the rotor positions of the motors are consistent.

[0077] Specifically, after obtaining the target rotor position difference, the rotor positions of the motors can be adjusted according to a preset hierarchical adjustment strategy based on the target rotor position difference, so as to quickly adjust the rotor positions of the motors under the premise of ensuring stable starting of the motors, and gradually reduce the rotor position difference between the motors until the rotor positions of the motors are consistent, and then stop adjusting and control the motors to start synchronously, thereby realizing synchronous starting of the motors.

[0078] In summary, in the motor starting stage, the high-frequency square wave signals are injected into the motors connected to the single inverter, the response signals of the motors are obtained, the high-frequency response signals of the motors are extracted from the response signals of the motors, and then the phase-locked loop normalization processing is performed according to the high-frequency response signals of the motors, respectively, to obtain the initial rotor positions of the motors. Compared with the prior art, the use of the filter is cancelled, and thus the influence of the filter on the current phase and the current response speed can be eliminated, the rotor position recognition accuracy in the motor starting stage is improved, the initial rotor position recognition effect of the motors is better, and additional hardware such as an encoder and a Hall sensor is not needed to detect the initial rotor position, the number of power electronic elements can be effectively reduced, the system cost, volume and size are also reduced, the system structure of the multi-motor control system is simplified, and the hardware complexity is reduced. Then, the target rotor position difference is determined according to the initial rotor positions of the motors, and the rotor positions of the motors are adjusted according to a preset hierarchical adjustment strategy based on the target rotor position difference, so as to quickly adjust the rotor positions of the motors under the premise of ensuring stable starting of the motors, and gradually reduce the rotor position difference between the motors until the rotor positions of the motors are consistent, and then control the motors to start synchronously, thereby realizing smooth control of the synchronous starting of the motors, and improving the operation reliability in the motor starting stage.

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

[0080] Sub-step 1101, respectively determining the rotation speed of each motor connected by the single inverter;

[0081] Sub-step 1102, in the case that the rotation speed of each motor is lower than a preset rotation speed, injecting the high-frequency square wave voltage signal in the two-phase rotating coordinate system by the single inverter based on the fundamental frequency of the motor, wherein the frequency of the high-frequency square wave signal is greater than the fundamental frequency;

[0082] Sub-step 1103, respectively extracting the response signal of each motor in the two-phase stationary coordinate system.

[0083] The preset rotation speed refers to a preset rotation speed threshold, which can be used to determine whether the motor has been normally started. For example, when the rotation speed of a certain motor is greater than the rotation speed threshold, it is considered that the motor has been normally started and enters the running state. When the rotation speed of a certain motor is not greater than the rotation speed threshold, it is considered that the motor is in the starting stage. The preset rotation speed can be set to zero, so that when the rotation speed of the motor is greater than the rotation speed threshold, it is considered that the motor enters the running state. The fundamental frequency of the motor can refer to the frequency of the fundamental signal of the motor. For example, the fundamental frequency of the motor can be determined by the fundamental frequency injected by the motor. For example, the fundamental frequency can be determined as the fundamental frequency of the motor, so that the fundamental frequency of the motor is much lower than the frequency of the high-frequency square wave signal, and the fundamental frequency can be used to determine the running frequency of the motor, such as the running frequency of the motor.

[0084] Specifically, in order to obtain the rotor position information of the motor under sensorless control, to optimize the control performance of the multi-motor synchronous starting, the embodiments of the present application can detect the rotation speed of each motor connected by the single inverter after the motor is powered on, and can determine whether the detected rotation speed of each motor exceeds the preset rotation speed, so that when the rotation speed of each motor is lower than the preset rotation speed, it is considered that the motor is in the starting stage, and then the frequency of the high-frequency square wave signal can be determined according to the fundamental frequency of the motor under the condition that the rotation speed of each motor is lower than the preset rotation speed, so that the high-frequency pulse width modulation signal can be generated by the digital circuit as the high-frequency square wave signal, and the high-frequency pulse width modulation signal can be injected into the motor winding of each motor connected by the single inverter in the two-phase rotating coordinate system through the single inverter, so that each motor generates a corresponding response current under the excitation of the high-frequency square wave signal, and the response current generated by the motor can be collected in a two-phase stationary coordinate system such as an α-β coordinate system, so that the response current signal of each motor can be obtained.

[0085] The two-phase rotating coordinate system refers to a rectangular coordinate system that rotates synchronously with the rotor flux linkage, for example, the two-phase rotating coordinate system can be a dq coordinate system composed of a direct axis (d-axis) and a quadrature axis (q-axis); the high-frequency square wave signal can be a high-frequency current signal or a high-frequency voltage signal, which is not limited in the embodiments of the present application.

[0086] In some optional embodiments of the present application, the high-frequency square wave signal can be directly generated by a simple digital circuit or a switching device, for example, a high-frequency pulse width modulation (PWM) signal can be generated by a digital circuit as the injected high-frequency square wave signal, which is simple and has low hardware cost, without the need for complex filtering or modulation circuits; in addition, the rising / falling edge and duty cycle of the high-frequency square wave signal can be easily extracted by a simple detection circuit, for example, the rising / falling edge information of the high-frequency square wave signal can be extracted by a comparator or zero point detection, so as to reduce the dependence on the signal processing algorithm, making the signal processing algorithm simpler, for example, the square wave feature information can be directly extracted by detecting the edge (such as the rising edge / falling edge) or zero point of the square wave, so as to determine the motor rotor position according to the extracted square wave feature information; and the rapid change of the square wave signal is suitable for scenarios that require rapid adjustment, for example, the steep edge of the square wave can provide a faster dynamic response than the sine wave, that is, the rapid change of the square wave is suitable for scenarios that require rapid adjustment (such as motor transient process).

[0087] Optionally, the embodiments of the present application can separate the signals based on the response signals of each motor respectively to obtain the high-frequency response signals of each motor, which can specifically include the following sub-steps:

[0088] Sub-step 1201, determining the high-frequency response current feature corresponding to the high-frequency square wave signal;

[0089] In sub-step 1202, according to the high-frequency response current characteristic, a modulation response signal of the high-frequency square wave signal in the two-phase static coordinates of each motor is extracted from the response signal of each motor, respectively.

[0090] In 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 can refer to a characteristic of the high-frequency response current, and specifically can represent the characteristic that the high-frequency square wave response current has equal amplitude but opposite direction. Specifically, since the frequency of the injected high-frequency square wave signal is much greater than the fundamental frequency, it can be approximately considered that the fundamental at adjacent sampling time is constant, and the high-frequency response current characteristic corresponding to the high-frequency square wave signal can be generated based on the characteristic that the high-frequency square wave response current has equal amplitude but opposite direction, so as to represent the characteristic that the high-frequency square wave response current has equal amplitude but opposite direction by the high-frequency response current characteristic. Then, according to the high-frequency response current characteristic, the modulation response signal of the high-frequency square wave signal in the two-phase static coordinates of the motor can be extracted from the response signal of the motor based on the characteristic that the high-frequency square wave response current has equal amplitude but opposite direction, so as to determine the extracted modulation response signal as the high-frequency response signal corresponding to the high-frequency square wave signal.

[0092] Optionally, the embodiment of the present application can determine the current difference value at adjacent sampling time as the high-frequency response current characteristic based on the characteristic that the high-frequency square wave response current has equal amplitude but opposite direction, so as to separate the high-frequency response current and the fundamental response current through the current difference value at adjacent sampling time. Then, the high-frequency response current signal can be generated based on the high-frequency response current, and the fundamental response current signal can be generated based on the fundamental response current. For example, based on the characteristic that the fundamental current at adjacent sampling time is approximately constant and the high-frequency square wave response current has equal amplitude but opposite direction, the high-frequency response current calculation formula and the fundamental response current calculation formula can be determined according to the response current calculation formula.

[0093] The response current calculation formula is:

[0094] The high-frequency response current calculation formula is:

[0095] The fundamental response current calculation formula is:

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

[0097] It can be seen that, according to the high-frequency response current calculation formula and the fundamental response current calculation formula, based on the characteristics that the fundamental current signal amplitude and the harmonic current signal amplitude are different, and the high-frequency square wave response current amplitudes are equal but opposite in direction, the fundamental response signal and the high-frequency response signal of the motor can be separated from the current response signal of the motor, so that the rotor initial position of the motor can be identified according to the high-frequency response signal subsequently.

[0098] Of course, in addition to the current signal separation method described above, other separation methods can also be used to separate the high-frequency response 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 take the separated high-frequency component signal as the high-frequency response signal of the motor for rotor initial position identification of the motor, and the present application does not make specific limitation.

[0099] The current separation method is also applicable to deriving the current response 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 represented as:

[0100]

[0101] wherein iαh and iβh can be used to represent the high-frequency response current generated in the α-β coordinate system, iαh is used to represent the high-frequency response current of the α axis, iβh is used to represent the high-frequency response current of the β axis, A(θ) is a coordinate transformation matrix, Ld is the d-axis inductance of the motor, Lq is the q-axis inductance of the motor, U dh is the high-frequency stator voltage of the d axis in the dq coordinate system, U qh is the high-frequency stator voltage of the q axis in the dq coordinate system. Through the conversion formula, the motor stator voltage equation can be converted from the three-phase abc coordinate system to the dq coordinate system, such as the coordinate transformation matrix A(θ) calculation formula and the expression of the high-frequency square wave signal The high-frequency current calculation formula The simplified high-frequency response signal calculation formula

[0102] Under the excitation of the high-frequency square wave signal, when the motor is in a low-speed or stationary state, and the frequency of the injected high-frequency square wave signal is much greater than the fundamental frequency, the influence of the back electromotive force and the resistance voltage drop can be ignored, and the simplified high-frequency response signal calculation formula The response signal of the motor can be simplified and converted to the α and β axes to obtain the high-frequency response current iah in the α axis and the high-frequency response current iβh in the β axis, and the high-frequency response current iah in the α axis and the high-frequency response current iβh in the β axis can be used as the current parameters to be identified and extracted at present and input to the normalized phase-locked loop position observer for normalization processing to obtain the initial position of the rotor of the motor. Wherein, -1 represents the inverse transformation of the matrix; U h represents the amplitude of the injected high-frequency voltage, and (-1)k represents the positive and negative of the square wave signal. The expression of the high-frequency square wave signal for indicating the injected high-frequency square wave signal.

[0103] In some optional embodiments of the present application, the normalized phase-locked loop position observer comprises a rotor position observer. The function of the rotor position observer can be divided into two parts: one is to operate the input two-phase α and β axis high-frequency response currents to decouple to obtain the rotor error information; the other is to phase-lock the obtained rotor position error information to obtain the estimated rotor position information θ. Optionally, the above step 130 can specifically comprise the following sub-steps, including:

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

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

[0106] Sub-step 1303, performing normalization processing based on the rotor position error information to obtain the initial position of each motor rotor.

[0107] Specifically, after the rotor position information of the motor is identified by using the high-frequency square wave signal, the error normalization processing can be used to construct the rotor position observer to identify and extract the accurate initial position of the rotor by using the rotor position observer, thereby improving the operation reliability of the control method in the multi-motor starting stage.

[0108] As an example of the present 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, in the starting stage, the output signal can be adjusted by combining the proportional term (P) and the integral term (I) according to the difference between the reference angular velocity and the measured feedback angular velocity through the speed loop proportional-integral (PI) control, so as to reduce the system error and improve the stability. For example, the adjustment output signal of the first motor can be output through the speed loop PI control according to the difference between the reference angular velocity ωrf1 of the first motor and the measured feedback angular velocity ωr1, so as to reduce the system error and improve the stability through the adjustment output signal of the first motor. Similarly, the adjustment output signal of the second motor can be output through the speed loop PI control according to the difference between the reference angular velocity ωrf2 of the second motor and the measured feedback angular velocity ωr2, so as to reduce the system error and improve the stability through the adjustment output signal of the second motor.

[0109] In the speed loop control, the PI control can be used to adjust the output torque or voltage of the motor, so that the actual speed can follow the target speed as soon as possible, and the steady-state error can be eliminated, so as to obtain the dq-axis reference current value. The dq-axis reference current value can be subtracted from the actual feedback value, and then the current loop PI control is performed, and then a high-frequency square wave voltage signal is used, such as Figure 6 As shown, that is, 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 signal of each motor can be extracted in the α-β coordinate system, and then the response current signal is separated, that is, the response current signal is separated, so that the high-frequency response current signal and the low-frequency response current signal can be obtained. The high-frequency response current signal and the low-frequency response current signal can specifically 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 with the single inverter as an example, the d-axis reference current value id1 of the first motor can be subtracted from the first actual feedback value of the first motor, such as Figure 5As shown, the first motor first fundamental signal in dq coordinate system is generated through current loop PI control, the first motor first drive voltage signal Ud1 is generated by superimposing the first fundamental signal and the injected first high frequency square wave signal Uinj1, and the first motor corresponding α-axis voltage response signal Uα1 is obtained through inverse park conversion in α-β coordinate system; and the first motor q-axis reference current value iq1 is subtracted from the first motor first actual feedback value, the first motor second fundamental signal in dq coordinate system is generated through current loop PI control, the first motor second drive voltage signal Uq1 is generated by superimposing the second fundamental signal and the injected high frequency square wave signal, the first motor corresponding β-axis voltage response signal Uβ1 is obtained through inverse park conversion in α-β coordinate system, the first motor α-axis voltage response signal Uα1 and the β-axis voltage response signal Uβ1 are determined as the response current signal corresponding to the first motor, and then the response current signal is separated, i.e., the response current signal is separated, so that the first motor α-axis high frequency response current signal iαh1 and the β-axis high frequency response current signal iβh1 in α-β coordinate system can be obtained, and further the first motor α-axis high frequency response current signal iαh1 and the β-axis high frequency response current signal iβh1 in α-β coordinate system can be input into the phase-locked loop for normalization processing, i.e., 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, the rotor position observer is used for calculation, the rotor position error information of the first motor is obtained, and the rotor initial position θ1 of the first motor is obtained based on the normalization processing of the rotor position error information.

[0111] For example, the second motor d-axis reference current value id2 can be subtracted from the second motor first actual feedback value, as shown in the following formula (5): Figure 5As shown, the first fundamental wave signal of the second motor in the dq coordinate system is generated through the current loop PI control to superimpose the first fundamental wave signal and the injected second high-frequency square wave signal Uinj2 to generate the first driving voltage signal Ud2 of the second motor, which is converted to the a-β coordinate system through the inverse park transformation to obtain the corresponding a-axis voltage response signal Ua2 of the second motor; and the q-axis reference current value iq2 of the second motor is subtracted from the first actual feedback value of the second motor, the second fundamental wave signal of the second motor in the dq coordinate system is generated through the current loop PI control, and the second fundamental wave signal and the injected high-frequency square wave signal are superimposed to generate the second driving voltage signal Uq2 of the second motor, which is converted to the a-β coordinate system through the inverse park transformation to obtain the corresponding β-axis voltage response signal Uβ2 of the second motor, and the a-axis voltage response signal Ua2 and the β-axis voltage response signal Uβ2 of the second motor are determined as the corresponding response signal of the second motor, so that the a-axis high-frequency response current signal iαh2 and the β-axis high-frequency response current signal iβh2 of the second motor in the a-β coordinate system can be obtained, and then the a-axis high-frequency response current signal iαh2 and the β-axis high-frequency response current signal iβh2 of the second motor in the a-β coordinate system can be input into the phase-locked loop for normalization processing, i.e., the a-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 observer, and the rotor initial position θ1 of the second motor is obtained based on the normalization processing of the rotor position error information.

[0112] Specifically, due to the magnetic resistance effect of the motor, i.e., the stator winding of the motor has different magnetic resistances at different rotor positions, such as the saliency effect of the permanent magnet synchronous motor (PMSM), the high-frequency square wave voltage can generate a modulated response current in the a-β coordinate system, and the amplitude and phase of the response current are related to the rotor position. Therefore, the example of the present application can infer the rotor position of the motor by using the current response caused by the change of the magnetic resistance, such as amplitude modulation or phase shift based on the current signal, extracting the rotor angle through the filter, and combining the algorithm (such as the phase detection in the phase-locked loop). The core function of the Park transformation is to decouple the relationship between the voltage and the current of the motor, so that the control problem of the three-phase alternating current motor can be simplified to the control of two independent variables, and the rotor angle is extracted to determine the rotor position information of the motor based on the extracted rotor angle.

[0113] Wherein, Ud is the driving voltage signal of d-axis, Uq is the driving voltage signal of q-axis, after the inverse park transformation, it can be converted into α-β coordinate system, and then the reference voltage vector adjustment can be carried out based on the voltage response signal in the α-β coordinate system, to obtain the reference voltage vector (Va, Vb, Vc); after the space vector pulse width modulation (SVPWM) modulation, finally the driving motor operation can be controlled through power devices such as insulate-gate bipolar transistor (IGBT); the next part is the feedback part, the three-phase currents ia, ib, ic are converted into α-axis current response signal iα and β-axis current response signal iβ through Clark transformation, from which the high-frequency components iαh, iβh are extracted, and the feedback angular velocity ωr is obtained through phase-locked loop processing, and iα, iβ are converted into low-frequency response current signals id, iq through park transformation, which are also fed back to the system dq-axis voltage and current as feedback quantities, for example, the three-phase currents ia, ib, ic of the first motor are converted into α-axis current response signal iα1 and β-axis current response signal iβ1 through Clark transformation, from which the high-frequency components iαh1, iβh1 of the first motor are extracted, and the feedback angular velocity ωr1 of the first motor is obtained through phase-locked loop processing, and the α-axis current response signal iα1 and the β-axis current response signal iβ1 are converted into low-frequency response current signals id1, iq1 of the first motor through park transformation; for another example, the three-phase currents ia, ib, ic of the second motor are converted into α-axis current response signal iα2 and β-axis current response signal iβ2 through Clark transformation, from which the high-frequency components iαh2, iβh2 of the second motor are extracted, and the feedback angular velocity ωr2 of the second motor is obtained through phase-locked loop processing, and the α-axis current response signal iα2 and the β-axis current response signal iβ2 are converted into low-frequency response current signals id2, iq2 of the second motor through park transformation.

[0114] The core role of Clark transformation is to convert the current / voltage signal in three-phase symmetrical or asymmetrical system into two-phase rectangular coordinate system (α-β), so as to simplify the controller design and improve the calculation efficiency. Among them, Clark transformation is usually the first step of Park transformation, which converts three-phase signal into α-β coordinate system, and then converts into d-q axis coordinate system through Park transformation.

[0115] It can be seen that in the case that the rotation speeds of the motors are all lower than the preset rotation speed, the 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, the signal separation is performed based on the response signal, the high-frequency response current and the low-frequency current signal are separated, the rotor position identification is performed by using the high-frequency response signal to improve the accuracy of the rotor position identification, and the low-frequency current signal can be used as the fundamental response signal to access the system current loop for normal closed-loop control to realize the system current loop feedback.

[0116] As an example of the present application, in the multi-motor synchronous starting control system, as shown in Figure 6 the high-frequency square wave signal is injected to identify the initial position of the rotor by using the high-frequency response current, and the fundamental response current can be accessed to the system current loop for normal closed-loop control. After the response current signal of the motor is extracted, the high-frequency response signal and the low-frequency current signal are separated from the response signal current of the motor according to the preset signal separation mode, that is, the response current signal is separated to obtain the high-frequency response signal and the low-frequency current signal, the rotor position identification is performed by using the high-frequency response signal to improve the accuracy of the rotor position identification, that is, the high-frequency response current signal is input into the rotor position observer to identify the rotor position information of the two motors by using the rotor position observer, that is, the rotor position information of the first motor and the rotor position information of the second motor are identified, and the low-frequency current signal can be used as the fundamental response signal to access the system current loop for normal closed-loop control to realize the system current loop feedback.

[0117] In an optional embodiment of the present application, the determination of the target rotor position difference according to the initial rotor positions of the motors includes the following sub-steps:

[0118] Sub-step 1401, determining the number of motors;

[0119] Sub-step 1402, in the case that the number of motors is greater than a preset motor number threshold, determining the standard deviation of the initial rotor positions according to the initial rotor positions of the motors;

[0120] Sub-step 1403, determining the target rotor position difference by using the standard deviation of the initial rotor positions.

[0121] The number of motors is the total number of motors connected to a single inverter, for example, in the case that four motors are connected to a single inverter, the number of motors is four; the preset motor number threshold can be set according to the demand of multi-motor stable starting control, for example, it can be set to three or four, etc., and the present application does not limit this.

[0122] For example, when the preset motor quantity threshold is 4, if 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 quantity threshold. At this time, the standard deviation can be calculated according to the rotor initial positions of the motors connected to the single inverter, so as to determine the target rotor position difference or the calculated standard deviation as the target rotor position difference.

[0123] Optionally, the application embodiment for determining the target rotor position difference according to the rotor initial positions of the motors can further include: when the number of motors is less than the preset motor quantity threshold, performing average value calculation according to the rotor initial positions of the motors connected to the single inverter to obtain rotor initial position average values corresponding to the motors; determining a target position difference between the rotor initial position of each motor and the rotor initial position average value based on the rotor initial position average value; and determining the target position difference as the target rotor position difference for each motor.

[0124] For example, when the preset motor quantity threshold is 4, if 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 quantity threshold. At this time, the average value can be calculated according to the rotor initial positions of the motors connected to the single inverter to determine the rotor initial position average value. Then, the position difference between the rotor initial position average value and the rotor initial position of each motor can be determined as the target rotor position difference corresponding to the motor, so that the target rotor position difference can be used subsequently.

[0125] In this case, when the number of motors is equal to the preset motor quantity threshold, the average value can be calculated according to the rotor initial positions of the motors connected to the single inverter to obtain rotor initial position average values corresponding to the motors. Then, the target position difference between the rotor initial position of each motor and the rotor initial position average value can be calculated based on the rotor initial position average value, so as to determine the target position difference as the target rotor position difference for each motor. Alternatively, the rotor initial position standard deviation can be determined according to the rotor initial positions of the motors, and the target rotor position difference can be determined by using the rotor initial position standard deviation. The application embodiments are not limited in this regard.

[0126] Specifically, after the target rotor position difference is determined according to the rotor initial positions of the motors, the rotor position of each motor can be adjusted according to a preset hierarchical adjustment strategy based on the target rotor position difference of each motor, so as to control the motors to start synchronously when the rotor positions of the motors are consistent, thereby achieving synchronous starting of multiple motors.

[0127] In some optional embodiments of the present application, the target rotor position difference Δθ can be compared with a preset rotor position error range, so that when the target rotor position difference Δθ 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, the position adjustment parameter Δθ / 2 at each moment can be calculated by using the bisection method according to the preset hierarchical adjustment strategy, and Δθ / 2 is taken as a feedback value for rotor position adjustment. For example, when the initial rotor position θ1 of the first motor is less than the initial rotor position θ2 of the second motor, i.e., when θ1<θ2, the sum of the initial rotor position θ1 of the first motor and the position adjustment parameter Δθ / 2 is taken as the initial rotor information of the first motor for synchronous starting, and the difference between the initial rotor position θ2 of the second motor and the position adjustment parameter Δθ / 2 is taken as the initial rotor information of the second motor for synchronous starting, so that the motor synchronous starting rotor position control can be performed based on the initial rotor information of the two motors, to complete the synchronous starting of the two motors when the rotor positions of the two motors are the same, and to improve the stability and reliability of the synchronous starting of the two motors. Alternatively,

[0128] When the target rotor position difference exceeds the preset rotor position error range, i.e., 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 preset hierarchical adjustment strategy, until the rotor position difference between the motors becomes zero, i.e., when the initial rotor positions of the motors are consistent, the motors are controlled to start at the same time, to complete the synchronous starting of the two motors when the rotor positions of the two motors are the same, and to improve the stability and reliability of the synchronous starting of the two motors.

[0129] Alternatively, the rotor position of each motor can be adjusted according to the preset hierarchical adjustment strategy based on the target rotor position difference, to control the synchronous starting of the motors when the rotor positions of the motors are consistent. Specifically, when the target rotor position difference exceeds the preset rotor position error range, the preset target adjustment parameter corresponding to the hierarchical adjustment strategy is extracted, and the average value of the initial rotor positions of the motors is determined by average value calculation based on the initial rotor positions of the motors. The rotor position of each motor is adjusted according to the hierarchical adjustment strategy based on the initial rotor position of each motor, in combination with the target adjustment parameter and the average value of the initial rotor positions, to control the synchronous starting of each motor when the rotor positions of the motors are consistent. The preset rotor position error range can be determined by a preset rotor error threshold value. For example, when the rotor error threshold value is 30°, the rotor error threshold value can be taken as the maximum sub-error threshold value of the rotor position error range, and the inverse of the rotor error threshold value can be taken as the minimum sub-error threshold value of the rotor position error range, so that the rotor position error range is (-30°, 30°).

[0130] For example, in the case of one-to-two, i.e. in the case of controlling two motors synchronously starting by one inverter, as shown in FIG. 1, 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 difference Δθ between the two motors can be calculated according to the calculation formula Δθ = θ2 - θ1 by using the rotor position information of the two motors, and it can be judged whether the rotor position difference Δθ exceeds the preset rotor position error range. For example, in the case of the preset rotor position error range being (-30°, 30°), if the rotor position difference Δθ is not large, such as in the case of the rotor position difference Δθ being less than the preset 30° and greater than 0°, the bisection method can be used to calculate Δθ / 2 at each moment, and the Δθ / 2 is used as the feedback value for the rotor position adjustment until Δθ = 0, so as to control the motors to start synchronously. Figure 5 Figure 6 For example, in the case of one-to-two, i.e. in the case of controlling two motors synchronously starting by one inverter, as shown in FIG. 1, 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 difference Δθ between the two motors can be calculated according to the calculation formula Δθ = θ2 - θ1 by using the rotor position information of the two motors, and it can be judged whether the rotor position difference Δθ exceeds the preset rotor position error range. For example, in the case of the preset rotor position error range being (-30°, 30°), if the rotor position difference Δθ is not large, such as in the case of the rotor position difference Δθ being less than the preset 30° and greater than 0°, the bisection method can be used to calculate Δθ / 2 at each moment, and the Δθ / 2 is used as the feedback value for the rotor position adjustment until Δθ = 0, so as to control the motors to start synchronously.

[0131] For example, in the case of one-to-two, i.e. in the case of controlling two motors synchronously starting by one inverter, as shown in FIG. 1, 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 difference Δθ between the two motors can be calculated according to the calculation formula Δθ = θ2 - θ1 by using the rotor position information of the two motors, and it can be judged whether the rotor position difference Δθ exceeds the preset rotor position error range. For example, in the case of the preset rotor position error range being (-30°, 30°), if the rotor position difference Δθ is not large, such as in the case of the rotor position difference Δθ being less than the preset 30° and greater than 0°, the bisection method can be used to calculate Δθ / 2 at each moment, and the Δθ / 2 is used as the feedback value for the rotor position adjustment until Δθ = 0, so as to control the motors to start synchronously.

[0132] For example, in the case of one-to-two, i.e. in the case of controlling two motors synchronously starting by one inverter, as shown in FIG. 1, 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 difference Δθ between the two motors can be calculated according to the calculation formula Δθ = θ2 - θ1 by using the rotor position information of the two motors, and it can be judged whether the rotor position difference Δθ exceeds the preset rotor position error range. For example, in the case of the preset rotor position error range being (-30°, 30°), if the rotor position difference Δθ is not large, such as in the case of the rotor position difference Δθ being less than the preset 30° and greater than 0°, the bisection method can be used to calculate Δθ / 2 at each moment, and the Δθ / 2 is used as the feedback value for the rotor position adjustment until Δθ = 0, so as to control the motors to start synchronously.

[0133] ​Compared with the regulation and control mode in the prior art that uses single motor rotor position information as a reference to control another motor rotor position, the embodiment of the application can not only ensure the stability of the double motor starting control operation, but also improve the double motor starting control precision and response speed, can smoothly achieve the purpose of rotor position information synchronization in the motor starting stage, and can effectively solve the problems of poor motor starting control stability and motor starting failure in the motor starting process in the prior art. Moreover, it can avoid the problem of the motor entering the running state after starting due to too long motor starting control time, and solve the problem of single control method due to single motor standby in the prior art.

[0134] As shown in Figure 7 The embodiment of the application also provides a single-inverter multi-motor starting control system, which comprises an inverter 610 and at least two motors 620 electrically connected with the inverter 610.

[0135] The inverter 6100 is configured to implement the single-inverter multi-motor starting control method provided by any one of the preceding embodiments of the application, so that the single-inverter multi-motor starting control system can inject a high-frequency square wave signal into each motor connected with the single inverter and obtain a response signal during the motor starting stage, then perform signal separation based on the response signal of each motor respectively to obtain the high-frequency response signal of each motor, and obtain the initial position of the rotor of each motor through phase-locked loop normalization processing. Then, the target rotor position difference can be determined according to the initial position of the rotor, and the rotor position can be adjusted based on the target rotor position difference according to the hierarchical adjustment strategy until the rotors of the motors are synchronized, so as to realize precise synchronous starting of the multi-motor, simplify the system structure and reduce the cost, and improve the operation reliability in the multi-motor starting stage.

[0136] In a specific implementation, the single-inverter multi-motor starting control system provided by the embodiment of the application can be integrated in an electrical appliance as a motor drive control system of the electrical appliance, so that the electrical appliance can execute the single-inverter multi-motor starting control method provided by the embodiment of the application through a control device to use the high-frequency square wave signal injection combined with the filterless signal separation method to avoid the phase lag caused by traditional filtering, and cooperate with the phase-locked loop normalization processing to effectively improve the rotor initial position identification accuracy, and can design different target rotor position difference calculation methods for different motor quantities to make the synchronous control more suitable for actual application scenarios. Through the hierarchical adjustment strategy, the advantages of coarse adjustment and fine adjustment can be considered to shorten the synchronization time while ensuring the adjustment accuracy and improve the starting efficiency.

[0137] As shown in Figure 8As shown, the application further provides an electrical appliance device, comprising a processor 811, a communication interface 812, a memory 813 and a communication bus 814, wherein the processor 811, the communication interface 812 and the memory 813 complete mutual communication through the communication bus 814, the memory 813 is used for storing a computer program, and the processor 811 is used for executing the computer program stored in the memory 813 to realize the steps of the single-inverter dragging multi-motor starting control method provided by any one of the preceding embodiments of the application.

[0138] In a specific implementation, the electrical appliance device in the embodiments of the application can include but is not limited to a refrigeration device such as an air conditioner and a refrigerator, and can also include a washing machine and other types of electrical appliance devices, and the embodiments of the application do not specifically limit this.

[0139] The circuit, system and device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, can be located in one place or can be distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the embodiments.

[0140] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software plus a general hardware platform, and of course can also be realized by hardware.

[0141] Based on such understanding, the above technical solutions can be embodied in the form of a software product in essence or in the form of a contribution to related technologies, and the computer software product can be stored in a computer readable storage medium such as a ROM / RAM, a magnetic disk or an optical disk, and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device) to execute the method described in each embodiment or some parts of the embodiment.

[0142] It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order

[0143] The above description is merely that of the specific embodiments of the application and as such is not to be taken in a limiting sense. Various modifications and alterations of the embodiments described herein will become apparent to those skilled in the art from the foregoing description, which does not limit the generality presented. It is the intention that all such modifications and alterations be considered equaliy by the spirit and scope of this application. It is therefore intended to cover in the appended claims all such changes and alterations that come within the scope of this application.

Claims

1. A method for starting control of a single-inverter-fed multi-motor, characterized by, The starting control method comprises: in the motor starting stage, injecting a high-frequency square wave signal into each motor connected to a single inverter to obtain a response signal of each motor; performing signal separation based on the response signal of each motor to obtain a high-frequency response signal of each motor; performing phase-locked loop normalization processing based on the high-frequency response signal of each motor to obtain a rotor initial position of each motor; determining a target rotor position difference based on the rotor initial position of each motor; based on the target rotor position difference, performing rotor position adjustment of each motor according to a preset hierarchical adjustment strategy to control the synchronous starting of each motor when the rotor positions of each motor are consistent.

2. The start-up control method according to claim 1, characterized by The response signal of the motor is a response current signal, and the high-frequency square wave signal is injected into each motor connected to a single inverter in the motor starting stage to obtain a response signal of each motor, which comprises: determining the rotational speed of each motor connected to the single inverter; in the case that the rotational speed of each motor is lower than a preset rotational speed, injecting the high-frequency square wave voltage signal into the single inverter in a two-phase rotating coordinate system based on the fundamental frequency of the motor, wherein the frequency of the high-frequency square wave signal is greater than the fundamental frequency; extracting the response current signal of each motor in a two-phase stationary coordinate system.

3. The start-up control method according to claim 1, characterized by Performing signal separation based on the response signal of each motor to obtain a high-frequency response signal of each motor, comprising: determining the high-frequency response current characteristics corresponding to the high-frequency square wave signal; according to the high-frequency response current characteristics, extracting the modulation response signal of the high-frequency square wave signal in the two-phase stationary coordinate of each motor 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 by The phase-locked loop normalization processing based on the high-frequency response signal of each motor to obtain a rotor initial position of each motor, comprising: inputting the high-frequency response signal into a rotor position observer; calculating the high-frequency response signal by using the rotor position observer to obtain rotor position error information; performing normalization processing based on the rotor position error information to obtain the rotor initial position of each motor.

5. The start-up control method according to claim 1, characterized by The target rotor position difference is determined based on the rotor initial position of each motor, comprising: determining the number of motors; in the case that the number of motors is greater than a preset motor number threshold, determining the rotor initial position standard deviation based on the rotor initial position of each motor; determining the target rotor position difference by using the rotor initial position standard deviation.

6. The start-up control method according to claim 1, characterized by The target rotor position difference is determined based on the rotor initial position of each motor, comprising: determining the number of motors; in the case that the number of motors is less than a preset motor number threshold, performing average value calculation based on the rotor initial position of each motor connected to a single inverter to obtain a rotor initial position average value corresponding to each motor; based on the rotor initial position average value, determining the target position difference between the rotor initial position of each motor and the rotor initial position average value; for each motor, the target position difference is determined as the target rotor position difference.

7. The start-up control method according to any one of claims 1 to 6, characterized by, The rotor position adjustment of each motor is performed according to a preset hierarchical 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, including: In the case that the target rotor position difference exceeds a preset rotor position error range, preset target adjustment parameters corresponding to the hierarchical adjustment strategy are extracted, and an average value of the rotor initial positions of each motor is calculated according to the rotor initial positions of each motor, so as to determine the average value of the rotor initial positions; The rotor position adjustment of each motor is performed according to the hierarchical adjustment strategy based on the target adjustment parameters and the average value of the rotor initial positions, so as to control the synchronous start of each motor when the rotor positions of each motor are consistent.

8. A starting control system for a single inverter supporting multiple motors, characterized in that, It comprises: an inverter and at least two motors electrically connected with the inverter; The inverter is configured to implement the start control method according to any one of claims 1 to 7.

9. An electrical appliance, characterized in that It comprises: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete mutual communication through the communication bus; The memory is used for storing a computer program; The processor is used for executing the computer program stored on the memory, so as to realize the steps of the start control method according to any one of claims 1 to 7.

10. A computer storage medium storing computer-executable instructions, which, when executed by a processor, cause the processor to perform acts comprising: The computer executable instructions are used for executing the steps of the start control method according to any one of claims 1 to 7.

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