Control method, control device, system and medium of three-phase AC transmission system

Abstract

The present invention proposes a control method, a control device, a system and a medium for a three-phase AC transmission system, the method comprising: when the DC side voltage of a single-phase bridge rectifier filter circuit has a double frequency pulsation, obtaining the three-phase stator current on the stator side of a permanent magnet synchronous motor; determining the beat frequency current angular frequency corresponding to the low-frequency current component in the three-phase stator current; constructing a beat frequency coordinate system with the beat frequency current angular frequency as the rotation angular velocity, subjecting the three-phase stator current to a negative sequence Park transformation to obtain a first transformation current component and a second transformation current component, and then obtaining a first voltage compensation amount and a second voltage compensation amount; subjecting the first voltage compensation amount and the second voltage compensation amount to a negative sequence inverse Park transformation to obtain a target voltage compensation amount; adjusting an AC modulation signal according to the target voltage compensation amount to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. The embodiment of the present application can control the beat frequency AC current without adding additional components.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission systems, and in particular to a control method, a control device, a system and a medium for a three-phase AC transmission system. Background Art

[0002] In a three-phase AC drive system powered by a single-phase AC power supply, the single-phase rectifier in the three-phase AC drive system will have a double frequency pulsation component in both the input and output power during operation. This characteristic makes the DC side voltage of the three-phase AC drive system prone to 100Hz pulsation. This pulsating voltage will directly cause obvious beat frequency phenomenon in the motor stator voltage and current, especially when the motor runs at a frequency close to the double frequency of the power grid, its impact becomes particularly obvious and prominent. At this time, the motor power loss increases, the temperature rises sharply, and serious mechanical jitter and unbearable noise pollution are generated. In order to solve the beat frequency problem caused by the pulsation of the DC bus voltage, the pulsating voltage on the DC side can be directly suppressed through a specific hardware circuit design. These methods require the addition of additional components, which not only increases the cost, but also makes the control more complicated. Therefore, how to achieve zero-difference control of beat frequency AC current without adding additional components is an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a control method, a control device, a system and a medium for a three-phase AC transmission system, which can realize zero-difference control of beat frequency AC current without adding additional components.

[0004] In a first aspect, an embodiment of the present invention provides a control method for a three-phase AC transmission system, wherein the three-phase AC transmission system comprises a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, wherein the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor, and the control method comprises:

[0005] When the DC side voltage of the single-phase bridge rectifier filter circuit has double frequency pulsation, obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor;

[0006] Determining a beat current angular frequency corresponding to a low-frequency current component in the three-phase stator current;

[0007] A beat frequency coordinate system is constructed with the beat frequency current angular frequency as the rotation angular velocity, and the three-phase stator current is subjected to a negative sequence Park transformation to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system;

[0008] Obtaining a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component;

[0009] The first voltage compensation amount and the second voltage compensation amount are subjected to negative sequence inverse Park transformation to obtain a target voltage compensation amount, wherein the target voltage compensation amount includes a first target voltage compensation amount, a second target voltage compensation amount and a third target voltage compensation amount;

[0010] An AC modulation signal for controlling the three-phase inverter circuit is adjusted according to the target voltage compensation amount, so as to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor.

[0011] The control method of the three-phase AC transmission system provided by the embodiment of the present invention has at least the following beneficial effects: on the basis that the three-phase AC transmission system includes a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, and the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor, by obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor when there is a double frequency pulsation in the DC side voltage of the single-phase bridge rectifier filter circuit, determining the beat frequency current angular frequency corresponding to the low-frequency current component in the three-phase stator current, constructing a beat frequency coordinate system with the beat frequency current angular frequency as the rotation angular velocity, subjecting the three-phase stator current to a negative sequence Park transformation to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system, and obtaining the corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component. The first voltage compensation amount and the second voltage compensation amount under the system are subjected to negative-sequence inverse Park transformation to obtain a target voltage compensation amount. The AC modulation signal used to control the three-phase inverter circuit can be adjusted according to the target voltage compensation amount to directly and effectively control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. That is to say, the embodiment of the present application does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add additional power decoupling circuits or increase electrolytic capacitors. From the perspective of control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed on the motor side by the double frequency pulsating voltage, and achieving zero-difference control of the beat frequency AC current without adding additional components.

[0012] In the above control method, adjusting the AC modulation signal used to control the three-phase inverter circuit according to the target voltage compensation amount to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor includes:

[0013] Acquiring an AC modulation signal for controlling the three-phase inverter circuit;

[0014] Superimposing the AC modulation signal and the target voltage compensation amount to obtain a target modulation signal;

[0015] The three-phase inverter circuit is controlled according to the target modulation signal to provide current for the permanent magnet synchronous motor.

[0016] In the above control method, the three-phase stator current includes a first phase current, a second phase current and a third phase current, the first phase current includes a first fundamental frequency current component, a first low frequency current component and a first high frequency current component, the second phase current includes a second fundamental frequency current component, a second low frequency current component and a second high frequency current component, and the third phase current includes a third fundamental frequency current component, a third low frequency current component and a third high frequency current component;

[0017] The step of determining the beat current angular frequency corresponding to the low-frequency current component in the three-phase stator current comprises:

[0018] Converting the amplitude and phase angle of each current component in the three-phase stator current to a plane coordinate system;

[0019] Determining that the fundamental frequency current component and the high frequency current component in the three-phase stator current are positive sequence;

[0020] It is determined that the low-frequency current component in the three-phase stator current is a negative sequence, and the beat current angular frequency corresponding to the low-frequency current component is obtained.

[0021] In the above control method, obtaining the first voltage compensation amount and the second voltage compensation amount in the corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component includes:

[0022] Inputting the first conversion current component and the second conversion current component into a low-pass filter respectively to obtain a first current DC component and a second current DC component;

[0023] By performing PI control on the first current DC component and the second current DC component, a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system are respectively obtained.

[0024] In the above control method, the first current DC component and the second current DC component are subjected to PI control to obtain the first voltage compensation amount and the second voltage compensation amount in the corresponding beat frequency coordinate system, respectively, including:

[0025] Obtaining a first reference value and a second reference value for inputting into a PI controller, wherein the first reference value corresponds to the first current DC component, the second reference value corresponds to the second current DC component, and the first reference value and the second reference value are both set to zero;

[0026] Perform PI control according to the first reference value and the first current DC component to obtain a first voltage compensation amount in a corresponding beat frequency coordinate system;

[0027] PI control is performed according to the second reference value and the second current DC component to obtain a second voltage compensation amount in a corresponding beat frequency coordinate system.

[0028] In the above control method, before obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor, the control method further includes:

[0029] Obtaining a three-phase output voltage of the three-phase inverter circuit;

[0030] When the three-phase output voltage acts on the permanent magnet synchronous motor, a three-phase stator current with an angular frequency corresponding to the three-phase output voltage is generated.

[0031] In the above control method, the three-phase output voltage includes a first phase voltage, a second phase voltage and a third phase voltage, the first phase voltage includes a first fundamental frequency voltage component, a first low frequency voltage component and a first high frequency voltage component, the second phase voltage includes a second fundamental frequency voltage component, a second low frequency voltage component and a second high frequency voltage component, and the third phase voltage includes a third fundamental frequency voltage component, a third low frequency voltage component and a third high frequency voltage component.

[0032] In a second aspect, an embodiment of the present invention provides an operation control device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the control method as described in the embodiment of the first aspect is implemented.

[0033] In a third aspect, an embodiment of the present invention provides a three-phase AC transmission system, comprising an operation control device as described in the embodiment of the second aspect above.

[0034] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the control method described in the embodiment of the first aspect above.

[0035] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further described below in conjunction with the accompanying drawings and embodiments;

[0037] Figure 1 is a schematic diagram of a three-phase AC transmission system provided by an embodiment of the present invention;

[0038] Figure 2 is a flow chart of a control method for a three-phase AC transmission system provided by an embodiment of the present invention;

[0039] Figure 3 A beat frequency phenomenon current waveform diagram corresponding to A provided in an embodiment of the present invention;

[0040] Figure 4 A current harmonic analysis diagram of the beat frequency current of phase A provided by an embodiment of the present invention;

[0041] Figure 5 A schematic diagram showing the frequency components and phase sequence of the three-phase stator current provided by an embodiment of the present invention in a plane coordinate system;

[0042] Figure 6 A schematic diagram of a beat frequency suppression module provided in an embodiment of the present invention;

[0043] Figure 7 A schematic diagram of a voltage-compensated beat frequency suppression system based on a beat frequency coordinate system provided by an embodiment of the present invention;

[0044] Figure 8 A phase current waveform diagram corresponding to working condition 1 provided in an embodiment of the present invention;

[0045] Fig. 9 A diagram showing the harmonic content of the A-phase current before and after compensation corresponding to the working condition 1 provided in an embodiment of the present invention;

[0046] Fig.10 A motor torque waveform diagram under working condition 1 provided by an embodiment of the present invention;

[0047] Fig.11 A motor speed frequency waveform diagram under working condition 1 provided by an embodiment of the present invention;

[0048] Fig.12 A phase current waveform diagram before and after adding beat frequency suppression under working condition 2 provided by an embodiment of the present invention;

[0049] Fig.13A harmonic analysis diagram of the A-phase current waveform before and after adding beat frequency suppression under working condition 2 provided by an embodiment of the present invention;

[0050] Fig.14 The motor torque waveform diagram before and after adding beat frequency suppression under working condition 2 provided by an embodiment of the present invention;

[0051] Fig.15 The motor speed frequency waveform diagram before and after adding beat frequency suppression under working condition 2 provided by an embodiment of the present invention;

[0052] Fig.16 The A-phase current waveform before and after adding beat frequency suppression under working condition 3 provided by an embodiment of the present invention;

[0053] Fig.17 Harmonic analysis of the A-phase current waveform before and after adding beat frequency suppression under working condition 3 provided by an embodiment of the present invention;

[0054] Fig.18 The motor torque waveform before and after adding beat frequency suppression under working condition 3 provided by an embodiment of the present invention;

[0055] Fig.19 The motor speed frequency waveform before and after adding beat frequency suppression under working condition 3 provided by an embodiment of the present invention;

[0056] Fig. 20 It is a structural schematic diagram of the operation control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0058] It should be understood that in the description of the embodiments of the present invention, if there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features. "At least one" means one or more, "more than" means more than two, greater than, less than, exceeding, etc. are understood to not include the number itself, above, below, within, etc. are understood to include the number itself, and "several" means one or more, unless otherwise clearly and specifically limited. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. It can be understood that A and / or B can represent the situation where A exists alone, A and B exist at the same time, or B exists alone. Among them, A and B can be singular or plural.

[0059] In addition, unless otherwise clearly specified and limited, the term "connected / connected" should be understood in a broad sense, for example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium. It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in a different order from that in the flowchart. It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0060] In a three-phase AC drive system powered by a single-phase AC power supply, the single-phase rectifier in the three-phase AC drive system will have a double frequency pulsation component in both the input and output power during operation. This characteristic makes the DC side voltage of the three-phase AC drive system prone to 100Hz pulsation. This pulsating voltage will directly cause obvious beat frequency phenomenon in the stator voltage and current of the motor, especially when the motor runs at a frequency close to the double frequency of the power grid, its influence becomes particularly obvious and prominent. At this time, the power loss of the motor increases, the temperature rises sharply, and serious mechanical jitter and unbearable noise pollution are generated. In order to solve the beat frequency problem caused by the pulsation of the DC bus voltage, two major methods are currently used: hardware methods and software methods. The hardware method mainly suppresses the pulsating voltage on the DC side directly through a specific hardware circuit design (such as adding an additional power decoupling circuit or increasing the electrolytic capacitor). The hardware method of the related art requires the addition of additional components, which not only increases the cost, but also makes the control more complicated. The software method focuses more on achieving suppression of the bus double frequency voltage or direct beat frequency current by optimizing the control algorithm. However, in the traditional vector control system, the rotating coordinate system based on the motor angular velocity cannot convert the harmonic beat frequency current into a DC current signal for error-free control, which will lead to control errors and lack of versatility.

[0061] Based on this, the embodiment of the present application proposes a control method, control device, system and medium for a three-phase AC transmission system, which does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add an additional power decoupling circuit or increase the electrolytic capacitor. From the perspective of the control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed by the double frequency pulsating voltage on the motor side. It is not only low-cost but also simple in structure. In addition, the present application also uses a new rotating coordinate system with the beat frequency angular frequency as the rotation angular velocity to convert the beat frequency AC current into a DC current for control, forming a beat frequency suppression module independent of the transmission control system. It is not only highly versatile, but also cleverly solves the problem of zero-difference control of the beat frequency AC current.

[0062] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0063] like Figure 1 As shown, an embodiment of the present invention provides a schematic diagram of a three-phase AC transmission system, which includes a single-phase bridge rectifier filter circuit 110, a three-phase inverter circuit 120 and a permanent magnet synchronous motor 130 connected in sequence, wherein the three-phase inverter circuit 120 is used to provide a three-phase output voltage for the permanent magnet synchronous motor 130.

[0064] The single-phase bridge rectifier filter circuit 110 includes a single-phase bridge rectifier and a DC bus capacitor. The single-phase bridge rectifier is used to convert the input three-phase AC power into DC power. The single-phase bridge rectifier rectifier is usually composed of four diodes, which bridge two AC input phases in each AC cycle to generate a pulsating DC voltage on the load; the DC bus capacitor C dc In parallel with the output of the single-phase bridge rectifier, the DC bus capacitor C dc It is used to smooth the pulsating DC voltage after rectification, reduce the voltage ripple, and provide a relatively stable DC power supply for the three-phase inverter circuit 120.

[0065] The three-phase inverter circuit 120 converts the DC power on the DC bus into three-phase AC power, and provides a three-phase output voltage for the permanent magnet synchronous motor 130. The three-phase inverter circuit 120 uses electronic switches (such as IGBTs or transistors) to perform switching operations at a high frequency to generate three-phase AC power with controllable amplitude and phase.

[0066] The permanent magnet synchronous motor (PMSM) 130 can convert electrical energy into mechanical energy to drive the load to rotate. The permanent magnet synchronous motor 130 has high efficiency, high power density and good control performance, and is suitable for applications that require precise control of speed and torque.

[0067] Figure 2 is a flow chart of a control method for a three-phase AC transmission system provided by an embodiment of the present invention. The control method for a three-phase AC transmission system can be applied to Figure 1 In the three-phase AC drive system in the illustrated embodiment, the control method may include but is not limited to steps S110 to S160.

[0068] Step S110: when the DC side voltage of the single-phase bridge rectifier filter circuit has double frequency pulsation, the three-phase stator current of the stator side of the permanent magnet synchronous motor is obtained.

[0069] It is understandable that if Figure 1 As shown in the figure, due to the instantaneous power imbalance between the input and output power of the single-phase rectifier bridge, the DC bus voltage u dc(t) contains a pulsating voltage of twice the grid frequency, wherein the expression of the DC bus voltage is specifically shown in formula (1), that is:

[0070]

[0071] Among them, U dc is the DC component of the DC bus voltage, ΔU dc is the amplitude of the pulsating component of the DC bus voltage, ω s is the grid voltage angular frequency, is the grid power factor angle.

[0072] Ideally, the DC component of the DC bus voltage is a constant value, namely, U dc is a constant, then the functional expression of the base frequency switching function of the three-phase inverter circuit is specifically shown in formula (2), that is:

[0073]

[0074] Where m is the sine pulse width modulation degree, m = U m / U dc , U m is the effective value of the three-phase inverter circuit output, ω e It is the operating frequency of the three-phase inverter circuit, that is, the rotor rotation frequency of the permanent magnet synchronous motor.

[0075] The three-phase output voltage of the three-phase inverter circuit can be obtained from formulas (1) and (2), where the A phase voltage u a The specific expression of (t) is shown in formula (3), that is:

[0076]

[0077] From formula (3), we can know that when the DC side voltage of the single-phase bridge rectifier filter circuit has a double frequency pulsation, the A phase voltage is composed of three components, which are the output angular frequency ω of the three-phase inverter circuit. e The fundamental voltage component and angular frequency are 2ω s -ω e The low-frequency voltage component and angular frequency are 2ω s +ω e The high-frequency voltage components are u a0 (t),u a1 (t) and u a2 (t), whose expression is shown in formula (4).

[0078]

[0079] Similarly, the voltage expression u of phase B can be written as b(t) and the voltage expression of phase C u c (t), as shown in formula (5) and formula (6).

[0080]

[0081]

[0082] The three-phase output voltage acts on the permanent magnet synchronous motor to generate a current with a corresponding angular frequency. Therefore, the three-phase stator current on the stator side of the permanent magnet synchronous motor contains not only a fundamental frequency current component, but also an angular frequency of 2ω. s -ω e The low-frequency harmonic current component and the angular frequency are 2ω s +ω e According to the analysis of the impedance characteristics of permanent magnet synchronous motor, the frequency is 2ω s -ω e The impedance value of low-frequency harmonics is much smaller than 2ω s +ω e The impedance value of the high-frequency harmonics, so that the low-frequency harmonic current becomes the main harmonic component of the permanent magnet synchronous motor current. Figure 3 and Figure 4 As shown, Figure 3 The beat frequency current waveform corresponding to A is shown in Figure 2. Figure 4 is the current harmonic analysis diagram corresponding to the beat frequency phenomenon current of phase A, wherein the grid frequency corresponding to the beat frequency phenomenon current waveform diagram and the beat frequency phenomenon current harmonic analysis diagram is 50Hz, and the permanent magnet synchronous motor speed angular frequency is 99Hz. Figure 3 It can be seen that there is a very obvious 1Hz pulsation in the stator current of the permanent magnet synchronous motor. In order to more intuitively observe the harmonic content of each frequency, Fourier analysis is performed on the A phase current, as shown in Figure 4 shown. Figure 4 It shows that the fundamental frequency of phase A current is 99Hz, the low-frequency harmonic is 1Hz, the high-frequency current is 199Hz, and the low-frequency component is much larger than the high-frequency component, becoming the main harmonic current. The low-frequency harmonic current causes the electromagnetic torque of the permanent magnet synchronous motor to have obvious low-frequency oscillation, thus forming a beat frequency phenomenon. Therefore, the low-frequency current component can be called the beat frequency current.

[0083] In addition, it can be known from the motor principle that the frequency components of the three-phase stator voltage and the three-phase stator current on the stator side of the permanent magnet synchronous motor are completely consistent. Therefore, the three-phase stator current on the stator side of the permanent magnet synchronous motor can be directly obtained, and they are respectively set as i a 、i b and i c , as shown in formula (7).

[0084]

[0085] Among them, i a1 、i b1 、i c1 They are respectively the angular frequency of the three-phase stator current in the three-phase stationary coordinate system is ω e The amplitude of the component; i a2 、i b2 、i c2 The angular frequency of the three-phase stator current is 2ω s -ω e The amplitude of the component; i a3 、i b3 、i c3 The angular frequency of the three-phase stator current is 2ω s +ω e The magnitude of the component; The angular frequency is 2ω respectively. s -ω e , 2ω s +ω e Phase angle of the harmonic components.

[0086] Step S120: determining the beat current angular frequency corresponding to the low-frequency current component in the three-phase stator current.

[0087] Among them, the low-frequency current component in the three-phase stator current includes the low-frequency current component in the stator current of phase A, the low-frequency current component in the stator current of phase B and the low-frequency current component in the stator current of phase C.

[0088] Specifically, from formula (7), we can see that the beat current angular frequency corresponding to the low-frequency current component in the three-phase stator current is 2ω s -ω e .

[0089] Step S130: construct a beat frequency coordinate system with the beat frequency current angular frequency as the rotation angular velocity, and perform a negative sequence Park transformation on the three-phase stator current to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system.

[0090] It can be understood that the Park transformation can convert the current or voltage in the three-phase stationary coordinate system into a two-phase rotating coordinate system that is synchronous with the rotor rotation, that is, convert it to the direct axis (d axis) and the quadrature axis (q axis).

[0091] It should be noted that if Figure 5 As shown, replace i in formula (7) a 、i b 、i c The frequency components and phase sequence of the current i are expressed in the plane coordinate system. a 、i b 、ic The rotation frequency is ω e and 2ω s +ω e The component is positive sequence, and the rotation frequency is 2ω s -ω e The component is negative sequence, and the rotation frequency is 2ω extracted by negative sequence park transformation s -ω e Component. Traditional vector control transforms the three-phase AC into a DC component of a two-phase synchronous rotating coordinate system through rotation for zero-difference control. Based on the above analysis, it can be seen that the angular frequency of the beat frequency current (that is, the angular frequency of the beat frequency current corresponding to the low-frequency current component) is inconsistent with the traditional transmission system rotation angular frequency and cannot be transformed in the synchronous coordinate system of traditional vector control. In order to extract the beat frequency current (that is, the low-frequency current component) for precise control, it is necessary to select a new rotating coordinate system in which the beat frequency current angular frequency is the rotation speed, that is, the beat frequency coordinate system, and its rotation angular frequency is 2ω s -ω e , denoted as ω b , the rotation direction is clockwise. Therefore, the preset negative sequence park transformation equation needs to be selected during the rotation transformation, and its expression is shown in formula (8), that is:

[0092]

[0093] The three-phase stator current i a 、i b 、i c After negative sequence park transformation, the first transformed current component i in the beat frequency coordinate system is obtained bd and the second conversion current component i bq , where the first conversion current component i bd and the second conversion current component i bq Specifically, as shown in formula (9), that is:

[0094]

[0095] From formula (9), we can see that in the beat frequency coordinate system, the rotation frequency is ω b The beat frequency current component is transformed into a DC component; the rotation frequency is ω e Transformed into a rotation frequency of 2ω s ; Rotation frequency is 2ω s +ω e Transformed into a rotation frequency of 4ω s .

[0096] Step S140: obtaining a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component.

[0097] Step S150: subjecting the first voltage compensation amount and the second voltage compensation amount to negative sequence inverse Park transformation to obtain a target voltage compensation amount.

[0098] The target voltage compensation includes a first target voltage compensation, a second target voltage compensation and a third target voltage compensation. The target voltage compensation is the compensation of the AC modulation signal. The first target voltage compensation is related to the i in the three-phase stator current. a Correspondingly, it is used to adjust the A-phase current on the stator side of the permanent magnet synchronous motor. The second target voltage compensation amount is proportional to the i in the three-phase stator current. b Correspondingly, it is used to adjust the B-phase current on the stator side of the permanent magnet synchronous motor. The third target voltage compensation amount is proportional to the i in the three-phase stator current. c Correspondingly, it is used to adjust the C-phase current on the stator side of the permanent magnet synchronous motor.

[0099] In addition, the inverse Park transform is the inverse process of the Park transform, which converts the current or voltage in the two-phase rotating coordinate system back to the three-phase stationary coordinate system.

[0100] Step S160: adjusting the AC modulation signal for controlling the three-phase inverter circuit according to the target voltage compensation amount, so as to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor.

[0101] It can be understood that the AC modulation signal used to control the three-phase inverter circuit is adjusted according to the target voltage compensation amount, and the three-phase inverter circuit is controlled to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon.

[0102] In an embodiment of the present application, a three-phase AC transmission system includes a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, and the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor. When the DC side voltage of the single-phase bridge rectifier filter circuit has a double frequency pulsation, the three-phase stator current on the stator side of the permanent magnet synchronous motor is obtained, and the beat current angular frequency corresponding to the low-frequency current component in the three-phase stator current is determined. The beat frequency coordinate system is constructed with the beat current angular frequency as the rotation angular velocity, and the three-phase stator current is transformed by a negative sequence Park transformation to obtain To the first transformed current component and the second transformed current component in the beat frequency coordinate system, the first voltage compensation amount and the second voltage compensation amount in the corresponding beat frequency coordinate system are obtained according to the first transformed current component and the second transformed current component, and the first voltage compensation amount and the second voltage compensation amount are subjected to negative sequence inverse Park transformation to obtain the target voltage compensation amount, and the AC modulation signal used to control the three-phase inverter circuit can be adjusted according to the target voltage compensation amount, so as to directly and effectively control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. That is to say, the embodiment of the present application does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add additional power decoupling circuits or increase electrolytic capacitors. From the perspective of control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed by the double frequency pulsating voltage on the motor side, and achieving zero-difference control of the beat frequency AC current without adding additional components. In addition, the present application also uses a new rotating coordinate system with the beat frequency angular frequency as the rotation angular velocity to convert the beat frequency AC current into DC current for control, thereby forming a beat frequency suppression module independent of the transmission control system. It is not only highly versatile, but also cleverly solves the problem of zero-difference control of the beat frequency AC current.

[0103] In some embodiments, when the three-phase stator current includes a first phase current, a second phase current and a third phase current, the first phase current includes a first fundamental frequency current component, a first low frequency current component and a first high frequency current component, the second phase current includes a second fundamental frequency current component, a second low frequency current component and a second high frequency current component, and the third phase current includes a third fundamental frequency current component, a third low frequency current component and a third high frequency current component, then step S120 may include but is not limited to steps S210 to S230.

[0104] Step S210: converting the amplitude and phase angle of each current component in the three-phase stator current to a plane coordinate system.

[0105] It is understood that the current signal is subjected to Fourier decomposition or other signal processing techniques are used to extract components of different frequencies, including fundamental frequency, low frequency and high frequency components. For each identified frequency component, its phase angle is calculated. In the complex form of the spectrum, each frequency component can be expressed as a complex form of amplitude and phase angle. In the plane coordinate system, the phase sequence can be visualized by converting the amplitude and phase angle of each frequency component into a point in the polar coordinate system.

[0106] Step S220: Determine whether the fundamental frequency current component and the high frequency current component in the three-phase stator current are positive sequence.

[0107] The fundamental frequency current component includes a first fundamental frequency current component, a second fundamental frequency current component and a third fundamental frequency current component; the high frequency current component includes a first high frequency current component, a second high frequency current component and a third high frequency current component.

[0108] Step S230: determine whether the low-frequency current component in the three-phase stator current is a negative sequence, and obtain the beat current angular frequency corresponding to the low-frequency current component.

[0109] The low-frequency current component includes a first low-frequency current component, a second low-frequency current component and a third low-frequency current component.

[0110] It should be noted that, as shown in formula (7), the first phase current i a , the second phase current is i b , the third phase current is i c , the first fundamental frequency current component is i a1 sinω e t, the first low-frequency current component is The first high-frequency current component is The second fundamental frequency current component is The second low-frequency current component is The second high-frequency current component is The third fundamental frequency current component is The third low-frequency current component is The third high-frequency current component is

[0111] For example, Figure 5 As shown, replace i in formula (7) a 、i b 、i c The amplitude and phase angle of the current i are expressed in the plane coordinate system. a 、i b 、i c The rotation frequency is ω e and 2ω s +ω eThe component is positive sequence, and the rotation frequency is 2ω s -ω e The component is negative sequence, and the rotation frequency is 2ω extracted by negative sequence park transformation s -ω e The amount.

[0112] In the embodiment of the present application, the amplitude and phase angle of each current component in the three-phase stator current are converted to a plane coordinate system, and then the base frequency current component and the high frequency current component in the three-phase stator current are determined to be positive sequence, and finally the low frequency current component in the three-phase stator current is determined to be negative sequence, so as to realize the visualization of the phase sequence in the polar coordinate system. And the beat current angular frequency corresponding to the low frequency current component is obtained, so that the beat current angular frequency can be used as the rotation angular velocity to construct a beat coordinate system in the subsequent steps.

[0113] In some embodiments, step S140 may include but is not limited to steps S310 to S320.

[0114] Step S310: input the first converted current component and the second converted current component into a low-pass filter respectively to obtain a first current DC component and a second current DC component.

[0115] Among them, a low pass filter (LPF) is a circuit element that allows low frequency signals to pass through while suppressing high frequency signals above a specific cutoff frequency.

[0116] Step S320: performing PI control on the first current DC component and the second current DC component to obtain a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system respectively.

[0117] Specifically, Figure 6 As shown, after the negative sequence park transformation, the first transformation current component i bd and the second conversion current component i bq The first current DC component i in the beat frequency coordinate system can be obtained by LPF bd_filter and the second current DC component i bq_filter , and then the first voltage compensation value V corresponding to the beat frequency coordinate is obtained through PI control bd and the second voltage compensation amount V bq Furthermore, the target voltage compensation amount of the AC modulation signal is obtained through negative sequence inverse park transformation, and the above control process forms a beat frequency suppression module.

[0118] In an embodiment of the present application, the first converted current component and the second converted current component are respectively input into a low-pass filter to obtain a first current DC component and a second current DC component, and then the first current DC component and the second current DC component are subjected to PI control to obtain a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system, so that a target voltage compensation amount can be obtained according to the first voltage compensation amount and the second voltage compensation amount in subsequent steps, thereby forming a beat frequency suppression module independent of the transmission control system, which has a simple structure and is particularly suitable for applications in technical transformation.

[0119] In some embodiments, step S320 may include but is not limited to steps S410 to S430.

[0120] Step S410: Obtain a first reference value and a second reference value for inputting into a PI controller, wherein the first reference value corresponds to a first current DC component, the second reference value corresponds to a second current DC component, and both the first reference value and the second reference value are set to zero.

[0121] like Figure 6 In the PI controller, the first reference value i is input bd * and second reference value i bq * is set to zero to achieve the first current DC component i bd_filter and the second current DC component i bq_filter The zero-error tracking. When the first DC component i bd_filter and the second current DC component i bq_filter When the component is zero, the beat frequency phenomenon caused by the secondary pulsation of the DC bus voltage can be eliminated.

[0122] It should be noted that the PI controller (proportional integral controller) is a simple feedback controller widely used in industrial control systems to improve the stability and response performance of the system. PI stands for the two control links of proportional and integral. Among them, proportional control is the basic part of the PI controller, which adjusts the output proportionally according to the size of the error signal (the difference between the set value and the actual output); integral control is used to eliminate steady-state errors, and it responds to the accumulation (integral) of the error signal over time.

[0123] Step S420: performing PI control according to the first reference value and the first current DC component to obtain a first voltage compensation amount in a corresponding beat frequency coordinate system.

[0124] Step S430: performing PI control according to the second reference value and the second current DC component to obtain a second voltage compensation amount in a corresponding beat frequency coordinate system.

[0125] In the embodiment of the present application, by obtaining the first reference value and the second reference value for inputting into the PI controller, and setting the first reference value and the second reference value inputted into the PI controller to zero, the zero-static tracking of the first current DC component and the second current DC component in the current is realized. When the first current DC component and the second current DC component in the current are zero, the beat frequency phenomenon caused by the secondary pulsation of the DC bus voltage can be eliminated. In addition, the embodiment of the present application directly adopts the beat frequency suppression technology of extracting the beat frequency current, changing the beat frequency coordinates, and controlling the PI to generate the compensation modulation signal. The beat frequency current suppression effect is direct, intuitive and effective, and the beat frequency current suppression rate reaches more than 97%.

[0126] In some embodiments, step S160 may include but is not limited to steps S510 to S530.

[0127] Step S510: Acquire an AC modulation signal for controlling a three-phase inverter circuit.

[0128] Among them, the AC modulation signal of the three-phase inverter circuit is the modulation signal obtained by the original transmission system through the vector control algorithm.

[0129] Step S520: superimposing the AC modulation signal and the target voltage compensation amount to obtain a target modulation signal.

[0130] The target modulation signal is a modulation signal of a SVPWM (Space Vector Pulse Width Modulation) module, which is used to generate a voltage vector required by the motor to control the torque and speed of the motor.

[0131] Step S530: controlling the three-phase inverter circuit to provide current for the permanent magnet synchronous motor according to the target modulation signal.

[0132] For example, as shown in FIG7 , the beat frequency suppression module is placed into the traditional vector control to obtain a voltage-compensated beat frequency suppression system based on the beat frequency coordinate system. Figure 7 In the three-phase inverter circuit, the AC modulation signal V a 、V b 、V c , the target voltage compensation amount is V ba 、V bb 、V bc The three-phase stator current i of the motor a 、i b and i c The target voltage compensation value V is formed after calculation and processing by the beat frequency suppression module. ba 、V bb and V bc, and the AC modulation signal is superimposed to form the target modulation signal, which controls the three-phase inverter circuit to provide the motor voltage and current. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. Specifically, the rotation angle θ of the double frequency grid is obtained through a single-phase AC phase-locked loop s , calculated twice and the motor angle θ e Subtracting them will give the rotation angle θ corresponding to the beat frequency angular frequency. b .

[0133] In an embodiment of the present application, an AC modulation signal for controlling a three-phase inverter circuit is obtained, and then the AC modulation signal and the target voltage compensation amount are superimposed to obtain a target modulation signal. Finally, the three-phase inverter circuit is controlled according to the target modulation signal to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon.

[0134] In some embodiments, before obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor, the control method further includes the following steps:

[0135] Step S610: obtaining the three-phase output voltage of the three-phase inverter circuit;

[0136] Step S620: When the three-phase output voltage acts on the permanent magnet synchronous motor, a three-phase stator current with an angular frequency corresponding to the three-phase output voltage is generated.

[0137] It can be seen from the motor principle that the frequency components of the three-phase output voltage and the three-phase stator current on the stator side of the permanent magnet synchronous motor are completely consistent. Therefore, the corresponding three-phase stator current can be obtained based on the three-phase output voltage. The three-phase stator current is specifically shown in formula (7), which will not be repeated here.

[0138] In an embodiment of the present application, by obtaining the three-phase output voltage of the three-phase inverter circuit, when the three-phase output voltage acts on a permanent magnet synchronous motor, a three-phase stator current with an angular frequency corresponding to the three-phase output voltage is generated, and the AC modulation signal used to control the three-phase inverter circuit can be adjusted based on the three-phase stator current to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor.

[0139] In some embodiments, the three-phase output voltage includes a first phase voltage, a second phase voltage and a third phase voltage, the first phase voltage includes a first fundamental frequency voltage component, a first low frequency voltage component and a first high frequency voltage component, the second phase voltage includes a second fundamental frequency voltage component, a second low frequency voltage component and a second high frequency voltage component, and the third phase voltage includes a third fundamental frequency voltage component, a third low frequency voltage component and a third high frequency voltage component.

[0140] Among them, the first phase voltage corresponds to the first phase current, the first fundamental frequency voltage component corresponds to the first fundamental frequency current component, the first low frequency voltage component corresponds to the first low frequency current component, and the first high frequency voltage component corresponds to the first high frequency current component; the second phase voltage corresponds to the second phase current, the second fundamental frequency voltage component corresponds to the second fundamental frequency current component, the second low frequency voltage component corresponds to the second low frequency current component, and the second high frequency voltage component corresponds to the second high frequency current component; the third phase voltage corresponds to the third phase current, the third fundamental frequency voltage component corresponds to the third fundamental frequency current component, the third low frequency voltage component corresponds to the third low frequency current component, and the third high frequency voltage component corresponds to the third high frequency current component.

[0141] Specifically, as shown in formula (3), the first phase voltage, i.e., u a (t), the first fundamental frequency voltage component is U m sinω e t, the first low-frequency voltage component is The first high-frequency voltage component is

[0142]

[0143] As shown in formula (5), the second phase voltage is u b (t), the second fundamental frequency voltage component is The second low-frequency voltage component is The second high-frequency voltage component is

[0144] As shown in formula (6), the third phase voltage, i.e., u c (t), the third fundamental frequency voltage component is The third low-frequency voltage component is The third high-frequency voltage component is

[0145]

[0146] In order to verify the effectiveness and frequency adaptability of the beat frequency suppression technology, the operation of a three-phase AC drive system with single-phase AC power supply at three different operating frequencies was simulated, and the current waveform and harmonic content, compensation voltage waveform, torque and motor speed frequency waveform were observed to prove the effect of the proposed beat frequency suppression.

[0147] Among them, the AC transmission system adopts a permanent magnet synchronous motor, and the motor parameters are shown in Table 1.

[0148] Table 1

[0149] PMSM parameters Numeric Permanent magnet flux / Wb 0.4 Stator resistance / Ω 0.0485 D-axis inductance / mH 8.5 Q-axis inductance / mH 8.5 Pole pairs 1 Rated torque / (N·m) 5

[0150] Working condition 1: When the motor runs at 99Hz, the load torque is 5N*m, and the beat frequency suppression algorithm is added at t=5s, and the A phase current waveform is observed, such as Figure 8 and Fig. 9 shown.

[0151] Figure 8 It shows that when the beat frequency suppression algorithm is not added, the current of phase A has obvious 1Hz fluctuation, and the maximum current fluctuation value reaches 4.05A. After adding the beat frequency suppression algorithm, the 1Hz current waveform is basically eliminated, and the current fluctuation value is reduced to 0.51A. In order to obtain the specific size of the beat frequency current, the FFT analysis of the current of phase A is performed, and the following is obtained: Fig. 9 The harmonic content of phase A current before and after compensation is shown in the figure. It can be seen from the figure that the 99Hz fundamental current in phase A current is 8.85A, and before adding the beat frequency suppression algorithm, the 1Hz beat frequency current is 0.73A. After adding the beat frequency suppression algorithm, the 1Hz beat frequency current is reduced to 0.02A, and the suppression rate is 97.3%.

[0152] Fig.10 This is the motor torque waveform under working condition 1. Fig.11 This is the motor speed frequency waveform under working condition 1. Fig.10 It shows that when the beat frequency suppression algorithm is not added, the torque fluctuation of the motor reaches 2.94N*m. After adding the beat frequency suppression algorithm, the torque fluctuation is reduced to 1.3N*m. Fig.11 It shows that when the beat frequency suppression algorithm is not added, the speed frequency fluctuation of the motor is 0.2Hz. After adding the beat frequency suppression algorithm, the speed frequency fluctuation of the motor is reduced to 0.01Hz.

[0153] Working condition 2: In order to verify that the beat frequency suppression algorithm is applicable to different operating frequencies, the motor operating frequency is controlled at 95Hz, the load torque is 5N*m, and the beat frequency suppression algorithm is added at t=5s to observe the current waveform and harmonic content, torque and motor speed frequency. Fig.12 The waveform of the A phase current before and after adding beat frequency suppression under working condition 2 is shown below. Fig.13 This is the harmonic analysis diagram of the A-phase current waveform before and after adding beat frequency suppression under working condition 2.

[0154] Fig.12 It shows that when the motor speed frequency is 95Hz, the A phase current has a very obvious 5Hz fluctuation, and the fluctuation amplitude reaches 3.61A. After adding the beat frequency suppression algorithm for 5s, the maximum fluctuation value of the current is reduced to 0.27A, which is significantly suppressed. The FFT analysis of the A phase current waveform before and after adding the beat frequency suppression algorithm is shown in the following figure. Fig.13 As shown in the figure, it can be seen that before the beat frequency suppression algorithm is added, the 5Hz harmonic content in the A phase current is 0.66A. After the beat frequency suppression algorithm is added, the 5Hz harmonic content is reduced to 0.01A, and the suppression rate is 98.5%.

[0155] Fig.14The figure shows the motor torque waveform before and after adding beat frequency suppression under working condition 2. When the beat frequency suppression algorithm is not added, the torque fluctuation of the motor reaches 2.71N*m. After adding the beat frequency suppression algorithm, the torque fluctuation is reduced to 1.32N*m. Fig.15 The figure shows the motor speed frequency waveform before and after adding beat frequency suppression under working condition 2. When the beat frequency suppression algorithm is not added, the motor speed frequency fluctuation is 0.2Hz. After adding the beat frequency suppression algorithm, the motor speed frequency fluctuation is reduced to 0.02Hz.

[0156] Working condition 3: In order to verify the proposed algorithm for the case where the motor operating frequency is higher than twice the frequency, working condition 3 is set as the motor running at 105Hz, the load torque is still 5N*m, and the beat frequency suppression algorithm is added at t=5s to simulate and observe the motor current, torque and speed frequency. Fig.16 The A-phase current waveform before and after adding beat frequency suppression under working condition 3. Fig.17 This is the harmonic analysis of the A phase current waveform before and after adding beat frequency suppression under working condition 3. Fig.16 It shows that before adding the beat frequency suppression algorithm, the current of phase A under working condition 3 contains very obvious 5Hz fluctuations, and the maximum current fluctuation value reaches 4.67A. After adding the beat frequency suppression algorithm, the maximum current fluctuation value is reduced to 0.55A. FFT analysis of the current of phase A is performed to obtain the size of the 5Hz component in the current of phase A before and after adding the algorithm, as shown in Fig.17 As shown, before the beat frequency suppression algorithm is added, the 5 Hz beat frequency current in the A phase current is 0.76 A. After the beat frequency suppression algorithm is added, the 5 Hz beat frequency current is reduced to 0.02 A, and the harmonic suppression rate is 97.4%.

[0157] Fig.18 The figure shows the motor torque waveform before and after adding beat frequency suppression under working condition 3. Fig.19 The figure shows the motor speed frequency waveform before and after adding beat frequency suppression under working condition 3. Fig.18 As shown in the figure, when the beat frequency suppression algorithm is not added, the torque fluctuation of the motor reaches 3.56N*m. After adding the beat frequency suppression algorithm, the torque fluctuation is reduced to 1.25N*m. Fig.19 As shown in the figure, before adding the beat frequency suppression algorithm, the motor speed frequency fluctuation is 0.19Hz. After adding the beat frequency suppression algorithm, the motor speed frequency fluctuation is reduced to 0.01Hz, and the motor speed is smooth and stable.

[0158] In summary, through the simulation experiment of the three-phase AC drive system with single-phase AC power supply under three different motor speed and frequency conditions, it is verified that the voltage compensation beat frequency suppression strategy based on the beat frequency coordinate system can greatly reduce the beat frequency phenomenon caused by the secondary fluctuation of the DC bus voltage, and basically eliminate the beat frequency current. The beat frequency current suppression rate is more than 97%. At the same time, the beat frequency suppression technology reduces the fluctuation of the motor torque, and the fluctuation of the motor speed frequency is also greatly reduced. Therefore, the beat frequency phenomenon is effectively suppressed.

[0159] like Fig. 20 As shown, the third aspect of the present invention provides an operation control device 1000, including a memory 1010, a processor 1020, and a computer program stored in the memory 1010 and executable on the processor 1020, wherein the processor 1020 and the memory 1010 can be connected via a bus or other means. Fig. 20 An example of connection via a bus is shown, and when the processor executes the computer program, the control method of the first aspect embodiment described above is implemented.

[0160] The operation control device provided by the embodiment of the present invention, on the basis of a three-phase AC transmission system including a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, and the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor, by obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor when there is a double frequency pulsation in the DC side voltage of the single-phase bridge rectifier filter circuit, determining the beat frequency current angular frequency corresponding to the low-frequency current component in the three-phase stator current, constructing a beat frequency coordinate system with the beat frequency current angular frequency as the rotation angular velocity, subjecting the three-phase stator current to a negative-sequence Park transformation to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system, and obtaining a first voltage compensation amount and a second voltage compensation amount in the corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component. Voltage compensation amount, the first voltage compensation amount and the second voltage compensation amount are subjected to negative-sequence inverse Park transformation to obtain a target voltage compensation amount, and the AC modulation signal used to control the three-phase inverter circuit can be adjusted according to the target voltage compensation amount, so as to directly and effectively control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. That is to say, the embodiment of the present application does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add additional power decoupling circuits or increase electrolytic capacitors. From the perspective of control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed on the motor side by the double frequency pulsating voltage, and realizing the difference-free control of the beat frequency AC current without adding additional components.

[0161] A third aspect of the present invention provides a three-phase AC transmission system, comprising the operation control device of the second aspect of the present invention.

[0162] According to the three-phase AC transmission system provided by the embodiment of the present invention, the three-phase AC transmission system includes a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, and the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor. When the DC side voltage of the single-phase bridge rectifier filter circuit has a double frequency pulsation, the three-phase stator current on the stator side of the permanent magnet synchronous motor is obtained, and the beat frequency current angular frequency corresponding to the low-frequency current component in the three-phase stator current is determined. A beat frequency coordinate system is constructed with the beat frequency current angular frequency as the rotation angular velocity, and the three-phase stator current is subjected to a negative-sequence Park transformation to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system. According to the first transformed current component and the second transformed current component, a first voltage compensation amount and a corresponding voltage compensation amount in the beat frequency coordinate system are obtained. The second voltage compensation amount, the first voltage compensation amount and the second voltage compensation amount are subjected to negative-sequence inverse Park transformation to obtain a target voltage compensation amount, and then the AC modulation signal used to control the three-phase inverter circuit is adjusted according to the target voltage compensation amount, so as to directly and effectively control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. That is to say, the embodiment of the present application does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add additional power decoupling circuits or increase the electrolytic capacitor. From the perspective of the control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed on the motor side by the double frequency pulsating voltage, and achieving zero-difference control of the beat frequency AC current without adding additional components.

[0163] The fourth aspect of the present invention provides a computer-readable storage medium, which stores computer-executable instructions, and the computer-executable instructions can be used to enable a computer to execute the control method of the first aspect of the present invention. On the basis that the three-phase AC transmission system includes a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, and the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor, when the DC side voltage of the single-phase bridge rectifier filter circuit has a double frequency pulsation, the three-phase stator current on the stator side of the permanent magnet synchronous motor is obtained, and the beat frequency current angular frequency corresponding to the low-frequency current component in the three-phase stator current is determined, and a beat frequency coordinate system is constructed with the beat frequency current angular frequency as the rotation angular velocity, and the three-phase stator current is subjected to a negative sequence Park transformation to obtain a first conversion current component and a second conversion current component in the beat frequency coordinate system, and the first voltage compensation amount and the second voltage compensation amount in the corresponding beat frequency coordinate system are obtained according to the first conversion current component and the second conversion current component, and the first voltage compensation amount and the second voltage compensation amount in the beat frequency coordinate system are obtained according to the first conversion current component and the second conversion current component. A voltage compensation amount and a second voltage compensation amount are transformed through negative-sequence inverse Park to obtain a target voltage compensation amount, and the AC modulation signal used to control the three-phase inverter circuit can be adjusted according to the target voltage compensation amount, so as to directly and effectively control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor. At this time, the beat frequency current in the permanent magnet synchronous motor current is eliminated, thereby suppressing the beat frequency phenomenon. That is to say, the embodiment of the present application does not need to consider the double frequency pulsation in the DC side voltage, nor does it need to add additional power decoupling circuits or increase electrolytic capacitors. From the perspective of control strategy, the beat frequency current is separated to form a compensation voltage for the output voltage of the three-phase inverter circuit, thereby eliminating the beat frequency current formed on the motor side by the double frequency pulsating voltage, and achieving zero-difference control of the beat frequency AC current without adding additional components.

[0164] It will be appreciated by those skilled in the art that all or some of the steps and systems in the disclosed methods above may be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components may be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium or a non-transitory medium and a communication medium or a temporary medium. As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk DVD or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that may be used to store desired information and may be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0165] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A control method for a three-phase AC drive system, characterized in that: The three-phase AC transmission system comprises a single-phase bridge rectifier filter circuit, a three-phase inverter circuit and a permanent magnet synchronous motor connected in sequence, wherein the three-phase inverter circuit is used to provide a three-phase output voltage for the permanent magnet synchronous motor, and the control method comprises: When the DC side voltage of the single-phase bridge rectifier filter circuit has double frequency pulsation, obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor; Determining a beat current angular frequency corresponding to a low-frequency current component in the three-phase stator current; A beat frequency coordinate system is constructed with the beat frequency current angular frequency as the rotation angular velocity, and the three-phase stator current is subjected to a negative sequence Park transformation to obtain a first transformed current component and a second transformed current component in the beat frequency coordinate system; Obtaining a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component; The first voltage compensation amount and the second voltage compensation amount are subjected to negative sequence inverse Park transformation to obtain a target voltage compensation amount, wherein the target voltage compensation amount includes a first target voltage compensation amount, a second target voltage compensation amount and a third target voltage compensation amount; An AC modulation signal for controlling the three-phase inverter circuit is adjusted according to the target voltage compensation amount, so as to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor.

2. The control method according to claim 1, characterized in that: The step of adjusting the AC modulation signal for controlling the three-phase inverter circuit according to the target voltage compensation amount so as to control the three-phase inverter circuit to provide current for the permanent magnet synchronous motor includes: Acquiring an AC modulation signal for controlling the three-phase inverter circuit; Superimposing the AC modulation signal and the target voltage compensation amount to obtain a target modulation signal; The three-phase inverter circuit is controlled according to the target modulation signal to provide current for the permanent magnet synchronous motor.

3. The control method according to claim 1, characterized in that: The three-phase stator current includes a first phase current, a second phase current and a third phase current, the first phase current includes a first fundamental frequency current component, a first low frequency current component and a first high frequency current component, the second phase current includes a second fundamental frequency current component, a second low frequency current component and a second high frequency current component, and the third phase current includes a third fundamental frequency current component, a third low frequency current component and a third high frequency current component; The step of determining the beat current angular frequency corresponding to the low-frequency current component in the three-phase stator current comprises: Converting the amplitude and phase angle of each current component in the three-phase stator current to a plane coordinate system; Determining that the fundamental frequency current component and the high frequency current component in the three-phase stator current are positive sequence; It is determined that the low-frequency current component in the three-phase stator current is a negative sequence, and the beat current angular frequency corresponding to the low-frequency current component is obtained.

4. The control method according to claim 1, characterized in that: The obtaining of the first voltage compensation amount and the second voltage compensation amount in the corresponding beat frequency coordinate system according to the first transformed current component and the second transformed current component includes: Inputting the first conversion current component and the second conversion current component into a low-pass filter respectively to obtain a first current DC component and a second current DC component; By performing PI control on the first current DC component and the second current DC component, a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system are respectively obtained.

5. The control method according to claim 4, characterized in that: The first current DC component and the second current DC component are subjected to PI control to obtain a first voltage compensation amount and a second voltage compensation amount in a corresponding beat frequency coordinate system, respectively, including: Obtaining a first reference value and a second reference value for inputting into a PI controller, wherein the first reference value corresponds to the first current DC component, the second reference value corresponds to the second current DC component, and the first reference value and the second reference value are both set to zero; Perform PI control according to the first reference value and the first current DC component to obtain a first voltage compensation amount in a corresponding beat frequency coordinate system; PI control is performed according to the second reference value and the second current DC component to obtain a second voltage compensation amount in a corresponding beat frequency coordinate system.

6. The control method according to claim 1, characterized in that: Before obtaining the three-phase stator current on the stator side of the permanent magnet synchronous motor, the control method further includes: Obtaining a three-phase output voltage of the three-phase inverter circuit; When the three-phase output voltage acts on the permanent magnet synchronous motor, a three-phase stator current with an angular frequency corresponding to the three-phase output voltage is generated.

7. The control method according to claim 6, characterized in that: The three-phase output voltage includes a first phase voltage, a second phase voltage and a third phase voltage, the first phase voltage includes a first fundamental frequency voltage component, a first low frequency voltage component and a first high frequency voltage component, the second phase voltage includes a second fundamental frequency voltage component, a second low frequency voltage component and a second high frequency voltage component, and the third phase voltage includes a third fundamental frequency voltage component, a third low frequency voltage component and a third high frequency voltage component.

8. An operation control device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the control method according to any one of claims 1 to 7 when executing the computer program.

9. A three-phase AC transmission system, characterized in that: Comprising the operation control device as claimed in claim 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the control method according to any one of claims 1 to 7.

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