Motor control method, controller, control device and magnetic levitation compressor unit

Abstract

The application discloses a motor control method, a motor controller, a control device and a magnetic suspension compressor unit. The motor is driven by a frequency converter. The method comprises the following steps: acquiring an output voltage of the frequency converter; determining a modulation mode of the frequency converter and a frequency modulation mode of the motor according to the output voltage; and controlling the frequency converter according to the determined modulation mode and the frequency modulation mode, so as to control the motor to operate. The method determines the modulation mode of the frequency converter and the frequency modulation mode of the motor according to the output voltage of the frequency converter, guarantees the motor control effect, and is easy to meet the heat dissipation demand of the frequency converter.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation technology, and in particular to a motor control method, a computer-readable storage medium, a motor controller, a motor control device, and a magnetic levitation compressor unit. Background Technology

[0002] High-speed frequency converters used in magnetic levitation compressor units typically operate at frequencies of 700-1000Hz. IGBTs (Insulated Gate Bipolar Transistors) generate significant heat, increasing the requirements for heat dissipation. Conventional motor control methods are relatively simple and cannot meet the inverter's heat dissipation needs while ensuring motor control performance. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the first objective of this invention is to propose a motor control method that determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage of the frequency converter, ensuring effective motor control and easily meeting the heat dissipation requirements of the frequency converter.

[0004] A second objective of this invention is to provide a computer-readable storage medium.

[0005] The third objective of this invention is to provide a motor controller.

[0006] The fourth objective of this invention is to provide a motor control device.

[0007] The fifth objective of this invention is to provide a magnetic levitation compressor unit.

[0008] To achieve the above objectives, a first aspect of the present invention provides a motor control method, wherein the motor is driven by a frequency converter, the method comprising: acquiring the output voltage of the frequency converter; determining the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage; and controlling the frequency converter according to the determined modulation mode and frequency modulation mode to control the operation of the motor.

[0009] According to the motor control method of this invention, firstly, the output voltage of the frequency converter is acquired; then, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined based on the output voltage; and finally, the frequency converter is controlled according to the determined modulation mode and frequency regulation mode to control the motor operation. This method determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage of the frequency converter, ensuring the motor control effect and easily meeting the heat dissipation requirements of the frequency converter.

[0010] In addition, the motor control method according to the above embodiments of the present invention may also have the following additional technical features:

[0011] According to one embodiment of the present invention, determining the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage includes: when the output voltage is less than or equal to a preset voltage threshold, determining the modulation mode as a seven-segment modulation mode and determining the frequency regulation mode as an asynchronous frequency regulation mode; when the output voltage is greater than the preset voltage threshold, determining the modulation mode as a five-segment modulation mode and determining the frequency regulation mode as a synchronous frequency regulation mode.

[0012] According to one embodiment of the present invention, when the frequency converter is controlled by asynchronous frequency modulation, the carrier frequency of the frequency converter is a fixed frequency.

[0013] According to one embodiment of the present invention, the fixed frequency is 6000Hz.

[0014] According to one embodiment of the present invention, when the frequency converter is controlled by synchronous frequency modulation, the carrier frequency of the frequency converter changes with the operating frequency of the motor.

[0015] According to one embodiment of the present invention, obtaining the output voltage of the frequency converter includes: obtaining the three-phase voltage of the motor; calculating the effective value of the voltage based on the three-phase voltage as the output voltage.

[0016] According to one embodiment of the present invention, obtaining the output voltage of a frequency converter includes: obtaining the three-phase current of a motor; performing coordinate transformation on the three-phase current to obtain the d-axis voltage and q-axis voltage in a two-phase rotating coordinate system; and calculating the effective value of the voltage based on the d-axis voltage and q-axis voltage as the output voltage.

[0017] To achieve the above objectives, a second aspect of the present invention provides a computer-readable storage medium storing a motor control program thereon, which, when executed by a processor, implements the above-described motor control method.

[0018] According to the computer-readable storage medium of the present invention, based on the above-described motor control method, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0019] To achieve the above objectives, a third aspect of the present invention provides a motor controller, including a memory, a processor, and a motor control program stored in the memory and executable on the processor. When the processor executes the motor control program, it implements the above-described motor control method.

[0020] According to the motor controller of the present invention, based on the above-described motor control method, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0021] To achieve the above objectives, a fourth aspect of the present invention provides a motor control device, comprising: an acquisition module for acquiring the output voltage of a frequency converter; a determination module for determining the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage; and a control module for controlling the frequency converter according to the determined modulation mode and frequency modulation mode to control the operation of the motor.

[0022] According to an embodiment of the present invention, the motor control device acquires the output voltage of the frequency converter through an acquisition module, determines the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage through a determination module, and controls the frequency converter according to the determined modulation mode and frequency modulation mode to control the motor operation. This device determines the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage of the frequency converter, ensuring effective motor control and easily meeting the heat dissipation requirements of the frequency converter.

[0023] To achieve the above objectives, a fifth aspect of the present invention provides a magnetic levitation compressor unit, comprising: a compressor; and the aforementioned motor controller or motor control device for controlling the compressor.

[0024] According to the magnetic levitation compressor unit of the present invention, based on the above-mentioned motor controller or motor control device, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] Figure 1 This is a flowchart of a motor control method according to an embodiment of the present invention;

[0027] Figure 2 A circuit topology diagram of a frequency converter and a motor according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a basic vector space according to an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of a five-segment SPWM wave in sector I according to an embodiment of the present invention;

[0030] Figure 5 This is a schematic diagram of a seven-segment SPWM wave in sector I according to an embodiment of the present invention;

[0031] Figure 6 A flowchart of a motor control method according to a specific embodiment of the present invention;

[0032] Figure 7 This is a block diagram of a motor controller according to an embodiment of the present invention;

[0033] Figure 8 This is a block diagram of a motor control device according to an embodiment of the present invention;

[0034] Figure 9 This is a block diagram of a magnetic levitation compressor unit according to an embodiment of the present invention. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] The following description, with reference to the accompanying drawings, outlines an embodiment of the present invention, including a motor control method, a computer-readable storage medium, a motor controller, a motor control device, and a magnetic levitation compressor unit.

[0037] Figure 1 This is a flowchart of a motor control method according to an embodiment of the present invention.

[0038] like Figure 2 As shown, motor 1 is driven by frequency converter 2. The DC bus power is converted into three-phase AC power under PWM (Pulse Width Modulation) control by frequency converter 2, and the output three-phase AC power drives motor 1.

[0039] Specifically, in this embodiment, the inverter 2 uses IGBTs as switching devices to form a three-phase inverter bridge. The three-phase inverter bridge consists of three arms. In the figure, U1, U2, V1, V2, W1, and W2 are the drive signals controlling the six IGBTs. IGBTs controlled by U1 and U2 form one phase arm, IGBTs controlled by V1 and V2 form another phase arm, and IGBTs controlled by W1 and W2 form yet another phase arm. The on / off control signals of the upper and lower half-bridges on the same arm are opposite, and nodes A, B, and C are formed between two IGBTs on the same arm. Nodes A, B, and C are connected to the leads of the three-phase windings of motor 1. During the control process, the PWM signal input to the IGBT control terminal of the inverter controls the on / off state of the IGBTs, thereby causing nodes A, B, and C to output corresponding voltages Ua, Ub, and Uc to the three-phase windings of motor 1, driving motor 1 to run.

[0040] like Figure 1 As shown, the motor control method of this invention embodiment may include:

[0041] S1, obtain the output voltage of the frequency converter;

[0042] S2, determine the modulation method of the frequency converter and the frequency regulation method of the motor based on the output voltage;

[0043] S3 controls the frequency converter according to the determined modulation and frequency regulation methods to control the motor operation.

[0044] Specifically, the method first obtains the three-phase voltage output from the frequency converter and calculates the effective voltage value based on the three-phase voltage. The effective voltage value is then used as the output voltage of the frequency converter. Next, the effective voltage value output by the frequency converter is compared with the preset voltage. Based on the relationship between the current effective voltage value and the preset voltage, the corresponding motor control strategy is determined. Thus, this method determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage of the frequency converter. While ensuring the motor operation control effect, the switching frequency of the switching transistors in the frequency converter can be controlled by adjusting the modulation mode and the frequency regulation mode, thereby adjusting the heat generation of the frequency converter and easily meeting the temperature control requirements of the frequency converter.

[0045] It should be noted that the frequency converter has various modulation methods, including PAM (Pulse Amplitude Modulation), PWM, SPWM (Sinusoidal Pulse Width Modulation), and SVPWM (Space Vector Pulse Width Modulation). The motor's frequency regulation methods include synchronous frequency regulation and asynchronous frequency regulation. The specific settings can be configured according to the actual situation.

[0046] In one embodiment of the present invention, determining the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage includes: when the output voltage is less than or equal to a preset voltage threshold, determining the modulation mode as a seven-segment modulation mode and the frequency modulation mode as an asynchronous frequency modulation mode; when the output voltage is greater than the preset voltage threshold, determining the modulation mode as a five-segment modulation mode and the frequency modulation mode as a synchronous frequency modulation mode. The preset voltage threshold can be set according to actual conditions; for example, in one embodiment of the present invention, the preset voltage threshold is 250V. The range of the preset voltage threshold can be set to [220V, 260V].

[0047] Specifically, taking the SVPWM modulation method as an example, the inverter topology is as follows: Figure 2As shown, the switching states of the three-phase upper bridge arm are defined as U1, V1, and W1, and the lower bridge arm and upper bridge arm form complementary switching states with dead zones: U1_, V1_, and W1_. The upper bridge arm is defined as state "1" when it is on and state "0" when it is off, forming eight space voltage vectors. Six of these are non-zero space voltage vectors: U4(100), U6(110), U2(1010), U3(011), U1(001), and U5(101), and two are zero vectors: U0(000) and U7(111). It can be understood that the inverter does not output energy when the zero vector is in operation. The six basic vectors form the basic vector space, which is divided into... Figure 3 The six sectors shown are sectors I, II, III, IV, V, and VI. Taking sector I as an example, the voltage vector within each switching cycle can be synthesized from the basic vector and zero vector on both sides of this sector. The goal of SVPWM control is to make the synthesized reference voltage vector rotate in a circle according to a set amplitude by controlling the combination of switching states. Taking sector I as an example, when using a five-segment modulation method, such as... Figure 4 As shown, the vector action sequence is U0-U4-U6-U4-U0, where U4 and U6 are the basic voltage vectors of sector I, and U0 is the zero vector. During this process, W1 = 0, so the corresponding bridge arm remains unchanged, meaning the control signals of W1 and W2 remain unchanged, and the corresponding IGBT remains unchanged. When a seven-segment modulation method is used, the vector action sequence is as follows: Figure 5 The diagram shows U0-U4-U6-U7-U7-U6-U4-U0. During this process, the switching transistors of each phase arm need to be controlled.

[0048] Furthermore, the PWM signal uses a sawtooth or triangular wave as the carrier wave, which is compared with the desired waveform, the modulation wave, to generate the required PWM signal. In the PWM control circuit, the ratio of the carrier frequency fc to the modulation wave frequency fr is called the carrier ratio. Depending on whether the carrier and modulation wave are synchronized, it is divided into synchronous modulation and asynchronous modulation. When asynchronous modulation is used, the carrier frequency fc remains constant, while the modulation wave frequency fr changes, thus changing the carrier ratio. When synchronous modulation is used, the carrier and modulation wave are controlled in phase and frequency, and the carrier ratio is a fixed constant. Therefore, the number of carrier waves in the modulation wave within each cycle is fixed, and consequently, the number of pulses within each cycle is also fixed.

[0049] Based on the aforementioned seven-segment and five-segment modulation methods, as well as synchronous and asynchronous frequency modulation methods, this application determines the modulation method of the frequency converter and the frequency modulation method of the motor according to the output voltage as follows:

[0050] When the inverter's output voltage is less than or equal to a preset voltage threshold, a seven-segment modulation method is adopted, ensuring that the IGBT switches only once per phase per PWM cycle. This offers advantages such as low harmonic current and a good sinusoidal current output. Simultaneously, asynchronous frequency modulation is employed. In one embodiment of this application, when controlling the inverter using asynchronous frequency modulation, the inverter's carrier frequency is a fixed frequency, which can be set according to actual conditions, for example, a fixed frequency of 6000Hz. During this frequency modulation process, while changing the modulation wave frequency fr, the carrier frequency fc remains constant, causing the carrier ratio to continuously change. This allows the inverter to select a lower carrier frequency fc when operating at low frequencies, thereby reducing IGBT switching losses. Therefore, when the output voltage is less than or equal to the preset voltage threshold, asynchronous frequency modulation and seven-segment modulation are used to reduce switching losses and harmonic current through a low carrier frequency, ensuring a good output waveform.

[0051] When the inverter's output voltage exceeds a preset voltage threshold, a five-segment modulation method is employed. This ensures that the IGBT switching state of one phase bridge arm remains unchanged within each PWM cycle. Compared to the seven-segment modulation method, the switching frequency is reduced by one-third, thereby reducing power switching losses and significantly decreasing the inverter's heat generation, which helps reduce switching damage to the switching transistors. Simultaneously, when the inverter's output voltage exceeds the preset voltage threshold, a synchronous frequency modulation method is used. In one embodiment of this application, when controlling the inverter using synchronous frequency modulation, the inverter's carrier frequency changes in accordance with the motor's operating frequency. That is, while changing the modulation wave frequency fr, the carrier frequency fc is changed proportionally to maintain a constant carrier ratio. Due to the waveform symmetry, even-order harmonic problems are avoided. Therefore, when the output voltage exceeds the preset voltage threshold, synchronous frequency modulation and five-segment modulation are used. Five-segment modulation reduces the number of switching cycles of the switching transistors in each modulation cycle, reducing losses and inverter heat generation. Simultaneously, the carrier frequency increases with the modulation wave frequency, ensuring effective control.

[0052] In one embodiment of the present invention, obtaining the output voltage of the frequency converter includes: obtaining the three-phase voltage of the motor; and calculating the effective value of the voltage based on the three-phase voltage as the output voltage.

[0053] In other words, the three-phase voltages Ua, Ub, and Uc output from the frequency converter can be directly obtained. Then, the effective voltage value can be determined based on the maximum value of Ua, Ub, and Uc, and used as the output voltage. Alternatively, calculation methods such as arithmetic average or rectified average can be used to determine the output voltage based on Ua, Ub, and Uc. Another approach is to transform the three-phase voltages Ua, Ub, and Uc to a two-phase stationary coordinate system, and then determine the output voltage based on the α-axis voltage Uc in the two-phase stationary coordinate system. α and β-axis voltage Uβ The effective value of the voltage is determined. The specific method can be selected based on the actual situation.

[0054] In another embodiment of the present invention, obtaining the output voltage of the frequency converter includes: obtaining the three-phase current of the motor; performing coordinate transformation on the three-phase current to obtain the d-axis voltage and q-axis voltage in a two-phase rotating coordinate system; and calculating the effective value of the voltage based on the d-axis voltage and q-axis voltage as the output voltage.

[0055] In other words, the three-phase currents Ia, Ib, and Ic output from the frequency converter are first transformed using coordinate transformation to obtain the d-axis current Id and the q-axis current Iq. Then, the effective value of the output voltage Us is calculated based on Id and Iq. The calculation formula is as follows:

[0056] Ud=-ω*Lq*Iq+Rs*Id

[0057] Uq=ω*Ld*Id+Ke*ω+Rs*Iq

[0058] Us = sqrt(Ud*Ud + Uq*Uq)

[0059] Where Ud is the d-axis voltage, Uq is the q-axis voltage, Id is the d-axis current, Iq is the q-axis current, Ld is the d-axis inductance, Lq is the q-axis inductance, Rs is the stator resistance, ω is the rotor angular frequency, and Ke is the back electromotive force coefficient.

[0060] As a specific embodiment of this application, such as Figure 6 As shown, the motor control method may include the following steps:

[0061] S101, obtain the three-phase current of the motor.

[0062] S102 performs coordinate transformation on the three-phase current to obtain the d-axis current and q-axis current in a two-phase rotating coordinate system.

[0063] S103 calculates the effective value of the voltage based on the d-axis current and q-axis current, and uses it as the output voltage of the frequency converter.

[0064] S104. Determine whether the output voltage is less than or equal to a preset voltage threshold. If yes, proceed to step S105; otherwise, proceed to step S106.

[0065] S105, determine the modulation method as seven-band modulation and the frequency modulation method as asynchronous frequency modulation.

[0066] S106, determine the modulation method as five-band modulation and the frequency modulation method as synchronous frequency modulation.

[0067] In summary, the motor control method according to embodiments of the present invention first obtains the output voltage of the frequency converter, then determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage, and controls the frequency converter according to the determined modulation mode and frequency regulation mode to control the motor operation. This method determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage of the frequency converter, ensuring the motor control effect and easily meeting the heat dissipation requirements of the frequency converter.

[0068] Corresponding to the above embodiments, the present invention also proposes a computer-readable storage medium.

[0069] The computer-readable storage medium of this invention stores a motor control program thereon, which, when executed by a processor, implements the motor control method described above.

[0070] According to the computer-readable storage medium of the present invention, based on the above-described motor control method, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0071] Corresponding to the above embodiments, the present invention also proposes a motor controller.

[0072] like Figure 7 As shown, the motor controller 100 of this embodiment may include a memory 110, a processor 120, and a motor control program stored in the memory 110 and run on the processor 120. When the processor 120 executes the motor control program, it implements the above-described motor control method.

[0073] According to the motor controller of the present invention, based on the above-described motor control method, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0074] Corresponding to the above embodiments, the present invention also proposes a motor control device.

[0075] like Figure 8 As shown, the motor control device of this embodiment may include an acquisition module 10, a determination module 20, and a control module 30.

[0076] The acquisition module 10 acquires the output voltage of the frequency converter. The determination module 20 determines the modulation method of the frequency converter and the frequency regulation method of the motor based on the output voltage. The control module 30 controls the frequency converter according to the determined modulation method and frequency regulation method to control the motor operation.

[0077] According to one embodiment of the present invention, the determining module 20 determines the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage, specifically used for: when the output voltage is less than or equal to a preset voltage threshold, determining the modulation mode as a seven-segment modulation mode and determining the frequency regulation mode as an asynchronous frequency regulation mode; when the output voltage is greater than the preset voltage threshold, determining the modulation mode as a five-segment modulation mode and determining the frequency regulation mode as a synchronous frequency regulation mode.

[0078] According to one embodiment of the present invention, when the control module 30 controls the frequency converter using asynchronous frequency modulation, the carrier frequency of the frequency converter is a fixed frequency.

[0079] According to one embodiment of the present invention, the fixed frequency is 6000Hz.

[0080] According to one embodiment of the present invention, when the control module 30 controls the frequency converter using synchronous frequency modulation, the carrier frequency of the frequency converter changes with the operating frequency of the motor.

[0081] According to one embodiment of the present invention, the acquisition module 10 acquires the output voltage of the frequency converter, specifically for: acquiring the three-phase voltage of the motor; and calculating the effective value of the voltage based on the three-phase voltage as the output voltage.

[0082] According to another embodiment of the present invention, the acquisition module 10 acquires the output voltage of the frequency converter, specifically for: acquiring the three-phase current of the motor; performing coordinate transformation on the three-phase current to obtain the d-axis current and q-axis current in a two-phase rotating coordinate system; and calculating the effective value of the voltage based on the d-axis current and q-axis current as the output voltage.

[0083] It should be noted that for details not disclosed in the motor control device of the present invention, please refer to the details disclosed in the motor control method of the above embodiments of the present invention, which will not be repeated here.

[0084] According to an embodiment of the present invention, the motor control device acquires the output voltage of the frequency converter through an acquisition module, determines the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage through a determination module, and controls the frequency converter according to the determined modulation mode and frequency modulation mode to control the motor operation. This device determines the modulation mode of the frequency converter and the frequency modulation mode of the motor based on the output voltage of the frequency converter, ensuring effective motor control and easily meeting the heat dissipation requirements of the frequency converter.

[0085] Corresponding to the above embodiments, the present invention also proposes a magnetic levitation compressor unit.

[0086] like Figure 9 As shown, the magnetic levitation compressor unit 200 of this embodiment includes: a compressor 210; and the aforementioned motor controller 100 or the aforementioned motor control device, used to control the compressor.

[0087] According to the magnetic levitation compressor unit of the present invention, based on the above-mentioned motor controller or motor control device, the modulation mode of the frequency converter and the frequency regulation mode of the motor are determined according to the output voltage of the frequency converter, which ensures the motor control effect and easily meets the heat dissipation requirements of the frequency converter.

[0088] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0089] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0090] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0092] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0093] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A motor control method, characterized in that, The motor is driven by a frequency converter, and the method includes: Obtain the output voltage of the frequency converter; The modulation method of the frequency converter and the frequency regulation method of the motor are determined based on the output voltage; The frequency converter is controlled according to the determined modulation and frequency modulation methods to control the operation of the motor; Determining the modulation method of the frequency converter and the frequency regulation method of the motor based on the output voltage includes: When the output voltage is less than or equal to a preset voltage threshold, the modulation method is determined to be a seven-segment modulation method, and the frequency modulation method is determined to be an asynchronous frequency modulation method. When the output voltage is greater than the preset voltage threshold, the modulation method is determined to be a five-segment modulation method, and the frequency modulation method is determined to be a synchronous frequency modulation method; When the frequency converter is controlled using the synchronous frequency modulation method, the carrier frequency of the frequency converter changes in accordance with the operating frequency of the motor.

2. The method according to claim 1, characterized in that, When the frequency converter is controlled using the asynchronous frequency modulation method, the carrier frequency of the frequency converter is a fixed frequency.

3. The method according to claim 2, characterized in that, The fixed frequency is 6000Hz.

4. The method according to any one of claims 1-3, characterized in that, Obtaining the output voltage of the frequency converter includes: Obtain the three-phase voltage of the motor; The effective value of the voltage is calculated based on the three-phase voltage and used as the output voltage.

5. The method according to any one of claims 1-3, characterized in that, Obtaining the output voltage of the frequency converter includes: Obtain the three-phase current of the motor; The three-phase currents are transformed to obtain the d-axis current and q-axis current in a two-phase rotating coordinate system. The effective value of the voltage is calculated based on the d-axis current and the q-axis current, and is used as the output voltage.

6. A computer-readable storage medium, characterized in that, It stores a motor control program, which, when executed by a processor, implements the motor control method according to any one of claims 1-5.

7. A motor controller, characterized in that, It includes a memory, a processor, and a motor control program stored in the memory and executable on the processor. When the processor executes the motor control program, it implements the motor control method according to any one of claims 1-5.

8. A motor control device for implementing the motor control method according to any one of claims 1-5, characterized in that, include: The acquisition module is used to acquire the output voltage of the frequency converter; The determining module is used to determine the modulation mode of the frequency converter and the frequency regulation mode of the motor based on the output voltage; The control module is used to control the frequency converter according to the determined modulation and frequency modulation methods in order to control the operation of the motor.

9. A magnetic levitation compressor unit, characterized in that, include: compressor; The motor controller according to claim 7 or the motor control device according to claim 8 is used to control the compressor.

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