Electric compressor harmonic injection method and device and electric compressor

Abstract

The invention discloses an electric compressor harmonic injection method and device and an electric compressor. The method comprises the following steps: acquiring a three-phase voltage waveform of a to-be-tested motor; converting the three-phase voltage waveform into an alpha / beta two-phase waveform based on Clark transformation; obtaining a corresponding alpha fundamental wave, each harmonic wave and respective amplitude and phase through Fourier transform; obtaining a first phase output voltage and a second phase output voltage; and increasing at least one harmonic component randomly selected from each harmonic to the first phase output voltage and the second phase output voltage, updating the first phase output voltage and the second phase output voltage, and inputting the updated voltage to the to-be-tested motor. According to the embodiment of the invention, after the three-phase voltage waveform of the to-be-tested motor is obtained, the corresponding alpha fundamental wave and each harmonic wave are extracted through the Clark transform and the Fourier transform in sequence; and at least one harmonic component randomly selected from each harmonic is increased to the first-phase output voltage and the second-phase output voltage so as to adjust the output voltage and then output the output voltage to the motor to be tested, so that the torque ripple of the motor can be reduced, and the NVH effect of the compressor can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric compression control, and particularly to a harmonic injection method and device for an electric compressor and an electric compressor. Background Art

[0002] As an important component of an electric vehicle, the motor in an electric compressor is also developing towards high power and high torque. The greater the torque of the motor in the electric compressor, the greater the vibration and noise generated. Currently, the common treatment method is to directly reduce the phase current harmonics of the motor through software closed-loop control. However, due to cost considerations, the magnetic field distribution of the compressor motor is often not sinusoidal, and there are large harmonics in itself. Coupled with the fundamental component of the phase current, large harmonics are still generated, affecting the NVH performance of the compressor. Summary of the Invention

[0003] Embodiments of the present invention provide a harmonic injection method and device for an electric compressor and an electric compressor, aiming to solve the problem in the prior art that the compressor motor reduces the phase current harmonics through software closed-loop control. Due to cost considerations, its magnetic field distribution is often not sinusoidal, and there are large harmonics in itself. Coupled with the fundamental component of the phase current, large harmonics are still generated, affecting the NVH performance of the compressor.

[0004] In a first aspect, an embodiment of the present invention provides a harmonic injection method for an electric compressor, which includes: When the original machine drives the motor to be tested in the electric compressor to be tested, collect and obtain the three-phase voltage waveforms of the motor to be tested; Convert the three-phase voltage waveforms into α / β two-phase waveforms based on the Clarke transformation; Obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveforms through Fourier transform, and obtain the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics; where, there are multiple harmonic components in each harmonic, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0; Obtain the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor to be tested; Add at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage; Add at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage; Input the first-phase output voltage and the second-phase output voltage into the motor to be tested.

[0005] In a second aspect, an embodiment of the present invention further provides a harmonic injection device for an electric compressor, which includes: A three-phase voltage waveform acquisition unit, configured to acquire the three-phase voltage waveforms of the motor under test when the original machine drives the motor under test in the electric compressor to be tested; A Clarke transformation unit, configured to transform the three-phase voltage waveforms into α / β two-phase waveforms based on Clarke transformation; A Fourier transformation unit, configured to obtain an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveforms through Fourier transformation, and obtain the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics; wherein, the harmonics include a plurality of harmonic components, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0; An output voltage acquisition unit, configured to acquire a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor under test; A first harmonic injection unit, configured to increase at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage; A second harmonic injection unit, configured to increase at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage; A voltage output unit, configured to input the first-phase output voltage and the second-phase output voltage to the motor under test.

[0006] In a third aspect, an embodiment of the present invention further provides an electric compressor, which includes a memory and a processor, a computer program is stored on the memory, and when the processor executes the computer program, the method described in the first aspect above is implemented.

[0007] The embodiments of the present invention provide a method and device for harmonic injection of an electric compressor and the electric compressor. The method includes: when the original machine drives a to-be-tested motor in the to-be-tested electric compressor, collecting the three-phase voltage waveforms of the to-be-tested motor; converting the three-phase voltage waveforms into α / β two-phase waveforms based on the Clarke transformation; obtaining the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveforms through Fourier transform, and obtaining the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics; wherein, the each harmonic includes a plurality of harmonic components, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0; obtaining the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the to-be-tested motor; adding at least one harmonic component arbitrarily selected from the each harmonic to the first-phase output voltage to update the first-phase output voltage; adding at least one harmonic component arbitrarily selected from the each harmonic to the second-phase output voltage to update the second-phase output voltage; inputting the first-phase output voltage and the second-phase output voltage into the to-be-tested motor. The embodiments of the present invention can sequentially extract the corresponding α fundamental wave and each harmonic through Clarke transformation and Fourier transform after obtaining the three-phase voltage waveforms of the to-be-tested motor, and add at least one harmonic component arbitrarily selected from the each harmonic to the first-phase output voltage and the second-phase output voltage to adjust the output voltage and then output to the to-be-tested motor, which can reduce its torque ripple and improve the effect of compressor NVH. Description of the Drawings

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0009] Figure 1 It is a schematic flow chart of the method for harmonic injection of an electric compressor provided by the embodiments of the present invention; Figure 2 It is a schematic application scenario diagram of the method for harmonic injection of an electric compressor provided by the embodiments of the present invention; Figure 3 It is a schematic sub-flow chart of the method for harmonic injection of an electric compressor provided by the embodiments of the present invention; Figure 4 It is a schematic sub-flow chart of the method for harmonic injection of an electric compressor provided by the embodiments of the present invention; Figure 5 It is a schematic sub-flow chart of the method for harmonic injection of an electric compressor provided by the embodiments of the present invention; Figure 6Schematic block diagram of the harmonic injection device for an electric compressor provided by an embodiment of the present invention. Detailed implementation manners

[0010] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0011] It should be understood that when used in this specification and the appended claims, the terms "comprises" and "comprising" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0012] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in this specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0013] It should be further understood that the term " / and / " used in this specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0014] Please refer to Figure 1 , which is a schematic flow chart of the harmonic injection method for an electric compressor provided by an embodiment of the present invention. As Figure 1 shown, the harmonic injection method for the electric compressor includes steps S110 to S170.

[0015] S110. When the original machine drives the motor to be tested in the electric compressor to be tested, collect and obtain the three-phase voltage waveforms of the motor to be tested.

[0016] In this embodiment, the harmonic injection method of the electric compressor of the present application is applied to the controller of the motor to be tested (more specifically, it can be understood as the control algorithm module of the controller), and the motor control circuit specifically applied to the motor to be tested is specifically as Figure 2As shown, the motor control loop at least includes an electric compressor 10 (where the motor used is a permanent magnet synchronous motor, i.e., Permanent Magnet Synchronous Motor, abbreviated as PMSM), a space vector pulse width modulation generator 20, and a voltage source inverter 30; the space vector pulse width modulation generator 20 is connected to the voltage source inverter 30, and the voltage source inverter 30 is connected to the electric compressor 10 (specifically, connected to the permanent magnet synchronous motor in the electric compressor 10). Moreover, the voltage source inverter 30 can also be connected to a DC bus (i.e., DC BUS) to connect a DC power supply and convert it into alternating current.

[0017] In the early test stage of the electric compressor, in order to obtain a more appropriate harmonic injection method, the permanent magnet synchronous motor in the electric compressor can be used as the motor under test and connected to the original machine (which can be understood as the prime mover and can provide a stable speed). More specifically, the three phases of the permanent magnet synchronous motor, namely the U phase, V phase, and W phase, are respectively connected to the corresponding three phases (also the U phase, V phase, and W phase) of the original machine through a plug-in resistor (such as a resistance value of 120K), so as to facilitate the measurement of the back electromotive force of the permanent magnet synchronous motor and obtain the back electromotive force waveform data of the permanent magnet synchronous motor.

[0018] S120. Based on the Clarke transformation, convert the three-phase voltage waveform into an α / β two-phase waveform.

[0019] In this embodiment, when the three-phase voltage waveform of the motor under test is determined by the above method, corresponding to the three-phase system (which can be regarded as the abc coordinate system), its time-domain components can be transformed and corresponding to the two components of α and β in the orthogonal stationary coordinate system. Specifically, the three-phase voltage waveform can be converted into an α / β two-phase waveform through the Clarke transformation.

[0020] Among them, since it is known that the phases in the three-phase system differ by 120° in sequence and the αβ coordinate system corresponding to the orthogonal stationary coordinate system is an orthogonal coordinate system, after overlapping the α axis in the αβ coordinate system with the a axis in the abc coordinate system of the three-phase system, the Clarke transformation can be used to convert the three-phase voltage waveform into an α / β two-phase waveform.

[0021] In one embodiment, as Figure 3 shown, step S120 includes: S121. Obtain the base transformation matrix corresponding to the Clarke transformation; S122. Transform the three-phase voltage waveform according to the base transformation matrix to obtain the corresponding α / β two-phase waveform.

[0022] In this embodiment, when the initial base transformation matrix in the Clarke transformation is specifically represented by T, it is specifically as follows: ; After knowing the base transformation matrix corresponding to the Clarke transformation, after multiplying the above base transformation matrix by the vector (ia, ib, ic) composed of the current values corresponding to the three-phase voltage values at any time point in the three-phase voltage waveform, it can be correspondingly converted into a vector (iα, iβ) corresponding to the αβ coordinate system. Combining Kirchhoff's current law, it is known that the sum of all currents entering a certain node is equal to the sum of all currents leaving this node. When the three-phase currents corresponding to the motor under test are ia, ib, and ic respectively, then ia + ib + ic = 0. And because it is necessary to satisfy And the α-axis in the αβ coordinate system overlaps with the a-axis in the abc coordinate system of the three-phase system. Therefore, combining the initial base transformation matrix and the above conditions to be satisfied, it can be known that: ; Through the above transformation method, the conversion of the three-phase voltage waveform into an α / β two-phase waveform is realized.

[0023] S130. Obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics.

[0024] Among them, there are multiple harmonic components in each harmonic, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0.

[0025] In this embodiment, when using Fourier transform to obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform, it is considered that any periodic signal (or a finite-duration segment of a non-periodic signal) can be decomposed into the superposition of sine / cosine components with different frequencies. Specifically, it can be sampled over a full period (the number of sampling points N is an integer multiple of the period of the α fundamental wave) to avoid spectral leakage. Of course, when using Fourier transform to obtain the β fundamental wave corresponding to the α / β two-phase waveform, it also has an initial phase, and the initial phase of the β fundamental wave is obtained with reference to the phase of the α fundamental wave. That is, as long as Fourier transform is used to obtain the α fundamental wave corresponding to the α / β two-phase waveform and its phase is limited to 0, then the phase of the β fundamental wave can be measured.

[0026] Specifically in implementation, step S130 includes the following implementation methods: A1) Obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the α fundamental wave, the harmonics corresponding to the α fundamental wave, the β fundamental wave and the harmonics corresponding to the β fundamental wave; A2) Obtain the α fundamental wave, β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the α fundamental wave and each harmonic corresponding to the α fundamental wave. A3) Obtain the α fundamental wave, β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the β fundamental wave and each harmonic corresponding to the β fundamental wave.

[0027] Specifically, when processing the α / β two-phase waveform in combination with Fourier transform, it is necessary to perform discretization processing, Fourier calculation, and frequency resolution extraction in sequence. Finally, the α fundamental wave, β fundamental wave, and each harmonic can be obtained, and the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics can also be specifically obtained.

[0028] In one embodiment, step S130 includes: Obtain the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtain the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave as the respective harmonics.

[0029] Among them, each harmonic in the 2nd to 13th harmonics corresponds to a harmonic component.

[0030] In this embodiment, if high-order harmonics in the α / β two-phase waveform (i.e., harmonics with a multiple greater than 13 of the α fundamental wave) are used, the effect of injecting the input voltage of the motor under test is not good. It is necessary to select the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave as the respective harmonics, and each harmonic in the 2nd to 13th harmonics corresponds to a harmonic component.

[0031] Specifically, obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave as the respective harmonics includes the following implementation methods: B1) Obtain the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtain the 2nd to 13th harmonics corresponding to the α fundamental wave and the β fundamental wave respectively as the respective harmonics; B2) Obtain the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtain the 2nd to 13th harmonics corresponding to the α fundamental wave as the respective harmonics; B3) Obtain the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtain the 2nd to 13th harmonics corresponding to the β fundamental wave as the respective harmonics.

[0032] However, no matter which of the above methods is used to obtain the respective harmonics, they can all be injected into the first-phase output voltage and the second-phase output voltage.

[0033] S140. Obtain the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor under test.

[0034] In this embodiment, when specifically performing harmonic injection on the motor under test later to reduce torque ripple and improve the NVH (the full name of NVH is Noise, Vibration, Harshness, representing noise, vibration, and harshness) of the compressor, it is first necessary to obtain the first-phase output voltage and the second-phase output voltage input to the motor control loop at this time, and then perform harmonic injection processing on the above two input voltages respectively.

[0035] S150. Increase at least one harmonic component arbitrarily selected from the respective harmonics to the first-phase output voltage to update the first-phase output voltage.

[0036] In this embodiment, when performing harmonic injection on the input voltage, harmonic injection is required for both of the above two input voltages. At this time, the specific process can be described by taking the harmonic injection of the first-phase output voltage as an example. There are at least two harmonic injection methods, that is, arbitrarily selecting one harmonic component from the respective harmonics and increasing it to the first-phase output voltage, or arbitrarily selecting multiple harmonic components from the respective harmonics and increasing them to the first-phase output voltage, and the following will be described in detail in combination with specific embodiments.

[0037] In one embodiment, as the first embodiment of step S150, as Figure 4 shown, step S150 includes: S151A. Arbitrarily select one harmonic component from the 2nd to 13th harmonics included in the respective harmonics as the candidate harmonic component; S152A. Obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset first adjustment coefficient and a first offset angle; S153A. Superimpose a first adjustment amplitude on the amplitude of the first-phase output voltage and superimpose a first adjustment phase on the phase of the first-phase output voltage to update the first-phase output voltage; where the first adjustment amplitude = the first adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic amplitude of the candidate harmonic component + the first offset angle.

[0038] In this embodiment, when arbitrarily selecting one harmonic component from the various harmonics and adding it to the output voltage of the first phase, one harmonic component can be arbitrarily selected from the 2nd to 13th harmonics included in the various harmonics as a candidate harmonic component. For example, any one of the 2nd harmonic, 3rd harmonic, 4th harmonic, 5th harmonic, 6th harmonic, 7th harmonic, 8th harmonic, 9th harmonic, 10th harmonic, 11th harmonic, 12th harmonic, and 13th harmonic can be selected as the candidate harmonic component. Then, obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset first adjustment coefficient and a first offset angle. Finally, combine the first adjustment amplitude = the first adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic amplitude of the candidate harmonic component + the first offset angle. It should be noted that the rotational speed of the motor under test can also be regarded as the same as that of the original machine (however, after the motor under test is no longer in the test stage but in the actual application stage, the motor under test no longer needs to be connected to the original machine, and at this time, the rotational speed of the motor under test is its actual rotational speed). By the above method of injecting harmonics into the output voltage, the torque ripple can be reduced and the effect of improving the compressor NVH can be achieved.

[0039] In one embodiment, as the second embodiment of step S150, as Figure 5 shown, step S150 includes: S151B. Arbitrarily select multiple harmonic components from the 2nd to 13th harmonics included in the various harmonics as a candidate harmonic component set; S152B. Obtain the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtain a preset second adjustment coefficient and a second offset angle; S153B. Superimpose the second adjustment amplitude on the amplitude of the output voltage of the first phase and superimpose the second adjustment phase on the phase of the output voltage of the first phase to update the output voltage of the first phase; wherein, the second adjustment amplitude = the second adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the second adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the second offset angle.

[0040] In this embodiment, the difference from the first embodiment of step S150 is that multiple harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in the various harmonics as a candidate harmonic component set, and then the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set are respectively superimposed on the amplitude and phase of the output voltage of the first phase. Among them, the second adjustment coefficient can be set to be equal to the first adjustment system, and the second offset angle can be set to be equal to the first offset angle.

[0041] S160. Increase at least one harmonic component arbitrarily selected from the respective harmonics to the second-phase output voltage to update the second-phase output voltage.

[0042] In this embodiment, for harmonic injection into the second-phase output voltage, the specific process of harmonic injection into the second-phase output voltage can also be referred to. There are at least two harmonic injection methods, that is, arbitrarily select one harmonic component from the respective harmonics and increase it to the second-phase output voltage, or arbitrarily select multiple harmonic components from the respective harmonics and increase them to the second-phase output voltage, and the following will be described in detail in combination with specific embodiments.

[0043] In one embodiment, as the first embodiment of step S160, step S160 includes: Arbitrarily select one harmonic component from the 2nd to 13th harmonics included in the respective harmonics as the candidate harmonic component; Obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset third adjustment coefficient and a third offset angle; Superimpose a third adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a third adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the third adjustment amplitude = the third adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic amplitude of the candidate harmonic component + the third offset angle.

[0044] In this embodiment, when arbitrarily selecting one harmonic component from the respective harmonics and increasing it to the second-phase output voltage, one harmonic component can be arbitrarily selected from the 2nd to 13th harmonics included in the respective harmonics as the candidate harmonic component first, then obtain the harmonic amplitude and harmonic phase of this candidate harmonic component, and obtain a preset third adjustment coefficient and a third offset angle. Finally, in combination with the third adjustment amplitude = the third adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic amplitude of the candidate harmonic component + the third offset angle, it should be noted that the rotational speed of the motor under test can also be regarded as the same as the rotational speed of the original machine (however, after the motor under test is no longer in the test stage but in the actual application stage, the motor under test no longer needs to be connected to the original machine, and at this time, the rotational speed of the motor under test is its actual rotational speed). Among them, the third adjustment coefficient can be set to be equal to the first adjustment system, and the third offset angle can be set to be equal to the first offset angle. By the above method of injecting harmonics into the output voltage, the torque ripple can also be reduced and the effect of improving the compressor NVH can be achieved.

[0045] In one embodiment, as the second embodiment of step S160, step S160 includes: Arbitrarily select multiple harmonic components from the 2nd to 13th harmonics included in each of the harmonics as a candidate harmonic component set; Obtain the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtain a preset fourth adjustment coefficient and a fourth offset angle; Superimpose a fourth adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a fourth adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the fourth adjustment amplitude = the fourth adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the fourth adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the fourth offset angle.

[0046] In this embodiment, the difference from the first embodiment of step S160 is that multiple harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in each of the harmonics as a candidate harmonic component set, and then the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set are respectively superimposed on the amplitude and phase of the second-phase output voltage. Among them, the fourth adjustment coefficient can be set to be equal to the first adjustment coefficient, and the fourth offset angle can be set to be equal to the first offset angle.

[0047] S170. Input the first-phase output voltage and the second-phase output voltage into the motor under test.

[0048] In this embodiment, when the first-phase output voltage and the second-phase output voltage are updated in combination with harmonic injection processing and then input into the motor under test, it can make the motor rotate stably under the power supply of the first-phase output voltage and the second-phase output voltage.

[0049] It can be seen that the embodiment of implementing this method can extract the corresponding α fundamental wave and each harmonic after Clark transformation and Fourier transformation in sequence after obtaining the three-phase voltage waveforms of the motor under test, and at least one harmonic component arbitrarily selected from each harmonic is added to the first-phase output voltage and the second-phase output voltage to adjust the output voltage and then output to the motor under test, which can reduce its torque ripple and improve the effect of compressor NVH.

[0050] Figure 6 It is a schematic block diagram of a harmonic injection device for an electric compressor provided by an embodiment of the present invention. As Figure 6As shown, corresponding to the above harmonic injection method for an electric compressor, the present invention further provides an electric compressor harmonic injection device 100. The electric compressor harmonic injection device 100 includes: a three-phase voltage waveform acquisition unit 110, a Clarke transformation unit 120, a Fourier transformation unit 130, an output voltage acquisition unit 140, a first harmonic injection unit 150, a second harmonic injection unit 160, and a voltage output unit 170.

[0051] The three-phase voltage waveform acquisition unit 110 is configured to acquire the three-phase voltage waveforms of the motor to be tested when the original machine drives the motor to be tested in the electric compressor to be tested.

[0052] In this embodiment, the harmonic injection method for the electric compressor of the present application is applied to the controller of the motor to be tested (more specifically, it can be understood as the control algorithm module of the controller), and the motor control loop specifically applied to the motor to be tested is specifically as Figure 2 shown. In this motor control loop, at least an electric compressor 10 (where the motor used is a permanent magnet synchronous motor, i.e., Permanent Magnet Synchronous Motor and abbreviated as PMSM), a space vector pulse width modulation generator 20, and a voltage source inverter 30 are included; the space vector pulse width modulation generator 20 is connected to the voltage source inverter 30, and the voltage source inverter 30 is connected to the electric compressor 10 (specifically, it is connected to the permanent magnet synchronous motor in the electric compressor 10). Moreover, the voltage source inverter 30 can also be connected to a DC bus (i.e., DC BUS) for connecting a DC power supply and converting it into alternating current.

[0053] In order to obtain a more suitable harmonic injection method in the preliminary test stage of the electric compressor, the permanent magnet synchronous motor in the electric compressor can be first connected to the original machine (which can be understood as a prime mover that can provide a stable speed) as the motor to be tested. More specifically, the U-phase, V-phase, and W-phase of the permanent magnet synchronous motor are respectively connected to the corresponding three phases (also U-phase, V-phase, and W-phase) of the original machine through a plug-in resistor (such as a resistance value of 120K, etc.), so as to facilitate the measurement of the back electromotive force of the permanent magnet synchronous motor and obtain the back electromotive force waveform data of the permanent magnet synchronous motor.

[0054] The Clarke transformation unit 120 is configured to convert the three-phase voltage waveforms into α / β two-phase waveforms based on the Clarke transformation.

[0055] In this embodiment, when the three-phase voltage waveforms of the motor to be tested are determined by the above method, corresponding to a three-phase system (which can be regarded as an abc coordinate system), its time-domain components can be transformed and correspond to the α and β two components in the orthogonal stationary coordinate system. Specifically, the three-phase voltage waveforms can be converted into α / β two-phase waveforms through the Clarke transformation.

[0056] Among them, since the phases in a known three-phase system differ by 120° in sequence and the αβ coordinate system corresponding to the orthogonal stationary coordinate system is an orthogonal coordinate system, after overlapping the α-axis in the αβ coordinate system with the a-axis in the abc coordinate system of the three-phase system, the Clark transform can be used to convert the three-phase voltage waveform into an α / β two-phase waveform.

[0057] In one embodiment, the Clark transform unit 120 is specifically configured to: Obtain a basis transformation matrix corresponding to the Clark transform; Transform the three-phase voltage waveform according to the basis transformation matrix to obtain the corresponding α / β two-phase waveform.

[0058] In this embodiment, when the initial basis transformation matrix in the Clark transform is specifically represented by T, it is as follows: ; After knowing the basis transformation matrix corresponding to the Clark transform, after multiplying the above basis transformation matrix by the vector (ia, ib, ic) composed of the current values corresponding to the three-phase voltage values at any time point in the three-phase voltage waveform, it can be correspondingly converted into a vector (iα, iβ) corresponding to the αβ coordinate system. Also, in combination with Kirchhoff's current law, it is known that the sum of all currents entering a certain node is equal to the sum of all currents leaving this node. When the three-phase currents corresponding to the motor to be measured are ia, ib, and ic respectively, then ia + ib + ic = 0. And because it is necessary to satisfy And the α-axis in the αβ coordinate system is overlapped with the a-axis in the abc coordinate system of the three-phase system, so in combination with the initial basis transformation matrix and the above conditions to be satisfied, it can be known that: ; Through the above transformation method, the conversion of the three-phase voltage waveform into an α / β two-phase waveform is realized.

[0059] The Fourier transform unit 130 is configured to obtain an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics.

[0060] Among them, there are multiple harmonic components in each harmonic, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0.

[0061] In this embodiment, when using Fourier transform to obtain the fundamental α wave and each harmonic corresponding to the α / β two-phase waveform, it is considered that any periodic signal (or a finite-duration segment of an aperiodic signal) can be decomposed into a superposition of sine / cosine components with different frequencies. Specifically, integral-period sampling can be performed (the number of sampling points N is an integer multiple of the fundamental α wave period) to avoid spectral leakage. Of course, when using Fourier transform to obtain the fundamental β wave corresponding to the α / β two-phase waveform, it also has an initial phase, and the initial phase of the fundamental β wave is obtained with reference to the phase of the fundamental α wave.

[0062] Specifically in implementation, the following implementation manners are included in the Fourier transform unit 130: C1) Obtain the fundamental α wave, fundamental β wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the fundamental α wave, each harmonic corresponding to the fundamental α wave, the fundamental β wave, and each harmonic corresponding to the fundamental β wave; C2) Obtain the fundamental α wave, fundamental β wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the fundamental α wave and each harmonic corresponding to the fundamental α wave; C3) Obtain the fundamental α wave, fundamental β wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtain the amplitudes and phases of the fundamental β wave and each harmonic corresponding to the fundamental β wave.

[0063] Specifically, when processing the α / β two-phase waveform in combination with Fourier transform, discretization processing, Fourier calculation, and frequency resolution extraction need to be performed in sequence. Finally, the fundamental α wave, fundamental β wave, and each harmonic can be obtained, and the amplitudes and phases of the fundamental α wave and / or the fundamental β wave and the corresponding harmonics can also be specifically obtained.

[0064] In one embodiment, the Fourier transform unit 130 is specifically configured to: Obtain the fundamental α wave and fundamental β wave corresponding to the α / β two-phase waveform through Fourier transform, and obtain the 2nd to 13th harmonics corresponding to the fundamental α wave and / or the fundamental β wave as the each harmonic.

[0065] Among them, each harmonic in the 2nd to 13th harmonics corresponds to a harmonic component.

[0066] In this embodiment, if the effect of injecting the high-order harmonics (i.e., the harmonics whose multiple of the fundamental α wave is greater than 13) in the α / β two-phase waveform into the input voltage of the motor to be measured is not good, it is necessary to select the 2nd to 13th harmonics corresponding to the fundamental α wave and / or the fundamental β wave as the each harmonic, and each harmonic in the 2nd to 13th harmonics corresponds to a harmonic component.

[0067] When the Fourier transform unit 130 is replaced by one that performs Fourier transform to obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform, and obtains the amplitudes and phases of the α fundamental wave, the β fundamental wave and each harmonic, in specific implementation, it can obtain the 2nd to 13th harmonics corresponding to the α fundamental wave and the 2nd to 13th harmonics corresponding to the β fundamental wave to form each harmonic.

[0068] Specifically, obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave as each harmonic includes the following implementation manners: D1) Obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the α fundamental wave and the β fundamental wave respectively as each harmonic; D2) Obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the α fundamental wave as each harmonic; D3) Obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the β fundamental wave as each harmonic.

[0069] However, no matter which of the above methods is used to obtain each harmonic, they can all be injected into the first-phase output voltage and the second-phase output voltage.

[0070] The output voltage acquisition unit 140 is configured to acquire the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor to be measured.

[0071] In this embodiment, when specifically performing harmonic injection on the motor to be measured later to achieve the effect of reducing torque ripple and improving the compressor NVH (the full name of NHV is Noise, Vibration, Harshness, representing noise, vibration and roughness), first, it is necessary to acquire the first-phase output voltage and the second-phase output voltage input to the motor control loop at this time, and then perform the processing of injecting harmonics on the above two input voltages respectively.

[0072] The first harmonic injection unit 150 is configured to increase at least one harmonic component arbitrarily selected from each harmonic to the first-phase output voltage to update the first-phase output voltage.

[0073] In this embodiment, when performing harmonic injection on the input voltage, harmonic injection needs to be performed on both of the above two input voltages. At this time, the specific process can be described by taking the harmonic injection of the first-phase output voltage as an example. There are at least two harmonic injection methods, that is, randomly selecting one harmonic component from each harmonic to increase to the first-phase output voltage, or randomly selecting multiple harmonic components from each harmonic to increase to the first-phase output voltage, and the following will be described in detail in combination with specific embodiments.

[0074] In one embodiment, as the first embodiment of the first harmonic injection unit 150, it is specifically used for: Randomly select one harmonic component from the 2nd to 13th harmonics included in each harmonic as the candidate harmonic component; Obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset first adjustment coefficient and a first offset angle; Superimpose a first adjustment amplitude on the amplitude of the first-phase output voltage and superimpose a first adjustment phase on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the first adjustment amplitude = the first adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic amplitude of the candidate harmonic component + the first offset angle.

[0075] In this embodiment, when randomly selecting one harmonic component from each harmonic to increase to the first-phase output voltage, one harmonic component can be randomly selected from the 2nd to 13th harmonics included in each harmonic as the candidate harmonic component, such as selecting any one of the 2nd harmonic, 3rd harmonic, 4th harmonic, 5th harmonic, 6th harmonic, 7th harmonic, 8th harmonic, 9th harmonic, 10th harmonic, 11th harmonic, 12th harmonic, and 13th harmonic as the candidate harmonic component. Then, obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset first adjustment coefficient and a first offset angle. Finally, combine the first adjustment amplitude = the first adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic amplitude of the candidate harmonic component + the first offset angle. It should be noted that the rotational speed of the motor under test can also be regarded as the same as the rotational speed of the original machine (however, after the motor under test is no longer in the test stage but in the actual application stage, the motor under test no longer needs to be connected to the original machine, and at this time, the rotational speed of the motor under test is its actual rotational speed). By the above method of injecting harmonics into the output voltage, the torque ripple can be reduced and the effect of improving the compressor NVH can be achieved.

[0076] In one embodiment, as the second embodiment of the first harmonic injection unit 150, the first harmonic injection unit 150 is specifically used for: Arbitrarily select multiple harmonic components from the 2nd to 13th harmonics included in each of the harmonics as a candidate harmonic component set; Obtain the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtain a preset second adjustment coefficient and a second offset angle; Superimpose a second adjustment amplitude on the amplitude of the first-phase output voltage and superimpose a second adjustment phase on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the second adjustment amplitude = the second adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the second adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the second offset angle.

[0077] In this embodiment, the difference from the first embodiment of the first harmonic injection unit is that multiple harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in each of the harmonics as a candidate harmonic component set, and then the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set are respectively superimposed on the amplitude and phase of the first-phase output voltage. Among them, the second adjustment coefficient can be set to be equal to the first adjustment system, and the second offset angle can be set to be equal to the first offset angle.

[0078] The second harmonic injection unit 160 is configured to increase at least one harmonic component arbitrarily selected from each of the harmonics to the second-phase output voltage to update the second-phase output voltage.

[0079] In this embodiment, for harmonic injection into the second-phase output voltage, the specific process of harmonic injection into the second-phase output voltage can also be referred to. There are at least two harmonic injection methods, that is, arbitrarily select one harmonic component from each of the harmonics and increase it to the second-phase output voltage, or arbitrarily select multiple harmonic components from each of the harmonics and increase them to the second-phase output voltage, and the following will be described in detail in combination with specific embodiments.

[0080] In one embodiment, as the first embodiment of the second harmonic injection unit 160, the second harmonic injection unit 160 is specifically configured to: Arbitrarily select one harmonic component from the 2nd to 13th harmonics included in each of the harmonics as a candidate harmonic component; Obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain a preset third adjustment coefficient and a third offset angle; Superimpose a third adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a third adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the third adjustment amplitude = the third adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic amplitude of the candidate harmonic component + the third offset angle.

[0081] In this embodiment, when arbitrarily selecting a harmonic component from the various harmonics and adding it to the second-phase output voltage, one harmonic component can be arbitrarily selected from the 2nd to 13th harmonics included in the various harmonics as the candidate harmonic component, and then the harmonic amplitude and harmonic phase of the candidate harmonic component are obtained, and the preset third adjustment coefficient and third offset angle are obtained. Finally, in combination with the third adjustment amplitude = the third adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic amplitude of the candidate harmonic component + the third offset angle, it should be noted that the rotational speed of the motor under test can also be regarded as the same as that of the original machine (however, after the motor under test is no longer in the test stage but in the actual application stage, the motor under test no longer needs to be connected to the original machine, and at this time, the rotational speed of the motor under test is its actual rotational speed). Among them, the third adjustment coefficient can be set to be equal to the first adjustment system, and the third offset angle can be set to be equal to the first offset angle. By the above method of injecting harmonics into the output voltage, the torque ripple can also be reduced and the effect of improving the compressor NVH can be achieved.

[0082] In one embodiment, as the second embodiment of the second harmonic injection unit 160, the second harmonic injection unit 160 is specifically configured to: Arbitrarily select multiple harmonic components from the 2nd to 13th harmonics included in the various harmonics as a candidate harmonic component set; Obtain the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtain the preset fourth adjustment coefficient and fourth offset angle; Superimpose a fourth adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a fourth adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the fourth adjustment amplitude = the fourth adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the fourth adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the fourth offset angle.

[0083] In this embodiment, the difference from the first embodiment of the second harmonic injection unit is that multiple harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in each harmonic as a candidate harmonic component set, and then the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set are respectively superimposed on the amplitude and phase of the second-phase output voltage. Among them, the fourth adjustment coefficient can be set to be equal to the first adjustment system, and the fourth offset angle can be set to be equal to the first offset angle.

[0084] The voltage output unit 170 is configured to input the first-phase output voltage and the second-phase output voltage to the motor under test.

[0085] In this embodiment, when the first-phase output voltage and the second-phase output voltage are updated by combining harmonic injection processing and then input to the motor under test, it can make the motor rotate stably under the power supply of the first-phase output voltage and the second-phase output voltage.

[0086] It can be seen that implementing the embodiment of this device can extract the corresponding α fundamental wave and each harmonic after Clark transformation and Fourier transformation in sequence after obtaining the three-phase voltage waveforms of the motor under test, and at least one harmonic component arbitrarily selected from each harmonic is added to the first-phase output voltage and the second-phase output voltage to adjust the output voltage and then output to the motor under test, which can reduce its torque ripple and improve the effect of compressor NVH.

[0087] An embodiment of the present invention also provides an electric compressor, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the electric compressor harmonic injection method as described in any one of the foregoing.

[0088] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0089] In several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of each unit is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0090] The steps in the method embodiments of the present invention can be adjusted, combined, and deleted according to actual needs. The units in the device embodiments of the present invention can be combined, divided, and deleted according to actual needs. In addition, the functional units in various embodiments of the present invention can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0091] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a terminal, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention.

[0092] As mentioned above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for harmonic injection of an electric compressor, characterized in that, Including: When the original machine drives the motor under test in the electric compressor to be tested, acquiring the three-phase voltage waveforms of the motor under test; Converting the three-phase voltage waveforms into α / β two-phase waveforms based on the Clarke transformation; Obtaining the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveforms through Fourier transform, and obtaining the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics; wherein, the each harmonic includes a plurality of harmonic components, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0; Obtaining the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor under test; Adding at least one harmonic component arbitrarily selected from the each harmonic to the first-phase output voltage to update the first-phase output voltage; Adding at least one harmonic component arbitrarily selected from the each harmonic to the second-phase output voltage to update the second-phase output voltage; Inputting the first-phase output voltage and the second-phase output voltage into the motor under test.

2. The method according to claim 1, characterized in that, The converting the three-phase voltage waveforms into α / β two-phase waveforms based on the Clarke transformation includes: Obtaining the base transformation matrix corresponding to the Clarke transformation; Transforming the three-phase voltage waveforms according to the base transformation matrix to obtain the corresponding α / β two-phase waveforms.

3. The method according to claim 1, characterized in that, The obtaining the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveforms through Fourier transform includes: Obtaining the α fundamental wave and β fundamental wave corresponding to the α / β two-phase waveforms through Fourier transform, and obtaining the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave as the each harmonic; wherein, each harmonic in the 2nd to 13th harmonics corresponds to a harmonic component.

4. The method according to claim 3, wherein The adding at least one harmonic component arbitrarily selected from the each harmonic to the first-phase output voltage to update the first-phase output voltage includes: Arbitrarily selecting one harmonic component from the 2nd to 13th harmonics included in the each harmonic as the candidate harmonic component; Obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset first adjustment coefficient and a first offset angle; Superimposing a first adjustment amplitude on the amplitude of the first-phase output voltage and superimposing a first adjustment phase on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the first adjustment amplitude = the first adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic amplitude of the candidate harmonic component + the first offset angle.

5. The method according to claim 3, wherein The adding at least one harmonic component arbitrarily selected from the each harmonic to the first-phase output voltage to update the first-phase output voltage includes: Arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the each harmonic as the candidate harmonic component set; Obtaining the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtaining a preset second adjustment coefficient and a second offset angle; Superimpose a second adjustment amplitude on the amplitude of the first-phase output voltage and superimpose a second adjustment phase on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the second adjustment amplitude = the second adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the second adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the second offset angle.

6. The method according to claim 3, wherein The step of adding at least one harmonic component arbitrarily selected from the various harmonics to the second-phase output voltage to update the second-phase output voltage includes: Arbitrarily select one harmonic component from the 2nd to 13th harmonics included in the various harmonics as the candidate harmonic component; Obtain the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtain the preset third adjustment coefficient and third offset angle; Superimpose a third adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a third adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the third adjustment amplitude = the third adjustment coefficient * the rotational speed of the motor under test * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic amplitude of the candidate harmonic component + the third offset angle.

7. The method according to claim 3, characterized in that, The step of adding at least one harmonic component arbitrarily selected from the various harmonics to the second-phase output voltage to update the second-phase output voltage includes: Arbitrarily select a plurality of harmonic components from the 2nd to 13th harmonics included in the various harmonics as the candidate harmonic component set; Obtain the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtain the preset fourth adjustment coefficient and fourth offset angle; Superimpose a fourth adjustment amplitude on the amplitude of the second-phase output voltage and superimpose a fourth adjustment phase on the phase of the second-phase output voltage to update the second-phase output voltage; wherein, the fourth adjustment amplitude = the fourth adjustment coefficient * the rotational speed of the motor under test * the sum of the harmonic amplitudes of each candidate harmonic component in the candidate harmonic component set, and the fourth adjustment phase = the sum of the harmonic phases of each candidate harmonic component in the candidate harmonic component set + the fourth offset angle.

8. An electric compressor harmonic injection device, characterized in that, It includes: A three-phase voltage waveform acquisition unit, configured to acquire the three-phase voltage waveform of the motor under test when the original machine drives the motor under test in the electric compressor to be tested; A Clarke transformation unit, configured to transform the three-phase voltage waveform into an α / β two-phase waveform based on the Clarke transformation; A Fourier transformation unit, configured to obtain the α fundamental wave, β fundamental wave and various harmonics corresponding to the α / β two-phase waveform through Fourier transformation, and obtain the amplitudes and phases of the α fundamental wave and / or the β fundamental wave and the corresponding various harmonics; wherein, the various harmonics include a plurality of harmonic components, and the phase of the α fundamental wave is 0, and the phase of the β fundamental wave is determined when the phase of the α fundamental wave is 0; An output voltage acquisition unit, configured to acquire the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor under test; A first harmonic injection unit, configured to increase at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage, so as to update the first-phase output voltage; A second harmonic injection unit, configured to increase at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage, so as to update the second-phase output voltage; A voltage output unit, configured to input the first-phase output voltage and the second-phase output voltage to the motor under test.

9. The harmonic injection device for the electric compressor according to claim 8, wherein, Specifically, the Clarke transformation unit is configured to: Obtain a base transformation matrix corresponding to the Clarke transformation; Transform the three-phase voltage waveform according to the base transformation matrix to obtain the corresponding α / β two-phase waveform.

10. An electric compressor, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the harmonic injection method for an electric compressor according to any one of claims 1-7.

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