Electric compressor harmonic injection method, device and electric compressor

Abstract

The present invention discloses a method, device and electric compressor for injecting harmonics into an electric compressor, which collect and obtain the three-phase voltage waveform of the motor to be tested; convert the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transform; obtain the corresponding α fundamental wave and each harmonic and their respective amplitudes and phases through Fourier transform; obtain the first-phase output voltage and the second-phase output voltage; add at least one harmonic component arbitrarily selected from each harmonic to the first-phase output voltage and the second-phase output voltage, and input them to the motor to be tested after updating. The embodiment of the present invention can extract the corresponding α fundamental wave and each harmonic through Clarke transform and Fourier transform after obtaining the three-phase voltage waveform of the motor to be tested, and add at least one harmonic component arbitrarily selected from each harmonic to the first-phase output voltage and the second-phase output voltage to adjust the output voltage before outputting it to the motor to be tested, which can reduce its torque pulsation and improve the NVH effect of the compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of electric compression control, and in particular to a method and device for injecting harmonics into an electric compressor, and an electric compressor. Background Art

[0002] As a key component of electric vehicles, electric compressors are also developing motors with high power and torque. The greater the motor torque, the greater the vibration and noise generated. Currently, a common approach is to directly reduce the motor's phase current harmonics through software closed-loop control. However, for cost considerations, the magnetic field distribution of compressor motors is often non-sinusoidal, resulting in significant harmonics. These harmonics, coupled with the fundamental component of the phase current, still generate significant harmonics, impacting the compressor's NVH performance. Summary of the Invention

[0003] The embodiments of the present invention provide a method, device and electric compressor for injecting harmonics into 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 has large harmonics itself. When coupled with the fundamental component of the phase current, it still produces large harmonics, which affects the NVH performance of the compressor.

[0004] In a first aspect, an embodiment of the present invention provides a method for injecting harmonics into an electric compressor, comprising:

[0005] When the original machine is driving the motor under test in the electric compressor under test, collecting and obtaining the three-phase voltage waveform of the motor under test;

[0006] Converting the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation;

[0007] Obtaining an α fundamental wave, a β fundamental wave, and each subharmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding subharmonic; wherein each subharmonic includes multiple 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;

[0008] Obtaining a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor to be tested;

[0009] adding at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage;

[0010] adding at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage;

[0011] The first-phase output voltage and the second-phase output voltage are input to the motor to be tested.

[0012] In a second aspect, an embodiment of the present invention further provides a harmonic injection device for an electric compressor, comprising:

[0013] A three-phase voltage waveform acquisition unit is used to acquire the three-phase voltage waveform of the motor under test when the original machine is driving the motor under test in the electric compressor under test;

[0014] a Clarke transformation unit, configured to transform the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation;

[0015] a Fourier transform unit, configured to obtain, by Fourier transform, an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform, and obtain the amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding harmonic; wherein each harmonic includes multiple 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;

[0016] An output voltage acquisition unit, used to acquire a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor to be tested;

[0017] a first harmonic injection unit, configured to add at least one harmonic component arbitrarily selected from the harmonics to the first phase output voltage to update the first phase output voltage;

[0018] a second harmonic injection unit, configured to add at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage;

[0019] The voltage output unit is used to input the first-phase output voltage and the second-phase output voltage into the motor to be tested.

[0020] In a third aspect, an embodiment of the present invention further provides an electric compressor comprising a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the method described in the first aspect is implemented.

[0021] An embodiment of the present invention provides a method and device for injecting harmonics into an electric compressor, and an electric compressor. The method comprises: when the original machine is driving the motor to be tested in the electric compressor to be tested, collecting and obtaining the three-phase voltage waveform of the motor to be tested; converting the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transform; obtaining the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the amplitude and phase of the α fundamental wave and / or the β fundamental wave and the corresponding each harmonic; wherein each harmonic includes multiple harmonic components, and the 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 to be tested; adding at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage; adding at least one harmonic component arbitrarily selected from the harmonics 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 to the motor to be tested. The embodiment of the present invention can extract the corresponding α fundamental wave and each harmonic through Clarke transform and Fourier transform after obtaining the three-phase voltage waveform of the motor to be tested, and add at least one harmonic component arbitrarily selected from each harmonic to the first-phase output voltage and the second-phase output voltage to adjust the output voltage before outputting it to the motor to be tested, thereby reducing its torque pulsation and improving the NVH effect of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic flow chart of a harmonic injection method for an electric compressor provided in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of an application scenario of the electric compressor harmonic injection method provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a sub-process of a harmonic injection method for an electric compressor provided by an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a sub-process of a harmonic injection method for an electric compressor provided by an embodiment of the present invention;

[0027] Figure 5A schematic diagram of a sub-process of a harmonic injection method for an electric compressor provided by an embodiment of the present invention;

[0028] Figure 6 A schematic block diagram of a harmonic injection device for an electric compressor provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0031] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in the specification and appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0033] See also Figure 1 , which is a flow chart of the method for injecting harmonics into an electric compressor according to an embodiment of the present invention. Figure 1 As shown, the electric compressor harmonic injection method includes steps S110 to S170.

[0034] S110 , when the original machine is driving the motor to be tested in the electric compressor to be tested, collecting and obtaining the three-phase voltage waveform of the motor to be tested.

[0035] In this embodiment, the electric compressor harmonic injection method 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 as follows: Figure 2As shown, the motor control loop includes at least an electric compressor 10 (the motor used is specifically a permanent magnet synchronous motor (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, to the permanent magnet synchronous motor in the electric compressor 10). Furthermore, the voltage source inverter 30 can also be connected to a direct current bus (DC BUS) to connect to a DC power source and convert it into alternating current.

[0036] In order to obtain a more appropriate harmonic injection method in the early test stage of the electric compressor, the permanent magnet synchronous motor in the electric compressor can be used as the motor to be tested and connected to the original machine (which can be understood as the prime mover, which can provide a stable speed). More specifically, the three phases of the permanent magnet synchronous motor, U phase, V phase and W phase, are connected to the corresponding three phases of the original machine (also U phase, V phase and W phase) through a plug-in resistor (such as 120K resistance), 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.

[0037] S120 , converting the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation.

[0038] In this embodiment, after the three-phase voltage waveform of the motor to be tested is determined in the above manner, it corresponds to a three-phase system (which can be regarded as an abc coordinate system), and its time domain components can be converted and correspond to the two components 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 Clarke transformation.

[0039] Among them, since it is known that the phases in the three-phase system differ by 120° 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 three-phase voltage waveform can be converted into an α / β two-phase waveform in combination with the Clarke transform.

[0040] In one embodiment, if Figure 3 As shown, step S120 includes:

[0041] S121. Obtain a basis transformation matrix corresponding to the Clarke transformation;

[0042] S122. Transform the three-phase voltage waveform according to the base transformation matrix to obtain the corresponding α / β two-phase waveform.

[0043] In this embodiment, when the initial basis transformation matrix in the Clarke transformation is specifically represented by T, it is specifically as follows:

[0044] ;

[0045] After knowing the base transformation matrix corresponding to the Clarke transformation, the base transformation matrix can be multiplied by the vector (ia, ib, ic) composed of the current values ​​corresponding to the three-phase voltage values ​​corresponding to any time point in the three-phase voltage waveform to convert it into a vector (iα, iβ) corresponding to the αβ coordinate system. Combined with Kirchhoff's current law, it can be seen that the sum of all currents entering a node is equal to the sum of all currents leaving this node. When the three-phase currents corresponding to the motor to be tested are ia, ib and ic respectively, then ia+ib+ic=0 is satisfied. In addition, 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 basis transformation matrix and the above conditions to be satisfied, we can know that:

[0046] ;

[0047] The above transformation method realizes the conversion of the three-phase voltage waveform into an α / β two-phase waveform.

[0048] 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 amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding harmonic.

[0049] Wherein, each harmonic wave includes multiple 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.

[0050] In this embodiment, when Fourier transform is used to obtain the α fundamental, β fundamental, and various harmonics corresponding to the α / β two-phase waveform, it is taken into account that any periodic signal (or a finite-duration segment of a non-periodic signal) can be decomposed into a superposition of sine / cosine components of different frequencies. Specifically, sampling can be performed over a full cycle (where the number of sampling points N is an integer multiple of the α fundamental period) to avoid spectral leakage. Of course, when Fourier transform is used to obtain the β fundamental corresponding to the α / β two-phase waveform, it also has an initial phase, and the initial phase of the β fundamental is obtained with reference to the phase of the α fundamental. That is, as long as Fourier transform is used to obtain the α fundamental corresponding to the α / β two-phase waveform and its phase is limited to 0, the phase of the β fundamental can be measured.

[0051] In specific implementation, step S130 includes the following implementation methods:

[0052] A1) obtaining, by Fourier transform, an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform, and obtaining amplitudes and phases of the α fundamental wave, each harmonic corresponding to the α fundamental wave, the β fundamental wave, and each harmonic corresponding to the β fundamental wave;

[0053] A2) obtaining an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform by Fourier transform, and obtaining the amplitude and phase of the α fundamental wave and each harmonic corresponding to the α fundamental wave;

[0054] A3) Obtaining the α fundamental wave, β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the amplitude and phase of the β fundamental wave and each harmonic corresponding to the β fundamental wave.

[0055] 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, and finally the α fundamental wave, β fundamental wave and each harmonic can be obtained, and the amplitude and phase of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics can be specifically obtained.

[0056] In one embodiment, step S130 includes:

[0057] The α fundamental wave and the β fundamental wave corresponding to the α / β two-phase waveform are obtained by Fourier transform, and the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave are obtained as the harmonics.

[0058] Among them, each harmonic from the 2nd to the 13th harmonic corresponds to a harmonic component.

[0059] In this embodiment, if the higher harmonics in the α / β two-phase waveform (i.e., harmonics whose multiples of the α fundamental wave are greater than 13) are used to inject the input voltage of the motor to be tested, the effect is not good. Therefore, the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave need to be selected as the harmonics, and each of the 2nd to 13th harmonics corresponds to a harmonic component.

[0060] Specifically, obtaining the α fundamental wave and the 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 harmonics includes the following implementations:

[0061] B1) obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform by Fourier transform, and obtaining 2nd to 13th harmonics corresponding to the α fundamental wave and the β fundamental wave respectively as the harmonics;

[0062] B2) obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform by Fourier transform, and obtaining 2nd to 13th harmonics corresponding to the α fundamental wave as the harmonics;

[0063] B3) Obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining 2nd to 13th order harmonics corresponding to the β fundamental wave as the order harmonics.

[0064] However, no matter which of the above methods is used to obtain the harmonics, they can all be injected into the first-phase output voltage and the second-phase output voltage.

[0065] S140 , obtaining a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor to be tested.

[0066] In this embodiment, when harmonic injection is performed on the motor to be tested to reduce torque pulsation and improve the NVH (NHV) 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.

[0067] S150 , adding at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage.

[0068] In this embodiment, when harmonic injection is performed on the input voltage, both of the above-mentioned input voltages need to be harmonically injected. At this time, the specific process can be explained by taking the harmonic injection of the first-phase output voltage as an example. There are at least two harmonic injection methods, namely, arbitrarily selecting one harmonic component from the harmonics and adding it to the first-phase output voltage, or arbitrarily selecting multiple harmonic components from the harmonics and adding them to the first-phase output voltage. The details are explained below in conjunction with the specific implementation methods.

[0069] In one embodiment, as a first embodiment of step S150, as Figure 4 As shown, step S150 includes:

[0070] S151A, arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component;

[0071] S152A, obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset first adjustment coefficient and a first offset angle;

[0072] 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; wherein, the first adjustment amplitude = the first adjustment coefficient * the speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic phase of the candidate harmonic component + the first offset angle.

[0073] In this embodiment, when a harmonic component is arbitrarily selected from the harmonics and added to the first phase output voltage, a harmonic component can be arbitrarily selected from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component, such as selecting any harmonic component of the 2nd harmonic, the 3rd harmonic, the 4th harmonic, the 5th harmonic, the 6th harmonic, the 7th harmonic, the 8th harmonic, the 9th harmonic, the 10th harmonic, the 11th harmonic, the 12th harmonic, and the 13th harmonic as the candidate harmonic component, and then obtaining the harmonic coefficient of the candidate harmonic component. The amplitude and harmonic phase of the motor under test are calculated, and the preset first adjustment coefficient and first offset angle are obtained. Finally, the first adjustment amplitude = first adjustment coefficient * speed of the motor under test * harmonic amplitude of the candidate harmonic component, and the first adjustment phase = harmonic phase of the candidate harmonic component + first offset angle are combined. It should be noted that the speed of the motor under test can also be considered to be the same as the speed of the original motor (however, after the motor under test is no longer in the testing phase and is in the actual application phase, the motor under test is no longer connected to the original motor, and the speed of the motor under test is now its actual speed). By injecting harmonics into the output voltage in this way, torque pulsation can be reduced and the NVH effect of the compressor can be improved.

[0074] In one embodiment, as a second embodiment of step S150, as Figure 5 As shown, step S150 includes:

[0075] S151B, arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component set;

[0076] S152B, 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 second offset angle;

[0077] S153B. 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 speed of the motor to be tested * 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.

[0078] This embodiment differs from step S150 of the first embodiment in that a plurality of harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in 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 correspondingly superimposed on the amplitude and phase of the first-phase output voltage. The second adjustment coefficient can be set equal to the first adjustment coefficient, and the second offset angle can be set equal to the first offset angle.

[0079] S160 , adding at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage.

[0080] In this embodiment, harmonic injection is performed on the second-phase output voltage. Reference may be made to the specific process of harmonic injection on the second-phase output voltage, wherein there are at least two harmonic injection methods, namely, arbitrarily selecting one harmonic component from the harmonics and adding it to the second-phase output voltage, or arbitrarily selecting multiple harmonic components from the harmonics and adding them to the second-phase output voltage. Detailed descriptions are given below in conjunction with specific implementation methods.

[0081] In one embodiment, as a first embodiment of step S160, step S160 includes:

[0082] arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component;

[0083] Obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset third adjustment coefficient and a third offset angle;

[0084] A third adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a third adjustment phase is superimposed 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 speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic phase of the candidate harmonic component + the third offset angle.

[0085] In this embodiment, when arbitrarily selecting a harmonic component from the harmonics and adding it to the second-phase output voltage, a harmonic component can be first arbitrarily selected from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component, and then the harmonic amplitude and harmonic phase of the candidate harmonic component are obtained, and a preset third adjustment coefficient and third offset angle are obtained. Finally, the third adjustment amplitude = the third adjustment coefficient * the speed of the motor to be tested * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic phase of the candidate harmonic component + the third offset angle. It should be noted that the speed of the motor to be tested can also be considered to be the same as the speed of the original machine (but after the motor to be tested is no longer in the test phase and is in the actual application phase, the motor to be tested does not need to be connected to the original machine, and the speed of the motor to be tested is its actual speed). 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 injecting the harmonics into the output voltage, torque pulsation can also be reduced and the NVH effect of the compressor can be improved.

[0086] In one embodiment, as a second embodiment of step S160, step S160 includes:

[0087] arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component set;

[0088] Obtaining the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtaining a preset fourth adjustment coefficient and a fourth offset angle;

[0089] A fourth adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a fourth adjustment phase is superimposed 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 speed of the motor to be tested * 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.

[0090] This embodiment differs from step S160 of the first embodiment in that a plurality of harmonic components are arbitrarily selected from the 2nd to 13th harmonics included in 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 correspondingly superimposed on the amplitude and phase of the second-phase output voltage. The fourth adjustment coefficient can be set equal to that of the first adjustment coefficient, and the fourth offset angle can be set equal to the first offset angle.

[0091] S170. Input the first-phase output voltage and the second-phase output voltage to the motor to be tested.

[0092] 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 to be tested, it can rotate stably under the power supply of the first phase output voltage and the second phase output voltage.

[0093] It can be seen that the embodiment of the method can extract the corresponding α fundamental wave and each harmonic after obtaining the three-phase voltage waveform of the motor to be tested through Clarke transform and Fourier transform in sequence, and add at least one harmonic component arbitrarily selected from each harmonic to the first phase output voltage and the second phase output voltage to adjust the output voltage before outputting it to the motor to be tested, which can reduce its torque pulsation and improve the NVH effect of the compressor.

[0094] Figure 6 FIG. 1 is a schematic block diagram of a harmonic injection device for an electric compressor provided by an embodiment of the present invention. Figure 6 As shown, corresponding to the above electric compressor harmonic injection method, the present invention also 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 transform unit 120, a Fourier transform 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.

[0095] The three-phase voltage waveform acquisition unit 110 is used to acquire the three-phase voltage waveform of the motor to be tested when the original machine drives the motor to be tested in the electric compressor to be tested.

[0096] In this embodiment, the electric compressor harmonic injection method 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 as follows: Figure 2 As shown, the motor control loop includes at least an electric compressor 10 (the motor used is specifically a permanent magnet synchronous motor (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, to the permanent magnet synchronous motor in the electric compressor 10). Furthermore, the voltage source inverter 30 can also be connected to a direct current bus (DC BUS) to connect to a DC power source and convert it into alternating current.

[0097] In order to obtain a more appropriate harmonic injection method in the early test stage of the electric compressor, the permanent magnet synchronous motor in the electric compressor can be used as the motor to be tested and connected to the original machine (which can be understood as the prime mover, which can provide a stable speed). More specifically, the three phases of the permanent magnet synchronous motor, U phase, V phase and W phase, are connected to the corresponding three phases of the original machine (also U phase, V phase and W phase) through a plug-in resistor (such as 120K resistance), 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.

[0098] The Clarke transformation unit 120 is configured to transform the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation.

[0099] In this embodiment, after the three-phase voltage waveform of the motor to be tested is determined in the above manner, it corresponds to a three-phase system (which can be regarded as an abc coordinate system), and its time domain components can be converted and correspond to the two components 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 Clarke transformation.

[0100] Among them, since it is known that the phases in the three-phase system differ by 120° 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 three-phase voltage waveform can be converted into an α / β two-phase waveform in combination with the Clarke transform.

[0101] In one embodiment, the Clarke transform unit 120 is specifically configured to:

[0102] Obtaining a basis transformation matrix corresponding to the Clarke transform;

[0103] The three-phase voltage waveform is transformed according to the base transformation matrix to obtain the corresponding α / β two-phase waveform.

[0104] In this embodiment, when the initial basis transformation matrix in the Clarke transformation is specifically represented by T, it is specifically as follows:

[0105] ;

[0106] After knowing the base transformation matrix corresponding to the Clarke transformation, the base transformation matrix can be multiplied by the vector (ia, ib, ic) composed of the current values ​​corresponding to the three-phase voltage values ​​corresponding to any time point in the three-phase voltage waveform to convert it into a vector (iα, iβ) corresponding to the αβ coordinate system. Combined with Kirchhoff's current law, it can be seen that the sum of all currents entering a node is equal to the sum of all currents leaving this node. When the three-phase currents corresponding to the motor to be tested are ia, ib and ic respectively, then ia+ib+ic=0 is satisfied. In addition, 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 basis transformation matrix and the above conditions to be satisfied, we can know that:

[0107] ;

[0108] The above transformation method realizes the conversion of the three-phase voltage waveform into an α / β two-phase waveform.

[0109] The Fourier transform unit 130 is used to 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 amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding harmonic.

[0110] Wherein, each harmonic wave includes multiple 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.

[0111] In this embodiment, when Fourier transform is used to obtain the α fundamental and various harmonics corresponding to the α / β two-phase waveform, the consideration is that any periodic signal (or a finite-duration segment of a non-periodic signal) can be decomposed into a superposition of sine and cosine components of different frequencies. Specifically, full-cycle sampling (where the number of sampling points, N, is an integer multiple of the α fundamental period) is employed to avoid spectral leakage. Of course, when Fourier transform is used to obtain the β fundamental corresponding to the α / β two-phase waveform, an initial phase is also present, and the initial phase of the β fundamental is derived with reference to the phase of the α fundamental.

[0112] In specific implementation, the Fourier transform unit 130 includes the following implementation methods:

[0113] C1) obtaining an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform by Fourier transform, and obtaining amplitudes and phases of the α fundamental wave, each harmonic corresponding to the α fundamental wave, the β fundamental wave, and each harmonic corresponding to the β fundamental wave;

[0114] C2) obtaining an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform by Fourier transform, and obtaining the amplitude and phase of the α fundamental wave and each harmonic corresponding to the α fundamental wave;

[0115] C3) Obtaining the α fundamental wave, the β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the amplitude and phase of the β fundamental wave and each harmonic corresponding to the β fundamental wave.

[0116] 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, and finally the α fundamental wave, β fundamental wave and each harmonic can be obtained, and the amplitude and phase of the α fundamental wave and / or the β fundamental wave and the corresponding harmonics can be specifically obtained.

[0117] In one embodiment, the Fourier transform unit 130 is specifically configured to:

[0118] The α fundamental wave and the β fundamental wave corresponding to the α / β two-phase waveform are obtained by Fourier transform, and the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave are obtained as the harmonics.

[0119] Among them, each harmonic from the 2nd to the 13th harmonic corresponds to a harmonic component.

[0120] In this embodiment, if the higher harmonics in the α / β two-phase waveform (i.e., harmonics whose multiples of the α fundamental wave are greater than 13) are used to inject the input voltage of the motor to be tested, the effect is not good. Therefore, the 2nd to 13th harmonics corresponding to the α fundamental wave and / or the β fundamental wave need to be selected as the harmonics, and each of the 2nd to 13th harmonics corresponds to a harmonic component.

[0121] When the Fourier transform unit 130 is replaced by executing Fourier transform to obtain the α fundamental wave, β fundamental wave and each harmonic corresponding to the α / β two-phase waveform, and obtain the amplitude and phase of the α fundamental wave, the β fundamental wave and the each harmonic, it can be specifically executed to 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 constitute the each harmonic.

[0122] Specifically, obtaining the α fundamental wave and the 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 harmonics includes the following implementations:

[0123] D1) obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform by Fourier transform, and obtaining 2nd to 13th harmonics corresponding to the α fundamental wave and the β fundamental wave respectively as the harmonics;

[0124] D2) obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform by Fourier transform, and obtaining 2nd to 13th harmonics corresponding to the α fundamental wave as the harmonics;

[0125] D3) Obtaining an α fundamental wave and a β fundamental wave corresponding to the α / β two-phase waveform through Fourier transform, and obtaining 2nd to 13th order harmonics corresponding to the β fundamental wave as the order harmonics.

[0126] However, no matter which of the above methods is used to obtain the harmonics, they can all be injected into the first-phase output voltage and the second-phase output voltage.

[0127] The output voltage acquisition unit 140 is used to acquire the first-phase output voltage and the second-phase output voltage in the motor control loop corresponding to the motor to be tested.

[0128] In this embodiment, when harmonic injection is performed on the motor to be tested to reduce torque pulsation and improve the NVH (NHV) 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.

[0129] The first harmonic injection unit 150 is configured to add at least one harmonic component arbitrarily selected from the harmonics to the first phase output voltage to update the first phase output voltage.

[0130] In this embodiment, when harmonic injection is performed on the input voltage, both of the above-mentioned input voltages need to be harmonically injected. At this time, the specific process can be explained by taking the harmonic injection of the first-phase output voltage as an example. There are at least two harmonic injection methods, namely, arbitrarily selecting one harmonic component from the harmonics and adding it to the first-phase output voltage, or arbitrarily selecting multiple harmonic components from the harmonics and adding them to the first-phase output voltage. The details are explained below in conjunction with the specific implementation methods.

[0131] In one embodiment, as a first embodiment of the first harmonic injection unit 150, it is specifically used to:

[0132] arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component;

[0133] Obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset first adjustment coefficient and a first offset angle;

[0134] A first adjustment amplitude is superimposed on the amplitude of the first-phase output voltage and a first adjustment phase is superimposed 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 speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic phase of the candidate harmonic component + the first offset angle.

[0135] In this embodiment, when a harmonic component is arbitrarily selected from the harmonics and added to the first phase output voltage, a harmonic component can be arbitrarily selected from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component, such as selecting any harmonic component of the 2nd harmonic, the 3rd harmonic, the 4th harmonic, the 5th harmonic, the 6th harmonic, the 7th harmonic, the 8th harmonic, the 9th harmonic, the 10th harmonic, the 11th harmonic, the 12th harmonic, and the 13th harmonic as the candidate harmonic component, and then obtaining the harmonic coefficient of the candidate harmonic component. The amplitude and harmonic phase of the motor under test are calculated, and the preset first adjustment coefficient and first offset angle are obtained. Finally, the first adjustment amplitude = first adjustment coefficient * speed of the motor under test * harmonic amplitude of the candidate harmonic component, and the first adjustment phase = harmonic phase of the candidate harmonic component + first offset angle are combined. It should be noted that the speed of the motor under test can also be considered to be the same as the speed of the original motor (however, after the motor under test is no longer in the testing phase and is in the actual application phase, the motor under test is no longer connected to the original motor, and the speed of the motor under test is now its actual speed). By injecting harmonics into the output voltage in this way, torque pulsation can be reduced and the NVH effect of the compressor can be improved.

[0136] In one embodiment, the first harmonic injection unit 150 of the second embodiment as the first harmonic injection unit 150 is specifically configured to:

[0137] arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component set;

[0138] 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;

[0139] A second adjustment amplitude is superimposed on the amplitude of the first-phase output voltage and a second adjustment phase is superimposed on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the second adjustment amplitude = a second adjustment coefficient * the speed of the motor to be tested * 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 + a second offset angle.

[0140] This embodiment differs from the first embodiment of the first harmonic injection unit in 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 correspondingly superimposed on the amplitude and phase of the first phase output voltage. The second adjustment coefficient can be set equal to that of the first adjustment coefficient, and the second offset angle can be set equal to the first offset angle.

[0141] The second harmonic injection unit 160 is configured to add at least one harmonic component arbitrarily selected from the harmonics to the second phase output voltage to update the second phase output voltage.

[0142] In this embodiment, harmonic injection is performed on the second-phase output voltage. Reference may be made to the specific process of harmonic injection on the second-phase output voltage, wherein there are at least two harmonic injection methods, namely, arbitrarily selecting one harmonic component from the harmonics and adding it to the second-phase output voltage, or arbitrarily selecting multiple harmonic components from the harmonics and adding them to the second-phase output voltage. Detailed descriptions are given below in conjunction with specific implementation methods.

[0143] In one embodiment, as a first embodiment of the second harmonic injection unit 160, the second harmonic injection unit 160 is specifically configured to:

[0144] arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component;

[0145] Obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset third adjustment coefficient and a third offset angle;

[0146] A third adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a third adjustment phase is superimposed 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 speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic phase of the candidate harmonic component + the third offset angle.

[0147] In this embodiment, when arbitrarily selecting a harmonic component from the harmonics and adding it to the second-phase output voltage, a harmonic component can be first arbitrarily selected from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component, and then the harmonic amplitude and harmonic phase of the candidate harmonic component are obtained, and a preset third adjustment coefficient and third offset angle are obtained. Finally, the third adjustment amplitude = the third adjustment coefficient * the speed of the motor to be tested * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic phase of the candidate harmonic component + the third offset angle. It should be noted that the speed of the motor to be tested can also be considered to be the same as the speed of the original machine (but after the motor to be tested is no longer in the test phase and is in the actual application phase, the motor to be tested does not need to be connected to the original machine, and the speed of the motor to be tested is its actual speed). 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 injecting the harmonics into the output voltage, torque pulsation can also be reduced and the NVH effect of the compressor can be improved.

[0148] In one embodiment, as a second embodiment of the second harmonic injection unit 160, the second harmonic injection unit 160 is specifically configured to:

[0149] arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component set;

[0150] Obtaining the harmonic amplitude and harmonic phase of each candidate harmonic component in the candidate harmonic component set, and obtaining a preset fourth adjustment coefficient and a fourth offset angle;

[0151] A fourth adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a fourth adjustment phase is superimposed 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 speed of the motor to be tested * 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.

[0152] This embodiment differs from the first embodiment of the second harmonic injection unit in 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 correspondingly superimposed on the amplitude and phase of the second-phase output voltage. The fourth adjustment coefficient can be set equal to that of the first adjustment coefficient, and the fourth offset angle can be set equal to the first offset angle.

[0153] The voltage output unit 170 is configured to input the first-phase output voltage and the second-phase output voltage to the motor to be tested.

[0154] 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 to be tested, it can rotate stably under the power supply of the first phase output voltage and the second phase output voltage.

[0155] It can be seen that the embodiment of the device can extract the corresponding α fundamental wave and each harmonic after obtaining the three-phase voltage waveform of the motor to be tested through Clarke transform and Fourier transform in sequence, and add at least one harmonic component arbitrarily selected from each harmonic to the first phase output voltage and the second phase output voltage to adjust the output voltage before outputting it to the motor to be tested, which can reduce its torque pulsation and improve the NVH effect of the compressor.

[0156] An embodiment of the present invention also provides an electric compressor, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the electric compressor harmonic injection method as described in any one of the above items is implemented.

[0157] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0158] In the several embodiments provided herein, 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 the various units is merely a logical functional division, and actual implementation may employ other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not implemented.

[0159] The steps in the methods of the embodiments of the present invention may be adjusted in order, combined, or deleted as needed. The units in the devices of the embodiments of the present invention may be combined, divided, or deleted as needed. Furthermore, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit.

[0160] If this integrated unit is implemented as 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, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product, stored in a storage medium, includes instructions for enabling a computer device (such as a personal computer, terminal, or network device) to execute all or part of the steps of the method described in various embodiments of the present invention.

[0161] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for injecting harmonics into an electric compressor, characterized in that: include: When the original machine is driving the motor under test in the electric compressor under test, collecting and obtaining the three-phase voltage waveform of the motor under test; Converting the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation; Obtaining an α fundamental wave, a β fundamental wave, and each subharmonic corresponding to the α / β two-phase waveform through Fourier transform, and obtaining the amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding subharmonic; wherein each subharmonic includes multiple 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 a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor to be tested; adding at least one harmonic component arbitrarily selected from the harmonics to the first-phase output voltage to update the first-phase output voltage; adding at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage; The first-phase output voltage and the second-phase output voltage are input to the motor to be tested.

2. The method according to claim 1, characterized in that The converting of the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation includes: Obtaining a basis transformation matrix corresponding to the Clarke transform; The three-phase voltage waveform is transformed according to the base transformation matrix to obtain the corresponding α / β two-phase waveform.

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

4. The method according to claim 3, characterized in that The step of adding at least one harmonic component arbitrarily selected from the harmonics to the first phase output voltage to update the first phase output voltage includes: arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a 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; A first adjustment amplitude is superimposed on the amplitude of the first-phase output voltage and a first adjustment phase is superimposed 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 speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the first adjustment phase = the harmonic phase of the candidate harmonic component + the first offset angle.

5. The method according to claim 3, characterized in that The step of adding at least one harmonic component arbitrarily selected from the harmonics 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 harmonics as a 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; A second adjustment amplitude is superimposed on the amplitude of the first-phase output voltage and a second adjustment phase is superimposed on the phase of the first-phase output voltage to update the first-phase output voltage; wherein, the second adjustment amplitude = a second adjustment coefficient * the speed of the motor to be tested * 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 + a second offset angle.

6. The method according to claim 3, characterized in that The step of adding at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage includes: arbitrarily selecting a harmonic component from the 2nd to 13th harmonics included in the harmonics as a candidate harmonic component; Obtaining the harmonic amplitude and harmonic phase of the candidate harmonic component, and obtaining a preset third adjustment coefficient and a third offset angle; A third adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a third adjustment phase is superimposed 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 speed of the motor to be measured * the harmonic amplitude of the candidate harmonic component, and the third adjustment phase = the harmonic phase 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 harmonics to the second-phase output voltage to update the second-phase output voltage includes: arbitrarily selecting a plurality of harmonic components from the 2nd to 13th harmonics included in the harmonics as a 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 fourth adjustment coefficient and a fourth offset angle; A fourth adjustment amplitude is superimposed on the amplitude of the second-phase output voltage and a fourth adjustment phase is superimposed 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 speed of the motor to be tested * 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. A harmonic injection device for an electric compressor, characterized in that: include: A three-phase voltage waveform acquisition unit is used to acquire the three-phase voltage waveform of the motor under test when the original machine is driving the motor under test in the electric compressor under test; a Clarke transformation unit, configured to transform the three-phase voltage waveform into an α / β two-phase waveform based on Clarke transformation; a Fourier transform unit, configured to obtain, by Fourier transform, an α fundamental wave, a β fundamental wave, and each harmonic corresponding to the α / β two-phase waveform, and obtain the amplitude and phase of the α fundamental wave and / or the β fundamental wave and each corresponding harmonic; wherein each harmonic includes multiple 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, used to acquire a first-phase output voltage and a second-phase output voltage in a motor control loop corresponding to the motor to be tested; a first harmonic injection unit, configured to add 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 add at least one harmonic component arbitrarily selected from the harmonics to the second-phase output voltage to update the second-phase output voltage; The voltage output unit is used to input the first-phase output voltage and the second-phase output voltage into the motor to be tested.

9. The electric compressor harmonic injection device according to claim 8, characterized in that: The Clarke transform unit is specifically used for: Obtaining a basis transformation matrix corresponding to the Clarke transform; The three-phase voltage waveform is transformed 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 in the memory and executable on the processor, wherein: When the processor executes the computer program, the electric compressor harmonic injection method according to any one of claims 1 to 7 is implemented.

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