A current harmonic suppression method, device, equipment and medium

Abstract

The present application relates to the technical field of harmonic suppression, and discloses a current harmonic suppression method, device, equipment and medium, the method comprises the following steps: determining a target group according to the current operating frequency of a motor; outputting a pre-calculated coefficient group corresponding to the target group to a quasi-resonance controller; obtaining a quasi-resonance adjustment amount output by the quasi-resonance controller based on the input coefficient group; and obtaining a target control amount by combining the quasi-resonance adjustment amount and a proportional integral adjustment amount output by a proportional integral controller, wherein the present application does not require a large number of coefficient calculation processes in the control process, can greatly reduce the calculation amount, avoids a large amount of calculation from occupying the FOC interruption execution time, and can be implemented on a low-cost controller, thereby reducing the control cost.

Description

Technical Field

[0001] This invention relates to the field of harmonic suppression technology, specifically to a method, apparatus, device, and medium for suppressing current harmonics. Background Technology

[0002] Currently, the commonly used harmonic suppression strategy in motor control is to use the 5th and 7th order rotational transformations of the motor operating frequency to transform the sampled three-phase motor current to the dq axis. Then, the output is adjusted by multiple proportional-integral (PI) controllers to obtain the adjustment parameters in the 5th and 7th order dq axis coordinate systems. The adjustment parameters are then rotated to the αβ coordinate system of the fundamental frequency. The output adjustment amount is added to the given voltage in the αβ coordinate system output by the original control system to obtain the final target output voltage to the inverter.

[0003] When extracting harmonics, this scheme requires coordinate transformations according to the 5th and 7th order frequencies, involving a large number of trigonometric functions and a large amount of computation during the control process. Summary of the Invention

[0004] In view of this, the present invention provides a current harmonic suppression method, apparatus, device and medium to solve the technical problem of large computational load in the motor harmonic suppression control process.

[0005] In a first aspect, the present invention provides a method for suppressing current harmonics, comprising:

[0006] Determine the target group based on the current operating frequency of the motor;

[0007] The pre-calculated coefficient set corresponding to the target group is output to the quasi-resonant controller;

[0008] Obtain the quasi-resonant adjustment amount of the quasi-resonant controller based on the coefficient set of the input;

[0009] The target control quantity is obtained by combining the quasi-resonant regulation quantity and the proportional-integral regulation quantity of the output of the proportional-integral controller.

[0010] The current harmonic suppression method of the present invention determines the target group based on the current operating frequency of the motor, outputs the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller, obtains the quasi-resonant adjustment amount output by the quasi-resonant controller based on the input coefficient group, and obtains the target control amount by combining the quasi-resonant adjustment amount and the proportional-integral adjustment amount output by the proportional-integral controller. The quasi-resonant adjustment amount is obtained by calling the coefficient group according to the target group corresponding to the current operating frequency of the motor. The control process does not require a large number of coefficient calculations, which can greatly reduce the amount of calculation and avoid a large amount of calculation occupying the FOC interrupt execution time. Moreover, it can be implemented on a low-cost controller, reducing the control cost.

[0011] In some alternative implementations, the calculation steps for coefficient groups of any group include:

[0012] The number of groups in the coefficient group is determined based on the highest operating frequency of the motor.

[0013] The harmonic suppression center point frequency of each group is determined based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth.

[0014] Calculate the value of any coefficient in the coefficient group corresponding to each group based on the harmonic suppression center frequency and resonant bandwidth of each group.

[0015] This approach ensures that current harmonic suppression can be achieved based on a reasonable set of coefficients in different groups, thereby improving the effectiveness of the entire harmonic suppression method.

[0016] In some alternative implementations, the number of groups in the coefficient group is determined based on the highest operating frequency of the motor, including:

[0017] Divide the motor’s highest operating frequency by the resonant bandwidth to obtain the number of groups of coefficients. The center point of each group is the corresponding harmonic suppression center point frequency, and the frequency bandwidth of each group is the resonant bandwidth.

[0018] This method can quickly divide the coefficient groups into groups and determine the number of groups based on the motor parameters, providing a clear basis for subsequent calculation of the relevant parameters of each group.

[0019] In some alternative implementations, the harmonic suppression center frequency of each group is determined based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth, including:

[0020] Based on the center point frequency calculation formula, the harmonic suppression center point frequency for each group is determined according to the number of coefficient groups, the highest operating frequency of the motor, and the resonant bandwidth. The center point frequency calculation formula includes:

[0021] ω e_k =2*π*(k-1)f max / m+ω c / 2, k = 1, 2...m

[0022] In the formula, ω e_k f represents the harmonic suppression center frequency of the k-th group, where k represents the group number. max ω represents the highest operating frequency of the motor. c denoted by , where m represents the resonant bandwidth and m represents the number of groups in the coefficient set.

[0023] This formula takes into account factors such as the number of coefficient groups, the highest operating frequency of the motor, and the resonant bandwidth. It can accurately calculate the harmonic suppression center point frequency corresponding to each group, so that the harmonic suppression of each group can be accurately located in the corresponding frequency range, thereby improving the accuracy and effectiveness of harmonic suppression.

[0024] In some optional implementations, the values ​​of any coefficients in the coefficient group corresponding to each group are calculated based on the harmonic suppression center frequency and resonant bandwidth of each group, including:

[0025] Based on the coefficient calculation formula, the value of any coefficient in the coefficient group of each group is calculated according to the harmonic suppression center frequency and resonant bandwidth of each group. The coefficient calculation formula includes:

[0026] b 0_k =4K r ω c_k T s

[0027] b 1_k =0

[0028] b 2_k =-b 0_k

[0029] a 0_k =4+4ω c_k T s +ω0 2 T s 2

[0030] a 1_k =2ω0 2 T s 2 -8

[0031] a 2_k =4-4ω c T s +ω0 2 T s 2

[0032] In the formula, b 0_k b 1_k b 2_k a 0_k a 1_k and a 2_k K represents the coefficient in the coefficient group of the k-th group. r ω represents the resonance control coefficient. e_k T represents the harmonic suppression center frequency of the k-th group, where k represents the group number. s This represents the sampling period, and ω0 is the harmonic frequency that needs to be suppressed.

[0033] The coefficient values ​​in the corresponding coefficient group are pre-calculated using the coefficient calculation formula, which makes it convenient to directly call them when performing quasi-resonant regulation later, simplifying the calculation workload of the control process.

[0034] In some alternative implementations, obtaining the quasi-resonant adjustment amount of the quasi-resonant controller based on the input coefficient set includes:

[0035] Obtain the quasi-resonant adjustment value output by the quasi-resonant controller. The quasi-resonant controller executes a quasi-resonant control difference equation based on the coefficients in the input coefficient set, and outputs the quasi-resonant adjustment value. The quasi-resonant control difference equation is as follows:

[0036]

[0037] In the formula, b0, b1, b2, a0, a1 and a2 represent the coefficients in any group of coefficients, y(n) represents the output of the quasi-resonant controller, the output of the quasi-resonant controller is the quasi-resonant adjustment amount, u(n) represents the input of the quasi-resonant controller, and n represents the number of times the quasi-resonant controller is executed.

[0038] In this method, the quasi-resonant controller adjusts directly according to the quasi-resonant control differential equation by calling the coefficients, thus ensuring the accuracy of quasi-resonant adjustment while making rapid adjustments.

[0039] In some alternative implementations, the target control quantity is obtained by combining the quasi-resonant regulation quantity and the proportional-integral regulation quantity of the output of the proportional-integral controller, including:

[0040] The target control quantity is obtained by superimposing the quasi-resonant regulation quantity and the proportional-integral regulation quantity of the output of the proportional-integral controller.

[0041] By superimposing quasi-resonant regulation and proportional-integral regulation, the motor current can be controlled more effectively, and the current harmonic suppression effect can be improved.

[0042] In a second aspect, the present invention provides a current harmonic suppression device, comprising:

[0043] The group determination module is used to determine the target group based on the current operating frequency of the motor;

[0044] The coefficient group acquisition module is used to output the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller;

[0045] The quasi-resonance adjustment quantity acquisition module is used to acquire the quasi-resonance adjustment quantity output by the quasi-resonance controller based on the input coefficient group;

[0046] The adjustment control module is used to obtain the target control quantity by combining the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output of the proportional-integral controller.

[0047] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the current harmonic suppression method of the first aspect or any corresponding embodiment described above.

[0048] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the current harmonic suppression method of the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0049] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 This is a schematic flowchart of a current harmonic suppression method according to an embodiment of the present invention;

[0051] Figure 2 It is a software control logic diagram for motor operation control in related technologies;

[0052] Figure 3 This is a software control logic diagram of motor operation control according to an embodiment of the present invention;

[0053] Figure 4 This is a hardware schematic diagram of a motor controller in related technologies;

[0054] Figure 5 This is a flowchart illustrating another current harmonic suppression method according to an embodiment of the present invention;

[0055] Figure 6 This is a schematic diagram of the phase current FFT analysis without quasi-resonant control in an embodiment of the present invention;

[0056] Figure 7 This is a schematic diagram of the phase current FFT analysis when quasi-resonant control is added in an embodiment of the present invention;

[0057] Figure 8 This is a structural block diagram of the current harmonic suppression device in an embodiment of the present invention;

[0058] Figure 9 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Due to phenomena such as air gap magnetic field distortion and dead zone effect, a series of harmonic components exist in the operating current of permanent magnet synchronous motors. The presence of harmonics is a non-ideal situation; harmonics will worsen the sinusoidal nature of the current waveform of the permanent magnet motor. Harmonics of certain orders will cause additional torque fluctuations in the motor, introduce vibration noise, and shorten the lifespan of related components. In addition, harmonics of any order will affect the operating efficiency of the motor; higher harmonic content will reduce the motor's efficiency.

[0061] Based on the harmonic generation mechanism of permanent magnet synchronous motors (PMSMs), harmonics are mainly divided into motor-borne harmonics and nonlinear harmonics generated by power electronic devices. Motor-borne harmonics are also known as spatial harmonics, while harmonics generated by power electronic devices are called time harmonics. PMSMs have a limited number of stator slots and rotor poles, resulting in a non-standard sinusoidal rotating magnetic field generated by the stator windings during operation. Spatial harmonics are primarily influenced by factors such as cogging effect, winding distribution, magnetic saturation, and rotor pole structure. In motor control systems, the introduction of time harmonics is mainly related to the inverter. Inverters are nonlinear components. Taking a three-phase inverter system as an example, because the sinusoidal signal it generates is achieved by six switching transistors switching according to a certain pattern, coupled with dead-time effects and transistor voltage drops, its output signal is difficult to achieve a standard sinusoidal shape. Due to factors such as cogging effect and inverter nonlinearity, the 6th and 12th current harmonics of the dq axis in the motor control system are generally large (they are the 5th and 7th current harmonics in the three-phase current, but after coordinate transformation, they become the 6th current harmonic on the dq axis, and the 12th current harmonic is similar). Therefore, the embodiments of the present invention mainly suppress the 6th and 12th current harmonics of the motor dq axis.

[0062] To suppress harmonics, embodiments of the present invention provide a current harmonic suppression method that can achieve current harmonic suppression with a low computational load.

[0063] According to an embodiment of the present invention, a current harmonic suppression method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0064] This embodiment provides a current harmonic suppression method, which can be used in various types of control terminals, such as microcontroller units (MCUs), field-programmable gate arrays (FPGAs), etc. Figure 1 As shown, the process of this current harmonic suppression method includes the following steps:

[0065] Step S101: Determine the target group based on the current operating frequency of the motor.

[0066] Specifically, the operating frequencies of the motors are pre-grouped, with each group corresponding to a frequency range. The group is determined based on the frequency range in which the motor is currently operating. For example, the frequency range of each group has the same width; for instance, the first group's frequency range is 0 to 20Hz, the second group's frequency range is 20Hz to 40Hz, and so on.

[0067] It should be understood that the sum of the frequency ranges of each group should cover the entire operating frequency range of the motor, so that the corresponding target group can be determined when the motor is running at any frequency.

[0068] Step S102: Output the pre-calculated coefficient set corresponding to the target group to the quasi-resonant controller.

[0069] Step S103: Obtain the quasi-resonant adjustment amount output by the quasi-resonant controller based on the input coefficient group.

[0070] Specifically, each group corresponds to a coefficient group, and a coefficient group includes several coefficients. The coefficients in each coefficient group are calculated in advance using a coefficient calculation formula.

[0071] The coefficient calculation formula is derived by discretizing the transfer function of the quasi-resonant controller. The coefficients in the coefficient group are the parameters in the difference equation of the discretized quasi-resonant controller. After obtaining the values ​​of the coefficients, the quasi-resonant controller can directly substitute them into the difference equation to output the quasi-resonant adjustment amount.

[0072] Step S104: Combine the quasi-resonant regulation quantity and the proportional-integral regulation quantity output by the proportional-integral controller to obtain the target control quantity.

[0073] In related technologies, such as Figure 2 As shown, the motor's current loop is implemented using a proportional-integral (PI) controller, which controls the target d-axis current i. * d Target q-axis current i * qThe real-time d-axis current i is obtained by sampling. d Real-time q-axis current i q The corresponding proportional-integral controllers are input to obtain the dq-axis voltage control signals. The q-axis voltage control signals are then transformed into IPARK coordinates to obtain the three-phase voltage control signals, thereby realizing the control of the motor.

[0074] Figure 4 The diagram shows the controller hardware. First, three-phase or single-phase AC power is input, which is rectified and filtered by the bus capacitor to obtain a stable DC voltage. Then, the inverter bridge switches on and off under the drive signal from the control terminal, inverting the DC voltage. Finally, the inverted AC voltage is output to the motor for control.

[0075] Resonant control originates from the internal mode principle and is mainly used to solve the problem of zero steady-state error tracking of sinusoidal signals. The resonant element usually acts as the internal mode of a sinusoidal signal at a specific frequency, enabling the inverter to regulate the sinusoidal AC signal without steady-state error in the control loop. For example... Figure 3 As shown, in this embodiment of the invention, based on the current loop PI control of related technologies, a quasi-resonant (QR) controller is connected in parallel to suppress the 6th harmonic in the dq axis current.

[0076] Specifically, the target control quantity is obtained by superimposing the quasi-resonant regulation quantity and the proportional-integral regulation quantity output by the proportional-integral controller.

[0077] By superimposing quasi-resonant regulation and proportional-integral regulation, the motor current can be controlled more effectively, and the current harmonic suppression effect can be improved.

[0078] The current harmonic suppression method of this invention determines the target group based on the current operating frequency of the motor, outputs the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller, obtains the quasi-resonant adjustment amount output by the quasi-resonant controller based on the input coefficient group, and obtains the target control amount by combining the quasi-resonant adjustment amount and the proportional-integral adjustment amount output by the proportional-integral controller. The quasi-resonant adjustment amount is obtained by calling the coefficient group according to the target group corresponding to the current operating frequency of the motor. The control process does not require a large number of coefficient calculations, which can greatly reduce the amount of calculation and avoid a large amount of calculation occupying the FOC interrupt execution time. Moreover, it can be implemented on a low-cost controller, reducing the control cost.

[0079] In this embodiment of the invention, the coefficient groups are pre-calculated and stored before adjustment. When the motor operates at different speeds, different coefficient groups can be called to achieve full speed range coverage, simplifying operation and realizing quasi-resonant control of a low-cost microcontroller. In some embodiments, the calculation steps for any group of coefficients include:

[0080] Step S201: Determine the number of groups in the coefficient group based on the highest operating frequency of the motor.

[0081] Specifically, the highest operating frequency of the motor is divided by the resonant bandwidth to obtain the number of groups of coefficients. The center point of each group is the corresponding harmonic suppression center point frequency, and the frequency bandwidth of each group is the resonant bandwidth.

[0082] Choosing a resonant bandwidth that is too large will result in a poorer suppression effect, while choosing one that is too small will lead to too many coefficient sets to be calculated. Therefore, it is necessary to select an appropriate resonant bandwidth, which ranges from 15Hz×2×π to 25Hz×2×π. Ideally, the resonant bandwidth ω c Options include:

[0083] ω c =20Hz×2×π

[0084] If the maximum operating frequency of the motor is 100Hz, then during program initialization, five sets of coefficients can be calculated based on the motor's operating frequencies of 10Hz, 30Hz, 50Hz, 70Hz, and 90Hz as harmonic suppression frequencies. Taking a motor operating frequency of 10Hz as an example, the harmonic to be suppressed is the 6th harmonic, in which case:

[0085]

[0086] ω0 represents the harmonic frequency that needs to be suppressed.

[0087] This method can quickly divide the coefficient groups into groups and determine the number of groups based on the motor parameters, providing a clear basis for subsequent calculation of the relevant parameters of each group.

[0088] Step S202: Determine the harmonic suppression center point frequency of each group based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth.

[0089] Specifically, based on the center point frequency calculation formula, the harmonic suppression center point frequency for each group is determined according to the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth. The center point frequency calculation formula includes:

[0090] ω e_k =2*π*(k-1)f max / m+ω c / 2, k = 1, 2...m

[0091] In the formula, ω e_k f represents the harmonic suppression center frequency of the k-th group, where k represents the group number. max ω represents the highest operating frequency of the motor. c denoted by , where m represents the resonant bandwidth and m represents the number of groups in the coefficient set.

[0092] When the resonant bandwidth ω c =20Hz × 2 × π, maximum operating frequency of the motor f max If the frequency is 100Hz, it is divided into 5 groups with 5 harmonic suppression center point frequencies, namely 10Hz, 30Hz, 50Hz, 70Hz, and 90Hz. The corresponding frequencies of the first to fifth groups are 0-20Hz, 20-40Hz, 40-60Hz, 60-80Hz, and 80-100Hz. The corresponding group is obtained according to the frequency range in which the motor is currently operating.

[0093] This formula takes into account factors such as the number of coefficient groups, the highest operating frequency of the motor, and the resonant bandwidth. It can accurately calculate the harmonic suppression center point frequency corresponding to each group, so that the harmonic suppression of each group can be accurately located in the corresponding frequency range, thereby improving the accuracy and effectiveness of harmonic suppression.

[0094] Step S203: Calculate the value of any coefficient in the coefficient group of the corresponding group based on the harmonic suppression center point frequency and resonant bandwidth of each group.

[0095] Specifically, based on the coefficient calculation formula, the value of any coefficient in the coefficient group of each group is calculated according to the harmonic suppression center frequency and resonant bandwidth of each group. The coefficient calculation formula includes:

[0096] b 0_k =4K r ω c_k T s

[0097] b 1_k =0

[0098] b 2_k =-b 0_k

[0099] a 0_k =4+4ω c_k T s +ω0 2 T s 2

[0100] a 1_k =2ω0 2 T s 2 -8

[0101] a 2_k =4-4ω c T s +ω0 2 T s 2

[0102] In the formula, b 0_k b 1_k b 2_k a 0_k a 1_k and a 2_k K represents the coefficient in the coefficient group of the k-th group. r ω represents the resonance control coefficient. e_k T represents the harmonic suppression center frequency of the k-th group, where k represents the group number. s This represents the sampling period, and ω0 is the harmonic frequency that needs to be suppressed.

[0103] The coefficient values ​​in the corresponding coefficient group are pre-calculated using the coefficient calculation formula, which makes it convenient to directly call them when performing quasi-resonant regulation later, simplifying the calculation workload of the control process.

[0104] The embodiments of the present invention can ensure that current harmonic suppression can be performed based on a reasonable coefficient group under different groups, thereby improving the effectiveness of the entire harmonic suppression method.

[0105] In some embodiments, step S103, obtaining the quasi-resonant adjustment amount output by the quasi-resonant controller based on the input coefficient set, includes:

[0106] Obtain the quasi-resonant adjustment value output by the quasi-resonant controller. The quasi-resonant controller executes a quasi-resonant control difference equation based on the coefficients in the input coefficient set, and outputs the quasi-resonant adjustment value. The quasi-resonant control difference equation is as follows:

[0107]

[0108] In the formula, b0, b1, b2, a0, a1 and a2 represent the coefficients in any group of coefficients, y(n) represents the output of the quasi-resonant controller, the output of the quasi-resonant controller is the quasi-resonant adjustment amount, u(n) represents the input of the quasi-resonant controller, and n represents the number of times the quasi-resonant controller is executed.

[0109] The quasi-resonant controller adjusts directly according to the quasi-resonant control differential equation by calling the coefficients, ensuring the accuracy of quasi-resonant adjustment while making rapid adjustments.

[0110] The overall working principle of the embodiments of the present invention will be explained below:

[0111] Resonant control originates from the internal mode principle and is mainly used to solve the problem of zero steady-state error tracking of sinusoidal signals. The resonant element usually serves as the internal mode of a sinusoidal signal at a specific frequency, enabling the inverter to regulate the sinusoidal AC signal without steady-state error in the control loop. The most important idea of ​​this invention is to connect a quasi-resonant controller in parallel on the basis of traditional current loop PI control to suppress the 6th harmonic in the dq axis current.

[0112] The transfer function G of the resonant controller r (s) is:

[0113]

[0114] In the formula, K r ω0 is the resonance control coefficient, ω0 is the resonance frequency, i.e. the harmonic frequency that needs to be suppressed, and s represents the differential operator.

[0115] In practical control systems, resonant controllers are difficult to implement in both analog and digital systems. This is due to parameter errors in analog components and truncation errors in digital sampling. Furthermore, the resonant frequency gain band of an ideal resonant controller is very narrow, causing a sharp drop in gain outside the resonant frequency. When applied to motor control systems, fluctuations in motor speed can cause a shift in the fundamental frequency, leading to a deterioration in the motor's dynamic response due to the original resonant term. Therefore, an improved quasi-resonant controller is generally used instead of the ideal resonant controller, with the following transfer function:

[0116]

[0117] To implement the quasi-resonant controller in embedded microcontroller code, the transfer function of the quasi-resonant controller needs to be discretized.

[0118] Discretization is performed using a bilinear transform, let:

[0119]

[0120] Here, z represents a complex variable. Substituting this into the transfer function G... r In (s):

[0121]

[0122] Further simplification yields:

[0123]

[0124] Simplified to the standard second-order discretization form:

[0125]

[0126] In the formula: b0 = 4K r ω c T, b1=0, b2=-b0, a0=4+4ω c T s +ω0 2 T s 2 a1=2ω0 2 T s2 -8, a2=4-4ω c T s +ω0 2 T s 2 .

[0127] Typically, the denominator of a discrete transfer function is normalized to facilitate its subsequent writing in the form of a difference equation, i.e., written as

[0128]

[0129] The final quasi-resonant control difference equation can be obtained as follows:

[0130]

[0131] From the above derivation, it can be seen that the final quasi-resonant control includes three parameters, namely the resonant control coefficient K. r Resonant frequency ω0, resonant bandwidth ω c Resonance control coefficient K r and resonant bandwidth ω c Generally, a fixed value is used. The resonant frequency ω0 is the harmonic frequency that needs to be suppressed. To suppress the 6th harmonic in the fundamental frequency, we have ω0 = 6ω e ω e This represents the actual electrical angular velocity of the motor. To effectively suppress harmonics across all operating frequencies of the motor, coefficients b0, b1, b2, a0, a1, and a2 need to be calculated in real time. It is evident from the derivation of these coefficients that the computational load is substantial, involving numerous divisions and placing high demands on the microcontroller chip.

[0132] To reduce the time spent by the microcontroller calculating the quasi-resonant controller coefficients during FOC operation, this invention proposes a current harmonic suppression method to select the resonant bandwidth ω. c =20Hz×2×π is used for explanation, such as Figure 5 As shown, the method includes the following steps:

[0133] Step 1: Based on the motor's maximum operating frequency f max Determine the number of groups m in the coefficient group, and the highest frequency is the highest operating frequency according to the motor nameplate standard.

[0134] Step 2: Based on the number of groups m in the coefficient group and the maximum operating frequency f of the motor... max and resonant bandwidth ω c The harmonic suppression center frequency for each group is determined using the following formula:

[0135] ω e_k =2*π*(k-1)f max / m+ω c / 2, k = 1, 2...m

[0136] If the maximum operating frequency of the motor is f max If the frequency is 100Hz, it is divided into 5 groups with 5 harmonic suppression center point frequencies: 10Hz, 30Hz, 50Hz, 70Hz, and 90Hz. The corresponding frequencies for the first to fifth groups are 0-20Hz, 20-40Hz, 40-60Hz, 60-80Hz, and 80-100Hz.

[0137] Step 3: Separate m groups of ω e_k and ω c Substituting these values ​​into the previously derived coefficient calculation formula, we obtain m sets of coefficient values, {a 0_k a 1_k a 2_k b 0_k b 1_k b 2_k}, k = 1, 2...m.

[0138] Step 4: Determine the group of the current motor operating frequency.

[0139] Step 5: Assign the coefficient group corresponding to the group to the quasi-resonant controller, i.e., the QR controller.

[0140] Step 6: Execute the QR controller algorithm and superimpose the output adjustment onto the original PI controller.

[0141] The motor is controlled to run at 60Hz, and FFT analysis is performed on the motor phase currents. Without quasi-resonant control, the FFT analysis results are as follows. Figure 6 After incorporating quasi-resonant control, the phase current FFT analysis results are as follows: Figure 7 As shown.

[0142] Based on the comparison results, the following two conclusions can be drawn:

[0143] 1. Without quasi-resonant control, the phase current THD is 4.2%. After adding resonant control, the phase current THD decreases to 3.34%. Therefore, adding resonant control can effectively reduce the phase current THD.

[0144] 2. Without quasi-resonant control, the 5th and 7th harmonic currents (300Hz and 420Hz) of the phase current contain approximately 1.3%. After incorporating quasi-resonant control, the 5th and 7th harmonic currents (300Hz and 420Hz) of the phase current contain approximately 0.5%. Therefore, incorporating quasi-harmonic control can effectively suppress the specified harmonic orders.

[0145] This invention also provides a current harmonic suppression device, such as... Figure 8 As shown, it includes:

[0146] The group determination module 101 is used to determine the target group based on the current operating frequency of the motor.

[0147] The coefficient group acquisition module 102 is used to output the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller;

[0148] The quasi-resonance adjustment quantity acquisition module 103 is used to acquire the quasi-resonance adjustment quantity output by the quasi-resonance controller based on the input coefficient group;

[0149] The adjustment control module 104 is used to obtain the target control quantity by combining the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output by the proportional-integral controller.

[0150] The current harmonic suppression device of this invention determines the target group based on the current operating frequency of the motor, outputs the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller, obtains the quasi-resonant adjustment amount output by the quasi-resonant controller based on the input coefficient group, and obtains the target control amount by combining the quasi-resonant adjustment amount and the proportional-integral adjustment amount output by the proportional-integral controller. The quasi-resonant adjustment amount is obtained by calling the coefficient group according to the target group corresponding to the current operating frequency of the motor. In the control process, a large number of coefficient calculations are not required, which can greatly reduce the amount of calculation and avoid a large amount of calculation occupying the FOC interrupt execution time. Moreover, it can be implemented on a low-cost controller, reducing control costs.

[0151] Furthermore, the current harmonic suppression device also includes a coefficient group calculation module, which includes:

[0152] The group number determination module is used to determine the number of groups for the coefficient group based on the highest operating frequency of the motor.

[0153] The center point frequency determination module is used to determine the harmonic suppression center point frequency of each group based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth.

[0154] The coefficient calculation module is used to calculate the value of any coefficient in the coefficient group of each group based on the harmonic suppression center point frequency and resonant bandwidth of each group.

[0155] Furthermore, the group number determination module is also used for:

[0156] Divide the motor’s highest operating frequency by the resonant bandwidth to obtain the number of groups of coefficients. The center point of each group is the corresponding harmonic suppression center point frequency, and the frequency bandwidth of each group is the resonant bandwidth.

[0157] Furthermore, the center point frequency determination module is also used for:

[0158] Based on the center point frequency calculation formula, the harmonic suppression center point frequency for each group is determined according to the number of coefficient groups, the highest operating frequency of the motor, and the resonant bandwidth. The center point frequency calculation formula includes:

[0159] ω e_k =2*π*(k-1)f max / m+ω c / 2, k = 1, 2...m

[0160] In the formula, ω e_k f represents the harmonic suppression center frequency of the k-th group, where k represents the group number. max ω represents the highest operating frequency of the motor. c denoted by , where m represents the resonant bandwidth and m represents the number of groups in the coefficient set.

[0161] Furthermore, the coefficient calculation module is also used for:

[0162] Based on the coefficient calculation formula, the value of any coefficient in the coefficient group of each group is calculated according to the harmonic suppression center frequency and resonant bandwidth of each group. The coefficient calculation formula includes:

[0163] b 0_k =4K r ω c_k T s

[0164] b 1_k =0

[0165] b 2_k =-b 0_k

[0166] a 0_k =4+4ω c_k T s +ω0 2 T s 2

[0167] a 1_k =2ω0 2 T s 2 -8

[0168] a 2_k =4-4ω c T s +ω0 2 T s 2

[0169] In the formula, b 0_k b 1_k b 2_k a0_k a 1_k and a 2_k K represents the coefficient in the coefficient group of the k-th group. r ω represents the resonance control coefficient. e_k T represents the harmonic suppression center frequency of the k-th group, where k represents the group number. s This represents the sampling period, and ω0 is the harmonic frequency that needs to be suppressed.

[0170] Furthermore, the quasi-resonant adjustment quantity acquisition module is also used for:

[0171] Obtain the quasi-resonant adjustment value output by the quasi-resonant controller. The quasi-resonant controller executes a quasi-resonant control difference equation based on the coefficients in the input coefficient set, and outputs the quasi-resonant adjustment value. The quasi-resonant control difference equation is as follows:

[0172]

[0173] In the formula, b0, b1, b2, a0, a1 and a2 represent the coefficients in any group of coefficients, y(n) represents the output of the quasi-resonant controller, the output of the quasi-resonant controller is the quasi-resonant adjustment amount, u(n) represents the input of the quasi-resonant controller, and n represents the number of times the quasi-resonant controller is executed.

[0174] Furthermore, the adjustment and control module is also used for:

[0175] The target control quantity is obtained by superimposing the quasi-resonant regulation quantity and the proportional-integral regulation quantity of the output of the proportional-integral controller.

[0176] This invention also provides a schematic diagram of the structure of a computer device, such as... Figure 9 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 9 Take a processor 10 as an example.

[0177] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0178] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0179] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0180] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0181] The computer device also includes an input device 30 and an output device 40. The processor 10, memory 20, input device 30, and output device 40 can be connected via a bus or other means. Figure 9 Taking the example of a connection between China and Israel via a bus.

[0182] Input device 30 can receive input numerical or character information, and generate key signal inputs related to user settings and function control of the computer device, such as a touchscreen, keypad, mouse, trackpad, touchpad, joystick, one or more mouse buttons, trackball, joystick, etc. Output device 40 may include display devices, auxiliary lighting devices (e.g., LEDs), and haptic feedback devices (e.g., vibration motors). The aforementioned display devices include, but are not limited to, liquid crystal displays, light-emitting diodes, displays, and plasma displays. In some alternative embodiments, the display device may be a touchscreen.

[0183] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0184] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0185] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope of protection.

Claims

1. A method for suppressing current harmonics, characterized in that, include: Determine the target group based on the current operating frequency of the motor; The pre-calculated coefficient set corresponding to the target group is output to the quasi-resonant controller; Obtain the quasi-resonant adjustment value of the quasi-resonant controller output based on the coefficient set of the input, where the coefficients in the coefficient set are the coefficients in the quasi-resonant control difference equation; The target control quantity is obtained by combining the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output by the proportional-integral controller.

2. The current harmonic suppression method according to claim 1, characterized in that, The steps for calculating the coefficient group of any group include: The number of groups in the coefficient group is determined based on the highest operating frequency of the motor. The harmonic suppression center point frequency of each group is determined based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth. Calculate the value of any coefficient in the coefficient group corresponding to each group based on the harmonic suppression center frequency and resonant bandwidth of each group.

3. The current harmonic suppression method according to claim 2, characterized in that, The determination of the number of groups for the coefficient group based on the highest operating frequency of the motor includes: Divide the highest operating frequency of the motor by the resonant bandwidth to obtain the number of groups of coefficients. The center point of each group is the corresponding harmonic suppression center point frequency, and the frequency bandwidth of each group is the resonant bandwidth.

4. The current harmonic suppression method according to claim 2, characterized in that, The determination of the harmonic suppression center point frequency for each group based on the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth includes: Based on the center point frequency calculation formula, the harmonic suppression center point frequency for each group is determined according to the number of groups in the coefficient group, the highest operating frequency of the motor, and the resonant bandwidth. The center point frequency calculation formula includes: In the formula, Indicates the first The harmonic suppression center frequency of each group Indicates the group number. Indicates the maximum operating frequency of the motor. Indicates the resonant bandwidth. This indicates the number of groups in the coefficient set.

5. The current harmonic suppression method according to claim 2, characterized in that, The calculation of the value of any coefficient in the coefficient group corresponding to each group based on the harmonic suppression center frequency and resonant bandwidth includes: Based on the coefficient calculation formula, the value of any coefficient in the coefficient group of each group is calculated according to the harmonic suppression center point frequency and resonant bandwidth of each group. The coefficient calculation formula includes: In the formula, , , , , and Indicates the first The coefficients of each group. This represents the resonance control coefficient. Indicates the first The harmonic suppression center frequency of each group Indicates the group number. Indicates the sampling period. The harmonic frequencies that need to be suppressed.

6. The current harmonic suppression method according to claim 5, characterized in that, Obtaining the quasi-resonant adjustment value of the quasi-resonant controller based on the input coefficient set includes: Obtain the quasi-resonant adjustment value output by the quasi-resonant controller. The quasi-resonant controller executes a quasi-resonant control difference equation based on the coefficients in the input coefficient set, and outputs the quasi-resonant adjustment value. The quasi-resonant control difference equation is as follows: In the formula, , , , , and This represents the coefficients in any group of coefficients. This represents the output of the quasi-resonant controller, which is the quasi-resonant adjustment value. This represents the input of the quasi-resonant controller. This indicates the number of times the quasi-resonant controller has been executed.

7. The current harmonic suppression method according to claim 1, characterized in that, The process of obtaining the target control quantity by combining the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output of the proportional-integral controller includes: The target control quantity is obtained by superimposing the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output by the proportional-integral controller.

8. A current harmonic suppression device, characterized in that, include: The group determination module is used to determine the target group based on the current operating frequency of the motor; The coefficient group acquisition module is used to output the pre-calculated coefficient group corresponding to the target group to the quasi-resonant controller, wherein the coefficients in the coefficient group are the coefficients in the quasi-resonant control difference equation; The quasi-resonance adjustment quantity acquisition module is used to acquire the quasi-resonance adjustment quantity output by the quasi-resonance controller based on the input coefficient group; The adjustment control module is used to obtain the target control quantity by combining the quasi-resonant adjustment quantity and the proportional-integral adjustment quantity output by the proportional-integral controller.

9. A computer device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the current harmonic suppression method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to perform the current harmonic suppression method according to any one of claims 1 to 7.

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