Gallium nitride totem-pole bridgeless PFC converter grid-side current harmonic self-adaptive suppression method

Abstract

The invention discloses a gallium nitride totem-pole bridgeless PFC converter grid-side current harmonic self-adaptive suppression method, and belongs to the technical field of PFC converter harmonic suppression. The invention aims to solve the problem that the EMI filter of the gallium nitride totem-pole bridgeless PFC converter introduces current harmonics. Comprising the following steps: 1, establishing a system admittance model, and designing initial virtual admittance parameters according to an established theoretical model; 2, on the basis of the virtual admittance parameters, selecting a proper taboo table and step length in combination with a taboo search algorithm; and 3, constructing a virtual admittance at the target harmonic frequency according to the calculated initial parameter to improve the damping characteristic of the system, and obtaining an equivalent current by combining a tabu search algorithm through input voltage harmonic information extraction and combining current given and modulation voltage information to realize adaptive active damping control of the converter system. And therefore, the grid-side current harmonics are suppressed. The method is used for suppressing the grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter.

Description

Technical Field

[0001] The present invention relates to a method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter, belonging to the technical field of harmonic suppression of PFC converters. Background Art

[0002] Air conditioner compressor drivers are mainly divided into three parts: a rectifier circuit, a power factor correction (PFC) circuit, and an inverter circuit. Among them, the PFC circuit can suppress the pollution of the converter harmonics to the power grid and is an important part of the compressor driver.

[0003] The totem-pole bridgeless PFC converter has been widely used due to its high frequency and high efficiency characteristics. In order to prevent the harmonic current of the converter switching frequency from flowing into the power grid, an EMI filter is usually required on the grid side of the totem-pole bridgeless PFC converter. Among them, the differential-mode inductor and differential-mode capacitor constitute an LC filter network. In practical applications, affected by the load and transmission line, the grid voltage contains certain harmonic components. This part of the harmonics will be converted into harmonic currents after passing through the converter, and the amplitude of the harmonic currents near the LC resonance frequency increases, increasing the THD of the grid-side current. Therefore, it is necessary to take harmonic suppression measures in the converter to improve the grid-side power quality.

[0004] The main suppression measures for grid-side current harmonics include two categories: harmonic suppression methods based on passive damping and harmonic suppression methods based on active damping. The suppression method based on passive damping suppresses current harmonics by directly increasing the system damping, generally achieved by connecting a resistor in series with the filter capacitor. This method does not affect the control part and has a good harmonic suppression effect, but it increases the hardware complexity of the system and increases the system loss. The active damping method can be mainly divided into two categories from the control perspective. One is the method of adding a digital filter; in practical applications, this method is very sensitive to parameter changes, and it is difficult to accurately design the relevant parameters. The other is the method of adding state variable feedback, which is easily affected by digital delay, and when the system impedance changes or the power range is wide, the suppression effect will become worse. Therefore, it is necessary to further study an active damping current harmonic suppression method applicable to a wide load range. Summary of the Invention

[0005] Aiming at the problem of current harmonics introduced by the EMI filter of the gallium nitride totem-pole bridgeless PFC converter, the present invention provides a method for adaptively suppressing grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter.

[0006] A method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to the present invention includes:

[0007] Establish a system input admittance model of the air-conditioning compressor driver, design the initial amplitude and initial phase of the virtual admittance, and at the same time determine the current reference component at the target frequency and the harmonic transfer function of the grid-side voltage, and the modulation voltage reference component at the target frequency and the harmonic transfer function of the grid-side voltage;

[0008] Design the iteration step size and the length of the taboo table of the taboo search algorithm according to the initial amplitude and initial phase of the virtual admittance;

[0009] Starting from the initial value of the virtual admittance, execute the taboo search algorithm in combination with the iteration step size and the length of the taboo table. By continuously iterating the virtual admittance amplitude and virtual admittance phase, obtain the optimal solution of the virtual admittance; perform damping distribution in combination with the current reference component at the target frequency and the harmonic transfer function of the grid-side voltage and the modulation voltage reference component at the target frequency and the harmonic transfer function of the grid-side voltage; obtain the target virtual admittance according to the damping distribution result, and obtain the target virtual admittance current; calculate the current reference component at the target frequency and the modulation voltage reference component at the target frequency from the target virtual admittance current; calculate the control signal of the PWM link based on the current reference component at the target frequency and the modulation voltage reference component at the target frequency, so as to realize the adaptive active damping control of the PFC converter, and further realize the suppression of grid-side current harmonics.

[0010] According to the method for adaptively suppressing grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter of the present invention, the system input admittance model is:

[0011]

[0012] In the formula, Y g_d is the system input admittance, s is a complex variable, i g_d is the harmonic current at the target frequency, u g_d is the harmonic voltage at the target frequency, Y is the input admittance of the GaN totem-pole bridgeless PFC converter, Y DM is the differential-mode capacitance admittance, Y d is the virtual admittance, L DM is the differential-mode inductor in the EMI filter, R g is the line resistance of the GaN totem-pole bridgeless PFC converter.

[0013] According to the method for adaptively suppressing grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter of the present invention, the method for designing the initial amplitude and initial phase of the virtual admittance is:

[0014] Based on formula (1), take the virtual admittance amplitude and phase corresponding to the minimum amplitude of Y g_d as the initial amplitude and initial phase of the virtual admittance.

[0015] For the method of adaptively suppressing grid-side current harmonics of a GaN totem-pole bridgeless PFC converter according to the present invention, the methods for determining the current reference component at the target frequency and the harmonic transfer function between the grid-side voltage, and the modulation voltage reference component at the target frequency and the harmonic transfer function between the grid-side voltage are as follows:

[0016] Express the virtual admittance Y d as:

[0017]

[0018] where |Y d | is the magnitude of the virtual admittance, is the phase of the virtual admittance, ω d is the target frequency;

[0019]

[0020] where G d1 is the harmonic transfer function between the current reference component at the target frequency and the grid-side voltage, G d2 is the harmonic transfer function between the modulation voltage reference component at the target frequency and the grid-side voltage, K is is the current feedback coefficient, 1 / V m is the gain of the PWM link, L is the boost inductor of the GaN totem-pole bridgeless PFC converter, U dc is the DC part of the output voltage of the GaN totem-pole bridgeless PFC converter.

[0021] For the method of adaptively suppressing grid-side current harmonics of a GaN totem-pole bridgeless PFC converter according to the present invention, the design method for the iteration step size of the tabu search algorithm is as follows:

[0022]

[0023] where Δd1 is the magnitude iteration step size, Δd2 is the phase iteration step size, |Y init | is the initial magnitude of the virtual admittance, is the initial phase of the virtual admittance, and x is the step size adjustment coefficient.

[0024] For the method of adaptively suppressing grid-side current harmonics of a GaN totem-pole bridgeless PFC converter according to the present invention, the design method for the length of the tabu list of the tabu search algorithm is as follows:

[0025] Determine the length of the tabu list according to the requirement for the ability to identify the local optimal solution of the virtual admittance and the requirement for the accuracy of the global optimal solution.

[0026] For the method of adaptively suppressing grid-side current harmonics of a GaN totem-pole bridgeless PFC converter according to the present invention, the execution process of the tabu search algorithm is as follows:

[0027] Taking the virtual admittance amplitude |Y d | as the abscissa and the virtual admittance phase as the ordinate, perform the tabu search algorithm separately in two directions through neighborhood search; combined with the set iteration boundary, continuously iterate to search for high-quality solutions near the initial value of the virtual admittance until the optimal solution of the virtual admittance is obtained.

[0028] According to the method for adaptively suppressing the grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter of the present invention, the iterative process of the virtual admittance is expressed as:

[0029]

[0030] In the formula is the candidate solution set of the virtual admittance obtained after the 2m-th iteration, where m is a positive integer; is the amplitude of the virtual admittance in the 2m-th iteration, is the phase of the virtual admittance in the 2m-th iteration, d 2m is the difference between the candidate solution of the virtual admittance obtained in the 2m-th iteration and the initial value of the virtual admittance;

[0031]

[0032] In the formula, Δh 2m is the current harmonic change value in the 2m-th iteration, is the amplitude change value of the virtual admittance Y d within 2m iterations, is the phase change value of the virtual admittance Y d within 2m + 1 iterations;

[0033]

[0034] In the formula is the maximum value of the current harmonics in the 2m-th iteration.

[0035] According to the method for adaptively suppressing the grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter of the present invention, the method for determining the virtual admittance based on the iteration boundary is:

[0036]

[0037] In the formula, Y max is the upper limit value of the iteration boundary, and Y min is the lower limit value of the iteration boundary.

[0038] According to the method for adaptively suppressing the grid-side current harmonics of the gallium nitride totem-pole bridgeless PFC converter of the present invention, the equivalent admittance Y d1 generated by the current reference command component obtained by damping distribution and the equivalent admittance Y generated by the modulation voltage reference command componentd2 :

[0039]

[0040] where G ic is the transfer function of the current controller, and G id is the transfer function of the inductor current and duty ratio, and T i is the loop gain transfer function;

[0041] T i = K is G ic G id / V m ;

[0042] The target virtual admittance is determined by the sum of the equivalent admittance Y d1 and the equivalent admittance Y d2 .

[0043] Advantages of the present invention: The method of the present invention relates to the suppression of grid-side current harmonics in a GaN totem-pole bridgeless PFC converter, and can improve the problem of the degradation of the grid-side current quality caused by the introduction of current harmonics by the EMI filter. Based on the establishment of the input admittance model of the GaN totem-pole bridgeless PFC converter, the amplitude and phase parameters of the initial virtual admittance are designed, and the command components of the current and voltage set values and the grid-side voltage harmonic transfer function are determined. The iteration step size of the algorithm and the length of the taboo table are designed according to the amplitude and phase parameters of the initial virtual admittance. According to the calculated initial parameters, the virtual admittance is constructed at the target harmonic frequency to improve the damping characteristics of the system. Combining the taboo search algorithm, the equivalent current is obtained by extracting the input voltage harmonic information and combining the current set value and the modulation voltage information, realizing the adaptive active damping control of the converter system, thereby suppressing the grid-side current harmonics.

[0044] The present invention applies the adaptive virtual impedance technology to the suppression of grid-side current harmonics in a GaN totem-pole bridgeless PFC converter to solve the problem that the harmonic suppression effect of the traditional strategy is limited by the load range. Brief Description of the Drawings

[0045] Figure 1 is the overall block diagram of the method for adaptively suppressing grid-side current harmonics of the GaN totem-pole bridgeless PFC converter described in the present invention; in the figure, u g , u in and u dc are the grid-side input voltage, the converter input voltage, and the bus voltage respectively, and i g and i Lare the input current and the boost inductor current respectively. Q1 and Q2 are two high-frequency switches in the totem-pole bridgeless PFC converter. Q3 and Q4 are two low-frequency switches respectively. L and C are the boost inductor and the bus capacitor respectively. ADC is the analog-to-digital converter. PLL is the phase-locked loop. sin represents the sin value for solving the phase of the converter input voltage. ZCD is the zero-crossing detection section. PWM is the pulse width modulator. BPF is the band-pass filter; Y init and |Y init |, φ init are the initial virtual admittance in parallel, the initial amplitude of the virtual admittance, and the initial phase of the virtual admittance respectively. i ref and i vco and u ref are the reference current, the output current of the voltage controller, and the reference voltage respectively. d f is the duty cycle signal. G vc and G ic are the transfer function of the voltage controller and the transfer function of the current controller respectively;

[0046] Figure 2 is the system admittance amplitude characteristic diagram at the target frequency under different virtual admittance amplitude and phase parameter conditions; in the figure, |Yg_d| represents the system admittance amplitude at the target frequency;

[0047] Figure 3 is the experimental waveform diagram of the virtual admittance calculation process under the condition of 200W;

[0048] Figure 4 is Figure 3 the enlarged experimental comparison waveform diagram before and after enabling the method of the present invention in

[0049] Figure 5 is Figure 4 the FFT analysis comparison result of the grid-side voltage and current before and after enabling the method of the present invention in

[0050] Figure 6 is the comparison result diagram of the grid-side current harmonic amplitude at the target frequency before and after enabling the method of the present invention under different power conditions; in the figure, |ig_d| represents the grid-side current harmonic amplitude. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0052] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0053] The present invention will be further described below in conjunction with the accompanying drawings, but it is not a limitation of the present invention.

[0054] Combined with Figure 1 and Figure 2 As shown, the present invention provides a method for adaptively suppressing the grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter, including

[0055] Establish a system input admittance model of the air conditioner compressor driver, design the initial amplitude and initial phase of the virtual admittance, and at the same time determine the current reference command component at the target frequency and the grid-side voltage harmonic transfer function and the modulation voltage reference command component and the grid-side voltage harmonic transfer function;

[0056] Design the iteration step size and the length of the taboo list of the taboo search algorithm according to the initial amplitude and initial phase of the virtual admittance;

[0057] Starting from the initial value of the virtual admittance, execute the taboo search algorithm in combination with the iteration step size and the length of the taboo list. By continuously iterating the virtual admittance amplitude and virtual admittance phase, obtain the optimal solution of the virtual admittance; perform damping distribution in combination with the current reference command component and the grid-side voltage harmonic transfer function and the modulation voltage reference command component and the grid-side voltage harmonic transfer function; obtain the target virtual admittance according to the damping distribution result, and obtain the target virtual admittance current; calculate the current reference command component at the target frequency and the modulation voltage reference command component at the target frequency from the target virtual admittance current; calculate the control signal of the PWM link based on the current reference command component at the target frequency and the modulation voltage reference command component at the target frequency, so as to realize the adaptive active damping control of the PFC converter, and further realize the suppression of the grid-side current harmonics.

[0058] In this embodiment, a system admittance model is first established, and the initial virtual admittance parameters are designed according to the established theoretical model; then, on the basis of the virtual admittance parameters, a suitable taboo list and step size are selected in combination with the taboo search algorithm; then, according to the calculated initial parameters, a virtual admittance is constructed at the target harmonic frequency to improve the damping characteristics of the system. In combination with the taboo search algorithm, the equivalent current is obtained by extracting the input voltage harmonic information and combining the current reference and modulation voltage information, so as to realize the adaptive active damping control of the converter system, thereby suppressing the grid-side current harmonics.

[0059] Furthermore, the system input admittance model is:

[0060]

[0061] Where Y g_dis the system input admittance, s is a complex variable, and i g_d is the harmonic current at the target frequency, and u g_d is the harmonic voltage at the target frequency, Y is the input admittance of the GaN totem-pole bridgeless PFC converter, and Y DM is the differential-mode capacitance admittance, and Y d is the virtual admittance, and L DM is the differential-mode inductor in the EMI filter, and R g is the line resistance of the GaN totem-pole bridgeless PFC converter.

[0062] The method for designing the initial amplitude and initial phase of the virtual admittance is as follows:

[0063] Based on Equation (1), when the amplitude of Y g_d is the smallest, the corresponding virtual admittance amplitude and phase are used as the initial amplitude and initial phase of the virtual admittance.

[0064] The method for determining the harmonic transfer function of the current set value command component and the grid-side voltage at the target frequency and the harmonic transfer function of the modulation voltage set value command component and the grid-side voltage is as follows:

[0065] Express the virtual admittance Y d as:

[0066]

[0067] where |Y d | is the virtual admittance amplitude, is the virtual admittance phase, ω d is the target frequency;

[0068] Use a filter to obtain the input voltage at ω d . Calculate the target virtual admittance current according to the virtual admittance, and then convert it into the converter current set value command and the modulation voltage command. By combining the two, the equivalent virtual admittance current at ω d is obtained to achieve the control effect of active damping.

[0069]

[0070] where G d1 is the harmonic transfer function of the current set value command component and the grid-side voltage at the target frequency, G d2 is the harmonic transfer function of the modulation voltage set value command component and the grid-side voltage at the target frequency, K is is the current feedback coefficient, 1 / V m is the PWM link gain, L is the boost inductor of the GaN totem-pole bridgeless PFC converter, and U dc is the DC part of the output voltage of the GaN totem-pole bridgeless PFC converter.

[0071] Furthermore, the design method of the iteration step size of the tabu search algorithm is as follows:

[0072]

[0073] In the formula, Δd1 is the amplitude iteration step size, and Δd2 is the phase iteration step size, that is, the amplitude and phase search radii for a single iteration; |Y init | is the initial amplitude of the virtual admittance, is the initial phase of the virtual admittance, and x is the step size adjustment coefficient.

[0074] The design method of the tabu list length of the tabu search algorithm is as follows:

[0075] Determine the tabu list length according to the requirements for the ability to identify local optimal solutions of the virtual admittance and the accuracy requirements for the global optimal solution. Increasing the tabu list length will enhance the algorithm's ability to identify local optimal solutions, but will increase the error of the final global optimal solution; decreasing the tabu list length will enhance the accuracy of the found global optimal solution, but will reduce the ability to identify local optimal solutions.

[0076] The execution process of the tabu search algorithm is as follows:

[0077] Take the virtual admittance amplitude |Y d | as the abscissa and the virtual admittance phase as the ordinate, and perform the tabu search algorithm through neighborhood search in two directions respectively; combined with the set iteration boundary, continuously iterate, search for high-quality solutions near the initial value of the virtual admittance, and continuously iterate until the optimal solution of the virtual admittance is obtained. During the iteration, a tabu list is used to record the attributes of the recent moves and prevent the repetition of such moves, thus avoiding cycling at the local optimal solution. Setting the iteration boundary during the iteration process can ensure the correct operation of the algorithm.

[0078] Express the iteration process of the virtual admittance in the adaptive active damping control process as:

[0079]

[0080] In the formula is the candidate solution set of the virtual admittance obtained after the 2m-th iteration, where m is a positive integer; is the virtual admittance amplitude of the 2m-th iteration, is the virtual admittance phase of the 2m-th iteration, and d 2m is the difference between the candidate solution of the virtual admittance obtained after the 2m-th iteration and the initial value of the virtual admittance;

[0081]

[0082] In the formula, Δh2m is the current harmonic variation value at the 2m-th iteration, is the virtual admittance Y d the amplitude variation value within 2m iterations, is the virtual admittance Y d the phase variation value within the (2m + 1)-th iteration; sgn(·) is the sign function;

[0083]

[0084] wherein is the maximum value of the current harmonic at the 2m-th iteration.

[0085] The method for determining the virtual admittance based on the iteration boundary in the adaptive active damping control process is as follows:

[0086]

[0087] wherein Y max is the upper limit value of the iteration boundary, and Y min is the lower limit value of the iteration boundary.

[0088] The equivalent admittance Y d1 generated by the current reference command component obtained by damping distribution and the equivalent admittance Y d2 generated by the modulation voltage reference command component:

[0089]

[0090] wherein G ic is the transfer function of the current controller, G id is the transfer function of the inductor current and the duty cycle, and T i is the loop gain transfer function;

[0091] T i = K is G ic G id / V m ;

[0092] The target virtual admittance is determined by the sum of the equivalent admittance Y d1 and the equivalent admittance Y d2 .

[0093] Combined with Figure 1 as shown, in this embodiment, the control part of the PFC converter adopts a double closed-loop control method with an outer voltage loop and an inner current loop. The voltage controller and the current controller are both PI controllers; the converter input voltage u in, the phase angle value θ of the input voltage is obtained through the phase-locked loop PLL; then, the sine value of the phase of the input voltage is solved, and the zero-crossing detection result is output by the zero-crossing detection section ZCD;

[0094] Then, the output voltage u of the converter is obtained through the analog-to-digital converter ADC dc , and the voltage reference value u ref is subtracted from the voltage feedback value u dc . The difference passes through the voltage controller transfer function G vc to obtain the output current i vco . Then, combined with the sine value of the phase of the input voltage, the reference current i ref is obtained; meanwhile, the initial value of the virtual admittance is continuously iterated through the tabu search, and the results of each iteration are input into the damping distribution section. After adding the reference current i ref to the current command component of the current given value of the damping distribution section, subtracting the inductor current i L , after being adjusted by the current controller transfer function G ic , adding it to the modulation voltage command component of the damping distribution section, and combining with the duty cycle signal d f , it is input to the PWM section; the PWM section generates the control signal of the switch in combination with the zero-crossing detection result, and finally realizes the suppression of the grid-side current harmonics.

[0095] Figure 1 In [[ID=]], the input voltage u in of the converter and the inductor current i L are filtered by a band-pass filter; the tabu search part performs the iteration of the virtual admittance in combination with the initial amplitude of the virtual admittance, the initial phase of the virtual admittance, and the filtering result.

[0096] Embodiment:

[0097] Next, the effectiveness of the proposed grid-side current harmonic adaptive suppression method for the gallium nitride totem-pole bridgeless PFC converter based on the tabu search algorithm is verified on the experimental platform of the permanent magnet compressor drive system using the totem-pole bridgeless PFC converter.

[0098] The parameter settings of the experimental platform are as follows: grid voltage 220Vrms, grid frequency 50Hz, bus voltage 350V, boost inductor 500μH, bus capacitor 940μF, differential-mode capacitor 4μF, differential-mode inductor 80μH, common-mode capacitor 5.1nF, common-mode inductor 4mH, rated power 1500W. The control algorithm is executed by the Renesas RX62T controller, and the control frequency is 50kHz.

[0099] To verify the effectiveness of the proposed suppression method, the enabling process when the motor operates at a power of 200W is as Figure 3 shown. The experimental comparison results before and after enabling are as Figure 4 ,Figure 5 As shown. From Figure 4 and Figure 5 it can be seen that after enabling the suppression method, the grid-side current harmonics are significantly reduced. From Figure 5 it can be seen that before enabling the suppression method, the amplitude of the 17th current harmonic is 0.144 A, and after enabling the suppression strategy, the amplitude of the 17th current harmonic is reduced to 0.006 A, which proves the effectiveness and feasibility of the proposed method.

[0100] To verify the effectiveness of the proposed method under different power conditions, experiments were carried out under the conditions of 200 W, 400 W, 600 W, 800 W, 1200 W, and 1500 W respectively. FFT analysis was performed on the grid-side current, and the experimental results of the amplitude of the 17th current harmonic are as Figure 6 shown. From Figure 6 it can be seen that under different grid-side power conditions, the proposed strategy can achieve good suppression effects on current harmonics of specific orders.

[0101] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not depart from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter, characterized in that including establish a system input admittance model of an air-conditioning compressor driver, design the initial amplitude and initial phase of the virtual admittance, and simultaneously determine the current reference component at the target frequency and the harmonic transfer function between the grid-side voltage, and the modulation voltage reference component and the harmonic transfer function between the grid-side voltage; design the iteration step size and the length of the tabu list of the tabu search algorithm according to the initial amplitude and initial phase of the virtual admittance; starting from the initial value of the virtual admittance, execute the tabu search algorithm in combination with the iteration step size and the length of the tabu list. By continuously iterating the virtual admittance amplitude and virtual admittance phase, obtain the optimal solution of the virtual admittance; perform damping distribution in combination with the current reference component and the harmonic transfer function between the grid-side voltage, and the modulation voltage reference component and the harmonic transfer function between the grid-side voltage; obtain the target virtual admittance according to the damping distribution result, and obtain the target virtual admittance current; calculate the current reference component at the target frequency and the modulation voltage reference component at the target frequency from the target virtual admittance current; calculate the control signal of the PWM link based on the current reference component at the target frequency and the modulation voltage reference component at the target frequency, so as to realize the adaptive active damping control of the PFC converter, and further realize the suppression of grid-side current harmonics.

2. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 1, characterized in that the system input admittance model is: where Y g_d is the system input admittance, s is a complex variable, and i g_d is the harmonic current at the target frequency, u g_d is the harmonic voltage at the target frequency, Y is the input admittance of the GaN totem-pole bridgeless PFC converter, Y DM is the differential-mode capacitance admittance, Y d is the virtual admittance, L DM is the differential-mode inductor in the EMI filter, R g is the line resistance of the GaN totem-pole bridgeless PFC converter.

3. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 2, characterized in that the method for designing the initial amplitude and initial phase of the virtual admittance is: Based on Equation (1), the magnitude and phase of the virtual admittance corresponding to the minimum magnitude of Y g_d are used as the initial magnitude and initial phase of the virtual admittance, respectively.

4. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 3, wherein the method for determining the current reference component at the target frequency and the harmonic transfer function between the grid-side voltage, and the modulation voltage reference component and the harmonic transfer function between the grid-side voltage is: The virtual admittance Y d is expressed as: where |Y d | is the virtual admittance amplitude, is the virtual admittance phase, ω d is the target frequency; where G d1 is the instruction component of the current set value at the target frequency and the harmonic transfer function of the grid-side voltage, G d2 is the instruction component of the modulation voltage set value at the target frequency and the harmonic transfer function of the grid-side voltage, K is is the current feedback coefficient, 1 / V m is the gain of the PWM link, L is the boost inductor of the GaN totem-pole bridgeless PFC converter, U dc is the DC part of the output voltage of the GaN totem-pole bridgeless PFC converter.

5. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 4, wherein the method for designing the iteration step size of the tabu search algorithm is: where Δd1 is the amplitude iteration step, Δd2 is the phase iteration step, |Y init | is the initial amplitude of the virtual admittance, is the initial phase of the virtual admittance, and x is the step adjustment coefficient.

6. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 5, wherein, the method for designing the length of the tabu list of the tabu search algorithm is: determine the length of the tabu list according to the requirement for the ability to identify the local optimal solution of the virtual admittance and the accuracy requirement for the global optimal solution.

7. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 6, characterized in that the execution process of the tabu search algorithm is: Taking the virtual admittance amplitude |Y d | as the abscissa and the virtual admittance phase as the ordinate, perform the tabu search algorithm through neighborhood search in two directions; combined with the set iteration boundary, continuously iterate to search for high-quality solutions near the initial value of the virtual admittance until the optimal solution of the virtual admittance is obtained.

8. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 7, characterized in that represent the iteration process of the virtual admittance as: where is the set of virtual admittance candidate solutions obtained after the 2m-th iteration, where m is a positive integer; is the magnitude of the virtual admittance at the 2m-th iteration, is the phase of the virtual admittance at the 2m-th iteration, d 2m is the difference between the virtual admittance candidate solution obtained at the 2m-th iteration and the initial value of the virtual admittance; where Δh 2m is the current harmonic variation value at the 2m-th iteration, is the magnitude variation value of the virtual admittance Y d within the 2m-th iteration, is the phase variation value of the virtual admittance Y d within the (2m + 1)-th iteration; In the formula is the maximum value of the current harmonic at the 2m-th iteration.

9. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 8, characterized in that the method for determining the virtual admittance based on the iteration boundary is: where Y max is the upper limit value of the iteration boundary, and Y min is the lower limit value of the iteration boundary.

10. The method for adaptively suppressing grid-side current harmonics of a gallium nitride totem-pole bridgeless PFC converter according to claim 9, characterized in that The equivalent admittance Y generated by the current reference instruction component obtained through damping distribution d1 and the equivalent admittance Y generated by the modulation voltage reference instruction component d2 : where G ic is the transfer function of the current controller, G id is the transfer function of the inductor current and the duty ratio, T i is the transfer function of the loop gain; T i = K is G ic G id / V m ; Determine the target virtual admittance from the sum of the equivalent admittance Y d1 and the equivalent admittance Y d2 .

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