A broadband and high-precision control method for a power amplifier

Abstract

A method for high-precision, broadband power amplifier control belongs to the field of power electronics. This method includes control of both the switching power amplifier portion and the linear power amplifier portion. The switching power amplifier portion primarily comprises an output voltage control loop and a circulating current control loop. Reference voltage feedforward control and load current feedforward control are employed to accelerate output voltage control, enabling the output voltage of the DC power amplifier to quickly track the reference voltage. Overall energy balance control, interphase energy balance control, and inter-arm energy balance control are employed to balance the capacitor voltages of each submodule, ensuring stable operation of the modular multi-level switching DC power amplifier. By leveraging the characteristics of the linear power amplifier, it is connected in series with the switching power amplifier and used as a voltage closed loop to quickly and accurately compensate for the error between the reference wave and the actual output of the switching power amplifier. This improves the output frequency range and voltage accuracy of the power amplifier, meeting the demand for high-bandwidth, high-response control methods.

Description

Technical Field

[0001] The present invention belongs to the technical fields of four-quadrant digital-analog hybrid simulation, broadband high-precision controlled voltage source, power electronics, etc., and specifically relates to a broadband high-precision control method for a power amplifier suitable for applications such as digital-analog hybrid simulation. Background Art

[0002] Hybrid simulation technology, combining the convenience of real-time simulation with the realism of physical simulation, has garnered widespread attention in recent years. Hybrid simulation systems can easily replicate extreme and faulty environments that are difficult to achieve in the real world. This allows for thorough research and testing of various operating conditions for physical equipment before deploying it in a live system. This accelerates the R&D process and enables testing of interactions between physical equipment and the power grid.

[0003] Implementing hybrid digital-analog simulation involves numerous technical challenges, particularly the design of the hybrid simulation interface. The characteristics of this interface are crucial to the system's simulation results and are a key focus of hybrid simulation research. Research on new power grids and key power electronic equipment requires wide bandwidth, fast transient response, high voltage, and large capacity, particularly for harmonic suppression, rapid fault diagnosis and removal, and broadband oscillation research. For these hybrid simulation targets, there is an urgent need to develop power amplifiers with high output voltage, high bandwidth, fast response speed, and high slew rate to replicate the real-time signals of digital simulation and better support the development of key power electronic equipment.

[0004] For high-output voltage applications, the main solutions currently include cascaded switching power amplifiers (CHB switching power amplifiers) and modular multilevel switching power amplifiers (MMC switching power amplifiers). Compared to CHB switching power amplifiers, MMC switching power amplifiers do not require isolated power supply and are easier to achieve four-quadrant operation. However, research on control methods for MMC switching power amplifiers is still limited, and they cannot meet the requirements of high bandwidth and high response speed. Summary of the Invention

[0005] The present invention aims to solve the current lack of research on control methods for MMC switching power amplifiers and the inability to meet the requirements of high bandwidth and high response speed, and provides a broadband and high-precision control method for power amplifiers.

[0006] The technical solution adopted in the present invention is:

[0007] A wideband high-precision control method for a power amplifier, wherein the power amplifier includes a modular multi-level converter and a linear power amplifier (LPA);

[0008] The method includes controlling a switching power amplifier and a linear power amplifier; each phase of the switching power amplifier includes two upper and lower bridge arms, each bridge arm includes an inductor and N stacked full-bridge sub-modules with the same structure, each full-bridge sub-module includes a full-bridge power unit and a group of capacitors, the AC side of which is connected to the power grid via a transformer, and the DC side serves as the switching power amplifier output, the switching power amplifier output u1 and the linear power amplifier output u2 are connected in series as the total output u of the power amplifier out , that is, the power amplifier output voltage u out ;

[0009] The control of the switching power amplifier includes outer loop control and inner loop control. The outer loop control includes output voltage control loop, overall energy balance control loop, phase-to-phase energy balance control loop, and bridge arm energy balance control loop. The inner loop control includes circulating current control loop and AC current control loop.

[0010] The method comprises the following steps:

[0011] Step 1: Execute the output voltage control loop and set u ref As the output voltage given signal and the detected power amplifier output voltage u out The difference between the two is sent to the PI controller to obtain the DC current control quantity I dc * , while detecting the load current i out , which is used as the feedforward quantity and I dc * Add them together and multiply by 1 / 3 to get the DC loop control command current I of each phase dc,j * , where j represents the three phases A, B, and C;

[0012] Step 2: Execute the energy balance control loop between bridge arms, and calculate the average value of the bridge arm capacitor voltage u C_avg_upj As a given signal, the average voltage of the lower bridge arm capacitor u C_avg_lowj As the feedback signal, the difference between the two is multiplied by cos(ωt+θ j ), and obtain the base frequency circulation control instruction I of each phase c1,j * , and the DC loop control command current I dc,j * After adding, we get the given signal I of the circulating current control loop. c,j * ; where ω is the grid voltage frequency, θ j is the phase of the j-phase grid voltage, and t is the time;

[0013] Step 3: Execute the circulating current control loop to detect the circulating current i of each phase of the switching power amplifier c,j As feedback, the given signal Ic,j * After making the difference, it is sent to the proportional resonant controller (PR controller) PR(ω) to get the value No. 1.

[0014] Detecting the circulating current of each phase of the switching power amplifier c,j As feedback, the given signal I c,j * After the difference is made, the proportional controller (P controller) controls the second value, and the first value and the second value are added to obtain the common mode voltage adjustment value Δu of each phase. cm,j At the same time, in order to speed up the output voltage control speed, u ref Multiply by 1 / 2 and add Δu cm,j Add together to get the common mode voltage reference u of each phase cm,j ;

[0015] Step 4: Execute the overall energy balance control loop, with U C As a given signal, monitor the voltage U of each submodule capacitor sm , calculate the average capacitor voltage ∑U of all full-bridge submodules in the switching power amplifier sm / 6N is used as feedback, and the difference is sent to the PI regulator for control, and I AC * ; N is a natural number;

[0016] At the same time, the inter-phase energy balance control loop is executed, with the average value of the capacitor voltage of all full-bridge sub-modules ∑U sm / 6N is used as a reference to calculate the average value of the capacitor voltage of each phase u C_avg_j As feedback, the difference is obtained after the P regulator acts on it. AC,j * , I AC * with I AC,j * After adding, multiply it by the reference phase signal cos(ωt+θ j ) as the given signal of each phase AC current control loop;

[0017] At the same time, the inter-phase energy balance control loop is executed, with the average value of the capacitor voltage of all full-bridge sub-modules ∑U sm / 6N is used as a reference to calculate the average value of the capacitor voltage of each phase u C_avg_j As feedback, the difference is obtained after the P regulator acts on it. AC,j * , I AC * with I AC,j * After adding, multiply it by the reference phase signal cos(ωt+θ j) as the given signal of each phase AC current control loop;

[0018] Step 5: Execute the AC current control loop and detect the AC current i AC,j As feedback, the difference between the given signal of each phase AC current control loop in step 4 is sent to the proportional resonant controller (PR controller) PR(ω) to obtain the phase differential mode voltage reference u dm,j , the resonant frequency is ω;

[0019] Step 6: Set the common mode voltage of each phase to reference u cm,j Differential mode voltage reference u dm,j Subtract and get the voltage reference u of each phase upper bridge arm up,j ; Reference the common mode voltage of each phase to u cm,j Differential mode voltage reference u dm,j Add together to get the voltage reference u of the lower bridge arm of each phase low,j ; Each phase upper arm voltage reference u up,j And each phase lower arm voltage reference u low,j After modulation, the PWM switching signal of the MOSFET in each full-bridge sub-module is obtained;

[0020] Step 7: The PWM switching signal controls the full-bridge submodule in the switching power amplifier to obtain the switching power amplifier output voltage u1;

[0021] Step 8: Output voltage given signal u ref The difference between the output voltage u1 of the switching power amplifier and the output voltage u2 of the linear power amplifier is used as the input signal of the linear power amplifier, and then u2 is obtained after being amplified by the linear power amplifier.

[0022] Step 9: Compare the switching amplifier output voltage u1 with the output voltage given signal u ref The difference is used as the voltage reference of the linear power amplifier, and the output voltage u2 of the linear power amplifier is used as feedback. The difference between the two is used as the input of the linear power amplifier. The linear power amplifier operates on the error until the error is fully compensated.

[0023] Preferably, the specific implementation method of the modulation effect described in step 6 is: the received upper bridge arm voltage of each phase is referenced to u up,j And each phase lower arm voltage reference u low,j Compare with 2N triangular carriers with a phase shift angle of π / N respectively, and superpose to obtain the number of upper and lower bridge arms of each phase, n up,j 、n low,j If the bridge arm current makes the capacitors of each full-bridge sub-module charged, select n with a lower capacitor voltage. up,j 、n low,jIf the bridge arm current makes the capacitors of each submodule discharged, select n with a higher capacitor voltage. up,j 、n low,j Each module is put into operation to generate PWM signals for each full-bridge sub-module.

[0024] Preferably, the method utilizes the high bandwidth and high precision characteristics of the linear power amplifier, connects it in series with the switching power amplifier, and uses it as a voltage closed loop to quickly and accurately compensate for the error between the reference wave and the actual output of the switching power amplifier, further improving the output frequency range and voltage accuracy of the power amplifier. Specifically, the switching power amplifier output voltage u1 is connected to the output voltage given signal u ref The difference is used as the voltage reference of the linear power amplifier, and the output voltage u2 of the linear power amplifier is used as feedback. The difference between the two is used as the input of the linear power amplifier. The linear power amplifier operates on the error until the error is fully compensated.

[0025] Beneficial effects: The present invention discloses a method for wideband and high-precision control of a power amplifier, including control of a switching power amplifier part and control of a linear power amplifier part. The switching power amplifier part mainly includes an output voltage control loop and a circulating current control loop, and adopts reference voltage feedforward control and load current feedforward control to accelerate the control speed of the output voltage, so that the output voltage of the DC power amplifier can quickly track the reference voltage. In view of the characteristics of the suspended capacitors of each sub-module of the modular multi-level switching DC power amplifier, overall energy balance control, phase-to-phase energy balance control, and bridge arm-to-bridge energy balance control are adopted to balance the capacitor voltages of each sub-module, thereby ensuring the stable operation of the modular multi-level switching DC power amplifier. By utilizing the high bandwidth and high precision characteristics of the linear power amplifier, it is connected in series with the switching power amplifier and used as a voltage closed loop to quickly and accurately compensate for the error between the reference wave and the actual output of the switching power amplifier, further improving the output frequency range and voltage accuracy of the power amplifier, solving the problem that the current research on the control method of the MMC switching power amplifier is lacking and cannot meet the requirements of high bandwidth and high response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a switching power amplifier;

[0027] Figure 2 It is a control process diagram of a wide-band high-precision control method for a power amplifier;

[0028] Figure 3 It is a schematic diagram of the control process of the overall energy balance control loop;

[0029] Figure 4 It is a schematic diagram of the control process of the inter-phase energy balance control loop;

[0030] Figure 5 It is a schematic diagram of the control process of the energy balance control loop between bridge arms, and LPF is a low-pass filter. DETAILED DESCRIPTION

[0031] Specific implementation method 1: refer to Figures 1 to 5 Specifically describing this embodiment, a method for controlling a power amplifier with high bandwidth and high precision is described in this embodiment, wherein the power amplifier includes a modular multi-level converter and a linear power amplifier LPA;

[0032] The method includes controlling a switching power amplifier and a linear power amplifier; each phase of the switching power amplifier includes two upper and lower bridge arms, each bridge arm includes an inductor and N stacked full-bridge sub-modules with the same structure, each full-bridge sub-module includes a full-bridge power unit and a group of capacitors, the AC side of which is connected to the power grid via a transformer, and the DC side serves as the switching power amplifier output, the switching power amplifier output u1 and the linear power amplifier output u2 are connected in series as the total output u of the power amplifier out , that is, the power amplifier output voltage u out ;

[0033] The control of the switching power amplifier includes outer loop control and inner loop control. The outer loop control includes output voltage control loop, overall energy balance control loop, phase-to-phase energy balance control loop, and bridge arm energy balance control loop. The inner loop control includes circulating current control loop and AC current control loop.

[0034] The method comprises the following steps:

[0035] Step 1: Execute the output voltage control loop and set u ref As the output voltage given signal and the detected power amplifier output voltage u out The difference between the two is sent to the PI controller to obtain the DC current control quantity I dc * , while detecting the load current i out , which is used as the feedforward quantity and I dc * Add them together and multiply by 1 / 3 to get the DC loop control command current I of each phase dc,j * , where j represents the three phases A, B, and C;

[0036] Step 2: Execute the energy balance control loop between bridge arms, and calculate the average value of the bridge arm capacitor voltage u C_avg_upj As a given signal, the average voltage of the lower bridge arm capacitor u C_avg_lowj As the feedback signal, the difference between the two is multiplied by cos(ωt+θ j ), and obtain the base frequency circulation control instruction I of each phase c1,j * , and the DC loop control command current Idc,j * After adding, we get the given signal I of the circulating current control loop. c,j * ; where ω is the grid voltage frequency, θ j is the phase of the j-phase grid voltage, and t is the time;

[0037] Step 3: Execute the circulating current control loop to detect the circulating current i of each phase of the switching power amplifier c,j As feedback, the given signal I c,j * After making the difference, it is sent to the proportional resonant controller (PR controller) PR(ω) to get the value No. 1.

[0038] Detecting the circulating current of each phase of the switching power amplifier c,j As feedback, the given signal I c,j * After the difference is made, the proportional controller (P controller) controls the second value, and the first value and the second value are added to obtain the common mode voltage adjustment value Δu of each phase. cm,j At the same time, in order to speed up the output voltage control speed, u ref Multiply by 1 / 2 and add Δu cm,j Add together to get the common mode voltage reference u of each phase cm,j ;

[0039] Step 4: Reference Figure 3 , execute the overall energy balance control loop, with U C (U C Is a reference instruction, appearing in Figure 3 In the control process, as a reference) as a given signal, the voltage U of each sub-module capacitor is monitored sm , calculate the average capacitor voltage ∑U of all full-bridge submodules in the switching power amplifier sm / 6N is used as feedback, and the difference is sent to the PI regulator for control, and I AC * ; N is a natural number;

[0040] Reference Figure 4 , and execute the inter-phase energy balance control loop at the same time, taking the average value of the capacitor voltage of all full-bridge submodules ∑U sm / 6N is used as a reference to calculate the average value of the capacitor voltage of each phase u C_avg_j As feedback, the difference is obtained after the P regulator acts on it. AC,j * , I AC * with I AC,j * After adding, multiply it by the reference phase signal cos(ωt+θj ) as the given signal of each phase AC current control loop;

[0041] Step 5: Execute the AC current control loop and detect the AC current i AC,j As feedback, the difference between the given signal of each phase AC current control loop in step 4 is sent to the proportional resonant controller (PR controller) PR(ω) to obtain the phase differential mode voltage reference u dm,j , the resonant frequency is ω;

[0042] Step 6: Set the common mode voltage of each phase to reference u cm,j Differential mode voltage reference u dm,j Subtract and get the voltage reference u of each phase upper bridge arm up,j ; Reference the common mode voltage of each phase to u cm,j Differential mode voltage reference u dm,j Add together to get the voltage reference u of the lower bridge arm of each phase low,j ; Each phase upper arm voltage reference u up,j And each phase lower arm voltage reference u low,j After modulation, the PWM switching signal of the MOSFET in each full-bridge sub-module is obtained;

[0043] Step 7: The PWM switching signal controls the full-bridge submodule in the switching power amplifier to obtain the switching power amplifier output voltage u1;

[0044] Step 8: Output voltage given signal u ref The difference between the output voltage u1 of the switching power amplifier and the output voltage u2 of the linear power amplifier is used as the input signal of the linear power amplifier, and then u2 is obtained after being amplified by the linear power amplifier.

[0045] Step 9: Compare the switching amplifier output voltage u1 with the output voltage given signal u ref The difference is used as the voltage reference of the linear power amplifier, and the output voltage u2 of the linear power amplifier is used as feedback. The difference between the two is used as the input of the linear power amplifier. The linear power amplifier operates on the error until the error is fully compensated.

[0046] Specific embodiment 2: This embodiment further illustrates the method for controlling a power amplifier with high precision over a wide bandwidth as described in embodiment 1. In this embodiment, the transfer function of the PR controller described in steps 3 and 5 is:

[0047]

[0048] where K p is the proportionality coefficient, K r is the resonant gain, ω c is the resonant bandwidth, and s is a variable in the complex frequency domain.

[0049] Specific embodiment three: This embodiment is a further description of the wideband high-precision control method of a power amplifier described in embodiment one. In this embodiment, the specific implementation method of the modulation effect described in step six is: the received upper bridge arm voltage of each phase is referenced to u up,j And each phase lower arm voltage reference u low,j Compare with 2N triangular carriers with a phase shift angle of π / N respectively, and superpose to obtain the number of upper and lower bridge arms of each phase, n up,j 、n low,j If the bridge arm current makes the capacitors of each full-bridge sub-module charged, select n with a lower capacitor voltage. up,j 、n low,j If the bridge arm current makes the capacitors of each submodule discharged, select n with a higher capacitor voltage. up,j 、n low,j Each module is put into operation to generate PWM signals for each full-bridge sub-module.

[0050] Specific embodiment: A method for controlling a power amplifier with wideband and high precision, including the control of a switching power amplifier and a linear power amplifier. Each phase of the switching power amplifier comprises two upper and lower bridge arms, each bridge arm comprising an inductor and N stacked submodules of the same structure. Each submodule comprises a full-bridge power unit and a group of capacitors. The AC side is connected to the power grid via a transformer, and the DC side serves as the switching power amplifier output. The switching power amplifier output and the linear power amplifier output are connected in series to serve as the total output of the power amplifier, such as Figure 1 shown.

[0051] The switching power amplifier operation control method is characterized by including outer loop control and inner loop control. The outer loop control includes output voltage control, overall energy balance control, phase-to-phase energy balance control, and bridge arm energy balance control. The inner loop control includes circulating current control and AC current control. Specifically, it includes the following steps:

[0052] (1) Execute the output voltage control loop, such as Figure 2 As shown, u ref As the output voltage given signal, detect the output voltage u of the switching power amplifier out The difference between the two is sent to the PI controller to obtain the DC current control quantity I dc * , while detecting the load current i out , which is used as the feedforward quantity and I dc * Add them together and multiply by 1 / 3 to get the DC loop control command current I of each phase dc,j * , j represents the three phases A, B, and C * .

[0053] (2) Execute the energy balance control loop between bridge arms, such as Figure 5 As shown in the figure, the average voltage of the upper bridge arm capacitor of each phase is used as the given signal, and the average voltage of the lower bridge arm capacitor is used as the feedback signal. The difference between the two is multiplied by cos(ωt+θ j ), ω is the grid voltage frequency, θ j is the phase of the j-phase grid voltage. On this basis, the fundamental frequency circulating current control instruction I of each phase is obtained through circulating current decoupling control. c1,j * , and the DC loop control command current I dc,j * After adding, we get the given signal I of the circulating current control loop. c,j * ,;

[0054] (3) Execute the circulating current control loop to detect the circulating current of each phase of the switching power amplifier i c,j As feedback, the difference with the given value is sent to the proportional resonant controller (PR controller) and the proportional controller (P controller) for control to obtain the common mode voltage regulation of each phase Δu dm,j At the same time, in order to speed up the output voltage control speed, u ref Multiply by 1 / 2 and add Δu dm,j Add together to get the common mode voltage reference u of each phase dm,j The PR controller transfer function is:

[0055]

[0056] where K p is the proportionality coefficient, K r is the resonant gain, ω c is the resonant bandwidth.

[0057] (4) Execute the overall energy balance control loop, such as Figure 3 As shown, U C As a given signal, monitor the voltage U of each submodule capacitor sm , calculate the average capacitor voltage ∑U of all submodules in the switching power amplifier sm / 6N is used as feedback, and the difference is sent to the PI regulator for control, and I AC * ; At the same time, the inter-phase energy balance control loop is executed, such as Figure 4 As shown, the average value of the capacitor voltage of all submodules ∑U sm / 6N is used as a reference, and the average value of the capacitor voltage of each phase is calculated as feedback. The difference is obtained after the PI regulator acts on it. AC,j * , I AC * with I AC,j* Add and multiply the reference phase signal cos(ωt+θ j ) as the given signal of each phase AC current control loop.

[0058] (5) Execute the AC current control loop and detect the AC current i AC,j As feedback, the difference with the given signal is sent to the proportional resonant controller (PR controller), the resonant frequency is ω, and the differential mode voltage reference u of each phase is obtained dm,j .

[0059] The upper-arm voltage reference for each phase is obtained by subtracting the common-mode voltage reference from the differential-mode voltage reference. The lower-arm voltage reference for each phase is obtained by adding the common-mode voltage reference to the differential-mode voltage reference. Each arm voltage reference is modulated to generate the PWM switching signal for the MOSFET in each submodule.

[0060] (6) The specific implementation method of the modulation function is: compare the received bridge arm voltage reference with 2N triangular carriers with a phase shift angle of π / N respectively, and superimpose them to obtain the number n of upper and lower bridge arms of each phase. up,j 、n low,j If the bridge arm current makes the capacitors of each submodule in a charging state, select n with a lower capacitor voltage. up,j 、n low,j If the bridge arm current makes the capacitors of each submodule discharged, select n with a higher capacitor voltage. up,j 、n low,j Modules invested.

[0061] (7) Taking advantage of the high bandwidth and high precision of the linear power amplifier, it is connected in series with the switching power amplifier and used as a voltage closed loop to quickly and accurately compensate for the error between the reference wave and the actual output of the switching power amplifier, further improving the output frequency range and voltage accuracy of the power amplifier. Specifically, the switching power amplifier output voltage u1 is connected to the output voltage given signal u ref The difference is used as the voltage reference of the linear power amplifier, and the output voltage u2 of the linear power amplifier is used as feedback. The difference between the two is used as the input of the linear power amplifier. The linear power amplifier operates on the error until the error is fully compensated.

[0062] The present invention is described by way of several specific embodiments. It should be understood by those skilled in the art that various modifications and equivalent substitutions may be made to the present invention without departing from the scope of the present invention. In addition, various modifications may be made to the present invention for specific situations or circumstances without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed, but is intended to include all embodiments falling within the scope of the claims.

Claims

1. A method for controlling a power amplifier with high bandwidth and high precision, characterized in that: The power amplifier includes a modular multi-level converter and a linear power amplifier LPA; the method includes controlling the switching power amplifier and the linear power amplifier; each phase of the switching power amplifier includes two upper and lower bridge arms, each bridge arm contains an inductor and N full-bridge sub-modules with the same structure stacked together, each full-bridge sub-module contains a full-bridge power unit and a group of capacitors, the AC side of which is connected to the power grid through a transformer, and the DC side is used as the switching power amplifier output, the switching power amplifier output u1 and the linear power amplifier output u2 are connected in series as the total output u of the power amplifier out , that is, the power amplifier output voltage u out The control of the switching power amplifier includes outer loop control and inner loop control. The outer loop control includes the output voltage control loop, the overall energy balance control loop, the phase-to-phase energy balance control loop, and the bridge arm energy balance control loop. The inner loop control includes the circulating current control loop and the AC current control loop. The method comprises the following steps: Step 1: Execute the output voltage control loop and set u ref As the output voltage given signal and the detected power amplifier output voltage u out The difference between the two is sent to the PI controller to obtain the DC current control value , while detecting the load current i out , which is used as the feedforward quantity and Add them together and multiply by 1 / 3 to get the DC loop control command current of each phase , where j represents the three phases A, B, and C; Step 2: Execute the energy balance control loop between bridge arms, and calculate the average value of the bridge arm capacitor voltage u C_avg_upj As a given signal, the average voltage of the lower bridge arm capacitor u C_avg_lowj As the feedback signal, the difference between the two is multiplied by the PI controller. , get the fundamental frequency circulation control instructions of each phase , and the DC loop control command current After adding, we get the given signal of the circulating current control loop ;in, is the grid voltage frequency, for Phase grid voltage phase, For time; Step 3: Execute the circulating current control loop to detect the circulating current of each phase of the switching power amplifier As feedback, the given signal of the circulating current control loop After making the difference, it is sent to the proportional resonant controller (PR controller) Then we get the value of number one, Detecting the circulating current of each phase of the switching power amplifier As feedback, the given signal of the circulating current control loop After the difference is made, the proportional controller (P controller) controls the second value, and the first value and the second value are added to get the common mode voltage regulation of each phase. At the same time, in order to speed up the output voltage control speed, Multiply by 1 / 2 and Add together to get the common mode voltage reference of each phase ; Step 4: Execute the overall energy balance control loop, with U C As a given signal, monitor the voltage U of each submodule capacitor sm , calculate the average capacitor voltage of all full-bridge submodules in the switching power amplifier As feedback, the difference is sent to the PI regulator for control, and the result is ; N is a natural number; At the same time, the inter-phase energy balance control loop is executed, with the average value of the capacitor voltage of all full-bridge submodules As a reference, calculate the average value of the capacitor voltage of each phase As feedback, the difference is obtained after the P regulator acts on it. , and Add and then multiply by the reference phase signal of the phase AC voltage As a given signal for each phase AC current control loop; At the same time, the inter-phase energy balance control loop is executed, with the average value of the capacitor voltage of all full-bridge submodules As a reference, calculate the average value of the capacitor voltage of each phase As feedback, the difference is obtained after the P regulator acts on it. , and Add and then multiply by the reference phase signal of the phase AC voltage As a given signal for each phase AC current control loop; Step 5: Execute the AC current control loop and detect the AC current As feedback, the difference between the given signal of each phase AC current control loop in step 4 is sent to the proportional resonant controller (PR controller) PR(ω) to obtain the differential mode voltage reference of each phase , the resonant frequency is ; Step 6: Set the common mode voltage of each phase to the reference voltage. Differential mode voltage reference for each phase Subtract and get the voltage reference of each phase upper bridge arm ; Reference the common mode voltage of each phase Differential mode voltage reference for each phase Add together to get the voltage reference of each phase lower bridge arm ; Each phase upper arm voltage reference With each phase lower arm voltage reference After modulation, the PWM switching signal of the MOSFET in each full-bridge sub-module is obtained; Step 7: The PWM switching signal controls the full-bridge submodule in the switching power amplifier to obtain the switching power amplifier output voltage u1; Step 8: Output voltage given signal The difference between the output voltage u1 of the switching power amplifier and the output voltage u2 of the linear power amplifier is used as the input signal of the linear power amplifier, and then amplified by the linear power amplifier to obtain u2; Step 9: Compare the switching amplifier output voltage u1 with the output voltage given signal The difference is used as the voltage reference of the linear power amplifier, and the output voltage u2 of the linear power amplifier is used as feedback. The error between the two is used as the input of the linear power amplifier, and the linear power amplifier operates on the error until the error is fully compensated.

2. A method for controlling a power amplifier with high bandwidth and high precision according to claim 1, characterized in that: The specific implementation method of the modulation effect described in step 6 is: the received upper bridge arm voltage of each phase is referenced With each phase lower arm voltage reference Compare with 2N triangular carriers with a phase shift angle of π / N respectively, and superpose to obtain the number of upper and lower bridge arms of each phase 、 If the bridge arm current makes the capacitors of each full-bridge sub-module charged, select a capacitor with a lower voltage. 、 Module is put into operation; if the bridge arm current makes the capacitors of each submodule discharged, select a capacitor with a higher voltage. 、 Each module is put into operation to generate PWM signals for each full-bridge sub-module.

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