A reliable parallel control system and method for high-efficiency bidirectional power conversion modules

Abstract

The present invention belongs to the field of advanced control technology for high-performance power conversion systems, and specifically relates to a reliable parallel control system and method for efficient bidirectional power conversion modules, including a bipolar current space vector modulation module, an input current sharing backstepping control module and an output voltage sharing backstepping control module; wherein the input current sharing backstepping control module includes an output current outer loop backstepping controller, an output voltage middle loop backstepping control unit, and an input current inner loop backstepping control unit; the output voltage sharing backstepping control module includes an output voltage outer loop backstepping control unit and an input current inner loop backstepping control unit; the current stress and voltage stress of the switch tube are greatly reduced, and a modular design is adopted, which is easy to expand; from the perspective of energy conservation, the output voltage sharing and input current sharing of each module are used as the entry point, and the power balance between modules is achieved through the power balance backstepping control method, which effectively improves the safety and reliability of the parallel system.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced control of high-performance power conversion systems, and in particular relates to a reliable parallel control system and method for efficient bidirectional power conversion modules. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] High-efficiency bidirectional power conversion systems are widely used in applications such as electric vehicle charging, power battery testing, and battery energy storage, and are common key technologies for the above applications. Conventional power conversion systems often adopt a two-stage structure of AC / DC and DC / DC, which not only requires more power switches and complicated drive circuit design, but also has a large DC bus capacitor, making it difficult to further improve the efficiency and power density of this solution. The high-frequency link matrix converter is a three-phase single-stage high-frequency isolated AC / DC converter with a simple drive design and no need for DC bus capacitors. It has the advantages of high efficiency, high power density, and high reliability, and is an ideal alternative to the traditional two-stage power conversion topology.

[0004] As the voltage and capacity of battery systems continue to increase, the voltage and power levels of power conversion systems have increased significantly, which has led to an exponential increase in the cost of power switching devices, which has seriously restricted their market application. Domestic and foreign scholars have proposed technologies such as multi-level and series-parallel. However, due to the existence of bidirectional switches, the multi-level control technology of matrix converters is extremely complex and not conducive to engineering applications; in practical applications, there are often inconsistent parameters of inductance and capacitance devices, resulting in power imbalance between series-parallel modules, reducing the reliability of system operation. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a reliable parallel control system and method for high-efficiency bidirectional power conversion modules, designs an input-side parallel and output-side series modular high-frequency chain matrix converter (IPOS-HFLMC), which greatly reduces the current stress and voltage stress of the switching tube, adopts a modular design, and is easy to expand. From the perspective of energy conservation, the output voltage and input current of each module are used as the entry point, and the power balance between modules is achieved through the power balance backstepping control method, which effectively improves the safety and reliability of the parallel system.

[0006] According to some embodiments, a first solution of the present disclosure provides a modular high-frequency link matrix converter, which adopts the following technical solution:

[0007] A modular high-frequency link matrix converter comprises a first high-frequency link matrix converter submodule and a second high-frequency link matrix converter submodule;

[0008] The three-phase input ends of the first high-frequency link matrix converter submodule and the second high-frequency link matrix converter submodule are connected in parallel to the three-phase power grid, the negative electrode of the output capacitor of the first high-frequency link matrix converter submodule is connected to the positive electrode of the output capacitor of the second high-frequency link matrix converter submodule, the positive electrode of the output capacitor of the first high-frequency link matrix converter submodule is connected to the positive electrode of the load battery, and the negative end of the output capacitor of the second high-frequency link matrix converter submodule is connected to the negative electrode of the battery load.

[0009] According to some embodiments, the second solution of the present disclosure provides a high-efficiency bidirectional power conversion module reliable parallel control system, which adopts the modular high-frequency link matrix converter provided in the first solution and adopts the following technical solutions:

[0010] A high-efficiency bidirectional power conversion module reliable parallel control system, comprising:

[0011] Bipolar current space vector modulation module, input current sharing backstepping control module and output voltage sharing backstepping control module; wherein the input current sharing backstepping control module includes an output current outer loop backstepping controller, an output voltage middle loop backstepping control unit, and an input current inner loop backstepping control unit; the output voltage sharing backstepping control module includes an output voltage outer loop backstepping control unit and an input current inner loop backstepping control unit;

[0012] The output current outer loop backstepping controller obtains the output voltage reference value and the output current error variable of each high-frequency link matrix converter submodule according to the received given output current reference value and the output current actual value and the output voltage actual value of the modular high-frequency link matrix converter;

[0013] The output voltage mid-loop back-stepping control unit obtains the reference value of the input current in the active component d-axis and the output voltage error variable of the modular high-frequency link matrix converter according to the actual output current value and the actual output voltage value of the modular high-frequency link matrix converter, as well as the reference value of the input current in the active component d-axis and the output current error variable;

[0014] The output voltage outer loop backstepping control unit obtains a reference value of the input current in the active component d-axis and an output current error variable according to the received given output voltage reference value and the output current actual value and output voltage reference value of the modular high-frequency chain matrix converter;

[0015] The input current inner loop backstepping control unit calculates the modulation ratio of the three-phase current active component according to the three-phase current of the modular high-frequency link matrix converter, the bridge arm midpoint voltage, and the output of the output voltage middle loop backstepping control unit or the output voltage outer loop backstepping control unit;

[0016] The bipolar current space vector modulation module obtains a control pulse signal for driving a bidirectional switch of a modular high-frequency link matrix converter according to the modulation ratio of the three-phase current active component.

[0017] As a further technical limitation, it also includes a phase-locked loop module and a coordinate transformation module; the phase-locked loop module obtains the phase angle of the grid voltage according to the actual value of the three-phase voltage; the coordinate transformation module obtains the active component and reactive component of the grid current according to the actual value of the three-phase current.

[0018] As a further technical limitation, the output voltage mid-ring backstepping control unit is used to control the output voltage and track the reference voltage; the output voltage mid-ring backstepping control unit includes a first output voltage mid-ring backstepping controller and a second output voltage mid-ring backstepping controller; the first output voltage mid-ring backstepping controller is used for a first high-frequency link matrix converter sub-module, and the second output voltage mid-ring backstepping controller is used for a second high-frequency link matrix converter sub-module.

[0019] Furthermore, the input current inner loop backstepping control unit is used to control the active component of the input current and the active component of the bridge arm midpoint voltage, and track the reference value of the active component of the input current and the active component of the bridge arm midpoint voltage; the input current inner loop backstepping control unit includes a first input current inner loop backstepping controller and a second input current inner loop backstepping controller; the first input current inner loop backstepping controller is used for the first high-frequency link matrix converter submodule, and the second input current inner loop backstepping controller is used for the second high-frequency link matrix converter submodule.

[0020] Furthermore, the output voltage outer loop backstepping control unit is used to control the total output voltage and track a given output voltage reference value; the output voltage outer loop backstepping control unit includes a first output voltage outer loop backstepping controller and a second output voltage outer loop backstepping controller; the first output voltage outer loop backstepping controller is used for a first high-frequency link matrix converter submodule, and the second output voltage outer loop backstepping controller is used for a second high-frequency link matrix converter submodule.

[0021] As a further technical limitation, under the voltage balance condition of the three-phase grid, according to Kirchhoff's law, the grid-side loop equation of the high-frequency link matrix converter of the dq two-phase synchronous rotating coordinate system is established as follows:

[0022]

[0023]

[0024] Among them, e d 、e q Represent the active and reactive components of the grid voltage respectively, i d 、i qRepresent the active and reactive components of the grid current respectively, i dt 、i qt They represent the active and reactive components of the input current of the three-phase / single-phase AC-DC matrix structure, respectively, and v d 、v q They represent the active component and reactive component of the midpoint voltage of the bridge arm of the three-phase / single-phase AC-DC matrix structure, ω represents the angular velocity of the grid, m d and m q are the modulation ratios of the active and reactive components of the three-phase current respectively.

[0025] Furthermore, in the input current sharing backstepping control module, the differential equation of the DC side of the high-frequency link matrix converter is established as:

[0026]

[0027] Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of the first high-frequency link matrix converter submodule, i dc is the output current of the output rectifier full bridge, i o is the output current of IPOS-HFLMC, L dc is the output filter inductor, C o is the output filter capacitor, d(t) represents the total disturbance on the output side, |d(t)|<ρ, ρ is a positive real number.

[0028] Furthermore, in the output voltage equalization backstepping control module, the differential equation of the DC side of the high-frequency link matrix converter is established as follows:

[0029]

[0030] Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of the first high-frequency link matrix converter submodule, i dc is the output current of the output rectifier full bridge, i o is the output current of IPOS-HFLMC, L dc is the output filter inductor, C o is the output filter capacitor, d1(t) and d2(t) represent the voltage disturbance and current disturbance on the output side respectively, |d1(t)|<ρ1,|d2(t)|<ρ2, ρ1, ρ2 are positive real numbers.

[0031] According to some embodiments, a third solution of the present disclosure provides a reliable parallel control method for high-efficiency bidirectional power conversion modules, which adopts the following technical solutions:

[0032] A reliable parallel control method for high-efficiency bidirectional power conversion modules, including a current sharing mode and a voltage sharing mode;

[0033] The specific process of the current sharing mode is as follows:

[0034] According to the received given output current reference value and the output current actual value and output voltage actual value of the modular high-frequency link matrix converter, an output voltage reference value and an output current error variable of each high-frequency link matrix converter submodule are obtained;

[0035] According to the output current actual value and the output voltage actual value of the modular high-frequency link matrix converter, as well as the reference value of the input current in the active component d-axis and the output current error variable, the reference value of the input current in the active component d-axis and the output voltage error variable of the modular high-frequency link matrix converter are obtained;

[0036] The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output voltage error variable of the modular high-frequency link matrix converter;

[0037] According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained;

[0038] The specific process of the pressure equalization mode is as follows:

[0039] According to the received given output voltage reference value and the output current actual value and output voltage reference value of the modular high-frequency chain matrix converter, a reference value of the input current in the active component d axis and an output current error variable are obtained;

[0040] The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output current error variable of the modular high-frequency link matrix converter;

[0041] According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The modular high-frequency link matrix converter proposed in the present disclosure can be connected in parallel or cascade on the grid side and in series or parallel on the DC side, which can be flexibly expanded and greatly improve the system power level and DC output voltage and current range.

[0044] 2. The power balancing backstepping control method proposed in the present invention includes input current balancing backstepping control (i.e. current balancing mode) and output voltage balancing backstepping control (i.e. voltage balancing mode). The current balancing mode can achieve current balancing on the input side while ensuring voltage balancing on the output side. The voltage balancing mode can achieve voltage balancing on the output side while ensuring current balancing on the input side, ultimately achieving power balancing between modules and effectively improving the safety and reliability of the parallel system.

[0045] 3. The present invention can quickly track charge and discharge instructions, quickly and stably charge and discharge according to the system specified power, and can effectively resist internal and external disturbances of the system, so that the high-frequency link matrix converter has good dynamic response performance and anti-interference performance.

[0046] 4. The power balancing backstepping control method proposed in the present disclosure has a simple implementation process and can be extended to other matrix converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0048] Figure 1 is a topological structure diagram of a modular high-frequency link matrix converter in the first embodiment of the present disclosure;

[0049] Figure 2 It is an overall control block diagram of a reliable parallel control system for high-efficiency bidirectional power conversion modules in the second embodiment of the present disclosure;

[0050] Figure 3 is a diagram of a power balancing research system in Embodiment 3 of the present disclosure;

[0051] Figure 4 is a comparison chart of simulation results based on the application of open-loop control and voltage-balanced mode power balancing backstepping control method in the third embodiment of the present disclosure;

[0052] Figure 5 It is a comparison chart of simulation results of the power balancing backstepping control method based on the application of open-loop control and current sharing mode in the third embodiment of the present disclosure. DETAILED DESCRIPTION

[0053] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0054] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0055] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0056] In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0057] Embodiment 1

[0058] This embodiment introduces a modular high-frequency link matrix converter.

[0059] like Figure 1 As shown, the modular high-frequency link matrix converter used in this embodiment is an input-side parallel-output-side series modular high-frequency link matrix converter (IPOS-HFLMC), including a first high-frequency link matrix converter sub-module HFLMC-1 and a second high-frequency link matrix converter sub-module HFLMC-2; wherein, the three-phase input ends of HFLMC-1 and HFLMC-2 are connected in parallel to the three-phase power grid, the negative electrode of the HFLMC-1 output capacitor is connected to the positive electrode of the HFLMC-2 output capacitor, the positive electrode of the HFLMC-1 output capacitor is connected to the positive electrode of the load battery, and the negative end of the HFLMC-2 output capacitor is connected to the negative electrode of the battery load.

[0060] exist Figure 1 In, e a 、e b 、e c is the three-phase grid voltage, L1, C1, L2, and C2 are the second-order LC low-pass filters on the AC side of HFLMC-1 and HFLMC-2 respectively, and S apl1 , S aph1 , S bpl1 , S bph1 , S cpl1 , S cph1 , S anl1 , S anh1 , S bnl1 , S bnh1 , S cnl1 , S cnh1 The three-phase / single-phase AC-DC matrix structure of HFLMC-1, S apl2 , S aph2 , S bpl2 , S bph2 , S cpl2 , S cph2 , S anl2 , S anh2, S bnl2 , S bnh2 , S cnl2 , S cnh2 The three-phase / single-phase AC-DC matrix structure of HFLMC-2 is composed of T1 and T2, which are high-frequency transformers of HFLMC-1 and HFLMC-2 respectively. 11 , S 12 , S 13 , S 14 , S 21 , S 22 , S 23 , S 24 They are the output rectifier full bridge of HFLMC-1 and HFLMC-2, L dc1 , C o1 , L dc2 , C o2 They are the DC side second-order LC low-pass filters of HFLMC-1 and HFLMC-2, respectively. o1 、v o2 are the output voltages of HFLMC-1 and HFLMC-2, v o is the battery voltage, i o is the output current of IPOS-HFLMC.

[0061] In this embodiment, the modular high-frequency link matrix converter adopts an input side parallel and output side series connection mode; in other embodiments, the modular high-frequency link matrix converter may also adopt an input side parallel and output side parallel connection mode, an input side cascade and output side parallel connection mode, and an input side cascade and output side series connection mode, all of which are within the protection scope of the present disclosure.

[0062] Embodiment 2

[0063] Embodiment 2 of the present disclosure introduces a highly efficient bidirectional power conversion module reliable parallel control system based on the modular high-frequency link matrix converter introduced in Embodiment 1.

[0064] In this embodiment, the power balancing backstepping control includes an input current balancing backstepping control module (current balancing mode) and an output voltage balancing backstepping control module (voltage balancing mode). In the actual battery charging and discharging process, there are two modes: constant current charging and discharging and constant voltage charging and discharging. The input current balancing backstepping control module mentioned in the embodiment is suitable for constant current charging and discharging, and the output voltage balancing backstepping control module is suitable for constant voltage charging and discharging. The overall control block diagram is as follows: Figure 2 shown.

[0065] Current sharing mode

[0066] The input current sharing backstepping control module includes an output current outer loop backstepping controller, an output voltage middle loop backstepping control unit (including a first output voltage middle loop backstepping controller and a second output voltage middle loop backstepping controller), and an input current inner loop backstepping control unit (including a first input current inner loop backstepping controller and a second input current inner loop backstepping controller). The specific working process is as follows:

[0067] 1) Given the output current reference value i o * , output current i o and the total output voltage v o The output current is sent to the output current outer loop back-stepping controller to calculate the output voltage reference value v of HFLMC-1 and HFLMC-2. o1 * 、v o2 * and output current error variable z1;

[0068] 2) Set the output voltage v of HFLMC-1 o1 , output current i o , and step 1) to obtain the output voltage reference value v of the HFLMC-1 module o1 * The output current error variable z1 is sent to the first output voltage mid-loop back-stepping controller to calculate the reference value i of the input current of HFLMC-1 on the active component d axis. d1 * and output voltage error variable z 21 Similarly, HFLMC-2 calculates the reference value i of the input current of HFLMC-2 in the active component d axis through the second output voltage mid-loop back-stepping controller d2 * and output voltage error variable z 22 ;

[0069] 3) The three-phase current i of HFLMC-1 abc1 and the bridge arm midpoint voltage v abc1 After coordinate transformation abc-dq, we get i d1 、i q1 、v d1 、v q1 , and the reference value i of the input current on the d axis obtained in step 2) d1 * and output voltage error variable z 21 The modulation ratio m of HFLMC-1 is calculated and sent to the first input current inner loop backstepping controller. d1 Similarly, the modulation ratio m of HFLMC-2 is calculated by the second input current inner loop backstepping controller. d2 ;

[0070] 4) Three-phase voltage e abc The phase angle θ of the grid voltage is obtained by the phase-locked loop PLL and compared with the modulation ratio m obtained in step 3). d1 、m d2 Input bipolar current space vector modulation together;

[0071] 5) Bipolar current space vector modulation generates a control pulse signal of a three-phase / single-phase AC-DC matrix structure to drive a bidirectional switch of the three-phase / single-phase AC-DC matrix structure.

[0072] Pressure balance mode

[0073] The output voltage equalization backstepping control module includes an output voltage outer loop backstepping control unit (including a first output voltage outer loop backstepping controller and a second output voltage outer loop backstepping controller), an input current inner loop backstepping control unit (including a first input current inner loop backstepping controller and a second input current inner loop backstepping controller), and the specific working process is as follows:

[0074] 1) Given the output voltage reference value v o * The output voltage reference value of HFLMC-1 and HFLMC-2 is obtained by dividing by the number of modules and comparing it with the measured output current actual value i o The actual output voltage value v of HFLMC-1 is sent to the first output voltage outer loop backstepping controller and the second output voltage outer loop backstepping controller respectively. o1 Entering the first output voltage outer loop back-stepping controller, the actual output voltage value of HFLMC-2 is v o2 Enter the second output voltage outer loop backstepping controller; the first output voltage outer loop backstepping controller calculates the reference value i of the input current on the active component d axis d1 * and output current error variable z 21 The second output voltage outer loop backstepping controller calculates the reference value i of the input current in the active component d axis d2 * and output current error variable z 22 ;

[0075] 2) Actual value of three-phase current of HFLMC-1 abc1 and the bridge arm midpoint voltage v abc1 After coordinate transformation abc-dq, we get i d1 、i q1 、v d1 、v q1 , and the reference value i of the input current on the d-axis obtained in step 1) d1 * and output current error variable z 21The modulation ratio m of HFLMC-1 is calculated and sent to the first input current inner loop backstepping controller. d1 Similarly, the modulation ratio m of HFLMC-2 is calculated by the second input current inner loop backstepping controller. d2 ;

[0076] 3) Three-phase voltage e abc The phase angle θ of the grid voltage obtained by the phase-locked loop PLL is equal to the modulation ratio m obtained in step 2). d1 、m d2 Input bipolar current space vector modulation together;

[0077] 4) Bipolar current space vector modulation generates a control pulse signal of a three-phase / single-phase AC-DC matrix structure to drive a bidirectional switch of the three-phase / single-phase AC-DC matrix structure.

[0078] Embodiment 3

[0079] Embodiment 3 of the present disclosure introduces a method for a reliable parallel control system of high-efficiency bidirectional power conversion modules based on the one described in embodiment 1.

[0080] A reliable parallel control method for high-efficiency bidirectional power conversion modules includes a current sharing mode and a voltage sharing mode; wherein the specific process of the current sharing mode is:

[0081] According to the received given output current reference value and the output current actual value and output voltage actual value of the modular high frequency chain matrix converter, an output voltage reference value and an output current error variable of each HFLMC module are obtained;

[0082] According to the output current actual value and the output voltage actual value of the modular high-frequency link matrix converter, as well as the reference value of the input current in the active component d-axis and the output current error variable, the reference value of the input current in the active component d-axis and the output voltage error variable of the modular high-frequency link matrix converter are obtained;

[0083] The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output voltage error variable of the modular high-frequency link matrix converter;

[0084] According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained;

[0085] The specific process of the pressure equalization mode is as follows:

[0086] According to the received given output voltage reference value and the output current actual value and output voltage reference value of the modular high-frequency chain matrix converter, a reference value of the input current in the active component d axis and an output current error variable are obtained;

[0087] The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output current error variable of the modular high-frequency link matrix converter;

[0088] According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained.

[0089] As one or more implementation methods, under the three-phase grid voltage balance condition, if the loss is not considered, according to the power conservation law, it can be obtained that

[0090]

[0091] Since the output side is connected in series and the average current flowing into each output voltage divider capacitor is zero in steady state, it is obvious that

[0092] i dc1 =i dc2 (2)

[0093] If output voltage equalization control is adopted, v o1 =v o2 , and ensure the unity power factor on the grid side Then the grid-side currents of modules HFLMC-1 and HFLMC-2 are equal I a1 =I a2 Therefore, while controlling the output voltage of the IPOS-HFLMC system, ensuring the same power factor angle of the grid-side current, the output voltage and input current can be achieved simultaneously. Next, we only need to design an output voltage equalization backstepping controller to achieve v o1 =v o2 .

[0094] If input current sharing control is used, I a1 =I a2 , and ensure the unity power factor on the grid side Then the output voltages of modules HFLMC-1 and HFLMC-2 are equal. o1 =v o2 Therefore, while controlling the current sharing on the input side of the IPOS-HFLMC system, ensuring the same power factor angle of the grid-side current, the input current sharing and output voltage sharing can be achieved simultaneously. Next, we only need to design an input current sharing backstepping controller to achieve I a1 =I a2 Therefore, the power balance research system can be summarized as follows: Figure 3 .

[0095] The topological structures of the two modules are exactly the same. Next, the modeling process and the design process of the backstepping controller are introduced using the module HFLMC-1 as an example.

[0096] 1. Establish the mathematical model of high-frequency link matrix converter

[0097] Under the voltage balance condition of the three-phase power grid, according to Kirchhoff's law, the grid-side loop equation of the high-frequency link matrix converter is established and converted to the dq two-phase synchronous rotating coordinate system:

[0098]

[0099] Among them, e d 、e q is the active and reactive components of the grid voltage, i d 、i q is the active and reactive components of the grid current, i dt 、i qt is the active and reactive components of the input current of the three-phase / single-phase AC-DC matrix structure, v d 、v q is the active and reactive components of the midpoint voltage of the bridge arm of the three-phase / single-phase AC-DC matrix structure, ω is the angular velocity of the grid, m d and m q The output voltage equalization backstepping controller in voltage equalization mode and the input current equalization backstepping controller in current equalization mode control the modulation ratio m of the active component. d Realize the control of output voltage and current.

[0100] When the grid side has unity power factor, e q =i q =0,e d =E m , the power balance expression on the AC side and the DC side is:

[0101]

[0102] In the voltage-balanced mode, the differential equation of the DC side of the high-frequency link matrix converter is established:

[0103]

[0104] Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of HFLMC-1, i dc is the output current of the output rectifier full bridge, i o is the output current of IPOS-HFLMC, L dcis the output filter inductor, C o is the output filter capacitor. d1(t)d2(t) represents the voltage and current disturbances on the output side, |d1(t)|<ρ1,|d2(t)|<ρ2, ρ1,ρ2 are positive real numbers.

[0105] In the current sharing mode, the differential equation of the DC side of the high-frequency link matrix converter is established

[0106]

[0107] Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of HFLMC-1, i dc is the output current of the output rectifier full bridge, i o is the output current of IPOS-HFLMC, L dc is the output filter inductor, C o is the output filter capacitor. d(t) represents the total disturbance on the output side, |d(t)|<ρ, ρ is a positive real number.

[0108] 2. Output voltage equalization backstepping controller design

[0109] According to the backstepping control principle, the system error variable is first defined as:

[0110]

[0111] The differential of the systematic error variable is given by:

[0112]

[0113] (1) Design of output voltage outer loop backstepping controller

[0114] The output voltage outer loop backstepping controller aims to control the output voltage v o , Tracking reference value v o * .

[0115] The Lyapunov energy function is defined as Then its first-order derivative is:

[0116]

[0117] when It is negative timing, which can ensure the stability of the output voltage outer loop. Therefore, the output voltage outer loop backstepping controller can be designed as

[0118]

[0119] Where sgn(·) is a sign function, K1, K2 and η1, η2 are the parameters of the outer loop backstepping controller, all of which are positive real numbers.

[0120] In the above formula, i d * It can be regarded as an introduced virtual control variable and also the reference value of the input current inner loop backstepping controller.

[0121] Substituting the designed output voltage outer loop backstepping controller (12) into equation (11), we can get

[0122]

[0123] According to formula (13), when z3 approaches zero and ρ1<η1, ρ2<η2, it can be satisfied

[0124] The next step is to design an input current inner loop backstepping controller so that z3 tends to zero.

[0125] (2) Input current inner loop backstepping controller design

[0126] The control objective of the input current inner loop backstepping controller is to control the active component of the input current i d and v d Track reference value i respectively d * and v d * .

[0127] The Lyapunov energy function of the entire high-frequency link matrix converter system can be defined as

[0128]

[0129] Taking the derivative of formula (14), we can get

[0130]

[0131] when It is negative timing, which can ensure the stability of the entire closed-loop system. Therefore, the input current inner loop backstepping controller can be designed as

[0132]

[0133] Among them, K3 and K4 are the parameters of the inner loop controller, both of which are positive real numbers.

[0134] Substituting the designed input current inner loop backstepping controller formula (16) into formula (15), we can get

[0135]

[0136] Among them, the coefficient K = min{2K1, 2K2, 2K3, 2K4}.

[0137] When ρ1<η1,ρ2<η2, that is, the perturbation is bounded, the derivative of the Lyapunov energy function is is a negative definite function, so the system is globally asymptotically stable.

[0138] In summary, the output voltage equalization backstepping controller of the modular high-frequency link matrix converter is:

[0139]

[0140] 3. Input current sharing back-stepping controller design

[0141] According to the backstepping control principle, the system error variable is first defined as:

[0142]

[0143] The differential of the systematic error variable is given by:

[0144]

[0145] (1) Design of output current outer loop backstepping controller

[0146] The output current outer loop backstepping controller aims to control the output current i o , Tracking reference value i o * .

[0147] The Lyapunov energy function is defined as Then its first-order derivative is

[0148]

[0149] when It is negative timing, which can ensure the stability of the output current outer loop. Therefore, the output current outer loop backstepping controller can be designed as

[0150]

[0151] Where sgn(·) is the sign function, K1 and η are the parameters of the outer and inner loop controllers, both of which are positive real numbers.

[0152] In the above formula, i d * It can be regarded as an introduced virtual control variable and also the reference value of the input current inner loop backstepping controller.

[0153] Substituting the designed output current outer loop backstepping controller (21) into equation (20), we can get

[0154]

[0155] According to (22), when z2 approaches zero and ρ<η, it can be satisfied

[0156] The next step is to design an output voltage mid-loop backstepping controller so that z2 approaches zero.

[0157] (2) Design of output voltage mid-loop backstepping controller

[0158] The control objective of the output voltage back-stepping controller is to control the output voltage v dc Tracking reference value v dc * .

[0159] The Lyapunov energy function of the middle ring is defined as Then its first-order derivative is

[0160]

[0161] when It is negative timing, which can ensure the stability of the output voltage loop. Therefore, the output voltage loop backstepping controller can be designed as

[0162]

[0163] Where K2 is the parameter of the middle loop controller, which is a positive real number.

[0164] Substituting the designed output voltage mid-loop back-stepping controller (24) into equation (23), we can get

[0165]

[0166] According to (25), when z3 approaches zero and ρ<η, it can be satisfied

[0167] The next step is to design an input current inner loop backstepping controller so that z3 tends to zero.

[0168] (3) Input current inner loop backstepping controller design

[0169] The control objective of the input current inner loop backstepping controller is to control the active component of the input current i d and v d Track reference value i respectively d * and v d * .

[0170] The Lyapunov energy function of the entire high-frequency link matrix converter system can be defined as

[0171]

[0172] Taking the derivative of the above formula, we can get

[0173]

[0174] when It is negative timing, which can ensure the stability of the entire closed-loop system. Therefore, the input current inner loop backstepping controller can be designed as

[0175]

[0176] Among them, K3 and K4 are the parameters of the inner loop controller, both of which are positive real numbers.

[0177] Substituting the designed input current inner loop backstepping controller formula (28) into formula (27), we can get

[0178]

[0179] Among them, the coefficient K = min{2K1, 2K2, 2K3, 2K4}.

[0180] When ρ < η, that is, the perturbation is bounded, the derivative of the Lyapunov energy function is is a negative definite function, so the system is globally asymptotically stable.

[0181] In summary, the input current sharing backstepping controller of the modular high-frequency link matrix converter is:

[0182]

[0183] Next, the power balancing backstepping control method proposed in this embodiment that can simultaneously achieve output side voltage balancing and input side current balancing is verified by software simulation. The simulation software is MATLAB / Simulink 2017b. The simulation parameters are shown in Table 1. In order to make the parameter inconsistency phenomenon more obvious, the transformer ratio of HFLMC-2 is changed to 100:110 in the simulation, which is an extremely harsh working condition. The other parameters are consistent.

[0184] Table 1 Simulation parameters

[0185]

[0186] The power balancing backstepping control method proposed in this embodiment is applied to compare the simulation effect with the open-loop control. Figure 4 is a simulation comparison result of applying the open-loop control and the output voltage equalization backstepping control method proposed in this embodiment. Before applying the method proposed in this embodiment, the output current i oThere are slight fluctuations, and the input current and output voltage of the two modules are unbalanced, that is, the input current i of HFLMC-1 is a1 Less than the input current i of HFLMC-2 b2 , the output voltage of HFLMC-1 is v o1 Less than the output voltage v of HFLMC-2 o2 After applying the method proposed in this embodiment, the output current i o The small fluctuations are eliminated, and the input current and output voltage of each module are in a balanced state. In addition, in the process of switching from open-loop control to the method proposed in this embodiment, no overshoot occurs, and the control is fast and stable.

[0187] Figure 5 It is the simulation comparison result of applying open-loop control and the input current equalization backstepping control method proposed in this embodiment. Before applying the method proposed in this embodiment, the input current and output voltage of the two modules are unbalanced, that is, the input current i of HFLMC-1 is a1 Less than the input current i of HFLMC-2 b2 , the output voltage of HFLMC-1 is v o1 Less than the output voltage v of HFLMC-2 o2 , and the output current i o After applying the method proposed in this embodiment, the input current and output voltage of each module reach a balanced state, and the output current i o The small fluctuations are eliminated. In addition, no overshoot occurs during the process of switching from open-loop control to the method proposed in this embodiment, and the control is fast and stable.

[0188] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A high-efficiency bidirectional power conversion module reliable parallel control system, used for a modular high-frequency link matrix converter, comprising a first high-frequency link matrix converter submodule and a second high-frequency link matrix converter submodule; the three-phase input ends of the first high-frequency link matrix converter submodule and the second high-frequency link matrix converter submodule are connected in parallel to a three-phase power grid, the negative electrode of the output capacitor of the first high-frequency link matrix converter submodule is connected to the positive electrode of the output capacitor of the second high-frequency link matrix converter submodule, the positive electrode of the output capacitor of the first high-frequency link matrix converter submodule is connected to the positive electrode of the load battery, and the negative end of the output capacitor of the second high-frequency link matrix converter submodule is connected to the negative electrode of the battery load, characterized in that: include: Bipolar current space vector modulation module, input current sharing backstepping control module and output voltage sharing backstepping control module; wherein the input current sharing backstepping control module includes an output current outer loop backstepping controller, an output voltage middle loop backstepping control unit, and an input current inner loop backstepping control unit; the output voltage sharing backstepping control module includes an output voltage outer loop backstepping control unit and an input current inner loop backstepping control unit; The output current outer loop backstepping controller obtains the output voltage reference value and the output current error variable of each high-frequency link matrix converter submodule according to the received given output current reference value and the output current actual value and the output voltage actual value of the modular high-frequency link matrix converter; The output voltage mid-loop back-stepping control unit obtains a reference value of the input current of the modular high-frequency link matrix converter in the active component d-axis and an output voltage error variable according to the output current actual value and the output voltage actual value of the modular high-frequency link matrix converter, as well as the output voltage reference value and the output current error variable; The output voltage outer loop backstepping control unit obtains a reference value of the input current in the active component d-axis and an output current error variable according to the received given output voltage reference value and the output current actual value and output voltage actual value of the modular high-frequency chain matrix converter; The input current inner loop backstepping control unit calculates the modulation ratio of the three-phase current active component according to the three-phase current of the modular high-frequency link matrix converter, the bridge arm midpoint voltage, and the output of the output voltage middle loop backstepping control unit or the output voltage outer loop backstepping control unit; The bipolar current space vector modulation module obtains a control pulse signal for driving a bidirectional switch of a modular high-frequency link matrix converter according to the modulation ratio of the three-phase current active component.

2. A high-efficiency bidirectional power conversion module reliable parallel control system as described in claim 1, characterized in that: The high-efficiency bidirectional power conversion module reliable parallel control system also includes a phase-locked loop module and a coordinate transformation module; the phase-locked loop module obtains the phase angle of the grid voltage according to the actual value of the three-phase voltage; the coordinate transformation module obtains the active component and reactive component of the grid current according to the actual value of the three-phase current.

3. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 1, characterized in that: The output voltage mid-ring backstepping control unit is used to control the output voltage and track the reference voltage; the output voltage mid-ring backstepping control unit includes a first output voltage mid-ring backstepping controller and a second output voltage mid-ring backstepping controller; the first output voltage mid-ring backstepping controller is used for a first high-frequency link matrix converter submodule, and the second output voltage mid-ring backstepping controller is used for a second high-frequency link matrix converter submodule.

4. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 3, characterized in that: The input current inner loop backstepping control unit is used to control the active component of the input current and the active component of the bridge arm midpoint voltage, and track the reference value of the active component of the input current and the reference value of the active component of the bridge arm midpoint voltage; the input current inner loop backstepping control unit includes a first input current inner loop backstepping controller and a second input current inner loop backstepping controller; the first input current inner loop backstepping controller is used for the first high-frequency link matrix converter submodule, and the second input current inner loop backstepping controller is used for the second high-frequency link matrix converter submodule.

5. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 4, characterized in that: The output voltage outer loop backstepping control unit is used to control the total output voltage and track a given output voltage reference value; the output voltage outer loop backstepping control unit includes a first output voltage outer loop backstepping controller and a second output voltage outer loop backstepping controller; the first output voltage outer loop backstepping controller is used for a first high-frequency link matrix converter submodule, and the second output voltage outer loop backstepping controller is used for a second high-frequency link matrix converter submodule.

6. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 1, characterized in that: Under the voltage balance condition of the three-phase power grid, according to Kirchhoff's law, the grid-side loop equation of the high-frequency link matrix converter in the dq two-phase synchronous rotating coordinate system is established as follows: Among them, e d 、e q Represent the active and reactive components of the grid voltage respectively, i d 、i q Represent the active and reactive components of the grid current respectively, i dt 、i qt They represent the active and reactive components of the input current of the three-phase / single-phase AC-DC matrix structure, respectively, and v d 、v q They represent the active component and reactive component of the midpoint voltage of the bridge arm of the three-phase / single-phase AC-DC matrix structure, ω represents the angular velocity of the grid, m d and m q are the modulation ratios of the active and reactive components of the three-phase current, respectively. R is the damping resistor, L is the input filter inductor, C is the input filter capacitor, n is the transformer turns ratio, and i dc Represents the output current of the output rectifier full bridge.

7. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 6, characterized in that: In the input current sharing backstepping control module, the differential equation of the DC side of the high-frequency link matrix converter is established as: Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of the first high-frequency link matrix converter submodule, i dc is the output current of the output rectifier full bridge, i o is the output current of the modular high-frequency link matrix converter, L dc is the output filter inductor, C o is the output filter capacitor, d(t) represents the total disturbance on the output side, |d(t)|<ρ, ρ is a positive real number.

8. A high-efficiency bidirectional power conversion module reliable parallel control system as claimed in claim 7, characterized in that: In the output voltage equalization backstepping control module, the differential equation of the DC side of the high-frequency link matrix converter is established as: Among them, v dc is the output voltage of the output rectifier full bridge, v o is the output voltage of the first high-frequency link matrix converter submodule, i dc is the output current of the output rectifier full bridge, i o is the output current of the modular high-frequency link matrix converter, L dc is the output filter inductor, C o is the output filter capacitor, d1(t) and d2(t) represent the voltage disturbance and current disturbance on the output side respectively, |d1(t)|<ρ1,|d2(t)|<ρ2, ρ1, ρ2 are positive real numbers.

9. A modular high-frequency link matrix converter power balancing backstepping control method, used in a high-efficiency bidirectional power conversion module reliable parallel control system as claimed in any one of claims 1 to 8, characterized in that: Including current sharing mode and voltage sharing mode; The specific process of the current sharing mode is as follows: According to the received given output current reference value and the output current actual value and output voltage actual value of the modular high-frequency link matrix converter, an output voltage reference value and an output current error variable of each high-frequency link matrix converter submodule are obtained; According to the output current actual value and output voltage actual value of the modular high-frequency link matrix converter, as well as the output voltage reference value and the output current error variable, the reference value of the input current of the modular high-frequency link matrix converter in the active component d-axis and the output voltage error variable are obtained; The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output voltage error variable of the modular high-frequency link matrix converter; According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained; The specific process of the pressure equalization mode is as follows: According to the received given output voltage reference value and the output current actual value and output voltage actual value of the modular high-frequency chain matrix converter, a reference value of the input current in the active component d-axis and an output current error variable are obtained; The modulation ratio of the three-phase current active component is calculated based on the three-phase current, the bridge arm midpoint voltage, the reference value of the input current in the active component d axis and the output current error variable of the modular high-frequency link matrix converter; According to the modulation ratio of the active component of the three-phase current, a control pulse signal for driving the bidirectional switch of the modular high-frequency link matrix converter is obtained.

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