Converter backflow power suppression method, device and system and storage medium

Abstract

The invention provides a backflow power suppression method, device and system of a converter and a readable storage medium, and the method comprises the steps: calculating a first modulation parameter of the converter based on the output voltage of the converter, and outputting a plurality of first target driving signals for driving a part of switching tubes to be switched on or switched off based on the first modulation parameter, therefore, closed-loop control on the output voltage of the converter is realized; after closed-loop control, calculating a second modulation parameter when the backflow power of the converter is smaller than or equal to a preset threshold value based on the first modulation parameter; wherein one of the first modulation parameter and the second modulation parameter is a phase shift ratio, and the other one is a modulation ratio; and respectively outputting a plurality of second target driving signals for driving the other switching tubes to be switched on or switched off based on the second modulation parameter, thereby controlling the backflow power in the switching period of the converter within a certain range. Through the implementation of the scheme, the efficiency and the service life of the converter can be remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a method, device, system and readable storage medium for suppressing backflow power of a converter. Background Art

[0002] In recent years, the global new energy vehicle market has grown rapidly, and the market demand for high-performance fast charging / supercharging has become increasingly urgent. In related technologies, electric vehicle charging systems are usually implemented using a two-stage architecture, and its shortcomings are mainly reflected in two aspects: first, the power passes through two-stage converters, so the efficiency and power density are limited; second, the intermediate bus often requires a large-capacity electrolytic capacitor, which not only increases the system cost, but also reduces the life and reliability of the system. Single-stage isolated AC / DC converters can improve efficiency and power density because energy is only converted through a single-stage power conversion; at the same time, the electrolytic capacitor on the intermediate bus is also eliminated, so it has received more and more attention and research.

[0003] Modulation ratio and phase shift angle are two important parameters for the converter to stabilize the output voltage. The related technology usually adopts a method of controlling the output voltage of the converter by adjusting the primary-secondary phase shift angle with a fixed modulation ratio or by adjusting the primary-secondary phase shift angle with a fixed modulation ratio. This control method causes the primary side of the converter to uncontrollably feed back the power to the input source (such as Figure 1 The situation is even worse when the input and output voltages do not match.

[0004] The existence of return power requires the input source to provide greater forward power under the same output power, thereby raising the current, resulting in an increase in the effective current value and current peak value; a higher effective current value will bring higher conduction losses to switching devices and magnetic devices, and a higher current peak value will bring greater turn-off losses, which will also shorten the life of power devices. Summary of the invention

[0005] The embodiments of the present application provide a method, device, system and readable storage medium for suppressing the backflow power of a converter, which can at least solve the problem in the related art that the efficiency and service life of the converter need to be improved.

[0006] In a first aspect, an embodiment of the present application provides a method for suppressing backflow power of a converter; the converter includes a matrix circuit, an inductor, an isolation transformer and a full-bridge circuit, the matrix circuit is connected to the primary side of the isolation transformer through the inductor, the full-bridge circuit is connected to the secondary side of the isolation transformer, and the matrix circuit is used to connect three-phase alternating current; the matrix circuit and the full-bridge circuit are respectively provided with a plurality of switch tubes; the method for suppressing backflow power includes:

[0007] After the matrix circuit is connected to the three-phase alternating current, a first modulation parameter of the converter is calculated based on the output voltage of the converter, and a plurality of first target drive signals are output based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter;

[0008] After the closed-loop control of the converter is completed, a second modulation parameter of the converter is calculated based on the first modulation parameter when the reflux power is less than or equal to a preset threshold; wherein the first modulation parameter and the second modulation parameter, one is a modulation ratio and the other is a shift ratio;

[0009] Based on the second modulation parameter, multiple second target drive signals are output respectively; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit, and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control the switch tubes on the full-bridge circuit to be turned on or off.

[0010] In a second aspect, an embodiment of the present application provides a backflow power suppression device for a converter; the converter includes a matrix circuit, an inductor, an isolation transformer and a full-bridge circuit, the matrix circuit is connected to the primary side of the isolation transformer through the inductor, the full-bridge circuit is connected to the secondary side of the isolation transformer, and the matrix circuit is used to connect three-phase alternating current; the matrix circuit and the full-bridge circuit are respectively provided with a plurality of switch tubes; the backflow power suppression device includes:

[0011] A first calculation module is used to calculate a first modulation parameter of the converter based on the output voltage of the converter after the matrix circuit is connected to the three-phase alternating current, and output a plurality of first target drive signals based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter;

[0012] A second calculation module is used to calculate, after completing the closed-loop control of the converter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold based on the first modulation parameter; wherein the first modulation parameter and the second modulation parameter, one is a modulation ratio and the other is a shift ratio;

[0013] An output module is used to output multiple second target drive signals based on the second modulation parameter; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is a switch tube on the matrix circuit, and the other is a switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control the switch tubes on the full-bridge circuit to be turned on or off.

[0014] A third aspect of an embodiment of the present application provides a backflow power suppression system, comprising: a converter and a controller, the converter and the controller are electrically connected, wherein the converter comprises a matrix circuit, an isolation transformer and a full-bridge circuit, the matrix circuit is connected to the primary side of the isolation transformer through an inductor, the full-bridge circuit is connected to the secondary side of the isolation transformer, and the matrix circuit is used to access three-phase alternating current; the matrix circuit and the full-bridge circuit are respectively provided with multiple switching tubes; the controller is used to implement each step in the backflow power suppression method of the converter provided in the first aspect of the embodiment of the present application.

[0015] The fourth aspect of the embodiments of the present application provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a controller, the steps of the method for suppressing the backflow power of the converter provided in the first aspect of the embodiments of the present application are implemented.

[0016] As can be seen from the above, according to the converter backflow power suppression method, device, system and readable storage medium provided by the present application scheme; after the matrix circuit is connected to the three-phase alternating current, the first modulation parameter of the converter is calculated based on the output voltage of the converter, and multiple first target drive signals are output based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter; after completing the closed-loop control of the converter, the second modulation parameter of the converter is calculated based on the first modulation parameter when the backflow power is less than or equal to the preset threshold value; wherein, the first The modulation parameter and the second modulation parameter, one is the modulation ratio and the other is the shift ratio; based on the second modulation parameter, a plurality of second target drive signals are output respectively; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off, so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control the switch tubes on the full-bridge circuit to be turned on or off. In the present application scheme, one of the shift ratio or the modulation ratio is adjusted first to realize the closed-loop control of the output voltage; then the other modulation parameter in the shift ratio or the modulation ratio is adjusted to drive the corresponding switch tubes to be turned on or off at the appropriate time, so as to suppress the reflux power, reduce the effective value of the current, and improve the efficiency and life of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the effect of reflux power in the related art;

[0018] Figure 2 A schematic diagram of the structure of a converter provided in the first embodiment of the present application;

[0019] Figure 3 A basic flow chart of a method for suppressing backflow power of a converter provided in the second embodiment of the present application;

[0020] Figure 4 An effective vector distribution diagram provided for the second embodiment of the present application;

[0021] Figure 5 Schematic diagram of the effect of an outward phase shift and an inward phase shift in a dual phase shift mode provided in the second embodiment of the present application

[0022] Figure 6 A schematic diagram of the effect of a phase shift comparison in a single phase shift mode provided in the second embodiment of the present application;

[0023] Figure 7This is a control block diagram for suppressing reflux power when closed-loop control of output voltage is performed by adjusting the modulation ratio in the second embodiment of the present application;

[0024] Figure 8 This is a control block diagram for suppressing reflux power when closed-loop control of output voltage is performed by adjusting the shift phase in the second embodiment of the present application;

[0025] Fig. 9 An inductor current waveform diagram provided for the second embodiment of the present application;

[0026] Fig.10 The inductor current waveform diagram of the related art;

[0027] Fig.11 A 12-sector space vector diagram provided in the second embodiment of the present application;

[0028] Fig.12 A curve diagram showing a change in a zero-return power time-shift phase angle with a second modulation parameter provided in the second embodiment of the present application;

[0029] Fig.13 A schematic diagram of a control model for achieving zero reflux power provided in the third embodiment of the present application;

[0030] Fig.14 A schematic diagram of a control model for achieving zero reflux power provided in the fourth embodiment of the present application;

[0031] Fig.15 A schematic diagram of a program module of a backflow power suppression device for a converter provided in the fifth embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0033] In the description of the embodiments of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0035] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] In order to solve the problem that the efficiency and service life of the converter in the related technology need to be improved, the first embodiment of the present application provides a backflow power suppression system, including a converter and a controller, the converter is electrically connected to the controller, and the controller is used to implement the backflow power suppression method of the converter.

[0037] Specifically, the converter in this embodiment can be a matrix-dual active bridge AC / DC converter. The matrix-dual active bridge AC / DC converter has a streamlined circuit structure and a low-impedance current path. The primary matrix circuit can efficiently convert the three-phase industrial frequency input into a volt-second balanced high-frequency AC square wave, and send it to the primary side of the isolation transformer, and cooperate with the secondary full-bridge circuit to perform phase shift control similar to the DC / DC dual active bridge, so as to achieve the effect of output voltage regulation and input power factor correction (PFC).

[0038] In some implementations of this embodiment, the converter includes an LC filter, a matrix circuit, an inductor, an isolation transformer, and a full-bridge circuit. The matrix circuit includes three bridge arms, each of which includes two bidirectional switches connected in series, and the bidirectional switch is composed of two switch tubes connected in series inversely. The two ends of the bridge arm of the matrix circuit are connected to the primary side of the isolation transformer through the inductor, and the three-phase alternating current is connected to the midpoints of the three bridge arms of the matrix circuit respectively after passing through the LC filter. The midpoint of the bridge arm of the full-bridge circuit is connected to the secondary side of the isolation transformer, and the two ends of the full-bridge circuit are connected to the output capacitor and then connected to an external load or battery.

[0039] like Figure 2As shown, in some implementations of this embodiment, the LC filter includes capacitors and inductors, that is, the converter includes three AC side inductors, three AC side capacitors, a matrix circuit, an isolation transformer, a full-bridge circuit, an output capacitor and a load; the matrix circuit has three bridge arms, one ends of the three AC side inductors are respectively connected to the three-phase AC power supply port, and the other ends of the three AC side inductors are respectively connected to the midpoints of the three bridge arms of the matrix circuit via the three AC side capacitors.

[0040] In some implementations of this embodiment, a switch tube S is provided in the full bridge circuit. 13 , S 14 , S 15 , S 16 , switch tube S 13 The emitter and switch tube S 14 The collectors of the switch tube S are connected as a bridge arm, and the midpoint of the bridge arm is connected to one end of the secondary side of the isolation transformer; 15 The emitter and switch tube S 16 The collectors of the switch tube S are connected as a bridge arm, and the midpoint of the bridge arm is connected to the other end of the secondary side of the isolation transformer; 13 The collector and switch tube S 15 The collector of is connected as the positive DC side node of the full bridge circuit and connected to one end of the output capacitor Co. The switch tube S 14 The emitter and switch tube S 16 The emitter of is connected as the negative DC side node of the full-bridge circuit and is connected to the other end of the output capacitor Co. The output capacitor Co can also be connected to the load R.

[0041] In some implementations of this embodiment, a plurality of switch tubes S are also provided in the matrix circuit. ap , S bp , S cp , S an , S bn , S cn , each switch tube is composed of two switch tubes connected, that is, S ap Including switch tubes S1 and S2, S bp Including switch tubes S5 and S6, S cp Including switch tube S9 and S 10 , S an Including switch tubes S3 and S4, S bn Including switch tubes S7 and S8, S cn Including switch tube S 11 and S 12 ; AC side inductance L a With switch tube S ap Connection: AC side inductance L b With switch tube S bp Connection: AC side inductance Lc With switch tube S bp Connection: switch tube S ap Connect to one end of the primary side of the isolation transformer; switch tube S an Connect to the other end of the primary side of the isolation transformer; switch tube S bp Connect to one end of the primary side of the isolation transformer, switch tube S bn Connect to the other end of the primary side of the isolation transformer; switch tube S cp Connect to one end of the primary side of the isolation transformer, switch tube S cn Connect to the other end of the primary side of the isolation transformer.

[0042] It should be understood that, in some embodiments, placing the inductor on the primary side or the secondary side of the converter circuit does not affect the working principle of the converter, so changing the position of the inductor does not affect the implementation of the backflow power suppression method in this embodiment. The bidirectional switch of the matrix circuit adopts a common source or common drain connection method, which does not affect the working principle of the converter, so changing the connection method of the bidirectional switch does not affect the implementation of the backflow power suppression method in this embodiment.

[0043] The second embodiment of the present application provides a method for suppressing the backflow power of a converter, which is used to suppress the backflow power of the converter in the first embodiment. Figure 3 The basic flow diagram of the method for suppressing the backflow power of the converter provided in this embodiment is as follows:

[0044] Step 301: After the matrix circuit is connected to the three-phase alternating current, a first modulation parameter of the converter is calculated based on the output voltage of the converter, and a plurality of first target drive signals are output based on the first modulation parameter.

[0045] Specifically, each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter. The first modulation parameter can be a phase shift ratio or a modulation ratio; when the first modulation parameter is a phase shift ratio, the first target switch tube includes each switch tube on the full-bridge circuit, and when the first modulation parameter is a modulation ratio, the first target switch tube includes each switch tube on the matrix circuit. In the specific implementation process, the modulation parameters can be controlled by a preset loop control strategy to achieve the goal of closed-loop control of the output voltage and input current. In this embodiment, the preset loop control strategy can be a control strategy such as PI dual-loop control, dual-loop decoupling + feedforward control, PR dual-loop control, direct power control, etc., which is not limited here.

[0046] Exemplarily, in the PI dual-loop control strategy, the control signal can be continuously updated according to the error feedback, which ultimately plays a role in optimizing the phase shift angle. The dual-loop decoupling + feedforward control strategy can use the decoupling control algorithm to compensate for the non-ideal characteristics of the system. The feedforward control predicts the load changes in advance based on the system model; by combining the feedforward information with the error information, it ensures that the phase shift angle is adjusted in a timely and accurate manner. The PR dual-loop control strategy can periodically detect the harmonic components of the output signal and automatically correct the phase shift angle to optimize the output quality. In the direct power control strategy, the output active power and reactive power are directly controlled, and the phase shift angle is dynamically adjusted according to real-time power monitoring. That is, the power error can be directly fed back and the phase shift angle can be quickly adjusted to maintain power balance.

[0047] Exemplarily, in the PI dual-loop control strategy, the modulation ratio can be changed by adjusting the PI parameters, thereby controlling the output. The dual-loop decoupling + feedforward control strategy is based on the PI dual-loop control, adding decoupling and feedforward links, eliminating the mutual influence between the current loop and the voltage loop through the decoupling link, predicting the system disturbance and compensating in advance through the feedforward link, that is, by optimizing the decoupling and feedforward parameters, the accuracy and dynamic response of the modulation ratio are improved. In the PR dual-loop control strategy, a proportional-resonant (PR) regulator is used to adjust the current and voltage at the same time; the PR regulator has good band-limited characteristics, which can effectively suppress harmonic interference and improve system stability; that is, the modulation ratio can be changed by adjusting the PR parameters to improve the quality of the modulation waveform. In the direct power control strategy, the output active power and reactive power are directly controlled without the current and voltage loops; the modulation ratio is directly determined by calculating the power error to achieve fast and accurate power control.

[0048] Step 302: After the closed-loop control of the converter is completed, a second modulation parameter of the converter is calculated based on the first modulation parameter when the reflux power is less than or equal to a preset threshold.

[0049] Specifically, the first modulation parameter and the second modulation parameter are, one is the modulation ratio and the other is the shift ratio. After the output voltage is closed-loop controlled by the first modulation parameter, a suitable second modulation parameter is calculated; the control freedom (shift ratio and modulation ratio) in the converter is fully utilized to adjust the voltage output, thereby improving the efficiency and life of the converter.

[0050] Step 303: output a plurality of second target driving signals respectively based on the second modulation parameters.

[0051] Specifically, each second target driving signal is used to control the corresponding second target switch tube to turn on or off, so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is a switch tube on the matrix circuit, and the other is a switch tube on the full-bridge circuit; the driving signal corresponding to the modulation ratio is used to control the switching tubes on the matrix circuit to turn on or off, and the driving signal corresponding to the shift ratio is used to control the switching tubes on the full-bridge circuit to turn on or off. That is, when the voltage changes alternately, the corresponding switch tube can be driven to turn on and off in a timely manner through the target driving signal, so that the reflux power of each switching cycle of the converter is controlled within a certain range, thereby improving the efficiency and service life of the converter.

[0052] In one implementation of this embodiment, the phase shift ratio includes an outer phase shift ratio and an inner phase shift ratio; accordingly, the step of calculating the second modulation parameter of the converter when the return power is less than or equal to the preset threshold value based on the first modulation parameter includes: substituting the first modulation parameter into the first target calculation formula to calculate the second modulation parameter when the return power of the converter is less than or equal to the first preset threshold value in the dual phase shift mode; wherein the first target calculation formula is expressed as:

[0053]

[0054] Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, and K5 are preset constant values, d1 represents the outward shift phase ratio, and D2 represents the inward shift phase ratio.

[0055] Further, in an implementation of this embodiment, the step of calculating the second modulation parameter of the converter when the return power is less than or equal to the preset threshold based on the first modulation parameter further includes: substituting the first modulation parameter into the second target calculation formula to calculate the second modulation parameter when the return power of the converter is zero in the dual phase shift mode; wherein the second target calculation formula is expressed as:

[0056] U m M+K1D1U o +K2D2U o +K3U o =0.

[0057] In one implementation of this embodiment, when D2=1+D1, the converter is simplified from the dual-phase shift mode to the single-phase shift mode. Accordingly, the step of calculating the second modulation parameter of the converter when the return power is less than or equal to the preset threshold based on the first modulation parameter includes: substituting the first modulation parameter into the third target calculation formula to calculate the second modulation parameter of the converter when the return power is less than or equal to the second preset threshold in the single-phase shift mode; wherein the third target calculation formula is expressed as:

[0058]

[0059] Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, K5 are preset constant values, and D1 represents the shift ratio. By adjusting the first modulation parameter and the second modulation parameter in this way, the reflux power in the switching cycle can be suppressed to K times the rated power Po.

[0060] Furthermore, the step of calculating the second modulation parameter of the converter when the return power is less than or equal to the preset threshold based on the first modulation parameter further includes: substituting the first modulation parameter into a fourth target calculation formula to calculate the second modulation parameter of the converter when the return power is zero in the single phase shift mode; wherein the fourth target calculation formula is expressed as:

[0061] U m M+(K1+K2)D1U o +(K2+K3)U o =0.

[0062] Specifically, the primary matrix circuit in this embodiment is responsible for converting the three-phase power frequency input into a high-frequency AC square wave with volt-second balance and sending it to the isolation transformer; the matrix circuit has a total of six effective vectors and three zero vectors, and the effective vectors are distributed as follows: Figure 4 As shown. The modulation ratio of the matrix circuit can be defined as the reference vector modulus |I ref | and the effective vector modulus |I AC |Ratio Times, symbolized by M:

[0063]

[0064] In the dual phase shift mode, the modulation ratio M, the primary and secondary phase shift ratios D1 and D2 are coordinated to suppress the reflux power in the matrix-dual active bridge converter, thereby improving the efficiency and life of the converter. Figure 5As shown, when the converter works in dual phase shift mode, there are two phase shifts: outer phase shift D1 and inner phase shift D2. Define outer phase shift D1 = φ1 / π, φ1 is the secondary bridge arm voltage v S The rising edge and matrix circuit output voltage v PN The internal phase shift is D2 = φ2 / π, where φ2 is the secondary bridge arm voltage v S The falling edge and matrix circuit output voltage v PN The phase shift angle of the rising edge.

[0065] like Figure 6 As shown, when D2=1+D1, the converter is simplified from the dual phase shift mode to the single phase shift mode, and the reflux power in the matrix-dual active bridge converter can be suppressed by coordinated control of the modulation ratio M and the primary-secondary phase shift ratio D1.

[0066] In this embodiment, the first preset threshold and the second preset threshold can be values ​​greater than or equal to zero, respectively, and the first preset threshold and the second preset threshold can be equal or unequal. In some specific implementations, when the preset threshold is less than 10% of the output power (that is, when the converter reflux power accounts for less than 10% of the output power), the values ​​of K1, K2, K3, k4, and k5 can be limited based on the method shown in Table 1.

[0067] Table 1:

[0068] parameter Value range <![CDATA[K1]]> [0，20] <![CDATA[K2]]> [-20，20] <![CDATA[K3]]> [-40，0] <![CDATA[K4]]> [0，1] <![CDATA[K5]]> [0，20]

[0069] Of course, the second target calculation formula and the fourth target calculation formula can also be used to adjust the phase shift ratio and the modulation ratio to achieve the ideal effect of controlling the reflux power to zero, thereby further improving the efficiency and life of the converter.

[0070] In one implementation of this embodiment, the modulation ratio can be used to perform closed-loop control of the output voltage, and the corresponding shift ratio can be calculated based on any one of the above-mentioned first target calculation formula, second target calculation formula, third target calculation formula, and fourth target calculation formula, thereby achieving the effect of reflux power suppression. Specifically, Figure 7 As shown, the sampled three-phase input voltage, current and output voltage are sent to the closed-loop controller to calculate the modulation ratio M and the reactive power control quantity u q , M and u q After dq / αβ coordinate transformation, the control quantity u in the αβ coordinate system is obtained α and u β The vector modulator generates the driving signals V for the first to twelfth switch tubes accordingly. GS_1 ~V GS_12 , used to control the first to twelfth switch tubes S1 to S12 The phase shift ratios D1 and D2 are calculated based on any one of the first target calculation formula, the second target calculation formula, the third target calculation formula, and the fourth target calculation formula, and the phase shift ratios D1 and D2 are made to change linearly with the modulation ratio M. The phase shift controller generates the driving signals V of the thirteenth to sixteenth switch tubes based on the phase shift ratios D1 and D2. GS_13 ~V GS_16 , used to control the thirteenth to sixteenth switch tubes S of the full-bridge circuit 13 ~S 16 The turn-on and turn-off of the transistor can achieve the effect of suppressing the reflux power.

[0071] In another implementation of this embodiment, a phase shift ratio can be used to perform closed-loop control of the output voltage, and a corresponding modulation ratio can be calculated based on any one of the first target calculation formula, the second target calculation formula, the third target calculation formula, and the fourth target calculation formula, thereby achieving the effect of reflux power suppression. Specifically, Figure 8 As shown, the sampled output voltage is sent to the closed-loop controller, the output voltage is transformed and controlled, the phase shift phases D1 and D2 are calculated, and the phase shift controller generates the thirteenth to sixteenth drive signals V based on the phase shift phases D1 and D2. GS_13 ~V GS_16 , used to control the thirteenth switch of the full-bridge circuit. At the same time, the corresponding modulation ratio M is calculated according to the shift ratios D1 and D2, and the modulation ratio M changes with the shift ratios D1 and D2. Modulation ratio M and reactive power control quantity u q (When achieving unity power factor control, take u q =0) After dq / αβ coordinate transformation, the control quantity u in the αβ coordinate system is obtained α and u β The vector modulator generates the driving signals V for the first to twelfth switch tubes accordingly. GS_1 ~V GS_12 , used to control the first to twelfth switch tubes S1 to S 12 The on and off of the circuit can achieve the control effect of suppressing the reflux power.

[0072] Under the control conditions of the same hardware parameters (L=10uH, n=1), the same input and output voltage (three-phase AC input: 380V, output: 350V), and the same output power (22kW), when conducting comparative verification tests, the following results can be obtained: Fig. 9 and 10 The effect waveform shown in the figure, Fig. 9 This is a waveform diagram of the effect achieved by the control method of this embodiment. Fig.10This is the effect waveform diagram corresponding to the control scheme of the related technology. It can be seen that when other conditions are the same, the control method of this embodiment can control the reflux power to 0, reduce the effective value of the current to 17%, which is equivalent to reducing the conduction loss to 31%. At the same time, the peak current is reduced to 15.5%, which reduces the turn-off loss by 15.5%; the efficiency of the converter is significantly improved.

[0073] In one implementation of the present embodiment, the backflow power suppression method also includes: obtaining an expression for the zero-crossing moment of the inductor current of the converter; deriving an expression for the backflow power within the fundamental period of the converter based on the expression for the zero-crossing moment of the inductor current; and deriving a target calculation formula based on the backflow power expression.

[0074] Furthermore, in one implementation of the present embodiment, the step of obtaining an expression of the zero-crossing moment of the inductor current of the converter includes: generating a space vector diagram of the converter based on current vectors corresponding to different working modes of the matrix circuit and voltage values ​​of each phase in the three-phase alternating current; wherein the space vector diagram includes multiple sectors, each sector in the time domain corresponds to multiple switching cycles, and each switching cycle corresponds to multiple working modes; based on the symmetrical distribution rule of the vector current in the sector of the space vector diagram and the expression of the inductor current under each working mode, an expression of the zero-crossing moment of the inductor current of the converter is derived.

[0075] Specifically, the matrix circuit can transform the three-phase power frequency input into a volt-second balanced high-frequency AC square wave and send it to the primary side of the isolation transformer. To ensure the normal operation of the circuit, short circuit is not allowed at the input end and open circuit is not allowed at the output end. Nine current vectors can be set, as shown in Table 1. The on / off state of the switch tube corresponding to each vector is represented by 1 / 0, and one current vector corresponds to one working mode.

[0076] Table 1:

[0077]

[0078]

[0079] According to the size of the adjacent vectors and the voltage values ​​of each phase in the three-phase AC, the space vector diagram of the converter is constructed and divided into 12 small sectors, such as Fig.11 The vector selection and corresponding vector action duty ratio in each small sector are shown in Table 2, where D R Represents the duty cycle of the effective vector to the right of the reference vector, D L represents the duty cycle of the effective vector to the left of the reference vector, and D0 represents the duty cycle of the zero effective vector. M is the modulation ratio of the matrix circuit;

[0080] Table 2:

[0081]

[0082] Based on the space vector diagram and the duty cycle of the above current vector, as well as the symmetry characteristics of the sector current vector, a quantitative analysis of the converter's operating mode can be performed to derive a control expression for achieving zero reflux power, which is the above target calculation formula.

[0083] Taking the first sector as an example, that is, determining the first sector as the target sector, the working mode of the converter is quantitatively analyzed:

[0084] Define the phase shift ratio in single phase shift mode: D φ1 =φ1 / π, where φ1 represents the original-secondary side phase shift angle.

[0085] First working mode (t0-t1): primary side S ap and S bn conduction, the output voltage of the matrix circuit is the line voltage u AB , the secondary side S2 and S3 are turned on, and the voltage reflected to the primary side is -nU o The voltage across the transmission inductor L is u AB +nU o , the inductor current rises linearly. At t zc Before the moment (the moment when the inductor current passes through zero), the energy in the inductor is transferred to the primary power supply and the secondary load, and there is reflux power. zc After the moment, the primary power supply and the secondary load store energy in the inductor. The inductor current expression at this stage is:

[0086]

[0087] The inductor current value at the end of the mode is:

[0088]

[0089] Second working mode (t1-t2): primary side S ap and S bn conduction, the output voltage of the matrix circuit is the line voltage u AB , the secondary side S1 and S4 are turned on, and the voltage reflected to the primary side is nU o , the voltage across the inductor L is u AB -nU o , whether the inductor current rises or falls depends on the sign of the voltage at both ends. In this stage, the primary power supply transfers energy to the secondary load. The inductor current expression in this stage is:

[0090]

[0091] The inductor current value at the end of the mode is:

[0092]

[0093] The third working mode (t2-t3): primary side S ap and S cn conduction, the output voltage of the matrix circuit is the line voltage u AC , the secondary side S1 and S4 are turned on, and the voltage reflected to the primary side is nU o , the voltage across the inductor L is u AC -nU o , whether the inductor current rises or falls depends on the sign of the voltage at both ends. In this stage, the primary power supply transfers energy to the secondary load. The inductor current expression in this stage is:

[0094]

[0095] The inductor current value at the end of the mode is:

[0096]

[0097] The fourth working mode (t3-t4): primary side S ap and S an The output voltage of the matrix circuit is 0, the secondary side S1 and S4 are turned on, and the voltage refracted to the primary side is nU o , the voltage across the inductor L is -nU o , the inductor current decreases linearly, and the inductor transfers energy to the secondary load. The inductor current expression at this stage is:

[0098]

[0099] The inductor current value at the end of the mode is:

[0100]

[0101] The operating modes in the second half of the switching cycle are symmetrical to those in the first half of the switching cycle and will not be described in detail here.

[0102] From the current symmetry of a single switching cycle, we know that i L (t4) = -i L (t0), that is:

[0103]

[0104] Simplified, the initial value of the inductor current i in the first sector is L (t0) is expressed as:

[0105]

[0106] Among them, f srepresents the switching frequency, f s =1 / T s , T s Represents the switching cycle.

[0107] Based on the current slope in the inductor current expression corresponding to the first working mode, the expression of the inductor current zero-crossing moment can be derived:

[0108]

[0109] Based on the above expression of the inductor current zero-crossing time, the expression of the return power on the switching cycle scale can be obtained:

[0110]

[0111] The three-phase input line voltage U ab and U ac The expression is:

[0112]

[0113] Where w is the angular frequency of the AC input voltage and pi is the circumference of a circle.

[0114] D in Table 2 R =M*sin(π / 6-ωt) and D L =M*sin(π / 6+ωt) Substitute the duty cycle D of the effective vector on the right side of the reference vector ab and the duty cycle D of the effective vector to the left of the reference vector ac , combined with the above three-phase input line voltage U ab and U ac The above reflux power expression can be further simplified as:

[0115]

[0116] Among them, U m Indicates the peak value of the three-phase AC phase voltage.

[0117] Furthermore, the expression of the return power in the fundamental period can be obtained:

[0118]

[0119] By analyzing the expression of the reflux power in the switching cycle, we can find that: as long as the expression inside the square mode is always controlled to be 0, the reflux power in each switching cycle can be guaranteed to be 0. Furthermore, the reflux power in the input fundamental wave cycle is 0, that is:

[0120] 1.5U m U o +2Dφ1 nU o =0

[0121] Based on this, it can be concluded that when the return power is 0, the relationship between the phase shift angle φ1 and the modulation ratio M (the fifth target calculation formula) is expressed as:

[0122]

[0123] Based on the above target calculation formula, a curve of the modulation ratio M changing with the phase shift angle φ1 at zero reflux power can be drawn, as shown in Fig.12 shown.

[0124] Based on the technical solution of the embodiment of the present application, after the matrix circuit is connected to the three-phase alternating current, the first modulation parameter of the converter is calculated based on the output voltage of the converter, and multiple first target drive signals are output based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize the closed-loop control of the output voltage of the converter; after completing the closed-loop control of the converter, the second modulation parameter of the converter is calculated based on the first modulation parameter when the reflux power is less than or equal to the preset threshold; wherein the first modulation parameter and the second modulation parameter, one is the modulation ratio, and the other is the shift ratio; multiple second target drive signals are output respectively based on the second modulation parameter; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off, so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit, and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control each switch tube on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control each switch tube on the full-bridge circuit to be turned on or off. In the present application scheme, one of the phase shift ratio or the modulation ratio is adjusted first to achieve closed-loop control of the output voltage; then the other modulation parameter in the phase shift ratio or the modulation ratio is adjusted to drive the corresponding switching tubes to turn on or off at the appropriate time, so as to achieve the effect of suppressing backflow power, reducing the effective value of current, and improving the efficiency and life of the converter.

[0125] The third embodiment of the present application provides a method for suppressing the backflow power of a converter, the method comprising: after the matrix circuit is connected to the three-phase alternating current, calculating the shift ratio of the converter based on the output voltage of the converter and performing closed-loop control on the output voltage of the converter; after completing the closed-loop control of the converter, calculating the modulation ratio of the converter when the backflow power is zero based on the shift ratio; outputting target drive signals corresponding to each bidirectional switch tube based on the modulation ratio; wherein each target drive signal is used to drive the conduction and shutdown of the corresponding bidirectional switch tube, so that the backflow power of the converter is zero during the voltage output process.

[0126] In one implementation of the present embodiment, the above-mentioned step of calculating the first modulation parameter of the converter based on the output voltage of the converter after the matrix circuit is connected to the three-phase AC power includes: after the matrix circuit is connected to the three-phase AC power and the first modulation parameter of the converter is determined to be a shift phase, calculating a first error parameter between the output voltage and a preset output voltage reference value; inputting the first error parameter into a preset voltage loop PI regulator to output the shift phase through the voltage loop PI regulator.

[0127] Specifically, Fig.13 The figure shows a schematic diagram of a control model for realizing zero backflow power in a specific implementation method. In order to meet the closed-loop control of the output voltage and the power factor correction control of the input current, a mathematical model corresponding to the converter is constructed based on the PI double-loop control strategy to form a voltage outer loop and a current inner loop. The voltage outer loop is used to control the DC side voltage of the converter, and the current inner loop is used to control the current according to the parameters output by the voltage outer loop.

[0128] The voltage outer loop is composed of U o_ref , U o And PI link composition. o_ref is the output voltage reference value, U o is the output voltage of the converter, PI represents the voltage loop PI regulator, that is, proportional integral regulator. o_ref With output voltage U o The difference (i.e., the first error parameter) is sent to the voltage loop PI regulator, and the voltage loop PI regulator outputs a shift ratio D φ1 ; and the output voltage U can be controlled by the voltage loop PI regulator o Real-time follow reference value U o_ref , to achieve the goal of closed-loop control of the output voltage. Specifically, during the closed-loop control process, when the output voltage is low, U o_ref and U o The difference is positive, the output of the voltage loop PI regulator increases, and the shift ratio is D φ1 As the voltage increases, more energy is transmitted from the primary side to the secondary side, and the output voltage rises, achieving a closed-loop effect.

[0129] In one implementation of this embodiment, after the closed-loop control of the converter is completed, the shift ratio is substituted into the fifth target calculation formula (that is, the specific expression of the fourth target calculation formula) to calculate the modulation ratio of the converter when the reflux power is zero; the fifth target calculation formula is expressed as:

[0130]

[0131] Among them, D φ1 Indicates the shift ratio, U orepresents the output voltage, n represents the primary-to-secondary turns ratio of the isolation transformer, M represents the modulation ratio, U m Indicates the peak value of the three-phase AC phase voltage. φ1 By performing phase shift control on the converter, the reflux power of the converter can be made zero in the full voltage range and full load range.

[0132] Furthermore, in some implementations of the present embodiment, the above-mentioned steps of outputting multiple second target drive signals based on the second modulation parameter include: if the first modulation parameter is a shift ratio, the second modulation parameter is determined as an active control quantity, and the active control quantity and the preset reactive control quantity are input into the first dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; and multiple second target drive signals are output based on the vector modulation parameters.

[0133] Specifically, Fig.13 As shown, the modulation ratio M is determined as the active control quantity, and the preset reactive control quantity u is matched. q By controlling and adjusting, the input power factor can be controlled. In order to achieve the correction control of the input power factor, the reactive control amount u q Set to 0 to control the power factor to 1. M and u q Through the dq / αβ transformation model, the coordinate transformation from the two-phase rotating dq coordinate system to the two-phase stationary αβ coordinate system can be realized, and the control quantity u in the two-phase stationary αβ coordinate system can be obtained. α and u β . Further, the matrix vector modulator can be combined with u α and u β Calculate the switch tube S in the primary matrix circuit ap , S bp , S cp , S an , S bn , S cn The target drive signal V GS_AP 、V GS_BP 、V GS_CP 、V GS_AN 、V GS_BN 、V GS_CN It should be emphasized that in the related art, when closed-loop control is performed on the output voltage and the input power factor is corrected, it is often necessary to sample the three-phase input current and put it into the current loop for control. However, this embodiment does not need to sample the three-phase input current, which saves the cost of the current sampling chip and peripheral circuits and further improves the power density.

[0134] This embodiment can change the power transmitted from the primary side to the secondary side by controlling the phase shift angle of the primary side and the secondary side, thereby realizing closed-loop control of the output voltage of the converter; based on the phase shift ratio, the modulation ratio when the converter reflux power is zero is calculated, and then based on the modulation ratio, corresponding drive signals are output to each bidirectional switch tube respectively to drive each bidirectional switch tube to be turned on or off at the appropriate time, so as to achieve the effect of suppressing the reflux power, reducing the effective value of the current, and improving the efficiency and life of the converter.

[0135] The fourth embodiment of the present application provides a method for suppressing the backflow power of a converter, the method comprising: after the matrix circuit is connected to the three-phase alternating current, based on the output voltage of the converter and the three-phase current sampling values, calculating the modulation ratio of the matrix circuit and performing closed-loop control on the output voltage of the converter; after completing the closed-loop control of the converter, calculating the phase shift ratio when the backflow power of the converter is zero in a single-phase shift mode based on the modulation ratio; outputting target drive signals corresponding to each switch tube based on the phase shift ratio; wherein each target drive signal is used to drive the conduction and shutdown of the corresponding switch tube, so that the backflow power of the converter is zero during the voltage output process.

[0136] Furthermore, in some implementations of the present embodiment, the above-mentioned step of calculating the first modulation parameter of the converter based on the output voltage of the converter after the matrix circuit is connected to the three-phase AC power includes: after the matrix circuit is connected to the three-phase AC power and the first modulation parameter of the converter is determined to be the modulation ratio, calculating the second error parameter between the output voltage and the preset output voltage reference value, and determining the current active component reference value of the matrix circuit based on the second error parameter; combining the three-phase current sampling values ​​and the current active component reference value, performing input power factor correction on the matrix circuit to obtain the corresponding modulation ratio.

[0137] Furthermore, in some implementations of the present embodiment, the above-mentioned steps of outputting multiple second target drive signals based on the second modulation parameters include: if the first modulation parameter is the modulation ratio, then the reactive control amount and the modulation ratio determined in the closed-loop control process are input into the second dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; and outputting multiple second target drive signals based on the vector modulation parameters.

[0138] Specifically, Fig.14 The figure shows a schematic diagram of a control model for realizing zero backflow power in a specific implementation method. In order to meet the closed-loop control of the output voltage and the power factor correction control of the input current, a mathematical model corresponding to the converter is constructed based on the PI double-loop control strategy to form a voltage outer loop and a current inner loop. The voltage outer loop is used to control the DC side voltage of the converter, and the current inner loop is used to control the current according to the parameters output by the voltage outer loop.

[0139] The voltage outer loop is composed of U o_ref , Uo And PI link composition. o_ref is the output voltage reference value, U o is the output voltage of the converter, and PI represents the voltage loop PI regulator. o_ref With output voltage U o The difference (i.e., the second error parameter) is sent to the voltage loop PI regulator; the output voltage U is controlled by the voltage loop PI regulator. o Real-time follow reference value U o_ref , to achieve the goal of closed-loop control of the output voltage, and use the output of the voltage loop PI regulator as the reference value i of the active current component in the two-phase rotating dq coordinate system dref .

[0140] The inner current loop is composed of i abc , abc / dq, i d 、i q 、u d_PI 、u q_PI , two PI links. abc represents the sampling value of the three-phase input current (that is, the above-mentioned three-phase current sampling value), the second abc / dq transformation model can realize the coordinate transformation from the three-phase stationary abc coordinate system to the two-phase rotating dq coordinate system, i d and i q i abc The active current and reactive current output after abc / dq coordinate transformation. The active component reference value i of the current in the two-phase rotation dq coordinate system dref With active current i d The difference is subtracted and sent to the active current PI regulator, which outputs the modulation ratio M. The input active current is controlled by the current loop PI regulator to follow the reference value i in real time. dref To achieve power factor correction, ensure that the input voltage and input current are in phase. Ideally, there is no reactive current. Therefore, the reactive current reference value can be set to 0. q Subtract the difference, and send it to the reactive current PI regulator, which controls the reactive current to 0. The active current PI regulator outputs the modulation ratio M, and the reactive current PI regulator outputs the reactive control quantity u q . M and u q The coordinate transformation from the two-phase rotating dq coordinate system to the two-phase stationary αβ coordinate system can be realized through the second dq / αβ transformation model, and the vector modulation parameter u in the two-phase stationary αβ coordinate system can be obtained. α and u β . will u α and u βInput to the matrix vector modulator, through which the bidirectional switch tube S in the primary matrix circuit can be calculated. ap , S bp , S cp , S an , S bn , S cn The target drive signal V GS_AP 、V GS_BP 、V GS_CP 、V GS_AN 、V GS_BN 、V GS_CN .

[0141] Further, in one implementation of this embodiment, the shift ratio is substituted into the fifth target calculation formula (that is, the specific expression of the fourth target calculation formula) to calculate the modulation ratio of the converter when the return power is zero; the fifth target calculation formula is expressed as:

[0142]

[0143] Among them, D φ1 Indicates the shift ratio, U o represents the output voltage, n represents the primary-to-secondary turns ratio of the isolation transformer, M represents the modulation ratio, U m Indicates the peak value of the three-phase AC phase voltage. φ1 By performing phase shift control on the converter, the reflux power of the converter can be made zero in the full voltage range and full load range.

[0144] Further, in some implementations of this embodiment, Fig.14 As shown, under the premise of completing the above voltage outer loop + current inner loop control, the modulation ratio M calculated by the active current PI regulator is used to substitute the modulation ratio M into the target calculation formula to calculate the shift ratio D φ1 The size of the phase shift controller can be obtained by shifting the phase ratio D φ1 Calculate the target drive signal V corresponding to each switch tube S1, S2, S3, S4 in the full-bridge circuit GS_1 、V GS_2 、V GS_3 、V GS_4 In the process of driving and controlling the corresponding switch tube through the target drive signal, V GS_1 、V GS_4 When the dead zone is ignored, the duty cycle is 50%. In terms of phase, the rising edge of the target drive signal differs from the rising edge of the first vector of the primary matrix circuit by D. φ1 T s ; V GS_2 、V GS_3 The duty cycle is 50% when the dead zone is ignored and VGS_1 、V GS_4 Complementary. By implementing the backflow power suppression method of this embodiment, the backflow power can be reduced to 0, the effective value of the current can be reduced by about 17%, and the conduction loss can be reduced by about 31% under the same conditions; at the same time, the peak current can be reduced by about 15.5%, and the turn-off loss can be reduced by 15.5%, and the efficiency and life of the converter can be significantly improved.

[0145] This embodiment can adjust the modulation ratio of the matrix circuit based on the sampling value of the three-phase input current and the actual output voltage, and perform closed-loop control on the output voltage of the converter, that is, the output voltage control is achieved by controlling the duty cycle of the switch tubes of the primary matrix circuit; the corresponding shift ratio is calculated based on the modulation ratio, and then the target drive signal corresponding to the full-bridge circuit is generated based on the shift ratio, thereby driving each switch tube to be turned on or off at the appropriate time, so as to achieve the effect of suppressing the backflow power, reducing the effective value of the current, and improving the efficiency and life of the converter.

[0146] Fig.15 A converter backflow power suppression device is provided in the fifth embodiment of the present application. The converter backflow power suppression device can be applied to the converter backflow power suppression method described above. The converter includes a matrix circuit, an inductor, an isolation transformer and a full-bridge circuit. The matrix circuit is connected to the primary side of the isolation transformer through the inductor, and the full-bridge circuit is connected to the secondary side of the isolation transformer. The matrix circuit is used to access three-phase alternating current. The matrix circuit and the full-bridge circuit are respectively provided with multiple switch tubes. Fig.15 As shown, the reflux power suppression device of the converter mainly includes:

[0147] The first calculation module 1501 is used to calculate the first modulation parameter of the converter based on the output voltage of the converter after the matrix circuit is connected to the three-phase alternating current, and output a plurality of first target drive signals based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter;

[0148] A second calculation module 1502 is used to calculate, after completing the closed-loop control of the converter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold based on the first modulation parameter; wherein the first modulation parameter and the second modulation parameter, one is a modulation ratio, and the other is a shift ratio;

[0149] A generation module 1503 is used to output multiple second target drive signals based on the second modulation parameter; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is a switch tube on the matrix circuit, and the other is a switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control the switch tubes on the full-bridge circuit to be turned on or off.

[0150] In some implementations of this embodiment, the first calculation module is specifically used to: after the matrix circuit is connected to three-phase alternating current and the first modulation parameter of the converter is determined to be a shift phase, calculate the first error parameter between the output voltage and a preset output voltage reference value; input the first error parameter to a preset voltage loop PI regulator to output the shift phase through the voltage loop PI regulator.

[0151] In some other implementations of this embodiment, the first calculation module is specifically used to: after the matrix circuit is connected to three-phase alternating current and the first modulation parameter of the converter is determined to be the modulation ratio, calculate the second error parameter between the output voltage and the preset output voltage reference value, and determine the current active component reference value of the matrix circuit based on the second error parameter; combine the three-phase current sampling values ​​and the current active component reference value to perform input power factor correction on the matrix circuit to obtain the corresponding modulation ratio.

[0152] Further, in some implementations of this embodiment, the phase shift ratio includes an outer phase shift ratio and an inner phase shift ratio; accordingly, the second calculation module is specifically used to: substitute the first modulation parameter into the first target calculation formula, and calculate the second modulation parameter when the reflux power of the converter in the dual phase shift mode is less than or equal to the first preset threshold; wherein the first target calculation formula is expressed as:

[0153]

[0154] Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, and K5 are preset constant values, d1 represents the outward shift phase ratio, and D2 represents the inward shift phase ratio.

[0155] Further, in some implementations of this embodiment, the second calculation module is further specifically used to: substitute the first modulation parameter into the second target calculation formula to calculate the second modulation parameter when the reflux power of the converter is zero in the dual phase shift mode; wherein the second target calculation formula is expressed as:

[0156] Um M+K1D1U o +K2D2U o +K3U o =0.

[0157] In some other implementations of this embodiment, the second calculation module is specifically used to: substitute the first modulation parameter into the third target calculation formula to calculate the second modulation parameter when the reflux power of the converter in the single phase shift mode is less than or equal to the second preset threshold; wherein the third target calculation formula is expressed as:

[0158]

[0159] Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, and K5 are preset constant values, and D1 represents the shift ratio.

[0160] Further, in some implementations of this embodiment, the second calculation module is further specifically used to: substitute the first modulation parameter into the fourth target calculation formula to calculate the second modulation parameter when the reflux power of the converter is zero in the single phase shift mode; wherein the fourth target calculation formula is expressed as:

[0161] U m M+(K1+K2)D1U o +(K2+K3)U o =0.

[0162] In some implementations of this embodiment, a derivation module is also included, which is used to: obtain an expression for the zero-crossing moment of the inductor current of the converter; derive an expression for the reflux power within the fundamental period of the converter based on the expression for the zero-crossing moment of the inductor current; and derive a target calculation formula based on the reflux power expression.

[0163] Furthermore, in some implementations of the present embodiment, when the derivation module executes the function of obtaining the expression of the zero-crossing moment of the inductor current of the converter, it is specifically used to: generate a space vector diagram of the converter based on the current vectors corresponding to different working modes of the matrix circuit and the voltage values ​​of each phase in the three-phase alternating current; wherein the space vector diagram includes multiple sectors, each sector in the time domain corresponds to multiple switching cycles, and each switching cycle corresponds to multiple working modes; based on the symmetrical distribution rule of the vector current in the sector of the space vector diagram and the expression of the inductor current under each working mode, derive the expression of the zero-crossing moment of the inductor current of the converter.

[0164] In some implementations of this embodiment, the output module is specifically used for: if the first modulation parameter is a shift ratio, then the second modulation parameter is determined as the active control quantity, and the active control quantity and the preset reactive control quantity are input into the first dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; based on the vector modulation parameters, multiple second target drive signals are output respectively.

[0165] In some other implementations of this embodiment, the output module is specifically used for: if the first modulation parameter is the modulation ratio, then the reactive control amount and the modulation ratio determined in the closed-loop control process are input into the second dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; and multiple second target drive signals are output based on the vector modulation parameters.

[0166] Based on the technical solution of the embodiment of the present application, after the matrix circuit is connected to the three-phase alternating current, the first modulation parameter of the converter is calculated based on the output voltage of the converter, and multiple first target drive signals are output based on the first modulation parameter; wherein each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to realize the closed-loop control of the output voltage of the converter; after completing the closed-loop control of the converter, the second modulation parameter of the converter is calculated based on the first modulation parameter when the reflux power is less than or equal to the preset threshold; wherein the first modulation parameter and the second modulation parameter, one is the modulation ratio, and the other is the shift ratio; multiple second target drive signals are output respectively based on the second modulation parameter; wherein each second target drive signal is used to control the corresponding second target switch tube to be turned on or off, so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit, and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control each switch tube on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control each switch tube on the full-bridge circuit to be turned on or off. In the present application scheme, one of the phase shift ratio or the modulation ratio is adjusted first to achieve closed-loop control of the output voltage; then the other modulation parameter in the phase shift ratio or the modulation ratio is adjusted to drive the corresponding switching tubes to turn on or off at the appropriate time, so as to achieve the effect of suppressing backflow power, reducing the effective value of current, and improving the efficiency and life of the converter.

[0167] The sixth embodiment of the present application also provides a backflow power suppression system. The backflow power suppression system can be used to implement the backflow power suppression method of the converter in the aforementioned embodiment, and mainly includes: a converter and a controller electrically connected to the converter; the controller can be configured with a memory, a controller, and a computer program stored in the memory and executable on the controller, and the memory and the controller are connected by communication. When the controller executes the computer program, the method in the aforementioned embodiment 2 is implemented. Among them, the number of controllers can be one or more.

[0168] The memory may be a high-speed random access memory (RAM) memory or a non-volatile memory, such as a disk memory. The memory is used to store executable program codes, and the controller is coupled to the memory.

[0169] Furthermore, an embodiment of the present application also provides a computer-readable storage medium, which may be arranged in the above-mentioned backflow power suppression system, and the computer-readable storage medium may be the memory in the above-mentioned embodiment.

[0170] The computer readable storage medium stores a computer program, and when the program is executed by the controller, the method for suppressing the backflow power of the converter in the above-mentioned embodiment is implemented. Furthermore, the computer storable medium can also be a U disk, a mobile hard disk, a read-only memory (ROM), a RAM, a magnetic disk or an optical disk, etc., which can store program codes.

[0171] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0172] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0173] In addition, each functional module in each embodiment of the present application can be integrated into a processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The above integrated modules can be implemented in the form of hardware or software functional modules.

[0174] If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a readable storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned readable storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0175] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0176] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0177] The above is a description of the reflux power suppression method, device, system and readable storage medium of the converter provided in the present application. For technicians in this field, according to the ideas of the embodiments of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for suppressing reflux power of a converter, characterized in that: The converter includes a matrix circuit, an inductor, an isolation transformer and a full-bridge circuit, wherein the matrix circuit is connected to the primary side of the isolation transformer through the inductor, the full-bridge circuit is connected to the secondary side of the isolation transformer, and the matrix circuit is used to connect three-phase alternating current; The matrix circuit and the full-bridge circuit are respectively provided with a plurality of switch tubes; The backflow power suppression method comprises: After the matrix circuit is connected to the three-phase alternating current, a first modulation parameter of the converter is calculated based on the output voltage of the converter, and a plurality of first target drive signals are output based on the first modulation parameter; wherein each of the first target drive signals is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter; After the closed-loop control of the converter is completed, a second modulation parameter of the converter is calculated based on the first modulation parameter when the reflux power is less than or equal to a preset threshold; wherein one of the first modulation parameter and the second modulation parameter is a modulation ratio and the other is a shift ratio; Based on the second modulation parameter, multiple second target drive signals are output respectively; wherein each of the second target drive signals is used to control the corresponding second target switch tube to be turned on or off so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit, and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control each of the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control each of the switch tubes on the full-bridge circuit to be turned on or off.

2. The method for suppressing the backflow power of the converter according to claim 1, characterized in that: After the matrix circuit is connected to the three-phase alternating current, calculating the first modulation parameter of the converter based on the output voltage of the converter includes: After the matrix circuit is connected to the three-phase alternating current and the first modulation parameter of the converter is determined to be the phase shift ratio, a first error parameter between the output voltage and a preset output voltage reference value is calculated; the first error parameter is input to a preset voltage loop PI regulator to output the phase shift ratio through the voltage loop PI regulator; Alternatively, after the matrix circuit is connected to three-phase alternating current and the first modulation parameter of the converter is determined to be the modulation ratio, a second error parameter between the output voltage and a preset output voltage reference value is calculated, and a current active component reference value of the matrix circuit is determined based on the second error parameter; and input power factor correction is performed on the matrix circuit in combination with the three-phase current sampling values ​​and the current active component reference value to obtain the corresponding modulation ratio.

3. The method for suppressing the backflow power of a converter according to claim 1, characterized in that: The shift ratio includes an outward shift ratio and an inward shift ratio; The calculating, based on the first modulation parameter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold value comprises: Substitute the first modulation parameter into the first target calculation formula to calculate the second modulation parameter when the reflux power of the converter in the dual phase shift mode is less than or equal to the first preset threshold; wherein the first target calculation formula is expressed as: Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, and K5 are respectively preset constant values, D1 represents the outward shift phase ratio, and D2 represents the inward shift phase ratio.

4. The method for suppressing the backflow power of a converter according to claim 3, characterized in that: The calculating, based on the first modulation parameter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold value also includes: Substitute the first modulation parameter into the second target calculation formula to calculate the second modulation parameter of the converter when the reflux power is zero in the dual phase shift mode; wherein the second target calculation formula is expressed as: U m M+K1D1U o +K2D2U o +K3U o =0.

5. The method for suppressing the backflow power of a converter according to claim 1, characterized in that: The calculating, based on the first modulation parameter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold value comprises: Substitute the first modulation parameter into the third target calculation formula to calculate the second modulation parameter when the reflux power of the converter in the single-phase shift mode is less than or equal to the second preset threshold; wherein the third target calculation formula is expressed as: Among them, U m Indicates the peak value of the three-phase AC phase voltage, U o represents the output voltage, M represents the modulation ratio, P o represents the output power of the converter, K1, K2, K3, K4, K5 are respectively preset constant values, and D1 represents the shift ratio.

6. The method for suppressing the backflow power of the converter according to claim 5, characterized in that: The calculating, based on the first modulation parameter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold value also includes: Substituting the first modulation parameter into the fourth target calculation formula, the second modulation parameter of the converter when the reflux power is zero in the single-phase shift mode is calculated; wherein the fourth target calculation formula is expressed as: U m M+(K1+K2)D1U o +(K2+K3)U o =0。 7. The method for suppressing the backflow power of a converter according to any one of claims 1 to 6, characterized in that: The outputting a plurality of second target driving signals respectively based on the second modulation parameter comprises: If the first modulation parameter is the shift ratio, the second modulation parameter is determined as the active control amount, and the active control amount and the preset reactive control amount are input into the first dq / αβ transformation model to calculate the vector modulation parameter of the matrix circuit; and a plurality of second target drive signals are outputted respectively based on the vector modulation parameter; Alternatively, if the first modulation parameter is the modulation ratio, the reactive control amount and the modulation ratio determined in the closed-loop control process are input into the second dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; and multiple second target drive signals are output respectively based on the vector modulation parameters.

8. A converter backflow power suppression device, characterized in that: The converter includes a matrix circuit, an inductor, an isolation transformer and a full-bridge circuit, wherein the matrix circuit is connected to the primary side of the isolation transformer through the inductor, the full-bridge circuit is connected to the secondary side of the isolation transformer, and the matrix circuit is used to connect three-phase alternating current; The matrix circuit and the full-bridge circuit are respectively provided with a plurality of switch tubes; The backflow power suppression device comprises: a first calculation module, configured to calculate a first modulation parameter of the converter based on the output voltage of the converter after the matrix circuit is connected to the three-phase alternating current, and output a plurality of first target drive signals based on the first modulation parameter; wherein each of the first target drive signals is used to control the corresponding first target switch tube to be turned on or off, so as to realize closed-loop control of the output voltage of the converter; A second calculation module is used for calculating, after completing the closed-loop control of the converter, a second modulation parameter of the converter when the reflux power is less than or equal to a preset threshold based on the first modulation parameter; wherein, one of the first modulation parameter and the second modulation parameter is a modulation ratio and the other is a shift ratio; An output module is used to output multiple second target drive signals based on the second modulation parameter; wherein each of the second target drive signals is used to control the corresponding second target switch tube to be turned on or off so as to achieve the reflux power suppression effect required by the converter; the first target switch tube and the second target switch tube, one is the switch tube on the matrix circuit, and the other is the switch tube on the full-bridge circuit; the drive signal corresponding to the modulation ratio is used to control each of the switch tubes on the matrix circuit to be turned on or off, and the drive signal corresponding to the shift ratio is used to control each of the switch tubes on the full-bridge circuit to be turned on or off.

9. A backflow power suppression system, characterized in that: The invention comprises a converter and a controller electrically connected to the converter, wherein: The converter includes a matrix circuit, an isolation transformer and a full-bridge circuit. The matrix circuit is connected to the primary side of the isolation transformer through an inductor, and the full-bridge circuit is connected to the secondary side of the isolation transformer. The matrix circuit is used to access three-phase alternating current. The matrix circuit and the full-bridge circuit are respectively provided with a plurality of switch tubes. The controller is used to execute the steps in the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a controller, the steps in the method according to any one of claims 1 to 7 are implemented.

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