Soft switching control method, device and system of converter and readable storage medium

Abstract

The invention provides a soft switching control 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, and generating a plurality of first target driving signals based on the first modulation parameter, so as to control the connection or disconnection of a corresponding first target switching tube through each first target driving signal, the closed-loop control of the output voltage and the input current of the converter is realized; calculating a second modulation parameter of the converter after closed-loop control 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 one is a phase shift ratio; generating a plurality of second target driving signals based on the second modulation parameter; wherein the driving signal corresponding to the modulation ratio is used for controlling each switching tube of the matrix circuit to be switched on or switched off, and the driving signal corresponding to the phase shift ratio is used for controlling each switching tube of the full-bridge circuit to be switched on or switched off. By implementing the scheme of the invention, soft switching of all switching tubes within a full voltage range and a full load range can be realized.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a soft switching control method, device, system and readable storage medium 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] In a single-stage isolated AC / DC converter, the output voltage can be controlled by adjusting the modulation ratio of the matrix circuit and the primary-secondary phase shift angle. However, the related technology usually adopts a method of controlling the output voltage by adjusting the primary-secondary phase shift angle with a fixed modulation ratio or by adjusting the modulation ratio with a fixed primary-secondary phase shift angle, which easily causes switching losses to the switch tube of the converter, makes it difficult to achieve soft switching control, and is prone to generate electromagnetic interference (EMI). Summary of the invention

[0004] The embodiments of the present application provide a soft switching control method, device, system and readable storage medium for a converter, which can at least solve the problem in the related art that soft switching control of the converter is difficult to implement and prone to electromagnetic interference.

[0005] In a first aspect, an embodiment of the present application provides a soft switch control method 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 soft switch control method includes:

[0006] 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 generated 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 and input current of the converter;

[0007] Based on the first modulation parameter, calculating a second modulation parameter of the converter after closed-loop control; wherein the first modulation parameter and the second modulation parameter, one is a modulation ratio and the other is a shift ratio;

[0008] A plurality of second target drive signals are generated 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 realize the soft switching of 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.

[0009] In a second aspect, an embodiment of the present application provides a soft switch control 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 soft switch control device includes:

[0010] 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 generate 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 and input current of the converter;

[0011] A second calculation module is used to calculate a second modulation parameter of the converter after closed-loop control 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;

[0012] A generating module is used to generate multiple second target driving signals based on a second modulation parameter; wherein each second target driving signal is used to control the corresponding second target switch tube to be turned on or off so as to realize soft switching of the converter; the first target switch tube and the second target switch tube, one is a switch tube on a matrix circuit, and the other is a switch tube on a full-bridge circuit; the driving signal corresponding to the modulation ratio is used to control the switching on or off of each switch tube on the matrix circuit, and the driving signal corresponding to the shift ratio is used to control the switching on or off of each switch tube on the full-bridge circuit.

[0013] The third aspect of the embodiment of the present application provides a soft switching control system, including: a converter and a controller, the converter and the controller are electrically connected, wherein 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 access three-phase alternating current; the matrix circuit is provided with multiple switching tubes; the controller is used to implement each step in the soft switching control method of the converter provided in the first aspect of the embodiment of the present application.

[0014] 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 in the soft switching control method of the converter provided in the first aspect of the embodiments of the present application are implemented.

[0015] As can be seen from the above, according to the soft switching control method, device, system and readable storage medium of the converter provided by the scheme of the present application, after the matrix circuit is connected to the three-phase AC power, the first modulation parameter of the converter is calculated based on the output voltage of the converter, and multiple first target drive signals are generated 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 and input current of the converter; based on the first modulation parameter, the second modulation parameter of the converter after closed-loop control is calculated; wherein, the first 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, multiple second target drive signals are generated; 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 realize the soft switching of 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. Through the implementation of the scheme of the present application, one modulation parameter in the phase shift ratio or the modulation ratio is adjusted first to achieve closed-loop control of the output voltage and the input current; then the other modulation parameter in the phase shift ratio or the modulation ratio is adjusted to drive the corresponding switch tubes to be turned on or off at the appropriate time, thereby achieving soft switching of all switch tubes within the full voltage range and the full load range, which can improve the working efficiency of the converter and achieve the effect of reducing switching losses and improving EMI. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a converter provided in the first embodiment of the present application;

[0017] Figure 2 A basic flow chart of a soft switching control method for a converter provided in the second embodiment of the present application;

[0018] Figure 3 A 6-sector space vector distribution diagram provided in the second embodiment of the present application;

[0019] Figure 4 A schematic diagram of the effects 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;

[0020] Figure 5 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;

[0021] Figure 6 Schematic diagram of polarity requirements of inductor current when soft switching is achieved in dual phase shift mode in the second embodiment of the present application;

[0022] Figure 7 Schematic diagram of polarity requirements of inductor current when soft switching is achieved in single phase shift mode in the second embodiment of the present application;

[0023] Figure 8 This is a control block diagram for realizing soft switching when closed-loop control of output voltage is performed by adjusting the modulation ratio in the second embodiment of the present application;

[0024] Fig. 9 This is a control block diagram for realizing soft switching when closed-loop control of the output voltage is performed by adjusting the shift phase in the second embodiment of the present application;

[0025] Fig.10 A waveform diagram of an inductor current change provided in the second embodiment of the present application;

[0026] Fig.11 A 12-sector space vector distribution diagram provided in the second embodiment of the present application;

[0027] Fig.12 A curve diagram showing a second modulation parameter changing with a phase shift angle provided in the second embodiment of the present application;

[0028] Fig.13 A schematic diagram of a current limiting condition for realizing soft switching provided in the second embodiment of the present application;

[0029] Fig.14 A schematic diagram of a switching state of a converter at time t0 provided in the second embodiment of the present application;

[0030] Fig.15 A curve diagram of another second modulation parameter versus phase shift angle provided in the second embodiment of the present application;

[0031] Fig.16 A control block diagram of a soft switch implementation provided in the third embodiment of the present application;

[0032] Fig.17 A waveform diagram of an inductor current change provided in the third embodiment of the present application;

[0033] Fig.18 A control block diagram of a soft switch implementation provided in the fourth embodiment of the present application;

[0034] Fig.19 A waveform diagram of an inductor current change provided in the fourth embodiment of the present application;

[0035] Fig. 20 A schematic diagram of a program module of a soft switching control device for a converter provided in the fifth embodiment of the present application. DETAILED DESCRIPTION

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] In order to solve the problem in the related art that soft switching control of the converter is difficult to implement and prone to electromagnetic interference, the first embodiment of the present application provides a soft switching control system, including a converter and a controller, the converter is electrically connected to the controller, and the controller is used to implement a soft switching control method of the converter.

[0041] Specifically, the converter in this embodiment can be a matrix-dual active bridge AC / DC converter, and the matrix-dual active bridge AC / DC 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 the three-phase AC power. The matrix-dual active bridge AC / DC converter in this embodiment has a simplified circuit structure and a low-impedance current path. The primary side matrix circuit can efficiently convert the three-phase AC input voltage into a high-frequency AC rectangular wave, and cooperate with the secondary side 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 stabilization and input power factor correction (PFC).

[0042] 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.

[0043] Further, in some implementations of this embodiment, Figure 2 As shown, 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.

[0044] 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 to 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.

[0045] 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 L c With switch tube S bp Connection: switch tube S ap Connected to one end of the primary side of the isolation transformer; switch tube S an Connected to the other end of the primary side of the isolation transformer; switch tube S bp Connected to one end of the primary side of the isolation transformer, the switch tube S bn Connected to the other end of the primary side of the isolation transformer; switch tube Scp Connected to one end of the primary side of the isolation transformer, the switch tube S cn Connect to the other end of the primary side of the isolation transformer.

[0046] The second embodiment of the present application provides a soft switching control method of a converter, which is used to implement the soft switching control of the converter in the first embodiment. Figure 2 The basic flow chart of the soft switching control method of the converter provided in this embodiment is as follows:

[0047] Step 201: 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 generated based on the first modulation parameter.

[0048] Specifically, the above-mentioned output voltage refers to the DC side output voltage of the full-bridge circuit; each first target drive signal is used to control the corresponding first target switch tube to be turned on or off, so as to achieve closed-loop control of the output voltage and input current 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 first modulation parameter can be controlled by a preset loop control strategy to achieve the goal of closed-loop control of the output voltage and input current. The preset loop control strategy can be PI dual-loop control, dual-loop decoupling + feedforward control, PR dual-loop control, direct power control and other control strategies, which are not limited here.

[0049] 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.

[0050] 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.

[0051] Step 202: Calculate a second modulation parameter of the converter after closed-loop control based on the first modulation parameter.

[0052] Specifically, the first modulation parameter and the second modulation parameter are modulation ratio and phase shift angle, respectively. This embodiment can fully utilize two control degrees of freedom (modulation ratio and phase shift angle), and can realize soft switching of each switch tube within the full voltage range and full load range by adaptively adjusting the two.

[0053] Step 203: Generate a plurality of second target driving signals based on the second modulation parameters.

[0054] Specifically, each second target driving signal is used to control the corresponding second target switch tube to turn on or off, so as to realize the soft switching of 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. Through the implementation of this embodiment, 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 it switches in a zero current or zero voltage state, which can significantly reduce the loss of each switch tube in the converter during the switching process and improve the overall working efficiency of the converter.

[0055] In some implementations 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 matrix circuit in the converter after closed-loop control based on the first modulation parameter includes: substituting the first modulation parameter into a target calculation formula to calculate the second modulation parameter of the matrix circuit; wherein the target calculation formula includes a dual phase shift mode calculation formula and a single phase shift mode calculation formula; the dual phase shift mode calculation formula is expressed as:

[0056] U m M+K1D1U o +K2D2U o +K3U o =K4

[0057] The calculation formula of single phase shift mode is expressed as:

[0058] U m M+(K1+K2)D1U o +(K2+K3)U o =K4

[0059] D1 represents the outward shift ratio, D2 represents the inward shift ratio, K1, K2, K3, K4 are preset constant values, U o represents the output voltage, M represents the modulation ratio, U m Indicates the peak value of the three-phase AC phase voltage.

[0060] Specifically, this embodiment provides a coordinated control scheme of the modulation ratio M and the primary-secondary shift ratio (outward shift ratio D1 and inward shift ratio D2) to achieve soft switching of all switches in the matrix-dual active bridge converter, thereby improving the efficiency and life of the converter. The primary matrix circuit 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. The effective vectors are distributed as follows: Figure 3 The modulation ratio of the matrix circuit is defined as the reference vector modulus |I ref | and the effective vector modulus |I AC |Ratio Times, symbolized by M, then:

[0061]

[0062] like Figure 4 As shown, when the converter works in double phase shift, there are two phase shift ratios, D1 and D2. Define the outer phase shift ratio D1 = φ1 / π, the inner phase shift ratio D2 = φ2 / π, where φ1 is the secondary bridge arm voltage v S The rising edge and matrix circuit output voltage v PN The phase shift angle of the rising edge; 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.

[0063] like Figure 5 As shown, when D2=1+D1, the converter is simplified from the double-phase shift mode to the single-phase shift mode. The hard switching of the switch tube will increase the loss and heat of the converter and generate greater electromagnetic interference.

[0064] The realization of soft switching at different times has different requirements on the polarity of the inductor current. In some implementations of this embodiment, for example Figure 6 As shown, when the reference vector I ref When the angle with the α axis in the effective vector distribution diagram is in the interval [-π / 6, 0], due to the symmetry of the three-phase AC, for t1, t2, t3, t4, t6, t7, t8, and t9, the inductor current easily meets the soft switching condition and will not lose ZVS (zero voltage switching). For the switch tube turned on at time t0 and the switch tube turned on at time t5, whether ZVS can be achieved depends on the initial value of the inductor current i L When the phase shift ratio and modulation ratio satisfy the double phase shift mode calculation formula, i L The polarity of (t0) is negative, which can realize the soft switching of all switches of the matrix-dual active bridge converter. In some implementations of this embodiment, when D2=1+D1, the converter is simplified from the double-phase shift mode to the single-phase shift mode. ref When the angle between the inductor current and the α axis in the effective vector distribution diagram is in the interval [-π / 6, 0], the polarity of the inductor current satisfies Figure 7 When the relationship between the modulation ratio and the phase shift ratio satisfies the above single phase shift mode calculation formula, the reflux power in the switching cycle can be suppressed to the rated power P o K times of that and achieve soft switching.

[0065] In some implementations of this embodiment, the initial value of the inductor current can be constrained within a range of -40A to -0.1A. The constant values ​​K1 and K2 can be constrained in the manner shown in Table 1. S , K3, K4, the modulation ratio and shift ratio can be constrained in the manner shown in Table 2. By optimizing the above parameter values, soft switching of all switch tubes can be achieved without causing high reflux power.

[0066] Table 1:

[0067] parameter Value range <![CDATA[K1]]> [0,20] <![CDATA[K2]]> [-20,20] <![CDATA[K3]]> [-40,0] <![CDATA[K4]]> [0,100]

[0068] Table 2:

[0069] parameter Value range <![CDATA[Phase shift ratio D1]]> [0,0.8] <![CDATA[Phase shift ratio D2]]> [0,1.8] Modulation ratio M [0,1]

[0070] In some implementations of this embodiment, Figure 8 As shown, the output voltage can be controlled in a closed loop by controlling the modulation ratio, and then the corresponding shift ratio is calculated according to the above target calculation formula. Specifically, 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 control amount uq , 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 S 12 The phase shift ratio D1 and D2 are calculated according to the above target calculation formula, and change linearly with the modulation ratio M. The phase shift controller generates the drive signal V of the thirteenth to sixteenth switch tubes based on the phase shift ratio 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 on and off of the circuit can achieve the effect of soft switching.

[0071] In some other implementations of this embodiment, Fig. 9 As shown, the output voltage can be controlled by controlling the phase shift ratio to perform closed-loop control, and then the corresponding modulation ratio is calculated according to the above target calculation formula. Specifically, the sampled output voltage is sent to the closed-loop controller, the output voltage is transformed and controlled, the phase shift ratios D1 and D2 are calculated, and 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 conduction and shutdown of the thirteenth to sixteenth switch tubes of the full-bridge circuit. At the same time, the modulation ratio M is obtained by the above target calculation formula, and changes with the shift ratios D1 and D2. The modulation ratio M and the reactive power control amount 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 modulation ratio M and the shift ratio D1 and D2 satisfy the relationship defined by the above target calculation formula, which can achieve the control effect of soft switching.

[0072] Using the above Figure 8 When the converter is operated in the manner shown in 9, for any given set of parameters (L = 10uH, n = 1, U o =500V, f s=70kHz, K1=0.667, K2=0.667, K3=-1.333K4=18.667) under the inductor current waveform (such as Fig.10 As shown in the figure, it can be seen that under different loads, the initial value of the inductor current can always be accurately controlled at the desired -10A, helping to achieve soft switching of all switches in the full range and improve the efficiency of the converter.

[0073] In one implementation of the present embodiment, before the above-mentioned step of calculating the second modulation parameter of the matrix circuit in the converter after closed-loop control based on the first modulation parameter, it also includes: generating 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 corresponds to multiple switching cycles in the time domain, 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, combined with the vector action duty cycle of the target sector in the space vector diagram and the voltage values ​​of each phase in the three-phase alternating current, the target calculation formula is derived.

[0074] 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.

[0075] Table 1:

[0076]

[0077]

[0078] 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 in each small sector and the corresponding vector action duty ratio 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;

[0079] Table 2:

[0080]

[0081] 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 the control expression for soft switching, which is the above target calculation formula.

[0082] 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:

[0083] Define the shift ratio: D φ1 =φ1 / π, where φ1 represents the original-secondary side phase shift angle.

[0084] 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 , secondary side S 14 and S 15 The voltage refracted to the primary side is -nU o , where n represents the primary-to-secondary turns ratio of the transformer, that is, the ratio of the primary turns to the secondary turns, U o Represents the output voltage of the converter. The voltage across the inductor L is u AB +nU o , the inductor current rises linearly. At the moment when the inductor current passes through zero (t zc Before the moment t, the energy in the inductor is transferred to the primary power supply and the secondary load. 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:

[0085]

[0086] The inductor current value at the end of the mode is:

[0087]

[0088] Second working mode: primary side S ap and S bn conduction, the output voltage of the matrix circuit is the line voltage u AB , secondary side S 13 and S 16 The voltage refracted 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 across the two ends. At this stage, the primary power supply transfers energy to the secondary load. The inductor current expression at this stage is:

[0089]

[0090] The inductor current value at the end of the mode is:

[0091]

[0092] The third working mode: primary side S ap and S cn conduction, the output voltage of the matrix circuit is the line voltage u AC , secondary side S 13 and S 16 The voltage refracted 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 across the two ends. At this stage, the primary power supply transfers energy to the secondary load. The inductor current expression at this stage is:

[0093]

[0094] The inductor current value at the end of the mode is:

[0095]

[0096] The fourth working mode: primary side S ap and S an The output voltage of the matrix circuit is 0, and the secondary side S 13 and S 16 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:

[0097]

[0098] The inductor current value at the end of the mode is:

[0099]

[0100] The operating mode in the second half of the switching cycle is symmetrical to that in the first half of the switching cycle and will not be described in detail here.

[0101] From the current symmetry of a single switching cycle, we know that i L (t4) = -i L (t0), that is:

[0102]

[0103] Simplified, the initial value of the inductor current i in the first sector is L (t0) is expressed as:

[0104]

[0105] The three-phase input line voltage U ab and U ac The expression is:

[0106]

[0107]

[0108] Where w is the angular frequency of the AC input voltage and pi is the circumference of a circle.

[0109] D in Table 2 R =M*sin(π / 6-ωt) and D L =M*sin(π / 6+ωt) and substitute into D ab and D ac In the above, combined with the three-phase input line voltage U ab and U ac The expression of the initial value of the inductor current can be further simplified as follows:

[0110]

[0111] Based on this, the corresponding relationship between the modulation ratio M and the phase shift angle φ1 in the single phase shift mode can be obtained as follows (i.e., the expanded form of the above single phase shift mode calculation formula):

[0112]

[0113] Among them, f s represents the switching frequency, f s =1 / T s .

[0114] Therefore, in order to achieve a fixed negative current control in each switching cycle while controlling the output voltage through the modulation ratio M, an initial inductor current value i can be set. L (t0), substituting into the above formula, the phase shift angle φ1 changes linearly with the modulation ratio M, achieving the effect of accurately controlling the initial value of the current. The change curve of the phase shift angle and the modulation ratio can be drawn, as shown in Fig.12 As shown, it can be seen that the fixed current initial value i L At (t0), there is a linear relationship between the phase shift angle φ1 and the modulation ratio M.

[0115] By reasonably limiting the current polarity and current amplitude of each switch tube, all switches can achieve soft switching in the full voltage range (for example, 300V to 1000V) and full load range (for example, 0 to 40kW); the limiting conditions can be as follows: Fig.13 Set up as shown in Table 3:

[0116] Table 3:

[0117]

[0118]

[0119] It should be understood that in the solutions of the related art, since only the power output requirement is considered, there is no constraint on the inductor current waveform, which causes some switches in the matrix circuit to lose the ZVS (zero voltage switching) condition, resulting in large conduction losses, especially when the input and output voltages do not match, the loss of ZVS is even worse. This will bring additional switching losses to the hard switching of the switch tube, reduce the conversion efficiency of the converter, and also bring greater noise, which has an adverse effect on the EMI level of the whole machine.

[0120] Furthermore, in one implementation of this embodiment, the initial value of the inductor current and the output voltage of the matrix circuit satisfy the following relationship:

[0121]

[0122] Among them, u represents the voltage value output by the matrix circuit at the corresponding moment, t dead Indicates the dead time, c 0_mosfet Represents the equivalent capacitance of the target switch tube.

[0123] Specifically, the initial value of the inductor current has a significant impact on the realization of soft switching, such as Fig.14 As shown in the figure, the t0 moment of the first sector is taken as an example to illustrate the inductor current condition for the switch tube to achieve ZVS opening. At t0 moment, the previous cycle ends, S an Shutdown, S bn Not yet turned on, at this time S bn The voltage is positive at the bottom and negative at the top. If you want to achieve ZVS, you need the inductor current i L During the dead time t dead Internal S cn The charge on S is discharged and at the same time an Charge to u AB ; Required inductor current i L The polarity is negative, and the absolute value of the inductor current must satisfy:

[0124]

[0125] Initial value of negative inductor current i L (t0) If the polarity is set to negative and the absolute value is too large, the reflux power will increase, which will have a negative impact on efficiency. In order to achieve soft switching of all switches without causing additional reflux power, in some specific implementations, the initial value of the inductor current can be set to:

[0126]

[0127] Substituting the initial value of the inductor current into the corresponding relationship between the modulation ratio M and the phase shift angle φ1 in the single phase shift mode, the more specific corresponding relationship between the phase shift angle φ1 and the modulation ratio M, equation 2, can be derived:

[0128]

[0129] Based on this, for any given set of parameters (L = 15uH, n = 1, U o =500V, f s =70kHz L (t0) = -10A), the curve of modulation ratio M changing with phase shift angle φ1 can be obtained as follows: Fig.15 As shown. By using phase shift control to achieve closed-loop control of the converter output voltage, the output voltage can be stabilized. The modulation ratio M is obtained from the above formula, so that the modulation ratio M can be adjusted with the phase shift ratio D. φ1 Linear changes to achieve soft switching control effect.

[0130] It can be seen that through the implementation of this embodiment, 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 generated 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 and input current of the converter; based on the first modulation parameter, the second modulation parameter of the converter after closed-loop control is calculated; 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 generated 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 realize the soft switching of 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. Through the implementation of the scheme of the present application, one modulation parameter in the phase shift ratio or the modulation ratio is adjusted first to achieve closed-loop control of the output voltage and the input current; then the other modulation parameter in the phase shift ratio or the modulation ratio is adjusted to drive the corresponding switch tubes to be turned on or off at the appropriate time, thereby achieving soft switching of all switch tubes within the full voltage range and the full load range, which can improve the working efficiency of the converter and achieve the effect of reducing switching losses and improving EMI.

[0131] The third embodiment of the present application provides a specific control method for soft switching of a converter, which uses the shift ratio as the first modulation parameter and the modulation ratio as the second modulation parameter to control the converter to achieve soft switching of each switch tube within the full voltage range; specifically, the following implementation methods are included:

[0132] In one implementation of the present embodiment, after the matrix circuit is connected to the three-phase AC power, the step of 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 AC power and the first modulation parameter of the converter is determined to be a shift phase, calculating the first error parameter between the output voltage of the converter and a preset output voltage reference value; inputting the first error parameter to a preset voltage loop PI regulator to output the shift phase through the voltage loop PI regulator.

[0133] Specifically, after the matrix circuit is connected to three-phase alternating current, a first error parameter between the output voltage and a preset output voltage reference value is calculated; the first error parameter is input into a preset voltage loop PI regulator to output a shift phase ratio of the converter through the voltage loop PI regulator; based on the shift phase ratio, the output voltage of the converter is closed-loop controlled.

[0134] Furthermore, in one implementation of the present embodiment, the above-mentioned step of performing closed-loop control on the output voltage of the converter based on the phase shift ratio includes: determining the target transmission energy from the primary side to the secondary side in the converter based on the phase shift ratio; generating a phase shift control signal of the converter based on the target transmission energy; wherein the phase shift control signal is used to regulate the phase difference between the primary side and the secondary side to achieve closed-loop control of the output voltage of the converter.

[0135] Specifically, Fig.16 The figure shows a control block diagram of a soft switch in a specific implementation method. To meet the closed-loop control of the output voltage, a mathematical model corresponding to the converter can be 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.

[0136] 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.

[0137] In one implementation of this embodiment, the step of calculating the modulation ratio of the matrix circuit in the converter after closed-loop control based on the phase shift ratio includes: substituting the phase shift ratio into the single phase shift mode calculation formula to calculate the modulation ratio of the matrix circuit; wherein the single phase shift mode calculation formula is expressed as:

[0138]

[0139] Among them, D φ1 Indicates the shift ratio, i L (t0) represents the initial value of the inductor current of the sector to which the converter currently operates, L represents the inductance value, and f s Indicates the switching frequency, 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.

[0140] Furthermore, in some specific implementations, the modulation ratio required for the soft switching control may be calculated using the following specific single phase shift mode calculation formula. The specific single phase shift mode calculation formula is expressed as:

[0141]

[0142] Among them, t dead Indicates the dead time, C 0mosfet Represents the equivalent capacitance of the target switch tube.

[0143] Furthermore, in one implementation of the present embodiment, the above-mentioned step of generating a target drive signal for the matrix circuit based on the modulation ratio includes: determining the modulation ratio as the active control quantity, and inputting the active control quantity and the preset reactive control quantity into a preset dq / αβ transformation model, and calculating the vector modulation parameters of the matrix circuit; based on the vector modulation parameters, generating the target drive signal for the matrix circuit.

[0144] Specifically, Fig.16 As shown, the modulation ratio M is determined as the active control quantity, and the preset reactive control quantity u is matched. q, the input power factor can be controlled. To achieve the correction control of the input power factor, the reactive control quantity 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 .

[0145] Through the implementation of the scheme of this embodiment, for any given set of parameters (L = 10uH, n = 1, U o =500V, f s =70kHz, i L (t0) = -10A), we can get Fig.17 The waveform diagram of the inductor current change shown in the figure shows that under different modulation ratios, the initial value of the inductor current can always be accurately controlled at the desired -10A, helping to achieve soft switching of all switches in the full range and improve the efficiency of the converter. It should be emphasized that in the related art, when closed-loop control of output voltage regulation and correction of input power factor are performed, it is often necessary to sample the three-phase input current and put it into the current loop for control, while this embodiment does not need to sample the three-phase input current, saving the cost of current sampling chips and peripheral circuits, and also allowing the power density to be further improved.

[0146] It can be seen that through the implementation of this embodiment, after the matrix circuit is connected to the three-phase AC power, the phase shift ratio of the converter is calculated based on the output voltage of the converter and the output voltage of the converter is closed-loop controlled; based on the phase shift ratio, the modulation ratio of the matrix circuit in the converter after closed-loop control is calculated; based on the modulation ratio, the target drive signal of the matrix circuit is generated; wherein, the target drive signal is used to drive the corresponding bidirectional switch tube to turn on or off during the process of switching the working mode of the converter to realize the soft switching of the converter. In this embodiment, the output voltage is closed-loop controlled by adjusting the phase shift angle; according to the target calculation formula, the corresponding modulation ratio M is calculated to realize the soft switching of all switch tubes in the full voltage range and full load range, which is conducive to reducing switching losses, improving the efficiency of the converter, and improving EMI. In addition, the soft switching control method provided in this embodiment can complete power factor correction without sampling the input current, which is conducive to saving circuit costs.

[0147] The fourth embodiment of the present application also provides a specific control method for the soft switch of the converter, which uses the modulation ratio as the first modulation parameter and the shift ratio as the second modulation parameter to control the converter to achieve soft switching of each switch tube within the full voltage range; specifically, the following implementation methods are included:

[0148] 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 alternating current 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 modulation ratio, calculating the second error parameter between the output voltage of the converter 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 value and the current active component reference value of the converter, performing input power factor correction on the matrix circuit and outputting the modulation ratio.

[0149] Specifically, after the matrix circuit is connected to the three-phase alternating current, 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; the input power factor of the matrix circuit is corrected in combination with the three-phase current sampling value and the current active component reference value to obtain a corresponding reactive power control amount and a modulation ratio; based on the reactive power control amount and the modulation ratio, a first drive signal of the matrix circuit is generated; wherein the first drive signal is used to drive the corresponding second switch tube to turn on or off, so as to realize closed-loop control of the output voltage and input current of the converter.

[0150] Furthermore, in one implementation of the present embodiment, the above-mentioned step of combining 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 reactive control amount and modulation ratio includes: inputting the three-phase current sampling values ​​into a preset abc / dq conversion model to calculate the reactive current and active current corresponding to the three-phase current sampling values; combining the reactive current and the preset reactive current component reference value to generate a power factor correction parameter; inputting the power factor correction parameter into the reactive current PI regulator of the converter to realize input power factor correction of the matrix circuit and output the corresponding reactive control amount; inputting the current active component reference value and the active current into the active current PI regulator of the converter to enable the active current PI regulator to output the modulation ratio of the matrix circuit.

[0151] Furthermore, in one implementation of the present embodiment, the step of generating the first drive signal of the matrix circuit based on the reactive control amount and the modulation ratio includes: inputting the reactive control amount and the modulation ratio into a preset dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; and generating the first drive signal of the matrix circuit based on the vector modulation parameters.

[0152] Specifically, Fig.18 The figure shows a control block diagram of a soft switch 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.

[0153] 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, 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 .

[0154] The inner current loop is composed of i abc , abc / dq, i d 、i q 、u d_PI 、uq_PI , two PI links. abc represents the sampling value of the three-phase input current (that is, the above three-phase current sampling value), the 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 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 β Input 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 first driving signal V GS_AP 、V GS_BP 、V GS_CP 、V GS_AN 、V GS_BN 、V GS_CN .

[0155] Further, in some implementations of this embodiment, under the premise of completing the above voltage outer loop + current inner loop, the modulation ratio M calculated by the active current PI regulator is substituted 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 φ1Calculate the second drive signal V corresponding to each first switch tube S1, S2, S3, S4 in the full bridge circuit GS_1 、V GS_2 、V GS_3 、V GS_4 In some specific drive control schemes, that is, in the process of driving and controlling the corresponding first switch tube by the second drive signal, V GS_1 、V GS_4 The same opening and closing, ignoring the dead zone, the duty cycle is 50%. In terms of phase, the rising edge of the second 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 V GS_1 、V GS_4 Based on this drive control scheme, any set of parameters (L = 15uH, n = 1, U o =500V, f s =70kHz, i L (t0) = -10A) under the inductor current change waveform, such as Fig.19 As shown, it can be seen that under different modulation ratios, the initial value of the inductor current can always be accurately controlled at the desired -10A, that is, it can help achieve soft switching of all switch tubes in the full voltage range and full load range, thereby improving the efficiency of the converter.

[0156] It can be seen that through the implementation of this embodiment, after the matrix circuit is connected to the three-phase AC power, based on the output voltage and three-phase current sampling values ​​of the converter, the modulation ratio of the matrix circuit is calculated and the output voltage of the converter is closed-loop controlled; based on the modulation ratio, the phase shift ratio of the converter after closed-loop control is calculated; based on the phase shift ratio, the second drive signal of the full-bridge circuit is generated; wherein the second drive signal is used to drive the corresponding first switch tube to turn on or off during the process of the converter switching the working mode, so as to realize the soft switching of the converter. Specifically, this embodiment takes the output voltage control and input power factor correction control as the first control target, and takes the realization of soft switching of all switch tubes in the full voltage range and full load range as the second control target, and makes full use of the control freedom (modulation ratio M and phase shift angle φ1) in the converter; by adjusting the modulation ratio M to perform closed-loop control on the output voltage; according to the target calculation formula, the corresponding phase shift angle φ1 is calculated, and the soft switching of all switch tubes in the full voltage range and full load range can be realized, so as to reduce the switching loss, improve the converter efficiency and improve the EMI.

[0157] Fig. 20A soft switch control device for a converter is provided in the fifth embodiment of the present application. 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 connect three-phase alternating current. The matrix circuit and the full-bridge circuit are respectively provided with multiple switch tubes. Fig.10 As shown, the soft switch control device of the converter mainly includes:

[0158] The first calculation module 2001 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 generate 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 and input current of the converter;

[0159] The second calculation module 2002 is used to calculate the second modulation parameter of the converter after closed-loop control based on the first modulation parameter; wherein the first modulation parameter and the second modulation parameter, one is the modulation ratio and the other is the shift ratio;

[0160] The generation module 2003 is used to generate 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 to realize the soft switching of 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.

[0161] 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 of the converter 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.

[0162] In some implementations of this embodiment, the first calculation module is also 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 of the converter 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 value and the current active component reference value of the converter to perform input power factor correction on the matrix circuit and output the modulation ratio.

[0163] 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 target calculation formula to calculate the second modulation parameter of the matrix circuit; wherein the target calculation formula includes a dual phase shift mode calculation formula and a single phase shift mode calculation formula; the dual phase shift mode calculation formula is expressed as:

[0164] U m M+K1D1U o +K2D2U o +K3U o =K4

[0165] The calculation formula of single phase shift mode is expressed as:

[0166] U m M+(K1+K2)D1U o +(K2+K3)U o =K4

[0167] D1 represents the outward shift ratio, D2 represents the inward shift ratio, K1, K2, K3, K4 are preset constant values, U o represents the output voltage, M represents the modulation ratio, U m Indicates the peak value of the three-phase AC phase voltage.

[0168] In some implementations of this embodiment, a derivation module is also included, which is 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 corresponds to multiple switching cycles in the time domain, 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, combined with the vector action duty cycle of the target sector in the space vector diagram and the voltage values ​​of each phase in the three-phase alternating current, the target calculation formula is derived.

[0169] Furthermore, in some implementations of this embodiment, the initial value of the inductor current and the output voltage of the matrix circuit satisfy the following relationship:

[0170]

[0171] Among them, u represents the voltage value output by the matrix circuit at the corresponding moment, t dead Indicates the dead time, C 0_mosfet Represents the equivalent capacitance of the target switch tube.

[0172] In some implementations of this embodiment, the generation module is specifically used to: when the second modulation parameter is the modulation ratio, determine the second modulation parameter as the active control quantity, and input the active control quantity and the preset reactive control quantity into the preset dq / αβ transformation model to calculate the vector modulation parameters of the matrix circuit; based on the vector modulation parameters, generate the second target drive signal of each switch tube in the matrix circuit.

[0173] According to the soft switching control device of the converter provided in this embodiment, 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 a plurality of first target drive signals are generated 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 and input current of the converter; based on the first modulation parameter, the second modulation parameter of the converter after the closed-loop control is calculated; wherein the first 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 generated; 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 realize the soft switching of 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. Through the implementation of the scheme of the present application, one modulation parameter in the phase shift ratio or the modulation ratio is adjusted first to achieve closed-loop control of the output voltage and the input current; then the other modulation parameter in the phase shift ratio or the modulation ratio is adjusted to drive the corresponding switch tubes to be turned on or off at the appropriate time, thereby achieving soft switching of all switch tubes within the full voltage range and the full load range, which can improve the working efficiency of the converter and achieve the effect of reducing switching losses and improving EMI.

[0174] The sixth embodiment of the present application also provides a soft switch control system. The soft switch control system can be used to implement the soft switch control method of the converter in the above-mentioned embodiment, mainly including: 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 above-mentioned embodiment 2 is implemented. Among them, the number of controllers can be one or more.

[0175] 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.

[0176] Furthermore, an embodiment of the present application also provides a computer-readable storage medium, which may be disposed in the above-mentioned soft switch control system, and the computer-readable storage medium may be the memory in the aforementioned embodiment.

[0177] The computer readable storage medium stores a computer program, and when the program is executed by the controller, the soft switch control method of the converter in the above-mentioned embodiment is implemented. Further, the computer readable storage 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] The above is a description of the soft switching control 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 may 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 soft switching control method for 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 soft switch control 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 generated 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 and input current of the converter; Based on the first modulation parameter, calculating a second modulation parameter of the converter after closed-loop control; wherein the first modulation parameter and the second modulation parameter, one is a modulation ratio and the other is a shift ratio; A plurality of second target drive signals are generated 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 realize the soft switching of 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.

2. The soft switching control method 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 of the converter and a preset output voltage reference value is calculated; The first error parameter is input into a preset voltage loop PI regulator so as to output the shift phase through the voltage loop PI regulator.

3. The soft switching control method 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 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 of the converter 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; In combination with the three-phase current sampling values ​​of the converter and the current active component reference value, the matrix circuit is subjected to input power factor correction and the modulation ratio is output.

4. The soft switching control method of the converter according to claim 1, characterized in that: The shift ratio includes an outward shift ratio and an inward shift ratio; The step of calculating, based on the first modulation parameter, a second modulation parameter of the matrix circuit in the converter after closed-loop control, comprises: Substituting the first modulation parameter into a target calculation formula, calculating the second modulation parameter of the matrix circuit; wherein the target calculation formula includes a dual-phase shift mode calculation formula and a single-phase shift mode calculation formula; the dual-phase shift mode calculation formula is expressed as: U m M+K1D1U o +K2D2U o +K3U o =K4 The calculation formula of the single phase shift mode is expressed as: U m M+(K1+K2)D1U o +(K2+K3)U o =K4 D1 represents the outward shift ratio, D2 represents the inward shift ratio, K1, K2, K3, K4 are preset constant values, U o represents the output voltage, M represents the modulation ratio, U m Indicates the peak value of the three-phase AC phase voltage.

5. The soft switching control method of the converter according to claim 4, characterized in that: Before calculating the second modulation parameter of the converter after closed-loop control based on the first modulation parameter, the method further includes: 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, a space vector diagram of the converter is generated; wherein the space vector diagram includes a plurality of sectors, each sector corresponds to a plurality of switching cycles in the time domain, and each of the switching cycles corresponds to a plurality of the working modes; Based on the symmetrical distribution rule of the vector current in the sector of the space vector diagram, combined with the vector action duty cycle of the target sector in the space vector diagram and the voltage value of each phase in the three-phase alternating current, the target calculation formula is derived.

6. The soft switching control method of the converter according to claim 4, characterized in that: The initial value of the inductor current and the output voltage of the matrix circuit satisfy the following relationship: Wherein, u represents the voltage value output by the matrix circuit at the corresponding time, t dead Indicates the dead time, C 0_mosfet Represents the equivalent capacitance of the target switch tube.

7. The soft switching control method of the converter according to claim 2, characterized in that: The generating a plurality of second target drive signals based on the second modulation parameter comprises: When the second modulation parameter is the modulation ratio, the second modulation parameter is determined as an active control amount, and the active control amount and a preset reactive control amount are input into a preset dq / αβ transformation model to calculate a vector modulation parameter of the matrix circuit; Based on the vector modulation parameters, second target driving signals corresponding to the switch tubes in the matrix circuit are generated respectively.

8. A soft switching control device for 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 soft switch control 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 to generate 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 and input current of the converter; A second calculation module is used to calculate a second modulation parameter of the converter after closed-loop control 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; A generating module, used to generate 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 realize soft switching of 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 soft switch control 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 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 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.

Images