Start control method and device of three-port converter circuit

Abstract

The invention provides a starting control method and device for a three-port converter circuit. The starting control method comprises the steps of collecting real-time voltages of the second ends of the three full-bridge circuits, responding to the situation that the real-time voltage of the load end is smaller than a preset voltage, starting an Nth round of quick starting mode, and starting the Nth round of quick starting mode in the Nth round of quick starting mode; determining an expression of the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the (N-1) th round of quick start mode and the real-time voltages of the second ends of the three full-bridge circuits, wherein N is a positive integer; and based on the expressions of the real-time voltages and the maximum currents of the second ends of the three full-bridge circuits, calculating the optimal solution of the switch-on phase difference among the three full-bridge circuits by using a mathematical optimization method. The optimal solution is a switch-on phase difference which enables all currents in the three-port converter circuit to be within a safe range and enables the power of the load end to be maximum. Therefore, the three-port converter circuit can rapidly reach a stable state in a safe state.

Description

Technical Field

[0001] The invention relates to the field of power electronics, and in particular to a startup control method and a device for a three-port converter circuit. Background Art

[0002] In recent years, research in the field of DC microgrids has increasingly become a focus. With its unique advantages, it has become a key platform for promoting the deep integration of power grids, new energy and energy storage technologies.

[0003] With the continuous advancement of industry technology, the market has put forward an urgent demand for power electronic converters with higher integration and greater power density. In this context, the three-port converter (TPC) technology came into being. With its simplicity of structural design, low loss characteristics in system operation, and high flexibility of energy flow, it plays a pivotal role in DC microgrid systems and injects new vitality into the future development of the industry. The three-port converter is usually used to realize energy transfer and management between different voltage levels. The main functions include conversion, regulation and distribution of electric energy. It is suitable for a variety of application scenarios, such as renewable energy systems, energy storage systems and electric vehicles. Generally, it has three ports, each of which can be connected to a different power source or load. For example, one end is connected to the grid, one end is connected to the energy storage battery or photovoltaic unit, and the remaining end is connected to the load.

[0004] Figure 1 The schematic diagram of the circuit structure of the commonly used three-port converter in the prior art is shown as follows: Figure 1 As shown, the three-port converter includes three full-bridge circuits B1, B2 and B3; a full-bridge circuit is a circuit that converts DC power into AC power, usually composed of four switch tubes (such as transistors, MOSFETs, IGBTs, etc.), the four switch tubes are divided into two pairs, and the two pairs of switches realize the switching and adjustment of the positive and negative polarities of voltage and current by alternating conduction; one end of the full-bridge circuit B1 is connected to the power supply V1, and the other end is connected to one of the coupling ends of the three-port transformer T1 through the inductor L1, the number of turns of the coil at the coupling end is n1, and the full-bridge circuit B1 includes the switch tube Q 11 , Q 12 , Q 13 and Q 14 , Q 11 and Q 13 The forward switch pair that forms the full-bridge circuit B1, Q 12 and Q 14 The reverse switch pair constitutes the full-bridge circuit B1; one end of the full-bridge circuit B2 is connected to the power supply V2, and the other end is connected to the other coupling end of the three-port transformer T1 through the inductor L2. The number of turns of the coil at the coupling end is n2. The full-bridge circuit B2 includes a switch tube Q 21 , Q22 , Q 23 and Q 24 , Q 21 and Q 23 The forward switch pair that forms the full bridge circuit B2, Q 22 and Q 24 The reverse switch pair constitutes the full-bridge circuit B2; one end of the full-bridge circuit B3 is connected to the load R3, and the other end is connected to the third coupling end of the three-port transformer T1 through the inductor L3. The number of turns of the coil at the coupling end is n3. The full-bridge circuit B3 includes a switch tube Q 31 , Q 32 , Q 33 and Q 34 , Q 31 and Q 33 The forward switch pair that forms the full bridge circuit B3, Q 32 and Q 34 The reverse switch pair constituting the full-bridge circuit B3 and the load R3 are also connected in parallel with a voltage stabilizing capacitor C3.

[0005] by Figure 1 Taking the three-port converter circuit shown in the figure as an example, at startup, there is no charge stored on the voltage-stabilizing capacitor C3 of the load port R3, and the circuit is equivalent to a short circuit. A large current will be generated at startup, which will not only easily damage the switching elements, but also generate a large amount of loss to reduce system efficiency. In order to protect the switching elements of the three-port converter circuit and improve efficiency to ensure power density, it is necessary to study the corresponding soft start strategy to limit the maximum current during the startup process. In addition, in order to increase the system power, fast startup should be considered as much as possible within the safety range. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0007] In order to improve the safety and power of a three-port converter circuit during startup, the present invention aims to provide a startup control method, device, equipment and computer storage medium for a three-port converter circuit.

[0008] According to one aspect of the present invention, a startup control method for a three-port converter circuit is provided, wherein the three-port converter circuit comprises three full-bridge circuits, three inductors and a three-port transformer, wherein the first port of each full-bridge circuit is coupled to one of the coupling ends of the three-port transformer via one of the three inductors, wherein the second end of the first full-bridge circuit and the second end of the second full-bridge circuit respectively constitute a first power input end and a second power input end, and the second end of the third full-bridge circuit constitutes a load end, wherein the load end is connected in parallel to a load and a voltage-stabilizing capacitor, and the startup control method comprises: collecting the real-time voltage of the second ends of the three full-bridge circuits, and in response to the real-time voltage of the load end being less than a preset voltage, starting the Nth round of fast startup; In the Nth round of quick start mode, an expression of the maximum current appearing in the three inductors is determined based on the switch turn-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits, where N is a positive integer; and an optimal solution of the switch turn-on phase difference between the three full-bridge circuits is calculated using a mathematical optimization method based on the real-time voltage at the second end of the three full-bridge circuits and the expression of the maximum current. The optimal solution is a switch turn-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end. The switch turn-on phase difference between the three full-bridge circuits is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

[0009] In one embodiment, the expression for determining the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of the fast start mode and the real-time voltage of the second end of the three full-bridge circuits includes: according to the current symmetry in the three-port converter circuit, using Calculate the current values ​​of all inflection points of the three inductors. xy represents the current of the xth inductor at the yth inflection point, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit respectively determined in the N-1th round of fast start-up mode, and k4, k5 and k6 are shown in the following table:

[0010] <![CDATA[i xy ]]> <![CDATA[k4]]> <![CDATA[k5]]> <![CDATA[k6]]> <![CDATA[i 11 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V1Z3-2V3Z2]]> <![CDATA[-2V3Z2]]> <![CDATA[i 12 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V1Z2+2V1Z3-2V2Z3]]> <![CDATA[i 13 ]]> <![CDATA[πV1Z3+πV1Z3-πV2Z3-πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V3Z2]]> <![CDATA[i 21 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V1Z3+2V3Z1]]> <![CDATA[2V3Z1]]> <![CDATA[i 22 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[2V1Z3-2V2Z1-2V2Z3]]> <![CDATA[i 23 ]]> <![CDATA[πV1Z3-πV2Z1+πV3Z1-πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[-2V3Z1]]> <![CDATA[i 31 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V3Z1-2V3Z2]]> <![CDATA[-2V3Z1-2V3Z2]]> <![CDATA[i 32 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V1Z2+2V2Z1]]> <![CDATA[i 33 ]]> <![CDATA[πV1Z2+πV2Z1-πV3Z1-πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V3Z1+2V3Z2]]>

[0011] , wherein V1, V2 and V3 are the real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively; and the current values ​​of all inflection points of the three inductors are compared, and the calculation formula corresponding to the maximum current value is determined as the expression of the maximum current.

[0012] In one embodiment, the expression for determining the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits also includes: when N=1, when determining the expression for the maximum current, φ2 and φ3 are initialized to 0.

[0013] In one embodiment, the optimal solution for calculating the switch-on phase difference between the three full-bridge circuits by using a mathematical optimization method includes: calculating the theoretical current of the load end based on the real-time voltage and the reference voltage of the load end; determining the smaller value of the theoretical current and the preset current as the limiting current; and solving To calculate the optimal solution of φ2 and φ3, where i max (φ2, φ3) is the expression of the maximum current, I set To limit the current, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively; V1, V2 and V3 are the real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively; φ2 and φ3 are the switch-on phase differences between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, respectively.

[0014] In one embodiment, solving The optimal solution to calculate φ2 and φ3 includes: Convert to KKT conditions and solve to obtain the optimal solution of φ2 and φ3.

[0015] In one embodiment, solving The optimal solution to calculate φ2 and φ3 includes: using Calculate the theoretical values ​​of φ2 and φ3 2set and φ 3set ; In response to use Calculate the execution values ​​of φ2 and φ3; or in response to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or in response to use Calculate the execution values ​​of φ2 and φ3; and determine the execution values ​​of φ2 and φ3 as the optimal solution. k3=2(Z1Z2+Z1Z3+Z2Z3), k4, k5 and k6 are the maximum current i determined in this round of fast start mode xy The corresponding expressions in the following table are calculated as follows:

[0016] <![CDATA[i xy ]]> <![CDATA[k4]]> <![CDATA[k5]]> <![CDATA[k6]]> <![CDATA[i 11 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V1Z3-2V3Z2]]> <![CDATA[-2V3Z2]]> <![CDATA[i 12 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V1Z2+2V1Z3-2V2Z3]]> <![CDATA[i 13 ]]> <![CDATA[πV1Z3+πV1Z3-πV2Z3-πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V3Z2]]> <![CDATA[i 21 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V1Z3+2V3Z1]]> <![CDATA[2V3Z1]]> <![CDATA[i 22 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[2V1Z3-2V2Z1-2V2Z3]]> <![CDATA[i 23 ]]> <![CDATA[πV1Z3-πV2Z1+πV3Z1-πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[-2V3Z1]]> <![CDATA[i 31 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V3Z1-2V3Z2]]> <![CDATA[-2V3Z1-2V3Z2]]> <![CDATA[i 32 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V1Z2+2V2Z1]]> <![CDATA[i 33 ]]> <![CDATA[πV1Z2+πV2Z1-πV3Z1-πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V3Z1+2V3Z2]]>

[0017] Table i xyRepresents the current of the xth inductor at the yth inflection point.

[0018] In one embodiment, calculating the theoretical current of the load end based on the real-time voltage of the load end and the reference voltage includes: determining the theoretical current using a proportional-integral control algorithm based on the real-time voltage of the load and the reference voltage of the load.

[0019] In one embodiment, the switch-on phase difference includes a first switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and a second switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, and the startup control method further includes: initializing a first PWM control signal of the first full-bridge circuit; setting the PWM control signal of the second full-bridge circuit to a second PWM signal that is delayed by the first switch-on phase difference from the first PWM control signal; and setting the PWM control signal of the third full-bridge circuit to a second PWM signal that is delayed by the second switch-on phase difference from the first PWM control signal.

[0020] According to another aspect of the present invention, a starting device for a three-port converter circuit is also disclosed. The three-port converter circuit includes three full-bridge circuits, three inductors and a three-port transformer. The first port of each full-bridge circuit is coupled to one of the coupling ends of the three-port transformer through one of the three inductors. The second end of the first full-bridge circuit and the second end of the second full-bridge circuit constitute the first power input end and the second power input end respectively. The second end of the third full-bridge circuit constitutes the load end. The load end is connected in parallel with the load and the voltage-stabilizing capacitor. The starting device includes a collection device and a control device connected to the collection device. The collection device is used to collect the real-time voltage of the second ends of the three full-bridge circuits. The control device is configured to: in response to the real-time voltage of the load end being small At a preset voltage, the Nth round of quick start mode is started. In the Nth round of quick start mode, the control device determines an expression of the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits, where N is a positive integer. Based on the real-time voltage at the second end of the three full-bridge circuits and the expression of the maximum current, a mathematical optimization method is used to calculate an optimal solution for the switch turn-on phase difference between the three full-bridge circuits. The optimal solution is a switch turn-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end. The switch turn-on phase difference between the three full-bridge circuits is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

[0021] In one embodiment, the control device is further configured to: according to the current symmetry in the three-port converter circuit, use Calculate the current values ​​of all inflection points of the three inductors; and compare the current values ​​of all inflection points of the three inductors, and determine the calculation formula corresponding to the maximum current value as the expression of the maximum current. xy represents the current of the xth inductor at the yth inflection point, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit respectively determined in the N-1th round of fast start-up mode, and k4, k5 and k6 are shown in the following table:

[0022] <![CDATA[i xy ]]> <![CDATA[k4]]> <![CDATA[k5]]> <![CDATA[k6]]> <![CDATA[i 11 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V1Z3-2V3Z2]]> <![CDATA[-2V3Z2]]> <![CDATA[i 12 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V1Z2+2V1Z3-2V2Z3]]> <![CDATA[i 13 ]]> <![CDATA[πV1Z3+πV1Z3-πV2Z3-πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V3Z2]]> <![CDATA[i 21 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V1Z3+2V3Z1]]> <![CDATA[2V3Z1]]> <![CDATA[i 22 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[2V1Z3-2V2Z1-2V2Z3]]> <![CDATA[i 23 ]]> <![CDATA[πV1Z3-πV2Z1+πV3Z1-πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[-2V3Z1]]> <![CDATA[i 31 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V3Z1-2V3Z2]]> <![CDATA[-2V3Z1-2V3Z2]]> <![CDATA[i 32 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V1Z2+2V2Z1]]> <![CDATA[i 33 ]]> <![CDATA[πV1Z2+πV2Z1-πV3Z1-πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V3Z1+2V3Z2]]>

[0023] Among them, V1, V2 and V3 are real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively.

[0024] In one embodiment, the control device is further configured to: when N=1, initialize φ2 and φ3 to 0 when determining the expression of the maximum current.

[0025] In one embodiment, the starting device further includes a proportional-integral controller and a limiter. The proportional-integral controller is connected to the acquisition device to obtain the real-time voltage at the load end. The proportional-integral controller is connected to the control device through the limiter. The proportional-integral controller calculates the theoretical current at the load end based on the reference voltage and the real-time voltage at the load end and outputs the theoretical current to the limiter. In response to the theoretical current being less than the upper limit current and greater than the lower limit current, the limiter outputs the theoretical current to the control device. In response to the theoretical current being greater than or equal to the upper limit current, the limiter outputs the upper limit current to the control device. In response to the theoretical current being less than or equal to the lower limit current, the limiter outputs the lower limit current to the control device. The control device is further configured to: solve To calculate the optimal solution of φ2 and φ3, where i max (φ2, φ3) is the expression of the maximum current, I set is the output current of the limiter, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, V1, V2 and V3 are the real-time voltages at the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit respectively.

[0026] In one embodiment, the control device is further configured to: Calculate the theoretical values ​​of φ2 and φ3 2set and φ 3set ; In response to use Calculate the execution values ​​of φ2 and φ3; or in response to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or in response to use Calculate the execution values ​​of φ2 and φ3; and determine the execution values ​​of φ2 and φ3 as the optimal solution. k3=2(Z1Z2+Z1Z3+Z2Z3), k4, k5 and k6 are the maximum current i determined in this round of fast start mode xy The corresponding expressions in the following table are calculated as follows:

[0027] <![CDATA[i xy ]]> <![CDATA[k4]]> <![CDATA[k5]]> <![CDATA[k6]]> <![CDATA[i 11 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V1Z3-2V3Z2]]> <![CDATA[-2V3Z2]]> <![CDATA[i 12 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V1Z2+2V1Z3-2V2Z3]]> <![CDATA[i 13 ]]> <![CDATA[πV1Z3+πV1Z3-πV2Z3-πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V3Z2]]> <![CDATA[i 21 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V1Z3+2V3Z1]]> <![CDATA[2V3Z1]]> <![CDATA[i 22 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[2V1Z3-2V2Z1-2V2Z3]]> <![CDATA[i 23 ]]> <![CDATA[πV1Z3-πV2Z1+πV3Z1-πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[-2V3Z1]]> <![CDATA[i 31 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V3Z1-2V3Z2]]> <![CDATA[-2V3Z1-2V3Z2]]> <![CDATA[i 32 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V1Z2+2V2Z1]]> <![CDATA[i 33 ]]> <![CDATA[πV1Z2+πV2Z1-πV3Z1-πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V3Z1+2V3Z2]]>

[0028] Table i xy Represents the current of the xth inductor at the yth inflection point.

[0029] In any of the aforementioned embodiments, the switch-on phase difference includes a first switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and a second switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, characterized in that the control device is further configured to: initialize and set a first PWM control signal for the first full-bridge circuit; set the PWM control signal of the second full-bridge circuit to a second PWM signal that is delayed by the first switch-on phase difference from the first PWM control signal; and set the PWM control signal of the third full-bridge circuit to a third PWM signal that is delayed by the second switch-on phase difference from the first PWM control signal; and output the first PWM control signal, the second PWM signal and the third PWM signal to the switch tube of the first full-bridge circuit, the switch tube of the second full-bridge circuit and the switch tube of the third full-bridge circuit respectively to control the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit to be forward-conducted or reverse-conducted.

[0030] According to another invention of the present invention, a startup control device for a three-port converter circuit is also disclosed, including a memory, a processor, and a computer program stored in the memory, and the processor is used to execute the computer program stored in the memory to implement the steps of the startup control method for the three-port converter circuit as described in any of the aforementioned embodiments.

[0031] According to another invention of the present invention, an energy storage device is also disclosed, including a three-port converter circuit and a starting device connected to the three-port converter circuit, the starting device is used to control the three-port converter circuit to implement the starting control method as described in any of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings.

[0033] Figure 1 is a circuit structure diagram of an exemplary three-port converter circuit according to the prior art;

[0034] Figure 2 is a flow chart of a startup control method of a three-port converter circuit in an embodiment according to one aspect of the present invention;

[0035] Figure 3 is a schematic diagram of voltage curves of the second ends of three ports in a three-port converter circuit according to one aspect of the present invention;

[0036] Figure 4 is a schematic diagram of a voltage curve and a current curve of any inductor in a three-port converter circuit according to one aspect of the present invention;

[0037] Figure 5 is a partial flow chart of a startup control method of a three-port converter circuit in an embodiment according to one aspect of the present invention;

[0038] Figure 6 is a module block diagram of a startup control device of a three-port converter circuit in an embodiment according to another aspect of the present invention;

[0039] Figure 7 is a module block diagram of a startup control device of a three-port converter circuit in an embodiment according to another aspect of the present invention;

[0040] Figure 8 is a module block diagram of an energy storage device in an embodiment according to one aspect of the present invention. DETAILED DESCRIPTION

[0041] The following description is given to enable those skilled in the art to implement and use the invention and incorporate it into a specific application context. Various modifications, as well as various uses in different applications will be readily apparent to those skilled in the art, and the general principles defined herein are applicable to a wide range of embodiments. Thus, the present invention is not limited to the embodiments given herein, but should be granted the broadest scope consistent with the principles and novel features disclosed herein.

[0042] In the following detailed description, many specific details are set forth to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the practice of the present invention need not be limited to these specific details. In other words, known structures and devices are shown in block diagram form without detailed display to avoid obscuring the present invention.

[0043] The reader is reminded of all documents and literature filed simultaneously with this specification and open to public inspection, and the contents of all such documents and literature are incorporated herein by reference. Unless otherwise directly stated, all features disclosed in this specification (including any attached claims, abstracts and drawings) can be replaced by alternative features for achieving the same, equivalent or similar purposes. Therefore, unless otherwise explicitly stated, each feature disclosed is only an example of a group of equivalent or similar features.

[0044] Note that, where used, the symbols left, right, front, back, top, bottom, forward, reverse, clockwise and counterclockwise are used only for convenience and do not imply any specific fixed direction. In fact, they are used to reflect the relative position and / or direction between the various parts of the object. In addition, the terms "first" and "second" are used only for descriptive purposes and should not be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, which may be directly connected, indirectly connected through an intermediate medium, or internally connected between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Note that, in the case of use, further, preferably, further and more preferably are simple beginnings for explaining another embodiment based on the previous embodiment, and the content of further, preferably, further or more preferably followed by the above embodiment is combined with the previous embodiment as a complete composition of another embodiment. Several further, preferably, further or more preferably settings followed by the same embodiment can be arbitrarily combined to form another embodiment.

[0047] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0048] According to one aspect of the present invention, a startup control method for a three-port converter circuit is provided.

[0049] A three-port converter circuit refers to a conversion circuit that includes three ports and can realize conversion, regulation and distribution of electrical energy between the three ports. Figure 1 is a schematic diagram of a conventional three-port converter circuit in the art, referring to Figure 1 The basic structure of the three-port converter circuit can be understood, such as Figure 1As shown, the three-port converter circuit generally includes three full-bridge circuits, three inductors and a three-port transformer.

[0050] Each full-bridge circuit includes two pairs of switch tubes, and the alternating opening of the two pairs of switch tubes can realize the mutual conversion between direct current and alternating current. Each full-bridge circuit includes two ports, with the AC port as the first port and the DC port as the second port, one of which is the input end and the other is the output end. Based on the different functional settings of the full-bridge circuit, the input end and the output end can be converted to each other. For example, the input end can be a DC end and the output end can be an AC end, or the input end can be an AC end and the output end can be a DC end.

[0051] The three-port transformer T1 includes three ports coupled to each other. Figure 1 The coupling ports are implemented by using coils, and the numbers of coil turns of the three ports are n1, n2 and n3 respectively.

[0052] The first port (AC end) of each full-bridge circuit is coupled to one of the coupling ports of the three-port transformer through one of the three inductors, such as Figure 1 As shown, the first port of the full-bridge circuit B1 is connected to the coupling port n1 of the three-port transformer T1 through the inductor L1, the first port of the full-bridge circuit B2 is connected to the coupling port n2 of the three-port transformer T1 through the inductor L2, and the first port of the full-bridge circuit B3 is connected to the coupling port n3 of the three-port transformer T1 through the inductor L3.

[0053] The three-port converter circuit generally has three ports, two of which are used as power input terminals and the remaining port is used as a load terminal. In the present application, the second ends of the three full-bridge circuits constitute the three ports of the three-port converter circuit, the second end of the first full-bridge circuit and the second end of the second full-bridge circuit are used as power input terminals to respectively constitute the first power input terminal and the second power input terminal, the second end of the third full-bridge circuit is used as a load terminal, and the load terminal is connected in parallel with a load and a voltage stabilizing capacitor.

[0054] It can be understood that in a specific application scenario, the three-port converter circuit may also include other adapted circuit functions and their corresponding devices, for example, the second end of the first full-bridge circuit and the second end of the second full-bridge circuit may also be provided with corresponding voltage-stabilizing capacitors. This application only takes the basic circuit structure of the three-port converter circuit as an example to illustrate the startup control method of the three-port converter circuit, and does not limit the specific circuit structure of the three-port converter circuit or the circuit structure of its peripheral circuits.

[0055] Figure 2 A startup control method applicable to a three-port converter circuit in a specific embodiment is shown. Figure 2 The startup control method shown includes steps S210 to S230.

[0056] Wherein, step S210 is: collecting the real-time voltage of the second end of the three full-bridge circuits, and in response to the real-time voltage of the load end being less than the preset voltage, starting the Nth round of quick start mode.

[0057] "Collection" generally refers to obtaining real-time voltage by certain means, which can be obtained from an external voltage detection device or directly collected by directly setting a voltage detection unit. The "collection" frequency in step S210 can be set based on the supported collection frequency of the collection device, the switching alternating conduction frequency of the full-bridge circuit, or the computing power of the computing device. For example, the minimum value of the frequency determined based on the three can be determined as the actual collection accuracy. After each collection, the real-time voltage at the load end is compared with the preset voltage to determine whether to turn on the fast start mode. Among them, the frequency set based on the computing power of the computing device refers to the reciprocal of the time required to complete a round of fast start mode. It can be understood that within this time, even if multiple real-time voltages are obtained, only one round of fast start mode can be completed. Therefore, multiple acquisitions may result in data lag or waste.

[0058] The preset voltage can be set according to the steady-state voltage across the load R3. It can be understood that when the three-port converter circuit completes startup and reaches a stable state, the voltage across the voltage-stabilizing capacitor C3 remains unchanged, the voltage-stabilizing capacitor C3 is equivalent to being disconnected, and the voltage across the load R3 remains stable, which is the steady-state voltage. Preferably, the preset voltage can be set to 80% or more of the steady-state voltage, which can generally be understood as when the real-time voltage at the load end reaches the preset voltage value, the voltage-stabilizing capacitor in the third full-bridge circuit has stored a certain amount of electricity, and in the process of the load end voltage continuing to climb, the current in the third full-bridge circuit will no longer have the degree of damaging the switching element.

[0059] It can be understood that step S210 is a loop step. When the voltage across the load has not reached the preset voltage, step S210 will be executed repeatedly. If the voltage across the load reaches the preset voltage, the quick start mode is no longer started, and the control mode when the three-port converter circuit is in a stable state can be entered as needed. The present application does not limit the control mode in the stable state.

[0060] In the Nth round of quick start mode, step S220 is: based on the switch turn-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits, an expression of the maximum current appearing in the three inductors is determined, where N is a positive integer.

[0061] The following combination Figure 3 and Figure 4 Explain the principle of determining the maximum current.

[0062] Figure 3Figure 2 shows a schematic diagram of the voltage waveform at the midpoint of the bridge arm of the three-port converter circuit. Figure 1 Taking the full-bridge circuit B1 shown in the figure as an example, the voltage at the midpoint of the bridge arm refers to the switch tube Q 11 and Q 13 The connection point and the switch tube Q 12 and Q 14 The voltage difference between the connection points. Figure 3 The horizontal axis is the phase, and the vertical axis is the voltage difference at the midpoint of the bridge arm of any full-bridge circuit (i.e., the voltage difference at the first end of any full-bridge circuit). When the forward switch pair of a full-bridge circuit is turned on and the reverse switch pair is turned off, the voltage at the first end of the full-bridge circuit is positive. When the reverse switch pair of a full-bridge circuit is turned on and the forward switch pair is turned off, the voltage at the first end of the full-bridge circuit is negative. Figure 3 As shown, assuming that the forward turn-on starting phase of the first full-bridge circuit is θ0, the reverse turn-on starting phase of the first full-bridge circuit is θ3, the forward turn-on starting phase of the second full-bridge circuit is θ1, and the forward turn-on starting phase of the third full-bridge circuit is θ2, then the phase difference φ2 between θ0 and θ1 is the switch conduction phase difference between the first full-bridge circuit and the second full-bridge circuit, the phase difference φ3 between θ0 and θ2 is the switch conduction phase difference between the first full-bridge circuit and the third full-bridge circuit, and the reverse turn-on starting phase of the second full-bridge circuit and the reverse turn-on starting phase of the third full-bridge circuit can be calculated according to the period of the PWM control signal of the switch tube and are no longer marked.

[0063] Figure 4 The figure shows the corresponding curves of the voltage and current at both ends of the inductor connected to a full-bridge circuit. That is, the current variation trend of the inductor (L1 / L2 / L3) in the three-port transformer circuit is as follows: Figure 4 The curve i in Lx As shown in Figure 2, the voltage variation trend of the inductor (L1 / L2 / L3) is as follows: Figure 4 The curve V Lx As shown. Combined Figure 4 It can be seen that the voltage of each inductor and its current have a corresponding relationship, so the corresponding current curve can be determined according to the collected real-time voltage.

[0064] like Figure 4 As shown, the curve of any inductor generally includes three inflection points, and different inflection points correspond to different current expressions. Figure 4 The inflection point current in is marked as i xy In the form of, x represents the port (i.e., 1 represents the first port B1, 2 represents the second port B2, and 3 represents the third port B3), and y represents the inflection point (1 represents inflection point 1, i.e., the current inflection point when the phase is θ1, 2 represents inflection point 2, i.e., the current inflection point when the phase is θ2, and 3 represents inflection point 3, i.e., the current inflection point when the phase is θ3).

[0065] It can be understood that in order to improve the safety of the three-port converter circuit, it is necessary to ensure that the maximum current in the circuit is still within the safe current range of the three-port converter circuit. Therefore, in any round of the fast start mode, it is necessary to determine the inductance and inflection point where the maximum current in the circuit appears. Since the phase shift angle changes continuously during the entire startup process, the value of the current at each inflection point in the current control cycle can be predicted by the value of the phase shift angle in the previous control cycle.

[0066] Specifically, step S220 can be refined as follows: according to the current symmetry in the three-port converter circuit, the switch-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits are substituted into the calculation to determine the current values ​​of all inflection points of the three inductors; and the current values ​​of all inflection points of the three inductors are compared, and the calculation formula corresponding to the maximum current value is determined as the expression of the maximum current.

[0067] In the first round of rapid startup mode, that is, when N=1, the switch-on phase differences φ2 and φ3 determined in the N-1th round can be set to 0, that is, a switch-on phase difference value is initialized for the first round of rapid startup mode.

[0068] Figure 4 Each current in can be expressed as the following formula (1):

[0069]

[0070] Among them, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively; when N=1, φ2 and φ3 are 0, and when N≠1, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit determined by the N-1 rounds of quick start mode; k4, k5 and k6 are coefficients corresponding to the inductance and the inflection point. According to the current symmetry in the three-port converter circuit, k4, k5 and k6 can be represented by the real-time voltage of the second end of the three full-bridge circuits and the impedance of the inductance, as shown in Table 1.

[0071] Table 1

[0072] <![CDATA[i xy ]]> <![CDATA[k4]]> <![CDATA[k5]]> <![CDATA[k6]]> <![CDATA[i 11 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V1Z3-2V3Z2]]> <![CDATA[-2V3Z2]]> <![CDATA[i 12 ]]> <![CDATA[πV2Z3-πV1Z3-πV1Z2+πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V1Z2+2V1Z3-2V2Z3]]> <![CDATA[i 13 ]]> <![CDATA[πV1Z3+πV1Z3-πV2Z3-πV3Z2]]> <![CDATA[-2V2Z3]]> <![CDATA[2V3Z2]]> <![CDATA[i 21 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V1Z3+2V3Z1]]> <![CDATA[2V3Z1]]> <![CDATA[i 22 ]]> <![CDATA[πV2Z1-πV1Z3-πV3Z1+πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[2V1Z3-2V2Z1-2V2Z3]]> <![CDATA[i 23 ]]> <![CDATA[πV1Z3-πV2Z1+πV3Z1-πV2Z3]]> <![CDATA[-2V2Z1-2V2Z3]]> <![CDATA[-2V3Z1]]> <![CDATA[i 31 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[-2V1Z2-2V3Z1-2V3Z2]]> <![CDATA[-2V3Z1-2V3Z2]]> <![CDATA[i 32 ]]> <![CDATA[πV3Z1-πV2Z1-πV1Z2+πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V1Z2+2V2Z1]]> <![CDATA[i 33 ]]> <![CDATA[πV1Z2+πV2Z1-πV3Z1-πV3Z2]]> <![CDATA[2V2Z1]]> <![CDATA[2V3Z1+2V3Z2]]>

[0073] Z1, Z2 and Z3 in Table 1 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, and V1, V2 and V3 in Table 1 are the real-time voltages of the first ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively.

[0074] It can be understood that the impedance of the inductor connected to the three full-bridge circuits is a fixed value. When the real-time voltage of the second end of the three full-bridge circuits is obtained, k4, k5 and k6 in the current expression of each inflection point of each inductor can be calculated. Therefore, in each round of rapid start mode, the φ2 and φ3 of the previous round and the real-time voltage of the second end of the three full-bridge circuits are substituted into formula (1) to calculate the specific current value of each inflection point of each inductor. Then, by comparing the three inflection points of the three inductors, a total of 9 specific current values, the inductor and its inflection point where the maximum current appears can be determined. The current expression of the corresponding inflection point of the corresponding inductor where the maximum current appears is determined as the maximum current expression. It can be understood that in the comparison process, φ2 and φ3 are replaced by the phase difference of the previous round; in the maximum current expression, φ2 and φ3 refer to the control phase difference that needs to be determined in this round of rapid start mode, so they are still represented by unknown parameters φ2 and φ3, and k4, k5 and k6 are represented by specific values ​​obtained by table lookup and calculation, that is, there are and only unknown parameters φ2 and φ3 in the maximum current expression.

[0075] Further, step S230 is: based on the expressions of the real-time voltage and the maximum current at the second ends of the three full-bridge circuits, a mathematical optimization method is used to calculate the optimal solution of the switch-on phase difference between the three full-bridge circuits. The optimal solution is a switch-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end. The switch-on phase difference is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

[0076] It can be understood that when the maximum current is within the safe range, the current at any position of the three-port converter circuit is within the safe range, and at the same time, the load current also has an achievable limit. Therefore, the theoretical current corresponding to the load can be determined based on the real-time voltage of the load, and then the limit of the maximum current can be determined based on the magnitude relationship between the theoretical current and the preset current.

[0077] Those skilled in the art will appreciate that mathematical optimization problems can be solved using existing or future mathematical methods that can solve mathematical optimization problems.

[0078] In a specific embodiment, the theoretical current of the load can be calculated using a proportional integral control algorithm. The reference value of the proportional integral algorithm can be set to the reference voltage of the load, such as determining the voltage of the load when the three-port converter circuit is in a steady state as the reference voltage; the input value of the proportional integral control algorithm (PI, Proportion Integral) can be set to the real-time voltage of the load. That is, based on the reference voltage and implementation voltage of the load, the theoretical current of the load can be calculated using the proportional integral control algorithm.

[0079] It should be noted that the proportional-integral control algorithm can ensure the calculation accuracy of the theoretical current without generating too much waste of computing power; without considering the waste of resources, technicians in this field can also adopt other existing or future calculation methods that can calculate the corresponding current based on the real-time voltage, such as PID (Proportion Integral Differential) control algorithm.

[0080] The preset current can be set based on the amplitude of the maximum safe current of the three-port converter circuit, such as the maximum safe current, or the amplitude can be set to a value slightly smaller than the amplitude of the maximum safe current. Then the amplitude of the theoretical current of the load and the preset current can be compared, and the smaller amplitude is determined as the limiting current I set It can be understood that the limiting current has a positive and negative sign, and the positive and negative signs of the theoretical current are determined as the positive and negative signs of the limiting current.

[0081] The power expression of the load is shown in equation (2).

[0082]

[0083] The constraint condition of the switch turn-on phase difference can be expressed as a mathematical optimization problem shown in the following formula (3).

[0084]

[0085] Among them, i max (φ2, φ3) is the expression of the maximum current determined in the aforementioned step S220, I set To limit the current, φ2 and φ3 are unknown parameters that need to be determined in this round of fast start mode.

[0086] The optimization problem shown in formula (3) can be transformed into KKT conditions (Karush-Kuhn-Tucker Conditions, Carlos-Kuhn-Tucker conditions, common aliases: Kuhn-Tucker, Karush-Kuhn-Tucker optimization conditions, Karush-Kuhn-Tucker conditions, Kuhn-Tucker optimization conditions, Kuhn-Tucker conditions)).

[0087] The KKT condition refers to a necessary and sufficient condition for a nonlinear programming problem to have an optimal solution under certain regular conditions. Under the premise that formula (3) can be converted into the KKT condition, the mathematical optimization problem has an optimal solution.

[0088] In a specific embodiment, the solution of the KKT condition transformed from equation (3) is the following equation (4):

[0089]

[0090] Among them, φ 2set and φ 3set They refer to the theoretical values ​​of φ2 and φ3 obtained by solving, k3=2(Z1Z2+Z1Z3+Z2Z3), k4, k5 and k6 are the maximum current i determined in this round of fast start mode xy The calculated values ​​of the corresponding expressions in Table 1.

[0091] Then, when the calculated φ 2set and φ 3set Satisfied When φ2 and φ3 are equal to φ 2set and φ 3set .

[0092] When φ 2set and φ 3set Any one of them does not satisfy the restriction condition of formula (3) When the switch that does not meet the phase difference φ is turned on, 2set or φ 3set Set it as its corresponding limit value, and then calculate the other one according to formula (1).

[0093] Specifically, when φ 2set When ≤0, the execution value of φ2 can be set to 0, and then the execution value of φ3 can be calculated using formula (1), as shown in formula (5); When , the execution value of φ3 can be set to π / 2, and then the execution value of φ2 can be calculated using formula (1), as shown in formula (6).

[0094]

[0095]

[0096] In summary, φ is determined by formula (4) 2set and φ 3set After that, based on φ 2set and φ 3set The distribution interval of determines the execution values ​​of φ2 and φ3, which can be summarized as the following formula (7):

[0097]

[0098] The execution values ​​of φ2 and φ3 are the optimal solutions to the mathematical optimization problem (3).

[0099] Preferably, after the execution values ​​of φ2 and φ3 are determined, corresponding switch-on control signals of the first full-bridge circuit, the second full-bridge circuit, and the third full-bridge circuit can be generated.

[0100] Figure 5 FIG. 2 shows a schematic diagram of the steps of generating a switch-on control signal in an embodiment. Figure 5 As shown, in this embodiment, after the execution values ​​of φ2 and φ3 are determined, steps S510 to S530 may be further included.

[0101] Wherein, step S510 is: initializing and setting a first PWM control signal of the first full-bridge circuit.

[0102] In a switching cycle, when the PWM control signal is positive, the forward switch pair is turned on and the reverse switch pair is turned off; when the PWM control signal is negative, the forward switch pair is turned off and the reverse switch pair is turned on.

[0103] Step S520 is: setting the PWM control signal of the second full-bridge circuit to a second PWM signal that is delayed by a first switch-on phase difference from the first PWM control signal.

[0104] That is, PWM2(ωt+φ2)=PWM1(ωt), wherein PWM1 refers to the PWM control signal of the first full-bridge circuit, and PWM2 refers to the PWM control signal of the second full-bridge circuit.

[0105] Step S530 is: setting the PWM control signal of the third full-bridge circuit to a second PWM signal that is delayed by a second switch-on phase difference from the first PWM control signal.

[0106] That is, PWM3(ωt+φ3)=PWM1(ωt), wherein PWM1 refers to the PWM control signal of the first full-bridge circuit, and PWM3 refers to the PWM control signal of the third full-bridge circuit.

[0107] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0108] According to another aspect of the present invention, a startup control device for a three-port converter circuit is also provided.

[0109] Figure 6 FIG. 6 shows a startup control device 600 of a three-port converter circuit in a specific embodiment. Figure 6 As shown, the startup control device 600 of the three-port converter circuit includes a memory 610 and a processor 620 .

[0110] The memory 610 is used to store computer programs.

[0111] The processor 620 is connected to the memory 610 to execute the computer program stored in the memory 610. When the processor 620 executes the computer program, the steps of the startup control method of the three-port converter circuit in any of the above embodiments are implemented.

[0112] According to another aspect of the present invention, there is also provided a Figure 1 The starting device of the three-port converter circuit shown.

[0113] in, Figure 1 The three-port converter circuit shown is as described in the aforementioned startup control method of the three-port converter circuit, and will not be described in detail again.

[0114] Figure 7 A starting device suitable for a three-port converter circuit in a specific embodiment is shown. Figure 7 The starting device shown includes a collection device 710 and a control device 710 connected to the collection device 710 .

[0115] The acquisition device 710 is used to acquire the real-time voltages V1, V2 and V3 of the second ends of the three full-bridge circuits.

[0116] The acquisition device 710 may be an existing or future device that can acquire voltage in real time, such as a Hall sensor.

[0117] The actual acquisition frequency of the acquisition device 710 can be set based on the supported acquisition frequency of the acquisition device, the switching alternating conduction frequency of the full-bridge circuit, or the computing power of the computing device. For example, the minimum value of the frequencies determined based on the three can be determined as the actual acquisition accuracy. Among them, the frequency set based on the computing power of the computing device refers to the reciprocal of the time required to complete a round of the fast start mode.

[0118] Optionally, the actual acquisition frequency of the acquisition device 710 may be the acquisition frequency set by the device, but the frequency of outputting the real-time voltage to the control device 720 or the frequency of the control device 720 obtaining the real-time voltage from the acquisition device 710 may be set based on the supportable acquisition frequency of the acquisition device, the switching alternating conduction frequency of the full-bridge circuit, or the computing power of the computing device.

[0119] Preferably, the acquisition device 710 may include at least three sub-devices to respectively acquire the real-time voltage of the second end of the three full-bridge circuits, and the acquisition start signals of the three sub-devices are the same, that is, the three sub-devices simultaneously acquire the real-time voltage of the corresponding monitoring object.

[0120] The control device 720 is configured to: in response to the real-time voltage at the load end being less than the preset voltage, start the Nth round of quick start mode. In the Nth round of quick start mode, the control device 720 determines the expression of the maximum current appearing in the three inductors based on the switch-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits, where N is a positive integer, and calculates the optimal solution of the switch-on phase difference between the three full-bridge circuits based on the real-time voltage at the second end of the three full-bridge circuits and the expression of the maximum current using a mathematical optimization method. Among them, the optimal solution is the switch-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end, and the switch-on phase difference between the three full-bridge circuits is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

[0121] Among them, the preset voltage can be set according to the steady-state voltage across the load R3. It can be understood that when the three-port converter circuit completes startup and reaches a stable state, the voltage across the voltage-stabilizing capacitor C3 remains unchanged, the voltage-stabilizing capacitor C3 is equivalent to a circuit breaker, and the voltage across the load R3 remains stable, which is the steady-state voltage. Preferably, the preset voltage can be set to 80% or more of the steady-state voltage, which can generally be understood as when the real-time voltage at the load end reaches the preset voltage value, the voltage-stabilizing capacitor in the third full-bridge circuit has stored a certain amount of electricity, and in the process of the load end voltage continuing to climb, the current in the third full-bridge circuit will no longer have the degree of damaging the switching element.

[0122] It can be understood that when the voltage across the load has not reached the preset voltage, the control device 720 will continuously obtain the real-time voltage at the load end and determine whether to start the next round of fast start mode. If the voltage across the load reaches the preset voltage, the control device 720 will no longer start the fast start mode, and can enter the control mode when the three-port converter circuit is in a stable state as needed.

[0123] The principle of determining the maximum current has been described in detail in the startup control method of the aforementioned three-port converter circuit and will not be repeated here.

[0124] Specifically, in order to determine the expression of the maximum current, the control device 720 is further configured to: according to the current symmetry in the three-port converter circuit, use The current values ​​of all the inflection points of the three inductors are calculated; and the current values ​​of all the inflection points of the three inductors are compared, and the calculation formula corresponding to the maximum current value is determined as the expression of the maximum current.

[0125] Among them, i xyrepresents the current of the xth inductor at the yth inflection point, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit respectively determined in the N-1th round of quick start mode, and k4, k5 and k6 are as shown in Table 1 above.

[0126] In particular, in the first round of the rapid start-up mode, ie, when N=1, the control device 720 initializes the switch-on phase differences φ2 and φ3 in the first round of calculation to zero.

[0127] It can be understood that the impedance of the inductor connected to the three full-bridge circuits is a fixed value. After the real-time voltage of the second end of the three full-bridge circuits is obtained, k4, k5 and k6 in the current expression of each inflection point of each inductor can be calculated. Therefore, in each round of fast start mode, φ2 and φ3 of the previous round and the real-time voltage of the second end of the three full-bridge circuits are substituted into The specific current value of each inflection point of each inductor can be calculated.

[0128] By comparing the specific values ​​of the three inflection points of the three inductors, a total of 9 currents, the inductor where the maximum current appears and its inflection point can be determined. The current expression of the corresponding inflection point of the corresponding inductor where the maximum current appears is determined as the maximum current expression. It can be understood that in the comparison process, φ2 and φ3 are replaced by the phase difference of the previous round; in the maximum current expression, φ2 and φ3 refer to the control phase difference that needs to be determined in this round of quick start mode, so they are still expressed by unknown parameters φ2 and φ3, and k4, k5 and k6 are expressed by specific values ​​obtained by table lookup and calculation, that is, there are only unknown parameters φ2 and φ3 in the maximum current expression.

[0129] Furthermore, the starting device 700 may further include a proportional-integral controller 730 and a limiter 740 .

[0130] The proportional-integral controller 730 is connected to the acquisition device 710 to obtain the real-time voltage V3 of the load end. The proportional-integral controller (PI) 730 is based on the reference voltage V ref And the real-time voltage V3 calculates the theoretical current I at the load end S .

[0131] The limiter 740 is connected to the proportional-integral controller 730 and receives the theoretical current I output by the proportional-integral controller 730. S The output end of the limiter 740 is connected to the control device 720. The limiter 740 may have an upper limit current I Lim and lower limit current -I Lim . Then when -ILim S Lim When the limiter 740 outputs the theoretical current I S As the limiting current I set ; when I S ≥I Lim When the limiter 740 outputs the upper limit current I Lim As the limiting current I set ; when I S ≤-I Lim When the limiter 740 outputs the lower limit current -I Lim As the limiting current I set .

[0132] Further, the control device 720 is configured to: solve To calculate the optimal solution of φ2 and φ3.

[0133] Among them, i max (φ2, φ3) is the expression of the maximum current, I set is the output current of the limiter 740, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, V1, V2 and V3 are the real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 is the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit, and φ3 is the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit.

[0134] The amplitude of the upper and lower current limits I Lim The value may be set based on the magnitude of the maximum safe current of the three-port converter circuit, such as being set to the maximum safe current, or being set to a value slightly smaller than the magnitude of the maximum safe current.

[0135] Mathematical optimization problems The solution process is as described above and will not be repeated here.

[0136] In a specific embodiment, the control device 720 is further configured to: Calculate the theoretical values ​​of φ2 and φ3 2set and φ 3set ; In response to use Calculate the execution values ​​of φ2 and φ3; or in response to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or in response to use Calculating execution values ​​of φ2 and φ3; and determining the execution values ​​of φ2 and φ3 as the optimal solution. ​​

[0137] in, k3=2(Z1Z2+Z1Z3+Z2Z3), k4, k5 and k6 are the maximum current i determined in this round of fast start mode xy The calculated values ​​of the corresponding expressions in Table 1.

[0138] Preferably, after determining the execution values ​​of φ2 and φ3, the control device 720 can generate corresponding switch opening control signals for the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, and output the first PWM control signal, the second PWM signal and the third PWM signal to the switch tube of the first full-bridge circuit, the switch tube of the second full-bridge circuit and the switch tube of the third full-bridge circuit respectively to control the forward conduction or reverse conduction of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit.

[0139] Among them, PWM2(ωt+φ2)=PWM1(ωt), PWM3(ωt+φ3)=PWM1(ωt).

[0140] Among them, PWM1 refers to the PWM control signal of the first full-bridge circuit, PWM2 refers to the PWM control signal of the second full-bridge circuit, and PWM3 refers to the PWM control signal of the third full-bridge circuit.

[0141] Optionally, in other embodiments, the proportional-integral controller 730 may also use other controllers such as a proportional-integral-derivative controller (PID) to achieve the same function.

[0142] According to yet another aspect of the present invention, an energy storage device is provided.

[0143] Figure 8 FIG. 2 shows a structural block diagram of an energy storage device in an embodiment. Figure 8 As shown, the energy storage device includes a three-port converter circuit 810 and a start-up device 820 connected to the three-port converter circuit.

[0144] Among them, the three-port converter circuit 810 can be used Figure 1 The three-port converter circuit structure shown or its variant circuit.

[0145] The startup device 820 is used to control the three-port converter circuit 810 to implement the startup control method described in any of the above embodiments.

[0146] In a specific embodiment, the starting device 820 can be used Figure 7 The starting device shown or other starting devices that enable the three-port converter circuit to implement the aforementioned starting control method.

[0147] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, boxes, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician can implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0148] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0149] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0150] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0151] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. However, it should be understood that the scope of protection of the present invention shall be subject to the appended claims and shall not be limited to the specific structures and components of the above-described embodiments. Those skilled in the art may make various changes and modifications to the embodiments within the spirit and scope of the present invention, and these changes and modifications also fall within the scope of protection of the present invention.

Claims

1. A startup control method for a three-port converter circuit, the three-port converter circuit comprising three full-bridge circuits, three inductors and a three-port transformer, the first port of each full-bridge circuit being coupled to one of the coupling ends of the three-port transformer through one of the three inductors, wherein: The second end of the first full-bridge circuit and the second end of the second full-bridge circuit constitute the first power input end and the second power input end respectively, and the second end of the third full-bridge circuit constitutes the load end, and the load end is connected in parallel with the load and the voltage stabilizing capacitor, wherein the startup control method comprises: The real-time voltage of the second end of the three full-bridge circuits is collected, and in response to the real-time voltage of the load end being less than the preset voltage, the Nth round of quick start mode is started. In the Nth round of quick start mode, Determine an expression for the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of the fast start-up mode and the real-time voltage of the second end of the three full-bridge circuits, where N is a positive integer; and Based on the real-time voltage at the second end of the three full-bridge circuits and the expression of the maximum current, a mathematical optimization method is used to calculate the optimal solution of the switch-on phase difference between the three full-bridge circuits. The optimal solution is a switch-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end. The switch-on phase difference between the three full-bridge circuits is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

2. The startup control method according to claim 1, characterized in that: The expression for determining the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of the fast start mode and the real-time voltage of the second end of the three full-bridge circuits includes: According to the current symmetry in the three-port converter circuit, Calculate the current values ​​of all inflection points of the three inductors, where i xy represents the current of the xth inductor at the yth inflection point, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit respectively determined in the N-1th round of fast start-up mode, k4, k5 and k6 are shown in the following table, ， Wherein, V1, V2 and V3 are real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively; and The current values ​​of all the inflection points of the three inductors are compared, and the calculation formula corresponding to the maximum current value is determined as the expression of the maximum current.

3. The startup control method according to claim 2, characterized in that: The expression for determining the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of the fast start-up mode and the real-time voltage of the second end of the three full-bridge circuits also includes: When N=1, φ2 and φ3 are initialized to 0 when determining the expression of the maximum current.

4. The startup control method according to claim 1, characterized in that: The method of using a mathematical optimization method to calculate the optimal solution for the switch-on phase difference between the three full-bridge circuits comprises: Calculating a theoretical current of the load end based on the real-time voltage of the load end and a reference voltage; Determining a smaller value between the theoretical current and the preset current as a limiting current; and Solving mathematical optimization problems To calculate the optimal solution of φ2 and φ3, where i max (φ2, φ3) is the expression of the maximum current, I set is the limiting current, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively, V1, V2 and V3 are the real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, respectively.

5. The startup control method according to claim 4, characterized in that: Solving the mathematical optimization problem The optimal solutions to calculate φ2 and φ3 include: Will Convert to KKT conditions and solve to obtain the optimal solution of φ2 and φ3.

6. The startup control method according to claim 4, characterized in that: Solving the mathematical optimization problem The optimal solutions to calculate φ2 and φ3 include: use Calculate the theoretical values ​​of φ2 and φ3 2set and φ 3set ,in, k3=2(Z1Z2+Z1Z3+Z2Z3), k4, k5 and k6 are the maximum current i determined in this round of fast start mode xy The calculated values ​​of the corresponding expressions in the following table are: ， Table i xy represents the current of the xth inductor at the yth inflection point; In response to use Calculate the execution values ​​of φ2 and φ3; or In response to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or In response to use Calculating execution values ​​of φ2 and φ3; and determining the execution values ​​of φ2 and φ3 as the optimal solution.

7. The startup control method according to claim 4, characterized in that: Calculating the theoretical current of the load end based on the real-time voltage of the load end and the reference voltage includes: The theoretical current is determined by using a proportional-integral control algorithm based on the real-time voltage of the load and the reference voltage of the load.

8. The startup control method according to any one of claims 1 to 7, wherein the switch-on phase difference comprises a first switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and a second switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, wherein: Also includes: Initializing and setting a first PWM control signal of the first full-bridge circuit; Setting the PWM control signal of the second full-bridge circuit to a second PWM signal that is delayed from the first PWM control signal by a phase difference of the first switch on; and The PWM control signal of the third full-bridge circuit is set to be a second PWM signal delayed from the first PWM control signal by a phase difference of the second switch turn-on.

9. A starting device for a three-port converter circuit, the three-port converter circuit comprising three full-bridge circuits, three inductors and a three-port transformer, the first port of each full-bridge circuit being coupled to one of the coupling ends of the three-port transformer via one of the three inductors, wherein: The second end of the first full-bridge circuit and the second end of the second full-bridge circuit constitute the first power input end and the second power input end respectively, the second end of the third full-bridge circuit constitutes the load end, the load end is connected in parallel with the load and the voltage stabilizing capacitor, and the starting device includes a collection device and a control device connected to the collection device, the collection device is used to collect the real-time voltage of the second ends of the three full-bridge circuits, The control device is configured to: in response to the real-time voltage at the load end being less than a preset voltage, start the Nth round of quick start mode, in the Nth round of quick start mode, the control device determines an expression of the maximum current appearing in the three inductors based on the switch turn-on phase difference determined in the N-1th round of quick start mode and the real-time voltage at the second end of the three full-bridge circuits, N is a positive integer, and based on the real-time voltage at the second end of the three full-bridge circuits and the expression of the maximum current, calculate the optimal solution of the switch turn-on phase difference between the three full-bridge circuits using a mathematical optimization method, the optimal solution being a switch turn-on phase difference that makes all currents in the three-port converter circuit within a safe range and maximizes the power at the load end, and the switch turn-on phase difference between the three full-bridge circuits is used to indicate the phase difference of the switch control signals of the three full-bridge circuits.

10. The starting device according to claim 9, characterized in that It also includes a proportional-integral controller and a limiter, wherein the proportional-integral controller is connected to the acquisition device to obtain the real-time voltage of the load end, and the proportional-integral controller is connected to the control device through the limiter. The proportional-integral controller calculates the theoretical current of the load end based on the reference voltage and the real-time voltage of the load end and outputs the theoretical current to the limiter. In response to the theoretical current being less than the upper limit current and greater than the lower limit current, the limiter outputs the theoretical current to the control device, In response to the theoretical current being greater than or equal to the upper limit current, the limiter outputs the upper limit current to the control device, In response to the theoretical current being less than or equal to the lower limit current, the limiter outputs the lower limit current to the control device, The control device is further configured to: Solution To calculate the optimal solution of φ2 and φ3, where i max (φ2, φ3) is the expression of the maximum current, I set is the output current of the limiter, Z1, Z2 and Z3 are the impedances of the inductors connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively, V1, V2 and V3 are the real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit, respectively, φ2 and φ3 are the switch-on phase difference between the first full-bridge circuit and the second full-bridge circuit and the switch-on phase difference between the first full-bridge circuit and the third full-bridge circuit, respectively.

11. A startup control device for a three-port converter circuit, comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor is used to implement the steps of the startup control method of the three-port converter circuit according to any one of claims 1 to 8 when executing the computer program stored in the memory.

12. An energy storage device, characterized in that: The invention comprises a three-port converter circuit and a start-up device connected to the three-port converter circuit, wherein the start-up device is used to control the three-port converter circuit to implement the start-up control method according to any one of claims 1 to 8.

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