A start-up control method for a three-port converter circuit and apparatus therefor

Abstract

The application provides a starting control method and device of a three-port converter circuit. The starting control method comprises: collecting real-time voltages of the second ends of three full-bridge circuits; in response to the real-time voltage of the load end being less than a preset voltage, starting the Nth round of fast starting mode; in the Nth round of fast starting mode, determining an expression of the maximum current appearing in the three inductors based on the switching on phase difference determined in the (N-1)th round of fast starting mode and the real-time voltage of the second end of the three full-bridge circuits, wherein N is a positive integer; and based on the real-time voltage of the second end of the three full-bridge circuits and the expression of the maximum current, calculating the optimal solution of the switching on phase difference among the three full-bridge circuits by using a mathematical optimization method, wherein the optimal solution is the switching on phase difference that makes all the currents in the three-port converter circuit within a safe range and makes the power of the load end maximum. Thus, the three-port converter circuit can quickly reach a stable state in a safe state.

Description

Technical Field

[0001] This invention relates to the field of power electronics, and more particularly to a startup control method and apparatus for a three-port converter circuit. Background Technology

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

[0003] With the continuous advancement of industry technology, the market has created an urgent demand for power electronic converters with higher integration and greater power density. Against this backdrop, three-port converter (TPC) technology has emerged. Thanks to its simple structural design, low-loss characteristics during system operation, and high flexibility in energy flow, it plays a crucial role in DC microgrid systems, injecting new vitality into the future development of the industry. Three-port converters are typically used to achieve energy transfer and management between different voltage levels. Their main functions include the conversion, regulation, and distribution of electrical energy, making them suitable for various application scenarios such as renewable energy systems, energy storage systems, and electric vehicles. They generally have three ports, each of which can be connected to a different power source or load. For example, one port can be connected to the grid, one port to an energy storage battery or photovoltaic unit, and the remaining port to the load.

[0004] Figure 1 A schematic diagram of the circuit structure of a commonly used three-port converter in the prior art is shown, such as... 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, typically consisting of four switching transistors (such as transistors, MOSFETs, IGBTs, etc.). These four transistors are divided into two pairs, and the two pairs of switches alternately conduct to switch and regulate the positive and negative polarities of voltage and current. One end of full-bridge circuit B1 is connected to power supply V1, and the other end is connected to one coupling terminal of three-port transformer T1 through inductor L1. The number of turns of the coil at this coupling terminal is n1. Full-bridge circuit B1 includes a switching transistor Q. 11 Q 12 Q 13 and Q 14 Q 11 and Q 13 The positive switching pair Q that constitutes the full-bridge circuit B1 12 and Q 14 The reverse switching 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 terminal of the three-port transformer T1 through the inductor L2. The number of turns of the coil at this coupling terminal is n2. The full-bridge circuit B2 includes the switching transistor Q. 21 Q22 Q 23 and Q 24 Q 21 and Q 23 The positive switching pair Q that constitutes the full-bridge circuit B2 22 and Q 24 The reverse switching 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 terminal of the three-port transformer T1 through the inductor L3. The number of turns of the coil at this coupling terminal is n3. The full-bridge circuit B3 includes the switching transistor Q. 31 Q 32 Q 33 and Q 34 Q 31 and Q 33 The positive switching pair Q that constitutes the full-bridge circuit B3 32 and Q 34 The reverse switching pair that constitutes the full-bridge circuit B3, and the load R3 also has a voltage-regulating capacitor C3 connected in parallel.

[0005] by Figure 1 Taking the three-port converter circuit shown as an example, during startup, the Zener capacitor C3 at the load port R3 has no stored charge, effectively creating a short circuit. This results in a large current during startup, which can easily damage the switching elements and cause significant losses, reducing system efficiency. To protect the switching elements of the three-port converter circuit while improving efficiency to ensure power density, appropriate soft-start strategies need to be studied to limit the maximum current during startup. Furthermore, to improve system power, rapid startup should be considered as much as possible within a safe range. Summary of the Invention

[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0007] To improve the safety and power of a three-port converter circuit during startup, this invention aims to provide a startup control method, apparatus, device, 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. 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 coupling terminal of the three-port transformer through one of the three inductors. The second terminals of the first and second full-bridge circuits respectively constitute a first power input terminal and a second power input terminal. The second terminal of the third full-bridge circuit constitutes a load terminal. The load terminal is connected in parallel with a load and a voltage regulator capacitor. The startup control method includes: acquiring the real-time voltage of the second terminals of the three full-bridge circuits; and, in response to the real-time voltage of the load terminal being less than a preset voltage, initiating the Nth round of rapid startup. In the dynamic mode, under the Nth round of fast start-up mode, based on the switch turn-on phase difference determined in the (N-1)th round of fast start-up mode and the real-time voltage at the second terminal of the three full-bridge circuits, the expression for the maximum current appearing in the three inductors is determined, where N is a positive integer; and based on the expressions for the real-time voltage at the second terminal of the three full-bridge circuits and the maximum current, the optimal solution for the switch turn-on phase difference between the three full-bridge circuits is calculated using a mathematical optimization method. The optimal solution is the switch turn-on phase difference that keeps 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-on phase difference determined in the (N-1)th round of fast start-up mode and the real-time voltage at the second terminal of the three full-bridge circuits includes: utilizing the current symmetry in the three-port converter circuit, Calculate the current values ​​at all inflection points of the three inductors. Where i xy Let represent the current of the x-th inductor at the y-th inflection point. Z1, Z2, and Z3 are the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively. φ2 and φ3 are the switching phase differences between the first and second full-bridge circuits and between the first and third full-bridge circuits, respectively, determined in the (N-1)th round of fast start mode. k4, k5, and k6 are shown in the table below.

[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] Where V1, V2, and V3 are the real-time voltages at the second terminals of the first, second, and third full-bridge circuits, respectively; and the formula corresponding to the maximum current value is determined by comparing the current values ​​at all inflection points of the three inductors.

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

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

[0014] In one embodiment, the solution The calculation of the optimal solutions for φ2 and φ3 includes: The conditions are transformed into KKT conditions and solved to obtain the optimal solutions for φ2 and φ3.

[0015] In one embodiment, the solution The optimal solutions for φ2 and φ3 are calculated by using: Calculate the theoretical values ​​φ2 and φ3. 2set and φ 3set ; in response use Calculate the execution values ​​of φ2 and φ3; or respond to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or respond to use Calculate the execution values ​​of φ2 and φ3; and determine the execution values ​​of φ2 and φ3 as the optimal solution. Among these, k3 = 2(Z1Z2 + Z1Z3 + Z2Z3), k4, k5, and k6 are the maximum currents i determined in this round of rapid start-up mode. xy The calculated values ​​of the expressions corresponding to the following table are:

[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] In the table i xyThis represents the current at the y-th inductor's inflection point.

[0018] In one embodiment, calculating the theoretical current at the load end based on the real-time voltage and reference voltage at the load end 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. The start-up control method further includes: initializing and setting a first PWM control signal for the first full-bridge circuit; setting the PWM control signal for the second full-bridge circuit to a second PWM signal that is delayed by the first PWM control signal by the first switch-on phase difference; and setting the PWM control signal for the third full-bridge circuit to a second PWM signal that is delayed by the first PWM control signal by the second switch-on phase difference.

[0020] According to another aspect of the present invention, a startup 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 coupling terminal of the three-port transformer through one of the three inductors. The second terminals of the first and second full-bridge circuits respectively constitute a first power input terminal and a second power input terminal. The second terminal of the third full-bridge circuit constitutes a load terminal. The load terminal is connected in parallel with a load and a voltage regulator capacitor. The startup device includes a data acquisition device and a control device connected to the data acquisition device. The data acquisition device is used to acquire the real-time voltage of the second terminals of the three full-bridge circuits. The control device is configured to: respond to a small change in the real-time voltage of the load terminal... At a preset voltage, the Nth round of fast start mode is activated. In the Nth round of fast start mode, the control device determines the expression for the maximum current in the three inductors based on the switch turn-on phase difference determined in the (N-1)th round of fast start mode and the real-time voltage at the second terminal of the three full-bridge circuits. N is a positive integer. Based on the real-time voltage at the second terminal of the three full-bridge circuits and the expression for the maximum current, the optimal solution for the switch turn-on phase difference between the three full-bridge circuits is calculated using a mathematical optimization method. The optimal solution is the switch turn-on phase difference that keeps 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: utilize the current symmetry in the three-port converter circuit to... Calculate the current values ​​at all inflection points of the three inductors; compare the current values ​​at all inflection points of the three inductors, and determine the formula corresponding to the maximum current value as the expression for the maximum current. Where i xy Let represent the current of the x-th inductor at the y-th inflection point. Z1, Z2, and Z3 are the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively. φ2 and φ3 are the switching phase differences between the first and second full-bridge circuits and between the first and third full-bridge circuits, respectively, determined in the (N-1)th round of fast start mode. k4, k5, and k6 are shown in the table below.

[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] Where V1, V2, and V3 are the real-time voltages at the second terminals 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 initialize φ2 and φ3 to 0 when determining the expression for the maximum current, when N=1.

[0025] In one embodiment, the starting device further includes a proportional-integral (PI) controller and a limiter. The PI controller is connected to the acquisition device to obtain the real-time voltage at the load end. The PI controller is connected to the control device via the limiter. The PI 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 but 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 solutions for φ2 and φ3, where i max (φ2,φ3) is the expression for the maximum current, I set Z1, Z2, and Z3 are the output current of the limiter, respectively. Z1, Z2, and Z3 are the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively. V1, V2, and V3 are the real-time voltages at the second terminals of the first, second, and third full-bridge circuits, respectively. φ2 and φ3 are the switching phase differences between the first and second full-bridge circuits and between the first and third full-bridge circuits, respectively.

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

[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] In the table i xy This represents the current at the y-th inductor's inflection point.

[0029] In any of the foregoing 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. 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 for the second full-bridge circuit to a second PWM signal that is delayed by the first PWM control signal by the first switch-on phase difference; set the PWM control signal for the third full-bridge circuit to a third PWM signal that is delayed by the first PWM control signal by the second switch-on phase difference; and output the first PWM control signal, the second PWM signal, and the third PWM signal to the switches of the first full-bridge circuit, the second full-bridge circuit, and 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 conduct forward or reverse.

[0030] According to another invention of the present invention, a startup control device for a three-port converter circuit is also disclosed, comprising a memory, a processor, and a computer program stored in the memory, wherein 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 foregoing embodiments.

[0031] According to yet 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 being used to control the three-port converter circuit to implement the starting control method as described in any of the foregoing embodiments. Attached Figure Description

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

[0033] Figure 1 This is a schematic diagram of the circuit structure of an exemplary three-port converter circuit drawn based on existing technology;

[0034] Figure 2 This is a flowchart illustrating a startup control method for a three-port converter circuit according to one embodiment of the present invention;

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

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

[0037] Figure 5 This is a partial flowchart illustrating a startup control method for a three-port converter circuit according to one embodiment of the present invention.

[0038] Figure 6 This is a block diagram of a start-up control device for a three-port converter circuit according to another aspect of the present invention.

[0039] Figure 7 This is a block diagram of a start-up control device for a three-port converter circuit according to another aspect of the present invention.

[0040] Figure 8 This is a block diagram of an energy storage device according to one aspect of the present invention. Detailed Implementation

[0041] The following description is provided to enable those skilled in the art to implement and use the invention and adapt it to specific application contexts. Various modifications and 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. Therefore, the 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, numerous specific details are set forth to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that practice of the invention is not necessarily limited to these specific details. In other words, well-known structures and devices are shown in block diagram form without being depicted in detail to avoid obscuring the invention.

[0043] Readers should note all documents and references submitted concurrently with this specification and open to public inspection, the contents of which are incorporated herein by reference. Unless otherwise expressly stated, all features disclosed in this specification (including any appended claims, abstracts, and drawings) may be replaced by alternative features for the same, equivalent, or similar purposes. Therefore, unless explicitly stated otherwise, each disclosed feature is merely one example of a set of equivalent or similar features.

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

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly, referring to direct connection or indirect connection through an intermediate medium, or internal connection between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] Note that, in practice, "further," "preferably," "even further," and "more preferably" are simply starting points for describing another embodiment based on the foregoing embodiments. The combination of the content following "further," "preferably," "even further," or "more preferably" with the foregoing embodiments constitutes the complete configuration of another embodiment. Any combination of several "further," "preferably," "even further," or "more preferably" settings following the same embodiment can form yet another embodiment.

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely 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 converter circuit that includes three ports and can realize the conversion, regulation and distribution of electrical energy between the three ports. Figure 1 This is a schematic diagram of a conventional three-port converter circuit in this field, with reference to... Figure 1 You can understand the basic structure of a three-port converter circuit, such as... Figure 1As shown, a three-port converter circuit typically includes three full-bridge circuits, three inductors, and one three-port transformer.

[0050] Each full-bridge circuit includes two pairs of switching transistors, which alternately switch on to convert between direct current (DC) and alternating current (AC). Each full-bridge circuit has two ports: an AC port as the first port and a DC port as the second port. One of these ports is the input, and the other is the output. Depending on the functional configuration of the full-bridge circuit, the input and output ports can be interchanged; for example, the input can be DC and the output AC, or vice versa.

[0051] The three-port transformer T1 consists of three mutually coupled ports. Figure 1 The implementation uses coils as coupling ports, with the number of coil turns for the three ports being n1, n2, and n3, respectively.

[0052] The first port (AC terminal) 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 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 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 inductor L3.

[0053] A three-port converter circuit typically has three ports, two of which serve as power input terminals and the remaining port as a load terminal. In this application, the second terminals of three full-bridge circuits constitute the three ports of the three-port converter circuit. The second terminals of the first and second full-bridge circuits are used as power input terminals to form the first and second power input terminals, respectively. The second terminal of the third full-bridge circuit serves as the load terminal, and a load and a voltage regulator capacitor are connected in parallel at the load terminal.

[0054] It is understood that in specific application scenarios, the three-port converter circuit may also include other adapted circuit functions and their corresponding devices. For example, the second terminal of the first full-bridge circuit and the second terminal of the second full-bridge circuit may also be equipped with corresponding voltage-regulating capacitors. This application only uses 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 for a three-port converter circuit is shown in a specific embodiment. Figure 2 The start-up control method shown includes steps S210 to S230.

[0056] Step S210 involves: acquiring the real-time voltage at the second terminal of the three full-bridge circuits; and, in response to the real-time voltage at the load terminal being less than the preset voltage, initiating the Nth round of fast start-up mode.

[0057] "Acquisition" broadly refers to obtaining real-time voltage through certain means, which can be from an external voltage detection device or directly by setting a voltage detection unit. The "acquisition" frequency in step S210 can be set based on the acquisition frequency supported by the acquisition device, the switching frequency of the full-bridge circuit, or the computing power of the computing device. For example, the minimum value among these three determined frequencies can be used as the actual acquisition accuracy. After each acquisition, the real-time voltage at the load end is compared with a preset voltage to determine whether to activate the fast start mode. The frequency set based on the computing power of the computing device refers to the reciprocal of the time required to complete one round of fast start mode. It can be understood that within this time, even if multiple real-time voltage acquisitions are made, 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 based on the steady-state voltage across 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 regulator capacitor C3 remains unchanged, effectively making capacitor C3 an open circuit. The voltage across load R3 remains stable; this voltage is the steady-state voltage. Preferably, the preset voltage can be set to 80% or more of the steady-state voltage. This generally means that when the real-time voltage at the load end reaches this preset voltage value, the voltage regulator capacitor in the third full-bridge circuit has stored a certain amount of charge. As the load voltage continues to rise, the current in the third full-bridge circuit will no longer damage the switching elements.

[0059] It is understood that step S210 is a cyclic step, and it will be continuously executed as long as the voltage across the load has not yet reached the preset voltage. If the voltage across the load reaches the preset voltage, the fast start mode will not be activated, and the control mode when the three-port converter circuit is in a stable state can be entered as needed. This application does not limit the control mode in the stable state.

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

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

[0062] Figure 3A schematic diagram of the voltage waveform at the midpoint of the bridge arm of a three-port converter circuit is shown. Figure 1 Taking the full-bridge circuit B1 shown as an example, the voltage at the midpoint of the bridge arm refers to the voltage across the switching transistor Q. 11 and Q 13 Connection point and switching transistor Q 12 and Q 14 The voltage difference between the connection points. Figure 3 The horizontal axis represents phase, and the vertical axis represents the voltage difference at the midpoint of any full-bridge arm (i.e., the voltage difference at the first terminal of any full-bridge circuit). When the forward switch pair of a full-bridge circuit is on and the reverse switch pair is off, the voltage at the first terminal of the full-bridge circuit is positive; when the reverse switch pair of a full-bridge circuit is on and the forward switch pair is off, the voltage at the first terminal of the full-bridge circuit is negative. For example... Figure 3 As shown, assuming the forward turn-on start phase of the first full-bridge circuit is θ0, the reverse turn-on start phase of the first full-bridge circuit is θ3, the forward turn-on start phase of the second full-bridge circuit is θ1, and the forward turn-on start phase of the third full-bridge circuit is θ2, then the phase difference φ2 between θ0 and θ1 is the switching conduction phase difference between the first and second full-bridge circuits, and the phase difference φ3 between θ0 and θ2 is the switching conduction phase difference between the first and third full-bridge circuits. The reverse turn-on start phases of the second and third full-bridge circuits can be calculated based on the period of the PWM control signal of the switching transistors and are not marked further.

[0063] Figure 4 This diagram illustrates the voltage and current curves across the inductors connected in a full-bridge circuit. Specifically, it shows the current variation trend of the inductors (L1 / L2 / L3) in a three-port transformer circuit as follows: Figure 4 curve i in Lx As shown, the voltage change trend of the inductors (L1 / L2 / L3) is as follows: Figure 4 curve V in Lx As shown. Combined with Figure 4 It can be seen that there is a corresponding relationship between the voltage and current of each inductor, so the corresponding current curve can be determined based on 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 is identified as i xy The form is: 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), 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 is understandable that, to improve the safety of the three-port converter circuit, it is necessary to ensure that the maximum current in the circuit remains within the safe current range of the three-port converter circuit. Therefore, in any round of fast start-up mode, it is necessary to determine the inductor where the maximum current occurs in the circuit and its inflection point. Since the phase shift angle changes continuously throughout the start-up process, the value of the current at each inflection point in the current control cycle can be predicted by using the value of the phase shift angle in the previous control cycle.

[0066] Specifically, step S220 can be refined as follows: based on the current symmetry in the three-port converter circuit, substitute the switch-on phase difference determined in the (N-1)th round of fast start mode and the real-time voltage of the second terminal of the three full-bridge circuits into the calculation to determine the current value 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.

[0067] In the first round of fast start mode, when N=1, the switch turn-on phase differences φ2 and φ3 determined in the (N-1)th round can be set to 0, which is to initialize the switch turn-on phase difference value for the first round of fast start mode.

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

[0069]

[0070] Where Z1, Z2, and Z3 are the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively; when N = 1, φ2 and φ3 are 0; when N ≠ 1, φ2 and φ3 are the switching phase differences between the first and second full-bridge circuits and between the first and third full-bridge circuits, as determined by the N-1 round fast start mode; k4, k5, and k6 are coefficients corresponding to the inductors and inflection points. According to the current symmetry in the three-port converter circuit, k4, k5, and k6 can be represented by the real-time voltages at the second terminals of the three full-bridge circuits and the impedances of the inductors, 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] In Table 1, Z1, Z2, and Z3 represent the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively. In Table 1, V1, V2, and V3 represent the real-time voltages at the first terminals of the first, second, and third full-bridge circuits, respectively.

[0074] It is understandable that the impedance of the inductors connected to the three full-bridge circuits is a fixed value. After the real-time voltage of the second terminal of the three full-bridge circuits is obtained, k4, k5 and k6 in the current expression of each inductor at each inflection point can be calculated. Therefore, in each round of fast start mode, by substituting φ2 and φ3 of the previous round and the real-time voltage of the second terminal of the three full-bridge circuits into equation (1), the specific value of the current at each inflection point of each inductor can be calculated. 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 occurs can be determined. The current expression of the corresponding inflection point of the inductor where the maximum current occurs is determined as the maximum current expression. It is understandable 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 fast start mode, so they are still represented by the unknown parameters φ2 and φ3, while k4, k5 and k6 are represented by the specific values ​​obtained by looking up the table and calculation. That is, the maximum current expression contains only the unknown parameters φ2 and φ3.

[0075] Further, step S230 is as follows: Based on the expressions for the real-time voltage and maximum current at the second terminal of the three full-bridge circuits, the optimal solution for the switching turn-on phase difference between the three full-bridge circuits is calculated using a mathematical optimization method. The optimal solution is the switching 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 switching turn-on phase difference is used to indicate the phase difference of the switching control signals of the three full-bridge circuits.

[0076] It is understandable that when the maximum current is within the safe range, the current at any point in the three-port converter circuit is within the safe range. Furthermore, 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 relationship between the theoretical current and the preset current.

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

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

[0079] It should be noted that the proportional-integral control algorithm can ensure the accuracy of the theoretical current calculation without wasting too much computing power. Without considering resource waste, those skilled in the art can also use other existing or future calculation methods that can calculate the corresponding current based on real-time voltage, such as the 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. It can be set to the maximum safe current, or the amplitude can be set to a value slightly smaller than the maximum safe current. Then, the amplitudes of the theoretical load current and the preset current can be compared, and the smaller amplitude is determined as the limiting current I. set It is understandable that the limiting current has positive and negative values, and the positive and negative values ​​of the theoretical current are determined as the positive and negative values ​​of the limiting current.

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

[0082]

[0083] The constraint on the phase difference of the switch opening can be expressed as the mathematical optimization problem shown in equation (3).

[0084]

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

[0086] The optimization problem shown in equation (3) can be transformed into KKT conditions (Karush-Kuhn-Tucker conditions, commonly known as Kuhn-Tucker, Karush-Kuhn-Tucker optimization conditions, Karush-Kuhn-Tucker conditions, Kuhn-Tucker optimization conditions, Kuhn-Tucker conditions).

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

[0088] In one specific embodiment, the solution obtained by transforming equation (3) to the KKT conditions is the following equation (4):

[0089]

[0090] Where, φ 2set and φ 3set These refer to the theoretical values ​​of φ2 and φ3 obtained through solving, respectively. k3 = 2(Z1Z2 + Z1Z3 + Z2Z3), k4, k5, and k6 are the maximum currents i determined in this round of rapid start-up mode. xy The calculated values ​​of the corresponding expressions in Table 1.

[0091] Then, when the calculated φ 2set and φ 3set Satisfaction At that time, the execution values ​​of φ2 and φ3 are respectively equal to φ 2set and φ 3set .

[0092] When φ 2set and φ 3set Any one of them does not satisfy the constraint condition of equation (3) When the phase difference φ between the switches that do not meet the requirements can be turned on, the switch can be activated. 2set or φ 3set Set 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 equation (1), as shown in equation (5); when When φ3 is set to π / 2, the execution value of φ2 can be calculated using equation (1), as shown in equation (6).

[0094]

[0095]

[0096] In summary, φ is determined by equation (4). 2set and φ 3set Then, based on φ 2set and φ 3set The distribution intervals determine the execution values ​​of φ2 and φ3, which are summarized in the following formula (7):

[0097]

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

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

[0100] Figure 5 A schematic diagram illustrating the steps of generating a switch-on control signal in one embodiment is shown. Figure 5 As shown, in this embodiment, after determining the execution values ​​of φ2 and φ3, steps S510 to S530 may also be included.

[0101] Step S510 involves initializing and setting the first PWM control signal of the first full-bridge circuit.

[0102] During one switching cycle, when the PWM control signal is positive, the forward switch is turned on and the reverse switch is turned off; when the PWM control signal is negative, the forward switch is turned off and the reverse switch 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 the first PWM control signal by the phase difference of the first switch being turned on.

[0104] That is, PWM2(ωt+φ2)=PWM1(ωt), where 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 the second switch turn-on phase difference from the first PWM control signal.

[0106] That is, PWM3(ωt+φ3)=PWM1(ωt), where 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 methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

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

[0109] Figure 6 A startup control device 600 for a three-port converter circuit in a specific embodiment is shown. For example... 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 a computer program stored in the memory 610. When the processor 620 executes the computer program, it implements the steps of the startup control method for the three-port converter circuit in any of the foregoing embodiments.

[0112] According to another aspect of the invention, a method suitable for Figure 1 The starting device for the three-port converter circuit shown.

[0113] in, Figure 1 The three-port converter circuit shown is described in the previous section on the startup control method of the three-port converter circuit, and will not be repeated here.

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

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

[0116] The acquisition device 710 can be an existing or future device capable of acquiring 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 acquisition frequency supported by the acquisition device, the switching frequency of the full-bridge circuit, or the computing power of the computing device. For example, the minimum value among the frequencies determined based on these three factors 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 one round of fast start mode.

[0118] Optionally, the actual acquisition frequency of the acquisition device 710 can be the acquisition frequency set by the device, but the frequency at which the real-time voltage is output to the control device 720 or the frequency at which the control device 720 obtains the real-time voltage from the acquisition device 710 can be set based on the acquisition frequency supported by the acquisition device, the switching 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 acquire the real-time voltage of the second terminal of three full-bridge circuits respectively, and the acquisition start signal of the three sub-devices is 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 activate the Nth round of fast start-up mode in response to a real-time voltage at the load end being less than a preset voltage. In the Nth round of fast start-up mode, the control device 720 determines an expression for the maximum current appearing in the three inductors based on the switch-on phase difference determined in the (N-1)th round of fast start-up mode and the real-time voltage at the second terminals of the three full-bridge circuits, where N is a positive integer. Based on the expressions for the real-time voltage at the second terminals of the three full-bridge circuits and the maximum current, the control device 720 calculates the optimal solution for the switch-on phase difference between the three full-bridge circuits using a mathematical optimization method. The optimal solution is the switch-on phase difference that keeps 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 for the three full-bridge circuits.

[0121] The preset voltage can be set based on the steady-state voltage across 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 regulator capacitor C3 remains unchanged, effectively making capacitor C3 an open circuit. The voltage across load R3 remains stable; this voltage is the steady-state voltage. Preferably, the preset voltage can be set to 80% or more of the steady-state voltage. This generally means that when the real-time voltage at the load end reaches this preset voltage value, the voltage regulator capacitor in the third full-bridge circuit has stored a certain amount of charge. As the load voltage continues to rise, the current in the third full-bridge circuit will no longer damage the switching elements.

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

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

[0124] Specifically, to determine the expression for the maximum current, the control device 720 is further configured to: utilize the current symmetry in the three-port converter circuit, Calculate the current values ​​at all inflection points of the three inductors; compare the current values ​​at all inflection points of the three inductors, and determine the formula corresponding to the maximum current value as the expression for the maximum current.

[0125] Among them, i xyLet represent the current of the x-th inductor at the y-th inflection point. Z1, Z2, and Z3 are the impedances of the inductors connected to the first, second, and third full-bridge circuits, respectively. φ2 and φ3 are the switching phase differences between the first and second full-bridge circuits and between the first and third full-bridge circuits, respectively, determined in the (N-1)th round of fast start mode. k4, k5, and k6 are shown in Table 1 above.

[0126] Specifically, in the first round of fast start mode, i.e. when N=1, the control device 720 initializes the switch-on phase differences φ2 and φ3 calculated in the first round to 0.

[0127] It is understandable that the impedance of the inductors connected to the three full-bridge circuits is a fixed value. Once the real-time voltage at the second terminal of the three full-bridge circuits is obtained, k4, k5, and k6 in the current expression for each inductor at each inflection point can be calculated. Therefore, in each round of fast start-up mode, φ2 and φ3 from the previous round, as well as the real-time voltage at the second terminal of the three full-bridge circuits, are substituted into... In this way, the specific value of the current at each inflection point of each inductor can be calculated.

[0128] By comparing the specific values ​​of the nine currents at the three inflection points of the three inductors, the inductor and its inflection point where the maximum current occurs can be determined. The current expression for the corresponding inflection point of the inductor where the maximum current occurs is then defined as the maximum current expression. It can be understood that during the comparison process, φ2 and φ3 are replaced by the phase difference from the previous round; in the maximum current expression, φ2 and φ3 refer to the control phase difference that needs to be determined for this round of rapid start-up mode, and therefore are still represented by the unknown parameters φ2 and φ3. k4, k5, and k6 are represented by specific values ​​obtained through table lookup and calculation. That is, the maximum current expression contains only the unknown parameters φ2 and φ3.

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

[0130] The proportional-integral (PI) controller 730 is connected to the data acquisition device 710 to obtain the real-time voltage V3 at the load terminal. The PI controller 730 is based on the reference voltage V at the load terminal. ref And the theoretical current I at the load terminal is calculated from the real-time voltage V3. 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 of limiter 740 is connected to control device 720. Limiter 740 may have an upper limit current I. Lim and lower limit current -I Lim Then when -ILim S Lim At that time, the limiter 740 outputs the theoretical current I. S As the limiting current I set ; when I S ≥I Lim At that time, the limiter 740 outputs the upper limit current I. Lim As the limiting current I set ; when I S ≤-I Lim At that time, the limiter 740 outputs the lower limit current -I. Lim As the limiting current I set .

[0132] Furthermore, the control device 720 is configured to: solve The optimal solutions for φ2 and φ3 are calculated.

[0133] Among them, i max (φ2,φ3) is the expression for the maximum current, I set φ1 is the output current of 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 terminals of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, φ2 is the switching phase difference between the first full-bridge circuit and the second full-bridge circuit, and φ3 is the switching phase difference between the first full-bridge circuit and the third full-bridge circuit.

[0134] The amplitude I of the upper limit current and the lower limit current Lim It can be set based on the amplitude of the maximum safe current of the three-port converter circuit, such as setting it to the maximum safe current, or setting the amplitude to a value slightly smaller than the maximum safe current.

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

[0136] In one specific embodiment, the control device 720 is further configured to: utilize Calculate the theoretical values ​​φ2 and φ3. 2set and φ 3set ; in response use Calculate the execution values ​​of φ2 and φ3; or respond to φ 2set ≤0, use Calculate the execution values ​​of φ2 and φ3; or respond to use Calculate the execution values ​​of φ2 and φ3; and determine 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 currents i determined in this round of rapid start-up 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-on 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 transistors of the first full-bridge circuit, the second full-bridge circuit, and 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 conduct forward or reverse.

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

[0140] Wherein, 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] Alternatively, in other embodiments, the proportional-integral controller 730 may also employ other controllers such as a proportional-integral-derivative (PID) controller to achieve the same function.

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

[0143] Figure 8 A structural block diagram of an energy storage device according to one embodiment is shown. Figure 8 As shown, the energy storage device includes a three-port converter circuit 810 and a starting device 820 connected to the three-port converter circuit.

[0144] The three-port converter circuit 810 can be adopted. Figure 1 The circuit structure of the three-port converter or its variants is shown.

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

[0146] In a specific embodiment, the starting device 820 may employ... Figure 7 The start-up device shown or other start-up device that enables the three-port converter circuit to implement the aforementioned start-up 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 both. To clearly illustrate this hardware-software interchangeability, the various illustrative components, blocks, modules, circuits, and steps are described above in a generalized manner 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. Those skilled in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be construed as departing from the scope of the invention.

[0148] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or performed using 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. The general-purpose processor may be a microprocessor, but in alternatives, it 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, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0149] The steps of the methods or algorithms 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 both. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor such that the processor can read and write information to / from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside as discrete components in the user terminal.

[0150] In one or more exemplary embodiments, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functionality may be stored or transmitted as one or more instructions or code on or through a computer-readable medium. A computer-readable medium includes both computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium accessible to a computer. By way of example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and is accessible to a computer. Any connection is also legitimately referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of a medium. As used in this article, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs. Disks typically reproduce data magnetically, while discs reproduce data optically using lasers. Combinations of these should also be included within the scope of computer-readable media.

[0151] The preceding 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 this invention should be determined by the appended claims and should not be limited to the specific structures and components of the embodiments described above. Various changes and modifications can be made to the embodiments by those skilled in the art within the spirit and scope of this invention, and these changes and modifications also fall within the scope of protection of this invention.

Claims

1. A start-up control method of a three-port converter circuit, the three-port converter circuit comprising three full-bridge circuits, three inductors and a three-port transformer, a first port of each full-bridge circuit being coupled to one of the coupled 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 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, and the load end is connected in parallel with a load and a voltage stabilizing capacitor, and the starting control method comprises: collecting real-time voltages 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 an Nth round of fast starting mode, in the Nth round of fast starting mode, according to current symmetry in the three-port converter circuit, substituting the switching on phase difference determined in the (N-1)th round of fast starting mode and the real-time voltages of the second ends of the three full-bridge circuits into calculation to determine current values of all inflection points of the three inductors, and comparing the current values of all inflection points of the three inductors, determining a calculation formula corresponding to a maximum current value as an expression of the maximum current, N being a positive integer; and based on the real-time voltages of the second ends of the three full-bridge circuits and the expression of the maximum current, using a mathematical optimization method to calculate an optimal solution of the switching on phase difference among the three full-bridge circuits, the optimal solution being a switching on phase difference that makes all currents in the three-port converter circuit within a safe range and makes the power of the load end maximum, the switching on phase difference among the three full-bridge circuits being used to indicate a phase difference of switching control signals of the three full-bridge circuits.

2. The start-up control method according to claim 1, characterized by According to current symmetry in the three-port converter circuit, substituting the switching on phase difference determined in the (N-1)th round of fast starting mode and the real-time voltages of the second ends of the three full-bridge circuits into calculation to determine current values of all inflection points of the three inductors comprises: According to the current symmetry in the three-port converter circuit, by using The current values of all the inflection points of the three inductors are calculated, wherein, 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 switching-on phase differences between the first full-bridge circuit and the second full-bridge circuit and between the first full-bridge circuit and the third full-bridge circuit determined in the N-1th round of the fast start mode, k4, k5 and k6 are shown in the following table, wherein V1, V2 and V3 are respectively real-time voltages of the second ends of the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit.

3. The start-up control method according to claim 2, characterized by According to current symmetry in the three-port converter circuit, substituting the switching on phase difference determined in the (N-1)th round of fast starting mode and the real-time voltages of the second ends of the three full-bridge circuits into calculation to determine current values of all inflection points of the three inductors further comprises: when N=1, initializing φ2 and φ3 to 0 when determining the expression of the maximum current.

4. The start-up control method according to claim 1, characterized by The using a mathematical optimization method to calculate an optimal solution of the switching on phase difference among 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 limit current as a smaller one of the theoretical current and a preset current; and Solving mathematical optimization problems to calculate optimal solutions of φ2 and φ3, where i max (φ2, φ3) is an expression of the maximum current, I set is the limit current, Z1, Z2 and Z3 are impedances of inductances connected to the first full-bridge circuit, the second full-bridge circuit and the third full-bridge circuit respectively, 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 φ2 and φ3 are switching turn-on phase differences between the first full-bridge circuit and the second full-bridge circuit and between the first full-bridge circuit and the third full-bridge circuit respectively.

5. The start-up control method according to claim 4, characterized by Solving a mathematical optimization problem comprising calculating optimal solutions for φ2 and φ3 includes: Will The conditions are transformed into KKT conditions and solved to obtain the optimal solutions for φ2 and φ3.

6. The start-up control method according to claim 4, characterized by Solving a mathematical optimization problem comprising calculating optimal solutions for φ2 and φ3 includes: By using The theoretical values φ 2set and φ 3set wherein, k3 = 2(Z1Z2 + Z1Z3 + Z2Z3), k4, k5 and k6 are the maximum currents i xy The calculated values of the expressions corresponding in the table below, Table i xy Ix,y represents the current of the xth inductor at the yth knee in response to with computing the executed values of φ2 and φ3; or In response to φ 2set ≤ 0, utilize the computed values of φ2 and φ3; or in response to with computing the execution values of φ2 and φ3; and determining the execution values of φ2 and φ3 as the optimal solution.

7. The start-up control method according to claim 4, characterized by The calculating a theoretical current of the load end based on the real-time voltage of the load end and a reference voltage comprises: determining the theoretical current 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 start-up control method according to any one of claims 1 to 7, wherein the switching-on phase difference includes a first switching-on phase difference between the first full-bridge circuit and the second full-bridge circuit and a second switching-on phase difference between the first full-bridge circuit and the third full-bridge circuit, and wherein Further comprising: initializing a first PWM control signal of the first full-bridge circuit; setting a PWM control signal of the second full-bridge circuit as a second PWM signal that is delayed from the first PWM control signal by the first switching on phase difference; and The PWM control signal of the third full-bridge circuit is set as a second PWM signal delayed from the first PWM control signal by the second switch-on phase difference.

9. A starting device of a three-port converter circuit based on a starting control method of the three-port converter circuit according to any one of claims 1 to 8, the three-port converter circuit comprising three full-bridge circuits, three inductors, and a three-port transformer, a first port of each of the full-bridge circuits being coupled to one of the coupled ends of the three-port transformer through one of the inductors, wherein, The second ends of the first full-bridge circuit and the second full-bridge circuit respectively constitute first and second power input ends, and the second end of the third full-bridge circuit constitutes a load end, and the load end is connected in parallel with a load and a voltage stabilizing capacitor, characterized in that the starting device comprises a collecting device and a control device connected with the collecting device, and the collecting device is used to collect real-time voltages 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 less than a preset voltage, start an Nth round of fast starting mode, in the Nth round of fast starting mode, according to current symmetry in the three-port converter circuit, the control device substitutes the switch-on phase difference determined in an (N-1)th round of fast starting mode and the real-time voltage of the second end of the three full-bridge circuits into calculation to determine current values of all inflection points of the three inductors, compares the current values of all inflection points of the three inductors, determines an expression of a maximum current corresponding to a maximum current value, N is a positive integer, and based on the real-time voltage of the second end of the three full-bridge circuits and the expression of the maximum current, the control device calculates an 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 that makes all currents in the three-port converter circuit within a safe range and makes power of the load end maximum, and the switch-on phase difference among the three full-bridge circuits is used to indicate a phase difference of switch control signals of the three full-bridge circuits.

10. The starting apparatus of claim 9, wherein Further comprising a proportional-integral controller and a limiter, the proportional-integral controller is connected with the collecting device to obtain the real-time voltage of the load end, and the proportional-integral controller is connected with the control device through the limiter, The proportional-integral controller calculates a theoretical current of the load end based on a reference voltage and a real-time voltage of the load end and outputs the theoretical current to the limiter, In response to the theoretical current being less than an upper limit current and greater than a 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: solving to calculate the optimal solution of φ2 and φ3, wherein, 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 switching turn-on phase differences between the first full-bridge circuit and the second full-bridge circuit and between the first full-bridge circuit and the third full-bridge circuit respectively.

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

12. An energy storage device, characterized by, The three-port converter circuit and a starting device connected with the three-port converter circuit are provided, and the starting device is used to control the three-port converter circuit to implement the starting control method according to any one of claims 1-8.

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