Non-isolated three-port converter topology and wide-range soft switching control method

Abstract

The invention discloses a non-isolated three-port converter topology and a wide-range soft switching control method. Comprising a photovoltaic cell direct current source US, an input voltage stabilization capacitor C1, an energy storage direct current source B, an energy storage voltage stabilization capacitor C2, a load resistor RL, an output voltage stabilization capacitor C3, a first switch unit K1, a second switch unit K2, a third switch unit K3, a fourth switch unit K4, a fifth switch unit K5, a sixth switch unit K6, a power inductor L1 and a power inductor L2. According to the invention, the power switch tube and the two power inductors are shared, and single-stage power conversion is adopted among the three ports, so that the advantages of high power density and high efficiency are achieved; a photovoltaic port transmits energy in a wide voltage range, voltage constraint conditions are eliminated, and the application range is expanded; and when the voltage of the photovoltaic port changes in a wide range, the working modes of the three working modes of the converter are not changed, so that the converter has a voltage self-adaptive characteristic, and the stability of the converter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic energy storage conversion, and specifically to a non-isolated three-port converter topology and a wide-range soft-switching control method. Background Art

[0002] With the increasing scarcity of traditional energy resources, photovoltaic power generation has gradually become a research and attention focus. However, photovoltaic power generation systems are affected by environmental factors such as light and temperature, and have problems of unstable power generation power and large intermittency. In order to improve the stability of photovoltaic power generation systems and increase energy utilization efficiency, energy storage devices are usually introduced into the power generation systems to achieve power balance of the power generation systems. Traditional photovoltaic power generation systems usually require multiple DC / DC converters to connect the photovoltaic port, the energy storage port, and the load port, which not only results in a large number and large volume of converters, but also reduces the system efficiency.

[0003] Due to its advantages such as high power density, high integration, and good control performance, the non-isolated three-port converter is widely used in the photovoltaic energy storage system. However, traditional non-isolated three-port converters are usually hard-switched, resulting in large switching losses. To reduce switching losses and improve the converter efficiency, soft-switching technology needs to be introduced. Although non-isolated three-port converters with soft-switching technology have been developed to some extent, there are still some problems, such as a narrow photovoltaic port voltage range and the inability of the converter to achieve full-range soft-switching after the load is increased, making it difficult to meet the requirements of the photovoltaic energy storage system for wide voltage range and stable high-efficiency operation. To solve the above problems, many improvement schemes have been proposed by research institutions and industries at home and abroad. For example, the literature "R. Faraji, L. Ding, M. Esteki, N. Mazloum and S. A. Khajehoddin, "Soft-Switched Single Inductor Single Stage Multiport Bidirectional Power Converter for Hybrid Energy Systems," IEEE Transactions on Power Electronics, vol. 36, no. 10, pp. 11298-11315, Oct. 2021." proposed a soft-switching single inductor single stage multiport bidirectional power converter. By introducing a parallel capacitor for the switching tube and using a coupled inductor to charge and discharge the parallel capacitors on different power flow paths, the soft-switching of the switching tube is achieved. While the additional auxiliary switching tube creates soft-switching conditions for other switching tubes, it can also achieve the independent soft-switching ability of the converter under no-load conditions. This scheme solves the problems faced by traditional non-isolated three-port converters to a certain extent through power path reconstruction and magnetic coupling adjustment mechanisms. Nevertheless, the voltage gain range of this converter is limited, and the number of switching tubes used is large, resulting in increased control complexity and energy loss. Therefore, it is of great significance to disclose a non-isolated three-port converter that can improve the full-load power of soft-switching by controlling the conduction timing of the switching tubes to make the two power inductors series-connected or independently used in different operating modes, and at the same time, the photovoltaic port voltage is in a wide range. Summary of the Invention

[0004] The purpose of the present invention is to provide a non-isolated three-port converter topology and a wide-range soft-switching control method to solve the problems raised in the above background technology.

[0005] To achieve the above purpose, the present invention provides the following technical solutions: A non-isolated three-port converter includes a photovoltaic cell DC source U S , an input voltage stabilizing capacitor C 1, energy storage DC source B, energy storage voltage stabilizing capacitor C 2 , load resistor R L , output voltage stabilizing capacitor C 3 , first switch unit K 1 , second switch unit K 2 , third switch unit K 3 , fourth switch unit K 4 , fifth switch unit K 5 , sixth switch unit K 6 , power switch tube S 1 , power switch tube S 2 , power switch tube S 3 , power switch tube S 4 , power switch tube S 5 , power switch tube S 6 , body diode D S1 , body diode D S2 , body diode D S3 , body diode D S4 , body diode D S5 , body diode D S6 , series diode D 1 , series diode D 2 , parallel capacitor C S1 , parallel capacitor C S2 , parallel capacitor C S3 , parallel capacitor C S4 , parallel capacitor C S5 , parallel capacitor C S6 , power inductor L 1 , power inductor L 2 ;

[0006] The positive electrode of the photovoltaic cell DC source U S is connected to the anode of the series diode D 1 , the cathode of the series diode D 1 is connected to the positive electrode of the input voltage stabilizing capacitor C 1 and the drain of the power switch tube S 1 , the source of the power switch tube S 1 is connected to the drain of the power switch tube S 2 and one end of the power inductor L 1 , the other end of the power inductor L 1 is connected to the anode of the series diode D 2 and the drain of the power switch tube S 6 , the cathode of the series diode D 2 is connected to the positive electrode of the output voltage stabilizing capacitor C 3 and one end of the load resistor R L , the other end of the load resistor R LThe other end is connected to the output voltage stabilizing capacitor C 3 The negative electrode and the power switch tube S 6 The source electrode of the power switch tube S 2 The source electrode of the power switch tube S is connected to the power switch tube S 3 The drain electrode and the power inductor L 2 One end of the power inductor L 2 The other end is connected to the power switch tube S 4 The source electrode and the power switch tube S 5 The drain electrode of the power switch tube S 4 The drain electrode is connected to the energy storage voltage stabilizing capacitor C 2 The positive electrode and the positive electrode of the energy storage DC source B. The negative electrode of the energy storage DC source B is connected to the energy storage voltage stabilizing capacitor C 2 The negative electrode, the power switch tube S 6 The source electrode of the power switch tube S 5 The source electrode of the power switch tube S 3 The source electrode, the input voltage stabilizing capacitor C 1 The negative electrode and the photovoltaic cell DC source U S The negative electrode.

[0007] Preferably, the first switching unit K 1 Consists of a power switch tube S 1 , a body diode D S1 And a parallel capacitor C S1 The power switch tube S 1 Is in parallel with the body diode D S1 And the parallel capacitor C S1 In parallel; the second switching unit K 2 Consists of a power switch tube S 2 , a body diode D S2 And a parallel capacitor C S2 The power switch tube S 2 Is in parallel with the body diode D S2 And the parallel capacitor C S2 In parallel; the third switching unit K 3 Consists of a power switch tube S 3 , a body diode D S3 And a parallel capacitor C S3 The power switch tube S 3 Is in parallel with the body diode D S3 And the parallel capacitor C S3 In parallel; the fourth switching unit K 4 Consists of a power switch tube S 4 , a body diode D S4 And a parallel capacitor C S4 The power switch tube S 4 Is in parallel with the body diode D S4 And the parallel capacitor CS4 Parallel connection; the fifth switching unit K 5 Composed of a power switching transistor S 5 , a body diode D S5 and a parallel capacitor C S5 The power switching transistor S 5 is connected in parallel with the body diode D S5 and the parallel capacitor C S5 Parallel connection; the sixth switching unit K 6 Composed of a power switching transistor S 6 , a body diode D S6 and a parallel capacitor C S6 The power switching transistor S 6 is connected in parallel with the body diode D S6 and the parallel capacitor C S6 in parallel.

[0008] Non-isolated three-port converter topology and wide-range soft-switching control method, the control method includes three working modes:

[0009] The first working mode: when the power P i of the photovoltaic port is greater than the power P 0 of the load port, the converter enters the single-input dual-output mode. While transferring energy from the photovoltaic port to the load port, the remaining energy is transferred to the energy storage port; by independently controlling two power inductors operating in parallel, a multi-modal energy transfer path is constructed;

[0010] The second working mode: when the power P i of the photovoltaic port is less than the power P 0 of the load port, the converter enters the dual-input single-output mode, and the photovoltaic port combines with the energy storage port to transfer energy to the load port; by time-division multiplexing control of the power inductor L 1 and the power inductor L 2 , a multi-modal energy transfer path is constructed;

[0011] The third working mode: when there is no energy exchange at the photovoltaic port, P i =0, the converter enters the single-input single-output mode, and the energy storage port alone transfers energy to the load port; by multiplexing control of the power inductor L 1 and the power inductor L 2 , a multi-modal energy transfer path is constructed.

[0012] Preferably, the first working mode specifically includes the independent control logic of the power inductor L 1 and the independent control logic of the power inductor L 2 .

[0013] Preferably, the power inductor L 1The independent control logic is specifically as follows:

[0014] The first stage: Control the power switch tube S 1 and the power switch tube S 6 to conduct, and the photovoltaic port charges the power inductor L 1 positively;

[0015] The second stage: Switch to the state where the power switch tube S 1 conducts and the power switch tube S 6 turns off. The power inductor L 1 charges or discharges positively through the photovoltaic port and the load port;

[0016] The third stage: The power switch tube S 1 turns off, activates the power switch tubes S 2 and S 3 to conduct. The power inductor L 1 conducts positive freewheeling for the load port;

[0017] The fourth stage: Switch to the state where the power switch tube S 6 conducts, drives the power inductor L 1 to complete reverse current extraction. The reverse current extraction means that the current of the power inductor L 1 flows reversely and discharges the parallel capacitor of its adjacent branch to prepare for the soft switching of the power switch tube in the next cycle;

[0018] The independent control logic of the power inductor L 2 is specifically as follows:

[0019] The first stage: Control the power switch tubes S 2 and S 5 to conduct, and the photovoltaic port charges the power inductor L 2 positively;

[0020] The second stage: Switch to the state where the power switch tube S 2 conducts and the power switch tube S 5 turns off. The power inductor L 2 charges or discharges positively through the photovoltaic port and the energy storage port;

[0021] The third stage: The power switch tube S 2 turns off, activates the power switch tubes S 3 and S 4 to conduct. The power inductor L 2 conducts positive freewheeling for the energy storage port;

[0022] The fourth stage: Switch to the state where the power switch tube S 5 conducts, drives the power inductor L 2Complete reverse pumping.

[0023] Preferably, the second working mode specifically includes the time-sharing control logic of the power inductor L 1 the time-sharing control logic of the power inductor L 2 the time-sharing control logic of the power inductor L 1 series power inductor L 2 the multiplexing control logic.

[0024] Preferably, the time-sharing control logic of the power inductor L 1 is specifically as follows:

[0025] First stage: Control the power switch tubes S 1 and the power switch tubes S 6 to conduct, and the photovoltaic port charges the power inductor L 1 forward; Second stage: Switch to the state where the power switch tube S 1 conducts and the power switch tube S 6 turns off, and the power inductor L 1 charges or discharges forward through the photovoltaic port and the load port;

[0026] The time-sharing control logic of the power inductor L 2 is specifically as follows:

[0027] First stage: Control the power switch tubes S 3 and the power switch tubes S 4 to conduct, and the energy storage port charges the power inductor L 2 in reverse;

[0028] The multiplexing control logic of the series power inductor L 1 and the power inductor L 2 is specifically as follows:

[0029] First stage: Control the power switch tube S 4 to conduct and the power switch tube S 3 to turn off, and the series power inductor L 1 and the power inductor L 2 charge or discharge in reverse through the energy storage port and the load port;

[0030] Second stage: The power switch tube S 4 turns off, activates the power switch tubes S 2 and the power switch tubes S 5 to conduct, and the series power inductor L 1 and the power inductor L 2 perform forward freewheeling on the load port;

[0031] Third stage: Switch to the state where the power switch tube S 6 conducts, drives the series power inductor L1 and power inductor L 2 Complete reverse current pumping.

[0032] Preferably, the third working mode specifically includes power inductor L 1 Series power inductor L 2 of multiplexing control logic.

[0033] Preferably, the multiplexing control logic of the series power inductor L 1 Series power inductor L 2 is specifically as follows:

[0034] First stage: Control power switch S 4 and power switch S 6 to conduct, and the energy storage port charges the series power inductor L 1 and power inductor L 2 forwardly;

[0035] Second stage: Switch to the state where power switch S 4 conducts and power switch S 6 turns off. The series power inductor L 1 and power inductor L 2 are charged or discharged forwardly through the energy storage port and the load port;

[0036] Third stage: Power switch S 4 turns off, activates power switch S 2 and power switch S 5 to conduct. The series power inductor L 1 and power inductor L 2 perform forward freewheeling on the load port;

[0037] Fourth stage: Switch to the state where power switch S 6 conducts, and drives the series power inductor L 1 and power inductor L 2 to complete reverse current pumping.

[0038] The control method adjusts the duty cycles of the two power inductors by controlling the conduction timing of the power switches, realizes the autonomous power distribution of the three ports. At the same time, with the design of the parallel capacitor of the power switch and the multiplexing dual inductors, the reverse current pumping ability of power inductor L 1 and power inductor L 2 can be improved, so that the voltage across the corresponding two ends of each power switch is clamped to zero voltage at the conduction moment, thereby realizing the soft-switching characteristic of zero-voltage conduction within the full load range.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] (1) The non-isolated three-port converter involved in the present invention shares a power switch and two power inductors, and single-stage power conversion is implemented between all three ports, having the advantages of high power density and high efficiency;

[0041] (2) The non-isolated three-port converter involved in the present invention transfers energy at the photovoltaic port within a wide voltage range, eliminates the voltage constraint conditions, and expands the application scope;

[0042] (3) The non-isolated three-port converter involved in the present invention has unchanged operating modes for the three operating modes of the converter when the voltage at the photovoltaic port varies within a wide range, has voltage self-adaptive characteristics, and improves the stability of the converter;

[0043] (4) For the non-isolated three-port converter involved in the present invention, the design of parallel capacitors for power switch tubes and multiplexed dual inductors improves the reverse current extraction ability of the power inductors, and each power switch tube can achieve zero-voltage conduction within the full load range. Description of the Drawings

[0044] Figure 1 is a schematic diagram of the complete topological structure of the multiplexed dual-inductor non-isolated three-port converter described in the present invention;

[0045] Figure 2 is a schematic diagram of the simplified topological structure of the multiplexed dual-inductor non-isolated three-port converter described in the present invention under the third operating mode;

[0046] Figure 3 is a schematic diagram of the main operating waveforms and operating modes of the multiplexed dual-inductor non-isolated three-port converter described in the present invention under the first operating mode;

[0047] Figure 4 is a schematic diagram of the main operating waveforms and operating modes of the multiplexed dual-inductor non-isolated three-port converter described in the present invention under the second operating mode;

[0048] Figure 5 is a schematic diagram of the main operating waveforms and operating modes of the multiplexed dual-inductor non-isolated three-port converter described in the present invention under the third operating mode;

[0049] Figure 6 is the drive signal u of the power switch tube of the multiplexed dual-inductor non-isolated three-port converter described in the present invention under the first operating mode at different input voltages gs1 -u gs6 、the currents i L1 、i L2 of the two power inductors, and the soft-switching simulation waveform diagram of the power switch tube;

[0050] Figure 7Under the second working mode, the driving signal u of the power switch tube of the multiplexed dual-inductor non-isolated three-port converter according to the present invention under different input voltages gs1- u gs6 and the soft-switching simulation waveforms of the currents i L1 and i L2 of the two power inductors and the power switch tube;

[0051] Figure 8 Under the third working mode, the driving signal u gs1 -u gs6 of the power switch tube of the multiplexed dual-inductor non-isolated three-port converter according to the present invention under different input voltages, the currents i L1 and i L2 of the two power inductors and the soft-switching simulation waveforms of the power switch tube. Specific embodiments

[0052] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0053] Please refer to Figure 1-8 , the present invention provides a non-isolated three-port converter, including a photovoltaic cell DC source U S , an input voltage stabilizing capacitor C 1 , a storage DC source B, a storage voltage stabilizing capacitor C 2 , a load resistor R L , an output voltage stabilizing capacitor C 3 , a first switch unit K 1 , a second switch unit K 2 , a third switch unit K 3 , a fourth switch unit K 4 , a fifth switch unit K 5 , a sixth switch unit K 6 , a power switch tube S 1 , a power switch tube S 2 , a power switch tube S 3 , a power switch tube S 4 , a power switch tube S 5 , a power switch tube S 6 , a body diode D S1 , a body diode D S2 , a body diode D S3 , a body diode D S4 , a body diode D S5 , a body diode DS6 , series-connected diode D 1 , series-connected diode D 2 , parallel-connected capacitor C S1 , parallel-connected capacitor C S2 , parallel-connected capacitor C S3 , parallel-connected capacitor C S4 , parallel-connected capacitor C S5 , parallel-connected capacitor C S6 , power inductor L 1 , power inductor L 2 ;

[0054] The positive pole of the photovoltaic cell DC source U S is connected to the anode of the series-connected diode D 1 , and the cathode of the series-connected diode D 1 is connected to the positive pole of the input voltage-regulating capacitor C 1 and the drain of the power switch tube S 1 . The source of the power switch tube S 1 is connected to the drain of the power switch tube S 2 and one end of the power inductor L 1 . The other end of the power inductor L 1 is connected to the anode of the series-connected diode D 2 and the drain of the power switch tube S 6 . The cathode of the series-connected diode D 2 is connected to the positive pole of the output voltage-regulating capacitor C 3 and one end of the load resistor R L . The other end of the load resistor R L is connected to the negative pole of the output voltage-regulating capacitor C 3 and the source of the power switch tube S 6 . The source of the power switch tube S 2 is connected to the drain of the power switch tube S 3 and one end of the power inductor L 2 . The other end of the power inductor L 2 is connected to the source of the power switch tube S 4 and the source of the power switch tube S 5 . The drain of the power switch tube S 4 is connected to the positive pole of the energy storage voltage-regulating capacitor C 2 and the positive pole of the energy storage DC source B. The negative pole of the energy storage DC source B is connected to the negative pole of the energy storage voltage-regulating capacitor C 2 , the source of the power switch tube S 6 , the source of the power switch tube S 5 , the source of the power switch tube S 3 , the source of the power switch tube S 1 , the negative pole of the input voltage-regulating capacitor C S and the negative pole of the photovoltaic cell DC source U

[0055] The first switching unit K 1 is composed of a power switching transistor S 1 , a body diode D S1 and a parallel capacitor C S1 . The power switching transistor S 1 is in parallel with the body diode D S1 and the parallel capacitor C S1 . The second switching unit K 2 is composed of a power switching transistor S 2 , a body diode D S2 and a parallel capacitor C S2 . The power switching transistor S 2 is in parallel with the body diode D S2 and the parallel capacitor C S2 . The third switching unit K 3 is composed of a power switching transistor S 3 , a body diode D S3 and a parallel capacitor C S3 . The power switching transistor S 3 is in parallel with the body diode D S3 and the parallel capacitor C S3 . The fourth switching unit K 4 is composed of a power switching transistor S 4 , a body diode D S4 and a parallel capacitor C S4 . The power switching transistor S 4 is in parallel with the body diode D S4 and the parallel capacitor C S4 . The fifth switching unit K 5 is composed of a power switching transistor S 5 , a body diode D S5 and a parallel capacitor C S5 . The power switching transistor S 5 is in parallel with the body diode D S5 and the parallel capacitor C S5 . The sixth switching unit K 6 is composed of a power switching transistor S 6 , a body diode D S6 and a parallel capacitor C S6 . The power switching transistor S 6 is in parallel with the body diode D S6 and the parallel capacitor C S6 .

[0056] Non-isolated three-port converter topology and wide-range soft-switching control method. The control method includes three working modes:

[0057] The first working mode: When the power of the photovoltaic port is P iGreater than the load port power P 0 When this occurs, the converter enters the single-input dual-output mode. While transferring energy from the photovoltaic port to the load port, the remaining energy is transferred to the energy storage port. By independently controlling the two power inductors operating in parallel, a multi-modal energy transfer path is constructed;

[0058] The second operating mode: When the power P of the photovoltaic port i is less than the load port power P 0 When this occurs, the converter enters the dual-input single-output mode, and energy is transferred from the photovoltaic port in combination with the energy storage port to the load port; by time-division multiplexing control of the power inductor L 1 and the power inductor L 2 to construct a multi-modal energy transfer path;

[0059] The third operating mode: When there is no energy exchange at the photovoltaic port, P i = 0, the converter enters the single-input single-output mode, and the energy storage port alone transfers energy to the load port; by multiplexing control of the power inductor L 1 and the power inductor L 2 to construct a multi-modal energy transfer path.

[0060] The first operating mode specifically includes the independent control logic of the power inductor L 1 and the independent control logic of the power inductor L 2 .

[0061] The independent control logic of the power inductor L 1 is specifically as follows:

[0062] The first stage: Control the power switch tube S 1 , the power switch tube S 6 to conduct, and the photovoltaic port charges the power inductor L 1 positively;

[0063] The second stage: Switch to the state where the power switch tube S 1 conducts and the power switch tube S 6 is off. The power inductor L 1 is charged or discharged positively through the photovoltaic port and the load port;

[0064] The third stage: The power switch tube S 1 is turned off, activating the power switch tube S 2 , the power switch tube S 3 to conduct, and the power inductor L 1 performs positive freewheeling for the load port;

[0065] The fourth stage: Switch to the power switch tube S 6 to conduct, driving the power inductor L 1Complete reverse current pumping; the reverse current pumping refers to the current of the power inductor L 1 flowing in the reverse direction and discharging the parallel capacitor of its adjacent branch, preparing for the soft switching of the power switch tube in the next cycle;

[0066] The independent control logic of the power inductor L 2 is specifically as follows:

[0067] The first stage: Control the power switch tube S 2 and the power switch tube S 5 to conduct, and the photovoltaic port charges the power inductor L 2 in the forward direction;

[0068] The second stage: Switch to the conduction state of the power switch tube S 2 and the off state of the power switch tube S 5 . The power inductor L 2 is charged or discharged in the forward direction through the photovoltaic port and the energy storage port;

[0069] The third stage: Turn off the power switch tube S 2 , activate the power switch tube S 3 and the power switch tube S 4 to conduct, and the power inductor L 2 performs forward freewheeling on the energy storage port;

[0070] The fourth stage: Switch to the conduction of the power switch tube S 5 , drive the power inductor L 2 to complete reverse current pumping.

[0071] The second working mode specifically includes the time-sharing control logic of the power inductor L 1 , the time-sharing control logic of the power inductor L 2 and the multiplexing control logic of the series power inductor L 1 and the power inductor L 2 .

[0072] The time-sharing control logic of the power inductor L 1 is specifically as follows:

[0073] The first stage: Control the power switch tube S 1 and the power switch tube S 6 to conduct, and the photovoltaic port charges the power inductor L 1 in the forward direction; The second stage: Switch to the conduction state of the power switch tube S 1 and the off state of the power switch tube S 6 . The power inductor L 1 is charged or discharged in the forward direction through the photovoltaic port and the load port;

[0074] The power inductor L 2The time-sharing control logic is specifically as follows:

[0075] The first stage: Control the power switch tube S 3 and the power switch tube S 4 to conduct, and the energy storage port performs reverse charging on the power inductor L 2 ;

[0076] The multiplexing control logic of the series power inductor L 1 and the series power inductor L 2 is specifically as follows:

[0077] The first stage: Control the power switch tube S 4 to conduct, the power switch tube S 3 to turn off, and the series power inductor L 1 and the power inductor L 2 perform reverse charging or discharging through the energy storage port and the load port;

[0078] The second stage: The power switch tube S 4 turns off, activates the power switch tube S 2 and the power switch tube S 5 to conduct, and the series power inductor L 1 and the power inductor L 2 perform forward freewheeling on the load port;

[0079] The third stage: Switch to the power switch tube S 6 to conduct, drive the series power inductor L 1 and the power inductor L 2 to complete reverse current extraction.

[0080] The third working mode specifically includes the multiplexing control logic of the power inductor L 1 and the series power inductor L 2 ;

[0081] The multiplexing control logic of the power inductor L 1 and the series power inductor L 2 is specifically as follows:

[0082] The first stage: Control the power switch tube S 4 and the power switch tube S 6 to conduct, and the energy storage port performs forward charging on the series power inductor L 1 and the power inductor L 2 ;

[0083] The second stage: Switch to the state where the power switch tube S 4 conducts and the power switch tube S 6 turns off, and the series power inductor L 1 and the power inductor L 2Forward charging or discharging is carried out through the energy storage port and the load port;

[0084] The third stage: The power switch tube S 4 Turns off, activates the power switch tube S 2 , the power switch tube S 5 Conducts, and the series power inductor L 1 and the power inductor L 2 Perform forward freewheeling on the load port;

[0085] The fourth stage: Switch to the power switch tube S 6 Conducts, drives the series power inductor L 1 and the power inductor L 2 Complete reverse current pumping.

[0086] The control method realizes the autonomous power distribution of the three ports by controlling the conduction timing of the power switch tubes and adjusting the duty cycles of the two power inductors. At the same time, with the design of the parallel capacitor of the power switch tubes and the multiplexing of the dual inductors, the reverse current pumping ability of the power inductor L 1 and the power inductor L 2 can be improved, so that the voltage across the corresponding two ends of each power switch tube is clamped to zero voltage at the conduction moment, thereby realizing the soft-switching characteristic of zero-voltage conduction in the full load range.

[0087] The multiplexing dual-inductor non-isolated three-port converter described in the present invention realizes three working modes through the independent, time-sharing and multiplexing control of the dual power inductors. The characteristics of each mode are as follows:

[0088] I. Working mode switching mechanism

[0089] 1. Single-input dual-output mode (P i >P 0 ): The photovoltaic port supplies power to the load port and the energy storage port respectively.

[0090] 2. Dual-input single-output mode (P i <P 0 ): The photovoltaic port and the energy storage port jointly supply power to the load port.

[0091] 3. Single-input single-output mode (P i =0): The energy storage port supplies power to the load port alone.

[0092] II. Typical working mode examples

[0093] In the first working mode, there are 12 working modes in the converter. As shown in the appendix Figure 3 , the core process includes:

[0094] 1. The power inductors L 1 and the power inductor L2 Charging stage: Power switch tube S 1 and power switch tube S 2 and power switch tube S 5 and power switch tube S 6 conduct, the series diode D 1 is forward-biased, and the photovoltaic port simultaneously charges the power inductor L 1 and power inductor L 2 in the forward direction (corresponding to mode 1);

[0095] 2. The power inductors L 1 in parallel operation and power inductor L 2 Charge / discharge stage: Power switch tube S 1 and power switch tube S 2 and power switch tube S 4 conduct, the series diode D 1 and series diode D 2 are forward-biased, and the power inductor L 1 performs forward charge / discharge through the photovoltaic port and the load port, and at the same time the power inductor L 2 performs forward charge / discharge through the photovoltaic port and the energy storage port (corresponding to mode 3);

[0096] 3. The power inductors L 1 in parallel operation and power inductor L 2 Freewheeling stage: Power switch tube S 2 and power switch tube S 3 and power switch tube S 4 conduct, the series diode D 2 is forward-biased, and the power inductor L 1 performs forward freewheeling on the load port, and at the same time the power inductor L 2 performs forward freewheeling on the energy storage port (corresponding to mode 7);

[0097] 4. The power inductors L 1 in parallel operation and power inductor L 2 Reverse current extraction stage: Power switch tube S 2 and power switch tube S 3 and power switch tube S 5 and power switch tube S 6 conduct, and the power inductors L 1 and power inductor L 2 perform reverse current extraction (corresponding to mode 11);

[0098] 5. Soft-switching implementation stage: When the power switch tubes S 1 -S 6 turn off, the parallel capacitors C S1 -C S6Discharge through the current of adjacent branches. When the drain-source voltage u of the power switch transistor ds1 -u ds6 drops to zero, the body diode D S1 -D S6 conducts, and the power switch transistor S 1 -S 6 conducts under zero-voltage conditions (corresponding to Mode 2, Mode 4, Mode 6, Mode 8, Mode 10, Mode 12).

[0099] In the second operating mode, there are 10 operating modes in the converter, as shown in the appendix Figure 4 as follows. The core processes include:

[0100] 1. Charging stage of the parallel-connected power inductors L 1 and L 2 : The power switch transistors S 1 、S 3 、S 4 、S 6 conduct, the series diode D 1 is forward-biased, the photovoltaic port charges the power inductor L 1 positively, and the energy storage port charges the power inductor L 2 positively (corresponding to Mode 1);

[0101] 2. Charge / discharge stage of the series power inductors L 1 and L 2 : The power switch transistors S 2 、S 4 conduct, the series diodes D 1 、D 2 are forward-biased, and the series power inductors L 1 and L 2 charge / discharge positively through the energy storage port and the load port (corresponding to Mode 5);

[0102] 3. Freewheeling stage of the series power inductors L 1 and L 2 : The power switch transistors S 2 、S 5 conduct, the series diode D 2 is forward-biased, and the series power inductors L 1 and L 2 perform positive freewheeling on the load port (corresponding to Mode 7);

[0103] 4. Reverse current extraction stage of the series power inductors L 1 and L 2 : The power switch transistors S 2 、S5 and the power switch tube S 6 conducts, and the series power inductor L 1 and the power inductor L 2 perform reverse current pumping (corresponding to Mode 9);

[0104] 5. Soft-switching implementation stage: When the power switch tube S 1 -S 6 turns off, the parallel capacitors C S1 -C S6 discharge through the current of the adjacent branch. When the drain-source voltage u ds1 -u ds6 of the power switch tube drops to zero, the body diode D S1 -D S6 conducts, and the power switch tube S 1 -S 6 turns on under zero-voltage conditions (corresponding to Modes 2, 4, 6, 8, and 10).

[0105] In the third operating mode, the converter has 8 operating modes, as shown Figure 5 in the appendix. The core process includes:

[0106] 1. Charging stage of the series power inductor L 1 and the power inductor L 2 : The power switch tubes S 2 , S 4 , and S 6 conduct, and the energy storage port charges the series power inductor L 1 and the power inductor L 2 forward (corresponding to Mode 1);

[0107] 2. Charging / discharging stage of the series power inductor L 1 and the power inductor L 2 : The power switch tubes S 2 , S 4 conduct, the series diode D 2 is forward-biased, and the series power inductor L 1 and the power inductor L 2 perform forward charging / discharging through the energy storage port and the load port (corresponding to Mode 3);

[0108] 3. Freewheeling stage of the series power inductor L 1 and the power inductor L 2 : The power switch tubes S 2 , S 5 conduct, the series diode D 2 is forward-biased, and the series power inductor L 1 and the power inductor L 2Forward freewheeling of the load port (corresponding to Mode 5);

[0109] 4. Series power inductor L 1 and power inductor L 2 Reverse current pumping stage: Power switch S 2 、Power switch S 5 、Power switch S 6 conducts, and the series power inductor L 1 and power inductor L 2 perform reverse current pumping (corresponding to Mode 7);

[0110] 5. Soft-switching implementation stage: When the power switch S 4 -S 6 turns off, the parallel capacitors C S4 -C S6 discharge through the current of the adjacent branch. When the drain-source voltage u ds4 -u ds6 drops to zero, the body diode D S4 -D S6 conducts, and the power switch S 4 -S 6 conducts under zero-voltage conditions (corresponding to Mode 2, Mode 4, Mode 6, Mode 8).

[0111] Embodiment 1, single-input dual-output mode:

[0112] To verify the correctness of the proposed scheme, Matlab / Simulink is used for simulation. The simulation parameters are: Photovoltaic port voltage u i = 40 - 80V, load port voltage u 0 = 60V, load port power P 0 = 300W, energy storage port voltage u b = 48V, power inductor L 1 = 4μH, power inductor L 2 = 3μH, energy storage voltage-stabilizing capacitor C 2 = 16.6μF, output voltage-stabilizing capacitor C 3 = 62.5μF, parallel capacitor C S1 = C S2 = C S3 = C S4 = C S5 = C S6 = 3nF, switching frequency f s = 200kHz.

[0113] When it is detected that the photovoltaic port power P i > load port power P 0When, due to the voltage self - adapting characteristic of the converter, according to the following formula, at u i >u 0 >u 0 、u 0 >u i >u b 、u 0 >u b >u i In these three operating conditions, by adjusting the duty cycle to maintain the same mode - switching logic, the 12 - mode control sequence in Appendix Figure 3 is executed to stabilize the voltages at the load port and the energy - storage port.

[0114]

[0115]

[0116] Among them, M PV-L is the voltage gain from the photovoltaic port to the load port, M PV-B is the voltage gain from the photovoltaic port to the energy - storage port, and T 11 、T 12 、T 13 、T 21 、T 22 、T 23 are the times of each stage of the power inductor L 1 and the power inductor L 2 respectively.

[0117] In this embodiment, the drive signals u gs1 -u gs6 of the power switch tubes, the currents i L1 、i L2 of the two power inductors, and the soft - switching simulation waveforms of the power switch tubes of the non - isolated three - port converter described in the present invention under the photovoltaic - port voltages of 80V, 60V, and 40V are as shown in Figure 6 .

[0118] Embodiment 2: Dual - input single - output mode:

[0119] With the configuration parameters the same as those in Embodiment 1, when it is detected that the power P i < of the photovoltaic port is less than the power P 0 of the load port, due to the voltage self - adapting characteristic of the converter, according to the following formula, at u i >u 0 >u b 、u 0 >u i >u b 、u 0 >u b >u iUnder three working conditions, the same mode switching logic is maintained by duty cycle adjustment, and the 10-mode control sequence attached Figure 4 is executed to stabilize the load port voltage.

[0120]

[0121] Among them, M B-L is the voltage gain from the energy storage port to the load port.

[0122] In this embodiment, the drive signals u gs1 -u gs6 of the power switch tubes, the currents i L1 and i L2 of two power inductors, and the soft-switching simulation waveforms of the power switch tubes of the non-isolated three-port converter according to the present invention are as Figure 7 shown.

[0123] Embodiment 3, single-input single-output mode:

[0124] The configuration parameters are the same as those in Embodiment 1. When it is detected that the power P i of the photovoltaic port is 0, according to the following formula, the same mode switching logic is maintained by duty cycle adjustment, and the 8-mode control sequence attached Figure 5 is executed to stabilize the load port voltage.

[0125]

[0126] In this embodiment, the drive signals u gs1 -u gs6 of the power switch tubes of the multiplexed dual-inductor non-isolated three-port converter according to the present invention, the current i 1 of the power inductor L L1 and the current i 2 of the power inductor L L2 and the soft-switching simulation waveforms of the power switch tubes are as Figure 8 shown.

[0127] According to the above theoretical analysis and corresponding simulations, the non-isolated three-port converter proposed by the present invention has the advantages of high power density, high efficiency, good stability, and a wide photovoltaic port voltage range, and has strong practicability. Each power switch tube can achieve zero-voltage conduction within the full load range. Therefore, the present invention has more advantages compared with some existing technologies.

[0128] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A non-isolated three-port converter, characterized in that: Including photovoltaic cell DC source U S , input voltage stabilizing capacitor C1, energy storage DC source B, energy storage voltage stabilizing capacitor C2, load resistor R L , output voltage stabilizing capacitor C3, first switch unit K1, second switch unit K2, third switch unit K3, fourth switch unit K4, fifth switch unit K5, sixth switch unit K6, power switch tube S1, power switch tube S2, power switch tube S3, power switch tube S4, power switch tube S5, power switch tube S6, body diode D S1 、Body diode D S2 、Body diode D S3 、Body diode D S4 、Body diode D S5 、Body diode D S6 , series diode D1, series diode D2, parallel capacitor C S1 , parallel capacitor C S2 , parallel capacitor C S3 , parallel capacitor C S4 , parallel capacitor C S5 , parallel capacitor C S6 , power inductor L1, power inductor L2; The photovoltaic cell DC source U S The positive electrode of the series diode D1 is connected to the anode of the series diode D1, the cathode of the series diode D1 is connected to the positive electrode of the input voltage stabilizing capacitor C1 and the drain of the power switch tube S1, the source of the power switch tube S1 is connected to the drain of the power switch tube S2 and one end of the power inductor L1, the other end of the power inductor L1 is connected to the anode of the series diode D2 and the drain of the power switch tube S6, the cathode of the series diode D2 is connected to the positive electrode of the output voltage stabilizing capacitor C3 and the load resistor R L One end of the load resistor R L The other end is connected to the negative electrode of the output stabilizing capacitor C3 and the source of the power switch tube S6, the source of the power switch tube S2 is connected to the drain of the power switch tube S3 and one end of the power inductor L2, the other end of the power inductor L2 is connected to the source of the power switch tube S4 and the drain of the power switch tube S5, the drain of the power switch tube S4 is connected to the positive electrode of the energy storage stabilizing capacitor C2 and the positive electrode of the energy storage DC source B, the negative electrode of the energy storage DC source B is connected to the negative electrode of the energy storage stabilizing capacitor C2, the source of the power switch tube S6, the source of the power switch tube S5, the source of the power switch tube S3, the negative electrode of the input stabilizing capacitor C1 and the photovoltaic cell DC source U S of the negative electrode.

2. The non-isolated three-port converter according to claim 1, characterized in that: The first switch unit K1 is composed of a power switch tube S1, a body diode D S1 And the parallel capacitor C S1 The power switch tube S1 and the body diode D S1 And the parallel capacitor C S1 The second switch unit K2 is composed of a power switch tube S2, a body diode D S2 And the parallel capacitor C S2 The power switch tube S2 and the body diode D S2 And the parallel capacitor C S2 The third switch unit K3 is composed of a power switch tube S3, a body diode D S3 And the parallel capacitor C S3 The power switch tube S3 and the body diode D S3 And the parallel capacitor C S3 The fourth switch unit K4 is composed of a power switch tube S4, a body diode D S4 And the parallel capacitor C S4 The power switch tube S4 and the body diode D S4 And the parallel capacitor C S4 The fifth switch unit K5 is composed of a power switch tube S5, a body diode D S5 And the parallel capacitor C S5 The power switch tube S5 and the body diode D S5 And the parallel capacitor C S5 The sixth switch unit K6 is composed of a power switch tube S6, a body diode D S6 And the parallel capacitor C S6 The power switch tube S6 and the body diode D S6 And the parallel capacitor C S6 in parallel.

3. The non-isolated three-port converter topology and wide range soft switch control method according to any one of claims 1-2, characterized in that: The control method includes three working modes: The first working mode: When the PV port power P i When the power is greater than the load port power P0, the converter enters the single-input dual-output mode, transmitting energy from the photovoltaic port to the load port while transmitting the remaining energy to the energy storage port; A multi-modal energy transfer path is constructed by independently controlling two power inductors running in parallel; The second working mode: When the PV port power P i When the power is less than the load port power P0, the converter enters the dual-input single-output mode, and the photovoltaic port and the energy storage port transmit energy to the load port; the power inductor L1 and the power inductor L2 are controlled by time-division multiplexing to construct a multi-modal energy transmission path; The third working mode: When the photovoltaic port does not exchange energy, P i =0, the converter enters the single-input single-output mode, and the energy storage port transmits energy to the load port alone; by multiplexing and controlling the power inductor L1 and the power inductor L2, a multi-modal energy transmission path is constructed.

4. The non-isolated three-port converter topology and wide range soft switch control method according to claim 3, characterized in that: The first working mode specifically includes an independent control logic of the power inductor L1 and an independent control logic of the power inductor L2.

5. The non-isolated three-port converter topology and wide range soft switch control method according to claim 4, characterized in that: The independent control logic of the power inductor L1 is specifically as follows: The first stage: the power switch tube S1 and the power switch tube S6 are controlled to be turned on, and the photovoltaic port positively charges the power inductor L1; The second stage: the power switch tube S1 is switched on and the power switch tube S6 is switched off, and the power inductor L1 is positively charged or discharged through the photovoltaic port and the load port; The third stage: the power switch tube S1 is turned off, the power switch tube S2 is activated, the power switch tube S3 is turned on, and the power inductor L1 performs forward freewheeling to the load port; The fourth stage: switching on the power switch tube S6 to drive the power inductor L1 to complete reverse current extraction; the reverse current extraction refers to the current of the power inductor L1 flowing in the opposite direction and discharging the parallel capacitor of its adjacent branch to prepare for the soft switching of the power switch tube in the next cycle; The independent control logic of the power inductor L2 is specifically as follows: The first stage: control the power switch tube S2 and the power switch tube S5 to be turned on, and the photovoltaic port charges the power inductor L2 positively; The second stage: the power switch tube S2 is switched on and the power switch tube S5 is switched off, and the power inductor L2 is positively charged or discharged through the photovoltaic port and the energy storage port; The third stage: the power switch tube S2 is turned off, the power switch tube S3 is activated, the power switch tube S4 is turned on, and the power inductor L2 performs forward freewheeling to the energy storage port; The fourth stage: the power switch tube S5 is switched on to drive the power inductor L2 to complete reverse current extraction.

6. The non-isolated three-port converter topology and wide range soft switch control method according to claim 3, characterized in that: The second working mode specifically includes a time-sharing control logic of the power inductor L1, a time-sharing control logic of the power inductor L2, and a multiplexing control logic of connecting the power inductor L1 in series with the power inductor L2.

7. The non-isolated three-port converter topology and wide range soft switch control method according to claim 6, characterized in that: The time-sharing control logic of the power inductor L1 is specifically as follows: The first stage: control the power switch tube S1 and the power switch tube S6 to be turned on, and the photovoltaic port charges the power inductor L1 positively; the second stage: switch to the power switch tube S1 turned on and the power switch tube S6 turned off, and the power inductor L1 is positively charged or discharged through the photovoltaic port and the load port; The time-sharing control logic of the power inductor L2 is specifically as follows: The first stage: control the power switch tube S3 and the power switch tube S4 to be turned on, and the energy storage port reversely charges the power inductor L2; The multiplexing control logic of the power inductor L1 in series with the power inductor L2 is specifically as follows: Phase 1: Control the power switch tube S4 to turn on and the power switch tube S3 to turn off, and the series power inductor L1 and the power inductor L2 are reversely charged or discharged through the energy storage port and the load port; The second stage: the power switch tube S4 is turned off, the power switch tube S2 is activated, the power switch tube S5 is turned on, and the power inductor L1 and the power inductor L2 are connected in series to provide forward freewheeling to the load port; The third stage: the power switch tube S6 is switched on to drive the series power inductor L1 and the power inductor L2 to complete reverse current extraction.

8. The non-isolated three-port converter topology and wide range soft switch control method according to claim 3, characterized in that: The third working mode specifically includes a multiplexing control logic of connecting the power inductor L1 in series with the power inductor L2.

9. The non-isolated three-port converter topology and wide range soft switch control method according to claim 8, characterized in that: The multiplexing control logic of the power inductor L1 in series with the power inductor L2 is specifically as follows: The first stage: the power switch tube S4 and the power switch tube S6 are controlled to be turned on, and the energy storage port positively charges the series power inductor L1 and the power inductor L2; The second stage: switch to the power switch tube S4 on state and the power switch tube S6 off state, the series power inductor L1 and the power inductor L2 are positively charged or discharged through the energy storage port and the load port; The third stage: the power switch tube S4 is turned off, the power switch tube S2 is activated, the power switch tube S5 is turned on, and the power inductor L1 and the power inductor L2 are connected in series to provide forward freewheeling to the load port; The fourth stage: the power switch tube S6 is switched on to drive the series power inductor L1 and the power inductor L2 to complete reverse current extraction.

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