Optical-storage integrated multi-input high-gain DC-DC converter

Abstract

An optical-storage integrated multi-input high-gain DC-DC converter comprises a photovoltaic DC input source, an energy storage battery, switches S1 to S4, diodes D1 to D5 and Do, capacitors C1 to C4 and Co and an inductor L1. The converter has four power supply modes including a photovoltaic single-output mode, an energy storage battery single-output mode, a photovoltaic dual-output mode and a light-storage dual-output mode. A photovoltaic single-output mode, an energy storage battery single-output mode, a photovoltaic dual-output mode and a light-storage dual-output mode are realized in the DC-DC converter. And the number of converters in the optical-storage system, the control difficulty and the manufacturing cost are effectively reduced. Moreover, the output voltage can be effectively improved through a boost structure in the converter, and the converter is more suitable for the application occasion of a light-storage converter under new energy grid connection.

Description

Technical Field

[0001] The invention relates to a DC-DC converter, in particular to a photoelectric-storage integrated multi-input high-gain DC-DC converter. Background Art

[0002] Renewable energy power generation systems have strong randomness and volatility. In order to improve the stability of the power supply system, energy storage units are usually introduced into the system to smooth power fluctuations. However, in traditional photovoltaic storage DC power supply systems, independent DC-DC converters are usually configured for photovoltaic power generation units, energy storage units, and photovoltaic-storage charging units to achieve different current conversion functions. This configuration method not only increases the number of converters, resulting in increased system costs and reduced reliability, but also makes the control of the system complicated. In addition, since the power generation voltage of the new energy power generation unit is low and the grid-connected voltage is often high, the voltage gain of the traditional DC-DC converter is low, making it difficult to achieve a large boost capability.

[0003] For example, the patent document with application publication number CN114696349A discloses a power-adjustable photovoltaic storage and charging integrated method and system, which includes: setting up a power-adjustable photovoltaic storage and charging integrated system; selecting the allocation method according to the use period, bidirectional flow of energy between the AC bus and the DC bus during the valley period, charging the electric vehicle and the battery unit, and the battery unit is in a static state during the normal period, and the photovoltaic unit sends the generated electricity to the DC bus through the photovoltaic DC-DC module; when the electricity price is peak, the power stored in the battery unit and the photovoltaic unit are preferentially used to charge the electric vehicle; the control switch matrix dynamically allocates the power of the charging DC-DC module through the switching of the switch to ensure that any charging gun meets the charging power demand. This patent solution realizes the energy interaction between the microgrid system and the AC power grid through the energy storage PCS, and the energy storage and charging piles in the microgrid can directly interact with energy through the DC bus. It realizes the combination of photovoltaic and energy storage, realizes the selection of allocation methods according to the use period, and improves the economy of the power grid. However, in this system, the photovoltaic and energy storage units and the charging and discharging circuits are equipped with multiple independent DC-DC converters, which not only increases the number of converters, resulting in increased system costs and reduced reliability, but also complicates the control of the system. Summary of the invention

[0004] In order to solve the problem of a large number of converters and insufficient boosting capability in existing photovoltaic and energy storage systems. The present invention proposes a photovoltaic-storage integrated multi-input high-gain DC-DC converter, which includes photovoltaic and energy storage ports, and a boosting structure. Photovoltaic single output mode, energy storage battery single output mode, photovoltaic dual output mode, and photovoltaic-storage dual output mode are realized inside a DC-DC converter. The number of converters, control difficulty, and manufacturing cost in the photovoltaic-storage system are effectively reduced. And the output voltage can be effectively increased by the boosting structure in the converter, which is more suitable for the application of photovoltaic-storage converters under new energy grid connection.

[0005] The technical solution adopted by the present invention is:

[0006] A photovoltaic-storage integrated multi-input high-gain DC-DC converter includes a photovoltaic DC input source, an energy storage battery, switches S1-S4, diodes D1-D5, Do, capacitors C1-C4, Co, and an inductor L1; its connection form is as follows:

[0007] One end of the photovoltaic DC input source is connected to the drain of the switch S1, and the source of the switch S1 is connected to the source of the switch S2 and one end of the inductor L1 respectively;

[0008] The drain of the switch S2 is connected to the positive electrode of the energy storage battery and the source of the switch S3 respectively, and the drain of the switch S3 is connected to the cathode of the diode D1;

[0009] The other end of the inductor L1 is respectively connected to the anode of the diode D1, one end of the capacitor C1, the other end of the capacitor C2, the drain of the switch S4, and the anode of the diode D4;

[0010] One end of the capacitor C2 is connected to the anode of the diode Do and the cathode of the diode D5 respectively;

[0011] The other end of capacitor C1 is connected to the anode of diode D3 and the cathode of diode D2 respectively.

[0012] The cathode of the diode D4 is connected to the anode of the diode D5 and one end of the capacitor C3 respectively;

[0013] The other end of capacitor C3 is connected to the anode of diode D5 and one end of capacitor C4 respectively; the other end of capacitor C4 is connected to the anode of diode D2;

[0014] The cathode of the diode Do is connected to one end of the capacitor Co; the other end of the capacitor Co is respectively connected to one end of the capacitor C4, the source of the switch S4, the negative electrode of the energy storage battery, and the other end of the photovoltaic DC input source;

[0015] One end of the load R and the other end of the load R are connected to one end of the capacitor Co and the other end of the capacitor Co respectively.

[0016] The converter has four power supply modes: photovoltaic single output mode, energy storage battery single output mode, photovoltaic dual output mode, and light-storage dual output mode. The voltage gains are as follows:

[0017] In PV single output mode:

[0018]

[0019] Among them, u PV Indicates photovoltaic output voltage, D 4 represents the duty cycle of switch S4;

[0020] In the energy storage battery single output mode:

[0021]

[0022] Among them, u ES Indicates the battery output voltage;

[0023] In PV dual output mode:

[0024]

[0025] Among them, D 3 represents the duty cycle of switch S3;

[0026] In light-storage dual output mode:

[0027]

[0028] Among them, D 2 represents the duty cycle of switch S2;

[0029] In the photovoltaic single output mode, switch S1 is in the normally on state, switches S2 and S3 are in the normally off state, and switch S4 is in the PWM mode. At this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R. When switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time.

[0030] In the single output mode of the energy storage battery, switches S1 and S3 are in the normally off state, switch S2 is in the normally open state, and switch S4 is in the PWM mode. At this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R. When switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time.

[0031] In the photovoltaic dual output mode, switch S1 is in the normally on state, switch S2 is in the normally off state, and switches S3 and S4 are in the PWM mode. At this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R. When switch S4 is turned off, switch S3 is turned on, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time; when switch S4 is turned off, switch S3 is turned off, and the energy storage battery Battery stops charging.

[0032] In the photovoltaic-storage dual output mode, switch S1 is in the normally on state, switch S3 is in the normally off state, switches S1, S2 and S4 are in the PWM mode, and switches S1 and S2 are complementary. At this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, photovoltaic and energy storage batteries charge inductor L1, capacitor C2, and capacitor C4 respectively, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to load R; when switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, photovoltaic, energy storage battery, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and load R is supplied with power at the same time.

[0033] The present invention provides a multi-input high-gain DC-DC converter with integrated light-storage technology, and the technical effects are as follows:

[0034] 1) The present invention constructs photovoltaic and energy storage converters in one DC-DC converter, effectively reducing the number of converters in the photovoltaic-storage system, the control difficulty and the manufacturing cost.

[0035] 2) Compared with the traditional DC-DC converter, the converter of the present invention has a higher voltage boost function and is more suitable for the grid-connected voltage requirements in renewable energy power generation situations.

[0036] 3) The converter of the present invention effectively reduces the number of converters in the photovoltaic-storage system, the control difficulty and the manufacturing cost. And the output voltage can be effectively increased through the boost structure in the converter, which is more suitable for photovoltaic-storage converter applications under new energy grid connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below in conjunction with the accompanying drawings and examples;

[0038] Figure 1 It is a circuit schematic diagram of the present invention.

[0039] Figure 2 The present invention is in photovoltaic single output mode, u PV =48V, D4=0.64, u o =400V simulation waveform.

[0040] Figure 3 In the present invention, in the single output mode of the energy storage battery, u ES =60V, D4=0.55, u o =400V simulation waveform.

[0041] Figure 4 In the photovoltaic dual output mode, u PV =48V, u ES =60V, D3=0.2, D4=0.53, u o =400V simulation waveform.

[0042] Figure 5 In the light-storage dual output mode, u PV =48V, u ES =60V, D2=0.44, D4=0.6, u o =400V simulation waveform. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings. Figure 1 The converter topology of the present invention is shown. The converter includes a photovoltaic DC input source, a storage battery, four active switches S1, S2, S3, S4, six diodes D1, D2, D3, D4, D5, Do, five capacitors C1, C2, C3, C4, Co, and an inductor L1. The connection form is as follows:

[0044] One end of the photovoltaic DC input source is connected to the drain of the active switch S1, the source of the active switch S1 is connected to the source of the active switch S2 and one end of the inductor L1, the other end of the inductor L1 is connected to one end of the capacitor C1, the other end of the capacitor C2, the drain of the active switch S4 and the anode of the diode D4, the other end of the capacitor C1 is connected to the anode of the diode D3 and the cathode of the diode D2, one end of the capacitor C2 is connected to the anode of the diode Do and the cathode of the diode D5, the other end of the capacitor C4 is connected to the anode of the diode D2, one end of the capacitor C4 is connected to the cathode of the diode D3 and the other end of the capacitor C3, one end of the capacitor C3 is connected to the anode of the diode D5 and the cathode of the diode D4, one end of the capacitor Co is connected to the cathode of the diode Do, the other end of the capacitor Co is connected to one end of the capacitor C4, the source of the active switch S4, the negative electrode of the energy storage battery and the other end of the photovoltaic DC input source, and one end and the other end of the load R are connected to one end and the other end of the capacitor Co respectively.

[0045] In the photovoltaic single output mode, the active switch S1 is in the normally on state, the active switches S2 and S3 are in the normally off state, and the active switch S4 is in the PWM mode. At this time, when the active switch S4 is turned on, the diodes D2 and D5 are turned on, the diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, the capacitor C2, and the capacitor C4, the capacitor C1 and the capacitor C3 are discharged, and the capacitor Co supplies power to the load R. When the active switch S4 is turned off, the diodes D2 and D5 are turned off, the diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, the inductor L1, the capacitor C2, and the capacitor C4 are discharged, the capacitor C1 and the capacitor C3 are charged, and the load R is supplied with power at the same time. At this time, the input and output voltage relationship is: Wherein, D4 is the duty cycle of the active switch S4.

[0046] Figure 2 The present invention is in photovoltaic single output mode, u PV =48V, D4=0.64, u o =400V simulation waveform. Figure 2 It can be seen that when the photovoltaic output voltage is 48V as the input source, the output voltage requirement of 400V at the load end is achieved by controlling the duty cycle of switch S4 to 0.64.

[0047] In the single output mode of the solar energy storage battery, the active switches S1 and S3 are in the normally off state, the active switch S2 is in the normally open state, and the active switch S4 is in the PWM mode. At this time, when the active switch S4 is turned on, the diodes D2 and D5 are turned on, the diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, the capacitor C2, and the capacitor C4, the capacitor C1 and the capacitor C3 are discharged, and the capacitor Co supplies power to the load R. When the active switch S4 is turned off, the diodes D2 and D5 are turned off, the diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, the inductor L1, the capacitor C2, and the capacitor C4 are discharged, the capacitor C1 and the capacitor C3 are charged, and the load R is supplied with power at the same time. At this time, the input and output voltage relationship is: Wherein, D4 is the duty cycle of the active switch S4.

[0048] Figure 3 In the present invention, in the single output mode of the energy storage battery, u ES =60V, D4=0.55, u o =400V simulation waveform. Figure 3 It can be seen that when the battery output voltage is 60V as the input source, the output voltage requirement of 400V at the load end is achieved by controlling the duty cycle of the switch S4 to 0.55.

[0049] In the photovoltaic dual output mode, the active switch S1 is in the normally on state, the active switch S2 is in the normally off state, and the active switches S3 and S4 are in the PWM mode. At this time, when the active switch S4 is turned on, the diodes D2 and D5 are turned on, the diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, the capacitor C2, and the capacitor C4, the capacitor C1 and the capacitor C3 are discharged, and the capacitor Co supplies power to the load R. When the active switch S4 is turned off, the active switch S3 is turned on, the diodes D2 and D5 are turned off, the diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, the inductor L1, the capacitor C2, and the capacitor C4 are discharged, the capacitor C1 and the capacitor C3 are charged, and the load R is supplied with power at the same time. In the stage where the active switch S4 is turned off, the active switch S3 is turned off, and the energy storage battery Battery stops charging. At this time, the input and output voltage relationship is: Where: D3, D4 are the duty cycles of active switches S3, S4 respectively.

[0050] Figure 4 In the photovoltaic dual output mode, u PV =48V, u ES =60V, D3=0.2, D4=0.53, u o =400V simulation waveform. Figure 4It can be seen that when the photovoltaic output voltage is 48V as the input source, by controlling the duty cycle of switch S3 at 0.2 and the duty cycle of switch S4 at 0.53, the requirements of 60V output voltage at the battery end and 400V output voltage at the load end are achieved.

[0051] In the light-storage dual output mode, the active switch S1 is in the normally on state, the active switch S3 is in the normally off state, the active switches S1, S2 and S4 are in the PWM mode, and the active switches S1 and S2 are complementary. At this time, when the active switch S4 is turned on, the diodes D2 and D5 are turned on, the diodes D1, D3, D4 and Do are turned off, the photovoltaic and energy storage batteries charge the inductor L1, capacitor C2, and capacitor C4 respectively, the capacitor C1 and capacitor C3 are discharged, and the capacitor Co supplies power to the load R. When the active switch S4 is turned off, the diodes D2 and D5 are turned off, the diodes D1, D3, D4 and Do are turned on, the photovoltaic, energy storage battery, inductor L1, capacitor C2, capacitor C4 are discharged, the capacitor C1 and capacitor C3 are charged, and the load R is supplied with power at the same time. At this time, the input and output voltage relationship is: Wherein, D2 and D4 are the duty cycles of active switches S2 and S4 respectively.

[0052] Figure 5 In the light-storage dual output mode, u PV =48V, u ES =60V, D2=0.44, D4=0.6, u o =400V simulation waveform. Figure 5 It can be seen that when the photovoltaic output voltage is 48V and the battery output voltage is 60V as dual input power sources, the output voltage requirement of 400V at the load end is achieved by controlling the duty cycle of switch S2 at 0.44 and the duty cycle of switch S4 at 0.6.

[0053] The present invention provides a photovoltaic-storage integrated multi-input high-gain DC-DC converter, which realizes energy interaction between the microgrid system and the AC power grid through the energy storage PCS. The energy storage and charging piles in the microgrid can directly interact with each other through the DC bus. It realizes the combination of photovoltaic and energy storage, realizes the selection of the deployment mode according to the use period, and improves the economy of the power grid.

Claims

1. A multi-input high-gain DC-DC converter with integrated light and storage, characterized in that: It includes a photovoltaic DC input source, an energy storage battery, switches S1-S4, diodes D1-D5, Do, capacitors C1-C4, Co, and an inductor L1; its connection form is as follows: one end of the photovoltaic DC input source is connected to the drain of the switch S1, and the source of the switch S1 is respectively connected to the source of the switch S2 and one end of the inductor L1; The drain of the switch S2 is connected to the positive electrode of the energy storage battery and the source of the switch S3 respectively, and the drain of the switch S3 is connected to the cathode of the diode D1; The other end of the inductor L1 is respectively connected to the anode of the diode D1, one end of the capacitor C1, the other end of the capacitor C2, the drain of the switch S4, and the anode of the diode D4; One end of the capacitor C2 is connected to the anode of the diode Do and the cathode of the diode D5 respectively; The other end of capacitor C1 is connected to the anode of diode D3 and the cathode of diode D2 respectively. The cathode of the diode D4 is connected to the anode of the diode D5 and one end of the capacitor C3 respectively; The other end of capacitor C3 is connected to the anode of diode D5 and one end of capacitor C4 respectively; the other end of capacitor C4 is connected to the anode of diode D2; The cathode of the diode Do is connected to one end of the capacitor Co; the other end of the capacitor Co is respectively connected to one end of the capacitor C4, the source of the switch S4, the negative electrode of the energy storage battery, and the other end of the photovoltaic DC input source; One end of the load R and the other end of the load R are connected to one end of the capacitor Co and the other end of the capacitor Co respectively.

2. According to claim 1, a multi-input high-gain DC-DC converter with integrated light and storage is characterized in that: The converter has four power supply modes: photovoltaic single output mode, energy storage battery single output mode, photovoltaic dual output mode, and photovoltaic-storage dual output mode.

3. According to claim 2, a multi-input high-gain DC-DC converter with integrated light and storage is characterized in that: In PV single output mode, the voltage gain is as follows: Among them, u PV represents the photovoltaic output voltage, and D4 represents the duty cycle of switch S4.

4. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the energy storage battery single output mode, the voltage gain is as follows: Among them, u ES Indicates the battery output voltage.

5. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In photovoltaic dual output mode, the voltage gain is as follows: Wherein, D3 represents the duty cycle of switch S3.

6. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the light-storage dual output mode, the voltage gain is as follows: Wherein, D2 represents the duty cycle of switch S2.

7. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the photovoltaic single output mode, switch S1 is in the normally on state, switches S2 and S3 are in the normally off state, and switch S4 is in the PWM mode; at this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R; when switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time.

8. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the single output mode of the energy storage battery, switches S1 and S3 are in the normally off state, switch S2 is in the normally open state, and switch S4 is in the PWM mode; at this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R; when switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time.

9. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the photovoltaic dual-output mode, switch S1 is in the normally-on state, switch S2 is in the normally-off state, and switches S3 and S4 are in the PWM mode; at this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, the photovoltaic DC input source charges the inductor L1, capacitor C2, and capacitor C4, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to the load R; when switch S4 is turned off, switch S3 is turned on, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, the photovoltaic DC input source, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and power is supplied to the load R at the same time; in the switch S4 off stage, switch S3 is turned off, and the energy storage battery Battery stops charging.

10. The optical-storage integrated multi-input high-gain DC-DC converter according to claim 2, characterized in that: In the photovoltaic-storage dual output mode, switch S1 is in the normally-on state, switch S3 is in the normally-off state, switches S1, S2 and S4 are in the PWM mode, and switches S1 and S2 are complementary turned on; at this time, when switch S4 is turned on, diodes D2 and D5 are turned on, diodes D1, D3, D4 and Do are turned off, photovoltaic and energy storage batteries charge inductor L1, capacitor C2, and capacitor C4 respectively, capacitor C1 and capacitor C3 are discharged, and capacitor Co supplies power to load R; when switch S4 is turned off, diodes D2 and D5 are turned off, diodes D1, D3, D4 and Do are turned on, photovoltaic, energy storage battery, inductor L1, capacitor C2, capacitor C4 are discharged, capacitor C1 and capacitor C3 are charged, and load R is supplied with power at the same time.

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