CN108667058A - A chain energy storage system structure that can eliminate secondary pulsation - Google Patents

Abstract

The invention discloses a chain type energy storage system structure capable of eliminating secondary pulsation, wherein a group of battery packs B11 is connected in series with an inductor L1 and then connected in parallel with another group of battery packs B12 to form a battery unit, two ends of the battery unit are connected with two ends of a half-bridge structure, an upper bridge arm and a lower bridge arm of the half-bridge structure are respectively provided with a MOSFET power tube S11 and S12, the MOSFET power tubes S11 and S12 are respectively connected with diodes D11 and D12 in an anti-parallel mode, a plurality of battery units connected with the half-bridge structure are connected in series, then the battery units are connected in series with an inductor L0 and then connected in parallel with a capacitor C0, and two ends of the capacitor C0 are respectively connected with an inverter of the half-bridge structure.

Description

A chain energy storage system structure that can eliminate secondary pulsation

technical field

The invention relates to the technical field of battery systems, in particular to a chain-type energy storage system structure capable of eliminating secondary pulsation.

Background technique

For battery-based chain energy storage systems, effective grid connection to the DC side (battery pack) is required. At present, the existing structural design can be roughly divided into two categories. One is to directly cascade the battery pack with the inverter to achieve grid connection. On the one hand, this requires the battery pack to have a higher voltage level, requiring a large number of batteries to be connected in series, which affects the reliability of the system. On the other hand, there is a secondary pulsation power when the battery pack exchanges energy with the grid, which will endanger the battery life. The traditional topology uses a large capacitor in parallel with the battery pack to absorb the secondary pulsation, but it puts forward high requirements for the size of the capacitor. The second type is to cascade the battery pack with the DC-DC converter, and realize grid connection through the inverter. The current inverter and DC-DC converter both use a full-bridge structure, which requires more The IGBT switch tube, on the one hand, complicates the control method, and on the other hand, increases the cost.

Contents of the invention

The purpose of the present invention is to provide a chained energy storage system structure capable of eliminating secondary pulsation in order to remedy the defects of the prior art.

The present invention is achieved through the following technical solutions:

A chain-type energy storage system structure that can eliminate secondary pulsation. A battery pack B11 is connected in series with an inductor L1 and then connected in parallel with another battery pack B12 to form a battery unit. The two ends of the battery unit are connected to the half-bridge structure The two ends of the half-bridge structure are connected to each other. There are MOSFET power transistors S11 and S12 respectively on the upper and lower bridge arms of the half-bridge structure. The MOSFET power transistors S11 and S12 are respectively anti-parallel with diodes D11 and D12. The battery cells are connected in series, and then a capacitor C0 is connected in parallel with an inductor L0 in series, and both ends of the capacitor C0 are respectively connected to an inverter with a half-bridge structure for grid connection. When the switch tube of the upper half-bridge arm of each battery unit is turned on, the battery unit is connected to the whole system, and when the lower half-bridge arm is turned on, the battery unit is cut off. balanced. By monitoring the state of charge (SOC) of the battery pack, the on-off time of the upper half-bridge switch tube of each unit is controlled. Since the off-time is very short, the voltage at both ends of the capacitor cannot change suddenly, and effective grid connection can be realized. At the same time, since the battery pack passes through the equivalent BUCK circuit and then exchanges energy with the grid, it can filter out secondary pulses and help extend battery life.

The upper and lower bridge arms of the inverter with the half-bridge structure have a MOSFET power tube S1 and S2 respectively, and the MOSFET power tubes S1 and S2 are connected in antiparallel with diodes D1 and D2 respectively.

Aiming at the deficiencies of the prior art, the present invention proposes a chain-type energy storage system structure that can eliminate the secondary pulsation. The chain-type energy storage system structure is composed of an equivalent buck/boost bidirectional converter and a half-bridge inverter. The battery pack The DC-DC converter with cascaded half-bridge structure charges the capacitor on the DC bus when the upper half-bridge arm is turned on. When the lower switching tube is turned on, each battery unit is balanced within the unit through the inductance, and the capacitor on the DC bus clamps the output voltage of the DC side, and then cascaded with the inverter so that the DC side can be connected to the grid. The on-off control strategy of the upper and lower switch tubes is determined by the state of charge (SOC) of each battery pack, which can achieve the balance of each battery pack and further prolong the service life of the battery pack.

The advantages of the present invention are: the present invention avoids the direct energy exchange between the battery pack and the grid, so that the battery pack is not affected by the secondary pulsation; the half-bridge structure is adopted, which reduces the number of IGBT switch tubes and simplifies the control method at the same time The cost is reduced; the balance of each group of batteries can be realized through a relatively simple control method, and the service life of the batteries can be prolonged.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Detailed ways

As shown in Figure 1, a chain-type energy storage system structure that can eliminate secondary pulsation. A battery pack B11 is connected in series with an inductor L1 and then connected in parallel with another battery pack B12 to form a battery unit. The two ends are connected to the two ends of the half-bridge structure. There are MOSFET power transistors S11 and S12 respectively on the upper and lower bridge arms of the half-bridge structure. The battery cells connected in the half-bridge structure are connected in series, and then a capacitor C0 is connected in parallel with an inductor L0 in series. Both ends of the capacitor C0 are also connected to a half-bridge inverter for grid connection. When the switch tube of the upper half-bridge arm of each battery unit is turned on, the battery unit is connected to the whole system, and when the lower half-bridge arm is turned on, the battery unit is cut off. balanced. By monitoring the state of charge (SOC) of the battery pack, the on-off time of the upper half-bridge switch tube of each unit is controlled. Since the off-time is very short, the voltage at both ends of the capacitor cannot change suddenly, and effective grid connection can be realized. At the same time, since the battery pack passes through the equivalent BUCK circuit and then exchanges energy with the grid, it can filter out secondary pulses and help extend battery life.

The upper and lower bridge arms of the inverter with the half-bridge structure have a MOSFET power tube S1 and S2 respectively, and the MOSFET power tubes S1 and S2 are connected in antiparallel with diodes D1 and D2 respectively.

As shown in Figure 1, the chain-type energy storage system that can eliminate the secondary pulsation is composed of an equivalent buck/boost bidirectional converter and a half-bridge inverter, where C0 is the energy storage capacitor, L0 is the energy storage inductance, S1 and S2 It is the power tube of the half-bridge inverter, and the capacities of C1 and C2 are equal. In the working state of the DC side supplying power to the grid, the bidirectional DC-DC half bridge module upper bridge arm switch S11, lower bridge arm diode D11 and inductor L0 form an equivalent buck circuit, giving the upper and lower half bridge switch tubes S11 and S12 complementary Control signal, when the upper switch tube is turned on, the battery pack will charge the DC bus C0, when the lower switch tube is turned on, each battery unit is balanced within the unit through the inductance, C0 clamps the output voltage of the DC side, so that the DC side can be Realize grid connection.

Claims (2)

1. a kind of system for chain type energy storage structure that can eliminate secondary pulsation, it is characterised in that：By one group of battery pack B11 series connection one A inductance L1 one battery unit of composition in parallel with another group of battery pack B12 progress again, by the both ends of battery unit and half-bridge knot The both ends of structure are connected, and there are one MOSFET power tubes S11, S12, MOSFET work(respectively on the upper and lower bridge arm of the half-bridge structure Rate pipe S11, S12 distinguishes anti-paralleled diode D11, D12, by it is multiple be connected with half-bridge structure after battery unit connect, C0 is connected in parallel with a capacitor after connecting again with an inductance L0, the both ends of capacitance C0 are also respectively connected with the inversion of a half-bridge structure Device carries out grid-connected.

2. a kind of system for chain type energy storage structure that can eliminate secondary pulsation according to claim 1, it is characterised in that：Institute There are one MOSFET power tubes S1, S2, MOSFET power tubes S1, S2 respectively on the upper and lower bridge arm of the inverter for the half-bridge structure stated Anti-paralleled diode D1, D2 respectively.