CN208198121U - Integrated hybrid energy source interface circuit topological structure for electric automobile - Google Patents

Abstract

The utility model discloses a topological structure of an integrated hybrid energy source interface circuit for an electric vehicle, comprising a bidirectional DC-DC interface circuit connecting a power battery unit and a DC bus bar. 1. A power battery unit composed of an inductance element and a switch network Interface circuit two between the supercapacitor unit and the bidirectional DC-DC interface circuit three connecting the supercapacitor unit and the DC bus. The topology structure of the utility model is different from the previous hybrid energy source interface circuit. Both the power battery and the super capacitor have a bidirectional DC-DC interface circuit connected to the DC bus, especially an interface circuit directly connected to the two energy sources. Second, the structure of the hybrid energy source system can be used to build a voltage equalization circuit for the power battery unit with the supercapacitor module forming the hybrid energy source as the core, so as to achieve the purpose of dynamic and static balance of the voltage of each series-connected power battery unit during the charging and discharging process , without additional auxiliary pressure equalization device.

Description

An Integrated Hybrid Energy Source Interface Circuit Topology for Electric Vehicles

technical field

The utility model relates to the field of energy storage technology and power supply, in particular to an integrated hybrid energy source interface circuit topology structure for electric vehicles, which is suitable for hybrid energy storage systems such as electric vehicles and urban rail transit.

Background technique

Restricted by the limited reserves of oil resources in the world and the increasing dependence of economic development on oil, the current shortage of oil resources has made the world's major automobile countries face huge challenges. From the perspective of environmental protection, fuel vehicles pollute the environment while consuming a large amount of oil resources. Under the environment of oil shortage, public awareness of environmental protection has increased significantly, government promotion, laws and regulations have been improved day by day, and people's recognition of electric vehicles has increased, electric vehicles are leading the development trend of the world's automobile industry. A reliable, efficient and low-cost power system is the key to electric vehicles, and the energy storage technology is one of the key factors restricting the development of electric vehicles at present. The power battery represented by lithium battery has excellent energy density, but the power density and cycle The indicators of life are general, especially the high current output itself will further reduce the cycle life. As a new type of energy storage element, supercapacitor has superior cycle life performance and outstanding power density, but its energy density is low, so it can be used as an auxiliary energy source, and a power battery with high energy density constitutes a hybrid energy source for electric vehicles. The advantages of a single energy storage make up for the shortcomings of traditional electric vehicles.

Normally, the hybrid energy storage system of an electric vehicle is composed of different energy storage units connected in a certain connection way through a specific interface circuit. The existing connection methods mainly include: 1. The power battery unit and the supercapacitor unit directly 2. The power battery unit is connected in series with the bidirectional DC-DC interface circuit and then connected in parallel with the supercapacitor unit on the DC busbar; 3. The supercapacitor unit is connected in series with the bidirectional DC-DC interface circuit and then connected in parallel with the power battery unit. DC bus; 4. The power battery unit and the supercapacitor unit are respectively connected in parallel to the DC bus through a bidirectional DC-DC interface circuit. Different connection topologies will not only directly affect the advantages of each energy storage unit, but also affect the effect of energy management. Therefore, different connection methods determine the different performances of hybrid energy storage systems.

The power battery unit is the core component of the hybrid energy source of electric vehicles, and the voltage level of a single power battery is low. To obtain a power battery pack with a high voltage level, multiple power battery cells must be connected in series. When the power battery is used in series, the inconsistency of the terminal voltage will affect the utilization rate and service life of the whole power battery unit, which limits its wide application. In the traditional hybrid energy source system, the connection mode of the energy storage unit is relatively simple, and there is a lack of research on the topology of the power electronic interface circuit responsible for the connection function, especially the existing topology does not consider the interaction between different energy storage units. Direct connection without direct interconnection simplifies the composition and control of the system, splits the integrity of the hybrid energy storage system, and restricts the complementary play of the advantages and characteristics of different energy storage sources.

Utility model content

The purpose of this utility model is to overcome the deficiencies of the existing hybrid energy source electric vehicle technology and provide an integrated hybrid energy source interface circuit topology for electric vehicles. The topology connection mode of the interface circuit can respectively realize two storage Independent control of the energy between the energy source and the DC bus, and the topology itself can not only realize the direct energy exchange of the two energy sources, but also realize the voltage equalization function of the power battery unit based on the principle of time-division multiplexing. Compared with the traditional hybrid energy source topology, it uses fewer components and realizes high-speed, high-efficiency, and low-cost power battery unit dynamic and static voltage equalization technology and the complementary play of the advantages of the two energy storages, effectively improving power. The service life of the battery unit and the power performance of the vehicle provide greater flexibility for regenerative braking energy recovery.

The technical solution adopted by the utility model: an integrated hybrid energy source interface circuit topology structure for electric vehicles, the topology structure includes:

Bidirectional DC-DC interface circuit 1 connecting the power battery unit and the DC bus,

The interface circuit between the power battery unit and the supercapacitor unit composed of inductive elements and switching networks II,

A bidirectional DC-DC interface circuit three connecting the supercapacitor unit and the DC bus;

The power battery unit and the supercapacitor unit realize independent control of energy exchange with the DC bus through the first bidirectional DC-DC interface circuit and the third bidirectional DC-DC interface circuit;

With the supercapacitor unit as the core and the interface circuit 2 directly connected to the two energy sources as the balance circuit, the voltage balance circuit of the power battery unit is constructed;

Use the non-destructive component supercapacitor as the medium of the voltage equalization of the power battery unit to realize the dynamic and static balance of the voltage of each series-connected power battery unit during the charging and discharging process;

According to the principle of time-division multiplexing, the interface circuit 2 directly connected to the two energy sources realizes the direct energy exchange between the power battery and the supercapacitor.

Beneficial effect:

1) Both the power battery and the supercapacitor have a bidirectional DC-DC interface circuit connected to the DC bus, which can realize independent control of the energy between the two energy storage and the DC bus.

2) The topology design of the interface circuit directly connecting the two energy sources enables the device itself to realize the voltage equalization function of the power battery unit without adding an additional voltage equalization device to the power battery unit. Therefore, the use of additional components is effectively reduced, the cost of the whole device is low, and the weight and volume are small.

3) The topology design of the interface circuit that directly connects two energy sources enables a direct "energy transfer channel" between the two energy sources, which can realize two-way exchange of energy, thereby complementing the advantages of the two energy storage characteristics and effectively improving energy efficiency. The cycle life of the power battery unit improves the output quality of the energy source to increase the power performance of the vehicle, and also provides greater flexibility and more optimization options for the recovery of regenerative braking energy.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the present invention.

Fig. 2a and Fig. 2b are schematic diagrams of voltage equalization work of the interface circuit.

Fig. 3a and Fig. 3b are flow charts of voltage equalization control of the interface circuit.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the utility model is described further.

As shown in Figure 1, an integrated hybrid energy source interface circuit topology for electric vehicles, the topology includes: a bidirectional DC-DC interface circuit-1 connecting the power battery unit and the DC bus, consisting of inductive elements and switches The interface circuit two 2 between the power battery unit and the supercapacitor unit formed by the network, and the bidirectional DC-DC interface circuit three 3 connecting the supercapacitor unit and the DC bus;

The power battery unit and the supercapacitor unit realize independent control of energy exchange with the DC bus through the bidirectional DC-DC interface circuit 1 and the bidirectional DC-DC interface circuit 3 respectively; with the supercapacitor unit as the core, the two The interface circuit 2 of this kind of energy source is a balance circuit, which constructs the voltage equalization circuit of the power battery unit; uses the non-destructive component supercapacitor as the medium of the power battery unit voltage equalization, and realizes that the voltage of each series-connected power battery unit is dynamically adjusted during the charging and discharging process. Static balance; according to the principle of time-division multiplexing, the interface circuit 2 directly connected to the two energy sources realizes the direct energy exchange between the power battery and the super capacitor.

Figure 2 is a working diagram of a single voltage equalization module composed of a supercapacitor and an interface circuit that equalizes the voltage of two adjacent battery cells during the charging and discharging process (the analysis does not lose generality, the internal resistance model of the battery is selected, and the assumption Internal resistance R _ESR1 >R _ESR2 ). Its charge and discharge voltage equalization control flow chart is shown in Figure 3.

When charging, the terminal voltage U _B1 >U _B2 , if the maximum value of the terminal voltage U _B1 exceeds the maximum allowable terminal voltage setting value U _a , the charging process will end; if the difference between the two voltages exceeds the maximum allowable voltage difference U _g , The purpose of voltage balance is achieved by changing the average value of the charging current of the two battery cells. That is, through the action of the switch, the battery with high terminal voltage is charged to the supercapacitor (state 1), and then the supercapacitor is discharged to the battery cell with low terminal voltage (state 2), then the terminal voltage of the two battery cells during the entire charging process They are:

U _B1 ＝E _B +R _ESR1 ×(ID×I ₁ )

U _B2 ＝E _B +R _ESR2 ×(I+(1-D)×I ₂ )

Until U _B1 -U _B2 ≤ U _g , the switch stops acting and pressure equalization ends. The schematic diagram of this process is shown in Figure 2a, and the flow chart of charging voltage equalization control is shown in Figure 3a.

When discharging, the terminal voltage U _B1 < U _B2 , if the minimum terminal voltage U _B1 is less than the minimum terminal voltage setting value U _b allowed for discharge, the discharge process will end; if the difference between the two voltages exceeds the maximum allowable voltage difference U _g , The purpose of voltage balance is still achieved by changing the average value of the charging current of the two battery cells. That is, through the action of the switch, let the battery with high terminal voltage charge the supercapacitor (state 1), and then discharge the supercapacitor to the battery cell with low terminal voltage (state 2), then the terminal voltage of the two battery cells during the entire discharge process They are:

U _B1 ＝E _B -R _ESR1 ×(I-(1-D)×I ₁ )

U _B2 ＝E _B -R _ESR2 ×(I+D×I ₂ )

Until U _B1 -U _B2 ≤ U _g , the switch stops acting and pressure equalization ends. A schematic diagram of this process is shown in Figure 2b. The flow chart of discharge voltage equalization control is shown in Figure 3b.

In order to further illustrate the specific working mode of the interface circuit involved in the utility model, an interface circuit directly connected to two energy sources for energy exchange is chosen as an example to illustrate the specific working principle of the utility model, that is, the two energy sources are connected through the interface During the energy exchange process of the circuit, the switching element is replaced by a power electronic switching tube MOSFET, as shown in Figure 3.

Figure 3a is the process of charging the supercapacitor, and the energy is transferred from the power battery to the supercapacitor. First turn on the switch tubes M ₁ and M ₂ , and the power battery charges the inductors L ₁ and L ₂ through these two switch tubes; then keep M ₁ on and turn off M ₂ at this time, the power battery and the inductors L ₁ and L _{2 The} electric energy stored in the supercapacitor is charged through M1 and _VD3 . The above process realizes the transmission of electric energy from the power battery to the supercapacitor.

Figure 3b is the process of discharging the supercapacitor, and the energy is transferred from the supercapacitor to the power battery. _First turn _on the switch tube M3, the _{supercapacitor} charges the power battery through _VD1 and M3, and at the same time the inductors L1 and _L2 store electric energy _; then turn off _M3 and the electric energy stored in the inductors L1 and L2 _passes through VD ₁ and VD ₃ continue to charge the power battery. The above process realizes the transmission of electric energy from the supercapacitor to the power battery.

It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the utility model, and these improvements and modifications should also be regarded as the protection scope of the utility model. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (1)

1. a kind of integrated hybrid energy sources interface circuit topological structure for electric car, it is characterised in that: topology knot Structure includes:

The bi-directional DC-DC interface circuit one of power battery unit and DC bus is connected,

By the interface circuit two between inductance element and switching network the power battery unit constituted and supercapacitive cell,

Connect the bi-directional DC-DC interface circuit three of supercapacitive cell and DC bus；

The power battery unit and supercapacitive cell pass through bi-directional DC-DC interface circuit one and bi-directional DC-DC interface respectively Circuit three realizes the independent control of the energy exchange between DC bus；

Using supercapacitive cell as core, to be directly connected to the interface circuits two of two kinds of energy sources as balancing circuitry, construction force The voltage balance circuit of battery unit；

The medium pressed using lossless element super capacitor as power battery unit realizes each concatenated power battery monomer electricity It is pressed in charge and discharge process and moves static equilibrium；

According to the principle of time-sharing multiplex, the interface circuit two for being directly connected to two kinds of energy sources realizes power battery and super capacitor two The DIRECT ENERGY in class energy storage source exchanges.