阅读说明：本技术 一种具有完备均衡支路的电压均衡电路及控制方法 (Voltage equalization circuit with complete equalization branch and control method ) 是由 张小兵 周国华 冷敏瑞 田庆新 徐顺刚 于 2019-10-23 设计创作，主要内容包括：本发明公开了一种具有完备均衡支路的电压均衡电路及控制方法。均衡电路包括四个以上结构相同的开关单元,每个开关单元配置一个电池；开关单元包括两个MOS管,电池的正极连接到第一MOS管的漏极,第一MOS管的源极连接到第二MOS管的漏极,第二MOS管的源极连接到电池的负极；所有开关单元所配置的电池串联；任意两个开关单元的第一MOS管的源极之间均连接有一条均衡支路；每个开关单元的第一MOS管的源极还分别连接有一条均衡支路,这些均衡支路的另一端相互连接。本发明可实现电池组内所有电池间的能量传输,快速地均衡电池电压。在结构上具有对称性,均衡速度与电池电压的不均衡分布无关,且均衡速度不随电池数量的增加而变慢。(The invention discloses a voltage equalization circuit with a complete equalization branch circuit and a control method. The equalizing circuit comprises more than four switch units with the same structure, and each switch unit is provided with a battery; the switch unit comprises two MOS tubes, the anode of the battery is connected to the drain electrode of the first MOS tube, the source electrode of the first MOS tube is connected to the drain electrode of the second MOS tube, and the source electrode of the second MOS tube is connected to the cathode of the battery; the batteries configured by all the switch units are connected in series; a balance branch is connected between the source electrodes of the first MOS tubes of any two switch units; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balance branch, and the other ends of the balance branches are mutually connected. The invention can realize the energy transmission among all the batteries in the battery pack and quickly balance the battery voltage. The structure has symmetry, the equalizing speed is independent of the unbalanced distribution of the battery voltage, and the equalizing speed does not become slow along with the increase of the number of the batteries.)

1. A voltage equalization circuit with a complete equalization branch circuit is characterized by comprising more than four switch units with the same structure, wherein each switch unit is provided with a battery; the switch unit comprises two MOS tubes, the anode of the battery is connected to the drain electrode of the first MOS tube, the source electrode of the first MOS tube is connected to the drain electrode of the second MOS tube, and the source electrode of the second MOS tube is connected to the cathode of the battery; the batteries configured by all the switch units are connected in series;

a balance branch is connected between the source electrodes of the first MOS tubes of any two switch units;

the source electrode of the first MOS tube of each switch unit is also respectively connected with a balance branch, and the other ends of the balance branches are mutually connected.

2. A voltage equalizing circuit with a complete equalizing branch as in claim 1 wherein said equalizing branch is a single capacitor branch.

3. The voltage equalization circuit having a completed equalization branch as claimed in claim 1, wherein said equalization branch is a capacitor and inductor series branch.

4. The voltage equalizing circuit with complete equalizing branches as claimed in claim 1, wherein one equalizing branch is connected between the sources of the first MOS transistors of any two switch units, and the equalizing branch is a single-capacitor branch; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balancing branch, the other ends of the balancing branches are mutually connected, and the balancing branches are capacitor and inductor series branches.

5. The voltage equalizing circuit with complete equalizing branches as claimed in claim 1, wherein an equalizing branch is connected between the sources of the first MOS transistors of any two switch units, and the equalizing branch is a capacitor-inductor series branch; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balancing branch, the other ends of the balancing branches are mutually connected, and the balancing branch is a single-capacitor branch.

6. The method of claim 2, wherein let V be a complete equalization branch_GS1Controlling the first MOS transistor of each switching unit, V_GS2The second MOS tube controls each switch unit; the V is_GS1And V_GS2Is a pair of PWM signals with fixed frequency, complementary duty ratio and dead time.

7. A method for controlling a voltage equalizing circuit with complete equalizing branches according to any of claims 3-5, characterized in that let V be_GS1Controlling the first MOS transistor of each switching unit, V_GS2The second MOS tube controls each switch unit; the V is_GS1And V_GS2The PWM signal is a pair of PWM signals with fixed frequency, complementary duty ratio and dead time, and the frequency of the PWM signals is the resonance frequency of a capacitor and inductor series branch circuit.

Technical Field

The invention relates to the technical field of lithium battery/super capacitor voltage equalization, in particular to a voltage equalization circuit with a complete equalization branch circuit and a control method.

Background

Lithium batteries and super capacitors are often used as energy storage elements in pure electric vehicles and new energy power generation. However, since the voltage of a single lithium battery/super capacitor (hereinafter, the lithium battery and the super capacitor are collectively referred to as a battery for convenience of description) is generally low, a large number of battery cells are often required to be connected in series to meet the large voltage requirement of the load. Due to production and manufacturing reasons, parameters such as internal resistance, voltage, self-discharge rate and the like of each battery monomer are different, and the difference can cause the voltage inconsistency of the battery during charging and discharging. The inconsistency of the voltages among the batteries wastes the available capacity of the battery pack, accelerates the aging of the batteries, and shortens the service life of the batteries. In order to solve the problem of inconsistency of the battery cells, an equalization circuit needs to be added into the battery pack.

Existing equalization circuits mainly include energy-dissipative and non-energy-dissipative types. The energy dissipation type equalization circuit consumes energy in the high-voltage battery by using energy consumption elements such as resistors and the like so as to realize equalization of battery voltage in the battery pack. The mode has low cost and small volume, but the energy waste is serious. The non-dissipative equalization circuit utilizes non-energy-consuming elements such as capacitors and inductors as energy transmission media to realize the transmission of energy from the high-voltage battery to the low-voltage battery. Among them, the equalizing circuit using the capacitor as the energy transfer medium has been widely studied due to the simple circuit structure and the simple control. The single-capacitor equalization circuit is the simplest in structure, but the equalization circuit can only achieve energy transmission between two batteries at the same time, and the equalization speed is low. The traditional switched capacitor equalization circuit comprises a single-layer switched capacitor equalization circuit, a double-layer switched capacitor equalization circuit, a chain-shaped switched equalization circuit and the like, energy can be transmitted among a plurality of batteries at the same time, but the equalization speed of the traditional switched capacitor equalization circuit changes along with the unbalanced voltage distribution of the batteries, and the equalization speed of the traditional switched capacitor equalization circuit decreases along with the increase of the number of the batteries.

Disclosure of Invention

The invention aims to provide a voltage equalization circuit with a complete equalization branch circuit and a control method.

The technical scheme for realizing the purpose of the invention is as follows:

a voltage equalization circuit with a complete equalization branch comprises more than four switch units with the same structure, wherein each switch unit is provided with a battery; the switch unit comprises two MOS tubes, the anode of the battery is connected to the drain electrode of the first MOS tube, the source electrode of the first MOS tube is connected to the drain electrode of the second MOS tube, and the source electrode of the second MOS tube is connected to the cathode of the battery; the batteries configured by all the switch units are connected in series; a balance branch is connected between the source electrodes of the first MOS tubes of any two switch units; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balance branch, and the other ends of the balance branches are mutually connected.

Further, the equalizing branch is a single-capacitor branch.

Further, the equalizing branch is a capacitor and inductor series branch.

Furthermore, a balancing branch is connected between the source electrodes of the first MOS transistors of any two switch units, and the balancing branch is a single-capacitor branch; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balancing branch, the other ends of the balancing branches are mutually connected, and the balancing branches are capacitor and inductor series branches.

Furthermore, a balancing branch is connected between the source electrodes of the first MOS transistors of any two switch units, and the balancing branch is a capacitor and inductor series branch; the source electrode of the first MOS tube of each switch unit is also respectively connected with a balancing branch, the other ends of the balancing branches are mutually connected, and the balancing branch is a single-capacitor branch.

The equalizing branch circuit is a circuit with a single capacitor branch circuit, and the control method comprises the following steps: let V_GS1Controlling the first MOS transistor of each switching unit, V_GS2The second MOS tube controls each switch unit; the V is_GS1And V_GS2Is a pair of PWM signals with fixed frequency, complementary duty ratio and dead time.

The equalizing branch comprises a capacitor and inductor series branch, and the control method comprises the following steps: let V_GS1Controlling the first MOS transistor of each switching unit, V_GS2The second MOS tube controls each switch unit; the V is_GS1And V_GS2The PWM signal is a pair of PWM signals with fixed frequency, complementary duty ratio and dead time, and the frequency of the PWM signals is the resonance frequency of a capacitor and inductor series branch circuit.

The invention has the beneficial effects that: the invention provides all possible direct and indirect equalization paths for any two batteries, i.e. the equalization paths are complete. The direct equalization path is composed of a single equalization branch, and the indirect equalization path is composed of two equalization branches which are connected in series. Based on a complete balancing path, the invention can realize energy transmission among all batteries in the battery pack and quickly balance the battery voltage. Meanwhile, the invention has symmetry in structure, each battery has the same number of equalization paths, and the number of equalization paths increases with the increase of the number of batteries. Therefore, the equalizing speed of the invention is irrelevant to the unbalanced distribution of the battery voltage, and the equalizing speed does not become slow along with the increase of the number of the batteries.

Drawings

FIG. 1 is a circuit diagram of the equalizing branch of the present invention as a single capacitor branch;

FIG. 2 is a circuit configuration diagram of embodiment 1;

FIG. 3a shows the operating state I of example 1;

FIG. 3b shows the operating state II of example 1;

FIG. 4 shows the capacitance C under the condition of voltage imbalance 1 in the embodiment 1_2,1Voltage and current simulation waveforms of (1);

FIG. 5a is a simulated waveform of the cell voltage in case of voltage imbalance 1 of example 1;

FIG. 5b is a simulated waveform of the cell voltage in case of voltage imbalance 2 of example 1;

FIG. 5c is a simulated waveform of the cell voltage in case of voltage imbalance 3 of example 1;

FIG. 6 is a circuit configuration diagram of embodiment 2;

FIG. 7 shows a capacitor C according to example 2_2,1Voltage and current simulation waveforms of (1);

fig. 8 is a simulation waveform of the battery voltage of example 2.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

A voltage equalization circuit with complete equalization branch comprises batteries B connected in series in sequence₁,B₂,…,B_nWherein n is a positive integer greater than or equal to 4; the device also comprises n groups of MOS tubes and n (n +1)/2 equalizing branches.

Batteries B connected in series in sequence₁,B₂,…,B_nAnd the lithium battery (module) or the super capacitor (module) can be used.

The equalizing branch can be a single-capacitor branch, a series branch of a capacitor and an inductor, or an equalizing branch with other structures.

Fig. 1 is a circuit diagram of a voltage equalization circuit with a complete equalization branch, in which the equalization branch is a single capacitor branch.

As shown in FIG. 1, and a battery B_iThe parallel ith group of MOS tubes comprises two MOS tubes S_i1And S_i2. First MOS transistor S_i1And a second MOS transistor S_i2After being connected in series, the electrolyte is then mixed with a battery B_iParallel connection; the concrete connection mode is as follows: first MOS transistor S_i1Drain electrode of and battery B_iIs connected with the anode of the second MOS transistor S_i2Source electrode of and battery B_iThe negative electrodes are connected; first MOS transistor S_i1Source electrode of and the second MOS transistor S_i2Is connected with the drain electrode, and the connection point of the drain electrode is an equalizing branch connection point b_i(ii) a Each battery B_iCorresponding to a balanced branch connection point b_i(ii) a Wherein i is 1,2, …, n.

The n (n +1)/2 single-capacitor branches can be divided into two types:

the first method comprises the following steps: each single-capacitor branch is connected with the connection point of the balance branch corresponding to any two batteries; n (n-1)/2 strips. The detailed connection mode is as follows: capacitor C_j,k(j＝2,3,…,n；k＝1,2,…,n-1；j>k) One end of the formed balance branch is connected with a battery B_jCorresponding balanced branch connection point b_jAnd the other end is connected with a battery B_kCorresponding balanced branch connection point b_k(ii) a The balance branch is a battery B_jAnd B_kA single branch equalization path between;

and the second method comprises the following steps: one end of each single-capacitor branch is connected with a balanced branch connection point corresponding to a battery, and the other end of each single-capacitor branch is connected with an auxiliary connection point b₀(ii) a N in total; the detailed connection mode is as follows: capacitor C_0,iOne end of the equalizing branch (i-1, 2, …, n) is connected with a battery B_iCorresponding balanced branch connection point b_iAnd the other end is connected to an auxiliary connection point b₀(ii) a Wherein, the capacitor C_0,j(j ═ 2,3, …, n) and capacitor C_0,k(k＝1,2,…,n-1；j>k) The formed balance branches are connected to form a battery B_jAnd B_kAn equalization path comprising two equalization branches;

and the equalizing branch connection point corresponding to each battery is connected with the n equalizing branches.

The equalizing branch circuit is a voltage equalizing circuit with a complete equalizing branch circuit and a capacitor and inductor series branch circuit, and the structure of the equalizing branch circuit is similar to that of the equalizing branch circuit which is a single capacitor branch circuit, so that various circuits can be formed. Firstly, replacing all single capacitor branches in the structure with capacitor and inductor series branches; secondly, the first type of single capacitor branch is replaced by a capacitor and inductor series branch, and the other single capacitor branches are still single capacitor branches; thirdly, the single capacitor branch of the second type is replaced by a capacitor and inductor series branch, and the other branches are still single capacitor branches. When the equalizing branch is a capacitor and inductor series branch, the voltage difference between the battery and the capacitor can be increased through the resonance of the capacitor and the inductor, so that the equalizing current is increased, and the equalizing speed is increased; meanwhile, the switching frequency of the equalizing circuit is adjusted to be close to the resonant frequency of the capacitor and inductor series branch, so that the current flowing through the MOS tube at the moment of on-off can be reduced, the circuit loss is reduced, and the equalizing efficiency is improved. Further, when all the equalizing branches are capacitor and inductor series branches, zero current switching of all MOS tubes in the circuit can be realized, and the equalizing efficiency of the circuit is obviously improved.

The control method of the voltage equalization circuit with the complete equalization branch circuit comprises the following steps: using a pair of fixed-frequency, complementary-duty-ratio PWM signals V with dead time_GS1And V_GS2Controlling the n groups of MOS tubes, wherein: v_GS1Controlling the first MOS transistor S in each group of MOS transistors_i1，V_GS2Controlling the second MOS transistor S in each group of MOS transistors_i2。

In the control method, when the equalizing branch is a single-capacitor branch, the switching frequency of the control signal is not definitely limited and can be set as required; when the equalizing branch is a capacitor and inductor series branch, the switching frequency of the control signal needs to be set to the resonant frequency of the capacitor and inductor series branch or a frequency close to the resonant frequency in order to ensure the equalizing performance of the circuit.