WO2018072384A1

WO2018072384A1 - Two-stage equalization charge system and equalization charge method for managing power battery set

Info

Publication number: WO2018072384A1
Application number: PCT/CN2017/077040
Authority: WO
Inventors: 谭晓军; 韦旺; 陈维杰; 康斌
Original assignee: 中山大学
Priority date: 2016-10-20
Filing date: 2017-03-17
Publication date: 2018-04-26
Also published as: CN106571659A

Abstract

Disclosed are a two-stage equalization charge system and an equalization charge method for managing a power battery set. Group equalization is first performed on a battery set, then charging equalization is performed on the battery set, so as to achieve entire equalization in the battery set, thereby prolonging the service life and improving the energy utilization rate of the battery set as well as improving the equalization time efficiency of the battery set.

Description

Title of Invention: Two-stage Equilibrium Charging System for Power Battery Management and Equalization Charging Method

Technical field

[0001] The present invention relates to the field of battery equalization charging technology, and in particular to a two-stage equalization charging system applied to automotive power battery management.

Background technique

[0002] At present, batteries for electric vehicles mainly include high-performance batteries such as nickel-hydrogen, lead-acid, and lithium ions. Compared with the first two commonly used batteries, lithium-ion batteries can achieve the same capacity, the battery size and weight are smaller, and the lithium-ion battery has more obvious advantages in terms of charging speed and anti-memory effect. Lithium-ion battery batteries have a discharge voltage of less than 5V. In actual use, they are often connected in series to form a battery pack. Due to the limited manufacturing process, uneven material and different environments, the battery pack will have some differences after using it for a while. As the number of charge and discharge cycles of the battery pack increases, the battery inconsistency becomes larger and larger, and overcharge and overdischarge will occur, which seriously affects battery life. Therefore, lithium-ion battery packs must have an equalization system to balance the above inconsistencies.

[0003] The equalization control of the power battery pack is divided into a dissipative type equalization and a non-dissipative type equalization, and the dissipative type equalization dissipates the higher energy battery through the resistor in the form of energy dissipation, and the method has a simple structure, but causes Energy is wasted, and energy is consumed in the form of heat, which tends to cause the ambient temperature to be too high. The non-dissipative equalization control redistributes the energy of the battery pack by means of energy transfer, so that the battery pack is balanced. The energy utilization rate of the method is high, but the number of battery cells is large, the energy transmission is long, and the control is complicated. Affects the balance of daytime efficiency.

technical problem

[0004] The object of the present invention is to solve the deficiencies of the prior art, and provide a two-stage equalization charging system and a balanced charging method for power battery management, improve energy utilization of the battery pack, and improve equalization efficiency. .

Problem solution Technical solution

The present invention achieves the above objects in this way:

[0006] A two-stage equalization charging system and an equalization charging method for power battery management, dividing a battery pack into a plurality of battery groups, further comprising a battery pack charger and an intra-group equalization circuit, wherein the intra-group equalization circuit includes A voltage monitoring unit and a battery equalization unit for detecting each battery in the battery group; the equalization process of the battery group includes the following steps:

[0007] a voltage monitoring unit detects the voltage of each battery, obtains the average voltage of the battery group, sets the equalization threshold, when the voltage is higher than the sum of the average voltage and the threshold, the battery is the battery that performs the discharge, and is lower than the average voltage The battery with the difference between the thresholds is a battery for performing charging, and the intra-group equalization circuit connects the battery that performs the discharge with the battery that performs the charging, and performs intra-group equalization until the absolute difference between the voltage of the battery and the average voltage in the battery group is absolute. The value is less than the threshold, and step b is performed;

[0008] b battery pack charger to charge the battery pack, the voltage monitoring unit detects the voltage of each battery, when one of the battery pack is full, stop charging, and perform step c;

[0009] c. Repeat step a until the battery pack completes the equalization.

[0010] wherein, in step c, it is determined that all battery groups complete the equalization condition: the voltage monitoring unit detects the voltage of each battery, obtains the average voltage of the battery group, and the voltage and average voltage of each battery in the battery group The absolute value of the difference is less than the threshold value, and the battery group is determined to complete the equalization.

[0011] wherein, there is also a central control unit, the battery pack charger and the intra-group equalization circuit are connected to the central control unit via the communication bus, and the step a吋 is performed, and the voltage monitoring unit detects the obtained voltage data of each battery through the communication bus. Transfer to the central control unit, the central control unit calculates the average voltage of the battery pack and sets the equalization threshold, and outputs a control signal to the battery equalization unit to perform intra-group equalization; when the step a is completed, the central control unit outputs a control signal to the battery. The group charger performs step b.

[0012] wherein the intra-group equalization circuit is further provided with a heat control system, which comprises a temperature sensor and a fan, and controls the working state of the fan according to the temperature sensor detecting the temperature of the battery group.

[0013] wherein, the battery equalization unit comprises a transformer, an equalization control chip, and a control switch, and the primary side of each transformer is connected in series with the switch terminal, and is connected to a battery in the battery group, and each of the transformers is connected. After the series control of the switch is connected in parallel with other transformers, the control terminal of the control switch is connected to the corresponding output port of the equalization control chip. Advantageous effects of the invention

Beneficial effect

[0014] The beneficial effects of the present invention are: The two-stage equalization charging system of the present invention achieves overall balance in the battery pack by first balancing the battery component groups and then performing equalization of the battery, thereby improving the service life and energy of the battery pack. The utilization rate also improves the balanced dipole efficiency of the battery pack.

Brief description of the drawing

DRAWINGS

[0015] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

1 is a schematic structural diagram of a two-stage equalization charging system;

2 is a circuit schematic diagram of an intra-group equalization circuit;

3 is a structural schematic diagram of a battery pack charger;

4 is a working flow chart of a two-stage equalization charging system.

Embodiments of the invention

[0020] The present invention will be further described below in conjunction with FIGS. 1 through 4 and specific embodiments.

[0021] As shown in FIG. 1 , a two-stage equalization charging system and a balanced charging method for power battery management, dividing a battery pack into a plurality of battery groups, and further comprising a central control unit and a plurality of The charged battery pack charger and a number of intra-group equalization circuits for the first stage equalization of the battery pack. The battery pack charger and the intra-group equalization circuit are connected to the central control unit via a communication bus. The battery pack charger includes a charger body and a charging socket, and the intra-group equalization circuit is a non-dissipative type equalization, and includes a voltage monitoring unit, a battery equalization unit, and a balanced socket. The battery combinations are grouped according to the characteristics of the voltage monitoring unit and the battery equalization unit. Each group of equalization circuits is connected to the battery pack by means of a balanced socket, monitors the voltage signal of each battery in the group, and transmits the battery voltage signal to the central control unit via the communication bus. The central control unit equalizes the battery pack according to the corresponding strategy. After the first level of equalization is completed, a corresponding control command is sent to the group charger through the communication bus to start charging equalization.

[0022] The communication bus can adopt a CAN bus, and the voltage monitoring unit can adopt a chip LTC6804, The LTC3300 can be used as the equalization control chip for the intra-group equalization circuit.

[0023] The charging socket, the negative electrode is connected to the negative electrode of the battery group, the positive electrode is connected to the positive electrode of the battery group; the equalizing socket, the negative electrode is connected to the negative electrode of the battery group, and the other is connected to the positive electrode of the battery unit single battery in turn.

[0024] wherein the intra-group equalization circuit is a first-level equalization, comprising one LTC6804-based voltage monitoring unit, two LTC3300-based battery equalization units, and an equalization socket. Each of the LTC6804-based voltage monitoring units can detect up to 12 single cells, and each LTC3300-based voltage equalization unit can control charging and discharging of the battery cells within 6 cells. Therefore, the equalization system has 12 batteries. The grouping is performed, and the equalization socket is connected to the battery group to perform an equalization operation.

[0025] Further, as shown in FIG. 2, the first-stage balanced topology structure is corresponding to 6 transformers for the 1-6 batteries, and the primary side of the transformer is connected to the single battery, and the secondary side of the transformer corresponds to the entire battery group, 1- The 6th battery can transfer energy to the 1-12th battery or transfer the energy from the 1-12th battery to the single battery; the 7-12th battery corresponds to the other six transformers, the primary side of the transformer is connected to the single battery, and the transformer is replaced. The battery corresponds to the 7-12 battery, and the 7- 12 battery can achieve the energy balance of the 7-12 battery itself.

[0026] Further, the two-stage equalization charging system further includes a thermal control system connected to the central control unit, the thermal control system includes a fan and a temperature sensor disposed in the battery pack, and the temperature sensor is configured to monitor the battery pack. The temperature and the temperature signal are transmitted to the central control unit. The central control unit returns the corresponding control signal through the control bus to control the working state of the fan, including the fan's switching speed and speed.

[0027] Further, as shown in FIG. 3, the battery pack charger further includes an EMI filter module, a rectification filter circuit, a dual-tube forward circuit, an LC filter sampling circuit, and a microcontroller; an EMI filter module input terminal and a city Electrically connected, the output end is connected to the rectifying and filtering circuit; the double-tube forward-exciting circuit comprises a transformer, the transformer comprises a primary side coil and a secondary side coil; the primary side coil is connected with the output end of the rectifying and filtering circuit, and further comprises a switching inverter, The Shaoguan inverter consists of Dl, D2, Ql, Q2, and the inverter receives the control signal from the microcontroller to control the on/off of the double-switch forward circuit; the LC filter sampling circuit is connected to the secondary side of the transformer. The output of the LC filter sampling circuit is connected to the charging socket of the charger. The microcontroller can be a single chip microcomputer, A RM, DSP, or the like.

[0028] Further, the battery pack charger LC sampling circuit includes a voltage sampling point and a current sampling point, which are fed back to the microcontroller through current and voltage sampling, and the microcontroller sends a corresponding signal according to the feedback signal. The PWM wave controls the on and off of the bypass tube to realize the stability of the feedback type power supply circuit Work.

[0029] Further, as shown in FIG. 4, the two-stage equalization charging system has an equalization strategy:

[0030] Step a: The batteries Nos. 1 to 6 are equalized with the average voltage Uavg of the batteries No. 1 to No. 12, and the batteries of Nos. 7 to 12 are equalized with the average voltage Uavg of the batteries No. 7 to No. 12, if the voltage is Above the equilibrium target and the threshold U1, the battery performs a discharge operation. If the voltage is lower than the difference between the equalization target and the threshold U1, the battery performs a charging operation, and the first level equalization is completed by the intra-group equalization circuit, and proceeds to step b;

[0031] Step b _: using a battery pack charger to separately charge the battery pack until any battery in the group is full, proceeds to step c;

[0032] Step c: If the battery voltage U in the battery group and the average voltage of the group are less than the set threshold Ul, the two-stage equalization charging is completed, and the equalization operation ends. Otherwise skip to step a for the next round of equalization.

Claims

Claim

[Claim 1] A two-stage equalization charging system and a balanced charging method for power battery management, characterized in that: dividing a battery pack into a plurality of battery packs, further comprising a battery pack charger and an intra-group equalization circuit, The intra-group equalization circuit includes a voltage monitoring unit for detecting each battery in the battery group, and a battery equalization unit. The equalization process of the battery group includes the following steps: a. The voltage monitoring unit detects the voltage of each battery to obtain the average voltage of the battery group. , setting an equalization threshold, wherein the battery whose voltage is higher than the sum of the average voltage and the threshold is a battery that performs discharge, and the battery that is lower than the average voltage and the threshold is a battery that performs charging, and the battery within which the equalization circuit performs discharge Connected to the battery that performs charging, and performs intra-group equalization until the absolute value of the difference between the voltage and the average voltage of all the batteries in the battery group is less than the threshold, and step b is performed;

b. The battery pack charger charges the battery pack, the voltage monitoring unit detects the voltage of each battery, stops charging when one of the battery packs is fully charged, and performs step c c. Repeat step a until the battery pack completes the equalization.

[Claim 2] The two-stage equalization charging system and the equalization charging method for power battery management according to claim 1, wherein: in step c, it is determined that all battery groups complete the equalization condition: voltage monitoring unit The voltage of each battery is detected to obtain the average voltage of the battery group. When the absolute value of the difference between the voltage of each battery in the battery group and the average voltage is less than the threshold, the battery group is determined to complete the equalization.

[Claim 3] The two-stage equalization charging system and the equalization charging method for power battery management according to claim 1, wherein: a central control unit, a battery pack charger, and an intra-group equalization circuit are further provided. The communication bus is connected to the central control unit, and in step a吋, the voltage data of each battery obtained by the voltage monitoring unit is transmitted to the central control unit through the communication bus, and the central control unit calculates the average voltage of the battery group and sets the equalization threshold. And outputting a control signal to the battery equalization unit to perform intra-group equalization; when the step a is completed, the central control unit outputs a control signal to the battery pack charger to perform step b.

[Claim 4] A two-stage equalization charging system for power battery management according to claim 1 The charging method is characterized in that: the intra-group equalization circuit further comprises a heat control system, which comprises a temperature sensor and a fan, and controls the working state of the fan according to the temperature sensor detecting the temperature of the battery group.

[Claim 5] The two-stage equalization charging system and the equalization charging method for power battery management according to claim 1, wherein: the battery equalization unit comprises a transformer, an equalization control chip, and a control switch, each The primary side of the transformer is connected in series with the shut-off terminal of the switch and connected to a battery in the battery group. The secondary side of each transformer is connected in series with the shut-off terminal of the switch, and then connected in parallel with other transformers to control the control terminal connection. Equalize the corresponding output port of the control chip.