TW201436420A - Active type battery electricity balancing control method - Google Patents

Abstract

The present invention is to provide an active type battery electricity balancing control method, according to the capacity and voltage of each battery to calculate the equilibrium energy electricity required by each cell, and developed charging mode, discharging mode and idle mode three kind of battery electricity balanced control method, achieved effectively prevent overcharge and over discharge cell.

Description

Active battery power balance control method

The invention relates to a battery power balance control method, in particular to a battery power balance control method mainly based on the capacity and voltage of each battery.

Since the voltage of a single battery is limited, it is necessary to connect a plurality of batteries in series to meet the demand voltage. Due to slight differences in the manufacturing process, the internal chemical reaction, electrolyte and plate deterioration of each battery after a period of use of the battery The difference will be larger and larger, which will affect the battery's charge and discharge capacity and power storage capacity, especially for batteries with poor performance, which will cause a vicious circle and fail to meet the standard life. This is because the battery is not balanced. The problem is that the battery life is shortened and the battery efficiency is lowered.

The current widely used response method is Battery Voltage Equalization, which aims to equalize the charge and discharge voltage of each battery of a series of battery packs, so that the voltage of the battery is maintained at the same voltage value, avoiding the battery. Overcharge and overdischarge occur; among them, the method of battery homogenization technology can be divided into passive and active.

The passive power balance technology has a parallel resistance equalization method and an overvoltage discharge equalization method. Parallel resistance equalization method is to directly connect the resistors in parallel to the battery to achieve the component flow. However, since the resistors are permanently connected in parallel to the battery, excessive energy is consumed, and the overvoltage discharge equalization method mainly improves the parallel connection. The resistance homogenization method has the disadvantage of excessive energy consumption, but it still has the problem of heat dissipation of the resistor, and it is only suitable for a small-capacity battery system.

Active power balancing is a non-consumption technology that improves the problem of passive power balancing and is suitable for large-capacity battery systems. Among them, the most common and widely used DC/DC converters are used as battery balancing methods. Based on the equal battery voltage, when the battery voltage reaches the set voltage value, the DC/DC converter operates, and the excess power is transmitted from the single battery back to the battery pack, but the equalization effect is still not as expected.

For example, please refer to Annex 1 for the discharge voltage curve of 8 lead-acid battery series battery packs. Since the battery pack does not use the equalization circuit, after a period of use, as shown in the curve of Annex 1, the battery pack The actual capacity difference of each battery has obviously reached about 10%, but in the discharge process, from the initial stage to the middle stage of discharge, about 80% of the discharge time, the voltage of each battery is still very close, only in the late stage of discharge, the battery power When the battery is almost used up, the voltage of each battery is significantly different.

Therefore, if the control of the battery balance is based only on the voltage, the effect of the battery balance may be very limited, and the battery power cannot be effectively balanced.

The object of the present invention is to provide an active battery power balance control method, which effectively balances the control of the battery power and avoids material degradation caused by overcharging or overdischarging of the battery.

According to the foregoing objective, the present invention provides an active battery power balance control method, in which a digital signal processor DSP (or a single chip or a computer) is used as a control core, and a battery is in a charging state and a discharging state via a bidirectional DC/DC converter. And the idle state can control the battery balance.

The active battery power balancing method of the present invention includes:

(a) The energy balance control method of the discharge mode, wherein the energy balance control method of the discharge mode is to sum the total power of the plurality of series connected batteries and take an average value when the battery is discharged, if any battery is high At the average value, the battery whose electric quantity is higher than the average value is discharged. If any battery power is lower than the average value, the battery whose electric quantity is lower than the average value is charged, and when the battery is in a low electric quantity difference Within the error range, the voltages of the plurality of series connected batteries are summed and an average value is taken. If any battery voltage is higher than the average value, the battery whose voltage is higher than the average value is discharged, if any battery voltage Below the average, the battery whose voltage is lower than the average is charged;

(b) an energy balance control method for a charging mode, wherein the energy balance control method of the charging mode is based on a percentage of an individual battery residual capacity as a percentage of an actual maximum storage capacity of the individual battery in a state in which the battery is charged, If the percentage of any battery residual power in its actual maximum storage capacity is higher than the reference value, it will be charged with more power, if the percentage of any battery residual power in its actual maximum storage capacity is lower than the reference value , it is charged with less power, so that each battery maintains the same residual power ratio, and when the battery's power difference is within the error range, the voltage of the plurality of series batteries is summed and an average value is taken. If any battery voltage is higher than the average value, the battery whose voltage is higher than the average value discharges, and if any battery voltage is lower than the average value, the battery whose voltage is lower than the average value is charged;

(c) an energy balance control method for the idle mode, wherein the energy balance control method of the idle mode is to charge the battery to increase its power when the battery is lower than the average when the battery is idle ( SOC, State of Charge, and the sum of the energy charged and its original residual power is less than the maximum capacity that the battery can store. If the battery is higher than the average, then The battery is discharged to reduce its power (SOC), and when the battery discharges the output power to the DC bus, the voltage of the busbar should be considered, and should not be higher than the maximum voltage of the system.

The invention is characterized in that the equalized energy required for each battery is calculated according to the capacity and voltage of each battery, and the digital signal processor DSP is used as the control core, and the electric vehicle is charged state via the bidirectional DC/DC converter. The battery state and the idle state can all be used to control the battery power balance so that each battery does not overcharge or over discharge. When the battery power reaches equilibrium, the energy storage of the battery pack can be fully utilized, so that the output of the entire battery will not be It is affected by a small number of poorly performing batteries.

1. . . Signal processing unit

2. . . Loop

3. . . Load power unit

4. . . Gate drive unit

5. . . Bidirectional DC/DC converter unit

6. . . Detection unit

7. . . battery

Figure 1: Schematic block diagram of the application structure of the present invention.
Annex 1: The discharge voltage curve of a series battery pack of 8 lead-acid batteries.

The purpose of the present invention, the technical contents, the features and the effects achieved by the present invention will be more readily understood by the detailed description of the embodiments of the present invention and the combination and use thereof.

First, referring to FIG. 1 , the present invention basically includes a signal processing unit 1 , a load power unit 3 electrically connected to the circuit 2 and the signal processing unit 1 , and is electrically connected to the signal processing unit 1 . a gate driving unit 4, and a plurality of bidirectional DC/DC converting units 5 electrically connected to the gate driving unit 4, respectively, are electrically connected to the respective bidirectional DC/DC converting units 5, and input detection signals to A detecting unit 6 of the signal processing unit 1 and a plurality of batteries 7 connected in series with each other and in parallel with the bidirectional DC/DC converting units 5 respectively implement the active battery level balancing control method of the present invention. The signal processing unit 1 is a DSP (Digital Signal Processing) or a single chip or a computer. This embodiment uses a DSP as an example to describe the signal input by the self-load power unit and the detecting unit. After calculation and processing, it serves as the basis for controlling battery balance.

The active battery power balance control method of the present invention comprises: (a) an energy balance control method of a discharge mode, (b) an energy balance control method of a charge mode, and (c) an energy balance control method of an idle mode, which will be sequentially Detailed description.

First of all, the energy balance control method for the discharge mode is to add a total value of a plurality of series connected batteries in a state in which the battery is discharged, and assume that if n batteries are connected in series, the power of the n batteries is increased. Always take an average value, expressed as a mathematical expression ,among them, For the average amount of electricity, Is the power of the kth battery;

If any battery is above the average (assuming the kth battery is more than ), the battery whose electric quantity is higher than the average value is discharged (discharging the k-th battery), and the excess energy is transferred from the battery to the high-voltage DC bus by the bidirectional DC/DC converter. The amount of electricity to be transferred is expressed mathematically as ( The amount of power that needs to be removed for the kth battery. Conversely, if any battery is below the average (assuming the kth battery is less than the battery) ), by means of a bidirectional DC/DC converter, the energy is transferred from the high voltage DC bus to the battery, and the amount of electricity to be transferred is mathematically expressed as ( The amount of power that needs to be moved for the kth battery).

Moreover, since the electric quantity estimation method has a certain error (about 3 to 5% or more), when the electric quantity difference of each battery is within the error range, the voltage equalization control method is adopted, and the battery voltage is used as the energy transfer. According to that, that is, summing the voltages of the n series of cells and taking an average value, expressed as a mathematical expression ,among them For the average voltage, Represents the voltage of the kth battery;

If any battery voltage is higher than the average ( And the battery whose voltage is higher than the average value is discharged, and the energy is transferred from the battery to the DC bus by the bidirectional DC/DC converter. If any battery voltage is lower than the average value, the voltage is low. The battery at this average is charged, and energy is transferred from the DC bus to the battery by a bidirectional DC/DC converter.

Continuing, regarding the energy balance control method of the charging mode, it should be noted that when the battery is in the charging state, special attention should be paid to the weak battery, because it is more overcharged, so in the charging process, the weaker battery needs to be lowered. The electric quantity is charged with less current. At this time, the method of equalizing the battery should not be controlled by maintaining the same residual electric quantity, and the energy balance control method of the charging mode proposed by the present invention is when the battery is in a charging state. The percentage of the individual battery residual capacity as a percentage of the actual maximum storage capacity of the individual battery is used as a reference value, ,among them, For the maximum capacity of the nth battery, For the residual power of the nth battery, if the percentage of any battery residual power in its actual maximum storage capacity is higher than the reference value, it will be charged with more power, if any battery residual power accounts for its own actual When the percentage of the maximum storage capacity is lower than the reference value, it is charged with less power, in other words, the energy is injected into the stronger battery by the bidirectional DC/DC converter, so that it is charged with more power. Wait until the power is supplied to the load, and then let it release more power to increase the battery's performance;

Similarly, for a weaker battery to charge less power, that is, by using a bidirectional DC/DC converter, the energy is removed from the weaker battery to maintain the same residual capacity ratio, which will avoid weaker batteries. Overcharged. Keep each battery at the same residual capacity ratio.

Moreover, since the electric quantity estimation method has a certain error (about 3 to 5% or more), when the electric quantity difference of each battery is within the error range, the voltage equalization control method is adopted, and the battery voltage is used as the energy transfer. According to that, that is, summing the voltages of the n series of cells and taking an average value, expressed as a mathematical expression ,among them For the average voltage, Represents the voltage of the kth battery;

If any battery voltage is higher than the average ( And the battery whose voltage is higher than the average value is discharged, and the energy is transferred from the battery to the DC bus by the bidirectional DC/DC converter. If any battery voltage is lower than the average value, the voltage is low. The battery at this average is charged, and energy is transferred from the DC bus to the battery by a bidirectional DC/DC converter.

Subsequently, the present invention proposes an energy balance control for the idle time of the electric vehicle. Usually, in order not to increase the weight of the electric vehicle and reduce the device cost of the energy balance control circuit, the ability to equalize the power of the circuit is much lower than the rated power of the external charger and the motor load. Under this condition, the energy shift between the batteries can be performed by the idle time of the electric vehicle, including the return waiting time, the station time, and the red light time, so as to improve the energy generated when the battery pack is operated at a high power. Unbalanced problem, try to achieve the energy balance of the battery in the late stage of discharge and later in the charge.

As mentioned in the above paragraph, the energy balance control method of the idle mode is to charge the battery to increase its power (SOC, State of Charge) when the battery is below the average when the battery is idle. Battery capacity"), and the sum of the energy charged and its original residual power is less than the maximum capacity that the battery can store. For example, in the idle mode, when the power of the kth battery is lower than the average value, The mathematical formula of the transferred power (same power balance as the charging mode) is and In order to avoid overcharging some batteries, it is necessary to add restrictions, the mathematical formula is That is, when the power of the kth battery is lower than the average value, the battery needs to be charged to increase its power (SOC), but the sum of the charged energy and its original residual power should be less than the battery can store. Maximum capacity to avoid overcharging the battery;

Similarly, if the charge of any battery is higher than the average value, the battery is discharged to reduce its power (SOC). If the power of the kth battery is higher than the average value, the battery needs to be discharged. Decrease its power (SOC) to maintain the energy balance of each battery. However, if the output power cannot be absorbed by the low battery, it will cause the DC bus voltage to rise, which may cause overvoltage in the system and cause the battery. Damage, therefore, during a period of inactivity, if a battery needs to output power to the DC bus, consider the voltage of the bus, not higher than the maximum voltage of the system.

The invention is applicable to a series battery or a series battery pack and can be widely applied to mobile vehicles, bicycles, bicycles and the like, and can also be applied to a battery energy storage system of a renewable energy source, a battery system of a UPS, a lithium battery, a nickel hydrogen battery and Lead acid battery products.

In summary, the present invention has the following features and advantages:

1. Calculate the required equalization energy according to the capacity and voltage of each battery, effectively achieve the balance of battery power and high reliability.

2. Stable battery balance control can be performed in the charging state, discharging state and idle state.

3. Improve the capacity and life of the series battery pack, thereby reducing the cost of battery replacement.

The foregoing is only a preferred embodiment of the present invention, which is intended to be understood by those skilled in the art and is not intended to limit the scope of the present invention. Equivalent variations or modifications of the shapes, configurations and features are intended to be included within the scope of the present invention.

1. . . Signal processing unit

2. . . Loop

3. . . Load power unit

4. . . Gate drive unit

5. . . Bidirectional DC/DC converter unit

6. . . Detection unit

7. . . battery

Claims (4)

An active battery power balance control method includes: an energy balance control method for a discharge mode, wherein the energy balance control method of the discharge mode is to sum and take an average of a plurality of series connected batteries in a state in which the battery is discharged. Value, if any battery power is higher than the average value, the battery whose battery is higher than the average value discharges, and if any battery power is lower than the average value, the battery whose battery is lower than the average value is charged. Moreover, when the battery power difference is within the error range, the voltages of the plurality of series batteries are summed and an average value is taken. If any battery voltage is higher than the average value, the battery whose voltage is higher than the average value The discharge is performed, and if any of the battery voltages is lower than the average value, the battery whose voltage is lower than the average value is charged. An active battery power balance control method includes: an energy balance control method of a charging mode, wherein the energy balance control method of the charging mode is that, in a state in which the battery is charged, the individual battery residual power accounts for the actual maximum storage of the individual battery. The percentage of capacity is the reference value. If the percentage of any battery residual power in its actual maximum storage capacity is higher than the reference value, it will be charged with more power, if any battery residual power accounts for its actual maximum storage. If the percentage of the capacity is lower than the reference value, it is charged with less power, so that each battery maintains the same residual power ratio, and when the battery's power difference is within the error range, that is, a plurality of series connected batteries The voltage is summed and takes an average value. If any battery voltage is higher than the average value, the battery whose voltage is higher than the average value is discharged. If any battery voltage is lower than the average value, the voltage is lower than the average value. The average battery is charged. An active battery power balance control method includes: an energy balance control method for an idle mode, wherein the idle mode energy balance control method is: when the battery is idle, if the battery power is lower than an average value, The battery is charged to increase its SOC (State of Charge), and the sum of the charged energy and its original residual power is less than the maximum capacity that the battery can store, and if any battery When the battery is above average, the battery is discharged to reduce its power (SOC), and when the battery discharges the output to the DC bus, the voltage of the bus should be considered, not higher than the maximum voltage of the system. The active battery balancing control method of claim 1 or 2 or 3, wherein the circuit architecture of the method includes at least one signal processing unit, and a load power unit electrically connected to the circuit and the signal processing unit respectively. And at least one gate driving unit electrically connected to the signal processing unit, and the plurality of bidirectional DC/DC converting units electrically connected to the gate driving unit respectively, and electrically connected to the individual bidirectional DC/DC converting units respectively Inputting a detection signal to a detection unit of the signal processing unit, and a plurality of batteries connected in series with each other and in parallel with the two-way DC/DC conversion units, wherein the signal processing unit is a DSP (Digital Signal Processing) Processor) or single chip or computer.