KR20140143237A - Apparatus for balancing of battery voltage using fuzzy algorism - Google Patents

Abstract

The present invention relates to an apparatus for balancing a battery voltage by using a fuzzy algorithm According to the present invention, the apparatus for balancing the battery voltage comprises a voltage measurement unit, a switching unit, and a control unit. The voltage measurement unit measures a voltage of each of a plurality of batteries connected in series. The switching unit is connected to at least one equalizer which controls charging and discharging of the batteries. The switching unit controls the operation of the voltage equalizer so as to balance a voltage between at least two batteries among the plurality of batteries. The control unit generates a current value by applying the measured voltage and a voltage difference between at least two batteries to a preset fuzzy algorithm, and controls the operation of the switching unit based on the current value. According to the present invention, it can be expected to obtain the effect that the powers of the plurality of batteries can be uniformly controlled with high accuracy by using the apparatus for balancing the battery voltage, to which the fuzzy algorithm is applied.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a battery voltage balancing apparatus using a fuzzy algorithm,

The present invention relates to a battery voltage balancing apparatus using a fuzzy algorithm, and more particularly, to an apparatus for balancing a plurality of serially connected battery voltages by controlling a plurality of individual cell voltage equalizers based on a fuzzy algorithm.

Renewable energy sources, including solar cells, are attracting attention as alternative energy sources because they do not use fossil fuels that are limited to the earth and minimize environmental pollution. However, since the voltage and current are unstable in the renewable energy source, it is difficult to supply stable power to the load. Therefore, in recent years, techniques for securing the power output of a system using an energy storage device such as a battery have been developed.

A conventional renewable power generation system has a structure in which a series type power converter is connected from a plurality of power sources to supply power to a load. However, since each input power source is configured independently, battery voltage may be varied. In order to prevent the voltage deviation between the batteries, a charge balancing circuit (balancing circuit) is used separately from the power converter.

There is a method of balancing the battery voltage. There is a method of balancing while consuming power by a resistor. However, there is a problem that efficiency is low. Balancing using an inductor can increase the efficiency. However, There is a problem that the cost for constructing the system increases.

The technology of the background of the present invention is described in Korean Patent Laid-Open Publication No. 10-2010-0088369 (2010.08.09).

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an apparatus for balancing a plurality of series-connected battery voltages by controlling a plurality of individual cell voltage equalizers based on a fuzzy algorithm.

According to an aspect of the present invention, there is provided an apparatus for controlling battery voltage balancing, comprising: a voltage measuring unit for measuring a voltage of each of a plurality of batteries connected in series; A switching unit connected to at least one voltage equalizer for controlling charging and discharging of the batteries and controlling the operation of the voltage equalizer to balance voltages between at least two of the plurality of batteries; And a controller for applying a voltage difference between the measured voltage and at least two batteries to a predetermined fuzzy algorithm to generate a current value and controlling the operation of the switching unit based on the current value.

Here, the voltage equalizer is connected to each of the two batteries, the first end connected to the first battery and the second battery, the second end connected to the first inductor and the capacitor, and the third end connected to the switching unit A first switch connected; A second switch having a first end connected to the capacitor and the second inductor, a second end connected to the first battery and the second battery, and a third end connected to the switching unit; A first diode coupled to the first and second ends of the first switch; And a second diode coupled to the first and second ends of the second switch.

Here, the first switch and the second switch operate respectively in an ON state or an OFF state in accordance with a duty ratio matched with the current value, and the voltage of the first battery and the second battery Balancing can be controlled.

Here, the fuzzy algorithm calculates membership function calculation, T-norms calculation, normalizing calculation, fuzzy calculation value calculation and current value calculation using the measured voltage and voltage difference. Can be performed sequentially.

Here, the control unit may perform the logarithmic function calculation using the following equation.

Here, a _i is a parameter value for deriving a membership function, which is approximate values formed within a set range of a voltage value, bi is a difference between an approximate value and a voltage, i is a number of approximate values matching the input voltage value, Vb is a voltage value of a battery having a large charge amount among two batteries, and De is a voltage difference value charged in two batteries.

Here,

The T-norm calculation can be performed using the following equation.

)는 Ai(Vb)와 Bi(De) 중 작은 값이고, N은 계산된 Ai(Vb)와 Bi(De)의 조합 수이다.Here, the output value (

) Is a smaller value of Ai (Vb) and Bi (De), and N is the number of combinations of calculated Ai (Vb) and Bi (De).

Here, the control unit may perform the normalization value calculation using the following equation.

)들이며, 분자는 N까지의

값이다.Here, the denominator is an output value obtained by T-

), And the molecule has up to N

Value.

Here, the control unit may calculate the fuzzy arithmetic operation value using the following equation.

Here, si is an optimization function value, and pi and qi are parameters for deriving an optimization function value, respectively.

Here, the control unit can calculate the current value through the fuzzy calculation value using the following equation.

Here, if the calculated current value is not included in the set range, the controller repeats the fuzzy algorithm after changing the values of pi and qi by a predetermined value, and if the calculated current value is within the set range, So that the operation of the switching unit can be controlled.

As described above, according to the present invention, it is possible to expect an effect of uniformly controlling power of a plurality of batteries with high accuracy by using a battery voltage balancing apparatus to which a fuzzy algorithm is applied.

1 is a diagram of a system to which a typical individual cell voltage equalizer is applied.
2 is a block diagram illustrating a system to which a battery voltage balancing apparatus according to an embodiment of the present invention is applied.
3 is a block diagram illustrating a battery voltage balancing apparatus according to an embodiment of the present invention.
4 is a view for explaining the operation of the battery voltage balancing apparatus according to the embodiment of the present invention.
5 is a flowchart illustrating a battery voltage balancing method of a battery voltage balancing apparatus according to an embodiment of the present invention.
6 is a diagram illustrating a structure of an adaptive neuron-fuzzy inference algorithm according to an embodiment of the present invention.
FIG. 7 is a graph illustrating changes in first and second battery voltages due to operation of a battery voltage balancing apparatus according to an embodiment of the present invention. Referring to FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

First, a circuit to which an individual cell equalizer (ICE) is applied will be described with reference to FIG. 1. Referring to FIGS. 2 to 7, a battery with a single cell voltage equalization applied with fuzzy theory according to an embodiment of the present invention, The voltage balancing device will be described in detail.

1 is a diagram of a system to which a typical individual cell voltage equalizer is applied.

1, a system 100 to which a typical individual cell voltage equalizer 120 is applied includes a plurality of individual cell voltage equalizers 120 (ICE_1, ICE_j, ICE_j + 1, ICE_n-1) And each of the individual cell voltage equalizers 120 includes at least two positive and negative electrodes 110a and 110b of the battery 110, -) so as to balance the voltage between the batteries 110. At this time, the system 100 has one fewer individual cell equalizer 120 (hereinafter referred to as "ICE") than the number of batteries 110 for managing the battery of the cell.

A system to which a battery voltage balancing apparatus according to an embodiment of the present invention is applied will be described in detail with reference to FIG. 2 through FIG.

FIG. 2 is a block diagram showing a system to which a battery voltage balancing apparatus according to an embodiment of the present invention is applied, FIG. 3 is a diagram illustrating a battery voltage balancing apparatus according to an embodiment of the present invention, FIG. 4 is a diagram illustrating an operation of a battery voltage balancing apparatus according to an embodiment of the present invention.

2, a battery voltage balancing system 200 according to an embodiment of the present invention includes a battery pack device 210 (ICE_1, ICE_j, ICE_j + 1, ICE_n-1) to which individual cell voltage equalizers 230 And a battery voltage balancing device 240. [

The battery pack device 210 includes a plurality of batteries 220 (Vb1, Vb2, Vbj, Vbj + 1, Vbj + 2, Vbn-1, Vbn) and a plurality of individual cell voltage equalizers 230. The battery pack device 210 is the same as the system 100 to which the typical individual cell voltage equalizer 120 described with reference to FIG. 1 is applied, and a detailed description thereof will be omitted.

The battery voltage balancing device 240 includes a switching unit 250, a control unit 260 and a voltage measurement unit 270. The battery voltage balancing device 240 uses an adaptive neuron-fuzzy inference system algorithm (ANFIS) And controls voltage balancing between at least two batteries 220 connected in series. The adaptive neuron-fuzzy reasoning algorithm will be described with reference to FIGS. 5 and 6. FIG.

The switching unit 250 is connected to each individual cell voltage equalizer 230 and turns on / off the switch of the individual cell voltage equalizer 230 under the control of the control unit 260. At this time, the switching unit 250 may be configured to be matched to the individual cell voltage equalizers 230, respectively. At this time, the switching unit 250 generates a PWM (Pulse-Width Modulation) signal matching the current value received from the control unit 260 and controls the switches 236 and 237 of the individual cell voltage equalizer 230.

The control unit 260 includes a microprocessor unit and controls voltage balancing between the batteries 221 and 222 according to the adaptive neuron-fuzzy inference algorithm through a microprocessor.

The voltage measuring unit 270 measures the voltages of the respective batteries 220 and provides the measured information to the control unit 260. At this time, the voltage measuring unit 270 includes a plurality of voltage sensors, and each voltage meter measures a voltage of at least one battery.

3, the battery voltage balancing device 240 includes a plurality of individual cell voltage equalizers 230 in the battery pack device 210 and a switching unit 250 And a voltage measuring unit 270 is connected to both ends of at least one battery 220 to measure the amount of voltage of the battery.

One individual cell voltage equalizer 230 in the battery pack 210 is connected to the positive (+) and negative (-) terminals of two serially connected batteries and has two switches 236 and 237, two diodes 234, and 235), two inductors 231 and 232, and one capacitor 233.

The first switch 236 and the second switch 237 are each composed of a MOSFET which is a transistor. When a voltage is applied to the gate Gate, a current flows between the source and the drain .

The drain of the first switch 236 is connected to the first inductor 231 and the capacitor 233 and the diode 234 is connected between the source and the drain. The source is connected to the cathode of the first battery 221 and the anode of the second battery 222, and the gate is connected to the switching unit 250.

The source of the second switch 237 is connected to the capacitor 233 and the second inductor 232, and a diode 235 is connected between the source and the drain. The drain is connected to the negative electrode of the first battery 221 and the positive electrode of the second battery 222, and the gate is connected to the switching unit 250.

The first end of the first inductor 231 is connected to the positive electrode of the first battery 221 and the voltage measuring unit 270 and the second end of the first inductor 231 is connected to the source of the first switch 236 and the capacitor 233 .

The second inductor 232 has a first end connected to the source of the capacitor 233 and the second switch 237 and a second end connected to the cathode of the second battery 221 and the voltage measuring unit 270 .

The capacitor 233 has a first end connected to the source of the first switch 236 and the first inductor 231 and a second end connected to the source of the second switch 237 and the second inductor 232 .

The operation of the circuit according to the on / off of the switching unit will be briefly described with reference to FIG. 4. When the switching unit 250 is turned on / off, the individual cell voltage equalizer 230 switches the first switch 236, Off operation of the first and second switches 237 and 237 to charge / discharge the electric power of the batteries 221 and 222, respectively.

First, assuming that the first battery 221, Vb1 has a higher cell voltage than the second battery 222, Vb2, a duty ratio (hereinafter referred to as "duty " The switching unit 250 controls on / off of the first switch 236 and the second switch 237 based on the " ratio " The duty ratio of the control unit 260 will now be described with reference to FIGS. 5 to 8. FIG.

The first switch 236 is charged by the capacitor 233 when the switching unit 250 is turned on and the first switch 236 is turned off by the switching unit 250. [ The second battery 222 is charged with the electric power of the charged capacitor.

On the other hand, assuming that the first battery 221 (Vb1) has a cell voltage lower than that of the second battery 222 (Vb2), the second switch 237 performs on / off operation by the switching unit 250 And the first battery 221 is charged with the electric power of the second battery 237.

The operations of the individual cell voltage equalizer 230 are well known to those skilled in the art and will not be described in detail.

The operation of the controller of the battery voltage balancing apparatus according to the embodiment of the present invention will now be described with reference to FIGS. 5 through 7. FIG.

FIG. 5 is a flowchart illustrating a battery voltage balancing method of a battery voltage balancing apparatus according to an embodiment of the present invention, FIG. 6 is a diagram illustrating a structure of an adaptive neuron-fuzzy reasoning algorithm according to an embodiment of the present invention, 7 is a graph illustrating first and second battery voltage fluctuations due to the operation of the battery voltage balancing apparatus according to the embodiment of the present invention.

5 and 6, the controller 260 of the battery voltage balancing device 240 according to the embodiment of the present invention includes an adaptive neuron-fuzzy inference And controls the voltage balancing operation of the individual cell voltage equalizer 230 by controlling the switching unit 250 through the calculated optimum current value.

Hereinafter, an adaptive neuron-fuzzy reasoning algorithm for the processes from layer 1 to layer 5 in FIG. 5 will be described in detail.

In step S500, the controller 260 performs a membership function calculation on the membership functions using the fuzzy logic function of Equation (1). In this case, X1 in FIG. 5 is a voltage value of a battery having a larger value among Vb1 and Vb2, and X2 is a voltage difference value between Vb1 and Vb2.

Here, a _i and b _i are parameter values for deriving the membership function, which are approximate values formed close to the voltage value and the voltage value, and i is the number of approximate values matching the input voltage value (for example, When the voltage value is inputted, the values included in the fuzzy set matching the voltage value of 4V among the fuzzy sets stored in the storage unit (omitted)). Vb is a voltage value of a battery having a high voltage value when there are two voltages Vb1 and Vb2, and De is a voltage difference value between Vb1 and Vb2.

The control unit 260 performs T-norms calculation (T-norms calculation), which is a layer 2 process, using Ai (Vb) and Bi (De) calculated through the membership function calculation function (S502). The T-norm calculation is for measuring the intensity of the inferred values in Equation (1), and is performed by the following Equation (2).

)은 수학식 1에 의해 계산된 두 값 중 작은 값(최소값 T)을 의미하며, 1부터 N까지의 값을 계산한다. 이때, N은 상기 수학식 1에 의해 계산된 A_i(Vb)와 B_i(De)의 조합 수이다.Here, the output value (

) Denotes a smaller value (minimum value T) of the two values calculated by Equation (1), and calculates a value from 1 to N. [ In this case, N is the number of combinations of A _i (Vb) and B _i (De) calculated by Equation (1).

The control unit 260 normalizes the layer 3 process using the output value calculated through the T-Nomus calculation function (S504). The normalization function is performed by the following equation (3).

)들이며, 분자는 N까지의

값이다. 이때, 제어부(260)는 분자에 대해 N까지의 출력값들을 순차적으로 이용하여 정규화값 (

)을 계산한다.At this time, the denominator is the sum of all the output values calculated by the equation (2)

), And the molecule has up to N

Value. At this time, the controller 260 sequentially uses the output values up to N with respect to the numerator to obtain a normalized value (

).

In operation S506, the controller 260 calculates a fuzzy calculation value b _i s _i for controlling the switching unit 250 through the layer 4 process. At this time, the layer 4 process is performed by the following equation (4).

Here, s _i is an optimization function value, and p _i and q _i are parameters for deriving an optimization function value, respectively, and initial values are 1 and 2, respectively, and the value is changed by the control unit 260.

The control unit 260 may control the switching unit 250 by adding the values obtained by multiplying all the optimization function values 1 through i by the normalization value by applying the fuzzy calculation value calculated through the layer 4 process to the following Equation 5 The current value I _turn is calculated (S058). Here, the current value is a value for the control unit 260 to control the switching unit 250, and the switch unit 250 generates the PWM control signal using the current value. At this time, the ON times of the switches 236 and 237 of the individual cell voltage equalizer 230 are determined by the PWM control signal.

The control unit 260 calculates an error value using the following Equation (6) to determine whether the current value calculated through Equation (5) is an optimal current value (S510).

는 수학식 5에 의해 계산된 전류값이고,

는 기 설정된 전류값이다. here,

Is a current value calculated by Equation (5)

Is a predetermined current value.

The control unit 260 determines whether the calculated error value is included in a predetermined range (e.g., 0.5) (S512). If the error value is not included in the predetermined range as a result of the determination in step S512, The controller 260 changes the values of p _i and q _i by a predetermined value (for example, -0.1), and then repeats steps S500 through S512.

If it is determined in step S510 that the error value is included in the predetermined range, the controller 260 determines the current value calculated by Equation (5) as the optimal current value and outputs the current value to the switching unit 250 based on the current value. .

7, a battery voltage balancing device 240 according to an embodiment of the present invention includes switches 230 and 237 of individual cell voltage equalizers 230 through a switching unit 250 to which a calculated optimal current value is applied. ), It is possible to minimize a difference in the amount of voltage of the two batteries 221 and 222. [

According to the present invention, by controlling the individual cell voltage equalizer to the optimum current value calculated by using the battery voltage balancing apparatus to which the adaptive neuron-fuzzy inference algorithm is applied, There is a great advantage that power can be controlled evenly with high accuracy.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

100: System with individual cell voltage equalizer applied
110: Battery
120: Individual cell voltage equalizer
200: Battery Voltage Balancing System
210: Battery pack device
220: Battery
230: Individual cell voltage equalizer
240: Battery voltage balancing device
250:
260:
270: voltage measuring unit

Claims (10)

An apparatus for balancing a voltage between a plurality of batteries connected in series,
A voltage measuring unit for measuring a voltage of each of a plurality of batteries connected in series;
A switching unit connected to at least one voltage equalizer for controlling charging and discharging of the batteries and controlling the operation of the voltage equalizer to balance a voltage between at least two of the plurality of batteries; And
Generating a current value by applying a voltage difference between the measured voltage and the at least two batteries to a predetermined fuzzy algorithm, and controlling the operation of the switching unit based on the current value,
And a battery voltage balancing device. The method according to claim 1,
Wherein the voltage equalizer comprises:
Each of the two batteries being connected to each other,
A first switch having a first end connected to the first battery and a second battery, a second end connected to the first inductor and the capacitor, and a third end connected to the switching unit;
A second switch having a first end connected to the capacitor and the second inductor, a second end connected to the first battery and the second battery, and a third end connected to the switching unit;
A first diode coupled to the first and second ends of the first switch; And
A second diode coupled to the first and second ends of the second switch,
And a battery voltage balancing device. 3. The method of claim 2,
Wherein the first switch and the second switch comprise:
And a battery voltage balancing unit that operates on and off according to a duty ratio matched with the current value to control voltage balancing of the first battery and the second battery through charge and discharge of the capacitor, Device. The method according to claim 1,
The fuzzy algorithm,
Membership Function Calculation, T-Norms Calculation, Normalizing Value Calculation, Fuzzy Calculation Value Calculation, and Current Value Calculation are sequentially performed using the measured voltage and the voltage difference Wherein the battery voltage balancing device is a battery voltage balancing device. 5. The method of claim 4,
Wherein,
A battery voltage balancing apparatus for performing the calculation of the battery function using the following equation:

Here, a _i is a parameter value for deriving the membership function, which is approximate values formed within the set range of the voltage value, bi is the difference between the approximate value and the voltage, i is the number of approximate values matching the input voltage value Vb is a voltage value of a battery having a higher charge amount among the two batteries, and De is a voltage difference value charged in the two batteries. 6. The method of claim 5,
Wherein,
A battery voltage balancing apparatus for performing the T-norm calculation using the following equation:

Here, the output value (

) Is a smaller value of Ai (Vb) and Bi (De), and N is the number of combinations of calculated Ai (Vb) and Bi (De). The method according to claim 6,
Wherein,
A battery voltage balancing apparatus for performing the normalization value calculation using the following equation:

Here, the denominator is an output value obtained by the T-norm calculation

), And the molecule has up to N

Value. 8. The method of claim 7,
Wherein,
A battery voltage balancing apparatus for performing the calculation of the fuzzy calculation value using the following equation:

Here, si is an optimization function value, and pi and qi are parameters for deriving an optimization function value, respectively. 9. The method of claim 8,
Wherein,
A battery voltage balancing apparatus for calculating the current value through the fuzzy operation value using the following equation:

10. The method of claim 9,
Wherein,
If the calculated current value is not included in the set range, the value of pi and the value of qi are changed by a set value, and the fuzzy algorithm is repeated,
And controls the operation of the switching unit using the current value when the calculated current value is within a set range.

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