KR20200086848A - Battery system - Google Patents

Abstract

The present invention relates to a battery system including a reverse voltage protection circuit connected between a first battery and a load. The protection circuit comprises: a first transistor connected to a drain connected to a first battery, a source connected to a load, and a third transistor collector; a diode unit connected between bases of the first battery and a third transistor; a third transistor including an emitter connected to the source of the first transistor, the base connected to the diode unit, and a collector connected to a collector of a second transistor; and a Zener diode connected between the source of the first transistor and the third transistor collector. When a first voltage on a first battery side is lower than a second voltage on a load side, a reverse voltage current path is formed through the first transistor for maintaining an initial voltage capable of operating the third transistor, the third transistor and the second transistor.

Description

Battery system {BATTERY SYSTEM}

The present invention relates to a battery system, and more particularly, to a system for protecting a battery from reverse voltage.

As environmental issues have recently become an issue due to interest in the environment, interest and demand for eco-friendly renewable energy that can replace fossil fuels, which have a great influence on environmental issues, is increasing. The need for is increasing.

Secondary cells are one of the energy sources that can replace such fossil fuels, and semi-permanently used by charging the electricity generated in the process where the current supplied by external power causes oxidation/reduction reaction of the material between the anode and the cathode. This is a possible battery.

Secondary cells have the primary advantage of being able to dramatically reduce the use of fossil fuels, as well as the fact that by-products from the use of energy do not occur at all. In addition, unlike a primary battery that is used once and discarded, the secondary battery has an advantage that it can be charged multiple times. Due to this advantage, the secondary battery is an electric vehicle (EV, Electric Vehicle), a hybrid vehicle (HV, Hybrid Vehicle), an energy storage system (ESS) or an uninterruptible power source using a medium-to-large battery used for home or industrial use. It is used in a wide range of fields such as Uninterruptible Power Supply (UPS).

The secondary battery may not be applied when used in a battery such as a mobile terminal requiring a low capacity, but the unit secondary in an environment in which there is a high capacity such as an electric vehicle, an energy storage system and an uninterruptible power supply as described above. A plurality of battery cells can be used.

As described above, when a plurality of secondary battery cells are joined and used in the form of a battery, problems such as overheating and overvoltage may cause the battery to overheat due to an abnormal operation, which causes the unit cell to swell and break. In order to compensate for this problem, when a plurality of secondary battery cells are connected and used, it is always necessary to measure and monitor various state information such as voltage, current, and temperature of individual cells and prevent overcharging or overdischarging of unit cells. In addition, it is necessary to prevent the system from being damaged from a reverse voltage that may occur when the battery pack internal circuit is disconnected or damaged by an external environment or an abnormal situation.

The present invention is to overcome the above-mentioned problems, the system according to the embodiment is to protect the battery when the reverse voltage is introduced into the battery, and to have a fast current reduction response when the load is shorted (short).

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned may be clearly understood by a person having ordinary skill in the art from the description of the present invention. .

The embodiment provides a battery system including a reverse voltage protection circuit connected between a first battery and a load, wherein the reverse voltage protection circuit of the battery system includes a drain connected to the first battery, a source connected to the load, and a third A first transistor connected to a transistor collector; A diode unit connected between the first battery and the base of the third transistor; The third transistor including an emitter connected to the source of the first transistor, a base connected to the diode portion, and a collector connected to the collector of the second transistor; And a zener diode connected between the source of the first transistor and the third transistor collector, and when the first voltage on the first battery side is lower than the second voltage on the load side, the third transistor and the third transistor. A reverse voltage current path via 2 transistors is formed.

Further, the diode portion of the battery system according to the embodiment includes a first diode and a second diode, and the first diode and the second diode are connected in series.

Further, the reverse voltage protection circuit of the battery system according to the embodiment further includes a third diode including an anode connected to the source of the first transistor and a cathode connected to the emitter of the third transistor.

In addition, the third diode of the battery system according to the embodiment further includes a diode unit for increasing a difference between an operating voltage of the first voltage and the second voltage.

In addition, the reverse voltage protection circuit of the battery system according to an embodiment further includes a first capacitor including one end connected to the cathode of the third diode and the other end connected to ground.

In addition, the reverse voltage protection circuit of the battery system according to the embodiment further includes a fourth diode including a cathode connected to the collector of the second transistor and an anode connected to the collector of the third transistor.

Further, the battery system of the battery system according to the embodiment further includes a BMS, and the BMS is configured to apply a control signal to the base of the second transistor.

In addition, the reverse voltage protection circuit of the battery system according to the embodiment, the first resistor connected between the cathode of the second diode and the anode of the fourth diode

It further includes.

In addition, the battery system of the battery system according to an embodiment further includes a second battery, the reverse voltage protection circuit further includes a fifth diode, and the fifth diode is an anode connected to the battery and the first transistor It includes a cathode connected to the other end of the.

Further, when the first voltage on the first battery side of the battery system according to the embodiment is lower than the second voltage, or the first voltage on the second battery side is higher than the first voltage on the first battery side , A reverse voltage current path is formed through the third transistor and the second transistor.

In addition, the BMS of the battery system according to the embodiment is configured to apply a control signal to the base of the second transistor that suppresses leakage current using at least one of the first battery and the second battery.

The battery system according to the present invention has an effect of protecting the battery when a reverse voltage is introduced into the battery and having a fast current reduction response when the load is shorted.

1 is a battery system according to an embodiment.
2 is a reverse voltage current path of the reverse voltage protection circuit according to the embodiment.
3 is a battery system according to another embodiment.
4 is a reverse voltage current path of a reverse voltage protection circuit according to another embodiment.

Hereinafter, exemplary embodiments disclosed herein will be described in detail with reference to the accompanying drawings, but the same or similar reference numerals are assigned to the same or similar elements, and overlapping descriptions thereof will be omitted. The suffixes "modules" and "parts" for components used in the following description are given or mixed only considering the ease of writing the specification, and do not have meanings or roles distinguished from each other in themselves. In addition, in the description of the embodiments disclosed herein, when it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed herein, detailed descriptions thereof are omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the specification is not limited by the accompanying drawings, and all modifications included in the spirit and technical scope of the present invention , It should be understood to include equivalents or substitutes.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but there may be other components in between. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, terms such as “comprises” or “have” are intended to indicate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, and that one or more other features are present. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Hereinafter, a battery system according to an embodiment will be described with reference to FIG. 1. 1 is a battery system according to an embodiment.

Referring to FIG. 1, the battery system 1 includes a battery 10, a reverse voltage protection circuit 20, a BMS, and a load, and the battery 10 includes a BM including a reverse voltage protection circuit 20. Is connected to the load.

The battery 10 is connected to the BMS and the reverse voltage protection circuit 20.

The reverse voltage protection circuit 20 includes first to third transistors Q1, Q2 and Q3, first to fifth diodes D1, D2, D3, D4 D5, zener diode ZD, and first to third 4 resistors R1, R2, R3, R4, and a first capacitor C1.

The first transistor Q1 includes a battery 10 and one end (drain) connected to the BMS, the other end (source) connected to the BMS and the load, and a control terminal connected to the collector C of the third transistor Q3. The first transistor Q1 may be a PMOS FET, but embodiments are not limited thereto.

The second transistor Q2 includes a collector connected to the cathode of the fourth diode, a base connected to one end of the third resistor R3 and the fourth resistor R4, and an emitter connected to ground, and sleep current ). The second transistor Q2 may be an npn transistor, but the embodiment is not limited thereto, and the collector C of the second transistor may be connected to ground and used.

The third transistor Q3 includes an emitter E connected to the cathode of the third diode D3, a base B connected to the cathode of the second diode, and a collector C connected to the control terminal of the first transistor do. The third transistor may be a pnp transistor, but embodiments are not limited thereto.

The first diode D1 and the second diode D2 are connected in series, and the first diode D1 is an anode connected to the battery 10 and a cathode connected to the anode of the second diode D2. The second diode D2 includes an anode connected to the first diode D1 and a cathode connected to the base B of the third transistor Q3.

The first diode D1 and the second diode D2 form the diode unit 31.

The third diode D3 includes an anode connected to the other end of the first transistor Q1 and a cathode connected to the emitter E of the third transistor. For convenience of explanation, the third diode D3 is illustrated as one diode, but the difference between the first voltage V1 and the second voltage V2 is performed by connecting at least one diode in series to the third diode D3. The operating voltage by (V1-V2) can be increased.

The fourth diode D4 includes an anode connected between the first resistor R1 and the second resistor R2 and a cathode connected to the emitter of the second transistor Q2. The fourth diode D4 may be omitted because it is used as a short.

The Zener diode ZD is connected to the cathode connected to the load and the control terminal of the first transistor Q1 to apply an operating voltage to the control terminal of the first transistor Q1.

The first capacitor includes one end connected to the emitter E of the third transistor Q3 and the other end connected to ground. The first capacitor C1 maintains the operating voltage of the third transistor Q3 by maintaining the second voltage V2 for a predetermined time in an abnormal state.

For convenience of description, the first diode D1 and the first diode D1 are described as configuring the diode unit 31, but the embodiment is not limited thereto, and only the first diode D1 is the diode unit 31 ), or three or more diodes, such as a first diode D1, a second diode D2, and a third diode (not shown), may constitute the diode unit 31. Also, a plurality of capacitors connected in series to the first capacitor C1 may be included.

The diode unit 31 applies an operating voltage to the base B of the third transistor Q3, and this operating voltage V1-V2 is determined by the number of diodes in the diode unit 31.

The first resistor R1 and the second resistor R2 are connected in series, and the first resistor R1 is connected between the base B of the third transistor Q3 and the anode of the fourth diode D4. It is done. The second resistor R2 is connected between the anode of the fourth diode D4 and the control terminal of the first transistor Q1.

The BMS measures the first voltage V1 of the battery 10, measures the voltage of the second voltage V2 on the load side, is driven by the second voltage V2, and controls the second transistor Q2. A signal (Vcc, for example 5V) is generated.

Hereinafter, a reverse voltage current path according to an embodiment will be described with reference to FIG. 2. 2 is a reverse voltage current path of the reverse voltage protection circuit 20 according to the embodiment.

In the present invention, the standby state means a state in which the control signal (Vcc) is not supplied by the BMS, and the normal state provides the control signal (Vcc) in the BMS and the first voltage (V1) is greater than the second voltage (V2). It means high state (V1>V2). The abnormal state means that the control signal Vcc is supplied from the BMS and the first voltage V1 becomes a lower state V1 <V2 than the second voltage V2, but is not limited thereto.

In the standby state, even though the voltage of the battery 10 passes through the internal diode Di of the first transistor Q1, the control signal Vcc is not supplied by the BMS. Since there is no current passing through the Zener diode ZD or the third transistor Q3, the source-gate voltage VSG of the first transistor Q1 becomes 0V, so there is no leakage current caused by the reverse voltage prevention circuit 20. .

In the normal state, when the voltage of the battery 10 passes through the internal diode Di of the first transistor Q1 and the BMS supplies a high level control signal (Vcc, for example 5V), the zener diodes (ZD, Zener) 12V is applied to the voltage = 12V, and a current path Lo passing through the Zener diode ZD, the second resistor R2, the fourth diode D4, and the second transistor Q2 is generated, and the first VSG of transistor Q1 becomes equal to Zener voltage 12V. Therefore, since the VSG of the first transistor Q1 is sufficiently higher than the threshold voltage, the loss of the first transistor Q1 by Io*Io*Ron is less than that of using a diode.

In the abnormal state, since the third transistor Q3 is turned on and the first transistor Q1 is turned off, the third diode D3, the third transistor Q3, the second resistor R2, and the third transistor Q3 are turned off. A reverse voltage current path Ro is formed through the four diodes D4 and the second transistor Q2.

Specifically, the voltage VEB between the emitter E and the base B of the third transistor Q3 is calculated by Equation 1 below.

[Equation 1]

VEB=VE-VB,

VEB=VF(D1)+VF(D2)-VF(D3)-Ron(Q1)*Io=VF-Ron(Q1)*Io,

VE=V1-Ron(Q1)*Io-VF(D3), VB=V1-VF(D1)-VF(D2)

Here, VEB is the voltage between the emitter E and the base B of the third transistor Q3, VE is the emitter E voltage of the third transistor Q3, VB is the third transistor Q3 ) Is the base (B) voltage, VF is the forward voltage of the diode, Ron (Q1) is the on resistance of the first transistor Q1 (on resistance), and Io is the current flowing through the first transistor Q1. .

In the normal state, it is assumed, for example, that the first voltage (V1) = 12 V, Ron (Q1) = 0.04 dB, Io = 3 A, and VF = 0.7 V. According to Equation 1, the voltage (VEB(Q3)) between the emitter E and the base B of the third transistor Q3 = 0.7-0.12V = 0.58V, and the third transistor Q3 The voltage (VEB(Q3)) between the emitter E and the base B is less than 0.7V. Accordingly, since the third transistor Q3 operates in a cutoff region, the third transistor Q3 is turned off. At this time, the second voltage V2=V1-Ron(Q1)*Io=11.88V.

In addition, in an abnormal state, for example, the first voltage V1 and the second voltage V2 are both 12V and the first voltage V1 is less than the second voltage V2 (for example, 10V). It is when falling. In this abnormal state, the emitter voltage VE of the third transistor Q3=V2-VF(D3)=11.88-0.7=11.18V, the base voltage VB of the third transistor Q3=V1-VF( D2)-F(D3)=10-0.7-0.7=8.6V, and the third transistor is turned on. That is, the voltage (VEB(Q3)) between the emitter E and the base B of the third transistor Q3 becomes 2.58V (11.18-8.6=2.58V), so that the third transistor Q3 is active or It operates in the saturation region (2.58V> 0.7V). Therefore, the third transistor Q3 is turned on.

In addition, the voltage VSG between the source and the gate of the first transistor Q1 is between the forward voltage VF of the third diode D3 and the emitter E and the collector C of the third transistor Q3. The sum of the voltages VEC {VSG(Q1) = VF(D3)+VEC(Q3)}, and the voltage VEC between the emitter E and the collector C of the third transistor Q3 is almost 0V. Thus, the voltage between the source and the gate of the first transistor Q1 is about 0.7V, which is lower than the threshold voltage (2V) of the first transistor Q1. Therefore, the first transistor Q1 is turned off and the reverse voltage is not introduced into the battery 10 by the internal diode Di of the first transistor Q1.

Therefore, in the abnormal state, the third transistor Q3 is turned on and the first transistor Q1 is turned off, such that the third diode D3, the third transistor Q3, the second resistor R2, and the fourth diode D4 are turned on. , And a reverse voltage current path Ro via the second transistor Q2 is formed. Therefore, discharge from the second voltage V2 to the first voltage V1 does not occur, and the second voltage V2 can be continuously maintained. In order to reduce the current through which the second voltage V2 is discharged, the second resistor R2 is not set too small.

Hereinafter, a battery system according to another embodiment will be described with reference to FIGS. 3 and 4. 3 is a battery system according to another embodiment, and FIG. 4 is a reverse voltage current path of the reverse voltage protection circuit according to another embodiment.

Referring to FIG. 3, the battery system 2 includes a first battery 10a, a second battery 10b, a reverse voltage protection circuit 21, a BMS, and a load, and the first battery 10a, The 2 battery 10b is connected to the load through the reverse voltage protection circuit 21 and the BMS.

In the battery system 2, two batteries 10a and 10b are connected to the BMS, and the reverse voltage protection circuit 21 includes a fifth diode D5 and the battery system 1 according to the embodiment. It is different and the rest of the configuration is the same as that of the battery system 1, so the description is omitted.

The first battery 10a may be a lead acid battery and the output voltage may be a third voltage, for example, 16V, but embodiments are not limited thereto.

The second battery 10b may be a lithium ion battery and the output voltage may be a fourth voltage, for example, 12V, but the embodiment is not limited thereto.

Only the battery having a high output voltage among the first battery 10a and the second battery 10b is selected and connected to the load.

The fifth diode D5 includes an anode connected to the second battery 10b and a cathode connected to a load, and blocks reverse voltage from being applied to the second battery 10b in an abnormal state. The fifth diode D5 may be replaced with a reverse voltage protection circuit 21.

The BMS measures the first voltage V1a of the first battery 10a or the first voltage V1b of the second battery 10b, measures the voltage of the second voltage V2, and has a high level (for example, For example, a control signal Vcc of the second transistor Q2 of 5V) is generated.

Referring to FIG. 4, in the standby state, even if the first voltage V1a or the first voltage V1b passes through the internal diode Di of the first transistor Q1, the BMS supplies the control signal Vcc. Do not Since there is no current passing through the Zener diode ZD or the third transistor Q3, the source-gate voltage VSG of the first transistor Q1 becomes 0 V, and there is no leakage current caused by the reverse voltage preventing circuit 20. .

In the normal state, the third transistor Q3 is turned off, and the first voltage V1a or the first voltage V1b passes through the internal diode Di of the first transistor Q1 and a high level control signal in the BMS When (Vcc) is supplied, a current path (Lo) passing through the Zener diode (ZD), the second resistor (R2), the fourth diode (D4), and the second transistor (Q2) is generated.

In the abnormal state, the third transistor Q3 is turned on and the first transistor Q1 is turned off, such that the third diode D3, the third transistor Q3, the second resistor R2, the fourth diode D4, And a reverse voltage current path Ro passing through the second transistor Q2. The second voltage V2 is connected to the ground through the reverse voltage current path Ro.

In addition, in the abnormal state, when the first voltage V1b is higher than the first voltage V1a, the first transistor Q1 is turned off, and the third diode D3, the third transistor Q3, and the second resistor ( R2), a fourth diode D4, and a reverse voltage current path Ro through the second transistor Q2 are formed. The second voltage V2 is connected to the ground through the reverse voltage current path Ro.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to this, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights. Accordingly, the above detailed description should not be construed as limiting in all respects, but should be considered illustrative. The scope of the invention should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

1, 2: Battery system
10: battery
10a: first battery
10b: second battery
20,21: reverse voltage protection circuit

Claims (11)

A battery system including a reverse voltage protection circuit connected between a first battery and a load,
The reverse voltage protection circuit,
A drain connected to the first battery, a source connected to a load, and a first transistor connected to a third transistor collector;
A diode unit connected between the first battery and the base of the third transistor;
The third transistor including an emitter connected to the source of the first transistor, a base connected to the diode portion, and a collector connected to the collector of the second transistor; And
A zener diode connected between the source of the first transistor and the third transistor collector
Including,
When the first voltage on the first battery side is lower than the second voltage on the load side, a reverse voltage current path is formed through the third transistor and the second transistor. According to claim 1,
The diode unit includes a first diode and a second diode,
The first diode and the second diode are connected in series, the battery system. According to claim 2,
The reverse voltage protection circuit,
A third diode comprising an anode connected to the source of the first transistor and a cathode connected to the emitter of the third transistor
Battery system further comprising a. According to claim 3,
The third diode is a diode unit for increasing a difference between an operating voltage of the first voltage and the second voltage
Battery system further comprising a. According to claim 4,
The reverse voltage protection circuit,
A first capacitor comprising one end connected to the cathode of the third diode and the other end connected to ground.
Further comprising, a battery system. The method of claim 5,
The reverse voltage protection circuit,
A fourth diode comprising a cathode connected to the collector of the second transistor and an anode connected to the collector of the third transistor
Further comprising, a battery system. The method of claim 6,
The battery system further comprises a BMS,
Wherein the BMS is configured to apply a control signal to the base of the second transistor. The method of claim 7,
The reverse voltage protection circuit,
A first resistor connected between the cathode of the second diode and the anode of the fourth diode
Further comprising, a battery system. The method of claim 8,
The battery system further includes a second battery,
The reverse voltage protection circuit further includes a fifth diode,
The fifth diode includes an anode connected to the battery and a cathode connected to the other end of the first transistor. The method of claim 9,
When the first voltage on the first battery side is lower than the second voltage, or when the first voltage on the second battery side is higher than the first voltage on the first battery side, the third transistor and the second A battery system in which a reverse voltage current path via a transistor is formed. The method of claim 10,
The BMS is configured to apply a control signal to the base of the second transistor that suppresses leakage current, using at least one of the first battery and the second battery.

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