Precharge relay drive circuit and battery system

Abstract

The present invention relates to a relay driving circuit that generates a gate voltage for controlling the on / off of a pre-charge relay, and a battery system including the same. The relay driving circuit of the present invention is a relay driving circuit that controls an electrical connection between an external device and a battery pack, and includes at least one transistor that receives an enable level control signal and is turned on, a first resistor that has one end connected to a positive electrode of the battery pack when the transistor is turned on and the other end connected to the relay, and a second resistor that is connected between the other end of the first resistor and the external device, and the relay is turned on by receiving power supplied from the battery pack at a ratio of the resistance value of the second resistor to the combined resistance value of the first resistor and the second resistor.

Description

[Technical Field]

[0001] [Cross-reference to related applications] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0004142 dated January 12, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a relay drive circuit that generates a gate voltage for controlling the on / off of a precharge relay, and a battery system including the same. [Background technology]

[0003] A relay is a device that controls the on / off of an electric circuit using a predetermined electric signal, and is classified into mechanical relays and electronic relays depending on the operating principle. A mechanical relay uses an electromagnet, and when an electric current flows through the electromagnet, the magnetic contacts attach to the electrodes, connecting the circuit and controlling the on / off of the electric circuit.

[0004] An electronic relay is a non-contact relay that uses a semiconductor switching element to make and break the electrical circuit, eliminating the need for electrical contacts. It has an electrically isolated input side and an output side made up of semiconductors that has high-load switching capabilities. In other words, an electronic relay controls the on / off state of an electrical circuit by allowing a high-load current to flow to the output side when an electrical signal is applied to the input side. Even with a very small input signal, an electronic relay can control a high-load output signal. Because it has no mechanical moving parts, it has a long lifespan, a fast response speed, and is less susceptible to shock, vibration, and installation positioning, making it more widely used than a mechanical relay.

[0005] Meanwhile, metal-oxide semiconductor field effect transistors (MOSFETs) are widely used as semiconductor switching elements, but power must be applied to the gate to operate the MOSFETs.

[0006] The conventional relay driving circuit includes a separate power supply circuit for driving the semiconductor switching element, which increases the complexity of the relay driving circuit and the circuit area, resulting in additional costs. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a relay driving circuit that controls the on / off of a semiconductor switching element by driving the relay driving circuit with the power supply of a battery pack without a separate power supply circuit, and a battery system including the same. [Means for solving the problem]

[0008] According to one aspect of the present invention, a relay driving circuit for controlling an electrical connection between an external device and a battery pack includes at least one transistor that receives an enable level control signal and turns on; a first resistor having one end connected to a positive electrode of the battery pack and the other end connected to the relay when the transistor turns on; and a second resistor connected between the other end of the first resistor and the external device, and the relay is turned on when power is applied from the battery pack at a ratio of the resistance value of the second resistor to the combined resistance value of the first resistor and the second resistor.

[0009] The relay driving circuit may further include a Zener diode connected in parallel with the second resistor to maintain a voltage level across the second resistor.

[0010] The transistor may include a first transistor that receives an enable level control signal to be turned on, and a second transistor that receives a ground level voltage to be turned on when the first transistor is turned on, thereby electrically connecting the positive electrode of the battery pack and the first resistor.

[0011] According to one aspect of the present invention, a battery system includes: a main relay that controls an electrical connection between an external device and a battery pack; a pre-charge relay that is connected in parallel with the main relay and is turned on before the main relay is turned on and is turned off a predetermined time after the main relay is turned on; a BMS that generates a control signal to control switching of the main relay and the pre-charge relay; and a relay drive circuit that includes at least one transistor that is turned on in response to a first control signal of an enable level from the BMS, a first resistor having one end connected to a positive electrode of the battery pack and the other end connected to the pre-charge relay when the transistor is turned on, and a second resistor connected between the other end of the first resistor and the external device, and controls on / off of the pre-charge relay, wherein the pre-charge relay is turned on by receiving power supplied from the battery pack at a ratio of the resistance value of the second resistor to the combined resistance value of the first resistor and the second resistor.

[0012] The first relay driving circuit may further include a Zener diode connected in parallel with the second resistor to maintain a voltage level across the second resistor.

[0013] The transistor may include a first transistor that receives a first control signal of an enable level to be turned on, and a second transistor that receives a ground level voltage to be turned on when the first transistor is turned on, thereby electrically connecting the positive electrode of the battery pack and the first resistor.

[0014] The precharge relay may include a MOSFET that receives power from the battery pack via a gate terminal and is turned on. [Effects of the Invention]

[0015] The present invention has the effect of simplifying the relay driving circuit, reducing the area, and reducing costs by eliminating a separate power supply circuit provided in the relay driving circuit. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a block diagram illustrating a battery system according to one embodiment. [Figure 2] FIG. 2 is a block diagram illustrating in detail the function of the first relay drive circuit of FIG. 1. [Figure 3] 2 is a block diagram illustrating in detail the function of the second relay drive circuit of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings. Identical or similar components will be designated by the same or similar reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and / or "section" used in the following description for components are added or used interchangeably solely for the convenience of drafting the specification, and do not have any distinct meanings or functions. Furthermore, when describing the embodiments disclosed herein, if a detailed description of related prior art is deemed to obscure the gist of the embodiments disclosed herein, such detailed description will be omitted. Furthermore, the accompanying drawings are intended to facilitate understanding of the embodiments disclosed herein, and the technical concepts disclosed herein should not be limited by the accompanying drawings, and should be understood to include all modifications, equivalents, or alternatives within the concept and technical scope of the present invention.

[0018] Terms including ordinal numbers such as "first," "second," etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0019] When a component is said to be "coupled" or "connected" to another component, it should be understood that it may be directly coupled or connected to the other component, but that there may be other components in between. Conversely, when a component is said to be "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0020] In this application, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0021] FIG. 1 is a block diagram showing a battery system according to one embodiment, FIG. 2 is a block diagram explaining in detail the function of a first relay drive circuit of FIG. 1, and FIG. 3 is a block diagram explaining in detail the function of a second relay drive circuit of FIG. 1.

[0022] Referring to FIG. 1, a battery system 1 includes a battery pack 10, a BMS 20, a relay 30, and a relay drive circuit 40.

[0023] The battery pack 10 has a plurality of battery cells connected in series / parallel to supply a required power supply. In Fig. 1, the battery pack 10 includes a plurality of battery cells connected in series and is connected between two output terminals OUT1 and OUT2 of the battery system 1, and a relay 30 is connected between the positive terminal of the battery system 1 and the output terminal OUT1. The configurations and the connections between the configurations shown in Fig. 1 are merely examples, and the present invention is not limited thereto.

[0024] The BMS 20 can generate a control signal for controlling the switching of the relay 30 and transmit it to the relay driving circuit 40. For example, the BMS 20 transmits a first control signal CS1 and a second control signal CS2 to the relay driving circuit 40 to enable the relay driving circuit 40.

[0025] The relay 30 may include a pre-charge relay 31 and a main relay 33 connected in parallel with the pre-charge relay 31. The relay 30 may be configured as an electronic relay including a semiconductor switching element. For example, the semiconductor switching element may be, but is not limited to, a metal-oxide semiconductor field effect transistor (MOSFET) or a bipolar junction transistor (BJT).

[0026] The pre-charge relay 31 may be implemented as a MOSFET and may be switched in response to an on-level first gate voltage VG1, and may be connected in series with a pre-charge resistor Rf. The pre-charge relay 31 reduces a surge current that occurs when connecting the battery pack 10 to an external device, thereby preventing damage to the main relay 33 due to the surge current. For example, the pre-charge relay 31 may be turned on before the main relay 33 is turned on, and may be turned off after a predetermined time has elapsed since the main relay 33 was turned on, thereby reducing the surge current.

[0027] The main relay 33 is implemented as a bipolar junction transistor (BJT) and can be switched in response to an off-level second gate voltage VG2. The main relay 33 controls an electrical connection between the battery system 1 and an external device (e.g., a load, a charger). When the main relay 33 is turned on, the battery system 1 and the external device are electrically connected to each other, and charging or discharging is performed.

[0028] For example, if the external device is a load, a discharging operation is performed in which power is supplied from the battery pack 10 to the load, and if the external device is a charger, a charging operation is performed in which the battery pack 10 is charged by the charger. When the main relay 33 is turned off, the battery system 1 and the external device are electrically isolated from each other.

[0029] The relay drive circuit 40 may include a first relay drive circuit 41 and a second relay drive circuit 43 .

[0030] The first relay driving circuit 41 receives a first control signal CS1 of an enable level and generates a first gate voltage VG1 capable of turning on the precharge relay 31. The first relay driving circuit 41 may have one end connected to the positive electrode of the battery pack 10 and the other end connected to a first output terminal OUT1 of the battery system 1.

[0031] 2, the first relay drive circuit 41 may include a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2, and a Zener diode ZD. The protection block (PB) shown in FIG. 2 may include various elements such as a fuse to protect the precharge relay 31.

[0032] The base B of the first transistor Q1 receives a first control signal CS1 transmitted from the BMS 20, and the collector C of the first transistor Q1 is connected to the base B of the second transistor Q2. The collector C of the second transistor Q2 is connected to the positive electrode of the battery pack 10, and the emitter E of the second transistor Q2 is connected to one end of the first resistor R1. Specifically, the emitter E of the second transistor Q2 is connected to one end of the second resistor R2, the cathode of the Zener diode ZD, and the gate G of the pre-charge relay 31 via the first resistor R1.

[0033] The first transistor Q1 is an NPN transistor that is turned on when the first control signal CS1 is at a high level and turned off when it is at a low level, while the second transistor Q2 is a PNP transistor that is turned off when the signal input to its base B is at a high level and turned on when it is at a low level.

[0034] For example, when an enable level, e.g., a high level first control signal CS1, is input to the base B of the first transistor Q1, the first transistor Q1 is turned on and the collector C of the first transistor Q1 is connected to ground GND. A ground GND level voltage is applied to the base B of the second transistor Q2, which is connected to the collector C of the first transistor Q1, turning on the second transistor Q2. Then, the positive electrode of the battery pack 10 is connected to the first resistor R1 via the second transistor Q2, and power supplied from the battery pack 10 is applied to the gate of the MOSFET, turning on the precharge relay 31.

[0035] When the second transistor Q2 is turned on, one end of the first resistor R1 is connected to the positive electrode of the battery pack 10, and the other end is connected to the pre-charge relay 31. Specifically, the other end of the first resistor R1 is connected to one end of the second resistor R2, the cathode of the Zener diode ZD, and the gate terminal of the pre-charge relay 31.

[0036] The second resistor R2 is connected between the first resistor R1 and an external device. Specifically, one end of the second resistor R2 is connected to the other end of the first resistor R1, and the other end of the second resistor R2 is connected to the external device via the first output port OUT1 of the battery system 1.

[0037] The Zener diode ZD is connected in parallel with the second resistor R2 and clamps the voltage across the second resistor R2 to the breakdown voltage of the Zener diode ZD, thereby maintaining a constant level of the first gate voltage VG1 applied to the gate G terminal of the precharge relay 31.

[0038] 2, the precharge relay 31 is implemented as a MOSFET and can be switched in response to an on-level first gate voltage VG1. A drain D terminal of the MOSFET is connected to the positive electrode of the battery pack 10, and a source S terminal of the MOSFET is connected to an external device via a first output terminal OUT1 of the battery system 1. The MOSFET is turned on by a first gate voltage VG1 applied to a gate G terminal to electrically connect the battery pack 10 to the external device.

[0039] According to one embodiment, the pre-charge relay 31 may be turned on by receiving power (P=VI) supplied from the battery pack 10 at a ratio (R2 / R1+R2) of the resistance value of the second resistor R2 to the combined resistance value of the first resistor R1 and the second resistor R2. For example, the voltage value of the first gate voltage VG1 may be calculated by multiplying a voltage (V) value corresponding to the power of the battery pack 10 by the ratio (R2 / R1+R2) of the resistance value of the second resistor R2 to the combined resistance value (R1+R2) of the first resistor R1 and the second resistor R2.

[0040] The second relay driving circuit 43 receives a second control signal CS2 of an enable level to turn on the main relay 33. The second relay driving circuit 43 may have one end connected to the positive electrode of the battery pack 10 and the other end connected to the first output terminal OUT1 of the battery system 1.

[0041] 3, the second relay driving circuit 43 may include a third transistor Q3. A base B of the third transistor Q3 receives a second control signal CS2 transmitted from the BMS 20, and a collector C of the third transistor Q3 is connected to the base B of the main relay 33. A protection block (PB) shown in FIG. 3 may include various elements such as a fuse to protect the main relay 33.

[0042] The third transistor Q3 is an NPN transistor that is turned on when the second control signal CS2 is high and turned off when it is low. At this time, the main relay 33 is a PNP transistor that is turned off when the signal input to its base B terminal is high and turned on when it is low.

[0043] For example, when an enable level, e.g., a high level second control signal CS2, is input to the base B of the third transistor Q3, the third transistor Q3 is turned on and the collector C of the third transistor Q3 is connected to the ground GND. A voltage of the ground GND level is applied to the base B of the main relay 33, which is connected to the collector C of the third transistor Q3, and the main relay 33 is turned on. Then, the battery pack 10 and an external device can be electrically connected via the main relay 33.

[0044] That is, in the second relay driving circuit 43, the second gate voltage VG2 is not separately generated using the battery pack 10, but the ground GND level voltage from the third transistor Q3 can perform the function of the second gate voltage VG2 that can turn on the main relay 33.

[0045] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to these, and various modifications and improvements made by those skilled in the art to which the present invention pertains also fall within the scope of the present invention.

Claims

1. A pre-charge relay that controls an electrical connection between an external device and a battery pack, the pre-charge relay being connected in parallel with a main relay that controls the electrical connection between the external device and the battery pack, being turned on before the main relay is turned on, and being turned off after a predetermined time has elapsed since the main relay was turned on, at least one transistor that receives a control signal of an enable level and is turned on; a first resistor having one end connected to the positive electrode of the battery pack when the transistor is turned on and the other end connected to the precharge relay; a second resistor connected between the other end of the first resistor and the external device; The precharge relay is an ON operation when power is applied from the battery pack at a ratio of the resistance value of the second resistor to the combined resistance value of the first resistor and the second resistor; The transistor is a first transistor that receives a control signal of an enable level and is turned on; a second transistor that receives a ground level voltage and turns on when the first transistor is turned on, electrically connecting a positive electrode of the battery pack and the first resistor;

2. The precharge relay driving circuit of claim 1 , further comprising a Zener diode connected in parallel with the second resistor to maintain a voltage level across the second resistor.

3. a main relay that controls an electrical connection between the external device and the battery pack; a precharge relay connected in parallel to the main relay, turned on before the main relay is turned on, and turned off after a predetermined time has elapsed since the main relay was turned on; a BMS that generates a control signal for controlling switching of the main relay and the precharge relay; a relay driving circuit including at least one transistor receiving a first control signal of an enable level from the BMS and turned on; a first resistor having one end connected to a positive electrode of the battery pack and the other end connected to the pre-charge relay when the transistor is turned on; and a second resistor connected between the other end of the first resistor and the external device, and controlling on / off of the pre-charge relay; The precharge relay is an ON operation when power is applied from the battery pack at a ratio of the resistance value of the second resistor to the combined resistance value of the first resistor and the second resistor; The transistor is a first transistor that receives a first control signal at an enable level and is turned on; and a second transistor that receives a ground level voltage and turns on when the first transistor is turned on, electrically connecting a positive electrode of the battery pack and the first resistor;

4. The first relay drive circuit The battery system of claim 3 , further comprising a Zener diode connected in parallel with the second resistor to maintain a voltage level across the second resistor.

5. the relay drive circuit includes a second relay drive circuit that controls on / off of the main relay; the second relay drive circuit includes a third transistor; 5. The battery system according to claim 3, wherein when the third transistor is turned on, the main relay receives a ground level voltage and is turned on.

6. The precharge relay is The battery system according to claim 3 , further comprising a MOSFET that receives power supplied from the battery pack via a gate terminal and is turned on.

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