Discharging circuit for pre-charging capacitor and battery management system

Abstract

The utility model discloses a discharging circuit for a pre-charging capacitor and a battery management system. The circuit comprises a pre-charging module, a discharging element, an MCU, a relay K1, an MOS transistor Q1 and the pre-charging capacitor C1. The pre-charging module comprises a switch S1, a switch S2 and a resistor R1; the switch S2 is connected in series with a power supply path between the battery and the electric equipment; one end of the switch S1 is connected to an intermediate node of the switch S2 and the battery, and the other end of the switch S1 is connected to an intermediate node of the switch S2 and electric equipment after being connected in series with the resistor R1; the pre-charging capacitor C1 is connected in parallel with two ends of the electric equipment; one end of the discharge element is connected to an intermediate node of the switch S1 and the resistor R1, and the other end of the discharge element is grounded through the relay K1 and the MOS tube Q1; and the MCU receives a power-off instruction, the S2 is switched off, the K1 or the Q1 is switched on, and the electric energy on the C1 is consumed through the discharge element. An active discharging mode is adopted, extra energy consumption caused by a discharging element is avoided, and the discharging speed is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of capacitor discharge control, and in particular to a discharge circuit for pre-charging capacitor and a battery management system. BACKGROUND

[0002] In power electronic systems, especially in electric vehicles, energy storage systems and various battery-powered electrical equipment, pre-charging is an important part of the power supply process. After the system is powered on, the battery first charges the pre-charging capacitor, and then supplies power to the electrical equipment after the pre-charging is completed, thereby effectively avoiding the impact of transient large current;

[0003] When the system is powered off and the battery stops supplying power, there may still be electrical energy remaining on the pre-charging capacitor. If this electrical energy is not released in time, it may cause electric shock risk, damage to electrical equipment or affect the restart of the system. Therefore, the electrical energy on the pre-charging capacitor also needs to be released in time after the system is powered off to ensure system safety.

[0004] The traditional discharge method usually connects a resistor in parallel across the pre-charging capacitor and relies on the natural discharge process of the capacitor itself, but this may take a long time, and the resistor will also consume part of the energy when the battery is supplying power since it is always connected in the high-voltage loop, resulting in additional power consumption. CONTENT OF THE INVENTION

[0005] To solve the above technical problems, the present application provides a discharge circuit for pre-charging capacitor and a battery management system.

[0006] In a first aspect, the present application provides a discharge circuit for pre-charging capacitor, which adopts the following technical solution:

[0007] The discharge circuit for pre-charging capacitor comprises a pre-charging module, a discharge element, an MCU, a relay K1, a MOS tube Q1 and a pre-charging capacitor C1.

[0008] The pre-charging module comprises a switch S1, a switch S2 and a resistor R1.

[0009] The switch S2 is connected in series on the power supply path between the battery and the electrical equipment. One end of the switch S1 is connected to the intermediate node of the switch S2 and the battery, and the other end of the switch S1 is connected to the intermediate node of the switch S2 and the electrical equipment after being connected in series with the resistor R1. The pre-charging capacitor C1 is connected in parallel across the electrical equipment.

[0010] One end of the discharge element is connected to the intermediate node of the switch S1 and the resistor R1, and the other end is connected to ground through the relay K1 and the MOS tube Q1 respectively.

[0011] The MCU is configured to close the switch S1 to pre-charge the pre-charge capacitor C1 through the battery via the resistor R1 when receiving a power-on instruction; the MCU is further configured to open the switch S1 and close the switch S2 to supply power to the electric device via the battery when the pre-charge of the pre-charge capacitor C1 is completed; and the MCU is further configured to open the switch S2 and close the relay K1 or turn on the MOS tube Q1 to consume the electric energy on the pre-charge capacitor C1 via the discharging element when receiving a power-off instruction.

[0012] By adopting the technical scheme, when the battery supplies power to the electric device, the switch device on the path where the discharging element is located is opened, and the discharging element does not consume the battery energy; when receiving a power-off instruction to stop supplying power to the electric device, the MCU quickly controls the switch device on the discharging circuit to be closed, so that the pre-charge capacitor C1 and the discharging element form a discharging path, and an active discharging mode is adopted to avoid the discharging element from consuming additional energy and to achieve a relatively fast discharging speed; the relay K1 and the MOS tube Q1 are provided as two switch devices to form two discharging paths, and in a scenario where the pre-charge capacitor C1 has a relatively large discharging current or a sharp peak current, the relay K1 is used for discharging; in a scenario where the pre-charge capacitor C1 has a relatively small discharging current, a relatively stable discharging current, or a relatively high discharging speed requirement, the MOS tube Q1 is used for discharging, thereby improving the reliability and wide applicability of the circuit; and the discharging element is connected to one end of the resistor R1, so that the resistor R1 participates in the pre-charge process and the discharging process, thereby achieving multiple applications of the resistor R1 in the pre-charge and discharging processes, improving the utilization rate, and reducing the cost and space occupation to a certain extent.

[0013] In a specific implementation, the discharging circuit further comprises an isolation driving module; the isolation driving module is connected between the MCU and the control end of the MOS tube Q1, and the MCU is configured to drive the MOS tube Q1 to be turned on via the isolation driving module.

[0014] The isolation driving module comprises a transistor Q2, a gate driving optocoupler, a resistor R2 and a resistor R3.

[0015] The anode pin of the gate driving optocoupler is connected to a power supply voltage Vcc1 via the resistor R3, and the cathode pin of the gate driving optocoupler is grounded via the transistor Q2; the control end of the transistor Q2 is connected to the MCU.

[0016] The output pin of the gate driving optocoupler is connected to the control end of the MOS tube Q1 via the resistor R2, the power supply pin of the gate driving optocoupler is connected to a power supply voltage Vcc2, and the ground pin of the gate driving optocoupler is grounded.

[0017] The MCU is configured to drive the triode Q2 to be turned on, so that the gate drive optocoupler is turned on, and the output pin of the gate drive optocoupler outputs a high level to drive the MOS tube Q1 to be turned on.

[0018] By adopting the above technical solutions, the isolation driving module is added between the MCU and the MOS tube Q1, so that the MCU controls the on-off of the MOS tube Q1 through the isolation driving module; and the triode Q2 and the gate drive optocoupler are used in the isolation driving module, so that the high and low voltages are isolated, and the safety of the circuit is improved.

[0019] In a specific implementable embodiment, the isolation driving module further comprises a resistor R4 and a resistor R5.

[0020] The resistor R4 is connected in series between the MCU and the control end of the triode Q2, and one end of the resistor R5 is connected to the control end of the triode Q2 and the other end is grounded.

[0021] In a specific implementable embodiment, the discharge circuit further comprises a protection module; one end of the protection module is connected to the discharge element, and the other end is connected to the relay K1 and the MOS tube Q1 respectively; and the protection module is configured to prevent the reverse flow of current.

[0022] The protection module comprises one or more diodes connected in series.

[0023] By adopting the above technical solutions, the anti-reverse diode is added in the discharge circuit of the pre-charge capacitor C1, so that the safety of the circuit is improved.

[0024] In a specific implementable embodiment, the discharge element comprises a fuse and / or a resistor.

[0025] In a specific implementable embodiment, the switch S1 and the switch S2 are relays.

[0026] In a specific implementable embodiment, the MOS tube Q1 is an NMOS tube.

[0027] In a second aspect, the application provides a battery management system, which adopts the following technical solutions: the battery management system comprises the discharge circuit for the pre-charge capacitor in the first aspect or any of the implementable embodiments of the first aspect.

[0028] The one or more technical solutions provided in the embodiments of the application have at least the following technical effects or advantages:

[0029] 1. When the battery supplies power to the device, the switching device on the path where the discharge element is located is open, and the discharge element does not consume battery energy. When the power-down command is received and the power supply to the device is stopped, the MCU quickly controls the switching device on the discharge circuit to close, so that the pre-charge capacitor C1 and the discharge element form a discharge path. The active discharge method is adopted to avoid the discharge element causing additional energy consumption, and the discharge speed is faster.

[0030] 2. By setting up two switching devices, relay K1 and MOSFET Q1, two discharge paths are formed. When the discharge current of the pre-charge capacitor C1 is large or has peak current, the relay K1 path is used for discharge; when the discharge current of the pre-charge capacitor C1 is small, the discharge current is relatively stable, or the discharge speed requirement is relatively high, the MOSFET Q1 path is used for discharge, which improves the reliability and wide applicability of the circuit.

[0031] 3. By connecting the discharge element to one end of the resistor R1, the resistor R1 can participate in both the pre-charge and discharge processes, realizing multiple applications of the resistor R1 in the pre-charge and discharge processes, with high utilization rate, and reducing cost and space occupation to a certain extent. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a discharge circuit used for pre-charged capacitors in an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Precharge module; 2. Discharge element; 3. MCU; 4. Isolation drive module; 5. Protection module. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0036] In the description of the embodiments of this application, the words "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design that is described as "for example" or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Rather, the use of the words "for example" or "for instance" is intended to present the relevant concepts in a specific manner.

[0037] In the description of the embodiments of the present application, the term "a plurality of" means two or more. The terms "comprise", "contain", "have" and their conjugates mean "including but not limited to", unless otherwise specifically emphasized.

[0038] The embodiments of the present application provide a discharge circuit for pre-charging a capacitor, as shown in the accompanying drawings, the discharge circuit comprises a pre-charging module 1, a discharge element 2, an MCU 3, a relay K1, a MOS tube Q1 and a pre-charging capacitor C1. Figure 1

[0039] The pre-charging module 1 comprises a switch S1, a switch S2 and a resistor R1.

[0040] The switch S2 is connected in series on the power supply path between the battery and the electrical equipment; one end of the switch S1 is connected to the intermediate node of the switch S2 and the battery, and the other end of the switch S1 is connected to the intermediate node of the switch S2 and the electrical equipment after being connected in series with the resistor R1; the pre-charging capacitor C1 is connected in parallel across the electrical equipment.

[0041] One end of the discharge element 2 is connected to the intermediate node of the switch S1 and the resistor R1, and the other end is connected to the ground through the relay K1 and the MOS tube Q1 respectively.

[0042] The MCU 3 is configured to close the switch S1 to pre-charge the pre-charging capacitor C1 through the resistor R1 when receiving a power-on instruction; the MCU 3 is further configured to open the switch S1 and close the switch S2 to supply power to the electrical equipment by the battery when the pre-charging capacitor C1 is pre-charged; the MCU 3 is further configured to open the switch S2 and close the relay K1 or turn on the MOS tube Q1 to consume the electric energy on the pre-charging capacitor C1 through the discharge element 2 when receiving a power-off instruction.

[0043] As understood by those skilled in the art, when the relay K1 is closed, the pre-charging capacitor C1, the resistor R1, the discharge element 2 and the relay K1 form a discharge circuit; when the MOS tube Q1 is closed, the pre-charging capacitor C1, the discharge element 2 and the MOS tube Q1 form a discharge circuit.

[0044] ​Therefore, when the battery supplies power to the electrical equipment, the switch device on the path where the discharging element 2 is located is turned off, and the discharging element 2 does not consume the battery energy. When receiving a power-off instruction and stopping supplying power to the electrical equipment, the MCU 3 quickly controls the switch device on the discharging circuit to be closed, so that the pre-charging capacitor C1 and the discharging element 2 form a discharging path, and an active discharging mode is adopted to avoid additional energy consumption caused by the discharging element 2 and to achieve a faster discharging speed. In addition, the relay K1 and the MOS tube Q1 are provided as two switch devices to form two discharging paths. In a scenario where the pre-charging capacitor C1 has a large discharging current or a sharp current, the relay K1 is used for discharging. In a scenario where the pre-charging capacitor C1 has a small and stable discharging current or a high discharging speed requirement, the MOS tube Q1 is used for discharging, thereby improving the reliability and wide applicability of the circuit. Moreover, the discharging element 2 is connected to one end of the resistor R1, so that the resistor R1 participates in the pre-charging process and the discharging process, thereby realizing multiple applications of the resistor R1 in the pre-charging and discharging processes, improving the utilization rate, and reducing the cost and space occupation to a certain extent.

[0045] In a possible implementation, as shown in Figure 1 the discharging circuit further comprises an isolation driving module 4; the isolation driving module 4 is connected between the MCU 3 and the control end of the MOS tube Q1, and the MCU 3 is configured to drive the MOS tube Q1 to be turned on through the isolation driving module 4.

[0046] The isolation driving module 4 comprises a transistor Q2, a gate driving optocoupler, a resistor R2 and a resistor R3.

[0047] The anode pin of the gate driving optocoupler is connected to a power supply voltage Vcc1 through the resistor R3, and the cathode pin of the gate driving optocoupler is grounded through the transistor Q2. The control end of the transistor Q2 is connected to the MCU 3.

[0048] The output pin of the gate driving optocoupler is connected to the control end of the MOS tube Q1 through the resistor R2, the power supply pin of the gate driving optocoupler is connected to a power supply voltage Vcc2, and the ground pin of the gate driving optocoupler is grounded.

[0049] The MCU 3 is configured to drive the transistor Q2 to be turned on, so that the gate driving optocoupler is turned on, the output pin of the gate driving optocoupler outputs a high level, and the MOS tube Q1 is driven to be turned on.

[0050] Preferably, the model of the gate driving optocoupler is TLP350.

[0051] The skilled in the art can understand that when it is needed to control the MOS tube Q1 to be turned on, the MCU 3 outputs low level to the control end of the triode Q2, then the triode Q2 is turned on and the diode in the gate drive optocoupler is turned on, so that the output pin of the gate drive optocoupler outputs high level to drive the MOS tube Q1 to be turned on.

[0052] Therefore, the isolation driving module 4 is added between the MCU 3 and the MOS tube Q1, so that the MCU 3 controls the MOS tube Q1 to be turned on or off through the isolation driving module 4; and the triode Q2 and the gate drive optocoupler in the isolation driving module 4 can isolate high and low voltage, so as to improve the safety of the circuit.

[0053] In a possible implementation, as shown in Figure 1 the isolation driving module 4 further comprises a resistor R4 and a resistor R5;

[0054] The resistor R4 is connected in series between the MCU 3 and the control end of the triode Q2, and one end of the resistor R5 is connected to the control end of the triode Q2 and the other end is grounded.

[0055] The skilled in the art can understand that the resistor R4 and the resistor R5 are used to configure the turn-on current of the triode Q2.

[0056] In a possible implementation, as shown in Figure 1 the discharge circuit further comprises a protection module 5; one end of the protection module 5 is connected to the discharge element 2 and the other end is connected to the relay K1 and the MOS tube Q1 respectively; and the protection module 5 is used to prevent current from flowing backward.

[0057] The protection module 5 comprises one or more diodes connected in series. Figure 1 A case where the protection module 5 comprises one diode is shown.

[0058] Therefore, the anti-reverse diode is added in the discharge circuit of the pre-charge capacitor C1, so as to improve the safety of the circuit.

[0059] In a possible implementation, the discharge element 2 comprises a fuse and / or a resistor. As shown in Figure 1 the discharge element 2 comprises a fuse. Figure 1 A case where the discharge element 2 comprises one fuse is shown, and the skilled in the art can design one resistor or a combination of multiple resistors in series or in parallel according to actual needs, which is not limited in the present application.

[0060] In a possible implementation, the switch S1 and the switch S2 are relays.

[0061] In a possible implementation, the MOS tube Q1 is an NMOS tube.

[0062] The embodiment of the application provides a battery management system, comprising the discharge circuit for pre-charging capacity described in the above embodiment.

[0063] The above are preferred embodiments of the application, and do not limit the protection scope of the application, so: all equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A discharge circuit for pre-charged capacitors, characterized by, It comprises a pre-charging module (1), a discharging element (2), an MCU (3), a relay K1, a MOS tube Q1 and a pre-charging capacitor C1; The pre-charging module (1) comprises a switch S1, a switch S2 and a resistor R1; The switch S2 is connected in series on the power supply path between the battery and the electrical equipment; one end of the switch S1 is connected to the intermediate node of the switch S2 and the battery, and the other end of the switch S1 is connected to the intermediate node of the switch S2 and the electrical equipment after being connected in series with the resistor R1; the pre-charging capacitor C1 is connected in parallel across the electrical equipment; One end of the discharging element (2) is connected to the intermediate node of the switch S1 and the resistor R1, and the other end is grounded through the relay K1 and the MOS tube Q1 respectively; The MCU (3) is used for closing the switch S1 to make the battery pre-charge the pre-charging capacitor C1 through the resistor R1 when receiving a power-on instruction; the MCU (3) is also used for opening the switch S1 and closing the switch S2 to make the battery supply power to the electrical equipment after the pre-charging capacitor C1 is pre-charged; the MCU (3) is also used for opening the switch S2 and closing the relay K1 or turning on the MOS tube Q1 to consume the electric energy on the pre-charging capacitor C1 through the discharging element (2) when receiving a power-off instruction.

2. The discharge circuit for pre-charged capacitors of claim 1, wherein, It also comprises an isolation driving module (4); the isolation driving module (4) is connected between the MCU (3) and the control end of the MOS tube Q1; the MCU (3) is used for driving the MOS tube Q1 to be turned on through the isolation driving module (4); The isolation driving module (4) comprises a transistor Q2, a gate driving optocoupler, a resistor R2 and a resistor R3; The anode pin of the gate driving optocoupler is connected to the power supply voltage Vcc1 through the resistor R3, and the cathode pin of the gate driving optocoupler is grounded through the transistor Q2; the control end of the transistor Q2 is connected to the MCU (3); The output pin of the gate driving optocoupler is connected to the control end of the MOS tube Q1 through the resistor R2, the power supply pin of the gate driving optocoupler is connected to the power supply voltage Vcc2, and the ground pin of the gate driving optocoupler is grounded; The MCU (3) is used for making the gate driving optocoupler be turned on by driving the transistor Q2 to be turned on, so that the output pin of the gate driving optocoupler outputs a high level to drive the MOS tube Q1 to be turned on.

3. The discharge circuit for pre-charged capacitors of claim 2, wherein, The isolation driving module (4) further comprises a resistor R4 and a resistor R5; The resistor R4 is connected in series between the MCU (3) and the control end of the transistor Q2, and one end of the resistor R5 is connected to the control end of the transistor Q2 and the other end is grounded.

4. The discharge circuit for pre-charged capacitors of claim 1, wherein, It also comprises a protection module (5); one end of the protection module (5) is connected to the discharging element (2), and the other end is connected to the relay K1 and the MOS tube Q1 respectively; the protection module (5) is used for preventing current from flowing backward; The protection module (5) comprises one or more series-connected diodes.

5. The discharge circuit for pre-charged capacitors of claim 1, wherein, The discharge element (2) comprises a fuse and / or a resistor.

6. The discharge circuit for pre-charged capacitors of claim 1, wherein, The switch S1 and the switch S2 are relays.

7. The discharge circuit for pre-charged capacitors of claim 1, wherein, The MOS tube Q1 is an NMOS tube.

8. A battery management system, characterized by, A discharge circuit for pre-charging a capacitor according to any one of claims 1-7.

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