A pre-charging device, a control method of the pre-charging device, a battery pack and a vehicle

Abstract

The embodiment of the present application relates to the technical field of circuit, and discloses a pre-charging device, a control method of the pre-charging device, a battery pack and a vehicle, in which the first end of an energy storage circuit is used for coupling the first end of a power battery, the first end of a switch circuit is coupled to the second end of the energy storage circuit, the first end of a voltage reduction circuit is used for coupling the first end of the power battery, the second end of the voltage reduction circuit is coupled to the switch circuit, the first end of a pre-charging capacitor is coupled to the second end of the switch circuit, and the second end of the pre-charging capacitor is used for coupling the second end of the power battery. The voltage reduction circuit is used for reducing the first voltage input at the first end of the voltage reduction circuit to a second voltage, and outputting the second voltage through the second end of the voltage reduction circuit. The switch circuit is used for turning on the first end of the switch circuit and the second end of the switch circuit based on the second voltage, so that the power battery charges the pre-charging capacitor through the energy storage circuit. The technical scheme of the present application can reduce the hardware cost.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, and more specifically to a pre-charging device, a control method for the pre-charging device, a battery pack, and a vehicle. Background Technology

[0002] As semiconductor technology matures, power devices are gradually being used to replace precharge relays and precharge resistors, thereby reducing the size and cost of precharge devices.

[0003] Typically, low-voltage drive power devices are required to turn on or off to precharge the pre-charge capacitor. However, the output voltage of the power battery is high-voltage. Related technologies incorporate isolation circuits between the power devices and the power battery to isolate the high-voltage side from the low-voltage side.

[0004] However, in related technologies, not only is it necessary to introduce isolation circuits, but also to set up low-voltage power supplies to drive power devices. Therefore, there is a technical problem of high hardware costs. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a pre-charging device, a control method for the pre-charging device, a battery pack, and a vehicle, which aims to solve the technical problem of high hardware cost in the prior art.

[0006] In a first aspect, embodiments of this application provide a pre-charging device, including: an energy storage circuit, a switching circuit, a step-down circuit, a pre-charging capacitor, and the switching circuit. A first terminal of the energy storage circuit is coupled to a first terminal of a power battery. A first terminal of the switching circuit is coupled to a second terminal of the energy storage circuit. A first terminal of the step-down circuit is coupled to the first terminal of the power battery. A second terminal of the step-down circuit is coupled to the switching circuit. A first terminal of the pre-charging capacitor is coupled to the second terminal of the switching circuit. The second terminal of the pre-charging capacitor is coupled to a second terminal of the power battery. The step-down circuit is configured to reduce a first voltage input to its first terminal to a second voltage, and output the second voltage through its second terminal. The switching circuit is configured to, based on the second voltage, connect the first terminal and the second terminal of the switching circuit, so that the power battery charges the pre-charging capacitor through the energy storage circuit.

[0007] In this embodiment, the step-down circuit reduces the first voltage input from the power battery to a second voltage and outputs it to the switching circuit, allowing power to be drawn from the power battery to supply power to the switching circuit. Furthermore, the step-down circuit also isolates the high-voltage power from the power battery side from the low-voltage power from the switching circuit side. Simultaneously, the switching circuit conducts its first and second terminals based on the second voltage, enabling the power battery to charge the pre-charge capacitor through the energy storage circuit. This allows the stable second voltage provided by the step-down circuit to serve as a control signal source for the switch, ensuring the switching circuit operates under defined voltage conditions. This ensures the pre-charge capacitor receives a controlled charging current from the energy storage circuit, achieving stable pre-charging. The energy storage circuit is connected in series between the power battery and the pre-charge capacitor. It absorbs potential current spikes or voltage fluctuations during charging, mitigating direct impact on the pre-charge capacitor and extending its lifespan, as well as that of subsequent loads. By incorporating a step-down circuit, this application eliminates the need for an isolation circuit and a low-voltage power supply, enabling power supply and control of the switching circuit while reducing the hardware cost of the pre-charging device.

[0008] In some embodiments, the step-down circuit includes: a first switching sub-circuit, a step-down sub-circuit, and a power amplifier sub-circuit. A first terminal of the first switching sub-circuit is coupled to a first terminal of the power battery. A first terminal of the step-down sub-circuit is coupled to a second terminal of the first switching sub-circuit. A second terminal of the step-down sub-circuit is coupled to a switching circuit. A third terminal of the step-down sub-circuit is coupled to a first terminal of the pre-charge capacitor and a first voltage reference terminal. A first terminal of the power amplifier sub-circuit is coupled to a first terminal of the step-down sub-circuit. A second terminal of the power amplifier sub-circuit is coupled to a second terminal of the step-down sub-circuit. The first switching sub-circuit is configured to connect the first terminal of the first switching sub-circuit and the second terminal of the first switching sub-circuit when pre-charging the pre-charge capacitor.

[0009] In this embodiment, the buck circuit includes a first switching sub-circuit, a buck sub-circuit, and a power amplifier sub-circuit. The first switching sub-circuit is used to turn on its first and second terminals when pre-charging the pre-charge capacitor. It can selectively connect the power battery's energy to the buck sub-circuit during the pre-charging phase and disconnect it during the non-pre-charging phase to cut off the power consumption path, thereby reducing the static loss of the entire buck circuit in standby mode. Based on the hardware connection relationship of the buck sub-circuit, the bucked second voltage can drive the switching circuit, reducing the need for an additional reference voltage source. By using the power amplifier sub-circuit to amplify the current of the bucked signal or enhance its driving capability, a second voltage with sufficient driving capability is provided to the switching circuit, avoiding insufficient conduction of the switching circuit due to excessively high output impedance of the buck sub-circuit.

[0010] In some embodiments, the step-down sub-circuit includes: a first resistor, a Zener diode, a first capacitor, and a second capacitor. The first end of the first resistor is coupled to the second end of the first switching sub-circuit. The first end of the Zener diode is coupled to the second end of the first resistor. The second end of the Zener diode is coupled to a first voltage reference terminal. The voltage between the first and second ends of the Zener diode is a second voltage. The first end of the first capacitor is coupled to the first end of the Zener diode. The second end of the first capacitor is coupled to the second end of the Zener diode. The first end of the second capacitor is coupled to the second end of the power amplifier sub-circuit. The second end of the second capacitor is coupled to the first voltage reference terminal.

[0011] In this embodiment, the specific structure of the buck converter sub-circuit is defined. A first resistor limits the input current to prevent overcurrent damage to the Zener diode. Simultaneously, the reverse breakdown characteristic of the Zener diode generates a stable second voltage between its first and second terminals, thus obtaining a reference voltage unaffected by fluctuations in the power battery voltage, providing precise control levels for subsequent switching circuits. A first capacitor connected in parallel across the Zener diode filters out high-frequency noise or transient spikes that may be generated during Zener diode operation, resulting in a smoother second voltage and improved stability of the switching circuit control signal. A second capacitor further filters the output of the power amplifier sub-circuit, suppressing ripple that may be introduced after amplification, thereby providing a clean drive voltage for the switching circuit and preventing switch malfunctions due to voltage ripple. Based on the buck converter sub-circuit provided in this application, stable buck and filtering effects can be achieved with lower cost and fewer components, which is beneficial for improving the anti-interference capability of the pre-charging device in complex electromagnetic environments.

[0012] In some embodiments, the power amplifier sub-circuit includes: a second resistor and a transistor, the first end of the second resistor being coupled to the second end of the first switching sub-circuit, the first end of the transistor being coupled to the first end of the Zener diode, the second end of the transistor being coupled to the second end of the second resistor, the third end of the transistor being coupled to the first end of the second capacitor, and the first end of the switching circuit.

[0013] In this application embodiment, the specific structure of the power amplifier sub-circuit is defined. Utilizing the current amplification characteristics of the transistor, the stable voltage output from the Zener diode is used as the base bias, allowing the transistor to operate in the amplification or saturation region. This converts the high-impedance, low-current second voltage generated by the buck converter into a low-impedance, high-current driving capability, meeting the drive current requirements of the switching circuit. The second resistor provides a suitable operating point current for the transistor while limiting the current flowing through it to prevent damage due to overcurrent, thereby improving the long-term reliability of the power amplifier sub-circuit. The power amplifier sub-circuit provided in this application, through a simple discrete component power amplifier structure, eliminates the need for integrated operational amplifiers or dedicated driver chips, achieving the conversion from a high-impedance voltage source to a low-impedance voltage source. This helps reduce device cost and complexity while maintaining reliable driving of the switching circuit.

[0014] In some embodiments, the first switching sub-circuit includes: a reverse protection diode and a first optocoupler switch. The first terminal of the reverse protection diode is coupled to the first terminal of the power battery. The first terminal of the first optocoupler switch is coupled to the second terminal of the reverse protection diode. The second terminal of the first optocoupler switch is coupled to the first terminal of the step-down sub-circuit. The third terminal of the first optocoupler switch is used to input a first control signal. The fourth terminal of the first optocoupler switch is coupled to a second voltage reference terminal. The first optocoupler switch is configured to: when precharging the pre-charge capacitor, conduct the third terminal and the fourth terminal of the first optocoupler switch based on the first control signal, so that the first terminal and the second terminal of the first optocoupler switch are connected.

[0015] In this embodiment, the specific structure of the first switching sub-circuit is defined. Utilizing the unidirectional conductivity of the diode, the reverse current flowing from the step-down circuit or subsequent circuit to the power battery is blocked, preventing the energy from the energy storage circuit or pre-charge capacitor from flowing back into the battery when pre-charging ends or the system loses power, thus protecting the power battery from reverse voltage surges. During pre-charging of the pre-charge capacitor, the first optocoupler switch conducts its third and fourth terminals based on the first control signal, making the first and second terminals conduct. Utilizing the electrical isolation characteristics of the optocoupler switch, the low-voltage control signal is completely isolated from the high-voltage power battery circuit, thereby preventing high-voltage side interference or faults from propagating to the low-voltage control circuit through the control circuit, improving system safety and anti-interference capabilities. The first switching sub-circuit provided in this application, through the series connection of the anti-reverse diode and the optocoupler switch, achieves on-demand access during the pre-charging stage and also provides directional protection and electrical isolation functions.

[0016] In some embodiments, the switching circuit includes: a switching device and a second switching sub-circuit, a first terminal of the switching device being coupled to a second terminal of the energy storage circuit, a second terminal of the switching device being coupled to a pre-charge capacitor, a first terminal of the second switching sub-circuit being coupled to a second terminal of a step-down circuit, and a second terminal of the second switching sub-circuit being coupled to a controlled terminal of the switching device. The second switching sub-circuit is configured to: when pre-charging the pre-charge capacitor, connect the first terminal of the second switching sub-circuit and the second terminal of the second switching sub-circuit.

[0017] In this embodiment, the specific structure of the switching circuit is defined. The switching device is coupled between the energy storage circuit and the pre-charge capacitor. A second switching sub-circuit serves as an intermediate part, selectively applying the second voltage output from the step-down circuit to the controlled terminal of the switching device. This enables indirect control of the switching device's on / off state. By switching the second switching sub-circuit on and off, the second voltage can be quickly transmitted to the controlled terminal. Simultaneously, the second switching sub-circuit itself possesses a certain driving capability, which helps improve the switching speed of the switching device. Furthermore, separating the switching device from the second switching sub-circuit allows for separation of the power path and control path in the layout, reducing interference from high current to the control signal.

[0018] In some embodiments, the second switching sub-circuit includes: a second optocoupler switch, a first terminal of which is coupled to a second terminal of a step-down circuit, a second terminal of which is coupled to a controlled terminal of a switching device, a third terminal of which is used to input a second control signal, and a fourth terminal of which is coupled to a second voltage reference terminal. The second optocoupler switch is configured to: when precharging a precharge capacitor, conduct the third terminal and the fourth terminal of the second optocoupler switch based on the second control signal, thereby connecting the first terminal and the second terminal of the second optocoupler switch.

[0019] In this embodiment, the specific structure of the second switching sub-circuit is defined. During pre-charging, the third and fourth terminals of the second optocoupler switch are turned on based on the second control signal, making the first and second terminals connected. Utilizing the electrical isolation characteristics of the optocoupler switch, the control signal is isolated from the high-voltage side where the controlled terminal of the switching device is located, thereby preventing high voltage from entering the low-voltage control circuit when the switching device experiences a short circuit or breakdown fault, protecting the front-end controller. Simultaneously, the output side of the optocoupler switch exhibits low on-resistance when turned on, allowing the second voltage output from the buck circuit to be transmitted to the controlled terminal of the switching device with almost no attenuation, ensuring that the switching device receives sufficient gate voltage for full conduction, thereby reducing the conduction loss of the switching device. Based on the second switching sub-circuit provided in this application, the integrity of the driving voltage of the switching device is guaranteed while achieving isolation control.

[0020] In some embodiments, the switching circuit further includes: a third switching sub-circuit, a first terminal of which is coupled to the controlled terminal of the switching device, a second terminal of which is coupled to a first voltage reference terminal, and the third switching sub-circuit being configured to: connect the first terminal of the third switching sub-circuit and the second terminal of the third switching sub-circuit when the first terminal of the second switching sub-circuit is disconnected from the second terminal of the second switching sub-circuit.

[0021] In this embodiment, the switching circuit further includes a third switching sub-circuit. When the first and second terminals of the second switching sub-circuit are disconnected, the first and second terminals of the third switching sub-circuit are connected. This provides a low-impedance discharge path for the controlled terminal of the switching device when pre-charging is complete or when the switching device needs to be turned off. This allows the accumulated charge at the controlled terminal (especially the charge stored in the gate capacitor of the switching device) to be quickly discharged to the first voltage reference terminal, thereby ensuring that the switching device is turned off quickly and reliably, avoiding mis-turn-on due to the controlled terminal being floating or residual charge. Without this discharge path, when the second switching sub-circuit is disconnected, the controlled terminal of the switching device may be in a high-impedance state, making it highly susceptible to external electric field interference or leakage current, resulting in uncertain voltage and causing the switching device to turn on unexpectedly, potentially leading to overcharging of the pre-charge capacitor or system failure. By actively pulling down the third switching sub-circuit, the potential of the controlled terminal can be forcibly pulled down to the potential of the first voltage reference terminal, thereby forcibly turning off the switching device. Based on the switching circuit provided in this application, the third switching sub-circuit and the second switching sub-circuit form a complementary drive. The second switching sub-circuit is responsible for applying voltage when conducting, and the third switching sub-circuit is responsible for discharging voltage when turning off. Together, they realize active control of the controlled end of the switching device, which is beneficial to improving the control accuracy and safety of the pre-charging process.

[0022] In some embodiments, the third switching sub-circuit includes: a third optocoupler switch, a first terminal of which is coupled to the controlled terminal of a switching device, a second terminal of which is coupled to a first voltage reference terminal, a third terminal of which is coupled to a power supply, and a fourth terminal of which is used to input a third control signal. The third optocoupler switch is configured to: when the first terminal of the second switching sub-circuit is disconnected from the second terminal of the second switching sub-circuit, conduct the third terminal and the fourth terminal of the third optocoupler switch based on the third control signal, thereby connecting the first terminal and the second terminal of the third optocoupler switch.

[0023] In this embodiment, the specific structure of the third switch sub-circuit is defined. Based on the third control signal, the third and fourth terminals of the third optocoupler switch are turned on, thereby connecting the first and second terminals. Utilizing the isolation characteristics of the optocoupler switch, the turn-off control signal is isolated from the high-voltage side, thus maintaining complete electrical isolation of the entire pre-charge device control terminal and improving system safety and integrity. When the third optocoupler switch is turned on, its output side forms a low-impedance path from the controlled terminal of the switching device to the first voltage reference terminal. Since the on-resistance of the optocoupler switch can be kept small, the charge at the controlled terminal can be quickly discharged. The third switch sub-circuit provided in this application achieves turn-off control through the optocoupler switch, continuing the advantages of electrical isolation while realizing remote and safe control of forced turn-off of the switching device.

[0024] In some embodiments, the pre-charge device further includes a control circuit coupled to the switching circuit and configured to control the single-on time of a first terminal and a second terminal of the switching circuit based on parameters of the energy storage circuit and the pre-charge capacitor.

[0025] This application determines the resistance value of the equivalent resistor, the inductance of the energy storage circuit, and the capacitance value of the pre-charge capacitor in the pre-charge circuit (i.e., the charging circuit formed by the power battery through the energy storage circuit, the switching circuit, and the pre-charge capacitor). Based on the resistance value of the equivalent resistor, the inductance of the energy storage circuit, and the capacitance value of the pre-charge capacitor, it calculates the time constant required for the energy storage circuit to rise from the initial current to the saturation current. This allows for the setting of the single-time conduction duration (or initial conduction duration) of the switching circuit. If the single-time conduction duration of the switching circuit is too long, the current flowing through the energy storage circuit may become excessive, exceeding the saturation current of the energy storage circuit. The energy storage circuit will then lose its ability to suppress current surges, causing the current to spike exponentially, forming a huge peak current, which in turn affects the entire pre-charge device. Conversely, if the single-time conduction duration of the switching circuit is too short, frequent switching between on and off states will result in a slower charging rate for the pre-charge capacitor, prolonging the pre-charge duration. In the embodiments of this application, the control circuit enables fine-grained management of the pre-charge process, improving the reliability of pre-charge.

[0026] Secondly, embodiments of this application provide a control method for a pre-charging device, applied to the pre-charging device as described in the first aspect. The method includes: controlling a step-down circuit to reduce the first voltage input to the power battery to a second voltage, applying the second voltage to a switching circuit to turn on the switching circuit, so that the power battery charges the pre-charging capacitor through an energy storage circuit.

[0027] In this embodiment, the control method for the pre-charge device first performs a voltage reduction step, actively converting the high voltage to a low voltage suitable for the control terminal of the switching device using a voltage reduction circuit. This avoids potential gate overvoltage failure or drive circuit damage that could result from directly using a high-voltage control signal. A second voltage is applied to the switching circuit to turn it on, allowing precise control of the timing of the pre-charge circuit connection. The pre-charge capacitor is charged through an energy storage circuit. The inductive or impedance characteristics of the energy storage element limit the rise rate and peak value of the charging current, effectively suppressing the surge current generated during the initial charging of the pre-charge capacitor and protecting the power battery, the pre-charge capacitor, and subsequent load circuits. The control method for the pre-charge device provided in this application is simple, requiring no complex current sampling feedback. Soft-start pre-charge can be achieved solely through voltage transformation and switching control, reducing the complexity of the control algorithm and the dependence on sensors.

[0028] In some embodiments, the control method for the pre-charging device further includes: determining the single-on time of the first terminal and the second terminal of the switching circuit based on the parameters of the energy storage circuit and the pre-charging capacitor.

[0029] In some embodiments, the switching circuit includes: a switching device and a second switching sub-circuit, a first terminal of the switching device being coupled to the energy storage circuit, and a second terminal of the switching device being coupled to the pre-charge capacitor. A second voltage is applied to the switching circuit to turn it on, allowing the power battery to charge the pre-charge capacitor through the energy storage circuit. This includes: The second switch sub-circuit is turned on, and the second voltage is applied to the controlled terminal of the switch device to turn on the switch device, so that the power battery can charge the pre-charge capacitor through the energy storage circuit.

[0030] Thirdly, embodiments of this application provide a battery pack, which includes a power battery and a pre-charging device as described in the first aspect.

[0031] Fourthly, embodiments of this application provide a vehicle, including: a pre-charging device as described in the first aspect, or a battery pack as described in the third aspect. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application will be described below.

[0033] Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a battery pack disclosed in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a pre-charging device disclosed in an embodiment of this application. Figure 1 ; Figure 4 This is a schematic diagram of the structure of a pre-charging device disclosed in an embodiment of this application. Figure 2 ; Figure 5 This is a schematic diagram of the structure of a pre-charging device disclosed in an embodiment of this application. Figure 3 ; Figure 6 This is a schematic diagram of the structure of a pre-charging device disclosed in an embodiment of this application. Figure 4 .

[0034] Explanation of reference numerals in the attached figures: 1-Vehicle; 1000-battery pack; 100 - Power battery; 200 - Pre-charge device; 300 - High voltage load; K - Relay; 201 - Switching circuit; 202 - Buck circuit; 203 - Control circuit; 2011 - Power supply; 2012 - Second switch sub-circuit; 2013 - Third switch sub-circuit.

[0035] 2021 - First switching sub-circuit; 2022 - Buck converter sub-circuit; 2023 - Power amplifier sub-circuit; R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; R6 - Sixth resistor; R7 - Seventh resistor; R8 - Eighth resistor; D1 - Freewheeling diode; D2 - Zener diode; D3 - Reverse protection diode; L-energy storage circuit; C - Pre-charge capacitor; C1 - First capacitor; C2 - Second capacitor; Q1 - Switching device; Q2 - Transistor; U1 - First optocoupler switch; U2 - Second optocoupler switch; U3 - Third optocoupler switch. Detailed Implementation

[0036] The terms “first,” “second,” etc., are used for descriptive purposes only and have no sequential or technical meaning, nor should they be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0037] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "coupled" and "connected" refer to the flow of current or signal from one conductor to another. A connection between A and B means that current or signal can flow from A to B and vice versa. A connection between A and B includes direct electrical connection and indirect electrical connection. A direct electrical connection between A and B means that A and B are electrically connected through physical contact. An indirect electrical connection between A and B means that A and B are electrically connected through C, where C can be at least one wire or device.

[0038] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0039] The embodiments of this application are described below with reference to the accompanying drawings.

[0040] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in an embodiment of this application. The vehicle can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle.

[0041] Vehicle 1 includes a battery pack 1000 and a high-voltage load 2000.

[0042] Among them, the battery pack 1000 is the core power supply module for the vehicle's high-voltage electrical energy, providing stable high-voltage DC power to the high-voltage load 2000.

[0043] High-voltage load 2000 refers to high-voltage electrical components in vehicle 1, such as motor controllers, on-board chargers, high-voltage DC-DC converters, and high-voltage positive temperature coefficient (PTC) heaters.

[0044] In some embodiments, such as Figure 2As shown, the battery pack 1000 includes a power battery 100 and a pre-charge device 200.

[0045] Before powering the high-voltage load 2000, the power battery 100 needs to charge the pre-charge capacitor coupled to the high-voltage load 2000 through the pre-charge device 200. During the entire pre-charge process, the pre-charge device is mainly used for current limiting to prevent the pre-charge capacitor from being damaged by a large current.

[0046] In some embodiments, as semiconductor technology matures, power devices (also known as switching devices, such as insulated gate bipolar transistors (IGBTs), silicon carbide (SICs), and metal-oxide-semiconductor field-effect transistors (MOSFETs)) are gradually adopted to replace precharge relays and precharge resistors, thereby reducing the size and cost of precharge devices.

[0047] However, low voltage (such as 15V or 20V) is usually required to drive the power devices to turn on or off, thereby achieving pre-charging of the pre-charge capacitor. Since the power battery 100 outputs a high voltage (such as 400V or 800V), an isolation circuit needs to be set between the power devices and the power battery 100 to achieve isolation between the high-voltage side and the low-voltage side.

[0048] As can be seen from the above, in this embodiment, not only is it necessary to introduce an isolation circuit, but also to set up a low-voltage power supply to drive the power devices. Therefore, there is a technical problem of high hardware cost.

[0049] Based on this, embodiments of this application provide a pre-charging device for use in vehicles.

[0050] In some embodiments, the high-voltage load 2000 is equipped with a large-capacity pre-charge capacitor. In order to more intuitively introduce the pre-charge device 200 provided in this application, the following embodiments are all described with the pre-charge device 200 including the pre-charge capacitor as an example.

[0051] like Figure 3 As shown, the pre-charge device 200 includes: an energy storage circuit L, a switching circuit 201, a step-down circuit 202, and a pre-charge capacitor C.

[0052] In this circuit, the first terminal of the energy storage circuit L is coupled to the first terminal of the power battery 100. The first terminal of the switching circuit 201 is coupled to the second terminal of the energy storage circuit L. The first terminal of the step-down circuit 202 is coupled to the first terminal of the power battery 100, and the second terminal of the step-down circuit 202 is coupled to the switching circuit 201. The first terminal of the pre-charge capacitor C is coupled to the second terminal of the switching circuit 201, and the second terminal of the pre-charge capacitor C is coupled to the second terminal of the power battery 100. The third terminal of the step-down circuit 202 and the first terminal of the pre-charge capacitor C are both coupled to the first voltage reference terminal GND1.

[0053] In this embodiment, the energy storage circuit L is connected in series between the power battery 100 and the pre-charge capacitor C. The energy storage circuit L absorbs the current spikes or voltage fluctuations that may occur during charging, thereby mitigating the direct impact on the pre-charge capacitor C and extending the service life of the pre-charge capacitor C and subsequent loads.

[0054] The step-down circuit 202 is used to reduce the first voltage input to the first terminal of the step-down circuit 202 to a second voltage, and output the second voltage through the second terminal of the step-down circuit 202. The step-down circuit 202 can draw power from the power battery 100 to supply power to the switching circuit 201.

[0055] In addition, the step-down circuit 202 can isolate the high voltage on the power battery 100 side from the low voltage on the switching circuit 201 side.

[0056] The switching circuit 201 is used to connect the first terminal of the switching circuit 201 and the second terminal of the switching circuit 201 based on the second voltage, so that the power battery 100 charges the pre-charge capacitor C through the energy storage circuit L.

[0057] In this way, the stable second voltage provided by the step-down circuit 202 can be used as the control signal source for the switching circuit 201 to conduct, so that the switching circuit 201 can complete the conduction action under a certain voltage condition, thereby ensuring that the pre-charge capacitor C obtains the controlled charging current from the energy storage circuit L, and realizing the smooth pre-charging of the pre-charge capacitor C.

[0058] In this embodiment, by setting up a step-down circuit 202, not only is it unnecessary to introduce an isolation circuit or set up a low-voltage power supply, but it is also possible to power and control the switching circuit 201, thereby reducing the hardware cost of the pre-charging device.

[0059] In some embodiments, such as Figure 3 As shown, the pre-charge device 200 further includes a freewheeling diode D1, the cathode of which is coupled to the first terminal of the energy storage circuit L, and the anode of which is coupled to the second terminal of the energy storage circuit L. The freewheeling diode D1 is conductive from the anode to the cathode.

[0060] During the pre-charging process of the pre-charge capacitor C, when the first and second terminals of the switching circuit 201 are connected, the power battery 100 charges the pre-charge capacitor C through the energy storage circuit L. When the first and second terminals of the switching circuit 201 are disconnected, the energy storage circuit L and the freewheeling diode D1 form a freewheeling circuit. The two ends of the energy storage circuit L are directly short-circuited by a wire, and the electrical energy on the energy storage circuit L is discharged through the freewheeling diode D1 to prevent the voltage across the energy storage circuit L from rising rapidly and damaging the switching circuit 201.

[0061] The battery pack also includes a relay K, which is coupled between the first terminal of the power battery 100 and the first terminal of the pre-charge capacitor C.

[0062] The pre-charging device 200 also includes a control circuit 203. During pre-charging, the control circuit 203 controls the relay K to open, and the power battery 100 charges the pre-charging capacitor C through the energy storage circuit L in the pre-charging device 200. The control circuit 203 detects the voltage difference across the relay K. When the voltage between the first and second terminals of the relay K is less than a voltage threshold, it determines that pre-charging is complete. The control circuit 203 then controls the relay K to open, and the power battery 100 supplies power to the pre-charging capacitor C, i.e., the high-voltage load downstream of the pre-charging capacitor C, through the relay K.

[0063] In the pre-charge device 200, the control circuit 203 is coupled to the switching circuit 201. Figure 3 The connection relationship of the control circuit 203 is not shown in the figure.

[0064] The control circuit 203 is used to control the single-time conduction time of the first terminal and the second terminal of the switching circuit 201 according to the parameters of the energy storage circuit L and the pre-charge capacitor C.

[0065] In this embodiment of the application, the control circuit 203 is used to control the single conduction time of the first terminal and the second terminal of the switching circuit 201 according to the parameters of the energy storage circuit L and the pre-charge capacitor C.

[0066] This application determines the resistance value of the equivalent resistor, the inductance of the energy storage circuit L, and the capacitance value of the pre-charge capacitor C in the pre-charge circuit (i.e., the charging circuit formed by the power battery 100 through the energy storage circuit L, the switching circuit 201, and the pre-charge capacitor C). Based on the resistance value of the equivalent resistor, the inductance of the energy storage circuit L, and the capacitance value of the pre-charge capacitor C, the application calculates the time constant required for the energy storage circuit L to rise from the initial current to the saturation current. In this way, the single conduction duration (or the initial conduction duration) of the switching circuit 201 can be set.

[0067] If the single on-time of the switching circuit 201 is too long, the current flowing through the energy storage circuit L may become excessive, exceeding the saturation current of the energy storage circuit L. This would cause the energy storage circuit L to lose its ability to suppress sudden current changes, resulting in an exponential surge in current and forming a huge peak current, which would then affect the entire pre-charging device 200. Conversely, if the single on-time of the switching circuit 201 is too short, the frequent switching between on and off states would result in a slower charging rate for the pre-charging capacitor C, thus prolonging the pre-charging time.

[0068] Specifically, the current flowing through the energy storage circuit L satisfies the following formula: I(t) = U / (W) d L)×e -ɑ sin(W) d t); Where U represents the initial voltage of the pre-charge capacitor C, L represents the inductance of the energy storage circuit L, Wd represents the damped oscillation angular frequency of the pre-charge circuit, and α represents the attenuation coefficient.

[0069] Damped oscillation frequency W d Satisfy the following formula: W d =(W0 2 -ɑ 2 ) 1 / 2 ; Where W0 represents the undamped resonant angular frequency, and α represents the attenuation coefficient.

[0070] The undamped resonant angular frequency W0 satisfies the following formula: W0 = 1 / (LC) 1 / 2 ; Where L represents the inductance of the energy storage circuit L, and C represents the capacitance of the pre-charge capacitor C.

[0071] The attenuation coefficient α satisfies the following formula: a = R / (2L); Where R represents the resistance value of the equivalent resistance of the pre-charge circuit, and L represents the inductance of the energy storage circuit L.

[0072] In this embodiment of the application, the control circuit 203 can determine the single conduction time of the first and second terminals of the control switch circuit 201 based on the saturation current of the energy storage circuit L, and then calculate the duty cycle of the pulse width modulation (PWM) signal that controls the first and second terminals of the control switch circuit 201 to conduct.

[0073] In practical applications, as the voltage across the pre-charge capacitor C gradually increases, the voltage difference across the energy storage circuit L continuously decreases, the rate of increase of the current flowing through the energy storage circuit L slows down, and a longer conduction time is required for the current flowing through the energy storage circuit L to reach the saturation current.

[0074] Therefore, in some embodiments, the control circuit 203 may only calculate the initial conduction duration of the first terminal and the second terminal of the switching circuit 201. In subsequent control, the switching circuit 201 may be controlled to conduct according to the PWM signal corresponding to the conduction duration.

[0075] In some other embodiments, after calculating the initial conduction time between the first terminal and the second terminal of the switching circuit 201, the control circuit 203 can gradually increase the conduction time between the first terminal and the second terminal of the switching circuit 201 and shorten the pre-charging time during subsequent control processes, as the voltage difference between the power battery 100 and the pre-charging capacitor C decreases.

[0076] In some other embodiments, the control circuit 203 can continuously or periodically calculate the conduction duration of the second terminal of the switch circuit 201, and based on this, control the first terminal of the switch circuit 201 to conduct with the second terminal of the switch circuit 201. This enables fine-grained management of the pre-charging process and improves the reliability of pre-charging.

[0077] In some embodiments, such as Figure 4 As shown, the step-down circuit 202 includes: a first switching sub-circuit 2021, a step-down sub-circuit 2022, and a power amplifier sub-circuit 2023. The switching circuit 201 includes: a switching device Q1 and a second switching sub-circuit 2012.

[0078] The first terminal of the first switch sub-circuit 2021 is used to couple to the first terminal of the power battery 100.

[0079] The first terminal of the step-down sub-circuit 2022 is coupled to the second terminal of the first switching sub-circuit 2021, the second terminal of the step-down sub-circuit 2022 is coupled to the switching circuit 201, and the third terminal of the step-down sub-circuit 2022 is coupled to the first terminal of the pre-charge capacitor C and the first voltage reference terminal GND1.

[0080] The first terminal of the power amplifier sub-circuit 2023 is coupled to the first terminal of the buck sub-circuit 2022, and the second terminal of the power amplifier sub-circuit 2023 is coupled to the second terminal of the buck sub-circuit 2022.

[0081] When the first switch sub-circuit 2021 precharges the pre-charge capacitor C, it connects the first terminal of the first switch sub-circuit 2021 to the second terminal of the first switch sub-circuit 2021.

[0082] The first switch sub-circuit 2021 is used to turn on its first and second terminals when precharging the precharge capacitor C. It can selectively connect the power energy of the power battery 100 to the buck sub-circuit 2022 during the precharging stage, and disconnect it during the non-precharging stage to cut off the power consumption path, thereby reducing the static loss of the entire buck circuit 202 in the standby state.

[0083] The step-down sub-circuit 2022 is used to reduce the first voltage to the second voltage. The stepped-down second voltage can drive the switching circuit 201. Power is supplied to the pre-charge capacitor C through the second terminal of the step-down sub-circuit 2022, which can reduce the need for an additional reference voltage source.

[0084] The power amplifier sub-circuit 2023 amplifies the current or enhances the driving capability of the stepped-down signal, providing a second voltage with sufficient driving capability for the switching circuit 201, and avoiding insufficient conduction of the switching circuit 201 due to excessively high output impedance of the step-down sub-circuit 2022.

[0085] The first terminal of the switching device Q1 is coupled to the second terminal of the energy storage circuit L, and the second terminal of the switching device Q1 is coupled to the pre-charge capacitor C.

[0086] The first terminal of the second switch sub-circuit 2012 is coupled to the second terminal of the step-down circuit 202, and the second terminal of the second switch sub-circuit 2012 is coupled to the controlled terminal of the switching device Q1.

[0087] When precharging the pre-charge capacitor C, the first terminal of the second switch sub-circuit 2012 and the second terminal of the second switch sub-circuit 2012 are connected.

[0088] In this embodiment, the switching device Q1 is coupled between the energy storage circuit L and the pre-charge capacitor C. A second switching sub-circuit 2012 serves as an intermediate part, selectively applying the second voltage output from the step-down circuit 202 to the controlled terminal of the switching device Q1. This enables indirect control of the conduction state of the switching device Q1. By switching the second switching sub-circuit 2012 on and off, the second voltage can be quickly transmitted to the controlled terminal of the switching device Q1. Simultaneously, the second switching sub-circuit 2012 itself possesses a certain driving capability, which helps improve the switching speed of the switching device Q1. Furthermore, separating the switching device Q1 and the second switching sub-circuit 2012 allows for the separation of the power path and control path in the layout, reducing interference from high current to the control signal.

[0089] In some embodiments, such as Figure 5 As shown, the switching circuit 201 also includes a third switching sub-circuit 2013.

[0090] The first terminal of the third switch sub-circuit 2013 is coupled to the controlled terminal of the switching device Q1, and the second terminal of the third switch sub-circuit 2013 is coupled to the first voltage reference terminal GND1.

[0091] When the first terminal of the second switch sub-circuit 2012 is disconnected from the second terminal of the second switch sub-circuit 2012, the first terminal of the third switch sub-circuit 2013 is connected to the second terminal of the third switch sub-circuit 2013.

[0092] When the first and second terminals of the second switching sub-circuit 2012 are disconnected, the first and second terminals of the third switching sub-circuit 2013 are connected. This provides a low-impedance discharge path for the controlled terminal of switching device Q1 when pre-charging is complete or when it is necessary to turn off switching device Q1. This allows the charge accumulated at the controlled terminal of switching device Q1 (i.e., the charge stored in the gate capacitor of switching device Q1) to be quickly discharged to the first voltage reference terminal GND1. This ensures that switching device Q1 is turned off quickly and reliably, preventing mis-turn-on due to a floating controlled terminal or residual charge. Without this discharge path, when the second switching sub-circuit 2012 is disconnected, the controlled terminal of switching device Q1 may be in a high-impedance state, making it highly susceptible to external electric field interference or leakage current, resulting in uncertain voltage and potentially causing unexpected turn-on of switching device Q1, which could lead to overcharging of the pre-charge capacitor or system failure. The active pull-down of the third switching sub-circuit 2013 can force the controlled terminal potential down to the first voltage reference terminal potential, thereby forcibly turning off switching device Q1. Based on the switching circuit 201 provided in this application, the third switching sub-circuit 2013 and the second switching sub-circuit 2012 form a complementary drive. The second switching sub-circuit 2012 is responsible for applying voltage when conducting, and the third switching sub-circuit 2013 is responsible for discharging voltage when turning off. Together, they realize the active control of the controlled terminal of the switching device Q1, which is beneficial to improving the control accuracy and safety of the pre-charging process.

[0093] In some embodiments, a schematic diagram of the pre-charge device 200 is shown below. Figure 6 As shown.

[0094] The step-down sub-circuit 2022 includes: a first resistor R1, a Zener diode D2, a first capacitor C1, and a second capacitor C2.

[0095] The first end of the first resistor R1 is coupled to the second end of the first switch sub-circuit 2021.

[0096] The first terminal of Zener diode D2 is coupled to the second terminal of the first resistor R1, and the second terminal of Zener diode D2 is coupled to the first voltage reference terminal GND.

[0097] The first terminal of the first capacitor C1 is coupled to the first terminal of the Zener diode D2, and the second terminal of the first capacitor C1 is coupled to the second terminal of the Zener diode D2.

[0098] The first terminal of the second capacitor C2 is coupled to the second terminal of the power amplifier sub-circuit 2023, and the second terminal of the second capacitor C2 is coupled to the first voltage reference terminal GND1.

[0099] The voltage between the first and second terminals of the Zener diode D2 is the second voltage.

[0100] The first resistor R1 limits the input current to prevent overcurrent from damaging the Zener diode D2.

[0101] Zener diode D2 has reverse breakdown characteristics, which can generate a stable second voltage between the first and second terminals, thereby obtaining a reference voltage that is not affected by voltage fluctuations of the power battery 100, and providing a precise control level for the subsequent switching circuit 201.

[0102] The first capacitor C1 is connected in parallel across the Zener diode D2 to filter out high-frequency noise or transient spikes that may be generated when the Zener diode D2 is working, thereby making the second voltage smoother and improving the stability of the control signal of the switching circuit 201.

[0103] The second capacitor C2 performs further filtering on the output side of the power amplifier sub-circuit 2023, further suppressing the ripple that may be introduced after amplification by the power amplifier, thereby providing a clean drive voltage for the switching circuit 201 and avoiding malfunction of the switch due to voltage ripple.

[0104] Based on the step-down sub-circuit 2022 provided in this application, stable step-down and filtering effects can be achieved with lower cost and fewer components, which is beneficial to improving the anti-interference capability of the pre-charge device 200 in complex electromagnetic environments.

[0105] In this embodiment of the application, the nominal value of the Zener diode D2 can be selected as 18V, and the cutoff voltage of the Zener diode D2 can be set to 0.7V.

[0106] Combination Figure 6 As shown, in the step-down sub-circuit 2022, the voltage at the second terminal of Zener diode D2 is the reference voltage Upre, and the voltage at the first terminal of Zener diode D2 is Upre + 18V. The voltage at the second terminal of switching device Q1 is the reference voltage Upre. Ideally, the voltage at the first terminal of Zener diode D2 passes through the power amplifier sub-circuit 2023 and the second switching sub-circuit 2012 without loss. When the second switching sub-circuit 2012 is turned on, the voltage at the controlled terminal of switching device Q1 is Upre + 18V, and the voltage difference between the controlled terminal and the second terminal of switching device Q1 is 18V, which is sufficient to drive switching device Q1 to conduct.

[0107] In some embodiments, it should be noted that the energy stored in the buck sub-circuit 2022 should meet the drive energy requirements of the switching device Q1 during the pre-charging process, and the target energy satisfies the following formula: E = Eq1 on / PWM duty cycle × precharge duration; Where Eq1 is the energy required for the switching device Q1 to turn on once, and the PWM duty cycle is the duty cycle of the drive signal that drives the switching device Q1.

[0108] The power amplifier sub-circuit 2023 includes: a second resistor R2 and a transistor Q2.

[0109] The first end of the second resistor R2 is coupled to the second end of the first switch sub-circuit 2021.

[0110] The first terminal of transistor Q2 is coupled to the first terminal of Zener diode D2, the second terminal of transistor Q2 is coupled to the second terminal of second resistor R2, the third terminal of transistor Q2 is coupled to the first terminal of second capacitor C2, and the first terminal of switching circuit 201.

[0111] In this embodiment, transistor Q2 is a PNP transistor. Based on the circuit structure provided in this application, the voltage at the second terminal (collector) of transistor Q2 is less than the voltage at the first terminal (base), and the voltage at the first terminal (base) is less than the voltage at the third terminal (emitter). Transistor Q2 is in the amplification region. Utilizing the current amplification characteristic of transistor Q2, the stable voltage output from the Zener diode is used as the base bias, allowing transistor Q2 to operate in the amplification or saturation region. This converts the high-impedance, low-current second voltage generated by the step-down circuit 2022 into a low-impedance, high-current driving capability, meeting the driving current requirements of the switching circuit 201. The second resistor R2 provides a suitable operating point current for transistor Q2, while limiting the current flowing through transistor Q2 to prevent transistor Q2 from being damaged due to overcurrent, thereby improving the long-term operational reliability of the power amplifier sub-circuit 2023.

[0112] The power amplifier sub-circuit 2023 provided in this application can realize the conversion from a high impedance voltage source to a low impedance voltage source through a simple discrete component power amplifier structure without the need for integrated operational amplifiers or dedicated driver chips. This helps to reduce device cost and complexity, while maintaining reliable driving of the switching circuit 201.

[0113] The first switch sub-circuit 2021 includes: an anti-reverse diode D3 and a first optocoupler switch U1.

[0114] The first terminal of the anti-reverse diode D3 is coupled to the first terminal of the power battery 100.

[0115] The first terminal of the first optocoupler switch U1 is coupled to the second terminal of the anti-reverse diode D3, the second terminal of the first optocoupler switch U1 is coupled to the first terminal of the step-down sub-circuit 2022, the third terminal of the first optocoupler switch U1 is used to input the first control signal, and the fourth terminal of the first optocoupler switch U1 is coupled to the second voltage reference terminal GND2.

[0116] Based on the working principle of an optocoupler switch, the optocoupler switch includes a light-emitting diode (LED) and a phototransistor. The first terminal of the phototransistor serves as the first terminal of the first optocoupler switch U1, and the second terminal of the phototransistor serves as the second terminal of the first optocoupler switch U1. The anode of the LED serves as the third terminal of the first optocoupler switch U1, and the cathode of the LED serves as the fourth terminal of the first optocoupler switch U1.

[0117] If the voltage at the anode of the LED is greater than the voltage at the cathode, and the voltage between the anode and cathode is greater than its forward voltage, the LED will conduct and emit light, and at the same time, the phototransistor will conduct.

[0118] Therefore, when the third terminal of the first optocoupler U1 is connected to the fourth terminal of the first optocoupler U1, the first terminal of the first optocoupler U1 is connected to the second terminal of the first optocoupler U1.

[0119] In this embodiment of the application, when precharging the pre-charge capacitor C, the third terminal and the fourth terminal of the first optocoupler switch U1 are turned on based on the first control signal, so that the first terminal and the second terminal of the first optocoupler switch U1 are turned on.

[0120] In some embodiments, the first switch sub-circuit 2021 further includes a third resistor R3, which is coupled between the control circuit 203 and the third terminal of the first optocoupler switch U1.

[0121] In conjunction with the above embodiments, when precharging the pre-charge capacitor C, the control circuit 203 sends a first control signal to the third terminal of the first optocoupler switch U1, so that the third terminal of the first optocoupler switch U1 is connected to the fourth terminal of the first optocoupler switch U1, thereby making the first terminal of the first optocoupler switch U1 connected to the second terminal of the first optocoupler switch U1.

[0122] In this embodiment, the unidirectional conductivity of the anti-reverse diode is utilized to block the current flowing in reverse from the step-down sub-circuit 2022 or the subsequent circuit to the power battery 100, preventing the energy from the energy storage circuit L or the pre-charge capacitor C from flowing back into the battery when pre-charging is completed or the system loses power, thus protecting the power battery 100 from reverse voltage surges. During pre-charging of the pre-charge capacitor C, the electrical isolation characteristics of the optocoupler switch are used to completely isolate the low-voltage control signal (i.e., the first control signal) from the high-voltage power battery 100 circuit, thereby preventing high-voltage side interference or faults from propagating to the low-voltage control circuit through the control circuit, improving system safety and anti-interference capabilities.

[0123] In this embodiment, the control circuit 203 controls the first optocoupler switch U1 to turn on, serving as an enable control signal for the pre-charging device 200 to activate. This prevents the power battery 100 from continuously charging the pre-charging capacitor C during high-voltage power-off, thus avoiding energy waste and safety risks. Simultaneously, it avoids the risk of damage to devices such as the Zener diode D2 caused by transient interference such as surges entering the high-voltage bus during high-voltage power-on.

[0124] In some embodiments, the switching circuit 201 further includes a fourth resistor R4, which is coupled between the controlled terminal of the switching device Q1 and the second terminal of the switching device Q1.

[0125] The fourth resistor R4 serves as the gate pull-down resistor for the switching device Q1, preventing the controlled terminal (also known as the gate) of the switching device Q1 from being floating and ensuring the reliable turn-off of the switching device Q1. At the same time, the fourth resistor R4 also provides a discharge circuit for the capacitor at the controlled terminal of the switching device Q1, accelerating the turn-off of the switching device Q1.

[0126] The second switch sub-circuit 2012 includes: a second optocoupler switch U2.

[0127] The first terminal of the second optocoupler switch U2 is coupled to the second terminal of the step-down circuit 202, the second terminal of the second optocoupler switch U2 is coupled to the controlled terminal of the switching device Q1, the third terminal of the second optocoupler switch U2 is used to input the second control signal, and the fourth terminal of the second optocoupler switch U2 is coupled to the second voltage reference terminal GND2.

[0128] Based on the working principle of an optocoupler switch, the optocoupler switch includes a light-emitting diode (LED) and a phototransistor. The first terminal of the phototransistor serves as the first terminal of the second optocoupler switch U2, and the second terminal of the phototransistor serves as the second terminal of the second optocoupler switch U2. The anode of the LED serves as the third terminal of the second optocoupler switch U2, and the cathode of the LED serves as the fourth terminal of the second optocoupler switch U2.

[0129] If the voltage at the anode of the LED is greater than the voltage at the cathode, and the voltage between the anode and cathode is greater than its forward voltage, the LED will conduct and emit light, and at the same time, the phototransistor will conduct.

[0130] Therefore, when the third terminal of the second optocoupler U2 is connected to the fourth terminal of the second optocoupler U2, the first terminal of the second optocoupler U2 is connected to the second terminal of the second optocoupler U2.

[0131] In this embodiment of the application, when precharging the pre-charge capacitor C, the third terminal of the second optocoupler switch U2 is connected to the fourth terminal of the second optocoupler switch U2 based on the second control signal, so that the first terminal of the second optocoupler switch U2 is connected to the second terminal of the second optocoupler switch U2.

[0132] In some embodiments, the first switch sub-circuit 2021 further includes a fifth resistor R5, which is coupled between the control circuit 203 and the third terminal of the second optocoupler switch U2.

[0133] In conjunction with the above embodiments, when precharging the pre-charge capacitor C, the control circuit 203 sends a second control signal to the third terminal of the second optocoupler switch U2, so that the third terminal of the second optocoupler switch U2 is connected to the fourth terminal of the second optocoupler switch U2, thereby connecting the first terminal of the second optocoupler switch U2 to the second terminal of the second optocoupler switch U2.

[0134] In this embodiment, during pre-charging, the third and fourth terminals of the second optocoupler switch U2 are connected based on the second control signal, thereby connecting the first and second terminals of the second optocoupler switch U2. Utilizing the electrical isolation characteristics of the optocoupler switch, the control signal (i.e., the second control signal) is isolated from the high-voltage side where the controlled terminal of the switching device Q1 is located. This prevents high voltage from entering the low-voltage control circuit when the switching device Q1 experiences a short circuit or breakdown fault, thus protecting the upstream controller.

[0135] Meanwhile, the output side of the optocoupler switch exhibits a low on-resistance when it is turned on, which can transmit the second voltage output by the buck circuit 202 to the controlled terminal of the switching device Q1 with almost no attenuation, ensuring that the switching device Q1 obtains sufficient gate voltage to be fully turned on, thereby reducing the conduction loss of the switching device Q1.

[0136] The third switch sub-circuit 2013 includes: the third optocoupler switch U3.

[0137] The first terminal of the third optocoupler switch U3 is coupled to the controlled terminal of the switching device Q1, the second terminal of the third optocoupler switch U3 is coupled to the first voltage reference terminal GND1, the third terminal of the third optocoupler switch U3 is coupled to the power supply 2011, and the fourth terminal of the third optocoupler switch U3 is used to input the third control signal.

[0138] Based on the working principle of an optocoupler switch, the optocoupler switch includes a light-emitting diode (LED) and a phototransistor. The first terminal of the phototransistor serves as the first terminal of the third optocoupler switch U3, and the second terminal of the phototransistor serves as the second terminal of the third optocoupler switch U3. The anode of the LED serves as the third terminal of the third optocoupler switch U3, and the cathode of the LED serves as the fourth terminal of the third optocoupler switch U3.

[0139] If the voltage at the anode of the LED is greater than the voltage at the cathode, and the voltage between the anode and cathode is greater than its forward voltage, the LED will conduct and emit light, and at the same time, the phototransistor will conduct.

[0140] Therefore, when the third terminal of the third optocoupler U3 is connected to the fourth terminal of the third optocoupler U3, the first terminal of the third optocoupler U3 is connected to the second terminal of the third optocoupler U3.

[0141] In this embodiment of the application, when the first terminal of the second switch sub-circuit 2012 is disconnected from the second terminal of the second switch sub-circuit 2012, the third terminal of the third optocoupler switch U3 and the fourth terminal of the third optocoupler switch U3 are turned on based on the third control signal, so that the first terminal of the third optocoupler switch U3 and the second terminal of the third optocoupler switch U3 are turned on.

[0142] In some embodiments, the first switch sub-circuit 2021 further includes a sixth resistor R6, which is coupled to the controlled terminal of the switching device Q1 and the first terminal of the third optocoupler switch U3.

[0143] In conjunction with the above embodiments, when precharging the pre-charge capacitor C, the control circuit 203 sends a third control signal to the third terminal of the third optocoupler switch U3, so that the third terminal of the third optocoupler switch U3 is connected to the fourth terminal of the third optocoupler switch U3, thereby connecting the first terminal of the third optocoupler switch U3 to the second terminal of the third optocoupler switch U3.

[0144] In this embodiment, when the first terminal of the second switch sub-circuit 2012 is disconnected from the second terminal of the second switch sub-circuit 2012, the third terminal and the fourth terminal of the third optocoupler switch U3 are turned on based on the third control signal, so that the first terminal and the second terminal of the third optocoupler switch U3 are turned on. Utilizing the isolation characteristics of the optocoupler switch, the turn-off control signal (i.e., the third control signal) is isolated from the high-voltage side, thereby maintaining complete electrical isolation of the entire pre-charge device 200 control terminal and improving the system's safety and integrity. When the third optocoupler switch U3 is turned on, a low-impedance path is formed on its output side from the controlled terminal of the switching device Q1 to the first voltage reference terminal. Since the on-resistance of the optocoupler switch can be made relatively small, the charge at the controlled terminal can be quickly discharged.

[0145] In some embodiments, the switching circuit 201 further includes a seventh resistor R7 and an eighth resistor R8. The seventh resistor R7 is coupled between the control circuit 203 and the fourth terminal of the third optocoupler switch U3. The eighth resistor R8 is coupled between the second terminal of the second optocoupler switch U2 and the controlled terminal of the switching device Q1.

[0146] Combination Figure 6 The embodiment shown describes the operating logic of the pre-charge device 200.

[0147] The power battery 100, energy storage circuit L, switching device Q1, and pre-charge capacitor C constitute the pre-charge circuit.

[0148] During the pre-charge phase, the control circuit 203 sends a first control signal (high-level signal) to the third terminal of the first optocoupler switch U1, which turns on the first switch sub-circuit 2021, thereby putting the step-down circuit 202 into operation.

[0149] During the first time period, the control circuit 203 sends a second control signal (high-level signal) to the third terminal of the second optocoupler switch U2, causing the second switch sub-circuit 2012 to be turned on. At the same time, it sends a second control signal (high-level signal) to the third terminal of the third optocoupler switch U3, causing the third switch sub-circuit 2013 to be turned off.

[0150] The step-down circuit 202 supplies power to the controlled terminal of the switching device Q1 through the second switching sub-circuit 2012, causing the switching device Q1 to conduct. At this time, the power battery 100 charges the pre-charge capacitor C through the energy storage circuit L and the switching device Q1.

[0151] When the power battery 100 continuously charges the pre-charge capacitor C, the current flowing through the energy storage circuit L will continuously increase due to the resistance of the energy storage circuit L to current changes.

[0152] During the second time period, the control circuit 203 sends a third control signal (low-level signal) to the third terminal of the second optocoupler switch U2, causing the second switch sub-circuit 2012 to disconnect. At the same time, it sends a third control signal (low-level signal) to the third terminal of the third optocoupler switch U3, causing the third switch sub-circuit 2013 to turn on.

[0153] At this time, the second switch sub-circuit 2012 is disconnected, and the level received by the controlled terminal of switch device Q1 causes switch device Q1 to disconnect. The controlled terminal of switch device Q1 discharges voltage through the third switch sub-circuit 2013, causing switch device Q1 to disconnect quickly. After switch device Q1 disconnects, the energy storage circuit L and the freewheeling diode D1 form a freewheeling circuit to consume the electrical energy in the energy storage circuit L.

[0154] The control circuit 203 can control the switching device Q1 to turn on and off by controlling the ratio of the first time period to the second time period (which can be understood as the duty cycle of the PWM signal), thereby realizing the charging of the pre-charge capacitor C with a limited current and avoiding excessive charging current that could damage the pre-charge capacitor C.

[0155] In this embodiment, during the continuous charging of the pre-charge capacitor C, a second capacitor C2 is connected to the first voltage reference terminal GND1 to counteract the continuous decrease in voltage between the first terminal of the power battery 100 and the first voltage reference terminal GND1 during the pre-charging process, ensuring a stable driving power supply for the switching device Q1. Simultaneously, as the potential of the first voltage reference terminal GND1 continuously rises, the voltage difference between the first terminal of the power battery 100 and the first voltage reference terminal GND1 continuously decreases. When the voltage difference between the first terminal of the power battery 100 and the first voltage reference terminal GND1 falls below the voltage regulation value of the Zener diode D2, the second capacitor C2 continuously discharges as an energy storage element, ensuring a stable driving power supply for the switching device Q1.

[0156] As can be seen from the above, based on the pre-charging device provided in the embodiments of this application, by setting a step-down circuit, not only is it not necessary to introduce an isolation circuit, but also not necessary to set a low-voltage power supply, bootstrap circuit, etc., it can realize the power supply and control of the switching circuit, saving space, reducing weight, and reducing the hardware cost of the pre-charging device.

[0157] In some embodiments, this application also provides a control method for a pre-charging device, applied to the pre-charging device of the above embodiments, the control method for the pre-charging device including: The step-down circuit is controlled to reduce the first voltage input to the power battery to a second voltage. The second voltage is then applied to the switching circuit to turn it on, allowing the power battery to charge the pre-charge capacitor through the energy storage circuit.

[0158] In some embodiments, the control method for the pre-charging device further includes: determining the single-on time of the first terminal and the second terminal of the switching circuit based on the parameters of the energy storage circuit and the pre-charging capacitor.

[0159] In some embodiments, the switching circuit includes: a switching device and a second switching sub-circuit, a first terminal of the switching device being coupled to an energy storage circuit, and a second terminal of the switching device being coupled to a pre-charge capacitor. Applying a second voltage to the switching circuit to turn it on, so that the power battery charges the pre-charge capacitor through the energy storage circuit, includes: controlling the second switching sub-circuit to turn on, applying the second voltage to the controlled terminal of the switching device to turn it on, so that the power battery charges the pre-charge capacitor through the energy storage circuit.

[0160] The specific implementation of the control method for the pre-charge device has been explained in detail when introducing the pre-charge device, and will not be repeated here.

[0161] The specific control logic can be referred to the working logic of the control circuit in the above embodiment, and will not be repeated here.

[0162] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. A pre-charging device, characterized in that, include: An energy storage circuit (L) is provided, the first end of which is used to couple to the first end of a power battery (100). A switching circuit (201), the first terminal of which is coupled to the second terminal of the energy storage circuit (L); A step-down circuit (202) is provided, wherein a first terminal of the step-down circuit (202) is coupled to a first terminal of the power battery (100), and a second terminal of the step-down circuit (202) is coupled to the switching circuit (201); the step-down circuit (202) is configured to reduce a first voltage input to the first terminal of the step-down circuit (202) to a second voltage, and output the second voltage through the second terminal of the step-down circuit (202); A pre-charge capacitor (C) has a first terminal coupled to the second terminal of the switching circuit (201), and the second terminal of the pre-charge capacitor (C) is used to couple to the second terminal of the power battery (100). The switching circuit (201) is configured to: based on the second voltage, connect the first terminal of the switching circuit (201) to the second terminal of the switching circuit (201) so that the power battery (100) charges the pre-charge capacitor (C) through the energy storage circuit (L).

2. The pre-charging device according to claim 1, characterized in that, The step-down circuit (202) includes: A first switch sub-circuit (2021) is used to couple to the first terminal of the power battery (100); A step-down sub-circuit (2022) has a first terminal coupled to the second terminal of the first switching sub-circuit (2021), a second terminal coupled to the switching circuit (201), and a third terminal coupled to the first terminal of the pre-charge capacitor (C) and the first voltage reference terminal (GND1). A power amplifier sub-circuit (2023) is provided, wherein the first terminal of the power amplifier sub-circuit (2023) is coupled to the first terminal of the buck sub-circuit (2022), and the second terminal of the power amplifier sub-circuit (2023) is coupled to the second terminal of the buck sub-circuit (2022). The first switch sub-circuit (2021) is configured to connect the first terminal of the first switch sub-circuit (2021) to the second terminal of the first switch sub-circuit (2021) when the pre-charge capacitor (C) is pre-charged.

3. The pre-charging device according to claim 2, characterized in that, The step-down sub-circuit (2022) includes: The first resistor (R1) has its first end coupled to the second end of the first switch sub-circuit (2021); A Zener diode (D2) is provided, wherein the first terminal of the Zener diode (D2) is coupled to the second terminal of the first resistor (R1), and the second terminal of the Zener diode (D2) is coupled to the first voltage reference terminal (GND1); the voltage between the first terminal and the second terminal of the Zener diode (D2) is the second voltage. A first capacitor (C1) has its first terminal coupled to the first terminal of the Zener diode (D2), and its second terminal coupled to the second terminal of the Zener diode (D2). The second capacitor (C2) has its first end coupled to the second end of the power amplifier sub-circuit (2023), and its second end coupled to the first voltage reference terminal (GND1).

4. The pre-charging device according to claim 3, characterized in that, The power amplifier sub-circuit (2023) includes: The second resistor (R2) has its first end coupled to the second end of the first switch sub-circuit (2021); Transistor (Q2), the first end of which is coupled to the first end of Zener diode (D2), the second end of which is coupled to the second end of second resistor (R2), the third end of which is coupled to the first end of second capacitor (C2) and the first end of switch circuit (201).

5. The pre-charging device according to claim 2, characterized in that, The first switch sub-circuit (2021) includes: Anti-reverse diode (D3), the first terminal of which is coupled to the first terminal of the power battery (100); A first optocoupler switch (U1) has its first terminal coupled to the second terminal of the anti-reverse diode (D3), its second terminal coupled to the first terminal of the step-down sub-circuit (2022), its third terminal used to input a first control signal, and its fourth terminal coupled to a second voltage reference terminal (GND2). The first optocoupler switch (U1) is configured to, when precharging the precharge capacitor (C), conduct the third terminal and the fourth terminal of the first optocoupler switch (U1) based on the first control signal, thereby connecting the first terminal and the second terminal of the first optocoupler switch (U1).

6. The pre-charging device according to claim 1, characterized in that, The switching circuit (201) includes: A switching device (Q1), the first terminal of which is coupled to the second terminal of the energy storage circuit (L), and the second terminal of which is coupled to the pre-charge capacitor (C). The second switching sub-circuit (2012) has a first terminal coupled to the second terminal of the step-down circuit (202) and a second terminal coupled to the controlled terminal of the switching device (Q1). The second switching sub-circuit (2012) is configured to connect the first terminal of the second switching sub-circuit (2012) and the second terminal of the second switching sub-circuit (2012) when the pre-charge capacitor (C) is pre-charged.

7. The pre-charging device according to claim 6, characterized in that, The second switching sub-circuit (2012) includes: The second optocoupler switch (U2) has its first terminal coupled to the second terminal of the step-down circuit (202), its second terminal coupled to the controlled terminal of the switching device (Q1), its third terminal used to input a second control signal, and its fourth terminal coupled to a second voltage reference terminal (GND2). The second optocoupler switch (U2) is configured to, when precharging the precharge capacitor (C), conduct the third terminal and the fourth terminal of the second optocoupler switch (U2) based on the second control signal, thereby connecting the first terminal and the second terminal of the second optocoupler switch (U2).

8. The pre-charging device according to claim 6, characterized in that, The switching circuit (201) further includes: A third switching sub-circuit (2013) has a first terminal coupled to the controlled terminal of the switching device (Q1) and a second terminal coupled to a first voltage reference terminal (GND1). The third switching sub-circuit (2013) is configured to connect the first terminal of the third switching sub-circuit (2013) to the second terminal of the second switching sub-circuit (2012) when the first terminal of the second switching sub-circuit (2012) is disconnected from the second terminal of the second switching sub-circuit (2012).

9. The pre-charging device according to claim 8, characterized in that, The third switch sub-circuit (2013) includes: The third optocoupler switch (U3) has its first terminal coupled to the controlled terminal of the switching device (Q1), its second terminal coupled to the first voltage reference terminal (GND1), its third terminal coupled to the power supply (2011), and its fourth terminal used to input a third control signal. The third optocoupler switch (U3) is configured to, when the first terminal of the second switching sub-circuit (2012) is disconnected from the second terminal of the second switching sub-circuit (2012), conduct the third terminal and the fourth terminal of the third optocoupler switch (U3) based on the third control signal, so that the first terminal and the second terminal of the third optocoupler switch (U3) are connected.

10. The pre-charging device according to any one of claims 1-9, characterized in that, Also includes: The control circuit (203), coupled to the switching circuit (201), is configured to control the single-on time of the first terminal of the switching circuit (201) and the second terminal of the switching circuit (201) according to the parameters of the energy storage circuit (L) and the pre-charge capacitor (C).

11. A control method for a pre-charging device, characterized in that, The method, applied to the pre-charge device as described in any one of claims 1-10, comprises: The step-down circuit is controlled to reduce the first voltage input to the power battery to a second voltage. The second voltage is applied to the switching circuit to turn it on, so that the power battery can charge the pre-charge capacitor through the energy storage circuit.

12. The control method for the predictive device according to claim 11, characterized in that, Also includes: Based on the parameters of the energy storage circuit and the pre-charge capacitor, the single-time conduction time of the first terminal and the second terminal of the switching circuit is determined.

13. The control method for the pre-charge device according to claim 12, characterized in that, The switching circuit includes: a switching device and a second switching sub-circuit. A first terminal of the switching device is coupled to the energy storage circuit, and a second terminal of the switching device is coupled to the pre-charge capacitor. Applying the second voltage to the switching circuit to turn it on, allowing the power battery to charge the pre-charge capacitor through the energy storage circuit, includes: The second switch sub-circuit is controlled to conduct, and the second voltage is applied to the controlled terminal of the switch device to conduct the switch device, so that the power battery charges the pre-charge capacitor through the energy storage circuit.

14. A battery pack, characterized in that, include: Power battery, And a pre-charging device as described in any one of claims 1-10, coupled to the power battery.

15. A vehicle, characterized in that, include: The pre-charge device as described in any one of claims 1-10, or the battery pack as described in claim 14.

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