Pre-charge circuit and battery system

Abstract

The application discloses a pre-charging circuit and a battery system, through a pre-charging unit, the pre-charging circuit can realize gentle current storage and energy release, and through a loop switching unit, the pre-charging circuit can realize switching of a second loop and a first loop accessed by the pre-charging unit, and then the pre-charging circuit can complete pre-charging of a load by using the energy storage and energy release characteristics of the pre-charging unit. Meanwhile, the control of a driving circuit on the loop switching of the loop switching unit can be completed based on a pre-charging current of the pre-charging circuit, so that the pre-charging current flowing through the pre-charging unit can be kept in a constant average current state in the process of continuous energy storage and energy release of the pre-charging unit, thereby making the pre-charging of the load end more stable and rapid, and reducing the overall heat dissipation.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicles, and in particular to a pre-charging circuit and battery system. Background Technology

[0002] With the booming development of electric vehicles in the new energy field, the safety and energy efficiency of electric vehicle battery systems are receiving increasing attention, and measures to improve system performance and reliability are becoming more and more abundant. In traditional battery systems, a passive pre-charging scheme is generally adopted, in which a pre-charging resistor limits the current to pre-charge the bus capacitor. During pre-charging, the pre-charging resistor generates a lot of heat. On the one hand, this affects the service life of the pre-charging resistor, and in severe cases, it may cause thermal failure of the pre-charging resistor and lead to fire. At the same time, the heat dissipated by the pre-charging resistor can damage surrounding devices, affecting system safety. On the other hand, it increases system power consumption and reduces system economy. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a pre-charging circuit that can solve the problem of high heat dissipation.

[0004] The present invention also proposes a battery system.

[0005] According to a first aspect of the present invention, a pre-charging circuit is applied to a battery system, the battery system including an energy storage unit, a main positive relay, and a main negative relay, wherein the positive terminal of the energy storage unit is connected to one end of the main positive relay, the negative terminal of the energy storage unit is connected to one end of the main negative relay, the other end of the main positive relay is connected to one end of a load, and the other end of the main negative relay is connected to the other end of the load.

[0006] The pre-charging circuit includes:

[0007] A pre-charge unit is used to smoothly flow the current through the pre-charge unit and store electrical energy;

[0008] A circuit switching unit is used to switch between a first circuit and a second circuit. The first circuit is composed of the pre-charge unit and the load connected in series, and the second circuit is composed of the pre-charge unit, the energy storage unit, the main positive relay, and the load connected in series.

[0009] The driving circuit has a voltage detection terminal, a reference voltage terminal, and a loop switching control terminal. The voltage detection terminal is used to acquire the real-time voltage corresponding to the pre-charge current flowing through the pre-charge unit. The reference voltage terminal is used to connect to a first reference voltage. The driving circuit is used to obtain a driving voltage based on the real-time voltage and the first reference voltage, and output the driving voltage to the loop switching unit through the loop switching control terminal, so that the loop switching unit completes the switching between the second loop and the first loop.

[0010] The pre-charging circuit according to embodiments of the present invention has at least the following beneficial effects:

[0011] The pre-charge unit can smooth the current and store energy, and then release the stored energy. The loop switching unit can switch between the first and second loops connected to the pre-charge unit, thus utilizing the energy storage and release characteristics of the pre-charge unit to pre-charge the load. Simultaneously, the drive circuit controls the loop switching based on the pre-charge current of the pre-charge loop, ensuring that the pre-charge current flowing through the pre-charge unit remains at a constant average current during the continuous energy storage and release process. This results in smoother and faster pre-charging of the load, while also reducing overall heat dissipation.

[0012] According to some embodiments of the present invention, the loop switching unit includes:

[0013] A switching unit has a switch input terminal, a switch output terminal, and a switch controlled terminal. The switch input terminal is connected to the output terminal of the pre-charge unit, the switch output terminal is connected to the negative terminal of the energy storage unit, and the switch controlled terminal is connected to the loop switching control terminal. The input terminal of the pre-charge unit is connected to the other end of the load.

[0014] The first unidirectional conducting device has its input terminal connected to the output terminal of the precharge unit and its output terminal connected to one end of the load.

[0015] According to some embodiments of the present invention, the circuit switching unit further includes a second unidirectional conducting device connected between the output terminal of the precharge unit and the switch input terminal.

[0016] According to some embodiments of the present invention, the pre-charge unit includes:

[0017] A pre-charge sensor, one end of which is connected to the other end of the load;

[0018] The first current sampling resistor has one end connected to the other end of the pre-charge inductor and the other end connected to the switch input terminal.

[0019] According to some embodiments of the present invention, the precharge unit further includes a first safety unit connected between one end of the precharge inductor and the other end of the load.

[0020] According to some embodiments of the present invention, the driving circuit includes:

[0021] A hysteresis comparator has a first input terminal, a second input terminal, and a first comparison output terminal, wherein the first input terminal is connected to one end of the pre-charge inductor, and the first comparison output terminal is connected to the switch-controlled terminal.

[0022] The first resistor has one end connected to the second input terminal and the other end connected to the first reference voltage.

[0023] The second resistor is connected between the first comparator output terminal and the second input terminal.

[0024] According to some embodiments of the present invention, the constraint formula for the pre-charge current is:

[0025]

[0026] In the formula, I MAX I is the maximum value of the pre-charge current. MIN R3 is the minimum value of the pre-charge current, R4 is the first resistor, R1 is the first current sampling resistor, VCC is the operating voltage of the hysteresis comparator, and V1 is the first reference voltage.

[0027] According to some embodiments of the present invention, the driving circuit further includes an isolated gate driver connected between the first comparator output terminal and the switch controlled terminal.

[0028] According to some embodiments of the present invention, the pre-charging circuit further includes:

[0029] An overcurrent protection unit is used to detect the pre-charge current flowing through the pre-charge unit and adjust the operating state of the drive circuit.

[0030] According to some embodiments of the present invention, the overcurrent protection unit includes:

[0031] The second current sampling resistor is connected between the switch output terminal and the negative terminal of the energy storage unit;

[0032] An operational amplifier unit has a third input terminal, a fourth input terminal, and an operational amplifier output terminal, wherein the third input terminal and the fourth input terminal are respectively connected to the two ends of the second current sampling resistor;

[0033] A voltage comparator has a fifth input terminal, a sixth input terminal, and a second comparison output terminal. The fifth input terminal is connected to the output terminal of the operational amplifier, the sixth input terminal is used to connect to a second reference voltage, and the second comparison output terminal is used to adjust the operating state of the drive circuit.

[0034] The battery system according to a second aspect embodiment of the present invention includes the pre-charging circuit of the first aspect embodiment. Since the battery system of the present invention substantially employs all the technical solutions of the pre-charging circuit of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 This is a schematic diagram of a battery system according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the voltage change of the capacitor of the load according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram illustrating the change in the pre-charge current flowing through the pre-charge inductor according to an embodiment of the present invention.

[0040] Figure label:

[0041] Energy storage unit 110, main positive relay 120, main negative relay 130, load 140,

[0042] Precharge unit 210, circuit switching unit 220, drive circuit 230, overcurrent protection unit 240. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features indicated, or implicitly indicating the order of the technical features indicated.

[0045] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0047] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0048] To better describe the pre-charging circuit of this embodiment of the invention, the applied battery system is briefly described here. The battery system includes an energy storage unit 110, a main positive relay 120, a main negative relay 130, and a battery management system. The positive terminal of the energy storage unit 110 is connected to one end of the main positive relay 120, and the negative terminal of the energy storage unit 110 is connected to one end of the main negative relay 130. The other end of the main positive relay 120 is connected to one end of the load 140, and the other end of the main negative relay 130 is connected to the other end of the load 140. After the battery management system controls the main positive relay 120 and the main negative relay 130 to close, the electrical energy in the energy storage unit 110 can supply power to the load 140.

[0049] See Figure 1 As shown, Figure 1 This is a pre-charging circuit provided in one embodiment of the present invention. The pre-charging circuit includes a pre-charging unit 210, a current detection unit, a voltage detection unit, and a loop switching unit 220.

[0050] Pre-charging circuit, including:

[0051] The pre-charge unit 210 is used to smooth the current flowing through the pre-charge unit 210 and store electrical energy;

[0052] The circuit switching unit 220 is used to switch between the first circuit and the second circuit. The first circuit is composed of the precharge unit 210 and the load 140 connected in series, and the second circuit is composed of the precharge unit 210, the energy storage unit 110, the main positive relay 120, and the load 140 connected in series.

[0053] The driving circuit 230 has a voltage detection terminal, a reference voltage terminal, and a loop switching control terminal. The voltage detection terminal is used to obtain the real-time voltage corresponding to the pre-charge current flowing through the pre-charge unit 210. The reference voltage terminal is used to connect to the first reference voltage V1. The driving circuit 230 is used to obtain the driving voltage according to the real-time voltage and the first reference voltage V1, and outputs the driving voltage to the loop switching unit 220 through the loop switching control terminal, so that the loop switching unit 220 completes the switching between the second loop and the first loop.

[0054] refer to Figure 1 The circuit switching unit 220 can switch between two circuits: whether the pre-charge unit 210 is directly connected to both ends of the load 140 to form the first circuit, or whether the pre-charge unit 210 forms the second circuit through the energy storage unit 110 and the main positive relay 120 in series. When the main relay is closed, and the circuit switching unit 220 switches to the second circuit, the pre-charge unit 210, the energy storage unit 110, the main positive relay 120, and the load 140 are connected in series to form the second circuit. The energy storage unit 110 directly pre-charges the load 140. At the same time, the pre-charge current flows smoothly through the pre-charge unit 210, completing energy storage. When the circuit switching unit 220 switches to the first circuit, the pre-charge unit 210 and the load 140 are connected in series to form the first circuit. The energy stored in the pre-charge unit 210 pre-charges the load 140. After pre-charging is completed, the main negative relay 130 can be connected to stop pre-charging and start formal power supply.

[0055] To ensure smooth and rapid pre-charging, a pre-charging current is introduced to control the switching of the circuit switching unit 220. By continuously switching between the first and second circuits, the pre-charging unit 210 continuously stores and releases energy, thereby controlling the pre-charging current flowing through the pre-charging unit 210 within a stable range, maintaining the pre-charging current at a constant average current. Furthermore, detecting the pre-charging voltage across the load 140 can determine whether pre-charging is complete. When the pre-charging voltage reaches the required level, the main negative relay 130 can be activated to complete the formal output power supply.

[0056] In this embodiment of the invention, the pre-charge unit 210 in the pre-charge circuit can achieve current smoothing and energy storage, and can release energy after storage. The circuit switching unit 220 can switch between the second circuit and the first circuit connected to the pre-charge unit 210, thereby utilizing the energy storage and release characteristics of the pre-charge unit 210 to complete the pre-charging of the load 140. At the same time, the drive circuit 230 can control the circuit switching of the circuit switching unit 220 based on the pre-charging current of the pre-charge circuit, so that the pre-charging current flowing through the pre-charge unit 210 can remain at a constant average current during the continuous energy storage and release of the pre-charge unit 210. This makes the pre-charging of the load 140 more stable and rapid, while also reducing the overall heat dissipation.

[0057] refer to Figure 1 In some embodiments, the loop switching unit 220 includes a switching unit and a first unidirectional conducting device.

[0058] The switching unit has a switch input terminal, a switch output terminal, and a switch controlled terminal. The switch input terminal is connected to the output terminal of the precharge unit 210, the switch output terminal is connected to the negative terminal of the energy storage unit 110, and the switch controlled terminal is connected to the loop switching control terminal. The input terminal of the precharge unit 210 is connected to the other end of the load 140.

[0059] The first unidirectional conducting device has its input terminal connected to the output terminal of the precharge unit 210 and its output terminal connected to one end of the load 140.

[0060] refer to Figure 1 The switching unit is controlled by the drive circuit 230, which can adjust the opening and closing of the switch input terminal and the switch output terminal, thereby enabling control over whether the pre-charge unit 210 is connected to the negative terminal of the energy storage unit 110. Furthermore, when it is necessary to switch between the first circuit and the second circuit, the switching unit can be used directly to complete the switch.

[0061] When the switching unit is in the ON state, due to the reverse cut-off characteristic of the first unidirectional conducting device, current can be output from the positive terminal of the energy storage unit 110, flow through the main positive relay 120, the load 140, the pre-charge unit 210, and the switching unit, and return to the negative terminal of the energy storage unit 110, forming a second circuit. When the switching unit is in the OFF state, the energy storage unit 110 cannot form a circuit. At this time, the pre-charge unit 210 can release energy in this state because it stored energy when the first circuit was working. Current can start from the output terminal of the pre-charge unit 210, flow through the unidirectional conducting device into the load 140, and then return from the load 140 to the input terminal of the pre-charge unit 210, forming the first circuit, and continuing to pre-charge the capacitor at the load 140 terminal.

[0062] In some embodiments, the switching unit is a MOSFET. The MOSFET can achieve on / off control under high power conditions, ensuring accurate switching between the second and first circuits. (Reference) Figure 1 , Figure 1 An NMOS transistor Q1 is used, with its source connected to the negative terminal of the energy storage unit 110, its drain connected to the output terminal of the pre-charge unit 210, and its gate connected to the driving circuit 230. This allows for on / off control under the control of the driving circuit 230. Furthermore, using a MOS transistor enables load-bearing cutoff, which provides better circuit safety compared to the traditional method of directly connecting a relay to the passive resistor pre-charge circuit. In some embodiments, the first unidirectional conducting device is a diode, for example... Figure 1 The first diode D1 is shown in the figure.

[0063] refer to Figure 1 In some embodiments, the circuit switching unit 220 further includes a second unidirectional conducting device connected between the output terminal of the precharge unit 210 and the switch input terminal. The second unidirectional conducting device can also serve as a reverse cutoff device, achieving the purpose of protection. The second unidirectional conducting device can be a diode, for example... Figure 1 The second diode D2 is shown in the diagram.

[0064] In some embodiments, the pre-charge unit 210 includes a pre-charge inductor L1 and a first current sampling resistor R1. One end of the pre-charge inductor L1 is connected to the other end of the load 140; one end of the first current sampling resistor R1 is connected to the other end of the pre-charge inductor L1, and the other end is connected to the switch input terminal. (Reference) Figure 1 The pre-charge inductor L1 serves to smooth the current and store energy. During second-circuit operation, the pre-charge current flows through the pre-charge inductor L1. Due to its inductive characteristics, the pre-charge inductor L1 stores some energy. However, as the second-circuit operation time increases, the pre-charge current flowing through the pre-charge inductor L1 continues to grow. Simultaneously, the first current sampling resistor R1 converts the pre-charge current into a real-time voltage. When the real-time voltage exceeds the reference voltage, the switching unit switches the pre-charge inductor L1 to the first-circuit operation. At this point, the pre-charge inductor L1 acts as a power supply device, continuing to pre-charge the load 140.

[0065] refer to Figure 1 In some embodiments, the precharge unit 210 further includes a first fuse unit connected between one end of the precharge inductor L1 and the other end of the load 140. The first fuse unit is a fuse that can protect the circuit by directly melting when the current is too high.

[0066] refer to Figure 1In some embodiments, the driving circuit 230 includes a hysteresis comparator IC2, a first resistor R3, and a second resistor R4. The hysteresis comparator IC2 has a first input terminal, a second input terminal, and a first comparison output terminal. The first input terminal is connected to one end of the pre-charge inductor L1, and the first comparison output terminal is connected to the switch control terminal. The first resistor R3 has one end connected to the second input terminal and the other end connected to a first reference voltage V1. The second resistor R4 is connected between the first comparison output terminal and the second input terminal. Because of the hysteresis comparison logic, the delayed on / off control of the switching unit can be completed using only one hysteresis comparator IC2, that is, the maximum and minimum values ​​of the pre-charge current in the pre-charge circuit can be determined. Specifically, the maximum and minimum values ​​of the pre-charge current can be determined using the first reference voltage V1, the first current sampling resistor R1, the operating voltage VCC of the hysteresis comparator IC2, the first resistor R3, and the second resistor R4.

[0067] refer to Figure 1 In some embodiments, the driving circuit 230 further includes an isolation gate driver IC1 connected between the first comparator output terminal and the switch-controlled terminal. The isolation gate driver IC1 can both provide isolation and effectively drive the NMOS transistor.

[0068] refer to Figure 1 In some embodiments, the pre-charging circuit further includes an overcurrent protection unit 240, which detects the pre-charging current flowing through the pre-charging unit 210 and adjusts the operating state of the drive circuit 230. The overcurrent protection unit 240 serves as an active safety protection measure, enabling the switching unit to be actively disconnected when the circuit current is large, thereby limiting excessive current. The overcurrent protection unit 240 effectively prevents the fuse from blowing directly or prolonged overcurrent operation.

[0069] In some embodiments, the overcurrent protection unit 240 includes a second current sampling resistor R2, an operational amplifier unit U1, and a voltage comparator U2.

[0070] The second current sampling resistor R2 is connected between the switch output terminal and the negative terminal of the energy storage unit 110;

[0071] Operational amplifier unit U1 has a third input terminal, a fourth input terminal and an operational amplifier output terminal. The third input terminal and the fourth input terminal are respectively connected to the two ends of the second current sampling resistor R2.

[0072] The voltage comparator U2 has a fifth input terminal, a sixth input terminal, and a second comparison output terminal. The fifth input terminal is connected to the output terminal of the operational amplifier, the sixth input terminal is used to connect to the second reference voltage V2, and the second comparison output terminal is used to adjust the operating state of the drive circuit 230.

[0073] The second current sampling resistor R2 converts the pre-charge current in the detected circuit into a real-time voltage. After preliminary amplification by the operational amplifier unit U1, the voltage is sent to the voltage comparator U2 for comparison with the second reference voltage V2 to determine whether an overcurrent has occurred. It is understandable that by changing the value of the second reference voltage V2, the execution standard of the overcurrent protection action can be adjusted to suit the protection requirements of different pre-charge circuits.

[0074] To better describe the pre-charging circuit of the embodiments of the present invention, it is combined with... Figure 1 , Figure 3 The following is a description of a specific embodiment, in which the energy storage unit 110 directly uses a power battery.

[0075] The circuit connection relationship in this specific embodiment will be described first.

[0076] The positive terminal of the power battery is connected to the cathode of the first diode D1 and one end of the load 140. The other end of the load 140 is connected to one end of the fuse F1. The other end of the fuse F1 is connected to one end of the pre-charge inductor L1. The other end of the pre-charge inductor L1 is connected to one end of the first current sampling resistor R1. The other end of the first current sampling resistor R1 is connected to the anode of the first diode D1 and the anode of the second diode D2. The cathode of the second diode D2 is connected to the drain of the NMOS transistor Q1. The source of the NMOS transistor Q1 is connected to one end of the second current sampling resistor R2, and the other end of the second current sampling resistor R2 is connected to the negative terminal of the power battery. Thus, the first diode D1, load 140, fuse F1, pre-charge inductor L1, and first current sampling resistor R1 constitute the first circuit; the power battery, fuse F2, load 140, fuse F1, pre-charge inductor L1, first current sampling resistor R1, second diode D2, NMOS transistor Q1, and second current sampling resistor R2 constitute the second circuit.

[0077] The negative input terminal of the hysteresis comparator IC2 is connected to the end of the pre-charge inductor L1 near the first current sampling resistor R1, the positive input terminal is connected to the first reference voltage V1 through the first resistor R3, and the output terminal is connected to the positive input terminal by the second resistor R4.

[0078] The input of the isolated gate driver IC1 is connected to the output of the hysteresis comparator IC2, and the output is connected to the gate of the NMOS transistor Q1.

[0079] The positive and negative input terminals of the operational amplifier unit U1 are connected to the two ends of the second current sampling resistor R2, respectively; the negative input terminal of the voltage comparator U2 is connected to the output terminal of the operational amplifier unit U1, the positive input terminal is connected to the second reference voltage V2, and the output terminal is connected to the enable terminal or the operating voltage terminal of the isolated gate driver IC1.

[0080] Based on the above specific circuit structure, the specific working process of this specific embodiment is described here.

[0081] The main positive relay 120 closes, and pre-charging starts. The pre-charging circuit of this specific embodiment is put into operation. The positive input terminal VIN+ of the hysteresis comparator IC2 is connected to the first reference voltage V1. At this time, the pre-charging current I is 0, and the real-time voltage is 0, that is, the voltage of the negative input terminal VIN- of the hysteresis comparator IC2 is 0. Therefore, VIN- < VIN+, and the output voltage VOUT of the hysteresis comparator IC2 outputs the voltage VCC. At this time, the isolation gate driver IC1 drives the NMOS transistor to conduct, and the pre-charging current flows through the second loop, and the power battery charges the load 140 and the pre-charging inductor L1.

[0082] When the pre-charging current reaches the maximum value I MAX *, VIN- = I MAX *R1 = VIN+, VOUT is 0. At this time, the isolation gate driver IC1 drives the NMOS transistor to disconnect, and the pre-charging current flows through the first loop, and the pre-charging inductor L1 discharges and charges the load 140. When the pre-charging current decreases to the minimum value I MIN *, VIN- = I MIN *R1 = VIN+, VOUT = VCC. At this time, the isolation gate driver IC1 drives the NMOS transistor to conduct, and the pre-charging current flows through the second loop, and the power battery charges the load 140 and the pre-charging inductor L1. When the pre-charging current reaches the maximum value I MAX *, VIN- = I MAX *R1 = VIN+, VOUT = 0. At this time, the isolation gate driver IC1 drives the NMOS transistor to disconnect, and the pre-charging current flows through the first loop, and the pre-charging inductor L1 discharges and charges the load 140. By continuously charging and discharging the pre-charging inductor L1, the pre-charging current can be controlled between I MAX and I MIN , until the requirements for pre-charging are met at both ends of the load 140.

[0083] In addition, to determine the maximum value I MAX and the minimum value I MIN of the pre-charging current, the following formula can be referred to:

[0084]

[0085] To better describe the actual effect of the present invention, here in combination with Figure 2 , Figure 3 , further explanation is carried out. As Figure 2 shown, Figure 2In the graph, the horizontal axis represents time, and the vertical axis represents the voltage on the 140Ω capacitor side of the load. It can be seen that the capacitor voltage increases almost linearly. Since the charging voltage remains essentially constant, it can be observed that the pre-charging current remains essentially constant throughout the charging process, or rather, it remains a constant average current. Further combining... Figure 3 , Figure 3 The waveform shown is the actual waveform of the pre-charge current flowing through the pre-charge inductor L1. Figure 3 The horizontal axis represents time, and the vertical axis represents the pre-charge current value. It can be seen that between the continuous switching on and off of the MOSFET, the pre-charge current flowing through the pre-charge inductor L1 remains within a constant range, thus ensuring that the pre-charge current can be in a constant average current effect.

[0086] See Figure 1 As shown, one embodiment of the present invention also proposes a battery system including the pre-charging circuit as described above. Since the battery system of this embodiment substantially employs all the technical solutions of the pre-charging circuit described above, it possesses at least all the beneficial effects brought about by the technical solutions of the described embodiments.

[0087] refer to Figure 1 In some embodiments, the battery system further includes a second fuse unit connected between the positive terminal of the energy storage unit 110 and one end of the main positive relay 120. The second fuse unit provides overcurrent protection, thereby ensuring the safety of the battery system's power supply. The second fuse unit can be a fuse, for example... Figure 1 The fuse shown is F2.

[0088] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A pre-charging circuit, applied to a battery system, characterized in that, The battery system includes an energy storage unit, a main positive relay, and a main negative relay. The positive terminal of the energy storage unit is connected to one end of the main positive relay, the negative terminal of the energy storage unit is connected to one end of the main negative relay, the other end of the main positive relay is connected to one end of the load, and the other end of the main negative relay is connected to the other end of the load. The pre-charging circuit includes: A pre-charge unit is used to smoothly flow the current through the pre-charge unit and store electrical energy; A circuit switching unit is used to switch between a first circuit and a second circuit. The first circuit is composed of the pre-charge unit and the load connected in series, and the second circuit is composed of the pre-charge unit, the energy storage unit, the main positive relay, and the load connected in series. The driving circuit has a voltage detection terminal, a reference voltage terminal, and a loop switching control terminal. The voltage detection terminal is used to acquire the real-time voltage corresponding to the pre-charge current flowing through the pre-charge unit. The reference voltage terminal is used to connect to a first reference voltage. The driving circuit is used to obtain a driving voltage based on the real-time voltage and the first reference voltage, and output the driving voltage to the loop switching unit through the loop switching control terminal, so that the loop switching unit can complete the switching between the second loop and the first loop. The loop switching unit includes: A switching unit has a switch input terminal, a switch output terminal, and a switch controlled terminal. The switch input terminal is connected to the output terminal of the pre-charge unit, the switch output terminal is connected to the negative terminal of the energy storage unit, and the switch controlled terminal is connected to the loop switching control terminal. The input terminal of the pre-charge unit is connected to the other end of the load. The first unidirectional conducting device has its input terminal connected to the output terminal of the precharge unit and its output terminal connected to one end of the load. The pre-charge unit includes: A pre-charge sensor, one end of which is connected to the other end of the load; The first current sampling resistor has one end connected to the other end of the pre-charge inductor and the other end connected to the switch input terminal. The circuit switching unit also includes a second unidirectional conduction device connected between the output terminal of the precharge unit and the switch input terminal.

2. The pre-charging circuit according to claim 1, characterized in that, The driving circuit includes: A hysteresis comparator has a first input terminal, a second input terminal, and a first comparison output terminal. The first input terminal is connected to one end of the pre-charge inductor, and the first comparison output terminal is connected to the switch-controlled terminal. The first resistor has one end connected to the second input terminal and the other end connected to the first reference voltage. The second resistor is connected between the first comparator output terminal and the second input terminal.

3. The pre-charging circuit according to claim 2, characterized in that, The constraint formula for the pre-charge current is: In the formula, I MAX I is the maximum value of the pre-charge current. MIN R3 is the minimum value of the pre-charge current, R4 is the first resistor, R1 is the first current sampling resistor, VCC is the operating voltage of the hysteresis comparator, and V1 is the first reference voltage.

4. The pre-charging circuit according to claim 2, characterized in that, The driving circuit also includes an isolated gate driver connected between the first comparator output terminal and the switch-controlled terminal.

5. The pre-charging circuit according to claim 1, characterized in that, The pre-charging circuit also includes: An overcurrent protection unit is used to detect the pre-charge current flowing through the pre-charge unit and adjust the operating state of the drive circuit.

6. The pre-charging circuit according to claim 5, characterized in that, The overcurrent protection unit includes: The second current sampling resistor is connected between the switch output terminal and the negative terminal of the energy storage unit; An operational amplifier unit has a third input terminal, a fourth input terminal, and an operational amplifier output terminal, wherein the third input terminal and the fourth input terminal are respectively connected to the two ends of the second current sampling resistor; A voltage comparator has a fifth input terminal, a sixth input terminal, and a second comparison output terminal. The fifth input terminal is connected to the output terminal of the operational amplifier, the sixth input terminal is used to connect to a second reference voltage, and the second comparison output terminal is used to adjust the operating state of the drive circuit.

7. A battery system, characterized in that, Includes the pre-charging circuit as described in any one of claims 1 to 6.

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