New energy vehicle high-voltage bus pre-charging circuit system and method and vehicle

Abstract

The invention discloses a new energy automobile high-voltage bus pre-charging circuit system and method and a vehicle, and belongs to the field of new energy automobiles. The system comprises a series main loop and a battery management system which are sequentially composed of a power battery positive electrode, a main positive relay, a load capacitor, a main negative relay and a power battery negative electrode, and further comprises a pre-charging circuit, the pre-charging circuit comprises a pre-charging resistor, a single-phase conduction device and a solid-state relay composed of an isolation controller and a field effect transistor. The solid-state relay is connected in series with the pre-charging resistor and the single-phase conduction device in sequence and then is connected in parallel with the two ends of the main positive relay. The pre-charging power-on process of the high-voltage bus load capacitor is optimized, the high-dynamic scene requirement is met, and the system safety and stability are improved.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicles. Specifically, this invention relates to a high-voltage bus pre-charging circuit system, method and vehicle for new energy vehicles. Background Technology

[0002] Traditional solutions achieve high-voltage pre-charging through a series pre-charge resistor and a mechanical relay. During system startup, the pre-charge mechanical relay closes, and the high-voltage battery charges the load-side capacitor through the pre-charge resistor, limiting inrush current. When the capacitor voltage approaches the battery voltage, the main relay closes, and the pre-charge relay opens, completing the pre-charging process.

[0003] Traditional mechanical relays have a limited lifespan (typically tens of thousands of operations) due to contact wear and arcing issues, making them unsuitable for high-frequency applications. Over time, this leads to relay failure, interrupting pre-charging, preventing the main relay from closing, and preventing the vehicle from receiving high voltage. The operating time (milliseconds) of mechanical relays limits pre-charging speed, and they cannot terminate pre-charging in a very short time to protect the pre-charging circuit in case of a fault. This makes them unsuitable for high-dynamic scenarios. Furthermore, relays occupy space, increasing system complexity and cost.

[0004] Therefore, this invention proposes a high-voltage bus pre-charging circuit system, method, and vehicle for new energy vehicles. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of the prior art and proposes a pre-charging circuit system, method and vehicle for high-voltage bus in new energy vehicles to achieve the following objectives: optimize the pre-charging and power-on process of the high-voltage bus load capacitor, meet the requirements of high dynamic scenarios and improve system safety and stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a pre-charging circuit system for a high-voltage bus of a new energy vehicle, comprising a series main circuit consisting of a positive terminal of a power battery 1, a main positive relay 3, a load capacitor 6, a main negative relay 9, and a negative terminal of the power battery 1, and a battery management system. The system also includes a pre-charging circuit, which includes a pre-charging resistor 4, a single-phase conductor 5, and a solid-state relay consisting of an isolation controller 8 and a field-effect transistor 2. The solid-state relay is connected in parallel across the main positive relay 3 after being connected in series with the pre-charging resistor 4 and the single-phase conductor 5.

[0007] Preferably, the first terminal of the field-effect transistor 2 is connected to the first terminal of the main positive relay 3, and the second terminal of the field-effect transistor 2 is connected to the second terminal of the main positive relay 3 after being connected in series with the pre-charge resistor 4 and the unidirectional conduction device 5. The control terminal of the field-effect transistor 2 is connected to the isolation controller 8. The isolation controller 8 is connected to the battery management system.

[0008] Preferably, the pre-charging circuit further includes a shunt comparator 7, the pre-charging resistor 4 is connected in parallel between the positive input terminal and the negative input terminal of the shunt comparator 7; the positive power supply terminal of the shunt comparator 7 is connected to the isolation controller 8, the negative power supply terminal of the shunt comparator 7 is grounded, and the feedback terminal 10 of the shunt comparator 7 is connected to the isolation controller 8.

[0009] Preferably, the shunt comparator 7 is model AD8214.

[0010] Preferably, the field-effect transistor 2 is N-type, and correspondingly, the first terminal of the field-effect transistor 2 is the drain, the second terminal is the source, the control terminal is the gate, and the gate control voltage is a positive voltage.

[0011] Preferably, the field-effect transistor 2 is a P-type transistor, and correspondingly, the first terminal of the field-effect transistor 2 is the source, the second terminal is the drain, the control terminal is the gate, and the gate control voltage is a negative voltage.

[0012] This application also provides a method for pre-charging a high-voltage busbar of a new energy vehicle, using the aforementioned high-voltage busbar pre-charging circuit system for a new energy vehicle, characterized in that: the method includes: Step S1: The battery management system receives the high-voltage system power-on command, controls the main negative relay 9 to close and activates the isolation controller 8; Step S2: After the isolation controller 8 is activated, it outputs the gate voltage to the field-effect transistor 2, so that the field-effect transistor 2 is turned on and begins pre-charging; Step S3: Within the set pre-charge time window, the battery management system continuously monitors the high-voltage bus voltage and determines whether it has reached the preset voltage threshold. If it has, proceed to step S4; otherwise, proceed to step S5. Step S4: The battery management system controls the main positive relay 3 to close and shuts down the isolation controller 8. Correspondingly, the isolation controller 8 stops outputting the gate voltage, causing the field-effect transistor 2 to turn off. At the same time, the isolation controller 8 enters a sleep state, thus completing the pre-charge process. Step S5: The isolation controller 8 stops outputting the gate voltage, causing the field-effect transistor 2 to turn off. At the same time, the battery management system exits the pre-charge process and reports a pre-charge fault.

[0013] Preferably, step S2 further includes: after the pre-charging starts, the comparator 7 collects the voltage drop across the pre-charging resistor 4 in real time to obtain the pre-charging current, and compares it with the preset current threshold in the comparator 7. If the comparator 7 detects that the pre-charging current is greater than or equal to the preset current threshold, the comparator 7 outputs an abnormal signal through the feedback terminal 10 to enable the isolation controller 8 and then jumps to step S5; if the comparator 7 detects that the pre-charging current is less than the preset current threshold, then step S3 is executed.

[0014] Preferably, in step S2, the gate voltage is greater than or equal to 15V to ensure that the field-effect transistor 2 is turned on quickly and stably.

[0015] This application further proposes a vehicle that includes the aforementioned high-voltage bus pre-charging circuit system for new energy vehicles.

[0016] The technical effects of this invention are as follows: 1. This invention not only effectively controls the charging current of the high-voltage bus capacitor, reduces stress on electrical components, and improves system safety, but also enhances the starting efficiency of new energy vehicles to a certain extent. Furthermore, by eliminating the need for a pre-charge relay, it also reduces vehicle costs.

[0017] 2. Compared with the traditional pre-charging circuit, the mechanical relay in the traditional pre-charging circuit is replaced by a solid-state relay composed of an isolation controller and a field-effect transistor. Since the solid-state relay is smaller in size, the size of the pre-charging circuit is reduced, thus reducing the complexity of the system.

[0018] 3. Adding a shunt comparator to the system can quickly provide feedback on precharge circuit faults and directly feed them back to the isolation controller to control the switching of the field-effect transistor. Attached Figure Description

[0019] Figure 1 A circuit diagram of a high-voltage bus pre-charging circuit system for new energy vehicles is provided for an embodiment of the present invention; Figure 2 A flowchart of a high-voltage bus pre-charging method for new energy vehicles provided in an embodiment of the present invention; Figure 1 The reference numerals in the attached diagram are as follows: 1. Power battery; 2. Field-effect transistor; 3. Main positive relay; 4. Precharge resistor; 5. Single-phase conductor; 6. Load capacitor; 7. Comparator; 8. Isolation controller; 9. Main negative relay; 10. Comparator feedback terminal; 11. Comparator bias power supply. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. This is to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solutions of the present invention, and to facilitate its implementation. It should be noted that the terms "first," "second," etc., used in this application are only for the convenience of describing the technical solutions and to distinguish components; the corresponding component configurations may be the same or different, and are not intended to limit the scope of this application. To make the technical solutions of the present invention clearer, the present invention will be explained and illustrated through the following embodiments.

[0021] This embodiment provides a high-voltage bus pre-charging circuit system for new energy vehicles, such as... Figure 1 As shown, the system includes a series main circuit consisting of the positive terminal of the power battery 1, a main positive relay 3, a load capacitor 6, a main negative relay 9, and the negative terminal of the power battery 1, as well as a battery management system. This embodiment also includes a pre-charging circuit, which includes a pre-charging resistor 4, a unidirectional conductor 5, and a solid-state relay consisting of an isolation controller 8 and a field-effect transistor 2 (FET). The solid-state relay is connected in parallel across the main positive relay 3 after being connected in series with the pre-charging resistor 4 and the unidirectional conductor 5. The battery management system is connected to the main positive relay 3, the main negative relay 9, and the isolation controller 8, respectively, and is used to control the switching of the main positive relay 3 and the main negative relay 9, as well as to activate or deactivate the isolation controller 8.

[0022] This embodiment replaces the traditional mechanical relay with a solid-state relay composed of an isolation controller 8 and a field-effect transistor 2. Utilizing the fast switching and longer lifespan of the field-effect transistor 2 in the solid-state relay, the charging current of the load capacitor 6 is effectively limited, thereby improving system safety and stability and reducing costs. Simultaneously, the switching action time of the field-effect transistor 2 is also faster than that of a traditional mechanical relay, improving the pre-charge speed and meeting the requirements of high-dynamic scenarios.

[0023] Specifically, for the solid-state relay in this embodiment, the first terminal of the field-effect transistor 2 is connected to the first terminal of the main positive relay 3, and the second terminal of the field-effect transistor 2 is connected to the second terminal of the main positive relay 3 after being connected in series with the pre-charge resistor 4 and the unidirectional conduction device 5. The control terminal of the field-effect transistor 2 is connected to the isolation controller 8; the isolation controller 8 is connected to the battery management system. The unidirectional conduction device 5 is a diode. If the field-effect transistor 2 used is an N-channel type, the first terminal of the field-effect transistor 2 is the drain, the second terminal is the source, the control terminal is the gate, and the gate control voltage is a positive voltage. If the field-effect transistor 2 used is a P-channel type, the first terminal of the field-effect transistor 2 is the source, the second terminal is the drain, the control terminal is the gate, and the gate control voltage is a negative voltage. The appropriate type can be flexibly selected according to actual needs during implementation.

[0024] In this embodiment, the isolation controller 8 uses a microcontroller (MCU), which has the advantages of small size and high integration, facilitating system deployment and reducing costs. When pre-charging is required, the isolation controller 8 outputs a stable gate voltage to the gate of the field-effect transistor 2, thereby reliably driving the field-effect transistor 2 to conduct. At this time, the power battery 1 can charge the load capacitor 6 through the pre-charging resistor 4. After pre-charging is completed, the isolation controller 8 stops outputting the gate voltage, thus quickly turning off the field-effect transistor 2 and ending the pre-charging process.

[0025] Meanwhile, to ensure the pre-charge current remains within a safe range and to prevent excessive pre-charge current from damaging the system, this embodiment also includes a shunt comparator 7 in the pre-charge circuit. Specifically, the pre-charge resistor 4 is connected in parallel between the non-inverting and inverting input terminals of the shunt comparator 7. The positive power supply terminal of the shunt comparator 7 is connected to the isolation controller 8, and the negative power supply terminal of the shunt comparator 7 is grounded. The isolation controller 8 outputs a comparator bias power supply 11 to power the shunt comparator 7. The feedback terminal 10 of the shunt comparator 7 is connected to the isolation controller 8, thereby providing feedback on the state of the pre-charge resistor 4 to the isolation controller 8 through the comparator feedback terminal 10. During operation, the shunt built into the shunt comparator 7 continuously samples the voltage drop across the pre-charge resistor 4 to obtain the pre-charge current. After processing by the comparator 7, the comparison result is input to the isolation controller 8 through the feedback terminal 10. When the pre-charge current exceeds a preset current threshold, the comparator feedback terminal 10 enables the isolation controller 8 to immediately turn off the field-effect transistor 2 to prevent damage to the pre-charge resistor 4 or the field-effect transistor 2 due to abnormal conditions.

[0026] For example, the shunt comparator 7 in this embodiment is model AD8214. In addition to the built-in shunt, it also integrates a 2.4V regulator. The user can set the comparator threshold voltage as needed through an external resistor. The AD8214 then compares the voltage across the shunt resistor with the comparator threshold voltage and outputs the comparison result. The use of the shunt comparator 7 allows the pre-charge process to be terminated in a very short time to protect the pre-charge circuit in the event of a fault.

[0027] In summary, the high-voltage bus pre-charging system for new energy vehicles with solid-state relays provided in this embodiment realizes the function of mechanical relays by controlling the field-effect transistors 2 through the isolation controller 8. At the same time, in conjunction with the comparator 7 to collect the state in the pre-charging circuit, it achieves precise limitation of charging current, improves the safety and stability of the electrical system of new energy vehicles, and has significant technological progress and practical application value.

[0028] Correspondingly, this embodiment also proposes a pre-charging method for high-voltage busbars of new energy vehicles, using the aforementioned pre-charging circuit system for high-voltage busbars of new energy vehicles, such as... Figure 2 As shown, the method includes the following steps: Step S1: The battery management system receives the high-voltage system power-on command, controls the main negative relay 9 to close, and then activates the isolation controller 8 to prepare for the pre-charge process.

[0029] Step S2: After the isolation controller 8 is activated, it outputs a gate voltage to the field-effect transistor 2, causing the field-effect transistor 2 to turn on and begin pre-charging. In this embodiment, the gate voltage output by the isolation controller 8 after activation is not lower than 15V, ensuring that the field-effect transistor 2 turns on quickly and stably, thereby allowing the pre-charging current to pass through to charge the load capacitor 6.

[0030] Simultaneously, after pre-charging begins, the shunt comparator 7 collects the voltage drop across the pre-charging resistor 4 in real time through its built-in shunt to obtain the pre-charging current, and compares it with the preset current threshold in the comparator 7 to ensure that the current fluctuates within the specified safe range. If the comparator 7 detects that the pre-charging current is greater than or equal to the preset current threshold, it is considered that the pre-charging current is abnormal. At this time, the comparator 7 outputs an abnormal signal through the feedback terminal 10 to enable the isolation controller 8 and then jumps to step S5; if the comparator 7 detects that the pre-charging current is less than the preset current threshold, it continues to execute step S3.

[0031] Step S3: Within the set pre-charge time window, the battery management system continuously monitors the high-voltage bus voltage to determine whether it has reached a preset voltage threshold, ensuring the smooth completion of the pre-charge process. This voltage threshold is close to the output voltage of the power battery 1, thereby reducing the difference between the output voltage of the power battery 1 and the load voltage after closing the main positive relay 3 after pre-charge is completed, avoiding the impact of instantaneous large current on electrical components. If the high-voltage bus voltage reaches the preset voltage threshold within the set pre-charge time window, step S4 is executed; otherwise, a pre-charge fault is considered to have occurred, and step S5 is executed.

[0032] Step S4: The battery management system controls the main positive relay 3 to close and shuts down the isolation controller 8. Correspondingly, the isolation controller 8 stops outputting the gate voltage, causing the field-effect transistor 2 to turn off. At the same time, the isolation controller 8 enters a low-power sleep state, thus completing the pre-charge process.

[0033] In step S5, the isolation controller 8 stops outputting the gate voltage within less than 1ms, causing the field-effect transistor 2 to turn off rapidly. At the same time, the battery management system exits the pre-charge process and reports a pre-charge fault.

[0034] This embodiment also provides a vehicle, which includes the above-described high-voltage bus pre-charging circuit system for new energy vehicles.

[0035] Based on the above embodiments, the advantages and effects of the present invention are as follows: 1. This invention not only effectively controls the charging current of the high-voltage bus capacitor, reduces stress on electrical components, and improves system safety, but also enhances the starting efficiency of new energy vehicles to a certain extent. Furthermore, by eliminating the need for a pre-charge relay, it also reduces vehicle costs.

[0036] 2. Compared with the traditional pre-charging circuit, the mechanical relay in the traditional pre-charging circuit is replaced by a solid-state relay composed of an isolation controller and a field-effect transistor. Since the solid-state relay is smaller in size, the size of the pre-charging circuit is reduced, thus reducing the complexity of the system.

[0037] 3. Adding a shunt comparator to the system can quickly provide feedback on precharge circuit faults and directly feed them back to the isolation controller to control the switching of the field-effect transistor.

[0038] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A high-voltage bus pre-charging circuit system for new energy vehicles, comprising a series main circuit consisting of a positive terminal of a power battery (1), a main positive relay (3), a load capacitor (6), a main negative relay (9), and a negative terminal of the power battery (1), and a battery management system, characterized in that: The system also includes a pre-charging circuit, which includes a pre-charging resistor (4), a unidirectional conductor (5), and a solid-state relay consisting of an isolation controller (8) and a field-effect transistor (2). The solid-state relay is connected in parallel across the main positive relay (3) after being connected in series with the pre-charging resistor (4) and the unidirectional conductor (5).

2. The high-voltage bus pre-charging circuit system for new energy vehicles according to claim 1, characterized in that: The first terminal of the field-effect transistor (2) is connected to the first terminal of the main positive relay (3). The second terminal of the field-effect transistor (2) is connected in series with the pre-charge resistor (4) and the single-phase conduction device (5) and then connected to the second terminal of the main positive relay (3). The control terminal of the field-effect transistor (2) is connected to the isolation controller (8). The isolation controller (8) is connected to the battery management system.

3. A pre-charging circuit system for a high-voltage busbar of a new energy vehicle according to claim 1 or 2, characterized in that: The pre-charging circuit also includes a shunt comparator (7), and the pre-charging resistor (4) is connected in parallel between the positive input terminal and the negative input terminal of the shunt comparator (7); the positive power supply terminal of the shunt comparator (7) is connected to the isolation controller (8), the negative power supply terminal of the shunt comparator (7) is grounded, and the feedback terminal (10) of the shunt comparator (7) is connected to the isolation controller (8).

4. The high-voltage bus pre-charging circuit system for new energy vehicles according to claim 3, characterized in that: The shunt comparator (7) is model AD8214.

5. A pre-charging circuit system for a high-voltage busbar of a new energy vehicle according to claim 1, characterized in that: The field-effect transistor (2) is of type N. Correspondingly, the first terminal of the field-effect transistor (2) is the drain, the second terminal is the source, the control terminal is the gate, and the gate control voltage is a positive voltage.

6. The high-voltage bus pre-charging circuit system for new energy vehicles according to claim 1, characterized in that: The field-effect transistor (2) is P-type. Correspondingly, the first terminal of the field-effect transistor (2) is the source, the second terminal is the drain, the control terminal is the gate, and the gate control voltage is a negative voltage.

7. A method for pre-charging a high-voltage busbar of a new energy vehicle, using a high-voltage busbar pre-charging circuit system for a new energy vehicle according to any one of claims 1-6, characterized in that: The method includes: Step S1: The battery management system receives the power-on command of the high-voltage system, controls the main negative relay (9) to close and activates the isolation controller (8). Step S2: After the isolation controller (8) is activated, it outputs the gate voltage to the field-effect transistor (2), so that the field-effect transistor (2) is turned on and begins pre-charging; Step S3: Within the set pre-charge time window, the battery management system continuously monitors the high-voltage bus voltage and determines whether it has reached the preset voltage threshold. If it has, proceed to step S4; otherwise, proceed to step S5. Step S4: The battery management system controls the main positive relay (3) to close and shuts down the isolation controller (8). Correspondingly, the isolation controller (8) stops outputting the gate voltage, causing the field-effect transistor (2) to turn off. At the same time, the isolation controller (8) enters the sleep state, thus completing the pre-charge process. Step S5: The isolation controller (8) stops outputting the gate voltage, causing the field-effect transistor (2) to turn off. At the same time, the battery management system exits the pre-charge process and reports a pre-charge fault.

8. The method for pre-charging a high-voltage busbar of a new energy vehicle according to claim 7, characterized in that: Step S2 further includes: after the pre-charging starts, the comparator (7) collects the voltage drop on the pre-charging resistor (4) in real time to obtain the pre-charging current and compares it with the preset current threshold in the comparator (7). If the comparator (7) detects that the pre-charging current is greater than or equal to the preset current threshold, the comparator (7) outputs an abnormal signal through the feedback terminal (10) to enable the isolation controller (8) and then jumps to step S5; if the comparator (7) detects that the pre-charging current is less than the preset current threshold, then step S3 continues to be executed.

9. A pre-charging method for a high-voltage busbar of a new energy vehicle according to claim 7 or 8, characterized in that: In step S2, the gate voltage is greater than or equal to 15V to ensure that the field-effect transistor (2) turns on quickly and stably.

10. A vehicle, characterized in that: The vehicle includes a high-voltage bus pre-charging circuit system for new energy vehicles according to any one of claims 1-6.

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