High voltage pre-charge circuit and method

Abstract

The application discloses a high-voltage pre-charging circuit and method, which comprises a pre-charging driving module, a pre-charging current detection module and a whole vehicle control module; the pre-charging driving module is connected with the whole vehicle control module and a power battery respectively, and the pre-charging current detection module is connected with the pre-charging driving module and the whole vehicle control module respectively. In the application, the current pre-charging current is collected, and when the current pre-charging current is not equal to a preset current, the current pre-charging current is adjusted to the preset current, so that the pre-charging process is pre-charged with the constant preset current, thereby reducing the pre-charging time of the vehicle battery and improving the user experience.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a high-voltage pre-charging circuit and method. Background Technology

[0002] With the popularization of electric vehicles, electric vehicles are becoming more and more common in daily life. The traditional electric vehicle pre-charging circuit uses a pre-charging resistor and a pre-charging relay. The power battery is used as the power source. When the pre-charging relay is closed, the current is limited by the pre-charging resistor to charge the capacitor on the high-voltage device bus. The pre-charging is completed when the voltage on the bus capacitor reaches 98% or more of the battery bus voltage.

[0003] The traditional control scheme described above takes about 800ms-1000ms to complete pre-charging. With signal filtering and signal confirmation, it takes about 1000ms, resulting in a long waiting time for the vehicle to prepare after the customer presses the start button, which affects the customer experience.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this invention is to provide a high-voltage pre-charging circuit and method, which aims to solve the technical problem of excessively long pre-charging time for vehicle batteries in the prior art.

[0006] To achieve the above objectives, the present invention proposes a high-voltage pre-charging circuit, which includes: a pre-charging drive module, a pre-charging current detection module, and a vehicle control module;

[0007] The pre-charge drive module is connected to the vehicle control module and the power battery, respectively, and the pre-charge current detection module is connected to the pre-charge drive module and the vehicle control module, respectively.

[0008] The pre-charge current detection module is used to detect the current pre-charge current during the pre-charge process of the power battery and send the current pre-charge current to the vehicle control module.

[0009] The vehicle control module is used to adjust the duty cycle of the PWM pulse signal according to the current pre-charge current when the current pre-charge current is not equal to the preset current, and output the adjusted PWM pulse signal to the pre-charge drive module.

[0010] The precharge drive module is used to adjust the current precharge current to the preset current according to the adjusted PWM pulse signal.

[0011] Optionally, the precharge drive module includes: a precharge relay, a first inductor, a first MOSFET, and a first diode;

[0012] The first terminal of the precharge relay is connected to the relay drive pin of the vehicle control module, the second terminal of the precharge relay is connected to the positive terminal of the precharge battery, and the third terminal of the precharge relay is connected to the first terminal of the first inductor.

[0013] The second terminal of the first inductor is connected to the drain of the first MOSFET and the anode of the first diode, respectively.

[0014] The gate of the first MOSFET is connected to the PWM pulse pin of the vehicle control module, and the output of the first MOSFET is connected to the negative terminal of the precharged battery.

[0015] The negative terminal of the first diode is connected to the positive terminal of the power battery.

[0016] Optionally, the pre-charge current detection module includes: first to fifth resistors, an operational amplifier, and a first capacitor;

[0017] Wherein, the first end of the first resistor is connected to the source of the first MOS transistor and the first end of the second resistor, and the second end of the first resistor is connected to the first end of the third resistor and the second end of the bus capacitor.

[0018] The second end of the second resistor is connected to the negative input of the operational amplifier and the first end of the fourth resistor. The second end of the third resistor is connected to the positive input of the operational amplifier. The output of the operational amplifier is connected to the second end of the fourth resistor and the first end of the fifth resistor. The second end of the fifth resistor is connected to the first end of the first capacitor and the current detection pin of the vehicle control module. The second end of the first capacitor is grounded.

[0019] Optionally, the high-voltage pre-charge circuit further includes: a capacitor voltage detection module;

[0020] The capacitor voltage detection module is connected to the vehicle control module and the bus capacitor located between the pre-charge drive module and the power battery.

[0021] The capacitor voltage detection module is used to detect the capacitor voltage across the bus capacitor during the pre-charging process of the power battery, and output the capacitor voltage to the vehicle control module.

[0022] The vehicle control module is also used to output a cutoff signal to the pre-charge drive module when the capacitor voltage is greater than or equal to a preset voltage value;

[0023] The precharge drive module is also used to stop outputting the preset current when it receives the cutoff signal.

[0024] Optionally, the capacitor voltage detection module includes: an optocoupler, a sixth resistor, a seventh resistor, and a second capacitor;

[0025] In this configuration, the second capacitor is connected in parallel with the bus capacitor. The first end of the optocoupler is connected to the positive terminal of the precharged battery. The second end of the optocoupler is connected to the optocoupler control pin of the vehicle control module. The third end of the optocoupler is connected to the precharge drive module and the first end of the second capacitor. The fourth end of the optocoupler is connected to the first end of the seventh resistor. The second end of the seventh resistor is connected to the voltage detection pin of the vehicle control module and the first end of the sixth resistor. The second end of the sixth resistor is connected to the second end of the second capacitor and the negative terminal of the precharged battery.

[0026] Optionally, the high-voltage pre-charge circuit further includes: a battery voltage detection module and a CAN communication module;

[0027] The battery voltage detection module is connected to the power battery and the vehicle control module respectively.

[0028] The battery voltage detection module is used to detect the bus voltage of the bus to be connected to the power battery when a pre-charge command is received, and send the bus voltage to the vehicle control module through the CAN communication module.

[0029] The vehicle control module is also used to output a drive signal to the precharge drive module when it receives the battery terminal bus voltage;

[0030] The pre-charge drive module is also used to output a preset current to charge the power battery when it receives the drive signal.

[0031] Optionally, the battery voltage detection module includes: a battery management chip, a main positive relay, and a main negative relay;

[0032] The first pin of the battery management chip is connected to the first terminal of the bus capacitor and the first terminal of the main positive relay, and the second pin of the battery management chip is connected to the second terminal of the bus capacitor and the first terminal of the main negative relay.

[0033] The third terminal of the battery management chip is connected to the positive terminal of the power battery and the second terminal of the main positive relay, and the fourth terminal of the battery management chip is connected to the negative terminal of the power battery and the second terminal of the main negative relay.

[0034] The fifth terminal of the battery management chip is connected to the vehicle control module via the CAN communication module.

[0035] To achieve the above objectives, the present invention also proposes a high-voltage pre-charging method, the high-voltage pre-charging method comprising:

[0036] Detect the current pre-charge current during the pre-charge process of the power battery;

[0037] When the current pre-charge current is not equal to the preset current, the duty cycle of the PWM pulse signal is adjusted according to the current pre-charge current;

[0038] The current pre-charge current is adjusted to the preset current based on the PWM pulse signal after the duty cycle adjustment.

[0039] Optionally, before the step of detecting the current pre-charge current during the pre-charge process of the power battery, the method further includes:

[0040] Upon receiving a pre-charge command, the bus voltage of the power battery to be connected is detected;

[0041] When the battery terminal bus voltage is received, the pre-charged battery is driven to output a preset current to charge the power battery.

[0042] Optionally, after the step of adjusting the current value of the current pre-charge current to the preset current value according to the PWM pulse signal adjusted by the duty cycle, the method further includes:

[0043] Detect the capacitor voltage across the bus capacitor;

[0044] When the capacitor voltage is greater than a preset voltage, the pre-charge battery output pre-charge current is stopped.

[0045] This invention provides a high-voltage pre-charging circuit and method. The high-voltage pre-charging circuit includes a pre-charging drive module, a pre-charging current detection module, and a vehicle control module. The pre-charging drive module is connected to both the vehicle control module and the power battery. The pre-charging current detection module is connected to both the pre-charging drive module and the vehicle control module. The pre-charging current detection module detects the current pre-charging current during the pre-charging process of the power battery and sends the current pre-charging current to the vehicle control module. The vehicle control module adjusts the duty cycle of a PWM pulse signal according to the current pre-charging current when it is not equal to a preset current, and outputs the adjusted PWM pulse signal to the pre-charging drive module. The pre-charging drive module adjusts the current pre-charging current to the preset current according to the adjusted PWM pulse signal. In this invention, by acquiring the current pre-charging current and adjusting it to the preset current when it is not equal to the preset current, the pre-charging process is performed with a constant preset current, thereby reducing the pre-charging time of the vehicle battery and improving the user experience. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the structure of the first embodiment of the high-voltage pre-charging circuit proposed in this invention;

[0048] Figure 2 This is a schematic diagram of the structure of a high-voltage pre-charging circuit in the prior art;

[0049] Figure 3 This is a circuit diagram of the precharge drive module of the second embodiment of the high-voltage precharge circuit proposed in this invention.

[0050] Figure 4 This is a circuit diagram of the pre-charge current detection module in the second embodiment of the high-voltage pre-charge circuit proposed in this invention.

[0051] Figure 5 This is a circuit diagram of the capacitor voltage detection module in the second embodiment of the high-voltage pre-charging circuit proposed in this invention.

[0052] Figure 6 This is a circuit diagram of the battery voltage detection module in the second embodiment of the high-voltage pre-charging circuit proposed in this invention.

[0053] Figure 7 This is a circuit diagram of the second embodiment of the high-voltage pre-charging circuit proposed in this invention;

[0054] Figure 8 This is a flowchart illustrating the first embodiment of the high-voltage pre-charging method proposed in this invention.

[0055] Figure 9 This is a schematic flowchart of the second embodiment of the high-voltage pre-charging method proposed in this invention.

[0056] Explanation of icon numbers:

[0057] label name label name 10 Precharge driver module 20 Precharge current detection module 30 Vehicle control module K1 Precharge relay K2 Main positive relay K3 Main negative relay V Battery voltage Q1 First MOSFET Q2 optocoupler R1~R7 Resistors 1 to 7 U1 operational amplifier BMS Battery management chip C1~C3 First to third capacitors GND Grounding

[0058] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0059] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0061] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0062] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, the user should consider such a combination of technical solutions to be non-existent and not within the scope of protection claimed by this invention.

[0063] Reference Figure 1 , Figure 1 This is a schematic diagram of the first embodiment of the high-voltage pre-charging circuit proposed in this invention. Based on Figure 1 The first embodiment of the high-voltage pre-charging circuit of the present invention is presented.

[0064] In this embodiment, the high-voltage pre-charging circuit includes: a pre-charging drive module 10, a pre-charging current detection module 20, and a vehicle control module 30;

[0065] The pre-charge drive module 10 is connected to the vehicle control module 30 and the power battery, respectively, and the pre-charge current detection module 20 is connected to the pre-charge drive module 10 and the vehicle control module 30, respectively.

[0066] It should be understood that, during battery charging, to prevent the current surge caused by the instantaneous high-voltage power-on from affecting the vehicle's power battery, a pre-charging process is performed before the main power battery is charged. (Refer to...) Figure 2 During the pre-charging process, a pre-charging resistor and a pre-charging relay are typically used. Taking a commonly used 400V platform battery system with a high-voltage bus capacitor totaling 2000uF and a 100-ohm pre-charging resistor as an example, in... Figure 2In this case, the pre-charging time of the pre-charging resistor is T1 = 4RC = 0.8S. In addition, due to the resistance characteristics, the resistance value of the pre-charging resistor will gradually increase during the pre-charging process, which will cause the pre-charging current to gradually decrease, further increasing the pre-charging time.

[0067] It should be noted that the precharge drive module 10 is a drive module used to drive the precharge battery to precharge the power battery. This precharge drive module 10 can control the output precharge current by setting the conduction state of the internal switching transistor. The precharge current detection module 20 is a module used to detect the precharge current during the power battery precharge process. Since the precharge current may change during the power battery precharge process, the precharge current detection module 10 can detect the precharge current in real time or at certain intervals. The vehicle control module 30 can be a vehicle controller, which can control the precharge process of the power battery.

[0068] During the pre-charging process, the pre-charging current detection module 20 can detect the current pre-charging current of the power battery and send the current pre-charging current to the vehicle control module 30. When the current pre-charging current is not equal to the preset current, the vehicle control module 30 can adjust the duty cycle of the PWM pulse signal according to the current pre-charging current and output the adjusted PWM pulse signal to the pre-charging drive module 10. The pre-charging drive module 30 can adjust the current pre-charging current to the preset current according to the adjusted PWM pulse signal.

[0069] The current precharge current is the precharge current detected by the precharge current detection module 20 at the current detection time point. This preset current is a pre-set charging current output by the precharge battery with a constant current value. The current value of this precharge current can be the maximum current value or a current value within a certain range below the maximum current value, such as 6A. The PWM pulse signal is the signal used by the precharge drive module 10 to control the output duration of the precharge battery. The duty cycle of this PWM pulse signal is related to the output duration of the precharge battery. It can be understood that within a complete cycle, the longer the output duration of the precharge battery, the larger the corresponding precharge current value. When the precharge current changes, the output time of the precharge battery can be adjusted by regulating the duty cycle of the PWM pulse signal, thereby maintaining a constant precharge current value.

[0070] Understandably, taking a commonly used 400V platform battery system with a total high-voltage bus capacitor value of 2000uF and a preset current of 6A as an example, the time for the power battery to be precharged by this preset current is T2=U*C / I=0.13S. Compared with the precharging method of precharging resistor and precharging relay, the precharging time of the power battery can be reduced when the power battery is precharged with a preset current of constant current value.

[0071] This embodiment provides a high-voltage pre-charging circuit, which includes a pre-charging drive module, a pre-charging current detection module, and a vehicle control module. The pre-charging drive module is connected to both the vehicle control module and the power battery, and the pre-charging current detection module is connected to both the pre-charging drive module and the vehicle control module. The pre-charging current detection module detects the current pre-charging current during the pre-charging process of the power battery and sends the current pre-charging current to the vehicle control module. The vehicle control module adjusts the duty cycle of a PWM pulse signal according to the current pre-charging current when it is not equal to a preset current, and outputs the adjusted PWM pulse signal to the pre-charging drive module. The pre-charging drive module adjusts the current pre-charging current to the preset current according to the adjusted PWM pulse signal. In this invention, by acquiring the current pre-charging current and adjusting it to the preset current when it is not equal to the preset current, the pre-charging process is performed with a constant preset current, thereby reducing the pre-charging time of the vehicle battery and improving the user experience.

[0072] Based on the first embodiment of the high-voltage pre-charging circuit described above, a second embodiment of the high-voltage pre-charging circuit of the present invention is proposed.

[0073] Reference Figure 3 In this embodiment, the precharge drive module includes: a precharge relay K1, a first inductor L1, a first MOSFET Q1, and a first diode D1;

[0074] The first terminal of the precharge relay K1 is connected to the relay drive pin of the vehicle control module 30, the second terminal of the precharge relay K1 is connected to the positive terminal of the precharge battery, and the third terminal of the precharge relay K1 is connected to the first terminal of the first inductor L1.

[0075] The second terminal of the first inductor L1 is connected to the drain of the first MOS transistor Q1 and the anode of the first diode D1, respectively.

[0076] The gate of the first MOSFET Q1 is connected to the PWM pulse pin of the vehicle control module 30, and the output terminal of the first MOSFET Q1 is connected to the negative terminal of the precharged battery.

[0077] The negative terminal of the first diode D1 is connected to the positive terminal of the power battery.

[0078] It should be noted that the pre-charge relay K1 is used to control whether the connection between the pre-charge battery and the power battery is conductive. The vehicle control module 30 can directly control the start and stop of pre-charging by controlling the conduction or cutoff of the pre-charge relay K1. The first inductor L1 is used to boost the battery voltage V output by the pre-charge battery. The first inductor L1 can form a boost circuit with the first MOSFET Q1. The pre-charge battery can be the low-voltage battery in the vehicle. The battery voltage V output by the low-voltage battery can be boosted by the boost circuit composed of the first inductor L1 and the first MOSFET. When the pre-charge relay K1 is closed, the low-voltage battery is controlled to charge the first inductor L1 by controlling the first MOSFET Q1 to conduct; conversely, the voltage stored in the first inductor L1 can be output by controlling the first MOSFET Q1 to pre-charge the power battery.

[0079] Among them, the first diode D1 can be a Schottky diode. The setting of the first diode D1 can effectively prevent the voltage on the power battery from flowing back into the low-voltage pre-charged battery.

[0080] In specific implementation, the vehicle control module 30 can output a low-level signal to the pre-charge relay K1 via the relay drive pin. At this time, the coil of the pre-charge relay K1 is turned on, and the contacts close. The pre-charge battery can output the battery voltage V to the first inductor L1 through the contacts. The vehicle control module 30 outputs a PWM pulse signal to the gate of the first MOSFET Q1. During the effective duty cycle of the PWM pulse signal, the pre-charge battery charges the first inductor L1; during the ineffective duty cycle of the PWM pulse signal, the first inductor L1 outputs a preset current to charge the power battery through the first diode D1.

[0081] Furthermore, the pre-charge current detection module 20, as shown in the figure, includes: first to fifth resistors, operational amplifier U1, and first capacitor C1;

[0082] Wherein, the first end of the first resistor R1 is connected to the source of the first MOS transistor Q1 and the first end of the second resistor R2, and the second end of the first resistor R1 is connected to the first end of the third resistor R3 and the second end of the bus capacitor C3.

[0083] The second end of the second resistor R2 is connected to the negative input of the operational amplifier U1 and the first end of the fourth resistor R4. The second end of the third resistor R3 is connected to the positive input of the operational amplifier U1. The output of the operational amplifier U1 is connected to the second end of the fourth resistor R4 and the first end of the fifth resistor R5. The second end of the fifth resistor R5 is connected to the first end of the first capacitor C1 and the current detection pin of the vehicle control module 30. The second end of the first capacitor C1 is grounded to GND.

[0084] It should be understood that the first resistor R1 is a sampling resistor, and the current pre-charge current in the pre-charge state can be obtained by acquiring the voltage value across the first resistor R1. Operational amplifier U1, together with the second resistor R2, the third resistor R3, and the fourth resistor R4, forms a differential operational amplifier circuit. This differential operational amplifier circuit can differentially amplify the current pre-charge current passing through the first resistor R1. The fifth resistor R5 and the first capacitor C1 can form a low-pass filter circuit. The current pre-charge current, after differential amplification, can also pass through this low-pass filter circuit to filter out noise, thus ensuring an accurate current pre-charge current input to the vehicle control module 30.

[0085] It should be noted that since the signal received by the vehicle control module 30 is usually a voltage signal, the current through the first resistor R1 can be converted into a corresponding voltage signal by the differential operational amplifier circuit and the low-pass filter circuit, and then input to the vehicle control module.

[0086] In addition, this embodiment also includes a voltage conversion module, which can convert the battery voltage of the precharged battery into a negative voltage of the corresponding voltage value, and use the negative voltage to power the negative voltage terminal of the operational amplifier U1. The positive voltage terminal of the operational amplifier U1 can be directly powered by the precharged battery.

[0087] In this embodiment, the high-voltage pre-charging circuit further includes: a capacitor voltage detection module;

[0088] The capacitor voltage detection module is connected to the vehicle control module 30 and the bus capacitor C3 located between the precharge drive module 10 and the power battery.

[0089] It should be understood that during the pre-charging process of the power battery, it is also necessary to determine in real time whether the power battery has completed pre-charging to avoid wasting resources by continuing pre-charging after it has been completed. Therefore, in this embodiment, a capacitor voltage detection module can also be set up. This module can obtain the voltage across the power battery by detecting the voltage across the bus capacitor C3 connected in parallel with the power battery, thereby determining whether the power battery has completed pre-charging.

[0090] In a specific implementation, the capacitor voltage detection module can detect the capacitor voltage across the bus capacitor C3 in real time during the pre-charging process of the power battery, and output the capacitor voltage to the vehicle control module 30; the vehicle control module 30 can output a cut-off signal to the pre-charging drive module 10 when the capacitor voltage is greater than or equal to a preset voltage value; the pre-charging relay K1 in the pre-charging drive module 10 can disconnect its contacts when it receives the cut-off signal, thereby stopping the output of the preset current to the power battery.

[0091] The preset voltage value is a pre-set voltage used to determine whether the pre-charging process of the power battery is complete. The cut-off signal is a signal that controls the pre-charging drive module 10 to disconnect the connection between the pre-charging battery and the power battery, stopping the pre-charging of the power battery. In this embodiment, the cut-off signal can be a high-level signal.

[0092] Reference Figure 5 In this embodiment, the capacitor voltage detection module includes: an optocoupler Q2, a sixth resistor R6, a seventh resistor R7, and a second capacitor C2;

[0093] In this configuration, the second capacitor C2 is connected in parallel with the bus capacitor C3. The first end of the optocoupler Q2 is connected to the positive terminal of the precharged battery. The second end of the optocoupler Q2 is connected to the optocoupler control pin of the vehicle control module 30. The third end of the optocoupler Q2 is connected to the precharge drive module 10 and the first end of the second capacitor C2. The fourth end of the optocoupler Q2 is connected to the first end of the seventh resistor R7. The second end of the seventh resistor R7 is connected to the voltage detection pin of the vehicle control module 30 and the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the second end of the second capacitor C2 and the negative terminal of the precharged battery.

[0094] exist Figure 5 In this configuration, the sixth resistor R6 and the seventh resistor R4 can be used as sampling resistors. The sixth resistor R6 and the seventh resistor R7 are connected in parallel with the second capacitor C2 and the bus capacitor C3. When the optocoupler Q2 is turned on, the voltage value at the midpoint between the sixth resistor R6 and the seventh resistor R7 can be input to the vehicle control module 30, thereby detecting the voltage across the bus capacitor C3.

[0095] In a specific implementation, the vehicle control module 30 can output a low-level signal to the second terminal of the optocoupler Q2 through the optocoupler control pin. At this time, the first and second terminals of the optocoupler Q2 are connected, and the third and fourth terminals are connected, connecting the sixth resistor R6 and the seventh resistor R7 in parallel across the bus capacitor C3 and the second capacitor C2. The capacitor voltage across the bus capacitor C3 can be input to the voltage detection pin of the vehicle control module 30 through the second terminal of the seventh resistor R7. The vehicle control module 30 can compare the received capacitor voltage with the preset voltage value and determine whether the power battery has been pre-charged based on the comparison result.

[0096] In this embodiment, the high-voltage pre-charging circuit further includes: a battery voltage detection module and a CAN communication module;

[0097] The battery voltage detection module is connected to both the power battery and the vehicle control module 30.

[0098] In this embodiment, before the vehicle control module 30 outputs a low-level signal to control the pre-charge relay K1 to close, it also needs to confirm whether the connection of the power battery is complete. For example, if the relay at the power battery end is not closed, even if the pre-charge relay K1 is closed, the power battery cannot be pre-charged.

[0099] Therefore, in this embodiment, a battery voltage detection module and a CAN communication module are also provided. The battery voltage detection module can detect the bus voltage connected to the power battery. When the bus voltage is detected, it can be determined that the relay used to connect the bus and the power battery is closed, and the pre-charging step can be performed.

[0100] In specific implementation, the vehicle control module 30 can output a pre-charge command to the battery voltage detection module. Upon receiving the pre-charge command, the battery voltage detection module detects the bus voltage of the bus to be connected to the power battery and sends the bus voltage to the vehicle control module 30 via the CAN communication module. When the vehicle control module 30 receives the battery bus voltage, it outputs a drive signal to the pre-charge drive module 10. Upon receiving the drive signal, the pre-charge drive module 10 can output a preset current to charge the power battery. If the vehicle control module 30 does not receive the battery bus voltage, it indicates that the power battery has not completed pre-charge preparation, and the vehicle control module 30 will temporarily not output a drive signal to the pre-charge drive module 10.

[0101] Reference Figure 6 The battery voltage detection module includes: a battery management chip (BMS), a main positive relay (K2), and a main negative relay (K3);

[0102] The first pin of the battery management chip BMS is connected to the first terminal of the bus capacitor C3 and the first terminal of the main positive relay K2, and the second pin of the battery management chip BMS is connected to the second terminal of the bus capacitor C3 and the first terminal of the main negative relay K3.

[0103] The third terminal of the battery management chip (BMS) is connected to the positive terminal of the power battery and the second terminal of the main positive relay K2, and the fourth terminal of the battery management chip (BMS) is connected to the negative terminal of the power battery and the second terminal of the main negative relay K3.

[0104] The fifth terminal of the battery management chip (BMS) is connected to the vehicle control module 30 via the CAN communication module.

[0105] It should be understood that the Battery Management System (BMS) chip is used to regulate the charging and discharging process of the power battery. In this embodiment, the BMS chip can collect parameters such as the bus voltage and battery voltage at the power battery terminal. The main negative relay K2 is used to establish a connection between the bus and the power battery when pre-charging begins. The main positive relay K3 is used to close after pre-charging is completed, thereby controlling the end of the pre-charging process.

[0106] Reference Figure 7 In this embodiment, the pre-charging process of the power battery is as follows: When pre-charging preparation is complete, the battery management chip (BMS) and the vehicle control module 30 initiate self-tests. Upon confirming that no fault signals appear during the self-test, pre-charging begins. The BMS first closes the main negative relay K3, then sends the power battery terminal bus voltage signal to the BMS, and feeds back the status of the main negative relay and the power battery terminal bus voltage to the vehicle control module 30 via the CAN communication module. The vehicle control module 30 obtains the status of the main negative relay K3 through the CAN communication module. After confirming that the main negative relay K3 is closed, the vehicle controller outputs a low-level drive signal to the pre-charging relay K1, causing the pre-charging relay K1 to connect the pre-charging battery and the power battery. Then, the vehicle control module 30 outputs a PWM pulse signal to charge the boost inductor L1 during the effective duty cycle, and then pre-charges the power battery using the first inductor L1 during the ineffective duty cycle. The vehicle control module 30 detects the current pre-charge current during the pre-charge process through the pre-charge current detection module 20. When the current pre-charge current is not equal to the preset current, the duty cycle of the PWM pulse signal is dynamically adjusted in a closed loop to achieve the purpose of pre-charging the power battery with a constant pre-charge current.

[0107] In addition, the vehicle control module 30 can also detect the bus voltage at the bus terminal by controlling the optocoupler Q2 and the voltage divider circuit composed of the sixth resistor R6 and the seventh resistor R7. The bus voltage is compared with the battery voltage at the power battery terminal obtained by the vehicle control module 30 through the CAN communication module to confirm whether the pre-charging is completed. When the bus voltage is greater than or equal to the battery voltage, the vehicle control module 30 determines that the pre-charging is complete. The vehicle control module 30 outputs a PWM pulse signal with a duty cycle of 0 to the first MOSFET Q1 and outputs a cutoff signal to the pre-charging relay K1 to close the pre-charging relay K1. The battery management chip BMS closes the main positive relay K2 and feeds back the status of the main positive relay to the vehicle control module 30 through the CAN communication module to complete the entire pre-charging process.

[0108] In addition, refer to Figure 8 , Figure 8 This is a flowchart illustrating the first embodiment of the high-voltage pre-charging method of the present invention; based on Figure 8 The present invention also provides a high-voltage pre-charging method, the high-voltage pre-charging method comprising:

[0109] The high-voltage pre-charging method includes:

[0110] Step S10: Detect the current pre-charge current during the pre-charge process of the power battery;

[0111] Step S20: When the current pre-charge current is not equal to the preset current, adjust the duty cycle of the PWM pulse signal according to the current pre-charge current;

[0112] Step S30: Adjust the current pre-charge current to the preset current according to the PWM pulse signal after the duty cycle adjustment.

[0113] It should be understood that the execution subject in this embodiment can be the high-voltage pre-charging circuit described above. The specific structure of the high-voltage pre-charging circuit can be referred to the above embodiment, and will not be repeated here.

[0114] It should be understood that, during battery charging, to prevent the current surge caused by the instantaneous high-voltage power-on from affecting the vehicle's power battery, a pre-charging process is performed before the main power battery is charged. (Refer to...) Figure 2 During the pre-charging process, a pre-charging resistor and a pre-charging relay are typically used. Taking a commonly used 400V platform battery system with a high-voltage bus capacitor totaling 2000uF and a 100-ohm pre-charging resistor as an example, in... Figure 2 In this case, the pre-charging time of the pre-charging resistor is T1 = 4RC = 0.8S. In addition, due to the resistance characteristics, the resistance value of the pre-charging resistor will gradually increase during the pre-charging process, which will cause the pre-charging current to gradually decrease, further increasing the pre-charging time.

[0115] It should be noted that the high-voltage pre-charging circuit in this embodiment includes: a pre-charging drive module, a pre-charging current detection module, and a vehicle control module. The pre-charging drive module is used to drive the pre-charging battery to pre-charge the power battery. This pre-charging drive module can control the output pre-charging current by setting the conduction state of the internal switching transistor. The pre-charging current detection module is used to detect the pre-charging current during the power battery pre-charging process. Since the pre-charging current may change during the power battery pre-charging process, the pre-charging current detection module can detect the pre-charging current in real time or at regular intervals. The vehicle control module can be a vehicle controller, which can control the pre-charging process of the power battery.

[0116] During the pre-charging process, the pre-charging current detection module can detect the current pre-charging current of the power battery and send the current pre-charging current to the vehicle control module. When the current pre-charging current is not equal to the preset current, the vehicle control module can adjust the duty cycle of the PWM pulse signal according to the current pre-charging current and output the adjusted PWM pulse signal to the pre-charging drive module. The pre-charging drive module can adjust the current pre-charging current to the preset current according to the adjusted PWM pulse signal.

[0117] The current precharge current is the precharge current detected by the precharge current detection module at the current detection point. This preset current is a pre-set charging current output by the precharge battery with a constant value. The precharge current value can be the maximum precharge current value or a current value within a certain range below the maximum current value, such as 6A. The PWM pulse signal is the signal used by the precharge drive module 10 to control the output duration of the precharge battery. The duty cycle of this PWM pulse signal is related to the output duration of the precharge battery. It can be understood that within a complete cycle, the longer the output duration of the precharge battery, the larger the corresponding precharge current value. When the precharge current changes, the output time of the precharge battery can be adjusted by regulating the duty cycle of the PWM pulse signal, thereby maintaining a constant precharge current value.

[0118] Understandably, taking a commonly used 400V platform battery system with a total high-voltage bus capacitor value of 2000uF and a preset current of 6A as an example, the time for the power battery to be precharged by this preset current is T2=U*C / I=0.13S. Compared with the precharging method of precharging resistor and precharging relay, the precharging time of the power battery can be reduced when the power battery is precharged with a preset current of constant current value.

[0119] This embodiment provides a high-voltage pre-charging method. This method detects the current pre-charging current during the pre-charging process of the power battery. When the current pre-charging current is not equal to a preset current, the duty cycle of a PWM pulse signal is adjusted according to the current pre-charging current. The current pre-charging current is then adjusted to the preset current based on the PWM pulse signal with the adjusted duty cycle. In this invention, by acquiring the current pre-charging current and adjusting it to the preset current when it is not equal to the preset current, the pre-charging process is performed with a constant preset current, thereby reducing the pre-charging time of the vehicle battery and improving the user experience.

[0120] Reference Figure 9 , Figure 9 This is a flowchart illustrating the second embodiment of the high-voltage pre-charging method of the present invention; based on the first embodiment of the high-voltage pre-charging method described above, a second embodiment of the high-voltage pre-charging method of the present invention is proposed.

[0121] In this embodiment, before step S10, the following steps are also included:

[0122] Step S101: Upon receiving a pre-charge command, detect the bus voltage of the bus to be connected to the power battery;

[0123] Step S102: Upon receiving the battery terminal bus voltage, drive the pre-charged battery to output a preset current to charge the power battery.

[0124] In this embodiment, before the vehicle control module outputs a low-level signal to control the pre-charge relay to close, it also needs to confirm whether the power battery connection is complete. For example, if the relay at the power battery end is not closed, even if the pre-charge relay is closed, the power battery cannot be pre-charged.

[0125] Therefore, in this embodiment, a battery voltage detection module and a CAN communication module are also provided. The battery voltage detection module can detect the bus voltage connected to the power battery. When the bus voltage is detected, it can be determined that the relay used to connect the bus and the power battery is closed, and the pre-charging step can be performed.

[0126] In practice, the vehicle control module can output a pre-charge command to the battery voltage detection module. Upon receiving the pre-charge command, the battery voltage detection module detects the bus voltage of the bus to be connected to the power battery and sends this bus voltage to the vehicle control module via the CAN communication module. When the vehicle control module receives the battery bus voltage, it outputs a drive signal to the pre-charge drive module. Upon receiving the drive signal, the pre-charge drive module can output a preset current to charge the power battery. If the vehicle control module does not receive the battery bus voltage, it indicates that the power battery has not completed pre-charge preparation, and the vehicle control module will not output a drive signal to the pre-charge drive module temporarily.

[0127] Reference Figure 6 The battery management chip is used to regulate the charging and discharging process of the power battery. In this embodiment, the battery management chip can collect parameters such as the bus voltage and battery voltage at the power battery terminal. The main negative relay is used to establish a connection between the bus and the power battery when pre-charging begins. The main positive relay is used to close after pre-charging is completed, thereby controlling the end of the pre-charging process.

[0128] Furthermore, in this embodiment, after step S30, the following steps are also included:

[0129] Step S40: Detect the capacitor voltage across the bus capacitor;

[0130] Step S50: When the capacitor voltage is greater than the preset voltage, stop driving the pre-charged battery to output pre-charge current.

[0131] It should be understood that during the pre-charging process of the power battery, it is also necessary to determine in real time whether the power battery has completed pre-charging to avoid wasting resources by continuing pre-charging after it has been completed. Therefore, in this embodiment, a capacitor voltage detection module can also be set up. This module can obtain the voltage across the power battery by detecting the voltage across the bus capacitor connected in parallel with the power battery, thereby determining whether the power battery has completed pre-charging.

[0132] In a specific implementation, the capacitor voltage detection module can detect the capacitor voltage across the bus capacitor in real time during the pre-charging process of the power battery, and output the capacitor voltage to the vehicle control module; the vehicle control module can output a cut-off signal to the pre-charging drive module when the capacitor voltage is greater than or equal to a preset voltage value; the pre-charging relay in the pre-charging drive module can disconnect its contacts when it receives the cut-off signal, thereby stopping the output of the preset current to the power battery.

[0133] The preset voltage value is a pre-set voltage used to determine whether the pre-charging process of the power battery is complete. The cutoff signal is a signal that controls the pre-charging drive module to disconnect the connection between the pre-charging battery and the power battery, stopping the pre-charging of the power battery. In this embodiment, the cutoff signal can be a high-level signal.

[0134] In this embodiment, the sixth and seventh resistors can be sampling resistors, and they are connected in parallel with the second capacitor and the bus capacitor. When the optocoupler is turned on, the voltage value at the midpoint between the sixth and seventh resistors can be input to the vehicle control module, thereby detecting the voltage across the bus capacitor.

[0135] In a specific implementation, the vehicle control module can output a low-level signal to the second end of the optocoupler through the optocoupler control pin. At this time, the first and second ends of the optocoupler are connected, and the third and fourth ends are connected, connecting the sixth and seventh resistors in parallel across the bus capacitor and the second capacitor. The capacitor voltage across the bus capacitor can be input to the voltage detection pin of the vehicle control module through the second end of the seventh resistor. The vehicle control module can compare the received capacitor voltage with the preset voltage value and determine whether the power battery has been pre-charged based on the comparison result.

[0136] Reference Figure 7 In this embodiment, the pre-charging process of the power battery is as follows: When pre-charging preparation is complete, the battery management chip and the vehicle control module initiate self-tests. If no fault signal is detected during the self-test, pre-charging begins. The battery management chip first closes the main negative relay, then sends the power battery terminal bus voltage signal, and feeds back the main negative relay status and the power battery terminal bus voltage to the vehicle control module via the CAN communication module. The vehicle control module obtains the main negative relay status via the CAN communication module. After confirming that the main negative relay is closed, the vehicle controller outputs a low-level drive signal to the pre-charging relay, enabling the pre-charging relay to connect the pre-charging battery and the power battery. Then, the vehicle control module outputs a PWM pulse signal to charge the boost inductor during the effective duty cycle, and then pre-charges the power battery using the first inductor during the ineffective duty cycle. The vehicle control module detects the current pre-charging current during the pre-charging process through the pre-charging current detection module. When the current pre-charging current is not equal to the preset current, the duty cycle of the PWM pulse signal is dynamically adjusted in a closed loop to achieve constant pre-charging current for the power battery.

[0137] In addition, the vehicle control module can also detect the bus voltage at the bus terminal by controlling the optocoupler and the voltage divider circuit composed of the sixth and seventh resistors. It compares the bus voltage with the battery voltage at the power battery terminal obtained by the vehicle control module through the CAN communication module to confirm whether the pre-charging is complete. When the bus voltage is greater than or equal to the battery voltage, the vehicle control module determines that the pre-charging is complete. The vehicle control module outputs a PWM pulse signal with a duty cycle of 0 to the first MOSFET and outputs a cutoff signal for the pre-charging relay to turn off the pre-charging relay. The battery management chip closes the main positive relay and feeds back the status of the main positive relay to the vehicle control module through the CAN communication module to complete the entire pre-charging process.

[0138] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A high-voltage pre-charging circuit, characterized in that, The high-voltage pre-charging circuit includes: a pre-charging drive module, a pre-charging current detection module, and a vehicle control module; The pre-charge drive module is connected to the vehicle control module and the power battery, respectively, and the pre-charge current detection module is connected to the pre-charge drive module and the vehicle control module, respectively. The pre-charge current detection module is used to detect the current pre-charge current during the pre-charge process of the power battery and send the current pre-charge current to the vehicle control module. The vehicle control module is used to adjust the duty cycle of the PWM pulse signal according to the current pre-charge current when the current pre-charge current is not equal to the preset current, and output the adjusted PWM pulse signal to the pre-charge drive module. The precharge drive module is used to adjust the current precharge current to the preset current according to the adjusted PWM pulse signal, so as to reduce the precharge time of the power battery. The high-voltage pre-charging circuit also includes: a battery voltage detection module and a CAN communication module; The battery voltage detection module is connected to the power battery and the vehicle control module respectively. The battery voltage detection module is used to detect the bus voltage connected to the power battery bus when a pre-charge command is received, and send the bus voltage to the vehicle control module through the CAN communication module. The vehicle control module is also used to output a drive signal to the pre-charge drive module when it receives the voltage of the power battery terminal bus; The pre-charge drive module is also used to output a preset current to charge the power battery when it receives the drive signal; The high-voltage pre-charging circuit also includes: a capacitor voltage detection module; The capacitor voltage detection module is connected to the vehicle control module and the bus capacitor located between the pre-charge drive module and the power battery. The capacitor voltage detection module is used to detect the capacitor voltage across the bus capacitor during the pre-charging process of the power battery, and output the capacitor voltage to the vehicle control module. The vehicle control module is also used to output a cutoff signal to the pre-charge drive module when the capacitor voltage is greater than or equal to a preset voltage value; The precharge drive module is also used to stop outputting the preset current when it receives the cutoff signal.

2. The high-voltage pre-charging circuit as described in claim 1, characterized in that, The precharge drive module includes: a precharge relay, a first inductor, a first MOSFET, and a first diode; The first terminal of the precharge relay is connected to the relay drive pin of the vehicle control module, the second terminal of the precharge relay is connected to the positive terminal of the precharge battery, and the third terminal of the precharge relay is connected to the first terminal of the first inductor. The second terminal of the first inductor is connected to the drain of the first MOSFET and the anode of the first diode, respectively. The gate of the first MOSFET is connected to the PWM pulse pin of the vehicle control module, and the output of the first MOSFET is connected to the negative terminal of the precharged battery. The negative terminal of the first diode is connected to the positive terminal of the power battery.

3. The high-voltage pre-charging circuit as described in claim 2, characterized in that, The pre-charge current detection module includes: first to fifth resistors, an operational amplifier, and a first capacitor; Wherein, the first end of the first resistor is connected to the source of the first MOS transistor and the first end of the second resistor, and the second end of the first resistor is connected to the first end of the third resistor and the second end of the bus capacitor. The second end of the second resistor is connected to the negative input of the operational amplifier and the first end of the fourth resistor. The second end of the third resistor is connected to the positive input of the operational amplifier. The output of the operational amplifier is connected to the second end of the fourth resistor and the first end of the fifth resistor. The second end of the fifth resistor is connected to the first end of the first capacitor and the current detection pin of the vehicle control module. The second end of the first capacitor is grounded.

4. The high-voltage pre-charging circuit as described in claim 1, characterized in that, The capacitor voltage detection module includes: an optocoupler, a sixth resistor, a seventh resistor, and a second capacitor; In this configuration, the second capacitor is connected in parallel with the bus capacitor. The first end of the optocoupler is connected to the positive terminal of the precharged battery. The second end of the optocoupler is connected to the optocoupler control pin of the vehicle control module. The third end of the optocoupler is connected to the precharge drive module and the first end of the second capacitor. The fourth end of the optocoupler is connected to the first end of the seventh resistor. The second end of the seventh resistor is connected to the voltage detection pin of the vehicle control module and the first end of the sixth resistor. The second end of the sixth resistor is connected to the second end of the second capacitor and the negative terminal of the precharged battery.

5. The high-voltage pre-charging circuit as described in claim 3, characterized in that, The battery voltage detection module includes: a battery management chip, a main positive relay, and a main negative relay; The first pin of the battery management chip is connected to the first terminal of the bus capacitor and the first terminal of the main positive relay, and the second pin of the battery management chip is connected to the second terminal of the bus capacitor and the first terminal of the main negative relay. The third terminal of the battery management chip is connected to the positive terminal of the power battery and the second terminal of the main positive relay, and the fourth terminal of the battery management chip is connected to the negative terminal of the power battery and the second terminal of the main negative relay. The fifth terminal of the battery management chip is connected to the vehicle control module via the CAN communication module.

6. A high-voltage pre-charging method, characterized in that, The high-voltage pre-charging method is applied to the high-voltage pre-charging circuit according to any one of claims 1-5; The high-voltage pre-charging method includes: Detect the current pre-charge current during the pre-charge process of the power battery; When the current pre-charge current is not equal to the preset current, the duty cycle of the PWM pulse signal is adjusted according to the current pre-charge current; The current pre-charge current is adjusted to the preset current based on the PWM pulse signal with the duty cycle adjusted, so as to reduce the pre-charge time of the power battery; Before the step of detecting the current pre-charge current during the pre-charge process of the power battery, the method further includes: Upon receiving a pre-charge command, the bus voltage of the power battery to be connected is detected; When the bus voltage of the power battery is received, the pre-charged battery is driven to output a preset current to charge the power battery.

7. The high-voltage pre-charging method as described in claim 6, characterized in that, After the step of adjusting the current pre-charge current to the preset current based on the PWM pulse signal with the duty cycle adjusted, the method further includes: Detect the capacitor voltage across the bus capacitor; When the capacitor voltage is greater than a preset voltage, the pre-charged battery is stopped from outputting a preset current.

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