Multi-path pre-charging circuit, control method and vehicle

Abstract

The invention provides a multi-path pre-charging circuit, a control method and a vehicle, and belongs to the technical field of new energy vehicles. The input end of each charging control sub-circuit is electrically connected with the power supply, the output end of each charging control sub-circuit is configured to be electrically connected with the corresponding load capacitor, and each charging control sub-circuit comprises a pre-charging branch circuit and a charging switch connected with the pre-charging branch circuit in parallel; the pre-charging branch comprises a pre-charging switch and a pre-charging resistor; the control module is configured to adjust the conduction duty ratio of a target pre-charging switch in a pre-charging branch connected with the to-be-charged load capacitor based on the charging requirement of the to-be-charged load capacitor so as to control the power supply to charge the to-be-charged load, and turn off the target pre-charging switch under the condition that the to-be-charged load capacitor is fully charged so as to charge the to-be-charged load. And a charging switch connected with the to-be-charged load capacitor is closed. According to the multi-path pre-charging circuit provided by the invention, the charging time can be shortened to the maximum extent.

Description

Technical Field

[0001] This invention belongs to the field of vehicle technology, specifically relating to a multi-channel pre-charging circuit, a control method, and a vehicle. Background Technology

[0002] In the high-voltage systems of new energy vehicles, a large-capacity DC bus capacitor is typically installed at the input terminal to filter current ripple and maintain stable bus voltage. However, at the instant the high-voltage system is powered on, the voltage of the high-voltage battery is suddenly applied across the uncharged bus capacitor. Since the bus capacitor cannot change abruptly, its equivalent impedance is extremely low at this time, which can trigger a huge instantaneous inrush current, easily burning out the main relay in the high-voltage system and posing a serious safety hazard. Summary of the Invention

[0003] In view of the above problems, embodiments of this application provide a multi-channel pre-charging circuit, a control method, and a vehicle to overcome or at least partially solve the above problems.

[0004] A first aspect of this application provides a multi-channel pre-charge circuit, comprising: A power supply; multiple charging control sub-circuits, each charging control sub-circuit having its input terminal electrically connected to the power supply and its output terminal configured to be electrically connected to a corresponding load capacitor; each charging control sub-circuit including a pre-charge branch and a charging switch connected in parallel with the pre-charge branch; the pre-charge branch including a pre-charge switch and a pre-charge resistor; a control module electrically connected to the control terminals of the pre-charge switch and the charging switch; the control module being configured to adjust the duty cycle of the target pre-charge switch in the pre-charge branch connected to the load capacitor to be charged based on the charging demand of the load capacitor to be charged, so as to control the power supply to charge the load capacitor to be charged, and to turn off the target pre-charge switch and close the charging switch connected to the load capacitor to be charged when the load capacitor to be charged is fully charged.

[0005] In some embodiments, the multi-channel pre-charging circuit further includes a main charging switch, a first terminal of which is electrically connected to the power supply, a second terminal of which is electrically connected to the input terminal of the plurality of charging control sub-circuits, and a control terminal of which is electrically connected to the control module; the main charging switch is configured to close in response to a charging signal output by the control module, so that the power supply provides power to the plurality of charging control sub-circuits.

[0006] In some embodiments, the pre-charge branch further includes a diode, the positive terminal of which is electrically connected to the second terminal of the main charging switch, the negative terminal of which is electrically connected to the first terminal of the pre-charge switch, the second terminal of the pre-charge switch is electrically connected to the first terminal of the pre-charge resistor, the second terminal of the pre-charge resistor is electrically connected to the first terminal of the load capacitor, and the second terminal of the load capacitor to be charged is electrically connected to the negative terminal of the power supply.

[0007] In some embodiments, the pre-charge branch further includes a current detection unit connected in series between the pre-charge resistor and the load capacitor, and a voltage detection unit connected in parallel across each load capacitor. The current detection unit and the voltage detection unit are respectively electrically connected to the control module. The control module is further configured to adjust the duty cycle of the target precharge switch based on the charging voltage across the load capacitor to be charged detected by the voltage detection unit and the charging current flowing into the load capacitor to be charged detected by the current detection unit.

[0008] In some embodiments, the charging requirement of the load capacitor to be charged includes a target charging voltage. The control module includes a voltage loop controller and a current loop controller. The input terminal of the voltage loop controller is electrically connected to the voltage detection unit, the output terminal of the voltage loop controller is electrically connected to the first input terminal of the current loop controller, the second input terminal of the current loop controller is electrically connected to the current detection unit, and the output terminal of the current loop controller is electrically connected to the control terminal of the pre-charge switch. The voltage loop controller is configured to determine the target charging current required for charging the load capacitor based on the voltage difference between the target charging voltage and the charging voltage across the load capacitor to be charged, and output the target charging current to the current loop controller. The current loop controller is configured to generate a pulse width modulation signal based on the current difference between the target charging current and the charging current, and output it to the target pre-charge switch.

[0009] In some embodiments, the charging requirement of the load capacitor to be charged also includes a target charging time. The control module is further configured to determine the maximum allowable charging current of the load capacitor to be charged based on the target charging voltage, the target charging time, and the capacitance value of the load capacitor to be charged, and to control the charging current output by the precharge branch including the target precharge switch to be within the range of the maximum allowable charging current.

[0010] In some embodiments, the precharge switch includes an insulated gate bipolar transistor, and the main charging switch and the charging switch include a relay.

[0011] A second aspect of this application provides a control method for a multi-channel pre-charge circuit, applied to a control module in the multi-channel pre-charge circuit described in the first aspect of this application. The control method includes: Based on the charging demand of the load capacitor to be charged, the duty cycle of the target pre-charge switch in the pre-charge branch connected to the load capacitor to be charged is adjusted to control the power supply to charge the load capacitor to be charged; wherein, the input terminal of each of the multiple charging control sub-circuits is electrically connected to the power supply, and the output terminal of each charging control sub-circuit is configured to be electrically connected to the corresponding load capacitor, each charging control sub-circuit includes a pre-charge branch and a charging switch connected in parallel with the pre-charge branch, the pre-charge branch includes a pre-charge switch and a pre-charge resistor; the charging voltage across the load capacitor to be charged is obtained, and when the charging voltage indicates that the load capacitor to be charged is fully charged, the target pre-charge switch is turned off and the charging switch connected to the load capacitor to be charged is closed.

[0012] In some embodiments, the charging requirement includes a target charging time, and the control method further includes: Before controlling the target precharge switch to close, the maximum allowable charging current is determined based on the target charging time and the capacitance value of the load capacitor to be charged; based on the maximum allowable charging current, the charging current output by the precharge branch including the target precharge switch is controlled to be within the range of the maximum allowable charging current.

[0013] In a third aspect of this application, a vehicle is provided, including the multi-channel pre-charging circuit described in the first aspect of this application and a plurality of electrical loads, each of the electrical loads being provided with a load capacitor, and each charging control sub-circuit in the multi-channel pre-charging circuit being electrically connected to the corresponding load capacitor.

[0014] This embodiment provides a multi-channel pre-charging circuit with a power supply and multiple charging control sub-circuits. The input of each charging control sub-circuit is electrically connected to the power supply, and the output of each sub-circuit is configured to be electrically connected to a corresponding load capacitor. Each charging control sub-circuit includes a pre-charging branch and a charging switch connected in parallel with the pre-charging branch. The pre-charging branch includes a pre-charging switch and a pre-charging resistor, which facilitates layout optimization and miniaturization of the multi-channel pre-charging circuit. Furthermore, a control module is configured to adjust the duty cycle of the target pre-charging switch in the pre-charging branch connected to the load capacitor based on its charging requirements, thereby controlling the power supply to charge the load. During the charging process, the pre-charging branch can dynamically adapt the charging current flowing through the target pre-charging switch to load capacitors with different capacities and charging speeds by adjusting the duty cycle of the target pre-charging switch. This also minimizes the pre-charging time while ensuring charging current safety and avoiding impact damage. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the circuit structure of a multi-channel pre-charge circuit provided in an embodiment of this application; Figure 2 This is a schematic diagram of the circuit structure of a pre-charge branch provided in an embodiment of this application; Figure 3 This is a schematic diagram of a circuit structure for closed-loop control of a control module provided in an embodiment of this application; Figure 4 This is a charging waveform diagram of the load capacitor to be charged when the target charging voltage is 750V, provided in an embodiment of this application. Figure 5 This is a charging waveform diagram of the load capacitor to be charged when the target charging voltage is 600V, provided in an embodiment of this application. Figure 6 This is a charging waveform diagram of the load capacitor to be charged when the target charging voltage is 800V, provided in an embodiment of this application. Figure 7 This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a precharge switch is 50%, as provided in this embodiment of the application. Figure 8This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a precharge switch is 100%, as provided in this embodiment of the application. Figure 9 This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a precharge switch is 20%, as provided in the embodiments of this application. Detailed Implementation

[0017] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0018] To address the issue of main relay burnout in high-voltage systems, related technologies employ high-voltage pre-charging circuits. Specifically, a pre-charging branch consisting of a pre-charging relay and a current-limiting resistor is added outside the main relay circuit. When the high-voltage system is powered on, the pre-charging relay closes first, allowing the current-limiting resistor to slowly charge the bus capacitor. Once the capacitor voltage approaches the battery voltage, the main relay closes, achieving a smooth, shock-free connection to the high-voltage system. However, this traditional relay-based pre-charging scheme has the following inherent drawbacks: First, during the relay's engagement and disengagement process, an electric arc is generated between the contacts. The high temperature of the arc continuously erodes and oxidizes the contact surface, leading to increased contact resistance, abnormal heating, and ultimately, relay performance degradation or even failure. Second, as the voltage platform of new energy vehicles continues to rise, the voltage withstand requirements for relays also increase. High-voltage, high-current, and low-internal-resistance relays have complex manufacturing processes, significantly increasing costs. In complex systems requiring multiple pre-charging circuits, the use of relays will lead to a sharp increase in costs. Third, compared to solid-state switching devices of the same specifications, relays are usually several times larger in size and weight, which limits their use in space-constrained applications (such as small motor controllers).

[0019] In view of this, this embodiment provides a multi-channel pre-charge circuit, which replaces the traditional pre-charge relay with a pre-charge switch whose duty cycle can be controlled and adjusted, and constructs multiple parallel pre-charge branches. The control module can precisely control the amplitude and variation curve of the charging current by adjusting the duty cycle of the target pre-charge switch, thereby dynamically adapting to load capacitors with different capacities and charging speed requirements. This solution fundamentally achieves contactless switching, completely eliminating the arcing problem, while also possessing the comprehensive advantages of high flexibility, easy integration, and controllable cost. During the charging process of the target load, the control module can adjust the duty cycle of the target precharge switch in the target precharge branch so that the charging current flowing through the target charging switch can dynamically adapt to the load capacitors with different capacities and charging speed requirements, thus completely avoiding the arcing problem during the relay switching process.

[0020] The multi-channel pre-charge circuit provided in this embodiment will be described in detail below.

[0021] Figure 1 This is a schematic diagram of the circuit structure of a multi-channel pre-charge circuit provided in an embodiment of this application. Figure 1 It is known that the multi-channel pre-charging circuit includes: a power supply; multiple charging control sub-circuits, the input terminal of each charging control sub-circuit being electrically connected to the power supply, the output terminal of each charging control sub-circuit being configured to be electrically connected to the corresponding load capacitor, each charging control sub-circuit including a pre-charging branch and a charging switch connected in parallel with the pre-charging branch, the pre-charging branch including a pre-charging switch and a pre-charging resistor; a control module, electrically connected to the control terminals of the pre-charging switch and the charging switch respectively; the control module is configured to adjust the duty cycle of the target pre-charging switch in the pre-charging branch connected to the load capacitor to be charged based on the charging demand of the load capacitor to be charged, so as to control the power supply to charge the load capacitor to be charged, and when the load capacitor to be charged is fully charged, turn off the target pre-charging switch and close the charging switch connected to the load capacitor to be charged.

[0022] In this embodiment, the power supply can be the vehicle's power battery. The output terminal of the power supply is connected to multiple charging control sub-circuits, and the output terminal of each charging control sub-circuit is configured to be connected to the corresponding load capacitor. Therefore, the power supply can supply power to multiple load capacitors. Figure 1 The 100 in the code represents a charging control sub-circuit.

[0023] Each charging control subcircuit includes a pre-charge branch and a charging switch connected in parallel with the pre-charge branch. Since the pre-charge branch is a circuit that charges the load capacitor by connecting a pre-charge resistor and a pre-charge switch in series, the pre-charge branch can limit the surge current in the early stage of charging the load capacitor. The pre-charge switch, as the on / off control and current regulator of the pre-charge branch, can have its duty cycle adjusted by the control module. In this embodiment, there are multiple pre-charge branches, each corresponding to a load capacitor, and each pre-charge branch has a pre-charge switch. When multiple pre-charge switches are closed, the power supply can supply power to multiple load capacitors simultaneously.

[0024] The charging switch is connected in parallel with the pre-charge branch. Therefore, both ends of the charging switch are electrically connected to the power supply and the load capacitor, respectively. One charging switch corresponds to one pre-charge branch. For a single load capacitor, there are two charging paths: one is the pre-charge branch, and the other is the line where the charging switch is located. Thus, the charging switch and the pre-charge branch can work together, each undertaking different charging functions during the pre-charge and main charging phases of the load capacitor. During the pre-charge phase, the pre-charge switch is closed, and the charging switch is open. The power supply forms a charging circuit through the pre-charge resistor, utilizing its current-limiting effect to provide flexible and controlled charging of the load capacitor, effectively suppressing inrush current. During the main charging phase, when the load capacitor has completed pre-charge and needs to switch to full-power operation, the charging switch is closed, and the pre-charge switch is open. At this time, the current output from the main power supply path no longer passes through the pre-charge resistor, avoiding energy loss on the pre-charge resistor and meeting the continuous high-current demand of the load during steady-state operation.

[0025] The control module can be a vehicle controller, battery management system, motor controller, or other dedicated control device. Since the control module is electrically connected to the control terminals of the pre-charge switch and the charging switch, it can control the on / off state of the pre-charge switch and the charging switch to achieve coordinated operation of the charging switch and the pre-charge branch. Based on the charging demand of the load capacitor to be charged, it adjusts the duty cycle of the target pre-charge switch in the pre-charge branch connected to the load capacitor to control the power supply to charge the load capacitor. Once the load capacitor is fully charged, it turns off the target pre-charge switch and closes the charging switch connected to the load capacitor.

[0026] Continue to refer to Figure 1 The multiple pre-charging circuits also include a main charging switch, the first end of which is electrically connected to the power supply, the second end of which is electrically connected to the input of multiple charging control sub-circuits, and the control end of which is electrically connected to the control module. The main charging switch is configured to close in response to a charging signal output by the control module, so that the power supply can supply power to the multiple charging control sub-circuits.

[0027] In this embodiment, the multiple pre-charging circuits also include a main charging switch, that is, the main charging switch is... Figure 1 In the diagram, S0, the first terminal of the main charging switch is electrically connected to the power supply, the control terminal of the main charging switch is electrically connected to the input terminals of multiple charging control sub-circuits, and the control terminal of the main charging switch is electrically connected to the control module. Therefore, the control module can control the main charging switch to turn it on and off, so that the power supply can provide power to the multiple charging control sub-circuits. A specific example will be used below to illustrate this. Figure 1 The application of the multi-channel pre-charging circuit provided in this embodiment to a vehicle will be described in detail.

[0028] from Figure 1 It can be seen that, Figure 1 Taking a four-way pre-charging circuit as an example, the four-way pre-charging circuit includes four charging control sub-circuits, namely a first charging switch S1, a second charging switch S2, a third charging switch S3, and a fourth charging switch S4, a first pre-charging branch, a second pre-charging branch, a third pre-charging branch, and a fourth pre-charging branch. The first pre-charging branch includes a first pre-charging switch IGBT1 and a first pre-charging resistor R1; the second pre-charging branch includes a second pre-charging switch IGBT2 and a second pre-charging resistor R2; the third pre-charging branch includes a third pre-charging switch IGBT3 and a third pre-charging resistor R3; and the fourth pre-charging branch includes a fourth pre-charging switch IGBT4 and a fourth pre-charging resistor R4. VBUS is the power supply, and the four load capacitors are the first load capacitor C1, the second load capacitor C2, the third load capacitor C3, and the fourth load capacitor C4.

[0029] When the vehicle is powered on, assuming that the first load capacitor C1 and the third load capacitor C3 need to be pre-charged simultaneously, while the second load capacitor C2 and the fourth load capacitor C4 are not yet operational, the control module first closes the main charging switch S0 to connect the power supply to the circuit. Then, the control module selects two pre-charge branches connected to the first load capacitor C1 and the third load capacitor C3 from multiple pre-charge branches as target pre-charge branches. The control module sends pulse width modulation signals to the first pre-charge switch IGBT1 and the third pre-charge switch IGBT3 in the two selected target pre-charge branches. Specifically, a low duty cycle can be initially set to initiate a trial charge of the first load capacitor C1 and the third load capacitor C3 with a very small current. Subsequently, the control module dynamically and independently adjusts the duty cycle of the first pre-charge switch IGBT1 and the third pre-charge switch IGBT3 based on the real-time monitored bus current, precisely maintaining the charging current at the system's safe maximum value (e.g., 20A). During this process, due to the use of pulse width modulation signal control, the current is smooth and without impact.

[0030] When the control module detects that both the first load capacitor C1 and the third load capacitor C3 are fully charged, it determines that pre-charging is complete. The control module immediately turns off the first pre-charge switch IGBT1 and the third pre-charge switch IGBT3, and closes the first charging switch S1 and the third charging switch S3 connected to the load capacitors to be charged. At this time, current flows through the low-impedance charging switches to supply power to the first load capacitor C1 and the third load capacitor C3.

[0031] Continue to refer to Figure 1The pre-charge branch also includes a diode. The positive terminal of the diode is electrically connected to the second terminal of the main charging switch, the negative terminal of the diode is electrically connected to the first terminal of the pre-charge switch, the second terminal of the pre-charge switch is electrically connected to the first terminal of the pre-charge resistor, the second terminal of the pre-charge resistor is electrically connected to the first terminal of the load capacitor, and the second terminal of the load capacitor to be charged is electrically connected to the negative terminal of the power supply.

[0032] In this embodiment, the pre-charge branch also includes a diode. The diode has unidirectional conductivity and does not allow current to flow from the negative terminal to the positive terminal. Since there are multiple pre-charge branches in this embodiment, each pre-charge branch has a unique corresponding load capacitor, refer to... Figure 1 , Figure 1 The first pre-charge branch includes a first diode D1, the second pre-charge branch includes a second diode D2, the third pre-charge branch includes a third diode D3, and the fourth pre-charge branch includes a fourth diode D4. The capacity of each load capacitor is different, so the charging progress of each load capacitor is inconsistent.

[0033] For example, after the first load capacitor C1 is fully charged, the second load capacitor C2 may have just started charging. The fully charged first load capacitor C1 may flow in the reverse direction to the second load capacitor C2, which has a lower voltage, through other open paths, resulting in reverse current. Therefore, by setting a diode in the pre-charge branch, that is, setting a first diode D1 in the first pre-charge branch and a second diode D2 in the second pre-charge branch, the reverse current flow between the parallel first and second pre-charge branches can be avoided, ensuring that the pre-charge branch charges its corresponding load capacitor in one direction only.

[0034] In addition, when a precharge switch on a precharge branch experiences a circuit breakdown fault, the faulty precharge branch will lose its current limiting function. Without a diode, the power supply will form a large current loop through this faulty precharge branch, causing the entire high-voltage multi-path precharge circuit system to fail due to the fault. If a diode is present, even if the precharge switch of the faulty charging switch experiences a short circuit fault, the reverse cutoff characteristic of the diode will effectively block the current from other normal precharge branches, preventing the spread of the local fault and isolating the impact of the fault within the fault path.

[0035] Continue to refer to Figure 1 The precharge branch also includes a current detection unit, which is connected in series between the precharge resistor and the load capacitor. A voltage detection unit is connected in parallel across each load capacitor. The current detection unit and the voltage detection unit are electrically connected to the control module. The control module is also configured to adjust the duty cycle of the target precharge switch based on the charging voltage across the load capacitor to be charged detected by the voltage detection unit and the charging current flowing into the load capacitor to be charged detected by the current detection unit.

[0036] In this embodiment, the pre-charge branch also includes a current detection unit. Figure 1 The first pre-charge branch includes a first current detection unit Am1, the second pre-charge branch includes a second current detection unit Am2, the third pre-charge branch includes a third current detection unit Am3, and the fourth pre-charge branch includes a fourth current detection unit Am4. The current detection units are used to measure the charging current flowing into the load capacitor. A voltage detection unit is connected in parallel across each load capacitor. Figure 1 The first pre-charge branch includes a first voltage detection unit Vm1, the second pre-charge branch includes a second voltage detection unit Vm2, the third pre-charge branch includes a third voltage detection unit Vm3, and the fourth pre-charge branch includes a fourth voltage detection unit Vm4. The voltage detection units are used to detect the charging voltage of the load capacitor. Therefore, the control module can determine whether the pre-charging is complete by detecting the charging voltage transmitted by the voltage detection units during the charging process of the load capacitor to be charged. Secondly, during the pre-charging process, the control module can also dynamically adjust the duty cycle of the target pre-charge switch based on the real-time charging current value fed back by the current detection unit, thereby accurately stabilizing the charging current within the set safety range and realizing closed-loop intelligent control of the pre-charging process.

[0037] Figure 2 This is a schematic diagram of a circuit structure for closed-loop control of a control module provided in an embodiment of this application; from Figure 2 It is known that the charging requirement of the load capacitor to be charged includes a target charging voltage. The control module includes a voltage loop controller and a current loop controller. The input terminal of the voltage loop controller is electrically connected to the voltage detection unit, the output terminal of the voltage loop controller is electrically connected to the first input terminal of the current loop controller, the second input terminal of the current loop controller is electrically connected to the current detection unit, and the output terminal of the current loop controller is electrically connected to the control terminal of the pre-charge switch. The voltage loop controller is configured to determine the target charging current required for charging the load capacitor based on the voltage difference between the target charging voltage and the charging voltage across the load capacitor to be charged, and output the target charging current to the current loop controller. The current loop controller is configured to generate a pulse width modulation signal based on the current difference between the target charging current and the charging current, and output it to the target pre-charge switch.

[0038] In this embodiment, the control module includes a voltage loop controller and a current loop controller. The voltage loop controller monitors whether the voltage across the load capacitor reaches the target charging voltage. Specifically, based on the voltage difference between the target voltage and the charging voltage across the load capacitor, it determines the charging current required to reach the target charging voltage most quickly and stably, i.e., the target charging current. Then, it outputs the target charging current to the current loop controller. The current loop controller, based on the current difference between the target charging current and the current, calculates a pulse width modulation signal using its internal PID (Proportional-Integral-Derivative) algorithm, which directly acts on the target pre-charge switch. For example, if the charging current is too small → the current difference is positive → the PID calculation increases the duty cycle → the average current increases → the actual current rises to the target charging current. If the charging current is too large → the current difference is negative → the PID calculation decreases the duty cycle → the average current decreases → the charging current drops to near the target charging current, so that the charging current supplied by the target pre-charge branch to the load capacitor is the target charging current.

[0039] Figure 3 This is a schematic diagram of the circuit structure of a precharge branch provided in an embodiment of this application, with the target precharge switch being an IGBT. Figure 3 As can be seen, the output terminal of the current loop controller is electrically connected to the collector (C) of the target precharge switch, the collector (C) of the target precharge switch is electrically connected to the power supply, the emitter (E) of the target precharge switch is electrically connected to the first terminal of the target precharge resistor, the second terminal of the target precharge resistor is electrically connected to the first terminal of the current detection unit, the second terminal of the current detection unit is electrically connected to the first terminal of the load capacitor to be charged, the second terminal of the load capacitor to be charged is electrically connected to the negative terminal of the power supply, the voltage detection unit is connected in parallel across the load capacitor to be charged, the output terminal of the voltage detection unit is electrically connected to the first input terminal of the voltage loop controller, and the output terminal of the current detection unit is electrically connected to the first input terminal of the voltage loop controller.

[0040] For example, combined Figure 2 and Figure 3 The process of charging a target pre-charge branch for a load capacitor to be charged is described.

[0041] The voltage loop controller monitors the charging voltage across the capacitor to be charged and compares it with the target charging voltage. The PI controller within the voltage loop calculates the target charging current required to reach the target charging voltage based on the voltage difference and sends this target charging current as a command to the current loop controller. The upper limit of the target charging current output is strictly clamped to the maximum safe current value allowed by the system. Current limiting is achieved through voltage loop output limiting to prevent damage to the system from inrush current.

[0042] The current loop controller receives the target charging current from the voltage loop controller and controls the charging current to track the target charging current quickly and accurately. Specifically, this is achieved by adjusting the PWM duty cycle, i.e., the on-state duty cycle of the target pre-charge switch, to drive the target pre-charge switch and directly control the energy input. The current loop controller has an extremely fast response speed, instantly suppressing various disturbances and ensuring that the charging current never exceeds the safety limit set by the voltage loop controller.

[0043] For example, assuming the target charging voltage is 750V and the charging voltage across the load capacitor to be charged is 600V, the voltage difference is -150V, indicating that a larger current is needed for rapid charging to quickly reduce the voltage difference. However, the calculated result will exceed the preset maximum safe current (10A). At this time, the voltage loop controller outputs a target charging current of 10A. If the charging current of the load capacitor to be charged is 5A, the current loop controller will generate an adjustment proportional to the 5A deviation, significantly increasing the duty cycle of the target pre-charge switch in an attempt to quickly reduce the difference from the target charging current. Finally, the current loop controller will output a signal that significantly increases the duty cycle of the target pre-charge switch, driving the target pre-charge switch to be on for a longer time. The charging current in the target pre-charge branch rises rapidly from 5A until the charging current accurately tracks the target charging current of 10A.

[0044] Referring to the control methods described above, Figure 4 This is a charging waveform diagram of the load capacitor to be charged when the target charging voltage is 750V, provided in an embodiment of this application. Figure 5 This is a charging waveform diagram of the load capacitor to be charged when the target charging voltage is 600V, provided in an embodiment of this application. Figure 6 This application provides a charging waveform diagram of a load capacitor to be charged when the target charging voltage is 800V. Charging waveform diagrams of the load capacitor being charged when the target charging voltage is set to 750V, 600V, and 800V are shown respectively. Figures 4-6 As can be seen, the multi-channel pre-charge circuit in this embodiment can achieve a smooth rise in the voltage across the capacitor to be charged without intervention, and can smoothly transition to constant voltage mode, with the current gradually decreasing to zero and the voltage stabilizing at the target charging voltage without overshoot.

[0045] In some embodiments, the charging requirement of the load capacitor to be charged also includes a target charging time. The control module is also configured to determine the maximum allowable charging current of the load capacitor to be charged based on the target charging voltage, the target charging time, and the capacitance value of the load capacitor to be charged, and to control the charging current output by the precharge branch, including the target precharge switch, to be within the range of the maximum allowable charging current.

[0046] In this embodiment, when the vehicle is in certain specific driving modes or economic start, a shorter charging time can be set to quickly reach a ready state to meet the driver's needs. Therefore, the charging requirement can also include a target charging time, which can be dynamically set and issued by the vehicle's upper-level controller (such as the vehicle controller) based on the real-time driving mode, driver request, or system status.

[0047] For example, combined Figure 2 and Figure 3 Assume the target charging voltage is 750V, the target charging time ΔT is 500ms, and the capacitance of the load capacitor C to be charged is known to be 2mF.

[0048] The control module first plans the charging task. Using the formula I_avg ≈ C * ΔV / ΔT, it calculates: I_avg ≈ 0.002 F * 750 V / 0.5 s = 3 A. Therefore, to complete charging within 500ms, at least approximately 3A of average charging current is required. The control module compares this calculated value (3A) with the safety upper limit (10A), ultimately determining 3A as the maximum allowable charging current for this task and setting it as the new upper limit for the voltage loop controller's output limit.

[0049] Voltage loop controller operation: Initially, the voltage across the load capacitor to be charged is 600V, which differs from the target voltage by -150V. Although the voltage difference is large, due to the constraint of the target charging time (500ms), the target charging current calculated by the voltage loop controller is no longer clamped at 10A, but is instead clamped at 3A by a new, more stringent dynamic limiting. Therefore, the target charging current output by the voltage loop controller to the current loop controller is 3A.

[0050] Current loop controller operation: If the actual charging current is 1A, the current loop controller will detect a positive current deviation of +2A (target 3A - actual 1A). Based on the current difference, the current loop's PID algorithm will output a moderately increased PWM duty cycle (its increase is much smaller than the previous increase when the target was 10A), driving the pre-charge switch to allow the current to rise smoothly from 1A. After rapid adjustment, the current loop will eventually maintain the actual charging current accurately and stably at 3A, entering a constant current charging state.

[0051] Referring to the control methods described above, Figure 7 This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a precharge switch is 50%, as provided in this embodiment of the application. Figure 8 This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a precharge switch is 100%, as provided in this embodiment of the application. Figure 9This refers to the time it takes for the charging voltage to rise to the target charging voltage when the duty cycle of a pre-charge switch is 20%, as provided in the embodiments of this application. The target charging times are set to 0.352S, 0.176S, and 0.879S, respectively. Figures 7-8 As can be seen, if you want to control the target charging time, you only need to adjust the duty cycle of the target pre-charge switch.

[0052] In some embodiments, the precharge switch includes an insulated gate bipolar transistor, and the main charging switch and charging switch include relays.

[0053] In this embodiment, the pre-charging process involves frequent switching actions, specifically controlled by an electrical signal (PWM) output by the control module. This is a contactless switch, eliminating mechanical wear and arcing issues, and its lifespan far exceeds that of mechanical relays, easily withstanding millions or even tens of millions of operations. Therefore, the pre-charging switch can include an insulated-gate bipolar transistor. The main charging switch and charging switch function to maintain the main circuit current for the load capacitor after pre-charging. When the vehicle is running, the main charging switch and charging switch remain closed for extended periods. Furthermore, for devices with the same rated current, the voltage drop and power consumption of a relay in the channel state are typically lower than those of a solid-state switch of the same level. In power supply paths where high-frequency operation is not required, the main charging switch and charging switch can be relays.

[0054] This application also provides a control method for a multi-channel pre-charge circuit, applied to a control module in a multi-channel pre-charge circuit according to the first aspect of this application. The control method includes: Based on the charging demand of the load capacitor to be charged, the duty cycle of the target pre-charge switch in the pre-charge branch connected to the load capacitor to be charged is adjusted to control the power supply to charge the load capacitor to be charged. Each charging control sub-circuit has its input terminal electrically connected to the power supply, and its output terminal configured to be electrically connected to the corresponding load capacitor. Each charging control sub-circuit includes a pre-charge branch and a charging switch connected in parallel with the pre-charge branch. The pre-charge branch includes a pre-charge switch and a pre-charge resistor. The charging voltage across the load capacitor to be charged is acquired, and when the charging voltage indicates that the load capacitor is fully charged, the target pre-charge switch is turned off, and the charging switch connected to the load capacitor to be charged is closed.

[0055] In this embodiment, during the control of the multi-channel pre-charge circuit, combined with Figure 1First, the control module closes the main charging switch, connecting the power supply to multiple pre-charging branches and charging branches where multiple charging switches are located. Then, based on the charging requirements of the load capacitor to be charged, it selects at least one target pre-charging branch from the multiple pre-charging branches and controls the pre-charging switch on the target pre-charging branch to close, so that the power supply can charge the load capacitor to be charged. During the charging process, the control module also acquires the charging voltage across the load capacitor. When the charging voltage across the load capacitor indicates that the load capacitor is fully charged, the target pre-charging switch is closed, and the corresponding charging switch is closed at the same time. This achieves a seamless switching from the current-limiting pre-charging branch to the low-impedance charging branch, which avoids the surge current that may be generated when the power supply directly charges the capacitor and ensures the energy transfer efficiency when the system switches to full power operation.

[0056] In some embodiments, the charging requirement includes a target charging time, and the control method further includes: Before closing the target precharge switch, the maximum allowable charging current is determined based on the target charging time and the capacitance value of the load capacitor to be charged; based on the maximum allowable charging current, the charging current output by the precharge branch, including the target precharge switch, is controlled to be within the range of the maximum allowable charging current.

[0057] In this embodiment, the charging requirement includes a target charging time. Before pre-charging begins, the control method first determines the maximum allowable charging current to complete the charging task based on the target charging time and the capacitance value of the load capacitor. Subsequently, throughout the pre-charging process, the control module ensures that the actual charging current never exceeds the maximum charging current through closed-loop regulation. This method enables charging to be completed within a predetermined time while reducing system losses and thermal stress by limiting unnecessary excessive current.

[0058] In addition, if the control module knows the target charging voltage required for charging, it can also detect the charging voltage across the load capacitor to be charged, compare the charging voltage with the target charging voltage, determine the voltage difference between the charging voltage and the target charging voltage, and based on the voltage difference, obtain the target charging current required to quickly reduce the voltage difference, and then obtain the current charging current for the load capacitor to be charged. Based on the current difference between the charging current and the target charging current, the control module can adjust the pulse width modulation duty cycle of the target precharge switch, thereby changing the on-time of the target precharge switch so that the charging current can quickly reach the target charging current.

[0059] This application embodiment also provides a vehicle, which includes the multi-channel pre-charging circuit of this embodiment and multiple electrical loads. Each electrical load is provided with a load capacitor, and each charging control sub-circuit in the multi-channel pre-charging circuit is electrically connected to the corresponding load capacitor.

[0060] In this embodiment, the load capacitors of multiple electrical loads in the vehicle (such as motor controllers, DC-DC converters, air conditioning compressors, etc.) may have different capacities and different power-on timing requirements. Through the multi-path pre-charging circuit in this embodiment, the control module is allowed to independently select a pre-charging path for each load and set differentiated charging parameters (such as current and time), thereby realizing on-demand power distribution to different loads.

[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0062] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0063] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0064] The foregoing has provided a detailed description of the multi-channel pre-charging circuit, control method, and vehicle provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A multipath precharge circuit, comprising: include: Power supply; Multiple charging control sub-circuits are provided. The input terminal of each charging control sub-circuit is electrically connected to the power supply. The output terminal of each charging control sub-circuit is configured to be electrically connected to the corresponding load capacitor. Each charging control sub-circuit includes a pre-charge branch and a charging switch connected in parallel with the pre-charge branch. The pre-charge branch includes a pre-charge switch and a pre-charge resistor. The control module is electrically connected to the control terminals of the precharge switch and the charging switch, respectively; The control module is configured to adjust the duty cycle of the target precharge switch in the precharge branch connected to the load capacitor based on the charging demand of the load capacitor to be charged, so as to control the power supply to charge the load capacitor to be charged, and turn off the target precharge switch and close the charging switch connected to the load capacitor when the load capacitor to be charged is fully charged.

2. The multi-path pre-charge circuit of claim 1, wherein, It also includes a main charging switch, the first end of which is electrically connected to the power supply, the second end of which is electrically connected to the input end of the plurality of charging control sub-circuits, and the control end of which is electrically connected to the control module; The main charging switch is configured to close in response to a charging signal output by the control module, so that the power supply provides power to the plurality of charging control sub-circuits.

3. The multi-path pre-charge circuit of claim 2, wherein, The pre-charge branch also includes a diode, the positive terminal of which is electrically connected to the second terminal of the main charging switch, the negative terminal of which is electrically connected to the first terminal of the pre-charge switch, the second terminal of the pre-charge switch is electrically connected to the first terminal of the pre-charge resistor, the second terminal of the pre-charge resistor is electrically connected to the first terminal of the load capacitor, and the second terminal of the load capacitor to be charged is electrically connected to the negative terminal of the power supply.

4. The multiplex pre-charge circuit according to claim 1 or 3, wherein The pre-charge branch also includes a current detection unit, which is connected in series between the pre-charge resistor and the load capacitor. A voltage detection unit is connected in parallel across each load capacitor. The current detection unit and the voltage detection unit are electrically connected to the control module. The control module is further configured to adjust the duty cycle of the target precharge switch based on the charging voltage across the load capacitor to be charged detected by the voltage detection unit and the charging current flowing into the load capacitor to be charged detected by the current detection unit.

5. The multi-path pre-charge circuit of claim 4, wherein, The charging requirement of the load capacitor to be charged includes a target charging voltage. The control module includes a voltage loop controller and a current loop controller. The input terminal of the voltage loop controller is electrically connected to the voltage detection unit. The output terminal of the voltage loop controller is electrically connected to the first input terminal of the current loop controller. The second input terminal of the current loop controller is electrically connected to the current detection unit. The output terminal of the current loop controller is electrically connected to the control terminal of the pre-charge switch. The voltage loop controller is configured to determine the target charging current required to charge the load capacitor based on the voltage difference between the target charging voltage and the charging voltage across the load capacitor to be charged, and to output the target charging current to the current loop controller. The current loop controller is configured to generate a pulse width modulation signal output to the target pre-charge switch based on a current difference between the target charging current and the charging current.

6. The multi-path pre-charge circuit of claim 5, wherein, The charging requirement of the to-be-charged load capacitor further includes a target charging time, The control module is further configured to determine a maximum allowed charging current of the to-be-charged load capacitor based on the target charging voltage, the target charging time, and a capacitance value of the to-be-charged load capacitor, and control a charging current output by a pre-charge branch including the target pre-charge switch to be within a range of the maximum allowed charging current.

7. The multi-path pre-charge circuit of claim 2, wherein, The pre-charge switch includes an insulated gate bipolar transistor, and the main charging switch and the charging switch include relays.

8. A control method of a multipath precharge circuit, characterized by, The control method is applied to the multi-channel pre-charge circuit of any one of claims 1-7, and the control method comprises: Based on the charging requirement of the to-be-charged load capacitor, the duty cycle of the target pre-charge switch in the pre-charge branch connected to the to-be-charged load capacitor is adjusted to control the power supply to charge the to-be-charged load capacitor; wherein the input end of each charging control sub-circuit in the plurality of charging control sub-circuits is electrically connected to the power supply, the output end of each charging control sub-circuit is configured to be electrically connected to the corresponding load capacitor, and each charging control sub-circuit includes a pre-charge branch and a charging switch connected in parallel to the pre-charge branch, and the pre-charge branch includes a pre-charge switch and a pre-charge resistor; The charging voltage across the to-be-charged load capacitor is obtained, and the target pre-charge switch is turned off and the charging switch connected to the to-be-charged load capacitor is closed when the charging voltage indicates that the to-be-charged load capacitor is fully charged.

9. The control method according to claim 8, characterized by, The charging requirement includes a target charging time, and the control method further includes: Before controlling the target pre-charge switch to be closed, a maximum allowed charging current is determined based on the target charging time and a capacitance value of the to-be-charged load capacitor; and based on the maximum allowed charging current, a charging current output by a pre-charge branch including the target pre-charge switch is controlled to be within a range of the maximum allowed charging current.

10. A vehicle characterized by comprising: The multi-channel pre-charge circuit of any one of claims 1-7 and a plurality of electrical loads are included, each of the electrical loads is provided with a load capacitor, and each charging control sub-circuit in the multi-channel pre-charge circuit is electrically connected to the corresponding load capacitor.

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