Pre-charging circuit and energy storage converter

Abstract

The invention discloses a pre-charging circuit and an energy storage converter, and relates to the technical field of pre-charging circuits. The controller, the logic control unit and the switch unit are connected in sequence; the switch unit is connected with the direct-current pre-charging circuit and the alternating-current pre-charging circuit, logic judgment of input signals is directly completed through a semiconductor structure in a device by controlling hardware logic of the logic control unit of the driving module, and the response speed is high. The control driving module receives a target control signal issued by the controller, only one control signal exists between the controller and the control driving module from the connection relation and the logic function, and compared with a conventional scheme that the controller outputs two control signals corresponding to the judgment of respective pre-charging circuits respectively, the control driving module has the advantages that the control signals are more stable. The number of ports used by the controller is reduced, the identification process of two control signals is also reduced, and by issuing one target control signal, a plurality of control signals in a conventional scheme can control the pre-charging circuit, control is simplified, and the control circuit is optimized.

Description

Technical Field

[0001] This application relates to the field of pre-charging circuit technology, and in particular to a pre-charging circuit and an energy storage converter. Background Technology

[0002] Commercial and industrial power conversion systems (PCS) are equipped with pre-charge circuits. Before the PCS operates, the bus capacitor needs to be steadily charged to prevent large current surges when the main circuit contactor engages. The primary method is to buffer the DC battery voltage through a pre-charge relay and a pre-charge resistor; a few systems also have an AC pre-charge circuit. When the DC side of the PCS is disconnected from the energy storage battery, the DC bus voltage is 0, or the battery voltage is too low. In this case, an AC pre-charge circuit is needed to charge the DC bus capacitor.

[0003] In circuits that simultaneously support both DC and AC precharge, corresponding precharge resistors are connected. Two control signals are output from the microcontroller unit (MCU), and software controls and determines which precharge mode to use. During precharge, the software-controlled switching process has a relatively slow response time, involving a certain delay in detection, calculation, and instruction issuance.

[0004] Therefore, how to improve response speed when switching precharge methods is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a pre-charging circuit and an energy storage converter to solve the problem of slow response speed caused by switching pre-charging modes in conventional software control that outputs two control signals from a microcontroller.

[0006] To address the aforementioned technical problems, this application provides a pre-charging circuit, including a controller, a control drive module, a DC pre-charging circuit, and an AC pre-charging circuit; wherein the control drive module includes a logic control unit and a switching unit;

[0007] The controller, the logic control unit, and the switching unit are connected in sequence; the switching unit is connected to the DC pre-charge circuit and the AC pre-charge circuit.

[0008] The control drive module is used to receive the target control signal sent by the controller, process the target control signal through the logic control unit, and output a strobe signal to the switching unit to realize the pre-charge conduction of the DC pre-charge circuit and the AC pre-charge circuit.

[0009] On the one hand, the logic control unit includes a first logic control unit and a second logic control unit, and the switching unit includes a first switching unit and a second switching unit;

[0010] The first terminal of each of the first logic control unit and the second logic control unit is connected to the same port of the controller; the third terminal of the first logic control unit is connected to the first terminal of the first switching unit; the second terminal of the first switching unit is connected to the AC pre-charging circuit.

[0011] The second terminal of the second logic control unit is connected to a preset signal and is also connected to the second terminal of the first logic control unit; the third terminal of the second logic control unit is connected to the first terminal of the second switching unit; and the second terminal of the second switching unit is connected to the DC pre-charging circuit.

[0012] On the other hand, the first logic control unit is a first AND gate logic control unit, and the first switching unit is a first switching transistor;

[0013] The first input terminal of the first AND gate logic control unit is connected to the target control signal issued by the controller; the second terminal of the first AND gate logic control unit is connected to a preset signal; the output terminal of the first AND gate logic control unit is connected to the control terminal of the first switch; and the first terminal of the first switch is connected to the AC pre-charging circuit.

[0014] On the other hand, the second logic control unit includes a first NOT gate logic control unit and a second AND gate logic control unit, and the second switching unit is a second switching transistor;

[0015] The input terminal of the first NOT gate logic control unit serves as the second terminal of the second logic control unit and is connected to a preset signal; the output terminal of the first NOT gate logic control unit is connected to the second input terminal of the second AND gate logic control unit.

[0016] The first input terminal of the second AND gate logic control unit serves as the first terminal of the second logic control unit and is connected to the target control signal issued by the controller; the output terminal of the second AND gate logic control unit is connected to the control terminal of the second switch; the first terminal of the second switch is connected to the DC pre-charge circuit.

[0017] On the other hand, the DC pre-charging circuit and the AC pre-charging circuit share a pre-charging resistor.

[0018] On the other hand, the pre-charging circuit also includes a protection circuit;

[0019] The protection circuit is connected to the second terminal of each of the first logic control unit and the second logic control unit;

[0020] The protection circuit is used to output a preset signal to switch to the precharge mode of the AC precharge circuit when the DC precharge circuit is used in the precharge mode and the DC battery voltage is lower than the target battery voltage corresponding to the preset signal.

[0021] On the other hand, the protection circuit includes a first diode, a second diode, a third diode, a fourth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and an isolation unit;

[0022] The first diode and the second diode are connected in reverse series, and the cathode of the first diode is connected to the battery power supply; the second diode, the first resistor, the second resistor, the third resistor, the fourth resistor and the fifth resistor are connected in series in sequence, and the second end of the fifth resistor is grounded;

[0023] The third diode and the fourth diode are connected in parallel, and the anode of the third diode is connected to the second terminal of the fourth resistor and to the first terminal of the isolation unit; the anode of the fourth diode is connected to the second terminal of the fifth resistor; the second terminal of the isolation unit outputs a preset signal and is connected to the second terminals of the first logic control unit and the second logic control unit respectively.

[0024] On the other hand, the protection circuit includes a differential sampling unit, an operational amplifier unit, and a comparator;

[0025] The first terminal of the differential sampling unit is connected to the battery power supply, the second terminal of the differential sampling unit is grounded, and the third terminal of the differential sampling unit is connected to the first terminal of the operational amplifier unit; the second terminal of the operational amplifier unit is connected to the first input terminal of the comparator; the second input terminal of the comparator is connected to the target battery voltage signal corresponding to the preset signal; the output terminal of the comparator outputs the preset signal and is connected to the second terminal of the first logic control unit and the second logic control unit respectively.

[0026] On the other hand, the isolation unit is an optocoupler or a relay.

[0027] To address the aforementioned technical problems, this application also provides an energy storage converter, including the pre-charging circuit described above.

[0028] This application provides a pre-charging circuit. First, the control drive module includes a logic control unit and a switching unit, which are connected sequentially. The switching unit connects the DC pre-charging circuit and the AC pre-charging circuit. Compared to conventional solutions that use software logic to switch the pre-charging modes of the DC and AC pre-charging circuits, where the input signal needs to be acquired by the chip's AD / IO interface, the controller executes the code logic, and finally outputs a control signal, this approach relies on the processor and software, and the response speed is affected by the program's runtime. This application uses hardware logic, such as the logic control unit of the control drive module, to directly perform logical judgments on the input signal through the internal semiconductor structure of the device, outputting the corresponding selection signal. The entire process does not involve software programs and does not require the controller to execute instructions, resulting in a faster response speed. Second, the controller, logic control unit, and switching unit are connected sequentially. The switching unit connects the DC and AC pre-charging circuits, and the logic control unit outputs a selection signal to control the switching unit to turn on and off, thereby achieving the switching of the pre-charging modes of the DC and AC pre-charging circuits. Finally, the control drive module receives the target control signal sent by the controller. Based on the above connection relationship and logical function, there is only one type of control signal between the controller and the control drive module. Compared with the conventional solution where the controller outputs two control signals corresponding to their respective pre-charging circuits, this application reduces the number of controller ports used and also reduces the identification process of the two control signals. By sending one target control signal, the pre-charging circuit can be controlled by multiple control signals in the conventional solution, simplifying control and optimizing the control circuit.

[0029] In addition, this application also provides an energy storage converter that has the same beneficial effects as the pre-charge circuit described above. Attached Figure Description

[0030] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments 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.

[0031] Figure 1 This is a schematic diagram of a pre-charging circuit provided in an embodiment of this application;

[0032] Figure 2 This is a schematic diagram of another pre-charging circuit provided in an embodiment of this application;

[0033] Figure 3 A schematic diagram of a protection circuit provided in an embodiment of this application;

[0034] Figure 4This is a schematic diagram of the internal structure of a protection circuit provided in an embodiment of this application;

[0035] Figure 5 This is a schematic diagram of the internal structure of another protection circuit provided in an embodiment of this application. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0037] The core of this application is to provide a pre-charging circuit and an energy storage converter to solve the problem of slow response speed caused by switching pre-charging modes in conventional software control that outputs two control signals from a microcontroller.

[0038] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] In conventional pre-charging circuits, the DC battery side is buffered by a pre-charging relay and a pre-charging resistor, with a few having an AC pre-charging circuit. Using only DC-side pre-charging can meet the normal operating requirements of PCS equipment, relying on the DC-side battery voltage. In special cases, when the PCS's DC side is disconnected from the energy storage battery, the DC bus voltage is 0, or the battery voltage is too low. In this case, an AC-side pre-charging circuit is needed to charge the DC bus capacitor. Therefore, it is best to have both DC and AC pre-charging capabilities simultaneously. However, DC and AC pre-charging are controlled separately, and the specific pre-charging method used depends entirely on software control and judgment. Software malfunctions can lead to switching errors or no response, resulting in the bus capacitor not charging properly and the PCS equipment failing to start. Software judgment has a certain delay; for example, if the battery suddenly disconnects or the DC-side voltage drops to 0 instantaneously, the software may not have time to react before the main circuit contactor attempts to close, still generating a large current surge that can damage the equipment. To ensure accurate software judgment, the logic must be repeatedly debugged and sensor parameters calibrated. Later, as the equipment ages, the sensor accuracy deteriorates, requiring recalibration. Furthermore, troubleshooting problems on-site, determining whether the issue lies with the software logic or a faulty hardware sensor, is more complicated and delays equipment recovery time. Therefore, the pre-charging circuit provided in this application can solve the aforementioned technical problems.

[0040] Figure 1 This is a schematic diagram of a pre-charging circuit provided in an embodiment of this application, as shown below. Figure 1As shown, it includes a controller 1, a control drive module 2, a DC pre-charge circuit 3, and an AC pre-charge circuit 4; wherein, the control drive module 2 includes a logic control unit 5 and a switching unit 6;

[0041] Controller 1, logic control unit 5 and switching unit 6 are connected in sequence; switching unit 6 is connected to DC pre-charge circuit 3 and AC pre-charge circuit 4;

[0042] The control drive module 2 is used to receive the target control signal sent by the controller 1, process the target control signal through the logic control unit 5, and output the selection signal to the switching unit 6 to realize the pre-charge conduction of the DC pre-charge circuit 3 and the AC pre-charge circuit 4.

[0043] Specifically, the controller is connected to a logic control unit, which in turn is connected to a switching unit. The switching unit is connected to both the DC pre-charge circuit and the AC pre-charge circuit. Compared to conventional solutions where the controller outputs two control signals, each connected to its respective control drive module, and each control drive module connected to its corresponding pre-charge circuit, this embodiment uses a single target control signal. This target control signal is connected to the same control drive module. The logic control unit of the control drive module processes the target control signal and outputs a selection signal to the switching unit. The switching unit then connects to both the DC and AC pre-charge circuits, enabling pre-charge activation of both circuits.

[0044] The logic control unit is implemented through hardware logic, which can be based on logic gate signals or other hardware control signals. If logic gate signals are used, the specific NAND gates or other logic devices are not limited here, as long as they can enable pre-charging in a pre-charging mode at any given time. Regarding the switching unit, it can be of different switch types, or exist as a switching transistor for on / off switching; there are no limitations here.

[0045] The controller provided in this embodiment outputs a single target control signal, which means the controller needs to open one port signal for the pre-charging circuit, compared to the conventional two port signals, such as a first control signal and a second control signal. The first control signal controls the DC pre-charging circuit, and the second control signal controls the AC pre-charging circuit. This saves on the number of ports on the controller and avoids the need for software logic-based judgments. Furthermore, the controller not only issues the pre-charging logic instructions (target control signal), but also collects signals such as the DC-side battery voltage, AC-side grid voltage, and bus capacitor voltage in real time, while simultaneously monitoring the temperature and current of the pre-charging resistor to determine whether pre-charging is complete. This embodiment uses a single control signal to control both the DC and AC pre-charging circuits simultaneously, simplifying control.

[0046] Regarding the control drive signal, the system receives the target control signal, transmits and activates it, and outputs a control signal sufficient to drive the pre-charge circuit. The DC pre-charge circuit not only achieves current-limited charging between the battery and the bus capacitor, but also, after pre-charging is complete, allows the battery to directly supply power to the bus by short-circuiting the pre-charge resistor. The AC pre-charge circuit draws AC voltage from the grid, rectifies it into DC, and then charges the bus capacitor; it is suitable for scenarios where DC pre-charging cannot operate, such as when the battery is disconnected or undervoltage.

[0047] This application provides a pre-charging circuit. First, the control drive module includes a logic control unit and a switching unit, which are connected sequentially. The switching unit connects the DC pre-charging circuit and the AC pre-charging circuit. Compared to conventional solutions that use software logic to switch the pre-charging modes of the DC and AC pre-charging circuits, the input signal needs to be acquired by the chip's analog-to-digital (AD) / input-output (IO) interface first, then the controller executes the code logic, and finally outputs a control signal. This relies on the processor and software, and the response speed is affected by the program's runtime. This application uses hardware logic, such as the logic control unit of the control drive module, to directly complete the logical judgment of the input signal through the internal semiconductor structure of the device and output the corresponding selection signal. The entire process does not involve software programs and does not require the controller to execute instructions, resulting in a faster response speed. Second, the controller, logic control unit, and switching unit are connected sequentially. The switching unit connects the DC and AC pre-charging circuits. The logic control unit outputs a selection signal to control the switching unit to turn on and off, thereby achieving the switching of the pre-charging modes of the DC and AC pre-charging circuits. Finally, the control drive module receives the target control signal sent by the controller. Based on the above connection relationship and logical function, there is only one type of control signal between the controller and the control drive module. Compared with the conventional solution where the controller outputs two control signals corresponding to their respective pre-charging circuits, this application reduces the number of controller ports used and also reduces the identification process of the two control signals. By sending one target control signal, the pre-charging circuit can be controlled by multiple control signals in the conventional solution, simplifying control and optimizing the control circuit.

[0048] In some embodiments, the logic control unit includes a first logic control unit and a second logic control unit, and the switching unit includes a first switching unit and a second switching unit;

[0049] The first terminal of each of the first logic control unit and the second logic control unit is connected to the same port of the controller; the third terminal of the first logic control unit is connected to the first terminal of the first switching unit; the second terminal of the first switching unit is connected to the AC pre-charging circuit.

[0050] The second terminal of the second logic control unit is connected to a preset signal and is also connected to the second terminal of the first logic control unit; the third terminal of the second logic control unit is connected to the first terminal of the second switching unit; and the second terminal of the second switching unit is connected to the DC pre-charging circuit.

[0051] Specifically, the first logic control unit is used in conjunction with the first switch unit, and the second logic control unit is used in conjunction with the second switch unit.

[0052] The first terminal of each of the first and second logic control units is connected to the same port of the controller to receive the target control signal sent by the controller, thus saving the number of ports on the controller. The third terminal of the first logic control unit is connected to the first terminal of the first switching unit to output a control signal to control the on and off states of the first switching unit. The second terminal of the first switching unit is connected to the AC pre-charging circuit, and the on and off states of the first switching unit indicate whether the pre-charging mode of the AC pre-charging circuit is used.

[0053] The second terminal of the second logic control unit receives a preset signal and is connected to the second terminal of the first logic control unit. Regardless of the logic control method, two input signals are required: one for the second logic control unit and one for the preset signal. Similarly, the first logic control unit also has two input signals: one for the target control signal and one for the preset signal. The third terminal of the second logic control unit is connected to the first terminal of the second switching unit; the second terminal of the second switching unit is connected to the DC pre-charge circuit. The second logic control unit outputs a control signal to control the on / off state of the second switching unit. The on / off state of the second switching unit indicates whether the pre-charge mode of the DC pre-charge circuit is used.

[0054] The logic control units and switching units provided in this embodiment are connected accordingly, respectively controlling the pre-charging modes of the AC pre-charging circuit and the DC pre-charging circuit. It supports both DC and AC pre-charging paths, preventing the device from failing to start due to a single pre-charging failure. This connection allows for precise selection of the corresponding pre-charging circuit, with independent control of the circuit's conduction via the switching units. This avoids conflicts caused by simultaneous DC / AC pre-charging and prevents large current surges due to incorrect pre-charging mode selection, protecting components such as pre-charging resistors, capacitors, and contactors, and reducing the device failure rate.

[0055] In some embodiments, Figure 2 A schematic diagram of another pre-charging circuit provided in the embodiments of this application is shown below. Figure 2 As shown, the first logic control unit is the first AND gate logic control unit 7, and the first switching unit 6 is the first switching transistor Q1;

[0056] The first input terminal of the first AND gate logic control unit 7 is connected to the target control signal issued by the controller 1; the second terminal of the first AND gate logic control unit 7 is connected to the preset signal; the output terminal of the first AND gate logic control unit 7 is connected to the control terminal of the first switch Q1; the first terminal of the first switch Q1 is connected to the AC pre-charging circuit 3.

[0057] Specifically, the first logic control unit is a first AND gate logic control unit. If the target control signal is "1" and the preset signal is "1", the output of the first AND gate logic control unit is at a high level, and the control terminal of the first switch is input with a high level. At this time, the first switch is turned on to connect the pre-charging mode of the AC pre-charging circuit. If the target control signal is "1" and the preset signal is "0", the output of the first AND gate logic control unit is at a low level, and the control terminal of the first switch is input with a low level. At this time, the first switch is turned off to disconnect the pre-charging mode of the AC pre-charging circuit.

[0058] This embodiment provides a method to control the pre-charging mode of the AC pre-charging circuit through the connection between the AND gate and the first switching transistor. The AND gate logic control unit is hardware logic; a high-level input signal instantly outputs a conduction signal to the switching transistor—eliminating the need for software detection, calculation, and instruction issuance. This allows for rapid initiation of AC pre-charging in the instant of a sudden drop in DC-side voltage, avoiding the large current surge during main circuit closing. The AND gate logic is an interlocking mechanism; AC pre-charging will only conduct when both the DC-side voltage is zero and pre-charging initiation conditions are met. This prevents the situation where AC pre-charging is mistakenly activated despite DC-side power, eliminating the risk of conflict in the pre-charging circuit at the hardware level.

[0059] In some embodiments, such as Figure 2 As shown, the second logic control unit includes a first NOT gate logic control unit 8 and a second AND gate logic control unit 9, and the second switching unit is a second switching transistor Q2;

[0060] The input terminal of the first NOT gate logic control unit 8 serves as the second terminal of the second logic control unit and is connected to a preset signal; the output terminal of the first NOT gate logic control unit 8 is connected to the second input terminal of the second AND gate logic control unit 9.

[0061] The first input terminal of the second AND gate logic control unit 9 serves as the first terminal of the second logic control unit and is connected to the target control signal issued by the controller; the output terminal of the second AND gate logic control unit 9 is connected to the control terminal of the second switch Q2; the first terminal of the second switch Q2 is connected to the DC pre-charge circuit 4.

[0062] Specifically, the second logic control unit comprises a second AND gate logic control unit and a first NOT gate logic control unit. If the target control signal is "1" and the preset signal is "1", the preset signal is inverted by the first NOT gate logic control unit to obtain "0", then passed through the second AND gate logic control unit and ANDed with the target control signal to obtain a low level. At this time, the output of the second AND gate logic control unit is low, and the control terminal of the second switch receives a low level, turning off the second switch to disconnect the pre-charge mode of the DC pre-charge circuit. If the target control signal is "1" and the preset signal is "0", the preset signal is inverted by the first NOT gate logic control unit to obtain "1", then passed through the second AND gate logic control unit and ANDed with the target control signal to obtain a high level. At this time, the output of the second AND gate logic control unit is high, and the control terminal of the second switch receives a high level, turning on the second switch to connect the pre-charge mode of the DC pre-charge circuit.

[0063] Therefore, compared with the above embodiments, only one pre-charging mode can exist at the same time.

[0064] This embodiment controls the DC pre-charge circuit through the connection between a NOT gate, an AND gate, and a second switch. The NOT gate first inverts the preset signal and then performs an AND gate logic with the target control signal. Only when the AC pre-charge circuit is not activated and the voltage of the preset signal on the DC side is normal will a conduction signal be output to the second switch. This hardware logic fundamentally eliminates the conflict of simultaneous conduction of DC and AC pre-charge, without relying on software interlocks, thus maximizing safety. The hardware logic is completed automatically, without the need for additional software determination of whether the current scenario is AC or DC, making the pre-charge system highly adaptable to different scenarios.

[0065] In conventional solutions, different pre-charge resistors are used for different pre-charge modes. Unlike power resistors, this pre-charge system uses high-power aluminum-cased resistors or multiple sets of cement resistors, which is more expensive than ordinary power resistors. In some embodiments, the DC pre-charge circuit and the AC pre-charge circuit share a single pre-charge resistor.

[0066] Specifically, such as Figure 2As shown, the AC pre-charging circuit 3 includes a first relay K1, a first rectifier bridge U1, a fifth diode D5, and a sixth diode D6. Diodes D5 and D6 serve to prevent reverse connection. The first relay K1 controls the on / off state of the AC pre-charging circuit 3. When AC pre-charging is required, the first relay K1 is energized, connecting the AC power from the R and S phases of the power grid to the circuit. After pre-charging is complete, the first relay K1 is de-energized, disconnecting the AC side from the busbar to prevent long-term energization. The resistor inside the first relay K1 acts as a surge suppressor. At the moment the resistor is energized, the grid voltage will generate a surge current on the contacts inside the first relay K1. This resistor limits the surge current, protecting the contacts from burning and extending the contactor's lifespan. The first rectifier bridge U1 converts AC voltage to DC voltage. The R and S phase AC power input from the grid is converted into DC power after passing through the first rectifier bridge U1 (which has a bridge structure with four diodes inside), providing DC power for subsequent charging of the busbar capacitors (capacitors between BUS+ / -). Regarding the fifth diode D5 and the sixth diode D6, they are unidirectional and prevent reverse current. The rectified DC current flows to the bus capacitor through the diodes, while preventing the current on the bus side from flowing back into the AC precharge circuit (such as the battery voltage during DC precharge), thus avoiding circuit conflicts or component damage.

[0067] The DC pre-charging circuit 4 includes a second relay K2. The output terminal of the second relay K2 and the cathode of the sixth diode D6 of the AC pre-charging circuit are both connected to the first terminal of the pre-charging resistor R11. The second terminal of the pre-charging resistor R11 is connected to the bus capacitor.

[0068] This embodiment provides a single pre-charge resistor for both the DC and AC pre-charge circuits, eliminating the need for separate pre-charge resistors for each circuit. This saves PCB layout space and reduces the cost of the pre-charge resistors. It also avoids additional fault points caused by separate pre-charge resistors, simplifying maintenance by eliminating the need to check the status of the two resistors. Sharing a single resistor means that the current-limiting parameters (resistance and power) for both DC and AC pre-charge are unified, eliminating the need to adjust the matching of the two resistors separately and simplifying the pre-charge current control logic.

[0069] In some embodiments, Figure 3 A schematic diagram of a protection circuit provided in an embodiment of this application is shown below. Figure 3 As shown, the pre-charge circuit also includes a protection circuit 10;

[0070] Protection circuit 10 is connected to the second terminal of the first logic control unit 7 and the second logic control unit 9 respectively;

[0071] The protection circuit 10 is used to output a preset signal to switch to the precharge mode of the AC precharge circuit 3 when the DC precharge circuit 4 is used in the precharge mode and the DC battery voltage is lower than the target battery voltage corresponding to the preset signal.

[0072] Specifically, if the DC battery voltage is lower than the target battery voltage corresponding to the preset signal in the precharge mode of the DC precharge circuit, it indicates that the current DC battery voltage is insufficient and the DC precharge cannot charge the bus capacitor to a sufficient voltage. In this case, the AC precharge circuit will automatically switch to the AC precharge mode as a backup. This is achieved by the protection circuit detecting this situation in time, outputting a preset signal, and switching to the AC precharge circuit precharge mode.

[0073] It should be noted that while the above monitoring can also be achieved using software, hardware circuits such as protection circuits have a faster detection response than software. They can instantly transmit the low voltage signal to the first AND gate logic control unit, switching to AC pre-charging immediately without delaying the pre-charging progress.

[0074] This embodiment provides a system where both DC and AC pre-charging circuits exist simultaneously. When using the DC pre-charging circuit, a protection circuit detects that the DC battery voltage is below a threshold. The threshold determination for voltage detection is completed by the protection circuit (hardware), eliminating the need for continuous sampling and calculation by software. This reduces software resource consumption and avoids delays or errors in software detection. The system can trigger a signal as soon as the battery voltage drops below the threshold, rather than waiting until the battery voltage is too low or the DC pre-charging process has completely failed. This avoids abnormal loop current caused by forcibly pre-charging a low-voltage battery (such as excessive current burning out the pre-charging resistor) and also prevents over-discharge of the battery.

[0075] In some embodiments, Figure 4 This is a schematic diagram of the internal structure of a protection circuit provided in an embodiment of this application, as shown below. Figure 4 As shown, the protection circuit 10 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and an isolation unit 11.

[0076] The first diode D1 and the second diode D1 are connected in reverse series, and the cathode of the first diode D1 is connected to the battery power supply; the second diode D1, the first resistor R1, the second resistor R2, the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are connected in series in sequence, and the second end of the fifth resistor R5 is grounded.

[0077] The third diode D3 and the fourth diode D4 are connected in parallel, and the anode of the third diode D3 is connected to the second terminal of the fourth resistor R4 and to the first terminal of the isolation unit 11; the anode of the fourth diode D4 is connected to the second terminal of the fifth resistor R5; the second terminal of the isolation unit 11 outputs a preset signal and is connected to the second terminal of the first logic control unit and the second logic control unit respectively.

[0078] Specifically, the DC battery measurement circuit employs a three-stage protection system: reverse cutoff, voltage divider sampling, and overvoltage clamping. The first and second diodes are connected in reverse series to prevent reverse battery connection and reverse flow of the bus voltage. The voltage divider sampling stage (from the first to the fourth resistor) uses series resistors to divide the battery voltage, which can then be used in conjunction with the sampling voltage signal from the protection circuit to detect when the DC battery voltage is lower than the target battery voltage. The overvoltage clamping stage (the fifth resistor, the third diode, and the fourth diode) is connected in parallel at the ends of the voltage divider resistors. The third and fourth diodes act as Zener diodes; when the battery voltage is too high, the Zener diodes break down and conduct, clamping the voltage to a safe value and protecting the subsequent circuitry.

[0079] When the DC battery voltage is lower than the target battery voltage corresponding to the preset signal, the isolation unit disconnects, and the output preset signal is 1. At this time, the DC-side pre-charging circuit cannot work. When the DC battery voltage is sufficient, that is, greater than or equal to the target battery voltage corresponding to the preset signal, the isolation unit connects, and the output preset signal is 0. At this time, the DC-side pre-charging circuit works.

[0080] This embodiment provides a simultaneous presence of both DC and AC pre-charging circuits. When using the DC pre-charging circuit, a protection circuit detects that the DC battery voltage is below a threshold. The voltage divider resistor can stably acquire the battery voltage. Combined with hardware threshold judgment, this is more resistant to interference than a single sensor detection, avoiding incorrect pre-charging mode switching caused by misjudged battery voltage. Voltage divider sampling can monitor the voltage in real time. Once it falls below the threshold, a signal is immediately triggered to switch to AC pre-charging—preventing battery over-discharge (protecting battery life) and preventing the large current of DC pre-charging under low voltage from impacting the pre-charging resistor and contactor. The voltage divider signal can be directly connected to the isolation unit without relying on software calculations, resulting in a faster response speed. It can instantly start AC pre-charging when the battery voltage drops sharply, avoiding PCS failure.

[0081] In some embodiments, the isolation unit is an optocoupler or a relay.

[0082] Specifically, the input terminal of the optocoupler serves as the first terminal of the isolation unit; the output terminal of the optocoupler serves as the second terminal of the isolation unit; or, the first terminal of the relay serves as the first terminal of the isolation unit; and the second terminal of the relay serves as the second terminal of the isolation unit.

[0083] The isolation unit acts as a hardware switch for the voltage threshold. When the DC battery voltage is lower than the target battery voltage corresponding to the preset signal, the isolation unit is disconnected, and the preset signal output is 1. At this time, the DC-side pre-charging circuit cannot operate. When the DC battery voltage is sufficient, that is, greater than or equal to the target battery voltage corresponding to the preset signal, the isolation unit is connected, and the preset signal output is 0. At this time, the DC-side pre-charging circuit operates.

[0084] Optocouplers / relays can isolate the high-voltage circuit on the battery side from the low-voltage circuit on the precharge control side, avoiding high-voltage / surge interference on the battery side, while preventing low-voltage faults on the control side from affecting the battery side.

[0085] like Figure 4 As shown, the optocoupler Q3 is an isolation unit. Optocouplers are purely electronic devices with a switching response speed in the microsecond range (an order of magnitude faster than the milliseconds of relays). They can output signals instantly when the battery voltage drops sharply, making them more suitable for pre-charge scenarios with high response speed requirements. Optocouplers have no physical contacts, eliminating the problems of contact oxidation and burning. Their lifespan is much longer than relays under long-term, high-frequency use (e.g., multiple pre-charge switching sessions per day), reducing maintenance costs associated with component replacement. Optocouplers are chip-level devices, much smaller than relays, saving PCB board space. Furthermore, the current driving the optocoupler is very small (milliamperes), consuming less power than driving a relay coil, making them suitable for highly integrated, power-sensitive PCS devices. Optocouplers provide opto-electric conversion isolation, offering better electromagnetic compatibility (EMC) than relays, reducing the impact of strong electrical interference from the battery side on the control side signal, making them particularly suitable for industrial scenarios with complex electromagnetic environments.

[0086] The relay isolation unit allows the relay contacts to directly control high-voltage circuits (such as the main circuit for DC pre-charging). It can transmit 0 / 1 control signals and even function directly as a switching device for the DC pre-charging circuit—suitable for commercial and industrial energy storage scenarios with high battery voltage and large pre-charging current (e.g., hundreds of volts and tens of amps). The relay contacts physically switch on and off, outputting dry contact signals (independent of the power supply), and can adapt to control circuits with different voltage levels (e.g., 24V on the control side and 500V on the battery side), offering greater compatibility. The relay provides audible / status indicators of physical contact operation, allowing for quick assessment of the isolation unit's operating status during on-site maintenance, making troubleshooting more intuitive.

[0087] The isolation unit provided in this embodiment is an optocoupler or a relay. It eliminates the need for software to determine whether the voltage meets the standard; the hardware state of the isolation unit directly determines whether DC pre-charging can operate. When the battery voltage is insufficient, the hardware forcibly disconnects the pre-charging permission, completely avoiding the risk of low-voltage pre-charging due to software misjudgment, making it more reliable than pure software control. The isolation unit directly outputs a preset 0 / 1 signal; the control side only needs to recognize this level, eliminating the need to write complex voltage sampling and threshold comparison code. Furthermore, it avoids repeated calibration of software parameters during later debugging, making it more convenient.

[0088] In some embodiments, Figure 5 A schematic diagram of the internal structure of another protection circuit provided in the embodiments of this application is shown below. Figure 5 As shown, the protection circuit 10 includes a differential sampling unit 12, an operational amplifier unit 13, and a comparator 14;

[0089] The first terminal of the differential sampling unit 12 is connected to the battery power supply, the second terminal of the differential sampling unit 12 is grounded, and the third terminal of the differential sampling unit 12 is connected to the first terminal of the operational amplifier unit 13. The second terminal of the operational amplifier unit 13 is connected to the first input terminal of the comparator 14. The second input terminal of the comparator 14 is connected to the target battery voltage signal corresponding to the preset signal. The output terminal of the comparator 14 outputs the preset signal and is connected to the second terminal of the first logic control unit and the second logic control unit, respectively.

[0090] Specifically, and Figure 4 The protection circuits are different; the analog-to-digital converter (ADC) uses sampling + operational amplifier + comparator. Figure 5 The differential sampling unit acquires the voltages of battery B+ and battery B- in a differential manner, which can cancel common-mode interference (such as electromagnetic noise on the battery side) and obtain the true battery voltage more accurately. The operational amplifier unit amplifies the small voltage signal sampled differentially (for example, if the battery voltage is 500V, it may only be 5V after sampling), improving the signal-to-noise ratio and allowing the subsequent comparator to more accurately identify voltage changes. The comparator performs a hardware comparison between the voltage signal amplified by the operational amplifier unit and the target battery voltage signal corresponding to the preset signal. When the DC battery voltage is lower than the target battery voltage corresponding to the preset signal, the preset signal 1 is output, and the DC-side pre-charge circuit cannot work. When the DC battery voltage is sufficient, that is, greater than or equal to the target battery voltage corresponding to the preset signal, the preset signal output by the comparator is 0, and the DC-side pre-charge circuit works.

[0091] The protection circuit provided in this embodiment, which combines ADC sampling, operational amplifier, and comparator, effectively suppresses interference through the combination of differential sampling and operational amplifier amplification. This results in higher accuracy than simple resistor-divided voltage sampling, preventing misjudgment of battery voltage (e.g., misjudging a normal voltage as a low voltage). The comparator, a hardware device, has a voltage comparison response speed in the microsecond range, enabling it to instantly trigger protection when the battery voltage drops sharply.

[0092] Furthermore, this application also provides an energy storage converter, including the aforementioned pre-charging circuit.

[0093] For an introduction to the energy storage converter provided in this application, please refer to the above method embodiments. This application will not repeat the details here, as it has the same beneficial effects as the above pre-charging circuit.

[0094] The foregoing has provided a detailed description of a pre-charging circuit and an energy storage converter provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of this application.

[0095] It should also be noted that, in this specification, 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 apparatus 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 apparatus. 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 apparatus that includes the element.

Claims

1. A pre-charging circuit, characterized in that, It includes a controller, a control drive module, a DC pre-charge circuit, and an AC pre-charge circuit; wherein, the control drive module includes a logic control unit and a switching unit; The controller, the logic control unit, and the switching unit are connected in sequence; the switching unit is connected to the DC pre-charge circuit and the AC pre-charge circuit. The control drive module is used to receive the target control signal sent by the controller, process the target control signal through the logic control unit, and output a strobe signal to the switching unit to realize the pre-charge conduction of the DC pre-charge circuit and the AC pre-charge circuit.

2. The pre-charging circuit according to claim 1, characterized in that, The logic control unit includes a first logic control unit and a second logic control unit, and the switching unit includes a first switching unit and a second switching unit; The first terminal of each of the first logic control unit and the second logic control unit is connected to the same port of the controller; the third terminal of the first logic control unit is connected to the first terminal of the first switching unit; the second terminal of the first switching unit is connected to the AC pre-charging circuit. The second terminal of the second logic control unit is connected to a preset signal and is also connected to the second terminal of the first logic control unit; the third terminal of the second logic control unit is connected to the first terminal of the second switching unit; and the second terminal of the second switching unit is connected to the DC pre-charging circuit.

3. The pre-charging circuit according to claim 2, characterized in that, The first logic control unit is a first AND gate logic control unit, and the first switching unit is a first switching transistor; The first input terminal of the first AND gate logic control unit is connected to the target control signal issued by the controller; the second terminal of the first AND gate logic control unit is connected to a preset signal; the output terminal of the first AND gate logic control unit is connected to the control terminal of the first switch; and the first terminal of the first switch is connected to the AC pre-charging circuit.

4. The pre-charging circuit according to claim 2, characterized in that, The second logic control unit includes a first NOT gate logic control unit and a second AND gate logic control unit, and the second switching unit is a second switching transistor; The input terminal of the first NOT gate logic control unit serves as the second terminal of the second logic control unit and is connected to a preset signal; the output terminal of the first NOT gate logic control unit is connected to the second input terminal of the second AND gate logic control unit. The first input terminal of the second AND gate logic control unit serves as the first terminal of the second logic control unit and is connected to the target control signal issued by the controller; the output terminal of the second AND gate logic control unit is connected to the control terminal of the second switch; the first terminal of the second switch is connected to the DC pre-charge circuit.

5. The pre-charging circuit according to claim 1, characterized in that, The DC pre-charging circuit and the AC pre-charging circuit share a common pre-charging resistor.

6. The pre-charging circuit according to any one of claims 2 to 4, characterized in that, The pre-charging circuit also includes a protection circuit. The protection circuit is connected to the second terminal of each of the first logic control unit and the second logic control unit; The protection circuit is used to output a preset signal to switch to the precharge mode of the AC precharge circuit when the DC precharge circuit is used in the precharge mode and the DC battery voltage is lower than the target battery voltage corresponding to the preset signal.

7. The pre-charging circuit according to claim 6, characterized in that, The protection circuit includes a first diode, a second diode, a third diode, a fourth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and an isolation unit; The first diode and the second diode are connected in reverse series, and the cathode of the first diode is connected to the battery power supply. The second diode, the first resistor, the second resistor, the third resistor, the fourth resistor, and the fifth resistor are connected in series, with the second terminal of the fifth resistor grounded. The third diode and the fourth diode are connected in parallel, and the anode of the third diode is connected to the second terminal of the fourth resistor and to the first terminal of the isolation unit; the anode of the fourth diode is connected to the second terminal of the fifth resistor; the second terminal of the isolation unit outputs a preset signal and is connected to the second terminals of the first logic control unit and the second logic control unit respectively.

8. The pre-charging circuit according to claim 6, characterized in that, The protection circuit includes a differential sampling unit, an operational amplifier unit, and a comparator; The first terminal of the differential sampling unit is connected to the battery power supply, the second terminal of the differential sampling unit is grounded, and the third terminal of the differential sampling unit is connected to the first terminal of the operational amplifier unit; the second terminal of the operational amplifier unit is connected to the first input terminal of the comparator; the second input terminal of the comparator is connected to the target battery voltage signal corresponding to the preset signal; the output terminal of the comparator outputs the preset signal and is connected to the second terminal of the first logic control unit and the second logic control unit respectively.

9. The pre-charging circuit according to claim 7, characterized in that, The isolation unit is an optocoupler or a relay.

10. An energy storage converter, characterized in that, Includes the pre-charging circuit described in any one of claims 1 to 9.

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