Precharge circuit

Abstract

A pre-charge circuit, comprising a power supply switch (11), a driving switch circuit (14), a switch circuit (12), an input power supply (10), an internal circuit (13), a charging circuit (15); a first output end of the input power supply is connected with a first end of the power supply switch, a second end of the power supply switch is connected with a first end of the switch circuit and a first end of the internal circuit respectively, a second end of the switch circuit is connected with a second end of the input power supply and a first end of the driving switch circuit respectively, a third end of the switch circuit is connected with a second end of the driving switch circuit, a third end of the driving switch circuit is connected with a second end of the internal circuit and a first end of the charging circuit respectively, a fourth end of the driving switch circuit is connected with a second end of the charging circuit, and a third end of the charging circuit is connected with the second end of the input power supply; the input power supply is used for charging the internal circuit through the power supply switch and the charging circuit when the power supply switch is closed. The pre-charge circuit can avoid current impact caused by connecting the device to a high-voltage system.

Description

Technical Field

[0001] This application relates to the field of electrical technology, and more particularly to a pre-charging circuit. Background Technology

[0002] In recent years, with the development of new energy vehicles, they have become a new strategic industry for the country. Inside a car, there is a high-voltage direct current (HVDC) system. This system contains a HVDC input power supply and many high-voltage electrical devices. Capacitors for filtering are installed at the input ports of these devices. However, before the electrical devices are connected to the HVDC system, the voltage across the capacitors is zero. At the instant the devices are connected, the extremely high voltage difference between the inside and outside of the system creates a huge inrush current. This surge current not only impacts the entire system but can also damage the power supply switches of the electrical devices.

[0003] To improve this situation, a pre-charging circuit is usually added to protect the power supply switch. In common high-voltage DC systems, a pre-charging circuit is connected in parallel across the two ends of the power supply switch. This pre-charging circuit contains a relay. Although this pre-charging circuit can protect the power supply switch, the relay requires a dedicated control circuit to close, which leads to a complex circuit structure. At the same time, the relay is also relatively large, which is not conducive to the overall layout. Summary of the Invention

[0004] Based on this, this application provides a pre-charging circuit that can not only charge the capacitors in the internal circuit, but also connect to high-voltage DC after a certain delay, i.e. when the voltage difference between the inside and outside is small. This can effectively avoid the current surge when the device is connected to the high-voltage system, thus protecting the power supply switch and the electrical equipment.

[0005] In a first aspect, embodiments of this application provide a pre-charging circuit, which includes a power supply switch, a drive switch circuit, a switch circuit, an input power supply, an internal circuit, and a charging circuit.

[0006] The first output terminal of the input power supply is connected to the first terminal of the power supply switch. The second terminal of the power supply switch is connected to the first terminal of the switch circuit and the first terminal of the internal circuit. The second terminal of the switch circuit is connected to the second terminal of the input power supply and the first terminal of the drive switch circuit. The third terminal of the switch circuit is connected to the second terminal of the drive switch circuit. The third terminal of the drive switch circuit is connected to the second terminal of the internal circuit and the first terminal of the charging circuit. The fourth terminal of the drive switch circuit is connected to the second terminal of the charging circuit. The third terminal of the charging circuit is connected to the second terminal of the input power supply.

[0007] When the power supply switch is closed, the input power supply charges the internal circuit through the power supply switch and the charging circuit; when the voltage of the internal circuit is greater than a preset threshold, the switch circuit controls the drive switch circuit to be in working state, and the input power supply supplies power to the internal circuit through the power supply switch and the drive switch circuit.

[0008] In one possible implementation, the drive switch circuit includes: a drive switch and a first resistor;

[0009] The first end of the drive switch is connected to the second end of the input power supply. The second end of the drive switch is connected to the third end of the switch circuit and the first end of the first resistor. The third end of the drive switch is connected to the second end of the internal circuit and the first end of the charging circuit. The second end of the first resistor is connected to the charging circuit.

[0010] In one possible implementation, the switching circuit includes: a second resistor, a first switching circuit, and a second switching circuit;

[0011] The first end of the second resistor is connected to the second end of the power supply switch. The second end of the second resistor is connected to the first end of the first switch circuit and the first end of the second switch circuit. The second end of the first switch circuit is connected to the second end of the input power supply, the second end of the second switch circuit, and the first end of the drive switch. The third end of the second switch circuit is connected to the second end of the drive switch and the first end of the first resistor. The fourth end of the second switch circuit is connected to the third end of the first switch circuit.

[0012] In one possible implementation, the first switching circuit includes: a first switching transistor, a third resistor, a fourth resistor, a first Zener diode, and a first capacitor;

[0013] The first end of the third resistor is connected to the second end of the second resistor and the first end of the second switching circuit, respectively. The second end of the third resistor is connected to the first end of the first capacitor, the cathode of the first Zener diode, the first end of the fourth resistor, and the gate of the first switching transistor, respectively. The second end of the first capacitor is connected to the anode of the first Zener diode, the second end of the fourth resistor, the source of the first switching transistor, the second end of the input power supply, and the second end of the second switching circuit, respectively. The drain of the first switching transistor is connected to the third end of the second switching circuit.

[0014] In one possible implementation, the second switching circuit includes: a fifth resistor, a sixth resistor, a second Zener diode, and a second switching transistor;

[0015] The first end of the fifth resistor is connected to the second end of the second resistor and the first end of the third resistor, respectively. The second end of the fifth resistor is connected to the drain of the first switching transistor, the cathode of the second Zener diode, the first end of the sixth resistor, and the gate of the second switching transistor, respectively. The anode of the second Zener diode is connected to the second end of the sixth resistor, the source of the second switching transistor, the second end of the input power supply, and the first end of the drive switch, respectively. The drain of the second switching transistor is connected to the first end of the first resistor and the second end of the drive switch, respectively.

[0016] In one possible implementation, the charging circuit includes: a first diode, a second diode, a third diode, and a seventh resistor;

[0017] The first end of the seventh resistor is connected to the third end of the drive switch and the second end of the internal circuit. The second end of the seventh resistor is connected to the anode of the first diode. The cathode of the first diode is connected to the anode of the second diode and the second end of the first resistor. The cathode of the second diode is connected to the anode of the third diode. The cathode of the third diode is connected to the second end of the input power supply, the source of the second switching transistor, and the first end of the drive switch.

[0018] In one possible implementation, the drive switch is a semiconductor thyristor;

[0019] The first switch and the second switch are metal-oxide-semiconductor field-effect transistors.

[0020] In one possible implementation, the input power source is a DC power source.

[0021] The circuit provided in this application embodiment can not only charge the capacitor in the internal circuit, but also connect to high voltage DC after a certain delay, that is, when the voltage difference between the inside and outside is small. This can effectively avoid the current surge when the device is connected to the high voltage system, and protect the power supply switch and the electrical equipment. Attached Figure Description

[0022] The accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below.

[0023] Figure 1 This is a schematic diagram of a pre-charging circuit provided in an embodiment of this application;

[0024] Figure 2 This is another structural schematic diagram of a pre-charging circuit provided in an embodiment of this application;

[0025] Figure 3This is another schematic diagram of a pre-charging circuit provided in an embodiment of this application. Detailed Implementation

[0026] 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 a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0027] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] Please see Figure 1 , Figure 1 This is a schematic diagram of a pre-charging circuit provided in this application. Figure 1 As shown, the pre-charging circuit includes an input power supply 10, a power supply switch 11, a switching circuit 12, an internal circuit 13, a drive switching circuit 14, and a charging circuit 15.

[0030] The first output terminal of the input power supply 10 is connected to the first terminal of the power supply switch 11. The second terminal of the power supply switch 11 is connected to the first terminal of the switch circuit 12 and the first terminal of the internal circuit 13. The second terminal of the switch circuit 12 is connected to the second terminal of the input power supply 10 and the first terminal of the drive switch circuit 14. The third terminal of the switch circuit 12 is connected to the second terminal of the drive switch circuit 14. The third terminal of the drive switch circuit 14 is connected to the second terminal of the internal circuit 13 and the first terminal of the charging circuit 15. The fourth terminal of the drive switch circuit 14 is connected to the second terminal of the charging circuit 15. The third terminal of the charging circuit 15 is connected to the second terminal of the input power supply 10.

[0031] When the power supply switch 11 is closed, the input power supply 10 charges the internal circuit 13 through the power supply switch 11 and the charging circuit 15; when the voltage of the internal circuit 13 is greater than a preset threshold, the switch circuit 12 controls the drive switch circuit 14 to be in working state, and the input power supply 10 supplies power to the internal circuit 13 through the power supply switch 11 and the drive switch circuit 14.

[0032] The working principle of the pre-charging circuit provided in this application embodiment is as follows: When the power supply switch 11 is closed, the drive switch circuit 14 is in a non-operating state. At this time, the input power supply 10 forms a loop with the internal circuit 13 through the power supply switch 11 and the charging circuit 15, and charges the internal circuit 13. When the voltage across the internal circuit 13 of the switch circuit 12 is greater than the threshold, the charging is complete. After the charging is completed, the control drive switch circuit 14 is put into an operating state. When the drive switch circuit 14 is in an operating state, the charging circuit 15 is not operating. The input power supply 10 and the internal circuit 13 are connected through the drive switch circuit 14 and the power supply switch 11, and the input power supply 10 supplies power to the electrical equipment in the internal circuit 13.

[0033] The voltage threshold at both ends of the internal circuit 13 is determined according to actual needs and the voltage of the actual input power supply 10. This application embodiment does not impose specific limitations on this.

[0034] Alternatively, charging the internal circuit actually involves charging a capacitor connected in parallel across the internal circuit 13, which is not shown in the figure. This charging capacitor is part of the internal circuit.

[0035] The circuit provided in this application embodiment can not only charge the capacitor in the internal circuit, but also connect to high voltage DC after a certain delay, that is, when the voltage difference between the inside and outside is small. This can effectively avoid the current surge when the device is connected to the high voltage system, and protect the power supply switch and the electrical equipment.

[0036] Please see Figure 2 , Figure 2 This is a schematic diagram of another pre-charging circuit provided in an embodiment of this application, wherein, Figure 2 The pre-charging circuit shown is for Figure 1 The pre-charging circuit shown is obtained by refining it, and... Figure 1 Compared to the pre-charging circuit shown, the drive switch circuit 14 includes a drive switch 201 and a first resistor R1, and the switch circuit 12 includes a second resistor R2, a first switch circuit 202, and a second switch circuit 203. The first terminal of the drive switch 201 is connected to the second terminal of the input power supply 10. The second terminal of the drive switch 201 is connected to the third terminal of the switch circuit 12 and the first terminal of the first resistor R1. The third terminal of the drive switch 201 is connected to the second terminal of the internal circuit 13 and the first terminal of the charging circuit 15. The second terminal of the first resistor R1 is connected to the charging circuit 15. The first end of the second resistor R2 is connected to the second end of the power supply switch 11. The second end of the second resistor R2 is connected to the first end of the first switch circuit 202 and the first end of the second switch circuit 203. The second end of the first switch circuit 202 is connected to the second end of the input power supply 10, the second end of the second switch circuit 203, and the first end of the drive switch 201. The third end of the second switch circuit 203 is connected to the second end of the drive switch 201 and the first end of the first resistor R1. The fourth end of the second switch circuit 203 is connected to the third end of the first switch circuit 202.

[0037] Specifically, the driving switch in this embodiment is a semiconductor thyristor, which is a solid-state semiconductor device. It is composed of alternating P-type and T-type materials (PNPN) to create three pn junction layers. The semiconductor thyristor contains three electrodes: anode, cathode, and gate. When the gate voltage is greater than the gate trigger voltage threshold, the semiconductor thyristor changes from the off state to the on state. After the semiconductor thyristor is turned on, even if the gate voltage is lower than the trigger voltage threshold, it will remain in the on state as long as the current flowing through it is not lower than a certain limit.

[0038] Specifically, after the power supply switch 11 is closed, the drive switch 201, i.e., the semiconductor thyristor, is in the off state. The input power supply 10 charges the capacitor in the internal circuit 13 through the power supply switch 11 and the charging circuit 15. At this time, the first switch circuit 202 is not in the working state, and the second switch circuit 203 is in the working state. When the first switch circuit 202 reaches the working voltage, the first switch circuit 202 is in the working state, and the second switch circuit 203 is not in the working state. At the same time, the drive switch 201 is in the working state. At this time, the input power supply 10 and the internal circuit 13 form a loop through the drive switch 201. The drive switch 201 is in a low resistance state, so the charging circuit is not in the working state.

[0039] The circuit provided in this application embodiment can not only charge the capacitor in the internal circuit, but also connect to high voltage DC after a certain delay, that is, when the voltage difference between the inside and outside is small. This can effectively avoid the current surge when the device is connected to the high voltage system, and protect the power supply switch and the electrical equipment.

[0040] Please see Figure 3 , Figure 3 This is another schematic diagram of a pre-charging circuit provided in an embodiment of this application. For example... Figure 3 The pre-charging circuit shown is for Figure 2 The pre-charging circuit shown is further refined and, with Figure 2 Compared to the pre-charging circuit shown, the first switching circuit 202 includes: a first switching transistor Q2, a third resistor R3, a fourth resistor R4, a first Zener diode D1, and a first capacitor C1; the first end of the third resistor R3 is connected to the second end of the second resistor R2 and the first end of the second switching circuit 203, the second end of the third resistor R3 is connected to the first end of the first capacitor C1, the cathode of the first Zener diode D1, the first end of the fourth resistor R4, and the gate of the first switching transistor Q2, the second end of the first capacitor C1 is connected to the anode of the first Zener diode D1, the second end of the fourth resistor R4, the source of the first switching transistor Q2, the second end of the input power supply 10, and the second end of the second switching circuit 203, and the drain of the first switching transistor Q2 is connected to the third end of the second switching circuit 203.

[0041] The second switching circuit 203 mentioned above includes a fifth resistor R5, a sixth resistor R6, a second Zener diode D2, and a second switching transistor Q3;

[0042] The first end of the fifth resistor R5 is connected to the second end of the second resistor R2 and the first end of the third resistor R3. The second end of the fifth resistor R5 is connected to the drain of the first switch Q2, the cathode of the second Zener diode D2, the first end of the sixth resistor R6, and the gate of the second switch Q3. The anode of the second Zener diode D2 is connected to the second end of the sixth resistor R6, the source of the second switch Q2, the second end of the input power supply 10, and the first end of the drive switch 201. The drain of the second switch Q3 is connected to the first end of the first resistor R1 and the second end of the drive switch Q1.

[0043] The charging circuit 15 mentioned above includes: a first diode D3, a second diode D4, a third diode D5, and a seventh resistor R7;

[0044] The first end of the seventh resistor R7 is connected to the third end of the drive switch Q1 and the second end of the internal circuit 13. The second end of the seventh resistor R7 is connected to the anode of the first diode D3. The cathode of the first diode D3 is connected to the anode of the second diode D4 and the second end of the first resistor R1. The cathode of the second diode D4 is connected to the anode of the third diode D5. The cathode of the third diode D5 is connected to the second end of the input power supply 10, the source of the second switch Q3, and the first end of the drive switch Q1.

[0045] Specifically, the drive switch Q1 in the drive switch circuit 14 is a semiconductor thyristor, which has three electrodes: an anode (A electrode), a cathode (K electrode), and a gate electrode (G electrode). For example... Figure 3As shown, the cathode (K-terminal) of the semiconductor thyristor Q1 is connected to the second terminal (negative terminal) of the input power supply 10, the source of the second switch Q3, the sixth resistor R6, and the anode of the second Zener diode D2. The anode (A-terminal) of the semiconductor thyristor is connected to the first terminal of the seventh resistor R7 and the second terminal of the internal circuit 13. The gate (G-terminal) of the semiconductor thyristor is connected to the first terminal of the first resistor R1 and the drain of the second switch Q3. When the power supply switch 11 is closed, the pre-charge current charges the capacitor in the internal circuit 13 through the seventh resistor R7 of the charging circuit 15. Simultaneously, current flows through the second resistor R2, the fifth resistor R5, and the sixth resistor R6. The voltage formed across the sixth resistor R6 is applied to the second switch Q3, causing it to conduct. At this time, because the second switch Q3 is conducting, the voltage across the K and G terminals of the driving switch Q1 (the semiconductor thyristor) is zero, so the semiconductor thyristor Q1 is not conducting. Furthermore, the pre-charge current also flows through the second resistor R2, the third resistor R3, and the fourth resistor R4, and the first switch... A first capacitor C1 is connected in parallel across transistor Q2. Therefore, the voltage across capacitor C1 gradually increases. When it reaches the voltage threshold for transistor Q2 to turn on, Q2 turns on. Because Q2 turns on, it lowers the gate voltage of the second transistor Q3, causing Q3 to turn off. At this time, the voltage formed by diodes D5 and D4 is applied to the cathode and gate terminals of thyristor Q1 through resistor R1, turning on thyristor Q1. The trigger threshold of the thyristor is 1.5V. Due to this delayed turn-on process, the voltage across the capacitor in internal circuit 13 is not significantly different from the DC voltage input to power supply 10. Therefore, the current flowing through thyristor Q1 is relatively small, signifying the completion of the pre-charge process.

[0046] Furthermore, after the semiconductor thyristor Q1 is turned on, the current no longer flows through the charging circuit 15. As long as the internal circuit 13 remains operational, and current flows through the semiconductor thyristor Q1, it remains in the on state even if the voltage across the K and G terminals of the semiconductor thyristor Q1 drops below the gate conduction threshold. After the internal circuit 13 stops operating, the current through the semiconductor thyristor Q1 decreases to zero. At this point, the semiconductor thyristor Q1 returns to the off state. After the voltage across the first capacitor C1 also decreases to zero, the entire pre-charging circuit can enter the next pre-charging operation.

[0047] The circuit provided in this application embodiment can not only charge the capacitor in the internal circuit, but also connect to high voltage DC after a certain delay, that is, when the voltage difference between the inside and outside is small. This can effectively avoid the current surge when the device is connected to the high voltage system, and protect the power supply switch and the electrical equipment.

[0048] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A pre-charging circuit, characterized in that, Includes power supply switch, drive switch circuit, switch circuit, input power supply, internal circuit, and charging circuit; The first output terminal of the input power supply is connected to the first terminal of the power supply switch. The second terminal of the power supply switch is connected to the first terminal of the switch circuit and the first terminal of the internal circuit. The second terminal of the switch circuit is connected to the second terminal of the input power supply and the first terminal of the drive switch circuit. The third terminal of the switch circuit is connected to the second terminal of the drive switch circuit. The third terminal of the drive switch circuit is connected to the second terminal of the internal circuit and the first terminal of the charging circuit. The fourth terminal of the drive switch circuit is connected to the second terminal of the charging circuit. The third terminal of the charging circuit is connected to the second terminal of the input power supply. When the power supply switch is closed, the input power supply charges the internal circuit through the power supply switch and the charging circuit; when the voltage of the internal circuit is greater than a preset threshold, the switch circuit controls the drive switch circuit to be in working state, and the input power supply supplies power to the internal circuit through the power supply switch and the drive switch circuit. The preset threshold is determined based on the actual needs of the internal circuit and the input power supply. The drive switch circuit includes a drive switch and a first resistor; The first end of the drive switch is connected to the second end of the input power supply. The second end of the drive switch is connected to the third end of the switch circuit and the first end of the first resistor. The third end of the drive switch is connected to the second end of the internal circuit and the first end of the charging circuit. The second end of the first resistor is connected to the second end of the charging circuit. The switching circuit includes: a second resistor, a first switching circuit, and a second switching circuit; the first switching circuit includes a first switching transistor and a first capacitor; the second switching circuit includes a second switching transistor and a sixth resistor. The second terminal of the power supply switch is connected to the drain of the first switching transistor, the gate of the second switching transistor, and the first terminal of the sixth resistor through the second resistor. The first terminal of the first capacitor is connected to the gate of the first switching transistor. The second terminal of the first capacitor, the source of the first switching transistor, and the source of the second switching transistor are connected to the second terminal of the input power supply. The drain of the second switching transistor is connected to the first terminal of the first resistor and the second terminal of the drive switch. The first end of the sixth resistor is connected to the gate of the second switching transistor and the drain of the first switching transistor, and the second end of the sixth resistor is connected to the source of the second switching transistor.

2. The pre-charging circuit according to claim 1, characterized in that, The first end of the second resistor is connected to the second end of the power supply switch. The second end of the second resistor is connected to the first end of the first switch circuit and the first end of the second switch circuit. The second end of the first switch circuit is connected to the second end of the input power supply, the second end of the second switch circuit, and the first end of the drive switch. The third end of the second switch circuit is connected to the second end of the drive switch and the first end of the first resistor. The fourth end of the second switch circuit is connected to the third end of the first switch circuit.

3. The pre-charging circuit according to claim 2, characterized in that, The first switching circuit further includes: a third resistor, a fourth resistor, and a first Zener diode; The first end of the third resistor is connected to the second end of the second resistor and the first end of the second switching circuit, respectively. The second end of the third resistor is connected to the first end of the first capacitor, the cathode of the first Zener diode, the first end of the fourth resistor, and the gate of the first switching transistor, respectively. The second end of the first capacitor is connected to the anode of the first Zener diode, the second end of the fourth resistor, the source of the first switching transistor, the second end of the input power supply, and the second end of the second switching circuit, respectively. The drain of the first switching transistor is connected to the third end of the second switching circuit.

4. The pre-charging circuit according to claim 3, characterized in that, The charging circuit includes: a first diode, a second diode, a third diode, and a seventh resistor; The first end of the seventh resistor is connected to the third end of the drive switch and the second end of the internal circuit. The second end of the seventh resistor is connected to the anode of the first diode. The cathode of the first diode is connected to the anode of the second diode and the second end of the first resistor. The cathode of the second diode is connected to the anode of the third diode. The cathode of the third diode is connected to the second end of the input power supply, the source of the second switching transistor, and the first end of the drive switch.

5. The pre-charging circuit according to any one of claims 1-4, characterized in that, The drive switch is a semiconductor thyristor.

6. The pre-charging circuit according to claim 5, characterized in that, The first switch and the second switch are metal-oxide-semiconductor field-effect transistors.

7. The pre-charging circuit according to claim 6, characterized in that, The input power supply is a DC power supply.

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