An adaptive pre-charge switching circuit

Abstract

The application discloses a self-adaptive pre-charge switch circuit, which comprises a main path relay K1, a pre-charge branch relay K2 connected in parallel with the main path relay K1, a current-limiting resistor R connected with the pre-charge branch relay K2, a current collection circuit connected with an output end of the main path relay K1, a voltage comparison circuit connected between the main path relay K1, and a relay isolation driving circuit connected with the voltage comparison circuit. Circuit parameters can be conveniently adjusted, and the circuit has good versatility; a pressure difference value for opening the main path relay can be adjusted through a potentiometer in the voltage comparison circuit; overcurrent protection values can be adjusted through potentiometers in the driving circuit; and a pre-charge branch relay delay-off time can be adjusted through a potentiometer in the relay control circuit. The self-adaptive pre-charge protection, switch control, overcurrent protection and other functions are integrated, the volume is greatly reduced, and the self-adaptive pre-charge switch circuit is suitable for high-voltage direct-current output control circuits in power supply systems and power supply and distribution systems.

Description

Technical Field

[0001] This invention relates to the field of precharge circuit structure, and more particularly to an adaptive precharge switching circuit. Background Technology

[0002] In recent years, the application scope of high voltage direct current (HVDC) systems has been expanding, and it is the current trend in the development of power supply and distribution equipment. This system includes a high voltage direct current input power supply and many high voltage electrical devices. Capacitors are installed at the input ports of these devices for filtering. Therefore, in the high voltage direct current output circuit, the downstream load is mostly capacitive, which will generate a large inrush current at the moment of power-on, causing damage to the contacts of the output relay and leading to the failure of the output relay.

[0003] Currently, traditional precharge protection circuits require consideration of the capacitance and precharge time parameters of the downstream load during design, making them unsuitable for use in different high-voltage DC systems. This results in significant limitations in their application. In order to match different high-voltage DC systems, it is easy to create a situation where one set of precharge protection circuits is used for each high-voltage DC system, leading to low versatility. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an adaptive precharge switching circuit.

[0005] The present invention is achieved through the following technical solutions.

[0006] An adaptive precharge switching circuit includes:

[0007] Main circuit relay K1,

[0008] The pre-charge branch relay K2 is connected in parallel with the main relay K1;

[0009] The current acquisition circuit is connected to the output terminal of the main circuit relay K1;

[0010] The voltage comparison circuit is connected across the main circuit relay K1.

[0011] The relay isolation drive circuit is connected to the voltage comparison circuit.

[0012] The current acquisition circuit includes comparator U5B, whose pin 5 is connected to the +5VCC power supply through resistors R56 and R71, and grounded through capacitor C16; its pin 8 is connected to the +5VCC power supply, and also connected to capacitors C17 and C18; its pin 7 is connected to pin 6, and pin 7 is connected to pin 2 of comparator U5A through resistor R59; pin 2 of comparator U5A is connected to pin 1 through resistor R60; its pin 3 outputs the IOUT signal through resistor R57, and pin 3 is grounded through resistor R58, which is connected to the second terminals of capacitors C17 and C18; pin 1 of comparator U5A is also connected to the first terminal of capacitor C18 through resistor R61.

[0013] The voltage comparison circuit detects and compares the voltage difference across the contacts of the main relay K1. It includes comparators U3A, U3B, U4B, and U4A. Comparator U3A has five resistors connected in series at both its positive and negative input terminals. A resistor R47 and a capacitor C12 are connected in parallel between the negative input and output terminals of comparator U3A. The positive input terminal of comparator U3A is grounded through capacitor C11, which is connected in parallel with resistor R46. The output terminal of comparator U3A is connected to the positive input terminal of comparator U3B through resistor R48. The output terminal of comparator U3B is connected to port 1 of optocoupler isolation circuit OP1 through resistor R50. Port 2 of optocoupler isolation circuit OP1 is connected to port 1 of optocoupler isolation circuit OP2. Port 2 of optocoupler isolation circuit OP2 is grounded, port 3 is connected to the negative input terminal of comparator U3B, and port 4 is connected to… The input voltage is +5V. One side of port 4 of the optocoupler isolation circuit OP1 is connected to resistor R1, and the other side is connected to the negative terminal of Zener diode ZD2. The positive terminal of Zener diode ZD2 is grounded. Port 3 of the optocoupler isolation circuit OP1 is connected to the positive input terminal of comparator U4B. The positive input terminal of comparator U4B is connected to resistor R51, and the other end of resistor R51 is grounded. The inverting input terminal of comparator U4B is connected to the output terminal. The output terminal of comparator U4B is connected to the positive input terminal of comparator U4A through resistor R52. The power supply terminal of comparator U4A is connected to the 5V circuit power supply. Resistor R54, capacitor C15 and resistor R57 are connected in parallel between the inverting input terminal and the output terminal of comparator U4A. Resistor R53 is connected between the first terminal of resistor R54 and the first terminal of capacitor C15. Resistor R55 is connected between the second terminal of resistor R54 and the second terminal of capacitor C15.

[0014] The relay isolation drive circuit includes a pre-charge relay circuit, a positive power relay circuit, and a negative power relay circuit. The pre-charge relay control circuit includes a capacitor EC3, a resistor R19 connected in parallel with the capacitor EC3, a Zener diode ZD1 connected in parallel with the resistor R19, the positive terminal of the Zener diode ZD1 connected to the gate of the MOSFET Q1, the negative terminal of the Zener diode ZD1 connected to the drain of the MOSFET Q1, the source of the MOSFET connected to one end of relays K4B and K3B, and the other end of relays K4B and K3B each connected to a single-pole double-throw switch.

[0015] The positive power relay circuit includes a relay K1B. The first terminal of the relay K1B is connected to two single-pole double-throw switches connected in parallel. The second terminal of the relay K1B is connected to an inductor L1. The relay K1B is connected in parallel to a diode D2, and the positive and negative terminals of the diode D2 are connected to the first and second terminals of the relay K1B, respectively.

[0016] The negative power relay circuit includes a relay K2B, a diode D3, and an inductor L2. The first terminal of the relay K2B is connected to the positive terminal of the diode D3, the second terminal of the relay K2B is connected to the negative terminal of the diode D3, and the inductor L2 is connected to the second terminal of the relay K2B.

[0017] The main switching circuit includes relays K1A, K3A, and K4A, inductor R0, capacitor C22, and diode D16. Resistor R12 is connected to the second terminal of relay K1A. The first terminal of resistor R8 is connected between relay K1A and the first terminal of resistor R12. Resistors R8, R9, R10, and R11 are connected in series at the second terminal of resistor R8. Resistor R13 is connected to the second terminal of resistor R12. Resistors R14, R15, R16, R17, and R18 are connected in series at the other terminal of resistor R13. One end of inductor R0 is connected to the second terminal of relay K1A, and the other end of inductor R0 is connected to the first terminal of relay K4A. One end of capacitor C22 is connected between resistors R10 and R11, and the other end of capacitor C22 is the HV- port. The negative terminal of diode D16 is connected between resistors R17 and R18, and the positive terminal is the HV- port.

[0018] It also includes a current-limiting resistor R, which is connected to the pre-charge branch relay K2.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention integrates adaptive precharge protection, switch control, and overcurrent protection functions. Structurally, these functions are integrated into a single module, significantly reducing the size and facilitating replacement and maintenance. It is suitable for high-voltage DC output control circuits in power supply systems and power distribution systems. The circuit parameters can be easily adjusted, solving the problem that traditional precharge protection circuits, which require consideration of the capacitance and precharge time parameters of the downstream load during design, cannot be used in different high-voltage DC systems, thus demonstrating good versatility. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] Figure 2 This is the voltage comparison circuit diagram of the present invention;

[0023] Figure 3 This is the main circuit diagram of the switch of the present invention;

[0024] Figure 4 This is a circuit diagram of the relay isolation drive circuit of the present invention;

[0025] Figure 5 This is the circuit diagram for current acquisition in this invention. Detailed Implementation

[0026] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0027] An adaptive precharge switching circuit, employing a modular design, can be used in high-voltage DC output circuits in power supply systems and power distribution systems. It mainly includes a main circuit relay K1, a precharge branch relay K2 connected in parallel with the main circuit relay K1; a current acquisition circuit connected to the output terminal of the main circuit relay K1; a voltage comparison circuit connected across the main circuit relay K1; and a relay isolation drive circuit connected to the voltage comparison circuit.

[0028] To achieve the pre-charge and connection functions, this invention includes a main switching circuit. The main switching circuit includes relays K1A, K3A, and K4A, an inductor R0, a capacitor C22, and a diode D16. The second terminal of relay K1A is connected to a resistor R12. The first terminal of resistor R8 is connected between relay K1A and the first terminal of resistor R12. Resistors R8, R9, R10, and R11 are connected in series at the second terminal of resistor R8. The second terminal of resistor R12 is connected to a resistor R13. The other terminal of resistor R13 is connected in series with… Resistors R14, R15, R16, R17, and R18 are included. One end of inductor R0 is connected to the second terminal of relay K1A, and the other end of inductor R0 is connected to the first terminal of relay K4A. One end of capacitor C22 is connected between resistors R10 and R11, and the other end of capacitor C22 is the HV- port. The cathode of diode D16 is connected between resistors R17 and R18, and the anode is the HV- port. The main switching circuit also features a safe high-voltage direct test interface and an LED indicator interface.

[0029] When the high-voltage DC output circuit is powered on, the pre-charge branch relay is first turned on. After current limiting by the pre-charge resistor, the downstream load is charged. The voltage difference across the main relay contacts is automatically detected by the voltage comparison circuit. When the voltage difference is within the set range, the voltage difference can be set to 40V. After a certain delay, for redundant protection, the delay is generally set to about 2 seconds. The main relay output is turned on, and the pre-charge branch relay is turned off after a certain delay, thereby realizing the adaptive pre-charge protection function.

[0030] To adapt to different high-voltage DC systems, the aforementioned voltage difference value can be achieved by adjusting the corresponding resistor values ​​in the voltage comparison circuit. The resistor values ​​are adjusted using potentiometers. The voltage comparison circuit includes comparators U3A, U3B, U4B, and U4A. Five resistors are connected in series at both the positive and negative input terminals of comparator U3A. A resistor R47 and a capacitor C12 are connected in parallel between the negative input and output terminals of comparator U3A. The positive input terminal of comparator U3A is grounded through capacitor C11. 11. A resistor R46 is connected in parallel; the output of comparator U3A is connected to the positive input of comparator U3B through resistor R48. The output of comparator U3B is connected to port 1 of optocoupler isolation circuit OP1 through resistor R50. Port 2 of optocoupler isolation circuit OP1 is connected to port 1 of optocoupler isolation circuit OP2. Port 2 of optocoupler isolation circuit OP2 is grounded. Port 3 is connected to the inverting input of comparator U3B. Port 4 is connected to +5V. A resistor R1 is connected to one side of port 4 of optocoupler isolation circuit OP1, and the other... The side is connected to the negative terminal of Zener diode ZD2, and the positive terminal of Zener diode ZD2 is grounded; port 3 of optocoupler isolation circuit OP1 is connected to the positive input terminal of comparator U4B, and resistor R51 is connected to the positive input terminal of comparator U4B, with the other end of resistor R51 grounded; the inverting input terminal of comparator U4B is connected to the output terminal, and the output terminal of comparator U4B is connected to the positive input terminal of comparator U4A through resistor R52; the power supply terminal of comparator U4A is connected to a 5V circuit power supply, and the inverting input terminal and output terminal of comparator U4A are connected to... A resistor R54, a capacitor C15, and a resistor R57 are connected in parallel. A resistor R53 is connected between the first terminal of resistor R54 and the first terminal of capacitor C15. A resistor R55 is connected between the second terminal of resistor R54 and the second terminal of capacitor C15. One end of resistor R55 is connected to CHK_V. The reference voltage value is adjusted by changing the ratio of the resistance values ​​of resistors R36-R45 to the resistance value of resistor R46. In addition, the comparison voltage value is adjusted by changing the ratio between the CHK_V input value and resistors R54 and R55, thus obtaining different voltage difference values.

[0031] The current acquisition circuit can automatically disconnect the main circuit relay K1 and the pre-charge branch relay K2 when the circuit experiences overcurrent. The current acquisition circuit includes comparators U5B and U5A. The positive input terminal of comparator U5B is connected to the first terminal of resistor R56. The second terminal of resistor R56 is connected to resistors R70 and R71 respectively. A capacitor C16 is connected in parallel with resistor R56. The inverting input terminal of comparator U5B is connected to its output terminal. The output terminal of comparator U5B is connected to the inverting input terminal of comparator U5A through resistor R59. The inverting input of comparator U5A is connected to the output of comparator U5A via resistor R60. The non-inverting input of comparator U5A is connected to resistor R57. One end of resistor R58 is connected between the non-inverting input of comparator U5A and resistor R57, and the other end of resistor R58 is grounded. The output of comparator U5A is connected to resistor R61. Resistor R61 is connected to one end of capacitor C18. The other end of capacitor C18 is connected to one end of capacitor C17. The other end of capacitor C17 is connected to the power input of comparator U5B.

[0032] The relay isolation drive circuit includes a pre-charge relay circuit, a positive power relay circuit, and a negative power relay circuit. The pre-charge relay control circuit includes a capacitor EC3, a resistor R19 connected in parallel with the capacitor EC3, a Zener diode ZD1 connected in parallel with the resistor R19, the positive terminal of the Zener diode ZD1 connected to the gate of the MOSFET Q1, the negative terminal of the Zener diode ZD1 connected to the drain of the MOSFET Q1, the source of the MOSFET connected to one end of relays K4B and K3B, and the other end of relays K4B and K3B each connected to a single-pole double-throw switch.

[0033] The positive power relay circuit includes a relay K1B. The first terminal of the relay K1B is connected to two single-pole double-throw switches connected in parallel. The second terminal of the relay K1B is connected to an inductor L1. A diode D2 is connected in parallel with the relay K1B, and the positive and negative terminals of the diode D2 are connected to the first and second terminals of the relay K1B, respectively.

[0034] The negative power relay circuit includes a relay K2B, a diode D3, and an inductor L2. The first terminal of the relay K2B is connected to the positive terminal of the diode D3, the second terminal of the relay K2B is connected to the negative terminal of the diode D3, and the inductor L2 is connected to the second terminal of the relay K2B. In the relay isolation drive circuit, the drive safety isolation between the main relay and the precharge relay is realized, and the delay disconnection time of the precharge branch relay can be controlled.

Claims

1. An adaptive precharge switching circuit, characterized in that, include: Main circuit relay K1, The pre-charge branch relay K2 is connected in parallel with the main relay K1; The current acquisition circuit is connected to the output terminal of the main circuit relay K1; The voltage comparison circuit is connected across the main circuit relay K1. A relay isolation drive circuit is connected to a voltage comparison circuit. The main switching circuit includes relays K1A, K3A, and K4A, inductor R0, capacitor C22, and diode D16. Resistor R12 is connected to the second terminal of relay K1A. The first terminal of resistor R8 is connected between relay K1A and the first terminal of resistor R12. Resistors R8, R9, R10, and R11 are connected in series at the second terminal of resistor R8. Resistor R13 is connected to the second terminal of resistor R12. Resistors R14, R15, R16, R17, and R18 are connected in series at the other terminal of resistor R13. One end of inductor R0 is connected to the second terminal of relay K1A, and the other end of inductor R0 is connected to the first terminal of relay K4A. One end of capacitor C22 is connected between resistors R10 and R11, and the other end of capacitor C22 is the HV-port. The negative terminal of diode D16 is connected between resistors R17 and R18, and the positive terminal is the HV-port. The current acquisition circuit includes comparator U5B, whose pin 5 is connected to the +5VCC power supply through resistors R56 and R71, and grounded through capacitor C16; its pin 8 is connected to the +5VCC power supply and capacitor C17; its pin 7 is connected to pin 6, and pin 7 is connected to pin 2 of comparator U5A through resistor R59; pin 2 of comparator U5A is connected to pin 1 through resistor R60; its pin 3 outputs the IOUT signal through resistor R57, and pin 3 is grounded through resistor R58, which is connected to the second terminals of capacitors C17 and C18; pin 1 of comparator U5A is also connected to the first terminal of capacitor C18 through resistor R61. The voltage comparison circuit detects and compares the voltage difference across the contacts of the main relay K1. It includes comparators U3A, U3B, U4B, and U4A. Comparator U3A has five resistors connected in series at both its positive and negative input terminals. A resistor R47 and a capacitor C12 are connected in parallel between the negative input and output terminals of comparator U3A. The positive input terminal of comparator U3A is grounded through capacitor C11, which is connected in parallel with resistor R46. The output terminal of comparator U3A is connected to the positive input terminal of comparator U3B through resistor R48. The output terminal of comparator U3B is connected to port 1 of optocoupler isolation circuit OP1 through resistor R50. Port 2 of optocoupler isolation circuit OP1 is connected to port 1 of optocoupler isolation circuit OP2. Port 2 of optocoupler isolation circuit OP2 is grounded, port 3 is connected to the negative input terminal of comparator U3B, and port 4 is connected to… Input +5V voltage; One side of port 4 of optocoupler isolation circuit OP1 is connected to resistor R1, and the other side is connected to the negative terminal of Zener diode ZD2, with the positive terminal of Zener diode ZD2 grounded; Port 3 of optocoupler isolation circuit OP1 is connected to the positive input terminal of comparator U4B, and the positive input terminal of comparator U4B is connected to resistor R51, with the other end of resistor R51 grounded; The inverting input terminal of comparator U4B is connected to the output terminal, and the output terminal of comparator U4B is connected to the positive input terminal of comparator U4A through resistor R52; The power supply terminal of comparator U4A is connected to the 5V circuit power supply; Resistor R54, capacitor C15, and resistor R57 are connected in parallel between the inverting input terminal and the output terminal of comparator U4A; Resistor R53 is connected between the first terminal of resistor R54 and the first terminal of capacitor C15; Resistor R55 is connected between the second terminal of resistor R54 and the second terminal of capacitor C15. The relay isolation drive circuit includes a pre-charge relay circuit, a positive power relay circuit, and a negative power relay circuit. The pre-charge relay control circuit includes a capacitor EC3, a resistor R19 connected in parallel with the capacitor EC3, a Zener diode ZD1 connected in parallel with the resistor R19, the positive terminal of the Zener diode ZD1 connected to the gate of the MOSFET Q1, the negative terminal of the Zener diode ZD1 connected to the drain of the MOSFET Q1, the source of the MOSFET connected to one end of relays K4B and K3B, and the other end of relays K4B and K3B each connected to a single-pole double-throw switch. The positive power relay circuit includes a relay K1B. The first terminal of the relay K1B is connected to two single-pole double-throw switches connected in parallel. The second terminal of the relay K1B is connected to an inductor L1. The relay K1B is connected in parallel to a diode D2, and the positive and negative terminals of the diode D2 are connected to the first and second terminals of the relay K1B, respectively. The negative power relay circuit includes a relay K2B, a diode D3, and an inductor L2. The first terminal of the relay K2B is connected to the positive terminal of the diode D3, the second terminal of the relay K2B is connected to the negative terminal of the diode D3, and the inductor L2 is connected to the second terminal of the relay K2B.

2. The adaptive precharge switching circuit according to claim 1, characterized in that, It also includes a current-limiting resistor R, which is connected to the pre-charge branch relay K2.

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