Conversion type solid-state relay

Abstract

The utility model belongs to the technical field of relays, and particularly relates to a conversion type solid-state relay, which comprises an input commutation circuit, an MOS (Metal Oxide Semiconductor) tube driving circuit, a sampling circuit, a normally open output end, a normally closed output end and a short-circuit protection circuit, the input commutation circuit is connected with the MOS tube driving circuit, and the MOS driving circuit outputs a normally open signal or a normally closed signal through a normally open output end and a normally closed output end; the sampling circuit collects current in the MOS tube driving circuit to determine whether short circuit occurs, and the short circuit protection circuit is connected with the MOS tube driving circuit and the sampling circuit to realize short circuit protection. The solid-state relay provided by the utility model has remarkable advantages in the aspects of energy conservation, accurate control, rapid protection, system reliability and flexibility, and is suitable for various electronic and electrical systems.

Description

Technical Field

[0001] This utility model belongs to the field of relay technology, specifically relating to a switching solid-state relay. Background Technology

[0002] Solid-state relays are suitable for applications requiring electrical isolation and high-frequency switching. Their performance advantages can be fully realized through proper design of input drive, output load, and protection circuits. Solid-state relays are an important solution in industrial control, automation equipment, and power electronics. However, in some applications, solid-state relays need to be in a normally open or normally closed state and switch the load path under the control of input signals. Furthermore, relay circuits often lack built-in protection circuits; without them, a short circuit in the load can burn out electronic components. While some of these circuits incorporate protection circuits, existing ones are complex and fail to adequately protect the MOSFET after a short circuit, requiring a restart of the input power supply. Utility Model Content

[0003] The purpose of this invention is to provide a switching solid-state relay, which uses two MOSFETs and their driving circuit and commutation circuit to realize on / off switching, and adds short-circuit protection to extend the life of the relay.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A switching solid-state relay includes an input switching circuit, a MOSFET driving circuit, a sampling circuit, and a short-circuit protection circuit;

[0006] The input commutation circuit uses a full-bridge commutation circuit composed of four diodes, D1, D2, D3, and D4.

[0007] The MOSFET driving circuit includes a MOSFET Q1 and a first driving circuit connected thereto, a MOSFET Q2 and a second driving circuit connected thereto, wherein the output terminal of MOSFET Q1 is a normally open output terminal, and the output terminal of MOSFET Q2 is a normally closed output terminal.

[0008] The short-circuit protection circuit includes a first short-circuit protection circuit for protecting MOSFET Q1 and a second short-circuit protection circuit for protecting MOSFET Q2. The first and second short-circuit protection circuits have the same circuit structure, which includes a diode and a thyristor. The cathode of the diode is connected to the gate of the thyristor, the base of the thyristor is grounded, and its anode is connected to the front end of the first drive circuit. The cathode of the diode is grounded through a resistor, and the anode of the diode is connected to the output terminal of the sampling circuit.

[0009] The sampling circuit includes a sampling resistor R0, a sampling current-limiting resistor R1, a step-down resistor R2, a capacitor C1, and an optocoupler OP1. The sampling resistor R0, sampling current-limiting resistor R1, and step-down resistor R2 are connected in parallel to the working voltage terminal VCC. The sampling resistor R0 is connected to the output terminal of the drive circuit. The sampling current-limiting resistor R1 is connected to the input terminal of the optocoupler OP1, and a capacitor C1 is connected in parallel to the input terminal of the optocoupler OP1. The step-down resistor R2 is connected to the power supply terminal of the optocoupler OP1. The output terminal of the optocoupler OP1 outputs a trigger signal Us through resistor R14; the short-circuit protection circuit is activated by the trigger signal Us.

[0010] Furthermore, the first driving circuit includes resistors R15 and R16, diode D6, resistors R10 and R11, transistor T1, resistors R3 and R4, and Zener diode W1. Resistors R15 and R16 are connected in parallel to the output of the full-bridge commutation circuit. The connection point of resistors R15 and R16 is connected to the anode of diode D6. The cathode of diode D6 is connected to the base (B) of transistor T1 through resistor R11. The base (B) of transistor T1 is grounded through resistor R10. The collector (C) of transistor T1 is connected to the anode of Zener diode W1 through resistor R3. Zener diode W1 is connected in parallel with resistor R4. The collector (C) of transistor T1 is also connected to the gate (G) of MOSFET Q1 through resistor R3. The drain (D) of MOSFET Q1 is connected to the operating voltage terminal VCC, and its source (S) is a normally closed output terminal.

[0011] Furthermore, the second driving circuit is used to drive the MOSFET Q2 to turn on or off. It includes resistor R5, diodes D8 and D9, resistor R8 and diode D10, transistor T2, resistors R7 and R6, and Zener diode W2. The cathode of diode D8 is connected to the collector (C) of transistor T1, and its anode is connected to the anode of diode D9. The cathode of diode D9 is connected to the base (B) of transistor T2. The base (B) of transistor T2 is grounded through resistor R8, and its collector (C) is connected to the anode of Zener diode W2 through resistor R7. Zener diode W1 is connected in parallel with resistor R6. The collector (C) of transistor T2 is also connected to the gate (G) of MOSFET Q2 through resistor R7. The drain (D) of MOSFET Q2 is connected to the operating voltage terminal VCC, and its source (S) is a normally open output terminal.

[0012] This invention utilizes two MOSFETs and their driving circuit to design a switching mechanism. The MOSFETs are easily controlled by a microcontroller or digital signals, enhancing system flexibility. Furthermore, their low on-resistance, low power consumption, and high efficiency make them suitable for frequent switching operations. High-side sampling enables real-time monitoring of the load current and allows for immediate activation of short-circuit protection, which quickly disconnects the circuit to prevent damage to the MOSFETs. This effectively avoids faults caused by short circuits and extends equipment lifespan. This invention offers significant advantages in energy saving, precise control, rapid protection, system reliability, and flexibility, and is applicable to various electronic and electrical systems. Attached Figure Description

[0013] Figure 1 This is a circuit block diagram of the present invention.

[0014] Figure 2 This is a schematic diagram of the circuit structure of this utility model. Detailed Implementation

[0015] like Figure 1 As shown, this embodiment provides a switching solid-state relay including an input commutation circuit, a MOSFET driving circuit, a sampling circuit, a normally open output terminal, a normally closed output terminal, and a short-circuit protection circuit. The input commutation circuit is connected to the MOSFET driving circuit, which outputs normally open or normally closed signals through the normally open and normally closed output terminals. The sampling circuit collects the current in the MOSFET driving circuit to determine whether a short circuit has occurred. The short-circuit protection circuit is connected to the MOSFET driving circuit and the sampling circuit to achieve short-circuit protection.

[0016] like Figure 2 As shown, the input commutation circuit uses a full-bridge commutation circuit composed of four diodes D1, D2, D3, and D4. The input wiring does not distinguish between positive and negative, making it convenient to use.

[0017] The MOSFET driving circuit includes MOSFET Q1 and a first driving circuit connected to it, MOSFET Q2 and a second driving circuit connected to it. The first driving circuit is used to drive MOSFET Q1 to turn on or off. It includes resistors R15 and R16, diode D6, resistors R10 and R11, transistor T1, resistors R3 and R4, and W1. Resistors R15 and R16 are connected in parallel to the output of the full-bridge commutation circuit. The connection point of resistors R15 and R16 is connected to the anode of diode D6. The cathode of diode D6 is connected to the base (B) of transistor T1 through resistor R11. The base (B) of transistor T1 is grounded through resistor R10. The collector (C) of transistor T1 is connected to the anode of Zener diode W1 through resistor R3. Zener diode W1 is connected in parallel with resistor R4. The collector (C) of transistor T1 is also connected to the gate (G) of MOSFET Q1 through resistor R3. The drain (D) of MOSFET Q1 is connected to the operating voltage terminal VCC, and its source (S) is a normally closed output terminal. The second driving circuit is used to drive the MOSFET Q2 to turn on or off. It includes resistor R5, diodes D8 and D9, resistor R8 and diode D10, transistor T2, resistors R7 and R6, and Zener diode W2. The cathode of diode D8 is connected to the collector (C) of transistor T1, and its anode is connected to the anode of diode D9. The cathode of diode D9 is connected to the base (B) of transistor T2. The base (B) of transistor T2 is grounded through resistor R8, and its collector (C) is connected to the anode of Zener diode W2 through resistor R7. Zener diode W1 is connected in parallel with resistor R6. The collector (C) of transistor T2 is also connected to the gate (G) of MOSFET Q2 through resistor R7. The drain (D) of MOSFET Q2 is connected to the operating voltage terminal VCC, and its source (S) is a normally open output terminal.

[0018] The short-circuit protection circuit includes a first short-circuit protection circuit for protecting MOSFET Q1 and a second short-circuit protection circuit for protecting MOSFET Q2. The first short-circuit protection circuit includes diode D5, resistor R12, and thyristor SCR1. The cathode of diode D5 is connected to the gate (G) of thyristor SCR1, the base (K) of thyristor SCR1 is grounded, and its anode (A) is connected to the front end of the first drive circuit, i.e., to the positive terminal of diode D6. The cathode of diode D5 is grounded through resistor R12, and the anode of diode D5 is connected to the sampling circuit. The second short-circuit protection circuit is the same as the first short-circuit protection circuit. It includes thyristor SCR2, diode D7, and resistor R9. The anode of diode D7 is connected to the sampling circuit, and its cathode is connected to the gate (G) of thyristor SCR2. The base (K) of thyristor SCR2 is grounded, and its anode (A) is connected to the front end of the second drive circuit, i.e., to the positive terminal of diode D8. Two short-circuit protection circuits share a single sampling trigger signal Us; when any output load is short-circuited to ground, the sampling circuit outputs a protection trigger signal Us, which simultaneously triggers thyristors SCR1 and SCR2, blocks the drive signals of MOSFETs Q1 and Q2, and forcibly shuts down MOSFETs Q1 and Q2, thus completing the short-circuit protection function; the entire protection process takes less than 5µs.

[0019] The sampling circuit includes a sampling resistor R0, a sampling current-limiting resistor R1, a step-down resistor R2, a capacitor C1, and an optocoupler OP1. The sampling resistor R0, sampling current-limiting resistor R1, and step-down resistor R2 are connected in parallel to the operating voltage terminal VCC. The sampling resistor R0 is connected to the negative terminals of the Zener diodes W1 and W2 in the drive circuit. The sampling current-limiting resistor R1 is connected to the input terminal of the optocoupler OP1, and a capacitor C1 is connected in parallel to the input terminal of the optocoupler OP1. The step-down resistor R2 is connected to the power supply terminal of the optocoupler OP1. The output terminal of the optocoupler OP1 outputs a trigger signal Us through resistor R14. The sampling current-limiting resistor R1 is used to protect the primary side of the optocoupler from overload, capacitor C1 is used for spike absorption, and the step-down resistor R2 is used to reduce the power consumption of the optocoupler. Since this solid-state relay is a switching type, only one output MOSFET can be turned on at any time. During normal operation, the sampling voltage on the sampling resistor R0 is below 0.2V, the primary diode of the optocoupler OP1 will not conduct, and its secondary side has no output. When any output S1 or S2 is short-circuited to ground, the sampling voltage across resistor R0 rises rapidly. When it exceeds 0.7V, optocoupler OP1 turns on, and the secondary side outputs the sampling voltage. After being divided by resistor R14, the short-circuit protection trigger voltage Us is obtained, which simultaneously triggers thyristors SCR1 and SCR2, forcibly turning off the two output MOSFETs and completing the short-circuit protection function.

[0020] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any modifications and substitutions based on the technical solutions and utility model concepts provided by the present utility model should be covered within the protection scope of the present utility model.

Claims

1. A switching type solid-state relay, characterized in that: This includes the input commutation circuit, MOSFET drive circuit, sampling circuit, and short-circuit protection circuit; The input commutation circuit uses a full-bridge commutation circuit composed of four diodes, D1, D2, D3, and D4. The MOSFET driving circuit includes a MOSFET Q1 and a first driving circuit connected thereto, a MOSFET Q2 and a second driving circuit connected thereto, wherein the output terminal of MOSFET Q1 is a normally open output terminal, and the output terminal of MOSFET Q2 is a normally closed output terminal. The short-circuit protection circuit includes a first short-circuit protection circuit for protecting MOSFET Q1 and a second short-circuit protection circuit for protecting MOSFET Q2. The first and second short-circuit protection circuits have the same circuit structure, which includes a diode and a thyristor. The cathode of the diode is connected to the gate of the thyristor, the base of the thyristor is grounded, and its anode is connected to the front end of the first drive circuit. The cathode of the diode is grounded through a resistor, and the anode of the diode is connected to the output terminal of the sampling circuit. The sampling circuit includes a sampling resistor R0, a sampling current-limiting resistor R1, a step-down resistor R2, a capacitor C1, and an optocoupler OP1. The sampling resistor R0, sampling current-limiting resistor R1, and step-down resistor R2 are connected in parallel to the working voltage terminal VCC. The sampling resistor R0 is connected to the output terminal of the drive circuit. The sampling current-limiting resistor R1 is connected to the input terminal of the optocoupler OP1, and a capacitor C1 is connected in parallel to the input terminal of the optocoupler OP1. The step-down resistor R2 is connected to the power supply terminal of the optocoupler OP1. The output terminal of the optocoupler OP1 outputs a trigger signal Us through resistor R14; the short-circuit protection circuit is activated by the trigger signal Us.

2. The switching solid-state relay according to claim 1, characterized in that: The first driving circuit includes resistors R15 and R16, diode D6, resistors R10 and R11, transistor T1, resistors R3 and R4, and Zener diode W1. Resistors R15 and R16 are connected in parallel to the output of the full-bridge commutation circuit. The connection point of resistors R15 and R16 is connected to the anode of diode D6. The cathode of diode D6 is connected to the base (B) of transistor T1 through resistor R11. The base (B) of transistor T1 is grounded through resistor R10. The collector (C) of transistor T1 is connected to the anode of Zener diode W1 through resistor R3. Zener diode W1 is connected in parallel with resistor R4. The collector (C) of transistor T1 is also connected to the gate (G) of MOSFET Q1 through resistor R3. The drain (D) of MOSFET Q1 is connected to the operating voltage terminal VCC, and its source (S) is a normally closed output terminal.

3. A switching solid-state relay according to claim 2, characterized in that: The second driving circuit is used to drive the MOSFET Q2 to turn on or off. It includes resistor R5, diodes D8 and D9, resistor R8 and diode D10, transistor T2, resistors R7 and R6, and Zener diode W2. The cathode of diode D8 is connected to the collector (C) of transistor T1, and its anode is connected to the anode of diode D9. The cathode of diode D9 is connected to the base (B) of transistor T2. The base (B) of transistor T2 is grounded through resistor R8, and its collector (C) is connected to the anode of Zener diode W2 through resistor R7. Zener diode W1 is connected in parallel with resistor R6. The collector (C) of transistor T2 is also connected to the gate (G) of MOSFET Q2 through resistor R7. The drain (D) of MOSFET Q2 is connected to the operating voltage terminal VCC, and its source (S) is a normally open output terminal.

Images