Relay control circuit
By using components such as transistors and capacitors in the relay control circuit, and controlling two MOSFETs with one chip I/O port, the problems of resource waste and control complexity are solved, and the stability and safety of the load are achieved.
Patent Information
- Application Number
- CN202421546970.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-02
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-07-02
AI Technical Summary
In the existing technology, the relays that control high-power electric heating loads need to occupy the I/O port resources of two chips, which leads to resource waste and increased software control complexity, and poses a fire risk during short-circuit testing.
A relay control circuit is used, which utilizes a combination of two transistors, capacitors, resistors, and diodes to control two MOSFETs through the I/O port of a chip, thereby achieving stability of the load output and safety of short-circuit testing.
This technology enables the control of two MOSFETs using a single I/O port, saving costs and reducing the complexity of software control. It also maintains the load under control during short-circuit testing, thus avoiding the risk of fire.
Smart Images
Figure CN223624892U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of relay control in household appliances, and in particular to a relay control circuit. Background Technology
[0002] In circuit control, to ensure that there is no risk of fire caused by the output of high-power electric heating load under abnormal operation, it is necessary to perform abnormal short-circuit tests on the control circuit of high-power electric heating element. When the control circuit device is short-circuited, the output load must still be controlled and there must be no uncontrolled heating state that could cause a fire risk. For this reason, the current industry practice requires the use of I / O port resources of two chips.
[0003] The current industry practice is to use the I / O ports of two chips for control. This approach requires the I / O port resources of two chips to control one load output. When a product needs to control multiple load outputs, it requires twice the I / O port resources of the chip, leading to resource shortages and increasing costs. Secondly, in terms of software control, "driver chip I / O port_1" needs to be normally open. The correct control signal must be output from "driver chip I / O port_2" before "driver chip I / O port_1" can be opened, which increases the difficulty of software control.
[0004] Current industry design solutions require two I / O ports, and their working principle is as follows:
[0005] When the relay load output is not required, the program must set "Driver Chip I / O Port_1" to a low level to ensure that Q1 is in the off state in this state. When it is necessary to control the relay (REL1), the program first sets "Driver Chip I / O Port_2" to output a square wave signal to set Q2 to the on state. When the program determines that "Driver Chip I / O Port_2" does have a square wave output, the software program then sets "Driver Chip I / O Port_1" to a high level to set Q1 to the on state. It is necessary to control two I / O ports to meet the product setting requirements. Utility Model Content
[0006] To solve the above problems, this technical solution provides a relay control circuit.
[0007] To achieve the above objectives, the technical solution is as follows:
[0008] A relay control circuit includes a switching device REL1. The conducting terminal of the switching device REL1 is used to control the load output. The anode of its coil terminal receives a voltage, the cathode is connected to the collector of switching element Q1, and its emitter is connected to the collector of switching element Q2. The emitter of switching element Q2 is grounded. The bases of switching elements Q1 and Q2 are connected together and grounded through capacitor C2. This common connection point is also connected to the output terminal of diode D5. The ground terminal of capacitor C2 is connected to the first input terminal of diode D5, and the second input terminal of diode D5 is connected to capacitor C3. Capacitor C3 can also receive signals from a driver chip.
[0009] In some embodiments, the base of the switching element Q1 is connected to a resistor R1, the base of the switching element Q2 is connected to a resistor R2, and the resistors R1 and R2 are connected to a common contact.
[0010] In some embodiments, one end of the resistor R2 is grounded through the capacitor C1, and the other end is grounded through the resistor R4.
[0011] In some embodiments, the capacitor C3 is connected to a resistor R5.
[0012] In some embodiments, a diode D4 is connected between the anode and cathode of the coil end of the switching device REL1.
[0013] In some embodiments, the switching device REL1 is a relay or a silicon controlled rectifier (SCR).
[0014] In some embodiments, the switching element Q1 is a transistor or a MOSFET.
[0015] The beneficial effects of this application are:
[0016] This application only requires one I / O port to control two MOSFETs simultaneously, saving development resources, effectively reducing costs, and lowering the difficulty of software control. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below.
[0018] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model. Detailed Implementation
[0019] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.
[0020] Please refer to Figure 1 As shown, a relay control circuit includes a switching device REL1. Preferably, the switching device REL1 is a relay. The conducting terminal of the switching device REL1 is used to control the load output. Its coil anode receives a voltage, its cathode is connected to the collector of switching element Q1, and its emitter is connected to the collector of switching element Q2. The emitter of switching element Q2 is grounded. The bases of switching element Q1 and Q2 are connected together and grounded through capacitor C2. This common connection point is also connected to the output terminal of diode D5. The ground terminal of capacitor C2 is connected to the first input terminal of diode D5, and the second input terminal of diode D5 is connected to capacitor C3. Capacitor C3 can also receive signals from a driver chip. Preferably, switching elements Q1 and Q2 are transistors.
[0021] In this embodiment, the base of the switching element Q1 is connected to a resistor R1, the base of the switching element Q2 is connected to a resistor R2, and the resistors R1 and R2 are connected to a common contact point.
[0022] In this embodiment, one end of the resistor R2 is grounded through the capacitor C1, and the other end is grounded through the resistor R4.
[0023] In this embodiment, capacitor C3 is connected to resistor R5.
[0024] In this embodiment, a diode D4 is connected between the anode and cathode of the coil end of the switching device REL1.
[0025] This application employs a two-transistor control method (any other similar switching components are considered to use the same approach). When no relay load output is required, regardless of whether the driver chip I / O port is high or low, due to the DC-blocking and AC-passing characteristics of capacitor C3 (AC can pass, DC cannot pass), MOSFETs Q1 / Q2 are in a non-conducting state. When it is necessary to control the switching device REL1, the MCU outputs a square wave pulse signal through the driver chip I / O port.
[0026] When the "driver chip I / O port" is at a high level of a pulse signal, the high level charges capacitor C3. When the "driver chip I / O port" is at a high level of a pulse signal, capacitor C3 flows through diode D5, and current flows from pin 3 to pin 2 of diode D5. MOSFETs Q1 / Q2 are simultaneously turned on, charging capacitor C2 to store energy. When the "driver chip I / O port" is at a high level of a pulse signal, the high level charges capacitor C3 again. At this time, capacitor C2 discharges to maintain the high level required for MOSFETs Q1 / Q2 to conduct. This process repeats, and the continuous conduction of MOSFETs Q1 / Q2 ensures the stable output of switching device REL1.
[0027] When MOSFET Q1 is short-circuited, due to the DC-blocking and AC-passing characteristics of capacitor C3, the MCU needs to output a square wave pulse signal through the "driver chip I / O port" to turn it on. The relay output is normally controlled. When the MCU does not provide a pulse signal, the relay remains constant with no output. The same applies when MOSFET Q2 is short-circuited.
[0028] In summary, this solution only requires the MCU software to output a square wave pulse signal when load output needs to be controlled, without needing to judge other I / O ports. At the same time, when performing abnormal short circuit tests, whether shorting MOSFET Q1 or MOSFET Q2, the software only needs to output a square wave signal to the driver chip's I / O port. Moreover, one load output only needs to occupy one I / O port resource, achieving the effect of reducing resources and lowering costs.
[0029] The above description is only a preferred embodiment of this application and is not intended to limit the scope of implementation of this application. Any other embodiments whose principles and basic structures are the same as or similar to those of this application are within the protection scope of this application.
Claims
1. A relay control circuit, characterized in that, The device includes a switching device REL1, whose conducting terminal is used to control the load output. Its coil anode receives a voltage, its cathode is connected to the collector of switching element Q1, and its emitter is connected to the collector of switching element Q2. The emitter of switching element Q2 is grounded. A common contact is provided between the bases of switching elements Q1 and Q2, and this common contact is grounded through capacitor C2. This common contact is also connected to the output terminal of diode D5. The ground terminal of capacitor C2 is connected to the first input terminal of diode D5, and the second input terminal of diode D5 is connected to capacitor C3. Capacitor C3 can also receive signals from the driver chip.
2. The relay control circuit according to claim 1, characterized in that: The base of the switching element Q1 is connected to a resistor R1, and the base of the switching element Q2 is connected to a resistor R2. The resistors R1 and R2 are connected to a common contact.
3. A relay control circuit according to claim 2, characterized in that: One end of the resistor R2 is grounded through capacitor C1, and the other end is grounded through resistor R4.
4. A relay control circuit according to claim 1, characterized in that: The capacitor C3 is connected to a resistor R5.
5. A relay control circuit according to claim 1, characterized in that: A diode D4 is connected between the anode and cathode of the coil end of the switching device REL1.
6. A relay control circuit according to claim 1, characterized in that: The switching device REL1 is a relay or a thyristor.
7. A relay control circuit according to claim 1, characterized in that: The switching element Q1 is a transistor or a MOSFET.