CN204289267U - Relay low voltage starting circuit and electronic equipment - Google Patents

Abstract

The utility model discloses a relay low-voltage starting circuit and electronic equipment, this relay low-voltage starting circuit is used for starting the relay of connection between live wire and load, including first power module, second power module, voltage detection module, control module and switch module, first power module and second power module are used for providing the starting voltage for the relay, and voltage detection module is used for detecting the voltage value of first power module output and transmits control module, and control module is used for receiving the voltage value that voltage detection module detected and compares voltage value and default, sends control signal to switch module according to the comparison result; when the external voltage is reduced, the first power supply module is not enough to start the relay, and then the control module controls the switch module to disconnect the connection between the first power supply module and the relay and to switch on the connection between the second power supply module and the relay, so that the relay is started in a low-voltage state.

Description

Relay low voltage starting circuit and electronic equipment

technical field

The utility model relates to the field of power supplies, in particular to a relay low-voltage starting circuit and electronic equipment.

Background technique

Usually, the traditional fixed-frequency air-conditioning power supply circuit is stepped down by a transformer, and then output to the rectifier unit, rectified by the rectifier unit into a DC power supply, and then filtered by a filter capacitor to filter out high-order harmonics, and then output a stable DC power supply to the relay, so that After the relay is activated, the control load is powered on. However, the output voltage of the linear transformer decreases with the decrease of the input voltage. Therefore, when the voltage instability in some areas reduces the output voltage of the transformer, the output voltage after rectification will also decrease, causing the relay to fail to open. A/C not working.

Utility model content

The main purpose of the utility model is to provide a low-voltage starting circuit for a relay, which aims at enabling the relay to start even when the external input voltage is low.

In order to achieve the above purpose, the utility model provides a relay low-voltage starting circuit, which is used to start the relay connected between the live wire and the load, including a first power supply module, a second power supply module, a voltage detection module, a control module and a switch module , the first power supply module is connected to the relay through the switch module, the second power supply module is connected to the relay through the switch module, and the output terminal of the first power supply module is connected to the voltage detection module connected to the detection terminal, the output terminal of the voltage detection module is connected to the input terminal of the control module, and the control module is respectively connected to the switch module and the relay; wherein, the voltage detection module detects the first A voltage value output by a power supply module and transmit the voltage value to the control module, the control module compares the voltage value with a preset value, and sends a control signal to the switch module according to the comparison result, the The switch module turns on the connection between the first power module and the relay based on the control signal, so that the first power module supplies power to the relay; or turns on the second power module and the relay The connection between them enables the second power supply module to supply power to the relay, and the voltage value output by the second power supply module is not equal to the voltage value output by the first power supply module.

Preferably, the voltage value output by the second power module is greater than the voltage value output by the first power module, the switch module includes a first switch unit and a second switch unit, when the voltage output by the first power module When the value is greater than or equal to the preset value, the control module turns on the first switch unit and turns off the second switch unit, so that the first power supply module supplies power to the relay; when the When the voltage value output by the first power module is less than the preset value, the control module turns on the second switch unit and turns off the first switch unit, so that the second power module is the relay powered by.

Preferably, the first switch unit includes a first triode, the second switch unit includes a second triode, the emitter of the first triode is connected to the output terminal of the first power module , the collector of the first triode is connected to the first end of the control coil of the relay, the base of the first triode is connected to the first control terminal of the control module; the second The emitter of the triode is connected to the output terminal of the second power supply module, the collector of the second triode is connected to the first end of the control coil of the relay, and the base of the second triode is The pole is connected with the second control terminal of the control module.

Preferably, the first triode and the second triode are PNP transistors.

Preferably, the first power module includes a first secondary coil of a transformer, a first rectifier bridge, a first electrolytic capacitor and a first ceramic chip capacitor, one end of the first secondary coil is connected to the first rectifier bridge The first input end of the first secondary coil is connected, the other end of the first secondary coil is connected to the second input end of the first rectifier bridge; the first electrolytic capacitor is connected in parallel with the first ceramic capacitor; the second The positive pole of an electrolytic capacitor is connected to the first output end of the first rectifier bridge, and the negative pole of the first electrolytic capacitor is connected to the second output end of the first rectifier bridge and grounded; The common end of the anode and the first output end of the first rectifier bridge is connected to the input end of the first switch unit as the output end of the first power supply module.

Preferably, the second power supply module includes a second secondary coil of a transformer, a second rectifier bridge, a second electrolytic capacitor and a second ceramic chip capacitor, one end of the second secondary coil is connected to the second rectifier bridge The first input end of the second secondary coil is connected, the other end of the second secondary coil is connected to the second input end of the second rectifier bridge; the second electrolytic capacitor is connected in parallel with the second ceramic capacitor; the second The positive pole of the second electrolytic capacitor is connected to the first output end of the second rectifier bridge, and the negative pole of the second electrolytic capacitor is connected to the second output end of the second rectifier bridge and grounded; The common end of the anode and the first output end of the second rectifier bridge is used as the output end of the second power module and connected to the input end of the second switch unit.

Preferably, the voltage detection module includes a first resistor and a second resistor, one end of the first resistor is connected to the output end of the first power supply module, the other end of the first resistor is grounded through the second resistor, The common terminal between the first resistor and the second resistor is used as the output terminal of the voltage detection module and connected to the input terminal of the control module.

Preferably, the relay low-voltage starting circuit further includes a third triode, the base of the third triode is connected to the third control terminal of the control module, and the collector of the third triode It is connected with the second end of the control coil of the relay, and the emitter of the third triode is grounded; the third triode is an NPN type triode.

Preferably, the relay low-voltage starting circuit further includes a diode for reverse current protection of the relay, the anode of the diode is connected to the collector of the third triode, and the cathode of the diode is connected to the collector of the third triode. The first end of the control coil of the relay is connected.

In addition, in order to achieve the above object, the utility model also provides an electronic device, the electronic device includes a relay low-voltage starting circuit, the relay low-voltage starting circuit is used to start the relay connected between the live wire and the load, including a first power supply module, a second power supply module, a voltage detection module, a control module and a switch module, the first power supply module is connected to the relay through the switch module, and the second power supply module is connected to the relay through the switch module , the output end of the first power supply module is connected to the detection end of the voltage detection module, the output end of the voltage detection module is connected to the input end of the control module, and the control module is respectively connected to the switch module and the The relay is connected; wherein, the voltage detection module detects the voltage value output by the first power supply module and transmits the voltage value to the control module, and the control module compares the voltage value with a preset value comparing, sending a control signal to the switch module according to the comparison result, and the switch module conducts the connection between the first power supply module and the relay based on the control signal, so that the first power supply module is the supply power to the relay; or turn on the connection between the second power supply module and the relay, so that the second power supply module supplies power to the relay, and the output voltage value of the second power supply module is not equal to the first The output voltage value of the power module.

The utility model provides a relay low-voltage starting circuit and electronic equipment including the relay low-voltage starting circuit. The starting voltage of the relay low-voltage starting circuit is selectively provided by the first power module and the second power module. When the external voltage input is normal, the first power supply module provides the voltage for starting the relay; when the external voltage is unstable and lower than the normal range, at this time, the output voltage value of the first power supply module detected by the voltage detection module will also be low Based on the preset value of the control module, the control module controls the switch module to conduct the connection between the second power supply module and the relay. Since the output of the second power supply module is higher than the output of the first power supply module, even if the external voltage decreases, the first The output of the power supply module and the second power supply module is lower than the normal value, but the output of the second power supply module is enough to turn on the relay, so as to realize the low voltage turn on of the relay, so that the electronic equipment can work normally even in the low voltage state.

Description of drawings

FIG. 1 is a schematic diagram of a circuit structure of a preferred embodiment of the present invention.

The realization of the purpose of the utility model, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The utility model provides a low-voltage starting circuit for a relay.

In the embodiment of the utility model, referring to Fig. 1, the relay low-voltage starting circuit is used to start the relay RM1 connected between the live line L and the load Load, including a first power module 100, a second power module 200, a voltage detection Module 300, control module 400 and switch module 500, the first power module 100 is connected to the relay RM1 through the switch module 500, and the second power module 200 is connected to the relay RM1 through the switch module 500 , the output terminal of the first power supply module 100 is connected to the detection terminal of the voltage detection module 300, the output terminal of the voltage detection module 300 is connected to the input terminal I/O1 of the control module 400, and the control module 400 are respectively connected to the switch module 500 and the relay RM1; wherein the voltage detection module 300 detects the voltage value output by the first power supply module 100 and transmits the voltage value to the control module 400, so The control module 400 compares the voltage value with a preset value, and sends a control signal to the switch module 500 according to the comparison result, and the switch module 500 conducts the first power supply module 100 and the The connection between the relay RM1, so that the first power module 100 supplies power to the relay RM1; or the connection between the second power module 200 and the relay RM1 is turned on, so that the second power module 200 supplies power to the relay RM1, and the voltage value output by the second power module 200 is not equal to the voltage value output by the first power module 100 .

Specifically, the voltage value output by the second power module 200 is greater than the voltage value output by the first power module 100, the switch module 500 includes a first switch unit and a second switch unit, when the first power module 100 outputs When the voltage value is greater than or equal to the preset value, the control module 400 turns on the first switch unit and turns off the second switch unit, so that the first power module 100 is the relay RM1 power supply; when the voltage value output by the first power supply module 100 is less than the preset value, the control module 400 turns on the second switch unit and turns off the first switch unit, so that the second The second power supply module 200 supplies power to the relay RM1.

Usually, the load Load is a fixed-frequency air conditioner, and the power circuit of the fixed-frequency air conditioner controls the pull-in and disconnection of the relay RM1 through the first power module 100 , so as to control the conduction or disconnection of the load Load and the live line L. Since the voltage of the first power module 100 is unstable, when the voltage value output by the first power module 100 detected by the voltage detection module 300 is lower than the preset value of the control module 400, that is, the output voltage value of the first power module 100 is insufficient. Start with the control relay RM1, so the fixed-frequency air conditioner will not work normally; at this time, the control module 400 controls the switch module 500 to turn on the second power module 200, because the output voltage value of the second power module 200 is higher than that of the first power module 100 The output voltage value, so the voltage value output by the second power supply module 200 will make the relay RM1 open, the relay RM1 will pull in, connect the fixed-frequency air conditioner with the live line L, and the fixed-frequency air conditioner will work normally; thus realizing the low-voltage state of the relay RM1 It can also start normally.

Specifically, the first switch unit includes a first transistor Q1, the second switch unit includes a second transistor Q2, and the emitter of the first transistor Q1 serves as the input terminal of the first switch unit and the first power supply The output terminal of the module 100 is connected, and the emitter of the second transistor Q2 is connected to the output terminal of the second power supply module 200 as the input terminal of the second switch unit; the base of the first transistor Q1 is connected to the second transistor Q1 The base of Q2 is connected to the first control terminal I/O2 and the second control terminal I/O3 of the control module 400 respectively as the control terminal of the switch module 500; the collector of the first transistor Q1 is connected to the second transistor Q2 is connected to the collector, and the common node is connected to the first terminal e of the control coil of the relay RM1 as the output terminal of the switch module 500 .

In this embodiment, the first power module 100 and the second power module 200 are respectively provided by two secondary side coils after the step-down of the transformer, and the voltage output by the first secondary coil S1 after the step-down of the transformer is preferably AC 12V, the AC 12V is rectified by the first rectifier bridge B1, and outputs 12V DC; at this time, the output 12V DC has other harmonics, between the first output terminal c and the second output terminal d of the first rectifier bridge B1 The first electrolytic capacitor C1 and the first ceramic capacitor C2 are connected in parallel for filter processing to obtain a stable 12V DC. The voltage output by the second secondary coil S2 after the step-down treatment of the transformer is preferably AC 18V, and the AC 18V is rectified by the second rectifier bridge B2 to output 18V DC; at this time, the output 18V DC has other harmonics. A second electrolytic capacitor C3 and a second ceramic capacitor C4 are connected in parallel between the first output terminal c' and the second output terminal d' of the second rectifier bridge B2 to perform filtering processing to obtain a stable 18V direct current.

Specifically, the voltage value output by the first secondary coil S1 and the second secondary coil S2 can be obtained by adjusting the turns ratio of the transformer according to actual needs, which is not limited here; the structure of the first rectifier bridge B1 and the second rectifier bridge B2 The same, are composed of four diodes connected end to end.

When the voltage on the input side of the transformer is stable, that is, the 12V DC output from the first power module 100 is stable, at this time, the 12V DC voltage can maintain the normal startup of the relay RM1; the voltage formed by the series connection of the first resistor R1 and the second resistor R2 The detection module 300 performs voltage detection on the output of the first power supply module 100, the first resistor R1 is connected to the output terminal of the first power supply module 100, and the common node is the detection terminal of the voltage detection module 300; since the first resistor R1 and the second The resistor R2 forms a voltage divider circuit, and the common terminal of the first resistor R1 and the second resistor R2 is the output terminal of the voltage detection module 300, and the detection voltage is obtained by dividing the voltage by the second resistor R2. The voltage will also be fixed, and the detected voltage is passed to the control module 400; the control module 400 is preferably an MCU in this embodiment, and an AD conversion module is integrated inside it, and the MCU performs AD on the received voltage value After conversion, compared with the internal preset value, if the input side of the transformer is stable, the voltage value will be greater than or equal to the preset value, that is, the first control terminal I/O2 of the MCU will continuously output low level to the first The base of the transistor Q1 makes the first transistor Q1 continuously conduct, and the first power module 100 and the relay RM1 are continuously connected, so that the first power module 100 continuously provides the starting voltage for the relay RM1.

Specifically, in order to prevent the MCU from being burned due to excessive current, a current limiting resistor R3 is added between the output terminal of the voltage detection module 300 and the input terminal I/O1 of the MCU.

When the voltage on the input side of the transformer is unstable, the voltage on the input side of the transformer will be lower than the normal value, so the output of the first power module 100 will also be lower than 12V DC, and the DC voltage output by the first power module 100 will not be sufficient for normal startup Relay RM1; at this time, the output of the second power module 200 will be lower than 18V, but the output voltage of the second power module 200 is sufficient to activate the relay RM1. Then after the output voltage of the first power supply module 100 detected by the voltage detection module 300 is transmitted to the MCU, compared with the internal preset value, it will also be lower than the preset value, and the second control terminal I/O3 of the MCU will be Outputting a low level to the base of the second transistor Q2, turning on the second transistor Q2, so that the second power module 200 and the relay RM1 are continuously connected, so that the second power module 200 provides start-up for the relay RM1 Voltage, when the input side of the transformer is at low voltage, the relay RM1 can also be activated, which is convenient for the normal use of the fixed-frequency air conditioner.

Specifically, the first transistor Q1 and the second transistor Q2 are preferably PNP transistors.

Further, in order to make the relay RM1 start, its control coil forms a loop, the first end e of the control coil is connected to the collectors of the first triode Q1 and the second triode Q2, and the second end f of the control coil It can be grounded, so that when the first end e of the control coil has a high-level input, the relay RM1 can be turned on; but in order to make the performance of the relay RM1 stable, the relay RM1 will only start when all parts of the circuit are connected normally. The second terminal f of the control coil is connected to a third transistor Q3, the collector of the third transistor Q3 is connected to the second terminal f of the control coil, its emitter is grounded, and its base is connected to the third control circuit of the MCU. The terminal I/O4 is connected, so that when all parts of the circuit are operating normally, the third control terminal I/O4 of the MCU outputs a high level, and the third transistor Q3 is turned on. At this time, the control coil passes through the third three The pole tube Q3 is grounded, and the relay RM1 works normally.

Specifically, the third transistor Q3 is preferably an NPN transistor

Further, a diode D1 is connected between the collector of the third triode Q3 and the first end e of the control coil of the relay RM1, the anode of the diode D1 is connected to the collector of the third triode Q3, and its cathode is connected to the relay RM1 The first end e of the control coil of RM1 is connected to prevent the control coil of the relay RM1 from being burned out due to the unidirectional conductivity of the diode D1.

The utility model also provides an electronic device, which includes the relay low-voltage starting circuit described in the above-mentioned embodiment. The structure, working principle and beneficial effects of the relay low-voltage starting circuit all refer to the above-mentioned embodiment. description and will not be repeated here.

The above are only preferred embodiments of the present utility model, and are not intended to limit the patent scope of the present utility model. Any equivalent structure or equivalent process conversion made by using the description of the utility model and the contents of the accompanying drawings, or directly or indirectly used in other related All technical fields are all included in the scope of patent protection of the utility model in the same way.

Claims (10)

1. a relay low voltage start circuit, for starting the relay be connected between live wire and load, it is characterized in that, comprise the first power module, second source module, voltage detection module, control module and switch module, described first power module is connected with described relay by described switch module, described second source module is connected with described relay by described switch module, the output of described first power module is connected with the test side of described voltage detection module, the output of described voltage detection module is connected with the input of described control module, described control module is connected with described switch module and described relay respectively, wherein, described voltage detection module detects the magnitude of voltage of described first power module output and described magnitude of voltage is transferred to described control module, described magnitude of voltage and preset value compare by described control module, send according to comparative result and control signal to described switch module, described switch module, based on the connection described in described control signal conducting between the first power module and described relay, makes described first power module be that described relay is powered, or the connection described in conducting between second source module and described relay, make described second source module be that described relay is powered, the magnitude of voltage that described second source module exports is not equal to the magnitude of voltage that described first power module exports.

2. relay low voltage start circuit as claimed in claim 1, it is characterized in that, the magnitude of voltage that described second source module exports is greater than the magnitude of voltage that described first power module exports, described switch module comprises the first switch element and second switch unit, when the magnitude of voltage that described first power module exports is more than or equal to described preset value, first switch element described in described control module conducting, and disconnect described second switch unit, make described first power module be that described relay is powered; When the magnitude of voltage that described first power module exports is less than described preset value, second switch unit described in described control module conducting, and disconnect described first switch element, make described second source module be that described relay is powered.

3. relay low voltage start circuit as claimed in claim 2, it is characterized in that, described first switch element comprises the first triode, described second switch unit comprises the second triode, the emitter of described first triode is connected with the output of described first power module, the collector electrode of described first triode is connected with the first end of the control coil of described relay, and the base stage of described first triode is connected with the first control end of described control module; The emitter of described second triode is connected with the output of described second source module, the collector electrode of described second triode is connected with the first end of the control coil of described relay, and the base stage of described second triode is connected with the second control end of described control module.

4. relay low voltage start circuit as claimed in claim 3, it is characterized in that, described first triode and described second triode are PNP type triode.

5. relay low voltage start circuit as claimed in claim 2, it is characterized in that, described first power module comprises the first secondary coil of transformer, the first rectifier bridge, the first electrochemical capacitor and the first ceramic disc capacitor, one end of described first secondary coil is connected with the first input end of described first rectifier bridge, and the other end of described first secondary coil is connected with the second input of described first rectifier bridge; Described first electrochemical capacitor is in parallel with described first ceramic disc capacitor; The positive pole of described first electrochemical capacitor is connected with the first output of described first rectifier bridge, and the negative pole of described first electrochemical capacitor is connected rear ground connection with the second output of described first rectifier bridge; The positive pole of described first electrochemical capacitor is connected with the input of described first switch element with the output of the common port of the first output of described first rectifier bridge as described first power module.

6. relay low voltage start circuit as claimed in claim 2, it is characterized in that, described second source module comprises the second subprime coil of transformer, the second rectifier bridge, the second electrochemical capacitor and the second ceramic disc capacitor, one end of described second subprime coil is connected with the first input end of described second rectifier bridge, and the other end of described second subprime coil is connected with the second input of described second rectifier bridge; Described second electrochemical capacitor is in parallel with described second ceramic disc capacitor; The positive pole of described second electrochemical capacitor is connected with the first output of described second rectifier bridge, and the negative pole of described second electrochemical capacitor is connected rear ground connection with the second output of described second rectifier bridge; The positive pole of described second electrochemical capacitor is connected with the input of described second switch unit with the output of the common port of the first output of described second rectifier bridge as described second source module.

7. relay low voltage start circuit as claimed in claim 1, it is characterized in that, described voltage detection module comprises the first resistance, the second resistance, one end of described first resistance is connected with the output of the first power module, the other end of described first resistance is through described second grounding through resistance, and the common port between described first resistance with described second resistance is connected with the input of described control module as the output of described voltage detection module.

8. relay low voltage start circuit as claimed in claim 1, it is characterized in that, described relay low voltage start circuit also comprises the 3rd triode, the base stage of described 3rd triode is connected with the 3rd control end of described control module, the described collector electrode of the 3rd triode is connected with the second end of the control coil of described relay, the grounded emitter of described 3rd triode; Described 3rd triode is NPN type triode.

9. relay low voltage start circuit as claimed in claim 8; it is characterized in that; described relay low voltage start circuit also comprises one for carrying out the diode of reverse-current protection to relay; the anode of described diode is connected with the collector electrode of described 3rd triode, and the negative electrode of described diode is connected with the first end of the control coil of described relay.

10. an electronic equipment, is characterized in that, comprises the relay low voltage start circuit according to any one of claim 1 to 9.