Relay control circuit

Abstract

The utility model provides a relay control circuit. The relay control circuit comprises a relay switch circuit, an output control circuit and a differential amplification circuit. One end of the relay switch circuit is connected with the relay and is used for controlling the on and off of the relay; the output end of the output control circuit is connected with the other end of the relay switch circuit and is used for controlling the on and off of the relay switch circuit, and one output end of the output control circuit is connected with the sawtooth wave generating circuit; the input end of the differential amplification circuit is connected with the power supply circuit, and the output end of the differential amplification circuit is connected with the other input end of the output control circuit. According to the utility model, power loss of the relay can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of relays, in particular to a relay control circuit. Background Art

[0002] A relay is an electrical control component with isolation function, usually used in automated control circuits. It is a switch that uses a small current to control the operation of a large current, so it plays the role of electrical isolation and safety protection in the circuit.

[0003] There are two main electrical components of a relay, one is the coil part and the other is the switch part. The coil is the driving part or the input part. When the coil is energized, a magnetic field is generated, and the magnetic force closes the iron switch. The components connected to both sides of the switch can achieve electrical connection.

[0004] The commonly used setting method at present is to set the corresponding voltage according to the electrical specifications of the relay. For example, if the working voltage of the relay coil is 12V, then adding a 12V DC voltage to the coil can close the relay switch and achieve the purpose of connecting the control circuit.

[0005] Relays are used in most power supplies. Since the relay coil has a certain impedance, it will lose some power. For some power supplies with low power but high efficiency requirements, the power loss caused by the relay accounts for a large proportion, reducing the power supply efficiency of the power supply. Utility Model Content

[0006] The utility model provides a relay control circuit, aiming to solve the problem of large power loss generated by the relay in the current power supply.

[0007] The utility model provides a relay control circuit, which comprises a relay switch circuit, an output control circuit and a differential amplifier circuit; one end of the relay switch circuit is connected to the relay for controlling the on and off of the relay; the output end of the output control circuit is connected to the other end of the relay switch circuit for controlling the on and off of the relay switch circuit, and one output end of the output control circuit is connected to a sawtooth wave generating circuit; the input end of the differential amplifier circuit is connected to a power supply circuit, and the output end of the differential amplifier circuit is connected to the other input end of the output control circuit.

[0008] Furthermore, the relay switch circuit includes a first switch tube and a switch element, the controlled end of the first switch tube is connected to one end of the switch element, the first pole of the first switch tube is connected to the relay, the second pole of the first switch tube is connected to the negative pole of the power supply, and the other end of the switch element is connected to the output end of the output control circuit.

[0009] Furthermore, the relay switch circuit also includes a first diode, which is connected in parallel with the relay.

[0010] Furthermore, the relay switching circuit also includes a current limiting circuit and a voltage divider circuit; one end of the current limiting circuit is connected to the power supply, and the other end of the current limiting circuit is connected to the relay; one end of the voltage divider circuit is connected to the power supply, and the other end of the voltage divider circuit is connected to the controlled end of the first switch tube.

[0011] Furthermore, the current limiting circuit includes a first resistor, one end of the first resistor is connected to the cathode of the first diode and the relay respectively, and the other end of the first resistor is connected to the power supply.

[0012] Furthermore, the voltage divider circuit also includes a second resistor, a third resistor and a fourth resistor; one end of the second resistor is connected to the power supply, the other end of the second resistor is respectively connected to one end of the third resistor and the switching element, the other end of the third resistor is respectively connected to one end of the fourth resistor and the controlled end of the first switching tube, and the other end of the fourth resistor is connected to the negative electrode of the power supply.

[0013] Furthermore, the output control circuit includes a voltage comparator, the inverting input terminal of the voltage comparator is connected to the output terminal of the differential amplifier circuit, the non-inverting input terminal of the voltage comparator is connected to the sawtooth wave generating circuit, and the output terminal of the voltage comparator is connected to the relay switch circuit.

[0014] Furthermore, the differential amplifier circuit includes a differential amplifier and a fifth resistor, the two ends of the fifth resistor are respectively connected to the two input pins of the differential amplifier for sampling the power supply circuit, and an output pin of the differential amplifier is connected to the inverting input terminal of the voltage comparator.

[0015] Furthermore, it also includes a time-delay conduction circuit, the input end of the time-delay conduction circuit is connected to the power supply, and the output end of the time-delay conduction circuit is connected to the non-inverting input end of the voltage comparator.

[0016] Furthermore, the delayed conduction circuit includes a second switch tube and a third switch tube; the controlled end of the second switch tube is connected to the power supply, the first pole of the second switch tube is connected to the controlled end of the third switch tube, the first pole of the third switch tube is connected to the non-inverting input end of the voltage comparator, and the second pole of the second switch tube and the second pole of the third switch tube are both grounded.

[0017] The relay control circuit disclosed in the utility model comprises a relay switch circuit, an output control circuit and a differential amplifier circuit. The differential amplifier circuit is connected to the power supply circuit, and is used for collecting the current of the power supply circuit and amplifying it, and outputting a corresponding voltage value to the output control circuit. The output control circuit is also connected to the sawtooth wave generating circuit, and the sawtooth wave generating circuit outputs a continuously changing voltage to the output control circuit. The output control circuit outputs a corresponding signal to the relay switch circuit according to the voltage output by the differential amplifier circuit and the voltage output by the sawtooth wave generating circuit, so as to control the conduction and cutoff of the relay switch circuit. The voltage output by the differential amplifier circuit is related to the current of the power supply circuit. When the current of the power supply circuit is larger, the working time of the relay is longer. The longer the working time, the larger the duty cycle of the relay, thereby reducing the power loss of the relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a block diagram of a relay control circuit provided by an embodiment of the utility model;

[0020] Figure 2 is a block diagram of a relay control circuit provided by another embodiment of the utility model;

[0021] Figure 3 It is a circuit diagram of a relay switch circuit provided by an embodiment of the utility model;

[0022] Figure 4 It is a circuit diagram of an output control circuit and a differential amplifier circuit provided in one embodiment of the utility model;

[0023] Figure 5 It is a circuit diagram of a delayed conduction circuit provided in one embodiment of the utility model. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, operations, elements, components and / or groups thereof.

[0026] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in the utility model specification and the appended claims, the singular forms of "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the utility model specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0027] In addition, the directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", etc., are only for reference to the directions of the attached drawings and the use status of the product. Therefore, the directional terms used are used to illustrate and understand the present invention, but not to limit the present invention. In addition, in the drawings, structures with similar or identical structures are represented by the same reference numerals.

[0028] See also Figures 1 to 5 , Figure 1 1 is a block diagram of a relay control circuit 100 provided in one embodiment of the present utility model; Figure 2 is a block diagram of a relay control circuit 100 provided in another embodiment of the present utility model; Figure 3 1 is a circuit diagram of a relay switch circuit 10 provided in one embodiment of the utility model; Figure 4 1 is a circuit diagram of an output control circuit 20 and a differential amplifier circuit 30 provided in an embodiment of the present utility model;

[0029] Figure 5 FIG. 4 is a circuit diagram of a time-delay conduction circuit 40 provided in an embodiment of the present utility model. Figure 1As shown, the relay control circuit 100 includes a relay switch circuit 10, an output control circuit 20 and a differential amplifier circuit 30; one end of the relay switch circuit 10 is connected to the relay RL1 for controlling the on and off of the relay RL1; the output end of the output control circuit 20 is connected to the other end of the relay switch circuit 10 for controlling the on and off of the relay switch circuit 10, and one output end of the output control circuit 20 is connected to the sawtooth wave generating circuit 200; the input end of the differential amplifier circuit 30 is connected to the power supply circuit, and the output end of the differential amplifier circuit 30 is connected to the other input end of the output control circuit 20.

[0030] Specifically, the relay control circuit 100 may include a relay switch circuit 10, an output control circuit 20, and a differential amplifier circuit 30. The input end of the differential amplifier circuit 30 is connected to the power supply circuit, and is used to collect the current of the power supply circuit and generate a corresponding voltage, and amplify the generated voltage and output it to an input end of the output control circuit 20. At the same time, the output control circuit 20 is also connected to the sawtooth wave generating circuit 200. The specific circuit structure of the sawtooth wave generating circuit 200 is a circuit structure commonly used in the art, and will not be described here. The sawtooth wave generating circuit 200 can output a continuous voltage signal, which is output to the other input end of the output control circuit 20.

[0031] The output control circuit 20 outputs a corresponding level signal to the relay switch circuit 10 according to the magnitude between the voltage output by the differential amplifier circuit 30 and the voltage output by the sawtooth wave generating circuit 200, thereby controlling the on and off of the relay switch circuit 10, and further controlling the on and off of the relay RL1.

[0032] The voltage output by the differential amplifier circuit 30 is set to I_SENSE1, and the voltage output by the sawtooth wave generating circuit 200 is set to I_SENSE2. The output control circuit 20 outputs a corresponding level signal according to the size between I_SENSE1 and I_SENSE2. For example, if the relay switch circuit 10 is set to be turned on at a low level and turned off at a high level, when the voltage of I_SENSE1 is greater than the voltage of I_SENSE2, the output control circuit 20 outputs a low level, the relay switch circuit 10 is turned on, and the relay RL1 works. If the voltage of I_SENSE1 is less than the voltage of I_SENSE2, the output control circuit 20 outputs a high level, the relay switch circuit 10 is turned off, and the relay RL1 stops working. I_SENSE1 is related to the current of the power supply circuit. The larger the current of the power supply circuit, the larger I_SENSE1, the longer the conduction time of the relay switch circuit 10, the longer the working time of the relay RL1, and the larger the duty cycle of the relay RL1. Therefore, the duty cycle of the relay RL1 can increase with the increase of the output current of the power supply circuit, thereby reducing the loss of the relay RL1.

[0033] See also Figure 3 As a further embodiment, the relay switch circuit 10 includes a first switch tube Q1 and a switch element IC1, the controlled end of the first switch tube Q1 is connected to one end of the switch element IC1, the first pole of the first switch tube Q1 is connected to the relay RL1, the second pole of the first switch tube Q1 is connected to the negative pole of the power supply, and the other end of the switch element IC1 is connected to the output end of the output control circuit 20.

[0034] The relay switch circuit 10 may include a first switch tube Q1 and a switch element IC1. The first switch tube Q1 may be a triode, and the base of the first switch tube Q1 is connected to one end of the switch element IC1, the collector of the first switch tube Q1 is connected to the relay RL1, and the emitter of the first switch tube Q1 is grounded. The other end of the switch element IC1 is connected to the output control circuit 20. When the output control circuit 20 outputs a low level, the switch element IC1 is turned on, thereby turning on the first switch tube Q1 and the relay RL1. The switch element IC1 may be a photocoupler. When the output control circuit 20 outputs a high level, the secondary side of the photocoupler is turned on, and the first switch tube Q1 is turned off. When the output control circuit 20 outputs a low level, the photocoupler is turned off, the first switch tube Q1 is turned on, and the relay RL1 is turned on.

[0035] As a further embodiment, the relay switch circuit 10 further includes a first diode D1 , and the first diode D1 is connected in parallel with the relay RL1 .

[0036] The first diode D1 is connected in parallel with the relay RL1 , and its anode is also connected to the collector of the first switch tube Q1 . When the first switch tube Q1 is disconnected, the coil current of the relay RL1 is released through the first diode D1 .

[0037] As a further embodiment, the relay switch circuit 10 also includes a current limiting circuit 11 and a voltage divider circuit 12; one end of the current limiting circuit 11 is connected to the power supply, and the other end of the current limiting circuit 11 is connected to the relay RL1; one end of the voltage divider circuit 12 is connected to the power supply, and the other end of the voltage divider circuit 12 is connected to the controlled end of the first switch tube Q1.

[0038] Furthermore, the current limiting circuit 11 includes a first resistor R1 , one end of the first resistor R1 is connected to the cathode of the first diode D1 and the relay RL1 , respectively, and the other end of the first resistor R1 is connected to the power supply.

[0039] Furthermore, the voltage divider circuit 12 also includes a second resistor R2, a third resistor R3 and a fourth resistor R4; one end of the second resistor R2 is connected to the power supply, the other end of the second resistor R2 is respectively connected to one end of the third resistor R3 and the switching element IC1, the other end of the third resistor R3 is respectively connected to one end of the fourth resistor R4 and the controlled end of the first switch tube Q1, and the other end of the fourth resistor R4 is connected to the negative electrode of the power supply.

[0040] The current limiting circuit 11 is connected between the power supply voltage and the relay RL1, and is used to limit the current flowing through the coil of the relay RL1. Figure 3 As shown, Figure 3 The VCP in the figure is a signal voltage, which is used as the power supply voltage of the relay RL1. The second resistor R2, the third resistor R3 and the fourth resistor R4 form a voltage divider circuit 12 for voltage division. When the switch element IC1 is turned off, the current of VCP flows to the base of the first switch tube Q1 through the second resistor R2 and the third resistor R3, so that the first switch tube Q1 is turned on, and then the current of VCP can flow to the relay RL1, and the relay RL1 is closed.

[0041] See also Figure 4 As a further embodiment, the output control circuit 20 includes a voltage comparator IC3, the inverting input terminal of the voltage comparator IC3 is connected to the output terminal of the differential amplifier circuit 30, the non-inverting input terminal of the voltage comparator IC3 is connected to the sawtooth wave generating circuit 200, and the output terminal of the voltage comparator IC3 is connected to the relay switch circuit 10.

[0042] Among them, Figure 4As shown, the output control circuit 20 includes a voltage comparator IC3, the inverting input terminal of the voltage comparator IC3 is connected to the differential amplifier circuit 30, and the non-inverting input terminal of the voltage comparator IC3 is connected to the sawtooth wave generating circuit 200. The voltage comparator IC3 compares the magnitudes of the voltages output by the differential amplifier circuit 30 and the sawtooth wave generating circuit 200 to output a corresponding level signal to control the on and off of the relay switch circuit 10.

[0043] The output control circuit 20 may further include a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second diode D2, a third diode D3 and a first capacitor C1. The voltage signal output by the differential amplifier circuit 30 enters the inverting input terminal of the voltage comparator IC3 through the sixth resistor R6 and the third diode D3, and at the same time, the voltage of the power supply voltage VCC also enters the inverting input terminal of the voltage comparator IC3 through the second diode D2 and the seventh resistor R7. The first capacitor C1 is used as a filter capacitor to filter out high-frequency noise. When the output current of the power supply circuit is small, the third diode D3 is cut off, and the voltage of VCC is output to the inverting input terminal of the voltage comparator IC3, so that the inverting input terminal of the voltage comparator IC3 has an initial voltage. Generally, the initial voltage corresponds to the output voltage of the power supply when it is half loaded, thereby ensuring that no matter how much the output current of the power supply circuit is, the voltage of the inverting input terminal of the voltage comparator IC3 will not be less than the voltage of the power supply when it is half loaded, ensuring that the duty cycle of the relay RL1 is at least above 50%, and ensuring the stability of the relay RL1.

[0044] As a further embodiment, the differential amplifier circuit 30 includes a differential amplifier IC2 and a fifth resistor R5, the two ends of the fifth resistor R5 are respectively connected to the two input pins of the differential amplifier IC2 for sampling the power supply circuit, and an output pin of the differential amplifier IC2 is connected to the inverting input terminal of the voltage comparator IC3.

[0045] Among them, the differential amplifier IC2 can be a chip with a built-in differential amplifier, the two input pins of the chip are connected to the two ends of the fifth resistor R5, and the output pin of the chip is connected to the inverting input end of the voltage comparator IC3. The fifth resistor R5 is used as a sampling resistor and is connected between Output_Z and Output_L of the power supply circuit. When current passes through the fifth resistor R5, a voltage difference is generated at both ends of the fifth resistor R5. The larger the current, the larger the voltage difference. The voltage difference signal is input to the differential amplifier IC2, and after being amplified by the differential amplifier IC2, the corresponding voltage signal is output to the voltage comparator IC3.

[0046] See also Figure 2 and Figure 5As a further embodiment, it further includes a time-delay conduction circuit 40, the input end of the time-delay conduction circuit 40 is connected to the power supply, and the output end of the time-delay conduction circuit 40 is connected to the non-inverting input end of the voltage comparator IC3.

[0047] Furthermore, the delayed conduction circuit 40 includes a second switch tube Q2 and a third switch tube Q3; the controlled end of the second switch tube Q2 is connected to the power supply, the first electrode of the second switch tube Q2 is connected to the controlled end of the third switch tube Q3, the first electrode of the third switch tube Q3 is connected to the in-phase input end of the voltage comparator IC3, and the second electrode of the second switch tube Q2 and the second electrode of the third switch tube Q3 are both grounded.

[0048] Among them, Figure 5 As shown, the delayed conduction circuit 40 may include a second switch tube Q2 and a third switch tube Q3. The second switch tube Q2 may be a MOS tube, and the gate of the second switch tube Q2 is connected to the power supply, the source thereof is grounded, and the drain thereof is connected to the controlled end of the third switch tube Q3. The third switch tube Q3 may be a triode, and the base of the third switch tube Q3 is connected to the drain of the second switch tube Q2, the collector thereof is connected to the in-phase input end of the voltage comparator IC3, and the emitter thereof is grounded.

[0049] When the power supply is just started, the supply voltage VCC rises from 0V to 18V, and charges the second capacitor C2 through the thirteenth resistor R13 and the fourteenth resistor R14. Generally, the resistance of the thirteenth resistor R13 is large, and the capacitance of the second capacitor is large, so the charging speed is slow. At this time, the second switch tube Q2 is cut off, and the VCC current passes through the sixteenth resistor and the seventeenth resistor to turn on the third switch tube Q3, pulling down the voltage of the non-inverting input terminal of the voltage comparator IC3. The voltage comparator IC3 outputs a low level, and the relay RL1 is continuously turned on, thereby ensuring that when the power supply is just started, the relay RL1 can be closed immediately. When the electric quantity of the second capacitor C2 gradually increases to the turn-on voltage of the second switch tube Q2, the second switch tube Q2 is turned on, and the third switch tube Q3 is cut off. At this time, the non-inverting input terminal of the voltage comparator IC3 mainly receives the voltage output by the sawtooth wave generating circuit 200.

[0050] The relay control circuit disclosed by the utility model associates the output current of a power supply with the duty cycle of a relay. When the output current of the power supply is larger, the duty cycle of the relay is larger, thereby reducing the power loss of the relay.

[0051] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A relay control circuit, characterized in that: include: A relay switch circuit, one end of which is connected to the relay and is used to control the on and off of the relay; An output control circuit, wherein an output end of the output control circuit is connected to the other end of the relay switch circuit and is used to control the on and off of the relay switch circuit, and an output end of the output control circuit is connected to a sawtooth wave generating circuit; A differential amplifier circuit, wherein an input end of the differential amplifier circuit is connected to a power supply circuit, and an output end of the differential amplifier circuit is connected to another input end of the output control circuit.

2. The relay control circuit according to claim 1, characterized in that: The relay switch circuit includes a first switch tube and a switch element, the controlled end of the first switch tube is connected to one end of the switch element, the first pole of the first switch tube is connected to the relay, the second pole of the first switch tube is connected to the negative pole of the power supply, and the other end of the switch element is connected to the output end of the output control circuit.

3. The relay control circuit according to claim 2, characterized in that: The relay switch circuit further includes a first diode connected in parallel with the relay.

4. The relay control circuit according to claim 3, characterized in that: The relay switch circuit also includes a current limiting circuit and a voltage dividing circuit; One end of the current limiting circuit is connected to the power supply, and the other end of the current limiting circuit is connected to the relay; One end of the voltage divider circuit is connected to the power supply, and the other end of the voltage divider circuit is connected to the controlled end of the first switch tube.

5. The relay control circuit according to claim 4, characterized in that: The current limiting circuit includes a first resistor, one end of the first resistor is connected to the cathode of the first diode and the relay respectively, and the other end of the first resistor is connected to the power supply.

6. The relay control circuit according to claim 4, characterized in that: The voltage divider circuit further includes a second resistor, a third resistor and a fourth resistor; One end of the second resistor is connected to the power supply, the other end of the second resistor is respectively connected to one end of the third resistor and the switching element, the other end of the third resistor is respectively connected to one end of the fourth resistor and the controlled end of the first switching tube, and the other end of the fourth resistor is connected to the negative electrode of the power supply.

7. The relay control circuit according to claim 1, characterized in that: The output control circuit includes a voltage comparator, an inverting input terminal of the voltage comparator is connected to the output terminal of the differential amplifier circuit, a non-inverting input terminal of the voltage comparator is connected to the sawtooth wave generating circuit, and an output terminal of the voltage comparator is connected to the relay switch circuit.

8. The relay control circuit according to claim 7, characterized in that: The differential amplifier circuit includes a differential amplifier and a fifth resistor, wherein two ends of the fifth resistor are respectively connected to two input pins of the differential amplifier for sampling the power supply circuit, and an output pin of the differential amplifier is connected to the inverting input terminal of the voltage comparator.

9. The relay control circuit according to claim 7, characterized in that: It also includes a time-delay conduction circuit, the input end of the time-delay conduction circuit is connected to the power supply, and the output end of the time-delay conduction circuit is connected to the non-inverting input end of the voltage comparator.

10. The relay control circuit according to claim 9, characterized in that: The delayed conduction circuit includes a second switch tube and a third switch tube; The controlled end of the second switch tube is connected to the power supply, the first electrode of the second switch tube is connected to the controlled end of the third switch tube, the first electrode of the third switch tube is connected to the non-inverting input end of the voltage comparator, and the second electrode of the second switch tube and the second electrode of the third switch tube are both grounded.

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