A relay state detection circuit

Abstract

The utility model belongs to relay technology field discloses a kind of relay state detection circuit, the pin 3 of current transformer CT1 is connected the pin 4 of relay K1, the pin 3 of relay K1 is connected input end L, the pin 4 of current transformer CT1 is connected output end BSENS+, the pin 1 of current transformer CT1 is connected the positive end of diode D11 and the negative end of diode D15, the pin 2 of current transformer CT1 is connected the positive end of diode D2 and the negative end of diode D5, the negative end of diode D11 is connected the negative end of diode D2, the one end of resistance R5, the one end of resistance R11, the one end of resistance R12, the one end of capacitor C4 and port AVCC, the positive end of diode D15 is connected the positive end of D5, the other end of R5, the other end of R11, the other end of R12, the other end of C4 and port GND.The utility model has the beneficial effect that when relay drive is normally issued, the relay attraction state can be detected.

Description

Technical Field

[0001] This utility model relates to the field of relay technology, and in particular to a relay status detection circuit. Background Technology

[0002] With the explosive growth of the new energy market, high-power charging modules and various switching power supplies have been widely used, and relays, as an indispensable component in switching power supply design, have also seen extensive application. The main applications of relays in switching power supplies are logic switching and, after normal power-on, short-circuit surge current protection (using cement resistors) to commutate the input main current. The short-circuit commutation function essentially covers all medium- and high-power switching power supplies. However, if the relay fails to engage properly despite a normal drive signal, the power output will increase, and the large input current will flow entirely through the cement resistor, causing it to burn out and catch fire, resulting in an accident. Therefore, it is necessary to monitor the relay's engagement status.

[0003] Therefore, it is necessary to provide a relay status detection circuit that can detect the relay's energized state when the relay drive is normally activated. Utility Model Content

[0004] This utility model discloses a relay status detection circuit, which relates to switching power supply technology and can effectively solve the technical problems involved in the background art.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A relay status detection circuit for monitoring the status of relay K1 includes a current transformer CT1. Pin 3 of the current transformer CT1 is connected to pin 4 of the relay K1. Pin 3 of the relay K1 is connected to the input terminal L. Pin 4 of the current transformer CT1 is connected to the output terminal BSENS+. Pin 1 of the current transformer CT1 is connected to the positive terminal of diode D11 and the negative terminal of diode D15. Pin 2 of the current transformer CT1 is connected to the positive terminal of diode D2 and the negative terminal of diode D5. The negative terminal of diode D11 is connected to the negative terminal of diode D2, one end of resistor R5, one end of resistor R11, one end of resistor R12, one end of capacitor C4, and port AVCC. The positive terminal of diode D15 is connected to the positive terminal of diode D5, the other end of resistor R5, the other end of resistor R11, the other end of resistor R12, the other end of capacitor C4, and port GND.

[0007] The AVCC port is connected to pin 3 of clamping diode D17 and pin 6 of comparator U58. Pin 2 of clamping diode D17 is connected to port VCC2. Pin 1 of clamping diode D17 is connected to one end of resistor R18 and port GND. Pin 5 of comparator U58 is connected to one end of resistor R21, one end of resistor R14, and the other end of resistor R18. The other end of resistor R21 is connected to one end of resistor R17 and port VCC1. The other end of resistor R17 is connected to pin 7 of comparator U58, the other end of resistor R14, and port VCOME.

[0008] The port VCOME is connected to one end of resistor R25, the other end of resistor R25 is connected to one end of capacitor C5, pin 3 of clamping diode D18 and port RLY-TEST, the other end of capacitor C5 is connected to pin 1 of clamping diode D18, and pin 2 of clamping diode D18 is connected to port VCC3.

[0009] A relay status detection circuit includes a relay current sampling and rectifier circuit, a voltage comparator circuit, and a signal filtering circuit. The relay current sampling and rectifier circuit includes current sampling and rectification circuits. The voltage comparator circuit compares the rectified voltage. The signal filtering circuit filters the result of the previous comparison and sends it to the MUC for judgment processing. This provides a circuit scheme that can detect the relay's engaged state when the relay drive is normally activated.

[0010] As a preferred improvement of this utility model: the input terminal L is connected to the output terminal BSENS+ through resistors VR6 and VR7.

[0011] As a preferred improvement of this utility model, the current transformer CT1 is model DHC22AD3.

[0012] As a preferred improvement of this utility model, the comparator is model RM055XM.

[0013] As a preferred improvement of this utility model, the port RLY-TEST is connected to the controller MCU.

[0014] As a preferred improvement of this utility model: the controller MCU is connected to port RLYB, port RLYB is connected to one end of resistor R408, the other end of resistor R408 is connected to one end of capacitor C205, one end of resistor R407 and the base of transistor Q108, the other end of capacitor C205 is connected to the other end of resistor R408, the emitter of transistor Q108 and port GNDAUX, the collector of transistor Q108 is connected to the positive terminal of diode D115 and pin 1 of relay K1, the negative terminal of diode D115 is connected to pin 2 of relay K1, one end of resistor R401 and one end of resistor R404, and the other end of resistor R401 is connected to the other end of resistor R404 and port 12VP.

[0015] As a preferred improvement of this utility model, the MCU model is STM32F334R8T6.

[0016] As a preferred improvement of this utility model: the port GNDAUX and the port GND are connected to different grounding terminals, and the port 12VP is connected to a 12V power supply.

[0017] As a preferred improvement of this utility model: the ports VCC1, VCC2 and VCC3 are all connected to a 3V power supply.

[0018] The beneficial effects of this utility model are as follows:

[0019] A relay status detection circuit is disclosed, comprising a relay current sampling and rectification circuit, a voltage comparator circuit, and a signal filtering circuit. The relay current sampling and rectification circuit samples and rectifies the current when the relay is turned on. The hysteresis voltage comparator circuit determines whether the relay is normally turned on and outputs high and low voltage signals. The filtering circuit filters the output signal from the previous stage and sends it to the MCU for judgment. The above circuit has a simple structure, is easy to manufacture, has low cost, and is easy to promote. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0021] Figure 1 This is a schematic diagram of a relay status detection circuit according to the present invention. Figure 1 ;

[0022] Figure 2 for Figure 1Enlarged illustration Figure 1 ;

[0023] Figure 3 for Figure 1 Enlarged illustration Figure 2 ;

[0024] Figure 4 This is a schematic diagram of a relay status detection circuit according to the present invention. Figure 2 ;

[0025] Figure 5 This is a schematic diagram of a relay status detection circuit according to the present invention. Figure 3 . Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0031] Please see Figures 1-2 As shown, this utility model provides a relay status detection circuit for monitoring the status of relay K1. It includes a current transformer CT1. Pin 3 of the current transformer CT1 is connected to pin 4 of the relay K1. Pin 3 of the relay K1 is connected to the input terminal L. Pin 4 of the current transformer CT1 is connected to the output terminal BSENS+. The input terminal L is connected to the output terminal BSENS+ through resistors VR6 and VR7. Pin 1 of the current transformer CT1 is connected to the positive terminal of diode D11 and the negative terminal of diode D15. Pin 2 of the current transformer CT1 is connected to the positive terminal of diode D2 and the negative terminal of diode D5. The negative terminal of diode D11 is connected to the negative terminal of diode D2, one end of resistor R5, one end of resistor R11, one end of resistor R12, one end of capacitor C4, and port AVCC. The positive terminal of diode D15 is connected to the positive terminal of diode D5, the other end of resistor R5, the other end of resistor R11, the other end of resistor R12, the other end of capacitor C4, and port GND. The relay current sampling rectifier circuit consists of a CT1 current transformer and rectifier diodes D2, D11, D5, and D15. The primary winding of the CT1 current transformer is connected in series to the relay power circuit side. The secondary winding is connected to four rectifier diodes to rectify the positive and negative currents of the primary winding. R5, R11, and R12 are connected in parallel across the secondary winding of the CT1 to convert the current signal into a voltage signal. Capacitor C4 is a filter capacitor. The current transformer CT1 is a DHC22AD3 model.

[0032] Please see Figure 4As shown, port AVCC connects pin 3 of clamping diode D17 and pin 6 of comparator U58. Pin 2 of clamping diode D17 connects to port VCC2. Pin 1 of clamping diode D17 connects one end of resistor R18 and port GND. Pin 5 of comparator U58 connects one end of resistor R21, one end of resistor R14, and the other end of resistor R18. The other end of resistor R21 connects one end of resistor R17 and port VCC1. The other end of resistor R17 connects pin 7 of comparator U58, the other end of resistor R14, and port VCOME. The voltage comparator circuit consists of one comparator U58-B and external resistors. R21 and R18 form a voltage divider circuit to provide the comparison voltage for the comparator. R17 is a pull-up resistor, and R14 is a hysteresis resistor. When the comparator output is low, it is connected in parallel with R18 to form a hysteresis comparison voltage. D17 is a protection clamping diode, providing overvoltage protection for the comparator input pin. The circuit compares the preceding signal and outputs a relevant signal to the filter circuit based on the comparison value. The comparator model is RM055XM.

[0033] Please see Figure 5 As shown, port VCOME is connected to one end of resistor R25. The other end of resistor R25 is connected to one end of capacitor C5, pin 3 of clamping diode D18, and port RLY-TEST. Port RLY-TEST is connected to the controller MCU. The other end of capacitor C5 is connected to pin 1 of clamping diode D18, and pin 2 of clamping diode D18 is connected to port VCC3. The signal filtering circuit consists of resistors, capacitors, and clamping diodes. R25 and C5 form an RC filter to filter the signal output from the comparator. The filtered signal, after passing through clamping diode D18, is sent to the MCU for logic judgment via the RLY-TEST signal. In this embodiment, ports VCC1, VCC2, and VCC3 are all connected to a 3V power supply.

[0034] Please see Figure 3As shown, the controller MCU is connected to port RLYB. Port RLYB is connected to one end of resistor R408. The other end of resistor R408 is connected to one end of capacitor C205, one end of resistor R407, and the base of transistor Q108. The other end of capacitor C205 is connected to the other end of resistor R408, the emitter of transistor Q108, and port GNDAUX. The collector of transistor Q108 is connected to the positive terminal of diode D115 and pin 1 of relay K1. The negative terminal of diode D115 is connected to pin 2 of relay K1, one end of resistor R401, and one end of resistor R404. The other end of resistor R401 is connected to the other end of resistor R404 and port 12VP. The MCU model is STM32F334R8T6. Port GNDAUX and port GND are connected to different ground terminals, and port 12VP is connected to a 12V power supply.

[0035] When the relay is in the open state, no current flows through the relay current sampling rectifier circuit, and the output rectified voltage is 0V. At this time, the positive input voltage of the comparator is the 3V voltage divided by R17, R14, and R18. Since the positive input voltage of the comparator is greater than the negative input voltage, the comparator outputs a high level through the pull-up resistor R17. When the relay is energized, the output value of the relay current sampling rectifier circuit will be higher than the comparison voltage at the positive terminal of the hysteresis comparator. At this time, the comparator outputs a low level, and the MCU can determine the energized state of the relay based on the high and low levels, thus safely and reliably controlling power conversion. It should be further noted that any other components used to achieve the above effects should fall within the inventive concept of this utility model and should be protected within its scope.

[0036] Example 1

[0037] A relay state detection circuit includes a relay current sampling rectifier circuit, a voltage comparator circuit, and a signal filtering circuit. The relay current sampling rectifier circuit samples the current on the power side of the relay when it is in the energized state. The voltage comparator circuit compares the rectified voltage. The filtering circuit filters the output voltage of the relay.

[0038] Specifically, the current transformer CT1 of the relay current sampling rectifier circuit is connected in series into the relay power circuit to sample the current. D2, D11, D5, and D15 form a full-bridge rectifier circuit, which rectifies the positive and negative current waveforms into a positive current signal. The current signal is converted into a voltage signal by R5, R11, and R12 and sent to the subsequent circuit.

[0039] Specifically, the voltage comparator circuit comprises a fast comparator and external resistors, capacitors, and diodes. Capacitors R17, R18, R14, and R21 provide a comparison voltage for the positive input of the comparator, resistor R10 is a pull-up resistor, and diode D17 is a clamping protection diode. When the relay is not engaged, the output value of the preceding current sampling circuit is 0, and the comparator outputs a high level. When the relay is engaged, the value output by the current sampling circuit exceeds the positive input threshold of the comparator, and the comparator outputs a low level. Resistor R14, connected in parallel with R18 when the comparator output is low, provides another hysteresis voltage. This circuit implements a dual-threshold hysteresis function, ensuring the reliability of the subsequent relay judgment.

[0040] Specifically, the filter circuit consists of a resistor R25, a capacitor C5, and a clamping diode D18. The output of the pre-amplifier is filtered and then sent to the microcontroller (MUC) for judgment. The MUC determines the state of the relay based on the detected high and low level signals and further controls the power.

[0041] Working principle: A relay status detection circuit includes a relay current sampling and rectifier circuit, a voltage comparator circuit, and a filter circuit. The relay current sampling and rectifier circuit samples and rectifies the relay current. The comparator compares the sampled data with the comparison voltage and outputs a high or low level. The MUC determines the relay's energized state based on the filtered high or low level. This solution is simple in structure, easy to manufacture, low in cost, and easy to promote.

[0042] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A relay state detection circuit for monitoring the state of relay K1, characterized in that: The system includes a current transformer CT1. Pin 3 of the current transformer CT1 is connected to pin 4 of the relay K1. Pin 3 of the relay K1 is connected to the input terminal L. Pin 4 of the current transformer CT1 is connected to the output terminal BSENS+. Pin 1 of the current transformer CT1 is connected to the positive terminal of diode D11 and the negative terminal of diode D15. Pin 2 of the current transformer CT1 is connected to the positive terminal of diode D2 and the negative terminal of diode D5. The negative terminal of diode D11 is connected to the negative terminal of diode D2, one end of resistor R5, one end of resistor R11, one end of resistor R12, one end of capacitor C4, and port AVCC. The positive terminal of diode D15 is connected to the positive terminal of diode D5, the other end of resistor R5, the other end of resistor R11, the other end of resistor R12, the other end of capacitor C4, and port GND. The AVCC port is connected to pin 3 of clamping diode D17 and pin 6 of comparator U58. Pin 2 of clamping diode D17 is connected to port VCC2. Pin 1 of clamping diode D17 is connected to one end of resistor R18 and port GND. Pin 5 of comparator U58 is connected to one end of resistor R21, one end of resistor R14, and the other end of resistor R18. The other end of resistor R21 is connected to one end of resistor R17 and port VCC1. The other end of resistor R17 is connected to pin 7 of comparator U58, the other end of resistor R14, and port VCOME. The port VCOME is connected to one end of resistor R25, the other end of resistor R25 is connected to one end of capacitor C5, pin 3 of clamping diode D18 and port RLY-TEST, the other end of capacitor C5 is connected to pin 1 of clamping diode D18, and pin 2 of clamping diode D18 is connected to port VCC3.

2. The relay state detection circuit according to claim 1, characterized in that: The input terminal L is connected to the output terminal BSENS+ through resistors VR6 and VR7.

3. The relay state detection circuit according to claim 1, characterized in that: The current transformer CT1 is model DHC22AD3.

4. The relay state detection circuit according to claim 1, characterized in that: The comparator model is RM055XM.

5. A relay state detection circuit according to claim 1, characterized in that: The RLY-TEST port is connected to the controller MCU.

6. A relay state detection circuit according to claim 5, characterized in that: The controller MCU is connected to port RLYB. Port RLYB is connected to one end of resistor R408. The other end of resistor R408 is connected to one end of capacitor C205, one end of resistor R407, and the base of transistor Q108. The other end of capacitor C205 is connected to the other end of resistor R408, the emitter of transistor Q108, and port GNDAUX. The collector of transistor Q108 is connected to the positive terminal of diode D115 and pin 1 of relay K1. The negative terminal of diode D115 is connected to pin 2 of relay K1, one end of resistor R401, and one end of resistor R404. The other end of resistor R401 is connected to the other end of resistor R404 and port 12VP.

7. A relay state detection circuit according to claim 6, characterized in that: The MCU model is STM32F334R8T6.

8. A relay state detection circuit according to claim 6, characterized in that: The ports GNDAUX and GND are connected to different grounding terminals, and the port 12VP is connected to a 12V power supply.

9. A relay state detection circuit according to claim 1, characterized in that: Ports VCC1, VCC2, and VCC3 are all connected to a 3V power supply.

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