A switch power supply over / under voltage protector based on a magnetic latching relay

Abstract

The utility model discloses a kind of switch power supply over-voltage and under-voltage protector based on magnetic latching relay, it is related to electric power control field, solve the circuit reliability insufficient and cannot be applicable to wide voltage range scene by conventional relay.Between the input end of switch power supply circuit connects live wire and zero line, its output end is connected voltage control circuit in turn, voltage signal circuit input end is parallel between live wire and zero line, and its output end is accessed voltage control circuit;Relay action circuit is electrically connected with voltage control circuit, for executing on-off action when the voltage signal output by voltage control circuit exceeds or is lower than set threshold value.Switch power supply circuit as front-end processing unit, it can adapt to the conversion demand of wide range ac input voltage, magnetic latching relay is more advantageous in power consumption, action stability, can accurately and timely execute protection action according to the instruction of voltage control circuit under the condition that input voltage fluctuation is larger.

Description

Technical Field

[0001] This utility model relates to the field of power control, and in particular to an over / under voltage protector for a switching power supply based on a magnetic latching relay. Background Technology

[0002] With the rapid development of electronic technology, switching power supplies, as core power supply components for electronic devices, are widely used in many fields such as communications, industrial control, and home appliances. The stable operation of a switching power supply directly affects the reliability and lifespan of downstream equipment, and abnormal fluctuations in input voltage, such as overvoltage or undervoltage, are one of the main causes of damage to switching power supplies and downstream equipment. Therefore, configuring reliable overvoltage and undervoltage protection circuits for switching power supplies is crucial.

[0003] In existing technologies, over / under voltage protection circuits typically use ordinary relays as actuating elements. However, these relays suffer from high power consumption, short contact life, and slow response speed. Especially in long-term continuous operation scenarios, the need for continuous power supply to maintain the engaged state leads to continuous energy consumption by the relay coil, resulting in reduced circuit efficiency. Furthermore, frequent operation can cause contact wear, affecting the stability of the protection circuit. Additionally, some protection circuits use low-precision resistor divider networks or simple comparators for voltage detection modules. In applications with a wide voltage range, this makes it difficult to accurately identify over / under voltage thresholds, easily leading to false protection or delayed protection. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing a switching power supply over / under voltage protector based on a magnetic latching relay, which solves the problems of insufficient circuit reliability and inapplicability to wide voltage range scenarios caused by conventional relays.

[0005] The technical solution of this utility model includes a switching power supply circuit, a voltage regulator circuit, a voltage control circuit, a relay operating circuit, and a voltage signal circuit. The input terminal of the switching power supply circuit is connected to the live wire and the neutral wire, and its output terminal is sequentially connected to the voltage regulator circuit and the voltage control circuit for outputting voltage. The input terminal of the voltage signal circuit is connected in parallel between the live wire and the neutral wire, and its output terminal is connected to the voltage control circuit for acquiring the input voltage signal and transmitting it to the voltage control circuit. The relay operating circuit includes a magnetic latching relay and is electrically connected to the voltage control circuit for performing on / off actions when the voltage signal output by the voltage control circuit exceeds or falls below a set threshold.

[0006] The above technical solution uses a switching power supply circuit as the front-end processing unit, which can adapt to the conversion requirements of a wide range of AC input voltages. The voltage regulator circuit can provide a stable operating voltage for the subsequent voltage control circuit, ensuring that the control part can still operate reliably when the input voltage fluctuates greatly, thus improving the detection accuracy over a wide voltage range. The voltage signal circuit converts the wide range of input voltages into signals that the voltage control circuit can recognize, providing an accurate basis for over- and under-voltage threshold judgment and avoiding sampling distortion or misjudgment due to an excessively wide voltage range. The magnetic latching relay action circuit serves as the execution unit. Compared with ordinary relays, magnetic latching relays have advantages in terms of power consumption and action stability. They can accurately and promptly execute protection actions according to the instructions of the voltage control circuit when the input voltage fluctuates greatly. In conjunction with the voltage control circuit, reliable on-off control over a wide voltage range can be achieved.

[0007] In one possible design, the switching power supply circuit includes a varistor Y1, a current-limiting resistor R1, diodes D1, D2, D3, and D4, energy storage capacitors EC1, EC2, EC3, and EC4, an inductor L1, and a chip U1. The live wire and neutral wire pass through the varistor Y1 and the current-limiting resistor R1, and are rectified into a half-wave signal by diodes D1 and D2. This signal is then input to pin 4 of the power chip U1 via energy storage capacitors EC1 and EC2. Diode D3 and capacitor EC3 form a feedback loop connected to pin 2 of the chip U1. Diode D4, inductor L1, capacitor EC4, and pins 1, 2, 3, and 4 of the chip U1 constitute the voltage output terminal.

[0008] With the above design, the varistor Y1 and current-limiting resistor R1 in the switching power supply circuit can suppress surges and overcurrents under wide voltage input conditions; the combination of half-wave rectifier circuit and multiple energy storage capacitors can adapt to the rectification and filtering requirements of wide voltage input; the feedback loops D3, EC3 and inductor L1 improve the stability of the output voltage, providing a power supply foundation for the reliable operation of subsequent circuits over a wide voltage range.

[0009] In one possible design, the voltage regulator circuit includes a voltage regulator chip U2, an energy storage capacitor EC5, a resistor R6, and an LED1. The output voltage of the switching power supply circuit is regulated by the voltage regulator chip U2 and then output to the energy storage capacitor EC5. The resistor R6 and the LED1 are connected in series to form a power status indicator circuit.

[0010] With the above design, the voltage regulator chip U2 stabilizes the fluctuating voltage of the switching power supply output into a constant voltage, ensuring that the voltage control circuit can still obtain a stable operating power supply even when the input voltage fluctuates greatly; the energy storage capacitor EC5 further smooths the regulated output and reduces ripple interference; the LED1 status indicator can intuitively reflect the working status of the voltage regulator circuit, which is convenient for circuit debugging and fault diagnosis in a wide voltage scenario.

[0011] In one possible design, the voltage control circuit includes chip U3, resistor R7, resistor R8, and LED2. The voltage signal circuit is connected to pins 5 and 7 of chip U3 and inputs voltage signals through pins 5 and 7 of chip U3. Pins 2 and 3 of chip U3 serve as its output terminals to output magnetic latching relay control signals to the relay action circuit. The working status is indicated by resistor R8 and LED2.

[0012] With the above design, the voltage control circuit receives the sampling signal from the voltage signal circuit through pins 5 and 7 of chip U3, which can accurately identify the over- and under-voltage thresholds within a wide voltage range; the output terminals (pins 2 and 3) output control signals to the relay action circuit to achieve precise control of the magnetic latching relay; the LED2 status indicator can provide real-time feedback on the over- and under-voltage protection status, ensuring the observability of the protection logic during wide voltage fluctuations.

[0013] In one possible design, the relay operating circuit also includes resistors R9 and R10, and a driver chip U4. The magnetic latching relay control signal output by the voltage control circuit is input to pins 3 and 6 of the driver chip U4 via resistors R9 and R10. Pins 1 and 4 of the driver chip U4 output magnetic latching relay coil drive signals to control the magnetic latching relay's engagement and disengagement.

[0014] With the above design, resistors R9 and R10 provide current limiting protection for the control signal, ensuring stable signal transmission under wide voltage conditions; the driver chip U4 enhances the driving capability of the control signal, ensuring that the magnetic latching relay can reliably engage or disengage even when the coil voltage fluctuates due to a wide voltage input, thus improving the stability of the actuator's operation over a wide voltage range.

[0015] In one possible design, the voltage signal circuit includes resistors R2 and R3, voltage divider resistors R4 and R5, diodes D5 and D6, capacitors C1 and EC6. The voltage between the live wire and the neutral wire is half-wave rectified by resistors R2, R3, and diode D5, and then stepped down by voltage divider resistor R4 before being input to pin 5 of chip U3. Diode D6, resistors R5, capacitors C1 and EC6 form a voltage divider filter network, and the output signal is connected to pin 7 of chip U3.

[0016] Using the above design, the voltage signal circuit converts the wide-range input voltage of 110VAC-300VAC into a sampling signal for the adapter chip U3 through voltage division by resistors R2 and R3 and half-wave rectification by D5; the voltage divider resistor R4 further reduces the voltage to avoid damage to the control chip by high voltage; the filter network composed of diode D6, capacitor C1, and EC6 reduces ripple in the sampling signal and ensures the accuracy of the sampling signal over a wide voltage range. Attached Figure Description

[0017] Figure 1 This is a circuit block diagram of the present invention; Figure 2 This is the circuit schematic diagram of this utility model; The circuit includes: 1. Switching power supply circuit; 2. Voltage regulator circuit; 3. Voltage control circuit; 4. Relay operation circuit; 5. Voltage signal circuit. Detailed Implementation

[0018] like Figure 1 , Figure 2 The diagram illustrates an over / under voltage protector for a switching power supply based on a magnetic latching relay. It includes a switching power supply circuit 1, a voltage regulator circuit 2, a voltage control circuit 3, a relay operation circuit 4, and a voltage signal circuit 5. The input of the switching power supply circuit 1 is directly connected to the live wire and the neutral wire, and its output is sequentially connected to the voltage regulator circuit 2 and the voltage control circuit 3 to provide operating voltage for subsequent circuits. The input of the voltage signal circuit 5 is connected in parallel between the live wire and the neutral wire, acquiring the input voltage signal in real time and transmitting it to the voltage control circuit 3. The relay operation circuit 4 includes a magnetic latching relay (Relay1) and is electrically connected to the voltage control circuit 3, executing power on / off actions according to the instructions of the voltage control circuit 3. When the input voltage of the live wire and neutral wire is within the normal range (e.g., 180VAC-240VAC), the voltage signal circuit 5 transmits the sampling signal to the voltage control circuit 3. The voltage control circuit 3 outputs a sustaining signal, and the magnetic latching relay in the relay action circuit 4 remains engaged, ensuring normal power supply. When the input voltage exceeds the overvoltage threshold (e.g., ≥240VAC) or falls below the undervoltage threshold (e.g., ≤180VAC), the voltage control circuit 3 outputs a disconnect signal, the magnetic latching relay releases, and the power supply is cut off, thus achieving protection. In this way, the various module circuits work together to achieve overvoltage and undervoltage protection functions within a wide voltage range of 110VAC-300VAC.

[0019] The switching power supply circuit 1 includes a varistor Y1, a current-limiting resistor R1, diodes D1, D2, D3, and D4, energy storage capacitors EC1, EC2, EC3, and EC4, an inductor L1, and a chip U1 (such as a flyback power supply chip). A varistor Y1 (model optional 10K821) is connected in parallel between the live wire and the neutral wire to suppress input surge voltage. The live wire, after passing through the current-limiting resistor R1, is connected to diodes D1 and D2 to form a half-wave rectifier circuit. The rectified pulsating DC power is filtered by energy storage capacitors EC1 and EC2 and then input to pin 4 (voltage input) of the power supply chip U1. Diode D3 and capacitor EC3 are connected in series to form a feedback loop, which is connected to pin 2 (feedback) of U1 to stabilize the output voltage. Diode D4, inductor L1, capacitor EC4, and pins 2 and 5-8 of the chip U1 constitute the output terminal. Varistor Y1 and current-limiting resistor R1 protect the circuit from voltage surges; half-wave rectification and multi-stage capacitor filtering adapt to a wide input range of 110VAC-300VAC; feedback loop and inductor L1 ensure stable output voltage to meet the power supply requirements of subsequent circuits.

[0020] The voltage regulator circuit 2 includes a voltage regulator chip U2 (model CJ78L05), an energy storage capacitor EC5, a resistor R6, and an indicator light LED1 (green). The 5V voltage output from the switching power supply circuit 1 is connected to pin 1 (input terminal) of the voltage regulator chip U2. Pin 2 (ground) of the voltage regulator chip U2 shares ground with the neutral line, and pin 3 (output terminal) outputs a stable 5V voltage, which, after being filtered by the energy storage capacitor EC5, powers the voltage control circuit 3. The resistor R6 is connected in series with LED1 and then in parallel between pin 3 of the voltage regulator chip U2 and ground. The voltage regulator chip U2 stabilizes the fluctuating voltage output of the switching power supply to a constant 5V, ensuring that the voltage control circuit 3 operates reliably within a wide input voltage range. The energy storage capacitor EC5 further filters out ripple and reduces interference. The LED1 lights up when the circuit is working normally, providing a clear indication of the power supply status.

[0021] The voltage control circuit 3 includes chip U3, resistors R7 and R8, and indicator LED2 (red). The two sampling signals from the voltage signal circuit 5 are connected to pin 5 (overvoltage detection input) and pin 7 (undervoltage detection input) of chip U3, respectively. Pin 4 of chip U3 is connected to the 5V output of voltage regulator circuit 2, and pin 8 is grounded. Pins 2 (overvoltage control output) and 3 (undervoltage control output) of U3 serve as control signal outputs, connected to relay action circuit 4. Resistor R8 is connected in series with LED2 and then in parallel between the output of U3 and ground. Chip U3 receives the sampling signals through pins 5 and 7, compares them with the internal reference voltage, and outputs high-level control signals through pins 2 and 3 when there is overvoltage or undervoltage. LED2 illuminates during protection operation to indicate overvoltage or undervoltage status. Resistor R7 is used to adjust the voltage division ratio of the sampling signal to ensure detection accuracy.

[0022] The relay operation circuit 4 includes a magnetic latching relay, resistors R9 and R10, and a driver chip U4. The two control signals output from the voltage control circuit 3 are current-limited by resistors R9 and R10, respectively, and then connected to pins 3 and 6 (signal input terminals) of the driver chip U4. Pins 1 and 4 of U4 output pulse signals to drive the magnetic latching relay coil, controlling its engagement (conduction) or disengagement (opening). Resistors R9 and R10 protect the driver chip from overcurrent damage; the driver chip U4 amplifies the control signals, providing sufficient drive current to the magnetic latching relay coil; the magnetic latching relay can maintain its engaged or disengaged state without continuous power supply, reducing power consumption and ensuring reliable operation over a wide voltage range, thus extending its service life.

[0023] Voltage signal circuit 5 includes resistors R2 and R3, voltage divider resistors R4 and R5, diodes D5 and D6, capacitor C1, and energy storage capacitor EC6. The live wire is connected in series with resistors R2 and R3, then to the anode of diode D5. The cathode of D5 is connected to one end of voltage divider resistor R4, and the other end of R4 is connected to pin 5 (overvoltage detection terminal) of chip U3. The live wire is connected via the anode of diode D6, and the cathode of D6 is connected to one end of resistor R5. The other end of R5 is connected in parallel with capacitor C1 and energy storage capacitor EC6, then connected to pin 7 (undervoltage detection terminal) of chip U3. The other ends of capacitor C1 and energy storage capacitor EC6 are grounded. Resistors R2 and R3 divide the high-voltage input, and together with D5 and diode D6, half-wave rectification converts the wide-range voltage of 110VAC-300VAC into a low-voltage sampling signal. The voltage divider resistor R4 further reduces the voltage to ensure that the signal input to chip U3 is within a safe range. Capacitor C1 and energy storage capacitor EC6 filter and eliminate high-frequency interference, making the sampling signal more stable and improving the over- and under-voltage detection accuracy.

Claims

1. An over / under voltage protector for a switching power supply based on a magnetic latching relay, characterized in that: It includes a switching power supply circuit (1), a voltage regulator circuit (2), a voltage control circuit (3), a relay action circuit (4), and a voltage signal circuit (5); The input terminal of the switching power supply circuit (1) is connected to the live wire and the neutral wire, and its output terminal is connected to the voltage regulator circuit (2) and the voltage control circuit (3) in sequence, so as to output the voltage of the voltage regulator circuit (2) and the voltage control circuit (3); The input terminal of the voltage signal circuit (5) is connected in parallel between the live wire and the neutral wire, and its output terminal is connected to the voltage control circuit (3) to collect the input voltage signal and transmit it to the voltage control circuit (3). The relay action circuit (4) includes a magnetic latching relay and is electrically connected to the voltage control circuit (3) for performing on / off actions when the voltage signal output by the voltage control circuit (3) exceeds or falls below a set threshold.

2. The over / under voltage protector for a switching power supply based on a magnetic latching relay according to claim 1, characterized in that: The switching power supply circuit (1) includes a varistor Y1, a current-limiting resistor R1, diodes D1, D2, D3, and D4, energy storage capacitors EC1, EC2, EC3, and EC4, an inductor L1, and a chip U1. The live wire and neutral wire pass through the varistor Y1 and the current-limiting resistor R1, and are rectified into a half-wave signal by diodes D1 and D2. The signal is then input to pin 4 of the power chip U1 via energy storage capacitors EC1 and EC2. Diode D3 and capacitor EC3 form a feedback loop connected to pin 2 of the chip U1. Diode D4, inductor L1, capacitor EC4, and pins 1, 2, 3, and 4 of the chip U1 form the voltage output terminal.

3. The switching power supply over / under voltage protector based on a magnetic latching relay according to claim 1 or 2, characterized in that: The voltage regulator circuit (2) includes a voltage regulator chip U2, an energy storage capacitor EC5, a resistor R6, and a lamp LED1. The output voltage of the switching power supply circuit (1) is regulated by the voltage regulator chip U2 and then output to the energy storage capacitor EC5. The resistor R6 and the lamp LED1 are connected in series to form a power status indicator circuit.

4. The switching power supply over / under voltage protector based on a magnetic latching relay according to claim 1 or 2, characterized in that: The voltage control circuit (3) includes chip U3, resistor R7, resistor R8, and lamp LED2. The voltage signal circuit (5) is connected to pins 5 and 7 of chip U3 and inputs voltage signals through pins 5 and 7 of chip U3. Pins 2 and 3 of chip U3 are used as its output terminals to output magnetic latching relay control signals to relay action circuit (4). The working status is indicated by resistor R8 and lamp LED2.

5. The switching power supply over / under voltage protector based on a magnetic latching relay according to claim 1 or 2, characterized in that: The relay action circuit (4) also includes resistors R9 and R10 and a driver chip U4. The magnetic latching relay control signal output by the voltage control circuit (3) is input to pins 3 and 6 of the driver chip U4 through resistors R9 and R10. Pins 1 and 4 of the driver chip U4 output magnetic latching relay coil drive signals to control the magnetic latching relay to engage and disengage.

6. The switching power supply over / under voltage protector based on a magnetic latching relay according to claim 1 or 2, characterized in that: The voltage signal circuit (5) includes resistors R2 and R3, voltage divider resistors R4 and R5, diodes D5 and D6, capacitors C1 and EC6. The voltage between the live wire and the neutral wire is rectified by resistors R2, R3 and D5, and then stepped down by voltage divider resistor R4 before being input to pin 5 of chip U3. Diodes D6, R5, C1 and EC6 form a voltage divider filter network, and the output signal is connected to pin 7 of chip U3.

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