Power supply circuit of leakage protector
By introducing a transistor feedback power supply circuit into the power supply circuit of the leakage current device, the problems of high static power consumption and high cost of switching power supply of the leakage current device are solved, and a low power consumption and low cost power supply solution is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HAGER ELECTRICHUIZHOUCO LTD
- Filing Date
- 2025-06-09
- Publication Date
- 2026-05-15
AI Technical Summary
Existing residual current devices (RCDs) suffer from high static power consumption during power-on and have high switching power supply costs.
A power supply circuit employing a leakage current protection device includes an AC bridge input terminal, a resistor-capacitor step-down circuit, and a voltage regulator and energy storage circuit, with a transistor feedback power supply circuit connected in parallel. A comparator circuit composed of transistors Q1, Q2, and Q3 controls the switching on and off of transistor Q1 to achieve low-power power supply.
Low-power power supply for leakage current protection is achieved at a low cost, avoiding electromagnetic interference and reducing static power consumption.
Smart Images
Figure CN224249343U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of electronic technology in the electrical industry, and in particular to a power supply circuit for a leakage current protection device. Background Technology
[0002] In residual current circuit (RCC) products, a functional circuit is required to power the product's control chip and coil drive circuit. Currently, there are two common solutions: one is to use a resistor-capacitor (RC) step-down circuit, and the other is to use a switching power supply. Since RCCs are required to trip promptly when a leakage occurs simultaneously with power-on, existing products typically employ the following two methods.
[0003] In products using RC step-down technology, the impedance of the RC step-down circuit is relatively small in order to charge the capacitor of the drive circuit in a timely manner, and a large current needs to flow through it. This current is still large even when there is no leakage current in the product, resulting in a large static power consumption in products using this technology.
[0004] In products powered by switching power supplies, on the one hand, because they operate in a high-frequency switching state, they are prone to electromagnetic interference; on the other hand, switching power supplies that operate in a wide input voltage range of AC50V-AC230V are also more expensive. Utility Model Content
[0005] To address the aforementioned technical problems, this utility model solves the issues of high static power consumption and high cost of switching power supplies in leakage current protection products, and provides a low-cost power supply circuit for a leakage current protection device.
[0006] To solve the above-mentioned technical problems, the technical solution provided by this utility model is: a power supply circuit for a leakage current protector, which sequentially includes an AC bridge input terminal, a resistor-capacitor step-down circuit, and a voltage regulator and energy storage circuit. A transistor feedback power supply circuit is connected in parallel on the resistor-capacitor step-down circuit. The transistor feedback power supply circuit includes a comparator circuit composed of transistors Q1, Q2, and Q3. Transistor Q3 controls the on and off of transistor Q1 through transistor Q2, driving transistor Q1 to supply power to the voltage regulator and energy storage circuit.
[0007] Further details: In the power supply circuit of the aforementioned leakage current protection device, the emitter of transistor Q1 is connected to the AC bridge input terminal, the base of transistor Q1 is connected to the collector of transistor Q2, the emitter of transistor Q2 is grounded, the base of transistor Q2 is connected to the collector of transistor Q3 and then grounded, the emitter of transistor Q3 is connected to the AC bridge input terminal, the base of transistor Q3 is connected to the collector of transistor Q1 after series with resistor R4, and the base of transistor Q3 is grounded. The emitter of transistor Q2 is grounded after series with resistor R9, the collector of transistor Q3 is grounded after series with resistor R8, and the base of transistor Q3 is grounded after series with resistor R5. Resistor R1 is connected in series between the emitter of transistor Q1 and the AC bridge input terminal. Resistor R2 is connected in series between the emitter of transistor Q3 and the AC bridge input terminal. Resistor R3 is connected in series between the base of transistor Q1 and the collector of transistor Q2. A capacitor C2 is also connected in parallel at the input terminals of resistors R1 and R2, one end of capacitor C2 is connected to the AC bridge input terminal, and the other end is directly grounded. The comparator circuit also includes a resistor R6, one end of which is connected in parallel with the emitter of transistor Q3, and the other end is grounded.
[0008] Furthermore: In the power supply circuit of the aforementioned leakage current protector, the RC step-down circuit includes resistors R7, R10, and R11, and capacitor C3. Resistor R10 is connected in series with resistor R11, then in parallel with capacitor C3, and finally in series with resistor R7 and the AC bridge input terminal. The voltage regulator and energy storage circuit includes capacitor C1 and diode D2 connected in parallel.
[0009] Compared with existing technologies, the power supply circuit of the aforementioned leakage current protector sequentially includes an AC bridge input terminal, a resistor-capacitor (RC) step-down circuit, and a voltage regulator energy storage circuit. A transistor feedback power supply circuit is connected in parallel to the RC step-down circuit. The transistor feedback power supply circuit includes a comparator circuit composed of transistors Q1, Q2, and Q3. Transistor Q3 controls the switching on and off of transistor Q1 through transistor Q2, driving transistor Q1 to supply power to the voltage regulator energy storage circuit. This invention adds a comparator composed of transistors Q1, Q2, and Q3 for capacitor charging to the existing RC step-down circuit. The inputs of the comparator are a voltage divider input and a voltage divider feedback, respectively. Upon initial power-on, because the input of the voltage divider feedback is less than the voltage divider input, transistor Q3 conducts, which in turn drives transistor Q2 to provide bias to transistor Q1. Current flows through transistor Q1 to charge the voltage regulator energy storage circuit. When the charging voltage reaches a predetermined value, transistor Q1 turns off, and the required static operating current is supplied by the RC step-down circuit. When leakage occurs, the voltage of the voltage regulator energy storage circuit drops rapidly, and the input of the voltage divider feedback is again less than the voltage divider input, causing transistor Q3 to conduct, which in turn drives transistor Q1 to supply power to the voltage regulator energy storage circuit again. When the voltage recovers, transistor Q1 turns off again, entering a low-power state. This technology adds transistor feedback power supply to the RC step-down circuit, saving costs while maintaining low power consumption and eliminating electromagnetic interference. The rectified and divided input voltage is connected to the emitter of transistor Q3 (PNP), and the divided output voltage is connected to the base of the transistor. The inputs of these two terminals form a comparator to control the switching on and off of transistor Q1. This achieves power supply for the leakage current protector with low cost and low static power consumption, significantly saving costs. Attached Figure Description
[0010] Figure 1 This is a circuit diagram of the power supply circuit for the leakage current protection device of this utility model;
[0011] Figure 2 This is a circuit diagram of the power supply circuit for the leakage current protection device of this utility model; Detailed Implementation
[0012] To facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0013] like Figure 1 , 2A power supply circuit for a leakage current protection device includes, in sequence, an AC bridge input terminal, a resistor-capacitor (RC) step-down circuit, and a voltage regulator and energy storage circuit. A transistor feedback power supply circuit is connected in parallel to the RC step-down circuit. The transistor feedback power supply circuit includes a comparator circuit composed of transistors Q1, Q2, and Q3. Transistor Q3 controls the on / off state of transistor Q1 through transistor Q2, driving transistor Q1 to supply power to the voltage regulator and energy storage circuit. The emitter of transistor Q1 is connected to the AC bridge input terminal, the base of transistor Q1 is connected to the collector of transistor Q2, the emitter of transistor Q2 is grounded, the base of transistor Q2 is connected to the collector of transistor Q3 and then grounded, the emitter of transistor Q3 is connected to the AC bridge input terminal, the base of transistor Q3 is connected to the collector of transistor Q1 after series with resistor R4, and the base of transistor Q3 is grounded. The emitter of transistor Q2 is connected to ground after series with resistor R9, the collector of transistor Q3 is connected to ground after series with resistor R8, and the base of transistor Q3 is connected to ground after series with resistor R5. A resistor R1 is connected in series between the emitter of transistor Q1 and the input terminal of the AC bridge. A resistor R2 is connected in series between the emitter of transistor Q3 and the input terminal of the AC bridge. A resistor R3 is connected in series between the base of transistor Q1 and the collector of transistor Q2. A capacitor C2 is connected in parallel with the input terminals of resistors R1 and R2. One end of capacitor C2 is connected to the input terminal of the AC bridge, and the other end is directly grounded. The comparator circuit also includes a resistor R6, one end of which is connected in parallel with the emitter of transistor Q3, and the other end is grounded.
[0014] The described resistor-capacitor step-down circuit includes resistors R7, R10, R11, and C3. Resistor R10 is connected in series with resistor R11, then in parallel with capacitor C3, and finally in series with resistor R7 and the AC bridge input terminal.
[0015] The voltage-stabilized energy storage circuit includes a capacitor C1 and a diode D2 connected in parallel.
[0016] During operation, upon initial power-on, transistor Q3 conducts because the input of the voltage divider feedback is less than the voltage divider input. This drives transistor Q2 to provide bias to transistor Q1, and current flows through transistor Q1 to charge the voltage regulator and energy storage circuit. When the charging voltage reaches a predetermined value, transistor Q1 turns off, and the required static operating current is supplied by the RC step-down circuit. When leakage occurs, the voltage of the voltage regulator and energy storage circuit drops rapidly, and the input of the voltage divider feedback again becomes less than the voltage divider input. Transistor Q3 then conducts, driving transistor Q1 again to supply power to the voltage regulator and energy storage circuit. When the voltage recovers, transistor Q1 turns off again, entering a low-power state. This technology adds transistor feedback power supply to the RC step-down circuit, saving costs, maintaining low power consumption, and eliminating electromagnetic interference. The rectified and divided input voltage is connected to the emitter of transistor Q3 (PNP), and the divided output voltage is connected to the base of the transistor. The inputs of these two terminals form a comparator to control the switching on and off of transistor Q1, achieving power supply for the leakage current protector with low cost and low static power consumption.
[0017] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating this utility model, and are not intended to limit the implementation of this utility model. Those skilled in the art can make other variations or modifications based on the above description. It is not necessary to exhaustively list all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.
Claims
1. A power supply circuit for a residual current device (RCD), comprising, in sequence, an AC bridge input terminal, a resistive-capacitive step-down circuit, and a voltage regulator and energy storage circuit, characterized in that: A transistor feedback power supply circuit is connected in parallel with the resistor-capacitor step-down circuit; The transistor feedback power supply circuit includes a comparator circuit composed of transistors Q1, Q2, and Q3; Transistor Q3 controls the switching on and off of transistor Q1 through transistor Q2, driving transistor Q1 to supply power to the voltage regulator energy storage circuit.
2. The power supply circuit of the leakage current protector according to claim 1, characterized in that: The emitter of transistor Q1 is connected to the input terminal of the AC bridge. The base of transistor Q1 is connected to the collector of transistor Q2. The emitter of transistor Q2 is grounded. The base of transistor Q2 is connected to the collector of transistor Q3 and then grounded. The emitter of transistor Q3 is connected to the input terminal of the AC bridge. The base of transistor Q3 is connected to the collector of transistor Q1 after being connected in series with resistor R4. The base of transistor Q3 is grounded.
3. The power supply circuit of the leakage current protector according to claim 2, characterized in that: The emitter of transistor Q2 is connected to ground via resistor R9 in series, the collector of transistor Q3 is connected to ground via resistor R8 in series, and the base of transistor Q3 is connected to ground via resistor R5 in series.
4. The power supply circuit of the leakage current protector according to claim 3, characterized in that: A resistor R1 is connected in series between the emitter of transistor Q1 and the input terminal of the AC bridge.
5. The power supply circuit of the leakage current protector according to claim 4, characterized in that: The emitter of transistor Q3 is connected in series with resistor R2 to the input terminal of the AC bridge.
6. The power supply circuit of the leakage current protector according to claim 5, characterized in that: A resistor R3 is connected in series between the base of transistor Q1 and the collector of transistor Q2.
7. The power supply circuit of the leakage current protector according to claim 6, characterized in that: A capacitor C2 is connected in parallel to the input terminals of resistors R1 and R2. One end of capacitor C2 is connected to the input terminal of the AC bridge, and the other end is directly grounded.
8. The power supply circuit of the leakage current protector according to claim 7, characterized in that: The comparator circuit also includes a resistor R6, one end of which is connected in parallel with the emitter of transistor Q3, and the other end is grounded.
9. The power supply circuit of the leakage current protector according to claim 8, characterized in that: The described resistor-capacitor step-down circuit includes resistors R7, R10, R11, and C3. Resistor R10 is connected in series with resistor R11, then in parallel with capacitor C3, and finally in series with resistor R7 and the AC bridge input terminal.
10. The power supply circuit of the leakage current protector according to claim 9, characterized in that: The voltage-stabilized energy storage circuit includes a capacitor C1 and a diode D2 connected in parallel.