Self-powered circuit, circuit breaker
By adding PWM and hysteresis control circuits to the self-powered circuit, and based on the primary current switching control scheme of the current transformer, the problems of unstable power supply at low current and excessive power supply at high current are solved, thus realizing stable power extraction and voltage stability of the current transformer, and reducing measurement errors and core saturation.
Patent Information
- Application Number
- CN202521806665.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-25
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-25
AI Technical Summary
Existing self-powered circuits have unstable power supply at low current and excessive power supply at high current, which leads to current distortion and increased measurement error on the secondary side of the current transformer. Furthermore, the dual current transformer scheme results in a large circuit breaker with high cost.
The system employs a rectifier circuit, a current signal processing circuit, a PWM control circuit, a hysteresis control circuit, and a control switching circuit. By judging the magnitude of the primary current of the current transformer, the PWM and hysteresis control circuits are switched to achieve stable energy extraction control under different current conditions. The high-frequency PWM pulse signal and the hysteresis control circuit optimize the switching of the switching devices under low and high current conditions, respectively, to ensure voltage stability and energy utilization.
It improves the power supply stability at low currents, reduces current transformer core saturation and secondary current distortion, lowers measurement errors, and ensures voltage stability at high currents. It has the advantages of simple structure and fast response.
Smart Images
Figure CN224683880U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a self-powered circuit and belongs to the field of low-voltage electrical technology. Background Technology
[0002] With the development of the national economy and technology and the improvement of people's living standards, electricity has become an indispensable energy source in people's daily production and life, bringing endless convenience. With the construction of smart grids, the number of smart circuit breakers used in power grids is also increasing. Smart circuit breakers typically employ self-powered circuits, utilizing current transformers to extract electrical energy from the main circuit to power intelligent controllers, electronic trip units, and other components. The current transformer is the core component of the self-powered circuit; it must accurately measure current signals and reliably provide operating power. However, due to the inherent nonlinearity and magnetic saturation characteristics of current transformers, the power supply itself suffers from unstable power supply at low currents and excessive power supply at high currents. An effective energy extraction control circuit is needed to obtain a stable operating voltage. Furthermore, when the impedance of the load on the secondary side of the current transformer is high, its core requires a larger excitation current, which can easily lead to core saturation and severe distortion of the secondary current.
[0003] Existing energy harvesting control circuits typically employ a hysteresis comparator circuit. By controlling the switching on and off of the MOSFET in the energy harvesting circuit, the output voltage across the energy storage capacitor is controlled between the high and low threshold voltages of the hysteresis comparator circuit. This approach provides a stable and controllable operating voltage range. However, due to the limitations of the hysteresis comparator circuit, when the primary current of the current transformer is small, the MOSFET triggered by the energy storage capacitor voltage falling below the lower threshold voltage will remain off for a longer period. During this time, the secondary side of the current transformer operates continuously in a high-impedance state for an extended period, potentially leading to distortion of the secondary current. This is especially problematic when harmonics are present in the primary current, resulting in severe distortion of the secondary current and a significant increase in measurement error, affecting the reliability of the circuit breaker. On the other hand, since the MOSFET triggered by the energy storage capacitor voltage exceeding the upper threshold voltage has a relatively fixed on-time, the energy on the secondary side of the current transformer is not fully utilized during this period.
[0004] One improvement to this problem is to use dual current transformers, that is, to use one current transformer to extract energy and another current transformer to measure. However, this solution results in a larger circuit breaker size and higher cost, making it difficult to apply to small-sized circuit breakers. Utility Model Content
[0005] The technical problem to be solved by this utility model is to overcome the problems of unstable power supply at low current and excessive power supply at high current in the existing technology, and to provide a self-powered circuit that adopts different switching device on / off control schemes under different currents of the current transformer, thereby improving the power supply stability at low current and making full use of the energy on the secondary side of the current transformer at high current.
[0006] The present invention specifically adopts the following technical solution to solve the above-mentioned technical problems:
[0007] A self-powered circuit, comprising:
[0008] A rectifier circuit is used to rectify and output the secondary current of at least one current transformer and provide a current sampling signal of the secondary current.
[0009] The current signal processing circuit processes the current sampling signal provided by the rectifier circuit to obtain the current measurement signal. The energy harvesting circuit includes a switching device V1, a reverse protection diode D4, and an energy storage capacitor C1. The input terminal of the switching device V1 is connected to the positive output terminal of the rectifier circuit and the positive terminal of the reverse protection diode D4. The control terminal of the switching device V1 serves as the control signal input terminal of the energy harvesting circuit. The negative terminal of the reverse protection diode D4 is connected to the positive terminal of the energy storage capacitor C1 and serves as the output terminal of the energy harvesting circuit, outputting the system voltage Vcc. The output terminal of the switching device V1 and the negative terminal of the energy storage capacitor C1 are both grounded.
[0010] The PWM control circuit is used to generate a preset low-current energy harvesting circuit control signal Vpwm1.
[0011] The hysteresis control circuit is used to generate a high-current energy harvesting circuit control signal Vpwm2 based on the system voltage Vcc: when the system voltage Vcc rises to the high-voltage threshold V... H When the high-current power harvesting circuit control signal Vpwm2 is high, the system voltage Vcc drops to the low-voltage threshold V. L At this time, the high-current energy harvesting circuit control signal Vpwm2 is at a low level;
[0012] The control switching circuit is used to switch the control signal at the control signal input terminal of the power harvesting circuit according to the current measurement signal: when the current measurement signal is lower than the preset current threshold, the low current power harvesting circuit control signal Vpwm1 is input to the control signal input terminal of the power harvesting circuit; otherwise, the high current power harvesting circuit control signal Vpwm2 is input to the control signal input terminal of the power harvesting circuit.
[0013] Preferably, the rectifier circuit includes a set of rectifier sampling circuits corresponding one-to-one with the current transformers; each rectifier sampling circuit includes a rectifier bridge and a current sampling resistor, the input terminal of the rectifier bridge is connected to the secondary side of the corresponding current transformer, the negative output terminal of the rectifier bridge is grounded through the current sampling resistor and serves as the output terminal of the current sampling signal; the positive output terminals of all rectifier bridges are connected together to serve as the positive output terminal of the rectifier circuit.
[0014] Preferably, the current signal processing circuit includes a set of inverting amplifier circuits that correspond one-to-one with the current sampling signals.
[0015] Preferably, the frequency and duty cycle of the low-current energy harvesting circuit control signal Vpwm1 output by the PWM control circuit are adjustable.
[0016] Preferably, the energy extraction circuit further includes a TVS diode FV1 and a pull-down resistor R4. The negative terminal of the TVS diode FV1 is connected to the positive output terminal of the rectifier circuit, the input terminal of the switching device V1, and the positive terminal of the anti-reverse diode D4. One end of the pull-down resistor R4 is connected to the control terminal of the switching device V1. The positive terminal of the TVS diode FV1 and the other end of the pull-down resistor R4 are both grounded.
[0017] Preferably, the switching device V1 is a power switching device.
[0018] Preferably, the hysteresis control circuit includes resistors R11 to R13, capacitor C5, and comparator N5. One end of resistor R11 is connected to the system voltage Vcc, and the other end of resistor R11 is simultaneously connected to one end of capacitor C5, one end of resistor R12, one end of resistor R13, and the positive input terminal of comparator N5. The other end of capacitor C5 and the other end of resistor R12 are grounded. The negative input terminal of comparator N5 is connected to the reference voltage Vref3. The other end of resistor R13 is connected to the output terminal of comparator N5 and serves as the output terminal of the high current energy harvesting circuit control signal Vpwm2.
[0019] Preferably, the control switching circuit includes a set of comparison circuits corresponding one-to-one with the current measurement signals, as well as comparator N2D, resistors R7 and R8, capacitor C2, and analog switch N3; each comparison circuit includes a comparator and a reverse protection diode. The positive input terminal of the comparator is connected to its corresponding current measurement signal, the negative input terminal of the comparator is connected to the reference voltage Vref1, and the output terminal of the comparator is connected to the positive terminal of the reverse protection diode. The negative terminal of the reverse protection diode serves as the output terminal of the comparison circuit; the output terminals of each comparison circuit are simultaneously connected to resistor R7. One end of resistor R7 is connected to one end of capacitor C2, one end of resistor R8, and the positive input of comparator N2D. The other ends of capacitor C2 and resistor R8 are both grounded. The negative input of comparator N2D is connected to the reference voltage Vref2. The output of comparator N2D is connected to the IN terminal of analog switch N3. The NC and NO terminals of analog switch N3 are connected to the low current power extraction circuit control signal Vpwm1 and the high current power extraction circuit control signal Vpwm2, respectively. The COM terminal of analog switch N3 is connected to the control signal input of the power extraction circuit.
[0020] Based on the same inventive concept, the following technical solutions can also be obtained:
[0021] A circuit breaker comprising a self-powered circuit as described in any of the above technical solutions.
[0022] Compared with the prior art, the technical solution of this utility model has the following beneficial effects:
[0023] This invention, based on the existing energy harvesting control circuit based on a hysteresis comparator circuit, adds a PWM control circuit for generating control signals for the low-current energy harvesting circuit and a control switching circuit. The control switching circuit determines the magnitude of the primary current of the current transformer and switches the control of the PWM control circuit and the hysteresis control circuit on the energy harvesting circuit accordingly, achieving stable energy harvesting control of the current transformer under different current conditions. At low currents, the PWM control circuit controls the energy harvesting circuit, generating high-frequency PWM pulse signals to control the switching devices in the energy harvesting circuit, dispersing continuous conduction into multiple pulses, shortening the continuous high-impedance load time, and making the load on the current transformer more uniform. This alleviates the core saturation caused by the current transformer needing to operate continuously at high impedance for a long time to obtain sufficient energy when the primary current is small or even contains harmonics, thus improving the distortion of the secondary current waveform and reducing measurement errors. At high currents, the hysteresis control circuit controls the energy harvesting circuit, controlling the switching devices in the energy harvesting circuit based on the system voltage Vcc, ensuring stable Vcc voltage, strong anti-interference ability, and high stability. This utility model of a self-powered circuit has the advantages of simple structure, fast response, and ease of implementation. Attached Figure Description
[0024] Figure 1 This is a block diagram of the circuit structure of the circuit breaker of this utility model;
[0025] Figure 2 This is a specific circuit diagram of a rectifier circuit and an energy extraction circuit.
[0026] Figure 3 This is a specific implementation circuit diagram of a current signal processing circuit;
[0027] Figure 4 This is a circuit diagram of a specific implementation of a PWM control circuit;
[0028] Figure 5 This is a circuit diagram of a specific implementation of a hysteresis control circuit;
[0029] Figure 6 This is a circuit diagram illustrating a specific implementation of a control switching circuit. Detailed Implementation
[0030] To address the problems of unstable power supply at low currents and excessive power supply at high currents in existing technologies, this invention proposes adding a PWM control circuit and a control switching circuit to the existing power harvesting control circuit based on a hysteresis comparator circuit. The control switching circuit determines the magnitude of the primary current of the current transformer and switches the control of the PWM control circuit and the hysteresis control circuit on the power harvesting circuit accordingly, achieving stable power harvesting control of the current transformer under different current conditions. At low currents, the PWM control circuit controls the power harvesting circuit, generating a high-frequency PWM pulse signal to control the power harvesting circuit... The switching of the switching devices disperses the continuous conduction into multiple pulses, shortening the continuous high impedance time and making the load on the current transformer more uniform. This alleviates the core saturation caused by the secondary side needing to operate continuously at high impedance for a long time to obtain sufficient energy when the primary current is small or even contains harmonics. It also improves the distortion of the secondary current waveform and reduces measurement errors. Under high current conditions, the hysteresis control circuit controls the energy harvesting circuit. The hysteresis control circuit controls the conduction and cutoff of the switching devices in the energy harvesting circuit according to the magnitude of the system voltage Vcc, ensuring the voltage of Vcc is stable, with strong anti-interference ability and high stability.
[0031] Specifically, the self-powered circuit proposed in this utility model includes:
[0032] A rectifier circuit is used to rectify and output the secondary current of at least one current transformer and provide a current sampling signal of the secondary current.
[0033] The current signal processing circuit processes the current sampling signal provided by the rectifier circuit to obtain the current measurement signal. The energy harvesting circuit includes a switching device V1, a reverse protection diode D4, and an energy storage capacitor C1. The input terminal of the switching device V1 is connected to the positive output terminal of the rectifier circuit and the positive terminal of the reverse protection diode D4. The control terminal of the switching device V1 serves as the control signal input terminal of the energy harvesting circuit. The negative terminal of the reverse protection diode D4 is connected to the positive terminal of the energy storage capacitor C1 and serves as the output terminal of the energy harvesting circuit, outputting the system voltage Vcc. The output terminal of the switching device V1 and the negative terminal of the energy storage capacitor C1 are both grounded.
[0034] The PWM control circuit is used to generate a preset low-current energy harvesting circuit control signal Vpwm1.
[0035] The hysteresis control circuit is used to generate a high-current energy harvesting circuit control signal Vpwm2 based on the system voltage Vcc: when the system voltage Vcc rises to the high-voltage threshold V... H When the high-current power harvesting circuit control signal Vpwm2 is high, the system voltage Vcc drops to the low-voltage threshold V. L At this time, the high-current energy harvesting circuit control signal Vpwm2 is at a low level;
[0036] The control switching circuit is used to switch the control signal at the control signal input terminal of the power harvesting circuit according to the current measurement signal: when the current measurement signal is lower than the preset current threshold, the low current power harvesting circuit control signal Vpwm1 is input to the control signal input terminal of the power harvesting circuit; otherwise, the high current power harvesting circuit control signal Vpwm2 is input to the control signal input terminal of the power harvesting circuit.
[0037] To facilitate public understanding, the technical solution of this utility model will be described in detail below with reference to the accompanying drawings:
[0038] The basic structure of the circuit breaker of this utility model is as follows: Figure 1 As shown, it includes a microprocessor, other circuits (such as electronic trip units, communication circuits, etc.), and a self-powered circuit that powers these circuits.
[0039] like Figure 1As shown, the switching device of this utility model takes a MOSFET as an example. The self-powered circuit includes a rectifier circuit, a current signal processing circuit, an energy harvesting circuit, a PWM control circuit, a hysteresis control circuit, and a control switching circuit. The rectifier circuit is used to rectify the secondary current of at least one current transformer and provide a current sampling signal for that secondary current. The current signal processing circuit is used to process the current sampling signal provided by the rectifier circuit to obtain a current measurement signal. The power harvesting circuit is based on a MOSFET and a storage capacitor. It controls the switching of the MOSFET to achieve stable control of the system voltage Vcc output across the storage capacitor. The PWM control circuit is used to generate a preset low-current power harvesting circuit control signal (high-frequency PWM pulse signal). The hysteresis control circuit is used to generate a high-current power harvesting circuit control signal based on the system voltage Vcc: when the system voltage Vcc rises to the high voltage threshold, the high-current power harvesting circuit control signal is high; when the system voltage Vcc drops to the low voltage threshold, the high-current power harvesting circuit control signal is low. The control switching circuit is used to switch the control signal at the control signal input terminal of the power harvesting circuit based on the current measurement signal: when the current measurement signal is lower than the preset current threshold, a low-current power harvesting circuit control signal is input to the control signal input terminal of the power harvesting circuit; otherwise, a high-current power harvesting circuit control signal is input to the control signal input terminal of the power harvesting circuit.
[0040] The above-mentioned functional circuits can be implemented using various existing circuits. The following is a specific embodiment to further illustrate them:
[0041] The self-powered circuit in this embodiment uses three current transformers: 1a, 1b, and 1c to extract electrical energy from the three phases A, B, and C of the main circuit, respectively.
[0042] like Figure 2 As shown, the rectifier circuit in this embodiment includes three rectifier sampling circuits corresponding one-to-one with the current transformers. Each rectifier sampling circuit includes a rectifier bridge (rectifier bridges D1 to D3) and a current sampling resistor (R1 to R3). The input terminals of rectifier bridges D1 to D3 are connected to the secondary windings of their corresponding current transformers. The negative output terminals of rectifier bridges D1 to D3 are grounded via current sampling resistors R1 to R3 and serve as the output terminals of current sampling signals Va1, Vb1, and Vc1, respectively. The positive output terminals of rectifier bridges D1 to D3 are connected together to serve as the positive output terminal of the rectifier circuit. The rectifier bridges rectify the AC current output from the current transformers into pulsating DC current, and the current sampling resistors convert the pulsating DC current signals into current sampling signals Va1, Vb1, and Vc1, which are then sent to the current signal processing circuit for processing.
[0043] like Figure 2As shown, the power extraction circuit in this embodiment includes a MOSFET V1, a TVS diode FV1, a reverse protection diode D4, an energy storage capacitor C1, and a pull-down resistor R4. The drain of the MOSFET V1 is connected to the positive output terminal of the rectifier circuit, the negative terminal of the TVS diode FV1, and the positive terminal of the reverse protection diode D4. The gate of the MOSFET V1 is connected to one end of the pull-down resistor R4 and serves as the control signal input terminal of the power extraction circuit. The negative terminal of the reverse protection diode D4 is connected to the positive terminal of the energy storage capacitor C1 and serves as the output terminal of the power extraction circuit, outputting the system voltage Vcc. The positive terminal of the TVS diode FV1, the other end of the pull-down resistor R4, the source of the MOSFET V1, and the negative terminal of the energy storage capacitor C1 are all grounded. When the control signal received at the control signal input terminal of the power extraction circuit is high, the MOSFET is turned on; when the control signal is low, the MOSFET is turned off. The TVS diode FV1 is used to absorb instantaneous overvoltage, providing protection. The reverse protection diode D4 is used to prevent the energy storage capacitor C1 from discharging through the MOSFET V1. The energy storage capacitor C1 provides a relatively stable system voltage Vcc for the downstream load.
[0044] The current signal processing circuit in this embodiment includes three inverting amplifier circuits corresponding to the current sampling signals Va1, Vb1, and Vc1, respectively. Taking the inverting amplifier circuit corresponding to the current sampling signal Va1 as an example, its circuit structure is as follows: Figure 3 As shown, this inverting amplifier circuit, consisting of resistors R5 and R6 and operational amplifier N1, processes the current sampling signal Va1 to obtain the current measurement signal Va. The other two inverting amplifier circuits are similar.
[0045] The PWM control circuit in this embodiment is as follows: Figure 4 As shown, the circuit consists of resistors R9 and R10, capacitors C3 and C4, and a 555 timer N4. It is used to output the low-current power extraction circuit control signal Vpwm1 when the current is small. The frequency of Vpwm1 is... Duty cycle Both can be adjusted.
[0046] like Figure 5 As shown, the hysteresis control circuit in this embodiment includes resistors R11-R13, capacitor C5, and comparator N5. One end of resistor R11 is connected to the system voltage Vcc. The other end of resistor R11 is simultaneously connected to one end of capacitor C5, one end of resistor R12, one end of resistor R13, and the positive input terminal of comparator N5. The other end of capacitor C5 and the other end of resistor R12 are grounded. The negative input terminal of comparator N5 is connected to the reference voltage Vref3. The other end of resistor R13 is connected to the output terminal of comparator N5 and serves as the output terminal of the high-current energy harvesting circuit control signal Vpwm2. The hysteresis control circuit detects the voltage of Vcc through the voltage divider resistors R11 and R12. When Vcc starts to rise to the set high voltage threshold V... HAt this time, the positive input voltage is higher than the negative input voltage Vref3, the high current power extraction circuit control signal Vpwm2 is high, the MOSFET is turned on, the current transformer energy is bypassed through the MOSFET, the power supply stops, and the Vcc voltage drops. At this time, the output voltage of comparator N5, through feedback resistor R13, and Vcc, through voltage divider resistors, act together on the positive input terminal of N5. When the Vcc voltage is lower than the low voltage threshold V... L At this time, the voltage at the positive input terminal is lower than the voltage at the negative input terminal Vref3. The control signal Vpwm2 of the high current energy harvesting circuit is at a low level, the MOSFET is turned off, the current transformer is powered again, the Vcc voltage rises, until the MOSFET is turned on again, and the cycle repeats to achieve constant voltage control.
[0047] like Figure 6 As shown, the control switching circuit in this embodiment consists of comparators N2A-N2D, anti-reverse diodes D5-D7, resistors R7 and R8, capacitor C2, and analog switch N3. The positive input terminals of comparators N2A-N2C are connected to current measurement signals Va, Vb, and Vc, respectively; the negative input terminals of comparators N2A-N2C are connected to the reference voltage Vref1; the output terminals of comparators N2A-N2C are connected to the positive terminals of anti-reverse diodes D5-D7, and the negative terminals of anti-reverse diodes D5-D7 are simultaneously connected to one end of resistor R7. The other end of R7 is connected to one end of capacitor C2, one end of resistor R8, and the positive input of comparator N2D. The other ends of capacitor C2 and resistor R8 are both grounded. The negative input of comparator N2D is connected to the reference voltage Vref2. The output of comparator N2D is connected to the IN terminal of analog switch N3. The NC and NO terminals of analog switch N3 are connected to the low current power extraction circuit control signal Vpwm1 and the high current power extraction circuit control signal Vpwm2, respectively. The COM terminal of analog switch N3 is connected to the control signal input of the power extraction circuit. The current measurement signals Va, Vb, and Vc are integrated by comparators N2A-N2C and anti-reverse diodes D5-D7, and then output as a current discrimination signal Vm after passing through a hysteresis circuit composed of resistors R7, R8, and capacitor C2. The current discrimination signal Vm is compared with the switching threshold voltage Vref2 by comparator N2D. When Vm < Vref2, comparator N2D outputs a low level, and pins 1 and 2 of analog switch N3 are in the on state. At this time, the control signal Vpwm output by pin 1 of analog switch N3 is the low current energy harvesting circuit control signal Vpwm1 output by the PWM control circuit, which performs energy harvesting control on the energy harvesting circuit. When Vm ≥ Vref2, comparator N2D outputs a high level, and pins 1 and 8 of analog switch N3 are in the on state. At this time, the control signal Vpwm output by pin 1 of analog switch N3 is the high current energy harvesting circuit control signal Vpwm2 output by the hysteresis control circuit, which performs energy harvesting control on the energy harvesting circuit.
Claims
1. A self-powered circuit, characterized in that, include: A rectifier circuit is used to rectify and output the secondary current of at least one current transformer and provide a current sampling signal of the secondary current. The current signal processing circuit is used to process the current sampling signal provided by the rectifier circuit to obtain the current measurement signal; The power extraction circuit includes a switching device V1, a reverse protection diode D4, and an energy storage capacitor C1. The input terminal of the switching device V1 is connected to the positive output terminal of the rectifier circuit and the positive terminal of the reverse protection diode D4. The control terminal of the switching device V1 serves as the control signal input terminal of the power extraction circuit. The negative terminal of the reverse protection diode D4 is connected to the positive terminal of the energy storage capacitor C1 and serves as the output terminal of the power extraction circuit, outputting the system voltage Vcc. The output terminal of the switching device V1 and the negative terminal of the energy storage capacitor C1 are both grounded. The PWM control circuit is used to generate a preset low-current energy harvesting circuit control signal Vpwm1. The hysteresis control circuit is used to generate a high-current energy harvesting circuit control signal Vpwm2 based on the system voltage Vcc: when the system voltage Vcc rises to the high voltage threshold V... H When the high-current power harvesting circuit control signal Vpwm2 is high, the system voltage Vcc drops to the low-voltage threshold V. L At this time, the high-current energy harvesting circuit control signal Vpwm2 is at a low level; The control switching circuit is used to switch the control signal at the control signal input terminal of the power harvesting circuit according to the current measurement signal: when the current measurement signal is lower than the preset current threshold, the low current power harvesting circuit control signal Vpwm1 is input to the control signal input terminal of the power harvesting circuit; otherwise, the high current power harvesting circuit control signal Vpwm2 is input to the control signal input terminal of the power harvesting circuit.
2. The self-powered circuit as described in claim 1, characterized in that, The rectifier circuit includes a set of rectifier sampling circuits corresponding one-to-one with the current transformers; each rectifier sampling circuit includes a rectifier bridge and a current sampling resistor. The input terminal of the rectifier bridge is connected to the secondary winding of its corresponding current transformer, and the negative output terminal of the rectifier bridge is grounded through the current sampling resistor and serves as the output terminal of the current sampling signal; the positive output terminals of all rectifier bridges are connected together to serve as the positive output terminal of the rectifier circuit.
3. The self-powered circuit as described in claim 1, characterized in that, The current signal processing circuit includes a set of inverting amplifier circuits that correspond one-to-one with the current sampling signals.
4. The self-powered circuit as described in claim 1, characterized in that, The frequency and duty cycle of the low-current energy harvesting circuit control signal Vpwm1 output by the PWM control circuit are both adjustable.
5. The self-powered circuit as described in claim 1, characterized in that, The energy extraction circuit also includes a TVS diode FV1 and a pull-down resistor R4. The negative terminal of the TVS diode FV1 is connected to the positive output terminal of the rectifier circuit, the input terminal of the switching device V1, and the positive terminal of the anti-reverse diode D4. One end of the pull-down resistor R4 is connected to the control terminal of the switching device V1. The positive terminal of the TVS diode FV1 and the other end of the pull-down resistor R4 are both grounded.
6. The self-powered circuit as described in claim 1, characterized in that, The switching device V1 is a power switching device.
7. The self-powered circuit as described in claim 1, characterized in that, The hysteresis control circuit includes resistors R11 to R13, capacitor C5, and comparator N5. One end of resistor R11 is connected to the system voltage Vcc. The other end of resistor R11 is connected to one end of capacitor C5, one end of resistor R12, one end of resistor R13, and the positive input terminal of comparator N5. The other end of capacitor C5 and the other end of resistor R12 are grounded. The negative input terminal of comparator N5 is connected to the reference voltage Vref3. The other end of resistor R13 is connected to the output terminal of comparator N5 and serves as the output terminal of the high current energy harvesting circuit control signal Vpwm2.
8. The self-powered circuit as described in claim 1, characterized in that, The control switching circuit includes a set of comparator circuits corresponding one-to-one with the current measurement signal, as well as comparator N2D, resistors R7 and R8, capacitor C2, and analog switch N3. Each comparator circuit includes a comparator and a reverse protection diode. The positive input terminal of the comparator is connected to its corresponding current measurement signal, the negative input terminal is connected to the reference voltage Vref1, and the output terminal of the comparator is connected to the positive terminal of the reverse protection diode. The negative terminal of the reverse protection diode serves as the output terminal of the comparator circuit. The output terminals of each comparator circuit are also connected to one end of resistor R7. The other end of resistor R7 is connected to one end of capacitor C2, one end of resistor R8, and the positive input of comparator N2D. The other ends of capacitor C2 and resistor R8 are both grounded. The negative input of comparator N2D is connected to the reference voltage Vref2. The output of comparator N2D is connected to the IN terminal of analog switch N3. The NC and NO terminals of analog switch N3 are connected to the low current power extraction circuit control signal Vpwm1 and the high current power extraction circuit control signal Vpwm2, respectively. The COM terminal of analog switch N3 is connected to the control signal input of the power extraction circuit.
9. A circuit breaker, characterized in that, Includes the self-powered circuit as described in any one of claims 1 to 8.