Residual current operated circuit breaker

Abstract

A residual current circuit breaker comprises a residual current transformer, an excitation oscillation circuit, an integration circuit and a main control circuit, the excitation oscillation circuit is connected with an excitation winding of the residual current transformer, the integration circuit is used for converting an excitation square wave signal generated by the excitation oscillation circuit into a triangular wave signal and then outputting the triangular wave signal through a first output end and a second output end respectively, the first output end is connected with the main control circuit through a filter amplification circuit, the second output end is directly connected with the main control circuit, the main control circuit collects residual currents of the filter amplification circuit and / or the second output end respectively, and is used for controlling the residual current circuit breaker to be disconnected, so that not only residual currents of different sizes can be processed, but also the use of hardware circuits can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low-voltage electrical apparatus, in particular to a residual current circuit breaker. BACKGROUND

[0002] With the rapid development of the new energy industry at present, the existing AC type and A type residual current protection device cannot protect the residual current of all load type products. At this time, a full type residual current protection device with alternating current, pulsating direct current, smooth direct current, composite current, high frequency current, etc. is needed. However, the existing residual current protection devices on the market have a rated current of 63A and below, and a rated residual current of 300mA and below. With the increase of charging pile capacity at present, they cannot meet the needs of large-capacity photovoltaic power generation and automobile charging systems. Therefore, a residual current protection device with larger rated current and rated residual current is needed, which can be used as a general switch for new energy distribution systems. However, the existing residual current protection devices have poor sampling accuracy, and with the expansion of the rated residual current range and the adjustment, the sampling accuracy is poor or the cost is high. SUMMARY

[0003] The purpose of the present application is to overcome the defects of the prior art and provide a residual current circuit breaker with rated current and rated residual current meeting the needs of new energy distribution systems.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] A residual current circuit breaker, comprising a power supply circuit, a sampling circuit and a main control circuit, the power supply circuit supplies power to the sampling circuit and the main control circuit, the main control circuit collects the residual current of the main circuit of the circuit breaker through the sampling circuit, the sampling circuit comprises an excitation oscillation circuit and an integration circuit, the excitation oscillation circuit is connected with the excitation winding of the residual current transformer, the integration circuit is used for converting the excitation square wave signal generated by the excitation oscillation circuit into a triangular wave signal and outputting through the first output end and the second output end respectively, the first output end is connected with the main control circuit through a filter amplification circuit, the second output end is directly connected with the main control circuit, the main control circuit collects the residual current of the filter amplification circuit and / or the second output end respectively, and is used for controlling the residual current circuit breaker to be disconnected.

[0006] Preferably, it further comprises a residual current gear selection circuit and a delay gear selection circuit connected with the main control circuit respectively, the residual current gear selection circuit is used for outputting a plurality of different signals to the main control circuit to set the action threshold of the residual current, and the delay gear selection circuit is used for outputting a plurality of different signals to the main control circuit to set the delay threshold of the residual current.

[0007] Preferably, the main control circuit performs FIR or Kalman digital filtering on the second output terminal.

[0008] Preferably, the integration circuit comprises an operational amplifier U6B, a high-pass filter circuit and an RC integration circuit connected to the input terminal of the operational amplifier U6B, respectively, the output terminal of the operational amplifier U6B is connected to the filter-amplification circuit and the main control circuit, respectively, the high-pass filter circuit is connected to the excitation oscillation circuit, the high-pass filter circuit is used to filter the duty cycle signal output by the excitation oscillation circuit, the RC integration circuit is used to convert the filtered signal into a triangular wave signal, and the operational amplifier U6B is used as a voltage follower to increase the driving ability of the triangular wave signal at the same input terminal.

[0009] Preferably, the excitation oscillation circuit comprises a square wave pulse voltage driving circuit and a comparison circuit, the square wave pulse voltage driving circuit and the comparison circuit are connected to the secondary winding of the residual current transformer, and are used to form a cyclic self-excitation oscillation.

[0010] Preferably, the filter-amplification circuit comprises a four-order filter circuit composed of two second-order Butterworth active filter circuits in series.

[0011] Preferably, the filter-amplification circuit is further connected to a zero-adjusting circuit.

[0012] Preferably, the two second-order Butterworth active filter circuits each comprise an operational amplifier, the operational amplifier of one second-order Butterworth active filter circuit is connected to the zero-adjusting circuit, the zero-adjusting circuit comprises a resistor R60 and a resistor R63 connected between the voltage VCC and the ground terminal, the resistor R60 and the resistor R63 are connected in series, and the connection point between the resistor R60 and the resistor R63 is connected to the voltage at the same input terminal of the operational amplifier of the second-order Butterworth active filter circuit.

[0013] Preferably, the excitation oscillation circuit comprises a comparator U5B, a NPN transistor Q4, a PNP transistor Q6, the collector of the NPN transistor Q4 is connected with the voltage VCC, the emitter of the NPN transistor Q4 is connected with the emitter of the PNP transistor Q6, the collector of the PNP transistor Q6 is grounded, the connection point between the emitter of the NPN transistor Q4 and the emitter of the PNP transistor Q6 is connected with one end of the excitation winding of the residual current transformer, the reverse input end of the comparator U5B is connected with the reference voltage Vref through the resistor R1 and the resistor R5, the connection point between the resistor R1 and the resistor R5 is connected with the other end of the excitation winding, the bidirectional voltage stabilizing tube D6 is connected in parallel across the excitation winding, the positive input end of the comparator U5B is connected with the reference voltage Vref through the resistor R2, one end of the resistor R4 and the capacitor C20 connected in parallel is connected with the output end of the comparator U5B, the other end is connected with the base of the NPN transistor Q4 and the PNP transistor Q6, the output end of the comparator U5B is connected to the positive input end of the comparator U5B through the resistor R3 and is output to the main control circuit.

[0014] Preferably, the excitation oscillation circuit comprises a comparator U5B, the output end of the comparator U5B is connected with one end of the excitation winding of the residual current transformer, the reverse input end of the comparator U5B is connected with the reference voltage Vref through the resistor R28, the resistor R35 and the resistor R40, the other end of the excitation winding is connected between the resistor R28 and the resistor R35, the positive input end of the comparator U5B is connected with the reference voltage Vref through the resistor R38, the output end of the comparator U5B is connected to the positive input end of the comparator U5B through the resistor R36 and is output to the main control circuit, the bidirectional voltage stabilizing tube D6 is connected in parallel across the excitation winding, one end of the capacitor C23 is grounded, the other end is connected between the resistor R35 and the resistor R40.

[0015] The residual current circuit breaker of the application, the output signal of the integration circuit is divided into two signals by the first output end and the second output end, one of which is processed by the hardware filter amplification circuit and is input to the ADC of the main control circuit, used for processing small residual current signals such as 0.1A and below, the other is directly input to the ADC of the main control circuit, the main control circuit can filter out the carrier component of the triangular wave by digital filtering processing, restore the characteristics of the fundamental residual current in the main circuit, used for processing large residual current signals such as 0.1A and above, which can improve the accuracy of the sampled residual current, not only can process large and small residual currents, but also can reduce the use of hardware circuit. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the principle block diagram of the residual current circuit breaker of the application;

[0017] Figure 2 is the excitation voltage waveform diagram of the secondary winding when no residual current appears;

[0018] Figure 3 is the excitation voltage waveform of the secondary winding when residual current occurs;

[0019] Figure 4 is the excitation current waveform of the secondary winding when residual current does not occur;

[0020] Figure 5 is the excitation current waveform of the secondary winding when residual current occurs;

[0021] Figure 6 is the excitation current waveform of the secondary winding when residual current does not occur, Figure 2 is the waveform diagram after the waveform is integrated and transformed;

[0022] Figure 7 is the excitation current waveform of the secondary winding when residual current occurs, Figure 3 is the waveform diagram after the waveform is integrated and transformed;

[0023] Figure 8 is the excitation current waveform of the secondary winding when residual current does not occur, Figure 6 is the waveform diagram after the waveform is actively filtered;

[0024] Figure 9 is the excitation current waveform of the secondary winding when residual current occurs, Figure 7 is the waveform diagram after the waveform is actively filtered;

[0025] Figure 10 is the timing diagram of the power-on and power-off process of the voltage VCC, the voltage VDD and the ADC input of the master control circuit;

[0026] Figure 11 is the circuit diagram of the power supply monitoring circuit of the present application;

[0027] Figure 12 is the power-on and power-off process of the voltage VDD of the present application;

[0028] Figure 13 is the circuit diagram of the excitation oscillation circuit of the present application;

[0029] Figure 14 is the circuit diagram of another implementation mode of the excitation oscillation circuit of the present application;

[0030] Figure 15 is the circuit diagram of the residual current test circuit of the present application;

[0031] Figure 16 is the circuit diagram of the residual current test button detection of the present application;

[0032] Figure 17 is the circuit diagram of the tripping control circuit of the present application;

[0033] Figure 18 This is a flowchart illustrating the implementation process of this invention;

[0034] Figure 19 This invention relates to a residual current range and delay range selection circuit.

[0035] Figure 20 This is a circuit diagram of the integrator circuit created in this invention;

[0036] Figure 21 This is a circuit diagram of the filter amplifier circuit and zero-adjustment circuit created in this invention;

[0037] Figure 22 This is a circuit diagram of the rectifier circuit created by the present invention;

[0038] Figure 23 This is a circuit diagram of the BUCK step-down circuit created in this invention;

[0039] Figure 24 This is a circuit diagram of the DC-DC step-down circuit created in this invention;

[0040] Figure 25 This is a circuit diagram of the first step-down circuit created by the present invention;

[0041] Figure 26 This is a circuit diagram of the first step-down circuit created by the present invention. Detailed Implementation

[0042] The following is in conjunction with the appendix Figures 1 to 26 The given embodiments further illustrate specific implementations of the residual current operated circuit breaker of the present invention. The residual current operated circuit breaker of the present invention is not limited to the descriptions of the following embodiments.

[0043] like Figure 1 As shown, the residual current operated circuit breaker of this invention includes a residual current transformer 101, an excitation oscillation circuit 109, an integrator circuit 110, and a main control circuit 120. The excitation oscillation circuit 109 is connected to the excitation winding 107 on the residual current transformer. The integrator circuit 110 is used to convert the excitation square wave signal generated by the excitation oscillation circuit 109 into a triangular wave signal and output it through a first output terminal and a second output terminal respectively. The first output terminal is connected to the main control circuit 120 through a filter amplifier circuit 112, and the second output terminal is directly connected to the main control circuit 120. The main control circuit 120 performs digital filtering processing on the second output terminal. The main control circuit 120 collects the residual current of the filter amplifier circuit 112 and / or the second output terminal respectively to control the residual current operated circuit breaker to open. The main control circuit 120 determines the magnitude and duration of the residual current based on the first and second output terminals of the integrator circuit 110 respectively, and drives the residual current operated circuit breaker to open when the operating conditions are met.

[0044] The residual current circuit breaker of the present application, the output signal of the integration circuit 110 is divided into two signals by the first output end and the second output end, one of which is processed as the ADC input of the main control circuit 120 after being filtered and amplified by the hardware filter amplifier circuit 112, used to process small residual current signals such as 0.1A and below, the other is directly input to the ADC of the main control circuit 120, which can filter out the carrier component of the triangular wave through digital filtering processing, restore the characteristics of the fundamental residual current in the main circuit, and process large residual current signals such as 0.1A and above, which can improve the accuracy of the sampled residual current, not only can process large and small residual currents, but also can reduce the use of hardware circuits.

[0045] As shown in Figure 1 , the residual current circuit breaker of the present application includes a power supply circuit, a sampling circuit and a main control circuit 120, the power supply circuit supplies power to the sampling circuit and the main control circuit 120, the main control circuit 120 collects the residual current of the main circuit of the circuit breaker through the sampling circuit, when detecting the residual current, the main control circuit 120 outputs a trip control signal to the trip circuit to trigger the operating mechanism to trip, and then the residual current circuit breaker is disconnected. The sampling circuit of the present application includes a magnetizing oscillation circuit 109, an integration circuit 110, a filter circuit amplifier circuit 112 and a zero adjustment circuit 113 connected in sequence; the power supply circuit includes a rectifier circuit 102, and a first voltage reduction circuit 104 and a second voltage reduction circuit 106 connected to the rectifier circuit 102 through a BUCK voltage reduction circuit respectively. The residual current circuit breaker of the present application is a full-type residual current protection device with monitoring and protection of alternating current, pulsating direct current, smooth direct current, composite current, high-frequency current, etc. As shown in Figure 1 , the power supply circuit includes a rectifier circuit 102, and a first voltage reduction circuit 104 and a second voltage reduction circuit 106 connected to the rectifier circuit 102 through a BUCK voltage reduction circuit respectively, the first voltage reduction circuit 104 is used to provide voltage VCC and reference voltage Vref for the sampling circuit, the second voltage reduction circuit 106 is used to provide voltage VDD for the main control circuit 120, and the voltage VCC is greater than the voltage VDD, the voltage VCC of the present application is 12V, and the voltage VDD is 3.3V, the first voltage reduction circuit 104 is also used to generate a reference voltage Vref. As shown in Figure 10As shown, because the voltage VCC is greater than the voltage VDD, during the power-on process, the voltage VDD will be stabilized first, and the main control circuit 120 will start sampling through the sampling circuit when the voltage VCC is not stable. During the power-off process, the voltage VCC will also be powered off first, which also causes the sampling circuit to be unstable, and further causes the product to malfunction. Because the excitation oscillation circuit 109 is powered by 12V, and the MCU sampling here is powered by 3.3V, during power-on, 3.3V is stabilized first, and 12V is stabilized later, which will cause the MCU to start ADC sampling when the excitation oscillation circuit has not yet worked normally, and thus the ADC data collection is inaccurate, causing the trip to be triggered. During power-off, 12V is powered off first, and 3.3V is still stable, which will also cause the ADC sampling to be inaccurate, causing the trip to be triggered.

[0046] Preferably, the residual current operating circuit of the application further comprises a power supply monitoring circuit 122 connected with the main control circuit 120, the power supply monitoring circuit 122 collects the voltage VCC and the voltage VDD respectively, for detecting whether the power supply VCC is stable, and the monitoring signal output by the power supply monitoring circuit 122 can make the main control circuit 120 unable to output the trip signal. By monitoring the voltage VCC for powering the sampling circuit and the voltage VDD for powering the main control circuit through the power supply monitoring circuit, and outputting the monitoring signal to the main control circuit, only when the voltage VCC meets the stable condition, and the residual current size and duration meet the operating condition, the main control circuit can drive the residual current operating circuit to be disconnected, which can prevent the main control circuit from sampling the residual current unstably due to the unstable voltage VCC during the power-on and power-off processes, and further prevent the main control circuit from triggering the product to operate mistakenly.

[0047] Preferably, the power supply circuit further comprises a DC-DC step-down circuit 105, the DC-DC step-down circuit 105 comprises a step-down chip U2 connected between the second step-down circuit 106 and the rectifier circuit 102, and the model of the step-down chip U2 is LA1631. The rectifier circuit 102 comprises a rectifier bridge, for rectifying the single-phase or three-phase input current into a pulsating DC power supply, as the input of the BUCK step-down circuit 103, the BUCK step-down circuit 103 is used for step-down processing the rectified pulsating DC power supply to obtain a low-voltage DC power supply, the first step-down circuit 104 and the second step-down circuit 106 are linear step-down circuits respectively, the first step-down circuit 104 is used for linear step-down processing the low-voltage DC voltage output by the BUCK step-down circuit 103 into a smooth low-voltage DC voltage VCC and a reference reference power supply Vref, wherein Vref=VCC / 2.

[0048] As Figure 24The circuit diagram of the first voltage reduction circuit 104 is shown, the first voltage reduction circuit 104 includes a linear voltage reduction chip U4, the linear voltage reduction chip U4 is a special fixed value voltage reduction chip, the linear voltage reduction chip U4 is of the model MC78M12ABDTRKG, the input end of the linear voltage reduction chip U4 is connected with the BUCK voltage reduction circuit 103, the output end of the linear voltage reduction chip U4 is used for outputting the voltage VCC after voltage reduction, the output end of the linear voltage reduction chip U4 is connected with the input end of the over operational amplifier U5B after voltage division through resistors R20 and R24 of the same resistance value, and the output reference voltage Vref is followed by the output end of the over operational amplifier U5B.

[0049] As Figure 25 The circuit diagram of the second voltage reduction circuit 106 is shown, the second voltage reduction circuit 106 includes a linear voltage reduction chip U3, the linear voltage reduction chip U3 is a special fixed value voltage reduction chip, the linear voltage reduction chip U3 is of the model SGM2205, the input end of the linear voltage reduction chip U3 is connected with the DC-DC voltage reduction circuit 105 through a resistor R5, the output end of the linear voltage reduction chip U3 is used for generating the voltage VDD to supply power to the main control circuit 120, the two ends of the resistor R5 are respectively connected with the ground through a capacitor C4 and a capacitor C8, and the output end of the linear voltage reduction chip U3 is connected with the ground through a capacitor C7.

[0050] As Figure 21 The circuit diagram of the rectifier circuit 102 is shown, the rectifier circuit 102 includes a surge protection circuit and a rectifier part, and has the characteristics of three-phase four-wire arbitrary connection without distinguishing A, B, C and N. The surge protection circuit includes a pressure sensitive resistor RV1, a pressure sensitive resistor RV2, a pressure sensitive resistor RV3 and a pressure sensitive resistor RV4, one end of each of the pressure sensitive resistors RV1, RV2, RV3 and RV4 is connected with a first power line, a second power line, a third power line and a fourth power line respectively, and the other end of each of the pressure sensitive resistors RV1, RV2, RV3 and RV4 is connected with each other and connected to a common point, and the common point is not connected with other circuits. In the normal power supply process, two pressure sensitive resistors are connected in series between any two phases, thereby improving the rated use voltage of the product. Meanwhile, the four pressure sensitive resistors can adopt the same nominal voltage specification, and the residual voltage is lower than that of the connection mode of A, B and C to N respectively using higher nominal voltage pressure sensitive resistors in the case of surge voltage impact, thereby reducing the design requirements of the subsequent circuit.

[0051] The rectifier part includes rectifier diodes D1, D2, D3, D4, D5, D6, the anode of the first power line connected diode D1, the anode of the second power line connected diode D2 and the cathode of the diode D6, the cathode of the third power line connected diode D5, the anode of the fourth power line connected diode D3 and the cathode of the diode D4; further, the cathodes of the diodes D1, D2, D3 are connected to the input of the subsequent power supply, and the anodes of the diodes D4, D5, D6 are connected to the floating ground of the subsequent power supply.

[0052] As shown in Figure 22 , the BUCK voltage reduction circuit 103 includes a power supply chip U1, which is a dedicated BUCK voltage reduction chip, the model of the power supply chip U1 is LNK3296, it has a built-in MOS switch tube with a voltage higher than 800V, which can reduce the voltage after the rectifier circuit 102 to 12-24V low voltage available, the input end of the power supply chip U1 is connected with the rectifier circuit 102 through the resistance RT1, the resistance RT1, the capacitor C3 and the capacitor C9 in series form an RC filter circuit, the capacitor C3 and the capacitor C9 are in series to improve the overall voltage resistance, the resistance R4 and the resistance R7 are connected in series and then connected in parallel to the both ends of the capacitor C3, the resistance R9 and the resistance R11 are connected in series and then connected in parallel to the both ends of the capacitor C9, the resistance R4, the resistance R7, the resistance R9 and the resistance R11 are used as voltage-sharing resistors to evenly distribute the voltage across the capacitor C3 and the capacitor C9.

[0053] The DC-DC voltage reduction circuit 105 is also used to linearly reduce the low voltage DC voltage output by the BUCK voltage reduction circuit 103 to improve the conversion efficiency of the power supply, the output voltage of the DC-DC voltage reduction circuit 105 is linearly reduced by the second voltage reduction circuit 106 to become a smooth low voltage DC voltage VDD, and the generated voltage VDD is used to power the main control circuit 120 and related circuits.

[0054] It can be understood that the DC-DC voltage reduction circuit 105 can also not be set, and the voltage VDD can also be obtained directly through the second voltage reduction circuit 106, which all belong to the protection scope of the present application.

[0055] As shown in Figures 2 to 5 , the excitation oscillation circuit 109 is formed based on the nonlinear magnetization curve characteristics of the ferromagnetic material to form an RL self-oscillation, the excitation oscillation circuit 109 includes a square wave pulse voltage driving circuit and a comparison circuit, which are connected with the secondary winding 107 of the residual current transformer to form a circulating self-oscillation, and the square wave excitation voltage is applied across the secondary winding 107 of the residual current transformer through the excitation oscillation circuit 109, as shown in Figure 2 , the direction of the excitation current flowing through the secondary winding 107 of the residual current transformer is changed in a cycle, as shown in Figure 4The magnetic core 101 of the residual current transformer is switched between positive saturation and negative saturation.

[0056] When there is residual current in the main circuit, taking the direct current residual current as an example: the residual current transformer magnetic core 101 will be magnetized in one direction, which will cause the magnetic core to enter the magnetic saturation state in this direction in advance, and the corresponding excitation square wave duty cycle will be narrowed, and correspondingly, the residual current transformer magnetic core 101 will be delayed to enter the saturation state in the other direction, and the corresponding square wave excitation voltage duty cycle will be widened, as shown in Figure 3 At the same time, the current in the secondary winding 107 of the residual current transformer will also change accordingly, as shown in Figure 5 At the same time, the VCC is greater than the VDD, so as to provide a larger excitation current. As shown in Figures 13-14 Two embodiments of the excitation oscillation circuit 109 are shown respectively, both of which belong to the protection scope of the present application.

[0057] As shown in Figures 6-7 , the integral circuit 110 is used to convert the excitation square wave signal generated by the excitation oscillation circuit 109 into a triangular wave signal, as shown in Figure 6 and Figure 7 , the triangular wave signal acts as a carrier signal of the residual current in the main circuit passing through the residual current transformer magnetic core 101, which can reflect the fundamental residual current change characteristics in the main circuit, including the size and direction of the fundamental residual current in the main circuit.

[0058] As shown in Figure 19 , the integral circuit 110 includes an operational amplifier U6B and a high-pass filter circuit and an RC integral circuit connected to the input end of the operational amplifier U6B respectively, the output end of the operational amplifier U6B is connected with the filter amplification circuit 112 and the main control circuit 120 respectively, the high-pass filter circuit is connected with the excitation oscillation circuit 109, the high-pass filter circuit is used to filter the duty cycle signal output by the excitation oscillation circuit 109, the RC integral circuit is used to convert the filtered signal into a triangular wave signal, and the operational amplifier U6B is used as a voltage follower to increase the driving ability of the triangular wave signal at the same input end.

[0059] Specifically, the duty cycle signal output by the excitation oscillation circuit 109 enters the integral circuit 110 and is filtered by the high-pass filter circuit composed of the resistor R36 and the capacitor C17, and then is converted into a triangular wave signal by the RC integral circuit composed of the resistor R40 and the capacitor C20, the operational amplifier U6B is used as a voltage follower in the circuit to increase the driving ability of the triangular wave signal at the same input end, the first output end output signal of the operational amplifier U6B enters the next level of hardware filter amplification circuit 112, and the second output end of the operational amplifier U6B directly enters the ADC port of the main control circuit 120 after being divided by the resistor.

[0060] As shown in Figures 8-9 , the filter amplification circuit 112 is used for filter amplification processing, filtering out the carrier component of the triangular wave, and restoring the characteristics of the residual current in the main loop.

[0061] As shown in Figure 1 , it also includes a zero adjustment circuit, and the filter amplification circuit 112 is connected with the main control circuit 120 through the zero adjustment circuit. The main control circuit 120 collects the signal after zero adjustment and can directly calculate the effective value. The zero adjustment circuit is used to adjust the input of the smaller residual current channel. When the signal passes through the filter amplification circuit 112, the zero drift of the signal will be further amplified. By the zero adjustment circuit, the ADC input is within the zero error range, which can effectively improve the action accuracy of the product. Of course, the zero adjustment circuit can also not be set, and the filter amplification circuit 112 is directly connected with the main control circuit 120, which all belong to the protection scope of the present invention.

[0062] As shown in Figure 20 , the filter amplification circuit 112 includes a four-order filter circuit composed of two second-order Butterworth active filter circuits in series. The four-order filter circuit can better attenuate the carrier signal of excitation.

[0063] Further, the filter amplification circuit 112 further includes a zero adjustment circuit 113, and the two second-order Butterworth active filter circuits each include an operational amplifier. The operational amplifier of one of the second-order Butterworth active filter circuits is connected with the zero adjustment circuit 113. The zero adjustment circuit 113 is used to adjust the voltage of the noninverting input terminal of the operational amplifier of the second-order Butterworth active filter circuit.

[0064] Specifically, the operational amplifier of the second-order Butterworth active filter circuit connected with the zero adjustment circuit 113 is an operational amplifier U7B. According to the resistance voltage division principle, the zero adjustment circuit 113 includes resistors R60 and R63 connected between a voltage VCC and a ground terminal. The resistor R60 and the resistor R63 are connected in series, and the connection point between the resistor R60 and the resistor R63 is connected with the noninverting input terminal of the operational amplifier U7B. The resistance values of the resistor R60 and the resistor R63 of the zero adjustment circuit 113 can adjust the voltage of the noninverting input terminal of the operational amplifier U7B of the corresponding Butterworth active filter circuit, complete the output voltage adjustment of the operational amplifier U7B, and further be used for zero adjustment of the entire circuit.

[0065] Preferably, the main control circuit 120 performs FIR or Kalman digital filter processing on the second output terminal. The FIR filter can adopt an FIR filter, and the Kalman filter can adopt a Kalman filter. Of course, other digital filter methods can also be used, which all belong to the protection scope of the present invention.

[0066] AsFigure 11 As shown, the power supply monitoring circuit 122 of the embodiment is a hysteresis comparison circuit, which compares the power supply Vin obtained by dividing the voltage VCC with the voltage VDD, and outputs a low level to the main control circuit 120 when the power supply Vin is less than the voltage VDD, so that the main control circuit 120 cannot output the tripping signal, and outputs a high level to the main control circuit 120 when the power supply Vin is greater than the voltage VDD. The input power supply Vin of the comparator U3B is obtained by dividing the voltage VCC through the resistor R6 and the resistor R7, and the comparator U3B outputs a high level to the main control circuit 120 when the power supply Vin is greater than the voltage VDD, indicating that the voltage VCC is stable, so that the main control circuit 120 can open the residual current operating circuit breaker when the residual current size and the duration meet the operating conditions, otherwise the comparator U3B outputs a low level, and the main control circuit 120 cannot output the tripping signal to open the residual current operating circuit breaker.

[0067] As shown, during the power-on process, the comparator U3B outputs a high level only when the power supply Vin rises to V2, and the main control circuit 120 will not trigger the product operation before the high level is output; during the power-off process, the output of the comparator U3B is low when the power supply Vin drops to V1, and the main control circuit 120 will not trigger the product operation. Figure 12

[0068] Specifically, the power supply monitoring circuit 122 of the embodiment includes the comparator U3B, the output end of the comparator U3B is connected with the main control circuit 120, the reverse input end of the comparator U3B is connected with the voltage VDD, the same direction input end of the comparator U3B is connected with the node constituting the power supply Vin through the resistor R8, and the node constituting the power supply Vin is connected with the voltage VCC and the ground end through the resistor R6 and the resistor R7 respectively.

[0069] Further, the sampling circuit includes the excitation oscillation circuit 109, the integration circuit 110, the filter circuit amplification circuit 112 and the zero adjustment circuit 113 connected in sequence, and the excitation oscillation circuit 109 is connected with the excitation winding 107 of the residual current transformer.

[0070] ​The excitation oscillation circuit 109 generates RL self-excited oscillation based on the nonlinear magnetization curve characteristics of ferromagnetic materials. The excitation oscillation circuit 109 includes a square wave pulse voltage driving circuit and a comparator circuit. The secondary winding 107 of the residual current transformer, the square wave pulse voltage driving circuit, and the comparator form a cyclic self-excited oscillation. A square wave excitation voltage is applied across the secondary winding 107 of the residual current transformer. The integrator circuit 110 converts the excitation square wave signal generated by the excitation oscillation circuit 109 into a triangular wave signal. This triangular wave signal passes through the magnetic core 101 of the residual current transformer. The carrier signal of the residual current in the main circuit can reflect the variation characteristics of the fundamental residual current in the main circuit, including the magnitude and direction of the fundamental residual current in the main circuit. The filter amplifier circuit 112 is used for filtering and amplification processing, filtering out the carrier component of the triangular wave and restoring the characteristics of the residual current in the main circuit. The zero-adjustment circuit is used to adjust the input of the smaller residual current channel. When the signal passes through the filter amplifier circuit 112, the zero-point drift of the signal will be further amplified. By using the zero-adjustment circuit to keep the ADC input within the zero-point error range, the product's operating accuracy can be effectively improved. Of course, the zero-adjustment circuit can also be omitted, and the filter amplifier circuit 112 can be directly connected to the main control circuit 120, both of which fall within the protection scope of this invention.

[0071] It is understood that the sampling circuit can also use other existing technologies to collect leakage current signals, all of which fall within the protection scope of this invention. For example... Figures 13-14 Two embodiments of the excitation oscillation circuit 109 are shown, both of which fall within the protection scope of this invention.

[0072] like Figure 13 In the embodiment shown, the excitation oscillation circuit 109 includes a comparator U5B, an NPN transistor Q4, and a PNP transistor Q6. The collector of the NPN transistor Q4 is connected to the voltage VCC, and its emitter is connected to the emitter of the PNP transistor Q6. The collector of the PNP transistor Q6 is grounded. The connection point between the emitters of the NPN transistor Q4 and the PNP transistor Q6 is connected to one end of the excitation winding 107 on the residual current transformer. The inverting input terminal of the comparator U5B is connected to the reference voltage Vref via resistors R1 and R5. The connection point between resistors R1 and R5 is connected to the other end of the excitation winding 107. The bidirectional Zener diode D6 is connected in parallel across the two ends of the excitation winding 107. The positive input terminal of comparator U5B is connected to the reference voltage Vref via resistor R2. One end of the parallel connection of resistor R4 and capacitor C20 is connected to the output terminal of comparator U5B, and the other end is connected to the base of NPN transistor Q4 and PNP transistor Q6. The output terminal of comparator U5B is connected to the positive input terminal of comparator U5B via resistor R3 and outputs to the main control circuit 120.

[0073] like Figure 14In the illustrated embodiment, the excitation oscillation circuit 109 includes a comparator U5B. The output terminal of the comparator U5B is connected to one end of the excitation winding 107 on the residual current transformer. The inverting input terminal of the comparator U5B is connected to the reference voltage Vref via resistors R28, R35, and R40. The other end of the excitation winding 107 is connected between resistors R28 and R35. The inverting input terminal of the comparator U5B is connected to the reference voltage Vref via resistor R38. The output terminal of the comparator U5B is connected to the inverting input terminal via resistor R36 and outputs to the main control circuit 120. A bidirectional Zener diode D6 is connected in parallel across the two ends of the excitation winding 107. One end of capacitor C23 is grounded, and the other end is connected between resistors R35 and R40.

[0074] like Figure 1 As shown, the circuit also includes a residual current range selection circuit 117 and a delay range selection circuit 118. The residual current range selection circuit 117 and the delay range selection circuit 118 are used to set the action threshold for the magnitude of the residual current and the delay threshold for the duration, respectively. The residual current range selection circuit 117 outputs multiple different signals to the main control circuit 120 to set the action threshold for the magnitude of the residual current, and the delay range selection circuit 118 outputs multiple different signals to the main control circuit 120 to set the delay threshold for the residual current. When the magnitude of the residual current detected by the sampling circuit of the main control circuit 120 reaches the action threshold selected by the residual current range selection circuit 117, the main control circuit 120 starts timing. If the duration reaches the delay threshold selected by the delay range selection circuit 118, the main control circuit 120 trips the operating mechanism through the tripping circuit, thereby causing the residual current circuit breaker to open.

[0075] like Figure 18 As shown, the residual current range selection circuit 117 and the delay range selection circuit 118 are identical. Each circuit includes a rotary encoder switch SA1 and multiple resistors. By rotating the rotary encoder switch SA1, different resistors are connected. The main control circuit 120 then determines the range of the rotary encoder switch by detecting the high and low level changes of nodes Net1, Net2, and Net3. The second step-down circuit also provides a voltage VDD to the residual current range selection circuit 117 and the delay range selection circuit 118. This voltage VDD is connected to the main control circuit 120 through the multiple resistors with different resistance values ​​and the rotary encoder switch SA1.

[0076] The rotary encoding switch SA1 of the embodiment can generate five on states through the rotation of three pin contacts, and further can be set as five action threshold values of residual current size or delay position states. The residual current position selection circuit 117 of the embodiment includes 0.03A, 0.1A, 0.5A, 1A and 2A positions, and the delay position selection circuit 118 includes 0s, 0.1s, 0.3s, 0.5s and 2s positions. The main control circuit 120 judges the position of the rotary encoding switch by detecting the combination change of high and low levels of the Net1 node, the Net2 node and the Net3 node, and collects the residual current of the main circuit of the circuit breaker through the sampling circuit. When the residual current size is greater than the action threshold value and the duration reaches the delay threshold value, the main control circuit 120 sends a trip signal to disconnect the residual current operating circuit breaker.

[0077] Another embodiment of the residual current position selection circuit 117 and the delay position selection circuit 118 includes a rotary knob variable resistor, which outputs voltage signals with different voltage values to the main control circuit 120 by rotating the rotary knob variable resistor to adjust the resistance value. For example, one end of the rotary knob variable resistor of the residual current position selection circuit 117 is connected with a 3V power supply, and the other end is connected with the main control circuit 120. By rotating the rotary knob variable resistor to different positions to change the resistance value and then change the voltage value, 0.1V, 0.1V, 0.5V, 1V and 2V are respectively outputted to represent 0.03A, 0.1A, 0.5A, 1A and 2A positions.

[0078] As shown in Figure 1 , the residual current operating circuit breaker further includes a trip circuit. The trip circuit of the embodiment includes a trip control circuit 115 connected with the main control circuit 120, and a tripper 116 cooperating with the trip control circuit 115. The main control circuit 120 can drive the tripper 116 to act through the trip control circuit 115. When the tripper 116 acts, it can drive the operating mechanism to trip, and the operating mechanism can drive the residual current operating circuit breaker to disconnect. Figure 17

[0079] As shown in Figure 1 , the residual current operating circuit breaker further includes a test circuit. The test circuit of the embodiment includes a leakage test circuit 121, a residual current simulation circuit 114 and a test winding 108 wound on the magnetic core 101 of the residual current transformer. The leakage test circuit 121 is used to detect whether the test button is pressed. When the test button is pressed, the leakage test circuit 121 can make the residual current simulation circuit 114 simulate the residual current, simulate the generation of residual current fault, and test whether the residual current operating circuit breaker can disconnect.

[0080] As shown in Figure 1 ​As shown, the indicator circuit 119 includes at least two light-emitting elements as operation indication and fault indication of the circuit.

[0081] The host circuit 120 is an MCU. When the voltage VCC is stable and the test button is not pressed, the host circuit 120 judges whether the gear selected by the residual current gear selection circuit 117 is a large gear or a small gear, collects the leakage signal of the first output terminal or the second output terminal corresponding to the gear, and when the residual current of the output terminal reaches the action threshold set by the gear, the host circuit 120 starts timing and judges the delay threshold t selected by the delay gear selection circuit 118, and outputs a trip signal to the trip circuit when the leakage duration reaches the delay threshold t to disconnect the residual current action breaker. If the residual current gear selection circuit 117 selects the smallest gear (0.03A in this embodiment), the host circuit 120 skips the delay threshold judgment and directly outputs the trip signal.

[0082] As shown in the figure, Figure 16 The key detection circuit is connected with the host circuit 120 through the MCU_Test pin, Figure 15 The residual current simulation circuit 114 is also shown, which is connected with the host circuit 120 through the MCU_TestOut pin. When the host circuit 120 detects that Figure 16 The MCU_Test pin is high when the key S1 as the product trial button is pressed, and the MCU_TestOut pin can output a PWM signal with a duty cycle of 1:1 at this time. At this time, the switch tube Q5 will be intermittently opened, and the current will pass through the resistor R27, the test winding 108, and the resistor R39 to generate a simulated residual current in the test winding 108. After the simulated residual current is detected by the detection winding 107, the product is tripped.

[0083] The above is a further detailed description of the present invention in combination with a specific preferred embodiment, and cannot be regarded as a limitation of the specific implementation of the present invention. For ordinary skilled persons in the technical field to which the present invention belongs, without departing from the concept of the present invention, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A residual current circuit breaker comprising a power supply circuit, a sampling circuit and a control circuit (120), the power supply circuit supplying power to the sampling circuit and the control circuit (120), the control circuit (120) collecting residual current of a main circuit of the circuit breaker through the sampling circuit, characterized in that: The sampling circuit comprises an excitation oscillation circuit (109) connected with an excitation winding (107) of a residual current transformer and an integration circuit (110) for converting an excitation square wave signal generated by the excitation oscillation circuit (109) into a triangular wave signal and outputting the triangular wave signal through first and second output terminals respectively, the first output terminal being connected with the main control circuit (120) through a filter amplification circuit (112), and the second output terminal being directly connected with the main control circuit (120), the main control circuit (120) collecting residual currents of the filter amplification circuit (112) and / or the second output terminal respectively for controlling the residual current operated circuit breaker to be disconnected; the power supply circuit comprises a first voltage reduction circuit (104) for providing a voltage VCC for the sampling circuit and a second voltage reduction circuit (106) for providing a voltage VDD for the main control circuit (120), and the voltage VCC is greater than the voltage VDD; the residual current operated circuit breaker further comprises a power supply monitoring circuit (122) connected with the main control circuit (120), the power supply monitoring circuit (122) collecting the voltages VCC and VDD respectively for detecting whether the power supply VCC is stable and outputting a monitoring signal to the main control circuit, and the monitoring signal output by the power supply monitoring circuit (122) can make the main control circuit (120) unable to output a tripping signal.

2. The residual current operated circuit breaker according to claim 1, characterized in that: The residual current operated circuit breaker further comprises a residual current gear selection circuit (117) and a delay gear selection circuit (118) connected with the main control circuit (120) respectively, the residual current gear selection circuit (117) being used for outputting a plurality of different signals to the main control circuit (120) to set an action threshold of the residual current, and the delay gear selection circuit (118) being used for outputting a plurality of different signals to the main control circuit (120) to set a delay threshold of the residual current.

3. The residual current operated circuit breaker according to claim 1, characterized in that: The main control circuit (120) performs FIR or Kalman digital filter processing on the second output terminal.

4. The residual current operated circuit breaker according to claim 1, characterized in that: The integration circuit (110) comprises an operational amplifier U6B and a high-pass filter circuit and an RC integration circuit connected with input terminals of the operational amplifier U6B respectively, output terminals of the operational amplifier U6B being connected with the filter amplification circuit (112) and the main control circuit (120) respectively, the high-pass filter circuit being connected with the excitation oscillation circuit (109) and being used for filtering a duty cycle signal output by the excitation oscillation circuit (109), and the RC integration circuit being used for converting the filtered signal into a triangular wave signal, and the operational amplifier U6B being used as a voltage follower to increase driving capability of the triangular wave signal in the same direction.

5. The residual current circuit breaker according to claim 1, characterized in that: The excitation oscillation circuit (109) comprises a square wave pulse voltage driving circuit and a comparison circuit, the square wave pulse voltage driving circuit and the comparison circuit being connected with the excitation winding (107) of the residual current transformer for forming a cyclic self-excited oscillation.

6. The residual current circuit breaker according to claim 1, characterized in that: The filter amplification circuit (112) comprises a four-order filter circuit composed of two second-order Butterworth active filter circuits in series.

7. The residual current circuit breaker according to claim 6, characterized in that: A zero adjustment circuit is further connected to the filter-amplifier circuit (112).

8. The residual current circuit breaker according to claim 6, characterized in that: The two second-order Butterworth active filter circuits each comprise an operational amplifier, and the operational amplifier of one of the second-order Butterworth active filter circuits is connected to the zero adjustment circuit (113), which comprises a resistor R60 and a resistor R63 connected in series between a voltage VCC and a ground terminal, and a connection point between the resistor R60 and the resistor R63 is connected to a non-inverting input terminal of the operational amplifier of the second-order Butterworth active filter circuit.

9. The residual current circuit breaker according to claim 1, characterized in that: The excitation oscillation circuit (109) comprises a comparator U5B, an NPN transistor Q4, and a PNP transistor Q6, the collector of the NPN transistor Q4 is connected to a voltage VCC, the emitter of the NPN transistor Q4 is connected to the emitter of the PNP transistor Q6, the collector of the PNP transistor Q6 is connected to a ground terminal, a connection point between the emitter of the NPN transistor Q4 and the emitter of the PNP transistor Q6 is connected to one end of an excitation winding (107) of the residual current transformer, the reverse input terminal of the comparator U5B is connected to a reference voltage Vref via a resistor R1 and a resistor R5, a connection point between the resistor R1 and the resistor R5 is connected to the other end of the excitation winding (107), a bidirectional voltage stabilizing tube D6 is connected in parallel across the excitation winding (107), the non-inverting input terminal of the comparator U5B is connected to the reference voltage Vref via a resistor R2, one end of a resistor R4 and a capacitor C20 connected in parallel is connected to the output terminal of the comparator U5B, and the other end is connected to the base of the NPN transistor Q4 and the PNP transistor Q6, the output terminal of the comparator U5B is connected to the non-inverting input terminal of the comparator U5B via a resistor R3, and is output to the main control circuit (120).

10. The residual current circuit breaker according to claim 1, characterized in that: The excitation oscillation circuit (109) comprises a comparator U5B, a connection point between one end of an excitation winding (107) of the residual current transformer and the output terminal of the comparator U5B is connected to the other end of the excitation winding (107), the reverse input terminal of the comparator U5B is connected to a reference voltage Vref via a resistor R28, a resistor R35, and a resistor R40, the other end of the excitation winding (107) is connected between the resistor R28 and the resistor R35, the non-inverting input terminal of the comparator U5B is connected to the reference voltage Vref via a resistor R38, the output terminal of the comparator U5B is connected to the non-inverting input terminal of the comparator U5B via a resistor R36, and is output to the main control circuit (120), a bidirectional voltage stabilizing tube D6 is connected in parallel across the excitation winding (107), one end of a capacitor C23 is connected to a ground terminal, and the other end is connected between the resistor R35 and the resistor R40.

11. The residual current circuit breaker according to claim 1, characterized in that: The power supply monitoring circuit (122) comprises a hysteresis comparison circuit, which compares a power supply Vin obtained by voltage division of a voltage VCC with a voltage VDD, outputs a low level to the main control circuit (120) when the power supply Vin is less than the voltage VDD, so that the main control circuit (120) cannot output a trip signal, and outputs a high level to the main control circuit (120) when the power supply Vin is greater than the voltage VDD.

12. The residual current circuit breaker according to claim 1, characterized in that: The power supply monitoring circuit (122) comprises a comparator U3B, an output end of the comparator U3B is connected with the master control circuit (120), a reverse input end of the comparator U3B is connected with the voltage VDD, a same direction input end of the comparator U3B is connected with a node constituting a power supply Vin through a resistor R8, and the node constituting the power supply Vin is connected with the voltage VCC and the ground end through a resistor R6 and a resistor R7 respectively.

Images