Module for household electrical appliance power utilization protection

Abstract

The utility model discloses a module for electrical protection of household electrical appliances, which is used for being embedded into the front end of a power supply of the household electrical appliances, and specifically comprises a signal acquisition module consisting of a low-frequency signal acquisition circuit, a residual current signal acquisition circuit and a high-frequency signal acquisition circuit, the low-frequency mutual inductor is used for collecting phase line current low-frequency signal waveforms, the residual current mutual inductor is used for collecting residual current signal waveforms between a phase line and a zero line in real time, and the high-frequency mutual inductor is used for collecting phase line current high-frequency signal waveforms in real time. A low-frequency signal waveform, a residual current signal waveform and a high-frequency signal waveform are collected; the processor module judges whether short circuit and overload fault, electric leakage fault and fault arc occur, and controls the relay unit to timely disconnect the power supply circuit of the household appliance according to the fault judgment of the processor module, thereby effectively reducing the fire hazard of the household appliance.

Description

Technical Field

[0001] This utility model relates to the field of circuit safety protection technology, specifically a module for the protection of electricity used in household appliances. Background Technology

[0002] Since humans invented and began using electricity, it has brought both immense convenience and devastating dangers. It can damage appliances, cause fires, or result in electric shocks. If a device could ensure the safe use of electricity, many unnecessary losses could be avoided.

[0003] Most electrical protection systems for household appliances on the market are designed for short circuits, overloads, and leakage current. However, fault arcing caused by aging wiring, loose connections, and insulation peeling is often a major cause of fires and equipment damage. Fault arcing protection is a missing feature in the electrical protection systems for household appliances and needs to be improved. Utility Model Content

[0004] One technical problem this application aims to solve is to overcome the deficiencies of the above-mentioned related technologies and provide a module for the protection of household appliances' electricity usage, which incorporates short-circuit, overload, leakage, and arc fault protection functions to effectively reduce the occurrence of household appliance fires.

[0005] The technical solution adopted by this utility model to solve the technical problem is: a module for power protection of household appliances, which is embedded in the power supply front end of household appliances, specifically including:

[0006] A signal acquisition module consists of a low-frequency signal acquisition circuit, a residual current signal acquisition circuit, and a high-frequency signal acquisition circuit. It is connected to a low-frequency current transformer for acquiring the low-frequency signal waveform of the phase current, a residual current transformer for acquiring the residual current signal waveform between the phase and neutral lines in real time, and a high-frequency current transformer for acquiring the high-frequency signal waveform of the phase current in real time, so as to acquire the low-frequency signal waveform, the residual current signal waveform, and the high-frequency signal waveform.

[0007] A processor module, connected to the signal acquisition module, is used to determine whether a short circuit, overload fault, leakage fault, or fault arc has occurred based on the low-frequency signal waveform, residual current signal waveform, and high-frequency signal waveform.

[0008] A relay unit, connected to the processor module, is used to disconnect the power supply circuit of household appliances based on the fault diagnosis of the processor module.

[0009] Compared with related technologies, this utility model has the following advantages: The signal acquisition module integrates a low-frequency signal acquisition circuit, a residual current signal acquisition circuit, and a high-frequency signal acquisition circuit, which are used to acquire low-frequency signal waveforms, residual current signal waveforms, and high-frequency signal waveforms, so as to determine whether short circuit and overload faults, leakage faults, and fault arcs have occurred, respectively. Based on the fault judgment of the processor module, the relay unit is controlled to disconnect the power supply circuit of household appliances in a timely manner, so as to effectively reduce the occurrence of household appliance fires.

[0010] Preferably, the processor module uses a 32-bit embedded processor, specifically an STM32F103 chip. The STM32F103 chip is inexpensive, consumes little power, has a fast processing speed, and can promptly control the relay unit.

[0011] Preferably, the low-frequency transformer is a low-frequency transformer wound with a 2000:1 microcrystalline iron core; the low-frequency signal acquisition circuit includes a first resistor bias circuit composed of resistors R1 and R2, a first signal amplification circuit composed of resistors R3 and R4 for adjusting the amplification gain, and a first operational amplifier; one end of resistors R1 and R2 is connected to the CT1_1 lead of the low-frequency transformer, the other end of resistor R1 is connected to the power supply terminal, and the other end of resistor R2 is grounded; the first operational amplifier is connected to the power supply terminal, the non-inverting input terminal of the first operational amplifier is connected to the CT1_2 lead of the low-frequency transformer, and the I_LF output lead of the first signal amplification circuit is connected to the ADC pin of the processor chip.

[0012] Preferably, the residual current transformer is a residual current transformer wound with 500:1 nanocrystalline enameled wire; the residual current signal acquisition circuit includes a second resistor bias circuit composed of resistors R5 and R6, and a second signal amplification circuit composed of resistors R7 and R8 for adjusting the amplification gain and a second operational amplifier; one end of each of resistors R5 and R6 is connected to the CT2_1 lead of the residual current transformer, the other end of resistor R5 is connected to the power supply terminal, and the other end of resistor R6 is grounded; the non-inverting input terminal of the second operational amplifier is connected to the CT2_2 lead of the residual current transformer, and the I_G output lead of the first signal amplification circuit is connected to the ADC pin of the processor chip.

[0013] Preferably, the high-frequency transformer is a high-frequency transformer with a ferrite core wound with 100 turns of enameled wire; the high-frequency signal acquisition circuit includes a high-pass filter circuit, a rectifier bridge circuit, a voltage limiting circuit, a third signal amplification circuit and a voltage comparison circuit connected in sequence. The high-pass filter circuit is connected to the CT3_1 and CT3_2 leads of the high-frequency transformer, and the HF_PULSE pulse signal output lead at the output end of the voltage comparison circuit is connected to the input capture pin of the processor chip.

[0014] Furthermore, the high-pass filter circuit consists of capacitor C1, capacitor C2, resistor R9, and resistor R10. One plate of capacitor C1 is connected to the CT3_1 lead of the high-frequency transformer, and the other plate of capacitor C1 is connected to one end of resistor R9 and one input terminal of the rectifier bridge circuit. The other end of resistor R9 is grounded. One plate of capacitor C2 is connected to the CT3_2 lead of the high-frequency transformer, and the other plate of capacitor C2 is connected to one end of resistor R10 and the other input terminal of the rectifier bridge circuit. The other end of resistor R10 is grounded.

[0015] The voltage limiting circuit consists of diode D5 and resistor R11. The positive terminal of diode D5 and one end of resistor R11 are connected to the output terminal of the rectifier bridge circuit, and the negative terminal of diode D5 and the other end of resistor R11 are grounded.

[0016] The third signal amplification circuit consists of resistors R12 and R13 for adjusting the amplification gain and a third operational amplifier. The third operational amplifier is connected to the power supply terminal, the non-inverting input terminal of the third operational amplifier is connected to the voltage limiting circuit, and the output terminal of the third operational amplifier is connected to the voltage comparison circuit.

[0017] The voltage comparison circuit consists of resistors R14 and R15 for adjusting the comparison voltage threshold, a voltage comparator, and a pull-up resistor 16. The non-inverting input of the voltage comparator is connected to the output of the third operational amplifier. The voltage comparator is connected to the power supply and ground terminals respectively. The HF_PULSE pulse signal output lead of the voltage comparator is connected to the input capture pin of the processor chip.

[0018] Preferably, the first operational amplifier, the second operational amplifier, and the third operational amplifier all use the MCP6002. Attached Figure Description

[0019] Figure 1 This is a structural block diagram of the present invention.

[0020] Figure 2 This is a circuit diagram of the low-frequency signal acquisition circuit of this utility model.

[0021] Figure 3 This is a circuit diagram of the residual current signal acquisition circuit of this utility model.

[0022] Figure 4 This is a circuit diagram of the high-frequency signal acquisition circuit of this utility model. Detailed Implementation

[0023] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] This preferred embodiment is, for example Figure 1 The diagram shows a module for electrical protection of household appliances, designed to be embedded in the power supply front end of household appliances, specifically including:

[0026] A signal acquisition module consists of a low-frequency signal acquisition circuit, a residual current signal acquisition circuit, and a high-frequency signal acquisition circuit. It is connected to a low-frequency current transformer for acquiring the low-frequency signal waveform of the phase current, a residual current transformer for acquiring the residual current signal waveform between the phase and neutral lines in real time, and a high-frequency current transformer for acquiring the high-frequency signal waveform of the phase current in real time, so as to acquire the low-frequency signal waveform, the residual current signal waveform, and the high-frequency signal waveform.

[0027] A processor module, connected to the signal acquisition module, is used to determine whether a short circuit, overload fault, leakage fault, or fault arc has occurred based on the low-frequency signal waveform, residual current signal waveform, and high-frequency signal waveform.

[0028] A relay unit, connected to the processor module, is used to disconnect the power supply circuit of household appliances based on the fault diagnosis of the processor module; the relay unit adopts a 60A magnetic latching relay;

[0029] A sound and light alarm unit is connected to the processor module, as well as to the LED light and buzzer. It is used to drive the LED light and buzzer to sound an alarm when an overload fault or fault arc occurs, based on the fault judgment of the processor module.

[0030] A power supply module is connected to the processor module. The power supply module uses AC220V to 5V output and uses the AMS1117-3.3 chip to realize 5V to 3.3V conversion.

[0031] Preferably, the processor module uses a 32-bit embedded processor, which uses an STM32F103 chip.

[0032] Preferably, the low-frequency current transformer is a low-frequency current transformer wound with a 2000:1 microcrystalline iron core; the low-frequency signal acquisition circuit is as follows: Figure 2The circuit includes a first resistor biasing circuit consisting of resistors R1 and R2, a first signal amplification circuit consisting of resistors R3 and R4 for adjusting the amplification gain, and a first operational amplifier U1A. One end of resistors R1 and R2 is connected to the CT1_1 lead of the low-frequency transformer, the other end of resistor R1 is connected to the power supply, and the other end of resistor R2 is grounded. One end of resistors R3 and R4 is connected to the inverting input of the first operational amplifier U1A, the other end of resistor R3 is grounded, and the other end of resistor R4 is connected to the output of the first operational amplifier U1A. The first operational amplifier U1A is connected to the power supply, the non-inverting input of the first operational amplifier U1A is connected to the CT1_2 lead of the low-frequency transformer, and the I_LF output lead of the first signal amplification circuit is connected to the ADC pin of the processor chip.

[0033] Low-frequency signal waveforms are used to determine whether a short circuit or overload fault has occurred. Instantaneous disconnection is achieved when a short circuit occurs, and the disconnection time is calculated according to the inverse time formula (1) during an overload:

[0034]

[0035] In the formula, t is the overload protection tripping time, Q is the heat generated, R is the equivalent resistance of the electrical appliance, and I is the current.

[0036] To improve the speed of short-circuit breaking, the current derivative is used as the criterion. The sampling period for low-frequency signals is 6400 points per second, and one cycle of the operating frequency results in N = 128 sampling points. Every two points are used as a group of signals {i}. n i n+1}, calculate the derivative value of the current at point n, Dn=(i n+1 -i n ), continuously acquire N groups P{D1,D2,D3,...,DN}; determine whether Dn is greater than the threshold M, if so, record it as 1, otherwise record it as 0, calculate whether the result of P{D1,D2,D3,...,DN} is greater than N / 2, where N is the number of sampling points of the cycle, if so, it is judged as a short circuit fault, otherwise it is normal.

[0037] In overload fault diagnosis, the root mean square value I_LF of the low-frequency signal is calculated. rms Formula (2) is as follows:

[0038]

[0039] Substitute the calculation result into formula (1) to calculate the inverse time limit action time t, and the processor chip will trip according to the value of t.

[0040] Preferably, the residual current transformer is a residual current transformer wound with nanocrystalline 500:1 enameled wire; the residual current signal acquisition circuit is as follows: Figure 3The circuit includes a second resistor biasing circuit consisting of resistors R5 and R6, a second signal amplification circuit consisting of resistors R7 and R8 for adjusting the amplification gain, and a second operational amplifier U1B. One end of each resistor R5 and R6 is connected to the CT2_1 lead of the residual current transformer, the other end of resistor R5 is connected to the power supply, and the other end of resistor R6 is grounded. One end of each resistor R7 and R8 is connected to the inverting input of the second operational amplifier U1B, the other end of resistor R7 is grounded, and the other end of resistor R8 is connected to the output of the second operational amplifier U1B. The non-inverting input of the second operational amplifier U1B is connected to the CT2_2 lead of the residual current transformer. The I_G output lead of the first signal amplification circuit is connected to the ADC pin of the processor chip.

[0041] In residual current fault diagnosis, the root mean square (RMS) value of the residual current signal is calculated. The sampling rate is 6400 points per second, and the operating frequency is one cycle with N = 128 sampling points. The RMS value of the residual current signal I_G is then calculated. rms Formula (3) is as follows:

[0042]

[0043] In the formula, The square of the residual current signal.

[0044] Compare the calculation results I_G rms The threshold Q is set, and if the current exceeds the threshold Q, a residual current fault is considered to have occurred. The processor drives the relay to disconnect the circuit, where the threshold Q is 75% of the rated residual current value.

[0045] Preferably, the high-frequency transformer is a high-frequency transformer with a ferrite core wound with 100 turns of enameled wire; the high-frequency signal acquisition circuit includes a high-pass filter circuit, a rectifier bridge circuit, a voltage limiting circuit, a third signal amplification circuit and a voltage comparison circuit connected in sequence. The high-pass filter circuit is connected to the CT3_1 and CT3_2 leads of the high-frequency transformer, and the HF_PULSE pulse signal output lead at the output end of the voltage comparison circuit is connected to the input capture pin of the processor chip.

[0046] Furthermore, such as Figure 4 As shown, the high-pass filter circuit consists of capacitor C1, capacitor C2, resistor R9, and resistor R10. One plate of capacitor C1 is connected to the CT3_1 lead of the high-frequency transformer, and the other plate of capacitor C1 is connected to one end of resistor R9 and one input terminal of the rectifier bridge circuit. The other end of resistor R9 is grounded. One plate of capacitor C2 is connected to the CT3_2 lead of the high-frequency transformer, and the other plate of capacitor C2 is connected to one end of resistor R10 and the other input terminal of the rectifier bridge circuit. The other end of resistor R10 is grounded.

[0047] The rectifier bridge circuit is composed of four diodes D1, D2, D3 and D4 connected together. The negative terminal of diode D1 and the positive terminal of diode D2 are connected to the other plate of capacitor C1, the negative terminal of diode D3 and the positive terminal of diode D4 are connected to the other plate of capacitor C2, the positive terminals of diode D1 and D3 are grounded, and the negative terminals of diode D2 and D4 are connected to the output terminal.

[0048] The voltage limiting circuit consists of diode D5 and resistor R11. The positive terminal of diode D5 and one end of resistor R11 are connected to the output terminal of the rectifier bridge circuit, and the negative terminal of diode D5 and the other end of resistor R11 are grounded.

[0049] The third signal amplification circuit consists of resistors R12 and R13 for adjusting the amplification gain and a third operational amplifier U2A. One end of resistors R12 and R13 is connected to the inverting input terminal of the third operational amplifier U2A, the other end of resistor R12 is grounded, the other end of resistor R13 is connected to the output terminal of the third operational amplifier U2A, the third operational amplifier U2A is connected to the power supply terminal, the non-inverting input terminal of the third operational amplifier U2A is connected to the voltage limiting circuit, and the output terminal of the third operational amplifier U2A is connected to the voltage comparator circuit.

[0050] The voltage comparison circuit consists of resistors R14 and R15 for adjusting the comparison voltage threshold, voltage comparator U3A, and pull-up resistor 16. Voltage comparator U3A uses an LM393. One end of resistors R14 and R15 is connected to the inverting input of voltage comparator U3A, the other end of resistor R14 is connected to the power supply, and the other end of resistor R15 is grounded. One end of pull-up resistor 16 is connected to the power supply, and the other end of pull-up resistor 16 is connected to the output of voltage comparator U3A. The non-inverting input of voltage comparator U3A is connected to the output of the third operational amplifier U2A. Voltage comparator U3A is connected to both the power supply and ground. The HF_PULSE pulse signal output lead of voltage comparator U3A is connected to the input capture pin of the processor chip.

[0051] In the arc fault detection process, a timer calculates the number of high-frequency pulses every 20ms and stores them in a high-frequency pulse buffer. The current number of high-frequency pulses is compared with the number of high-frequency pulses of the previous two cycles. The absolute values ​​of each pair are subtracted to obtain three differences, namely D1, D2, and D3. D1, D2, and D3 are compared with the threshold P1 set by the program. If at least one of them is greater than the threshold, it can be determined that an arc fault has occurred. When an arc fault occurs, an audible and visual alarm is triggered. If the alarm lasts for more than 10 seconds, the circuit is disconnected. Otherwise, the calculation continues.

[0052] Preferably, the first operational amplifier U1A, the second operational amplifier U1B, and the third operational amplifier U2A all use MCP6002.

[0053] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A module for electrical protection of household appliances, characterized in that, A power supply front end for embedding into a household appliance, comprising: a signal acquisition module, which is composed of a low-frequency signal acquisition circuit, a residual current signal acquisition circuit and a high-frequency signal acquisition circuit, and is connected with a low-frequency transformer for acquiring a low-frequency signal waveform of a phase line current, a residual current transformer for acquiring a residual current signal waveform between the phase line and a zero line in real time, and a high-frequency transformer for acquiring a high-frequency signal waveform of the phase line current in real time, so as to acquire the low-frequency signal waveform, the residual current signal waveform and the high-frequency signal waveform; a processor module connected with the signal acquisition module, for judging whether a short circuit and overload fault, an electric leakage fault or a fault arc occurs according to the low-frequency signal waveform, the residual current signal waveform and the high-frequency signal waveform; a relay unit connected with the processor module, for disconnecting a power supply circuit of the household appliance according to the fault judgment of the processor module.

2. A module for electrical protection of household appliances according to claim 1, characterized in that, The processor module adopts a 32-bit embedded processor, and the 32-bit embedded processor adopts an STM32F103 chip.

3. A module for electrical protection of household appliances according to claim 2, characterized in that, The low-frequency transformer adopts a low-frequency transformer with an ultra-microcrystalline core and a winding ratio of 2000:1; the low-frequency signal acquisition circuit includes a first resistance biasing circuit composed of resistors R1 and R2, a first signal amplification circuit composed of resistors R3 and R4 and a first operational amplifier for adjusting an amplification gain multiple; one end of each of the resistors R1 and R2 is connected with a CT1_1 lead of the low-frequency transformer, the other end of the resistor R1 is connected with a power supply end, and the other end of the resistor R2 is grounded; the first operational amplifier is connected with the power supply end, a same direction input end of the first operational amplifier is connected with a CT1_2 lead of the low-frequency transformer, and an I_LF output lead of an output end of the first signal amplification circuit is connected with an ADC pin of a processor chip.

4. A module for electrical protection of household appliances according to claim 2, characterized in that, The residual current transformer adopts a residual current transformer with a nanocrystalline and a winding ratio of 500:1; the residual current signal acquisition circuit includes a second resistance biasing circuit composed of resistors R5 and R6, a second signal amplification circuit composed of resistors R7 and R8 and a second operational amplifier for adjusting an amplification gain multiple; one end of each of the resistors R5 and R6 is connected with a CT2_1 lead of the residual current transformer, the other end of the resistor R5 is connected with the power supply end, and the other end of the resistor R6 is grounded; a same direction input end of the second operational amplifier is connected with a CT2_2 lead of the residual current transformer, and an I_G output lead of an output end of the first signal amplification circuit is connected with the ADC pin of the processor chip.

5. A module for electrical protection of household appliances according to claim 2, characterized in that, The high-frequency transformer adopts a high-frequency transformer with a ferrite core and a winding ratio of 100 turns of enameled wire; the high-frequency signal acquisition circuit includes a high-pass filter circuit, a rectifier bridge circuit, a voltage limiting circuit, a third signal amplification circuit and a voltage comparison circuit connected in sequence, the high-pass filter circuit is connected with CT3_1 and CT3_2 leads of the high-frequency transformer, and an HF_PULSE pulse signal output lead of an output end of the voltage comparison circuit is connected with an input capture pin of the processor chip.

6. A module for electrical protection of household appliances according to claim 5, characterized in that, The high-pass filter circuit is composed of a capacitor C1, a capacitor C2, a resistor R9 and a resistor R10, one pole plate of the capacitor C1 is connected with a CT3_1 lead wire of the high-frequency transformer, another pole plate of the capacitor C1 is connected with one end of the resistor R9 and one input end of the rectifier bridge circuit, and the other end of the resistor R9 is grounded; one pole plate of the capacitor C2 is connected with a CT3_2 lead wire of the high-frequency transformer, another pole plate of the capacitor C2 is connected with one end of the resistor R10 and another input end of the rectifier bridge circuit, and the other end of the resistor R10 is grounded; The voltage limiting circuit is composed of a diode D5 and a resistor R11, the positive pole of the diode D5 is connected with one end of the resistor R11 and the output end of the rectifier bridge circuit, the negative pole of the diode D5 is grounded through the other end of the resistor R11; The third signal amplification circuit is composed of a resistor R12 and a resistor R13 for adjusting the amplification gain multiple and a third operational amplifier, the third operational amplifier is connected with a power supply end, the same direction input end of the third operational amplifier is connected with the voltage limiting circuit, and the output end of the third operational amplifier is connected with the voltage comparison circuit; The voltage comparison circuit is composed of a resistor R14 and a resistor R15 for adjusting the comparison voltage threshold, a voltage comparator and a pull-up resistor R16, the same direction input end of the voltage comparator is connected with the output end of the third operational amplifier, the voltage comparator is connected with a power supply end and a ground end respectively, and the HF_PULSE pulse signal output lead wire of the output end of the voltage comparator is connected with an input capture pin of the processor chip.

7. A module for electrical protection of household appliances according to claim 3, characterized in that, The first operational amplifier adopts MCP6002, and the second operational amplifier and the third operational amplifier adopt MCP6002.

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