Electric heating hot water boiler

Abstract

The invention discloses an electric heating hot water boiler, belongs to the technical field of boilers, and solves the problems that the temperature of the electric heating hot water boiler is generally controlled through an alternating current contactor; however, the problems that the temperature precision is not high enough, safety accidents are caused by electric sparks generated by infirm wiring of the alternating current contactor, and the main contact is adhered firmly or does not act easily due to frequent action of the alternating current contactor exist. Comprising a hot water boiler, a heater, a temperature controller and a temperature control instrument, and the heater is arranged in the hot water boiler. The temperature control precision is high, the temperature of the electric heating hot water boiler can be basically kept consistent with the set temperature, as the output of the power regulator is contactless output, no electric spark phenomenon exists, the power regulator is safe and reliable, the service life of the power regulator is far longer than that of an alternating current contactor, and certain maintenance cost is reduced. According to the temperature control method of the electric heating hot water boiler, the reliability, stability and accuracy of the temperature of the electric heating hot water boiler are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers, and in particular to an electric heating hot water boiler. Background Art

[0002] An electric hot water boiler is a device that uses electricity as its power source, converting it into heat. It heats water through electric heating elements (such as heating tubes and rods), raising the water temperature and producing hot water or steam. They offer advantages such as being pollution-free, noise-free, stable, and easy to operate. They utilize an automatic control system that enables automatic start / stop and constant temperature control. They are widely used in residential, hotel, school, hospital, factory, and other locations for hot water supply, heating, and steam generation. However, their operating costs are relatively high and are significantly affected by electricity supply and prices.

[0003] Electric hot water boilers are typically temperature-controlled using an AC contactor. This type of temperature control has three drawbacks. First, the temperature accuracy is insufficient, preventing the desired temperature from being achieved. Second, during operation, if the AC contactor's wiring is not secure, sparks can easily occur, leading to unnecessary safety incidents. Third, AC contactors operate frequently and have a limited number of uses. Once this limit is exceeded, the main contacts may become stuck or fail to operate.

[0004] Therefore, an electric hot water boiler is proposed to solve or alleviate the above problems. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose an electric heating hot water boiler.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: An electrically heated hot water boiler comprises a hot water boiler, a heater, a temperature controller, and a temperature control instrument. The heater is arranged in the hot water boiler, and a temperature sensor is provided on the hot water boiler. The output end of the temperature sensor is coupled to the temperature control instrument, and the temperature control instrument is coupled to the heater through a power regulator.

[0007] Preferably, the heater, temperature controller, power regulator, and temperature control instrument are jointly coupled to a multi-stage detection system, which collects the heater operating current in real time, generates an orthogonal signal, performs correlation integral calculation with the synchronous reference signal, detects the total harmonic distortion rate, performs triple interlock verification, and hard-wires the power regulator control signal within 200 milliseconds after confirming the thyristor half-wave conduction fault.

[0008] Preferably, the multi-stage detection system includes a current sampling front-end module, a digital reference generation module, a correlation integral detection core module, a harmonic analysis auxiliary channel module, and a fault decision and output module; The current sampling front-end module is coupled to the heater, and is used to collect the heater current signal and generate an orthogonal signal. The digital reference generation module is connected to the zero-crossing detection terminal of the current sampling front-end module and the output terminal of the temperature controller. The digital reference generation module is used to generate a reference signal and a dynamic threshold. The input terminal of the correlation integral detection core module is connected to the output terminal of the current sampling front-end module and the output terminal of the digital reference generation module. The input terminal of the harmonic analysis auxiliary channel module is connected to the output terminal of the current sampling front-end module and the output terminal of the temperature sensor. The control terminal of the harmonic analysis auxiliary channel module is connected to the SPI interface of the digital reference generation module. The input terminal of the fault decision and output module is connected to the fault flag output terminal of the correlation integral detection core module and the data output terminal of the harmonic analysis auxiliary channel module. The output terminal of the fault decision and output module is connected to the input terminal of the temperature controller.

[0009] Preferably, the current sampling front-end module includes a zero-phase-shift current transformer, an INA188 instrumentation amplifier, a first OPA2188 operational amplifier, a second OPA2188 operational amplifier, a first RC filter network, and a second RC filter network; The zero-phase-shift current transformer is connected to the current line of the heater, the output end of the zero-phase-shift current transformer is connected to the input end of the INA188 instrumentation amplifier, the output end of the INA188 instrumentation amplifier is connected to the input ends of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, the first RC filter network and the second RC filter network are respectively connected to the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, and the output ends of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier respectively output signals to the relevant integral detection core module.

[0010] Preferably, the digital reference generation module includes an FPGA field programmable gate array, a DAC8562 analog-to-digital converter, a DAC8531 analog-to-digital converter, an LM393 voltage comparator, and an HCPL-3700 optocoupler; The FPGA field programmable gate array receives a signal from a current sampling front-end module. The SPI interface of the FPGA field programmable gate array is connected to a DAC8562 analog-to-digital converter. The output end of the FPGA field programmable gate array is connected to a DAC8531 analog-to-digital converter to output a PWM signal. The two output ends of the DAC8562 analog-to-digital converter output signals. The output end of the DAC8531 analog-to-digital converter outputs a dynamic threshold. The input end of the LM393 voltage comparator is connected to the output end of the HCPL-3700 optocoupler. The input end of the HCPL-3700 optocoupler is used to connect to the L line of the power grid. The output end of the LM393 voltage comparator is connected to the FPGA field programmable gate array.

[0011] Preferably, the correlation integral detection core module includes a first AD835AN analog multiplier, a second AD835AN analog multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a fifth OPA2188 operational amplifier, and an LT1016 comparator; The X input terminal of the first AD835AN analog multiplier receives the signal output by the first OPA2188 operational amplifier, the Y input terminal of the first AD835AN analog multiplier receives the signal output by the DAC8562 analog-to-digital converter, the output terminal of the first AD835AN analog multiplier is connected to the input terminal of the third OPA2188 operational amplifier, the output terminal of the third OPA2188 operational amplifier is connected to the input terminal of the fifth OPA2188 operational amplifier, the X input terminal of the second AD835AN analog multiplier receives the signal output by the second OPA2188 operational amplifier, and the second AD8 The Y input of the 35AN analog multiplier receives the signal output by the DAC8562 analog-to-digital converter, the output of the second AD835AN analog multiplier is connected to the input of the fourth OPA2188 operational amplifier, the output of the fourth OPA2188 operational amplifier is connected to the input of the fifth OPA2188 operational amplifier, the output of the fifth OPA2188 operational amplifier is connected to the input of the LT1016 comparator, the output of the DAC8531 analog-to-digital converter is connected to the input of the LT1016 comparator, and the output of the LT1016 comparator is connected to the fault decision and output module.

[0012] Preferably, the harmonic analysis auxiliary channel module includes a sixth OPA2188 operational amplifier, a seventh OPA2188 operational amplifier, an eighth OPA2188 operational amplifier, a ninth OPA2188 operational amplifier, an AD7606 analog-to-digital converter, and a first STM32F407VGT6 microcontroller; The output end of the temperature sensor is connected to the input end of the sixth OPA2188 operational amplifier, the output end of the sixth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, the input end of the seventh OPA2188 operational amplifier is connected to the output end of the first OPA2188 operational amplifier in the current sampling front-end module, the output end of the seventh OPA2188 operational amplifier is connected to the input end of the eighth OPA2188 operational amplifier, the output end of the eighth OPA2188 operational amplifier is connected to the input end of the ninth OPA2188 operational amplifier, the output end of the ninth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, the output end of the AD7606 analog-to-digital converter is connected to the FPGA field programmable gate array in the digital reference generation module, and the first STM32F407VGT6 microcontroller is connected to the SPI interface of the FPGA field programmable gate array in the digital reference generation module.

[0013] Preferably, the fault decision and output module includes a second STM32F407VGT6 microcontroller, the input end of the second STM32F407VGT6 microcontroller is respectively coupled to the output end of the LT1016 comparator in the relevant integral detection core module and the first STM32F407VGT6 microcontroller in the harmonic analysis auxiliary channel module, and the second STM32F407VGT6 microcontroller is coupled to the input and output ends of the temperature controller.

[0014] The present invention has the following beneficial effects: The temperature control method of the present invention has high precision, and can make the temperature of the electric hot water boiler basically consistent with the set temperature. Since the output of the power regulator is contactless output, there is no electric spark phenomenon, which is safe and reliable. The service life of the power regulator is much longer than that of the AC contactor, which reduces a certain amount of maintenance costs. In summary, the temperature control method of the electric hot water boiler greatly improves the reliability, stability and accuracy of the temperature of the electric hot water boiler.

[0015] Secondly, the multi-level detection system of the present invention monitors the heater current waveform characteristics in real time, utilizes a triple interlock verification mechanism, and combines dynamic threshold adaptive technology under low-load conditions to accurately capture the 50% power attenuation caused by the thyristor half-wave conduction and hard-wires the power regulator control signal within 200 milliseconds, thereby solving the problem of difficult-to-detect dangerous conditions due to hidden failure of power devices while the temperature controller still displays normal output. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural block diagram of the multi-stage detection system in the present invention.

[0018] In the figure, 1 is a hot water boiler; 2 is a heater; 3 is a temperature controller; 4 is a temperature controller; 5 is a power regulator; 6 is a current sampling front-end module; 7 is a digital reference generation module; 8 is a correlation integral detection core module; 9 is a harmonic analysis auxiliary channel module; 10 is a fault decision and output module. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0022] In the description of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when in use, or are the orientation or position relationship commonly understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] Furthermore, the terms “first,” “second,” “third,” etc., are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0025] An electric hot water boiler, such as Figure 1 As shown, it includes a hot water boiler 1, a heater 2, a temperature controller 3, and a temperature controller 4. The heater 2 is arranged in the hot water boiler 1, and a temperature sensor is provided on the hot water boiler 1. The output end of the temperature sensor is coupled to the temperature controller 4, and the temperature controller 4 is coupled to the heater 2 through the power regulator 5.

[0026] The heater 2 is inserted into the electrically heated hot water boiler 1 to heat the water in the hot water boiler 1. A temperature is set in the temperature controller 4. The temperature controller 4 outputs a signal to the power regulator 5 based on the feedback signal of the temperature sensor. The heater 2 adjusts the temperature based on the output signal of the power regulator 5, so that the temperature of the electrically heated hot water boiler 1 is kept consistent with the set temperature. Since the output of the power regulator 5 is contactless, there is no electric spark phenomenon, which is safe and reliable. The service life of the power regulator 5 is much longer than that of the AC contactor, which reduces certain maintenance costs.

[0027] like Figure 2 As shown, the heater 2, the temperature controller 3, the power regulator 5, and the temperature controller 4 are jointly coupled to a multi-stage detection system. The multi-stage detection system collects the working current of the heater 2 in real time, generates an orthogonal signal, performs correlation integral calculation with the synchronous reference signal, detects the total harmonic distortion rate, and performs triple interlock verification. After confirming the thyristor half-wave conduction fault, the control signal of the power regulator 5 is hard-wired and cut off within 200 milliseconds.

[0028] The multi-stage detection system includes a current sampling front-end module 6, a digital reference generation module 7, a correlation integral detection core module 8, a harmonic analysis auxiliary channel module 9, and a fault decision and output module 10; the current sampling front-end module 6 is coupled to the heater 2, the current sampling front-end module 6 is used to collect the current signal of the heater 2 and generate an orthogonal signal, the digital reference generation module 7 is connected to the zero-crossing detection end of the current sampling front-end module 6 and the output end of the temperature controller 4, the digital reference generation module 7 is used to generate a reference signal and a dynamic threshold, the input end of the correlation integral detection core module 8 is connected to the output end of the current sampling front-end module 6 and the output end of the digital reference generation module 7, the input end of the harmonic analysis auxiliary channel module 9 is connected to the output end of the current sampling front-end module 6 and the output end of the temperature sensor, the control end of the harmonic analysis auxiliary channel module 9 is connected to the SPI interface of the digital reference generation module 7, the input end of the fault decision and output module 10 is connected to the fault flag output end of the correlation integral detection core module 8 and the data output end of the harmonic analysis auxiliary channel module 9, and the output end of the fault decision and output module 10 is connected to the input end of the temperature controller 4.

[0029] The current sampling front-end module 6 includes a zero-phase-shift current transformer, an INA188 instrumentation amplifier, a first OPA2188 operational amplifier, a second OPA2188 operational amplifier, a first RC filter network, and a second RC filter network; the zero-phase-shift current transformer is connected to the current line of the heater 2, the output end of the zero-phase-shift current transformer is connected to the input end of the INA188 instrumentation amplifier, the output end of the INA188 instrumentation amplifier is connected to the input end of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, the first RC filter network and the second RC filter network are respectively connected to the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, and the output ends of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier respectively output signals to the relevant integral detection core module 8.

[0030] The digital reference generation module 7 includes an FPGA field programmable gate array, a DAC8562 analog-to-digital converter, a DAC8531 analog-to-digital converter, an LM393 voltage comparator, and an HCPL-3700 optocoupler; the FPGA field programmable gate array receives signals from the current sampling front-end module 6, the SPI interface of the FPGA field programmable gate array is connected to the DAC8562 analog-to-digital converter, the output end of the FPGA field programmable gate array is connected to the DAC8531 analog-to-digital converter to output a PWM signal, the two output ends of the DAC8562 analog-to-digital converter output signals, the output end of the DAC8531 analog-to-digital converter outputs a dynamic threshold, the input end of the LM393 voltage comparator is connected to the output end of the HCPL-3700 optocoupler, the input end of the HCPL-3700 optocoupler is used to connect to the grid L line, and the output end of the LM393 voltage comparator is connected to the FPGA field programmable gate array.

[0031] The correlation integral detection core module 8 includes a first AD835AN analog multiplier, a second AD835AN analog multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a fifth OPA2188 operational amplifier, and an LT1016 comparator; the X input of the first AD835AN analog multiplier receives the signal output by the first OPA2188 operational amplifier, the Y input of the first AD835AN analog multiplier receives the signal output by the DAC8562 analog-to-digital converter, the output of the first AD835AN analog multiplier is connected to the input of the third OPA2188 operational amplifier, and the output of the third OPA2188 operational amplifier is connected to the input of the fifth OPA2188 operational amplifier. The X input terminal of the second AD835AN analog multiplier receives the output signal of the second OPA2188 operational amplifier, the Y input terminal of the second AD835AN analog multiplier receives the output signal of the DAC8562 analog-to-digital converter, the output terminal of the second AD835AN analog multiplier is connected to the input terminal of the fourth OPA2188 operational amplifier, the output terminal of the fourth OPA2188 operational amplifier is connected to the input terminal of the fifth OPA2188 operational amplifier, the output terminal of the fifth OPA2188 operational amplifier is connected to the input terminal of the LT1016 comparator, the output terminal of the DAC8531 analog-to-digital converter is connected to the input terminal of the LT1016 comparator, and the output terminal of the LT1016 comparator is connected to the fault decision and output module 10.

[0032] The harmonic analysis auxiliary channel module 9 includes a sixth OPA2188 operational amplifier, a seventh OPA2188 operational amplifier, an eighth OPA2188 operational amplifier, a ninth OPA2188 operational amplifier, an AD7606 analog-to-digital converter, and a first STM32F407VGT6 microcontroller; the output end of the temperature sensor is connected to the input end of the sixth OPA2188 operational amplifier, the output end of the sixth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, and the input end of the seventh OPA2188 operational amplifier is connected to the first OPA2188 operational amplifier in the current sampling front-end module 6. The output end of the seventh OPA2188 operational amplifier is connected to the input end of the eighth OPA2188 operational amplifier, the output end of the eighth OPA2188 operational amplifier is connected to the input end of the ninth OPA2188 operational amplifier, the output end of the ninth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, the output end of the AD7606 analog-to-digital converter is connected to the FPGA field programmable gate array in the digital reference generation module 7, and the first STM32F407VGT6 microcontroller is connected to the SPI interface of the FPGA field programmable gate array in the digital reference generation module 7.

[0033] The fault decision and output module 10 includes a second STM32F407VGT6 microcontroller, the input end of the second STM32F407VGT6 microcontroller is respectively coupled to the output end of the LT1016 comparator in the relevant integral detection core module 8 and the first STM32F407VGT6 microcontroller in the harmonic analysis auxiliary channel module 9, and the second STM32F407VGT6 microcontroller is coupled to the input and output ends of the temperature controller 4.

[0034] When the multi-level detection system is working, The current sampling front-end module 6 collects the current signal of the heater 2 and generates two orthogonal signals with a phase difference of ninety degrees; A sine reference signal and a cosine reference signal synchronized with the power grid are generated by a digital reference generation module 7. A power grid phase reference point is determined based on zero-crossing detection. The reference point is the zero-crossing moment plus a time offset of one-quarter of the power grid cycle. An orthogonal reference signal is generated, wherein the sine reference signal is a sine function of the power grid frequency, and the cosine reference signal is a cosine function of the power grid frequency. The phase difference between the two is constant at 90 degrees, and the sampling interval is 100 microseconds. During automatic phase calibration, when the maximum current value is greater than 10% of the rated current, calibration is performed: the phase angle difference between the sum of the main orthogonal signals and the sum of the secondary orthogonal signals is calculated, and the phase adjustment amount is calculated using a proportional-integral control algorithm with a proportional coefficient of 0.05 and an integral coefficient of 0.001. The phase offset of the reference signal is updated based on the phase adjustment amount; The correlation integral detection core module 8 calculates the correlation integral value of the current signal and the reference signal, multiplies the main orthogonal signal by the sine reference signal, and multiplies the secondary orthogonal signal by the cosine reference signal. The sum of the two multiplication results is subjected to a weighted average integral using a Hamming window function, and the integration window length is 2,000 sampling points. The total harmonic distortion rate is calculated by the harmonic analysis auxiliary channel module 9. The total harmonic distortion rate is calculated by extracting the fundamental component from the original current signal using an infinite impulse response bandpass filter, subtracting the fundamental component from the original current signal to obtain the harmonic component, and calculating the total harmonic distortion rate by taking the square root of the ratio of the energy of the harmonic component to the energy of the fundamental component and multiplying it by 100%. The calculation data length is 4,096 sampling points. The fault decision and output module 10 performs triple interlock verification, which includes: primary verification, judging whether the relevant integral value is less than the dynamic threshold; secondary verification, judging whether the total harmonic distortion rate is greater than 5%; tertiary verification, calculating the waveform symmetry index, which is calculated by the ratio of the absolute difference between the sum of the current in the first half cycle and the sum of the current in the second half cycle to the maximum current value, and judging whether the index is less than 0.95; fault confirmation, triggering the protection action when the state in which the primary verification, secondary verification and tertiary verification results are simultaneously met for five consecutive grid cycles; Among them, the dynamic threshold is calculated as the dynamic threshold is composed of the linear superposition of three parts: the fixed proportion rated value, the harmonic distortion rate weighting term and the temperature compensation term, where the rated value coefficient is 0.5, the harmonic distortion rate coefficient is 0.15, and the temperature compensation coefficient is 0.002 per degree Celsius, and the value range of the dynamic threshold is limited to between 0.3 times and 0.7 times the rated value.

[0035] The multi-stage detection system's identification of a half-wave conduction fault in hot water boiler 1 begins with the real-time capture of heater 2's operating current by the current sampling front-end module 6. This module collects the current signal contactlessly through a zero-phase-shift current transformer. After precise amplification by an instrumentation amplifier, a dual-channel bandpass filter separates the I_main and I_quad signals, each with strictly orthogonal phases. When the thyristor conducts for only half a cycle due to aging or drive anomalies, the current waveform will exhibit significant asymmetric distortion. At this point, the quadrature signal output by the current sampling front-end module 6 will carry abnormal DC components and harmonic characteristics.

[0036] At the same time, the digital reference generation module 7 locks the grid phase reference point through a high-precision zero-crossing detection circuit, and the digital direct synthesizer in the FPGA generates Ref_sin and Ref_cos signals that are strictly synchronized with the grid, with a phase resolution of 0.1 degrees. The module also calculates V_th in real time through a dynamic threshold algorithm. This threshold combines the rated value ratio, harmonic distortion rate weighting term and ambient temperature compensation term to ensure adaptability under different operating conditions.

[0037] The correlation integral detection core module 8 receives the I_main / I_quad signals from the front end and the Ref_sin / Ref_cos signals of the digital reference, and performs four-quadrant multiplication operations through an analog multiplier. The main channel current is multiplied by the sine reference signal, and the quadrature channel current is multiplied by the cosine reference signal. The two product results are input into the integrator composed of precision operational amplifiers. The Hamming window function is applied for weighted accumulation within the 200 millisecond integration window, and finally the correlation integral value V_corr is synthesized by the adder.

[0038] When a half-wave conduction fault occurs, the symmetry of the current waveform is destroyed, causing the V_corr value to drop sharply from 0.5 times the rated value in the normal state. This abnormal change is captured in real time by the high-speed comparator. When V_corr falls below the dynamic threshold V_th, the primary fault flag FLAG1 is generated. The harmonic analysis auxiliary channel module 9 synchronously processes the original current signal, filters out the fundamental component through a 6th-order high-pass filter, and uses the FPGA to perform a 1024-point fast Fourier transform to calculate the energy of each harmonic. The total harmonic distortion (THD) is calculated based on the square root of the ratio of the total harmonic component energy to the fundamental energy multiplied by 100%. A half-wave fault will cause significant odd harmonics, causing the THD value to jump from the normal state. When the THD exceeds the threshold, a secondary fault flag is generated.

[0039] After receiving the signal, the fault decision and output module 10 starts the third-level waveform symmetry verification, divides the current data of ten consecutive power frequency cycles into five cycle segments in the front and back, calculates the ratio of the absolute difference between the total current of the two segments and the maximum current value in the cycle, and derives the symmetry index based on this. When the index is lower than 0.95, a waveform asymmetry signal is generated.

[0040] The triple verification results are fed into the fault-tolerant decision logic, and a half-wave fault is finally confirmed only when the conditions of abnormal integral, excessive harmonics, and waveform asymmetry are simultaneously met for five complete grid cycles.

[0041] The module immediately drives the temperature controller 4 through the microcontroller to cut off the control signal of the power regulator 5, ensuring that even when the temperature controller 4 displays a normal output signal, it can still reliably identify the hidden half-wave fault in which the power drops below 50% of the nominal value, fundamentally eliminating the risk of boiler heating capacity degradation and temperature out of control caused by local failure of the thyristor.

[0042] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An electric hot water boiler, characterized in that: The invention comprises a hot water boiler (1), a heater (2), a temperature controller (3), and a temperature controller (4), wherein the heater (2) is arranged in the hot water boiler (1), and a temperature sensor is arranged on the hot water boiler (1), and an output end of the temperature sensor is coupled to the temperature controller (4), and the temperature controller (4) is coupled to the heater (2) via a power regulator (5).

2. An electric hot water boiler according to claim 1, characterized in that: The heater (2), the temperature controller (3), the power regulator (5), and the temperature controller (4) are coupled together with a multi-stage detection system. The multi-stage detection system collects the working current of the heater (2) in real time, generates an orthogonal signal, performs correlation integral calculation with a synchronous reference signal, detects the total harmonic distortion rate, performs triple interlock verification, and hard-wires the power regulator (5) control signal within 200 milliseconds after confirming a thyristor half-wave conduction fault.

3. An electric hot water boiler according to claim 2, characterized in that: The multi-stage detection system includes a current sampling front-end module (6), a digital reference generation module (7), a correlation integral detection core module (8), a harmonic analysis auxiliary channel module (9), and a fault decision and output module (10); The current sampling front-end module (6) is coupled to the heater (2), and the current sampling front-end module (6) is used to collect the current signal of the heater (2) and generate an orthogonal signal. The digital reference generation module (7) is connected to the zero-crossing detection end of the current sampling front-end module (6) and the output end of the temperature controller (4). The digital reference generation module (7) is used to generate a reference signal and a dynamic threshold. The input end of the correlation integral detection core module (8) is connected to the output end of the current sampling front-end module (6) and the output end of the digital reference generation module (7). The input end of the harmonic analysis auxiliary channel module (9) is connected to the output end of the current sampling front-end module (6) and the output end of the temperature sensor. The control end of the harmonic analysis auxiliary channel module (9) is connected to the SPI interface of the digital reference generation module (7). The input end of the fault decision and output module (10) is connected to the fault flag output end of the correlation integral detection core module (8) and the data output end of the harmonic analysis auxiliary channel module (9). The output end of the fault decision and output module (10) is connected to the input end of the temperature controller (4).

4. An electric hot water boiler according to claim 2, characterized in that: The current sampling front-end module (6) includes a zero-phase-shift current transformer, an INA188 instrumentation amplifier, a first OPA2188 operational amplifier, a second OPA2188 operational amplifier, a first RC filter network, and a second RC filter network; The zero-phase-shift current transformer is connected to the current line of the heater (2), the output end of the zero-phase-shift current transformer is connected to the input end of the INA188 instrument amplifier, the output end of the INA188 instrument amplifier is connected to the input ends of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, the first RC filter network and the second RC filter network are respectively connected to the first OPA2188 operational amplifier and the second OPA2188 operational amplifier, and the output ends of the first OPA2188 operational amplifier and the second OPA2188 operational amplifier respectively output signals to the relevant integral detection core module (8).

5. The electric hot water boiler according to claim 2, characterized in that: The digital reference generation module (7) includes an FPGA field programmable gate array, a DAC8562 analog-to-digital converter, a DAC8531 analog-to-digital converter, an LM393 voltage comparator, and an HCPL-3700 optical coupler; The FPGA field programmable gate array receives a signal from a current sampling front-end module (6); the SPI interface of the FPGA field programmable gate array is connected to a DAC8562 analog-to-digital converter; the output end of the FPGA field programmable gate array is connected to a DAC8531 analog-to-digital converter to output a PWM signal; two output ends of the DAC8562 analog-to-digital converter output signals; the output end of the DAC8531 analog-to-digital converter outputs a dynamic threshold; the input end of the LM393 voltage comparator is connected to the output end of the HCPL-3700 optocoupler; the input end of the HCPL-3700 optocoupler is used to connect to the L line of the power grid; and the output end of the LM393 voltage comparator is connected to the FPGA field programmable gate array.

6. The electric hot water boiler according to claim 2, characterized in that: The correlation integral detection core module (8) includes a first AD835AN analog multiplier, a second AD835AN analog multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a fifth OPA2188 operational amplifier, and an LT1016 comparator; The X input terminal of the first AD835AN analog multiplier receives the signal output by the first OPA2188 operational amplifier, the Y input terminal of the first AD835AN analog multiplier receives the signal output by the DAC8562 analog-to-digital converter, the output terminal of the first AD835AN analog multiplier is connected to the input terminal of the third OPA2188 operational amplifier, the output terminal of the third OPA2188 operational amplifier is connected to the input terminal of the fifth OPA2188 operational amplifier, the X input terminal of the second AD835AN analog multiplier receives the signal output by the second OPA2188 operational amplifier, and the second AD835 The Y input of the AN analog multiplier receives the signal output by the DAC8562 analog-to-digital converter, the output of the second AD835AN analog multiplier is connected to the input of the fourth OPA2188 operational amplifier, the output of the fourth OPA2188 operational amplifier is connected to the input of the fifth OPA2188 operational amplifier, the output of the fifth OPA2188 operational amplifier is connected to the input of the LT1016 comparator, the output of the DAC8531 analog-to-digital converter is connected to the input of the LT1016 comparator, and the output of the LT1016 comparator is connected to the fault decision and output module (10).

7. The electric hot water boiler according to claim 2, characterized in that: The harmonic analysis auxiliary channel module (9) includes a sixth OPA2188 operational amplifier, a seventh OPA2188 operational amplifier, an eighth OPA2188 operational amplifier, a ninth OPA2188 operational amplifier, an AD7606 analog-to-digital converter, and a first STM32F407VGT6 microcontroller; The output end of the temperature sensor is connected to the input end of the sixth OPA2188 operational amplifier, the output end of the sixth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, the input end of the seventh OPA2188 operational amplifier is connected to the output end of the first OPA2188 operational amplifier in the current sampling front-end module (6), the output end of the seventh OPA2188 operational amplifier is connected to the input end of the eighth OPA2188 operational amplifier, the output end of the eighth OPA2188 operational amplifier is connected to the input end of the ninth OPA2188 operational amplifier, the output end of the ninth OPA2188 operational amplifier is connected to the input end of the AD7606 analog-to-digital converter, the output end of the AD7606 analog-to-digital converter is connected to the FPGA field programmable gate array in the digital reference generation module (7), and the first STM32F407VGT6 microcontroller is connected to the SPI interface of the FPGA field programmable gate array in the digital reference generation module (7).

8. The electric hot water boiler according to claim 2, characterized in that: The fault decision and output module (10) includes a second STM32F407VGT6 microcontroller, the input end of the second STM32F407VGT6 microcontroller is respectively coupled to the output end of the LT1016 comparator in the relevant integral detection core module (8) and the first STM32F407VGT6 microcontroller in the harmonic analysis auxiliary channel module (9), and the second STM32F407VGT6 microcontroller is coupled to the input and output ends of the temperature controller (4).

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