A heating control method for an induction cooker based on gallium nitride and silicon carbide materials

Abstract

The present invention discloses a heating control method for an electromagnetic cooker based on gallium nitride and silicon carbide materials, which relates to the technical field of electromagnetic cooker control, including sampling a current signal; inputting the current signal into a gallium nitride driving circuit to generate a driving waveform; detecting the temperature distribution in the heating area of ​​the electromagnetic cooker and extracting temperature characteristic parameters; establishing a power control model based on the driving waveform and the temperature characteristic parameters and in combination with the conduction loss characteristics of the gallium nitride device; calculating the output power adjustment coefficient through the power control model, adjusting the duty cycle of the driving waveform according to the power adjustment coefficient, and obtaining a corrected driving signal; and controlling the output power of the gallium nitride power device using the corrected driving signal. An objective function is constructed based on the temperature distribution eccentricity, temperature control deviation, and heating uniformity coefficient, and an adaptive weight algorithm is used to dynamically adjust the weight coefficient, so as to achieve multi-objective optimization of temperature control, heating uniformity, and power loss.

Description

Technical Field

[0001] The invention relates to the technical field of induction cooker control, and in particular to a heating control method of an induction cooker based on gallium nitride and silicon carbide materials. Background Art

[0002] At present, silicon-based IGBT power devices and NTC thermistors are commonly used for induction cooker heating control. However, IGBT devices have large losses and poor switching characteristics when working at high frequencies, resulting in low system efficiency. At the same time, the temperature detection accuracy and response speed of NTC thermistors are limited, making it difficult to achieve precise temperature control, and it is impossible to obtain complete temperature distribution information in the heating area, affecting heating uniformity.

[0003] With the development of the third generation of semiconductor technology, gallium nitride power devices, due to their excellent high frequency performance and low switching loss, and silicon carbide temperature sensors with high precision and fast response, provide new technical solutions for improving the heating control performance of induction cookers. However, there is still a lack of mature control methods to give full play to the performance advantages of these new devices, especially in the control of temperature distribution uniformity and optimization of overall system energy efficiency. There is still much room for improvement. Summary of the invention

[0004] In view of the problems existing in the existing induction cooker heating control system in terms of temperature control accuracy, heating uniformity and energy utilization efficiency, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is how to achieve precise temperature control, uniform heating and high efficiency energy saving of an induction cooker through the coordinated application of gallium nitride power devices and silicon carbide temperature sensors.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, an embodiment of the present invention provides a heating control method for an induction cooker based on gallium nitride and silicon carbide materials, which includes sampling a current signal through a gallium nitride power device; inputting the current signal to a gallium nitride drive circuit, and the gallium nitride drive circuit generates a drive waveform based on the pulse width modulation principle; detecting the temperature distribution of the heating area of ​​the induction cooker through a silicon carbide temperature sensor array, filtering the temperature data, and extracting temperature characteristic parameters; establishing a power control model based on the drive waveform and the temperature characteristic parameters in combination with the conduction loss characteristics of the gallium nitride device; calculating the output power adjustment coefficient through the power control model, adjusting the duty cycle of the drive waveform according to the power adjustment coefficient, and obtaining a corrected drive signal; using the corrected drive signal to control the output power of the gallium nitride power device, drive the induction cooker coil to generate an electromagnetic field, and complete heating control.

[0007] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials described in the present invention, the gallium nitride driving circuit generates a driving waveform based on the pulse width modulation principle, including the following steps: collecting the DC bus voltage and performing A / D conversion, comparing the DC bus voltage with a preset reference voltage to obtain a voltage difference signal; using a proportional integral controller to compensate the voltage difference signal to generate a modulation wave signal; adjusting the triangular wave carrier frequency according to the amplitude of the modulation wave signal, and generating a triangular carrier through a triangular wave generator; inputting the triangular carrier and the modulation wave signal into a comparator for waveform comparison, and outputting a square wave signal according to the comparison result; adding a dead time to the square wave signal to form a complementary driving signal pair; converting the complementary driving signal pair into a driving waveform matching the gate characteristics of the gallium nitride power device through a level conversion circuit.

[0008] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials described in the present invention, wherein: extracting temperature characteristic parameters includes the following steps: sampling temperature data of the silicon carbide temperature sensor array to obtain a temperature data matrix; filtering the temperature data matrix using a median filtering algorithm to obtain effective temperature data; calculating the spatial gradient of the effective temperature data, and constructing a temperature gradient matrix through the temperature difference of adjacent sampling points; determining the thermal centroid coordinates of the effective temperature data based on a Gaussian weighted algorithm, the thermal centroid coordinates characterizing the position of the heating center; fitting the temperature gradient matrix, obtaining the temperature distribution surface equation, and calculating the peak point temperature value and the peak point position coordinates; generating a temperature characteristic parameter vector according to the thermal centroid coordinates, the peak point temperature value and the peak point position coordinates.

[0009] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials described in the present invention, the power control model is established including the following steps: obtaining the conduction characteristic parameters of the gallium nitride power device, the conduction characteristic parameters including the conduction resistance, the junction temperature coefficient, the junction temperature and the drain current; calculating the instantaneous conduction loss according to the conduction characteristic parameters, multiplying the duty cycle of the driving waveform by the instantaneous conduction loss to obtain the average conduction loss; constructing a temperature characteristic evaluation index, and establishing an objective function based on the temperature characteristic evaluation index and the average conduction loss; the temperature characteristic evaluation index includes the temperature distribution eccentricity, the temperature control deviation and the heating uniformity coefficient; using an adaptive weight algorithm to dynamically adjust the weight coefficient of the objective function; obtaining the optimal duty cycle equation based on the minimum value constraint of the objective function, determining the power adjustment coefficient according to the optimal duty cycle equation, and completing the establishment of the power control model.

[0010] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials of the present invention, the specific formula of the objective function is as follows: Among them, J is the objective function, They are temperature control weight coefficient, uniformity weight coefficient, and power loss weight coefficient. is the average conduction loss, d is the eccentricity of temperature distribution, is the heating uniformity coefficient, is the temperature control deviation.

[0011] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials described in the present invention, wherein: adjusting the duty cycle of the driving waveform according to the power adjustment coefficient includes the following steps: obtaining the reference duty cycle of the current driving waveform; calculating the adjustment amount of the target duty cycle according to the power adjustment coefficient; performing boundary value constraint processing on the adjusted target duty cycle; based on the target duty cycle after constraint processing, reconstructing the driving waveform according to the pulse width modulation principle, adjusting the high level duration of the waveform, and obtaining a driving waveform modulated by the duty cycle; converting the driving waveform modulated by the duty cycle into a driving signal matching the power device as a corrected driving signal for controlling the power output of the gallium nitride power device.

[0012] As a preferred solution of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials described in the present invention, the compensation processing of the voltage difference signal using a proportional-integral controller includes the following steps: using the voltage difference signal as the input end of the proportional-integral controller; multiplying the voltage difference signal by a preset proportional gain coefficient through the proportional link of the proportional-integral controller to obtain a linear proportional compensation amount; performing a time domain integration operation on the voltage difference signal through the integral link of the proportional-integral controller, and multiplying it by a preset integral gain coefficient to obtain an integral compensation amount; performing a linear superposition operation on the linear proportional compensation amount and the integral compensation amount to generate a modulated wave signal; and performing a limiting operation on the modulated wave signal.

[0013] The beneficial effects of the present invention are as follows: the present invention adopts gallium nitride power devices for current sampling, and its on-resistance changes little with junction temperature and has low switching loss, which can significantly improve the sampling accuracy and achieve stable high-frequency working performance. Through the silicon carbide temperature sensor array in conjunction with the Gaussian weighted algorithm and the median filter algorithm, the temperature distribution in the heating area can be accurately detected, and the temperature control accuracy and heating uniformity can be effectively improved. The objective function is constructed based on the temperature distribution eccentricity, temperature control deviation and heating uniformity coefficient, and the weight coefficient is dynamically adjusted using an adaptive weight algorithm, which can achieve multi-objective optimization of temperature control, heating uniformity and power loss. A dedicated isolation driver chip is used for level conversion, and accurate power regulation is achieved through dead time control and PWM modulation, while ensuring the switching reliability and control efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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 description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 The framework flow chart of the heating control method of the induction cooker based on gallium nitride and silicon carbide materials.

[0016] Figure 2 The invention provides a flow chart of pulse width modulation signal generation for a gallium nitride driving circuit of a heating control method for an induction cooker based on gallium nitride and silicon carbide materials.

[0017] Figure 3 Construct a flow chart for the power control model of the heating control method for an induction cooker based on GaN and SiC materials. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0021] Example 1, reference Figure 1~Figure 3 , which is the first embodiment of the present invention, and provides a heating control method for an induction cooker based on gallium nitride and silicon carbide materials. The framework flow chart is as follows Figure 1 As shown, including: S1: Current signal sampling through GaN power device.

[0022] Specifically, a sampling branch is set at the source end of the gallium nitride power device, and the sampling branch includes a current sensor; the output end of the current sensor is connected to the signal conditioning circuit, and the output end of the signal conditioning circuit is connected to the ADC sampling channel; the ADC sampling channel is controlled to sample the conditioned current signal to obtain a current sampling value. Among them, the current sensor adopts a Hall current sensor, and its output signal is amplified and filtered by the signal conditioning circuit. The signal conditioning circuit includes a second-order low-pass filter composed of an operational amplifier, with a cutoff frequency of 10kHz and a gain of 20dB. The ADC sampling frequency is set to 100kHz, and the sampling accuracy is 12 bits.

[0023] Preferably, GaN power devices have the characteristics of high switching frequency and low switching loss, and their on-resistance changes less with junction temperature. Therefore, using GaN power devices for current signal sampling can significantly improve sampling accuracy and reduce sampling errors. At the same time, GaN power devices have better switching characteristics and can maintain stable sampling performance under high-frequency working conditions, which is conducive to achieving precise power control of induction cookers.

[0024] S2: Input the current signal to the GaN driving circuit, which generates a driving waveform based on the pulse width modulation principle.

[0025] Specifically, the pulse width modulation signal generation flow chart of the GaN driving circuit is as follows: Figure 2 As shown, the following steps are included: S2.1: Collect the DC bus voltage and perform A / D conversion, compare the DC bus voltage with a preset reference voltage, and obtain a voltage difference signal.

[0026] S2.2: Use a proportional-integral controller to compensate the voltage difference signal and generate a modulated wave signal.

[0027] Specifically, a digital PI controller structure with feedforward and anti-saturation is adopted, and a table lookup method and a linear interpolation algorithm are used to implement discrete PI operations. The voltage difference signal is used as the input of the proportional-integral controller, and the signal represents the deviation between the actual DC bus voltage and the preset reference voltage; the voltage difference signal is converted into a preset proportional gain coefficient through the proportional link of the proportional-integral controller. Multiply them to get the linear proportional compensation, where the linear proportional compensation is used to achieve rapid adjustment of the transient characteristics of the system; through the integral link of the proportional integral controller, the voltage difference signal is integrated in the time domain and compared with the preset integral gain coefficient Multiply them to get the integral compensation, where the integral compensation is used to eliminate the steady-state error of the system; perform linear superposition operation on the linear proportional compensation and the integral compensation to generate a modulated wave signal, where the modulated wave signal satisfies the following mathematical expression: in, is the voltage difference signal, is the modulated wave signal, is the proportional gain coefficient, the value is 0.8, is the integral gain coefficient, and its value is 0.02.

[0028] Furthermore, the modulated wave signal is subjected to a limiting process, specifically including: when the amplitude of the modulated wave signal exceeds the upper threshold, it is clamped to the upper threshold; when the amplitude of the modulated wave signal is lower than the lower threshold, it is clamped to the lower threshold. The limiting process also includes an integrator anti-saturation process to prevent excessive accumulation of the integral amount. The upper threshold is set to 0.98, the lower threshold is set to 0.02, and the integrator anti-saturation is implemented using the backward Euler method.

[0029] S2.3: Adjust the triangular wave carrier frequency according to the amplitude of the modulation wave signal, and generate a triangular carrier through a triangular wave generator.

[0030] Specifically, a digital triangle wave generator is used, based on the table lookup method and digital integrator, with a frequency adjustment range of 10kHz to 50kHz, and the frequency is dynamically adjusted by looking up the pre-stored triangle wave waveform table and combining the digital differential algorithm. Among them, the frequency of the triangle carrier changes in direct proportion to the amplitude of the modulating wave signal.

[0031] S2.4: Input the triangular carrier and the modulated wave signals into the comparator for waveform comparison, and output a square wave signal according to the comparison result.

[0032] Specifically, when the amplitude of the triangular carrier wave is smaller than the amplitude of the modulating wave signal, a high level is output, otherwise a low level is output.

[0033] S2.5: Add dead time to the square wave signal to form a complementary drive signal pair.

[0034] Among them, the dead time is 200ns to 300ns.

[0035] S2.6: Convert the complementary driving signal pair into a driving waveform matching the gate characteristics of the GaN power device through a level conversion circuit.

[0036] The high level of the driving waveform is 6V to 6.5V, and the low level is -3V to -2V.

[0037] Preferably, through digital control and precise signal processing, efficient driving of gallium nitride power devices is achieved, with high signal accuracy and anti-interference ability, which is beneficial to improving the conversion efficiency and reliability of power electronic systems.

[0038] S3: Detect the temperature distribution of the heating area of ​​the induction cooker through the silicon carbide temperature sensor array, filter the temperature data, and extract the temperature characteristic parameters.

[0039] Specifically, the following steps are included: S3.1: Sample temperature data of an 8×8 silicon carbide temperature sensor array to obtain a temperature data matrix of 64 sampling points.

[0040] S3.2: Use the median filter algorithm to filter the temperature data matrix to obtain valid temperature data.

[0041] Specifically, 5 consecutive sampling values ​​are taken from each sampling point and sorted, and the middle value is selected as the effective temperature data. The filter window size is 5, and a simple insertion sort algorithm is used. The processing delay is less than 1ms. For abnormal values ​​(deviations from the previous effective value exceed 15°C), the previous effective value is used instead.

[0042] S3.3: Calculate the spatial gradient of the effective temperature data and construct an 8×8 temperature gradient matrix through the temperature difference of adjacent sampling points. The temperature gradient matrix represents the heating uniformity.

[0043] The spatial gradient calculation adopts the central difference method with a difference step of 1.5 cm, and the boundary points adopt forward or backward difference. The gradient calculation accuracy is 0.05℃ / cm.

[0044] S3.4: Determine the thermal centroid coordinates of the effective temperature data based on the Gaussian weighting algorithm, where the thermal centroid coordinates represent the location of the heating center.

[0045] Among them, the thermal centroid weight coefficient is set to 0.7, and the standard deviation of the Gaussian weight function is It is set to 1.8, the spatial resolution is 1.5 cm, the coordinate origin is set at the geometric center of the sensor array, and the positioning accuracy is ±0.8 cm.

[0046] S3.5: Fit the temperature gradient matrix, obtain the temperature distribution surface equation, and calculate the peak point temperature value and the peak point position coordinates.

[0047] The least square method is used to perform quadratic surface fitting on the temperature gradient matrix to obtain the temperature distribution surface equation.

[0048] S3.6: Generate a temperature characteristic parameter vector based on the thermal centroid coordinates, the peak point temperature value and the peak point position coordinates.

[0049] Preferably, the accurate characterization of the temperature distribution in the heating area of ​​the induction cooker is achieved through a high-precision temperature sensor array and a data processing algorithm, which has the following advantages: the median filter effectively suppresses random noise and improves the temperature measurement accuracy; the spatial gradient calculation intuitively reflects the heating uniformity; the thermal centroid coordinates and peak point coordinates analysis provide an accurate basis for heating control.

[0050] S4: Based on the driving waveform and temperature characteristic parameters, combined with the conduction loss characteristics of GaN devices, a power control model is established.

[0051] Specifically, the power control model construction flow chart is as follows: Figure 3 As shown, the following steps are included: S4.1: Obtain the on-state characteristic parameters of the GaN power device, including the on-state resistance R on , junction temperature coefficient , Junction temperature T j and the drain current I d .

[0052] S4.2: Calculate the instantaneous conduction loss according to the conduction characteristic parameters, multiply the duty cycle of the driving waveform by the instantaneous conduction loss, and obtain the average conduction loss.

[0053] Specifically, the instantaneous conduction loss The calculation formula is: Among them, I d is the drain current, T j is the junction temperature, is the junction temperature coefficient, R on is the on-resistance. This formula takes into account the change of on-resistance with junction temperature and more accurately reflects the instantaneous conduction loss in actual work.

[0054] S4.3: Construct a temperature characteristic evaluation index, and establish an objective function based on the temperature characteristic evaluation index and the average conduction loss.

[0055] Among them, the temperature characteristic evaluation indicators include temperature distribution eccentricity (Euclidean distance between thermal centroid coordinates and peak point position coordinates), temperature control deviation (difference between peak point temperature value and target temperature value) and heating uniformity coefficient. The specific formula of the objective function is as follows: Among them, J is the objective function, They are temperature control weight coefficient, uniformity weight coefficient, and power loss weight coefficient. is the average conduction loss, d is the eccentricity of temperature distribution, is the heating uniformity coefficient, is the temperature control deviation.

[0056] The heating uniformity coefficient is calculated by the temperature gradient matrix, and the process is as follows: obtain the temperature gradient matrix; for each element in the temperature gradient matrix, calculate the temperature difference between it and the adjacent element to obtain the temperature gradient matrix in the x and y directions; square the elements in the temperature gradient matrix in the x and y directions, add them, divide them by the total number of elements, and then take the square root to obtain the root mean square value of the temperature gradient; according to the root mean square value of the temperature gradient, the heating uniformity coefficient is calculated using the following formula : in, is the RMS value of the temperature gradient. When the RMS value of the temperature gradient is larger, the heating uniformity coefficient is smaller, indicating that the temperature distribution is more uneven; conversely, when the RMS value of the temperature gradient is smaller, the heating uniformity coefficient is larger, indicating that the temperature distribution is more uniform.

[0057] S4.4: Adopt adaptive weight algorithm to dynamically adjust the weight coefficient of objective function.

[0058] Among them, based on the temperature deviation Absolute value adjustment , according to the Euclidean distance d and the heating uniformity coefficient The product adjustment , based on the average conduction loss Ratio adjustment relative to rated power .

[0059] The reason why the corresponding weight coefficient is adjusted based on the absolute value of the temperature deviation is that the temperature deviation directly reflects the degree of deviation between the actual temperature and the target temperature. The larger the absolute value, the worse the temperature control effect. Increasing the corresponding weight can prompt the system to focus on adjusting the temperature to make it closer to the target value and improve the temperature control accuracy. The adjustment based on the product of the Euclidean distance and the heating uniformity coefficient is because the product of the two can comprehensively reflect the uniformity of the temperature distribution. A large product means poor temperature uniformity. Increasing the corresponding weight is conducive to guiding the system to improve the temperature distribution and ensure uniformity. The adjustment based on the ratio of the average conduction loss to the rated power is based on the fact that the ratio represents the level of power loss within the rated range. A high ratio means a large power loss. Adjusting the weight can promote the system to reduce losses and improve overall energy efficiency. Through such dynamic adjustments, the objective function can better adapt to different working conditions, balance various key indicators, and achieve better multi-objective optimization effects.

[0060] S4.5: Obtain an optimal duty cycle equation based on the minimum value constraint of the objective function, determine the power regulation coefficient according to the optimal duty cycle equation, and complete the establishment of the power control model.

[0061] Specifically, by taking the partial derivative of the objective function with respect to the duty cycle and setting it to 0, the optimal duty cycle equation can be obtained.

[0062] Furthermore, the determination of the power regulation coefficient includes the following steps: analyzing the key parameters and their influence weights in the optimal duty cycle equation; establishing the corresponding relationship between the duty cycle change and the power regulation demand; designing the calculation formula of the power regulation coefficient to ensure that it can accurately reflect the required power regulation amount; formulating the range constraint of the power regulation coefficient to ensure that the regulation process is smooth and controllable; and verifying the effectiveness of the power regulation coefficient through simulation and experiments.

[0063] S5: Calculate the output power regulation coefficient through the power control model, adjust the duty cycle of the driving waveform according to the power regulation coefficient, and obtain a corrected driving signal.

[0064] Specifically, the currently working PWM driving waveform is obtained in real time, and the reference duty cycle of the current driving waveform is obtained; then the power control model is called to calculate the power adjustment coefficient, and the power adjustment coefficient is multiplied by the reference duty cycle to obtain the adjustment amount of the target duty cycle; the boundary value constraint processing is performed on the adjusted target duty cycle, and the target duty cycle is limited to a preset maximum and minimum range to prevent the power output from exceeding the design limit of the induction cooker; based on the constrained target duty cycle, the driving waveform is reconstructed according to the pulse width modulation principle, and the high-level duration of the waveform is adjusted to obtain a driving waveform modulated by the duty cycle; a dedicated isolation driver chip is used to convert the driving waveform modulated by the duty cycle into a driving signal that matches the power device as a correction driving signal for controlling the power output of the gallium nitride power device.

[0065] S6: Use the corrected driving signal to control the output power of the GaN power device, drive the induction cooker coil to generate an electromagnetic field, and complete heating control.

[0066] Specifically, the corrected drive signal is first applied to the gates of the upper and lower gallium nitride power tubes in the half-bridge circuit at the same time, and the on and off of the power tubes are controlled by switching the gate voltage. During the high-frequency switching process, the power tube converts the DC bus voltage into a high-frequency AC voltage, and its effective value is determined by the duty cycle of the drive signal. The AC voltage is applied to both ends of the resonant circuit (composed of an induction cooker coil and a resonant capacitor) to generate an alternating current in the coil. The alternating current forms a changing magnetic field in the coil, and eddy currents are generated at the bottom of the cooker through the principle of electromagnetic induction. The eddy current loss is converted into heat energy to achieve heating. The system dynamically adjusts the duty cycle of the drive signal by real-time monitoring of the feedback of the temperature sensor array, thereby controlling the output power and keeping the temperature of the heating area near the set value. At the same time, various operating parameters are monitored to ensure that the system always works in a safe and reliable state.

[0067] In summary, the present invention uses gallium nitride power devices for current sampling, and its on-resistance changes little with junction temperature and has low switching loss, which can significantly improve the sampling accuracy and achieve stable high-frequency working performance. Through the silicon carbide temperature sensor array in conjunction with the Gaussian weighted algorithm and the median filter algorithm, the temperature distribution of the heating area can be accurately detected, and the temperature control accuracy and heating uniformity can be effectively improved. The objective function is constructed based on the temperature distribution eccentricity, temperature control deviation and heating uniformity coefficient, and the weight coefficient is dynamically adjusted using an adaptive weight algorithm, which can achieve multi-objective optimization of temperature control, heating uniformity and power loss. A dedicated isolation driver chip is used for level conversion, and accurate power regulation is achieved through dead time control and PWM modulation, while ensuring the switching reliability and control efficiency of the system.

[0068] Example 2, reference Figure 1~Figure 3 , which is the second embodiment of the present invention, provides a heating control method for an induction cooker based on gallium nitride and silicon carbide materials. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0069] To verify the feasibility and performance advantages of the invention, the research team conducted detailed simulation experiments and actual tests. In the construction of the experimental platform, the GS66508T gallium nitride power device was used, the operating frequency was set at 100kHz, and the DC bus voltage was 310V. The current sampling circuit uses the ACS723 Hall sensor, and the signal conditioning uses a second-order Butterworth low-pass filter built with the OPA2365 operational amplifier.

[0070] In the current sampling experiment, the oscilloscope monitoring found that the response time of the sampling signal was less than 1μs, the signal-to-noise ratio reached 52dB, and the sampling accuracy was better than 0.2%. Through comparative testing, compared with the traditional silicon-based MOSFET sampling solution, the sampling error of the gallium nitride device was reduced by 65%, and the temperature drift of the sampling accuracy did not exceed 0.1% / ℃ in the temperature range of -40℃ to 150℃.

[0071] The driving waveform generation experiment shows that under the dead time setting of 300ns, the rise time of the driving signal is 15ns, the fall time is 12ns, the high level of the driving waveform is stable at 6.2V, and the low level is -2.5V. Through FFT analysis, the harmonic distortion rate of the driving signal is less than 1.2%, which is much better than the traditional solution. In the temperature feature extraction experiment, the thermal centroid positioning accuracy reaches ±0.5cm, the temperature measurement range is 20℃ to 280℃, and the measurement error is less than ±1.5℃.

[0072] When the power control model is verified, under the condition of 2kW rated power, the dynamic response time of the system does not exceed 50ms, the temperature control accuracy is ±2°C, and the heating uniformity coefficient reaches 0.92. In order to more intuitively demonstrate the technical advantages of the present invention, the key performance indicators of the present invention are compared with those of the prior art as shown in Table 1.

[0073] Table 1 Comparison of performance indicators of the present invention and the prior art From the comparative data in Table 1, it can be seen that the present invention is superior to the existing technical solutions in key indicators such as current sampling response time, sampling accuracy, and temperature control accuracy. In particular, the performance is significantly improved in terms of heating uniformity and system dynamic response, which is mainly due to the coordinated optimization design of gallium nitride power devices and silicon carbide temperature sensor arrays.

[0074] In the long-term stability test, the system ran continuously for 100 hours, the power fluctuation did not exceed ±1%, and the temperature distribution eccentricity was always kept within 0.8cm. Through statistical analysis of energy consumption data, at a nominal power of 2kW, the overall efficiency of the system reached 94%, which is 5-6 percentage points higher than the traditional solution. The temperature dynamic response experiment showed that the time from room temperature to 200℃ was 90 seconds, the temperature overshoot did not exceed 5℃, and the steady-state error was controlled within the range of ±1.5℃, which fully verified the reliability and superiority of the control method.

[0075] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A heating control method for an induction cooker based on gallium nitride and silicon carbide materials, characterized in that: include, Current signal sampling through GaN power devices; Inputting the current signal to a gallium nitride driving circuit, wherein the gallium nitride driving circuit generates a driving waveform based on a pulse width modulation principle; The temperature distribution of the heating area of ​​the induction cooker is detected by a silicon carbide temperature sensor array, the temperature data is filtered and processed, and the temperature characteristic parameters are extracted; Based on the driving waveform and the temperature characteristic parameters, combined with the conduction loss characteristics of the gallium nitride device, a power control model is established; Calculating an output power adjustment coefficient through the power control model, and adjusting the duty cycle of the driving waveform according to the power adjustment coefficient to obtain a corrected driving signal; The corrected driving signal is used to control the output power of the gallium nitride power device, drive the induction cooker coil to generate an electromagnetic field, and complete heating control.

2. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 1, characterized in that: The gallium nitride driving circuit generates a driving waveform based on the pulse width modulation principle, comprising the following steps: Collecting the DC bus voltage and performing A / D conversion, comparing the DC bus voltage with a preset reference voltage to obtain a voltage difference signal; A proportional-integral controller is used to compensate the voltage difference signal to generate a modulated wave signal; The triangular wave carrier frequency is adjusted according to the amplitude of the modulated wave signal, and a triangular wave generator is used to generate a triangular carrier; Input the triangular carrier and the modulated wave signal into a comparator for waveform comparison, and output a square wave signal according to the comparison result; Adding dead time to the square wave signal to form a complementary drive signal pair; The complementary driving signal pair is converted into a driving waveform matching the gate characteristics of the gallium nitride power device through a level conversion circuit.

3. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 1, characterized in that: The extraction of temperature characteristic parameters comprises the following steps: Sampling temperature data of the silicon carbide temperature sensor array to obtain a temperature data matrix; Using a median filter algorithm to filter the temperature data matrix to obtain effective temperature data; Calculating the spatial gradient of the effective temperature data, and constructing a temperature gradient matrix through the temperature differences of adjacent sampling points; Determine the thermal centroid coordinates of the effective temperature data based on a Gaussian weighted algorithm, wherein the thermal centroid coordinates represent the location of the heating center; Fitting the temperature gradient matrix, obtaining the temperature distribution surface equation, and calculating the peak point temperature value and the peak point position coordinates; A temperature characteristic parameter vector is generated according to the thermal mass center coordinates, the peak point temperature value and the peak point position coordinates.

4. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 1, characterized in that: The power control model establishment comprises the following steps: Obtaining conduction characteristic parameters of the gallium nitride power device, wherein the conduction characteristic parameters include on-resistance, junction temperature coefficient, junction temperature, and drain current; Calculate the instantaneous conduction loss according to the conduction characteristic parameters, multiply the duty cycle of the driving waveform by the instantaneous conduction loss to obtain the average conduction loss; Constructing a temperature characteristic evaluation index, and establishing an objective function based on the temperature characteristic evaluation index and the average conduction loss; the temperature characteristic evaluation index includes temperature distribution eccentricity, temperature control deviation and heating uniformity coefficient; Adopting an adaptive weight algorithm to dynamically adjust the weight coefficient of the objective function; The optimal duty cycle equation is obtained based on the minimum constraint condition of the objective function, the power regulation coefficient is determined according to the optimal duty cycle equation, and the power control model is established.

5. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 4, characterized in that: The specific formula of the objective function is as follows: Among them, J is the objective function, They are temperature control weight coefficient, uniformity weight coefficient, and power loss weight coefficient. is the average conduction loss, d is the eccentricity of temperature distribution, is the heating uniformity coefficient, is the temperature control deviation.

6. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 1, characterized in that: Adjusting the duty cycle of the driving waveform according to the power adjustment coefficient comprises the following steps: Get the reference duty cycle of the current driving waveform; Calculating the adjustment amount of the target duty cycle according to the power regulation coefficient; performing boundary value constraint processing on the adjusted target duty cycle; Based on the target duty cycle after constraint processing, the driving waveform is reconstructed according to the pulse width modulation principle, and the high level duration of the waveform is adjusted to obtain the driving waveform modulated by the duty cycle; The duty cycle modulated driving waveform is converted into a driving signal matching the power device as a corrected driving signal for controlling the power output of the gallium nitride power device.

7. The heating control method of the induction cooker based on gallium nitride and silicon carbide materials according to claim 2, characterized in that: The use of a proportional-integral controller to perform compensation processing on the voltage difference signal comprises the following steps: The voltage difference signal is used as the input of the proportional-integral controller; The voltage difference signal is multiplied by a preset proportional gain coefficient through a proportional link of the proportional-integral controller to obtain a linear proportional compensation amount; Through the integral link of the proportional integral controller, the voltage difference signal is subjected to a time domain integral operation, and multiplied by a preset integral gain coefficient to obtain an integral compensation amount; The linear proportional compensation amount and the integral compensation amount are linearly superimposed to generate a modulated wave signal.

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