Wireless power supply device and heating control method thereof

Abstract

The application discloses a wireless power supply device and a heating control method thereof. The device comprises an inverter circuit and a resonance circuit. The input end of the inverter circuit is connected with a direct current, and the output end of the inverter circuit is connected with the resonance circuit. The resonance circuit comprises a resonance coil. The method comprises the following steps: obtaining a temperature difference value between an actual temperature and a target temperature of the resonance coil; obtaining a switching frequency of the inverter circuit according to the temperature difference value; and controlling the inverter circuit according to the switching frequency, so that the resonance circuit resonantly heats a load. According to the heating control method, the switching frequency of the inverter circuit is adjusted according to the actual temperature of the resonance coil, so that the output power of the resonance circuit is controlled, and the temperature of the resonantly heated load is automatically controlled.

Description

Technical Field

[0001] This invention relates to the field of heating control technology, and in particular to a heating control method for a wireless power supply device, a computer-readable storage medium, and a wireless power supply device. Background Technology

[0002] The diversity of wireless loads is placing increasingly higher demands on the performance of wireless power supply devices, with wireless charging and wireless heating being two commonly used functions. Currently, many products on the market can only provide one function, either wireless charging or wireless heating, or they can provide both functions simultaneously, but the compatibility between the two is poor, resulting in a less than ideal wireless experience for consumers. Consumers may even need to purchase multiple wireless power supply devices to meet the power needs of different wireless loads. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the first objective of this invention is to provide a heating control method for a wireless power supply device, which adjusts the switching frequency of the inverter circuit according to the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby achieving automatic control of the temperature for resonant heating of the load.

[0004] A second objective of this invention is to provide a computer-readable storage medium.

[0005] The third objective of this invention is to provide a wireless power supply device.

[0006] The fourth objective of this invention is to provide a wireless power supply device.

[0007] To achieve the above objectives, a first aspect of the present invention provides a heating control method for a wireless power supply device. The device includes an inverter circuit and a resonant circuit. The input terminal of the inverter circuit is connected to a direct current source, and the output terminal of the inverter circuit is connected to the resonant circuit. The resonant circuit includes a resonant coil. The method includes: obtaining the temperature difference between the actual temperature of the resonant coil and the target temperature; obtaining the switching frequency of the inverter circuit based on the temperature difference; and controlling the inverter circuit according to the switching frequency to cause the resonant circuit to resonate and heat the load.

[0008] According to the heating control method of the wireless power supply device of the present invention, the method first obtains the temperature difference between the actual temperature and the target temperature of the resonant coil, then obtains the switching frequency of the inverter circuit based on the temperature difference, and finally controls the inverter circuit according to the switching frequency to make the resonant circuit resonate and heat the load. Thus, this method adjusts the switching frequency of the inverter circuit according to the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby achieving automatic control of the temperature of the load resonant heating.

[0009] In addition, the heating control method of the wireless power supply device according to the above embodiments of the present invention may also have the following additional technical features:

[0010] According to one embodiment of the present invention, obtaining the switching frequency of the inverter circuit based on the temperature difference includes: obtaining the target heating power of the resonant circuit based on the temperature difference; obtaining the switching frequency based on the target heating power and the relationship between the power and frequency of the resonant circuit, wherein the target heating power is negatively correlated with the switching frequency, and the switching frequency is greater than the resonant frequency of the resonant circuit.

[0011] According to one embodiment of the present invention, obtaining the target heating power of a resonant circuit based on a temperature difference includes: obtaining the temperature range in which the temperature difference is located; obtaining the target heating power based on the temperature range, wherein different temperature ranges correspond to different target heating powers, and when the temperature difference is positive, the temperature difference is negatively correlated with the target heating power, and when the absolute value of the temperature difference is negative, the temperature difference is positively correlated with the target heating power.

[0012] According to one embodiment of the present invention, the switching frequency is at least 1.05 times the resonant frequency.

[0013] According to an embodiment of the present invention, the heating control method of the wireless power supply device further includes: obtaining the temperature change rate of the resonant coil within a preset time; and compensating the target heating power according to the temperature change rate.

[0014] According to one embodiment of the present invention, compensating for the target heating power based on the temperature change rate includes: obtaining the load capacity based on the temperature change rate; obtaining a first power compensation value for the resonant circuit based on the capacity; and compensating for the target heating power based on the first power compensation value.

[0015] According to an embodiment of the present invention, the heating control method of the wireless power supply device described above further includes: obtaining the voltage of the DC power supply based on the temperature change rate; obtaining a second power compensation value of the resonant circuit based on the voltage; and compensating the target heating power based on the second power compensation value.

[0016] To achieve the above objectives, a second aspect of the present invention provides a computer-readable storage medium storing a heating control program for a wireless power supply device, which, when executed by a processor, implements the aforementioned heating control method for the wireless power supply device.

[0017] The computer-readable storage medium of this invention, by executing the heating control method of the wireless power supply device described above, can automatically control the temperature of the load resonant heating.

[0018] To achieve the above objectives, a wireless power supply device is provided in a third aspect of the present invention, comprising: a memory, a processor, and a heating control program for the wireless power supply device stored in the memory and executable on the processor. When the processor executes the program, it implements the heating control method for the wireless power supply device described above.

[0019] The wireless power supply device of this invention can automatically control the temperature of the load resonant heating by executing the above-described heating control method of the wireless power supply device.

[0020] To achieve the above objectives, a fourth aspect of the present invention provides a wireless power supply device, comprising: an inverter circuit and a resonant circuit, wherein the input terminal of the inverter circuit is connected to a direct current, and the output terminal of the inverter circuit is connected to the resonant circuit, the resonant circuit including a resonant coil; a sampling circuit for sampling to obtain the actual temperature of the resonant coil; and a control circuit connected to both the sampling circuit and the inverter circuit, wherein the control circuit is used to obtain the temperature difference between the actual temperature and the target temperature of the resonant coil, obtain the switching frequency of the inverter circuit based on the temperature difference, and control the inverter circuit based on the switching frequency to cause the resonant circuit to resonate and heat the load.

[0021] According to an embodiment of the wireless power supply device of the present invention, the actual temperature of the resonant coil is obtained by a sampling circuit, the temperature difference between the actual temperature and the target temperature of the resonant coil is obtained by a control circuit, the switching frequency of the inverter circuit is obtained based on the temperature difference, and the inverter circuit is controlled according to the switching frequency to make the resonant circuit resonate and heat the load. Thus, the device adjusts the switching frequency of the inverter circuit according to the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby achieving automatic control of the temperature of the load resonant heating.

[0022] In addition, the wireless power supply device according to the above embodiments of the present invention may also have the following additional technical features:

[0023] According to one embodiment of the present invention, the control circuit obtains the switching frequency of the inverter circuit based on the temperature difference, specifically for: obtaining the target heating power of the resonant circuit based on the temperature difference;

[0024] The switching frequency is obtained based on the target heating power and the relationship between the power and frequency of the resonant circuit. The target heating power is negatively correlated with the switching frequency, and the switching frequency is greater than the resonant frequency of the resonant circuit.

[0025] According to one embodiment of the present invention, the control circuit obtains the target heating power of the resonant circuit based on the temperature difference, specifically for: obtaining the temperature range in which the temperature difference is located; obtaining the target heating power based on the temperature range, wherein different temperature ranges correspond to different target heating powers, and when the temperature difference is positive, the temperature difference is negatively correlated with the target heating power, and when the temperature difference is negative, the absolute value of the temperature difference is positively correlated with the target heating power.

[0026] According to one embodiment of the present invention, the switching frequency is at least 1.05 times the resonant frequency.

[0027] According to one embodiment of the present invention, the control circuit is further configured to acquire the temperature change rate of the resonant coil within a preset time; and to compensate the target heating power based on the temperature change rate.

[0028] According to one embodiment of the present invention, the control circuit compensates the target heating power based on the temperature change rate, specifically for: obtaining the load capacity based on the temperature change rate; obtaining a first power compensation value of the resonant circuit based on the capacity; and compensating the target heating power based on the first power compensation value.

[0029] According to one embodiment of the present invention, the control circuit is further configured to: obtain the voltage of the DC current based on the temperature change rate; obtain a second power compensation value of the resonant circuit based on the voltage; and compensate the target heating power based on the second power compensation value.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] Figure 1 A flowchart of a heating control method for a wireless power supply device according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the heating control of a wireless power supply device according to a specific embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the current versus frequency curve in a resonant circuit according to an embodiment of the present invention;

[0034] Figure 4 This is a block diagram of a wireless power supply device according to an embodiment of the present invention;

[0035] Figure 5 This is a block diagram of a wireless power supply device according to another embodiment of the present invention;

[0036] Figure 6 This is a partial circuit diagram of a wireless power supply device according to a specific embodiment of the present invention. Detailed Implementation

[0037] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0038] The heating control method, computer-readable storage medium, and wireless power supply device of the present invention are described below with reference to the accompanying drawings.

[0039] In one embodiment of the present invention, such as Figure 6 As shown, the wireless power supply device of the present invention may include an inverter circuit 210 and a resonant circuit 220. The input terminal of the inverter circuit 210 is connected to a direct current (DC), and the output terminal of the inverter circuit 210 is connected to the resonant circuit 220. The resonant circuit 220 includes a resonant coil 225. The inverter circuit 210 converts the input DC power into high-frequency AC power, which then supplies power to the load through the resonant circuit 220. The inverter circuit can be a full-bridge circuit, a half-bridge circuit, or other inverter circuits. It is understood that a full-bridge circuit is less prone to current leakage, while a half-bridge circuit is prone to current leakage during oscillation transitions, which can degrade the waveform and cause interference. The full-bridge circuit converts the AC power output from the AC transformer circuit into unidirectional pulsating DC power.

[0040] The diversity of wireless loads places increasingly higher demands on the performance of wireless power supply devices, with wireless charging and wireless heating being two commonly used functions. Current temperature control technologies typically change the heating power by directly altering the reference current in the resonant circuit; however, this method is inefficient and generates significant heat. To address this issue, this application proposes a heating control method for a wireless power supply device. This method adjusts the switching frequency of the inverter circuit based on the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby achieving automatic temperature control for the resonant heating of the load.

[0041] Figure 1 This is a flowchart of a heating control method for a wireless power supply device according to an embodiment of the present invention.

[0042] like Figure 1 As shown, the heating control method of the wireless power supply device in this embodiment of the invention may include the following steps:

[0043] S1, obtain the temperature difference between the actual temperature and the target temperature of the resonant coil.

[0044] Specifically, the resonant circuit includes a resonant coil. A temperature sensor mounted on the resonant coil can collect the actual temperature of the coil in real time, such as the center temperature. The collected actual temperature is compared with a set temperature (target temperature) to obtain a temperature difference value, which is the actual temperature minus the target temperature. This temperature difference value is then saved. For example, if the temperature sensor detects a center temperature of 80℃ for the resonant coil and a target temperature of 50℃, the temperature difference is +30℃; if the center temperature is 40℃ and the target temperature is 50℃, the temperature difference is -10℃.

[0045] S2, obtain the switching frequency of the inverter circuit based on the temperature difference.

[0046] Specifically, after obtaining the temperature difference value through the above step S1, the pre-stored temperature difference value-switching frequency table is called according to the temperature difference value to obtain the switching frequency of the inverter switch corresponding to the current temperature difference value. The temperature difference value can correspond one-to-one with the switching frequency, or the temperature range in which it is located can be obtained according to the temperature difference value, and the corresponding switching frequency can be obtained according to the temperature range.

[0047] S3 controls the inverter circuit according to the switching frequency so that the resonant circuit resonates and heats the load.

[0048] In other words, after obtaining the switching frequency corresponding to the current temperature difference through the above step S2, the inverter circuit is controlled according to the switching frequency to output the corresponding high-frequency AC power. This high-frequency AC power supplies power to the load through the resonant circuit. During the operation of the resonant circuit, the current of the resonant coil changes with the switching frequency. Therefore, the output current of the inverter circuit can be adjusted by adjusting the switching frequency, thereby indirectly controlling the power supply current of the resonant circuit and realizing the control of the resonant heating temperature.

[0049] Therefore, the heating control method of the present invention can not only effectively avoid the problems of low efficiency and severe heat generation caused by directly changing the reference current in the resonant circuit to change the heating power, but also realize automatic control of the temperature of the load resonant heating.

[0050] The following describes in detail how to obtain the switching frequency of the inverter circuit.

[0051] According to one embodiment of the present invention, obtaining the switching frequency of the inverter circuit based on the temperature difference includes: obtaining the target heating power of the resonant circuit based on the temperature difference; and obtaining the switching frequency based on the target heating power and the relationship between the power and frequency of the resonant circuit, wherein the target heating power is negatively correlated with the switching frequency, and the switching frequency is greater than the resonant frequency of the resonant circuit. That is, the larger the target heating power, the smaller the switching frequency, and vice versa.

[0052] Further, according to one embodiment of the present invention, obtaining the target heating power of the resonant circuit based on the temperature difference includes: obtaining the temperature range in which the temperature difference lies; obtaining the target heating power based on the temperature range, wherein different temperature ranges correspond to different target heating powers, and when the temperature difference is positive, the temperature difference is negatively correlated with the target heating power; when the temperature difference is negative, the absolute value of the temperature difference is positively correlated with the target heating power. That is, when the actual temperature is greater than the set temperature, the larger the temperature difference, the smaller the target heating power; and the smaller the temperature difference, the larger the target heating power. When the actual temperature is less than the set temperature, the larger the absolute value of the temperature difference, the larger the target heating power; and the smaller the absolute value of the temperature difference, the smaller the target heating power.

[0053] Specifically, step S1 yields the temperature difference value. Based on this value, a pre-stored temperature range-target heating power table is retrieved to determine the target heating power corresponding to the temperature range in which the temperature difference falls. When the temperature difference is positive, a larger value indicates a higher actual temperature of the resonant coil. To lower the actual temperature of the resonant coil, the output current of the inverter circuit needs to be kept relatively low, resulting in a lower target heating power. Conversely, a smaller temperature difference indicates that the actual temperature of the resonant coil is close to the set temperature. To increase the actual temperature of the resonant coil, the output current of the inverter circuit needs to be kept relatively high, resulting in a higher target heating power. When the temperature difference is negative, a larger absolute value indicates that the actual temperature of the resonant coil is much lower than the set temperature. To increase the actual temperature of the resonant coil, the output current of the inverter circuit needs to be kept relatively high, resulting in a higher target heating power. Conversely, a smaller absolute value indicates that the actual temperature of the resonant coil is close to the set temperature. To increase the actual temperature of the resonant coil, the output current of the inverter circuit needs to be kept relatively low, resulting in a lower target heating power.

[0054] See Figure 3As shown, Pr represents the target heating power corresponding to the resonant frequency fr. When the switching frequency is less than the resonant frequency, the current in the resonant circuit increases with the increase of the switching frequency; when the switching frequency is greater than the resonant frequency, the current in the resonant circuit decreases with the increase of the switching frequency. Therefore, when the temperature difference is positive, the larger the temperature difference, the lower the target heating power, and the higher the corresponding switching frequency; the smaller the temperature difference, the higher the target heating power, and the lower the corresponding switching frequency. When the temperature difference is negative, the larger the absolute value of the temperature difference, the higher the target heating power, and the lower the corresponding switching frequency; the smaller the absolute value of the temperature difference, the lower the target heating power, and the higher the corresponding switching frequency. It is understandable that inverter circuits mostly use PWM (Pulse Width Modulation) for frequency conversion. That is to say, the voltage output by the inverter circuit is actually a series of pulses, the width and interval of which are not equal. Their magnitude depends on the intersection of the modulating wave and the carrier wave, that is, the switching frequency. The higher the switching frequency, the more pulses in one cycle, and the better the smoothness of the current waveform. If the switching frequency is not set properly, it will produce unpleasant noise.

[0055] The target heating power is determined based on the temperature range, and the frequency corresponding to the current target heating power is determined based on the relationship between the target heating power and the frequency. Figure 3 As shown in Table 1, the corresponding switching frequency is then determined based on the relationship between the frequency and the resonant frequency.

[0056] Table 1

[0057] ΔT>+10 1.8*fr 0 < ΔT ≤ +10 1.5*fr -10≤ΔT≤0 1.3*fr -30≤ΔT<-10 1.1*fr ΔT < -30 1.05*fr

[0058] As shown in Table 1, ΔT represents the temperature difference between the actual temperature and the target temperature of the resonant coil. When the temperature difference is positive, the larger the temperature difference, the higher the corresponding switching frequency; the smaller the temperature difference, the lower the corresponding switching frequency. For example, when ΔT > +10℃, the switching frequency is 1.8*fr; when 0 < ΔT ≤ +10℃, the switching frequency is 1.5*fr. When the temperature difference is negative, the larger the absolute value of the temperature difference, the lower the corresponding switching frequency; the smaller the absolute value of the temperature difference, the higher the corresponding switching frequency. For example, when ΔT < -30℃, the switching frequency is 1.05*fr; when -10℃ ≤ ΔT ≤ 0, the switching frequency is 1.3*fr.

[0059] For example, when the detected temperature exceeds the target temperature by 10℃ (temperature difference of +10℃), the control switching frequency is 1.8*fr (resonant frequency). If fr = 100kHz, then the current switching frequency is 180kHz. When the detected temperature is 30℃ lower than the target temperature (temperature difference of -30℃), the control switching frequency is 1.05*fr (resonant frequency). If fr = 100kHz, then the current switching frequency is 105kHz. The resonant frequency is composed of inductance and capacitance, and its impedance is either zero or infinite.

[0060] To ensure the normal operation of the resonant circuit and make it inductive, in one embodiment of the present invention, the selected switching frequency is at least 1.05 times the resonant frequency of the resonant circuit. While ensuring the switching frequency is greater than the resonant frequency, it can also be any other multiple, such as 1.05 times. When the switching frequency is greater than the resonant frequency, the inductance of the series resonant circuit is greater than the capacitance, and the circuit exhibits an inductive load. According to one embodiment of the present invention, the heating control method further includes: obtaining the temperature change rate of the resonant coil within a preset time; and compensating the target heating power based on the temperature change rate. The preset time can be calibrated according to actual conditions.

[0061] In other words, during the actual operation of the power supply device, it is very likely that the target heating power obtained directly from the difference between the actual temperature of the resonant coil and the set temperature will not meet the requirements at once. For example, when it is necessary to raise the actual temperature of the resonant coil from 32°C to 35°C, according to the previously confirmed target heating power, the temperature may only rise by 1°C. Therefore, in order to improve the accuracy of temperature control, the target heating power can also be compensated according to the temperature change rate of the resonant coil.

[0062] According to one embodiment of the present invention, compensating for the target heating power based on the temperature change rate includes: obtaining the load capacity based on the temperature change rate; obtaining a first power compensation value for the resonant circuit based on the capacity; and compensating for the target heating power based on the first power compensation value.

[0063] Specifically, the temperature change rate of the resonant coil is obtained based on the temperature change over a period of time. The load capacity can be determined based on the temperature change rate. Then, the pre-stored load capacity-first power compensation value table is called according to the load capacity to obtain the power compensation value corresponding to the current load capacity. The sum of the first power compensation value and the target heating power is then used as the final target heating power. The switching frequency is determined based on the target heating power.

[0064] According to one embodiment of the present invention, the heating control method further includes: obtaining the voltage of the DC current based on the temperature change rate; obtaining a second power compensation value of the resonant circuit based on the voltage; and compensating the target heating power based on the second power compensation value.

[0065] Specifically, considering the variation in direct current (DC), to improve the accuracy and real-time performance of temperature control, the change in DC can be determined based on the temperature change over a period of time. Based on this DC variation, a second power compensation value is determined. Then, the sum of this second power compensation value and the target heating power is used as the final target heating power, and the switching frequency is determined based on this target heating power. As a concrete example, such as... Figure 2 As shown, the actual temperature T_feedback of the resonant coil in the resonant circuit is collected in real time by a temperature sensor and the difference is calculated with the set temperature T_ref. Based on the temperature difference, the target heating power level P_ref is selected. The switching frequency fs and the duty cycle of the PWM signal are determined according to the relationship between the current (power) and frequency in the resonant circuit. The duty cycle drives the circuit to work, and the switching frequency controls the inverter circuit to work, so as to output a high-frequency current, enabling the resonant circuit to resonate and heat the load. This forms a closed loop, realizing the temperature of the load resonant heating.

[0066] The drive circuit is an intermediate circuit used to amplify the signals from the control circuit, specifically amplifying the PWM pulses output by the control circuit to a level sufficient to drive the power transistors—acting as switching power amplifiers. The controller can adjust the frequency by changing the pulse train period, and adjust the voltage by changing the pulse width or duty cycle. By employing appropriate control methods, voltage and frequency can be coordinated. Current can be controlled by adjusting the PWM period and duty cycle. The controller sends the PWM signal to the drive circuit for power amplification to drive the high-frequency inverter circuit.

[0067] In summary, the heating control method of the wireless power supply device according to the embodiments of the present invention adjusts the switching frequency of the inverter circuit according to the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby realizing automatic control of the temperature of the load resonant heating.

[0068] Corresponding to the above embodiments, the present invention also proposes a computer-readable storage medium.

[0069] The present invention provides a computer-readable storage medium storing a heating control program for a wireless power supply device, which, when executed by a processor, implements the aforementioned heating control method for the wireless power supply device.

[0070] The computer-readable storage medium of this invention, by executing the heating control method of the wireless power supply device described above, can automatically control the temperature of the load resonant heating.

[0071] Corresponding to the above embodiments, the present invention also proposes a wireless power supply device.

[0072] like Figure 4 As shown, the wireless power supply device 100 of the present invention may include: a memory 110, a processor 120, and a heating control program for the wireless power supply device stored in the memory 110 and executable on the processor 120. When the processor 120 executes the heating control program for the wireless power supply device, it implements a heating control method for the wireless power supply device.

[0073] The wireless power supply device of this invention can automatically control the temperature of the load resonant heating by executing the above-described heating control method of the wireless power supply device.

[0074] Corresponding to the above embodiments, the present invention also proposes a wireless power supply device.

[0075] like Figure 5 As shown, the wireless power supply device 200 of this embodiment may include: an inverter circuit 210, a resonant circuit 220, a sampling circuit 230, and a control circuit 240.

[0076] The inverter circuit 210 has its input terminal connected to a direct current source (DC), and its output terminal connected to a resonant circuit 220. The resonant circuit 220 includes a resonant coil 225. A sampling circuit 230 is used to sample and obtain the actual temperature of the resonant coil 225. A control circuit 240 is connected to both the sampling circuit 230 and the inverter circuit 210. The control circuit 240 is used to obtain the temperature difference between the actual temperature and the target temperature of the resonant coil 225, and to obtain the switching frequency of the inverter circuit 210 based on the temperature difference. It also controls the inverter circuit 210 based on the switching frequency to enable the resonant circuit 220 to resonate and heat the load.

[0077] Specifically, the actual temperature T_feedback of the resonant coil 225 in the resonant circuit 220 is collected in real time by a temperature sensor. For example, the center temperature of the resonant coil 225 is collected. The collected actual temperature T_feedback is compared with the set temperature T_ref (target temperature) to obtain the temperature difference value. The temperature difference value is the actual temperature T_feedback minus the target temperature T_ref, and the temperature difference value is saved. For example, if the temperature sensor collects the center temperature of the resonant coil 225 as 80℃ and the target temperature as 50℃, the temperature difference value is +30℃; if the center temperature of the resonant coil 225 is 40℃ and the target temperature is 50℃, the temperature difference value is -10℃.

[0078] After obtaining the temperature difference, the pre-stored temperature difference-switching frequency table is called to obtain the switching frequency of the inverter circuit corresponding to the current temperature difference. The temperature difference can correspond one-to-one with the switching frequency, or the temperature range in which the temperature difference is located can be obtained, and the corresponding switching frequency can be obtained based on the temperature range.

[0079] After obtaining the switching frequency corresponding to the current temperature difference, the inverter circuit 210 is controlled according to the switching frequency to output a corresponding high-frequency AC power. This high-frequency AC power supplies power to the load through the resonant circuit 220. During the operation of the resonant circuit 220, the current of the resonant coil 225 changes with the switching frequency. Therefore, the output current of the inverter circuit 210 can be adjusted by adjusting the switching frequency, thereby indirectly controlling the power supply current of the resonant circuit 220 and realizing the control of the resonant heating temperature.

[0080] The difference between the actual temperature T_feedback and the set temperature T_ref is calculated. Specifically, the target heating power level P_ref is selected based on the temperature difference. The temperature difference value is used to retrieve a pre-stored temperature range-target heating power table to determine the target heating power corresponding to the temperature range in which the temperature difference value falls. When the temperature difference is positive, a larger temperature difference indicates a higher actual temperature of the resonant coil 225. If it is necessary to lower the actual temperature of the resonant coil 225, the output current of the inverter circuit 210 needs to be kept lower, resulting in a lower target heating power. Conversely, a smaller temperature difference indicates that the actual temperature of the resonant coil 225 is close to the set temperature. If it is necessary to raise the actual temperature of the resonant coil 225, the output current of the inverter circuit 210 needs to be kept higher, resulting in a higher target heating power. When the temperature difference is negative, the larger the absolute value of the temperature difference, the greater the actual temperature of the resonant coil 225 is compared to the set temperature. If it is necessary to increase the actual temperature of the resonant coil 225, the output current of the inverter circuit 210 needs to be controlled to be larger, and the target heating power will be greater. The smaller the absolute value of the temperature difference, the closer the actual temperature of the resonant coil 225 is to the set temperature. If it is necessary to increase the actual temperature of the resonant coil 225, the output current of the inverter circuit 210 needs to be controlled to be smaller, and the target heating power will be smaller.

[0081] See Figure 3As shown, Pr represents the target heating power corresponding to the resonant frequency fr. When the switching frequency is less than the resonant frequency, the current in the resonant circuit increases with the increase of the switching frequency; when the switching frequency is greater than the resonant frequency, the current in the resonant circuit decreases with the increase of the switching frequency. Therefore, when the temperature difference is positive, the larger the temperature difference, the lower the target heating power, and the higher the corresponding switching frequency; the smaller the temperature difference, the higher the target heating power, and the lower the corresponding switching frequency. When the temperature difference is negative, the larger the absolute value of the temperature difference, the higher the target heating power, and the lower the corresponding switching frequency; the smaller the absolute value of the temperature difference, the lower the target heating power, and the higher the corresponding switching frequency. It is understandable that inverter circuits mostly use PWM (Pulse Width Modulation) for frequency conversion. That is to say, the voltage output by the inverter circuit is actually a series of pulses, the width and interval of which are not equal. Their magnitude depends on the intersection of the modulating wave and the carrier wave, that is, the switching frequency. The higher the switching frequency, the more pulses in one cycle, and the better the smoothness of the current waveform. If the switching frequency is not set properly, it will produce unpleasant noise.

[0082] The switching frequency fs and the PWM signal duty cycle are determined based on the relationship between current (power) and frequency in the resonant circuit 220. The duty cycle drives the circuit, and the switching frequency controls the inverter circuit 210 to output a corresponding high-frequency AC power. This high-frequency AC power supplies the load through the resonant circuit 220. During the operation of the resonant circuit 220, the current in the resonant coil 225 changes with the switching frequency. For example, when the detected temperature exceeds the target temperature by 10℃ (temperature difference = +10℃), the switching frequency is controlled at 1.8*fr (resonant frequency). If fr = 100kHz, the current switching frequency is 180kHz. When the detected temperature is 30℃ lower than the target temperature (temperature difference = -30℃), the switching frequency is controlled at 1.05*fr (resonant frequency). If fr = 100kHz, the current switching frequency is 105kHz. The resonant frequency is composed of inductance and capacitance, and its impedance is either zero or infinite. Therefore, by adjusting the switching frequency of the inverter circuit 210, its output current can be adjusted, thereby indirectly controlling the power supply current of the resonant circuit 220 and achieving control of the resonant heating temperature.

[0083] During the actual operation of the power supply device, it is very likely that the target heating power obtained directly from the difference between the actual temperature of the resonant coil 225 and the set temperature may not meet the requirements at once. Therefore, in order to improve the accuracy of temperature control, the target heating power can also be compensated according to the temperature change rate of the resonant coil 225 within a preset time. The preset time can be calibrated according to the actual situation.

[0084] The load capacity can be determined based on the temperature change rate. Then, the pre-stored load capacity-first power compensation value table is called according to the load capacity to obtain the power compensation value corresponding to the current load capacity. The sum of the first power compensation value and the target heating power is then used as the final target heating power. The switching frequency is determined based on this target heating power.

[0085] Considering the variation in direct current (DC), to improve the accuracy and real-time performance of temperature control, the change in DC can be determined based on the temperature change over a period of time. Based on this DC change, a second power compensation value is determined. The sum of this second power compensation value and the target heating power is then used as the final target heating power. The switching frequency is determined based on this target heating power. According to the wireless power supply device of this embodiment, the switching frequency of the inverter circuit is adjusted based on the actual temperature of the resonant coil to control the output power of the resonant circuit, thereby achieving automatic control of the temperature of the load resonant heating.

[0086] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0087] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0088] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A heating control method for a wireless power supply device, characterized in that, The wireless power supply device includes an inverter circuit and a resonant circuit. The input terminal of the inverter circuit is connected to a direct current source (DC), and the output terminal of the inverter circuit is connected to the resonant circuit. The resonant circuit includes a resonant coil. The method includes: Obtain the temperature difference between the actual temperature and the target temperature of the resonant coil; Obtaining the switching frequency of the inverter circuit based on the temperature difference includes: determining the target heating power of the resonant circuit by calling a pre-stored mapping relationship between the temperature difference and the target heating power; obtaining the switching frequency based on the target heating power and the relationship between the power and frequency of the resonant circuit, wherein the target heating power is negatively correlated with the switching frequency, and the switching frequency is greater than the resonant frequency of the resonant circuit, and the switching frequency is at least 1.05 times the resonant frequency; The inverter circuit is controlled according to the switching frequency so that the resonant circuit resonates and heats the load.

2. The method according to claim 1, characterized in that, The step of determining the target heating power of the resonant circuit by invoking a pre-stored mapping relationship between the temperature difference and the target heating power based on the temperature difference includes: Obtain the temperature range within which the temperature difference value lies; The target heating power is obtained based on the temperature range, wherein different temperature ranges correspond to different target heating powers, and when the temperature difference is positive, the temperature difference is negatively correlated with the target heating power, and when the temperature difference is negative, the absolute value of the temperature difference is positively correlated with the target heating power.

3. The method according to any one of claims 1-2, characterized in that, The method further includes: Obtain the temperature change rate of the resonant coil within a preset time period; The target heating power is compensated based on the temperature change rate.

4. The method according to claim 3, characterized in that, The compensation of the target heating power based on the temperature change rate includes: The capacity of the load is obtained based on the rate of temperature change; The first power compensation value of the resonant circuit is obtained based on the capacity. The target heating power is compensated based on the first power compensation value.

5. The method according to claim 3, characterized in that, The method further includes: The voltage of the direct current is obtained based on the rate of temperature change; The second power compensation value of the resonant circuit is obtained based on the voltage. The target heating power is compensated according to the second power compensation value.

6. A computer-readable storage medium, characterized in that, It stores a heating control program for a wireless power supply device, which, when executed by a processor, implements the heating control method for a wireless power supply device according to any one of claims 1-5.

7. A wireless power supply device, characterized in that, include: A memory, a processor, and a heating control program for a wireless power supply device stored in the memory and executable on the processor, wherein when the processor executes the program, it implements the heating control method for a wireless power supply device according to any one of claims 1-5.

8. A wireless power supply device for implementing the heating control method of the wireless power supply device according to any one of claims 1-5, characterized in that, include: An inverter circuit and a resonant circuit are provided. The input terminal of the inverter circuit is connected to a direct current, and the output terminal of the inverter circuit is connected to the resonant circuit. The resonant circuit includes a resonant coil. A sampling circuit, used to sample and obtain the actual temperature of the resonant coil; A control circuit is provided, which is connected to the sampling circuit and the inverter circuit respectively. The control circuit is used to obtain the temperature difference between the actual temperature and the target temperature of the resonant coil, obtain the switching frequency of the inverter circuit based on the temperature difference, and control the inverter circuit based on the switching frequency so that the resonant circuit resonates and heats the load.

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