Control method of heating circuit, heating circuit and cooking equipment

Abstract

The invention provides a control method of a heating circuit, the heating circuit and cooking equipment. The heating circuit comprises a power supply circuit, a resonance circuit and a switching tube used for connecting the resonance circuit to the power supply circuit, the power supply circuit converts an accessed alternating current signal into a pulse direct current signal, and the control method comprises the following steps: acquiring an alternating current signal input into the power supply circuit and a resonance signal of the resonance circuit; the frequency conversion series of the resonance signal in the alternating current signal is determined; and adjusting the conduction duration of the switching tube in the current on-off period based on the frequency conversion stage number corresponding to the current on-off period of the switching tube so as to reduce the peak value of the alternating current signal input into the resonant circuit. According to the control method of the heating circuit, electromagnetic interference of the heating circuit can be reduced, and meanwhile the problem of space occupation of the heating circuit is solved.

Description

Technical Field

[0001] This application relates to the technical field of household appliances, and particularly to a control method for a heating circuit, a heating circuit, and a cooking device. Background Art

[0002] In the existing heating circuit that uses electromagnetic principles, in order to solve the electromagnetic compatibility problem generated when the resonant circuit works, a large number of filtering devices for meeting the electromagnetic compatibility of the heating circuit are added to the power supply circuit. For example, the input voltage is filtered, and then the filtered voltage is rectified; or the input power supply is rectified first, and then the rectified voltage is filtered. However, the power of electromagnetic heating devices is getting larger and larger, and the volume of the filtering devices required to meet electromagnetic compatibility also increases accordingly, resulting in an increase in the space occupied by the heating circuit. Summary of the Invention

[0003] This application provides a control method for a heating circuit, a heating circuit, and a cooking device, which can reduce the electromagnetic interference of the heating circuit and improve the problem of space occupation of the heating circuit at the same time.

[0004] To solve the above technical problems, this application provides a control method for a heating circuit. The heating circuit includes a power supply circuit, a resonant circuit, and a switching tube for connecting the resonant circuit to the power supply circuit. Among them, the power supply circuit converts the input AC signal into a pulsed DC signal. The control method includes obtaining the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determining the frequency conversion level of the resonant signal in the AC signal; adjusting the conduction duration of the switching tube within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching tube, so as to reduce the peak value of the AC signal input to the resonant circuit.

[0005] Among them, the conduction duration in the peak value region of the AC signal input to the power supply circuit is less than the conduction duration in the non-peak value region of the AC signal.

[0006] Among them, adjusting the conduction duration of the switching tube within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching tube includes obtaining the input power of the resonant circuit and determining the first conduction duration of the switching tube; obtaining the first adjustment duration corresponding to the frequency conversion level; determining the conduction duration based on the first conduction duration and the first adjustment duration.

[0007] Among them, obtaining the input power of the resonant circuit and determining the first conduction duration of the switching tube includes calculating the second conduction duration based on the input power and determining the power level; obtaining the second adjustment duration corresponding to the power level; calculating the first sum value of the second conduction duration and the second adjustment duration, and using the first sum value as the first conduction duration.

[0008] Among them, the frequency conversion levels of the resonance signal in the AC signal include the first frequency conversion level in the half envelope of the AC signal. Obtaining the first adjustment duration corresponding to the frequency conversion level includes obtaining the first adjustment duration corresponding to the first frequency conversion level; determining the conduction duration based on the first conduction duration and the first adjustment duration includes obtaining the position information of the envelope of the AC signal; in response to the envelope passing through the zero crossing point, calculating the first difference between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, and using the first difference as the conduction duration; in response to the envelope passing through the peak value, calculating the second sum value between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, then calculating the second difference between the second sum value and the base number, and using the second difference as the conduction duration, where the base number is the maximum value of the first adjustment duration of the first half envelope.

[0009] Among them, determining the conduction duration based on the first conduction duration and the first adjustment duration includes obtaining the position information of the envelope of the AC signal; in response to the envelope passing through the zero crossing point, calculating the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first decreases and then increases.

[0010] Among them, in response to the envelope passing through the zero crossing point, calculating the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first decreases and then increases includes, in response to the envelope passing through the zero crossing point, calculating the first conduction duration and the first adjustment duration so that the overall trend of the conduction duration corresponding to the frequency conversion level decreases within the first time period and increases within the second time period, where the first time period includes a sub-time period during which the conduction duration decreases and a sub-time period during which the conduction duration increases, and / or the second time period includes a sub-time period during which the conduction duration increases and a sub-time period during which the conduction duration decreases.

[0011] Among them, determining the conduction duration based on the first conduction duration and the first adjustment duration includes obtaining the position information of the envelope of the AC signal; in response to the envelope passing through the peak value, calculating the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first increases and then decreases.

[0012] Among them, in response to the envelope passing through the peak value, calculating the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first increases and then decreases includes, in response to the envelope passing through the peak value, calculating the first conduction duration and the first adjustment duration so that the overall trend of the conduction duration corresponding to the frequency conversion level increases within the first time period and decreases within the second time period, where the first time period includes a sub-time period during which the conduction duration increases and a sub-time period during which the conduction duration decreases, and / or the second time period includes a sub-time period during which the conduction duration decreases and a sub-time period during which the conduction duration increases.

[0013] Among them, an AC signal of the input power supply circuit and a resonance signal of the resonance circuit are acquired, and the frequency conversion stage of the resonance signal in the AC signal is determined, including determining the operating frequency of the AC signal based on the AC signal, and confirming the resonance frequency of the resonance circuit based on the resonance signal; calculating the ratio of the resonance frequency to the operating frequency, and using the ratio as the frequency conversion stage.

[0014] Among them, the control method further includes acquiring the position information of the envelope of the AC signal; in response to the envelope passing through zero, the steps of acquiring the AC signal of the input power supply circuit and the resonance signal of the resonance circuit, and determining the frequency conversion stage of the resonance signal in the AC signal are executed.

[0015] To solve the above technical problems, the present application provides a heating circuit, which includes a power supply circuit, a switching tube, a resonance circuit and a control circuit. The power supply circuit is used to connect to an AC signal; the switching tube is connected to the power supply circuit; the resonance circuit is connected to the switching tube and is connected to the power supply circuit through the switching tube; the control circuit is connected to the switching tube and is used to adjust the conduction duration of the switching tube in the current on-off cycle according to the above control method, and control the operation of the switching tube based on the conduction duration.

[0016] Among them, the heating circuit further includes a zero-crossing detection circuit, a frequency detection circuit, a voltage detection circuit, a current detection circuit and a resonance frequency detection circuit. The zero-crossing detection circuit is respectively connected to the power supply circuit and the control circuit and is used to detect the zero point of the AC signal; the frequency detection circuit is respectively connected to the power supply circuit and the control circuit and is used to detect the operating frequency of the AC signal; the voltage detection circuit is respectively connected to the power supply circuit and the control circuit and is used to detect the output voltage of the power supply circuit; the current detection circuit is respectively connected to the power supply circuit and the control circuit and is used to detect the output current of the power supply circuit; the resonance frequency detection circuit is respectively connected to the resonance circuit and the control circuit and is used to detect the resonance frequency of the resonance circuit.

[0017] To solve the above technical problems, the present application provides a cooking device, which includes the above heating circuit, and the control circuit adjusts the conduction duration of the switching tube in the current on-off cycle according to the above control method, and controls the operation of the switching tube based on the conduction duration.

[0018] The beneficial effects of the present application are as follows: The control method of the heating circuit in this embodiment is applied to the heating circuit. The heating circuit includes a power supply circuit, a resonant circuit, and a switching tube for connecting the resonant circuit to the power supply circuit. The power supply circuit converts the input AC signal into a pulsed DC signal. The control method includes obtaining the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determining the frequency conversion level of the resonant signal in the AC signal; adjusting the conduction duration of the switching tube within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching tube to reduce the peak value of the AC signal input to the resonant circuit. In the above manner, the control method in this embodiment reduces the peak value of the AC signal input to the resonant circuit by adjusting the conduction duration corresponding to the frequency conversion level in the current on-off cycle of the switching tube, so that the peak energy of the AC signal in the resonant circuit is symmetrically distributed and dispersed towards the trough direction, thereby reducing the generation of electromagnetic interference spikes and reducing the electromagnetic interference of the heating circuit; further, it can reduce the setting of electromagnetic filtering components, thereby reducing the board area occupied by the heating circuit, improving the problem of space occupation of the heating circuit, and at the same time reducing the setting of electromagnetic filtering components can reduce the cost of the heating circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings, where:

[0020] Figure 1 is a schematic flowchart of an embodiment of the control method of the heating circuit provided by the present application;

[0021] Figure 2 is a schematic flowchart of an embodiment of step S110 provided by the present application;

[0022] Figure 3 is a schematic timing diagram of an embodiment of the working mode of the resonant circuit provided by the present application;

[0023] Figure 4 is a schematic timing diagram of another embodiment of the working mode of the resonant circuit provided by the present application;

[0024] Figure 5 is a schematic flowchart of an embodiment of step S120 provided by the present application;

[0025] Figure 6 is a schematic flowchart of an embodiment of step S121 provided by the present application;

[0026] Figure 7It is a schematic flowchart of an embodiment of step S122 provided by this application;

[0027] Figure 8 It is a schematic flowchart of another embodiment of the control method of the heating circuit provided by this application;

[0028] Figure 9 It is a schematic structural diagram of an embodiment of the heating circuit provided by this application;

[0029] Figure 10 It is a schematic structural diagram of an embodiment of the cooking device provided by this application. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0031] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of this application, then the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If this specific posture changes, the directional indications will also change accordingly.

[0032] In addition, if there are descriptions such as "first" and "second" involved in the embodiments of this application, then the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by this application.

[0033] In the existing heating circuit using electromagnetic principles, in order to solve the electromagnetic compatibility problem generated during the operation of the resonant circuit, a large number of filtering devices for meeting the electromagnetic compatibility of the heating circuit are added at the position of the input external power supply. For example, the incoming AC signal is filtered, and then the filtered AC signal is rectified; or the incoming AC signal is rectified first, and then the rectified signal is filtered. However, as the power of the electromagnetic heating device increases, the volume of the filtering devices required for the heating circuit to meet electromagnetic compatibility also increases, resulting in an increase in the placement space of the heating circuit, and the miniaturization requirement of the electromagnetic heating device provided with the heating circuit cannot be met. Moreover, the large space occupied by the heating circuit leads to an increase in the volume of the electromagnetic heating device, and the setting of a large number of electromagnetic filtering components results in a corresponding increase in the cost of the heating circuit. Since the space in modern families is getting smaller and the demand for miniaturization of electromagnetic heating devices is increasing, the existing heating circuit cannot meet the development requirements of electromagnetic heating devices in the new era.

[0034] To solve the above technical problems, the present application provides a control method for a heating circuit. By adjusting the conduction duration of the switching tube at each moment of the input AC signal, the peak value of the AC signal input to the resonant circuit is reduced, and the peak energy of the AC wave is symmetrically distributed towards the trough direction, thereby reducing the generation of electromagnetic interference spikes and further reducing the electromagnetic interference of the heating circuit. Further, the setting of electromagnetic filtering components can be reduced, thereby reducing the board area occupied by the heating circuit, and further improving the problem of space occupation of the heating circuit. At the same time, reducing the setting of electromagnetic filtering components can reduce the cost of the heating circuit.

[0035] Among them, the heating circuit includes a power supply circuit, a resonant circuit, and a switching tube for connecting the resonant circuit to the power supply circuit. It can be understood that the heating circuit provides an alternating electromagnetic field by controlling the on / off of the switching tube and uses the alternating electromagnetic field for heating. The control method of the heating circuit can be applied to electromagnetic heating devices provided with the heating circuit. For example, the specific form of the electromagnetic heating device can be a rice cooker, an induction cooker, etc. The form of the electromagnetic heating device is not specifically limited herein. Refer to Figure 1 , Figure 1 is a schematic flowchart of an embodiment of the control method for the heating circuit provided by the present application. As shown in Figure 1 shown, the control method of the heating circuit includes the following steps:

[0036] Step S110: Obtain the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determine the frequency conversion level of the resonant signal in the AC signal.

[0037] From the AC signal and the resonant signal, it can be known that the operating frequency of the AC signal is much lower than the resonant frequency of the resonant signal. Then, within one period of the AC signal, the resonant circuit will repeat resonance for multiple periods. The frequency conversion level refers to the resonant periods corresponding to different moments within one period of the AC signal for the resonant circuit. Among them, the maximum value of the frequency conversion level refers to the number of periods that the resonant circuit repeats resonance within one period of the AC signal.

[0038] For example, within one period of the AC signal, if the resonant circuit resonates 200 times, then the frequency conversion level of the resonant signal in the AC signal is from level 1 to level 200, and the maximum value of the frequency conversion level is 200.

[0039] Specifically, referring to Figure 2 , Figure 2 is a schematic flowchart of an embodiment of step S110 provided in this application. Step S110 can be implemented through steps S111 - S112:

[0040] Step S111: Determine the operating frequency of the AC signal based on the AC signal, and confirm the resonant frequency of the resonant circuit based on the resonant signal.

[0041] The AC signal connected to the heating circuit can be the mains power, or the AC signal can be the AC signal provided by other devices. Among them, for different power supplies or the same power supply, due to power supply fluctuations, the frequencies of the AC signal at different times are different. Therefore, obtaining the operating frequency of the AC signal of the input power supply circuit can also be understood as obtaining the actual frequency of the AC signal of the input power supply circuit.

[0042] Step S112: Calculate the ratio of the resonant frequency to the operating frequency, and use the ratio as the maximum value of the frequency conversion level to confirm the frequency conversion level through the maximum value of the frequency conversion level.

[0043] Calculate the ratio of the resonant frequency to the operating frequency, and use the ratio as the maximum value of the frequency conversion level. Through the maximum value of the frequency conversion level, the frequency conversion level within this AC signal can be known. For example, if the operating frequency of the AC signal is 50 Hz and the resonant frequency of the resonant circuit is 25 KHz, then the maximum value of the frequency conversion level is: Nmax = (25 * 103 / 50) = 500. The frequency conversion levels within this period of the AC signal are 1, 2, 3,..., 500, where the frequency conversion levels are integers.

[0044] In other embodiments, the frequency of the pulsed DC signal is twice the operating frequency of the AC signal. The frequency conversion level can also be confirmed by obtaining the operating frequency of the pulsed DC signal and the resonant frequency of the resonant circuit.

[0045] Step S120: Adjust the conduction duration of the switching tube within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching tube, so as to reduce the peak value of the AC signal of the input resonant circuit.

[0046] Refer to Figure 3 , Figure 3 which is a timing diagram of an embodiment of the working mode of the resonant circuit provided by this application. As Figure 3 shown, the resonant circuit works in a continuous manner. Among them, the waveform of the AC signal accessed by the power supply circuit is a sine wave. After the power supply circuit rectifies the AC signal, a pulsed DC signal is output. At this time, the waveform of the pulsed DC signal is a mantou waveform. Refer to Figure 4 , Figure 4 which is a timing diagram of another embodiment of the working mode of the resonant circuit provided by this application. As Figure 4 shown, the resonant circuit works in an intermittent manner. By controlling the switching tube, the resonant circuit works for n1 packet drops and stops for n2 packet drops. Among them, n1 can be equal to n2; n1 can also be greater than or less than n2; n1 and n2 can also not be integers.

[0047] Among them, if the envelope shape of the AC signal in one cycle is the same as the waveform of the pulsed DC signal, then the acquisition of the envelope information of the AC signal in this embodiment can be achieved by acquiring the pulsed DC signal. The overall change trend of the resonant waveform of the resonant circuit follows the envelope change of the pulsed DC signal. Among them, different frequency conversion levels correspond to different moments within the AC signal period. Therefore, adjusting the conduction duration of the switching tube within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle can change the peak value of the AC signal of the input resonant circuit, so as to reduce the peak value of the AC signal of the input resonant circuit, thereby reducing the peak value of the resonant circuit.

[0048] Specifically, the conduction duration in the peak value area of the AC signal of the input power supply circuit is less than the conduction duration in the non-peak value area of the AC signal, that is, the overall trend of the conduction duration of the switching tube at the position with a high input voltage is less than the conduction duration of the switching tube at the position with a low input voltage. For example, in the peak value area, the average conduction duration of the switching tube is less than the conduction duration in the non-peak value area. Among them, in the peak value area, the conduction durations of the switching tubes corresponding to different frequency conversion levels can be equal, can show a decreasing trend, or can be a trend of first decreasing, then increasing and then decreasing. Similarly, in the non-peak value area, the conduction durations of the switching tubes corresponding to different frequency conversion levels can be equal, can show a decreasing trend; can show an increasing trend; can also be a trend of first decreasing, then increasing and then decreasing.

[0049] The control method of the heating circuit in this embodiment is applied to the heating circuit. The heating circuit includes a power supply circuit, a resonant circuit, and a switching transistor for connecting the resonant circuit to the power supply circuit. The power supply circuit converts the input AC signal into a pulsed DC signal. The control method includes obtaining the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determining the frequency conversion level of the resonant signal in the AC signal; adjusting the conduction duration of the switching transistor in the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching transistor, so as to reduce the peak value of the AC signal input to the resonant circuit. In the above manner, the control method of this embodiment reduces the peak value of the AC signal input to the resonant circuit by adjusting the conduction duration corresponding to the frequency conversion level of the current on-off cycle of the switching transistor, so that the peak energy of the AC signal of the input resonant circuit is symmetrically distributed in the direction of the trough, thereby reducing the generation of electromagnetic interference spikes and reducing the electromagnetic interference of the heating circuit; further, it is possible to reduce the setting of electromagnetic filtering components, thereby reducing the board area of the heating circuit, improving the space occupation problem of the heating circuit, and at the same time reducing the setting of electromagnetic filtering components can reduce the cost of the heating circuit.

[0050] Optionally, referring to Figure 5 , Figure 5 is a schematic flowchart of an embodiment of step S120 provided by this application. As Figure 5 shown, the step S120 of adjusting the conduction duration of the switching transistor in the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching transistor includes the following steps:

[0051] Step S121: Obtain the input power of the resonant circuit and determine the first conduction duration of the switching transistor.

[0052] When the input power of the resonant circuit is different, it can be understood that the resonant circuit works in different heating modes. For example, heating mode one is full-power heating, and heating mode two is non-full-power heating mode. And when the input power of the resonant circuit is different, the first conduction duration of the switching transistor is different. Then, based on the input power of the resonant circuit, the first conduction duration of the switching transistor is determined.

[0053] Step S122: Obtain the first adjustment duration corresponding to the frequency conversion level.

[0054] Obtain a first adjustment duration corresponding to the frequency conversion level. Herein, a preset duration is set, and multiplying the preset duration by the frequency conversion level can obtain the first adjustment duration corresponding to the frequency conversion level. For example, if the preset duration is t3, the first adjustment duration corresponding to the frequency conversion level can be: the first adjustment duration corresponding to the first-level frequency conversion level is 1*t3, the first adjustment duration corresponding to the second-level frequency conversion level is 2*t3,..., and the first adjustment duration corresponding to the N-level frequency conversion level is N*t3. Among them, the operating frequency and the resonant frequency of the AC signal determine that the maximum values of the frequency conversion levels of each AC signal are different. Then, different values of the preset duration t3 are set, and different ranges are divided for the maximum values of the frequency conversion levels. A preset duration t3 can be correspondingly set for different maximum values of the frequency conversion levels.

[0055] Step S123: Determine the conduction duration based on the first conduction duration and the first adjustment duration.

[0056] Determine the conduction duration of the switching tube based on the first conduction duration and the first adjustment time. For example, subtract the first adjustment duration from the first conduction duration, and use the difference as the conduction duration. Or add the first conduction duration and the first adjustment duration, subtract the base value from the sum value, and use the difference after subtracting the base value from the sum value as the conduction duration.

[0057] In this embodiment, after obtaining the first conduction duration corresponding to the input power, further obtain the first adjustment duration corresponding to the frequency conversion level, so as to determine the conduction duration based on the first conduction duration and the first adjustment duration, thereby improving the accuracy of the conduction duration and reducing the peak value of the AC signal of the input resonant circuit.

[0058] Optionally, refer to Figure 6 , Figure 6 is a schematic flowchart of an embodiment of step S121 provided by this application. As Figure 6 shown, step S121 can be implemented through the following steps:

[0059] Step S1211: Calculate a second conduction duration based on the input power and determine the power level.

[0060] Calculate the second conduction duration based on the input power of the resonant circuit, that is, determine the conduction duration of the switching tube according to the actual power. Determining the power level means determining the power level corresponding to the current input power of the resonant circuit.

[0061] Step S1212: Obtain a second adjustment duration corresponding to the power level.

[0062] Based on the power level, obtain a second adjustment duration corresponding to the power level. Understandably, the second adjustment duration is set to enable the resonant circuit to operate at different power levels. Among them, the values of the second adjustment duration can be different to distinguish different power levels. The setting of the value of the second adjustment duration can be based on the input power requirement. For example, the larger the input power, the larger the value of the second adjustment duration.

[0063] Step S1213: Calculate the first sum value of the second conduction duration and the second adjustment duration, and use the first sum value as the first conduction duration.

[0064] Based on the obtained second conduction duration and second adjustment duration, calculate the first sum value of the second conduction duration and the second adjustment duration, and use the first sum value as the first conduction duration.

[0065] In this embodiment, the second conduction duration is calculated based on the input power of the resonant circuit to obtain the accurate conduction duration of the switching tube, and further, the second adjustment duration corresponding to the power level is obtained according to the power level. The first sum value of the second conduction duration and the second adjustment duration is used as the first conduction duration to further accurately determine the conduction duration of the switching tube.

[0066] Optionally, the frequency conversion level of the resonant signal in the AC signal includes the first frequency conversion level in the half envelope of the AC signal. Obtaining the first adjustment duration corresponding to the frequency conversion level may include obtaining the first adjustment duration corresponding to the first frequency conversion level. Among them, the first frequency conversion level in this embodiment refers to the number of cycles in which the resonant circuit repeats its operation in the half envelope. For example, if the operating frequency of the AC signal is 50 Hz and the resonant frequency of the resonant circuit is 25 kHz, then the maximum value of the first frequency conversion level is: Nmax1 = (25 * 103 / 50) / 4 = 125. Refer to Figure 7 , Figure 7 is a schematic flowchart of an embodiment of step S123 provided by the present application. As Figure 7 shown, step S123 can be implemented through the following steps:

[0067] Step S1231: Obtain the position information of the envelope of the AC signal.

[0068] Obtain the envelope of the AC signal and determine the position information of the envelope. Specifically, the envelope of the pulsed DC signal can be obtained, and the position information of the envelope of the pulsed DC signal can be determined.

[0069] Step S1232: In response to the envelope crossing zero, calculate the first difference between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, and use the first difference as the conduction duration.

[0070] There is an increasing trend between the zero point and the peak of an envelope, that is, there is an increasing trend in the first half of an envelope. Then, in response to the envelope crossing the zero point, calculate the first difference between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, and use the first difference as the conduction duration. Between the zero point and the peak of this envelope, the trend of the conduction duration of the switching tube is decreasing. Understandably, when the input voltage is high, the conduction duration is shorter than when the input voltage is low.

[0071] Step S1233: In response to the envelope crossing the peak, calculate the second sum value between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, then calculate the second difference between the second sum value and the base number, and use the second difference as the conduction duration, where the base number is the maximum value of the first adjustment duration of the first half of the envelope.

[0072] There is a decreasing trend between the peak and the zero point of an envelope, that is, there is a decreasing trend in the second half of an envelope. Then, in response to the envelope crossing the peak, calculate the second sum value between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, then calculate the second difference between the second sum value and the base number, and use the second difference as the conduction duration. Among them, the waveform change trend of the envelope is overall symmetric, so the base number is the maximum value of the first adjustment duration of the first half of the envelope. Between the peak and the zero point of this envelope, the trend of the conduction duration of the switching tube is increasing. Understandably, where the input voltage is high, the conduction duration of the switching tube is shorter than where the input voltage is low.

[0073] In this embodiment, for the conduction duration of the switching tube, in the first half of the envelope, use the first difference between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level as the conduction duration, and in the second half of the envelope, calculate the second sum value between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, then calculate the second difference between the second sum value and the base number, and use the second difference as the conduction duration, so that the change trend of the conduction duration of the switching tube in the envelope is first decreasing and then increasing, so that the overall change trend of the peak value of the resonant circuit is the same as the change trend of the envelope.

[0074] Optionally, in another embodiment of step S123, it can also be implemented through steps S41 - S42:

[0075] Step S41: Obtain the position information of the envelope of the AC signal.

[0076] Obtain the envelope of the AC signal and determine the position information of the envelope. Specifically, the envelope of the pulsed DC signal can be obtained and the position information of the envelope of the pulsed DC signal can be determined.

[0077] Step S42: In response to the envelope crossing the zero point, calculate the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first decreases and then increases.

[0078] It can be known that two adjacent envelope zeros are a complete envelope. Among them, the overall trend of the envelope is first increasing and then decreasing. In order to keep the overall change trend of the peak value of the resonant circuit the same as that of the envelope, calculate the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion stage first decreases and then increases, so that the conduction duration is less at the place where the input voltage is high than at the place where the input voltage is low.

[0079] Optionally, in a specific embodiment of step S42, in response to the envelope passing through the zero point, calculate the first conduction duration and the first adjustment duration so that the overall trend of the conduction duration corresponding to the frequency conversion stage decreases within the first time period and increases within the second time period, where the first time period includes a sub-time period with a decreasing conduction duration and a sub-time period with an increasing conduction duration, and / or the second time period includes a sub-time period with an increasing conduction duration and a sub-time period with a decreasing conduction duration.

[0080] Optionally, in another embodiment of step S123, it can also be implemented through steps S51 - S52:

[0081] Step S51: Obtain the position information of the envelope of the AC signal.

[0082] Obtain the envelope of the AC signal and determine the position information of the envelope. Specifically, the envelope of the pulsed DC signal can be obtained and the position information of the envelope of the pulsed DC signal can be determined.

[0083] Step S52: In response to the envelope passing through the peak value, calculate the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion stage first increases and then decreases.

[0084] It can be known that between the peak values of two adjacent envelopes, the overall trend of the envelope is first decreasing and then increasing. In order to keep the overall change trend of the peak value of the resonant circuit the same as that of the envelope, calculate the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion stage first increases and then decreases.

[0085] Optionally, in an embodiment of step S52, in response to the envelope passing through the peak value, calculate the first conduction duration and the first adjustment duration so that the overall trend of the conduction duration corresponding to the frequency conversion stage increases within the first time period and decreases within the second time period, where the first time period includes a sub-time period with an increasing conduction duration and a sub-time period with a decreasing conduction duration, and / or the second time period includes a sub-time period with a decreasing conduction duration and a sub-time period with an increasing conduction duration.

[0086] Optionally, in another embodiment of the control method of the heating circuit provided by the present application, the control method further includes the following steps:

[0087] Step S210: Obtain the position information of the envelope of the AC signal.

[0088] Obtain the envelope of the AC signal and determine the position information of the envelope. Specifically, the envelope of the pulsed DC signal can be obtained, and the position information of the envelope of the pulsed DC signal can be determined.

[0089] Step S220: In response to the envelope crossing zero, obtain the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determine the frequency conversion stage number of the resonant signal in the AC signal.

[0090] At the position where the envelope crosses zero, obtain the AC signal of the power supply circuit and the resonant signal of the resonant circuit, and determine the frequency conversion stage number of the resonant signal in the AC signal. It can be understood that at the position where the envelope crosses zero, update the AC signal and the resonant signal to obtain the updated frequency conversion stage number. And adjust the conduction duration of the switching tube in the current on-off cycle based on the updated frequency conversion stage number.

[0091] Refer to Figure 8 , Figure 8 is a schematic flowchart of another embodiment of the control method provided by the present application. As Figure 8 shown, the execution process of the control method is as follows:

[0092] Obtain the preset second conduction duration t1, preset second adjustment duration t2, preset duration t3, preset frequency conversion stage number N and the preset resonant frequency fs1 of the resonant circuit of the switching tube. In response to the envelope crossing zero, obtain the output voltage V1 and output current I1 of the power supply circuit, calculate the input power P of the resonant circuit, update the second conduction duration t1, and update the second adjustment duration t2 according to the power level; and update the first conduction duration ton = t1 + t2; then obtain the operating frequency f of the alternating current, obtain the resonant frequency fs2, and calculate the maximum value Nmax1 of the first frequency conversion stage number; in response to the heating circuit not stopping working, calculate the first adjustment duration Nt3(1 - N) of the switching tube corresponding to the first frequency conversion stage number in the on-off cycle, in the first half envelope, use the first difference obtained by subtracting the first adjustment duration Nt3 corresponding to the first frequency conversion stage number from the first conduction duration ton as the conduction duration of the switching tube corresponding to the first frequency conversion stage number in the on-off cycle, and continue until the Nth stage of the first frequency conversion stage number. In the second half envelope, use the first adjustment duration corresponding to the Nth stage of the first frequency conversion stage number as the base number, make a second difference between the first conduction duration ton and the base number, and use the second sum value obtained by adding the second difference to the first adjustment duration corresponding to the first frequency conversion stage number as the conduction duration of the switching tube corresponding to the first frequency conversion stage number in the on-off cycle, and continue until the Nth stage of the frequency conversion stage number.

[0093] The present application provides a heating circuit. Refer to Figure 9 , Figure 9The figure is a schematic structural diagram of an embodiment of the heating circuit provided by this application. As Figure 9 shown, the heating circuit 10 includes a power supply circuit 11, a switching tube 12, a resonant circuit 13, and a control circuit 14. Among them, the power supply circuit 11 is connected to the resonant circuit 13, the resonant circuit 13 is respectively connected to the control circuit 14 and the switching tube 12, and the switching tube 12 is also respectively connected to the power supply circuit 11 and the control circuit 14. Among them, the power supply circuit 11 is used to access an AC signal and rectify the AC signal to output a pulsed DC signal, and the pulsed DC signal is used to supply power to the resonant circuit 13 and the switching tube 12, and the pulsed DC signal can also be used to supply power to the control circuit 14. Among them, the power supply circuit 11 is a conventional power supply module without adding a large number of additional electromagnetic filtering components.

[0094] Among them, when the heating circuit 10 works, the control circuit 14 adjusts the conduction duration of the switching tube 12 in the current on-off cycle based on the above control method of the heating circuit, and controls the operation of the switching tube 12 based on the conduction duration.

[0095] Optionally, continue to refer to Figure 9 , the heating circuit 10 further includes a zero-crossing detection circuit 15, a frequency detection circuit 16, a voltage detection circuit 17, a current detection circuit 18, and a resonant frequency detection circuit 19. Among them, the zero-crossing detection circuit 15 is respectively connected to the power supply circuit 11 and the control circuit 14, and the zero-crossing detection circuit 15 is used to detect the zero point of the alternating current input to the power supply circuit 11 and feedback a zero-crossing signal to the control circuit 14 when the alternating current zero-crossing point is detected. The frequency detection circuit 16 is respectively connected to the power supply circuit 11 and the control circuit 14, and the frequency detection circuit 16 is used to detect the operating frequency of the alternating current input to the power supply circuit 11. The voltage detection circuit 17 is respectively connected to the power supply circuit 11 and the control circuit 14, and the voltage detection circuit 17 is used to detect the output voltage of the power supply circuit 11. The current detection circuit 18 is respectively connected to the power supply circuit 11 and the control circuit 14, and the current detection circuit 18 is used to detect the output current of the power supply circuit 11. The resonant frequency detection circuit 19 is respectively connected to the resonant circuit 13 and the control circuit 14, and is used to detect the operating frequency of the resonant circuit 13.

[0096] It can be understood that the control circuit 14 will respectively obtain the zero-crossing signal, the operating frequency of the input alternating current, the voltage and current output by the power supply circuit 11, and the resonant frequency of the resonant circuit from the zero-crossing detection circuit 15, the frequency detection circuit 16, the voltage detection circuit 17, the current detection circuit 18, and the resonant frequency detection circuit 19. The control circuit 14 adjusts the conduction duration of the switching tube 12 in the current on-off cycle based on the obtained zero-crossing signal, actual frequency, output voltage, output current, and the resonant frequency of the resonant circuit, and controls the operation of the switching tube 12 based on the conduction duration.

[0097] For example, in 125 resonant cycles of the half envelope, the conduction duration of the switching tube corresponding to the first frequency conversion stage of the first stage is: ton - t3*1; the conduction duration of the switching tube corresponding to the first frequency conversion stage of the second stage is: ton - t3*2. Or in another 125 resonant cycles of the half envelope, the conduction duration of the switching tube corresponding to the first frequency conversion stage of the first stage is: ton - t3*125 + t3*1; the conduction duration of the switching tube corresponding to the first frequency conversion stage of the second stage is: ton - t3*125 + t3*2.

[0098] The present application provides a cooking device. Refer to Figure 10 , Figure 10 which is a schematic structural diagram of an embodiment of the cooking device provided by the present application. As Figure 10 shown, the cooking device 70 includes a heating circuit 71, and the heating circuit 71 is any one of the heating circuits in the above heating circuit embodiments, and the heating circuit adjusts the conduction duration of the switching tube in the current on-off cycle based on any one of the control method embodiments of the above heating circuit, and controls the operation of the switching tube based on the conduction duration. Among them, the cooking device can be a rice cooker, an induction cooker, etc., and the specific type of the cooking device is not limited herein.

[0099] In the description of the present application, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, mechanisms, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0100] Any process or method description shown in the flowchart or described in other ways herein can be understood as representing a mechanism, segment, or part of code including one or more executable instructions for implementing a specific logical function or process, and the scope of the preferred embodiments of the present application includes additional implementations, where the functions can be executed in a manner that is not shown or discussed, including in a substantially simultaneous manner or in a reverse order according to the involved functions, which should be understood by those skilled in the art of the embodiments of the present application.

[0101] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a definite list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (which can be a personal computer, server, network device, or other system that can fetch instructions from the instruction execution system, apparatus, or device and execute the instructions), or used in combination with these instruction execution systems, apparatuses, or devices.

[0102] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A control method for a heating circuit, characterized in that, The heating circuit includes a power supply circuit, a resonant circuit, and a switching transistor for connecting the resonant circuit to the power supply circuit. Among them, the power supply circuit converts the input AC signal into a pulsed DC signal. The control method includes: Obtain the AC signal input to the power supply circuit and the resonant signal of the resonant circuit, and determine the frequency conversion level of the resonant signal in the AC signal; Adjust the conduction duration of the switching transistor within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching transistor, so as to reduce the peak value of the AC signal input to the resonant circuit.

2. The control method according to claim 1, wherein: The conduction duration in the peak region of the AC signal input to the power supply circuit is less than the conduction duration in the non-peak region of the AC signal.

3. The control method according to claim 2, wherein The adjusting the conduction duration of the switching transistor within the current on-off cycle based on the frequency conversion level corresponding to the current on-off cycle of the switching transistor includes: Obtain the input power of the resonant circuit and determine the first conduction duration of the switching transistor; Obtain the first adjustment duration corresponding to the frequency conversion level; Determine the conduction duration based on the first conduction duration and the first adjustment duration.

4. The control method according to claim 3, wherein The obtaining the input power of the resonant circuit and determining the first conduction duration of the switching transistor includes: Calculate the second conduction duration based on the input power and determine the power level; Obtain the second adjustment duration corresponding to the power level; Calculate the first sum value of the second conduction duration and the second adjustment duration, and use the first sum value as the first conduction duration.

5. The control method according to claim 4, wherein The frequency conversion level of the resonant signal in the AC signal includes the first frequency conversion level of the resonant signal in the half envelope of the AC signal. The obtaining the first adjustment duration corresponding to the frequency conversion level includes: Obtain the first adjustment duration corresponding to the first frequency conversion level; The determining the conduction duration based on the first conduction duration and the first adjustment duration includes: Obtain the position information of the envelope of the AC signal; In response to the envelope passing through the zero point, calculate the first difference between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, and use the first difference as the conduction duration; In response to the envelope passing through the peak value, calculate the second sum value between the first conduction duration and the first adjustment duration corresponding to the first frequency conversion level, and then calculate the second difference between the second sum value and the base number, and use the second difference as the conduction duration, where the base number is the maximum value of the first adjustment duration in the first half envelope.

6. The control method according to claim 4, wherein The determining the conduction duration based on the first conduction duration and the first adjustment duration includes: Obtain the position information of the envelope of the AC signal; In response to the envelope passing through the zero point, calculate the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first decreases and then increases.

7. The control method according to claim 6, characterized in that The calculating the first conduction duration and the first adjustment duration so that the conduction duration corresponding to the frequency conversion level first decreases and then increases in response to the envelope passing through the zero point includes: In response to the zero-crossing of the envelope, calculate the first conduction duration and the first adjustment duration such that the conduction duration corresponding to the frequency conversion stage decreases as a whole in the first time period and increases as a whole in the second time period, where the first time period includes a sub-time period in which the conduction duration decreases and a sub-time period in which the conduction duration increases, and / or the second time period includes a sub-time period in which the conduction duration increases and a sub-time period in which the conduction duration decreases.

8. The control method according to claim 4, wherein Determining the conduction duration based on the first conduction duration and the first adjustment duration includes: Obtain the position information of the envelope of the AC signal; In response to the envelope passing through the peak value, calculate the first conduction duration and the first adjustment duration such that the conduction duration corresponding to the frequency conversion stage first increases and then decreases.

9. The control method according to claim 8, wherein The step of, in response to the envelope passing through the peak value, calculating the first conduction duration and the first adjustment duration such that the conduction duration corresponding to the frequency conversion stage first increases and then decreases includes: In response to the envelope passing through the peak value, calculate the first conduction duration and the first adjustment duration such that the conduction duration corresponding to the frequency conversion stage increases as a whole in the first time period and decreases as a whole in the second time period, where the first time period includes a sub-time period in which the conduction duration increases and a sub-time period in which the conduction duration decreases, and / or the second time period includes a sub-time period in which the conduction duration decreases and a sub-time period in which the conduction duration increases.

10. The control method according to claim 1, characterized in that, The step of obtaining the AC signal input to the power supply circuit and the resonance signal of the resonance circuit and determining the frequency conversion stage of the resonance signal in the AC signal includes: Determine the operating frequency of the AC signal based on the AC signal, and confirm the resonance frequency of the resonance circuit based on the resonance signal; Calculate the ratio of the resonance frequency to the operating frequency, and use the ratio as the frequency conversion stage.

11. The control method according to claim 1, wherein, The control method further includes: Obtain the position information of the envelope of the AC signal; In response to the envelope passing through the zero-crossing, execute the step of obtaining the AC signal input to the power supply circuit and the resonance signal of the resonance circuit and determining the frequency conversion stage of the resonance signal in the AC signal.

12. A heating circuit, characterized in that, Includes: A power supply circuit for connecting to an AC signal; A switching transistor connected to the power supply circuit; A resonance circuit connected to the switching transistor and the power supply circuit respectively, and connected to the power supply circuit through the switching transistor; A control circuit connected to the switching transistor, configured to adjust the conduction duration of the switching transistor in the current on-off cycle based on the control method according to any one of claims 1-11, and control the operation of the switching transistor based on the conduction duration.

13. The heating circuit according to claim 12, characterized in that, The heating circuit further includes: A zero-crossing detection circuit connected to the power supply circuit and the control circuit respectively, for detecting the zero point of the AC signal; A frequency detection circuit connected to the power supply circuit and the control circuit respectively, for detecting the operating frequency of the AC signal; A voltage detection circuit connected to the power supply circuit and the control circuit respectively, for detecting the output voltage of the power supply circuit; The current detection circuit is respectively connected to the power supply circuit and the control circuit, and is used to detect the output current of the power supply circuit; The resonance frequency detection circuit is respectively connected to the resonance circuit and the control circuit, and is used to detect the resonance frequency of the resonance circuit.

14. A cooking device, characterized in that, Comprising: The heating circuit according to any one of claims 12-13, and the control circuit adjusts the conduction duration of the switching tube within the current on-off cycle based on the control method according to any one of claims 1-11, and controls the operation of the switching tube based on the conduction duration.

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