Heating control method, device and electromagnetic heating cooking appliance

Abstract

The application discloses a heating control method, device and electromagnetic heating cooking utensil. The method comprises the following steps: obtaining a target power of the electromagnetic heating cooking utensil; judging whether the target power is less than a threshold power; if the target power is less than the threshold power, controlling the electromagnetic heating cooking utensil to sequentially enter a starting stage, a heating stage and a stopping stage in each control period, wherein in the starting stage, a driving current is provided to a power switch tube in a driving period of the power switch tube, the driving current comprises a first driving current I1 and a second driving current I2, a voltage value of a driving end of the power switch tube is obtained, the driving current is switched from I1 to I2 according to the voltage value, the amplitude of I1 remains unchanged, and the amplitude of I2 increases with the whole driving period. The power switch tube is turned on by the multi-section driving current, the C pole current when the power switch tube is turned on can be effectively reduced, and hard starting is avoided.

Description

Technical Field

[0001] This invention relates generally to the field of cooking appliance technology, and more specifically to a heating control method, device and electromagnetic heating cooking appliance. Background Technology

[0002] Electromagnetic induction heating (also known as IH heating or electromagnetic heating) cooking appliances generally include a resonant heating circuit (or LC oscillation circuit), and the power switching transistor IGBT is usually used to control the conduction and shutdown of the LC oscillation circuit.

[0003] Current IH cooking appliances often require low-power heating during cooking to ensure precise heat control and cooking results. To provide the necessary low power, the following solutions are commonly used:

[0004] The first method involves adjusting the drive pulse width to achieve power regulation. A smaller pulse width results in lower power, and a larger pulse width results in higher power. However, this method cannot achieve low power across the entire range. For example, with a rated power of 1200W, adjusting the pulse width cannot achieve 400W because the IGBT exhibits hard turn-on behavior under low power conditions, which can easily lead to IGBT burnout. (See appendix for details.) Figure 1 When the power gradually decreases from 1200W to 300W, the turn-on voltage of the power switch increases, leading to an increase in the starting current (see Appendix). Figure 3 (A schematic diagram showing the relationship between the collector voltage and collector current of a power switching transistor IGBT under different drive voltages) This can easily lead to the IGBT burning out.

[0005] The second method involves adjusting the duty cycle of the rated power to obtain lower power. For example, with a rated power of 1200W, a duty cycle of 6s / 4s, heating for 6s, stopping for 4s, and a cycle of 10s, an average power of 720W (1200W × 6 / 10) is obtained (see appendix). Figure 2 When using this method, a long heating cycle will affect the cooking effect, while a short heating cycle will cause the IGBT to be forcibly turned on, which will lead to the IGBT burning out.

[0006] The third method involves zero-crossing chopping at the AC end, such as by adding a thyristor to control zero-crossing loss. This method increases the need for high-power switching control, increases cost, requires more space, and has lower reliability.

[0007] The fourth method involves adding a transformer unit. In the initial stage, a low-voltage pulse drive is used, while in the heating stage, a high-voltage pulse drive is used, thus suppressing the starting pulse current and achieving low power. However, this method has low reliability, easily leading to damage to power devices. Furthermore, due to high circuit losses, it requires high timeliness and consistency of power devices, and cannot automatically adjust to adapt to the drive voltage.

[0008] Therefore, an electromagnetic heating control method is needed to at least partially solve the above problems. Summary of the Invention

[0009] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0010] To at least partially address the problems in the prior art, a first aspect of the present invention provides a heating control method for an electromagnetic heating cooking appliance, the electromagnetic heating cooking appliance comprising an LC resonant circuit and a power switching transistor, wherein the method comprises the following steps:

[0011] Obtain the target power of the electromagnetic heating cooking appliance;

[0012] Determine whether the target power is less than the threshold power;

[0013] If the target power is less than the threshold power, the electromagnetic heating cooking appliance is controlled to sequentially enter the start-up phase, the heating phase, and the stop phase in each control cycle, wherein, in the start-up phase:

[0014] During the drive cycle of the power switch, a drive current is provided to the power switch, the drive current including a first drive current I1 and a second drive current I2;

[0015] Obtain the voltage value at the drive terminal of the power switch transistor; and

[0016] The driving current is controlled to switch from the first driving current I1 to the second driving current I2 based on the voltage value at the driving terminal.

[0017] Wherein, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than or equal to the amplitude of the second driving current I2 in the previous driving cycle.

[0018] The amplitude of the second drive current I2 in the last drive cycle is greater than the amplitude of the second drive current I2 in the first drive cycle;

[0019] The amplitude of the first driving current I1 remains unchanged.

[0020] According to the electromagnetic heating control method of the present invention, when in low-power heating mode, the electromagnetic heating cooking appliance is controlled to sequentially enter the start-up stage, heating stage, and stop stage in each control cycle. Specifically, in the start-up stage, a multi-segment drive current is used to turn on the power switch transistor, and the drive current is controlled by monitoring the voltage at the drive terminal of the power switch transistor, which effectively avoids hard start of the power switch transistor.

[0021] During the start-up phase of the drive cycle, the second drive current I2 increases, gradually increasing the amplitude of the drive current, so that the cooking appliance can smoothly and reliably transition from the start-up phase to the heating phase, and is less prone to damage.

[0022] Optionally, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than the amplitude of the second driving current I2 in the previous driving cycle.

[0023] According to the electromagnetic heating control method of the present invention, during the driving cycle of the start-up phase, the amplitude of the second driving current I2 can be controlled to increase monotonically in a regular manner, and the control scheme is easy to implement.

[0024] Optionally, the amplitude of the second drive current I2 in the first drive cycle of the power switch is less than the amplitude of the first drive current I1; and / or

[0025] The amplitude of the second drive current I2 in the last drive cycle of the power switch is greater than the amplitude of the first drive current I1.

[0026] According to the electromagnetic heating control method of the present invention, the amplitude of the second driving current I2 is further reduced during the startup phase to further save power.

[0027] Optionally, controlling the switching of the drive current from the first drive current I1 to the second drive current I2 based on the voltage value at the drive terminal includes:

[0028] Determine whether the voltage value at the drive terminal is greater than a first voltage threshold, wherein the first voltage threshold is greater than the threshold voltage of the power switch transistor;

[0029] If the voltage value at the drive terminal is greater than the first voltage threshold, the drive current is controlled to switch from the first drive current I1 to the second drive current I2.

[0030] According to the electromagnetic heating control method of the present invention, in low-power heating mode, during the startup phase, the drive current is adjusted by the voltage value fed back from the drive terminal of the power switch tube, driving the power switch tube to operate sequentially in the cutoff region, amplification region, and saturation region. During the Miller plateau region of the power switch tube, the voltage at the drive terminal of the power switch tube is limited within a set range to limit the switching current flowing through the power switch tube at the moment of turn-on, avoiding hard turn-on of the power switch tube. This achieves reliable millisecond-level duty cycle low-power continuous heating and variable-power heating, thereby improving cooking results and enhancing user experience. Furthermore, the electromagnetic heating control method of the present invention can automatically adapt to power switch tubes from different manufacturers to achieve soft start without increasing cost or structural space, while also reducing electromagnetic interference and noise generated during electromagnetic heating startup.

[0031] Optionally, the heating control method further includes:

[0032] After the drive current is switched to the second drive current I2, the Miller platform is determined to have ended based on the voltage value at the drive terminal.

[0033] If the Miller platform has ended, determine whether the voltage value at the drive end is greater than the second voltage threshold.

[0034] If the voltage value at the driving terminal is greater than the second voltage threshold, the driving mode of the power switch is switched from current driving to voltage driving, and a first driving voltage Va is provided to the power switch to drive the power switch to operate in the saturated conduction state.

[0035] According to the electromagnetic heating control method of the present invention, during the startup phase, after the Miller period of the power switch ends, the power switch is operated in a voltage-driven mode to operate in a saturated conduction state. At this time, the conduction voltage between the collector and emitter of the power switch is reduced, and the heat loss of the power switch is reduced. This can protect the power switch while storing energy for the LC oscillation circuit.

[0036] Optionally, determining whether the Miller platform has ended based on the voltage value at the drive terminal includes:

[0037] Starting from the moment of the first predetermined time Tm after the drive current switches to the second drive current I2, if the voltage value of the drive terminal continuously increases within the second predetermined time Tp, the Miller platform is determined to end.

[0038] According to the electromagnetic heating control method of the present invention, by monitoring the gate voltage of the power switch, it is possible to effectively determine whether the Miller period has ended, and avoids the need to set up an additional power switch voltage monitoring component.

[0039] Optionally, during the heating phase, a first driving voltage Va is provided to the power switch during the driving cycle of the power switch to drive the power switch to operate in a saturated conduction state.

[0040] During the stop phase, the power switch is deactivated.

[0041] According to the electromagnetic heating control method of the present invention, during the heating stage, the power switch is operated in a saturated conduction state using a voltage-driven method. At this time, the conduction voltage between the collector (C) and emitter (E) of the power switch is reduced, thus decreasing the heat loss of the power switch. This allows for energy storage for the LC oscillation circuit while protecting the power switch. During the shutdown stage, the power switch is deactivated, thereby enabling different heating duty cycles.

[0042] Optionally, an AC power source is used to power the electromagnetic heating cooking appliance, and the heating control method further includes:

[0043] Obtain the zero-crossing signal of the AC power supply;

[0044] The starting point of the startup phase is determined based on the voltage zero-crossing signal.

[0045] According to the electromagnetic heating control method of the present invention, the starting point of the start-up stage is determined based on the zero-crossing point of the AC power supply, which can largely eliminate interference signals, thereby making the control more precise.

[0046] Optionally, determining the starting point of the startup phase based on the voltage zero-crossing point includes:

[0047] The time of bias duration T0 before the voltage zero-crossing point is determined as the starting point of the startup phase, and the startup phase continues until the end of the nth chopping cycle from the voltage zero-crossing point, where n is a non-negative integer.

[0048] According to the electromagnetic heating control method of the present invention, sufficient discharge time is given to the power switch tube when it is turned on, so as to avoid excessive current at the collector when the power switch tube is turned on.

[0049] Optionally, the bias duration T0 satisfies: 500μs≤T0≤5ms; and / or

[0050] n is equal to 1 or 0.

[0051] Optionally, the first drive current I1 satisfies: 10mA ≤ I1 ≤ 80mA; and / or

[0052] The second driving current I2 satisfies: 5mA≤I2≤60mA.

[0053] Optionally, the first driving voltage Va satisfies: 15V≤Va≤22V.

[0054] According to the electromagnetic heating control method of the present invention, a wider range of control parameters can be set to adapt to the performance of power switching transistors from different manufacturers.

[0055] A second aspect of the present invention provides a heating control device for an electromagnetic heating cooking appliance, the electromagnetic heating cooking appliance including a resonant heating circuit, wherein the heating control device includes:

[0056] A power switching transistor is used to control the resonant operation of the resonant heating circuit, and the power switching transistor includes a driving terminal.

[0057] A voltage detection module, one end of which is electrically coupled to the drive terminal of the power switch transistor to detect the voltage value at the drive terminal; and

[0058] A control drive module, comprising a voltage source and a variable current source, is electrically coupled to the drive terminal of the power switch and to the other end of the voltage detection module, to drive the power switch according to the voltage value at the drive terminal.

[0059] The control drive module performs the following operations:

[0060] Obtain the target power of the electromagnetic heating cooking appliance;

[0061] Determine whether the target power is less than the threshold power;

[0062] If the target power is less than the threshold power, in each control cycle, the control drive module controls the electromagnetic heating cooking appliance to sequentially enter the start-up phase, the heating phase, and the stop phase, wherein, in the start-up phase:

[0063] During the drive cycle of the power switch, the control drive module provides a drive current to the power switch, the drive current including a first drive current I1 and a second drive current I2.

[0064] The control drive module acquires the voltage value at the drive terminal of the power switch; and

[0065] The control drive module switches the drive current from the first drive current I1 to the second drive current I2 according to the voltage value at the drive terminal.

[0066] Wherein, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than or equal to the amplitude of the second driving current I2 in the previous driving cycle.

[0067] The amplitude of the second drive current I2 in the last drive cycle is greater than the amplitude of the second drive current I2 in the first drive cycle.

[0068] The amplitude of the first driving current I1 remains unchanged.

[0069] According to the electromagnetic heating control device of the present invention, when in low-power heating mode, the electromagnetic heating cooking appliance is controlled to sequentially enter the start-up stage, the heating stage, and the stop stage in each control cycle. Specifically, in the start-up stage, a multi-segment drive current is used to conduct the power switching transistor, and the drive current is controlled by monitoring the voltage at the drive terminal of the power switching transistor, which effectively avoids hard starting of the power switching transistor.

[0070] During the start-up phase of the drive cycle, the second drive current I2 increases, gradually increasing the amplitude of the drive current, so that the cooking appliance can smoothly and reliably transition from the start-up phase to the heating phase, and is less prone to damage.

[0071] Optionally, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than the amplitude of the second driving current I2 in the previous driving cycle.

[0072] According to the electromagnetic heating control device of the present invention, during the drive cycle of the start-up phase, the amplitude of the second drive current I2 can be controlled to increase monotonically in a regular manner, and the control scheme is easy to implement.

[0073] Optionally, the amplitude of the second drive current I2 in the first drive cycle of the power switch is less than the amplitude of the first drive current I1; and / or

[0074] The amplitude of the second drive current I2 in the last drive cycle of the power switch is greater than the amplitude of the first drive current I1.

[0075] According to the electromagnetic heating control device of the present invention, the amplitude of the second driving current I2 is further reduced during the startup phase to further save power.

[0076] Optionally, the control drive module switches the drive current from the first drive current I1 to the second drive current I2 according to the voltage value at the drive terminal, including:

[0077] The control drive module determines whether the voltage value at the drive terminal is greater than a first voltage threshold, wherein the first voltage threshold is greater than the threshold voltage of the power switch.

[0078] If the voltage value at the drive terminal is greater than the first voltage threshold, the control drive module switches the drive current from the first drive current I1 to the second drive current I2.

[0079] According to the electromagnetic heating control device of the present invention, in low-power heating mode, during the startup phase, the drive current is adjusted by the voltage value fed back from the drive terminal of the power switch tube, driving the power switch tube to operate sequentially in the cutoff region, amplification region, and saturation region. During the Miller plateau region of the power switch tube, the voltage at the drive terminal of the power switch tube is limited within a set range to limit the switching current flowing through the power switch tube at the moment of turn-on, avoiding hard turn-on of the power switch tube. This achieves reliable millisecond-level duty cycle low-power continuous heating and variable-power heating, thereby improving cooking results and enhancing user experience. Furthermore, the electromagnetic heating control method of the present invention can automatically adapt to power switch tubes from different manufacturers to achieve soft start without increasing cost or structural space, while also reducing electromagnetic interference and noise generated during electromagnetic heating startup.

[0080] Optionally, after the drive current is switched to the second drive current I2, the control drive module determines whether the Miller platform has ended based on the voltage value at the drive terminal.

[0081] If the Miller platform has ended, the control drive module determines whether the voltage value at the drive end is greater than the second voltage threshold.

[0082] If the voltage value at the driving terminal is greater than the second voltage threshold, the driving mode of the power switch is switched from current driving to voltage driving. The control driving module provides a first driving voltage Va to the power switch to drive the power switch to operate in the saturated conduction state.

[0083] According to the electromagnetic heating control device of the present invention, during the startup phase, after the Miller period of the power switch tube ends, the power switch tube is operated in a voltage-driven mode to operate in a saturated conduction state. At this time, the conduction voltage between the collector and emitter of the power switch tube is reduced, and the heat loss of the power switch tube is reduced. This can protect the power switch tube while storing energy for the LC oscillation circuit.

[0084] Optionally, the control drive module determines whether the Miller platform has ended based on the voltage value at the drive terminal, including:

[0085] Starting from the moment of the first predetermined time Tm after the drive current switches to the second drive current I2, if the voltage value of the drive terminal continuously increases within the second predetermined time Tp, the Miller platform is determined to end.

[0086] According to the electromagnetic heating control device of the present invention, by monitoring the gate voltage of the power switch, it is possible to effectively determine whether the Miller period has ended, and avoids the need to set up an additional power switch voltage monitoring component.

[0087] Optionally, during the heating phase, in the drive cycle of the power switch, the control drive module provides a first drive voltage Va to the power switch to drive the power switch to operate in a saturated conduction state.

[0088] During the stop phase, the power switch is deactivated.

[0089] According to the electromagnetic heating control device of the present invention, during the heating stage, the power switch is operated in a saturated conduction state using a voltage-driven method. At this time, the conduction voltage between the collector (C) and emitter (E) of the power switch is reduced, thus decreasing the heat loss of the power switch. This protects the power switch while simultaneously storing energy for the LC oscillation circuit. During the shutdown stage, the power switch is deactivated, thereby enabling different heating duty cycles.

[0090] Optionally, an AC power supply is used to power the electromagnetic heating cooking appliance. The heating control device further includes a voltage zero-crossing detection module, which is used to detect the voltage zero-crossing signal of the AC power supply. The control drive module acquires the voltage zero-crossing signal and determines the starting point of the start-up phase based on the voltage zero-crossing signal.

[0091] According to the electromagnetic heating control device of the present invention, the starting point of the start-up stage is determined based on the zero-crossing point of the AC power supply, which can largely eliminate interference signals, thereby making the control more precise.

[0092] Optionally, the control drive module determines the time of the bias duration T0 before the voltage zero-crossing point as the starting point of the startup phase, and the startup phase continues until the end of the nth chopping cycle from the voltage zero-crossing point, where n is a non-negative integer.

[0093] According to the electromagnetic heating control device of the present invention, sufficient discharge time is given to the power switch tube when it is turned on, so as to avoid excessive current at the collector when the power switch tube is turned on.

[0094] Optionally, the bias duration T0 satisfies: 500μs≤T0≤5ms; and / or

[0095] n is equal to 1 or 0.

[0096] Optionally, the first drive current I1 satisfies: 10mA ≤ I1 ≤ 80mA; and / or

[0097] The second driving current I2 satisfies: 5mA≤I2≤60mA.

[0098] Optionally, the first driving voltage Va satisfies: 15V≤Va≤22V.

[0099] According to the electromagnetic heating control device of the present invention, a wider range of control parameters can be set to adapt to the performance of power switching transistors from different manufacturers.

[0100] Optionally, the control drive module includes:

[0101] A drive module, comprising the voltage source and the variable current source, is electrically coupled to the drive terminal of the power switch transistor for driving the power switch transistor; and

[0102] A control module is electrically coupled to the voltage detection module to acquire the voltage value at the drive terminal. The control module is also electrically coupled to the drive module and controls the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

[0103] Optionally, the control drive module includes:

[0104] The driving module includes the voltage source and the variable current source. The driving module is electrically coupled to the driving terminal of the power switch transistor for driving the power switch transistor. The driving module is also electrically coupled to the voltage detection module for acquiring the voltage value at the driving terminal.

[0105] A control module, electrically coupled to the drive module, is used to control the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

[0106] Optionally, the control drive module includes:

[0107] The main control module is used to acquire the target power;

[0108] The driving module includes the voltage source and the variable current source. The driving module is electrically coupled to the driving terminal of the power switch transistor for driving the power switch transistor. The driving module is also electrically coupled to the voltage detection module for acquiring the voltage value at the driving terminal.

[0109] A heating control module is electrically coupled to the main control module for receiving the target power. The heating control module is also electrically coupled to the drive module. The heating control module determines whether the target power is less than the threshold power and controls the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

[0110] According to the electromagnetic heating control device of the present invention, the specific configuration of the control unit and the drive unit can adopt various hardware structure forms, and the user can flexibly configure them according to specific needs.

[0111] A third aspect of the present invention provides an electromagnetic heating cooking appliance, characterized in that it includes the heating control device according to the above description.

[0112] According to the electromagnetic heating control cooking appliance of the present invention, when in low-power heating mode, the electromagnetic heating cooking appliance sequentially enters a start-up phase, a heating phase, and a stop phase in each control cycle. Specifically, in the start-up phase, a multi-segment drive current is used to conduct the power switching transistor, and the drive current is controlled by monitoring the voltage at the drive terminal of the power switching transistor, which effectively avoids hard start of the power switching transistor.

[0113] According to the electromagnetic heating cooking appliance of the present invention, during the startup phase, the drive current is adjusted by the voltage value fed back from the drive terminal of the power switch tube, driving the power switch tube to operate sequentially in the cutoff region, amplification region, and saturation region. During the Miller plateau region of the power switch tube's turn-on, the voltage at the drive terminal of the power switch tube is limited within a set range to restrict the switching current flowing through the power switch tube at the moment of turn-on, avoiding hard turn-on of the power switch tube. This achieves reliable millisecond-level duty cycle low-power continuous heating and variable-power heating, thereby improving cooking performance and enhancing user experience. Furthermore, the electromagnetic heating cooking appliance of the present invention can automatically adapt to power switch tubes from different manufacturers to achieve soft start-up without increasing cost or structural space, while also reducing electromagnetic interference and noise generated during electromagnetic heating startup.

[0114] Specifically, the electromagnetic heating cooking appliance is an induction cooker, an induction rice cooker, or an induction pressure cooker.

[0115] The electromagnetic heating control device according to the present invention can be widely used in a variety of electromagnetic heating cooking appliances. Attached Figure Description

[0116] The following drawings, which are part of this invention, are used to understand the invention. The drawings illustrate specific embodiments of the invention and their descriptions, serving to explain the principles of the invention.

[0117] In the attached image:

[0118] Figure 1This is a schematic diagram of the IGBT turn-on waveform mentioned in the background section.

[0119] Figure 2 This is a schematic diagram of the duty cycle power regulation waveform mentioned in the background art;

[0120] Figure 3 This is a schematic diagram showing the relationship between the collector voltage and collector current of a power switching transistor IGBT under different driving voltages.

[0121] Figure 4 This is a schematic block diagram of an electromagnetic heating device for an electromagnetic heating cooking appliance according to a preferred embodiment of the present invention;

[0122] Figure 5a This is a flowchart illustrating the operation of the electromagnetic heating device of an electromagnetic heating cooking appliance according to a preferred embodiment of the present invention.

[0123] Figure 5b for Figure 5a A flowchart of a preferred embodiment of controlling the switching of drive current based on voltage value in step S30;

[0124] Figure 6a and Figure 6b This is a timing diagram of the drive current of the power switch during the startup phase of the electromagnetic heating control method according to a preferred embodiment of the present invention.

[0125] Figure 7 The waveform diagram of an embodiment of the electromagnetic heating control method according to the present invention during low-power operation (4 / 5 heating duty cycle);

[0126] Figure 8 The waveform diagram of another embodiment of the electromagnetic heating control method according to the present invention during low power operation (3 / 5 heating duty cycle);

[0127] Figure 9 The waveform diagram for another embodiment of the electromagnetic heating control method according to the present invention during low-power operation (2 / 5 heating duty cycle);

[0128] Figure 10a The collector current I of the power switch during the startup phase when the electromagnetic heating control method according to a preferred embodiment of the present invention is used. C C-terminal voltage and G-terminal voltage V G Timing diagram;

[0129] Figure 10b When a constant voltage drive control method is used at the gate (G) of a power switch, the collector (C) current I during the startup phase of the power switch is measured. C C-terminal voltage and G-terminal voltage V GTiming diagram;

[0130] Figure 11 A schematic block diagram of an electromagnetic heating device for an electromagnetic heating cooking appliance according to yet another embodiment of the present invention; and

[0131] Figure 12 This is a schematic block diagram of an electromagnetic heating device for an electromagnetic heating cooking appliance according to another embodiment of the present invention. Detailed Implementation

[0132] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with embodiments of the invention.

[0133] To fully understand the embodiments of the present invention, a detailed process will be described below. Obviously, the implementation of the embodiments of the present invention is not limited to the specific details familiar to those skilled in the art.

[0134] This invention first provides an electromagnetic heating control device and heating control method for an electromagnetic heating cooking appliance, so as to realize low-power continuous heating and variable power heating, improve cooking effect and enhance user experience.

[0135] In a preferred embodiment of the invention, the electromagnetic heating device is applied in an electromagnetic heating cooking appliance, such as an electromagnetic heating rice cooker (or IH rice cooker). An electromagnetic heating rice cooker typically includes a lid and a pot body, with an inner pot inside the pot body, forming a cooking space when the lid is closed. The electromagnetic heating device of the electromagnetic heating cooking appliance is typically located within the pot body, for example, below the inner pot, for heating the inner pot.

[0136] like Figure 4 As shown, in a preferred embodiment of the present invention, the heating control device of the electromagnetic heating cooking appliance is powered by an AC power supply. The device includes an EMC electromagnetic compatibility module 10, a rectification and filtering module 20, an LC resonant module 30, a switching module 40, a voltage detection module 50, a drive module 60, a control module 70, and a zero-crossing detection module 80.

[0137] The EMC (Electromagnetic Compatibility) module 10 is coupled to the AC mains power supply to filter interference signals. The rectifier-filter module 20 rectifies and filters the AC mains power supply filtered by the EMC module 10 before providing DC power to the LC resonant module 30. The switching module 40 controls the LC resonant module to operate resonantly. The switching module 40 includes an IGBT (Inductively Coupled Transistor), which has a gate (G), a collector (C), and an emitter (E). The LC resonant module 30 is connected to the collector of the IGBT. The zero-crossing detection module 80 detects the zero-crossing signal of the AC mains power supply filtered by the EMC module 10. The drive module 60 is electrically coupled to the drive terminal of the IGBT. The drive module 60 functions as both a voltage source and a variable current source, capable of outputting both drive voltage and drive current to the IGBT. The voltage detection module 50 is electrically coupled at one end to the drive terminal of the IGBT and at the other end to the control module 70. It detects the voltage value at the drive terminal of the IGBT and transmits this voltage value to the control module 70 in real time. The control module 70 controls the operation of the drive module 60. Specifically, the control module 70 controls the drive module 60 to drive the power switching transistor IGBT based on the feedback voltage value at the IGBT drive terminal. The control module 70 also receives the voltage zero-crossing signal detected by the voltage zero-crossing detection module 80.

[0138] Figure 5a for Figure 4 A preferred operating procedure for the heating control device of the electromagnetic heating cooking appliance shown includes the following steps:

[0139] S10, the control module 70 obtains the target power Pt of the electromagnetic heating cooking appliance, and then executes step S20.

[0140] The target power Pt is the heating power that the electromagnetic heating cooking appliance aims to achieve in the current stage. For example, if a user wants to cook porridge, they can select the porridge function in the interactive module of the electromagnetic heating cooking appliance. The appliance will automatically enter the porridge cooking mode, in which it can heat at a power of 600W. Therefore, the target power Pt is 600W. Optionally, the target power of the electromagnetic heating cooking appliance can be in the range of 0-2500W, i.e., 0W ≤ Pt ≤ 2500W.

[0141] S20. Control module 70 determines whether the target power Pt is less than the threshold power Pd. If the target power Pt is less than the threshold power Pd, step S30 is executed; otherwise, step S40 is executed.

[0142] The threshold power Pd is a preset threshold value. When the target power Pt is greater than or equal to the threshold power Pd, the electromagnetic heating cooking appliance is determined to be in high-power heating mode and can be heated in the normal way, and step S40 is executed. When the target power Pt is less than the threshold power Pd, the electromagnetic heating cooking appliance is determined to be in low-power heating mode, and step S30 is executed.

[0143] Preferably, the threshold power Pd and the rated power P satisfy: 500W≤Pd≤2200W, (P-600W)≤Pd≤(P-100W).

[0144] S30. In each control cycle, the control module 70 controls the electromagnetic heating cooking appliance to sequentially enter the start-up phase, the heating phase, and the stop phase. During the start-up phase, in the drive cycle of the power switching transistor IGBT, the control module 70 provides a drive current to the power switching transistor IGBT through the drive module 60. This drive current includes a first drive current I1 and a second drive current I2. Simultaneously, the voltage detection module 50 monitors and acquires the voltage value V at the drive terminal of the power switching transistor. G The voltage value V G Finally, the feedback is sent to the control module 70, which controls the drive module 60 to switch the drive current from the first drive current I1 to the second drive current I2 based on the voltage value. During the drive cycle in the startup phase, the amplitude of the second drive current I2 increases between the lower threshold Ia and the upper threshold Ib of the drive current, while the amplitude of the first drive current I1 remains unchanged. Specifically, the lower threshold Ia is less than the upper threshold Ib (e.g., ...). Figure 6a and Figure 6b (As shown).

[0145] Specifically, during the startup phase, as the drive cycle increases, the amplitude of the second drive current I2 gradually increases from the lower threshold Ia to the upper threshold Ib. The increase in the second drive current I2 can be monotonically increasing (e.g., ...). Figure 6a As shown), they can also be equal in any two adjacent drive cycles (e.g. Figure 6bas shown), a plateau period of the current amplitude is formed. That is, in any two adjacent driving cycles of the power switch tube, the amplitude of the second driving current I2 in the latter driving cycle is greater than or equal to the amplitude of the second driving current I2 in the former driving cycle; the amplitude of the second driving current I2 in the last driving cycle of the power switch tube (which is the upper drive current threshold Ib, the value of which can be greater than the amplitude of the first driving current I1) is greater than the amplitude of the second driving current I2 in the first driving cycle (which is the lower drive current threshold Ia, the value of which can be less than the amplitude of the first driving current I1); the amplitude of the first driving current I1 remains unchanged. Within the variation range of the second driving current I2, the amplitude of the second driving current I2 may increase in an equal-difference manner, may increase in a non-equal-difference manner, or may increase according to other regular patterns.

[0146] Preferably, the lower drive current threshold Ia is 5 mA, the upper drive current threshold Ib is 60 mA, and 10 mA ≤ I1 ≤ 80 mA.

[0147] S40, the control module 70 controls the cooking appliance to operate in a high-power heating mode.

[0148] For example, a voltage driving mode is used to drive the IGBT to operate in a saturated conduction state, that is, normal turn-on.

[0149] In step S30, preferably, refer to Figure 5b , the control module 70 controls the driving module 60 to switch the driving current from the first driving current I1 to the second driving current I2 according to the voltage value at the driving end of the IGBT, which comprises the following steps:

[0150] S31, the control module 70 determines whether the voltage value V of the driving end G is greater than the first voltage threshold V1, if yes, step S32 is performed, if not, V continues to be monitored G until V G is greater than V1.

[0151] Preferably, Vth < V1 ≤ Vth + 4V, wherein Vth is the threshold voltage of the power switch tube, Vth is usually between 4V and 8V, and Vth values of IGBTs from different manufacturers or of different models may be different. Preferably, V1 is 7.5V.

[0152] When the driving end voltage V of the IGBT GWhen the voltage exceeds the IGBT's threshold voltage Vth, the IGBT sequentially transitions from the cutoff region (cutoff state) to the amplification region (amplification state) and then to the saturation region (saturation conduction state). Due to the Miller effect, a plateau region (Miller plateau) forms at the drive terminal voltage. After the Miller plateau / Miller period ends, the IGBT enters the saturation region. The Miller plateau is a typical characteristic of the IGBT in the amplification region. In the amplification region, the IGBT has high impedance; if the collector current is large at this time, the IGBT is easily burned out.

[0153] If the voltage value V G If the voltage is less than or equal to V1, then return to continue monitoring (acquiring) the voltage value V at the drive terminal. G And continue to judge V G Is it greater than V1?

[0154] S32, the control module 70 controls the drive module 60 to switch the drive current from the first drive current I1 to the second drive current I2, and then executes step S33.

[0155] During the startup phase, in the drive cycle of the power switching transistor, after the drive current switches to the second drive current I2, the heating control device of the electromagnetic heating cooking appliance according to the present invention further performs the following steps:

[0156] S33, the control module 70 determines the voltage value V at the drive terminal. G Determine if the Miller platform has terminated. If so, proceed to step S34; otherwise, continue monitoring V. G Until the Miller platform ends.

[0157] S34, Control module 70 determines the voltage value V at the drive end. G If the voltage is greater than the second voltage threshold V2, proceed to step S35; otherwise, continue monitoring V. G Until V G Greater than V2.

[0158] Preferably, V2 is 10.5V.

[0159] S35. Switch the driving mode of the power switch from current driving to voltage driving. The control module 70 provides the first driving voltage Va to the power switch through the driving module 60 to drive the power switch to work in the saturation conduction state.

[0160] Preferably, 15V ≤ Va ≤ 22V. Preferably, Va = 18V.

[0161] If the voltage value V at the driving end G If it is less than or equal to V2, then return and continue to obtain V. G And continue to judge the V drive G Is it greater than V2?

[0162] The following combination Figure 7 The heating control method of the electromagnetic heating cooking appliance according to the present invention in each drive cycle of the power switching tube is described in detail.

[0163] Figure 7 The waveforms in the image, from top to bottom, are: AC mains voltage waveform, IGBT collector voltage (Vc) waveform under low power conditions, IGBT gate drive level diagram under low power conditions, and IGBT gate current (I) during the IGBT drive cycle under low power conditions. G Waveform and IGBT gate voltage V during IGBT drive cycle at low power G Waveform.

[0164] It will be understood by those skilled in the art that when employing such Figure 4 When the electromagnetic heating device is shown, Vc exhibits an oscillating waveform during the period when the IGBT is driven to conduct. During the period when the IGBT is not conducting, Vc eventually remains at a stable high level (e.g., 305-310V), which is the rectified DC voltage value (e.g., ...). Figure 7 The waveform of the collector voltage Vc of the IGBT under medium and low power conditions is shown below. Figure 3 As shown, the gate drive voltage V of the IGBT G The higher the collector voltage (Vc), the larger the collector current (Ic). If the collector voltage (Vc) is the rectified DC voltage (e.g., 305-310V) at the instant the IGBT enters the conduction phase, then the gate drive voltage (Vc) before the IGBT enters the saturation conduction state needs to be increased. G The heating control method of the electromagnetic heating cooking appliance according to the present invention can solve this problem to a certain extent. This is to prevent the collector current Ic from becoming too large before the IGBT enters the saturation conduction state (e.g., in the amplification state), which would lead to excessive heat generation by the IGBT and affect its service life.

[0165] Continue to refer to Figure 7 In a preferred embodiment, the control cycle of the electromagnetic heating cooking appliance is 5 chopping durations. In each control cycle, the electromagnetic heating cooking appliance is controlled to sequentially enter the start-up phase, the heating phase, and the stop phase. Figure 7 In the embodiment shown, drive pulses are applied to the IGBT during the startup and heating phases, but no drive pulses are applied during the shutdown phase.

[0166] like Figure 7As shown, during the startup phase, in the IGBT's drive cycle (e.g., from ① to ② in the figure), a first drive current I1 is applied to the IGBT's drive terminal (the gate of the IGBT), driving the IGBT using current drive, while simultaneously monitoring the IGBT's drive terminal voltage V. G As time goes on, V G Gradually increase, when V G When the voltage exceeds the IGBT's threshold voltage Vth, the IGBT turns on. Then V... G Continue to rise, when V G When the voltage exceeds the first voltage threshold V1, the first drive current I1 is switched to the second drive current I2. Here, the first voltage threshold V1 is greater than the IGBT's threshold voltage Vth; that is, when the IGBT is driven by the first drive current I1, the drive current is switched to the second drive current I2 while ensuring the IGBT is already turned on.

[0167] When the second drive current I2 is used to drive the IGBT, the drive terminal voltage V of the IGBT is continuously monitored. G As time progresses, the driving terminal voltage V of the IGBT decreases. G Presenting the Miller platform, i.e., V G The voltage will not rise further. As time progresses, the IGBT enters a saturated conduction state after the Miller period ends (i.e., the Miller plateau ends). In the saturated conduction state, the IGBT can be driven using voltage drive mode. Therefore, after the Miller plateau ends, the IGBT's drive terminal voltage V continues to be monitored. G When V G When the voltage exceeds the second voltage threshold V2, the Miller plateau is considered to have ended. Then, the system switches from current drive mode to voltage drive mode and uses the first drive voltage Va to drive the IGBT to conduct normally, so that it can work in the saturated conduction state.

[0168] Typically, the threshold voltage Vth of a power switching transistor is between 4V and 8V. In a preferred embodiment of the present invention, the first voltage threshold V1 is less than or equal to Vth+4V, and the Miller plateau voltage of the IGBT is basically equivalent to V1. Therefore, in the present invention, at the instant the IGBT is turned on, the voltage value at the IGBT drive terminal can be controlled to not exceed 12V (preferably 7.5V), which can effectively control the collector current of the IGBT and avoid hard turn-on of the IGBT.

[0169] like Figure 10a As shown, when the heating method of the electromagnetic heating cooking appliance according to the present invention is used, the collector current Ic of the power switch tube can be controlled below 40A during the start-up phase. Figure 10b As shown, when a constant voltage source is used to drive the power switch, the maximum value of the collector current Ic of the power switch can reach 55A. Through... Figure 10aand Figure 10b The comparison shows that the electromagnetic heating control method of the present invention effectively reduces the C-pole current when the power switch is started, thus avoiding hard start of the power switch.

[0170] Understandably, when the IGBT's drive terminal voltage V G After the Miller platform ended, V G It will climb upwards, therefore, by continuously monitoring V G This allows for timely detection of the Miller cycle ending, enabling a prompt switch from current-driven to voltage-driven mode. This ensures the IGBT maintains a large collector current in saturated conduction, rapidly storing energy for the LC oscillation circuit. In saturated conduction, the on-state voltage between the collector and emitter of the power switch decreases, reducing heat loss and protecting the power switch while simultaneously storing energy for the LC oscillation circuit.

[0171] Understandably, detecting the IGBT's drive terminal voltage V G There are several specific methods to determine the end of the Miller plateau. For example, the end of the Miller plateau can be determined by detecting the drop in the C-terminal voltage of the IGBT to its lowest point, or by detecting the V value after the Miller period ends. G The climb determines the end of the Miller platform, or for example, by calculating V. G The changing second derivative to discover V G Inflection points on the curve, etc. For example... Figure 7 As shown, in a preferred embodiment of the present invention, starting from the moment of the first predetermined time Tm after the drive current switches to I2, the voltage value V at the drive terminal within the second predetermined time Tp... G If the rate of increase is continuous (i.e., continuously increasing), the Miller plateau is considered to have ended. The value of Tm matches the duration of the Miller period; preferably, 1μs ≤ Tm ≤ 18μs, and 300ns ≤ Tp ≤ 10μs. Furthermore, to ensure the IGBT enters saturation conduction upon the end of the Miller period, V... G The Miller period is considered to end when the voltage continuously climbs and reaches the second voltage threshold V2. The second voltage threshold V2 is preferably 10.5V.

[0172] According to the heating control method of the electromagnetic heating cooking appliance of the present invention, during the start-up phase, the driving current is adjusted by the voltage value fed back from the IGBT driving terminal, driving the IGBT sequentially through the cutoff region, amplification region, and saturation region. During the Miller period after the IGBT is turned on, the driving terminal voltage V is adjusted. GBy limiting the current at a low level to restrict the collector current of the IGBT during its amplification state, hard turn-on of the IGBT is avoided, enabling reliable millisecond-level duty cycle low-power continuous heating, thereby improving cooking results and enhancing the user experience. Furthermore, the heating control method for electromagnetic heating cooking appliances according to the present invention can automatically adapt to power switching transistors from different manufacturers to achieve soft start-up without increasing cost or structural space, while also reducing electromagnetic interference and noise generated during electromagnetic heating startup.

[0173] According to the heating control method of the electromagnetic heating cooking appliance of the present invention, in the start-up stage, the amplitude of the second driving current I2 generally increases with the driving cycle, and the amplitude of the driving current gradually increases, so that the cooking appliance can transition from the start-up stage to the heating stage relatively smoothly and reliably, and is less prone to damage.

[0174] like Figure 7 As shown, the heating control method of the electromagnetic heating cooking appliance according to the present invention further includes, during the heating phase, in the driving cycle of the power switch tube (e.g., the cycle from ③ to ④ in the figure), the control module 70 controls the drive module 60 to provide a first driving voltage Va to the driving terminal of the power switch tube to drive the power switch tube, so that it operates in a saturated conduction state; during the stopping phase, the power switch tube is made not to operate, for example, the control module 70 controls the drive module 60 not to provide a driving voltage or driving current to the power switch tube, or the control module 70 controls the output driving value of the drive module 60 to be 0. Preferably, 15V ≤ Va ≤ 22V. Preferably, Va = 18V. During the heating phase, the power switch tube is normally turned on.

[0175] Preferably, in the electromagnetic heating control method according to the present invention, the starting point of the start-up phase of the electromagnetic heating cooking appliance can be determined according to the zero-crossing point of the AC power supply.

[0176] like Figure 7As shown, the starting point of the startup phase is determined by the bias duration T0 before the zero-crossing point P0 of the AC power supply. The startup phase continues for n chopping cycles (if the AC frequency is 50Hz, the chopping cycle is 10ms) until time Pb. In other words, the startup phase is from time Pa to time Pb. That is, the startup phase starts from the bias duration T0 before the zero-crossing point P0 of the AC power supply and continues until the end of the nth chopping cycle from the zero-crossing point P0 of the AC power supply. Here, n is a positive integer, 500μs≤T0≤5ms. Preferably, T0=2.5ms, n=1. As can be seen from the above description of the heating control method for the startup phase, in the IGBT drive cycle of the startup phase, the soft-start process is to discharge the C-terminal voltage of the IGBT. The startup phase lasts for one chopping cycle to ensure sufficient discharge. However, depending on the device performance of different brands / models of IGBTs, n can also be set to 0, that is, the discharge time is only T0.

[0177] exist Figure 7 In the timing diagram shown, the complete control cycle consists of 5 chopping cycles, with the startup phase approximately 1 chopping cycle, the heating phase 3 chopping cycles, and the shutdown phase approximately 1 chopping cycle (the shutdown phase of the previous control cycle and the startup phase of the next control cycle total 2 chopping cycles). The IGBT is turned on during the startup and heating phases, therefore... Figure 7 The diagram shows the case with a 4 / 5 heating duty cycle. During the startup phase, the IGBT performs soft start and normal turn-on sequentially within its drive cycle; therefore, the startup phase is also called the half-drive phase. During the heating phase, the IGBT is normally turned on; therefore, the heating phase is also called the full-drive phase. In this paper, the number of chopping cycles n during the startup phase is also referred to as the startup chopping cycle number n.

[0178] It should be noted that, in the heating control method of the electromagnetic heating cooking appliance according to the present invention, the zero-crossing point of the AC power supply is used to determine both the starting point of the start-up phase and the switching point between the start-up phase and the heating phase, as well as the switching point between the heating phase and the stop phase. For example... Figure 7 As shown, the start-up phase lasts approximately one chopping cycle and ends at the zero-crossing point of the AC power supply voltage; the heating phase begins and ends at the zero-crossing point of the AC power supply voltage, lasting for three chopping cycles. Determining the start point of each phase based on the zero-crossing point of the AC power supply voltage can largely eliminate interference signals and is more conducive to achieving precise control of electromagnetic heating cooking appliances.

[0179] Figure 8 and Figure 9 A timing diagram of another embodiment of the electromagnetic heating control method according to the present invention is shown. Figure 8and Figure 9 The implementation methods shown are the same as Figure 7 The only difference in the illustrated implementation is the duration of the heating and stopping phases. Figure 8 In the embodiment shown, the complete control cycle is 5 chopping cycles, while the heating phase lasts for 2 chopping cycles. Therefore Figure 8 The embodiment shown illustrates a 3 / 5 heating duty cycle. Figure 9 In the embodiment shown, the complete control cycle is 5 chopping cycles, while the heating phase lasts for 1 chopping cycle. Therefore Figure 9 The embodiment shown is for a 2 / 5 heating duty cycle.

[0180] Therefore, the heating control method of the electromagnetic heating cooking appliance according to the present invention can not only realize low-power continuous heating, but also realize low-power variable-power heating by adjusting the duty cycle of the start-up stage and the heating stage.

[0181] It should be pointed out that, Figure 7-9 This is merely a timing diagram illustrating an embodiment of the electromagnetic heating control method according to the present invention. The depiction of the amplitude and duration of the waveforms for each parameter in the diagram is for illustrative purposes only and does not imply any limitation on the amplitude, duration, or relationships between the waveforms of each parameter. For example, Figure 7-9 The amplitude of the second driving current I2 is less than that of I1. This is only used to indicate that the second driving current I2 is different from the first driving current I1, and is not intended to limit the second driving current I2 to necessarily being less than the first driving current I1. For example, the second driving current I2 can also be greater than the first driving current I1. Furthermore, the amplitude of the second driving current I2 can be the same or different in different driving cycles. Figure 7-9 As shown, each chopping cycle (10ms when the AC power frequency is 50Hz) contains multiple drive cycles. Within the same drive cycle, under microsecond-level cycle control, the amplitudes of the first drive current I1 and the second drive current I2 are essentially constant.

[0182] Figure 11 Another embodiment of the heating device of an electromagnetic heating cooking appliance according to the present invention is shown. In this embodiment, with... Figure 4 The embodiment shown differs in that one end of the voltage detection module 50 is electrically coupled to the driving terminal of the IGBT, and the other end is electrically coupled to the driving module 60. It is used to detect the voltage value at the driving terminal of the IGBT and transmit this voltage value to the driving module 60 in real time. The control module 70 controls the driving module 60 to drive the power switching transistor according to the voltage value at the driving terminal of the IGBT.

[0183] Figure 12Another embodiment of the heating device of an electromagnetic heating cooking appliance according to the present invention is shown. In this embodiment, with... Figure 11 The implementation shown differs in that the control unit includes a heating control module 70A and a main control module 70B. The zero-crossing detection module 80 transmits the voltage zero-crossing signal of the AC power supply to the heating control module 70A. The main control module 70B sends control signals to the heating control module 70A and makes corresponding adjustments based on the real-time feedback information from the heating control module 70A. The main control module 70B acquires the target power Pt of the electromagnetic heating cooking appliance and sends the target power Pt, threshold power Pd, bias duration T0, and number of start-up chopping cycles n to the heating control module 70A. The heating control module 70A determines whether the target power Pt is less than the threshold power Pd. When the target power Pt is less than the threshold power Pd, the heating control module 70A controls the drive module 60 to drive the power switching transistor according to the voltage value at the drive end and the voltage zero-crossing signal.

[0184] Figure 4 and Figure 11 The drive module 60 and control module 70 can be collectively referred to as the control drive module. Figure 12 The drive module 60, heating control module 70A, and main control module 70B can also be collectively referred to as the control drive module.

[0185] The present invention also provides an electromagnetic heating cooking appliance, which includes the heating control device of the electromagnetic heating cooking appliance described above and adopts the electromagnetic heating control method described above.

[0186] The electromagnetic heating cooking appliance according to the present invention can be an induction cooker, an electromagnetic heating rice cooker, or an electromagnetic heating pressure cooker, etc.

[0187] The aforementioned electromagnetic heating cooking appliances can obviously include the various features of the aforementioned heating control device, and can solve the corresponding technical problems and have the corresponding effects.

[0188] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for descriptive purposes only and is not intended to limit the scope of the invention.

[0189] The present invention has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the present invention to the described embodiments. Those skilled in the art will understand that many variations and modifications can be made based on the teachings of the present invention, and all such variations and modifications fall within the scope of protection claimed by the present invention.

Claims

1. A heating control method for an electromagnetic heating cooking appliance, the electromagnetic heating cooking appliance comprising a resonant heating circuit and a power switching transistor, characterized in that, Includes the following steps: Obtain the target power of the electromagnetic heating cooking appliance; Determine whether the target power is less than the threshold power; If the target power is less than the threshold power, the electromagnetic heating cooking appliance is controlled to sequentially enter the start-up phase, the heating phase, and the stop phase in each control cycle, wherein, in the start-up phase: During the drive cycle of the power switch, a drive current is provided to the power switch, the drive current including a first drive current I1 and a second drive current I2; Obtain the voltage value at the drive terminal of the power switch transistor; and The driving current is controlled to switch from the first driving current I1 to the second driving current I2 based on the voltage value at the driving terminal. Wherein, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than or equal to the amplitude of the second driving current I2 in the previous driving cycle. The amplitude of the second drive current I2 in the last drive cycle is greater than the amplitude of the second drive current I2 in the first drive cycle; The amplitude of the first driving current I1 remains unchanged.

2. The heating control method according to claim 1, characterized in that, In any two adjacent drive cycles of the power switch, the amplitude of the second drive current I2 in the later drive cycle is greater than the amplitude of the second drive current I2 in the previous drive cycle.

3. The heating control method according to claim 1, characterized in that, The amplitude of the second drive current I2 in the first drive cycle of the power switch is less than the amplitude of the first drive current I1; and / or The amplitude of the second drive current I2 in the last drive cycle of the power switch is greater than the amplitude of the first drive current I1.

4. The heating control method according to claim 1, characterized in that, The step of controlling the drive current to switch from the first drive current I1 to the second drive current I2 based on the voltage value at the drive terminal includes: Determine whether the voltage value at the drive terminal is greater than a first voltage threshold, wherein the first voltage threshold is greater than the threshold voltage of the power switch transistor; If the voltage value at the drive terminal is greater than the first voltage threshold, the drive current is controlled to switch from the first drive current I1 to the second drive current I2.

5. The heating control method according to claim 4, characterized in that, The heating control method further includes: After the drive current is switched to the second drive current I2, the Miller platform is determined to have ended based on the voltage value at the drive terminal. If the Miller platform has ended, determine whether the voltage value at the drive end is greater than the second voltage threshold. If the voltage value at the driving terminal is greater than the second voltage threshold, the driving mode of the power switch is switched from current driving to voltage driving, and a first driving voltage Va is provided to the power switch to drive the power switch so that it operates in the saturated conduction state.

6. The heating control method according to claim 5, characterized in that, The step of determining whether the Miller platform has ended based on the voltage value at the drive end includes: Starting from the moment of the first predetermined time Tm after the drive current switches to the second drive current I2, if the voltage value of the drive terminal continuously increases within the second predetermined time Tp, the Miller platform is determined to end.

7. The heating control method according to claim 1, characterized in that, During the heating phase, in the driving cycle of the power switch, a first driving voltage Va is provided to the power switch to drive the power switch to operate in the saturated conduction state. During the stop phase, the power switch is deactivated.

8. The heating control method according to any one of claims 1-7, characterized in that, The electromagnetic heating cooking appliance is powered by an AC power source, and the heating control method further includes: Obtain the zero-crossing signal of the AC power supply; The starting point of the startup phase is determined based on the voltage zero-crossing signal.

9. The heating control method according to claim 8, characterized in that, Determining the starting point of the startup phase based on the voltage zero-crossing signal includes: The time of bias duration T0 before the voltage zero-crossing point is determined as the starting point of the startup phase, and the startup phase continues until the end of the nth chopping cycle from the voltage zero-crossing point, where n is a non-negative integer.

10. The heating control method according to claim 9, characterized in that, The bias duration T0 satisfies: 500μs≤T0≤5ms; and / or n is equal to 1 or 0.

11. The heating control method according to any one of claims 1-7, characterized in that, The first drive current I1 satisfies: 10mA ≤ I1 ≤ 80mA; and / or The second driving current I2 satisfies: 5mA≤I2≤60mA.

12. The heating control method according to any one of claims 5-7, characterized in that, The first driving voltage Va satisfies: 15V≤Va≤22V.

13. A heating control device for an electromagnetic heating cooking appliance, the electromagnetic heating cooking appliance comprising a resonant heating circuit, characterized in that, The heating control device includes: A power switching transistor is used to control the resonant operation of the resonant heating circuit, and the power switching transistor includes a driving terminal. A voltage detection module, one end of which is electrically coupled to the drive terminal of the power switch transistor to detect the voltage value at the drive terminal; and A control drive module, comprising a voltage source and a variable current source, is electrically coupled to the drive terminal of the power switch and to the other end of the voltage detection module, to drive the power switch according to the voltage value at the drive terminal. The control drive module performs the following operations: Obtain the target power of the electromagnetic heating cooking appliance; Determine whether the target power is less than the threshold power; If the target power is less than the threshold power, in each control cycle, the control drive module controls the electromagnetic heating cooking appliance to sequentially enter the start-up phase, the heating phase, and the stop phase, wherein, in the start-up phase: During the drive cycle of the power switch, the control drive module provides a drive current to the power switch, the drive current including a first drive current I1 and a second drive current I2. The control drive module acquires the voltage value at the drive terminal of the power switch; and The control drive module switches the drive current from the first drive current I1 to the second drive current I2 according to the voltage value at the drive terminal. Wherein, in any two adjacent driving cycles of the power switch, the amplitude of the second driving current I2 in the later driving cycle is greater than or equal to the amplitude of the second driving current I2 in the previous driving cycle. The amplitude of the second drive current I2 in the last drive cycle is greater than the amplitude of the second drive current I2 in the first drive cycle. The amplitude of the first driving current I1 remains unchanged.

14. The heating control device according to claim 13, characterized in that, In any two adjacent drive cycles of the power switch, the amplitude of the second drive current I2 in the later drive cycle is greater than the amplitude of the second drive current I2 in the previous drive cycle.

15. The heating control device according to claim 13, characterized in that, The amplitude of the second drive current I2 in the first drive cycle of the power switch is less than the amplitude of the first drive current I1; and / or The amplitude of the second drive current I2 in the last drive cycle of the power switch is greater than the amplitude of the first drive current I1.

16. The heating control device according to claim 13, characterized in that, The control drive module switches the drive current from the first drive current I1 to the second drive current I2 according to the voltage value at the drive terminal, including: The control drive module determines whether the voltage value at the drive terminal is greater than a first voltage threshold, wherein the first voltage threshold is greater than the threshold voltage of the power switch. If the voltage value at the drive terminal is greater than the first voltage threshold, the control drive module switches the drive current from the first drive current I1 to the second drive current I2.

17. The heating control device according to claim 16, characterized in that, After the drive current is switched to the second drive current I2, the control drive module determines whether the Miller platform has ended based on the voltage value at the drive terminal. If the Miller platform has ended, the control drive module determines whether the voltage value at the drive end is greater than the second voltage threshold. If the voltage value at the driving terminal is greater than the second voltage threshold, the driving mode of the power switch is switched from current driving to voltage driving. The control driving module provides a first driving voltage Va to the power switch to drive the power switch to operate in the saturated conduction state.

18. The heating control device according to claim 17, characterized in that, The control drive module determines whether the Miller platform has ended based on the voltage value at the drive terminal, including: Starting from the moment of the first predetermined time Tm after the drive current switches to the second drive current I2, if the voltage value of the drive terminal continuously increases within the second predetermined time Tp, the Miller platform is determined to end.

19. The heating control device according to claim 13, characterized in that, During the heating phase, in the drive cycle of the power switch, the control drive module provides a first drive voltage Va to the power switch to drive the power switch to operate in a saturated conduction state. During the stop phase, the power switch is deactivated.

20. The heating control device according to any one of claims 13-19, characterized in that, The electromagnetic heating cooking appliance is powered by an AC power supply. The heating control device also includes a voltage zero-crossing detection module, which is used to detect the voltage zero-crossing signal of the AC power supply. The control drive module acquires the voltage zero-crossing signal and determines the starting point of the start-up phase based on the voltage zero-crossing signal.

21. The heating control device according to claim 20, characterized in that, The control drive module determines the time of the bias duration T0 before the voltage zero-crossing point as the starting point of the startup phase. The startup phase lasts until the end of the nth chopping cycle from the voltage zero-crossing point, where n is a non-negative integer.

22. The heating control device according to claim 21, characterized in that, The bias duration T0 satisfies: 500μs≤T0≤5ms; and / or n is equal to 1 or 0.

23. The heating control device according to any one of claims 13-19, characterized in that, The first drive current I1 satisfies: 10mA ≤ I1 ≤ 80mA; and / or The second driving current I2 satisfies: 5mA≤I2≤60mA.

24. The heating control device according to any one of claims 17-19, characterized in that, The first driving voltage Va satisfies: 15V≤Va≤22V.

25. The heating control device according to any one of claims 13-19, characterized in that, The control drive module includes: A drive module, comprising the voltage source and the variable current source, is electrically coupled to the drive terminal of the power switch transistor for driving the power switch transistor; and A control module is electrically coupled to the voltage detection module to acquire the voltage value at the drive terminal. The control module is also electrically coupled to the drive module and controls the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

26. The heating control device according to any one of claims 13-19, characterized in that, The control drive module includes: The driving module includes the voltage source and the variable current source. The driving module is electrically coupled to the driving terminal of the power switch transistor for driving the power switch transistor. The driving module is also electrically coupled to the voltage detection module for acquiring the voltage value at the driving terminal. A control module, electrically coupled to the drive module, is used to control the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

27. The heating control device according to any one of claims 13-19, characterized in that, The control drive module includes: The main control module is used to acquire the target power; The driving module includes the voltage source and the variable current source. The driving module is electrically coupled to the driving terminal of the power switch transistor for driving the power switch transistor. The driving module is also electrically coupled to the voltage detection module for acquiring the voltage value at the driving terminal. A heating control module is electrically coupled to the main control module for receiving the target power. The heating control module is also electrically coupled to the drive module. The heating control module determines whether the target power is less than the threshold power and controls the drive module to drive the power switch transistor according to the voltage value at the drive terminal.

28. An electromagnetic heating cooking appliance, characterized in that, Includes the heating control device according to any one of claims 13-27.

29. The electromagnetic heating cooking appliance according to claim 28, characterized in that, The electromagnetic heating cooking appliance is an induction cooker, an electromagnetic heating rice cooker, or an electromagnetic heating pressure cooker.

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