CN115278968A

CN115278968A - Heating control method and device and electromagnetic heating cooking appliance

Info

Publication number: CN115278968A
Application number: CN202110866699.XA
Authority: CN
Inventors: 朱春生; 李泽涌; 陈建化; 曹凯
Original assignee: Zhejiang Supor Electrical Appliances Manufacturing Co Ltd
Current assignee: Zhejiang Supor Electrical Appliances Manufacturing Co Ltd
Priority date: 2021-04-30
Filing date: 2021-07-29
Publication date: 2022-11-01

Abstract

The invention discloses a heating control method and device and an electromagnetic heating cooking appliance. The method comprises the following steps: acquiring target power of an electromagnetic heating cooking appliance; judging whether the target power is smaller than the threshold power; if the target power is smaller than the threshold power, controlling the electromagnetic heating cooking appliance to sequentially enter a starting stage, a heating stage and a stopping stage in each control period, wherein in the starting stage, in a driving period of the power switch tube, a driving current is provided for 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 at the same time, the driving current is controlled to be switched from I1 to I2 according to the voltage value, the I1 is in a decreasing trend as the driving period increases, and the I2 is in an increasing trend as the driving period increases. The invention adopts multi-section driving current to conduct the power switch tube, can effectively reduce C pole current when the power switch tube is switched on, and avoids hard start.

Description

Heating control method and device and electromagnetic heating cooking appliance

Technical Field

The invention relates to the technical field of cooking appliances, in particular to a heating control method and device of an electromagnetic heating cooking appliance and the electromagnetic heating cooking appliance.

Background

Electromagnetic induction heating (alternatively referred to as IH heating, electromagnetic heating) cooking appliances generally include a resonant heating circuit (alternatively referred to as LC oscillating circuit), which is typically turned on and off using a power switch IGBT.

Current IH cooking utensil, in order to guarantee the culinary art effect, often need heat with low power in the culinary art process to realize accurate firepower control and culinary art. To provide the low power required, the following are commonly used:

first, the driving pulse width is adjusted to achieve the purpose of power adjustment. When the pulse width is adjusted to be small, the power is reduced, and when the pulse width is adjusted to be large, the power is increased. However, the method cannot realize full-range low power, such as rated power 1200W, and the pulse width cannot reach 400W, because the IGBT has a hard turn-on phenomenon under the low power condition, the IGBT is easily burned out. For example, referring to fig. 1, when the power is gradually reduced from 1200W to 300W, the turn-on voltage of the power switch tube increases, which results in an increase in the starting current (see fig. 3, a graph of the relationship between the C voltage and the C electrode current of the power switch tube IGBT under different driving voltages), thereby easily causing the IGBT to burn out.

And secondly, regulating the rated power duty ratio to obtain low power. Such as a rated power of 1200W, a duty ratio of 6S/4S, a heating time of 6S, a stopping time of 4S and a period of 10S, and 720W (1200W multiplied by 6/10) of average power is obtained (see figure 2). When the method is adopted, the cooking effect is influenced if the heating period is long, and the IGBT is turned on hard if the heating period is short, so that the IGBT is burnt out.

And thirdly, chopping at the zero crossing point of the alternating current end, for example, adding a silicon controlled rectifier to control zero-crossing wave loss. The method can increase high-power switch control, increase cost, increase structural space and reduce reliability.

And fourthly, a voltage transformation unit is added, low-voltage pulse driving is carried out in the initial stage, and high-voltage pulse driving is carried out in the heating stage, so that starting pulse current can be inhibited, and low power is realized. However, the method has low reliability, easily causes the power device to be damaged, and cannot automatically adjust and adapt to the driving voltage because the circuit loss is large, the timeliness requirement is high, and the requirement on the consistency of the power device is high.

Therefore, there is a need for an electromagnetic heating control method to at least partially solve the above problems.

Disclosure of Invention

A series of concepts in a simplified form are introduced in the summary section, which is described in further detail in the detailed description section. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

To at least partially solve the problems in the background art, a first aspect of the present invention provides a heating control method for an electromagnetic heating cooking appliance including an LC resonant circuit and a power switch tube, wherein the method includes the steps of:

acquiring target power of the electromagnetic heating cooking appliance;

judging whether the target power is smaller than a threshold power;

if the target power is smaller than the threshold power, controlling the electromagnetic heating cooking appliance to enter a starting phase, a heating phase and a stopping phase in sequence in each control period, wherein in the starting phase:

in a driving period of the power switch tube, providing a driving current to the power switch tube, wherein the driving current comprises a first driving current I1 and a second driving current I2;

acquiring a voltage value of a driving end of the power switch tube; and is

Controlling the driving current to be switched from the first driving current I1 to the second driving current I2 according to the voltage value of the driving terminal,

in any two adjacent driving periods of the power switch tube, the amplitude of the first driving current I1 in the following driving period is smaller than or equal to the amplitude of the first driving current I1 in the previous driving period;

the amplitude of the first driving current I1 in the last driving period is smaller than the amplitude of the first driving current I1 in the first driving period;

in any two adjacent driving periods of the power switch tube, the amplitude of the second driving current I2 in the following driving period is greater than or equal to the amplitude of the second driving current I2 in the previous driving period;

the magnitude of the second driving current I2 in the last one of the driving periods is larger than the magnitude of the second driving current I2 in the first one of the driving periods.

According to the electromagnetic heating control method of the present invention, when in the low power heating mode, the electromagnetic heating cooking appliance is controlled to enter the start-up phase, the heating phase and the stop phase in turn in each control period. In the starting stage, the power switch tube is switched on by adopting a plurality of sections of driving currents, and the driving currents are controlled by monitoring the voltage of the driving end of the power switch tube, so that the hard starting of the power switch tube can be effectively avoided.

In all the driving periods of the starting stage, the first driving current I1 is in a decreasing trend, the second driving current I2 is in an increasing trend, and the amplitude of the driving current is gradually changed, so that the cooking appliance can be smoothly and reliably transited from the starting stage to the heating stage, and the cooking appliance is not easy to damage.

Optionally, in the same driving period of the power switch tube, the amplitude of the first driving current I1 is greater than the amplitude of the second driving current I2.

According to the electromagnetic heating control method, the amplitude of the first driving current I1 is larger than the amplitude of the second driving current I2, so that the driving end voltage of the power switch tube can be quickly increased, and the power switch tube can be quickly in a working state.

Optionally, in any two adjacent driving periods of the power switch tube, wherein,

the amplitude of the first driving current I1 in the subsequent driving period is smaller than the amplitude of the first driving current I1 in the previous driving period; and/or

The magnitude of the second driving current I2 in the subsequent driving period is larger than the magnitude of the second driving current I2 in the previous driving period.

According to the electromagnetic heating control method, the amplitude of the first driving current I1 and/or the amplitude of the second driving current I2 can be regularly controlled to be monotonously changed in all driving cycles of the starting stage, and the control scheme is easy to implement.

Optionally, the controlling of the driving current to be switched from the first driving current I1 to the second driving current I2 according to the voltage value of the driving terminal includes:

judging whether the voltage value of the driving end is larger than a first voltage threshold value or not, wherein the first voltage threshold value is larger than the threshold voltage of the power switch tube;

controlling the driving current to be switched from the first driving current I1 to the second driving current I2 if the voltage value of the driving terminal is greater than the first voltage threshold.

According to the electromagnetic heating control method, when in a low-power heating mode, in a starting stage, the driving current is adjusted through the voltage value fed back by the driving end of the power switch tube, the power switch tube is driven to work in a cut-off region, an amplification region and a saturation region in sequence, and the voltage of the driving end of the power switch tube is limited within a set range in a Mi Leping switching region of the power switch tube, so that the switching current flowing through the power switch tube at the moment when the power switch tube is switched on is limited, the power switch tube is prevented from being switched on hard, reliable millisecond-level duty ratio low-power continuous heating and variable power heating are realized, the cooking effect is improved, and the user experience is improved. In addition, according to the electromagnetic heating control method, the power switching tubes of different manufacturers can be automatically adapted to realize soft start, the cost and the structural space are not increased, and meanwhile, the electromagnetic interference and the noise generated by electromagnetic heating start can be reduced.

Optionally, the heating control method further comprises:

after the driving current is switched to the second driving current I2, judging whether the Miller platform is finished or not according to the voltage value of the driving end;

if the Miller platform is finished, judging whether the voltage value of the driving end is greater than a second voltage threshold value;

if the voltage value of the driving end is larger than the second voltage threshold, the driving mode of the power switch tube is switched from current driving to voltage driving, and a first driving voltage Va is provided for the power switch tube so as to drive the power switch tube to work in a saturation conducting state.

According to the electromagnetic heating control method, in the starting stage, after the Miller period of the power switching tube is finished, the voltage driving mode is adopted to enable the power switching tube to work in a saturated conduction state, at the moment, the conduction voltage between the C pole and the E pole of the power switching tube is reduced, the heat loss of the power switching tube is reduced, and the power switching tube can be protected while energy storage of an LC oscillating circuit is realized.

Optionally, the determining whether the miller platform is finished according to the voltage value at the driving end includes:

when the voltage value of the driving terminal continuously increases within the second predetermined period Tp from the time of the first predetermined period Tm after the driving current is switched to the second driving current I2, it is determined that the miller stage is finished.

According to the electromagnetic heating control method, whether the Miller period is finished or not can be effectively judged by monitoring the G-pole voltage of the power switch tube, and an additional arrangement of a C-pole voltage monitoring component of the power switch tube is avoided.

Optionally, in the heating phase, in a driving period of the power switch tube, providing a first driving voltage Va to the power switch tube to drive the power switch tube to operate in a saturated conducting state;

and in the stopping phase, the power switch tube is not operated.

According to the electromagnetic heating control method, in the heating stage, the power switching tube is enabled to work in a saturated conduction state by adopting a voltage driving mode, at the moment, the conduction voltage between the C pole and the E pole of the power switching tube is reduced, the heat loss of the power switching tube is reduced, and the power switching tube can be protected while energy storage of an LC oscillating circuit is realized. And in the stopping stage, the power switch tube does not work, so that different heating duty ratios can be realized.

Optionally, an alternating current power supply is used to supply power to the electromagnetic heating cooking appliance, and the heating control method further includes:

acquiring a voltage zero-crossing signal of the alternating current power supply;

and determining the starting point of the starting stage according to the voltage zero-crossing point signal.

According to the electromagnetic heating control method, the starting point of the starting stage is determined according to the voltage zero crossing point of the alternating current power supply, so that interference signals can be eliminated to a greater extent, and the control is more accurate.

Optionally, the determining the starting point of the start-up phase according to the voltage zero-crossing point includes:

determining a time offset by a time period T0 before the voltage zero-crossing time as a starting point of the startup phase, the startup phase lasting to an end of an nth chopping cycle from the voltage zero-crossing time, where n is a non-negative integer.

According to the electromagnetic heating control method, sufficient discharge time is provided for the power switch tube when the power switch tube is switched on, and overlarge C pole current is avoided when the power switch tube is switched on.

Optionally, the offset duration T0 satisfies: t0 is more than or equal to 500 mu s and less than or equal to 5ms; and/or

n is equal to 1 or 0.

Optionally, the first driving current I1 satisfies: i1 is more than or equal to 10mA and less than or equal to 80mA; and/or

The second driving current I2 satisfies: i2 is more than or equal to 5mA and less than or equal to 60mA.

Optionally, the first driving voltage Va satisfies: va is more than or equal to 15V and less than or equal to 22V.

According to the electromagnetic heating control method, a wider control parameter range can be set so as to adapt to the performance of power switching tubes of different manufacturers.

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

the power switch tube is used for controlling the resonance operation of the resonance heating circuit and comprises a driving end;

a voltage detection module, one end of which is electrically coupled to the driving end of the power switch tube to detect a voltage value of the driving end; and

a control driving module including a voltage source and a variable current source, the control driving module being electrically coupled to the driving terminal of the power switching transistor and to the other end of the voltage detection module to drive the power switching transistor according to the voltage value at the driving terminal,

wherein the control drive module performs the following operations:

acquiring target power of the electromagnetic heating cooking appliance;

judging whether the target power is smaller than a threshold power;

if the target power is smaller than the threshold power, the control driving module controls the electromagnetic heating cooking appliance to enter a starting stage, a heating stage and a stopping stage in sequence in each control period, wherein in the starting stage:

in a driving period of the power switch tube, the control driving module provides driving currents to the power switch tube, and the driving currents comprise a first driving current I1 and a second driving current

The current I2 is driven;

the control driving module acquires the voltage value of the driving end of the power switch tube; and is

The control driving module switches the driving current from the first driving current I1 to the second driving current I2 according to the voltage value of the driving terminal,

in any two adjacent driving periods of the power switching tube, the amplitude of the first driving current I1 in the following driving period is smaller than or equal to the amplitude of the first driving current I1 in the previous driving period;

the amplitude of the second driving current I2 in the last driving period is larger than the amplitude of the second driving current I2 in the first driving period;

in the same driving period of the power switch tube, the amplitude of the first driving current I1 is smaller than the amplitude of the second driving current I2.

According to the electromagnetic heating control device of the invention, when in the low-power heating mode, the electromagnetic heating cooking appliance is controlled to sequentially enter the starting phase, the heating phase and the stopping phase in each control period. In the starting stage, the power switch tube is switched on by adopting a plurality of sections of driving currents, and the driving currents are controlled by monitoring the voltage of the driving end of the power switch tube, so that the hard starting of the power switch tube can be effectively avoided.

Optionally, in any two adjacent driving periods of the power switching tube, the amplitude of the first driving current I1 in the following driving period is smaller than the amplitude of the first driving current I1 in the previous driving period.

According to the electromagnetic heating control device, the amplitude of the first driving current I1 can be regularly controlled to be monotonically decreased in all driving cycles of the starting stage, and the control scheme is easy to implement.

Optionally, in any two adjacent driving periods of the power switching tube, the magnitude of the second driving current I2 in the following driving period is greater than the magnitude of the second driving current I2 in the previous driving period.

According to the electromagnetic heating control device, the amplitude of the second driving current I2 can be regularly controlled to be monotonically increased in all driving periods in the starting stage, and the control scheme is easy to implement.

Optionally, the controlling the driving module to switch the driving current from the first driving current I1 to the second driving current I2 according to the voltage value of the driving end includes:

the control driving module judges whether the voltage value of the driving end is larger than a first voltage threshold value or not, wherein the first voltage threshold value is larger than the threshold voltage of the power switch tube;

if the voltage value of the driving end is larger than the first voltage threshold, the control driving module switches the driving current from the first driving current I1 to the second driving current I2.

According to the electromagnetic heating control device, when in a low-power heating mode, in a starting stage, the driving current is adjusted through the voltage value fed back by the driving end of the power switch tube, the power switch tube is driven to work in a cut-off region, an amplification region and a saturation region in sequence, and the voltage of the driving end of the power switch tube is limited within a set range in a Mi Leping switching region of the power switch tube, so that the switching current flowing through the power switch tube at the moment when the power switch tube is switched on is limited, the power switch tube is prevented from being switched on hard, reliable millisecond-level duty ratio low-power continuous heating and variable power heating are realized, the cooking effect is improved, and the user experience is improved. In addition, according to the electromagnetic heating control method, the power switching tubes of different manufacturers can be automatically adapted to realize soft start, the cost and the structural space are not increased, and meanwhile, the electromagnetic interference and the noise generated by electromagnetic heating start can be reduced.

Optionally, after the driving current is switched to the second driving current I2, the control driving module determines whether the miller platform is finished according to the voltage value of the driving end;

if the Miller platform is finished, the control driving module judges whether the voltage value of the driving end is greater than a second voltage threshold value;

if the voltage value of the driving end is larger than the second voltage threshold, the driving mode of the power switch tube is switched from current driving to voltage driving, and the control driving module provides a first driving voltage Va for the power switch tube to drive the power switch tube to work in a saturation conducting state.

According to the electromagnetic heating control device of the present invention, in the startup phase, after the miller period of the power switching tube is over, the power switching tube is operated in the saturated conduction state in the voltage driving mode, and at this time, the conduction voltage between the C pole and the E pole of the power switching tube is reduced, so that the heat loss of the power switching tube is reduced, and the power switching tube can be protected while realizing the energy storage of the LC oscillation circuit.

Optionally, the controlling and driving module determines whether the miller platform is finished according to the voltage value of the driving end, including:

According to the electromagnetic heating control device, whether the Miller period is finished or not can be effectively judged by monitoring the G-pole voltage of the power switch tube, and an additional arrangement of a C-pole voltage monitoring component of the power switch tube is avoided.

Optionally, in the heating phase, in a driving period of the power switching tube, the control driving module provides a first driving voltage Va to the power switching tube to drive the power switching tube to operate in a saturated conducting state;

and in the stopping stage, the power switch tube does not work.

According to the electromagnetic heating control device, in the heating stage, the power switching tube is enabled to work in a saturated conduction state by adopting a voltage driving mode, at the moment, the conduction voltage between the C pole and the E pole of the power switching tube is reduced, the heat loss of the power switching tube is reduced, and the power switching tube can be protected while energy storage of an LC oscillating circuit is realized. And the power switch tube does not work in the stopping stage, so that different heating duty ratios can be realized.

Optionally, an alternating current power supply is used for supplying power to the electromagnetic heating cooking appliance, the heating control device further includes a voltage zero-crossing detection module, the voltage zero-crossing detection module is used for detecting a voltage zero-crossing signal of the alternating current power supply, and the control driving module acquires the voltage zero-crossing signal and determines the starting point of the starting stage according to the voltage zero-crossing signal.

According to the electromagnetic heating control device, the starting point of the starting stage is determined according to the voltage zero crossing point of the alternating current power supply, so that interference signals can be eliminated to a greater extent, and the control is more accurate.

Optionally, the control driving module determines a time offset by a time length T0 before the voltage zero-crossing time as a starting point of the startup phase, the startup phase lasting until an end point of an nth chopping cycle from the voltage zero-crossing time, where n is a non-negative integer.

According to the electromagnetic heating control device, sufficient discharge time is provided for the power switch tube when the power switch tube is switched on, and overlarge C pole current is avoided when the power switch tube is switched on.

n is equal to 1 or 0.

According to the electromagnetic heating control device, a wider control parameter range can be set so as to adapt to the performance of power switching tubes of different manufacturers.

Optionally, the control drive module includes:

the driving module comprises the voltage source and the variable current source, and is electrically coupled with the driving end of the power switch tube and used for driving the power switch tube; and

the control module is electrically coupled to the voltage detection module and used for acquiring the voltage value of the driving end, and the control module is electrically coupled to the driving module and controls the driving module to drive the power switch tube according to the voltage value of the driving end.

Optionally, the control drive module includes:

the driving module comprises the voltage source and the variable current source, is electrically coupled with the driving end of the power switch tube and is used for driving the power switch tube, and is electrically coupled to the voltage detection module and is used for acquiring the voltage value of the driving end; and

the control module is electrically coupled to the driving module and used for controlling the driving module to drive the power switch tube according to the voltage value of the driving end.

Optionally, the control drive module includes:

a main control module for obtaining the target power;

the heating control module is electrically coupled to the main control module and used for receiving the target power, the heating control module is electrically coupled to the driving module, the heating control module judges whether the target power is smaller than the threshold power or not, and controls the driving module to drive the power switch tube according to the voltage value of the driving end.

According to the electromagnetic heating control device, the specific arrangement of the control unit and the driving unit can adopt various hardware structural forms, and a user can flexibly arrange the control unit and the driving unit according to specific requirements.

A third aspect of the present invention provides an electromagnetic heating cooking appliance including the heating control apparatus according to the above.

According to the electromagnetic heating control cooking appliance of the present invention, when in the low power heating mode, the electromagnetic heating cooking appliance enters the start-up phase, the heating phase and the stop phase in turn in each control period. In the starting stage, the power switch tube is switched on by adopting a plurality of sections of driving currents, and the driving currents are controlled by monitoring the voltage of the driving end of the power switch tube, so that the hard starting of the power switch tube can be effectively avoided.

According to the electromagnetic heating cooking utensil, in the starting stage, the driving current is adjusted through the voltage value fed back by the driving end of the power switch tube, the power switch tube is driven to work in a cut-off region, an amplification region and a saturation region in sequence, the voltage of the driving end of the power switch tube is limited within a set range in a Mi Leping switching region of the power switch tube, so that the switching current flowing through the power switch tube at the moment of switching on the power switch tube is limited, the power switch tube is prevented from being switched on hard, reliable millisecond-level duty ratio low-power continuous heating and variable-power heating are realized, the cooking effect is improved, and the user experience is improved. In addition, according to the electromagnetic heating cooking utensil provided by the invention, the power switch tubes of different manufacturers can be automatically adapted to realize soft start, the cost and the structural space are not increased, and meanwhile, the electromagnetic interference and the noise generated by electromagnetic heating start can be reduced.

Optionally, the electromagnetic heating cooking appliance is an induction cooker, an electromagnetic rice cooker or an electromagnetic pressure cooker.

The electromagnetic heating control device can be widely applied to various electromagnetic heating cooking appliances.

Drawings

The following drawings of the invention are included to provide a further understanding of the invention. The drawings illustrate specific embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

fig. 1 is a schematic diagram of a switching-on waveform of a power switching tube IGBT mentioned in the background art;

FIG. 2 is a diagram of a duty cycle power modulation waveform mentioned in the background art;

fig. 3 is a schematic diagram of a relationship curve between a C-pole voltage and a C-pole current of a power switch tube IGBT under different driving voltages;

fig. 4 is a schematic block diagram of an electromagnetic heating apparatus of an electromagnetic heating cooking appliance according to a preferred embodiment of the present invention;

fig. 5a is a flowchart of an operation of an electromagnetic heating apparatus of an electromagnetic heating cooking appliance according to a preferred embodiment of the present invention;

FIG. 5b is a flowchart illustrating the operation of one preferred embodiment of controlling the switching of the driving current according to the voltage value in step S30 of FIG. 5 a;

fig. 6a to 6c are timing diagrams of driving currents of the power switch tube in a start-up phase of the electromagnetic heating control method according to the preferred embodiment of the present invention;

FIG. 7 is a waveform diagram (4/5 heating duty cycle case) of an embodiment of an electromagnetic heating control method according to the present invention at low power operation;

FIG. 8 is a waveform diagram (3/5 heating duty cycle case) of another embodiment of an electromagnetic heating control method according to the present invention at low power operation;

FIG. 9 is a waveform diagram (2/5 heating duty case) of still another embodiment of an electromagnetic heating control method according to the present invention at low power operation;

FIG. 10a is C pole current I when the power switch tube is turned on in the starting stage by the electromagnetic heating control method according to the preferred embodiment of the present invention_CC-and G-voltages V_GTiming diagrams of (1);

FIG. 10b shows the C-pole current I when the power switch tube is turned on in the starting stage when the power switch tube G pole adopts the constant voltage driving control method_CC-and G-voltages V_GTiming diagrams of (1);

fig. 11 is a schematic block diagram of an electromagnetic heating apparatus of an electromagnetic heating cooking appliance according to still another embodiment of the present invention; and

fig. 12 is a schematic block diagram of an electromagnetic heating apparatus of an electromagnetic heating cooking appliance according to another embodiment of the present invention.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that embodiments of the invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in detail so as not to obscure the embodiments of the invention.

In the following description, a detailed process will be described in order to provide a thorough understanding of embodiments of the present invention. It is apparent that the implementation of the embodiments of the present invention is not limited to the specific details familiar to those skilled in the art.

The invention firstly provides an electromagnetic heating control device of an electromagnetic heating cooking utensil and a heating control method thereof, so as to realize low-power continuous heating and variable-power heating, improve the cooking effect and improve the user experience.

In a preferred embodiment of the present invention, the electromagnetic heating device is applied to an electromagnetic heating cooking appliance, such as an electromagnetic heating rice cooker (or referred to as IH rice cooker). An electromagnetic heating rice cooker generally includes a lid and a cooker body, and an inner pot is provided in the cooker body, and a cooking space is formed when the lid is closed. The electromagnetic heating device of the electromagnetic heating cooking appliance is generally located in the pot body, for example, below the inner pot, for heating the inner pot.

In the preferred embodiment of the present invention, as shown in fig. 4, the heating control device of the electromagnetic heating cooking appliance is powered by ac power, and the device comprises an EMC electromagnetic compatibility module 10, a rectifier filter module 20, an LC resonance module 30, a switch module 40, a voltage detection module 50, a driving module 60, a control module 70 and a zero-crossing detection module 80.

The EMC electromagnetic compatibility module 10 is coupled to an alternating mains supply for filtering interference signals. The rectification and filtering module 20 rectifies and filters the ac mains supply filtered by the EMC electromagnetic compatibility module 10, and then provides a dc power supply to the LC resonance module 30. The switch module 40 is used for controlling the LC resonance module to perform resonance operation, and the switch module 40 includes a power switch IGBT including a gate G (driving end), a collector C, and an emitter E. The LC resonance module 30 is connected to the collector of the IGBT. The zero-crossing detection module 80 is configured to detect a voltage zero-crossing point signal of the ac mains power filtered by the EMC electromagnetic compatibility module 10. The driving module 60 is electrically coupled to the driving terminals of the IGBTs. The driving module 60 has both a voltage source function and a variable current source function, and can output a driving voltage to the IGBT and also output a driving current to the IGBT. The voltage detection module 50 has one end electrically coupled to the driving end of the IGBT and the other end electrically coupled to the control module 70, and is configured to detect a voltage value of the driving end of the IGBT and transmit the 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 driving module 60 to drive the power switch tube IGBT according to the voltage value fed back to the IGBT driving terminal. The control module 70 also receives a voltage zero crossing signal detected by the voltage zero crossing detection module 80.

Fig. 5a is a preferred work flow of the heating control device of the electromagnetic heating cooking appliance shown in fig. 4, the work flow comprises the following steps:

s10, the control module 70 acquires the target power Pt of the electromagnetic heating cooking appliance, and then executes step S20.

Wherein the target power Pt is a heating power to be achieved by the electromagnetic heating cooking device at the current stage. For example, if a user wants to cook porridge, a porridge cooking function can be selected in the interactive module of the electromagnetic heating cooking appliance, and the electromagnetic heating cooking appliance automatically enters a porridge cooking mode in which the electromagnetic heating cooking appliance can be heated at a power of 600W, and the target power Pt is 600W. Optionally, the target power of the electromagnetic heating cooking appliance is in the range of 0-2500W, namely 0W ≦ Pt ≦ 2500W.

S20, the control module 70 determines whether the target power Pt is smaller than the threshold power Pd, if so, executes step S30, otherwise, executes step S40.

The threshold power Pd is a preset threshold value. When the target power Pt is greater than or equal to the threshold power Pd, it is determined that the electromagnetic heating cooking appliance is the high power heating mode, heating may be performed in a conventional manner, and step S40 is performed. When the target power Pt is less than the threshold power Pd, it is determined that the electromagnetic heating cooking appliance is the low power heating mode, and step S30 is performed.

Preferably, the threshold power Pd and the rated power P satisfy: pd is more than or equal to 500W and less than or equal to 2200W, and Pd is more than or equal to P-600W and less than or equal to (P-100W).

And S30, in each control period, the control module 70 controls the electromagnetic heating cooking appliance to enter a starting stage, a heating stage and a stopping stage in sequence. Wherein, in the starting phase, in the driving period of the power switch tube IGBT, the control module 70 provides the driving current to the power switch tube IGBT through the driving module 60, and the driving current is drivenThe current flow includes a first driving current I1 and a second driving current I2. Meanwhile, the voltage detection module 50 monitors and obtains the voltage value V of the driving end of the power switch tube_G. The voltage value V_GAnd finally fed back to the control module 70, and 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. In all the driving periods of the startup phase, the amplitude of the first driving current I1 decreases between the lower driving current threshold Ia and the upper driving current threshold Ib, and the amplitude of the second driving current I2 increases between the lower driving current threshold Ic and the upper driving current threshold Id. The first driving current lower threshold Ia is smaller than the first driving current upper threshold Ib, and the second driving current lower threshold Ic is smaller than the second driving current upper threshold Id.

Specifically, in the startup phase, as the drive period increases, the magnitude of the first drive current I1 gradually decreases from the first drive current upper threshold value Ib to the first drive current lower threshold value Ia. The decreasing process of the first driving current I1 may be monotone decreasing (as shown in fig. 6 a) or equal in any two adjacent driving periods (as shown in fig. 6 b), forming a plateau of the current amplitude. That is, in any two adjacent driving periods of the power switch tube, the amplitude of the first driving current I1 in the following driving period is smaller than or equal to the amplitude of the first driving current I1 in the previous driving period; the amplitude of the first driving current I1 in the last driving period of the power switch tube (which is the first driving current lower threshold Ia) is smaller than the amplitude of the first driving current I1 in the first driving period (which is the first driving current upper threshold Ib). In the variation interval of the first driving current I1, the amplitude of the first driving current I1 may be in an equal-difference decreasing variation, may not be in an equal-difference decreasing variation, or may be in another decreasing variation law.

Specifically, in the startup phase, the magnitude of the second drive current I2 gradually increases from the second drive current lower threshold Ic to the second drive current upper threshold Id as the drive period increases. The increasing process of the second driving current I2 may be monotone increasing (as shown in fig. 6 a) or equal in any two adjacent driving periods (as shown in fig. 6 c), forming a plateau of the current amplitude. That is, in any two adjacent driving periods of the power switch tube, the amplitude of the second driving current I2 in the following driving period is greater than or equal to the amplitude of the second driving current I2 in the previous driving period; the amplitude of the second driving current I2 in the last driving period of the power switch tube (which is the second driving current upper threshold Id) is greater than the amplitude of the second driving current I2 in the first driving period (which is the second driving current lower threshold Ic). In the variation interval of the second driving current I2, the amplitude of the second driving current I2 may be increased with equal difference, or increased with unequal difference, or increased with other regularity.

The number of cycles of the amplitude plateau of the first driving current I1 may be equal to or different from the number of cycles of the amplitude plateau of the second driving current I2 in all driving cycles of the start-up phase. In time, the magnitude plateau of the first drive current I1 may be non-overlapping, partially overlapping, or fully overlapping with the magnitude plateau of the second drive current I2. The number of amplitude plateau periods of the first drive current I1 and the second drive current I2 is greater than or equal to 0.

Preferably, the amplitude of the first driving current I1 is larger than the amplitude of the second driving current I2 in the same driving period of the start-up phase.

Preferably, the first lower driving current threshold Ia is 10mA, the first upper driving current threshold Ib is 80mA, the second lower driving current threshold Ic is 5mA, and the second upper driving current threshold Ic is 60 malid.

And S40, the control module 70 controls the cooking appliance to work in a high-power heating mode.

For example, the IGBT is driven to operate in a saturated conduction state, i.e., normally turned on, by a voltage driving method.

In step S30, preferably, referring to fig. 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 of the driving terminal of the IGBT, including the steps of:

s31, the control module 70 judges the voltage value V of the driving end_GIf it is greater than the first voltage threshold V1, if so, executing step S32, if not, continuing to monitor V_GUp to V_GGreater than V1.

Preferably, vth < V1 ≦ Vth +4V, where Vth is the threshold voltage of the power switch tube, and usually Vth is between 4V and 8V, and Vth values of different manufacturers or different types of IGBTs may be different. Preferably, V1 is 7.5V.

When the driving end voltage V of the IGBT_GWhen the voltage is larger than the threshold voltage Vth of the IGBT, the IGBT sequentially enters an amplification area (amplification state) and a saturation area (saturation conduction state) from a cut-off area (cut-off state), the voltage of a driving end forms a platform area (Miller platform) due to the Miller effect, and after the Miller platform/Miller period is finished, the IGBT enters the saturation area. The miller platform is a typical sign of an IGBT in the amplification region. In the amplification region, the IGBT has high impedance, and if the C pole current of the IGBT is high at the moment, the IGBT is easy to burn out.

If the voltage value V is_GIf the voltage value is less than or equal to V1, returning to continuously monitor (obtain) the voltage value V of the driving end_GAnd continue to judge V_GWhether greater than V1.

S32, 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, and then performs step S33.

In the starting phase, in the driving period of the power switch tube, after the driving current is switched to the second driving current I2, the heating control device of the electromagnetic heating cooking utensil further executes the following steps:

s33, the control module 70 controls the driving end to work according to the voltage value V of the driving end_GJudging whether the Miller platform is finished or not, if so, executing the step S34, and if not, continuously monitoring the V_GUntil the miller plateau ends.

S34, the control module 70 judges the voltage value V of the driving end_GIf it is greater than the second voltage threshold V2, if so, executing step S35, if not, continuing to monitor V_GUp to V_GGreater than V2.

Preferably, V2 is 10.5V.

And S35, switching the driving mode of the power switch tube from current driving to voltage driving, and providing a first driving voltage Va to the power switch tube through the driving module 60 by the control module 70 so as to drive the power switch tube to work in a saturated conduction state.

Preferably, 15V ≦ Va ≦ 22V. Preferably, va =18V.

If the voltage value V of the driving terminal_GIf the value is less than or equal to V2, returning to continue to obtain V_GAnd continue to judge whether to drive V_GWhether greater than V2.

The heating control method of the heating control device of the electromagnetic heating cooking appliance according to the present invention in the driving cycle of the power switch tube is described in detail below with reference to fig. 7.

In fig. 7, the waveforms are, from top to bottom, the ac mains waveform, the C-pole voltage Vc waveform of the IGBT at low power, the G-pole driving level diagram of the IGBT at low power, and the G-pole current I of the IGBT in the driving period of the IGBT at low power_GWaveform and G-voltage V of IGBT in IGBT driving period under low power_GAnd (4) waveform.

It will be understood by those skilled in the art that when the electromagnetic heating device shown in fig. 4 is adopted, vc exhibits an oscillating waveform during the time when the IGBT is driven to conduct, and finally is maintained at a stable high level (for example, 305-310V) during the time when the IGBT is not conducting, i.e., a rectified dc voltage value (as shown in the waveform of Vc, the C voltage of the IGBT in fig. 7 under low power). As shown in fig. 3, the G-pole driving voltage V of the IGBT_GThe higher the C-voltage Vc, the greater the C-pole current Ic. If the C-pole voltage Vc is a rectified dc voltage (for example, 305-310V) at the moment when the IGBT enters the conducting phase, the G-pole driving voltage V before the IGBT enters the saturated conducting state is needed_GThe control is performed at a lower level to prevent that the IGBT generates too much heat to affect the service life of the IGBT due to too much C pole current Ic before the IGBT enters a saturated conduction state (for example, in an amplification state), that is, to prevent the IGBT from being turned on hard. The heating control method of the electromagnetic heating cooking utensil can solve the problem to a certain extent.

With continued reference to fig. 7, in a preferred embodiment, the control period of the induction heating cooking appliance is 5 chopping periods. In each control period, the electromagnetic heating cooking appliance is controlled to sequentially enter a starting stage, a heating stage and a stopping stage. In the embodiment shown in fig. 7, the drive pulse is applied to the IGBT in the start-up phase and the heating phase, and the drive pulse is not applied in the stop phase.

As shown in fig. 7, in the start-up phase, in the drive period of the IGBT (e.g., the period from (1) to (2) in the figure), first, a first drive current I1 is applied to the drive terminal (the G-pole of the IGBT) of the IGBT, and the IGBT is driven in a current-driven manner while monitoring the drive terminal voltage V of the IGBT_G. With prolonged time, V_GGradually increase when V_GAnd when the voltage is greater than the threshold voltage Vth of the IGBT, the IGBT is conducted. Then V_GContinues to rise as V_GWhen the first voltage threshold is larger than the first voltage threshold V1, the first driving current I1 is switched to the second driving current I2. The first voltage threshold V1 is greater than the threshold voltage Vth of the IGBT, that is, when the IGBT is driven by the first driving current I1, the driving current is switched to the second driving current I2 while ensuring that the IGBT is turned on.

When the IGBT is driven by the second driving current I2, the driving end voltage V of the IGBT is continuously monitored_G. With the prolonged time, the drive end voltage V of the IGBT_GExhibiting a Miller plateau, i.e. V_GNo longer rising. With the increase of the time, when the miller period ends (i.e., the miller plateau ends), the IGBT enters the saturated on state. In a saturated conduction state, the IGBT can be driven in a voltage drive mode. Therefore, after the miller platform is finished, the driving end voltage V of the IGBT is continuously monitored_G. When V is_GAnd when the voltage is greater than the second voltage threshold value V2, the end of the Miller platform can be determined, then the Miller platform is switched from the current driving mode to the voltage driving mode, and the IGBT is driven to be normally conducted by the first driving voltage Va so as to work in a saturated conducting state.

Typically, the threshold voltage Vth of the power switch tube is between 4V and 8V. In the preferred embodiment of the present invention, the first voltage threshold V1 is smaller than Vth +4V, and the miller platform voltage of the IGBT is substantially equivalent to V1, so in the present invention, at the moment when the IGBT is turned on, the voltage value of the driving terminal of the IGBT can be controlled to be substantially not more than 12V (preferably 7.5V), the C pole current of the IGBT can be effectively controlled, and the IGBT is prevented from being turned on hard.

As shown in fig. 10A, when the heating method of the electromagnetic heating cooking device according to the present invention is adopted, the C pole current Ic of the power switch tube can be controlled below 40A in the starting stage. As shown in fig. 10b, when the power switch tube is driven by a constant voltage source, the maximum value of the C pole current Ic of the power switch tube can reach 55A. As can be seen from a comparison between fig. 10a and fig. 10b, the electromagnetic heating control method according to the present invention effectively reduces the C-pole current when the power switch is turned on, and avoids the hard start of the power switch.

Understandably, when the driving end voltage V of the IGBT is V_GAfter the Miller platform of (1), V_GWill climb upwards, thus by continuously monitoring V_GThe end of the Miller period can be timely found, so that the current driving mode is timely switched to the voltage driving mode, the IGBT is enabled to have large C electrode current in a saturation conduction state, and the energy is rapidly stored for the LC oscillating circuit. In a saturated conduction state, the conduction voltage between the C pole and the E pole of the power switching tube is reduced, the heat loss of the power switching tube is reduced, and the power switching tube can be protected while energy storage of the LC oscillating circuit is realized.

Understandably, the driving end voltage V of the IGBT is detected_GThere are various specific methods for ending the miller stage, for example, the miller stage end can be determined by detecting that the voltage of the C terminal of the IGBT has dropped to the lowest point, or for example, by detecting the V terminal after the miller period ends_GDetermining the end of the Miller platform, or e.g. by calculating V_GSecond derivative of change to find V_GInflection points of the curve, etc. As shown in fig. 7, in the preferred embodiment of the present invention, the voltage value V of the driving terminal is set within the second predetermined period Tp from the time of the first predetermined period Tm after the driving current is switched to I2_GAnd continuously climbing (namely continuously increasing), judging that the Miller platform is finished. Wherein, the value of Tm is matched with the duration of the Miller period, preferably, tm is more than or equal to 1 mu s and less than or equal to 18 mu s, and Tp is more than or equal to 300ns and less than or equal to 10 mu s. Further, to ensure that the miller period ends and the IGBT enters the saturated on state, V may be set to_GContinuous crawlWhen the voltage rises to reach the second voltage threshold V2, the miller period is determined to be ended. The second voltage threshold V2 is preferably 10.5V.

According to the heating control method of the electromagnetic heating cooking utensil, in the starting stage, the driving current is adjusted through the voltage value fed back by the driving end of the IGBT, the IGBT is driven to sequentially pass through the cut-off area, the amplification area and the saturation area, and the voltage V of the driving end is measured in the Miller period after the IGBT is switched on_GThe limit is at a lower level to limit the C pole current of the IGBT under the amplification state of the IGBT, avoid the hard turn-on of the IGBT and realize reliable millisecond-level duty ratio low-power continuous heating, thereby improving the cooking effect and improving the user experience. In addition, according to the heating control method of the electromagnetic heating cooking utensil, the power switch tubes of different manufacturers can be automatically adapted to realize soft start, the cost and the structural space are not increased, and meanwhile, the electromagnetic interference and the noise generated by electromagnetic heating start can be reduced.

According to the heating control method of the electromagnetic heating cooking utensil, in the starting stage, the amplitude of the first driving current I1 is gradually reduced, and the amplitude of the second driving current I2 is gradually increased, so that the cooking utensil can be smoothly and reliably transited from the starting stage to the heating stage, and the cooking utensil is not easy to damage.

As shown in fig. 7, the heating control method of the electromagnetic heating cooking appliance according to the present invention further includes, during the heating phase, in a driving period of the power switch (for example, a period from (3) to (4) in the figure), the control module 70 controls the driving module 60 to provide the first driving voltage Va to the driving end of the power switch so as to drive the power switch to operate in a saturated conducting state; in the stop phase, the power switch is not operated, for example, the control module 70 controls the driving module 60 not to provide the driving voltage or the driving current to the power switch, or the control module 70 controls the output driving value of the driving module 60 to be 0. Preferably, 15V ≦ Va ≦ 22V. Preferably, va =18V. In the heating stage, the power switch tube is normally switched on.

Preferably, in the electromagnetic heating control method according to the present invention, a starting point of the start-up phase of the electromagnetic heating cooking appliance may be determined according to a zero-crossing point of the voltage of the ac power supply.

As shown in fig. 7, a time Pa offset by a time period T0 before a voltage zero-crossing time P0 of the ac power supply is determined as a starting point of the startup phase, and the startup phase continues for n chopping cycles (if the ac power frequency is 50Hz, the chopping cycle is 10 ms) from the voltage zero-crossing time P0 of the ac power supply until a time Pb. In other words, the start-up phase is from time Pa to time Pb. That is, the startup phase continues from a time offset by a time period T0 before the voltage zero-crossing time of the ac power source to the end of the nth chopping cycle from the voltage zero-crossing time of the ac power source. Wherein n is a positive integer, and T0 is more than or equal to 500 mu s and less than or equal to 5ms. Preferably, T0=2.5ms, n =1. As can be known from the above description of the heating control method in the start-up phase, in the drive period of the IGBT in the start-up phase, the soft start process is to discharge the C-voltage of the IGBT, and the start-up phase lasts for 1 chopper period to ensure sufficient discharge. However, depending on the device performance of IGBTs of different brands/models, n =0 may also be set, i.e. the discharge time period is only T0.

In the timing sequence shown in fig. 7, the complete control period is 5 chopping cycles, wherein the start-up period is about 1 chopping cycle, the heating period is 3 chopping cycles, and the stop period is about 1 chopping cycle (the stop period of the previous control period and the start period of the next control period total 2 chopping cycles), and the IGBT is turned on in the start-up period and the heating period, so that fig. 7 shows the case of 4/5 heating duty ratio. In the starting phase, in the driving period of the IGBT, the IGBT performs soft start and normal turn-on in sequence, so the starting phase is also referred to as a half-driving phase. During the warm-up phase, the IGBT is normally on, so the warm-up phase is also referred to as the full drive phase. The number of chopping cycles n of the start-up phase is also referred to herein as the number of start-up chopping cycles n.

It is to 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 voltage of the alternating current power supply is used for determining both the starting point of the start-up phase and the switching point of the start-up phase and the heating phase and the switching point of the heating phase and the stop phase. As shown in fig. 7, the start-up phase lasts for about 1 chopping cycle, ending at the voltage zero crossing of the ac power supply; the heating phase starts from the voltage zero crossing of the ac power supply and also ends at the voltage zero crossing of the ac power supply for 3 chopping cycles. The starting point of each stage is determined according to the voltage zero crossing point of the alternating current power supply, so that interference signals can be eliminated to a greater extent, and accurate control over the electromagnetic heating cooking appliance is facilitated.

Fig. 8 and 9 show timing diagrams of other embodiments of electromagnetic heating control methods according to the present invention. The embodiment shown in fig. 8 and 9 differs from the embodiment shown in fig. 7 only in that the heating phase and the stop phase differ in time length. In the embodiment shown in fig. 8, the complete control period is 5 chopping periods, while the duration of the heating phase is 2 chopping periods, so the embodiment shown in fig. 8 is a case of 3/5 heating duty cycle. In the embodiment shown in fig. 9, the complete control period is 5 chopping periods, and the duration of the heating phase is 1 chopping period, so the embodiment shown in fig. 9 is a 2/5 heating duty cycle case.

Therefore, according to the heating control method of the electromagnetic heating cooking utensil, not only can low-power continuous heating be realized, but also low-power variable-power heating can be realized by adjusting the duty ratio of the starting stage and the heating stage.

It should be noted that fig. 7-9 are only timing diagrams of embodiments of the electromagnetic heating control method according to the present invention, and the depiction of the amplitude, duration, etc. of each parameter waveform in the figures is merely for convenience of illustration and is not meant to limit the amplitude, duration, and relationship between each parameter waveform. For example, the amplitude of the second driving current I2 in fig. 7-9 is smaller than I1, which is only used to illustrate that the second driving current I2 is a different current from the first driving current I1, and is not used to limit the second driving current I2 to be smaller than the first driving current I1, for example, the second driving current I2 may also be larger than the first driving current I1. In addition, the amplitudes of I1 and I2 may be the same or different in different driving periods. As shown in fig. 7 to 9, a plurality of drive periods are included in each chopping period (one chopping period is 10ms when the frequency of the ac power source is 50 Hz). In the same driving period, the amplitudes of the first driving current I1 and the second driving current I2 are substantially constant under the periodic control of microsecond level.

Fig. 11 shows still another embodiment of the heating apparatus of the electromagnetic heating cooking appliance according to the present invention. Unlike the embodiment shown in fig. 4, the voltage detection module 50 has one end electrically coupled to the driving end of the IGBT and the other end electrically coupled to the driving module 60, and is configured to detect a voltage value at the driving end of the IGBT and transmit the voltage value to the driving module 60 in real time. The control module 70 controls the driving module 60 to drive the power switch tube according to the voltage value of the driving end of the IGBT.

Fig. 12 shows still another embodiment of a heating apparatus of an electromagnetic heating cooking appliance according to the present invention. Unlike the embodiment shown in fig. 11, the control unit includes a heating control module 70A and a main control module 70B. The zero-crossing detection module 80 transmits a zero-crossing voltage signal of the ac power source to the heating control module 70A. The main control module 70B sends a control signal to the heating control module 70A, and makes a corresponding adjustment according to the information fed back by the heating control module 70A in real time. The main control module 70B acquires a target power Pt of the electromagnetic heating cooking appliance, and transmits the target power Pt, a threshold power Pd, an offset duration T0, and a start-up chopping cycle number n to the heating control module 70A. The heating control module 70A determines whether the target power Pt is smaller than the threshold power Pd, and when the target power Pt is smaller than the threshold power Pd, the heating control module 70A controls the driving module 60 to drive the power switch according to the voltage value at the driving end and the voltage zero-crossing signal.

The drive module 60 and the control module 70 of fig. 4 and 11 may be collectively referred to as a control drive module. The drive module 60, heating control module 70A and main control module 70B of fig. 12 may also be collectively referred to as a control drive module.

The invention also provides an electromagnetic heating cooking appliance, which comprises the heating control device of the electromagnetic heating cooking appliance and adopts the electromagnetic heating control method.

The electromagnetic heating cooking appliance according to the invention can be an electromagnetic oven, an electromagnetic heating rice cooker or an electromagnetic heating pressure cooker and other cooking appliances.

The electromagnetic heating cooking appliance obviously can comprise various characteristics of the heating control device, and can solve the corresponding technical problems and have corresponding effects.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

The present invention has been described in terms of the above embodiments, but it should be understood that the above embodiments are for purposes of illustration and description only and are not intended to limit the invention to the scope of the described embodiments. It will be appreciated by those skilled in the art that many variations and modifications are possible in light of the above teaching and are within the scope of the invention as claimed.

Claims

1. A heating control method for an electromagnetic heating cooking appliance comprising a resonant heating circuit and a power switching tube, characterized in that it comprises the following steps:

acquiring target power of the electromagnetic heating cooking appliance;

judging whether the target power is smaller than a threshold power;

acquiring a voltage value of a driving end of the power switch tube; and is

2. The heating control method according to claim 1, wherein the amplitude of the first driving current I1 is larger than the amplitude of the second driving current I2 in the same driving period of the power switch tube.

3. The heating control method according to claim 1, wherein in any two adjacent driving cycles of the power switching tube, wherein,

4. The heating control method according to claim 1, wherein the controlling of the driving current to be switched from the first driving current I1 to the second driving current I2 according to the voltage value of the driving terminal includes:

5. The heating control method according to claim 4, characterized by further comprising:

6. The heating control method according to claim 5, wherein the determining whether the miller platform is finished according to the voltage value at the driving end comprises:

when the voltage value of the driving terminal continuously increases within the second predetermined period Tp from the time of the first predetermined period Tm after the driving current is switched to the second driving current I2, it is determined that the miller plateau is finished.

7. The heating control method according to claim 1,

in the heating stage, in the driving period of the power switch tube, providing a first driving voltage Va to the power switch tube so as to drive the power switch tube to work in a saturated conducting state;

and in the stopping phase, the power switch tube is not operated.

8. The heating control method according to any one of claims 1 to 7, wherein an alternating current power supply is used to supply power to the electromagnetic heating cooking appliance, the heating control method further comprising:

acquiring a voltage zero crossing point signal of the alternating current power supply;

9. The heating control method according to claim 8, wherein the determining the starting point of the startup phase according to the voltage zero-crossing point includes:

10. The heating control method according to claim 9,

the offset duration T0 satisfies: t0 is more than or equal to 500 mu s and less than or equal to 5ms; and/or

n is equal to 1 or 0.

11. The heating control method according to any one of claims 1 to 7,

the first drive current I1 satisfies: i1 is more than or equal to 10mA and less than or equal to 80mA; and/or

12. The heating control method according to any one of claims 5 to 7, characterized in that the first drive voltage Va satisfies: va is more than or equal to 15V and less than or equal to 22V.

13. A heating control device for an electromagnetic heating cooking appliance including a resonant heating circuit, the heating control device comprising:

wherein the control drive module performs the following operations:

acquiring target power of the electromagnetic heating cooking appliance;

judging whether the target power is smaller than a threshold power;

in a driving period of the power switch tube, the control driving module provides driving currents to the power switch tube, wherein the driving currents comprise a first driving current I1 and a second driving current I2;

14. The heating control device as claimed in claim 13, wherein the amplitude of the first driving current I1 is greater than the amplitude of the second driving current I2 in the same driving period of the power switch tube.

15. The heating control device of claim 13, wherein in any two adjacent driving cycles of the power switch tube, wherein,

16. The heating control device according to claim 13, wherein the controlling the driving module to switch the driving current from the first driving current I1 to the second driving current I2 according to the voltage value of the driving terminal includes:

17. The heating control device of claim 16,

after the driving current is switched to the second driving current I2, the control driving module judges whether the Miller platform is finished or not according to the voltage value of the driving end;

18. The heating control device of claim 17, wherein the control driver module determines whether the miller platform is finished based on the voltage value at the driver end, comprising:

19. The heating control device according to claim 13,

in the heating stage, in a driving period of the power switch tube, the control driving module provides a first driving voltage Va to the power switch tube to drive the power switch tube to work in a saturated conducting state;

and in the stopping phase, the power switch tube is not operated.

20. The heating control device according to any one of claims 13 to 19, wherein an ac power source is used to supply power to the electromagnetic heating cooking appliance, the heating control device further comprises a voltage zero-crossing detection module, the voltage zero-crossing detection module is configured to detect a voltage zero-crossing signal of the ac power source, and the control driving module acquires the voltage zero-crossing signal and determines a starting point of the start-up phase according to the voltage zero-crossing signal.

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

22. The heating control device of claim 21,

n is equal to 1 or 0.

23. The heating control device according to any one of claims 13 to 19,

24. The heating control device according to any one of claims 17 to 19, wherein the first drive voltage Va satisfies: va is more than or equal to 15V and less than or equal to 22V.

25. The heating control device of any one of claims 13-19, wherein the control drive module comprises:

26. The heating control device of any one of claims 13-19, wherein the control drive module comprises:

27. The heating control device of any one of claims 13-19, wherein the control drive module comprises:

a main control module for obtaining the target power;

28. An electromagnetic heating cooking appliance, characterized by comprising a heating control device according to any one of claims 13-27.

29. The electromagnetic heating cooking appliance of claim 28, wherein the electromagnetic heating cooking appliance is an induction cooker, an electromagnetic heating rice cooker, or an electromagnetic heating pressure cooker.