CN114698167A

CN114698167A - Electromagnetic heating equipment and power control method and power control device thereof

Info

Publication number: CN114698167A
Application number: CN202011589013.9A
Authority: CN
Inventors: 曾露添; 朱成彬; 雷俊; 江德勇; 刘文华; 王云峰
Original assignee: Foshan Shunde Midea Electrical Heating Appliances Manufacturing Co Ltd
Current assignee: Foshan Shunde Midea Electrical Heating Appliances Manufacturing Co Ltd
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-07-01
Anticipated expiration: 2040-12-29
Also published as: CN114698167B

Abstract

The invention discloses electromagnetic heating equipment, a power control method and a power control device thereof, wherein the power control method of the electromagnetic heating equipment comprises the following steps: when the power regulation mode of duty ratio regulation is adopted to control the output power of the secondary heating module of the electromagnetic heating equipment, the current duty ratio regulation mode for driving the secondary heating module to carry out heating work is determined; when the current duty ratio adjusting mode for driving the slave heating module to carry out heating work is determined to be a complementary duty ratio continuous adjusting mode, whether an upper bridge switching tube of the slave heating module works in a hard opening state is judged; if the upper bridge switching tube of the slave heating module works in a hard switching-on state, the upper bridge switching tube and the lower bridge switching tube of the slave heating module are controlled by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio. According to the power control method of the electromagnetic heating equipment, the high loss of the upper bridge switching tube can be prevented, the temperature rise is reduced, and the service life and the reliability are improved.

Description

Electromagnetic heating equipment and power control method and power control device thereof

Technical Field

The invention relates to the technical field of electromagnetic heating equipment, in particular to electromagnetic heating equipment and a power control method and a power control device thereof.

Background

In the related art, when the furnace end works, the switching tube may enter a hard switching-on state from a soft switching-on state, the loss of the switching tube is increased, the temperature is increased, the switching tube is damaged, and the reliability of a product is reduced.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a power control method of electromagnetic heating equipment, which can prevent the upper bridge switching tube from being large in loss, reduce temperature rise and improve service life and reliability.

The invention also provides a computer readable storage medium.

The invention also provides electromagnetic heating equipment capable of realizing the power control method.

The invention also provides a power control device of the electromagnetic heating equipment.

In order to achieve the above object, an embodiment of the present invention provides a power control method for an electromagnetic heating device, including the following steps: when the output power of a secondary heating module of the electromagnetic heating equipment is controlled by adopting a duty ratio adjusting power adjusting mode, determining a current duty ratio adjusting mode for driving the secondary heating module to perform heating work; when the current duty ratio adjusting mode for driving the slave heating module to carry out heating work is determined to be a complementary duty ratio continuous adjusting mode, judging whether an upper bridge switching tube of the slave heating module works in a hard switching-on state; and if the upper bridge switching tube of the slave heating module works in a hard switching-on state, controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio.

According to the power control method of the electromagnetic heating equipment, disclosed by the embodiment of the invention, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting a heating control mode of complementary duty ratio-symmetrical duty ratio alternation when the upper bridge switching tube of the secondary heating module works in a hard switching-on state, so that the upper bridge switching tube and the lower bridge switching tube alternately work in the hard switching-on state, the heat generated by hard switching is shared, the temperature rise of the upper bridge switching tube is reduced, the upper bridge switching tube is prevented from being damaged due to long-time work in the hard switching-on state, and the service life and the reliability of the electromagnetic heating equipment are improved.

In addition, the power control method of the electromagnetic heating apparatus according to the above-described embodiment of the present invention may further have the following additional technical features:

according to some embodiments of the present invention, determining whether the upper bridge switching tube of the slave heating module is in a hard on state includes: judging whether the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value or not; and if the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value, determining that the upper bridge switching tube works in a hard switching-on state.

According to some embodiments of the present invention, determining whether the upper bridge switching tube of the slave heating module is in a hard on state includes: detecting a midpoint voltage between an upper bridge switching tube and a lower bridge switching tube of the slave heating module; judging whether the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value or not according to the midpoint voltage; and when the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value, determining that the upper bridge switching tube works in a hard switching-on state.

According to some embodiments of the present invention, the controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by a heating control manner of complementary duty cycle-symmetric duty cycle alternation comprises: counting zero crossing points of an input alternating current power supply of the electromagnetic heating equipment; judging whether the zero crossing point count value is an odd value; when the zero crossing point count value is an odd value, outputting PWM signals with symmetrical duty ratios to the upper bridge switching tube and the lower bridge switching tube so as to enable the slave heating module to perform heating operation; and when the zero crossing point count value is an even value, outputting PWM signals with complementary duty ratios to the upper bridge switching tube and the lower bridge switching tube so as to heat the slave heating module.

According to some embodiments of the present invention, the complementary duty ratio refers to a relationship between a level of a PWM signal of the upper bridge switching tube and a level of a PWM signal of the lower bridge switching tube in a PWM cycle, except for a dead time; the symmetrical duty ratio refers to a relationship that the level of the PWM signal of the upper bridge switching tube and the level of the PWM signal of the lower bridge switching tube are opposite to each other in one PWM period, and the on-time of the upper bridge switching tube is equal to the on-time of the lower bridge switching tube.

According to some embodiments of the present invention, before controlling the output power of the electromagnetic heating device from the heating module by adopting a duty-regulated power regulation manner, the method further comprises: the method comprises the steps of obtaining a heating module with the largest input power in a plurality of heating modules of the electromagnetic heating equipment, taking the heating module with the largest input power as a main heating module, and taking the rest heating modules in the plurality of heating modules as slave heating modules.

According to some embodiments of the present invention, the output power of the main heating module is controlled by using a frequency-modulated power regulation method.

According to some embodiments of the present invention, controlling the output power of the main heating module by using a frequency-modulated power adjustment method includes: the method comprises the steps of outputting a first PWM signal with a fixed duty ratio to the main heating module, and controlling the output power of the main heating module by adjusting the frequency of the first PWM signal.

According to some embodiments of the present invention, controlling the output power of the slave heating module by a duty-adjusted power adjustment method includes: and outputting a second PWM signal with fixed frequency to the slave heating module, and controlling the output power of the slave heating module by adjusting the duty ratio of the second PWM signal.

In order to achieve the above object, an embodiment of the present invention provides a computer-readable storage medium on which a power control program of an electromagnetic heating apparatus is stored, which when executed by a processor implements a power control method of the electromagnetic heating apparatus according to an embodiment of the present invention.

In order to achieve the above object, an embodiment of the present invention provides an electromagnetic heating apparatus, including a memory, a processor, and a power control program of the electromagnetic heating apparatus stored in the memory and executable on the processor, where when the processor executes the power control program, the power control method of the electromagnetic heating apparatus according to the embodiment of the present invention is implemented.

In order to achieve the above object, an embodiment of the present invention provides a power control apparatus for an electromagnetic heating device, including: the power control module is used for determining a current duty ratio adjusting mode for driving the slave heating module to perform heating work when the power adjusting mode for adjusting the duty ratio is adopted to control the output power of the slave heating module of the electromagnetic heating equipment; the judging module is used for judging whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not when the current duty ratio adjusting mode for driving the slave heating module to carry out heating work is a complementary duty ratio continuous adjusting mode; the power control module is further used for controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio when the upper bridge switching tube of the slave heating module works in a hard on state.

According to the power control device of the electromagnetic heating equipment, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio when the upper bridge switching tube of the heating module works in a hard switching-on state, so that the upper bridge switching tube and the lower bridge switching tube work in the hard switching-on state alternately, heat generated by hard switching-on is shared together, the temperature rise of the upper bridge switching tube is reduced, the upper bridge switching tube is prevented from being damaged due to long-time work in the hard switching-on state, and the service life and the reliability of the electromagnetic heating equipment are improved.

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

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of a power control apparatus according to some embodiments of the invention;

FIG. 2 is a schematic flow diagram of a method of power control of an electromagnetic heating apparatus according to some embodiments of the present invention;

FIG. 3 is a flowchart illustrating step S1 of the power control method according to an embodiment of the invention;

FIG. 4 is a schematic diagram of a power control device and heating module according to a particular embodiment of the present invention;

FIG. 5 is a graph of PWM frequency versus output power for a main heating module according to an embodiment of the present invention;

FIG. 6 is a flow chart of controlling the output power of the main heating module using frequency modulated power regulation in accordance with an embodiment of the present invention;

FIG. 7 is a PWM waveform diagram of a power control apparatus outputting a main heating module according to an embodiment of the present invention;

FIG. 8 is a graph of duty cycle versus output power for the slave heater modules in the case where the half-bridge switching tube PWM frequency of the slave heater module is equal to that of the master heater module in accordance with an embodiment of the present invention;

FIG. 9 is a flow chart of controlling the output power from the heating module using duty-cycled power regulation in accordance with an embodiment of the present invention;

FIG. 10 is a PWM waveform diagram of a power control apparatus outputting a master heating module and a slave heating module according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a power control apparatus according to further embodiments of the present invention;

FIG. 12 is a flow chart schematic of a method of power control for an electromagnetic heating apparatus according to further embodiments of the present invention;

FIG. 13 is a schematic diagram of a power control device and heating module according to another exemplary embodiment of the present invention;

FIG. 14 is a waveform illustrating the operation of 50% duty cycle and 20% duty cycle switching tubes according to an embodiment of the present invention;

FIG. 15 is a waveform illustrating operation of a complementary duty cycle continuous regulation mode and a complementary duty cycle-symmetric duty cycle alternating heating control mode according to an embodiment of the present invention;

FIG. 16 is a waveform diagram illustrating the operation of outputting a PWM signal with complementary duty ratio and a PWM signal with symmetrical duty ratio to a switching tube according to an embodiment of the present invention;

fig. 17 is a flow chart of the control of the upper and lower bridge switching devices using complementary duty cycle-symmetrical duty cycle alternating heating control according to an embodiment of the present invention.

Description of the drawings:

a power control device 100; a heating module 50;

a determination module 10; a power control module 20; a judgment module 30;

a first heating module 200; a first driving module 201; a first upper bridge switching tube 202; a first lower bridge switching tube 203; a first heating coil 204; a first pair of

resonant capacitors

205, 206; a first half-bridge midpoint voltage detection module 207;

a second heating module 300; a second driving module 301; a second upper bridge switching tube 302; a second lower bridge switching tube 303; a second heating coil 304; a second pair of

resonant capacitors

305, 306; a second half-bridge midpoint voltage detection module 307;

a zero crossing detection module 101.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An electromagnetic heating apparatus, a power control method thereof, and a power control device 100 according to an embodiment of the present invention are described below with reference to the drawings.

The plurality of heating modules 50 (the number of heating modules 50 is two or more) of the electromagnetic heating apparatus may correspond to a plurality of heating zones, which may be used for heating of a plurality of appliances to simultaneously perform a plurality of cooking processes. The electromagnetic heating device here may be a multi-head induction cooker or the like, and the heating module 50 may include a heating coil or the like.

A power control method of an electromagnetic heating apparatus according to an embodiment of the first aspect of the present invention and a power control device 100 of an electromagnetic heating apparatus according to an embodiment of the second aspect of the present invention are described below with reference to fig. 1 to 10.

As shown in fig. 1, a power control apparatus 100 of an electromagnetic heating device includes: a determination module 10 and a power control module 20. The determining module 10 is configured to, when it is determined that a plurality of heating modules 50 of the electromagnetic heating apparatus work simultaneously, obtain input power of each heating module 50, and determine the type of the corresponding heating module 50 according to the input power of each heating module 50 when the input powers of the plurality of heating modules 50 are different; the power control module 20 is configured to control the output power of each heating module 50 in different power adjustment manners according to the type of each heating module 50.

As shown in fig. 2, the power control method of the electromagnetic heating apparatus includes step S1 and step S2.

Step S1: when the plurality of heating modules 50 of the electromagnetic heating equipment are determined to work simultaneously, the input power of each heating module 50 is obtained, and the type of the corresponding heating module 50 is determined according to the input power of each heating module 50 when the input powers of the plurality of heating modules 50 are different.

For example, in some embodiments, the types of heating modules 50 include a master heating module and a slave heating module. Determining the type of the corresponding heating module 50 from the input power to each heating module 50 may include: the heating module 50 with the largest input power among the plurality of heating modules 50 is obtained, and the heating module 50 with the largest input power is taken as a master heating module, and the remaining heating modules 50 among the plurality of heating modules 50 are taken as slave heating modules. The heating modules 50 are thus classified according to the difference in input power, which may be the power input by the user for each heating module 50 according to the desired cooking function. Here, the number of the slave heating modules is one or more. When only one heating module 50 of the electromagnetic heating device works, the heating module 50 can be used as a main heating module or a slave heating module to perform output power control in a corresponding power regulation mode.

In one specific embodiment according to the present invention, as shown in fig. 3, the type of the corresponding heating module 50 is determined according to the input power of each heating module 50 in step S1, including step S11 and step S12, as follows:

step S11: it is determined whether the input power to any one of the heating modules 50 has changed. If not, the type of the heating module 50 does not need to be judged and the output power does not need to be controlled, the method is exited, and the output power of the current heating module 50 is kept; if yes, go to step S12.

Step S12: the heating module 50 with the largest input power among the plurality of heating modules 50 is obtained, and this heating module 50 is taken as the master heating module, and the remaining heating modules 50 among the plurality of heating modules 50 are taken as the slave heating modules.

Thereby, the type of the heating module 50 is determined.

As shown in fig. 2, step S2: the output power of the corresponding heating module 50 is controlled in different power adjustment manners according to the type of each heating module 50. So that the output power of each heating module 50 is equal to its corresponding input power.

Output power is controlled by adopting different power regulation modes for the heating modules 50 of different types, consistency of working frequencies of the heating modules 50 which work simultaneously is facilitated, so that a series of synthetic frequencies generated by mixing multiple frequencies in the working process are avoided, sharp and harsh noises generated by synthesizing difference frequency signals are avoided, and use experience of users is improved.

For example, in some embodiments, step S2: the output power of the corresponding heating module 50 is controlled in different power adjusting manners according to the type of each heating module 50, including step S21 and step S22.

Step S21: and when the current heating module 50 is determined to be the main heating module, controlling the output power of the main heating module by adopting a frequency modulation power regulation mode.

The power control device 100 of the electromagnetic heating apparatus outputs a PWM (Pulse Width Modulation) signal to control the plurality of heating modules 50, where the plurality of heating modules 50 are a first heating module 200, a second heating module 300, and a third heating module 50 … …, respectively, as shown in fig. 4, the first heating module 200 includes a first driving module 201, a first upper bridge switching tube 202, a first lower bridge switching tube 203, a first heating coil 204, and a first pair of resonant capacitors 205, 206; the second heating module 300 includes a second driving module 301, a second upper bridge switching tube 302, a second lower bridge switching tube 303, a second heating coil 304, and a second pair of resonant capacitors 305, 306; … … the power control device 100 of the electromagnetic heating device outputs PWM signal to the driving module, the driving module outputs complementary PWM signal to control the upper bridge switch tube and the lower bridge switch tube to be alternatively conducted, the heating coil is controlled to output alternating current to generate alternating magnetic field, the alternating magnetic field induces the metal pot placed on the heating coil to generate alternating eddy current, the alternating eddy current causes the pot to heat, thereby realizing the heating of food.

The output power of the main heating module is controlled by adopting a frequency modulation power regulation mode, and the specific principle is as follows:

as shown in fig. 5, which is a relationship diagram of the PWM frequency and the output power of the main heating module, in the frequency range of the inductive region (frequency f 0-f 1), the larger the PWM frequency is, the smaller the output power is; the smaller the PWM frequency, the greater the output power.

Fig. 6 is a flow chart showing the control of the output power of the main heater module by using a frequency-modulated power regulation method. The method specifically comprises the following steps:

step S211: judging whether the input power of the main heating module is increased, if so, executing a step S212; if not, go to step S214;

step S212: reducing the PWM frequency of the main heating module, and then performing step S213;

step S213: judging whether the output power of the current main heating module is equal to the input power or not, if so, finishing the control of the output power of the main heating module, and exiting the method; if not, returning to execute S212;

step S214: increasing the PWM frequency of the main heating module, and then performing step S215;

step S215: judging whether the output power of the current main heating module is equal to the input power or not, if so, finishing the control of the output power of the main heating module, and exiting the method; if not, the process returns to step S214.

Fig. 7 shows a waveform diagram of the main heating module PWM output from the power control device 100. The power control device 100 outputs a main heater module PWM waveform like the waveform W10 in fig. 7, outputs power 1000W (corresponding to P10 in fig. 5), and has a frequency of 25KHz (corresponding to f10 in fig. 5).

If the user adjusts the heating power to 1500W, i.e., adjusts the input power of the main heater module to 1500W, steps S212 and S213 are executed until the output power of the main heater module is equal to the input power, and then the power control apparatus 100 outputs the PWM waveform of the main heater module as shown by W11 in fig. 7, the output power is shown by P11(1500W) in fig. 5, and the corresponding PWM frequency is shown by f11(23KHz) in fig. 5. It can be seen that the frequency of the PWM output from the power control device 100 is reduced from 25KHz (f10) to 23KHz (f11), and the output power is increased from 1000W to 1500W.

If the user adjusts the heating power to be reduced to 500W, i.e., adjusts the input power to the main heater module to be 500W, steps S214 and S215 are executed until the output power of the main heater module is equal to the input power, at which time the power control apparatus 100 outputs the main heater module PWM waveform as shown by W12 in fig. 7, the output power as shown by P12(500W) in fig. 5, and the corresponding PWM frequency as shown by f12(27KHz) in fig. 5. It can be seen that the frequency of the PWM output from the power control device 100 is increased from 25KHz (f10) to 27KHz (f12), thereby reducing the output power from 1000W to 500W.

The output power of the main heating module is controlled in a frequency modulation power adjusting mode, so that the output power of the main heating module is adjusted more quickly, the output power can be adjusted to be equal to the input power quickly, and the user experience is improved. And the method is favorable for obtaining larger working power and meets the requirement of a larger range for adjusting the output power.

Step S22: and when the current heating module 50 is determined to be the slave heating module, controlling the output power of the slave heating module by adopting a power regulation mode of regulating the duty ratio.

The specific principle of controlling the output power of the secondary heating module by adopting the power regulation mode of regulating the duty ratio is as follows:

FIG. 8 is a graph showing the relationship between the duty ratio and the output power of the slave heater module when the half-bridge switching tube PWM frequency of the slave heater module is equal to that of the master heater module. It can be seen that the smaller the duty cycle of the PWM, the smaller the output power; the larger the duty cycle of the PWM, the larger the output power.

Fig. 9 is a flowchart showing the control of the output power from the heater module by the duty ratio adjustment method. The method specifically comprises the following steps:

step S221: judging whether the input power of the heating module is increased, if so, executing step S222; if not, go to step S224;

step S222: increasing the PWM duty ratio of the slave heating module, and then performing step S223;

step S223: judging whether the output power of the current slave heating module is equal to the input power, if so, finishing the control of the output power of the slave heating module, and exiting the method; if not, returning to execute S222;

step S224: reducing the PWM duty ratio of the slave heating module, and then performing step S225;

step S225: judging whether the output power of the current slave heating module is equal to the input power, if so, finishing the control of the output power of the slave heating module, and exiting the method; if not, the process returns to step S224.

As shown in fig. 10, the power control apparatus 100 outputs PWM waveforms of the master and slave heater modules. W20 represents a PWM waveform of the main heater module output from the power control device 100, and the duty ratio is 50%. Waveform W21 is the PWM waveform that power control device 100 outputs the slave heater module, and the duty ratio is 30% (corresponding to P20 in fig. 8), and it can be seen that the PWM period of the master heater module (T10 in fig. 10) is equal to the PWM period of the slave heater module (T20 in fig. 1), and the PWM frequency of the slave heater module is equal to the PWM frequency of the master heater module, as expressed by the formula frequency f being 1/T.

If the user adjusts the increase from 500W to 600W in the heater module heat power, i.e., adjusts the input power from the heater module to 600W, the power control device 100 executes steps S222 and S223 until the output power from the heater module is equal to the input power, and then outputs the waveform from the heater module PWM as W22 in FIG. 10, when the time from the high level of the heater module PWM is increased from t21 to t22 in FIG. 10, and the corresponding duty ratio is increased from 30% to 40% in FIG. 8, thereby increasing the output power from 500W to 600W.

If the user adjusts the reduction of the heat power from 500W to 400W, that is, adjusts the input power from the heater module to 400W, the power control device 100 executes steps S224 and S225 until the output power from the heater module is equal to the input power, and then outputs the waveform from the heater module PWM as W23 in FIG. 10, when the high time from the heater module PWM is reduced from t21 to t23 in FIG. 10, the corresponding duty ratio is reduced from 30% to 30% in FIG. 8, and the reduction of the output power from 500W to 400W is realized.

The output power of the slave heating module is controlled by adopting a power regulation mode of regulating the duty ratio, so that the PWM frequency of the slave heating module is not changed in the power regulation process, the consistency of the PWM frequencies of the master heating module and the slave heating module and the consistency of the PWM frequencies of a plurality of slave heating modules are favorably realized, and the PWM frequency of the master heating module and the PWM frequency of the slave heating module output by the power control device 100 are kept the same no matter how the output power of the master heating module and the output power of the slave heating module are changed, namely, the frequency difference of all output PWM is kept to be zero. Because the difference frequency signal is zero, sharp and harsh noise can not be generated, and the user experience effect is effectively improved.

According to the power control method of the electromagnetic heating device in the embodiment of the first aspect of the present invention, the output power is controlled by adopting different power adjustment modes for different types of heating modules 50, which is beneficial to achieving the frequency consistency of the plurality of heating modules 50 which work simultaneously, so as to avoid the generation of a synthesized frequency due to the mixing of multiple frequencies in the working process, avoid the generation of sharp and harsh noise due to the synthesis of difference frequency signals, and facilitate the improvement of the user experience.

According to the power control device 100 of the electromagnetic heating apparatus in the embodiment of the second aspect of the present invention, the output power is controlled by adopting different power adjustment modes for different types of heating modules 50, which is beneficial to achieving the frequency consistency of the plurality of heating modules 50 that work simultaneously, so as to avoid the generation of a synthesized frequency due to the mixing of multiple frequencies during the working process, avoid the generation of sharp and harsh noise due to the synthesis of difference frequency signals, and facilitate the improvement of the user experience.

In the embodiment of the second aspect of the present invention, a method for determining the type of the corresponding heating module 50 by the determination module 10 and a method for controlling the output power of the corresponding heating module 50 by the power control module 20 in different power adjustment manners may refer to the power control method of the electromagnetic heating apparatus in the embodiment of the first aspect of the present invention, and are not described herein again.

According to some embodiments of the invention, step S21: the method for controlling the output power of the main heating module by adopting a frequency modulation power regulation mode comprises the following steps: and outputting a first PWM signal with a fixed duty ratio to the main heating module, and controlling the output power of the main heating module by adjusting the frequency of the first PWM signal. As shown in fig. 5, when the duty ratio of the first PWM signal is constant, the output power is smaller as the frequency is larger, and the output power is larger as the frequency is smaller. The output power of the main heating module is adjusted by fixing the duty ratio of the first PWM signal and only adjusting the frequency of the first PWM signal, so that the power adjustment is quicker, and the power adjustment method is simplified.

Further, step S22: the method for controlling the output power of the secondary heating module by adopting a power regulation mode of regulating the duty ratio comprises the following steps: and outputting a second PWM signal with a fixed frequency to the slave heating module, and controlling the output power of the slave heating module by adjusting the duty ratio of the second PWM signal. As shown in fig. 8, when the frequency of the second PWM signal is constant, the output power increases as the duty ratio increases, and the output power decreases as the duty ratio decreases. The frequency of the second PWM signal is fixed, and the output power of the slave heating modules is adjusted by only adjusting the duty ratio of the second PWM signal, so that the frequencies of the slave heating modules are always equal, and the generation of difference frequency signals is effectively reduced.

Also, in some embodiments, the frequency of the second PWM signal is the same as the frequency of the first PWM signal. In other words, the frequencies of the master heating module and the slave heating module are always equal, so that the generation of difference frequency signals is effectively avoided. For example, in some embodiments, after the frequency of the first PWM signal is adjusted until the output power of the master heating module is equal to the input power, the frequency of the second PWM signal is controlled to be equal to the frequency of the adjusted first PWM signal, and then the duty ratio of the second PWM signal is adjusted until the output power of the slave heating module is equal to the input power, so as to achieve the frequency consistency of the master heating module and the slave heating module. In addition, in the embodiment with a plurality of slave heating modules, the output power of the plurality of slave heating modules can be controlled independently without interference, the frequency consistency can be kept well, and the power adjusting method is simpler.

In some embodiments, the fixed duty ratio of the first PWM signal is 50%, and the duty ratio of the second PWM signal is adjustable from 0-50%, so that the output power of the slave heating module is adjusted within a range smaller than or equal to the output power of the master heating module. For example, in some embodiments, the duty cycle of the second PWM signal may be adjusted to 0, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, and so on. When the duty ratio of the second PWM signal is 0, the slave heating module stops heating; when the duty ratio of the second PWM signal is 50%, the output power of the slave heating module is equal to the output power of the master heating module.

When two or more heating modules 50 having the largest input power are selected from the plurality of heating modules 50, one of the heating modules 50 having the largest input power may be used as a master heating module, and the remaining heating modules 50 may be used as slave heating modules; alternatively, all the heating modules 50 having the maximum input power and the same input power may be used as the master heating modules, and the other heating modules 50 except for some master heating modules may be used as the slave heating modules, and the master heating modules may be controlled to input the first PWM signals having the same fixed duty ratio.

According to some embodiments of the present invention, when it is determined that only one heating module 50 of the electromagnetic heating apparatus works, the output power of the heating module 50 is controlled by using a frequency-modulated power adjustment manner, so that the output power of the heating module 50 is controlled more quickly, and a wider range or higher output power can be output to meet the cooking requirement.

For example, in one embodiment, when it is determined that the electromagnetic heating apparatus has only one heating module 50 in operation, the heating module 50 is controlled to input a first PWM signal having a fixed duty ratio of 50%, and the output power of the heating module 50 is controlled by adjusting the frequency of the first PWM signal.

A power control method of an electromagnetic heating apparatus according to an embodiment of the third aspect of the present invention and a power control device 100 of an electromagnetic heating apparatus according to an embodiment of the fourth aspect of the present invention are described below with reference to fig. 11 to 17.

The applicant finds that when the duty ratio of the heating module 50 is smaller than a certain value, the half-bridge upper switch tube enters a hard switching state from a soft switching state, the loss of the upper switch tube is increased, the temperature is increased, the upper switch tube is damaged, and the reliability of the electromagnetic heating device is reduced. Based on this, the invention also provides a power control method and a power control device 100 capable of reducing the temperature rise and the loss of the upper bridge switching tube.

As shown in fig. 11, a power control apparatus 100 of an electromagnetic heating device according to a fourth aspect of the present invention may include: a power control module 20 and a decision module 30.

The power control module 20 is configured to determine a current duty ratio adjusting mode for driving the slave heating module to perform heating operation when controlling the output power of the slave heating module of the electromagnetic heating device by using the duty ratio adjusting power adjusting mode. The judging module 30 is configured to judge whether the upper bridge switching tube of the slave heating module is in a hard on state when the current duty ratio adjusting mode for driving the slave heating module to perform heating operation is a complementary duty ratio continuous adjusting mode. In addition, the power control module 20 is further configured to control the upper bridge switching tube and the lower bridge switching tube of the slave heating module in a complementary duty ratio-symmetric duty ratio alternating heating control manner when the upper bridge switching tube of the slave heating module works in a hard on state

As shown in fig. 12, the power control method of the electromagnetic heating apparatus according to the embodiment of the third aspect of the present invention may include steps S3, S4, and S5. The method comprises the following specific steps:

step S3: and when the output power of the secondary heating module of the electromagnetic heating equipment is controlled by adopting a duty ratio adjusting power adjusting mode, determining a current duty ratio adjusting mode for driving the secondary heating module to perform heating work.

Among them, the heater module having the input power that is not the maximum among the plurality of heater modules 50, in other words, the heater module having the relatively small input power among the plurality of heater modules 50 may be the slave heater module. For example, the method for determining the slave heating modules in the plurality of heating modules 50 may refer to the power control method of the electromagnetic heating apparatus according to the embodiment of the first aspect of the present invention, and all the contents of the power control method according to the embodiment of the first aspect of the present invention may be applied to the power control method of the electromagnetic heating apparatus according to the embodiment of the third aspect of the present invention, and the specific contents and advantageous effects thereof are not described herein again.

Step S4: and when the current duty ratio adjusting mode for driving the slave heating module to perform heating work is determined to be a complementary duty ratio continuous adjusting mode, judging whether an upper bridge switching tube of the slave heating module works in a hard opening state.

The switch tube has small loss and low temperature rise in a soft switching-on state, and is an ideal working state. The switch tube has large loss and high temperature when in a hard on state. In general, when the duty ratio of the PWM signal is greater than a certain value, the upper bridge switching transistor and the lower bridge switching transistor operate in a soft on state. However, when the duty ratio is smaller than a certain value, the upper bridge switching tube enters a hard switching-on state from a soft switching-on state. Therefore, whether the upper bridge switching tube of the secondary heating module works in a hard switching-on state or not is determined, and control is performed according to the hard switching-on state, so that the problems that the upper bridge switching tube is too large in loss and too high in temperature rise are avoided.

For example, in some embodiments, step S4: judging whether the upper bridge switching tube of the secondary heating module works in a hard on state or not may include steps S41 and S42, which are as follows:

step S41: and judging whether the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value.

Step S42: and if the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value, determining that the upper bridge switching tube works in a hard switching-on state.

Here, the preset value can be flexibly set according to actual conditions, for example, in some embodiments, the preset value may be 30%, and if the duty ratio of the PWM signal of the upper bridge switching tube is 20%, and 20% is less than 30%, it is determined that the upper bridge switch operates in the hard on state.

For another example, in some embodiments, step S4: judging whether the upper bridge switching tube of the secondary heating module works in a hard on state or not can include steps S43, S44 and S45, which are as follows:

step S43: detecting the midpoint voltage between an upper bridge switching tube and a lower bridge switching tube of the secondary heating module;

step S44: determining whether the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value or not according to the midpoint voltage;

step S45: and when the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value, determining that the upper bridge switching tube works in a hard switching-on state.

Here, the preset voltage threshold may be set according to actual conditions, for example, the preset voltage threshold may be 0V. When the switch tube is conducted, if the voltage difference between the collector and the emitter of the switch tube is less than or equal to 0V, the switch tube is called a soft on state. Conversely, if the collector-emitter voltage difference of the switch tube is greater than 0V, it is called a hard on state.

The power control device 100 of the electromagnetic heating apparatus outputs a PWM signal to control the plurality of heating modules 50, the plurality of heating modules 50 are the first heating module 200 and the second heating module 300 … … respectively, the electromagnetic heating apparatus further includes a first half-bridge midpoint voltage detection module 207 and a second half-bridge midpoint voltage detection module 307 … …, which are disposed in one-to-one correspondence with the plurality of heating modules 50

As shown in fig. 13, the first heating module 200 includes a first driving module 201, a first upper bridge switching tube 202, a first lower bridge switching tube 203, a first heating coil 204, and a first

resonant capacitor pair

205, 206, and the first half bridge midpoint voltage detecting module 207 is configured to detect whether the first upper bridge switching tube 202 operates in a hard on state or a soft on state; the second heating module 300 comprises a second driving module 301, a second upper bridge switching tube 302, a second lower bridge switching tube 303, a second heating coil 304 and a second

resonant capacitor pair

305, 306, and the second half-bridge midpoint voltage detecting module 307 is configured to detect whether the second upper bridge switching tube 302 operates in a hard on state or a soft on state; … …

The second heater module 300 will be described as an example of the slave heater module.

Fig. 14 is a waveform diagram showing the operation of the second heating module 300. W10 is the gate (g1) driving waveform of the second upper bridge switching transistor 302, W11 is the gate (g2) driving waveform of the second lower bridge switching transistor 303, and W12 is the second half-bridge midpoint (g3) voltage waveform.

At time t11, when the duty ratio of the PWM signal is large, the second upper bridge switching tube 302 is turned on, the second half-bridge midpoint voltage detecting module 307 collects the midpoint voltage signal and sends the midpoint voltage signal to the power control device 100, the power control device 100 detects that the voltage of the second half-bridge midpoint voltage (g3) is at the high level 310V, which is equal to the power supply voltage (VC2), then the voltage difference between the collector and the emitter of the second upper bridge switching tube 302 is equal to 0V, and the power control device 100 determines that the second upper bridge switching tube 302 operates in the soft-on state. At a time t12, when the duty ratio of the PWM signal is relatively large, at a time when the second lower bridge switching tube 303 is turned on, the power control device 100 detects that the voltage of the second half-bridge midpoint voltage (g3) is low level 0V, which is equal to the ground voltage, a voltage difference between a collector and an emitter of the second lower bridge switching tube 303 is equal to 0V, and the power control device 100 determines that the second lower bridge switching tube 303 works in a soft-on state. Under the condition, the loss of the upper bridge switching tube and the lower bridge switching tube is small, and the system works stably.

However, when the PWM duty ratio of the second heating module 300 is smaller than a certain value, the half-bridge upper switch tube will enter the hard on state from the soft on state. With continued reference to fig. 14, at time t13, at the second upper bridge switching transistor 302 conduction time when the duty ratio of the PWM signal is small, the power control device 100 detects that the voltage of the second half-bridge midpoint voltage (g3) is at low level 0V, the supply voltage VC2 is 310V, the voltage difference between the collector and the emitter of the second upper bridge switching transistor 302 is equal to 310V, and the power control device 100 determines that the second upper bridge switching transistor 302 is in the hard-on state. In this case, the second upper bridge switch tube 302 has large loss and high temperature, which may seriously damage the second upper bridge switch tube 302.

Because there are two switch tubes, an upper bridge switch tube and a lower bridge switch tube in the half-bridge circuit, there may be four working states for the two switch tubes:

first, the upper bridge switch tube is turned on, and the lower bridge switch tube is turned off, as shown in the time period T1 in fig. 14;

secondly, the upper bridge switch tube is closed, and the lower bridge switch tube is turned on, as shown in the time period T2 in fig. 14;

third, the upper and lower bridge switches are turned off simultaneously, as shown in the d1 and d2 periods of fig. 14;

fourth, the upper and lower bridge switching tubes are turned on at the same time, which may cause a short circuit of the power supply, resulting in permanent damage to the switching tubes, and thus it is necessary to prevent the switching tubes from operating in this state.

When the gate PWM driving signal of the switching tube is switched from high level to low level, the current flowing through the collector and the emitter of the switching tube is not immediately turned off, i.e. the process of switching the switching tube from on to off is not instantly finished, and the switching tube can be completely turned off after a certain time (about 0.5 us). Therefore, during the switching of any one of the switching tubes to the other switching tube in the half-bridge circuit, a time period (about 2us) for simultaneously turning off the two switching tubes needs to be given to the driving signal, as shown by the time periods d1 and d2 in fig. 14, so that the two switching tubes operate in the third operating state, the short-circuit and the direct-connection of the upper switching tube and the lower switching tube are prevented, the service life and the safety are improved, and this time period is called dead time (dead time).

The duty ratio refers to the ratio of the high level time length to the whole period length in one period of the PWM signal. As shown in FIG. 14, T1 is the high time length, T3 is the length of one PWM cycle, and the duty cycle is equal to T1/T3.

For a half-bridge circuit with two switching tubes, the PWM signal of the upper switching tube and the PWM signal of the lower switching tube can have the following two modes:

the other mode is a complementary duty ratio mode, which means that in one PWM cycle, the dead time is removed, the level of the PWM signal of the upper bridge switching tube and the level of the PWM signal of the lower bridge switching tube in other time periods are in an opposite relation, and the condition that the upper bridge switching tube and the lower bridge switching tube are conducted simultaneously does not exist. For example, as shown in fig. 16, T13 is a PWM cycle, except for dead time d1 and d2, in other time periods, the upper bridge switching transistor is at high level and the lower bridge switching transistor is at low level in the time period T11; in the time period of T12, the upper bridge switch tube is at low level, and the lower bridge switch tube is at high level.

The other mode is a symmetrical duty ratio mode, which means that in one PWM period, the conduction time of an upper bridge switch tube is equal to that of a lower bridge switch tube, and the level of the PWM signal of the upper bridge switch tube is opposite to that of the PWM signal of the lower bridge switch tube. As shown in fig. 16, T23 is a PWM cycle, and the on time T21 of the upper bridge switch tube is equal to the on time T22 of the lower bridge switch tube, there may be a time period in which the PWM of the upper bridge switch tube and the PWM of the lower bridge switch tube are both in a low level state, such as the time period Ta in fig. 16, where the upper bridge switch tube and the lower bridge switch tube are in an off state.

The zero-crossing time is the time when the ac power voltage crosses zero, and as shown in fig. 15, the W20 waveform is a half-bridge power supply (e.g., VC1, VC2 as shown in fig. 13) voltage waveform, where Z10, Z11, Z12, etc. are all zero-crossing time flags.

According to some embodiments of the present invention, in step S4, the current duty ratio adjustment mode for driving the heating operation from the heating module is determined to be a complementary duty ratio continuous adjustment mode. The complementary duty cycle continuous adjustment mode means that the upper bridge switching tube and the lower bridge switching tube are heated at the same duty cycle in two adjacent PWM signal periods, and in one PWM period, namely a time period between two zero-crossing moments, the upper bridge switching tube and the lower bridge switching tube work in the complementary duty cycle mode, and the levels are in an opposite relation. As shown in fig. 15, during the TM1 period of the W21 waveform, the upper bridge switching tube and the lower bridge switching tube are both operated in complementary duty cycle mode, and their waveform is spread out as shown in the M1 period in fig. 16, in the period M1 between two adjacent zero-crossing times. When the upper bridge switching tube of the secondary heating module works in a soft switching-on state, the output power is controlled by adopting a complementary duty ratio continuous regulation mode.

As shown in fig. 12, step S5: and if the upper bridge switching tube of the secondary heating module works in a hard switching-on state, controlling the upper bridge switching tube and the lower bridge switching tube by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio.

The heating control mode of alternating complementary duty ratio and symmetric duty ratio refers to that the complementary duty ratio mode and the symmetric duty ratio mode are alternately output by taking a time period between two zero-crossing times as unit time, namely, taking one PWM signal cycle as unit time. As in the TM2 period in fig. 15, the PWM signal of the complementary duty mode is output in the M1 period, and the PWM signal of the symmetrical duty mode is output in the M2 period. Wherein, the M1 time segment expansion waveform is shown as the M1 time segment in fig. 16, the M2 time segment expansion waveform is shown as the M2 time segment in fig. 16, and the conduction time T21 of the upper bridge switch tube is equal to the conduction time T22 of the lower bridge switch tube.

The heating is controlled by a heating control mode with the alternation of complementary duty ratio and symmetrical duty ratio, so that the upper bridge switching tube is prevented from being in a hard switching-on state for a long time, in other words, after the upper bridge switching tube and the lower bridge switching tube are controlled by the heating control mode with the alternation of complementary duty ratio and symmetrical duty ratio, the hard switching-on state of a single upper bridge switching tube is originally improved to be the hard switching-on state of the upper bridge switching tube and the lower bridge switching tube, the heat generated by hard switching-on is independently born by the upper bridge switching tube and is improved to be shared by the upper bridge switching tube and the lower bridge switching tube, and the temperature rise of the switching tubes is reduced by half, so that the service life and the reliability of a product are improved.

For example, in some embodiments, the step S5 of controlling the upper and lower switching tubes by a complementary duty cycle-symmetric duty cycle alternating heating control manner may include steps S51-S54:

step S51: counting zero crossing points of an input alternating current power supply of the electromagnetic heating equipment;

step S52: determining whether a zero crossing point count value is an odd value;

step S53: when the zero crossing point count value is an odd value, outputting PWM signals with symmetrical duty ratios to an upper bridge switching tube and a lower bridge switching tube so as to heat the slave heating module;

step S54: and when the zero crossing point count value is an even value, outputting PWM signals with complementary duty ratios to the upper bridge switching tube and the lower bridge switching tube so as to heat the slave heating module.

The zero crossing point of the input alternating current power supply refers to the time when the voltage of the alternating current power supply crosses zero. The zero-crossing detection module 101 may generate a zero-crossing signal when the ac power source is at a zero-crossing point, and input the zero-crossing signal to the power control apparatus 100, and the power control apparatus 100 counts the zero-crossing point after detecting the zero-crossing signal, for example, the power control apparatus 100 may include a zero-crossing counter, and the zero-crossing counter counts the zero-crossing point according to the zero-crossing signal, so that the power control apparatus 100 controls whether to output a PWM signal with a symmetric duty ratio or a PWM signal with a complementary duty ratio to the upper switching tube and the lower switching tube when the next zero-crossing signal arrives.

Fig. 15 is a waveform diagram of the operation corresponding to the heating control mode of the complementary duty ratio continuous adjustment mode and the complementary duty ratio-symmetrical duty ratio alternation mode. Fig. 16 is a diagram showing operating waveforms of PWM signals outputting complementary duty ratios and PWM signals outputting symmetrical duty ratios.

In fig. 15, the waveform of W20 is a half-bridge power supply (VC1, VC2) voltage waveform, and Z10, Z11, Z12 and the like are marks of zero crossings of an input ac power of the electromagnetic heating device. In the period from D10 to D14 of the waveform of W21, the duty ratio of the operation of the upper bridge switching tube and the lower bridge switching tube is not changed, and as shown in the M1 stage operation waveform shown in FIG. 16, the duty ratio corresponds to a complementary duty ratio continuous adjustment mode. The switching process of M1 and M2 in the time periods D15-D112 shown in FIG. 15 and the operating waveforms of the switching tubes in the time periods M1 and M2 shown in FIG. 16 correspond to the heating control mode of complementary duty ratio-symmetrical duty ratio alternation.

As shown in fig. 15, assuming that the duty ratio of the current PWM signal is 20%, before time t11, the power control apparatus 100 adopts a complementary duty ratio continuous adjustment mode, and the upper bridge switching tube operates at 20% duty ratio, as shown in the M1 time period of W30 in fig. 16; the lower bridge switching tube operates at 80% duty cycle as shown by the M1 period of W31 in fig. 16.

At time t11, the power control apparatus 100 detects that the upper bridge switching tube is in a hard-on state, switches to a heating control mode of complementary duty cycle-symmetric duty cycle alternation, and clears the zero-crossing counter to zero, so that the zero-crossing count value (CNT) is zero. At the time of the zero-crossing point Z15, the power control device 100 executes the method shown in fig. 17, after the zero-crossing counter performs the operation of adding 1, the value of CNT is 1, which is an odd value, and the power control device 100 outputs a PWM signal with a symmetrical duty ratio, for example, the upper bridge switching tube operates at a 30% duty ratio, as shown in the M2 period of W30 in fig. 16; the lower bridge switching tube operates at 30% duty cycle as shown by the M2 period of W31 in fig. 16. As can be seen from fig. 15, at this stage, when the upper bridge switching tube is turned on (time t 21), the voltage difference between the collector and the emitter of the upper bridge switching tube is zero volts, and the upper bridge switching tube operates in the soft on state, and when the lower bridge switching tube is turned on (time t 22), the voltage difference between the collector and the emitter of the lower bridge switching tube is 310V, and the lower bridge switching tube operates in the hard on state. The upper bridge switching tube has small loss and low temperature rise, and the lower bridge switching tube has large loss and high temperature rise.

At the next zero-crossing point time Z16, the power control device 100 executes the method shown in fig. 17, after the zero-crossing counter performs the operation of adding 1, the value of CNT is 2, and is an even value, and the power control device 100 outputs a PWM signal with a complementary duty ratio, that is, the upper bridge switching tube operates at 20% duty ratio, as shown in the M1 time period of W30 in fig. 16; the lower bridge switching tubes operate at 80% duty cycle, as shown in FIG. 16 by the M1 period of W31. As can be seen from fig. 15, at this stage, when the upper bridge switching tube is turned on (time t 11), the voltage difference between the collector and the emitter of the upper bridge switching tube is 310V, and the upper bridge switching tube operates in a hard on state, and when the lower bridge switching tube is turned on (time t 12), the voltage difference between the collector and the emitter of the lower bridge switching tube is zero V, and the lower bridge switching tube operates in a soft on state. The upper bridge switching tube has large loss and high temperature, and the lower bridge switching tube has small loss and low temperature rise.

Therefore, after a heating control mode with alternating complementary duty ratio and symmetrical duty ratio is adopted, the upper bridge switching tube works in a hard on state under the complementary duty ratio mode, and the lower bridge switching tube works in a hard on state under the symmetrical duty ratio mode. The complementary duty ratio and the symmetrical duty ratio are alternately carried out, so that the upper bridge switching tube and the lower bridge switching tube alternately work in a hard switching-on state, heat generated by hard switching-on is shared, the temperature rise of the upper bridge switching tube is reduced by half, the phenomenon that the temperature rise is too high due to the fact that the upper bridge switching tube is in the hard switching-on state for a long time is avoided, and the service life and the reliability of the electromagnetic heating equipment are improved.

According to some embodiments of the present invention, before controlling the output power of the slave heating module of the electromagnetic heating apparatus by using the duty-adjusted power adjustment manner in step S1, the method further includes determining the master heating module and the slave heating module, and the determining method may refer to the power control method of the electromagnetic heating apparatus according to the embodiment of the first aspect of the present invention, and is not described herein again.

According to the power control method of the electromagnetic heating device in the embodiment of the third aspect of the invention, when the upper bridge switching tube of the heating module works in the hard on state, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio, so that the upper bridge switching tube and the lower bridge switching tube work in the hard on state alternately, heat generated by hard on is shared together, the temperature rise of the upper bridge switching tube is reduced, the upper bridge switching tube is prevented from being damaged due to long-time work in the hard on state, and the service life and the reliability of the electromagnetic heating device are improved.

According to the power control device 100 of the electromagnetic heating apparatus in the fourth aspect of the present invention, when the upper bridge switch tube of the heating module is in the hard on state, the upper bridge switch tube and the lower bridge switch tube are controlled by a heating control manner of the complementary duty ratio-symmetric duty ratio alternation, so that the upper bridge switch tube and the lower bridge switch tube are alternately operated in the hard on state, and share the heat generated by the hard on, the temperature rise of the upper bridge switch tube is reduced, the upper bridge switch tube is prevented from being damaged due to long-time operation in the hard on state, and the service life and reliability of the electromagnetic heating apparatus are improved.

In the embodiment of the fourth aspect of the present invention, the method for controlling the output power of the slave heating module by the power control module 20 in the duty ratio adjusting manner, the method for determining the current duty ratio adjusting manner for driving the slave heating module to perform heating operation, the method for determining whether the upper bridge switching tube of the slave heating module operates in the hard on state by the determining module 30, and the method for controlling the upper bridge switching tube and the lower bridge switching tube by the power control module 20 in the complementary duty ratio-symmetric duty ratio alternating heating control manner may refer to the power control method of the electromagnetic heating apparatus in the embodiment of the third aspect of the present invention, and are not described herein again.

According to a fifth aspect of the present invention, there is provided a computer readable storage medium, on which a power control program of an electromagnetic heating apparatus is stored, the power control program of the electromagnetic heating apparatus implementing a power control method of the electromagnetic heating apparatus according to the first aspect of the present invention or implementing a power control method of the electromagnetic heating apparatus according to the third aspect of the present invention when executed by a processor.

Since the power control method of the electromagnetic heating device according to the first aspect of the present invention has the above-mentioned beneficial technical effects, according to the computer-readable storage medium of the fifth aspect of the present invention, when the stored power control program is executed by the processor, the power control method described in the above-mentioned embodiment is implemented, and the output power is controlled by adopting different power adjustment modes for different types of heating modules 50, which is beneficial to implementing the frequency consistency of multiple heating modules 50 that work simultaneously, so as to avoid that multiple frequencies are mixed together to generate a synthesized frequency in the working process, avoid that a synthesized difference frequency signal generates sharp and harsh noise, and facilitate improving the user experience.

Since the power control method of the electromagnetic heating device according to the third aspect of the present invention has the above-mentioned beneficial technical effects, according to the computer-readable storage medium of the fifth aspect of the present invention, when the stored power control program is executed by the processor, the power control method described in the above-mentioned embodiment is implemented, and when the upper bridge switching tube of the heating module is in the hard on state, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting the heating control manner of complementary duty ratio-symmetric duty ratio alternation, so that the upper bridge switching tube and the lower bridge switching tube alternately operate in the hard on state, the heat generated by the hard on state is shared together, the temperature rise of the upper bridge switching tube is reduced, the upper bridge switching tube is prevented from being damaged due to long-time operation in the hard on state, and the service life and reliability of the electromagnetic heating device are improved.

An electromagnetic heating apparatus according to an embodiment of the sixth aspect of the present invention includes a memory, a processor, and a power control program of the electromagnetic heating apparatus stored on the memory and executable on the processor, and when the processor executes the power control program, the processor implements the power control method of the electromagnetic heating apparatus according to the embodiment of the first aspect of the present invention, or implements the power control method of the electromagnetic heating apparatus according to the embodiment of the third aspect of the present invention.

Since the power control method for the electromagnetic heating device according to the embodiment of the first aspect of the present invention has the above-mentioned beneficial technical effects, according to the electromagnetic heating device according to the embodiment of the sixth aspect of the present invention, the output power is controlled by adopting different power adjustment modes for different types of heating modules 50, which is beneficial to achieving the frequency consistency of the plurality of heating modules 50 that operate simultaneously, thereby avoiding that multiple frequencies are mixed together to generate a synthesized frequency in the operating process, avoiding that a difference frequency signal is synthesized to generate sharp and harsh noise, and being beneficial to improving the use experience of a user.

Because the power control method of the electromagnetic heating device according to the embodiment of the third aspect of the present invention has the above-mentioned beneficial technical effects, according to the electromagnetic heating device according to the embodiment of the sixth aspect of the present invention, when the upper bridge switching tube of the heating module works in the hard on state, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting the heating control manner of the complementary duty ratio-symmetric duty ratio alternation, so that the upper bridge switching tube and the lower bridge switching tube alternately work in the hard on state, share the heat generated by the hard on, reduce the temperature rise of the upper bridge switching tube, avoid the upper bridge switching tube from being damaged due to long-time work in the hard on state, and improve the service life and reliability of the electromagnetic heating device.

Other constructions and operations of electromagnetic heating apparatuses according to embodiments of the present invention are known to those of ordinary skill in the art and will not be described in detail herein.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example" or "some examples" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing steps of a custom logic function or process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A power control method of an electromagnetic heating device is characterized by comprising the following steps:

when the output power of a secondary heating module of the electromagnetic heating equipment is controlled by adopting a duty ratio adjusting power adjusting mode, determining a current duty ratio adjusting mode for driving the secondary heating module to perform heating work;

when the current duty ratio adjusting mode for driving the slave heating module to perform heating work is determined to be a complementary duty ratio continuous adjusting mode, judging whether an upper bridge switching tube of the slave heating module works in a hard opening state;

and if the upper bridge switching tube of the slave heating module works in a hard switching-on state, controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio.

2. The power control method of the electromagnetic heating equipment according to claim 1, wherein the step of judging whether the upper bridge switching tube of the slave heating module works in a hard on state comprises the following steps:

judging whether the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value;

and if the duty ratio of the PWM signal of the upper bridge switching tube is smaller than a preset value, determining that the upper bridge switching tube works in a hard switching-on state.

3. The power control method of the electromagnetic heating equipment according to claim 1, wherein the step of judging whether the upper bridge switching tube of the slave heating module works in a hard on state comprises the following steps:

detecting a midpoint voltage between an upper bridge switching tube and a lower bridge switching tube of the slave heating module;

judging whether the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value or not according to the midpoint voltage;

and when the voltage difference between the collector and the emitter of the upper bridge switching tube is greater than a preset voltage threshold value, determining that the upper bridge switching tube works in a hard switching-on state.

4. A power control method for an electromagnetic heating device as claimed in any one of claims 1 to 3, characterized in that the control of the upper and lower bridge switching tubes of the slave heating module by a heating control mode of complementary duty cycle-symmetrical duty cycle alternation comprises:

counting zero crossing points of an input alternating current power supply of the electromagnetic heating equipment;

judging whether the zero crossing point count value is an odd value;

when the zero crossing point count value is an odd value, outputting PWM signals with symmetrical duty ratios to the upper bridge switching tube and the lower bridge switching tube so as to enable the slave heating module to perform heating operation;

and when the zero crossing point count value is an even value, outputting PWM signals with complementary duty ratios to the upper bridge switching tube and the lower bridge switching tube so as to heat the slave heating module.

5. The power control method of electromagnetic heating equipment according to claim 4, characterized in that the complementary duty ratio is a PWM cycle, excluding dead time, and the level of the PWM signal of the upper bridge switching tube and the level of the PWM signal of the lower bridge switching tube are in an inverse relationship; the symmetrical duty ratio refers to a relationship that the level of the PWM signal of the upper bridge switching tube and the level of the PWM signal of the lower bridge switching tube are opposite to each other in one PWM period, and the on-time of the upper bridge switching tube is equal to the on-time of the lower bridge switching tube.

6. The power control method of the electromagnetic heating device according to claim 1, before controlling the output power of the electromagnetic heating device from the heating module by a duty-adjusted power adjustment method, further comprising:

the method comprises the steps of obtaining a heating module with the largest input power in a plurality of heating modules of the electromagnetic heating equipment, taking the heating module with the largest input power as a main heating module, and taking the rest heating modules in the plurality of heating modules as slave heating modules.

7. A power control method for an electromagnetic heating apparatus as claimed in claim 6, characterized in that the output power of the main heating module is controlled by frequency-modulated power regulation.

8. A power control method for an electromagnetic heating apparatus according to claim 7, wherein the controlling the output power of the main heating module by frequency-modulated power regulation comprises:

the method comprises the steps of outputting a first PWM signal with a fixed duty ratio to the main heating module, and controlling the output power of the main heating module by adjusting the frequency of the first PWM signal.

9. The power control method of the electromagnetic heating device according to claim 8, wherein the controlling the output power of the slave heating module by the duty ratio-adjusted power adjustment method comprises:

and outputting a second PWM signal with fixed frequency to the slave heating module, and controlling the output power of the slave heating module by adjusting the duty ratio of the second PWM signal.

10. A computer-readable storage medium, characterized in that a power control program of an electromagnetic heating apparatus is stored thereon, which when executed by a processor implements the power control method of the electromagnetic heating apparatus according to any one of claims 1 to 9.

11. An electromagnetic heating apparatus, comprising a memory, a processor and a power control program of the electromagnetic heating apparatus stored on the memory and operable on the processor, wherein the processor implements the power control method of the electromagnetic heating apparatus according to any one of claims 1 to 9 when executing the power control program.

12. A power control apparatus of an electromagnetic heating device, comprising:

the power control module is used for determining a current duty ratio adjusting mode for driving the slave heating module to carry out heating work when the power adjusting mode for adjusting the duty ratio is adopted to control the output power of the slave heating module of the electromagnetic heating equipment;

the judging module is used for judging whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not when the current duty ratio adjusting mode for driving the slave heating module to carry out heating work is a complementary duty ratio continuous adjusting mode;

the power control module is further used for controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting a heating control mode of alternating complementary duty ratio and symmetrical duty ratio when the upper bridge switching tube of the slave heating module works in a hard on state.