CN114698171B

CN114698171B - Electromagnetic heating equipment and power control method and power control device thereof

Info

Publication number: CN114698171B
Application number: CN202011591745.1A
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: 2023-01-24
Anticipated expiration: 2040-12-29
Also published as: CN114698171A

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 a plurality of heating modules of the electromagnetic heating equipment work simultaneously, determining a slave heating module in the plurality of heating modules; controlling the output power of the slave heating module by adopting a power regulation mode of regulating the duty ratio, and determining whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not; 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 an alternative duty ratio heating control mode. According to the power control method provided by the embodiment of the invention, the upper bridge switching tube and the lower bridge switching tube alternately work in a hard switching-on state, the 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 a product 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 state from a soft switching 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 large 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 a plurality of heating modules of the electromagnetic heating equipment work simultaneously, determining a slave heating module in the plurality of heating modules; controlling the output power of the slave heating module by adopting a power regulation mode of regulating the duty ratio, and determining whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not; 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 an alternative duty ratio heating control mode.

According to the power control method of the electromagnetic heating equipment, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting an alternative duty ratio heating control mode 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 alternately work in the hard switching-on state, 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.

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 an upper bridge switching tube of the slave heating module is operated in a hard on state comprises: 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 operates in a hard on state comprises: detecting a midpoint voltage between an upper bridge switching tube and a lower bridge switching tube of the slave heating module; 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; 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 an alternate duty cycle heating control method includes: counting zero-crossing points of an input alternating current power supply of the electromagnetic heating equipment; determining whether the zero-crossing count value is an odd value; when the zero crossing point count value is an odd value, outputting a PWM signal of a forward duty ratio to the upper bridge switching tube and the lower bridge switching tube so as to heat the slave heating module; and when the zero crossing point count value is an even value, outputting a PWM signal with a reverse duty ratio to the upper bridge switching tube and the lower bridge switching tube so as to heat the secondary heating module.

According to some embodiments of the present invention, the duty ratio of the PWM signal output to the upper bridge switching tube is the forward duty ratio when the duty ratio is in the range of 0-50%, and the duty ratio of the PWM signal output to the upper bridge switching tube is the reverse duty ratio when the duty ratio is in the range of 51-100%

According to some embodiments of the invention, determining a slave heating module of the plurality of heating modules comprises: and obtaining the heating module with the maximum input power from the plurality of heating modules, taking the heating module with the maximum input power as a main heating module, and taking the rest heating modules from 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 frequency-modulated power regulation.

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, the power control program of the electromagnetic heating apparatus implementing a power control method of the electromagnetic heating apparatus according to an embodiment of the present invention when executed by a processor.

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 device for an electromagnetic heating apparatus, including: the device comprises a first determining module, a second determining module and a control module, wherein the first determining module is used for determining a slave heating module in a plurality of heating modules when the plurality of heating modules of the electromagnetic heating equipment work simultaneously; the power control module is used for controlling the output power of the secondary heating module in a power regulation mode of regulating the duty ratio; the second determining module is used for determining whether an upper bridge switching tube of the slave heating module works in a hard-on state or not when the power control module controls the output power of the slave heating module in a power regulation mode of regulating the duty ratio; the power control module is also used for controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting an alternative duty ratio heating control mode when the upper bridge switching tube of the slave heating module works in a hard switching-on state.

According to the power control device 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 an alternative duty ratio heating control mode 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 alternately work in the hard switching-on state, heat generated by hard switching-on 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.

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 flow chart illustrating a step S1 of a power control method according to an embodiment of the present 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 schematic flow diagram 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 continuous duty cycle control scheme and an alternating duty cycle heating control scheme in accordance with an embodiment of the present invention;

fig. 16 is an operation waveform diagram for outputting a PWM signal of a forward duty ratio and a PWM signal of a reverse 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 an alternating duty cycle heating control scheme in accordance with 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 first determination module 30; a second determination module 40;

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 the electromagnetic heating device works with only one heating module 50, the heating module 50 may be used as a master heating module or a slave heating module to perform output power control in a corresponding power regulation manner.

In a specific embodiment according to the present invention, as shown in fig. 3, the type of the corresponding heating module 50 is determined in step S1 according to the input power of each heating module 50, 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: according to the type of each heating module 50, the output power of the corresponding heating module 50 is controlled in different power regulation modes. 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 different types of heating modules 50, so that the consistency of the working frequency of a plurality of heating modules 50 which work simultaneously is facilitated, a series of synthetic frequencies generated by mixing various frequencies in the working process are avoided, sharp and harsh noise generated by synthesizing differential frequency signals is avoided, and the use experience of a user is improved.

For example, in some embodiments, step S2: according to the type of each heating module 50, the output power of the corresponding heating module 50 is controlled by adopting different power regulation modes, 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, and 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 first resonant capacitor pairs 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; 5363 the power control device 100 of the electromagnetic heating device … … outputs PWM signals to the driving module, the driving module outputs complementary PWM signals to control the upper bridge switching tube and the lower bridge switching tube to be alternately conducted, the heating coil is controlled to output alternating current to generate an alternating magnetic field, the alternating magnetic field induces an alternating eddy current in a metal pot placed on the heating coil, and the alternating eddy current causes the pot to heat, thereby heating 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 f0 to 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 the 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 PWM waveform of the main heating module as W10 waveform in fig. 7, outputs a power of 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 heating module to 1500W, steps S212 and S213 are executed until the output power of the main heating module is equal to the input power, and then the power control apparatus 100 outputs the PWM waveform of the main heating module as W11 waveform in fig. 7, the output power is P11 (1500W) in fig. 5, and the corresponding PWM frequency is f11 (23 KHz) in fig. 5. It can be seen that the frequency of the PWM output from the power control device 100 is reduced from 25KHz (f 10) to 23KHz (f 11), and the output power is increased from 1000W to 1500W.

If the user adjusts the heating power to be reduced to 500W, that is, if the input power to the main heater module is adjusted to 500W, steps S214 and S215 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 main heater module PWM waveform as shown by W12 in fig. 7, the output power is shown by P12 (500W) in fig. 5, and the corresponding PWM frequency is shown by f12 (27 KHz) in fig. 5. It can be seen that the frequency of the PWM output from the power control device 100 is increased from 25KHz (f 10) to 27KHz (f 12), and the output power is reduced 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 duty ratio of the slave heater module in relation to the output power when the half-bridge switch 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 greater 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 is a PWM waveform of the power control device 100 outputting the main heater module, and the duty ratio is 50%. The waveform W21 is a PWM waveform outputted from the power control device 100 to the slave heater module, and has a duty ratio of 30% (corresponding to P20 in fig. 8), and it can be seen that the PWM period (T10 in fig. 10) of the master heater module is equal to the PWM period (T20 in fig. 1) of the slave heater module, and the PWM frequency of the slave heater module is equal to the PWM frequency of the master heater module, as represented by the formula frequency f = 1/T.

If the user adjusts the increase of the heat power from 500W to 600W, that is, adjusts the input power from the heater module to 600W, the power control device 100 outputs the waveform from the heater module PWM as W22 in FIG. 10 after executing steps S222 and S223 until the output power from the heater module is equal to the input power, at which time the high level time from 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 heater module 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 waveform in FIG. 10, when the high level 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 achieved.

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 manners 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, thereby avoiding the generation of a synthesized frequency due to the mixing of multiple frequencies during the work process, avoiding the generation of sharp and harsh noise due to the synthesis of a difference frequency signal, and being beneficial to improving the use experience of a user.

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 that the number of the slave heating modules is multiple, the output powers of the slave heating modules can be independently controlled without mutual interference, the frequency consistency can be well kept, and the power adjusting method is simpler.

In some embodiments, the fixed duty cycle of the first PWM signal is 50% and the duty cycle of the second PWM signal is adjustable from 0 to 50% so that the output power of the slave heating module is adjusted within a range less 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 device is in operation, the output power of the heating module 50 is controlled by using a frequency-modulated power adjustment method, 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 embodiment of the present invention may include: a first determination module 30, a power control module 20, and a second determination module 40.

The first determining module 30 is configured to determine a slave heating module of the plurality of heating modules 50 when the plurality of heating modules 50 of the electromagnetic heating device are simultaneously operated, and functions as the determining module 10 of the power control apparatus 100 according to the embodiment of the second aspect of the present invention. The power control module 20 is configured to control the output power from the heating module in a duty-adjusted power adjustment manner. The second determining module 40 is configured to determine whether an upper bridge switching tube of the slave heating module operates in a hard on state when the power control module 20 controls the output power of the slave heating module in a duty-adjusted power adjustment manner. In addition, the power control module 20 is further configured to control the upper bridge switching tube and the lower bridge switching tube by using an alternating duty ratio heating control manner when the upper bridge switching tube of the slave heating module operates 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:

and step S3: when the plurality of heating modules 50 of the electromagnetic heating apparatus are simultaneously operated, the slave heating module among the plurality of heating modules 50 is determined.

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.

And step S4: and controlling the output power of the slave heating module by adopting a power regulation mode of regulating the duty ratio, and determining whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not.

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: determining whether the upper bridge switching tube of the 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: determining whether the upper bridge switching tube of the heating module works in a hard on state or not may include steps S43, S44 and S45, which are as follows:

step S43: detecting a 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 turned on, 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 a first heating module 200 and a 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 pair of

resonant capacitors

205 and 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 below 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 (g 1) driving waveform of the second upper bridge switching tube 302, W11 is the gate (g 2) driving waveform of the second lower bridge switching tube 303, and W12 is the second half-bridge midpoint (g 3) voltage waveform.

At the 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 detection module 307 acquires a 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 (g 3) is a high level 310V, which is equal to the supply voltage (VC 2), 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 the time t12, at the time when the duty ratio of the PWM signal is large, the power control device 100 detects that the voltage of the second half-bridge midpoint voltage (g 3) is 0V, which is a low level and is equal to ground voltage, and then the voltage difference between the collector and the 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 the 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 tube 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 (g 3) is at the low level 0V, the supply voltage VC2 is 310V, the voltage difference between the collector and the emitter of the second upper bridge switching tube 302 is equal to 310V, and the power control device 100 determines that the second upper bridge switching tube 302 is in the hard-on state. In this case, the second upper bridge switching tube 302 has large loss and high temperature, which may cause damage to the second upper bridge switching tube 302.

According to some embodiments of the present invention, before determining whether the upper bridge switching tube of the heating module is operated in the hard on state in step S4, the method may further include the following steps: and determining to control the slave heating module by adopting a continuous duty ratio control mode. The continuous duty ratio control mode means that in two continuous adjacent PWM signal periods, the upper bridge switching tube and the lower bridge switching tube are heated at the same duty ratio. 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 continuous duty ratio control 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 an alternative duty ratio heating control mode.

The alternating duty ratio heating control mode is that the PWM duty ratio of the upper bridge switching tube in the current unit time and the PWM duty ratio of the lower bridge switching tube in the next unit time are complementarily changed by taking one PWM signal period as the unit time, and the PWM duty ratio of the lower bridge switching tube in the current unit time and the PWM duty ratio of the lower bridge switching tube in the next unit time are complementarily changed. For example, if the PWM duty ratio of the upper bridge switching tube is 20% and the PWM duty ratio of the lower bridge switching tube is 80% in the current unit time, the PWM duty ratio of the upper bridge switching tube is 80% and the PWM duty ratio of the lower bridge switching tube is 20% in the next unit time.

In other words, after the upper bridge switching tube and the lower bridge switching tube are controlled by adopting the alternating duty ratio heating control method, the hard switching state of a single upper bridge switching tube is originally improved into the hard switching state of the upper bridge switching tube and the lower bridge switching tube, the heat generated by hard switching is independently born and improved into the common sharing of 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 switching tube and the lower switching tube by using an alternating duty cycle heating control manner may include steps S51 to 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 a PWM signal of a forward duty ratio 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 reverse duty ratio to the upper bridge switching tube and the lower bridge switching tube so as to heat the secondary 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 forward duty ratio or a PWM signal with a reverse duty ratio to the upper switching tube and the lower switching tube when a next zero-crossing signal arrives.

Fig. 15 is a waveform diagram showing operation according to the continuous duty heating control method and the alternate duty heating control method. Fig. 16 is a waveform diagram showing the operation of outputting a PWM signal of a forward duty ratio and a PWM signal of a reverse duty ratio.

In fig. 15, a W20 waveform is a half-bridge supply (VC 1, VC 2) voltage waveform, and Z10, Z11, Z12, and the like are zero-crossing marks of an input ac power supply of the electromagnetic heating apparatus. In the time periods D10 to D14 of the W21 waveform, the duty ratios of the operation of the upper bridge switching tube and the lower bridge switching tube are not changed, and the M1-stage operation waveform shown in fig. 16 corresponds to a continuous duty ratio heating control mode. The switching process of M1 and M2 in the time periods D15 to 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 alternating duty cycle heating control method.

As shown in fig. 15, assuming that the duty ratio of the current PWM signal is 20%, before time t31, the power control apparatus 100 adopts the continuous duty ratio heating control manner, 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 period M1 of W31 in fig. 16.

At time t31, the power control apparatus 100 detects that the upper bridge switching tube is in a hard-on state, switches to an alternate duty cycle heating control mode, 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 apparatus 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 apparatus 100 outputs a PWM signal with a reverse duty ratio, that is, the upper bridge switching tube operates at 80% duty ratio, as shown in the M2 period of W30 in fig. 16; the lower bridge switching tube operates at 20% duty cycle as shown by the period M2 of W31 in fig. 16. As can be seen from fig. 15, at this stage, when the upper bridge switching tube is turned on, 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 a soft on state, and when the lower bridge switching tube is turned on, 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 a 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 apparatus 100 executes the method shown in fig. 17, and after the zero-crossing counter performs the addition operation of 1, the value of CNT is 2, which is an even number,

the power control device 100 outputs a PWM signal with a forward duty cycle, i.e. the upper bridge switching tube operates at a duty cycle of 20%, as shown in a period M1 of W30 in fig. 16; the lower bridge switching tube operates at 80% duty cycle as shown by the period M1 of W31 in fig. 16. As can be seen from fig. 15, at this stage, when the upper bridge switching transistor is turned on, the upper bridge switching transistor operates in a hard on state, and when the lower bridge switching transistor is turned on, the lower bridge switching transistor operates in a soft on state. The upper bridge switch tube has large loss and high temperature, and the lower bridge switch tube has small loss and low temperature rise.

Therefore, after the heating control mode with the alternating duty ratio is adopted, the upper bridge switching tube and the lower bridge switching tube work in a hard switching-on state alternately to share heat generated by hard switching-on, 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.

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 period, T2 is the PWM period, and the duty ratio is equal to T1/T2. For a half-bridge circuit with two switching tubes, the PWM switch of the upper switching tube and the PWM switch of the lower switching tube are complementarily turned on and off, in other words, when the upper switching tube is turned on, the lower switching tube is turned off, and when the upper switching tube is turned off, the lower switching tube is turned on, so that the upper switching tube and the lower switching tube are not simultaneously turned on.

Therefore, for the power control device 100 to output a PWM value of a duty cycle, the duty cycle value of the upper bridge switching tube and the duty cycle value of the lower bridge switching tube are complementary. For example, if the power control device 100 outputs a 20% duty ratio PWM value, the upper bridge switching tube PWM duty ratio is 20%, and the lower bridge switching tube PWM duty ratio is 80%. For a half-bridge switching heating system, 20% the output power of the PWM duty cycle is equal to 80% the output power of the PWM duty cycle. Therefore, when the duty ratio of the PWM signal output to the upper bridge switching tube is in the range of 0-50%, it is called a forward duty ratio, and when the duty ratio of the PWM signal output to the upper bridge switching tube is in the range of 51-100%, it is called a reverse duty ratio.

In addition, in the half-bridge circuit, during the switching-off of any one switch tube to the switching-on of the other switch tube, there is a time period (about 2 us) during which both switch tubes are switched off, which is called dead time (dead time), as shown in the time periods d1 and d2 in fig. 14, because when the gate PWM driving signal of the switch tube is switched from high level to low level, the current flowing through the collector and the emitter of the switch tube is not immediately switched off, and a certain time (about 0.5 us) is required for complete switching-off, so the dead time is used for preventing the upper bridge switch tube and the lower bridge switch tube from short-circuiting and passing through, and improving the service life and the safety.

According to the power control method of the electromagnetic heating device in the embodiment of the third aspect of the invention, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting an alternative duty ratio heating control mode 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, 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 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 operates in the hard on state, the upper bridge switch tube and the lower bridge switch tube are controlled by an alternate duty ratio heating control manner, so that the upper bridge switch tube and the lower bridge switch tube alternately operate in the hard on state, share heat generated by hard on, reduce temperature rise of the upper bridge switch tube, prevent the upper bridge switch tube from operating in the hard on state for a long time and being damaged, and improve the service life and reliability of the electromagnetic heating apparatus.

In the embodiment of the fourth aspect of the present invention, reference may be made to the power control method of the electromagnetic heating apparatus according to the third aspect of the present invention for the method for determining the slave heating module by the first determining module 30, the method for controlling the output power of the slave heating module by the power control module 20 in the duty-adjusted power adjustment manner, the method for determining whether the upper bridge switch of the slave heating module operates in the hard-on state by the second determining module 40, and the method for controlling the upper bridge switch tube and the lower bridge switch tube by the power control module 20 in the alternating duty-duty heating control manner, which 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 the upper bridge switching tube and the lower bridge switching tube of the heating module are controlled by using an alternate duty ratio heating control manner when the upper bridge switching tube is in the hard on state, so that the upper bridge switching tube and the lower bridge switching tube are alternately operated in the hard on state, and share the heat generated by the hard on, thereby reducing the temperature rise of the upper bridge switching tube, avoiding the upper bridge switching tube from being damaged due to long-time operation in the hard on state, and improving the service life and reliability of the electromagnetic heating device.

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, the upper bridge switching tube and the lower bridge switching tube are controlled by adopting the alternating duty ratio heating control manner when the upper bridge switching tube of the heating module works in the hard on state, so that the upper bridge switching tube and the lower bridge switching tube alternately work in the hard on state, share heat generated by 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 of the 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, such as 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). Further, 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," "lateral," "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, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of 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 according to specific situations by those of ordinary skill in the art.

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 will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, 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 a plurality of heating modules of the electromagnetic heating equipment work simultaneously, determining a slave heating module in the plurality of heating modules;

controlling the output power of the slave heating module by adopting a power regulation mode of regulating the duty ratio, and determining whether an upper bridge switching tube of the slave heating module works in a hard switching-on state or not;

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 an alternative duty ratio heating control mode.

2. A power control method for an electromagnetic heating apparatus as set forth in claim 1, wherein determining whether an upper bridge switching tube of said slave heating module is operating in a hard on state comprises:

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 an electromagnetic heating device according to claim 1, wherein determining whether the upper bridge switching tube of the slave heating module is operated in a hard on state comprises:

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

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;

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 apparatus 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 an alternate duty cycle heating control manner comprises:

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

determining whether the zero-crossing count value is an odd value;

when the zero crossing point count value is an odd value, outputting a PWM signal of a forward duty ratio to the upper bridge switching tube and the lower bridge switching tube so as to heat the slave heating module;

and when the zero crossing point count value is an even value, outputting a PWM signal with a reverse duty ratio to the upper bridge switching tube and the lower bridge switching tube so as to heat the secondary heating module.

5. The power control method of the electromagnetic heating apparatus according to claim 4, wherein the duty ratio of the PWM signal outputted to the upper bridge switching tube is the forward duty ratio when the duty ratio is in the range of 0-50%, and the duty ratio of the PWM signal outputted to the upper bridge switching tube is the reverse duty ratio when the duty ratio is in the range of 51-100%.

6. A power control method for an electromagnetic heating apparatus as set forth in claim 1, wherein determining a slave heating module among the plurality of heating modules comprises:

and obtaining the heating module with the maximum input power from the plurality of heating modules, taking the heating module with the maximum input power as a main heating module, and taking the rest heating modules from 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. A power control method for an electromagnetic heating apparatus according to claim 8, wherein the controlling the output power of the slave heating module by a duty-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, when executing the power control program, implements the power control method of the electromagnetic heating apparatus according to any one of claims 1 to 9.

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

the device comprises a first determining module, a second determining module and a control module, wherein the first determining module is used for determining a slave heating module in a plurality of heating modules when the plurality of heating modules of the electromagnetic heating equipment work simultaneously;

the power control module is used for controlling the output power of the secondary heating module in a power regulation mode of regulating the duty ratio;

the second determining module is used for determining whether an upper bridge switching tube of the slave heating module works in a hard-on state or not when the power control module controls the output power of the slave heating module in a power regulation mode of regulating the duty ratio;

the power control module is also used for controlling the upper bridge switching tube and the lower bridge switching tube of the slave heating module by adopting an alternative duty ratio heating control mode when the upper bridge switching tube of the slave heating module works in a hard switching-on state.