A control method and circuit for a high-power heating element

Abstract

The application relates to the technical field of electronic circuits, and discloses a control method of a high-power heating element, which comprises the following steps: S10, acquiring an over-zero signal of an alternating-current power supply through an over-zero detection circuit; S20, outputting the over-zero signal to a main control circuit; S30, outputting a control signal to a bidirectional thyristor driving circuit according to the over-zero signal by the main control circuit; and S40, controlling a load circuit according to the control signal by the bidirectional thyristor driving circuit, wherein the load circuit is used for controlling the conduction or disconnection of the heating element; wherein the heating element comprises at least two parallel heating modules, each heating module corresponds to a bidirectional thyristor driving circuit, the bidirectional thyristor driving circuit controls the on-off of each heating module at different time points, preferentially ensures that the power period of the heating element is minimum, and the bidirectional thyristor driving circuit controls the on-off of each heating module at different time points, so that the maximum value of the power difference of the heating element in the T / 2 time period before and after each over-zero point is minimum.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic circuit, in particular to a control method and circuit of a high-power heating element. BACKGROUND

[0002] EMC test (electromagnetic compatibility test) is used to evaluate the performance of electronic equipment in the electromagnetic environment, including the resistance of the equipment to electromagnetic interference (anti-interference) and the control of the electromagnetic interference (radiation) generated by the equipment itself. Its goal is to ensure that the equipment does not interfere with other equipment, nor is it disturbed by other equipment. High-power heating element, i.e. under the standard AC voltage (AC 220V, AC 230V or AC 240V), standard frequency (50Hz or 60Hz), load current >= 16A, i.e. load power >= 3520W heating element. High-power heating elements are generally used to heat liquids, gases or solids and other substances. In many application scenarios, high-power heating elements need to be quickly heated to different temperatures, and bidirectional thyristors are generally used to control the heating elements to achieve multiple different gear powers.

[0003] At present, there are single heating tube high-power heating elements, 2-branch heating tube high-power heating elements, 3-branch or more heating tube high-power heating elements, etc. on the market. For single heating tube high-power heating elements, if the traditional bidirectional thyristor control method is used, the heating element is divided into multiple different gear powers using the phase-shift triggering method, and in the process of EMC test, the circuit will generate a large electromagnetic interference, which causes the grid voltage waveform to be distorted and increases the harmonic pollution of the grid, thereby making it difficult to pass the conducted interference test in EMC test. If the bidirectional thyristor uses the zero-crossing triggering method to divide the heating element into multiple different gear powers, the on-off ratio is too small when the minimum gear power is used, and when the grid capacity is not large enough, phenomena such as flickering of the light and shaking of the meter pointer will occur, which makes it difficult to pass the voltage fluctuation and flicker test in EMC test. For 2-branch and 3-branch or more heating tube high-power heating elements (load current >= 16A), if the traditional bidirectional thyristor control method is still used, the pass rate of EMC test is also challenged.

[0004] Therefore, there is an urgent need for a control method that improves the pass rate of high-power heating elements in EMC test. SUMMARY

[0005] The technical problem to be solved by the present application is to solve the low pass rate of existing high-power heating elements in EMC test.

[0006] In order to solve the above technical problems, the present application provides a control method of a high-power heating element, characterized in that the control method of the heating element comprises:

[0007] S10, obtaining a zero-crossing signal of an alternating current power supply by a zero-crossing detection circuit;

[0008] S20, outputting the zero-crossing signal to a master control circuit;

[0009] S30, outputting a control signal to a triac drive circuit according to the zero-crossing signal by the master control circuit;

[0010] S40, controlling a load circuit according to the control signal by the triac drive circuit, the load circuit being used for controlling the heating element to turn on or off; wherein the heating element comprises at least two parallel heating modules, each of the heating modules corresponds to one of the triac drive circuits, the triac drive circuits control the on-off of each of the heating modules at different times to preferentially ensure that the minimum power cycle of the heating element is the smallest, and the triac drive circuits control the on-off of each of the heating modules at different times to ensure that the maximum value of the power difference of the heating element in the T / 2 time period before and after each zero-crossing point is the smallest.

[0011] Further, the number of the heating modules is 2, the two heating modules are a first heating module and a second heating module respectively, the first heating module and the second heating module are parallel, and the power of the first heating module is smaller than the power of the second heating module.

[0012] Further, the control method of the heating element further comprises:

[0013] The heating element outputs the power of multiple gears according to the requirement of the load circuit.

[0014] Further, the power difference of each adjacent gear of the multiple gears is equal.

[0015] According to another aspect of the present application, there is provided a circuit of a high-power heating element, the circuit of the heating element comprising:

[0016] an alternating current power supply, the alternating current power supply being used for providing alternating current;

[0017] a zero-crossing detection circuit, the zero-crossing detection circuit being used for obtaining a zero-crossing signal of the alternating current power supply and outputting the zero-crossing signal to a master control circuit;

[0018] a master control circuit, the master control circuit being used for outputting a control signal to a triac drive circuit according to the zero-crossing signal;

[0019] a triac drive circuit, the triac drive circuit being used for controlling a load circuit according to the control signal;

[0020] A load circuit is configured to control the heat generating element, wherein the heat generating element comprises two or more heat generating modules connected in parallel, and each of the heat generating modules corresponds to one of the triac driving circuits.

[0021] Further, the load circuit outputs different power gears by controlling the on or off time of the heat generating modules in the heat generating element.

[0022] Compared with the prior art, the control method for the high-power heat generating element passing EMC test has the following advantages:

[0023] In the embodiment of the present application, the triac driving circuits are used to control the on or off of each heat generating module at different time, so as to ensure that the minimum power cycle of the heat generating element is guaranteed, and the smaller the cycle of the heat generating element is, the shorter the interference time of the heat generating element to the circuit is, and the smaller the interference of the heat generating element to the circuit is. Therefore, the power cycle of the heat generating element is set to be the minimum, so as to improve the possibility of passing EMC test of the circuit, and the success rate of passing EMC test of the control method is improved. In the embodiment of the present application, the triac driving circuits are used to control the on or off of each heat generating module at different time, so as to ensure that the maximum value of the power difference of the heat generating element in the T / 2 time period before and after each zero-crossing point is the minimum. Since the larger the maximum value of the power difference of the heat generating element is, the larger the change range of the power of the heat generating element is, and the larger the interference of the heat generating element to the circuit is, the maximum value of the power difference of the heat generating element is set to be the minimum, so as to reduce the interference of the heat generating element to the circuit, and the success rate of passing EMC test of the control method is improved. In the embodiment of the present application, only a plurality of heat generating modules are connected in parallel, and a corresponding number of triac driving circuits and zero-crossing detection circuits are set, so as to realize low-cost EMC test. Since the plurality of heat generating modules are connected in parallel, the total power of the circuit passing EMC test can be greatly improved. The total power of the heat generating element is distributed to each heat generating module, and the smaller the power of each heat generating module is, the smaller the interference of the heat generating element to the circuit is, and the success rate of passing EMC test of the control method is improved. In the embodiment of the present application, the heat generating power of each heat generating module can be controlled, so as to affect the power of the heat generating element, realize multi-gear adjustment of the heat generating element, and each gear can pass EMC test. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a flow chart of the control method for the high-power heat generating element provided by the embodiment of the present application;

[0025] Figure 2 is a comparison chart of load circuit parameters of each gear of the B heat generating element and the C heat generating element in the control method for the high-power heat generating element provided by the embodiment of the present application.

[0026] Figure 3 is a circuit diagram of the control method of the high-power heating element provided by the embodiment of the present application;

[0027] Figure 4 is another circuit diagram of the control method of the high-power heating element provided by the embodiment of the present application;

[0028] Figure 5 is a load circuit parameter diagram of each gear of the control method of the high-power heating element provided by the embodiment of the present application;

[0029] Figure 6 is Figure 5 is a table diagram in the load circuit parameter diagram of each gear. DETAILED DESCRIPTION

[0030] Exemplary embodiments of the present application are described herein below with reference to the accompanying drawings, in which various details of the embodiments of the present application are set forth to facilitate an understanding, and should be considered in a descriptive sense. It will be readily appreciated that various modifications and changes can be made to the embodiments described herein without departing from the scope of the application. Likewise, the present application is not to be limited to the details of the described embodiments, but can be implemented with various changes and modifications that will be apparent to one ordinarily skilled in the art. It will be readily appreciated that the various embodiments of the present application are suitable for a wide range of applications, some of which are described herein, and the present application should be understood to include any such applications in which the stated features are practiced within the scope of the present application. The objectives of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0031] As shown in Figure 1 , Figure 2 and Figure 3 , in an optional embodiment of the present application, the control method of the heating element comprises:

[0032] S10, obtaining a zero-crossing signal of an alternating power supply by a zero-crossing detection circuit;

[0033] S20, outputting the zero-crossing signal to a main control circuit;

[0034] S30, outputting a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal by the main control circuit;

[0035] S40, controlling a load circuit according to the control signal by the bidirectional thyristor drive circuit, the load circuit being used for controlling the heating element to turn on or off; wherein the heating element comprises at least two parallel heating modules, each of the heating modules corresponds to one of the bidirectional thyristor drive circuits, the bidirectional thyristor drive circuits preferentially guarantee the minimum power cycle of the heating element by controlling the on-off of each of the heating modules at different time, and the bidirectional thyristor drive circuits guarantee the minimum maximum value of the power difference of the heating element in the T / 2 time period before and after each zero-crossing point.

[0036] The zero-crossing detection circuit is used to detect the zero-crossing signal of the alternating current. For example, in AC mains power, a zero-crossing signal is generated every half-cycle T / 2. When the frequency F of the AC current is 50Hz, T = 20ms; when the frequency of the AC current is 60Hz, T ≈ 16.667ms. The zero-crossing signal refers to the signal at the zero-voltage point of the AC current waveform. Specifically, when the AC current transitions from positive to negative (or vice versa), the voltage value is zero, and this moment is called the "zero-crossing point". In the zero-crossing detection circuit, after detecting this point, corresponding control or switching operations can be performed to achieve precise phase control. This method of detecting the zero-crossing point can reduce electromagnetic interference and improve the efficiency and stability of the circuit system. In this embodiment of the invention, the detected zero-crossing signal is transmitted to the bidirectional thyristor to control the conduction or shutdown of the heating element through zero-crossing triggering.

[0037] The bidirectional thyristor drive circuit controls the on / off state of each heating module at different times, prioritizing the minimization of the power cycle of the heating element. The cycle of the heating element is a multiple of the AC current (1T, 2T, 3T, etc.). When configuring the power of the heating element, the shortest cycle should be selected first. Figure 2 In the diagram, Figures B1-B14 show the parameter diagrams for each setting of heating element B, and Figures C1-C14 show the parameter diagrams for each setting of heating element C. Both heating elements are divided into 14 settings, each with two heating modules. The total heating power of the two modules is equal. The green and blue curves represent the parameter diagrams of different heating modules at various time periods. The blue curve represents the first heating module, and the green curve represents the second heating module. At setting 2, comparing Figures B2 and C2, we can see that the power cycle of heating element B in Figure B2 is T, while the power cycle of heating element C in Figure C2 is 2T. Since the power cycle of heating element B (T) is less than that of heating element C (2T), the power change time of heating element B is shorter than that of heating element C. Because a shorter power change time results in less interference to the circuit, the power cycle of the heating element should be minimized when setting it. This improves the success rate of EMC testing for high-power heating elements. Figure 2 The B heating elements in the 2nd, 5th, 7th, 9th and 12th gears are all configured with the shortest cycle selected first.

[0038] Among these measures, prioritizing minimizing the power cycle of the heating element, the bidirectional thyristor drive circuit controls the on / off states of each heating module at different times to ensure that the maximum power difference of the heating element is minimized within the adjacent T / 2 time intervals before and after each zero-crossing point. For example, in... Figure 2In the drawings, Figs. B1-B14 are parameter diagrams of each gear position of the B heating element, and Figs. C1-C14 are parameter diagrams of each gear position of the C heating element. Both of the heating elements are divided into 14 gear positions and are provided with two heating modules. The total heating power of the two heating modules is equal. The output power of the first module is denoted as P 第一模块 , and the output power of the second module is denoted as P 第二模块 . The green curve and the blue curve represent the parameter diagrams of different heating modules in each time period. The blue curve represents the first heating module, and the green curve represents the second heating module. In the sixth gear, by comparing Figs. B6 and C6, it can be seen that the period of the B heating element in Fig. B6 and the period of the C heating element in Fig. C6 are both 2T. They emit the same power in one period, but the current output waveforms are not the same. In Fig. B6, the time period in which the output power fluctuates most in the T / 2 time period adjacent to the zero crossing point is T / 2-3T / 2. The maximum power difference of the B heating element in Fig. B6 is the difference between the power of the heating element in the T / 2-T time period and the power of the heating element in the T-3T / 2 time period. Therefore, it is the difference between the output power of the second heating module in the T / 2-3T / 2 time period and 0, i.e., P 第二模块 -0=P 第二模块 ; in Fig. C6, the time period in which the output power fluctuates most in the T / 2 time period adjacent to the zero crossing point is 3T / 2-5T / 2. The maximum power difference of the C heating element in Fig. C6 is the difference between the sum of the output powers of the first and second heating modules in the 2T-5T / 2 time period and 0, i.e., P 第一模块 +P 第二模块 -0=P 第一模块 +P 第二模块 . Therefore, the maximum power difference of the B heating element in the T / 2 time period adjacent to the zero crossing point in Fig. B6 is less than the maximum power difference of the C heating element in the T / 2 time period adjacent to the zero crossing point in Fig. C6, i.e., P 第一模块 P 第一模块 +P 第二模块, so the B heating element should be selected to ensure that the maximum value of the power difference is minimum. By setting the maximum value of the power difference of the heating element to be minimum, the variation range of the power of the heating element can be reduced, the interference of the heating element to the circuit is reduced, and thus the success rate of the EMC test of the control method of the high-power heating element is improved. In the 8th gear, we can see from the comparison between FIG. B8 and FIG. C8 that the period of the B heating element in FIG. B8 and the period of the C heating element in FIG. C8 are both 2T, and the power emitted by them in one period of conduction is the same. In FIG. B8, the time period in which the output power fluctuates most in the T / 2 time period adjacent to the zero-crossing point is the 0-T time period. The maximum value of the power difference of the B heating element in FIG. B8 is the difference between the power of the heating element in the 0-T / 2 time period and the power of the heating element in the T / 2-T time period. Therefore, the difference between the output power of the first heating module in the 0-T / 2 time period and the sum of the output powers of the first heating module and the second heating module in the T / 2-T time period is P 第一模块 +P 第二模块 -P 第一模块 =P 第二模块 ; in FIG. C8, the time period in which the output power fluctuates most in the T / 2 time period adjacent to the zero-crossing point is the 3T / 2-5T / 2 time period. The maximum value of the power difference of the C heating element in FIG. C8 is the difference between the sum of the output powers of the first heating module and the second heating module in the 2T-5T / 2 time period and 0, i.e. P 第一模块 +P 第二模块 -0=P 第一模块 +P 第二模块 Therefore, the maximum value of the power difference of the B heating element in the T / 2 time period adjacent to the zero-crossing point in FIG. B8 is less than the maximum value of the power difference of the C heating element in the T / 2 time period adjacent to the zero-crossing point in FIG. C8, i.e. P 第二模块 <P 第一模块 +P 第二模块 , so the B heating element should be selected to ensure that the maximum value of the power difference is minimum. By setting the maximum value of the power difference of the heating element to be minimum, the variation range of the power of the heating element can be reduced, the interference of the heating element to the circuit is reduced, and thus the success rate of the EMC test of the control method of the high-power heating element is improved. The B heating elements in the 6th gear and the 8th gear in the figure are both realized by setting the maximum value of the power difference of the heating element to be minimum in the T / 2 time period adjacent to the zero-crossing point.

[0039] The embodiment of the present application controls the on-off of each heating module at different time through the bidirectional thyristor driving circuit, preferentially ensures the minimum power cycle of the heating element, and improves the possibility of passing EMC test and the success rate of passing EMC test of the control method, because the smaller the cycle of the heating element is, the shorter the interference time of the heating element to the circuit is, and the smaller the interference of the heating element to the circuit is; the embodiment of the present application controls the on-off of each heating module at different time through the bidirectional thyristor driving circuit, ensures the minimum maximum value of the power difference of the heating element in the T / 2 time period before and after each zero-crossing point, and improves the possibility of passing EMC test and the success rate of passing EMC test of the control method, because the larger the maximum value of the power difference of the heating element is, the larger the change range of the power of the heating element is, and the larger the interference of the heating element to the circuit is; the embodiment of the present application only needs to parallel multiple heating modules, sets the corresponding number of thyristor driving circuits and a zero-crossing detection circuit, and can realize low-cost EMC test, because the parallel connection of multiple heating modules can greatly improve the total power of the circuit passing EMC test, the multiple parallel heating modules can distribute the total power of the heating element to each heating module, the smaller the power of the single heating module is, the smaller the interference of the heating element to the circuit is, and the success rate of passing EMC test of the control method is improved; the embodiment of the present application can also control the heating power of each heating module and then affect the power of the heating element, realize multi-gear adjustment of the heating element, and each gear can pass EMC test.

[0040] As Figure 1 , Figure 4 , Figure 5 and Figure 6 indicate that, in an optional embodiment of the present application, the number of the heating modules is 2, the two heating modules are a first heating module and a second heating module respectively, the first heating module is parallel to the second heating module, and the power of the first heating module is less than that of the second heating module.

[0041] The power of the heating element is the sum of the powers of the parallel heating modules. The power of the heating element can be set to different gears to adapt to different scene requirements. Since the heating element is connected to alternating current, the power of the heating module is the power of the period of the heating module. The gear adjustment can be achieved by dividing the conduction time of a period to realize the power of a smaller heating module. For example, when the power of the heating module is 1000w and the period of the alternating current is T, when the heating module is conducted for the entire T, the heating power of the heating module is 1000w. When the heating module is conducted for 1 / 2T, the heating power of the heating module is 500w. When the power of the heating module is 1000w and the period of the heating module is 2T, when the heating module is conducted for the entire 2T, the heating power of the heating module is 1000w. When the heating module is conducted for 1 / 2 of the 2T, the heating power of the heating module is 500w. Different powers and different periods of the multiple heating modules can be set to cooperate with each other to divide the heating element into multiple gears.

[0042] Specifically, as shown in Figure 5 and Figure 6 , a preferred embodiment, in Figure 5 , Figure D is the voltage input waveform of the alternating current power supply; Figure E0 is the waveform when the load voltage is 0, and the corresponding load current is also 0 (shown in Figure F0), at this time the power of the heating element is 0. Figure Ex (x = 1-14) is the load voltage waveform of the xth gear, and the corresponding load current waveform of the xth gear is Figure Fx (x = 1-14). Wherein, the total power of the heating element is 5600w, the power of the first heating module is 1600w, and the power of the second heating module is 4000w; At this time, the heating element can be divided into 14 gears, the first gear: the period of the heating module is 2T, the first heating module is conducted for T / 2, and the second heating module is not conducted, at this time the power of the first gear of the heating element is 400W; The second gear: the period of the heating module is T, the first heating module is conducted for T / 2, and the second heating module is not conducted, at this time the power of the first gear of the heating element is 800W; The third gear: the period of the heating module is 2T, the first heating module is conducted for 3T / 4, and the second heating module is not conducted, at this time the power of the first gear of the heating element is 1200W; and so on, the parameters are shown in Figure 6 , the 14th gear: the period of the heating module is T, the first heating module is conducted for T, and the second module is conducted for T, at this time the power of the first module is 1600W, the power of the second module is 4000W, and the power of the heating element is 1600W+4000W=5600W. When the power of the first heating module is not equal to the power of the second heating module, the power of the first heating module and the power of the second heating module can be superimposed to have more gears. In this preferred embodiment, the power of the second heating module is 2.5 times the power of the first heating module, and the power difference of each gear is equal.

[0043] In the embodiment of the present application, the parallel configuration of the two heat generating modules provides more power gears. The first module has a small power, which is suitable for low demand scenarios, while the second module provides higher power to meet greater heat demand. The power of different heat generating modules can be set to different periods, so that the power of the heat generating element can be divided into multiple gears, and the multi-gear heat generating element meets the needs of different scenarios; smooth gear switching can also reduce the instantaneous current change and reduce the mutual interference between circuits, thereby improving the overall electromagnetic compatibility and the stability of the entire circuit and the pass rate of EMC test.

[0044] In an optional embodiment of the present application, the power difference between each adjacent gear of the multiple gears is equal.

[0045] Among them, adjacent gears refer to gears with close power in the heat generating element, for example, the power of the multiple gears of the heat generating element is 400W, 800W and 1200W, three gears, at this time, 400W and 800W, 800W and 1200W are adjacent gears, and the power difference between adjacent gears refers to that in a group of gears, the power difference between their adjacent gears is equal, for example, in the above example, 800W-400W=1200W-800W.

[0046] In the embodiment of the present application, the equal power difference between adjacent gears can make the heat change more stable when the user switches between different gears, thereby improving the user experience; it is helpful for the user to make more fine temperature adjustment according to the needs, and adapt to different environments and application requirements; the design of equal power difference also helps to maintain the stability of the circuit under each gear, thereby reducing the problem of mutual interference between circuits caused by excessive power adjustment fluctuation.

[0047] In the embodiment of the present application, a circuit of a high-power heat generating element passing EMC test is provided, and the circuit of the heat generating element comprises:

[0048] An alternating current power supply for providing alternating current;

[0049] A zero-crossing detection circuit for acquiring a zero-crossing signal of the alternating current power supply and outputting the zero-crossing signal to a main control circuit;

[0050] A main control circuit for outputting a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal;

[0051] A bidirectional thyristor drive circuit for controlling a load circuit according to the control signal;

[0052] A load circuit is configured to control the heat generating element, wherein the heat generating element comprises at least two heat generating modules connected in parallel, and each of the heat generating modules corresponds to one of the triac driving circuits.

[0053] The triac driving circuit controls the on-off of each heat generating module at different time points, thereby preferentially ensuring that the power cycle of the heat generating element is minimum.

[0054] The triac driving circuit controls the on-off of each heat generating module at different time points, thereby preferentially ensuring that the power cycle of the heat generating element is minimum. The triac driving circuit controls the on-off of each heat generating module at different time points, thereby preferentially ensuring that the power cycle of the heat generating element is minimum. The triac driving circuit controls the on-off of each heat generating module at different time points, thereby preferentially ensuring that the power cycle of the heat generating element is minimum. The triac driving circuit controls the on-off of each heat generating module at different time points, thereby preferentially ensuring that the power cycle of the heat generating element is minimum.

[0055] In an optional embodiment of the present application, the load circuit outputs different power gears by controlling the on or off time of the heat generating modules in the heat generating element.

[0056] The power of the heating module is the power of the period time of turning on one heating module, at this time, the gear adjustment can divide the on time of a period to realize the power of smaller heating module, for example, when the power of the heating module is 1000w, the period of the alternating current is T, when the period of the heating module is T, the heating power of the heating module is 1000w when turning on the whole T, and the heating power of the heating module is 500w when turning on 1 / 2T; at this time, different power gears can be output by controlling the on or off time of the heating module.

[0057] In the embodiment of the application, the different power gears output by controlling the on or off time of the heating module in the heating element can improve the experience of the user and adapt to different scene requirements.

[0058] It should be understood that the various forms of flow shown above can be reordered, added or deleted steps. For example, each step described in the application can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions disclosed in the application can be achieved, which is not limited herein.

[0059] The above specific embodiments do not constitute a limitation on the protection scope of the application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the principles of the application should be included in the protection scope of the application.

Claims

1. A control method of a high-power heat generating element, characterized by, The control method of the heating element comprises: S10, obtaining a zero-crossing signal of an alternating power supply through a zero-crossing detection circuit; S20, outputting the zero-crossing signal to a master control circuit; S30, the master control circuit outputs a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal; S40, the bidirectional thyristor drive circuit controls a load circuit according to the control signal, and the load circuit is used to control the heating element to be turned on or turned off; wherein the heating element comprises at least two parallel heating modules, each of the heating modules corresponds to one of the bidirectional thyristor drive circuits, and the bidirectional thyristor drive circuits control the on-off of each of the heating modules at different times to preferentially ensure that the power cycle of the heating element is minimum and the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero-crossing point is minimum.

2. The control method of a high-power heat generating element according to claim 1, characterized by, The number of the heating modules is 2, and the two heating modules are a first heating module and a second heating module, respectively; the first heating module and the second heating module are connected in parallel, and the power of the first heating module is less than the power of the second heating module.

3. The control method of a high-power heat generating element according to claim 2, characterized by, The control method of the heating element further comprises: The heating element outputs a plurality of gear powers according to the requirement of the load circuit.

4. The control method of a high-power heat generating element according to claim 3, characterized by, The power difference between each adjacent gear power in the plurality of gear powers is equal.

5. A circuit for a high-power heat-generating element, for use in the control method for a high-power heat-generating element according to claim 1, characterized in that, The circuit of the heating element comprises: An alternating power supply for providing alternating current; A zero-crossing detection circuit for obtaining a zero-crossing signal of the alternating power supply and outputting the zero-crossing signal to a master control circuit; A master control circuit for outputting a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal; A bidirectional thyristor drive circuit for controlling a load circuit according to the control signal; A load circuit for controlling the heating element to be turned on or turned off, wherein the heating element comprises at least two parallel heating modules, and each of the heating modules corresponds to one of the bidirectional thyristor drive circuits.

6. A circuit for a high power heat generating element according to claim 5, characterised in that, The load circuit outputs different power gears by controlling the on-off time of the heating modules in the heating element.

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