Control method and circuit of high-power heating element

Abstract

The invention relates to the technical field of electronic circuits, and discloses a control method of a high-power heating element. The control method comprises the following steps: S10, acquiring a zero-crossing signal of an alternating-current power supply through a zero-crossing detection circuit; s20, outputting the zero-crossing signal to a main control circuit; s30, the main control circuit outputs a control signal to the bidirectional silicon controlled rectifier driving circuit according to the zero-crossing signal; s40, the bidirectional silicon controlled rectifier drive circuit controls a load circuit according to the control signal, and the load circuit is used for controlling the heating element to be switched on or switched off; wherein the heating element comprises at least two heating modules which are connected in parallel, each heating module corresponds to one bidirectional silicon controlled rectifier driving circuit, and the bidirectional silicon controlled rectifier driving circuits preferentially ensure that the power period of the heating element is minimum by controlling the on-off of the heating modules at different moments respectively; the bidirectional silicon controlled rectifier drive circuit ensures that the maximum value of the power difference value of the heating elements in adjacent T / 2 time periods before and after each zero crossing point is minimum by respectively controlling the on-off of each heating module at different moments.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a control method and circuit for a high-power heating element. Background Art

[0002] EMC testing (electromagnetic compatibility testing) is used to evaluate the performance of electronic equipment in an electromagnetic environment, including the equipment's resistance to electromagnetic interference (anti-interference) and the control of electromagnetic interference (radiation) generated by the equipment itself. Its goal is to ensure that the equipment does not interfere with other equipment or be interfered with by other equipment. A high-power heating element is a heating element with a load current of >=16A, that is, a load power of >=3520W, at a standard AC voltage (AC220V, AC230V or AC240V) and a standard frequency (50Hz or 60Hz) of the mains. High-power heating elements are generally used to heat liquids, gases, solids and other substances. In many application scenarios, high-power heating elements need to be heated quickly to make the material reach different temperatures. Generally, a bidirectional thyristor is used to control the heating element to achieve multiple different gears of power.

[0003] At present, the high-power heating elements on the market include single-tube high-power heating elements, two-tube high-power heating elements, three-tube or more high-power heating elements, etc. For single-tube high-power heating elements, if the traditional bidirectional thyristor control method is used, the heating element is divided into multiple different gears of power by using the phase-shift trigger method, then during the EMC test, the circuit will generate large electromagnetic interference, which will cause the grid voltage waveform to be distorted and increase the grid harmonic pollution, making it difficult to pass the conducted interference test in the EMC test; if the bidirectional thyristor uses the zero-crossing trigger method to divide the heating element into multiple different gears of power, because the on-off ratio at the minimum gear power is too small, when the grid capacity is not large enough, there will be lighting flickering, meter pointer jitter and other phenomena, which makes it difficult to pass the voltage fluctuation and flicker test in the EMC test. For high-power heating elements with two and three or more heating tubes (load current>=16A), if the traditional bidirectional thyristor control method is still used, the pass rate of the EMC test is also facing challenges.

[0004] Therefore, there is an urgent need for a control method for improving the pass rate of high-power heating elements during EMC testing. Summary of the invention

[0005] The technical problem to be solved by the present invention is to solve the problem that the existing high-power heating elements have a low pass rate when performing EMC tests.

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

[0007] S10, obtaining a zero-crossing signal of the AC power supply through a zero-crossing detection circuit;

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

[0009] S30, the main control circuit outputs a control signal to the bidirectional thyristor drive circuit according to the zero-crossing signal;

[0010] S40, the bidirectional thyristor drive circuit controls the load circuit according to the control signal, and the load circuit is used to control the heating element to be turned on or off; wherein the heating element includes at least two heating modules connected in parallel, each heating module corresponds to one bidirectional thyristor drive circuit, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby preferentially ensuring that the power cycle of the heating element is minimized, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby ensuring that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized.

[0011] Furthermore, the number of the heating modules is 2, the two heating modules are respectively a first heating module and a second heating module, 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.

[0012] Furthermore, the control method of the heating element further includes:

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

[0014] Furthermore, the power difference between each adjacent gear position among the powers of the multiple gear positions is equal.

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

[0016] An alternating current power supply, the alternating current power supply being used to provide alternating current;

[0017] A zero-crossing detection circuit, the zero-crossing detection circuit is used to obtain a zero-crossing signal of the AC power supply and output the zero-crossing signal to a main control circuit;

[0018] A main control circuit, used for outputting a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal;

[0019] A bidirectional thyristor drive circuit, the bidirectional thyristor drive circuit is used to control the load circuit according to the control signal;

[0020] A load circuit, wherein the load circuit is used to control the heating element, wherein the heating element includes two or more heating modules connected in parallel, and each heating module corresponds to one bidirectional thyristor drive circuit.

[0021] Furthermore, the load circuit outputs different power gears by controlling the on or off time of the heating module in the heating element.

[0022] Compared with the prior art, the control method of a high-power heating element that passes the EMC test in the embodiment of the present invention has the following beneficial effects:

[0023] The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and preferentially ensures that the power cycle of the heating element is minimized. Since the smaller the cycle of the heating element is, the shorter the interference time of the heating element on the circuit is, the smaller the interference of the heating element on the circuit is. Setting the power cycle of the heating element to the minimum can increase the possibility of the circuit passing the EMC test, and improve the success rate of the control method passing the EMC test. The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and ensures that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized. Since the larger the maximum value of the power difference of the heating element is, the larger the variation of the power of the heating element is, the greater the interference of the heating element on the circuit is, and the power difference of the heating element is minimized. Setting the maximum value to the minimum can reduce the interference of the heating element on the circuit, thereby improving the success rate of the control method in passing the EMC test; the embodiment of the present invention only needs to connect multiple heating modules in parallel and set a corresponding number of thyristor drive circuits and zero-crossing detection circuits to achieve low-cost passing of the EMC test. Since a connection method in which multiple heating modules are connected in parallel is used, this method can greatly improve the total power of the circuit that passes the EMC test. Multiple heating modules connected in parallel can distribute the total power of the heating element to each heating module. The smaller the power of a single heating module, the less interference the heating element has on the circuit, thereby improving the success rate of the control method in passing the EMC test; the embodiment of the present invention can also control the heating power of each heating module to thereby affect the power of the heating element, thereby achieving multi-gear adjustment of the heating element, and each gear can pass the EMC test. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of a control method for a high-power heating element provided by an embodiment of the present invention;

[0025] Figure 2 It is a comparison diagram of load circuit parameters of heating elements B and C at various gears in the control method of a high-power heating element provided in an embodiment of the present invention.

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

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

[0028] Figure 5 It is a load circuit parameter diagram of each gear position of the step-by-step adjustment in the control method of the high-power heating element provided by the embodiment of the present invention;

[0029] Figure 6 yes Figure 5 The table diagram of the load circuit parameters for each gear position. DETAILED DESCRIPTION

[0030] The following is a description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope of the present invention. Similarly, for clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

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

[0032] S10, obtaining a zero-crossing signal of the AC power supply through a zero-crossing detection circuit;

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

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

[0035] S40, the bidirectional thyristor drive circuit controls the load circuit according to the control signal, and the load circuit is used to control the heating element to be turned on or off; wherein the heating element includes at least two heating modules connected in parallel, each heating module corresponds to one bidirectional thyristor drive circuit, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby preferentially ensuring that the power cycle of the heating element is minimized, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby ensuring that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized.

[0036] Among them, the zero-crossing detection circuit is used to detect the zero-crossing signal of the alternating current. For example, in the alternating current of the mains, a zero-crossing signal is generated in each half cycle T / 2. When the frequency F of the alternating current is 50Hz, T=20ms; when the frequency of the alternating current is 60Hz, T≈16.667ms. The zero-crossing signal refers to the signal of the alternating current waveform at the zero voltage point. Specifically, when the alternating 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 an embodiment of the present invention, the detected zero-crossing signal is used to be transmitted to the bidirectional thyristor to control the conduction or shutdown of the heating element by zero-crossing triggering.

[0037] Among them, the bidirectional thyristor drive circuit controls the on and off of each heating module at different times, and gives priority to ensuring that the power cycle of the heating element is the smallest. The cycle of the heating element is a multiple of the alternating current 1T, 2T, 3T... When configuring the power of the heating element, the smallest cycle should be selected first, for example, Figure 2 In the figure, Figure B1-B14 is the parameter diagram of each gear of the heating element B, and Figure C1-C14 is the parameter diagram of each gear of the heating element C. In the figure, the two heating elements are divided into 14 gears, and are each provided with two heating modules. The total heating power of the two heating modules is equal. The green curve and the blue curve represent the parameter diagrams of different heating modules in each time period, respectively. The blue curve represents the first heating module, and the green curve represents the second heating module. In the second gear, we can see from the comparison between Figure B2 and Figure C2 that the power cycle of the heating element B in Figure B2 is T, and the power cycle of the heating element C in Figure C2 is 2T. Since the power cycle of the heating element B is T, which is less than the power cycle of the heating element C, 2T, the power change time of the heating element B is less than the power change time of the heating element C. Because the shorter the power change time, the smaller the interference to the circuit, so when setting the power cycle of the heating element, the power cycle of the heating element should be guaranteed to be minimum, which can improve the success rate of the control method of the high-power heating element in passing the EMC test. Figure 2 The B heating elements in the 2nd, 5th, 7th, 9th and 12th gears are all configured with the smallest cycle being the priority when configuring the power cycle of the heating elements.

[0038] Wherein, under the premise of giving priority to minimizing the power cycle of the heating element, the bidirectional thyristor driving circuit controls the on and off of each heating module at different times to ensure that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized, for example, Figure 2In the figure, Figures B1-B14 are parameter diagrams of each gear of the B heating element, and Figures C1-C14 are parameter diagrams of each gear of the C heating element. In the figure, the two heating elements are divided into 14 gears, and both 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 recorded as P 第一模块 , the output power of the second module is recorded as P 第二模块 , the green curve and the blue curve represent the parameter diagrams of different heating modules in different time periods, the blue curve represents the first heating module, and the green curve represents the second heating module. In the 6th gear, we can see from the comparison between Figure B6 and Figure C6 that the period of the heating element B in Figure B6 and the period of the heating element C in Figure C6 are both 2T. The power they emit in one conduction cycle is the same, but their current output waveforms are not the same. In the T / 2 time period before and after the zero crossing in Figure B6, the time period with the largest output power fluctuation is the T / 2-3T / 2 time period. The maximum power difference of the heating element B in Figure 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, so it is the difference between the output power of the second heating module in the T / 2-3T / 2 time period and 0, that is, P 第二模块 -0=P 第二模块 In the T / 2 time period before and after the zero crossing in FIG. C6, the time period with the largest output power fluctuation is the time period of 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 heating module and the second heating module in the time period of 2T-5T / 2 and 0, that is, 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 heating element B in the T / 2 time period before and after the zero crossing in Figure B6 is less than the maximum value of the power difference of the heating element C in the T / 2 time period before and after the zero crossing in Figure C6, that is, P 第一模块 <P 第一模块 +P 第二模块In order to ensure that the maximum value of the power difference is the minimum, the B heating element should be selected. By setting the maximum value of the power difference of the heating element to the minimum, the variation of the power of the heating element can be reduced, and the interference of the heating element to the circuit can be reduced, thereby improving the success rate of the control method of the high-power heating element in passing the EMC test. In the 8th gear, we can see from the comparison of Figure B8 and Figure C8 that the period of the B heating element in Figure B8 and the period of the C heating element in Figure C8 are both 2T, and the power they emit in one conduction cycle is the same. In the T / 2 time period adjacent to the zero point in Figure B8, the time period with the largest output power fluctuation is the 0-T time period. The maximum value of the power difference of the B heating element in Figure 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, so it is 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, that is, P 第一模块 +P 第二模块 -P 第一模块 =P 第二模块 In the T / 2 time periods before and after the zero crossing in FIG. C8, the time period with the largest output power fluctuation is the time period of 3T / 2-5T / 2. The maximum 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 time period of 2T-5T / 2 and 0, that is, 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 heating element B in the T / 2 time period before and after the zero crossing in Figure B8 is less than the maximum value of the power difference of the heating element C in the T / 2 time period before and after the zero crossing in Figure C8, that is, P 第二模块 <P 第一模块 +P 第二模块 In order to ensure that the maximum value of the power difference is the minimum, the B heating element should be selected. By setting the maximum value of the power difference of the heating element to the minimum, the variation of the power of the heating element can be reduced, and the interference of the heating element to the circuit can be reduced, thereby improving the success rate of the control method of the high-power heating element in passing the EMC test. The B heating elements of the 6th and 8th gears in the figure are both set to minimize the maximum value of the power difference of the heating element in the T / 2 time period adjacent to the zero crossing point.

[0039] The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and preferentially ensures that the power cycle of the heating element is minimized. Since the smaller the cycle of the heating element is, the shorter the interference time of the heating element on the circuit is, the smaller the interference of the heating element on the circuit is. Setting the power cycle of the heating element to the minimum can increase the possibility of the circuit passing the EMC test, and improve the success rate of the control method passing the EMC test. The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and ensures that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized. Since the larger the maximum value of the power difference of the heating element is, the larger the variation of the power of the heating element is, the greater the interference of the heating element to the circuit is, and the minimum value of the power difference of the heating element is minimized. Setting the maximum value to the minimum can reduce the interference of the heating element on the circuit, thereby improving the success rate of the control method in passing the EMC test; the embodiment of the present invention only needs to connect multiple heating modules in parallel, set a corresponding number of thyristor drive circuits and a zero-crossing detection circuit to achieve low-cost passing of the EMC test. Since a connection method in which multiple heating modules are connected in parallel is used, this method can greatly improve the total power of the circuit that passes the EMC test. Multiple heating modules connected in parallel can distribute the total power of the heating element to each heating module. The smaller the power of a single heating module, the less interference the heating element has on the circuit, thereby improving the success rate of the control method in passing the EMC test; the embodiment of the present invention can also control the heating power of each heating module to thereby affect the power of the heating element, thereby achieving multi-gear adjustment of the heating element, and each gear can pass the EMC test.

[0040] like Figure 1 , Figure 4 , Figure 5 and Figure 6 As shown, in an optional embodiment of the present invention, the number of the heating modules is 2, the two heating modules are respectively a first heating module and a second heating module, 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.

[0041] Among them, the power of the heating element is the sum of the powers of the heating modules in parallel. 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 here is the power of the cycle time of a heating module. The gear adjustment at this time can achieve a smaller power of the heating module by dividing the conduction time of a cycle. For example, when the power of the heating module is 1000w, the cycle of the alternating current is T, when the cycle of the heating module is T, the heating power of the heating module for the entire T time is 1000w, and when it is turned on for 1 / 2T, the heating power of the heating module is 500w; when the power of the heating module is 1000w, when the cycle of the heating module is 2T, the heating power of the heating module for the entire 2T time is 1000w, and when it is turned on for 1 / 2 of 2T, the heating power of the heating module is 500w. The different powers of multiple heating modules and the setting of different cycles can cooperate with each other to divide the heating element into multiple gears.

[0042] Specifically, Figure 5 and Figure 6 As shown, a preferred embodiment, in Figure 5 Figure D is the voltage input waveform of the AC power supply; Figure E0 is the waveform when the load voltage is 0, and its corresponding load current is also 0 (as shown in Figure F0), and the power of the heating element is 0 at this time. Figure Ex (x = 1-14) is the load voltage waveform of the xth gear, and its corresponding load current waveform of the xth gear is Figure Fx (x = 1-14). Among them, 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 cycle of the heating module is 2T, the first heating module is turned on for T / 2 time, and the second heating module is not turned on. At this time, the power of the first gear of the heating element is 400W; the second gear: the cycle of the heating module is T, the first heating module is turned on for T / 2 time, and the second heating module is not turned on. At this time, the power of the first gear of the heating element is 800W; the third gear: the cycle of the heating module is 2T, the first heating module is turned on for 3T / 4 time, and the second heating module is not turned on. At this time, the power of the first gear of the heating element is 1200W; and so on, for detailed parameters, see Figure 6 , 14th gear: the cycle of the heating module is T, the time of turning on the first heating module is T, and the time of turning on the second module is 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. Among them, when the power of the first heating module is different from the power of the second heating module, the power between them 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 an embodiment of the present invention, two heating modules are configured in parallel to provide more power gears. The first module has a smaller power and is suitable for low-demand scenarios, while the second module provides higher power to meet greater heat requirements. The power of different heating modules can be set in different cycles, so that the power of the heating element can be divided into multiple gears, and the heating element with multiple gears meets the needs of different scenarios; smooth gear switching can also reduce instantaneous current changes and reduce mutual interference between circuits, thereby improving the overall electromagnetic compatibility, improving the stability of the entire circuit and the pass rate of EMC testing.

[0044] In an optional embodiment of the present invention, the power difference between each adjacent gear position among the powers of the plurality of gear positions is equal.

[0045] Among them, adjacent gears refer to gears in the heating element with similar powers. For example, the powers of the heating element's multiple gears are 400W, 800W and 1200W, three gears. At this time, the gears of 400W and 800W, 800W and 1200W are adjacent gears. The power difference of adjacent gears refers to a group of gears, and 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 invention, 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 helps the user to make more precise temperature adjustments as needed to adapt to different environments and application requirements; the design of equal power difference also helps to maintain the stability of the circuit in each gear, thereby reducing the problem of mutual interference between circuits caused by excessive power adjustment fluctuations.

[0047] In an embodiment of the present invention, a circuit of a high-power heating element that passes an EMC test is provided, and the circuit of the heating element comprises:

[0048] An alternating current power supply, the alternating current power supply being used to provide alternating current;

[0049] A zero-crossing detection circuit, the zero-crossing detection circuit is used to obtain a zero-crossing signal of the AC power supply and output the zero-crossing signal to a main control circuit;

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

[0051] A bidirectional thyristor drive circuit, the bidirectional thyristor drive circuit is used to control the load circuit according to the control signal;

[0052] A load circuit, wherein the load circuit is used to control the heating element, wherein the heating element includes at least two heating modules connected in parallel, and each of the heating modules corresponds to one bidirectional thyristor drive circuit.

[0053] Among them, the bidirectional thyristor driving circuit controls the on and off of each heating module at different times respectively, thereby preferentially ensuring that the power cycle of the heating element is minimized. The bidirectional thyristor driving circuit controls the on and off of each heating module at different times respectively, thereby ensuring that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized.

[0054] The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and preferentially ensures that the power cycle of the heating element is minimized. Since the smaller the cycle of the heating element is, the shorter the interference time of the heating element on the circuit is, the smaller the interference of the heating element on the circuit is. Setting the power cycle of the heating element to the minimum can increase the possibility of the circuit passing the EMC test, and improve the success rate of the circuit passing the EMC test. The embodiment of the present invention controls the on and off of each heating module at different times through a bidirectional thyristor drive circuit, and ensures that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized. Since the larger the maximum value of the power difference of the heating element is, the larger the variation of the power of the heating element is, the greater the interference of the heating element on the circuit is, and the power difference of the heating element is minimized. Setting the maximum value to the minimum can reduce the interference of the heating element on the circuit, thereby improving the success rate of the circuit passing the EMC test; the embodiment of the present invention only needs to connect multiple heating modules in parallel, set a corresponding number of thyristor drive circuits and a zero-crossing detection circuit to achieve low-cost passing of the EMC test. Since a connection method of multiple heating modules in parallel is used, this method can greatly improve the total power of the circuit passing the EMC test. Multiple heating modules connected in parallel can distribute the total power of the heating element to each heating module. The smaller the power of a single heating module, the less interference the heating element has on the circuit, thereby improving the success rate of the circuit passing the EMC test; the embodiment of the present invention can also control the heating power of each heating module to thereby affect the power of the heating element, thereby achieving multi-gear adjustment of the heating element, and each gear can pass the EMC test.

[0055] In an optional embodiment of the present invention, the load circuit outputs different power gears by controlling the on or off time of the heating module in the heating element.

[0056] Among them, the power of the heating module is the power of the cycle time of a heating module. At this time, the gear adjustment can achieve a smaller power of the heating module by dividing the conduction time of a cycle. For example, when the power of the heating module is 1000w, the cycle of the alternating current is T, when the cycle of the heating module is T, the heating power of the heating module when it is turned on for the entire T time is 1000w, and when it is turned on for 1 / 2T, the heating power of the heating module is 500w; at this time, different power gears can be output by controlling the conduction or disconnection time of the heating module.

[0057] In the embodiment of the present invention, by controlling the on or off time of the heating module in the heating element to output different power gears, the user experience can be improved and the requirements of different scenarios can be met.

[0058] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0059] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control method for a high-power heating element, characterized in that: The control method of the heating element comprises: S10, obtaining a zero-crossing signal of the AC power supply through a zero-crossing detection circuit; S20, outputting the zero-crossing signal to a main control circuit; S30, the main control circuit outputs a control signal to the bidirectional thyristor drive circuit according to the zero-crossing signal; S40, the bidirectional thyristor drive circuit controls the load circuit according to the control signal, and the load circuit is used to control the heating element to be turned on or off; wherein the heating element includes at least two heating modules connected in parallel, each heating module corresponds to one bidirectional thyristor drive circuit, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby preferentially ensuring that the power cycle of the heating element is minimized, and the bidirectional thyristor drive circuit controls the on and off of each heating module at different times respectively, thereby ensuring that the maximum value of the power difference of the heating element in the T / 2 time period adjacent to each zero crossing point is minimized.

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

3. The control method of the high-power heating element according to claim 2, characterized in that: The control method of the heating element further includes: The heating element outputs power of multiple gears according to the requirements of the load circuit.

4. The control method of the high-power heating element according to claim 3, characterized in that: The power difference between each adjacent gear position among the powers of the plurality of gear positions is equal.

5. A circuit of a high-power heating element, characterized in that: The circuit of the heating element comprises: An alternating current power supply, the alternating current power supply being used to provide alternating current; A zero-crossing detection circuit, the zero-crossing detection circuit is used to obtain a zero-crossing signal of the AC power supply and output the zero-crossing signal to a main control circuit; A main control circuit, used for outputting a control signal to a bidirectional thyristor drive circuit according to the zero-crossing signal; A bidirectional thyristor drive circuit, the bidirectional thyristor drive circuit is used to control the load circuit according to the control signal; A load circuit is used to control the heating element to be turned on or off, wherein the heating element includes at least two heating modules connected in parallel, and each of the heating modules corresponds to one bidirectional thyristor drive circuit.

6. The circuit of the high-power heating element according to claim 5, characterized in that: The load circuit outputs different power gears by controlling the on or off time of the heating module in the heating element.

Images