Magnetron drive circuit and heating device

Abstract

This application provides a magnetron driving circuit and a heating device, the magnetron driving circuit including: a rectifier circuit having a first output terminal connected to the anode of the magnetron and a second output terminal connected to the ground terminal of the magnetron, converting AC to DC to power the magnetron; a transformer having a primary coil connected to an AC power supply terminal or an inverter circuit, a first end of a first secondary coil connected to the cathode of the magnetron, a second end of the first secondary coil connected to the anode of the magnetron, and a second secondary coil connected to the rectifier circuit, supplying AC to the rectifier circuit; and a variable resistance component located in a loop between the first secondary coil, the anode of the magnetron, and the cathode of the magnetron, for limiting the current flowing through the magnetron, wherein the resistance of the component is positively correlated to the temperature of the component.

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on February 22, 2023, bearing application number "202310146977.3" and entitled "Magnetron driving circuit and heating device," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of drive control, and more particularly to a magnetron drive circuit and a heating device. [Background technology]

[0003] In the related technical solution, when the magnetron is working, it is equivalent to a diode placed in a constant magnetic field, and the electrons in the cathode of the magnetron interact between the perpendicular constant magnetic field and the electric field, converting the electric energy into electromagnetic energy to heat the food. The cathode of the magnetron is usually called the heart of the magnetron, and its operating temperature determines the operating stability and lifespan of the magnetron.

[0004] Here, after the magnetron is excited, the filament voltage is always maintained at about 3.3 V or decreases as the output power decreases. If the filament is constantly energized, it will cause an excessive temperature rise, which will cause the filament to overheat, resulting in severe evaporation of the material, degrading the quality of the filament and shortening its service life. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application aims to solve at least one of the technical problems existing in the prior art or related art.

[0006] Accordingly, a first aspect of the present application provides a drive circuit for a magnetron.

[0007] A second aspect of the present application provides a heating device. [Means for solving the problem]

[0008] In view of the above, a first aspect of the present application provides a magnetron drive circuit including: a rectifier circuit having a first output terminal connected to an anode of a magnetron and a second output terminal connected to a ground terminal of the magnetron, and used to convert AC to DC and supply power to the magnetron; a transformer having a primary coil connected to an AC power supply terminal or an inverter circuit, a first end of a first secondary coil connected to a cathode of the magnetron, a second end of the first secondary coil connected to the anode of the magnetron, and a second secondary coil connected to the rectifier circuit, and used to supply AC to the rectifier circuit; and a variable resistance component located in a loop among the first secondary coil, the anode of the magnetron, and the cathode of the magnetron, and used to limit the current flowing through the magnetron, wherein the resistance of the component and the temperature of the component show a positive correlation.

[0009] The technical solution of this application proposes a driving circuit for a magnetron, which includes a transformer, a rectifier circuit, and components connected to the magnetron.

[0010] Here, the component is connected in series between the magnetron filament and the first secondary coil, and when the magnetron is operating, the component generates heat due to its own current blocking effect or is affected by the temperature of the environment where the magnetron's driving current exists, causing the component's resistance to increase. When the component's resistance increases, the resistance connected in series between the magnetron filament and the first secondary coil also increases, resulting in a decrease in the current in the loop. When the current in the loop decreases, the amount of heat generated by the filament between the anode and cathode in the magnetron decreases, slowing down the evaporation rate of the filament and thereby extending the service life of the magnetron.

[0011] In the above technical solution, the current flowing through the filament is reduced, but since the current flowing through the filament is relatively large at the beginning of the magnetron startup, the temperature of the filament rises to a relatively high temperature, and when the filament is at a relatively high temperature, the secondary back bombardment characteristics of the electrons are utilized to keep the filament emitting electrons at a high temperature, thereby enabling the magnetron to operate. That is, the above technical solution of the present application can extend the service life of the magnetron while ensuring the normal operation of the magnetron.

[0012] Here, a rectifier circuit is provided to convert AC to DC, and a stable high voltage is applied to the anode of the magnetron, facilitating the magnetron to generate an electric field. Meanwhile, the first and second ends of the first secondary coil are connected to the anode and cathode of the magnetron, respectively, so that a voltage of approximately 3.3 volts is supplied to the filament between the anode and cathode of the magnetron. After the filament is energized and heated, it continuously emits electrons, which interact with the vertical constant magnetic field and the electric field to convert electric energy into electromagnetic energy.

[0013] In the above technical solutions, the resistance value of the component and the temperature of the component have a positive correlation, and it can be seen that as the temperature of the component increases, the resistance value of the component increases.

[0014] In addition, the magnetron driving circuit proposed in this application also has the following additional technical features.

[0015] In some technical solutions, optionally, the component includes a thermal relay and / or at least one thermistor.

[0016] In this technical solution, the form of the component is specifically limited. Here, the component may be a thermal relay. Specifically, a thermal relay is a protective electrical device for overload protection of motors and other electrical devices and circuits. Heat is generated by a current flowing through the thermal element, causing a bimetal with a different expansion coefficient to deform. When the deformation reaches a certain distance, the connecting rod is pushed, the control circuit is disconnected, the contactor loses power, and the main circuit is disconnected. Specifically, in this technical solution, when a large current flows through the thermal relay, the thermal relay is disconnected, and the series connection between the magnetron filament and the first secondary coil is turned off. At this time, the magnetron filament continues to emit electrons using the secondary backbombardment characteristics of electrons. When the temperature of the thermal relay's thermal element decreases, the deformation of the bimetal with a different expansion coefficient decreases, pushing the connecting rod and turning on the control circuit, i.e., turning on the series connection between the magnetron filament and the first secondary coil.

[0017] When the component is at least one thermistor, the thermistor's characteristic of increasing its resistance as the temperature rises is utilized to reduce the current flowing through the magnetron filament, thereby reducing the amount of heat generated by the filament between the magnetron's anode and cathode, and further slowing down the evaporation rate of the filament, thereby extending the service life of the magnetron.

[0018] In some technical solutions, optionally, the number of thermistors included in the at least one thermistor may be determined according to actual application scenarios, which will not be described in detail here.

[0019] In some technical solutions, both a thermal relay and at least one thermistor are optionally provided, so that the thermistor limits the current flowing through the magnetron filament and the thermal relay cuts off the loop in which the filament is present, thereby preventing the magnetron from operating in a high-temperature environment and extending the service life of the magnetron.

[0020] In some technical solutions, optionally, when the component includes a thermal relay and at least one thermistor, the thermal relay and the at least one thermistor are connected in series.

[0021] In this technical solution, when the component includes the above-mentioned thermal relay and at least one thermistor, the connection relationship between the thermal relay and the at least one thermistor is specifically defined.

[0022] By limiting the thermal relay and at least one thermistor to be connected in series, the current flowing through the magnetron filament is limited by the thermistor and the loop in which the filament exists is cut off by the thermal relay, thereby preventing the magnetron from operating in a high-temperature environment and extending the service life of the magnetron.

[0023] In some technical solutions, optionally, the thermal relay and the at least one thermistor are located at different positions in the loop between the first secondary coil and the magnetron.

[0024] In some technical solutions, optionally, the component is located between a first end of the first secondary coil and the cathode of the magnetron and / or between a second end of the first secondary coil and the anode of the magnetron.

[0025] In this technical solution, the location of the components is specifically limited, and may be near the cathode of the magnetron or near the anode of the magnetron according to the actual use.

[0026] In some technical solutions, the component optionally includes a terminal block and / or a socket hole used in conjunction with the magnetron.

[0027] In this technical solution, the component is a terminal block or a socket used in conjunction with the magnetron, which allows the component to be located close to the magnetron, and furthermore, when the magnetron is operating and its temperature rises, the temperature of the component is also affected by the change in the temperature of the magnetron, thereby limiting the current flowing through the magnetron filament even when the temperature of the magnetron is relatively high.

[0028] In the above technical solution, when the temperature of the magnetron is relatively high, the current flowing through the filament of the magnetron is limited, which reduces the possibility of the magnetron being damaged by too high a temperature, thereby extending the service life of the magnetron.

[0029] In some technical solutions, optionally, the component is at least a part of a first secondary coil.

[0030] In this technical solution, when the magnetron is operating, the transformer also operates and generates heat, and the temperature of the transformer also gradually increases as the operating time goes by. Based on this, the temperature of the transformer can also represent the temperature of the magnetron. Since the components and the first secondary coil are integrated, for example, the components are part or the whole of the first secondary coil, when the temperature of the transformer increases, the temperature of the components also increases synchronously. Furthermore, the increased resistance limits the current flowing through the magnetron filament, reducing the possibility of the magnetron being damaged by excessive temperature, thereby extending the service life of the magnetron.

[0031] In some technical solutions, optionally, when the component is at least a part of the first secondary coil, it can be understood that at least a part of the first secondary coil is made of a thermistor material.

[0032] In some technical solutions, the components are optionally leads.

[0033] In this technical solution, another form of component is provided, and the above-mentioned leads can be understood as conductive lines connecting the first secondary coil, the anode of the magnetron, and the cathode of the magnetron.

[0034] Here, the conductive lines are made of a thermistor material.

[0035] In some technical solutions, the components are optionally located in the housing of the magnetron.

[0036] In this technical solution, the component is mounted on the magnetron housing, which allows the conduction of the magnetron temperature to the component, and the temperatures of the magnetron and the component tend to be the same. Since the temperature of the magnetron and the temperature of the magnetron filament tend to be the same, the temperature of the magnetron filament is directly represented by the temperature of the component, which can change its own resistance to reduce the current flowing through the magnetron filament, reduce the possibility of the magnetron being damaged by excessively high temperatures, and extend the service life of the magnetron.

[0037] In some technical solutions, optionally, the rectifier circuit includes: a first capacitor having a first end connected to the anode of the magnetron and a second end connected to the first end of the second secondary coil; a first diode having an anode connected to the first end of the first capacitor and a cathode connected to the second end of the second secondary coil; a second capacitor having a first end connected to the second end of the first capacitor and a second end connected to the ground terminal of the magnetron; and a second diode having an anode connected to the cathode of the first diode and a cathode connected to the second end of the second capacitor.

[0038] In this technical solution, the topology structure of the rectifier circuit is specifically defined, and in this topology structure, the rectifier circuit includes a voltage doubler circuit, where the voltage doubler circuit not only realizes voltage increase but also realizes the role of converting AC to DC to supply power to the magnetron.

[0039] Here, the voltage doubler circuit is a circuit in which the above-mentioned first capacitor, first diode, second capacitor, and second diode are connected.

[0040] In some technical solutions, optionally, when the primary coil of the transformer is connected to the inverter circuit, the inverter circuit includes a third capacitor having a first end connected to the first DC bus and the first end of the primary coil and a second end connected to the second DC bus and the second end of the primary coil, and a switching tube located on the first DC bus or the second DC bus.

[0041] In this technical solution, the inverter circuit is limited to including a third capacitor and a switching tube, so that when the switching tube is turned on or off, the DC power supply at the first DC bus and the second DC bus is converted into AC power supply, and the voltage is converted by the primary coil of the transformer, thereby obtaining the voltage for power supply to the magnetron.

[0042] In the above technical solution, by providing an inverter circuit, the driving circuit of the magnetron can be applied to a DC power supply scenario, and can further meet the needs of various scenarios.

[0043] In some technical solutions, optionally the switching tube is a power tube.

[0044] In some technical solutions, optionally, the power supply may further include a rectifier bridge, the first input terminal of which is used to connect with the first AC power supply terminal, the second input terminal of which is used to connect with the second AC power supply terminal, the first output terminal of which is connected to the first DC bus, and the second output terminal of which is connected to the second DC bus.

[0045] In this technical solution, a rectifier bridge is provided to convert AC into DC, which further enables the magnetron driving circuit to be adapted to various AC power supply scenarios, and reduces the power supply requirements of the magnetron driving circuit.

[0046] In some technical solutions, optionally, the first DC bus and the second DC bus can be understood as the positive pole and the negative pole of the power supply.

[0047] In some technical solutions, optionally, the number of turns of the second secondary coil is equal to or greater than the number of turns of the primary coil.

[0048] In this technical solution, by limiting the number of turns of the second secondary coil to at least be greater than the number of turns of the primary coil, the AC voltage output by the first and second ends of the second secondary coil is higher than the AC voltage input by the primary coil. In this process, the AC output by the high voltage transformer is improved, a relatively high voltage is supplied to the rectifier circuit, and a high voltage can be supplied to the magnetron anode without providing a voltage doubler circuit in the rectifier circuit.

[0049] In some technical solutions, optionally, when the rectifier circuit does not include a voltage doubler circuit, the rectifier circuit includes a rectifier bridge to convert AC into DC.

[0050] A second aspect of the present application provides a heating device including a magnetron and any of the magnetron drive circuits described above.

[0051] In some technical solutions, optionally, the heating device includes a cooking device.

[0052] In some technical solutions, the cooking device optionally includes a microwave oven or a micro-steam oven combination.

[0053] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application.

[0054] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following detailed description of the embodiments with reference to the drawings. [Brief explanation of the drawings]

[0055] [Figure 1] FIG. 2 is a schematic diagram showing an example topology of a magnetron drive circuit in an embodiment of the present application. [Figure 2] 10 shows a schematic diagram of another topology of a magnetron drive circuit in an embodiment of the present application. [Figure 3] 1 shows a schematic diagram of a control flow in an embodiment of the present application. [Figure 4] 4 shows the correspondence between the resistance value and the temperature value of the component in the embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0056] In order to more clearly understand the above aspects, features and advantages of the present application, the present application will be described in more detail below with reference to the drawings and specific embodiments. Note that the examples and features in the examples of the present application may be combined with each other unless they are inconsistent.

[0057] In the following description, many specific details are set forth to facilitate a thorough understanding of the present application; however, the present application may be implemented in other ways than those described herein, and the scope of protection of the present application is not limited by the specific examples disclosed below.

[0058] In one embodiment, as shown in FIGS. 1 and 2 , a magnetron driving circuit is proposed, which includes: a rectifier circuit 102, the first output terminal of which is connected to the anode of the magnetron and the second output terminal of which is connected to the ground terminal of the magnetron, for converting AC into DC to power the magnetron; a transformer T, the primary coil of which is connected to an AC power supply terminal or an inverter circuit, the first end of the first secondary coil of which is connected to the cathode of the magnetron, the second end of the first secondary coil of which is connected to the anode of the magnetron, and the second secondary coil of which is connected to the rectifier circuit 102, for supplying AC to the rectifier circuit 102; and a variable resistance component 104, which is located in a loop between the first secondary coil, the anode of the magnetron, and the cathode of the magnetron, for limiting the current flowing through the magnetron, and the resistance of the component 104 is positively correlated to the temperature of the component 104.

[0059] The embodiment of the present application proposes a driving circuit for the magnetron, which includes a transformer T, a rectifier circuit 102, and a component 104 connected to the magnetron.

[0060] Here, the component 104 is connected in series between the magnetron filament and the first secondary coil. When the magnetron is operating, the component 104 generates heat due to its own current blocking effect, or is heated by the temperature of the environment where the magnetron driving current exists, causing the resistance of the component 104 to increase. When the resistance of the component 104 increases, the resistance connected in series between the magnetron filament and the first secondary coil also increases, resulting in a decrease in the current in the loop. When the current in the loop decreases, the heat generation of the filament between the anode and cathode of the magnetron decreases, slowing down the evaporation rate of the filament and thereby extending the service life of the magnetron.

[0061] In the above embodiment, the current flowing through the filament is reduced, but since the current flowing through the filament is relatively large at the beginning of the magnetron startup, the temperature of the filament rises to a relatively high temperature, and when the filament is at a relatively high temperature, the secondary back bombardment characteristics of the electrons are utilized to keep the filament emitting electrons at a high temperature, thereby enabling the magnetron to operate. That is, the above embodiment of the present application can ensure the normal operation of the magnetron and extend the service life of the magnetron.

[0062] The rectifier circuit 102 converts AC into DC, applying a stable high voltage to the anode of the magnetron and facilitating the magnetron to generate an electric field; meanwhile, the first and second ends of the first secondary coil are connected to the anode and cathode of the magnetron, respectively, so that a voltage of about 3.3 volts is supplied to the filament between the anode and cathode of the magnetron. After the filament is energized and heated, it continuously emits electrons, which interact with the vertical constant magnetic field and the electric field to convert electric energy into electromagnetic energy.

[0063] In some embodiments, the resistance of component 104 optionally correlates positively with the temperature of component 104. It can be seen that as the temperature of component 104 increases, the resistance of component 104 increases.

[0064] In the above example, the component 104 includes a thermal relay and / or at least one thermistor.

[0065] In this embodiment, the form of the component 104 is specifically limited. Here, the component 104 may be a thermal relay. Specifically, a thermal relay is a protective electrical device for overload protection of motors and other electrical devices and circuits. Heat is generated by the current flowing through the thermal element, causing bimetals with different expansion coefficients to deform. When the deformation reaches a certain distance, the connecting rod is pushed, disconnecting the control circuit, causing the contactor to lose power, and disconnecting the main circuit.

[0066] Specifically, in the embodiment of the present application, when the current flowing through the thermal relay is large, the thermal relay is disconnected and the series connection between the magnetron filament and the first secondary coil is turned off. At this time, the magnetron filament continues to emit electrons using the characteristics of secondary back bombardment of electrons. When the temperature of the thermal element of the thermal relay decreases, the deformation of the bimetal with different expansion coefficients is reduced, the connecting rod is pressed, and the control circuit is turned on, that is, the series connection between the magnetron filament and the first secondary coil is turned on.

[0067] When the component 104 is at least one thermistor, the thermistor's characteristic of increasing its resistance as the temperature increases is utilized to reduce the current flowing through the magnetron filament, thereby reducing the amount of heat generated by the filament between the magnetron's anode and cathode, and further slowing down the evaporation rate of the filament, thereby extending the service life of the magnetron.

[0068] In some embodiments, optionally, the number of thermistors included in the at least one thermistor may be determined according to the actual application scenario, which will not be described in detail here.

[0069] In some embodiments, optionally, both a thermal relay and at least one thermistor are provided, whereby the thermistor limits the current flowing through the magnetron filament and the thermal relay cuts off the loop in which the filament is located, thereby preventing the magnetron from operating in a high temperature environment and extending the useful life of the magnetron.

[0070] Optionally, in some embodiments, when component 104 includes a thermal relay and at least one thermistor, the thermal relay and the at least one thermistor are connected in series.

[0071] In this embodiment, when the component 104 includes the above-described thermal relay and at least one thermistor, the connection relationship between the thermal relay and the at least one thermistor is specifically defined.

[0072] By limiting the thermal relay and at least one thermistor to be connected in series, the current flowing through the magnetron filament is limited by the thermistor and the loop in which the filament exists is cut off by the thermal relay, thereby preventing the magnetron from operating in a high-temperature environment and extending the service life of the magnetron.

[0073] In some embodiments, optionally, the thermal relay and the at least one thermistor are at different positions in the loop between the first secondary coil and the magnetron.

[0074] In some embodiments, the component 104 is optionally located between a first end of the first secondary coil and the cathode of the magnetron and / or between a second end of the first secondary coil and the anode of the magnetron.

[0075] In this embodiment, the location of the component 104 is specifically limited, and may be near the cathode of the magnetron or near the anode of the magnetron depending on the actual use.

[0076] In some embodiments, component 104 optionally includes a terminal block and / or a receptacle for use in conjunction with a magnetron.

[0077] In this embodiment, component 104 is a terminal block or socket used in conjunction with a magnetron, allowing component 104 to be located close to the magnetron, and further, when the magnetron is operating and its temperature rises, the temperature of component 104 is also affected by changes in the temperature of the magnetron, thereby limiting the current flowing through the magnetron filament even when the magnetron temperature is relatively high.

[0078] In the above embodiment, when the temperature of the magnetron is relatively high, the current flowing through the filament of the magnetron is limited, which reduces the possibility that the magnetron will be damaged due to excessive temperature, thereby extending the service life of the magnetron.

[0079] Optionally, in some embodiments, component 104 is at least a portion of a first secondary coil.

[0080] In this embodiment, when the magnetron is operating, the transformer T also operates and generates heat, and the temperature of the transformer T also gradually increases as the operating time passes. Based on this, the temperature of the transformer T can also represent the temperature of the magnetron. Since the component 104 and the first secondary coil are integrated, for example, the component 104 is part or the entire first secondary coil, when the temperature of the transformer T increases, the temperature of the component 104 also increases synchronously. Furthermore, the increased resistance limits the current flowing through the magnetron filament, reducing the possibility of the magnetron being damaged by excessive temperature, thereby extending the service life of the magnetron.

[0081] In some embodiments, optionally, component 104 is at least a portion of a first secondary coil, which may be understood to mean that at least a portion of the first secondary coil is made of a thermistor material.

[0082] Optionally, in some embodiments, component 104 is a lead.

[0083] In this embodiment, an alternative form of component 104 is provided, where the leads can be understood as conductive lines connecting the first secondary coil, the anode of the magnetron, and the cathode of the magnetron.

[0084] Here, the conductive lines are made of a thermistor material.

[0085] In some embodiments, the component 104 is optionally located in the housing of the magnetron.

[0086] In this embodiment, by providing part 104 in the magnetron housing, the temperature of the magnetron can be conducted to part 104, and further, the temperatures of the magnetron and part 104 tend to be similar. Since the temperature of the magnetron and the temperature of the magnetron filament tend to be similar, the temperature of the magnetron filament can be directly represented by the temperature of part 104, thereby changing its own resistance value to reduce the current flowing through the magnetron filament, reducing the possibility of the magnetron being damaged by excessively high temperatures and extending the useful life of the magnetron.

[0087] In some embodiments, the rectifier circuit 102 optionally includes a first capacitor C1 having a first terminal connected to the anode of the magnetron and a second terminal connected to the first terminal of the second secondary coil, a first diode D1 having an anode connected to the first terminal of the first capacitor C1 and a cathode connected to the second terminal of the second secondary coil, a second capacitor C2 having a first terminal connected to the second terminal of the first capacitor C1 and a second terminal connected to the ground terminal of the magnetron, and a second diode D2 having an anode connected to the cathode of the first diode D1 and a cathode connected to the second terminal of the second capacitor C2.

[0088] In this embodiment, the topology structure of the rectifier circuit 102 is specifically limited, and in this topology structure, the rectifier circuit 102 includes a voltage doubler circuit, where the voltage doubler circuit not only realizes voltage increase but also realizes the role of converting AC into DC to power the magnetron.

[0089] Here, the voltage doubler circuit is a circuit formed by the first capacitor C1, the first diode D1, the second capacitor C2, and the second diode D2 and their connections.

[0090] In some embodiments, optionally, when the primary coil of the transformer T is connected to the inverter circuit, the inverter circuit includes a third capacitor C3 having a first end connected to the first DC bus and the first end of the primary coil and a second end connected to the second DC bus and the second end of the primary coil, and a switching tube Q located on the first DC bus or the second DC bus.

[0091] In this embodiment, the inverter circuit is limited to include the third capacitor C3 and the switching tube Q. When the switching tube Q is turned on or off, the DC power supply at the first DC bus and the second DC bus is converted into AC power supply, and the voltage is converted by the primary coil of the transformer T, thereby obtaining the voltage supply to the magnetron.

[0092] In the above embodiment, by providing an inverter circuit, the magnetron driving circuit can be applied to a DC power supply scenario, and can further meet the needs of various scenarios.

[0093] In some embodiments, the switching tube Q is optionally a power tube.

[0094] In some embodiments, the power supply circuit may optionally further include a rectifier bridge BD having a first input terminal adapted to be connected to the first AC power supply terminal, a second input terminal adapted to be connected to the second AC power supply terminal, a first output terminal adapted to be connected to the first DC bus, and a second output terminal adapted to be connected to the second DC bus.

[0095] In this embodiment, a rectifier bridge BD is provided to convert AC into DC using the rectifier bridge BD, which further enables the magnetron driving circuit to be adapted to various AC power supply scenarios and reduces the power supply requirements of the magnetron driving circuit.

[0096] In some embodiments, the first DC bus and the second DC bus may alternatively be understood as the positive and negative poles of a power supply.

[0097] In some embodiments, optionally, the number of turns in the second secondary coil is equal to or greater than the number of turns in the primary coil.

[0098] In this embodiment, by limiting the number of turns of the second secondary coil to at least be greater than the number of turns of the primary coil, the voltage of the AC output by the first and second ends of the second secondary coil is higher than the voltage of the AC input by the primary coil. In this process, the AC output by the high voltage transformer T is improved, a relatively high voltage is supplied to the rectifier circuit 102, and a high voltage can be supplied to the anode of the magnetron without providing a voltage doubler circuit in the rectifier circuit 102.

[0099] In some embodiments, optionally, if the rectifier circuit 102 does not include a voltage doubler circuit, the rectifier circuit 102 includes a rectifier bridge to convert AC to DC.

[0100] In one embodiment, there is provided a heating device including a magnetron and a magnetron drive circuit as described above.

[0101] In this embodiment, the heating device includes a drive circuit for the magnetron, which includes a transformer T, a rectifier circuit 102, and a component 104 connected to the magnetron.

[0102] Here, the component 104 is connected in series between the magnetron filament and the first secondary coil, and when the magnetron is operating, the component 104 generates heat due to its own current blocking effect, or is heated by the temperature of the environment in which the magnetron driving current exists, causing the resistance of the component 104 to increase. When the resistance of the component 104 increases, the resistance connected in series between the magnetron filament and the first secondary coil also increases, resulting in a decrease in the current in the loop. When the current in the loop decreases, the heat generation of the filament between the anode and cathode of the magnetron decreases, slowing down the evaporation rate of the filament, thereby extending the service life of the magnetron.

[0103] In some embodiments, the heating device may optionally be an incubator, a furnace, or the like.

[0104] In some embodiments, the heating device optionally includes a plurality of magnetrons, wherein the anodes of the plurality of magnetrons are connected and the cathodes of the plurality of magnetrons are connected.

[0105] In some embodiments, the heating device optionally includes a cooking device.

[0106] In some embodiments, the cooking appliance optionally includes a microwave oven or a micro-steam oven combination.

[0107] In this embodiment, as shown in Figure 3, several thermistors are connected in series in the secondary loop of the transformer supplying power to the magnetron filament, thereby achieving feedback regulation of the filament loop current. When the microwave oven is first turned on, there is a preheating stage so that the magnetron filament can emit electrons once its temperature reaches a predetermined value. During this stage, voltage exists across both the magnetron filament and the magnetron anode, but no current flows through the magnetron anode loop. After preheating is complete, the magnetron begins to operate, and the ambient temperature rises rapidly. As the thermistor resistance increases, the current in the filament power loop rapidly decreases. The magnetron's backbombardment characteristics are utilized to ensure that the filament continues to generate electrons, maintaining normal magnetron operation.

[0108] Furthermore, self-feedback regulation of filament temperature is also possible. If operation is manually stopped or the filament temperature is too low to emit electrons, the magnetron stops operating, the ambient temperature drops rapidly, and the thermistor resistance drops sharply. When the magnetron is then started again, the filament current increases rapidly, energizing the magnetron filament and heating it. Once the filament heats up to a certain temperature, it emits electrons, allowing the magnetron to continue operating. As the ambient temperature rises rapidly, the thermistor resistance also increases accordingly. The filament loop current decreases to nearly 0 amperes, and the cathode filament power loop is disconnected, equivalent to stopping the power supply and heating of the filament. This results in self-feedback regulation of filament heating.

[0109] As shown in Figure 4, the thermistor change curve shows that the resistance is close to 0 at room temperature (35°C) and approaches infinity as the temperature rises, and the current in the filament power loop becomes extremely small. This corresponds to a disconnection, which can prevent the magnetron filament from overheating during continuous power supply and the volatilization of the filament material, which will affect the magnetron's service life, and also improve the magnetron's efficiency.

[0110] The terms "first" and "second" features in the specification and claims of this application may explicitly or implicitly include one or more of those features. In this description, unless otherwise specified, "plurality" means two or more. Also, in the specification and claims, "and / or" refers to at least one of the items before and after it, and the symbol " / " generally indicates an "or" relationship between the related items before and after it.

[0111] In the description of the present application, the orientations or positional relationships indicated by terms such as “center,” “longitudinal direction,” “lateral direction,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial direction,” “radial direction,” and “circumferential direction” are based on the orientations or positional relationships shown in the drawings, and are intended merely to facilitate and simplify the description of the embodiments of the present application, and do not indicate or imply that the structures, devices, or elements shown must have a specific orientation or be configured or operate in a specific orientation, and therefore, it can be understood that these descriptions cannot be construed as limiting the present application.

[0112] In the description of this application, unless otherwise clearly specified or limited, the terms "attach," "couple," and "connect" should be understood in a broad sense, and may mean, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical structural connection, an electrical connection, a direct connection between the two, an indirect connection between the two via an intermediate medium, or internal communication between the two elements. The specific meanings of the above terms in this application can be specifically understood by those skilled in the art.

[0113] In the claims, specification, and drawings of this application, the term "plurality" means two or more unless expressly limited otherwise. The orientations or positional relationships indicated by terms such as "upper," "lower," etc., are based on the orientations or positional relationships shown in the drawings and are intended merely to facilitate and simplify the description of this application. They do not indicate or imply that the devices or elements shown must have a specific orientation, be configured, or operate in a specific orientation. Therefore, it is understood that these descriptions should not be construed as limiting this application. The terms "connect," "attach," "fixed," etc., should be understood broadly. For example, "connect" may refer to multiple objects being fixedly connected, detachably connected, or integrally connected, or multiple objects being directly connected, or multiple objects being indirectly connected via an intermediate medium. The specific meanings of the above data in this application are readily apparent to those skilled in the art.

[0114] In the claims, specification, and drawings of this application, the terms "one embodiment," "some embodiments," "specific embodiment," etc., mean that a specific feature, structure, material, or characteristic described with reference to that embodiment or example is included in at least one embodiment or example of this application. In the claims, specification, and drawings of this application, general references to such terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0115] The above is only a preferred embodiment of the present application, and does not limit the present application. Those skilled in the art can make various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principles of the present application shall fall within the scope of protection of the present application.

[0116] The correspondence between the reference numerals and the names of the components in FIGS. 1 and 2 is as follows: [Explanation of symbols]

[0117] 102 Rectifier circuit T transformer 104 parts C1 First capacitor C2 Second capacitor C3 Third capacitor D1 First diode D2 Second diode Q Switching Tube BD rectifier bridge

Claims

1. A magnetron drive circuit, comprising: a rectifier circuit, the first output terminal of which is connected to the anode of the magnetron and the second output terminal of which is connected to the ground terminal of the magnetron, for converting AC into DC to supply power to the magnetron; a transformer having a primary coil connected to an AC power supply terminal or an inverter circuit, a first end of a first secondary coil connected to a cathode of the magnetron, a second end of the first secondary coil connected to an anode of the magnetron, and a second secondary coil connected to the rectifier circuit, the transformer being used to supply the AC to the rectifier circuit; a variable resistance component located in a loop between the first secondary coil, the magnetron anode, and the magnetron cathode, the variable resistance component being used to limit the current flowing through the magnetron; The resistance value of the component and the temperature of the component show a positive correlation. Magnetron drive circuit.

2. The component includes a thermal relay and / or at least one thermistor.

2. The magnetron drive circuit according to claim 1.

3. the component includes a thermal relay and at least one thermistor, the thermal relay and the at least one thermistor being connected in series; 3. The magnetron drive circuit according to claim 2.

4. the component is located between a first end of the first secondary coil and a cathode of the magnetron and / or between a second end of the first secondary coil and an anode of the magnetron; 2. The magnetron drive circuit according to claim 1.

5. The components include a terminal block and / or a socket for use in conjunction with the magnetron.

2. The magnetron drive circuit according to claim 1.

6. the component is at least a portion of the first secondary coil; 2. The magnetron drive circuit according to claim 1.

7. the component is a lead; 2. The magnetron drive circuit according to claim 1.

8. The component is located in the housing of the magnetron. The magnetron drive circuit according to any one of claims 2 to 4.

9. The rectifier circuit includes: a first capacitor having a first end connected to the anode of the magnetron and a second end connected to the first end of the second secondary coil; a first diode having an anode connected to the first end of the first capacitor and a cathode connected to the second end of the second secondary coil; a second capacitor having a first end connected to the second end of the first capacitor and a second end connected to the ground end of the magnetron; a second diode having an anode connected to the cathode of the first diode and a cathode connected to the second end of the second capacitor; A magnetron drive circuit according to any one of claims 1 to 7.

10. A primary coil of the transformer is connected to the inverter circuit, and the inverter circuit comprises: a third capacitor having a first end connected to the first DC bus and the first end of the primary coil and a second end connected to the second DC bus and the second end of the primary coil; a switching tube located at the first DC bus or the second DC bus; A magnetron drive circuit according to any one of claims 1 to 7.

11. a rectifier bridge having a first input terminal adapted to connect to a first AC power supply terminal, a second input terminal adapted to connect to a second AC power supply terminal, a first output terminal adapted to connect to the first DC bus, and a second output terminal adapted to connect to the second DC bus; 11. The magnetron driving circuit according to claim 10.

12. The number of turns of the second secondary coil is equal to or greater than the number of turns of the primary coil. A magnetron drive circuit according to any one of claims 1 to 7.

13. A heating device, comprising: A magnetron and and a magnetron drive circuit according to any one of claims 1 to 7. heating device.

14. Including cooking equipment, The heating device according to claim 13.

15. The cooking device includes a microwave oven or a micro steam oven.

15. The heating device of claim 14.

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