Driving power supply and microwave cooking device

Abstract

The application discloses a driving power supply and a microwave cooking device. The driving power supply is used for supplying power to a magnetron, and comprises a first rectification filter circuit, a frequency conversion circuit, a power supply circuit and a processing circuit. The frequency conversion circuit comprises a transformer and a switching device, a control coil is located at a primary side of the transformer, the number of turns of the control coil is less than that of a primary coil, the power supply circuit is connected with the first rectification filter circuit through a first resistor and connected with the control coil through a second resistor, and the power supply circuit is configured to be charged through the first resistor before a charging voltage of the power supply circuit reaches a first set voltage and charged through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage. After the charging voltage of the power supply circuit reaches the first set voltage, the power supply circuit is charged through the second resistor, the loss of the second resistor caused by a high-voltage part of an alternating current power supply is effectively reduced, the use of a large resistor is reduced, the cost is reduced, and the miniaturization of the driving power supply is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of kitchen appliances, in particular to a driving power supply and a microwave cooking device. BACKGROUND

[0002] In the related art, a microwave oven includes a magnetron and a driving power supply, the driving power supply is connected to an AC power supply to supply power to the magnetron. The power supply circuit of the driving power supply provides power to the related circuits of the driving power supply by using the voltage after the rectification of the AC power supply through a voltage dividing resistor. However, since the AC power supply has a high-voltage part and a low-voltage part, the voltage dividing resistor generates a large amount of heat at the high-voltage part of the AC power supply, which reduces the service life of the voltage dividing resistor, or in order to ensure the service life of the voltage dividing resistor, a large resistor needs to be used, which increases the cost. SUMMARY

[0003] The present application provides a driving power supply and a microwave cooking device.

[0004] The present application provides a driving power supply for supplying power to a magnetron. The driving power supply includes a first rectification and filtering circuit, a frequency conversion circuit, a power supply circuit, and a processing circuit.

[0005] The frequency conversion circuit includes a transformer and a switching device, the transformer includes a primary coil and a control coil, the control coil is located at the primary side of the transformer, the number of turns of the control coil is less than the number of turns of the primary coil, the first rectification and filtering circuit is used to connect an AC power supply, and the primary coil is connected to the first rectification and filtering circuit.

[0006] The processing circuit is connected to the frequency conversion circuit and is used to control the on-off of the switching device.

[0007] The power supply circuit is connected to the first rectification and filtering circuit through a first resistor and is connected to the control coil through a second resistor, the power supply circuit is configured to charge through the first resistor before the charging voltage of the power supply circuit reaches a first set voltage, and to charge through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage.

[0008] In the above driving power supply, the power supply circuit is connected to the first rectification and filtering circuit through a first resistor and is connected to the control coil through a second resistor, the power supply circuit is configured to charge through the first resistor before the charging voltage of the power supply circuit reaches a first set voltage, and to charge through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage, and the number of turns of the control coil is less than the number of turns of the primary coil, which effectively reduces the loss of the second resistor at the high-voltage part of the AC power supply, improves the cost problem of the driving power supply, and also reduces the use of large resistors, so that the space configuration of the driving power supply is more flexible, which is conducive to the miniaturization of the driving power supply.

[0009] In some embodiments, the driving power source satisfies the condition: K1 / K2=1 / 34~2 / 17, wherein K1 represents the number of turns of the control coil, and K2 represents the number of turns of the primary coil.

[0010] In this way, the driving power source sets the ratio of the number of turns of the control coil to the number of turns of the primary coil to reduce the heat loss of the first resistor and the second resistor, while ensuring to provide a stable charging voltage for the power supply circuit, thereby ensuring stable operation of the driving power source.

[0011] In some embodiments, the frequency conversion circuit includes a resonance capacitor, two ends of the resonance capacitor being connected to two ends of the primary coil; the processing circuit includes a control circuit, a driving circuit and a synchronization circuit, the power supply circuit being connected to the driving circuit and the control circuit, and the synchronization circuit being connected to the control circuit and the control coil; the synchronization circuit is configured to detect the voltage of the resonance capacitor through the control coil; and the control circuit is configured to control the driving circuit to drive the switching device to be turned on in the case that the voltage of the resonance capacitor drops to zero volts.

[0012] In this way, the driving power source detects the voltage of the resonance capacitor through the synchronization circuit to control the driving circuit to drive the switching device to be turned on in the case that the voltage of the resonance capacitor drops to zero volts, thereby reducing the switching loss of the switching device.

[0013] In some embodiments, the control coil includes a first end and a second end, the first end being connected to a ground terminal, and the second end being connected to the synchronization circuit through a first diode and a third resistor, the output voltage of the control coil being the voltage of the second end rectified by the first diode with the ground terminal as a reference.

[0014] In this way, the driving power source rectifies the output voltage of the control coil through the first diode to ensure normal operation of the power supply circuit and the processing circuit.

[0015] In some embodiments, one end of the second resistor is connected between the negative electrode of the first diode and one end of the third resistor, and the other end of the second resistor is connected to the power supply circuit.

[0016] In this way, the voltage of the control coil is supplied to the power supply circuit through the second resistor to provide a stable charging voltage for the driving power source.

[0017] In some embodiments, the variable frequency circuit includes a resonance capacitor, two ends of the resonance capacitor are connected to two ends of the primary coil respectively; the processing circuit includes a control circuit, a driving circuit, a protection circuit and a voltage detection circuit, the power supply circuit is connected to the driving circuit and the control circuit, the protection circuit is connected to the control circuit and the control coil, and the voltage detection circuit is used to detect the voltage of the alternating power supply; the protection circuit is used to detect the voltage of the resonance capacitor through the control coil; the control circuit is used to correct the voltage of the resonance capacitor according to the voltage of the alternating power supply, and control the driving circuit to drive the switching device to be on or off according to the preset voltage protection threshold and the corrected voltage of the resonance capacitor, or the control circuit is used to correct the preset voltage protection threshold according to the voltage of the alternating power supply, and control the driving circuit to drive the switching device to be on or off according to the corrected preset voltage protection threshold and the voltage of the resonance capacitor.

[0018] In this way, the control circuit corrects the preset voltage protection threshold or the voltage of the resonance capacitor by acquiring the voltage of the alternating power supply and the voltage of the resonance capacitor, so as to achieve the purpose of protecting the switching device and improve the control accuracy of the control circuit.

[0019] In some embodiments, the control circuit is used to control the driving circuit to drive the switching device to be off when the corrected voltage of the resonance capacitor reaches the preset voltage protection threshold, or the control circuit is used to control the driving circuit to drive the switching device to be off when the voltage of the resonance capacitor reaches the corrected preset voltage protection threshold.

[0020] In this way, the control circuit compares the corrected preset voltage protection threshold with the voltage of the resonance capacitor, or compares the preset voltage protection threshold with the corrected voltage of the resonance capacitor, so as to achieve accurate protection of the switching device.

[0021] In some embodiments, the voltage detection circuit is connected to two ends of the alternating power supply through two second diodes.

[0022] In this way, the voltage detection circuit rectifies the alternating power supply through the two second diodes, so as to obtain the voltage of the alternating power supply.

[0023] In some embodiments, the driving power supply includes a second rectification and filtering circuit, the transformer includes a filament coil and an anode coil on the secondary side, the filament coil is connected to the second rectification and filtering circuit and the filament of the magnetron, and the anode coil is connected to the second rectification and filtering circuit and the anode of the magnetron.

[0024] Thus, the second rectification filter circuit rectifies the voltage amplified by the transformer to supply the magnetron.

[0025] The microwave cooking apparatus according to the embodiment of the present application includes a magnetron connected to the secondary side of the transformer.

[0026] In the microwave cooking apparatus, the power supply circuit is connected to the first rectification filter circuit through the first resistor and to the control coil through the second resistor, and the power supply circuit is configured to be charged through the first resistor before the charging voltage of the power supply circuit reaches the first set voltage and to be charged through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage, and the number of turns of the control coil is less than the number of turns of the primary coil, thereby effectively reducing the loss of the second resistor at the high voltage portion of the AC power supply, improving the cost problem of the driving power supply, and reducing the use of a large resistor, thereby making the space configuration of the driving power supply more flexible and facilitating the miniaturization of the driving power supply.

[0027] Additional aspects and advantages of the present application will be set forth in part in the description which follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following or can be learned from practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0028] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a circuit diagram of the driving power supply according to the embodiment of the present application;

[0030] Figure 2 is an output voltage waveform diagram of the control coil of the transformer according to the embodiment of the present application when the control coil is operated at a high frequency;

[0031] Figure 3 is an output voltage waveform diagram of the control coil of the transformer according to the embodiment of the present application at a certain power supply frequency;

[0032] Figure 4 is a graph showing the change of the charging voltage of the power supply circuit with respect to the operation time when the microwave cooking apparatus according to the embodiment of the present application is started;

[0033] Figure 5 is a voltage waveform diagram of the primary coil of the transformer according to the embodiment of the present application at a certain power supply frequency, with A terminal as a reference;

[0034] Figure 6 is a voltage waveform diagram of the primary side of the transformer according to the embodiment of the present application at an overvoltage;

[0035] Figure 7is a voltage waveform diagram of the primary side of the time-varying transformer under voltage of an embodiment of the present application;

[0036] Figure 8 is a circuit diagram of a driving power supply in the related art;

[0037] Figure 9 is a voltage waveform diagram of the primary coil of the transformer in the related art with GND as a reference under a certain power supply frequency;

[0038] Figure 10 is a waveform diagram of the maximum voltage of the frequency conversion circuit of the driving power supply in the related art under the operation of 30KHZ-50KHZ frequency.

[0039] Main component symbol explanation: driving power supply-100, magnetron-200, AC power supply-300, first rectification filter circuit-10, frequency conversion circuit-20, power supply circuit-30, processing circuit-40, second rectification filter circuit-50, filter capacitor-12, transformer-21, switching device-22, resonance capacitor-23, control circuit-41, driving circuit-42, synchronization circuit-43, protection circuit-44, voltage detection circuit-45, primary coil-211, control coil-212, filament coil-213, anode coil-214. DETAILED DESCRIPTION

[0040] Embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below are examples for explaining the present application and should not be construed as limiting the present application.

[0041] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be construed as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the present application. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0042] In the description of the present application, it is necessary to point out that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected. It can be mechanical connection, or electrical connection. It can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements, or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "lower", "below" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0044] The disclosure herein provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described herein. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples. Such repetition is for the purpose of simplification and clarity, and in itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0045] In the related art, please refer to Figures 8 to 10 , Figure 8 The circuit diagram of the driving power supply in the related art is Figure 9 The voltage waveform of the E end and the F end of the primary coil 711 when the power supply cycle (50HZ / 60HZ) is the voltage of the filter capacitor 62 at the E end, and the collector voltage waveform of the switching tube 72 at the F end. Figure 10 The waveform diagram of the maximum voltage when the frequency of the frequency conversion loop 70 is 30KHZ-50KHZ, Figure 10 The waveform indicates that when the switching tube 72 is closed, the primary coil 711 and the resonance capacitor 73 generate a resonance voltage, and the voltage is an up-down waveform. The power supply circuit 80 in the related art is supplied with power by the resistor R1', and the filter capacitor 62 is a high voltage equal to the alternating voltage 600. The power applied to the resistor R1' increases the loss of the resistor R1'.

[0046] Referring to Figures 1 to 7 The driving power supply 100 is configured to supply power to the magnetron 200. The driving power supply 100 comprises a first rectifier filter circuit 10, a frequency conversion circuit 20, a power supply circuit 30 and a processing circuit 40. The frequency conversion circuit 20 comprises a transformer 21 and a switching device 22. The transformer 21 comprises a primary coil 211 and a control coil 212. The control coil 212 is located at the primary side of the transformer 21. The number of turns of the control coil 212 is less than the number of turns of the primary coil 211. The first rectifier filter circuit 10 is configured to be connected to an alternating current power supply 300. The primary coil 211 is connected to the first rectifier filter circuit 10. The processing circuit 40 is connected to the frequency conversion circuit 20 and configured to control the switching device 22. The power supply circuit 30 is connected to the first rectifier filter circuit 10 through a first resistor R1 and connected to the control coil 212 through a second resistor R2. The power supply circuit 30 is configured to be charged through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches a first set voltage and to be charged through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage.

[0047] In the driving power supply 100, the power supply circuit 30 is connected to the first rectifier filter circuit 10 through the first resistor R1 and connected to the control coil 212 through the second resistor R2. The power supply circuit 30 is configured to be charged through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches the first set voltage and to be charged through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage. The number of turns of the control coil 212 is less than the number of turns of the primary coil 211. The loss of the second resistor R2 is effectively reduced when the alternating current power supply 300 is at a high voltage. The cost of the driving power supply 100 is improved. The use of large resistors is reduced. The space configuration of the driving power supply 100 is more flexible. The miniaturization of the driving power supply 100 is facilitated.

[0048] Specifically, the frequency conversion circuit 20 is connected to the first rectifier filter circuit 10. The frequency conversion circuit 20 is configured to output the rectified and filtered voltage. In an embodiment, the transformer 21 can be a step-up transformer. The transformer 21 is configured to step up the voltage rectified and filtered by the first rectifier filter circuit 10 to supply power to the magnetron 200.

[0049] In an embodiment, the switching device 22 can be a triode switching tube. When the switching device 22 is turned on, the primary coil 211 of the transformer 21 has current flowing through it. When the switching device 22 is turned off, the primary coil 211 of the transformer 21 releases the accumulated energy to the resonant capacitor 23 to form a resonance phenomenon.

[0050] The number of turns of the control coil 212 is less than the number of turns of the primary coil 211, and the control coil 212 is used to output a smaller voltage to supply to the power supply circuit 30, thereby reducing the loss of the first resistor R1 and the second resistor R2.

[0051] The first rectification and filtering circuit 10 can include a rectification circuit and a filtering circuit. The rectification circuit is mainly composed of rectification diodes, and is used to convert the voltage output by the alternating power supply 300 into direct current. In an embodiment, the number of rectification diodes can be 4, forming a rectification bridge, and in other embodiments, the number of rectification diodes can also be other numbers, which are not specifically limited here. The filtering circuit is connected to the rectification circuit and the frequency conversion circuit 20, and is used to reduce the alternating voltage component of the direct current output by the rectification circuit as much as possible, and retain the direct voltage part, so that the output voltage after filtering is more stable.

[0052] The power supply circuit 30 is used to supply voltage to the switching device 22 and the processing circuit 40, so that the processing circuit 40 can work normally.

[0053] The first set voltage can be the running start voltage of the driving power supply 100. Please combine Figure 4 That is, before the charging voltage of the power supply circuit 30 reaches the running start voltage of the driving power supply 100, the power supply circuit 30 charges through the first resistor R1. When the charging voltage of the power supply circuit 30 reaches the running start voltage of the driving power supply 100, the driving power supply 100 starts to run. After the charging voltage of the power supply circuit 30 reaches the running start voltage of the driving power supply 100, the power supply circuit 30 charges through the second resistor R2, so that the driving power supply 100 reaches a stable running voltage. In detail, the driving power supply 100 starts to run, and due to the control mode of soft start, the on-pulse width of the switching device 22 becomes larger, so that the transformer 21 runs. The current of the primary coil 211 of the transformer 21 increases, and the resonance voltage generated by the primary coil 211 and the resonance capacitor 23 increases, so that it can be ensured that the control coil 212 can supply power to the power supply circuit 30 through the second resistor R2 to maintain the normal work of the driving power supply 100, thereby reducing the loss of the first resistor R1 and the second resistor R2.

[0054] In some embodiments, the driving power supply 100 satisfies the condition:

[0055] K1 / K2 = 1 / 34 ~ 2 / 17, wherein K1 represents the number of turns of the control coil 212, and K2 represents the number of turns of the primary coil 211.

[0056] Therefore, the driving power supply 100 sets the ratio K1 / K2 of the number of turns K1 of the control coil 212 to the number of turns K2 of the primary coil 211 in the range [1 / 34, 2 / 17] to reduce the heat loss of the first resistor R1 and the second resistor R2, while ensuring that the power supply circuit 30 provides a stable charging voltage, thereby ensuring stable operation of the driving power supply 100.

[0057] Specifically, in one embodiment, the number of turns K2 of the primary coil 211 is greater than the number of turns K1 of the control coil 212, so that the control coil 212 outputs a lower voltage.

[0058] In one embodiment, according to the formula K1 / K2 = 1 / 34 ~ 2 / 17, the ratio K1 / K2 of the number of turns K1 of the control coil 212 to the number of turns K2 of the primary coil 211 is selected from the range [1 / 34, 2 / 17], i.e. 1 / 34≤K1 / K2≤2 / 17. In one example, K1 / K2 can be 1 / 34, 1 / 20, 1 / 17, 1 / 10, 2 / 17 or other values between 1 / 34 and 2 / 17.

[0059] By setting K1 / K2 to be selected from the range [1 / 34, 2 / 17], on the one hand, the lower voltage of the control coil 212 can reduce the loss of the first resistor R1 and the second resistor R2, and on the other hand, the lower voltage of the control coil 212 can provide a stable charging voltage for the power supply circuit 30, to ensure stable operation of the driving power supply 100.

[0060] Please refer to Figure 1 and Figure 2 In some embodiments, the frequency conversion circuit 20 includes a resonant capacitor 23, two ends of the resonant capacitor 23 being connected to two ends of the primary coil 211. The processing circuit 40 includes a control circuit 41, a driving circuit 42 and a synchronization circuit 43. The power supply circuit 30 is connected to the driving circuit 42 and the control circuit 41, the synchronization circuit 43 is connected to the control circuit 41 and the control coil 212, and the synchronization circuit 43 is used to detect the voltage of the resonant capacitor 23 through the control coil 212. The control circuit 41 is used to control the driving circuit 42 to drive the switching device 22 to conduct in the case that the voltage of the resonant capacitor 23 drops to zero volts.

[0061] Therefore, the driving power supply 100 detects the voltage of the resonant capacitor 23 through the synchronization circuit 43 to control the driving circuit 42 to drive the switching device 22 to conduct in the case that the voltage of the resonant capacitor 23 drops to zero volts, thereby reducing the switching loss of the switching device 22.

[0062] Specifically, in one embodiment, the voltage outputted by the control coil 212 can be the resonance capacitance turns ratio voltage. The voltage outputted by the control coil 212 can be detected by the synchronization circuit 43, and according to the turns ratio K1 / K2 selected from the range [1 / 34, 2 / 17] as described above, the voltage of the resonance capacitance 23 can be converted from the voltage outputted by the control coil 212 by the turns ratio K1 / K2. For example, when the value of the turns ratio K1 / K2 is 0.1 and the voltage outputted by the control coil 212 is 10V, the voltage of the resonance capacitance 23 can be calculated to be 100V. The above example is only for understanding the use of the present application and should not limit the actual application of the present application.

[0063] Please refer to Figure 2 , OFF refers to the waveform of the resonance capacitance turns ratio voltage when the switching device 22 is off. At the same time, ON refers to the waveform of the resonance capacitance turns ratio voltage that first rises and then falls to zero volts during the off period of the switching device 22 to reduce the switching loss of the switching device 22.

[0064] In one embodiment, the resonance capacitance 23 is connected in parallel with the primary coil 211, and the resonance capacitance 23 and the primary coil 211 form a resonance circuit containing a capacitance and an inductive coil. In the case where the switching device 22 is off, the resonance capacitance 23 can generate a resonance phenomenon in the resonance circuit to achieve instantaneous voltage boosting.

[0065] In one embodiment, the control circuit 41 can be used to correct the difference between the voltage of the AC power supply 300 and the voltage of the resonance capacitance 23 detected by the synchronization circuit 43 to ensure the normal operation of the driving power supply 100.

[0066] The driving circuit 42 can receive the driving signal outputted by the control circuit 41 to drive the switching device 22 to be on or off.

[0067] In the case where the synchronization circuit 43 detects that the voltage of the resonance capacitance 23 drops to zero volts, the control circuit 41 outputs a signal to the driving circuit 42 to drive the switching device 22 to be on, so that the switching loss of the switching device 22 is reduced.

[0068] Please refer to Figure 1 and Figure 3 In some embodiments, the control coil 212 includes a first end C and a second end D, the first end C is connected to the ground, and the second end D is connected to the synchronization circuit 43 through the first diode D1 and the third resistor R3. The output voltage of the control coil 212 is the voltage of the second end D rectified by the first diode D1 with the ground as the reference.

[0069] Thus, the driving power supply 100 rectifies the output voltage of the control coil 212 through the first diode Dl to ensure the normal operation of the power supply circuit 30 and the processing circuit 40.

[0070] Specifically, as shown in Figure 3 one embodiment, the first end C of the control coil 212 is connected to the ground, i.e., the first end C of the control coil 212 can be used as a reference point with a potential of zero.

[0071] The control coil 212 has a turns ratio K1 / K2 with the primary coil 211, and the output voltage of the control coil 212 is rectified through the second end D of the control coil 212 via the first diode Dl and then output.

[0072] The synchronization circuit 43 is connected to the first end C and the second end D of the control coil 212, and can be used to detect the output voltage of the control coil 212, and then obtain the voltage of the resonance capacitor 23 according to the turns ratio of the control coil 212 and the primary coil 211.

[0073] The first diode Dl can be a rectifier diode to supply the power supply circuit 30 and the processing circuit 40 to work.

[0074] The first diode Dl has a unidirectional conductivity, i.e., the current can only flow from the second end D of the control coil 212 to the second resistor R2 and the third resistor R3 through the first diode Dl, and the current cannot flow from the second resistor R2 to the second end D of the control coil 212 through the first diode Dl. Therefore, please refer to Figure 3 , taking the first end C of the control coil 212 as a reference, the voltage of the resonance capacitor 23 is output through the control coil 212 with a lower power similar waveform.

[0075] Please refer to Figure 1 and Figure 4 In some embodiments, one end of the second resistor R2 is connected between the negative electrode of the first diode Dl and one end of the third resistor R3, and the other end of the second resistor R2 is connected to the power supply circuit 30.

[0076] Thus, the voltage of the control coil 212 is supplied to the power supply circuit 30 through the second resistor R2 to provide a stable charging voltage for the driving power supply 100.

[0077] Specifically, in one embodiment, the output voltage of the control coil 212 is rectified through the first diode Dl and then transmitted to the second resistor R2 and the third resistor R3, respectively. That is, the second resistor R2 and the third resistor R3 are connected in parallel to divide the voltage, so that the voltage of the control coil 212 transmitted to the power supply circuit 30 through the second resistor R2 is reduced to ensure that the heat loss of the second resistor R2 is reduced under the condition that the power supply circuit 30 operates normally.

[0078] Further, when the charging voltage of the power supply circuit 30 reaches the operation start voltage of the driving power supply 100, the driving power supply 100 starts to operate, the power supply circuit 30 is supplied with power by the second resistor R2 through the control coil 212, and the heat loss of the first resistor R1 is reduced.

[0079] In one embodiment, please refer to Figure 4 In the case that the microwave cooking device starts to operate, the power supply circuit 30 is configured to charge the power supply circuit 30 through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches the operation start voltage of the driving power supply 100, and the charging voltage of the power supply circuit 30 slowly rises. After the charging voltage of the power supply circuit reaches the operation start voltage of the driving power supply 100, the on-pulse width of the switching device 22 becomes larger due to the soft start control mode, and the transformer 21 operates. The current of the primary coil 211 of the transformer 21 increases, the resonance voltage generated by the primary coil 211 and the resonance capacitor 23 increases, and the power supply circuit 30 is supplied with power by the second resistor R2 through the control coil 212 to reach a stable operating voltage.

[0080] In another embodiment, as Figure 5 shown, Figure 5 is a waveform diagram of the B end of the primary coil 211 of the transformer 21 with the A end as a reference. In the case that the switching device 22 is off, the resonance capacitor 23 and the primary coil 211 generate resonance phenomenon, and the voltage of the resonance capacitor 23 is greater than the voltage of the filter capacitor 12. That is, the voltage waveform of the resonance capacitor 23 is higher and located above the A end, and the voltage waveform of the filter capacitor 12 is lower and located below the A end.

[0081] Please refer to Figure 1 In some embodiments, the frequency conversion circuit 20 includes the resonance capacitor 23, two ends of the resonance capacitor 23 are connected to two ends of the primary coil 211. The processing circuit 40 includes the control circuit 41, the driving circuit 42, the protection circuit 44, and the voltage detection circuit 45. The power supply circuit 30 is connected to the driving circuit 42 and the control circuit 41. The protection circuit 44 is connected to the control circuit 41 and the control coil 212. The voltage detection circuit 45 is used to detect the voltage of the alternating current power supply 300. The protection circuit 44 is used to detect the voltage of the resonance capacitor 23 through the control coil 212. The control circuit 41 is used to correct the voltage of the resonance capacitor 23 according to the voltage of the alternating current power supply 300, and control the driving circuit 42 to drive the switching device 22 to turn on and off according to the preset voltage protection threshold and the corrected voltage of the resonance capacitor 23; or, the control circuit 41 is used to correct the preset voltage protection threshold according to the voltage of the alternating current power supply 300, and control the driving circuit 42 to drive the switching device 22 to turn on and off according to the corrected preset voltage protection threshold and the voltage of the resonance capacitor 23.

[0082] Therefore, the control circuit 41 achieves the purpose of protecting the switching device 22 by obtaining the voltage of the AC power supply 300 and the voltage of the resonant capacitor 23 to correct the preset voltage protection threshold or the voltage of the resonant capacitor 23, thereby improving the control accuracy of the control circuit 41.

[0083] Specifically, in one embodiment, the voltage of the filter capacitor 12 is the voltage of the AC power supply 300 after rectification by the first rectification and filter circuit 10. The voltage detected by the voltage detection circuit 45 is the voltage across the AC power supply 300 after rectification. That is, the voltage of the AC power supply 300 after rectification detected by the voltage detection circuit 45 is equal to the voltage of the filter capacitor 12, and the voltage detection circuit 45 can directly obtain the voltage of the filter capacitor 12.

[0084] By correcting the preset voltage protection threshold or the voltage of the resonant capacitor 23 with the voltage of the filter capacitor 12, the corrected preset voltage protection threshold or the voltage of the resonant capacitor 23 after correction can better reflect the voltage condition of the actual AC power supply 300, thereby improving the control accuracy of the control circuit 41.

[0085] In one embodiment, the protection circuit 44 can be an overvoltage protection circuit, an undervoltage protection circuit, or other circuits, which are not specifically limited here.

[0086] Please refer to Figure 1 , Figure 6 and Figure 7 In some embodiments, the control circuit 41 is configured to control the drive circuit 42 to turn off the switching device 22 when the voltage of the resonant capacitor 23 after correction reaches the preset voltage protection threshold, or the control circuit 41 is configured to control the drive circuit 42 to turn off the switching device 22 when the voltage of the resonant capacitor 23 reaches the preset voltage protection threshold after correction.

[0087] Therefore, the control circuit 41 compares the corrected preset voltage protection threshold with the voltage of the resonant capacitor 23, or compares the preset voltage protection threshold with the voltage of the resonant capacitor 23 after correction, to accurately protect the switching device 22.

[0088] Specifically, in one embodiment, please refer to Figure 6 The protection circuit 44 can be an overvoltage protection circuit, and the preset voltage protection threshold includes an overvoltage protection threshold V1. That is, when the voltage of the filter capacitor is high (overvoltage) and the voltage of the resonant capacitor 23 is low, the control circuit 41 corrects the overvoltage protection threshold V1, specifically, pulls down the overvoltage protection threshold V1, so that the voltage of the resonant capacitor 23 can reach the pulled-down overvoltage protection threshold V1, and the control circuit 41 can control the drive circuit 42 to turn off the switching device 22.

[0089] In one embodiment, referring to Figure 7 , the protection circuit 44 is an under-voltage protection circuit, and the preset voltage protection threshold includes an under-voltage protection threshold V2. That is, when the voltage of the filter capacitor is low (under-voltage) and the voltage of the resonant capacitor 23 is high, the control circuit 41 corrects the under-voltage protection threshold V2, specifically, pulls up the under-voltage protection threshold V2, so that the voltage of the resonant capacitor 23 reaches the pulled-up under-voltage protection threshold V2 more slowly, and the control circuit 41 can control the driving circuit 42 to drive the switching device 22 to turn off.

[0090] It can be understood that the embodiment of correcting the voltage of the resonant capacitor 23 can refer to the above-mentioned embodiment of correcting the preset voltage protection threshold, which will not be expanded here.

[0091] According to the turns ratio of the control coil 212 and the primary coil 211, the protection circuit 44 is configured to detect the voltage of the resonant capacitor 23 through the control coil 212.

[0092] The control circuit 41 can directly obtain the voltage of the filter capacitor 12 through the voltage detection circuit 45 and obtain the voltage of the resonant capacitor 23 through the protection circuit 44.

[0093] In some embodiments, the voltage detection circuit 45 is connected to both ends of the alternating current power supply 300 through two second diodes D2.

[0094] In this way, the voltage detection circuit 45 rectifies the alternating current power supply 300 through the two second diodes D2 to facilitate detection of the voltage of the alternating current power supply 300.

[0095] Specifically, in one embodiment, the second diode D2 can be a rectifier diode.

[0096] The two second diodes D2 are respectively connected to both ends of the alternating current power supply 300, which can be used to rectify the alternating voltage between the two ends of the alternating current power supply 300 to form a direct current voltage.

[0097] The voltage detection circuit 45 can obtain the voltage of the rectified alternating current power supply 300 through the two second diodes D2 to output to the control circuit 41 for processing.

[0098] In some embodiments, the driving power supply 100 includes a second rectification and filtering circuit 50, the transformer 21 includes a filament coil 213 and an anode coil 214 on the secondary side, the filament coil 213 is connected to the second rectification and filtering circuit 50 and the filament of the magnetron 200, and the anode coil 214 is connected to the second rectification and filtering circuit 50 and the anode of the magnetron.

[0099] Thus, the second rectification filter circuit 50 rectifies the voltage amplified by the transformer 21 to supply the magnetron 200 with a direct current.

[0100] Specifically, in one embodiment, the second rectification filter circuit 50 rectifies and filters the voltage amplified by the transformer 21 to obtain a direct current, which is then supplied to the magnetron 200.

[0101] In one embodiment, the filament coil 213 is configured to supply a voltage to the filament of the magnetron 200 to cause the filament to emit electrons. The anode coil 214 is configured to supply a voltage to the anode of the magnetron 200 to attract the electrons to move and hit the anode of the magnetron 200 to generate microwaves, which are used to heat food in a microwave cooking apparatus.

[0102] The embodiment of the present application also provides a microwave cooking apparatus. The microwave cooking apparatus comprises the magnetron 200 and the driving power supply 100 of any of the above embodiments, and the magnetron 200 is connected to the secondary side of the transformer 21.

[0103] In the microwave cooking apparatus, the power supply circuit 30 is connected to the first rectification filter circuit 10 through the first resistor R1 and connected to the control coil 212 through the second resistor R2. The power supply circuit 30 is configured to be charged through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches the first set voltage, and to be charged through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage. The number of turns of the control coil 212 is less than the number of turns of the primary coil 211, which effectively reduces the loss of the second resistor R2 at the high voltage part of the alternating current power supply, improves the cost problem of the driving power supply 100, and also reduces the use of large resistors, making the space configuration of the driving power supply 100 more flexible and facilitating the miniaturization of the driving power supply 100.

[0104] Specifically, the microwave cooking apparatus includes, but is not limited to, a microwave oven, a microwave steaming and baking all-in-one machine, a microwave rice cooker, and other household appliances.

[0105] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0106] While the embodiments of the application have been shown and described, it is to be understood that the embodiments can be varied, modified, substituted and otherwise changed by those skilled in the art without departing from the principles and spirit of the application. It is therefore intended that this application not be limited to the particular embodiments disclosed, but that the application will include all embodiments falling within the scope of the appended claims and their equivalents.

Claims

1. A driving power supply for supplying power to a magnetron, characterized in that, The driving power supply comprises a first rectification filter circuit, a frequency conversion circuit, a power supply circuit and a processing circuit; The frequency conversion circuit comprises a transformer and a switching device, the transformer comprises a primary coil and a control coil, the control coil is located at the primary side of the transformer, the number of turns of the control coil is less than the number of turns of the primary coil, the first rectification filter circuit is used for connecting an alternating current power supply, and the primary coil is connected to the first rectification filter circuit; The processing circuit is connected to the frequency conversion circuit and is used for controlling the switching device to be turned on or turned off; The power supply circuit is connected to the first rectification filter circuit through a first resistor and connected to the control coil through a second resistor, the power supply circuit is configured to be charged through the first resistor before the charging voltage of the power supply circuit reaches a first set voltage and to be charged through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage.

2. The driving power supply according to claim 1, characterized by The driving power supply satisfies the condition: K1 / K2=1 / 34~2 / 17, wherein K1 represents the number of turns of the control coil and K2 represents the number of turns of the primary coil.

3. The driving power supply according to claim 1, wherein The frequency conversion circuit comprises a resonance capacitor, two ends of the resonance capacitor are respectively connected to two ends of the primary coil; The processing circuit comprises a control circuit, a driving circuit and a synchronization circuit, the power supply circuit is connected to the driving circuit and the control circuit, and the synchronization circuit is connected to the control circuit and the control coil; The synchronization circuit is used for detecting the voltage of the resonance capacitor through the control coil; The control circuit is used for controlling the driving circuit to drive the switching device to be turned on in the case that the voltage of the resonance capacitor drops to zero volt.

4. The driving power supply according to claim 3, characterized by The control coil comprises a first end and a second end, the first end is connected to a ground terminal, the second end is connected to the synchronization circuit through a first diode and a third resistor, and the output voltage of the control coil is the voltage of the second end rectified by the first diode with the ground terminal as a reference.

5. The driving power supply according to claim 4, wherein One end of the second resistor is connected between the negative electrode of the first diode and one end of the third resistor, and the other end of the second resistor is connected to the power supply circuit.

6. The driving power supply according to claim 1, wherein The frequency conversion circuit comprises a resonance capacitor, two ends of the resonance capacitor are respectively connected to two ends of the primary coil; The processing circuit comprises a control circuit, a driving circuit, a protection circuit and a voltage detection circuit, the power supply circuit is connected to the driving circuit and the control circuit, the protection circuit is connected to the control circuit and the control coil, and the voltage detection circuit is used for detecting the voltage of the alternating current power supply; The protection circuit is used for detecting the voltage of the resonance capacitor through the control coil; The control circuit is used for correcting the voltage of the resonance capacitor according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be turned on or turned off according to a preset voltage protection threshold value and the voltage of the resonance capacitor after correction, or the control circuit is used for correcting the preset voltage protection threshold value according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be turned on or turned off according to the preset voltage protection threshold value after correction and the voltage of the resonance capacitor.

7. The driving power supply according to claim 6, wherein The control circuit is configured to control the driving circuit to drive the switching device to be turned off when the voltage of the corrected resonant capacitor reaches the preset voltage protection threshold. The control circuit is configured to control the driving circuit to drive the switching device to be turned off when the voltage of the resonant capacitor reaches the corrected preset voltage protection threshold.

8. The driving power supply according to claim 6, wherein The voltage detection circuit is connected to both ends of the AC power supply through two second diodes.

9. The driving power supply according to claim 1, wherein The driving power supply comprises a second rectifying and filtering circuit, the transformer comprises a filament coil and an anode coil on the secondary side, the filament coil is connected to the second rectifying and filtering circuit and the filament of the magnetron, and the anode coil is connected to the second rectifying and filtering circuit and the anode of the magnetron.

10. A microwave cooking apparatus, characterized by, The driving power supply comprises a magnetron and the driving power supply according to any one of claims 1-9, and the magnetron is connected to the secondary side of the transformer.

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