CN116723598A - Driving power supply and microwave cooking apparatus - Google Patents

Abstract

The invention discloses a driving power supply and microwave cooking equipment. The driving power supply is used for supplying power to the magnetron and comprises a first rectifying and filtering 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 control coil is positioned on the primary side of the transformer, the number of turns of the control coil is smaller than that of the primary coil, the power supply circuit is connected with the first rectifying and filtering circuit through the first resistor and connected with the control coil through the second resistor, and 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 charge through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage. According to the driving power supply, after the charging voltage of the power supply circuit reaches the first set voltage, the second resistor is charged, so that the loss of the high-voltage part of the alternating current power supply to the second resistor is effectively reduced, the use of a large resistor can be reduced, the cost is reduced, and the miniaturization of the driving power supply is facilitated.

Description

Driving power supply and microwave cooking apparatus

Technical Field

The invention relates to the technical field of kitchen appliances, in particular to a driving power supply and microwave cooking equipment.

Background

In the related art, a microwave oven includes a magnetron and a driving power source connected to an ac power source to supply power to the magnetron. The power supply circuit of the driving power supply supplies power to the related circuits of the driving power supply by using the voltage rectified by the alternating current power supply through the voltage dividing resistor. However, since the ac power supply has a high voltage portion and a low voltage portion, the heating of the voltage dividing resistor is large at the high voltage portion of the ac power supply, resulting in a reduction in the life of the voltage dividing resistor, or a large-sized resistor is required to be used in order to secure the life of the voltage dividing resistor, resulting in a corresponding increase in cost.

Disclosure of Invention

The embodiment of the invention provides a driving power supply and microwave cooking equipment.

Embodiments of the present invention provide a driving power supply for supplying power to a magnetron. The driving power supply comprises a first rectifying and filtering 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 positioned on the primary side of the transformer, the number of turns of the control coil is smaller than that of the primary coil, the first rectification filter circuit is used for being connected with an alternating current power supply, and the primary coil is connected with the first rectification filter circuit;

the processing circuit is connected with the frequency conversion circuit and used for controlling the on-off of the switching device;

the power supply circuit is connected with the first rectifying and filtering circuit through a first resistor, is connected with the control coil through a second resistor, and 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.

In the driving power supply, the power supply circuit is connected with the first rectifying and filtering circuit through the first resistor and is connected with the control coil through the 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 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, the number of turns of the control coil is smaller than that of the primary coil, so that the loss of the second resistor in the high-voltage part of the alternating current power supply is effectively reduced, the cost problem of the driving power supply is improved, the use of large resistors can be reduced, the space configuration of the driving power supply is more flexible, and the driving power supply is beneficial to miniaturization of the driving power supply.

In certain embodiments, the driving power supply satisfies the condition: k1/k2=1/34 to 2/17, where K1 represents the number of turns of the control coil and K2 represents the number of turns of the primary coil.

Therefore, the driving power supply is provided with the ratio range of the number of turns of the control coil to the number of turns of the primary coil, so that heating loss of the first resistor and the second resistor is reduced, and meanwhile, stable charging voltage of the power supply circuit can be guaranteed, and stable operation of the driving power supply is guaranteed.

In some embodiments, the frequency conversion circuit includes a resonance capacitor, and two ends of the resonance capacitor are respectively connected with two ends of the primary coil; the processing circuit comprises a control circuit, a driving circuit and a synchronous circuit, wherein the power circuit is connected with the driving circuit and the control circuit, and the synchronous circuit is connected with the control circuit and the control coil; the synchronous circuit is used for detecting the voltage of the resonant capacitor through the control coil; the control circuit is used for controlling the driving circuit to drive the switching device to be conducted under the condition that the voltage of the resonant capacitor is reduced to zero volt.

Therefore, the driving power supply detects the voltage of the resonant capacitor through the synchronous circuit to control the driving circuit to drive the switching device to be conducted under the condition that the voltage of the resonant capacitor is reduced to zero volt, so that the switching loss of the switching device is reduced.

In some embodiments, the control coil includes a first end and a second end, the first end is connected to a ground, 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 a voltage obtained by rectifying the voltage of the second end through the first diode with the ground as a reference.

Therefore, the driving power supply rectifies and outputs the output voltage of the control coil through the first diode, and the power supply circuit and the processing circuit are ensured to work normally.

In some embodiments, one end of the second resistor is connected between the cathode of the first diode and one end of the third resistor, and the other end of the second resistor is connected to the power circuit.

Thus, the voltage of the control coil is supplied to the power circuit through the second resistor to provide a stable charging voltage for the driving power.

In some embodiments, the frequency conversion circuit includes a resonance capacitor, and two ends of the resonance capacitor are respectively connected with two ends of the primary coil; the processing circuit comprises a control circuit, a driving circuit, a protection circuit and a voltage detection circuit, wherein the power circuit is connected with the driving circuit and the control circuit, the protection circuit is connected with 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 resonant capacitor according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be switched on and off according to a preset voltage protection threshold and the corrected voltage of the resonant capacitor, or is used for correcting the preset voltage protection threshold according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be switched on and off according to the corrected preset voltage protection threshold and the corrected voltage of the resonant capacitor.

Therefore, the control circuit corrects the preset voltage protection threshold or the voltage of the resonance capacitor by acquiring the voltage of the alternating current power supply and the voltage of the resonance capacitor, so that the purpose of protecting the switching device is achieved, and the control precision of the control circuit is improved.

In some embodiments, the control circuit is configured to control the driving circuit to drive the switching device to turn off or to control the switching device to turn off when the corrected voltage of the resonant capacitor reaches the preset voltage protection threshold; the control circuit is used for controlling the driving circuit to drive the switching device to be turned off under the condition that the voltage of the resonant capacitor reaches the corrected preset voltage protection threshold value.

Therefore, the control circuit realizes accurate protection of the switching device by comparing the corrected preset voltage protection threshold value with the voltage of the resonance capacitor or comparing the preset voltage protection threshold value with the voltage of the corrected resonance capacitor.

In some embodiments, the voltage detection circuit is connected to two ends of the ac power supply through two second diodes, respectively.

Thus, the voltage detection circuit rectifies the alternating current power supply through the two second diodes so as to be convenient for detecting and obtaining the voltage of the alternating current power supply.

In some embodiments, the driving power supply includes a second rectifying and filtering circuit, the transformer includes a filament coil on a secondary side and an anode coil, the filament coil is connected with the second rectifying and filtering circuit and filaments of the magnetron, and the anode coil is connected with the second rectifying and filtering circuit and anodes of the magnetron.

Thus, the second rectifying and filtering circuit rectifies the voltage amplified by the transformer to supply the magnetron to work.

An embodiment of the present invention provides a microwave cooking apparatus, which includes a magnetron and the driving power supply described in any of the above embodiments, wherein the magnetron is connected to a secondary side of the transformer.

In the microwave cooking device, the power supply circuit is connected with the first rectifying and filtering circuit through the first resistor and is connected with the control coil through the 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 the first set voltage, and is charged through the second resistor after the charging voltage of the power supply circuit reaches the first set voltage, the number of turns of the control coil is smaller than that of the primary coil, so that the loss of the second resistor in the high-voltage part of the alternating current power supply is effectively reduced, the cost problem of the driving power supply is improved, the use of large resistors can be reduced, the space configuration of the driving power supply is more flexible, and the miniaturization of the driving power supply is facilitated.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a circuit diagram of a driving power supply according to an embodiment of the present invention;

fig. 2 is a waveform diagram of an output voltage of the control coil of the transformer according to the embodiment of the present invention at the time of high frequency operation;

FIG. 3 is a waveform diagram of the output voltage of the control coil of the transformer at a certain power frequency in accordance with an embodiment of the present invention;

fig. 4 is a graph showing a change of a charging voltage of a power circuit with an operation time when a microwave cooking apparatus according to an embodiment of the present invention is started;

fig. 5 is a voltage waveform diagram of a primary coil of a transformer according to an embodiment of the present invention with reference to an a terminal at a certain power supply frequency;

fig. 6 is a voltage waveform diagram of the primary side of the transformer at overvoltage according to an embodiment of the invention;

FIG. 7 is a voltage waveform diagram of the primary side of the transformer at undervoltage in accordance with an embodiment of the present invention;

fig. 8 is a circuit diagram of a driving power supply in the related art;

fig. 9 is a voltage waveform diagram of a primary coil of a transformer in the related art with reference to GND at a certain power supply frequency;

fig. 10 is a waveform diagram of a frequency conversion circuit of a driving power supply in the related art at a maximum voltage operating at a frequency of 30KHZ to 50 KHZ.

Description of main reference numerals: the power supply comprises a driving power supply-100, a magnetron-200, an alternating current power supply-300, a first rectifying and filtering circuit-10, a frequency conversion circuit-20, a power supply circuit-30, a processing circuit-40, a second rectifying and filtering circuit-50, a filtering capacitor-12, a transformer-21, a switching device-22, a resonant capacitor-23, a control circuit-41, a driving circuit-42, a synchronization circuit-43, a protection circuit-44, a voltage detection circuit-45, a primary coil-211, a control coil-212, a filament coil-213 and an anode coil-214.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.

In the description of the present invention, 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", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present invention, it should be noted that the terms "mounted," "connected," and "coupled" are to be construed broadly, as well as, for example, fixedly coupled, detachably coupled, or integrally coupled, unless otherwise specifically indicated and defined. Either mechanically or electrically. Can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.

The disclosure herein provides many different embodiments or examples for implementing different structures of the invention. To simplify the present disclosure, components and arrangements of specific examples are described herein. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

In the related art, referring to fig. 8 to 10, fig. 8 is a circuit diagram of a driving power supply in the related art, fig. 9 is a voltage waveform of the E terminal and the F terminal of the primary coil 711 during a power cycle (50 HZ/60 HZ), the E terminal is a voltage of the filter capacitor 62, and the F terminal is a collector voltage waveform of the switching tube 72. Fig. 10 is a waveform diagram of the frequency conversion circuit 70 at the maximum voltage at which the frequency is 30KHZ to 50KHZ, and the waveform of fig. 10 shows a waveform in which the primary coil 711 and the resonance capacitor 73 generate resonance voltage when the switching tube 72 is turned off, and the voltage is increased and decreased. The power supply circuit 80 in the related art is supplied with power from the resistor R1', and the filter capacitor 62 is a high voltage equivalent to the ac voltage 600, and the loss of the resistor R1' increases by the power applied to the resistor R1 '.

Referring to fig. 1 to 7, a driving power supply 100 according to an embodiment of the present invention is used for supplying power to a magnetron 200. The driving power supply 100 includes a first rectifying and filtering circuit 10, a frequency conversion circuit 20, a power supply circuit 30, and a processing circuit 40. The frequency conversion circuit 20 includes a transformer 21 and a switching device 22, the transformer 21 includes a primary coil 211 and a control coil 212, the control coil 212 is located on the primary side of the transformer 21, the number of turns of the control coil 212 is smaller than that of the primary coil 211, the first rectifying and filtering circuit 10 is used for connecting with the ac power supply 300, and the primary coil 211 is connected with the first rectifying and filtering circuit 10. The processing circuit 40 is connected to the frequency conversion circuit 20 and is used for controlling the on-off of the switching device 22. The power supply circuit 30 is connected to the first rectifying and filtering circuit 10 through a first resistor R1, and is connected to the control coil 212 through a second resistor R2, and the power supply circuit 30 is configured to charge through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches a first set voltage, and to charge through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage.

In the driving power supply 100, the power supply circuit 30 is connected to the first rectifying and filtering circuit 10 through the first resistor R1, and is connected to the control coil 212 through the second resistor R2, the power supply circuit 30 is configured to charge through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches the first set voltage, and to charge through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage, and the number of turns of the control coil 212 is smaller than that of the primary coil 211, so that the loss of the second resistor R2 in the high-voltage portion of the ac power supply 300 is effectively reduced, the cost problem of the driving power supply 100 is improved, the use of large resistors can be reduced, the space configuration of the driving power supply 100 is more flexible, and the miniaturization of the driving power supply 100 is facilitated.

Specifically, the frequency conversion circuit 20 is connected to the first rectifying and filtering circuit 10, and the frequency conversion circuit 20 is configured to output the rectified and filtered voltage. In one embodiment, the transformer 21 may be a step-up transformer. The transformer 21 is used to boost the voltage rectified and filtered by the first rectifying and filtering circuit 10 to supply the magnetron 200 with operation.

In one embodiment, switching device 22 may be a triode switch. When the switching device 22 is turned on, a current flows through the primary winding 211 of the transformer 21. In the case where the switching device 22 is turned off, the primary coil 211 of the transformer 21 discharges the accumulated energy to the resonance capacitor 23 to form a resonance phenomenon.

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

The first rectifying and filtering circuit 10 may include a rectifying circuit and a filtering circuit. The rectifying circuit is mainly composed of a rectifying diode, and is used for converting the voltage output by the ac power supply 300 into dc. In one embodiment, the number of rectifier diodes may be 4 to form a rectifier bridge, and in other embodiments, the number of rectifier diodes may be other, without being limited thereto. The filtering circuit is connected to the rectifying circuit and the frequency conversion circuit 20, and is used for reducing the ac voltage component of the dc power output by the rectifying circuit as much as possible and retaining the dc voltage component, so that the filtered output voltage is more stable.

The power supply circuit 30 is used to supply a voltage to the switching device 22 and the processing circuit 40 so that the processing circuit 40 can operate normally.

The first set voltage may be an operation start voltage of the driving power source 100. Referring to fig. 4, that is, before the charging voltage of the power circuit 30 reaches the operation start voltage of the driving power supply 100, the power circuit 30 is charged through the first resistor R1. 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. After the charging voltage of the power supply circuit 30 reaches the operation 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 the stable operation voltage. In detail, the driving power source 100 starts to operate, and the on pulse width of the switching device 22 becomes large due to the control mode of the soft start, so that the transformer 21 operates. 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 the control coil 212 can supply power to the power circuit 30 through the second resistor R2 to maintain the normal operation of the driving power supply 100, thereby reducing the loss of the first resistor R1 and the second resistor R2.

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

k1/k2=1/34 to 2/17, where K1 represents the number of turns of the control coil 212 and K2 represents the number of turns of the primary coil 211.

In this way, the driving power supply 100 can reduce the heating loss of the first resistor R1 and the second resistor R2 by setting the ratio range [1/34,2/17] of the number of turns K1 of the control coil 212 and the number of turns K2 of the primary coil 211, and can ensure the stable charging voltage of the power supply circuit 30, thereby ensuring the stable operation of the driving power supply 100.

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 voltage output by the control coil 212 is low.

In one embodiment, 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.ltoreq.K1/K2.ltoreq.2/17, according to the formula K1/K2=1/34.about.2/17. In one example, K1/K2 may be 1/34, 1/20, 1/17, 1/10, 2/17, or other values between 1/34 and 2/17.

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 losses of the first resistor R1 and the second resistor R2, and on the other hand, the lower voltage of the control coil 212 can stably supply the charging voltage to the power supply circuit 30 to ensure the stable operation of the driving power supply 100.

Referring to fig. 1 and 2, in some embodiments, the frequency conversion circuit 20 includes a resonant capacitor 23, and two ends of the resonant capacitor 23 are respectively 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 drive circuit 42 and the control circuit 41, and the synchronization circuit 43 is connected to the control circuit 41 and the control coil 212, and the synchronization circuit 43 is configured to detect the voltage of the resonance capacitor 23 through the control coil 212. The control circuit 41 is configured to control the driving circuit 42 to drive the switching device 22 to be turned on when the voltage of the resonant capacitor 23 drops to zero volts.

In this way, 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 be turned on when the voltage of the resonant capacitor 23 drops to zero volt, thereby reducing the switching loss of the switching device 22.

Specifically, in one embodiment, the voltage output by control coil 212 may be a resonant capacitor turns ratio voltage. The voltage output from the control coil 212 can be detected by the synchronizing circuit 43, and the voltage of the resonance capacitor 23 can be obtained by converting the turns ratio K1/K2 with the voltage output from the control coil 212, according to the turns ratio K1/K2 selected from the range [1/34,2/17 ]. For example, when the value of the turns ratio K1/K2 is 0.1 and the voltage output from the control coil 212 is 10V, the voltage of the resonance capacitor 23 can be calculated as 100V. The above examples are only for understanding the purpose of the present invention and should not limit the practical application of the present invention.

Referring to fig. 2, off refers to a waveform of a resonant capacitor turns ratio voltage that generates a resonance phenomenon when the switching device 22 is turned off. Meanwhile, ON refers to a waveform of turning ON the switching device 22 at the moment when the resonant capacitor turns ratio voltage rises and then falls to zero volt during the turn-off of the switching device 22, so as to reduce the switching loss of the switching device 22.

In one embodiment, the resonant capacitor 23 is connected in parallel with the primary coil 211, and the resonant capacitor 23 forms a resonant tank with the primary coil 211 that contains a capacitor and an inductor. In the case of the switching device 22 being switched off, the resonant capacitor 23 can generate a resonance phenomenon in the resonant tank, so that a boost in instantaneous time is achieved.

In one embodiment, the control circuit 41 may be configured to correct the voltage difference between the ac power supply 300 and the resonant capacitor 23 detected by the synchronization circuit 43 to ensure the normal operation of the driving power supply 100.

The driving circuit 42 may receive a driving signal sent by the control circuit 41, and drive the switching device 22 to be turned on or off.

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

Referring to fig. 1 and 3, in some embodiments, the control coil 212 includes a first terminal C and a second terminal D, the first terminal C is connected to the ground terminal, the second terminal D is connected to the synchronization circuit 43 through the first diode D1 and the third resistor R3, and the output voltage of the control coil 212 is a voltage obtained by rectifying the voltage of the second terminal D through the first diode D1 based on the ground terminal.

In this way, the driving power supply 100 rectifies and outputs the output voltage of the control coil 212 through the first diode D1, so as to ensure that the power supply circuit 30 and the processing circuit 40 work normally.

Specifically, as shown in fig. 3, in one embodiment, the first end C of the control coil 212 is connected to ground, i.e., the first end C of the control coil 212 may serve as a reference point for zero potential.

The control coil 212 and the primary coil 211 have a turns ratio K1/K2, and the output voltage of the control coil 212 is rectified by the first diode D1 through the second end D of the control coil 212 and then output.

The synchronization circuit 43 is connected to the first end C and the second end D of the control coil 212, and is configured to detect an output voltage of the control coil 212, and further obtain a voltage of the resonant capacitor 23 according to a turn relation between the control coil 212 and the primary coil 211.

The first diode D1 may be a rectifier diode to supply power circuit 30 and processing circuit 40 to operate.

The first diode D1 has unidirectional conductivity, i.e. current can only flow from the second terminal D of the control coil 212 through the first diode D1 to the second resistor R2 and the third resistor R3, while current cannot flow from the second resistor R2 through the first diode D1 to the second terminal D of the control coil 212. Therefore, referring to fig. 3, with reference to the first end C of the control coil 212, the voltage of the resonant capacitor 23 is output with a similar waveform of lower power through the control coil 212.

Referring to fig. 1 and 4, in some embodiments, one end of the second resistor R2 is connected between the cathode of the first diode D1 and one end of the third resistor R3, and the other end of the second resistor R2 is connected to the power circuit 30.

In this way, 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.

Specifically, in one embodiment, the output voltage of the control coil 212 is rectified by the first diode D1 and then is respectively supplied to the second resistor R2 and the third resistor R3. 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 delivering the second resistor R2 to the power circuit 30 is reduced to ensure that the heating loss of the second resistor R2 is reduced under the condition that the power circuit 30 operates normally.

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 control coil 212 through the second resistor R2, and the heat loss of the first resistor R1 is reduced.

In one embodiment, referring to fig. 4, in a case where the microwave cooking apparatus starts to operate, the power supply circuit 30 is configured such that the power supply circuit 30 is charged 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 gradually 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 large due to the control manner of soft start, so that the transformer 21 operates. The current of the primary winding 211 of the transformer 21 increases, the resonance voltage generated by the primary winding 211 and the resonance capacitor 23 increases, and the power supply circuit 30 is supplied with power from the control winding 212 through the second resistor R2 to reach a stable operation voltage.

In another embodiment, as shown in fig. 5, fig. 5 is a waveform diagram of the B terminal when the primary coil 211 of the transformer 21 is referenced to the a terminal. In the case where the switching device 22 is turned off, the resonance phenomenon occurs between the resonance capacitor 23 and the primary coil 211, so that the voltage of the resonance capacitor 23 is greater than the voltage of the filter capacitor 12. That is, the voltage waveform of the resonant capacitor 23 is high, above the a terminal, and the voltage waveform of the filter capacitor 12 is low, below the a terminal.

Referring to fig. 1, in some embodiments, the frequency conversion circuit 20 includes a resonant capacitor 23, and two ends of the resonant capacitor 23 are respectively connected to two ends of the primary coil 211. The processing circuit 40 includes a control circuit 41, a drive circuit 42, a protection circuit 44, and a voltage detection circuit 45, the power supply circuit 30 connects the drive circuit 42 and the control circuit 41, the protection circuit 44 connects the control circuit 41 and the control coil 212, and the voltage detection circuit 45 detects the voltage of the ac power supply 300. The protection circuit 44 is configured to detect the voltage of the resonance capacitor 23 through the control coil 212. The control circuit 41 is configured to correct the voltage of the resonant capacitor 23 according to the voltage of the ac power supply 300, and control the driving circuit 42 to drive the switching device 22 to be turned on or off according to the preset voltage protection threshold and the corrected voltage of the resonant capacitor 23; or, the control circuit 41 is configured to correct the preset voltage protection threshold according to the voltage of the ac power supply 300, and control the driving circuit 42 to drive the switching device 22 to be turned on or off according to the corrected preset voltage protection threshold and the voltage of the resonance capacitor 23.

In this way, the control circuit 41 obtains the voltage of the ac power supply 300 and the voltage of the resonance capacitor 23 to correct the preset voltage protection threshold or the voltage of the resonance capacitor 23, thereby achieving the purpose of protecting the switching device 22 and improving the control accuracy of the control circuit 41.

Specifically, in one embodiment, the voltage of the filter capacitor 12 is the voltage rectified by the ac power supply 300 through the first rectifying and filtering circuit 10. The voltage detected by the voltage detection circuit 45 is a voltage obtained by rectifying both ends of the ac power supply 300. That is, the voltage detected by the voltage detection circuit 45 after rectification of the ac power supply 300 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.

The voltage of the filter capacitor 12 is used to correct the preset voltage protection threshold or correct the voltage of the resonant capacitor 23, so that the corrected preset voltage protection threshold or the corrected voltage of the resonant capacitor 23 can reflect the voltage condition of the real ac power supply 300, thereby improving the control accuracy of the control circuit 41.

In one embodiment, the protection circuit 44 may be an overvoltage protection circuit, an undervoltage protection circuit, or other circuits, which are not particularly limited herein.

Referring to fig. 1, 6 and 7, in some embodiments, the control circuit 41 is configured to control the driving circuit 42 to drive the switching device 22 to turn off or to control the switching device to turn off when the voltage of the corrected resonant capacitor 23 reaches the preset voltage protection threshold; the control circuit 41 is configured to control the driving circuit 42 to drive the switching device 22 to turn off when the voltage of the resonant capacitor 23 reaches the corrected preset voltage protection threshold.

In this way, the control circuit 41 compares the corrected preset voltage protection threshold value with the voltage of the resonance capacitor 23, or compares the preset voltage protection threshold value with the corrected voltage of the resonance capacitor 23, so as to realize precise protection of the switching device 22.

Specifically, in one embodiment, referring to fig. 6, the protection circuit 44 may be an overvoltage protection circuit, and the preset voltage protection threshold includes an overvoltage protection threshold V1. That is, when the filter capacitor voltage is high (overvoltage), the control circuit 41 corrects the overvoltage protection threshold V1, specifically, pulls down the overvoltage protection threshold V1 so that the voltage of the filter capacitor 23 can reach the pulled-down overvoltage protection threshold V1, and the control circuit 41 can control the driving circuit 42 to drive the switching device 22 to turn off.

In one embodiment, referring to fig. 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 filter capacitor voltage is low (under voltage), the control circuit 41 corrects the under voltage protection threshold V2 when the voltage of the resonant capacitor 23 is high, 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 later, and the control circuit 41 can control the driving circuit 42 to drive the switching device 22 to turn off.

It is understood that the embodiment of correcting the voltage of the resonant capacitor 23 may refer to the embodiment of correcting the preset voltage protection threshold, and is not specifically described herein.

The protection circuit 44 is configured to detect the voltage of the resonance capacitor 23 through the control coil 212 according to the turns ratio of the control coil 212 to the primary coil 211.

The control circuit 41 can directly acquire the voltage of the filter capacitor 12 through the voltage detection circuit 45, and can acquire the voltage of the resonance capacitor 23 through the protection circuit 44.

In some embodiments, the voltage detection circuit 45 is connected to two ends of the ac power supply 300 through two second diodes D2, respectively.

In this way, the voltage detection circuit 45 rectifies the ac power supply 300 through the two second diodes D2 so as to detect the voltage of the ac power supply 300.

Specifically, in one embodiment, the second diode D2 may be a rectifying diode.

The two second diodes D2 are respectively connected to two ends of the ac power supply 300, and can be used to rectify the ac voltage at two ends of the ac power supply 300 to form a dc voltage.

The voltage detection circuit 45 may obtain the voltage of the rectified ac power supply 300 through the two second diodes D2, and output the voltage to the control circuit 41 for processing.

In some embodiments, the driving power supply 100 includes the second rectifying and smoothing circuit 50, the transformer 21 includes a filament coil 213 and an anode coil 214 at the secondary side, the filament coil 213 is connected to the second rectifying and smoothing circuit 50 and the filaments of the magnetron 200, and the anode coil 214 is connected to the second rectifying and smoothing circuit 50 and the anode of the magnetron.

Thus, the second rectifying and filtering circuit 50 rectifies the voltage amplified by the transformer 21 to supply the magnetron 200 with operation.

Specifically, in one embodiment, the second rectifying and filtering circuit 50 is configured to rectify and filter the voltage boosted by the transformer 21 to obtain a dc voltage, and then supply the dc voltage to the magnetron 200 for operation.

In one embodiment, the filament coil 213 may be used to provide a voltage to the filaments of the magnetron 200 causing the filaments to emit electrons. The anode coil 214 serves to supply a voltage to the anode of the magnetron 200, attract the movement of electrons to strike the anode of the magnetron 200, generate microwaves, and the microwave cooking apparatus heats food by the microwaves generated from the magnetron 200.

The embodiment of the invention also provides microwave cooking equipment. The microwave cooking apparatus includes a magnetron 200 and the driving power supply 100 in any of the above embodiments, the magnetron 200 being connected to the secondary side of the transformer 21.

In the microwave cooking apparatus, the power supply circuit 30 is connected to the first rectifying and filtering 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 charge through the first resistor R1 before the charging voltage of the power supply circuit 30 reaches the first set voltage, and to charge through the second resistor R2 after the charging voltage of the power supply circuit 30 reaches the first set voltage, and the number of turns of the control coil 212 is smaller than that of the primary coil 211, so that the loss of the second resistor R2 in the high-voltage portion of the ac power supply is effectively reduced, the cost problem of the driving power supply 100 is improved, the use of large resistors can be reduced, the space configuration of the driving power supply 100 is more flexible, and the miniaturization of the driving power supply 100 is facilitated.

Specifically, the microwave cooking device includes, but is not limited to, household appliances such as microwave ovens, micro-steaming and baking integrated machines, microwave cookers, and the like.

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. A driving power supply for supplying power to a magnetron, characterized in that the driving power supply comprises a first rectifying and filtering 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 positioned on the primary side of the transformer, the number of turns of the control coil is smaller than that of the primary coil, the first rectification filter circuit is used for being connected with an alternating current power supply, and the primary coil is connected with the first rectification filter circuit;

the processing circuit is connected with the frequency conversion circuit and used for controlling the on-off of the switching device;

the power supply circuit is connected with the first rectifying and filtering circuit through a first resistor, is connected with the control coil through a second resistor, and 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.

2. The driving power supply according to claim 1, wherein the driving power supply satisfies the condition:

k1/k2=1/34 to 2/17, where 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 includes a resonance capacitor, both ends of the resonance capacitor being connected to both ends of the primary coil, respectively;

the processing circuit comprises a control circuit, a driving circuit and a synchronous circuit, wherein the power circuit is connected with the driving circuit and the control circuit, and the synchronous circuit is connected with the control circuit and the control coil;

the synchronous circuit is used for detecting the voltage of the resonant capacitor through the control coil;

the control circuit is used for controlling the driving circuit to drive the switching device to be conducted under the condition that the voltage of the resonant capacitor is reduced to zero volt.

4. A driving power supply according to claim 3, wherein the control coil includes a first terminal and a second terminal, the first terminal is connected to a ground terminal, the second terminal is connected to the synchronization circuit through a first diode and a third resistor, and the output voltage of the control coil is a voltage obtained by rectifying the voltage of the second terminal through the first diode with reference to the ground terminal.

5. The driving power supply according to claim 4, wherein one end of the second resistor is connected between a 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 includes a resonance capacitor, both ends of the resonance capacitor being connected to both ends of the primary coil, respectively;

the processing circuit comprises a control circuit, a driving circuit, a protection circuit and a voltage detection circuit, wherein the power circuit is connected with the driving circuit and the control circuit, the protection circuit is connected with 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 resonant capacitor according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be switched on and off according to a preset voltage protection threshold and the corrected voltage of the resonant capacitor, or is used for correcting the preset voltage protection threshold according to the voltage of the alternating current power supply and controlling the driving circuit to drive the switching device to be switched on and off according to the corrected preset voltage protection threshold and the corrected voltage of the resonant 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 or to control the switching device to be turned off when the corrected voltage of the resonant capacitor reaches the preset voltage protection threshold;

the control circuit is used for controlling the driving circuit to drive the switching device to be turned off under the condition that the voltage of the resonant capacitor reaches the corrected preset voltage protection threshold value.

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, respectively.

9. The driving power supply according to claim 1, wherein the driving power supply includes a second rectifying and smoothing circuit, the transformer includes a filament coil on a secondary side and an anode coil, the filament coil connects the second rectifying and smoothing circuit and filaments of the magnetron, and the anode coil connects the second rectifying and smoothing circuit and anodes of the magnetron.

10. A microwave cooking apparatus comprising a magnetron and the drive power supply of any one of claims 1-9, the magnetron being connected to the secondary side of the transformer.