Variable frequency drive circuit and cooking device

Abstract

The present application provides a variable frequency drive circuit and a cooking device, the variable frequency drive circuit being used in a cooking device including at least two heating elements including a microwave generator, and including a first switch element for adjusting the output power of a power loop, the power loop being connected to a common connection end of the at least two heating elements, a load selection circuit being connected to the power loop and having at least two output ends being used for connection to corresponding heating elements, and a control circuit being connected to the control end of the first switch element and the load selection circuit and being used for determining a target output power and a target heating element of the at least two heating elements based on received control information, and for controlling the first switch element to operate at the target output power and for controlling the load selection circuit to turn on and select the target heating element to operate.

Description

[Technical Field]

[0001] This application claims priority to a Chinese patent application filed with the China Patent Office on November 9, 2022, bearing application number "202211397379.5" and entitled "Variable frequency drive circuit and cooking device," the entire contents of which are incorporated herein by reference.

[0002] This application relates to the technical field of drives, and in particular to variable frequency drive circuits and cooking appliances. [Background technology]

[0003] With the continuous development of the home appliance industry, home appliance products are progressing towards multi-function, integration, integration and high space utilization, for example, power conversion technology is progressing towards high performance and high efficiency variable frequency.

[0004] For example, in the case of existing multi-function cooking devices that combine a microwave oven, a steamer, and an oven, variable frequency technology is used to control the microwave generator, but variable frequency technology is not used for other heating methods. Therefore, when heating using other heating methods, the energy efficiency and heating performance of the cooking device are still relatively low, and cannot meet current energy efficiency needs. Summary of the Invention [Problem to be solved by the invention]

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

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

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

[0008] In view of the above, according to a first aspect of the present application, the present application provides a variable frequency drive circuit for use in a cooking appliance including at least two heating elements including a microwave generator, the variable frequency drive circuit including: a power loop including a first switch element for adjusting the output power of the power loop, the power loop being connected to a common connection end of the at least two heating elements; a load selection circuit connected to the power loop and having at least two output ends used for connection to corresponding heating elements; and a control circuit connected to the control end of the first switch element and the load selection circuit, the control circuit being used for determining a target output power and a target heating element among the at least two heating elements based on received control information, and for controlling the first switch element to operate at the target output power and for controlling the load selection circuit to select the target heating element to be powered on and operate.

[0009] The technical solution of this application proposes a variable frequency drive circuit including a power loop, a load selection circuit, and a control circuit. Here, the power loop can realize power regulation, and when the load selection circuit is connected to the power loop, the load selection circuit is used to realize load selection. Based on this, the variable frequency control applied to the microwave generator can be applied to other heating elements. In this process, the other heating elements can also achieve variable frequency control in the same way as the microwave generator. This solves the problem of related technical solutions in that when heating elements other than the microwave generator are used for heating, their energy efficiency and heating performance are still relatively low and cannot meet current energy efficiency needs.

[0010] Furthermore, in the above technical solution of the present application, the same power loop can be reused by different heating elements, and while other heating elements other than the microwave generator can achieve variable frequency control, there is no need to add additional circuits to achieve variable frequency, which reduces the cost required to achieve variable frequency control of other heating elements.

[0011] In the above technical solutions, the control information can be understood as a control command received by the cooking appliance, for example, the control information may be microwave function, 300 watts, baking function, 1000 watts, or steaming function, 180°C, etc.

[0012] In one technical solution, a first switch element disposed in the power loop can be controlled by a control circuit to adjust a conduction time within a unit period, where the longer the conduction time within the unit period, the greater the output power of the power loop; conversely, the shorter the conduction time within the unit period, the smaller the output power of the power loop.

[0013] In one technical solution, it can be understood that the power loop is a circuit for adjusting the power supplied to the heating elements, and the load selection circuit is used to select the heating elements currently in operation within the cooking appliance, and the two can be used in coordination to realize variable frequency control of different heating elements.

[0014] In one technical solution, the first switch element is an insulated gate bipolar transistor (IGBT), which is a composite fully controlled voltage-driven power semiconductor device composed of a bipolar junction transistor (BJT) and an insulated gate field effect transistor (MOS), and has the advantages of both the high input impedance of a metal-oxide-semiconductor field-effect transistor (MOSFET) and the low conduction voltage drop of a giant transistor (GTR).

[0015] In addition, the variable frequency drive circuit proposed in this application also has the following additional technical features:

[0016] In the above technical solution, the variable frequency drive circuit further includes a communication circuit connected to the control circuit, used for receiving control information and transmitting the control information to the control circuit, where the control information is a pulse width modulation signal, and the frequency of the pulse width modulation signal corresponds one-to-one to the frequency of the heating element.

[0017] In this technical solution, a communication circuit is provided to establish data communication between the communication circuit and the computer board, so that when the computer board receives the functions and operating power selected by the user, i.e., the above-mentioned control information, it transfers the control information to the control circuit, and the control circuit controls the power loop and the load selection circuit, thereby realizing the variable frequency driving and control of different heating elements.

[0018] Here, since different heating elements use different frequencies of pulse-width modulated signals, the communication circuit can be used to realize the selection of different heating elements. This process reduces the manufacturing cost of the cooking appliance because multiple heating elements reuse the same communication circuit.

[0019] The load selection circuit has a first input terminal, and the power loop has a second input terminal and a third input terminal and a first output terminal and a second output terminal, the second input terminal and the third input terminal are used for connection to an AC terminal block, the first output terminal is connected to the first input terminal, the second output terminal is connected to the first terminal of the first switch member, and the second terminal of the first switch member is connected to the common connection terminal.

[0020] In this technical solution, specifically, the power loop is limited to include a rectifier circuit, where the rectifier circuit is provided to convert AC supplied from the AC terminal into DC, in which case the above variable frequency drive circuit can be applied to AC power supply scenarios, thus expanding the application scenarios of the variable frequency drive circuit.

[0021] Here, the second output terminal of the rectifier circuit is connected to the first input terminal of the load selection circuit, and the second output terminal of the rectifier circuit is connected to the common connection terminal via the first switch member, whereby the first switch member can control the supply of the direct current output by the rectifier circuit to the load selection circuit, and further adjust the power input to the load selection circuit.

[0022] In the above technical solution, the load selection circuit can be understood as a single-pole multi-throw switch, the movable contact of which is connected to the second output end of the rectifier circuit, and each static contact of the single-pole multi-throw switch is connected to a heating element, so that after the movable contact of the single-pole multi-throw switch selects the static contact to connect to, power is supplied to the heating element corresponding to the static contact.

[0023] In the above technical solution, the rectifier circuit can be understood as a rectifier. In the technical solution of the present application, the rectifier is a bridge rectifier. Specifically, the bridge rectifier is obtained by connecting four rectifier silicon chips in a bridge manner and packaging them with insulating plastic. In the high-power bridge rectifier, the outside of the insulating layer is covered with a zinc metal shell to improve heat dissipation.

[0024] In any of the above technical solutions, the power loop further includes a filter circuit, and the filter circuit includes a first resistor having a first end connected to the first output end and a second end connected to the second output end, and a capacitor connected in parallel to the first resistor.

[0025] In this technical solution, a filter circuit is provided to filter out high-frequency voltage fluctuations in the DC output from the rectifier circuit, allowing the filtered DC to stably supply power to the load selection circuit, thereby reducing power supply fluctuations that could cause abnormal operation of the heating element.

[0026] Specifically, the capacitor's properties prevent the voltage across it from changing too quickly. Therefore, the capacitor has the property of blocking voltage changes. This makes the DC current after filtering smoother, reducing voltage fluctuations in the power loop.

[0027] In any of the above technical solutions, the power loop further includes a reactor located between the first end of the first resistor and the first output end.

[0028] In this technical solution, a reactor is provided, so that the reactor and a filter circuit can be used in combination to limit the high-order harmonics of the power loop, thereby improving the power loss of the power loop.

[0029] In one technical solution, the reactor includes one coil.

[0030] In any of the above technical solutions, the power loop further includes a detection circuit whose input terminal is connected to the second input terminal and the third input terminal, and whose output terminal is connected to the control circuit, and when a surge fluctuation exists between the second input terminal and the third input terminal, the control circuit controls the power loop to stop operating.

[0031] In this technical solution, a detection circuit is provided, which is used to read the magnitude of the power supply voltage entering the rectifier circuit, and if the voltage entering the rectifier circuit is too low or too high, the power loop is controlled to stop operation, thereby reducing the possibility of damage to the variable frequency drive circuit caused by power supply abnormalities.

[0032] In any of the above technical solutions, the variable frequency driving circuit further includes a driving circuit located between the control circuit and the control end of the first switch member, and used to drive and operate the first switch member.

[0033] In the above technical solution, the first switch member requires a relatively large current or voltage to be driven, but when the control circuit controls the first switch member, the output voltage or current is limited, making it difficult to control the first switch member. Based on this, the technical solution of the present application provides a drive circuit between the control circuit and the first switch member, and the control circuit uses the drive circuit to drive and control the first switch member, thereby indirectly improving the driving capability of the control circuit.

[0034] In any of the above technical solutions, the load selection circuit includes a multi-way switch, an input terminal of the multi-way switch is connected to the power loop, and at least two output terminals of the multi-way switch are used to connect to corresponding heating elements.

[0035] In any of the above technical solutions, when the heating element connected to the variable frequency control circuit includes a first heating element and a second heating element, the load selection circuit includes a relay having one movable contact and two stationary contacts, the movable contact being connected to the first output end, one of the two stationary contacts being connected to the first heating element and the other of the two stationary contacts being connected to the second heating element, and a second switch element having a first end connected to the first power source by the relay and a second end grounded, wherein when the second switch element is conductive, the relay is powered on and closed, the movable contact is connected to the first stationary contact, and the first heating element is powered on and operates, and when the second switch element is cut off, the relay loses power and opens, the movable contact is connected to the second stationary contact, and the second heating element is powered on and operates.

[0036] The technical solution specifically shows the detailed topology structure of the load selection circuit, where the relay is an electrical control device, which is an electrical equipment that causes a predetermined step change in the controlled variable in the electrical output circuit when the change in the input quantity (excitation quantity) meets a predetermined requirement. It is actually an "automatic switch" that uses a small current to control the operation of a large current. Based on this, the small current can be used to control the operation of a large current. Since the small current and the large current are usually in separate loops, there is an isolation effect between them, which improves the safety of the variable frequency drive circuit.

[0037] In one technical solution, a second switch member is provided, so that the second switch member can be used to control a small current.

[0038] In the above technical solution, the second switch element is a triode, and there is no need to provide a driving circuit to drive and control the triode, and the triode is directly connected to the control circuit, which reduces the complexity of the entire circuit and eases the design difficulty.

[0039] According to a second aspect of the present application, there is provided a cooking device comprising at least two heating elements including a microwave generator and a variable frequency drive circuit according to any one of the above claims connected to the variable frequency drive circuit.

[0040] The technical solution of this application proposes a cooking device that includes the above-mentioned variable frequency drive circuit, which includes a power loop, a load selection circuit, and a control circuit. Here, the power loop can achieve power regulation, and when the load selection circuit is connected to the power loop, the load selection circuit is used to achieve load selection. Based on this, the variable frequency control applied to the microwave generator can be applied to other heating elements. In this process, the other heating elements can also achieve variable frequency control in the same way as the microwave generator. This solves the problem of related technical solutions, where when heating elements other than the microwave generator are used for heating, the energy efficiency and heating performance are still relatively low and cannot meet current energy efficiency needs.

[0041] Furthermore, the above technical solution of the present application realizes reuse of the same power loop by different heating elements, and while other heating elements other than the microwave generator realize variable frequency control, there is no need to add additional circuits to realize variable frequency, which reduces the cost required to realize variable frequency control of other heating elements.

[0042] In the above technical solutions, the control information can be understood as a control command received by the cooking appliance, for example, the control information may be microwave function, 300 watts, baking function, 1000 watts, or steaming function, 180°C, etc.

[0043] In one technical solution, a first switch element disposed in the power loop can be controlled by a control circuit to adjust a conduction time within a unit cycle, where the longer the conduction time within the unit cycle, the greater the output power of the power loop; conversely, the shorter the conduction time within the unit cycle, the smaller the output power of the power loop.

[0044] In one technical solution, it can be understood that the power loop is a circuit for adjusting the power supplied to the heating elements, and the load selection circuit is used to select the heating elements currently in operation within the cooking appliance, and the two can be used in coordination to realize variable frequency control of different heating elements.

[0045] In the above technical solution, the cooking device further includes a computer board; and a third switch member connected to the computer board and the power loop, which is conductive to supply power to the power loop when the computer board receives a start-up signal of the cooking device.

[0046] In this technical solution, the computer board can be understood as a control panel of the cooking appliance, and is a member for interaction between the user and the cooking appliance. Specifically, the computer board has a control panel, and the user can send control information to the variable frequency drive circuit through the control panel to control and operate the variable frequency drive circuit.

[0047] In the above technical solution, the provision of a third switch member allows the third switch member to be used to control whether to supply power to the variable frequency drive circuit. During this process, the cooking appliance can control the conduction and cut-off of the third switch member according to actual usage needs. Specifically, when the heating element of the cooking appliance does not need to be operated, the third switch member is controlled to be cut off to cut off power to the variable frequency drive circuit. When heating by the heating element of the cooking appliance is required, the third switch member is controlled to be conductive to supply power to the variable frequency drive circuit. When power is supplied to the variable frequency drive circuit, the power loop, load selection circuit, control circuit, etc. of the variable frequency drive circuit are powered on and operate. The provision of the third switch member improves the safety of the cooking appliance.

[0048] In the above technical solution, the problem of excessive power consumption of the cooking appliance due to continuous power supply to the variable frequency drive circuit can be avoided.

[0049] In any of the above technical solutions, the communication circuit of the variable frequency drive circuit is connected to a computer board, which is used to transmit control information to the communication circuit.

[0050] In any of the above technical solutions, the at least two heating elements further include a steam generator and / or a heating tube.

[0051] In this technical solution, the possible selection scheme of the heating elements is limited to meet the usage requirements of the cooking appliance in actual use.

[0052] In any of the above technical solutions, the microwave generator includes a magnetron, a step-up transformer having a first primary coil connected to a power loop and a first secondary coil connected to the magnetron, and a voltage doubler circuit connected to a second secondary coil of the step-up transformer and the magnetron.

[0053] In the technical solution, the first secondary coil has a first connection end and a second connection end, the magnetron has a first connection end, a second connection end and a third connection end, where the third connection end of the magnetron is used for grounding, the first connection end of the first secondary coil is connected to the first connection end of the magnetron, the second connection end of the first secondary coil is connected to the second connection end of the magnetron, the second secondary coil has a first connection end and a second connection end, and the voltage doubler circuit has a first connection end, a second connection end and a third connection end. , and a fourth connection end, wherein the first connection end of the second secondary coil is connected to the first connection end of the voltage doubler circuit, wherein the second connection end of the second secondary coil is connected to the second connection end of the voltage doubler circuit, and the fourth connection end of the voltage doubler circuit is connected to the third connection end of the magnetron, i.e., the fourth connection end of the voltage doubler circuit is grounded together with the third connection end of the magnetron, and the third connection end of the voltage doubler circuit is connected to the first connection end of the first secondary coil, thereby improving the voltage value at the first connection end of the magnetron.

[0054] In one technical solution, the voltage doubler circuit includes a first diode, a second diode, a first capacitor, and a second capacitor, wherein the anode of the first diode is connected to the cathode of the second diode and the first connection end of the second secondary coil; the cathode of the first diode is connected to the first end of the first capacitor and the third connection end of the magnetron; the second end of the first capacitor is connected to the first end of the second capacitor; the second end of the second capacitor is connected to the first connection end of the first secondary coil; the anode of the second diode is connected to the first connection end of the first secondary coil; and the second connection end of the second secondary coil is connected to the second end of the first capacitor.

[0055] In one possible design, the first connection end of the magnetron, the second connection end of the magnetron, and the third connection end of the magnetron are interface structures, thereby facilitating the connection between the voltage doubler circuit and the step-up transformer.

[0056] In any of the above technical solutions, the cooking appliance further includes a power supply circuit connected to the second primary coil of the step-up transformer and used to output a power supply voltage with a preset voltage value. In this technical solution, the power supply circuit is combined with the step-up transformer to obtain power and output a supply voltage with the preset voltage to power the control circuit, communication circuit, and load selection circuit. This process eliminates the need for separate power supplies for the control circuit, communication circuit, and load selection circuit, which is advantageous in reducing the number of power supplies provided in the cooking appliance and thereby easing the design difficulty of the cooking appliance.

[0057] In one technical solution, the power supply circuit is also connected to the first input terminal and the second input terminal of the rectifier circuit, so that the power supply circuit obtains power from the first input terminal and the second input terminal of the rectifier circuit to power the control circuit, the communication circuit, and the load selection circuit, and obtains power from the step-up transformer based on the second primary coil after the control circuit, the communication circuit, and the load selection circuit are powered on and operating.

[0058] In any of the above technical solutions, one end of the voltage doubler circuit is connected to a ground point, and the cooking apparatus further includes a sampling resistor located between the one end of the voltage doubler circuit and the ground point, with a first end connected to the one end of the voltage doubler circuit and a second end connected to the ground point, and a first end of the sampling resistor is connected to a computer board and used to feed back the working state of the microwave generator.

[0059] In this technical solution, a sampling resistor is provided to realize feedback of the current operating state of the microwave generator, so that the control circuit obtains the current operating state of the microwave generator, and then detects the current operating state of the microwave generator. If the control circuit detects that the current operating state of the microwave generator is abnormal, it controls to stop the power loop, thus reducing the possibility of failure of the cooking appliance.

[0060] Furthermore, if it detects that the current operating status of the microwave generator is abnormal, a message that the microwave generator is faulty will be sent to the computer board through the communication circuit, and the computer board will cut off the third switch, thereby reducing the possibility of failure of the cooking appliance and improving the reliability of the operation of the cooking appliance.

[0061] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the present application.

[0062] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following detailed description of the embodiments with reference to the drawings. [Brief explanation of the drawings]

[0063] [Figure 1] 1 shows a topology diagram of an example of a variable frequency drive circuit according to an embodiment of the present application. [Figure 2] 1 shows another topology schematic diagram of a variable frequency drive circuit in accordance with an embodiment of the present application; [Figure 3] 1 illustrates yet another topology schematic diagram of a variable frequency drive circuit in accordance with an embodiment of the present application. [Figure 4] 1 shows a further topology schematic of a variable frequency drive circuit in accordance with an embodiment of the present application; [Figure 5] 1 shows a topology diagram of a cooking device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0064] In order to more clearly understand the above aspects, features and advantages of the present application, the present application will be described in more detail below with reference to the drawings and specific embodiments. Note that the examples and features in the examples of the present application may be combined with each other unless they are inconsistent.

[0065] In the following description, many specific details are set forth to facilitate a thorough understanding of the present application; however, the present application may be implemented in other ways than those described herein, and the scope of protection of the present application is not limited by the specific examples disclosed below.

[0066] As shown in Figures 1, 2, 3, 4, and 5, the variable frequency drive circuit of the present application is used in a cooking device including at least two heating elements including a microwave generator, and includes: a power loop 102 including a first switch member Q1 for adjusting the output power of the power loop 102, the power loop 102 being connected to a common connection end of the at least two heating elements; a load selection circuit 104 connected to the power loop 102 and having at least two output ends used for connection to corresponding heating elements; and a control circuit 106 connected to the control end of the first switch member Q1 and the load selection circuit 104, for determining a target output power and a target heating element among the at least two heating elements based on received control information, and for controlling the first switch member Q1 to operate at the target output power, and for controlling the load selection circuit 104 to turn on and select the target heating element to operate.

[0067] The embodiment of the present application proposes a variable frequency drive circuit 110 including a power loop 102, a load selection circuit 104, and a control circuit 106. Here, the power loop 102 can realize power regulation. When the load selection circuit 104 is connected to the power loop 102, the load selection circuit 104 is used to realize load selection. Based on this, the variable frequency control applied to the microwave generator can be applied to other heating elements. In this process, the other heating elements can also achieve variable frequency control in the same way as the microwave generator. This solves the problem of related technical solutions that, when heating elements other than microwave generators are used for heating, the energy efficiency and heating performance are still relatively low and cannot meet current energy efficiency needs.

[0068] Furthermore, in the above-described embodiment of the present application, the reuse of the same power loop 102 by different heating elements is realized, and while other heating elements other than the microwave generator realize variable frequency control, there is no need to add additional circuitry to realize variable frequency, thereby reducing the cost required to realize variable frequency control of other heating elements.

[0069] In the above example, the control information can be understood as a control command received by the cooking appliance, for example, the control information may be microwave function, 300 watts, bake function, 1000 watts, or steam function, 180°C, etc.

[0070] In one embodiment, the first switch element Q1 disposed in the power loop 102 is controlled by the control circuit 106 to adjust the conduction time within a unit period. The longer the conduction time within a unit period, the greater the output power of the power loop 102. Conversely, the shorter the conduction time within a unit period, the smaller the output power of the power loop 102.

[0071] In one embodiment, it can be understood that the power loop 102 is a circuit for adjusting the power supplied to the heating elements, and the load selection circuit 104 is used to select the heating element currently in operation within the cooking appliance. These two can be used in concert to achieve variable frequency control of different heating elements.

[0072] In one embodiment, the heating element includes a heating element connection interface 114 and a load selection circuit 104 .

[0073] In one embodiment, the first switch element Q1 is an insulated gate bipolar transistor (IGBT), which is a composite fully controlled voltage-driven power semiconductor device consisting of a bipolar junction transistor (BJT) and an insulated gate field effect transistor (MOS), and has the advantages of both the high input impedance of a metal-oxide-semiconductor field-effect transistor (MOSFET) and the low conduction voltage drop of a giant transistor (GTR).

[0074] In some embodiments of the present application, the variable frequency drive circuit further includes a communication circuit 112 connected to the control circuit 106 and used to receive control information and transmit the control information to the control circuit 106, where the control information is a pulse width modulated signal, and the frequency of the pulse width modulated signal corresponds one-to-one to the heating element.

[0075] In this technical solution, a communication circuit 112 is provided to establish data communication between the communication circuit 112 and the computer board 202, and when the computer board 202 receives the functions and operating power selected by the user, i.e., the above-mentioned control information, it transfers the control information to the control circuit 106, and the control circuit 106 controls the power loop 102 and the load selection circuit 104 to realize the variable frequency driving and control of different heating elements.

[0076] Here, since different heating elements use different frequencies of pulse-width modulated signals, the selection of different heating elements can be achieved using the communication circuit 112. This process reduces the manufacturing cost of the cooking appliance because multiple heating elements reuse the same communication circuit.

[0077] In the above embodiment, the load selection circuit 104 has a first input terminal, and the power loop 102 has a second input terminal and a third input terminal and a first output terminal and a second output terminal, the second input terminal and the third input terminal are used for connecting to an AC terminal block, the first output terminal is connected to the first input terminal, the second output terminal is connected to the first terminal of the first switch member Q1, and the second terminal of the first switch member Q1 is connected to the common connection terminal.

[0078] In this embodiment, specifically, the power loop 102 is limited to include a rectifier circuit 1022, where the rectifier circuit 1022 is provided to convert AC supplied from the AC terminals into DC, in which case the variable frequency drive circuit can be applied to AC power supply scenarios, thus broadening the application scenarios of the variable frequency drive circuit 110.

[0079] Here, the second output terminal of the rectifier circuit 1022 is connected to the first input terminal of the load selection circuit 104, and the second output terminal of the rectifier circuit 1022 is connected to the common connection terminal via the first switch element Q1, so that the first switch element Q1 can control the power supply to the load selection circuit 104 by the rectifier circuit 1022 and further adjust the power input to the load selection circuit 104.

[0080] In the above embodiment, the load selection circuit 104 can be understood as a single-pole multi-throw switch, the movable contact of which is connected to the second output terminal of the rectifier circuit 1022, and each stationary contact of which is connected to a heating element, so that after the movable contact of the single-pole multi-throw switch selects the stationary contact to be connected, power is supplied to the heating element corresponding to the stationary contact.

[0081] In the above embodiment, the rectifier circuit 1022 can be understood as a rectifier. In the embodiment of the present application, the rectifier is a bridge rectifier. Specifically, the bridge rectifier is obtained by connecting four rectifier silicon chips in a bridge configuration and packaging them with insulating plastic. For high-power bridge rectifiers, the outside of the insulating layer is covered with a zinc metal shell to improve heat dissipation.

[0082] In any of the above embodiments, the power loop 102 further includes a filter circuit 1024, which includes a first resistor R1 having a first end connected to the first output end and a second end connected to the second output end, and a capacitor C connected in parallel to the first resistor R1.

[0083] In this embodiment, a filter circuit is provided to filter out high-frequency voltage fluctuations in the DC output from the rectifier circuit 1022, allowing the filtered DC to be stably supplied to the load selection circuit 104, thereby reducing fluctuations in power supply that could cause abnormal operation of the heating element.

[0084] Specifically, the characteristics of capacitor C prevent the voltage across the capacitor from changing suddenly. Therefore, the capacitor has the property of blocking voltage changes. This results in a smoother DC signal after filtering, reducing voltage fluctuations in the power loop 102.

[0085] In any of the above embodiments, the power loop 102 further includes a reactor H located between the first end of the first resistor R1 and the first output end.

[0086] In this embodiment, the reactor H is provided so that the reactor H and the filter circuit 1024 can be used in combination to limit the high-order harmonics of the power loop 102, thereby improving the power loss of the power loop 102.

[0087] In one embodiment, reactor H includes one coil.

[0088] In any of the above embodiments, the power loop 102 further includes a detection circuit 108 having an input terminal connected to the second input terminal and the third input terminal and an output terminal connected to the control circuit 106, and when a surge fluctuation exists between the second input terminal and the third input terminal, the control circuit 106 controls the power loop 102 to stop operating.

[0089] In this embodiment, the detection circuit 108 is provided to read the magnitude of the power supply voltage entering the rectifier circuit 1022, and if the voltage entering the rectifier circuit 1022 is too low or too high, the power loop 102 is controlled to stop operation, thereby reducing the possibility of damage to the variable frequency drive circuit 110 due to a power supply abnormality.

[0090] In any of the above embodiments, the variable frequency drive circuit further includes a drive circuit 110 located between the control circuit 106 and the control end of the first switch member Q1, and used to drive and operate the first switch member Q1.

[0091] In the above embodiment, the first switch element Q1 requires a relatively large current or voltage to be driven, but when the control circuit 106 controls the first switch element Q1, the output voltage or current is limited, making it difficult to control the first switch element Q1. Based on this, in the embodiment of the present application, a drive circuit 110 is provided between the control circuit 106 and the first switch element Q1, and the control circuit 106 uses the drive circuit 110 to drive and control the first switch element Q1. The provision of the drive circuit 110 indirectly improves the driving capability of the control circuit 106.

[0092] In any of the above embodiments, the load selection circuit includes a multi-way switch, an input terminal of the multi-way switch is connected to the power loop, and at least two outputs of the multi-way switch are used for connection to corresponding heating elements.

[0093] The control circuit 106 selects and activates the target heating element via outputs S0 and S1.

[0094] Specifically, as an example, when S0 is 0 and S1 is 1, the target heating element is a microwave generator; when S0 is 1 and S1 is 0, the target heating element is a first heating element, for example, a steam generator; and when S0 is 1 and S1 is 1, the target heating element is a second heating element, for example, a heating tube.

[0095] In any of the above embodiments, when the heating elements connected to the variable frequency control circuit 106 include a first heating element and a second heating element, the load selection circuit 104 includes a relay having one movable contact and two stationary contacts, the movable contact being connected to the first output terminal, one of the two stationary contacts being connected to the first heating element, and the other of the two stationary contacts being connected to the second heating element; and a second switch element having a first end connected to the first power source by the relay and a second end grounded. When the second switch element is conductive, the relay is powered on and closed, the movable contact is connected to the first stationary contact, and the first heating element is powered on and operates; when the second switch element is cut off, the relay is powered off and opened, the movable contact is connected to the second stationary contact, and the second heating element is powered on and operates.

[0096] Here, one of the first heating element and the second heating element is a microwave generator.

[0097] This embodiment specifically illustrates the detailed topology of the load selection circuit 104. A relay is an electrical control device that causes a predetermined step change in a controlled variable in an electrical output circuit when a change in an input quantity (excitation quantity) meets a predetermined requirement. It is actually an "automatic switch" that uses a small current to control the operation of a large current. Based on this, the small current can be used to control the operation of a large current. Since the small current and the large current are usually in separate loops, an isolation effect is created between them, improving the safety of the variable frequency drive circuit 110.

[0098] In one embodiment, a second switch member is provided so that the second switch member can be used to control a small current.

[0099] In the above embodiment, the second switch member is a triode, and there is no need to provide a drive circuit to drive and control the triode; the triode is directly connected to the control circuit, which reduces the complexity of the entire circuit and eases the difficulty of design.

[0100] In one embodiment, the present application provides a cooking device comprising at least two heating elements including microwave generators and a variable frequency drive circuit 110 as described in any one of the above claims, wherein the at least two heating elements are connected to the variable frequency drive circuit 110.

[0101] The embodiment of the present application proposes a cooking device, and since the cooking device includes the above-mentioned variable frequency drive circuit 110, it has all the beneficial technical effects of the above-mentioned variable frequency drive circuit 110, so it will not be described in detail here.

[0102] In the above embodiment, the cooking apparatus further includes a computer board 202 and a third switch member Q3 connected to the computer board 202 and the power loop 102, and conducting to supply power to the power loop 102 when the computer board 202 receives a start-up signal of the cooking apparatus.

[0103] In this embodiment, the computer board 202 can be understood as a control panel of the cooking appliance, and is a member for interaction between the user and the cooking appliance. Specifically, the computer board 202 has a control panel through which the user can send control information to the variable frequency drive circuit 110 to control and operate the variable frequency drive circuit 110.

[0104] In the above embodiment, the third switch element Q3 is provided to control whether to supply power to the variable frequency drive circuit 110. During this process, the cooking appliance can control the conduction and cutoff of the third switch element Q3 according to actual usage needs. Specifically, when the heating element of the cooking appliance does not need to be operated, the third switch element Q3 is controlled to be cut off to cut off power to the variable frequency drive circuit 110. When heating by the heating element of the cooking appliance is required, the third switch element Q3 is controlled to be conductive to supply power to the variable frequency drive circuit 110. When power is supplied to the variable frequency drive circuit 110, the power loop 102, load selection circuit 104, control circuit 106, etc. of the variable frequency drive circuit 110 are powered on and operate. The provision of the third switch element Q3 improves the safety of the cooking appliance.

[0105] In the above embodiment, the problem of excessive power consumption of the cooking appliance due to continuous power supply to the variable frequency drive circuit 110 can be avoided.

[0106] In any of the above embodiments, the communication circuit 112 of the variable frequency drive circuit 110 is connected to the computer board 202 , which is used to transmit control information to the communication circuit 112 .

[0107] In any of the above embodiments, the at least two heating elements further include a steam generator and / or a heating tube.

[0108] In this embodiment, the possible selection scheme of the heating elements is limited to meet the usage requirements of the cooking appliance in actual use.

[0109] In any of the above embodiments, the microwave generator includes a magnetron, a step-up transformer having a first primary coil connected to the power loop 102 and a first secondary coil connected to the magnetron, and a voltage doubler circuit connected to a second secondary coil of the step-up transformer and to the magnetron.

[0110] In this embodiment, the first secondary coil has a first connection end and a second connection end, the magnetron has a first connection end, a second connection end, and a third connection end, where the third connection end of the magnetron is used for grounding, the first connection end of the first secondary coil is connected to the first connection end of the magnetron, the second connection end of the first secondary coil is connected to the second connection end of the magnetron, the second secondary coil has a first connection end and a second connection end, the voltage doubler circuit has a first connection end, a second connection end, a third connection end, and and a fourth connection end, wherein the first connection end of the second secondary coil is connected to the first connection end of the voltage doubler circuit, the second connection end of the second secondary coil is connected to the second connection end of the voltage doubler circuit, and the fourth connection end of the voltage doubler circuit is connected to the third connection end of the magnetron, i.e., the fourth connection end of the voltage doubler circuit is grounded together with the third connection end of the magnetron, and the third connection end of the voltage doubler circuit is connected to the first connection end of the first secondary coil, thereby improving the voltage value at the first connection end of the magnetron.

[0111] In one embodiment, the voltage doubler circuit includes a first diode, a second diode, a first capacitor, and a second capacitor, wherein the anode of the first diode is connected to the cathode of the second diode and the first connection end of the second secondary coil, the cathode of the first diode is connected to the first end of the first capacitor and the third connection end of the magnetron, the second end of the first capacitor is connected to the first end of the second capacitor, the second end of the second capacitor is connected to the first connection end of the first secondary coil, the anode of the second diode is connected to the first connection end of the first secondary coil, and the second connection end of the second secondary coil is connected to the second end of the first capacitor.

[0112] In one possible design, the first connection end of the magnetron, the second connection end of the magnetron, and the third connection end of the magnetron are interface structures, which facilitates connection between the voltage doubler circuit and the step-up transformer.

[0113] In any of the above embodiments, the cooking appliance further includes a power supply circuit 204 connected to the second primary coil of the step-up transformer, for outputting a power supply voltage having a preset voltage value.

[0114] In this embodiment, the power supply circuit 204 is provided to combine the power supply circuit 204 to obtain power from the step-up transformer and output a supply voltage of a preset voltage to power the control circuit 106, the communication circuit 112, and the load selection circuit 104. In this process, there is no need to provide separate power supplies for the control circuit 106, the communication circuit 112, and the load selection circuit 104, which is advantageous in reducing the number of power supplies provided in the cooking appliance, thereby easing the design difficulty of the cooking appliance. Illustratively, the power supply circuit 204 is connected to AC via AC IN.

[0115] In one embodiment, the power supply circuit 204 is also connected to the first input terminal and the second input terminal of the rectifier circuit 1022, so that the power supply circuit 204 obtains power from the first input terminal and the second input terminal of the rectifier circuit 1022 to power the control circuit 106, the communication circuit 112, and the load selection circuit 104, and obtains power from the step-up transformer based on the second primary coil after the control circuit 106, the communication circuit 112, and the load selection circuit 104 are powered on and operating.

[0116] In any of the above embodiments, one end of the voltage doubler circuit is connected to ground, and the cooking apparatus further includes a sampling resistor 206 located between the one end of the voltage doubler circuit and ground, with a first end connected to the one end of the voltage doubler circuit and a second end connected to ground, and a first end of the sampling resistor 206 connected to the computer board 202, for feeding back the operating state of the microwave generator.

[0117] In this embodiment, the sampling resistor 206 is provided to realize feedback of the current operating state of the microwave generator, so that the control circuit 106 can obtain the current operating state of the microwave generator, and then detect the current operating state of the microwave generator. If the control circuit 106 detects that the current operating state of the microwave generator is abnormal, it will control to stop the power loop 102, thus reducing the possibility of failure of the cooking appliance.

[0118] Furthermore, if it is detected that the current operating status of the microwave generator is abnormal, a message that the microwave generator is faulty will be sent to the computer board 202 via the communication circuit 112, and the computer board 202 will turn off the third switch Q3, thereby reducing the possibility of failure of the cooking appliance and improving the reliability of the operation of the cooking appliance.

[0119] In one embodiment, the third switch element Q3 is a relay. When the user selects the microwave function, the relay on the computer board is closed to power the variable frequency integrated circuit (i.e., the aforementioned variable frequency drive circuit). The computer board sends a pulse width modulation (PWM) signal to the variable frequency integrated circuit in a frequency range of 350 Hz to 2000 Hz, corresponding to the input power in the microwave function. At this time, the variable frequency integrated circuit enters the microwave function in response to the signal. When the user switches the mode to the grill mode, the computer board sends a PWM signal to the variable frequency integrated circuit in a frequency range of 2500 Hz to 4500 Hz, corresponding to the input power in the grill mode of 0 W to 2000 W. The variable frequency integrated circuit switches to the grill operating mode and controls the multi-way switch to switch the load from the original switch transformer to the heating tube.

[0120] Specifically, the detection circuit 108 in FIG. 1 is connected to the control circuit 106 via SUREG and Vin, CS, PS, and OC_C of the control circuit 106 are grounded via capacitors, connected to the drive circuit 110 via DRIVER, reset via RESET, connected to the communication circuit 112 via the PWM pin, connected to the power supply circuit 204 via SYNC_P and VOP, and error output via ERROR. Clock and digital input / output are realized based on DIO and CLK, Vg connects the drive circuit 110 to the first switch element Q1, VDD and VSS are power supply connection terminals of the chip, GND represents ground, and the load selection circuit 104 realizes enable control via EN.

[0121] The terms "first" and "second" features in the specification and claims of this application may explicitly or implicitly include one or more of those features. In this description, unless otherwise specified, "plurality" means two or more. Also, in the specification and claims, "and / or" refers to at least one of the items before and after it, and the symbol " / " generally indicates an "or" relationship between the related items before and after it.

[0122] In the description of this application, unless otherwise clearly specified or limited, the terms "attach," "couple," and "connect" should be understood in a broad sense, and may mean, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical structural connection, an electrical connection, a direct connection between the two, an indirect connection between the two via an intermediate medium, or internal communication between the two elements. The specific meanings of the above terms in this application can be specifically understood by those skilled in the art.

[0123] In the claims, specification, and drawings of this application, the term "plurality" means two or more unless expressly limited otherwise. The orientations or positional relationships indicated by terms such as "upper," "lower," etc., are based on the orientations or positional relationships shown in the drawings and are intended merely to facilitate and simplify the description of this application. They do not indicate or imply that the devices or elements shown must have a specific orientation, be configured, or operate in a specific orientation. Therefore, it is understood that these descriptions should not be construed as limiting this application. The terms "connect," "attach," "fixed," etc., should be understood broadly. For example, "connect" may refer to multiple objects being fixedly connected, detachably connected, or integrally connected, or multiple objects being directly connected, or multiple objects being indirectly connected via an intermediate medium. The specific meanings of the above data in this application are readily apparent to those skilled in the art.

[0124] In the claims, specification, and drawings of this application, the terms "one embodiment," "some embodiments," "specific embodiment," etc., mean that a specific feature, structure, material, or characteristic described with reference to that embodiment or example is included in at least one embodiment or example of this application. In the claims, specification, and drawings of this application, general references to such terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0125] The above is only a preferred embodiment of the present application, and does not limit the present application. Those skilled in the art can make various modifications and variations to the present application. Any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and principles of the present application shall fall within the scope of protection of the present application. [Explanation of symbols]

[0126] The correspondence between the reference numerals and the names of the components in FIGS. 1 to 5 is as follows: 102 Power Loop 104 Load selection circuit Q1 First switch member 106 Control circuit 1022 Rectifier circuit 1024 filter circuit R1 1st resistor C capacitor H reactor 108 Detection circuit 110 Drive circuit 112 Communication Circuit 114 Heating element connection interface 202 Computer Board Q3 Third switch member 204 Power Supply Circuit 206 Sampling Resistor

Claims

1. 1. A variable frequency drive circuit for use in a cooking appliance including at least two heating elements including a microwave generator, comprising: a power loop including a first switch member for adjusting the output power of the power loop, the power loop being connected to the common connection end of at least two of the heating members; a load selection circuit connected to the power loop and having at least two outputs adapted for connection to corresponding heating elements; a control circuit connected to the control end of the first switch member and the load selection circuit, for determining a target output power and a target heating member among the at least two heating members based on received control information, and for controlling the first switch member to operate at the target output power and for controlling the load selection circuit to select the target heating member to be powered on and operate; Variable frequency drive circuit.

2. a communication circuit connected to the control circuit and used to receive the control information and transmit the control information to the control circuit; The control information is a pulse width modulation signal, and the frequency of the pulse width modulation signal corresponds one-to-one to the frequency of the heating element.

2. The variable frequency drive circuit of claim 1.

3. The load selection circuit has a first input, and the power loop includes: the rectifier circuit further includes a second input terminal and a third input terminal, and a first output terminal and a second output terminal, the second input terminal and the third input terminal being used for connection to an AC terminal block, the first output terminal being connected to the first input terminal, the second output terminal being connected to a first terminal of the first switch member, and the second terminal of the first switch member being connected to the common connection terminal; 2. The variable frequency drive circuit of claim 1.

4. The power loop further includes a filter circuit, the filter circuit comprising: a first resistor having a first end connected to the first output end and a second end connected to the second output end; a capacitor connected in parallel with the first resistor; 4. The variable frequency drive circuit of claim 3.

5. the power loop further includes a reactor located between the first end of the first resistor and the first output end; 5. The variable frequency drive circuit of claim 4.

6. The power loop a detection circuit having an input terminal connected to the second input terminal and the third input terminal and an output terminal connected to the control circuit; wherein a surge fluctuation exists between the second input and the third input, and the control circuit controls the power loop to stop operating.

4. The variable frequency drive circuit of claim 3.

7. Further, a driving circuit is disposed between the control circuit and the control end of the first switch member, and is used to drive and operate the first switch member.

4. The variable frequency drive circuit of claim 3.

8. The load selection circuit includes a multi-way switch, an input terminal of the multi-way switch is connected to the power loop, and at least two output terminals of the multi-way switch are used for connection to corresponding heating elements.

8. The variable frequency drive circuit of claim 7.

9. at least two heating elements including microwave generators; and a variable frequency drive circuit according to any one of claims 1 to 8 to which at least two of the heating elements are connected. Cooking equipment.

10. A computer board; a third switch member connected to the computer board and the power loop, the third switch member being conductive to supply power to the power loop when the computer board receives a start-up signal for the cooking appliance; The cooking device of claim 9.

11. a communication circuit of the variable frequency drive circuit is connected to the computer board for transmitting the control information to the communication circuit; The cooking device of claim 10.

12. At least two of the heating elements include: further comprising a steam generator and / or a heating tube; The cooking device of claim 10.

13. The microwave generator comprises: A magnetron and a step-up transformer having a first primary coil connected to the power loop and a first secondary coil connected to the magnetron; a voltage doubler circuit connected to a second secondary coil of the step-up transformer and the magnetron; The cooking device of claim 10.

14. Further, a power supply circuit is connected to the second primary coil of the step-up transformer and is used to output a power supply voltage having a predetermined voltage value. The cooking device of claim 13.

15. One end of the voltage doubler circuit is connected to a ground point, and the cooking device a sampling resistor located between one end of the voltage doubler circuit and the ground, the sampling resistor having a first end connected to the one end of the voltage doubler circuit and a second end connected to the ground; wherein a first end of the sampling resistor is connected to the computer board and is used to feedback the operating state of the microwave generator; The cooking device of claim 13.

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