CN109743805B - Electromagnetic oven coil panel with circuit optimization and efficient heating of oven panel - Google Patents
Electromagnetic oven coil panel with circuit optimization and efficient heating of oven panel Download PDFInfo
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Abstract
The invention discloses an electromagnetic oven coil panel which combines circuit optimization and efficient heating of a furnace panel, comprising a coil panel and a converter, wherein the coil panel comprises a coil panel magnetic core and a coil panel winding, and further comprises an equivalent impedance conversion network, the equivalent impedance conversion network is connected with the coil panel winding and the converter, the coil panel winding of the electromagnetic oven at least comprises a tap, and each part of the coil panel winding heats a pot. According to the induction cooker coil panel with the circuit optimization and the efficient heating of the coil panel, through selecting different ports or taps, the self inductance and mutual inductance of each part of windings of the coil panel in the resonance unit can be changed, so that different equivalent impedance transformation is realized, the output characteristics of the converter are optimized, the application range of the material of the induction cooker is widened, meanwhile, the ratio of the equivalent resistance value of the cooker to the equivalent resistance value of the coil panel is increased by combining the method for increasing the working frequency and the number of turns of coil coiling, and the heating efficiency of the coil panel can be improved on the premise of not changing the circuit structure and the stress of devices.
Description
Technical Field
The invention relates to an induction cooker heating technology, in particular to an induction cooker coil panel at least comprising a tap and a group of additional capacitors, and an equivalent impedance transformation method of the induction cooker coil panel.
Background
The induction cooker heats the metal cooker by using induction eddy current, namely, high-frequency alternating current is introduced into the coil panel to generate an alternating magnetic field, the bottom of the cooker generates eddy current by using electromagnetic induction, and the cooker is directly heated by using the Joule heating effect of the eddy current. Compared with the traditional heating mode, the electromagnetic oven does not need open fire or heat conduction, has heating efficiency 40% higher than that of the traditional oven, is safe and sanitary in use environment, does not need to lay a special gas pipeline, is convenient to install, can adapt to various occasions, and has wide application market.
The heating efficiency of the existing induction cooker is generally 86%, and a large lifting space is still provided. In order to improve the heating efficiency, namely the ratio of the folding resistance of the cooker to the alternating current resistance of the coil, the coil panel and the cooker are required to have higher mutual inductance, and the cooker material of the electromagnetic oven is required to have higher requirements. The related efficiency test and analysis result show that: compared with an aluminum pot, the heating efficiency of the stainless steel pot is improved by 35% under the same coil panel and working frequency of the electromagnetic oven. Therefore, the mutual inductance between the induction cooker coil panel and the cooker is improved, and the induction cooker coil panel and the cooker are effective methods for improving the heating efficiency of the induction cooker. At present, manufacturers of electromagnetic ovens at home and abroad basically adopt cookers with multi-layer material composite cookers with high-permeability stainless steel materials added to cookers, so that mutual inductance between the cookers and a coil panel is enhanced.
On the other hand, the heating efficiency can be improved by increasing the operating frequency. The induced potential of the coil disc coupled into the cooker is increased, and the equivalent resistance of the cooker folded to the primary side is increased. However, as the working frequency increases, the effective conductive cross-sectional area of the coil is reduced due to the skin effect and the proximity effect, and the alternating current resistance of the coil panel itself is also increased. Japanese Hataya M, oka Y, umetani K, et al, novel thin heating coil structure with reduced copper loss for high frequency induction cookers [ C ]// International Conference on Electrical Machines & systems, IEEE,2017, proposes a new coil disk winding and core structure in which coils are laminated with rectangular wires having a thickness close to the skin depth to reduce copper loss due to skin effect, and soft magnetic materials are added between different turns of coils to uniformly distribute current over the wire cross section to reduce copper loss due to proximity effect. The novel coil can effectively reduce the alternating current loss of the coil, and further improve the heating efficiency of the coil by improving the working frequency. However, in general, the induction cooker uses Litz wire as a coil panel, and its ac resistance is small, so that the use of a new coil panel to further reduce its ac resistance has a very limited effect on improving the heating efficiency of the coil panel.
Meanwhile, for a low-power electromagnetic oven, the single-tube quasi-resonant converter used by the low-power electromagnetic oven has strict requirements on the equivalent impedance value of a coil panel. From the above analysis, it is known that the heating efficiency of the induction cooker can be improved by increasing the operating frequency within a certain frequency range. However, the actual coil equivalent inductance is greater than the required coil equivalent inductance of the transducer at high frequencies, for which the coil turns need to be reduced to reduce the coil equivalent inductance. At the same time, the reduced number of turns of the coil panel will result in reduced folding resistance of the cooker, which is contrary to the aim of improving heating efficiency of the cooker. In addition, the folding resistance of the cooker is in direct proportion to the square of the number of turns of the coil panel, and the alternating current resistance of the coil is in linear relation with the number of turns of the coil panel, so that the heating efficiency can be improved by improving the number of turns of the coil panel. However, the coil equivalent inductance is also proportional to the square of the number of turns of the coil disc, and when the number of turns of the coil disc is increased, the coil equivalent inductance value is far greater than the coil equivalent inductance value required by the converter, so that the induction cooker cannot work in a quasi-resonance state. The larger switching loss will further reduce its heating efficiency and even damage the switching tube in severe cases. Therefore, on the premise of not changing the circuit structure of the induction cooker, the equivalent impedance value of the independent and decoupled coil panel is a key for effectively implementing the method for improving the heating efficiency.
In order to obtain independent and decoupled coil disc equivalent impedance values, transformation of the coil disc equivalent impedance values can be achieved through a resonant network. The original coil panel is connected into a resonance network, and the equivalent impedance transformation of the induction cooker coil panel can be realized through inductance capacitance resonance. And an additional inductor is connected in series, so that the impedance value of the resonant network can meet the quasi-resonance requirement of the electromagnetic oven. In order to realize impedance transformation, the resonance unit can be constructed by utilizing an additional capacitor and the coil panel of the induction cooker in series-parallel connection, and then the equivalent impedance transformation of the coil panel of the induction cooker is realized by combining an additional transformer. However, the additional transformer increases the volume weight of the coil panel of the induction cooker and further increases copper loss; meanwhile, if a transformer and a resonance network are added in the single-tube quasi-resonant converter, the coil panel impedance model is equivalent to extremely large excitation inductance and resistance which are connected in parallel, so that the single-tube quasi-resonant converter cannot work in a quasi-resonant state. Therefore, for a single quasi-resonant converter for a low-power induction cooker, an impedance conversion network of the single quasi-resonant converter needs to be further designed.
Disclosure of Invention
The invention aims to:
in order to solve the technical problems, the invention provides an electromagnetic oven coil panel which combines circuit optimization and efficient heating of an oven panel, and the electromagnetic oven coil panel comprises a coil panel magnetic core, a coil panel winding with a tap and an additional capacitor, wherein the coil panel winding is connected with an inverter through the tap or a port, and two ends of the coil panel winding are connected with the additional capacitor in parallel to form a resonance unit so as to realize the independence, decoupling and conversion of the equivalent impedance value of the electromagnetic oven coil panel. Meanwhile, by combining the measures of improving the number of turns of the coil winding and the working frequency, the heating efficiency of the induction cooker can be improved and the output characteristic of the converter can be improved. In addition, different equivalent impedance transformation can be realized by switching taps, so that the application range of the cooker of the induction cooker can be enlarged.
The technical scheme is as follows:
the induction cooker coil panel comprises a coil panel and a converter, wherein the coil panel comprises a coil panel magnetic core and a coil panel winding, and further comprises an equivalent impedance conversion network, and the equivalent impedance conversion network is connected with the coil panel winding and the converter.
Further, the converter comprises a power supply U d Resonance capacitor C r1 A switch tube Q, a diode D, wherein the power supply U d Positive electrode of (C) and resonance capacitor C r1 The first end is connected with the common end which is the output end of the converter, the collector of the switch tube Q, the cathode of the diode D and the resonance capacitor C r1 The common end of the second end is connected with the input end of the converter, and the emitter of the switching tube Q, the anode of the diode D and the power supply U d The negative electrode is connected; the equivalent impedance transformation network comprises an additional inductance L s First switch S 1 Second change-over switch S 2 Additional capacitor C r2 The coil disc winding is provided with two ports, and an additional capacitor C r2 The coil winding set arranged between the first port and the second port is provided with N taps, N is a natural number greater than or equal to 1, and the input end of the converter and the first switch S 1 The output end of the converter is connected with an additional inductor L s Is added with an inductance L s Is connected with a second change-over switch S 2 When N is 1, the second switch S 2 Can be switched to a first port and a second port, and a first switch S 1 Can be switched to a tap; when N is a natural number greater than 1, the second switch S 2 Can be switched to the firstA port, a second port or an ith tap, i being a natural number of 1 or more and N or less, a first switch S 1 The coil winding between the j-th tap and the port or tap connected by the two switches is a branch, and the other coil windings are connected in series with an additional capacitor C r2 The other branch is formed, the two branches are connected in parallel to form a resonance unit, and each part heats the cooker.
Further, the converter comprises a power supply U d Resonance capacitor C r1 A switch tube Q, a diode D, wherein the power supply U d Positive electrode of (C) and resonance capacitor C r1 The first end is connected with the common end which is the output end of the converter, the collector of the switch tube Q, the cathode of the diode D and the resonance capacitor C r1 The common end of the second end is connected with the input end of the converter, and the emitter of the switching tube Q, the anode of the diode D and the power supply U d The negative electrode is connected; the equivalent impedance network also comprises an additional inductance L s Additional capacitor C r2 Additional capacitor C r3 The additional inductance L s Is connected with the output end of the converter, and is additionally provided with an inductance L s Is connected with the first port of the coil winding, and is additionally provided with a capacitor C r2 Is connected with the input end of the converter, and is additionally provided with a capacitor C r2 Is connected with a second end of the coil winding, and an additional capacitor C is connected between the input end of the converter and the first end of the coil winding r3 Coil disc winding and additional capacitor C r2 A series branch is formed by series connection, and then the series branch is connected with an additional capacitor C r3 The resonant units are formed in parallel; and each part of the coil disc winding heats the cooker.
Further, an additional capacitor C r3 Replaced by a resonant inductance L r 。
Further, each inductor in the equivalent impedance transformation network can be wound on a coil disc magnetic core together with a coil coiling group, and the magnetic core is added to reduce the coupling between the magnetic core and the cooker so as to improve the utilization rate of the magnetic core; or respectively and independently wound on the independent magnetic cores to adjust the inductance value of each inductor.
Further, the resonance of the resonance unitFrequency omega r Optimized to be at the operating frequency omega s Equal, the coil disc windings have equivalent resistance R equ Equivalent inductance value L equ And additional inductance L s The inductance value optimization calculation formula is as follows:
wherein, the coil panel winding is connected with a change-over switch S 1 Switch S 2 The connected part is winding one W 1 The part of the coil windings except the first winding is a second winding W 2 ，C r2 For additional capacitance C r2 Capacitance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively used for meeting the output characteristic of the converter, L 1 And R is R 1 The equivalent inductance value and the equivalent resistance value of the winding I are respectively R 2 Is the equivalent resistance value of the winding two, M 12 And R is R M12 The mutual inductance and mutual resistance between the first winding and the second winding are respectively.
Further, the coil disc winding and an additional capacitor C r2 A series branch is formed by series connection, and then the series branch is connected with an additional capacitor C r3 A resonance unit is formed in parallel, and the resonance unit is connected with an additional inductance L s Series-connected converters, the resonant frequency ω of the resonant unit r And the working frequency omega s Equal, as shown in formula (5), the equivalent resistance R of the coil disc windings equ Inductance value L equ And additional inductance L s The optimization is represented by the relations (6) to (8):
wherein C is r2 For the additional capacitance C r2 Capacitance value C of (C) r3 For additional capacitance C r3 Capacitance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively.
Further, the coil disc winding and an additional capacitor C r2 Is connected in series to form a series branch and then is connected with the resonant inductor L r The parallel connection forms a resonance unit, the resonance unit is connected in series with an additional inductor, the resonance inductor and the additional inductor can be wound on a coil disc magnetic core or a separate magnetic core, and the resonance frequency omega of the resonance unit r Optimized to be at the operating frequency omega s Equal, the coil disc windings have equivalent resistance R equ Inductance value L equ And additional inductance L s The optimization calculation formula is as follows:
L set ＝L equ ＝L s +L r (11)
L s ＝L set -L r (12)
wherein C is r2 For additional capacitance C r2 Capacitance value L of (1) r Is the resonant inductance L r Inductance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively.
Further, through the change-over switch, the connection port of the coil panel and the converter can be changed, and meanwhile, the additional capacitance, the additional inductance and the resonant inductance are changed, so that the equivalent impedance transformation of different induction cooker coil panels can be realized, and further, the induction cooker is suitable for different input voltages and different working frequencies, and the application range of the induction cooker to cookers of different materials is enlarged; the additional capacitor is composed of a plurality of capacitors, the capacitance value of the additional capacitor can be changed through the relay, the additional inductor and the resonance inductor are respectively composed of a plurality of inductors, and the inductance value of the additional capacitor can be changed through the relay.
Further, the coil disc winding is wound into a single layer or a plurality of layers along a plane perpendicular to the air gap, and the plane geometry in the perpendicular direction of the air gap is circular, regular polygon or a combination of the above shapes; the coil disc magnetic core structure is U-shaped, and the magnetic conduction material is preferably ferrite so as to improve the magnetic field strength and reduce the cost; the wires of the coil disc winding, the additional inductor and the resonant inductor are preferably Litz wires so as to reduce the coil disc loss and the coil disc production cost, and the additional capacitor can be a film capacitor or a CBB capacitor.
The invention has the following beneficial effects:
1. the invention designs the induction cooker coil panel which has the advantages of circuit optimization and high-efficiency heating of the oven panel, and impedance transformation of the induction cooker coil panel can be realized through connecting an additional capacitor in parallel and connecting an additional inductor in series so as to meet the impedance requirement of a transformer on the coil panel.
2. According to the induction cooker coil panel which combines circuit optimization and high-efficiency heating of the panel, voltage stress, current stress and converter efficiency of devices in the converter can be optimized under the same output power by adjusting the equivalent impedance value of the coil panel after impedance conversion on the basis of not changing the original circuit topology.
3. According to the electromagnetic oven coil panel which combines circuit optimization and efficient heating of the oven panel, different equivalent impedance transformation can be realized by switching taps, and the application range of the cooker of the electromagnetic oven coil panel is enlarged.
4. According to the induction cooker coil panel which combines circuit optimization and efficient heating of the panel, the heating efficiency of cookers made of different materials can be effectively improved by properly improving the number of turns and the working frequency of the main winding, and meanwhile, the impedance requirement of the converter on the induction cooker coil panel can be met by combining impedance transformation.
Drawings
FIG. 1 is a schematic diagram of a conventional induction cooker coil panel;
FIG. 2 is a schematic diagram of an induction cooker coil panel adopting a tap structure, which is compatible with circuit optimization and efficient heating of the oven panel;
FIG. 3 is a schematic diagram of an induction cooker coil panel with only additional capacitors, which is compatible with circuit optimization and efficient heating of the panel;
FIG. 4 is a schematic diagram of an induction cooker coil panel employing resonant inductance and additional capacitance, which is a compromise between circuit optimization and efficient heating of the panel;
fig. 5 (a) is a schematic structural diagram of an induction cooker coil panel adopting a single tap mode, which is compatible with circuit optimization and efficient heating of the cooker panel, and fig. 5 (b) is a schematic structural diagram of an induction cooker coil panel adopting a three tap mode, which is compatible with circuit optimization and efficient heating of the cooker panel;
FIG. 6 is an equivalent circuit diagram of an induction cooker coil panel with both circuit optimization and efficient heating of the panel;
FIG. 7 is a simulated waveform diagram of an impedance transformation circuit of an induction cooker coil panel, which combines circuit optimization and efficient heating of the oven panel, when the load is an iron pan;
FIG. 8 is a graph of device stress for equivalent impedance of coil disks of different induction cookers;
FIG. 9 is a simulated waveform diagram of an impedance transformation circuit for an induction cooker coil panel with both circuit optimization and efficient heating of the panel when the load is an aluminum pan in accordance with the present invention;
FIG. 10 (a) is a waveform diagram of a circuit simulation of a conventional induction cooker coil panel for an aluminum pot;
FIG. 10 (b) is a waveform diagram of a circuit simulation of an induction cooker coil panel with a load of aluminum cookware, which is a compromise between circuit optimization and efficient heating of the cooker panel;
FIG. 11 is a graph of the heating efficiency of the burner plate at different numbers of turns and frequencies for an aluminum pan loaded.
Detailed Description
The invention is further explained below with reference to the drawings.
A coil panel of a traditional induction cooker is shown in fig. 1, which is formed by winding a whole section of winding, and a first port and a second port of the winding are connected into a converter. Due to the equivalent resistance R of the coil disc sum Equivalent to the self alternating current resistance R of the coil panel coil Folding resistor R with cooker pan The sum of the heating efficiencies eta of the furnace plate coil ＝P pan /(P pan +P coil )＝R pan /R sum ＝R pan /(R pan +R coil )。
Similar to the common inductance, the pot folding resistor R pan With total number of turns N of coil winding sum Is proportional to the square of the coil disc itself ac resistance R coil And N sum In a linear relationship, thus by increasing N sum Can improve the heating efficiency eta of the furnace plate coil . But with N sum Increase the coil disc equivalent inductance value L sum And then increases, resulting in a decrease in the output power of the converter, or failure to operate at quasi-resonance and damage the IGBT. But with the operating frequency omega s The improvement is that the eddy current skin depth induced by the bottom of the pot is reduced, and the pot is folded into a resistor R pan Will increase, and the coil winding is wound by Litz wire, the alternating current resistance value R is within a certain frequency range coil Substantially unchanged, and thus by increasing ω s Can improve the heating efficiency eta of the furnace plate coil . But with omega s The equivalent inductance value of the coil panel is far greater than the inductance value required by the quasi-resonance state of the converter, and the output power of the converter is reduced, or the converter cannot work in the quasi-resonance state, so that the IGBT is damaged. Therefore, the equivalent inductance value and the equivalent resistance value of the independent and decoupled coil panel are key to effectively implementing the method for improving the heating efficiency of the furnace panel.
Embodiment one:
fig. 5 (a) is a schematic structural diagram of a first embodiment of an induction cooker coil panel according to the invention, which combines circuit optimization and efficient heating of the panel, as shown in fig. 5 (a), in which the coil panel windings W are wound in a single-layer, whole-section manner to reduce the volume and weight of the coil panel, taps a are led out from the windings, and the coil panel passes through ports (1), (2) and an additional capacitor C r2 The parallel connection constitutes a resonant cell. Wherein the winding between the port (1) and the tap A is W 1 The winding between the port (2) and the tap A is W 2 . Additional inductance L s One end is passed through a change-over switch S 1 Is connected with the port (1) or the port (2), namely is connected with the resonance unit in series to form an impedance transformation network, and is further connected with the output end of the converter. Wherein an additional inductance L s The magnetic core can be wound on the magnetic core of the coil disc together with the coil disc, and the magnetic core is added to reduce the coupling between the magnetic core and the cooker so as to improve the utilization rate of the magnetic core; or individually wound on separate cores to adjust the additional inductance L s And (5) a sense value. The coil panel of the electromagnetic oven is connected with the input end of the converter through the tap A. The coil disc winding can be wound by adopting a size wire, a copper sheet and a copper tube, or can also be wound by adopting a PCB winding and the like, and the additional capacitor can be a CBB capacitor or a film capacitor.
Similar to the common inductance, the pot folding resistor R pan And N sum Is proportional to the square of the coil disc itself ac resistance R coil And N sum In a linear relationship, thus increasing N sum Can improve the heating efficiency eta of the furnace plate coil . But with the operating frequency omega s The thickness of the vortex skin induced by the bottom of the pot is reduced, and the folding resistance R of the pot is increased pan Will increase and the coil windings are wound with Litz wire, which is within a certain frequency rangeAC resistance value R coil Remains substantially unchanged, thus increasing ω s Can improve the heating efficiency eta of the furnace plate coil 。
But with N sum 、ω s Increase the coil disc equivalent inductance value L sum And also changes, failing to meet the converter requirements. The invention relates to an electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of a furnace panel, and an additional capacitor C is arranged through ports (1) and (2) r2 The parallel connection forms a resonance unit, thereby realizing the equivalent resistance R of the coil panel sum And (5) transforming. Wherein the resonant frequency omega of the resonant unit r Optimized to be at the operating frequency omega s Equal, as shown in formula (1); the equivalent resistance R of the coil disk of the induction cooker of the invention equ Optimized to the required resistance R of the converter set I.e. equivalent resistance R of resonant unit res Optimized as R set As shown in formula (2). In the formula (2), L 1 For winding W 1 Equivalent inductance value of M 12 For winding W 1 And winding W 2 Mutual inductance between R 1 For winding W 1 Equivalent resistance value of R 2 For winding W 2 Equivalent resistance value of R sum R is the total equivalent resistance value of coil windings M12 For winding W 1 And winding W 2 Mutual resistance between the two.
The resonant unit is connected with the additional inductance L s The equivalent inductance value L of the induction cooker coil is further realized by series connection equ ＝L s +L res Wherein an inductance L is added s Optimized to the converter requirement L set Equivalent inductance value L with resonance unit res The difference is represented by formula (3).
Therefore, the invention provides the electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of the oven panel, and N is realized by utilizing the characteristic of impedance transformation of the resonance unit sum 、ω s The equivalent impedance value Z of the coil panel of the induction cooker after lifting equ Meets the requirements of the converter, and effectively improves the heating efficiency of the furnace plate on the premise of not damaging the output characteristics of the converter.
At the same time Z equ But also the output characteristics of the converter. When R is equ When increased, the device voltage stress will increase and the current stress will decrease under the same output power conditions. At the same time, for different R equ Converter pair L equ There are also specific requirements to achieve zero voltage turn-on and quasi-resonant processes. Under the stress requirement of a specific IGBT device, the tap position and the additional capacitor C are arranged r2 Additional inductance L s Adjustable Z equ Is the optimal value. Therefore, the electromagnetic oven coil panel which combines circuit optimization and efficient heating of the oven panel can realize optimization of the output characteristic of the converter by utilizing the characteristic of impedance transformation of the resonance unit.
In addition, when the material of the load pot is changed, the equivalent impedance of each part of winding is also changed. By switching additional capacitance C r2 The resonance frequency omega of the resonance unit is made r Still with the operating frequency omega s Equality satisfies the formula (1). Through a change-over switch S 1 Changeable coil winding and additional inductance L s Thereby changing the equivalent impedance Z of the coil panel of the induction cooker of the invention equ At this time R equ As shown in formula (4), L s The formula (5) needs to be satisfied.
Therefore, the electromagnetic oven coil panel which has the advantages of circuit optimization and efficient heating of the oven panel ensures that the equivalent impedance value of the coil panel still meets the requirements of the converter after the material of the load cooker is changed, and effectively expands the application range of the electromagnetic oven cooker.
Embodiment two:
FIG. 5 (B) is a schematic diagram showing the structure of a second embodiment of an induction cooker coil with both circuit optimization and efficient heating of the coil, in which, as shown in FIG. 5 (B), the coil winding W is wound in a double-layer, whole-section manner to increase the mutual inductance between the windings and improve the heating efficiency of the coil winding, the tap A, the tap B and the tap C are led out from the winding, the tap A, B, C can be arranged at any position in the double-layer winding, and the coil winding passes through the ports (1), (2) and the additional capacitor C r2 The parallel connection constitutes a resonant cell. Wherein the winding between tap A and tap B is W 1 The whole winding removes W 1 The rest is W 2 The winding between tap A and tap C is W 3 The whole winding removes W 3 The rest is W 4 . Additional inductance L s An impedance transformation network is formed by connecting the tap A with the resonance unit in series and then is connected with the output end of the converter. Wherein an additional inductance L s The magnetic core can be wound on the magnetic core of the coil disc together with the coil disc, and the magnetic core is added to reduce the coupling between the magnetic core and the cooker so as to improve the utilization rate of the magnetic core; or individually wound on separate cores to adjust the additional inductance L s And (5) a sense value. The input end of the converter passes through a change-over switch S 1 To tap B or tap C.
As in embodiment one, with N sum 、ω s Improves the heating efficiency eta of the furnace plate coil Increased coil equivalent inductance value L sum And also changes, failing to meet the converter requirements. The invention relates to an electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of a furnace panel, and an additional capacitor C is arranged through ports (1) and (2) r2 The parallel connection forms a resonance unit, thereby realizing the equivalent resistance R of the coil panel sum And (5) transforming. Wherein the resonant frequency omega of the resonant unit r Optimized to be at the operating frequency omega s Equal, as shown in formula (1); the equivalent resistance of the coil disk of the induction cooker of the invention R equ Optimized to the required resistance R of the converter set I.e. equivalent resistance R of resonant unit res Optimized as R set As shown in formula (2). The resonant unit is connected with the additional inductance L s The equivalent inductance value L of the induction cooker coil is further realized by series connection equ ＝L s +L res Wherein an inductance L is added s Optimized to the converter requirement L set Equivalent inductance value L with resonance unit res The difference is represented by formula (3).
As in the first embodiment, the invention provides an electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of the oven panel, and utilizes the characteristic of impedance transformation of a resonance unit to enable N to be sum 、ω s The equivalent impedance value Z of the coil panel of the induction cooker after lifting equ Meets the requirements of the converter, and effectively improves the heating efficiency of the furnace plate on the premise of not damaging the output characteristics of the converter. Meanwhile, under the stress requirement of a specific IGBT device, a tap position and an additional capacitor C are arranged r2 Additional inductance L s Adjustable Z equ Is the optimal value. Therefore, the electromagnetic oven coil panel which combines circuit optimization and efficient heating of the oven panel can realize optimization of the output characteristic of the converter by utilizing the characteristic of impedance transformation of the resonance unit.
In addition, when the material of the load pot is changed, the equivalent impedance of each part of winding is also changed. By switching additional capacitance C r2 The resonance frequency omega of the resonance unit is made r Still with the operating frequency omega s Equality satisfies the formula (1). Through a change-over switch S 1 The connection port of the coil panel winding and the converter can be changed, so that the equivalent impedance Z of the coil panel of the electromagnetic oven can be changed equ At this time R equ As shown in formula (6), L s The formula (7) needs to be satisfied. In the formulas (6) and (7), L 3 For winding W 3 Equivalent inductance value of M 34 For winding W 3 And winding W 4 Mutual inductance between R 3 For winding W 3 Equivalent resistance value of R 4 For winding W 4 Equivalent resistance value of R sum R is the total equivalent resistance value of coil windings M34 For winding W 3 And winding W 4 Mutual resistance between the two.
Therefore, the electromagnetic oven coil panel which has the advantages of circuit optimization and efficient heating of the oven panel ensures that the equivalent impedance value of the coil panel still meets the requirements of the converter after the material of the load cooker is changed, and effectively expands the application range of the electromagnetic oven cooker.
Embodiment III:
fig. 3 is a schematic structural diagram of a third embodiment of an induction cooker coil panel with circuit optimization and efficient heating of the panel, as shown in fig. 3, in the third embodiment, coil panel windings W are wound in a single-layer and whole-section manner to reduce the volume and weight of the coil panel, and the coil panel passes through a port (2) and an additional capacitor C r2 Is connected in series to form a series branch, and is connected with an additional capacitor C r3 The resonant cells are formed in parallel. Additional inductance L s An impedance transformation network is formed by connecting the port (1) with the resonance unit in series and is further connected with the output end of the converter. Wherein an additional inductance L s The magnetic core can be wound on the magnetic core of the coil disc together with the coil disc, and the magnetic core is added to reduce the coupling between the magnetic core and the cooker so as to improve the utilization rate of the magnetic core; or individually wound on separate cores to adjust the additional inductance L s And (5) a sense value. The coil panel of the induction cooker is connected with the input end of the converter through the common point of the two groups of additional capacitors.
As in embodiment one, with N sum 、ω s Improves the heating efficiency eta of the furnace plate coil Increased coil equivalent inductance value L sum And also changes, failing to meet the converter requirements. The invention relates to an electromagnetic oven coil panel which combines circuit optimization and efficient heating of a stove panel, and an additional capacitor C is arranged through a port (2) r2 Is connected in series to form a series branch, and is connected with an additional capacitor C r3 Parallel-connection resonanceUnit, thereby realizing equivalent resistance R of coil panel sum And (5) transforming. Wherein the resonant frequency omega of the resonant unit r Optimized to be at the operating frequency omega s Equal, as shown in formula (8). The equivalent resistance R of the coil disk of the induction cooker of the invention equ Optimized to the required resistance R of the converter set I.e. equivalent resistance R of resonant unit res Optimized as R set As shown in formula (9).
The resonant unit is connected with the additional inductance L s The equivalent inductance value L of the induction cooker coil is further realized by series connection equ ＝L s +L res Wherein an inductance L is added s Optimized to the converter requirement L set Equivalent inductance value L with resonance unit res The difference is represented by formula (3).
Therefore, the invention provides the electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of the oven panel, and N is realized by utilizing the characteristic of impedance transformation of the resonance unit sum 、ω s The equivalent impedance value Z of the coil panel of the induction cooker after lifting equ Meets the requirements of the converter, and effectively improves the heating efficiency of the furnace plate on the premise of not damaging the output characteristics of the converter. At the same time, similar to the embodiment, under the stress requirement of a specific IGBT device, an additional capacitor C is arranged r2 Additional capacitor C r3 Additional inductance L s Adjustable Z equ Is the optimal value. Therefore, the electromagnetic oven coil panel which combines circuit optimization and efficient heating of the oven panel can realize optimization of the output characteristic of the converter by utilizing the characteristic of impedance transformation of the resonance unit.
In addition, when the material of the load pot is changed, the equivalent impedance of each part of winding is also changed. By switching additional capacitance C r2 With additional capacitance C r3 The resonance frequency omega of the resonance unit is made r Still with the operating frequency omega s Equality, i.e. satisfy formula (8), and vary R equ . By switching the additional inductance L s So as to satisfy the formula (10), and further change L equ . Therefore, the electromagnetic oven coil panel which has the advantages of circuit optimization and efficient heating of the oven panel ensures that the equivalent impedance value of the coil panel still meets the requirements of the converter after the material of the load cooker is changed, and effectively expands the application range of the electromagnetic oven cooker.
Embodiment four:
fig. 4 is a schematic structural diagram of a fourth embodiment of an induction cooker coil panel with both circuit optimization and efficient heating of the panel, as shown in fig. 4, in which coil windings W are wound in a single-layer, whole-section manner to reduce coil volume and weight, and the coil winding passes through a port (2) and an additional capacitor C r2 Is connected in series to form a series branch and then is connected with the resonant inductor L r The resonant cells are formed in parallel. The resonance unit passes through the port (1) and the additional inductance L s The series connection forms an impedance transformation network which is further connected with the output end of the converter. Wherein the resonant inductance L r Additional inductance L s The magnetic core can be wound on the magnetic core of the coil disc together with the coil disc, and the magnetic core is added to reduce the coupling between the magnetic core and the cooker so as to improve the utilization rate of the magnetic core; or individually wound on separate cores to adjust the additional inductance L s And (5) a sense value. The coil panel of the electromagnetic oven passes through the resonant inductor L r With additional capacitance C r2 Is connected with the input end of the converter.
As in embodiment one, with N sum 、ω s Improves the heating efficiency eta of the furnace plate coil Improving the quality. But with N sum 、ω s Increase the coil disc equivalent inductance value L sum And also changes, failing to meet the converter requirements. The invention relates to an electromagnetic oven coil panel which combines circuit optimization and efficient heating of a stove panel, and an additional capacitor C is arranged through a port (2) r2 In series to form a seriesBranch circuit, and resonant inductor L r The resonant units are formed in parallel, thereby realizing the equivalent resistance R of the coil panel sum And (5) transforming. Wherein the resonant frequency omega of the resonant unit r Optimized to be at the operating frequency omega s Equal, as shown in formula (11); the equivalent resistance R of the coil disk of the induction cooker of the invention equ Optimized to the required resistance R of the converter set I.e. equivalent resistance R of resonant unit res Optimized as R set As shown in formula (12).
The resonant unit is connected with the additional inductance L s The equivalent inductance value L of the induction cooker coil is further realized by series connection equ ＝L s +L res Wherein an inductance L is added s Optimized to the converter requirement L set Equivalent inductance value L with resonance unit res The difference is represented by formula (13).
L s ＝L set -L res ＝L set -L r (13)
Therefore, the invention provides the electromagnetic oven coil panel which combines circuit optimization and high-efficiency heating of the oven panel, and N is realized by utilizing the characteristic of impedance transformation of the resonance unit sum 、ω s The equivalent impedance value Z of the coil panel of the induction cooker after lifting equ Meets the requirements of the converter, and effectively improves the heating efficiency of the furnace plate on the premise of not damaging the output characteristics of the converter. At the same time, similar to the embodiment, under the stress requirement of a specific IGBT device, an additional capacitor C is arranged r2 Resonant inductance L r Additional inductance L s Adjustable Z equ Is the optimal value. Therefore, the electromagnetic oven coil panel which combines circuit optimization and efficient heating of the oven panel can realize optimization of the output characteristic of the converter by utilizing the characteristic of impedance transformation of the resonance unit.
In addition, when the material of the load pot is changed, the equivalent impedance of each part of winding is also changed. By switching additional capacitance C r2 And resonant inductance L r The resonance frequency omega of the resonance unit is made r Still with the operating frequency omega s Equality, i.e. satisfy formula (11), and vary R equ . By switching the additional inductance L s So as to satisfy the formula (13), and further change L equ . Therefore, the electromagnetic oven coil panel which has the advantages of circuit optimization and efficient heating of the oven panel ensures that the equivalent impedance value of the coil panel still meets the requirements of the converter after the material of the load cooker is changed, and effectively expands the application range of the electromagnetic oven cooker.
Test case one:
To verify the feasibility of the invention to achieve impedance transformation of the induction cooker coil panel, a simulation verification was performed using the induction cooker coil panel shown in fig. 5 (b) as an example. The coil winding W is wound in a double-layer and whole-section mode to increase mutual inductance among all partial windings and improve heating efficiency, a tap A, a tap B and a tap C are led out from the winding, a tap A, B, C can be arranged at any position in the double-layer winding, and the coil winding passes through ports (1) and (2) and an additional capacitor C r2 The parallel connection constitutes a resonant cell. Wherein the winding between tap A and tap B is W 1 The whole winding removes W 1 The rest is W 2 The winding between tap A and tap C is W 3 The whole winding removes W 3 The rest is W 4 . Additional inductance L s An impedance transformation network is formed by connecting the tap A with the resonance unit in series and then is connected with the output end of the converter. Wherein an additional inductance L s The coil winding can be wound alone or together with the coil winding on the coil core, but additional cores are added to shield the coupling with the Pan and coil winding W. The input end of the converter passes through a change-over switch S 1 To tap B or tap C. The coil disc magnetic core adopts U-shaped magnetic core, and each winding of coil disc adopts the haze line to wind, and additional electric capacity adopts CBB electric capacity. Specific parameters of the coil panel of this embodiment are as follows:
TABLE 1
An equivalent circuit diagram of the coil panel of the induction cooker shown in fig. 5 (b) is shown in fig. 6, wherein L 1 、R 1 Respectively represent the windings W 1 Equivalent inductance and resistance, L 2 、R 2 Respectively represent W 2 Equivalent inductance and resistance of M 12 Indicating winding W 1 And W is equal to 2 Mutual inductance between R M12 Representing the mutual inductance resistance between two partial windings, L s Represents additional inductance, C r2 Is an additional capacitance.
First, the induction cooker coil panel was simulated by using finite element simulation software ANSYS Maxwell2D, and the simulation results are shown in table 2.
TABLE 2
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Wherein L (N1, N1) and R (N1, N1) respectively represent the winding W 1 L (N2, N2) and R (N2, N2) respectively represent the winding W 2 L (N1, N2) and R (N1, N2) respectively represent the sum of the equivalent inductance and the equivalent resistance of the winding W 1 And winding W 2 Mutual inductance and mutual inductance resistance between the two.
The equivalent impedance value of each partial winding of ANSYS Maxwell2D simulation is used as a circuit parameter, the circuit simulation software Saber is used for carrying out circuit simulation on the impedance transformation principle, the simulation result is shown as figure 7, and u is shown as the following in For power supply input voltage, U rms Is the effective value of the input voltage of the power supply, i in For inputting current to power supply, I rms Input current effective value for power supply, p in For inputting power to power supply, P avg Is the average value of the input power of the power supply. Calculating to obtain apparent power S and reactive power Q of the power supply, and passing through active power P, reactive power Q and I rms The equivalent impedance value can be calculated and the results are shown in Table 3, where R equ 、L equ The equivalent resistance values of the coil disk of the induction cooker are respectively equal to the equivalent inductance values.
TABLE 3 Table 3
| f/kHz | I rms /A | V rms /V | S/VA | P/W | Q/Var | R equ /Ω | L equ /μH |
| 40 | 0.3086 | 7.071 | 2.182 | 0.6655 | 2.078 | 6.986 | 86.81 |
By setting tap position and selecting different additional inductances, the equivalent impedance value Z of the coil panel of the electromagnetic oven can be changed equ While changing the output characteristics of the single-tube quasi-resonant converter. At output power P o When the material is=2000W, the stress-equivalent resistance characteristic curve is shown in FIG. 8, in which U qcmax For the highest voltage of IGBT collector, I qmax For maximum current of IGBT collector, R equ Is the equivalent resistance of the coil disk of the electromagnetic oven. I of IGBT selected CE ＝40A，V CE =1350V, where the equivalent resistance R is selected equ =7Ω to obtain the best output characteristics.
Test case two:
the induction cooker coil panel in the first test example is taken as an example, and finite element simulation software ANSYS Maxwell2D is utilized to further describe the principle that the induction cooker coil panel provided by the invention can be suitable for cookers of different materials while taking circuit optimization and efficient heating of the induction cooker coil panel into consideration. The specific parameters of the test examples are the same as those of the first test example, and are shown in Table 1. The coil panel of the electromagnetic oven adopts a 3-tap structure, a tap A, B is selected when the stainless steel cooker is used, and the number of turns N of the coil coiling group among the taps A, B 1 =15; tap A, C is selected when the aluminum pot is provided with a coil winding number N among A, C taps 3 ＝6。
The equivalent impedance value of each part of windings of the induction cooker when the load is the stainless steel cooker is the same as the first test example after impedance transformation, and will not be described here. When the load is an aluminum pot, the equivalent impedance values of each part of the coil panel are shown in tables 4 and 5 through finite element simulation.
TABLE 4 Table 4
TABLE 5
Wherein L (N1, N1) and R (N1, N1) respectively represent the winding W 3 L (N2, N2) and R (N2, N2) respectively represent the winding W 4 L (N1, N2) and R (N1, N2) respectively represent the winding W 3 And winding W 4 Mutual inductance and mutual inductance resistance between the coil discs, L (CoilSum ) and R (CoilSum, coilSum) respectively represent the overall equivalent inductance L of the coil disc sum And equivalent resistance R sum 。
The equivalent impedance value of each partial winding of ANSYS Maxwell2D simulation is used as a circuit parameter, the circuit simulation software Saber is used for carrying out circuit simulation on the impedance transformation principle, the simulation result is shown as figure 9, and u is shown as the following in For power supply input voltage, U rms Is the effective value of the input voltage of the power supply, i in For inputting current to power supply, I rms Input current effective value for power supply, p in For inputting power to power supply, P avg Is the average value of the input power of the power supply. The calculated apparent power S and reactive power Q of the power supply are utilized to pass through the active power P, the reactive power Q and I rms The equivalent impedance value can be calculated and the results are shown in Table 6, where R equ 、L equ The equivalent resistance values of the coil disk of the induction cooker are respectively equal to the equivalent inductance values.
I of IGBT CE ＝30A，V CE With the conventional induction cooker coil disk structure, the output waveform is as shown in fig. 10 (a), wherein p, under the limit of IGBT stress o For output power, P avg For output power average value i Q For IGBT collector current, I qmax For IGBT collector current maximum value, u qc For IGBT collector voltage, U qcmax Is the maximum value of the IGBT collector voltage. Can be seen in U qcmax When=1059v, output power P o Only 129W is achieved, which is far lower than the requirement of heating power of the induction cooker, so that the aluminum pot cannot be used as a load pot of the induction cooker; the coil panel of the induction cooker, which combines circuit optimization and efficient heating of the coil panel, is used for selecting a tap A, C with equivalent resistance R equ =7Ω, the output waveform of which is shown in (b) of fig. 10, at U qcmax Output power P when=915V o Up to 497W, and can be used for a low-power electromagnetic oven.
Therefore, by switching different taps, additional capacitors and additional inductors, the self inductance and mutual inductance of each part of windings can be changed, so that the impedance transformation value is changed, the effective heating of cookers made of different materials is realized, and the application range of cookers of the coil disc of the induction cooker is enlarged.
TABLE 6
Test case three:
the induction cooker coil panel shown in fig. 5 (b) is taken as an example, and the principle that the induction cooker coil panel provided by the invention can improve the heating efficiency by considering both circuit optimization and efficient heating of the induction cooker coil is specifically described. Coil disc equivalent resistance R sum Equivalent to the self alternating current resistance R of the coil panel coil Folding resistor R with cooker pan Series connection of furnace plate heating efficiency eta coil ＝P pan /(P pan +P coil )＝R pan /R sum ＝R pan /(R pan +R coil ) Thus taking R as pan And R is R sum Is used as a reference value for the heating efficiency of the furnace plate. The coil disc magnetic core adopts U-shaped magnetic core, and each winding of coil disc adopts the haze line to wind, and additional electric capacity adopts CBB electric capacity. The specific parameters of the coil panel of this embodiment are shown in table 7:
TABLE 7
Similar to the common inductance, the pot folding resistor R pan And N sum Is proportional to the square of the coil disc itself ac resistance R coil And N sum In a linear relationship, thus by increasing N sum Can improve the heating efficiency eta of the furnace plate coil The method comprises the steps of carrying out a first treatment on the surface of the But with the operating frequency omega s The folding resistance R of the pot is improved along with the reduction of the skin depth pan Will increase, and the coil winding is wound by Litz wire, the alternating current resistance value R coil Substantially independent of frequency and therefore by increasing ω s Can improve the heating efficiency eta of the furnace plate coil . Meanwhile, the coil panel is connected into the converter by utilizing the tap, and an impedance conversion network is formed by combining an additional capacitor and an additional inductor, so that the coil panel can have equivalent resistance The reactance value meets the design requirements of the converter and the stress limit of the device.
Magnetic field simulation software is utilized to respectively perform magnetic field simulation on coil panels of 20kHz and 40kHz, eta coil ＝R pan /R sum As shown in fig. 11. It can be seen from ω s ＝20kHz、N sum η when=18 coil = 58.98 to ω s ＝40kHz、N sum η when=58 coil =85.23% and stove plate heating efficiency η coil The coil panel is improved by 26.25%, so that the heating efficiency of the cooker can be remarkably improved.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (9)
1. The electromagnetic oven coil panel with the circuit optimization and the high-efficiency heating of the oven panel comprises a coil panel and a converter, wherein the coil panel comprises a coil panel magnetic core and a coil panel winding, and is characterized by further comprising an equivalent impedance transformation network, and the equivalent impedance transformation network is connected with the coil panel winding and the converter;
the converter comprises a power supply U d Resonance capacitor C r1 A switch tube Q, a diode D, wherein the power supply U d Positive electrode of (C) and resonance capacitor C r1 The first end is connected with the common end which is the output end of the converter, the collector of the switch tube Q, the cathode of the diode D and the resonance capacitor C r1 The common end of the second end is connected with the input end of the converter, and the emitter of the switching tube Q, the anode of the diode D and the power supply U d The negative electrode is connected; the equivalent impedance transformation network comprises an additional inductance L s First switch S 1 Second change-over switch S 2 Additional capacitor C r2 The coil disc winding is provided with two ports, and an additional capacitor C r2 The coil panel winding is provided with N taps, N is a natural number greater than or equal to 1, and the input end of the converter and the first switch S are arranged between the first port and the second port 1 The output end of the converter is connected with an additional inductor L s Is added with an inductance L s Is connected with a second change-over switch S 2 When N is 1, the second switch S 2 Switch to a first port and a second port, a first switch S 1 Switching to a tap; when N is a natural number greater than 1, the second switch S 2 A first switch S for switching to a first port, a second port or an ith tap, i being a natural number of 1 or more and N or less 1 The coil windings are switched to the j tap, i is not equal to j, the ports connected by the two switches or the coil windings between the taps are one branch, and the other coil windings are connected in series with an additional capacitor C r2 The other branch is formed, and the two branches are connected in parallel to form a resonance unit.
2. The electromagnetic oven coil panel with the circuit optimization and the high-efficiency heating of the oven panel comprises a coil panel and a converter, wherein the coil panel comprises a coil panel magnetic core and a coil panel winding, and is characterized by further comprising an equivalent impedance transformation network, and the equivalent impedance transformation network is connected with the coil panel winding and the converter;
the converter comprises a power supply U d Resonance capacitor C r1 A switch tube Q, a diode D, wherein the power supply U d Positive electrode of (C) and resonance capacitor C r1 The first end is connected with the common end which is the output end of the converter, the collector of the switch tube Q, the cathode of the diode D and the resonance capacitor C r1 The common end of the second end is connected with the input end of the converter, and the emitter of the switching tube Q, the anode of the diode D and the power supply U d The negative electrode is connected; the equivalent impedance network also comprises an additional inductance L s Additional capacitor C r2 Additional capacitor C r3 The additional inductance L s Is connected with the output end of the converter, and is additionally provided with an inductance L s Is connected with the first port of the coil winding, and is additionally provided with a capacitor C r2 Is connected with the input end of the converter, and is additionally provided with a capacitor C r2 Is connected with a second end of the coil winding, and an additional capacitor C is connected between the input end of the converter and the first end of the coil winding r3 Coil windingGroup and additional capacitance C r2 A series branch is formed by series connection, and then the series branch is connected with an additional capacitor C r3 The resonant cells are formed in parallel.
3. An induction cooker coil panel with both circuit optimization and efficient heating of the panel as claimed in claim 2, wherein the additional capacitor C is formed by r3 Replaced by a resonant inductance L r 。
4. An induction cooker coil panel which combines circuit optimization and efficient heating of the panel as claimed in any one of claims 1, 2 and 3, wherein each inductor in the equivalent impedance transformation network is wound on a coil panel magnetic core together with the coil panel winding, and a magnetic core is added to reduce the coupling with a cooker and improve the utilization rate of the magnetic core; or respectively and independently wound on the independent magnetic cores to adjust the inductance value of each inductor.
5. An induction cooker coil panel with both circuit optimization and efficient heating of the panel as claimed in claim 1, wherein the resonant frequency ω of the resonant unit r Optimized to be at the operating frequency omega s Equal, the coil disc windings have equivalent resistance R equ Equivalent inductance value L equ And additional inductance L s The inductance value optimization calculation formula is as follows:
wherein, the coil panel winding is connected with a change-over switch S 1 Switch S 2 The connected part is winding one W 1 The part of the coil windings except the first winding is a second winding W 2 ，C r2 For additional capacitance C r2 Capacitance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively L 1 And R is R 1 The equivalent inductance value and the equivalent resistance value of the winding I are respectively R 2 Is the equivalent resistance value of the winding two, M 12 And R is R M12 The mutual inductance and mutual resistance between the first winding and the second winding are respectively.
6. An induction cooker coil panel with both circuit optimization and efficient heating of the panel as claimed in claim 2, wherein the coil panel windings and additional capacitance C r2 A series branch is formed by series connection, and then the series branch is connected with an additional capacitor C r3 A resonance unit is formed in parallel, and the resonance unit is connected with an additional inductance L s Series-connected converters, the resonant frequency ω of the resonant unit r And the working frequency omega s Equal, as shown in formula (5), the equivalent resistance R of the coil disc windings equ Inductance value L equ And additional inductance L s The optimization is represented by the relations (6) to (8):
wherein C is r2 For the additional capacitance C r2 Capacitance value C of (C) r3 For additional capacitance C r3 Capacitance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively.
7. An induction cooker coil according to claim 3, characterized in that the coil winding and the additional capacitor C are combined with each other r2 Is connected in series to form a series branch and then is connected with the resonant inductor L r The parallel connection forms a resonance unit, the resonance unit is connected in series with an additional inductor, the resonance inductor and the additional inductor are wound on a coil disc magnetic core or a separate magnetic core, and the resonance frequency omega of the resonance unit r Optimized to be at the operating frequency omega s Equal, the coil disc windings have equivalent resistance R equ Inductance value L equ And additional inductance L s The optimization calculation formula is as follows:
L set ＝L equ ＝L s +L r (11)
L s ＝L set -L r (12)
wherein C is r2 For additional capacitance C r2 Capacitance value L of (1) r Is the resonant inductance L r Inductance value L of (1) sum And R is R sum Respectively equivalent inductance value and equivalent resistance value of the coil panel winding, L set And R is R set The required inductance value and the required resistance value are respectively.
8. An induction cooker coil panel which combines circuit optimization and efficient heating of a cooker panel according to any one of claims 1-3, characterized in that the connection port of the coil panel and a converter is changed through a change-over switch, and meanwhile, an additional capacitor, an additional inductor and a resonant inductor are changed, so that equivalent impedance transformation of different induction cooker coil panels is realized, different input voltages and different working frequencies are further adapted, and the application range of the induction cooker to cookers of different materials is enlarged; the additional capacitor is composed of a plurality of capacitors, the capacitance value of the additional capacitor is changed through the relay, the additional inductor and the resonant inductor are respectively composed of a plurality of inductors, and the inductance value of the additional capacitor is changed through the relay.
9. An induction cooker coil panel according to any one of claims 1 to 3, characterized in that the coil panel windings are wound in a single layer or a plurality of layers along a plane perpendicular to the air gap, and the planar geometry in the direction perpendicular to the air gap is circular, regular polygon or a combination of the above; the coil disc magnetic core structure is U-shaped, and the magnetic conduction material is ferrite, so that the magnetic field strength is improved and the cost is reduced; the wires of the coil panel winding, the additional inductor and the resonant inductor are Litz wires, so that the coil panel loss is reduced, the coil panel production cost is reduced, and the additional capacitor is a thin film capacitor or a CBB capacitor.
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| CN1839537A (en) * | 2003-08-19 | 2006-09-27 | 高周波热鍊株式会社 | Power-feeding device and induction heating device |
| CN1874620A (en) * | 2005-05-30 | 2006-12-06 | 日立家用电器公司 | Induction heating device |
| CN204518108U (en) * | 2015-04-01 | 2015-07-29 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic Heating control circuit and electromagnetic appliance |
| CN210725394U (en) * | 2019-02-01 | 2020-06-09 | 南京航空航天大学 | Electromagnetic oven coil panel with circuit optimization and efficient heating of oven panel |
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