JP3399215B2 - High frequency inverter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency inverter that operates at a constant frequency and is effective for a multi-port induction heating cooker or the like. 2. Description of the Related Art Hitherto, a high-frequency inverter of this type has generally been disclosed in Japanese Patent Application Laid-Open No. Hei 5-21150. Hereinafter, the high-frequency inverter will be described with reference to FIGS. FIG. 8 is a circuit diagram of a conventional high-frequency inverter. In FIG. 8, reference numeral 101 denotes a DC power supply, 102 denotes an inverter circuit for converting DC to high-frequency current, and 103
Is a control circuit for controlling the inverter circuit 102. The inverter circuit 102 includes a reverse current blocking type first switching element 104 and a reverse current conduction type second switching element 1.
05, heating coil 106, first resonance capacitor 10
7, the second resonance capacitor 108 and the diode 109. The control circuit 103 includes a drive unit 110 and the like that alternately conduct the first switching element 104 and the second switching element 105 at a constant frequency f0. FIG. 9 shows operation waveforms of respective parts for explaining the operation of the conventional high-frequency inverter configured as described above. FIG. 10 shows input power control characteristics of a conventional high-frequency inverter. As is clear from FIG. 10, in the conventional high-frequency inverter, the on-time (ton1) ratio (ton1 / t0) of the first switching element 104 to the constant cycle (t0) is kept under the constant operating frequency (f0) of the inverter circuit. The input power (Pin) control can be performed by changing the
As is clear from the operation waveforms of FIG. 9, the first switching element 104 and the second switching element 105 were able to realize the zero volt switching operation. [0005] Since such a conventional high-frequency inverter can control input power at a constant operating frequency, when it is used in a multi-port induction heating cooker, it is caused by a difference in frequency between burners. Pot interference noise can be solved, and two switching elements can realize zero volt switching operation.
Although it was excellent in miniaturization, a low-cost and compact high-frequency inverter was required for the spread of multi-port induction heating cookers. In order to solve the above-mentioned problems, the present invention provides a coil having one end connected to a positive side of a DC power supply , a coil having one end connected to the other end of the DC power supply, and a minor connected to the DC power supply .
A first switching element connected to the coil, a first resonance capacitor forming a resonance circuit with the coil, and a series connection of a second switching element and a second resonance capacitor of a reverse current conduction type connected in parallel with the coil. And a control circuit for controlling the conduction of the first switching element and the second switching element, wherein the control circuit alternately controls the conduction of the switching elements at a constant frequency, and controls each of the switching elements to control the input power. This is obtained by changing the conduction ratio of the switching element. DETAILED DESCRIPTION OF THE INVENTION The invention of claim 1 Symbol mounting includes a DC power supply
A coil and one end is connected to the positive side of the carp
A first switching element connected to the other end of the DC power supply and the negative side of the DC power supply , a first resonance capacitor forming a resonance circuit with the coil, and a reverse connection connected in parallel with the coil.
A series connection of a current conduction type second switching element and a second resonance capacitor, and a control circuit for controlling conduction of the first switching element and the second switching element, wherein the control circuit keeps each of the switching elements constant. In addition to conducting conduction control alternately at the frequency and changing the conduction ratio of each switching element to control the input power, in a multi-port induction heating cooker, it is possible to solve the interference sound between the burners, and the first switching element and the second A high-frequency inverter capable of performing a zero-volt switching operation of a switching element can be achieved simply, compactly, and at low cost. FIG. 1 is a circuit diagram of an induction heating cooker using a high-frequency inverter according to the present invention. In FIG. 1, reference numeral 1 denotes a DC power supply, 2 denotes an inverter circuit, and 3 denotes a control circuit.
The inverter circuit 2 includes a heating coil 4 having one end connected to the plus side of the DC power supply 1, and a first switching element connected to the other end of the heating coil 4 and the minus side of the DC power supply 1. IG with reverse conducting diode
A BT5 and a first resonance capacitor 6 connected in parallel with the heating coil 4, that is, a series of an IGBT 7 with a built-in reverse conducting diode as a second switching element and a second resonance capacitor 8 in a so-called one-stone inverter. Circuit
It is configured to be connected in parallel with the coil 4 for heating.
The series circuit of the GBT 7 and the resonance capacitor 8 has a role of an auxiliary switch for realizing a constant frequency operation. The control circuit 3 includes a drive circuit 9 for driving the IGBT 5 and the IGBT 7, and the drive circuit 9 operates at a constant operating frequency (f
0), the IGBT 5 and the IGBT 7 are turned on alternately, so that the IGBT 5
Ratio D1 = ton1 /, which is the ratio of the on-time ton1
Input power control is performed by changing t0. FIG. 2 shows operation waveforms of each part of the inverter circuit 2 and FIG. 3 shows input power control characteristics of the inverter circuit 2. In FIG. 2, vge1 is a gate-emitter voltage of the IGBT5, vge2 is a gate-emitter voltage of the IGBT7, vce1 is a collector-emitter voltage of the IGBT5, vce2 is a collector-emitter voltage of the IGBT7, and ic1 is a voltage of the IGBT5. Collector current, ic2 is I
The collector current of the GBT 7 is shown. In the above description, the series circuit of the IGBT 7 as the second switching element and the second resonance capacitor 8 is as shown in FIG. 1, but the IGBT 7 and the second resonance capacitor 8 are replaced as shown in FIG. The configuration can be similarly implemented. The first resonance capacitor 6 can be connected in parallel to the first switching element IGBT 5 as shown in FIG. 5 or divided into two as shown in FIGS. 6a and 6b. The present invention can be similarly implemented. Further, as shown in FIG. 7, the first switching element can be similarly implemented by using a reverse current blocking type. [0013] As described above, according to the present invention, according to the invention of claim 1 Symbol placement, by inputting power control at a constant operating frequency, between the burner even when using multi-necked induction heating cooker And the switching element can perform a zero-volt switching operation, so that a high-frequency inverter having a low loss, low noise, and a simple configuration with a smaller number of components than the conventional one can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram of a high-frequency inverter according to an embodiment of the present invention. FIG. 2 is an operation waveform diagram of each part of the high-frequency inverter. FIG. 3 is an input power control characteristic diagram of the high-frequency inverter. FIG. 4 is another circuit configuration diagram of the high-frequency inverter. FIG. 5 is another circuit configuration diagram of the high-frequency inverter. FIG. 6 is another circuit configuration diagram of the high-frequency inverter. FIG. 8 is a circuit diagram of a conventional high-frequency inverter. FIG. 9 is an operation waveform diagram of each part of the high-frequency inverter. FIG. 10 is an input power control characteristic diagram of the high-frequency inverter. DESCRIPTION OF SYMBOLS 1 DC power supply 2 Inverter circuit 3 Control circuit 4 Coil 5 First switching element 6 First resonance capacitor 7 Second switching element 8 Second resonance capacitor

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Omori 1006 Oaza Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-5-343173 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 6/12 H05B 6/04

Claims (1)

(57) Patent Claims 1. A coil one end thereof connected to the positive side of the DC power source, My other end with the DC power supply of the coil
A first switching element connected to the eggplant side, a first resonance capacitor forming a resonance circuit with the coil, and a series connection of a reverse current conduction type second switching element and a second resonance capacitor connected in parallel with the coil. And a control circuit for controlling the conduction of the first switching element and the second switching element, and the control circuit controls the conduction of the switching elements alternately at a constant frequency,
A high-frequency inverter that changes the duty ratio of each switching element to control the input power.