JP2001196156A - Induction cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the cost increase of an induction cooker having two heating coils without enlarging the scale of a circuit. SOLUTION: The induction cooker comprises heating coils 4, two inverter circuits 11a, 11b consist of a resonant capacitor (5) and a switching element 6, an input current detecting circuit 8 detecting the value of input current, a voltage detecting circuit 9 detecting the voltage of power source, and a microcomputer 10 which controls the oscillation of above inverter circuits 11a, 11b and inputs the values detected by the input current detecting circuit 8 and the voltage detecting circuit 9. Further, two oscillation circuits 7a, 7b are controlled so as to drive alternately by the microcomputer 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control of an induction heating cooker in which an eddy current is generated in a metal to be heated by an electromagnetic induction effect of an alternating magnetic flux, and the cooking is performed by Joule heat due to a specific resistance of the metal. It concerns the device.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional control device for an induction heating cooker having two heating coils divides a commercial power supply into two lines and rectifies each input commercial power supply with a respective rectifier circuit. Then, the rectified output is smoothed by each smoothing circuit to obtain a DC power supply. Also, an input current detection circuit is provided for each of the two commercial power supply lines to detect the current of each line.

[0003]

In a conventional control device, a rectifier circuit, a smoothing circuit, and an input current detection circuit are each provided with two components.
Since a circuit is required, the scale of the inverter circuit is large, and as a result, the entire product is also large. In addition, the circuit size is large, which causes an increase in cost.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention aims to construct an inverter circuit in a small space and at low cost without increasing the scale of the inverter circuit even in an induction heating cooker having two heating coils. Things. For this purpose, the present invention controls the oscillation circuits to be alternately driven by the microcomputer.

[0005] By doing so, the rectifier circuit, the smoothing circuit, and the input current detection circuit can each be constituted by one circuit.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a rectifier circuit for rectifying a commercial power supply, a smoothing circuit for smoothing the rectified output to obtain a DC power supply, a heating coil and a resonance capacitor for converting the DC power supply into an AC power, and Two inverter circuits consisting of switching elements, an input current detection circuit for detecting the value of the input current, a power supply voltage detection circuit for detecting the commercial power supply voltage, and an oscillation control of the inverter circuit, an input current detection circuit,
The induction heating cooker has a microcomputer for inputting a value detected by a power supply voltage detection circuit, and further controls the microcomputer to alternately drive two oscillation circuits.

The present invention provides a control device capable of reducing the circuit size and reducing the cost by using one rectifier circuit, one smoothing circuit, and one input current detection circuit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing one embodiment of the induction heating cooker of the present invention. FIG. 2 also shows control timings of two oscillation circuits in one embodiment.

In the figure, 1 is a commercial power supply, and 2 is a rectifier circuit for rectifying the commercial power supply 1. Reference numeral 3 denotes a smoothing circuit for smoothing the output after rectification and obtaining a DC power supply. Each of the rectifier circuit 2 and the smoothing circuit 3 is a single circuit.

4 is a heating coil, 5 is a resonance capacitor, 6
Is a switching element, and these heating coil 4, resonance capacitor 5, and switching element 6 constitute inverter circuits 11a and 11b. The inverter circuits 11a and 11b convert DC power into AC and are divided into two circuits.

Reference numerals 7a and 7b denote oscillation circuits for driving the respective switching elements 6 of the inverter circuits 11a and 11b, and have two circuits. Reference numeral 8 denotes an input current detection circuit that detects the value of the input current, and 9 denotes a power supply voltage detection circuit that detects a commercial power supply voltage. In addition,
Since there is one commercial power supply line, the input current detection circuit 8 is also one circuit.

Reference numeral 10 denotes a microcomputer which inputs values detected by the input current detection circuit 8 and the power supply voltage detection circuit 9 and controls the oscillation of the inverter circuits 11a and 11b. The microcomputer 1
0 controls the two oscillation circuits 7a and 7b so that they are alternately driven. By performing such control, each of the rectifier circuit 2, the smoothing circuit 3, and the input current detection circuit 8 can be constituted by one circuit.

Referring to FIG. 1, a microcomputer 10
As shown in FIG. 2, the control timing of the oscillation circuits 7a and 7b controls the oscillation circuit 7a at T1 and controls the oscillation circuit 7b at T2.

The value input by the input current detection circuit 8 while controlling the oscillation circuit 7a is used as a current value.
The value input by the power supply voltage detection circuit 9 is defined as a voltage value,
The microcomputer 10 calculates the power value. The obtained power value is used for power correction of the inverter circuit 11a.

The value input by the input current detection circuit 8 while controlling the oscillation circuit 7b is used as a current value.
The value input by the power supply voltage detection circuit 9 is defined as a voltage value,
The microcomputer 10 calculates the power value. The obtained power value is used for power correction of the inverter circuit 11b.

By inputting a current value at the above timing, two input current detection circuits 8 are provided as shown in FIG.
Is unnecessary, and one input current detection circuit 8 is often unnecessary. Further, by using the input current detection circuit 8 that has become one, the commercial power supply line which is required two as shown in FIG. 3 can be reduced to one line. By using one commercial power supply line, only one rectifying circuit 2 and one smoothing circuit 3 are required.

[0017]

According to the present invention, by controlling two inverter circuits to be alternately driven by a microcomputer, only one rectifying circuit, a smoothing circuit, and an input current detecting circuit can be used, and two heating circuits can be used. Also in the induction heating cooker having a coil, an inverter circuit can be configured without reducing the circuit scale and in a small space, and without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an induction heating cooker according to an embodiment of the present invention.

FIG. 2 is a diagram showing control timings of two oscillation circuits.

FIG. 3 is a circuit diagram of an induction heating cooker in a conventional example.

[Explanation of symbols]

 1: Commercial power supply 2: Rectifier circuit 3: Smoothing circuit 4: Heating coil 5: Resonant capacitor 6: Switching element 7a: Oscillator circuit 7b: Oscillator circuit 8: Input current detection circuit 9: Power supply voltage detection circuit 10: Microcomputer 11a: Inverter circuit 11b: Inverter circuit

Claims (4)

[Claims] 1. A rectifier circuit (2) for rectifying a commercial power supply (1), a smoothing circuit (3) for smoothing an output after rectification to obtain a DC power supply, and a heating coil (2) for converting the DC power supply to AC. 4) and two inverter circuits (11a), (1) composed of a resonance capacitor (5) and a switching element (6).
1b), an input current detection circuit (8) for detecting an input current value, a power supply voltage detection circuit (9) for detecting a commercial power supply voltage, and the inverter circuits (11a) and (11b).
And a microcomputer (10) for inputting values detected by an input current detection circuit (8) and a power supply voltage detection circuit (9), and further comprising two oscillation circuits ( An induction heating cooker characterized by controlling to alternately drive 7a) and (7b). 2. The induction heating cooker according to claim 1, wherein the rectifier circuit for rectifying the commercial power supply is a single circuit. 3. The induction heating cooker according to claim 1, wherein a smoothing circuit (3) for smoothing the output after rectification and obtaining a DC power supply is provided as one circuit. 4. An input current detection circuit (8) detects at a timing when each of the inverter circuits (11a) and (11b) is controlled, and inputs it to a microcomputer (10) to detect the input current. 2. The induction heating cooker according to claim 1, wherein the circuit (8) is a single circuit.