JPS61284085A - Induction heating cooker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an induction heating cooker for general household use.

2. Description of the Related Art Conventionally, as shown in FIG. 3, this type of induction heating cooker includes an AC power source 1, a rectifier 2, an inverter 3 that generates high-frequency power, and a control circuit 4 that controls the inverter 3. , a fan motor 5 connected in series to the power input terminal of the control circuit 4 , and a power supply circuit 6 that supplies DC power to the control circuit 4 and the fan motor 5 . and a rectifier 8.

Problems to be Solved by the Invention However, in the conventional configuration described above, if the fan motor 5 fails and the wire is disconnected, power is not supplied to the control circuit 4, so the control circuit 4 does not operate normally, resulting in severe problems. In this case, there was a problem that the inverter 3 would be destroyed.

The present invention solves the above-mentioned conventional problems, and even if the fan motor is disconnected, power is supplied to the control circuit, thereby preventing the control circuit from malfunctioning, and ensuring high reliability of the induction wire. The purpose is to provide heated cooking.

Means for Solving the Problems In order to solve the above problems, the induction heating cooker of the present invention includes an inverter that generates high-frequency power, a control circuit that controls the inverter, and a power input terminal of the control circuit. This configuration includes fan motors connected in series and a disconnection conduction circuit that detects disconnection of the fan motor and short-circuits input terminals of the fan motors.

According to the above configuration, when the fan motor breaks down and is disconnected, the disconnection conduction circuit becomes conductive, so power is supplied to the control circuit and it can operate normally.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 is a circuit diagram of an induction heating cooker according to a first embodiment of the present invention, in which 11 is an AC power source, 12 is a rectifier, 13 is an inverter that generates high-frequency power, and 14 is a control circuit that controls the inverter 13. , 15 is a fan motor connected in series to the power input terminal of the control circuit 14; 16 is a power supply circuit that supplies DC power to the control circuit 14 and the fan motor 15; It is made up of.

19 is the fan motor 1 when the fan motor 15 is disconnected.
This circuit short-circuits the input terminals of the circuit 5 and is made up of a thyristor 20, a Zener diode 21, and a resistor 22.

In the above configuration, if the fan motor 15 breaks down and is disconnected, the voltage at both ends of the fan motor 15 increases,
When V' further increases beyond the Zener voltage of the Zener diode 21, a gate current flows through the thyristor 20 and the thyristor 20 is turned on.

When the thyristor 20 is turned on, the power input terminal of the control circuit 14 is connected to the output terminal of the power supply circuit 16, so that the control circuit 14 can operate normally.

FIG. 2 is a circuit diagram of an induction heating cooker according to a second embodiment of the present invention, in which 11 is an AC power source, 12 is a rectifier, 13 is an inverter that generates high-frequency power, and 14 is a control circuit that controls the inverter 13. , 15 is a fan motor connected in series to the power input terminal of the control circuit 14, and 16 is a power supply circuit that supplies DC power to the control circuit 14 and the fan motor 15. the power supply circuit 16 beam handle 23; a Zener diode 24 for generating a reference voltage; a resistor 25 for supplying current to the Zener diode 24;
A transistor 26, a resistor 27 that drives the base of the transistor 26, a resistor 28, a transistor 29 that controls on/off of the transistor 26 by the reference voltage of the Zener diode 24, and switching of the transistor 26 and the transistor 29. It is composed of resistors 30 and 31 for generating hysteresis to ensure the above, and a flywheel diode 32 that circulates the current of the reactor 23 while the transistor 26 is off. Reference numeral 19 denotes a conduction circuit when the circuit is disconnected, and is composed of a thyristor 20, a Zener diode 21, and a resistor 22.

33 is a capacitor.

In the above configuration, the voltage of the Zener diode 24 is
, assuming that the power supply voltage of the control circuit 14 is v2, the transistors 26 and 29 switch so that (2) becomes approximately the same voltage as Vl. That is, when v2 decreases, transistor 29 and transistor '2
When V2 turns on and v2 increases, transistor 29 and transistor 26 turn off and V2 decreases. When the fan motor 15 is not disconnected, the capacitor 32 reduces the ripple in the terminal voltage Vr of the fan motor 15.
It works to reduce noise and stabilize rotation. When the fan motor 15 malfunctions and is disconnected, ■1 exceeds the Zener voltage of the Zener diode 21, gate current flows to the thyristor 20, and the thyristor 20 turns on.
Ru. By turning on the thyristor 20, ■2 can obtain a stable voltage almost equal to ■1, as before the fan motor 15 was disconnected, and since V' becomes almost O, a high voltage is applied to the capacitor 33. can be prevented from being applied.

In this way, in the second embodiment, even when the fan motor 15 is disconnected, the power supply voltage 2 of the control circuit 14 can be kept at the same value as before the disconnection, so the control circuit 14 can operate normally. Further, the voltage between the terminals of the capacitor 33 can be prevented from becoming abnormally high when the fan motor 15 is disconnected, and the capacitor 33 can be prevented from being destroyed.

In each of the embodiments described above, disconnection of the fan motor 15 is detected by an increase in the voltage between the terminals of the fan motor 15, but it may also be detected by the current or rotational speed of the fan motor 15.

Effects of the Invention As described above, according to the present invention, a disconnection continuity circuit is provided which short-circuits the input terminals of the fan motor when the fan motor connected in series to the power input terminal of the control circuit is disconnected. Even if the circuit breaks down and is disconnected, power can be supplied to the control circuit and the control circuit can be prevented from malfunctioning, greatly improving reliability.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an induction heating cooker according to a first embodiment of the present invention, Fig. 2 is a circuit diagram of an induction heating cooker according to a second embodiment of the present invention, and No. 31ffl is a circuit diagram of an induction heating cooker according to a second embodiment of the present invention. FIG.

Claims (1)

[Claims] 1. An inverter that generates high-frequency power, a control circuit that controls this inverter, a fan motor that is connected in series to the power input terminal of this control circuit, and a disconnection of the fan motor that is detected and the input terminal of the fan motor An induction heating cooker equipped with a conduction circuit in the event of a disconnection, which short-circuits between the two.