JPH0246686A - induction heating device - Google Patents

Abstract

PURPOSE:To protect a high frequency inverter even if a supply voltage is lowered by providing a reference voltage setting means with a correction means for correcting detection level accordingly with the supply voltage. CONSTITUTION:A reference voltage setting means 7 is provided with a correction means 7a for correcting detection level accordingly with a supply voltage. The detection level Vk is set in low by the correction means 7a of the reference voltage setting means 7 to halt a high frequency inverter 9a when the supply voltage suddenly varies. The abnormality of the supply voltage is thus detected even if it is lowered. Therefore, the high frequency inverter 9a is halted only on the case that the high frequency inverter 9a should be protected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an induction heating device used as a cooker or heating device.

Conventional Technology In conventional induction heating devices, in order to protect the high-frequency inverter that supplies high-frequency current to the induction heating coil, it is common practice to detect sudden fluctuations in the power supply voltage and stop the high-frequency inverter. There is.

Fig. 6 shows an example of a circuit used in a conventional induction heating cooker.
t 2112411 Detected by the detection means 2 having a capacitor 2e, compared with a constant detection level Vr by the comparison means 3 having a comparator 3a, and when the power supply voltage a suddenly fluctuates, the output of the comparison means 3 is inverted and the high frequency inverter 4a Control was performed to send a stop signal to the induction heating circuit 4 having the following.

The waveforms of each a waveform are shown in Figure 6.

After rectifying the power supply voltage a with the rectifier 2a, the capacitor 2e
Since this bypasses the high frequency component, the detection voltage becomes as shown in b in Figure 6, and when this detection voltage reaches the detection level 71 or higher, the output of the comparison means 3 is reversed as in C in Figure 6, and induction heating occurs. It is sent to circuit 4 as a stop signal.

RM to be Solved by the Invention In the conventional configuration described above, the detection level vr is constant, and naturally remains constant even if the power supply voltage color changes.

Therefore, the conventional induction heating cooker has a problem in that when the power supply voltage suddenly fluctuates in a decreased state as shown in FIG. 7b, the abnormal voltage cannot be detected and the high frequency inverter cannot be protected.

The present invention solves the above-mentioned conventional problems, and aims to provide an induction heating device that can protect a high frequency inverter even when the power supply voltage drops.

Means for Solving the Problems In order to achieve this object, the induction heating apparatus of the present invention is such that the reference voltage setting means is provided with a correction means for correcting the detection level according to the power supply voltage.

Operation: Since the detection level is set according to the power supply voltage by the above-mentioned correction means, an abnormality in the power supply voltage can be detected even when the power supply voltage decreases.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
Figure 2 shows the first embodiment. In the figure, 6 is a power source for an induction heating circuit which will be described later, 6 is a power supply voltage detection means for detecting the power supply voltage, and includes a rectifier 61L, a resistor @
b, 60.6 (1, with capacitor 60 etc. and detection voltage 6
is set.

7 is a reference voltage setting means for setting the abnormal voltage detection level Vk of the power supply, and has a correction means 7a for correcting the detection level Vk according to the power supply voltage. 8 is a comparison means for comparing the detection voltage e and the detection level vk to detect an abnormal voltage, and 9 is an induction heating circuit having a high frequency inverter 91L.

The operation of the induction heating apparatus of this embodiment constructed as described above will be described below with reference to FIG. 2.

Figure 4 1 to C show the case where the power supply voltage a is high, Figure 2 d %
6 shows the case where the power supply voltage d is low. First, when the power supply voltage a is high, the detection level vk is set high by the correction means 7a of the reference voltage setting means 7.

When the power supply voltage a suddenly fluctuates as shown in FIG. 2a, the power supply voltage detection means 6 detects the output voltage S as shown in FIG. The comparison means 8 compares the detection voltage e and the detection level vk, and when e>111, the output C of the comparison means 8 becomes as shown in FIG. 2C, and in response to this signal, the induction heating circuit 9
stops the high frequency inverter 9a. Next, the power supply voltage d
When is low as shown in FIG. 2d, the correction means 7 & of the reference voltage setting means 7 sets the detection level vk low as shown in FIG. The high frequency inverter 9a is stopped when there is a sudden change. Furthermore, there is no need to protect the high frequency inverter 9a when the power supply voltage d changes suddenly near Ov, and the detected voltage e does not exceed the detection level vk and the high frequency inverter 9a stops.

As described above, according to this embodiment, by correcting the detection level vk by the correction means T& according to the power supply voltage,
Abnormalities in the power supply voltage can be detected even when the power supply voltage drops.
High frequency inverter 9! The high frequency inverter 91L can be stopped only when protection of the high frequency inverter 91L is necessary.

3 and 4 show the second embodiment, and in the figure 1o
11 is a power supply voltage detection means for detecting the power supply voltage, rectifier 12a1 resistor 12b
g 12 CI 1261 It has a diode 12d, capacitors 11a and 12f, and sets a detection voltage. 12 is a reference voltage setting means for setting the abnormal voltage detection level v6 of the power supply, which includes a rectifier 12a, a resistor to a resistor 12bl;
1201 12e, diode 12d, capacitor 1
It has 2f.

This reference voltage setting means 12 always sets the detection level ve higher than the detection voltage by the anode voltage of the diode 12d, and corrects the detection level V according to the power supply voltage. It also serves as a means. 13 is a comparison means for comparing the detection voltage and the detection level V to detect an abnormal voltage, and 14 is a high frequency inverter 141L.
It is an induction heating circuit with.

Regarding the induction heating device configured as above, the following is the fourth section.
The operation will be explained using figures.

Figure 4 1~C shows the case where the power supply room/pressure a is high.
C shows the case where the power supply voltage d is low. When the power supply voltage is a normal commercial frequency voltage, the detection voltage h and the detection level V are both connected to the power supply voltage a by the resistor 12b.

12C+12e is set to a value divided by the diode 12d, and the detection level We is always set higher than the detection voltage by the anode-cathode voltage of the diode 12d. Next, when the power supply voltage a suddenly fluctuates, the voltage detected via the capacitor 111L is greater than the detection level V, and when b>Ve (Fig. 4b), the high frequency inverter 14& stops. be done. Regardless of whether the power supply voltage is high or low, the detection level Va is set to a voltage higher than the detection voltage by a certain voltage, so it is high even when the power supply voltage d is low, as shown in Figure 4 d-f. The high-frequency inverter 14 can detect sudden changes in the power supply voltage d to the same extent as in the case of high-frequency inverter 14.
a can be protected.

As described above, according to this embodiment, with a simple configuration, even if the power supply voltage drops, abnormality in the power supply voltage can be detected and the high frequency inverter 14a can be protected.

Effects of the Invention As is clear from the above explanation, the present invention has advantages in that even when the power supply voltage drops, abnormalities in the power supply voltage can be accurately detected by correcting the detection level, and the high frequency inverter can be protected. This makes it possible to realize an induction heating device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an induction heating device according to an embodiment of the present invention, Fig. 2 is a waveform diagram of each part of the same, Fig. 3 is a circuit diagram of another embodiment, Fig. 4 is a waveform diagram of each part of the same, FIG. 5 is a circuit diagram of a conventional induction heating device, and FIG. 6 is a circuit diagram of a conventional induction heating device. FIG. 7 is a waveform diagram of each part. 6.1o...Power supply, 6,11...Power supply voltage detection means, 7,12...Reference voltage setting means, 7a...Correction means, 8 .13... Comparison means, 9,14... Induction heating circuit. Name of agent: Patent attorney Shigetaka Awano and one other person Figure 6...- k -... t Power source voltage detection means, lightning pressure setting means, correction means, and other means. Voltage inspection stage diagram

Claims (1)

[Claims] A power supply of the induction heating circuit, a power supply voltage detection means for detecting this power supply voltage, a reference voltage setting means for setting an abnormal voltage detection level of the power supply, and the voltages from the power supply voltage detection means and the reference voltage setting means are compared. , a comparison means for detecting an abnormal voltage, and the reference voltage setting means has a correction means for correcting a detection level according to a power supply voltage.