JPH02270290A - 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] Industrial applications The present invention relates to an induction heating cooker.

2. Description of the Related Art Conventionally, this type of induction heating cooker has a structure as shown in FIG.

That is, the inverter circuit consisting of the smoothing capacitor 203, the heating coil μ2o4, the resonant capacitor 205, and the switching element 206 and the control circuit 207 are connected by a GND line 209, and the GND line 209 drives the switching element 206 that constitutes the inverter circuit. In order to perform this stably, point 2 near the emitter of the switching element 206
It was taken from. In addition, 201 is a commercial AC power supply, 20
2 is a rectifier circuit, and 208 is a drive circuit within the control circuit 207.

Problems to be Solved by the Invention However, with such a configuration, there is a problem in that the control circuit 207 becomes a noise source and the noise terminal voltage increases. In particular, when a part of the control circuit is located away from the control circuit body and is connected with a long lead wire, such as the power setting/display unit of a built-in induction heating cooker (not shown), The problem of increased noise terminal voltage was significant.

In other words, since a high frequency current flows through loop 2 of the inverter circuit of the induction heating cooker for the heating coil/L'204 to generate a high frequency magnetic field, the control circuit 207 is Point 2, which is set as GND, has a potential that moves at a high frequency with respect to the ground (earth), and the control circuit 207 that functions as GND at these two points is a noise source, especially when the power of a built-in type induction heating cooker is increased. Connecting a part of the control circuit, such as a setting/display unit, away from the control circuit body using long lead wires will increase the noise source, and as a result, the noise terminal voltage will increase. there were.

Therefore, an object of the present invention is to reduce the noise terminal voltage caused by the control circuit as a noise source.

Means for Solving the Problems and In order to achieve the above object, the present invention provides a method in which, in addition to a GND line connecting an inverter circuit and a control circuit, the GND line of the inverter circuit and the control circuit is connected. Points with the same potential are connected through resistors.

Function The induction heating cooker of the present invention has a GND line connecting the vicinity of the emitter of the switching element of the inverter circuit and the GND of the control circuit, as well as a grounding line other than the loop portion through which high-frequency current flows on the inverter circuit side. By connecting the GND, which has a stable potential, and the GND of the control circuit through a relatively small resistance, the line connecting the GND of the inverter circuit and the GND of the control circuit through this relatively small resistance is This acts to stabilize the potential of GND on the control circuit side with respect to the ground, thereby weakening the effect of the control circuit as a noise source. As a result, even if a part of the control circuit is connected to the main body of the control circuit with a long lead wire, such as in the power setting/display unit of a via-in type induction heating cooker, the noise terminal voltage will be reduced. It is possible to suppress the increase.

Example An embodiment of the present invention will be described below with reference to FIG.

In Fig. 1, 1 is a commercial AC power supply, 2 is a rectifier circuit that rectifies the commercial AC power supply 1, 3 is a smoothing capacitor that smoothes the output of the rectifier circuit 2, 4 is a heating coil, 6 is a resonant capacitor, is a bipolar transistor which is a switching element, and the smoothing capacitor 3, heating coil 4, resonance capacitor 6, and bipolar transistor 6 constitute an inverter circuit. Further, 11 is a control circuit that controls the inverter circuit, T is the control circuit 110 main body part, 9 is a drive circuit included in the control circuit main body 7,
8 is a control circuit main body other than the drive circuit 9, and 1o is a power setting/display circuit which is a part of the control circuit located away from the control circuit main body. In addition, the GND is indicated by a thick solid line in the figure, and the GND of the inverter circuit and the GND of the control circuit are connected to the point d near the emitter of the bipolar transistor 6 and the GND point of the drive circuit 9 in the control circuit 11. In addition to the GND line 12 that connects the inverter circuit, a point d on the GND line that connects the point C other than the loop 1 through which the high-frequency current of the inverter circuit flows and the drive circuit 9 in the control circuit 11 and the control circuit main body 8 other than the drive circuit 9. 11A13, which connects the two through a relatively small resistance.

Next, the operation of the configuration of one embodiment will be explained.

When the induction heating cooker operates, loop 1 of the inverter circuit
A high frequency current flows through the loop 1, and the GND point on this loop 1 has a potential that moves at a high frequency with respect to the ground.
The control circuit 11 that operates with this ClNDO point a as a reference tends to become a noise source.

However, since the GND point C on the inverter circuit side, which has a stable potential with respect to the ground, is connected to the GND point d of the control circuit 11 by the wire 13 via a relatively small resistance, other than the drive circuit 9 The GND of the control circuit main body 8 and the power setting/display circuit has a stable potential with respect to the ground.

As a result, most parts of the control circuit 11 except the drive circuit 9 can become noise sources, and the noise terminal voltage does not increase as in the conventional case.

Effects of the Invention As described above, the present invention stabilizes the potential with respect to the ground of parts other than the GND line connecting the GND of the inverter circuit and the GND of the control circuit, as well as the part of the loop through which high-frequency current flows on the inverter circuit side. GND of the control circuit and GND of the control circuit
are connected through a relatively small resistance, so
Even when a part of the control circuit is used separately from the control circuit body, such as in a power setting/display unit of a built-in induction heating cooker, an increase in the noise terminal voltage can be suppressed. In addition, in order to stabilize the potential of the control circuit's GND with respect to the ground, the line connecting the inverter circuit's GND and the control circuit's GND is connected via a resistor, so the control circuit that drives the switching elements of the inverter circuit This also has the effect of preventing the route through which the drive current from the internal drive circuit flows by bypassing the line and destabilizing the drive of the switching element.

[Brief explanation of drawings]

FIG. 1 is a schematic circuit diagram of an induction heating cooker according to an embodiment of the present invention, and FIG. 2 is a schematic circuit diagram of a conventional induction heating cooker. 4... Heating coil, 11... Control circuit, 12... GND wire, 13... Resistor. Name of agent: Patent attorney Shigetaka Awano and 1 other person
1 figure
Figure 2

Claims (1)

[Claims] It has an inverter circuit including a heating coil and a control circuit for controlling the inverter circuit, and in addition to the GND line connecting the inverter circuit and the control circuit, the GND line of the inverter circuit and the control circuit is connected. An induction heating cooker that connects points with the same potential through resistors.