KR20090005142U - Induction heating cooker - Google Patents

Abstract

The present invention relates to an induction heating cooker, and an object of the present invention is to implement a full bridge inverter circuit using an idle half bridge inverter circuit to improve output capacity and improve the life of the switching element in the inverter circuit. In providing a cooker.

To this end, the induction heating cooker according to the present invention is a rectifying unit for rectifying the input AC power to DC power; First and second half bridge inverters that switch the DC power to provide a resonance voltage; First and second induction coils receiving the resonance voltage and inducing eddy currents in a magnetic container to heat the magnetic container; A first switching element connecting the first induction coil and the first half bridge circuit; A second switching element connecting the second induction coil and the second half bridge circuit; A third switching element and a resonant capacitor connecting the first and second half bridge circuits; First and second detectors configured to detect whether the magnetic container exists on top of the first and second induction coils; And an induction heating cooker including a control unit for controlling the first to third switching elements according to the sensing result of the first and second sensing units.

Induction Cooker, Half Bridge Inverter, Full Bridge Inverter

Description

Induction heating cooker

The present invention relates to an induction heating cooker, and more particularly, to an induction heating cooker using a half bridge inverter circuit.

Induction heating is a heating method that uses a phenomenon in which a secondary current (induction current) flows in a metal when the magnetic field is changed by winding a primary coil around the metal to be heated first. Occurs and the metal becomes hot. Induction heating cooker refers to a cooker such as a rice cooker made using this induction heating phenomenon.

That is, the induction heating cooker generates a strong magnetic field in the induction coil by rectifying commercial power and switching the rectified power to generate an intense magnetic field, and heat the metal to be heated to cook food by using the magnetic field. One device.

Switching transistors are used for switching induction coils in induction cookers. In particular, induction heating cookers generate large resonant voltages and resonant currents when switching rectified power, so high-speed switching to semiconductor devices is possible. Insulated Gate Bipolar Transistors (IGBTs) are widely used in PWM control inverters. Use

Induction hobs (or induction cooktops), one of such induction heating cookers, are generally equipped with two induction modules (2, 3) as shown in FIG. One induction module (hereinafter described with reference to the first induction module 2) is provided with two cooking tools 4A and 4B, and one induction coil and one to operate each cooking device. Requires an inverter circuit. That is, one induction module 2 consists of two induction coils L1 and L2 and two inverter circuits 40A and 40B. There are many types of inverter circuits, but the induction hob 1 usually uses a half bridge inverter 40A composed of two switching elements S1 and S2 and two resonant capacitors C1 and C2.

As described above, although two cooking utensils are provided in one induction module, it is extremely rare for actual users to use two cooking utensils at the same time, and most of them use only one cooking utensil. Therefore, there is a need for a discussion on how to effectively use the inverter circuit that is not operating on the cooking utensil side that is not used.

Accordingly, the present invention is to solve the above problems (the existence of an unused inverter circuit), an object of the present invention is to improve the output capacity by implementing a full bridge inverter circuit using an idle half bridge inverter circuit The present invention provides an induction heating cooker having an improved lifetime of a switching device in an inverter circuit.

Induction heating cooker according to the present invention for achieving the above object is a rectifying unit for rectifying the input AC power to DC power; First and second half bridge inverters that switch the DC power to provide a resonance voltage; First and second induction coils receiving the resonance voltage and inducing eddy currents in a magnetic container to heat the magnetic container; A first switching element connecting the first induction coil and the first half bridge circuit; A second switching element connecting the second induction coil and the second half bridge circuit; A third switching element and a resonant capacitor connecting the first and second half bridge circuits; First and second detectors detecting whether the magnetic container exists on top of the first and second induction coils; And a controller for controlling the first to third switching elements according to the sensing results of the first and second sensing units.

The first and second half bridge inverters are each composed of two switching elements and two resonant capacitors.

In addition, if it is determined that the magnetic container is present on the first and second induction coils, the controller short-circuits the first and second switching elements and controls the third switching element to be opened.

The controller controls the first and second switching elements to be opened and the third switching elements to be shorted when it is determined that the magnetic container exists only on the upper side of either the first or second induction coil.

According to the present invention, by implementing a full bridge inverter circuit using an idle half bridge inverter circuit, an improvement in output capacity and lifespan of a switching device in the inverter circuit can be obtained.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2 to FIG. 5 to be described below, the same parts as in FIG. 1 are denoted by the same reference numerals.

Induction heating cooker according to an embodiment of the present invention as shown in Figure 2 (hereinafter, one induction module (the first induction module 2 in Figure 1, two cooking spheres (4A, 4B)) The rectifier 20, the smoothing unit 30, the two half bridge inverters 40A and 40B, the sensing units 50A and 50B, the control unit 60, and the three switching elements SW1, SW2, SW3) and one resonant capacitor Cr.

That is, the induction heating cooker according to the present embodiment is configured by adding three switching elements (SW1, SW2, SW3) and one resonant capacitor (Cr) to the existing circuit shown in FIG. 1 (here, the added configuration Elements are represented by dotted circles).

The rectifier 20 rectifies the input AC power supply 10 and outputs the rectified pulsating voltage.

The smoothing unit 30 smoothes the pulsation voltage provided from the rectifying unit 20 and outputs a constant DC voltage obtained by smoothing.

The first half bridge inverter 40A includes a driving unit 45A for switching the switching elements S1 and S2 according to a control signal of the control unit 60 and a DC voltage provided from the smoothing unit 20 to the driving unit 45A. Resonant capacitors continuously resonating with the induction coil L1 by switching voltages S1 and S2 for switching in response to a switching control signal to provide a resonant voltage and a voltage input in series between the electrostatic terminal and the sub-power terminal. (C1, C2) is provided.

At this time, the induction coil (L1) is connected between the switching elements (S1, S2) and induces an eddy current in the cooking vessel (A) made of a magnetic body by the resonance voltage input from the rectifier 20 to prepare the cooking vessel (A) Heat.

The sensing unit 50A detects whether a magnetic substance (ie, a cooking vessel) is present on the induction coil L1, and provides the detection result to the controller 60.

Since the configurations of the second half bridge inverter 40B and the sensing unit 50B are the same as those of the first half bridge inverter 40A and the sensing unit 50A, the description thereof is omitted here.

In addition, in the present embodiment, as shown in FIG. 2, the first switching element is connected between the induction coil L1, the connection point of the resonant capacitor C1, and the resonant capacitor C2, and the switching element S3 and the switching element ( The second switching element SW2 is connected between the connection point of S4 and the induction coil L2. The third switching element SW3 and the resonance capacitor Cr are connected between the front end of the first switching element SW1 and the front end of the second switching element SW2.

The control unit 60 performs overall control of the induction heating cooker, using only one of the two cooking ports 4A and 4B provided in the induction module 2 using the detection results provided by the sensing units 50A and 50B. Or determine if both are being used. If it is determined that the user is using both cooking utensils, the control unit 60 sends a control signal to the first to third switching elements SW1, SW2, and SW3 to short-circuit SW1 and SW2, and to open SW3. To control.

On the other hand, if it is determined that the user is using only one cooking tool, the controller 60 sends control signals to the first to third switching elements SW1, SW2, and SW3 to open the SW1 and the SW2, and short-circuit the SW3. To control.

FIG. 3 is a circuit diagram when both cooking tools provided in the induction module are used. In FIG. 2, SW1 and SW2 are short-circuited and SW3 is controlled to open. In this case, the configuration and operation are the same as in the case of using two conventional half-bridge inverter circuits as shown in FIG. 1, and the controller 60 controls the two half-bridge inverters 40A and 40B separately, The boost function (a function that outputs high power in a short time so that the food can be cooked in a short time) is also controlled to operate for each cooking device (inverter).

Here, the operation of one inverter 40A of the two half bridge inverters 40A and 40B will be briefly described (the other inverter 40B is also the same as the operation below). First, when a cooking command is input through the control panel (refer to reference numeral 5 in FIG. 1), the driving unit 45A alternately generates a switching control signal for operating only one of the switching elements S1 and S2. For example, when the switching element S1 is turned on and the switching element S2 is cut off, a circuit composed of the switching element S1-induction coil L1-resonant capacitor C2 as the path indicated by ① in FIG. Is composed. On the other hand, when the switching element S2 is turned on and the switching element S1 is cut off, a circuit composed of a resonant capacitor C1-> induction coil L1-> The resonance voltage is provided to the coil L1. At this time, since the induction coil L1 and the resonant capacitors C1 and C2 are continuously in a resonance state, a large resonance current flows through the induction coil L1.

As a result of the resonance current, a high frequency magnetic field is generated in the induction coil L1, and an eddy current is induced in the container A due to electromagnetic induction by the high frequency magnetic field. do.

FIG. 4 is a circuit diagram when only one of two cooking tools of the induction module is used. In FIG. 2, SW1 and SW2 are opened, and SW3 is shorted. In this case, the induction module as a whole becomes one full bridge inverter circuit 40C including four switching elements S1 to S4 and one resonant capacitor Cr, and one induction coil L1 and the cooking port 4A. Will only work.

Here, the operation when one full bridge inverter circuit 40C is configured will be briefly described. At this time, the driving units 45A and 45B alternately generate a switching control signal for operating only one of the switching elements S1 and S4 or the switching elements S2 and S3. For example, if the switching elements S1 and S4 are turned on and the switching elements S2 and S3 are cut off, the switching element S1 induction coil L1 resonant capacitor Cr switching element as shown by e. A circuit composed of S4 is configured. On the other hand, when the switching elements S3 and S2 are connected and the switching elements S1 and S4 are cut off, the switching element S3 → resonant capacitor Cr → induction coil L1 → switching element S2 is formed as shown in the path ④. A circuit is constructed to provide a resonant voltage to the induction coil L1.

As shown in FIG. 4, when the half bridge inverter circuit 40B which has stopped operation is connected to the half bridge inverter circuit 40A which is operating, and implement | achieves one full bridge inverter circuit 40C, an output capacity (maximum output Power) increases (for example, if the output capacity when used as a half bridge inverter is 1000W, the output capacity when used as a full bridge inverter is 2000W), and the user can produce higher output when the boost function is selected. There is an advantage that the cooking of the food can be cooked in a faster time than the boost function when using the inverter.

In addition, if the half-bridge inverter and the full-bridge inverter wants to output the same output, for example, if both of them want to output 2000W, the two switching elements have to cover 2000W in the half-bridge inverter, whereas in the case of the full-bridge inverter Since four switching elements cover 2000W, the burden on the switching element is reduced by half, thereby improving the life of the switching element.

2 is a circuit configuration for implementing a full bridge inverter on the side of the first cooking zone 4A when the first cooking zone 4A is used and the second cooking zone 4B is not used. In the case of using the second cooking tool 4B without using 4A, a circuit for implementing a full bridge inverter on the side of the second cooking tool 4B can be configured as shown in FIG. 5.

1 is a driving circuit of a general induction heating cooker.

2 is a driving circuit of the induction heating cooker according to the first embodiment of the present invention.

3 is a circuit diagram when using both cooking utensils of the induction module.

4 is a circuit diagram when only one of two cooking tools of the induction module is used.

5 is a driving circuit of an induction heating cooker according to a second embodiment of the present invention.

* Description of symbols on the main parts of the drawings *

1: Induction heating cooker (induction hob) 2, 3: First and second induction module

4A, 4B: 1st and 2nd cookware 5: Control panel

10: AC power source 20: rectifier

30: smooth part

40A, 40B: first and second half bridge inverter

40C: Full Bridge Inverter

45A, 45B: drive unit 50A, 50B: detection unit

60: control unit L1, L2: induction coil

SW1, SW2, SW3: first, second and third switching elements

C1 ~ C4, Cr: Resonant Capacitor

Claims (4)

A rectifier for rectifying the input AC power into a DC power source; First and second half bridge inverters that switch the DC power to provide a resonance voltage; First and second induction coils receiving the resonance voltage and inducing eddy currents in a magnetic container to heat the magnetic container; A first switching element connecting the first induction coil and the first half bridge circuit; A second switching element connecting the second induction coil and the second half bridge circuit; A third switching element and a resonant capacitor connecting the first and second half bridge circuits; First and second detectors configured to detect whether the magnetic container exists on top of the first and second induction coils; Induction heating cooker including a control unit for controlling the first to third switching elements in accordance with the detection results of the first and second sensing unit The method of claim 1, The first and second half bridge inverters are induction heating cookers each composed of two switching elements and two resonant capacitors. The method of claim 1, When the controller determines that the magnetic container exists on the first and second induction coils, the controller short-circuits the first and second switching elements and controls the third switching elements to be opened. The method of claim 1, The control unit, if it is determined that the magnetic container exists only on the upper side of either the first or second induction coil, the induction heating to control the first and second switching elements to open and the third switching element to short-circuit. Cooker

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