KR100253558B1 - Induction heating cooker for magnetic and nonmagnetic loads - Google Patents

Abstract

PURPOSE: An induction heating cooking device with magnetism and non magnetism is provided to reduce a manufacturing cost by using a single inverter to control a plurality of load. CONSTITUTION: An induction heating cooking device with magnetism and non magnetism comprises a voltage branch portion(101), a heating portion(102), the first switching portion(103), and the second switching portion(104). The voltage branch portion(101) is formed with the first and the second filter capacitors(Cf1, Cf2). The heating portion(102) heats a plurality of heating plates. The first switching portion(103) selects a predetermined resonant circuit. The second switching portion(104) provides a power for heating a heating vessel.

Description

Magnetic and nonmagnetic induction cookers

The present invention relates to a magnetic and nonmagnetic combined induction heating cooker, and more particularly to a magnetic and nonmagnetic combined induction heating cooker to control a plurality of loads with a single inverter to minimize the cost and size of the system.

As shown in FIG. 1, a conventional multi-output type induction heating cooker includes a plurality of inverters 10-1 and 10-2 connected in parallel to an AC power source.

Each of the inverters 10-1 and 10-2 uniformly smoothes the rectified DC power rectified by the bridge rectifier circuit 11 and the rectified AC power through the bridge rectifier circuit 11. LC smoothing circuit 12 composed of filter inductor L _f and filter capacitor C _f , and working coil L _r and resonant capacitor C _r for resonating the output voltage of LC smoothing circuit 12. First and second switches S1 and S2, which are switched according to the LC resonant circuit 13 and the control signal input from the outside, to supply power to the working coil L _r to perform a heating operation. It consists of.

In the drawings, reference numerals D1 and D2 denote damping diodes for improving bandwidth and phase characteristics of the LC resonant circuit 13.

Referring to Figure 1 attached to the operation of the conventional multi-output induction heating cooker configured as described above are as follows.

First, the AC power source AC is rectified to the pulsating DC voltage through the bridge rectifier circuit 11 provided in each of the inverters 10-1 and 10-2, and then the filter inductor L _f and the filter capacitor C _f. It is smoothed uniformly by the LC smoothing circuit 12 which consists of).

At this time, when the second switch S2 is turned on according to the control signal and the output voltage of the LC smoothing circuit 12 is input to the LC resonance circuit 13, the current flowing through the working coil L _r is caused by resonance. is increased is charged with the resonance capacitor (C _r).

And, a certain time after the charging energy is discharged working coil of the second switch (S2) is off, (Off) as soon at the same time the first switch (S1) is turned on (ON) the resonant capacitor (C _r) according to a control signal ( The current flows in the reverse direction to L _r ).

In other words, this is repeated the same switch, but heating the working coil (L _r) the first and second switch is turned on (S1, S2) - on-time, that is, by changing the duty (Duty) ratio working coil (L _r) Control the current flowing through it.

Therefore, when the above charging and discharging operation is repeated at a high frequency above the audible frequency, the heating vessel on the heating plate (not shown) is omitted due to the electromagnetic induction effect due to the magnetic field generated from the working coil L _r . ), The appropriate output is passed.

However, such a conventional multi-output induction heating cooker generates interference noises due to the difference in operating frequency between adjacent heating plates according to the size and material of each heating vessel, which makes it difficult to control the output of the working coil, as well as separate control circuits. Inverter having a power supply to each one induction heating coil has a problem that the size and cost of the system is increased.

Therefore, the present invention has been proposed to solve the above problems of the prior art, to provide a magnetic and nonmagnetic combined induction heating cooker to minimize the cost and size of the system by controlling a plurality of loads with a single inverter. have.

Technical means of the present invention for achieving the above object is a voltage branch means for branching the input voltage through a plurality of filter capacitors, a plurality of resonant circuits consisting of a plurality of working coils and a single resonant capacitor by a voltage branch means. Heating means for resonating the branched input voltage to heat the plurality of heating vessels, and the plurality of relay elements form a resonant circuit together with the plurality of resonant circuits. Among the coils, a first switching means for selecting a predetermined resonant circuit in which a predetermined working coil operates to heat the heating vessel, and a plurality of switch elements in multiples of the number of relay elements are alternately switched and heated according to a control signal input from the outside. The means consists of a second switching means for supplying power to heat the heating vessel. The features.

1 is a circuit diagram of a conventional multi-output type induction cooker.

Figure 2 is a circuit diagram of a magnetic and nonmagnetic combined induction heating cooker according to the present invention.

3 and 4 is a waveform diagram of the current voltage according to the operation of the induction heating cooker shown in FIG.

5 is a circuit diagram of a magnetic and nonmagnetic combined induction heating cooker according to another embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

101: voltage branch 102: heating portion

103: first switching unit 104: second switching unit

Hereinafter, the present invention will be described with reference to the accompanying drawings.

2 is a circuit diagram of a magnetic and nonmagnetic combined induction heating cooker according to the present invention, and includes a voltage branch unit 101 including first and second filter capacitors C _f1 and C _f2 for branching an input voltage. The resonance capacitor C _r and the plurality of working coils L _r11 , L _r12 , L _r21 , and L _r22 form a plurality of resonant circuits to resonate the input voltage branched through the voltage branch unit 101, thereby providing a plurality of resonant circuits. A heating unit 102 for heating a heating vessel (not shown) on a heating plate (not shown) and a plurality of heating units 102 form a resonant circuit together with the heating unit 102. Relays Ry1 and Ry2 are switched to select a predetermined resonant circuit in which a predetermined working coil forms a resonant circuit among the plurality of working coils L _r11 , L _r12 , L _r21 , and L _r22 among the plurality of resonant circuits. To the first switching unit 103 and the control signal input from the outside. The first to fourth switches (S1~S4) is referred to switching the first to fourth damping diode (D1~D4) is a respective anti-parallel connected as well as the first to fourth auxiliary resonant capacitor (C _a1 ~C _a4) Each of the heating units 102 includes a second switching unit 104 connected in parallel and supplying power to heat the heating vessel according to a switching action.

Referring to Figures 2 and 5 attached to the operation and effect of the present invention configured as described above are as follows.

First, when the AC power source is rectified by a pulsating DC voltage by a bridge rectifying circuit (not shown) and is smoothed uniformly through an LC smoothing circuit (not shown), the input of the voltage branch unit 101 is performed. The first and second filter capacitors C _f1 and C _f2 branch off the input voltage.

At this time, of a plurality of resonant circuit of the heating unit 102, the first and second working coil (L _r11, L _r12) and the resonant capacitor (C _r) by using a composed resonant circuit when you want to heat the non-magnetic load, As shown in the switching states and current voltage waveforms of the first to fourth switches S1 to S4 illustrated in FIG. 3, the plurality of relays Ry1 of the first switching unit 103 are controlled by an operation mode control signal input from the outside. The first relay Ry1 of the Ry2 is turned off and the second relay Ry2 is located at the contact point 1 to select the first and second working coils L _r11 and L _r12 .

The second and third switches S2 and S3 of the second switching unit 104 are turned off and the first and fourth switches S1 and S4 are turned on by a control signal input from the outside. second working coil (L _r11, L _r12) and the resonant capacitor (C _r) is when the accomplished input voltage (Vd) is applied to a series resonant circuit to start the resonance by the first, second working coil (L _r11, L _r12 The current flowing through) rises linearly.

Thereafter, when the first and fourth switches S1 and S4 are turned off before the resonant half-cycle passes, the first to fourth auxiliary resonance capacitors C _{a1 to} C _a4 and the first and second working coils L _r11 and L _{r12 are turned off.} ) And the resonant capacitor C _r are subjected to auxiliary resonance so that the voltages of the second and third auxiliary resonance capacitors C _a2 and C _a3 drop from Vd to 0, and the first and fourth auxiliary resonance capacitors C _a1 The voltage at, C _a4 ) rises from 0 to Vd.

And, second, and third switch (S2, S3) of the damping diode (D2, D3) is conducting the first and second working coil (L _r11, L _r12) and the resonant capacitor (C _r) that forms the resonance circuit has input voltage Vd is applied in the reverse takes place by a voltage charged to the input voltage Vd and the resonant capacitor (C _r) continued resonance.

At this time, when the second and third switches S2 and S3 are turned on under the zero voltage condition, the resonance current drops to zero due to the continuous resonance, and this time, the resonance current increases in the opposite direction.

If the second and third switches S2 and S3 are turned off before the resonant half cycle passes, the first to fourth auxiliary resonance capacitors C _{a1 to} C _a4 and the first and second working coils L _r11 and L _{r12 are turned off.} ) And the resonant capacitor C _r again perform auxiliary resonance, so that the voltages of the first and fourth auxiliary resonance capacitors C _a1 and C _a4 drop from Vd to 0, while the second and third auxiliary resonance capacitors C The voltage of _a1 , C _a4 ) rises from 0 to Vd.

Then, the first and fourth switch (S1, S4) a damping diode (D1, D4) is conducting the first and second working coil (L _r11, L _r12) and the resonant capacitor (C _r) that is to make up the resonant circuit of the When the input voltage Vd is applied, resonance continues.

At this time, when the first and fourth switches S1 and S4 are turned on under the zero voltage condition, the resonant current drops to zero due to the continuous resonance, thereby ending one cycle of operation and repeating the cycle operation.

In this way, magnetic flux is generated by currents induced in the first and second working coils L _r11 and L _r12 , and the magnetic flux is heated by linking with a heating vessel (not shown) on a heating plate (not shown). Eddy current is generated at the bottom of the container. Therefore, the heating vessel is heated by Joule heat caused by this eddy current.

Next, when the magnetic load is to be heated, the third and fourth switches S3 and S4 are turned off, as shown in the switching states and current voltage waveforms of the first to fourth switches S1 to S4 shown in FIG. 5. In this state, the first and second switches S1 and S2 operate alternately, but the first relay Ry1 is positioned at the contact point 1, and the second relay Ry2 is turned off so that only the first working coil L _r11 is selected. Therefore, it operates as a half bridge.

If above, the second switch (S2) by a control signal inputted from the outside when the first switch (S1) is turned on at the same time as off the first working coil (L _r11) and the resonant capacitor (C _r) has a series of resonant circuit When half of the input voltage Vd / 2 is applied, the resonance starts to linearly increase the current flowing in the first working coil L _r11 .

Thereafter, when the magnitude of the current flowing through the first working coil L _r11 reaches a set value and the first switch S1 is turned off under the condition of zero voltage by a control signal input from the outside, the second auxiliary resonance capacitor _{Ca a2} ) Drops from Vd to zero.

When the voltage of the second auxiliary resonance capacitor _{Ca a2} becomes 0, the damping diode D2 of the second switch S2 is turned on, and the current flowing in the first working coil L _r11 decreases linearly. .

At this time, when the second switch S2 is turned on under the condition of the zero voltage by a control signal input from the outside, the current flowing through the first working coil L _r11 drops to zero and then increases in the opposite direction. When this current reaches the set value, the second switch S2 is turned off under the condition of zero voltage by a control signal input from the outside.

Then, when the voltage of the first auxiliary resonance capacitor _{Ca a1} decreases from Vd to 0, and the voltage of the second auxiliary resonance capacitor _{Ca a2} becomes 0, the damping diode D1 of the first switch S1 is turned on. In addition, the current flowing in the first working coil L _r11 is linearly increased.

Then, when this current becomes zero, one resonance period ends and the above-described resonance operation is repeated.

Table 1 below shows the working circuit and the resonant working coil according to the switching state and the heating operation mode of the first and second relays.

Relay status Operation mode Circuit method Operation coil Ry1 = 1, Ry2 = 0 Magnetic mode Half bridge L _r11 Ry1 = 0, Ry2 = 1 Nonmagnetic mode Full Bridge L _r11 + L _r12 Ry1 = 2, Ry2 = 0 Magnetic mode Half bridge L _r21 Ry1 = 0, Ry2 = 2 Nonmagnetic mode Full Bridge L _r21 + L _r22

In other words, the heating element first of a plurality of resonance circuits (102) third, fourth working coil (L _r21, L _r22) and the resonant capacitor (C _r) by using a composed resonant circuit, if you want to heat the non-magnetic load The first relay Ry1 of the plurality of relays Ry1 and Ry2 of the first switching unit 103 is turned off by the operation mode control signal input from the outside, and the second relay Ry2 is connected to the contact 2. 3rd and 4th working coils L _r21 and L _r22 are selected so that they are operated in a full bridge, and when the magnetic load is to be heated, the first relay Ry1 is located at the contact point 2 and the second relay ( Ry2 is turned off so that the third working coil L _r21 is selected to operate as a half bridge.

5 is a resonant capacitor of Figure 4 as compared to the circuit diagram of the induction heating cooker shown in as shown a circuit diagram of the magnetic and non-magnetic Combine induction heating cooker according to another embodiment of the present invention, Fig. 4 (C _r) the first The first resonant capacitor C _r1 forming the resonant circuit with the second working coils L _r11 and L _r12 and the second resonant capacitor forming the resonant circuit with the third and fourth working coils L _r21 and L _r22 ( C _r2 ) and other components are the same.

Therefore, when the first and second relays Ry1 and Ry2 and the first to fourth switches S1 to S4 are switched in accordance with an operation mode control signal input from the outside, the circuit diagram of the induction cooker shown in FIG. 4 is the same. It works according to the principle.

As described above, the present invention has the effect of minimizing the cost and size of the system by controlling a plurality of loads with a single inverter.

Claims (2)

Voltage branching means for branching an input voltage through a plurality of filter capacitors; Heating means for heating a plurality of heating vessels by resonating an input voltage branched by the voltage dividing means by a plurality of resonant circuits comprising a plurality of working coils and a single resonant capacitor; A plurality of relay elements constitute a resonant circuit together with the plurality of resonant circuits, and the relay elements are switched according to a control signal input from the outside to select a predetermined resonant circuit in which a predetermined working coil operates. First switching means for heating the heating vessel; Magnetic switch characterized in that it comprises a second switching means for switching the number of switch elements of the relay element number is alternately switched in accordance with a control signal input from the outside to supply power to the heating means to heat the heating vessel. Non-magnetic combined induction cooker. The method of claim 1, The magnetic and nonmagnetic combined induction heating cooker, characterized in that the number of the resonant capacitor of the heating means is 1/2 of the number of the working coil.

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