KR100784314B1 - Apparatus for controlling variable output of current trans voltage - Google Patents

Abstract

An apparatus for controlling variable output of a CT(Current Trans) voltage is provided to remarkably improve manufacturing efficiency by reducing a manufacturing cost and a number of parts by using one CT voltage output detector. An apparatus for controlling variable output of a CT voltage includes a CT output detector, first and second output detectors(800,810), and a variable CT voltage output controller(120). The CT voltage output detector detects current change inputted through normal power source according to operations of first and second heating coils and outputs a voltage converted from the current change. The first and the second output detectors detect whether the first and the second heating coils are operated or not respectively. The variable CT voltage output controller is connected to a voltage output terminal of the CT output detector and keeps output voltage outputted from the CT output detector uniform by varying resistance by results detected from the first and the second output detectors.

Description

Apparatus for controlling variable output of current trans voltage}

1 is an electric circuit diagram showing the configuration of a general induction heating cooking apparatus.

Figure 2 is a block diagram schematically showing the configuration of the induction heating cooking apparatus to which the variable output control device of the CT voltage according to the present invention is applied.

Figure 3 is an electric circuit diagram showing a variable output control device of the CT voltage in accordance with the present invention.

(Explanation of symbols for the main parts of the drawing)

100: commercial power supply 110: rectifier

120: CT output detector 130: voltage detector

140: output compensation unit 200: IH control unit

300: first IGBT driver 310: second IGBT driver

400: first IGBT element 410: second IGBT element

500: first heating coil part 510: second heating coil part

600: microprocessor 700: variable CT output control unit

710: first input delay unit 720: second input delay unit

800: first output detector 810: second output detector

802, 812: Light emitting portion 804, 814: Light receiving portion

The present invention relates to a CT voltage variable control device of an induction heating cooking apparatus having two independent heating coils. More specifically, only one heating coil is operated by using one CT output detector or two heating coils are operated at the same time. The present invention relates to a variable output control device for CT detection voltage which enables the CT detection voltage to be kept constant according to a change in the input current even in operation.

Induction heating (IH), that is, induction heating device generally switches the commercial DC voltage applied to the heating coil, and the counter electromotive force generated when the commercial DC voltage is turned off forms a strong magnetic field in the heating coil, thereby heating the heating. It is a device for cooking food and the like by heating the magnetic container seated on the coil.

The method of controlling the output of the induction heating apparatus is a method of controlling the output using phase detection means for detecting a phase difference signal from both ends of the resonant circuit of the induction heating apparatus, wherein the resonance time constant and the oscillation timing of the oscillation means are synchronized with each other. Using the phase difference signal detected by the phase detection means, a trigger signal is supplied to continuously oscillate the oscillation means.

In addition, another method of controlling the output of the induction heating apparatus is a control using a duty cycle, and the control using the duty cycle causes the power of the rated maximum output to be turned on and off. By controlling the ratio of the time, the short time for switching on the power and the long off time gives a low output, conversely, if the long on time and the short off time gives a high output.

1 is an electric circuit diagram showing the configuration of a general induction heating cooking apparatus. As shown in FIG. 1, AC (AC 220V) power applied from the commercial power supply 100 is converted from the rectifier 110 to DC power, and a change in the input current according to the driving of the heating coil is detected from the CT (current transformer). The output compensation control signal according to the CT output detector 120, the voltage detector 130 that detects the voltage variation value of the input power source, and the variation value detected by the CT output detector 120 and the voltage detector 130 A cooking vessel (not shown) is output in accordance with an output compensator 140 for outputting, a microprocessor 150 for outputting an oscillation signal of the IH control unit 200, and an oscillation signal output from the microprocessor 150. And an IH controller 160 for outputting an operation signal of the IGBT driver 170 for switching on / off the heating coil unit 190 to be heated. Reference numeral 180 is an IGBT device.

The CT output detector 120 detects the change in the input current from the CT (current transformer), thereby detecting the magnitude of the applied current. That is, the CT converts the primary side current of the commercial power supply 100 to a predetermined magnitude and outputs the current.

The CT output detection unit 120 has a heating coil unit 190 in the configuration to convert the variation of the input current to the variation of the output voltage using the CT, and then fed back to the IH controller to turn on the IGBT element 180 Adjust the (Turn on) time to maintain a constant output.

Recently, an IH circuit has been proposed in which two independent heating coils are installed to provide high power that cannot be provided by one heating coil. However, two independent CT output detectors are required to control the independent heating coils. There is a problem.

In addition, such a CT output detection unit is composed of power elements, there is a problem that the increase in the number of parts and manufacturing cost increase.

In order to solve the above problems, the present invention provides a CT detection voltage according to a change in input current when two heating coils operate or simultaneously operate using one CT output detector in an induction heating cooker having two independent heating coils. It is an object of the present invention to provide a variable output control device for CT voltage that can be kept constant.

In order to achieve the above object, the variable output control device for CT voltage according to the present invention is an induction heating cooker, the current input through the commercial power supply according to the operation of the first heating coil and the second heating coil for heating the cooking vessel. A CT output detector for detecting a variation of the current from a CT (current transformer) and converting the detected variation of the input current to output a voltage; A first output detector for detecting whether a first heating coil for heating the cooking vessel is operated; A second output detector for detecting whether a second heating coil for heating the cooking vessel is operated; And a variable CT output controller connected to the voltage output terminal of the CT output detector to vary the resistance value according to the detection results detected by the first and second output detectors so that the output voltage output from the CT output detector is kept constant. It includes.

The variable CT output controller may include a first resistor connected in parallel with the voltage output terminal of the CT output detector; A first transistor coupled to the collector, a base coupled to an output terminal of the first output detector, and an emitter coupled to a ground voltage; A second resistor connected in parallel with the voltage output terminal of the CT output detector; A second transistor coupled to the collector, a base coupled to an output terminal of the second output detector, and an emitter coupled to a ground voltage; A third transistor having a collector connected to a power supply voltage, a base connected to a collector of the first transistor and a collector of a second transistor, and an emitter connected to a ground voltage; A diode provided between the collector of the first transistor and the base of the third transistor and between the collector of the second transistor and the base of the third transistor; A third resistor connected in parallel with the voltage output terminal of the CT output detector; And a fourth transistor connected to the third resistor, a base connected to the collector of the third transistor, and an emitter connected to a ground voltage.

The variable CT output controller may include a first resistor connected in parallel with the voltage output terminal of the CT output detector; A first transistor coupled to the collector, a base coupled to an output terminal of the first output detector, and an emitter coupled to a ground voltage; A second resistor connected in parallel with the voltage output terminal of the CT output detector; A second transistor coupled to the collector, a base coupled to an output terminal of the second output detector, and an emitter coupled to a ground voltage; A logic circuit unit having a first input terminal connected to the collector of the first transistor, a second input terminal connected to the collector of the second transistor, and outputting a logic sum signal according to an input result of the first and second input terminals; A third resistor connected in parallel with the voltage output terminal of the CT output detector; And a fourth transistor connected to the third resistor, connected to an output terminal of the logic circuit, and an emitter connected to a ground voltage.

The variable CT output controller may further include a first input delay unit configured to delay the signal output from the first output detector by a predetermined time to be applied to the base of the first transistor; And a second input delay unit configured to delay the signal output from the second output detector by a predetermined time and be applied to the base of the second transistor.

The first input delay unit may have an anode connected to the base of the first transistor, the cathode may be connected to the first constant voltage diode connected to the first output detector, and the + input terminal may be connected to the anode of the first constant voltage diode. An input terminal comprising a first capacitor connected to a ground power source, the second input portion having an anode connected to a base of the second transistor, a cathode having a second constant voltage diode connected with the second output detecting portion, and a + input terminal having the first input voltage; 2 is connected to the anode of the constant voltage diode, and the input terminal comprises a second capacitor connected to a ground power source.

The first and second output detectors may include light emitting devices emitting light depending on whether the first and second heating coils are operated; And a light receiving device that is turned on or off depending on whether light is emitted from the light emitting device.

The light receiving element may be any one of a photo transistor and a CDS sensor.

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

First, the same reference numerals are used for the same components as in the prior art, and detailed description of the same components is omitted.

Figure 2 is a block diagram schematically showing the configuration of the induction heating cooking apparatus to which the variable output control device of the CT voltage according to the present invention, Figure 3 is an electric circuit diagram showing a variable output control device of the CT voltage according to the present invention.

As shown in FIGS. 2 and 3, an induction heating cooker having a variable output control device for CT voltage converts an AC (AC 220V) power applied from the commercial power supply 100 into a DC power supply in the rectifying unit 110 and heats it. The CT output detector 120 detects a change in the input current value according to the driving of the coil, converts the detected change in the input current into a voltage, and outputs the voltage, and the voltage detector 130 detects the voltage change in the input power. And an output compensator 140 for outputting an output compensation control signal according to the variation detected by the CT output detector 120 and the voltage detector 130, and a cooking vessel (not shown) to be heated to a constant output. Outputs an operation signal of the first IGBT driver 300 for switching the first heating coil unit 500 on / off and the second IGBT driver 310 for switching the second heating coil unit 510 on / off IH control unit 200 and IH control unit 200 The output voltage of the CT output detector 120 remains constant even if the input current fluctuates according to the operation of the microprocessor 600 and the first and second heating coil units 500 and 510 that output the oscillation signal. The first and second output detectors 800 for detecting the operation of the variable CT output controller 700 and the first and second heating coil units 500 and 510 and providing the variable CT output controller 700 to the variable CT output controller 700. 810). Reference numerals 400 and 410 are IGBT devices.

The CT output detector 120 detects a change in current input through the commercial power supply 100 from a CT (current transformer), and detects the change in the detected input current as a change in an output voltage (hereinafter referred to as a CT output voltage). Convert and output

The first IGBT driver 300 turns the IGBT element 400 on or off so that the first heating coil unit 500 is operated according to the driving signal output from the IH controller 200.

The second IGBT driver 310 turns the IGBT element 410 on or off so that the second heating coil unit 510 is operated according to the driving signal output from the IH controller 200.

The first heating coil unit 500 is composed of a heating coil and a resonance capacitor for heating a cooking vessel (not shown) at a constant output.

The second heating coil unit 510 is composed of a heating coil and a resonance capacitor for heating a cooking vessel (not shown) at a constant output.

The microprocessor 600 outputs an oscillation signal to the IH controller 200 so that the first and second heating coil units 500 and 510 can operate.

The variable CT output control unit 700 may operate the heating coil unit of any one of the first heating coil unit 500 and the second heating coil unit 510 when the CT output voltage output from the CT output detection unit 120 operates. The resistance value is varied so that the first heating coil unit 500 and the second heating coil unit 510 can be kept constant even when they are operated simultaneously.

In more detail, the variable CT output control unit 700 includes a variable CT output control unit 700 and a plurality of bipolar transistors Q1, Q2, Q3 and Q4, and a variable output voltage variable resistor R8, R9 and R10. And input delay units 710 and 720.

One side of the first resistor R9 is connected in parallel with the voltage output terminal of the CT output detector 120, and the other side thereof is connected to the collector of the first transistor Q2.

The first transistor Q2 has a base connected to the output terminal of the first output detector 800 that detects the operation of the first heating coil 500, an emitter connected to the ground voltage GND, and the collector 1 is connected to a resistor (R9).

One side of the second resistor R8 is connected in parallel with the voltage output terminal of the CT output detector 120, and the other side thereof is connected to the collector of the second transistor Q1.

The second transistor Q1 has a base connected to the output terminal of the second output detector 810 for detecting the operation of the second heating coil 510, an emitter connected to the ground voltage GND, and the collector 2 is connected to a resistor (R8).

The third transistor Q3 has a collector connected to the power supply voltage VCC through a resistor R11, a base connected to the collector of the first transistor Q2 and the collector of the second transistor Q1, and the ground voltage ( The emitter is connected to GND).

In addition, a diode D2 is provided between the collector of the first transistor Q2 and the base of the third transistor Q3, and the diode (between the collector of the second transistor Q1 and the base of the third transistor Q3). D3) is installed so that the operations of the first resistor R9 and the second resistor R8 do not affect each other.

One side of the third resistor R10 is connected in parallel with the voltage output terminal of the CT output detector 120, and the other side thereof is connected to the collector of the fourth transistor Q4.

The fourth transistor Q4 has a base connected to the collector of the third transistor Q3, an emitter connected to the ground voltage, and the collector connected to the third resistor R10.

In another embodiment of the present invention, a logic circuit portion (for example, a TTL element) for outputting a logic OR signal instead of the third transistor Q3 and the diodes D2 and D3 may be configured. Do. That is, the first input terminal is connected to the collector of the first transistor Q2, the second input terminal is connected to the collector of the second transistor Q1, and the logic sum signal is output according to the input result of the first and second input terminals. do.

The first input delay unit 710 is configured such that the signal output from the first output detector 800 is delayed for a predetermined time and applied to the base of the first transistor Q2. A cathode connected to the base of the first transistor Q2, and a cathode connected to the first constant voltage diode ZD2 connected to the first output detector 800, a + input terminal connected to an anode of the first constant voltage diode ZD2, and-an input terminal. The first capacitor C4 is connected to the ground power supply.

The second input delay unit 720 is configured such that a signal output from the second output detector 810 is delayed for a predetermined time and applied to the base of the second transistor Q1. Is connected to the base of the transistor Q1, and the cathode is connected to the second constant voltage diode ZD1 connected to the second output detector 810, the + input terminal is connected to the anode of the second constant voltage diode ZD1, and the input terminal is grounded. And a second capacitor C3 connected to the power supply.

The first output detector 800 is configured to detect the operation of the first heating coil unit 500. Preferably, the first IGBT driver 300 outputs a switching on / off signal of the first heating coil unit 500. It is connected to the output terminal of.

In addition, the first output detector 800 may include a light emitting device 802 that emits light according to the operation of the first heating coil, and a light receiving device that is turned on or off depending on whether light is emitted from the light emitting device 802. And an output terminal of the light receiving element 804 is connected to the cathode of the first constant voltage diode ZD2 of the first input delay unit 710.

The second output detector 810 is configured to detect the operation of the second heating coil unit 510. Preferably, the second IGBT driver 310 outputs a switching on / off signal of the second heating coil unit 510. It is connected to the output terminal of.

In addition, the second output detector 810 may include a light emitting device 812 that emits light according to the operation of the second heating coil, and a light receiving device that is turned on or off depending on whether light is emitted from the light emitting device 812. 814, and an output terminal of the light receiving element 814 is connected to the cathode of the second constant voltage diode ZD1 of the second input delay unit 720.

The light emitting elements 802 and 812 are turned on by a signal applied to indicate that the first and second heating coils are operated so that light is emitted. The light emitting devices 802 and 812 can use any configuration capable of emitting light such as an LED and an infrared light emitting sensor. In this embodiment, an LED is used.

The light receiving elements 804 and 814 are turned on or turned off depending on the light emitted from the light emitting elements 802 and 812, and the light receiving units 804 and 814 are a photo transistor, a CDS sensor, or an infrared ray. It is possible to use a light receiving sensor and the like, and a photo transistor is used in this embodiment.

The following describes the operation of the CT voltage variable control apparatus according to the present invention.

(When only the first heating coil part operates)

When the first heating coil unit 500 is operated through the first IGBT driver 300, power is applied to the light emitting device 802 of the first output detector 800 to emit light, and the emitted light is received. Turn on device 804.

When the light receiving element 804 is turned on, after a predetermined time delay by the first constant voltage diode ZD2 and the first capacitor C4, the first transistor Q2 is turned on so that the first resistor R9 is turned on with the ground power source. Be sure to

At this time, the third transistor Q3 is turned on and the fourth transistor Q4 is turned off to maintain only the first resistor R9 in the ground state.

Therefore, when only the first heating coil unit 500 operates, the resistance is changed so that the CT output voltage can maintain a constant voltage according to the single driving of the first heating coil unit 500.

(When only the second heating coil part operates)

When the second heating coil unit 510 is operated through the second IGBT driver 310, power is applied to the light emitting device 812 of the second output detector 810 to emit light, and the emitted light is received. Turn on device 814.

When the light receiving element 814 is turned on, the second transistor Q1 is turned on after being delayed by the second constant voltage diode ZD1 and the second capacitor C3 for a predetermined time, so that the second resistor R8 is turned on with the ground power supply. Be sure to

At this time, the third transistor Q3 is turned on and the fourth transistor Q4 is turned off to maintain only the second resistor R8 in the ground state.

Therefore, when only the second heating coil unit 510 operates, the resistance is changed so that the CT output voltage can maintain a constant voltage according to the independent driving of the second heating coil unit 510.

(When both the first heating coil section and the second heating coil section operate)

When the first and second heating coil units 500 and 510 are operated through the first and second IGBT drivers 300 and 310, the light emitting devices 802 and 812 of the first and second output detectors 800 and 810 are operated. Power is applied to emit light, and the emitted light turns on the light receiving elements 804 and 814, respectively.

In this case, when each of the light receiving elements 804 and 814 is turned on, the first transistor Q2 is turned on after being delayed by the first constant voltage diode ZD2 and the first capacitor C4 for a predetermined time, and thus the first resistor R9 is turned on. The second transistor Q1 is turned on and the second resistor R8 is grounded with the ground power supply after being delayed by the second constant voltage diode ZD1 and the second capacitor C3 for a predetermined time.

At this time, the third transistor Q3 is turned off, and the fourth transistor Q4 is turned on so that the first resistor R9, the second resistor R8, and the third resistor R10 maintain ground.

Therefore, the resistance of the operation of both the first heating coil unit 500 and the second heating coil unit 510 is variable, so that the CT output voltage can maintain a constant voltage.

As described above, the present invention has the advantage that the CT output voltage can be constantly controlled using one CT output detector in the induction heating apparatus using two independent heating coils.

In addition, by using a single CT output detection unit has the advantage that the manufacturing efficiency can be significantly improved by reducing the manufacturing cost and parts.

In the above, the present invention has been illustrated and described with respect to certain preferred embodiments. However, the present invention is not limited to the above-described embodiments, and those skilled in the art to which the present invention pertains can vary as many as possible without departing from the spirit of the present invention as set forth in the claims below. Changes may be made.

Claims (7)

In induction cooker, According to the operation of the first heating coil and the second heating coil for heating the cooking vessel detects the variation of the current input through the commercial power supply from the CT (current transformer), and converts the variation of the detected input current to output the voltage A CT output detector; A first output detector for detecting whether a first heating coil for heating the cooking vessel is operated; A second output detector for detecting whether a second heating coil for heating the cooking vessel is operated; And A variable CT output control unit connected to the voltage output terminal of the CT output detector to change a resistance value according to the detection results detected by the first and second output detectors so that the output voltage output from the CT output detector is kept constant; Variable output control device of CT voltage containing. The method of claim 1, The variable CT output controller may include a first resistor connected in parallel with the voltage output terminal of the CT output detector; A first transistor coupled to the collector, a base coupled to an output terminal of the first output detector, and an emitter coupled to a ground voltage; A second resistor connected in parallel with the voltage output terminal of the CT output detector; A second transistor coupled to the collector, a base coupled to an output terminal of the second output detector, and an emitter coupled to a ground voltage; A third transistor having a collector connected to a power supply voltage, a base connected to a collector of the first transistor and a collector of a second transistor, and an emitter connected to a ground voltage; A diode provided between the collector of the first transistor and the base of the third transistor and between the collector of the second transistor and the base of the third transistor; A third resistor connected in parallel with the voltage output terminal of the CT output detector; And And a fourth transistor coupled to the collector, a base coupled to the collector of the third transistor, and an emitter coupled to the ground voltage. The method of claim 1, The variable CT output controller may include a first resistor connected in parallel with the voltage output terminal of the CT output detector; A first transistor coupled to the collector, a base coupled to an output terminal of the first output detector, and an emitter coupled to a ground voltage; A second resistor connected in parallel with the voltage output terminal of the CT output detector; A second transistor coupled to the collector, a base coupled to an output terminal of the second output detector, and an emitter coupled to a ground voltage; A logic circuit unit having a first input terminal connected to the collector of the first transistor, a second input terminal connected to the collector of the second transistor, and outputting a logic sum signal according to an input result of the first and second input terminals; A third resistor connected in parallel with the voltage output terminal of the CT output detector; And And a fourth transistor coupled to the collector, coupled to an output terminal of the logic circuit portion, and coupled to an emitter connected to a ground voltage. The method of claim 2 or 3, The variable CT output controller may include: a first input delay unit configured to delay a signal output from the first output detector from the first output detector and to be applied to the base of the first transistor; And And a second input delay unit configured to delay the signal output from the second output detector by a predetermined time to be applied to the base of the second transistor. The method of claim 4, wherein The first input delay unit has an anode connected to the base of the first transistor, the cathode is connected to the first constant voltage diode connected to the first output detector, a + input terminal is connected to the anode of the first constant voltage diode, and an input terminal. A first capacitor connected to the ground power source, The second input part has an anode connected to the base of the second transistor, the cathode is connected to the second constant voltage diode connected with the second output detector, the + input end is connected to the anode of the second constant voltage diode, and the input end is grounded. And a second capacitor connected to a power supply. The method of claim 1, The first and second output detectors include a light emitting device that emits light depending on whether the first and second heating coils are operated; And And a light receiving element that is turned on or off depending on whether light is emitted from the light emitting element. The method of claim 6, And the light receiving element is any one of a photo transistor and a CDS sensor.

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