JPS60100394A - Electromagnetic induction cooking device - 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 Field of the Invention The present invention relates to an electromagnetic induction cooking device that uses electromagnetic induction heating and is electromagnetically coupled to the cooking surface of the cooker to drive other cooking devices.

Structure of conventional example and its problems Conventionally, induction heating cooker H using electromagnetic induction heating is well known.This type of cooker heats magnetic metal (pan) using an alternating magnetic field generated from a heating coil. is configured to do so. A device that drives a motor, heater, etc. by obtaining energy from a coupling coil electromagnetically coupled to the heating coil of this induction heating cooker has already been proposed.

However, when driving a load with such a coupling coil, there are still problems with the coupling state of the heating coil of the induction heating cooker and the above-mentioned coupling coil, the setting of the power control, and the fluctuation of the power supply voltage of the induction heating cooker. When a motor is used as the load, abnormal heating occurs, and when a heater is used, the service life is shortened.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is a device that drives a load by obtaining energy from a coupling coil that is electromagnetically coupled to the cooking surface of an induction heating cooker. The present invention provides a device that applies a constant voltage to a load without being affected by the power control settings of the device or the power supply voltage.

Structure of the Invention The present invention comprises a load connected to a coupling coil electromagnetically coupled to a heating coil, a voltage detection transmitting circuit connected to both ends of the load, and a load status receiving circuit receiving an output signal of the voltage detecting transmitting circuit. and an inverter control circuit connected to the output of the load state receiving circuit, and controls the oscillation frequency of the inverter according to changes in the transmission frequency of the voltage detection transmitting circuit, and applies the voltage to the load. This controls the voltage level to a constant level.

DESCRIPTION OF EXAMPLES Hereinafter, the present invention will be described in detail based on examples. FIG. 1 is a block diagram showing one embodiment of the present invention. In Figure 1, is 1 commercial? (1 source, 2 units: commercial '1Ft source AC inverter to exchange into high frequency power, 3 is the control circuit of inverter 2, 4i1.1. heating coil, 5 is the top plate 1 that forms the cooking surface, 6 is the heating A coupling coil is placed on the cooking surface to be electromagnetically coupled to the coil 4. 7 is a load connected to the coupling coil 6. 8 is a voltage detection transmitting circuit connected to both ends of the load 7, and its output is sent to the coupling coil 6. It is connected.

Reference numeral 9 denotes a load state receiving circuit, which has an input terminal connected to the heating coil 4 and an output terminal connected to the control circuit 3. 1o is a rectifier circuit connected to both ends of the coupling coil 6. 1
1 is a voltage controlled oscillation circuit, the output of a rectifier circuit 1o is connected to a control input, and the output thereof is connected to a coupling coil 6. 12 is a band pass filter whose input terminals are connected to both ends of the heating coil 4 and set within the oscillation frequency range of the voltage controlled oscillation circuit 11. The oscillation frequency of the voltage-controlled oscillation circuit 11 and the pass frequency of the bandpass filter 12 are set between twice the frequency of the commercial power supply 1 and the lower limit oscillation frequency of the inverter 2. 13 is a frequency-voltage converter circuit (hereinafter referred to as f-V converter)
The input terminal is connected to the output terminal of the closed pass filter 12.

14 is a comparison amplifier, one input terminal of which is connected to the output of the f-V converter 13, and the other input terminal connected to a predetermined reference voltage source Ref. 15 is a rectifier circuit, the input terminal of which is connected to the output terminal of the pantone filter 12; 16 is a voltage comparator whose input terminal is connected to the rectifier circuit 16.The operation will be described in the above configuration. When the commercial power supply 1 is turned on, power is supplied to the control circuit 3, and the inverter 2 starts oscillating in response to a drive signal from the control circuit 3. The heating coil 4 is heated by the oscillation of the inverter 2.
High-frequency currents are applied to both, and high-frequency magnetic lines of force are generated. Then, this high frequency magnetic field line penetrates the coupling coil 6,
An induced voltage is generated at both ends thereof and drives the load 7. Here, the voltage induced across the coupling coil 6 is rectified by the rectifier circuit 10 of the voltage detection and transmission circuit 8 to generate a DC power source and a voltage signal proportional to the magnitude of the induced voltage. This DC power supply and voltage signal are then used as the voltage control source for the next stage.
It generates an oscillation output with a frequency corresponding to the 11i pressure signal, and this oscillation output signal is superimposed on the coupling coil 6 and given as a signal. The signal applied to the coupling coil 6 is then detected by the heating coil 4. This detection signal is passed through the bandpass filter 12 of the load state receiving circuit 9, in which only the excavated frequency signal of the voltage controlled oscillation circuit 11 is passed, and this passed signal is used by the fV converter 13 to generate a DC voltage according to the signal frequency. Then, this DC voltage is compared with a predetermined reference voltage Ref in a comparator amplifier 14, and a signal corresponding to the deviation from the reference voltage Ref' is generated as an output.

Here, this reference voltage Ref serves as a setting for the voltage applied to the load 7. The output of the comparison amplifier 14 mentioned above is input to the control circuit 3, and the oscillation frequency of the inverter 2 is continuously varied. On the other hand, the signal passed through the bandpass filter 12 is rectified by the rectifier circuit 16, and the voltage comparator 16 determines whether or not there is an output from the rectifier circuit 16, and generates a switch output. This switch output is input to the control circuit 3, and when an output is generated in the rectifier circuit 15, the power control circuit of the control circuit 3 is prohibited, and the operation of the small object load detection circuit is prohibited.

Here, the feed bank operation for keeping the voltage of the load 7 constant in the configuration shown in FIG. 1 will be described in detail.

Now, the output frequency of the voltage controlled oscillation circuit 11 is set to increase by 2 in proportion to the voltage of negative #7. Therefore, the bandpass filter 12 generates an output having the same frequency as the above-mentioned frequency, and the fV converter 13 generates a DC voltage proportional to this frequency. Then, this DC voltage is compared with a reference voltage Ref in a comparator amplifier 14, and if the DC voltage output is higher than the reference voltage Ref, the output increases, the drive frequency of the control circuit 3 increases, and the heating coil 4 is energized. Reduce the current. (If the current applied to the coil 4 becomes smaller, the induced voltage in the coupling coil 6 will naturally become smaller, and the oscillation frequency of the voltage controlled oscillation circuit 11 will decrease, causing f-
The output voltage of V converter 13 also decreases. When the voltage becomes smaller than the reference voltage Ref, the voltage applied to the load 7 becomes constant by performing an operation opposite to the above-described operation. That is,
If the power status of the coupling coil 6 fluctuates, or if the power status of the coupling coil 6 changes within the operable range of
A constant voltage is supplied to the load 7 even if the voltage varies. Note that the comparison amplifier 14 and the control circuit 30
The relationship between the oscillation frequency of the inverter 2 and the output voltage may be determined as appropriate depending on the circuit configuration of the inverter.

Next, we will discuss Figure 2. FIG. 2 shows an embodiment of the voltage detection and transmission circuit 8 of FIG. 1. In FIG.

In Figure 2, 17, 20, 21.22 are resistances, 18
is a rectifier diode, 19 is a smoothing capacitor, 23 is a Zener diode, and 24 is a voltage controlled oscillator.

25 is a matching transformer, and 26 is a coupling capacitor.

The operation in the above configuration will be briefly explained. The voltage generated in the load 7 is rectified by a diode 18 via a resistor 17, and converted to a DC voltage by a smoothing capacitor 19. This DC voltage is stabilized by the resistor 22 and the Zener diode 23 and becomes the DC power supply for the voltage controlled oscillator 24, while the signal divided by the resistors 20 and 21 becomes the oscillation frequency control No. 1g of the voltage controlled oscillator 24. The voltage control excavator 24 provides an output with a frequency corresponding to the voltage of the smoothing capacitor 19 to the matching transformer 25. And Manochig! - The output generated from the output winding of the lance 26 is fed to the coupling coil 6 via the coupling capacitor 26.

Next, FIG. 3 will be described. FIG. 3 shows an embodiment of the connection relationship between the control circuit 3 and the load state receiving circuit 9 of FIG. Figure 3.

Reference numeral 27 is a small object negative i-nea detection circuit, 28 is a power control circuit, 29ilJ is a power setting volume, 30 pulse width control circuit, 31 is an inhibition circuit, and 32 is a base drive circuit. A configuration is shown in which the oscillation frequency of the inverter 2 is varied by varying the conduction time (pulse width).

The operation of the above configuration will be briefly described. Voltage comparator 16
detects the presence or absence of voltage in the rectifier circuit 15 and generates switching. Therefore, if voltage is generated in the rectifier circuit 16, the operation of the small object load detection circuit 27 is prohibited, and the operation of the power control circuit 28 is also prohibited. And this] 1. J1' (The pulse width control circuit 30 is operated by the output of the ratio axis amplifier 14, and the power setting volume 29 of the power control circuit 28 is not affected)'L is eliminated. The output of this pulse width control circuit 30 passes through an inhibition circuit 31 and is amplified by a base drive circuit 32 to provide a drive signal to the inverter 2.

Effects of the Invention As described in Section 2, according to the electromagnetic induction control device of the present invention, the voltage applied to the load connected to the coupling coil can be controlled to a constant level, so that the coupling between the heating coil and the coupling coil is improved. It is not affected by state, fluctuations in commercial power supply voltage, or power control settings.

This enables stable operation of the load. In addition, in the present invention, since the voltage detection signal is superimposed on the coupling coil,
It is possible to transfer signals reliably with good coupling, but it goes without saying that it can also be put to practical use by providing a dedicated antenna device for transmission and reception.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an electrical wiring diagram showing an embodiment of a part of the specific circuit shown in FIG. 1,
FIG. 3 is a block diagram showing a specific configuration of some of the connections shown in FIG. 1. 2... Inverter, 3... Control circuit,
4...Heating coil, 6...Coupling coil, 7...Load, 8...Voltage detection transmission circuit, 9...Load condition receiving circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] (1) A coupling coil electromagnetically coupled to a heating coil, a load connected to this coupling coil, a voltage detection transmission circuit connected to both ends of this load, and an output of this voltage detection transmission circuit. The circuit includes a load status receiving circuit that receives a signal, and an inverter control circuit connected to the load status receiving circuit, and controls the oscillation frequency of the inverter by changing the transmission frequency of the voltage detection transmitting circuit, and applies the voltage to the load. An electromagnetic induction cooking device that controls the voltage level at a constant level. (2) The voltage detection and transmission circuit consists of a rectifier circuit connected to both ends of a coupling coil and a voltage controlled oscillation circuit connected to the output of the rectifier circuit, and the output signal of the rectifier circuit causes the voltage controlled oscillation circuit to oscillate. The electromagnetic induction cooking device according to claim 1, wherein the frequency is continuously variable. (3) The load status receiving circuit includes a bandpass filter, a frequency-voltage conversion circuit connected to the output of the bandpass filter, and a comparison amplifier having a predetermined reference voltage connected to the output of the frequency-voltage conversion circuit. , and a rectifier circuit connected to the output of the bandpass filter, and a voltage comparator connected to the output of the rectifier circuit, and the comparison amplifier and the voltage comparator are connected to a control circuit of an inverter. The electromagnetic induction cooking apparatus according to claim 1, wherein the oscillation frequency of the inverter is controlled by the output signal of the comparison amplifier. (4) The control circuit consists of a pulse width control circuit for the switching elements of the inverter and the output of this pulse width control circuit. a comparator amplifier having a predetermined reference voltage, an inhibit circuit connected to the power, a base drive direction circuit connected to the output of the inhibit circuit, and a power control circuit connected to the input of the pulse width control circuit; The output of the voltage comparator is connected to the pulse width control circuit, and the output of the voltage comparator is connected to the power control circuit to control the voltage level applied to the load connected to the coupling coil. 3. The electromagnetic induction cooking device according to claim 3, wherein the level is maintained at a constant level without being affected by the operating state of the coil circuit. (6) Claim 2 or 3 in which the oscillation frequency of the voltage controlled oscillator circuit and the passing frequency of the free pass filter are set between twice the frequency of the commercial power supply and the lower limit oscillation frequency of the inverter. The electromagnetic induction cooking device described in .