JPS6121827Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electromagnetic induction device that includes a reception coil that is electromagnetically coupled to an induction heating coil of an induction heating cooker, and that uses alternating current induced by the reception coil as a power source.

Induction heating cookers use commercial AC power as a driving power source, which is rectified and smoothed, then connected to a high frequency inverter, converted to a high frequency alternating current of about 20 to 40 KHz, and then connected to an induction heating coil, which is also connected to a high frequency alternating current. It generates a magnetic field. This high-frequency alternating magnetic field is applied to an iron or stainless steel pot placed on the top plate to induction heat it.

In addition to heating the cooking pot, such induction heating cookers can also be used to heat other electrical equipment such as the top plate.
A method has been proposed in which a heater, mixer, etc. are mounted and operated. Such electrical equipment includes a power receiving coil that is electromagnetically coupled to the induction heating coil of the induction heating cooker, and power is supplied through the power receiving coil. In addition, the circuit configuration of such an induction heating cooker is, for example, as shown in Figure 5 of JP-A No. 54-48346, in which a DC voltage is applied to one end of the heating coil, and a switching transistor is connected to the heating coil. By turning ON and OFF,
The voltage at the other end of the heating coil is as shown in FIG. 8A of the above publication, and as a result, a voltage as shown in FIG. 4 is generated between both ends of the heating coil. The upper limit of the voltage obtained between both ends of such a heating coil is suppressed to about 140V, which is the voltage obtained by rectifying the commercial AC power supply, and the lower limit reaches about -800V due to the resonance of the inverter.

This invention focuses on the fact that the voltage waveform generated between the induction heating coils is asymmetrical with respect to zero potential, and the similar waveform voltage obtained through the receiving coil is full-wave rectified and outputs two different waveforms. By using half-wave rectification, the power input to the load can be switched in four stages, including the power off state.

An embodiment of the present invention will be described below based on the drawings.

Fig. 1 shows a device in which a mixer is used as an electric device. 1 is an induction heating cooker, and an inverter 2 generates a high-frequency alternating current of approximately 20 to 40 KHz by inputting commercial AC power, and a high-frequency alternating current is generated from this inverter 2. It includes an induction heating coil 3 to which an electric current is applied, and the cooking pot is placed on a top plate 4 on the top of the cooker. Reference numeral 5 denotes a mixer placed on the top plate 4, which is equipped with a power receiving coil 6 at its bottom and electromagnetically coupled to the heating coil 3 to form a type of transformer. 7 is a rectifying and smoothing circuit that rectifies and smoothes the high frequency alternating current obtained from the receiving coil 6;
9 is a DC motor to which a rectified and smoothed DC voltage is applied to the pulsating current in the rectifying and smoothing circuit 7; and 9 is a rotary blade driven by the DC motor 8.

Fig. 2 shows the implemented circuit, where 10 is a rectifier circuit formed by bridge-connecting four diodes _D1 to _D4 , and Sa and Sb are outputs provided on the anode side of diodes _D1 and _D2 . Each is operated independently using a changeover switch. 11 is a smoothing capacitor, and 8 is the motor serving as a load.

FIG. 3 shows operating waveforms. Voltage Vo is the voltage obtained across the receiving coil 6, and a similar waveform voltage of the voltage across the induction heating coil 3 is obtained. Voltage V ₁ is a full-wave rectified voltage obtained across the rectifier circuit 10 when both switches Sa and Sb are closed, and its smoothed output is shown as voltage V ₁ '. The number of turns of the power receiving coil 6 is determined so that the voltage V ₁ ' has a value suitable for driving the motor 8, and in this case, the voltage V ₁ is set to be 100V. The voltage obtained at this time
Vo has a waveform with a maximum voltage of 24.5V and a minimum voltage of -140V. Open switch Sa, switch Sb
When only the voltage V ₂ is closed, the high voltage portion of 140V is output as a half-wave rectified voltage, and the smoothed voltage V ₂ ' is approximately 85V. On the other hand, switch
When Sa is closed and switch Sb is opened, a voltage V ₃ with a small peak value, that is, a half-wave rectified voltage of 24.5V is output, and this is smoothed to produce a DC voltage of approximately 20V.
V ₃ ′ is obtained.

The three levels of voltage V ₁ ′ obtained in this way,
When driving a mixer that consumes 300W at V ₂ ′ and V ₃ ′, the output will be “strong” (300W) and “medium” (approx.
240W), "weak" (approximately 12W), and OFF state can be added to enable output adjustment in four stages. That is, high-speed and medium-speed motor rotation can be obtained with the output "strong" and "medium", and motor rotation at a stirring level can be obtained with the output "weak".

In summary, in the electromagnetic induction device of the present invention, the current obtained at both ends of the induction heating coil of the induction heating cooker is
Used to create an asymmetric alternating current with respect to 0 potential,
Since the different parts of each waveform are discriminated and outputted by half-wave rectification, in addition to a full-wave rectified output, two types of half-wave rectified output can be obtained.
This allows for stronger switching of the output supplied to the load.
It is possible to set it to four stages: medium, weak, and off.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a circuit diagram of the same, FIG. 3 is an operating waveform diagram of the mixer, and FIG. 4 is a waveform diagram showing the voltage between the induction heating coils. 1...Induction heating cooker, 2...Inverter, 3
...Induction heating coil, 4...Top plate, 5
... mixer, 6 ... power receiving coil, 7 ... rectifier smoothing circuit, 8 ... DC motor, 10 ... rectifier circuit,
11...Smoothing capacitor, Sa, Sb...Switch.

Claims (1)

[Scope of utility model registration request] In an electromagnetic induction device used in conjunction with an induction heating cooker that generates an asymmetrical voltage waveform between induction heating coils, a power receiving coil that is electromagnetically coupled to the induction heating coil is provided, and a power receiving coil is provided between the power receiving coil and the load. A rectifier circuit consisting of a diode bridge and a smoothing capacitor for smoothing the output of this rectifier circuit are inserted, and a switch is provided for each pair of diodes in the rectifier circuit, and by switching this switch, the full-wave rectified output can be changed to An electromagnetic induction device that obtains half-wave rectified output with two types of waveforms and is characterized in that the voltage applied to the load is controlled in four stages including an off state.