JPH01152962A - Frequency converter - Google Patents

Abstract

PURPOSE:To miniaturize a frequency converter and to dispense with cooling, by using a superconducting reactor made of superconductive materials between a diode and a capacitor. CONSTITUTION:A frequency converter is composed of a diode 1 to rectify the input power supply, a smoothing reactor 2, a smoothing capacitor 3, a waveform generation circuit 4, a transistor drive circuit 5, and a power transistor 6, and drives a motor 7. On this occasion, as a component material for winding a superconducting reactor 2 composed of superconductive materials is used. Among these superconductive materiale is a composition of SrBeYCu3O7-delta which shows superconductivity at nearly the room temperature. As no output voltage drop is thereby caused to the superconducting reactor, no generated torque will be reduced to a motor connected to the power output of the frequency converter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a frequency conversion device that can arbitrarily change the rotational speed of an electric motor.

BACKGROUND OF THE INVENTION In recent years, frequency conversion devices have been widely used in order to increase capacity and reduce power consumption by varying the rotational speed of compressors and blower motors in air conditioners, refrigerators, etc.

FIG. 2 shows a schematic configuration diagram of a conventional frequency conversion device. 1
is a diode that rectifies the input power supply, 2' is a reactor that smoothes the rectified voltage, and 3 is a smoothing capacitor. 4 is a waveform generation circuit that generates a waveform signal of a desired frequency and voltage; 6 is a waveform generation circuit that receives the output of this waveform generation circuit;
A transistor drive circuit 6 that amplifies this signal is a power transistor that inputs the output of this transistor drive circuit to its base terminal and converts the output voltage of the capacitor 3 to an arbitrary frequency and voltage, and is connected to a motor 7. There is.

To explain the operation of the conventional frequency converter configured as described above, first, a three-phase AC input power source is subjected to full-wave rectification using diode 1, and then full-wave rectification (pulsation) is performed using reactor 2' and capacitor 3. smooth the current) and convert it to direct current. On the other hand, the waveform generating circuit 4 generates a waveform of a desired frequency, the transistor drive circuit 5 amplifies the signal, and applies the signal to the power transistor 6. The converted voltage is converted into a waveform having the same shape as the output signal of the waveform generating circuit 4. That is,
By applying alternating current with a desired frequency and voltage to the electric motor 7, it becomes possible to change the rotation speed of the electric motor.

Problems to be Solved by the Invention However, in the frequency conversion device described above, when the output of the electric motor 7 becomes large, that is, the required torque becomes large,
The voltage drop in the reactor 2' increases, and as a result, the output voltage of the frequency converter, that is, the voltage applied to the motor 7 decreases, making it impossible to obtain the desired torque.

In addition, in such a case, since the current flowing through the reactor is large, there is a problem of increasing the size of the reactor with heat generating holes, increasing the cost of installing a cooling fan, etc. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a product that provides a desired torque to an electric motor and that reduces the size and cost of a reactor.

Means for Solving the Problems The present invention includes a superconducting material reactor made of a superconducting material between a diode and a capacitor.

Function According to the present invention, by using the superconducting material reactor, the resistance at both ends of this reactor is "0", so that
There is no voltage drop between both ends, and even when the required torque of the motor is large, there is no voltage drop in the frequency converter, and the desired torque can be obtained. In addition, since there is no resistance, there is no loss, and it is small and does not require cooling, reducing costs.

Embodiment An embodiment of the present invention will be explained with reference to FIG. Components with the same name and operation will be given the same number and the explanation will be omitted.

2 is a superconducting material reactor using a superconducting material as a constituent material of the winding, and this superconducting material is room temperature-resistant. That's 92
After firing in air at 0"C for 6 hours, it was crushed and
Turn the edge three times.

The powder is shaped, sintered by heating at 1000° C. in air for 5 hours, and cooled in a furnace. The sintered body produced in this manner exhibits superconductivity at 338K (65°C).

(Ihara et al., Japan Journal of Applied Physics (JAPANESE l0UFLN)
AL OF APPLI] 1DPHYSIC8), VO
L 26. A8. August 1987゜PP16
7-171'I.

The other components are the same as those of the conventional example, and the operation of the present invention configured as described above is as follows: Full-wave rectification is applied to the 9-phase AC input power source using diode 1, and superconducting material reactor 2 and capacitor 3 A highly smoothed DC voltage is generated, but since the resistance between both ends of the superconducting reactor is ``0'', the smoothing effect is the same as in the conventional method, but the voltage drop and heat generation are negligible. The subsequent operations are the same as those in the conventional example, and will therefore be omitted.

Therefore, since the frequency converter with the above configuration uses a superconducting material as a reactor, it does not reduce the desired torque of the electric motor, and since it does not generate heat, it is compact and does not require cooling, etc. .

Effects of the Invention As is clear from the above explanation, the present invention comprises a diode for rectifying input power, a capacitor for smoothing the rectified voltage, and a power transistor for converting the smoothed voltage into an arbitrary frequency and voltage. a waveform generation circuit that generates a waveform signal of arbitrary frequency and voltage; a transistor drive circuit that receives the output of this waveform generation circuit and drives the power transistor; and a transistor drive circuit that is arranged in series between the diode and the capacitor. Since it is equipped with a superconducting material reactor made of superconducting material, there is no drop in output voltage, so the generated torque of the electric motor connected to the output of the frequency converter does not decrease, which can greatly contribute to improved performance. .

In addition, since there is no loss in the reactor, it is small and does not require cooling, which has great effects such as low cost and the ability to contribute to product expansion.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a frequency converter according to the present invention, and FIG. 2 is a schematic diagram of a conventional frequency converter. 1... Diode, 2... Superconducting material reactor, 3... Capacitor, 6... Power transistor, 4... Waveform generation circuit, 6.
...Transistor drive circuit, 7...
Electric motor.

Claims (1)

[Claims] A diode that rectifies the input power supply, a capacitor that smoothes the rectified voltage, a power transistor that converts this smoothed voltage to any frequency and voltage, and a waveform generation circuit that generates a waveform signal of any frequency and voltage. and,
A frequency conversion device comprising: a transistor drive circuit that receives the output of the waveform generation circuit and drives the power transistor; and a superconducting material reactor that is arranged in series between the diode and the capacitor and is made of a superconducting material. .