JPH07298584A - Squirrel-cage self-excited single-phase induction generator - Google Patents

Abstract

PURPOSE:To obtain a squirrel-cage self-excited single-phase induction generator, wherein the leading current of the generator is automatically changed without increasing and decreasing the capacitance a capacitor in response to load changes. CONSTITUTION:A squirrel-cage three-phase induction machine, and two capacitors 4, which are connected in series, are connected between two terminals of the three-phase terminals of a stator. A single-phase load 5 is obtained from the mutually connecting point of two capacitors and from the remaining one terminal of the three-phase terminals.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a squirrel-cage self-excited single-phase induction generator in which a capacitor is connected to a generator terminal and an electric current is supplied to the capacitor to generate self-excited electric power.

As is well known, when a capacitor is connected between the stator terminals of a cage single-phase induction machine driven at a synchronous speed or higher, a residual magnetism of the rotor core causes a current to flow through the capacitor, causing a self-excitation phenomenon. As a result, the stator is held at a certain terminal voltage. At this time, if a single-phase load is connected in parallel with the capacitor, it can be operated as a squirrel-cage self-excited single-phase induction generator.

However, in the conventional squirrel-cage self-excited single-phase induction generator configured as described above, when the capacity of the capacitor is constant, the forward current supplied to it depends on the load. Since it cannot be adjusted, the fluctuation of the output voltage becomes large. Therefore, in order to obtain a constant output voltage, it is necessary to adjust the capacitance of the capacitor according to the load change.
The present invention has been made to solve the above-described problems, and the lead current of the capacitor automatically changes in response to a load change without adjusting the capacitance of the capacitor, resulting in fluctuation of the terminal voltage. The purpose is to obtain a cage-type self-excited single-phase induction generator that can be compensated.

[Means for Solving the Problems] A squirrel-cage three-phase induction machine is used to connect two of the three-phase terminals of the stator in series.
A set of capacitors is connected, and a single-phase load is taken from the point where these two sets of capacitors are connected to each other and the remaining one terminal of the three-phase terminals.

The function of the squirrel-cage self-excited single-phase induction generator according to the present invention is as follows.
Since the load current flows directly through the capacitor, the lead current of the capacitor automatically changes even if the capacitance of the capacitor is not adjusted for load changes, and the output voltage can be kept constant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a wiring diagram of a squirrel cage self-excited single-phase induction generator according to the present invention. When the rotor is rotated at a speed equal to or higher than the synchronous speed, a forward current due to the capacitor 4 flows in the stator winding 2, and the self-excitation phenomenon thereby keeps the stator at a certain terminal voltage. Therefore, if electric power is supplied to the single-phase load 5 from the point where the capacitors 4 are connected to each other as shown in FIG. Further, according to this connection, the current flowing in the single-phase load 5 directly flows through the capacitor 4, so that the lead current of the capacitor 4 automatically changes according to the load, and the fluctuation of the terminal voltage can be compensated. For example, in the case of a resistance load, a waveform 6 of the terminal voltage as shown in FIG. 2 is obtained, and this voltage shows a constant voltage characteristic 7 as the load current increases as shown in FIG. 3, and becomes almost constant.

As described above, according to the present invention, the variation of the terminal voltage can be automatically compensated for the load change only by connecting the capacitor to the stator terminal of the squirrel cage three-phase induction machine. However, a simple and inexpensive single-phase AC generator can be obtained.

[Brief description of drawings]

FIG. 1 is a wiring diagram of a squirrel-cage self-excited single-phase induction generator according to the present invention.

[Fig. 2] Waveform of generator terminal voltage (example)

[Fig. 3] Output voltage characteristics of the generator (example)

[Simple explanation of symbols]

 1 ... Cage type three-phase induction machine 2 ... Stator three-phase winding 3 ... Cage type rotor 4 ... Capacitor 5 ... Single-phase load

Claims (1)

[Claims] 1. A squirrel-cage three-phase induction machine is used to connect two sets of capacitors connected in series between two terminals of three-phase terminals of a stator, and to connect these two sets of capacitors to each other. A squirrel-cage self-excited single-phase induction generator, in which electric power is supplied to a single-phase load from the remaining one of the three-phase terminals, and the advance current due to the capacitor can be automatically adjusted according to the load.