JPS60261399A - Operating method of induction generator - Google Patents

Abstract

PURPOSE:To improve the power factor by using an induction generator as a voltage reducing starting motor, and operating it by the reduced voltage at a light load time as it is. CONSTITUTION:When a switch 4 is closed to close a changeover switch 3 to left side, the stator winding 2 of an induction generator 1 are coupled in a Y- connection, operated as a motor to start an engine. After the completion of the start is confirmed by a rotation detector 5, a load state is detected by a load rate detector 6. The switch 3 is closed at the left side at a light load time, the voltage between the phases is reduced, the exciting current is limited to prevent the power factor from decreasing. On the other hand, when the load rate is large, the switch 3 is closed at the right side as a delta-connection to operate in high power factor. Thus, it can prevent the power factor from decreasing at a light load time to operate in a high power factor.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to engine-driven induction generators, and more particularly to engine-driven induction generators.

This invention relates to a method of operating an induction generator in which the power factor is improved by using the generator as a reduced-voltage starting motor and operating it at reduced voltage during light loads.

[Background of the invention]

The driving force when the engine is driven is generally started by a cell motor powered by a battery, and the equipment required for this is complicated, and this accounts for most of the troubles that occur.

In addition, although induction generators do not require an excitation device or automatic voltage device, the excitation current received from the power source is 30 to 40% of the rated current.
0%, and as a result of operating with a reduced power factor of the receiving power, this was a factor that hindered its widespread use.

The tendency for the power and power factor to decrease is particularly noticeable during light load operation, and it was necessary to improve the power factor by using a phase advance capacitor.

[Purpose of the invention]

The purpose of the present invention is to improve the power factor of receiving power even during light load operation even when using a simple induction generator, and to use the generator as is for starting, eliminating the need for a starter motor and related purse equipment. The purpose of the present invention is to provide a simple and reliable method of operating an induction generator that increases operating efficiency.

[Summary of the invention]

The excitation current received from the power received by the induction generator is approximately inversely proportional to the number of turns of the stator winding wound around the iron core, that is, the phase-to-phase voltage, and during light load operation, the ratio of this excitation current to the active current is This is the cause of the decrease in power factor. At light loads, the current density in the windings is also small, so it is possible to change the current distribution and use the number of turns in series.

The key point of the present invention is to reduce the excitation current and improve the power factor by changing the connection of the stator windings during light load operation.

In addition, if the phase voltage is lowered by this winding switching and used as an induction motor, if the starting current is limited and used as a starting motor, the engine-driven induction generator will self-start,
After acceleration, the speed can be increased further and it can automatically operate as an induction generator.

[Embodiments of the invention]

The present invention will be described below based on an embodiment using a large-Δ switching method of an induction generator stator winding.

1 In FIG. 1(a), 1 is an induction generator driven by an engine (not shown), and 2 is its stator winding. Reference numeral 3 denotes a changeover switch that changes the phase-to-phase voltage of the stator winding 2. That is, when the switch 3 is closed to the right, the stator winding 2 becomes Y-connected as shown in Fig. 1(b), and each phase winding has one
//A voltage of terv is applied.

Next, if switch 3 is closed to the left, Δ shown in No. 18(c)
Since it is wired, full voltage is applied to each phase winding, allowing full load operation.

That is, if the switch 4 is turned on, the selector switch 3 is closed to the left, and the engine is started with a Y connection, the starting current is limited and the engine starts smoothly. After the rotation detector 5 confirms that the start has been completed, the load factor detector 6 operates the selector switch 3 according to the load condition, closing it to the left or right.
Figure (b) lowers the phase-to-phase voltage and limits the excitation current.
(See Figure 3) Prevent the power factor from decreasing. Also, when the load factor is large, the stator winding 2 will overheat if left as is.
Since the load factor detector 6 and the changeover switch 3 are operated to operate with the connection shown in FIG. 1(e), it is possible to operate at a high power factor throughout the load operation.

In FIG. 2, E//d indicates the operating state in FIG. 1(b), and the exciting current is AI'. Also, E is shown in Figure 1(c)
are the phase voltage and its excitation current A.

In Figure 3, φ1 indicates the power factor at full load operation i (Figure 1 (C)), and φ2 indicates the power factor at approximately 1/2 load, where the drop in power factor is noticeable, and the excitation current A is constant. This is because.

φ2' indicates the power factor when the load factor detector 6 and changeover switch 3 are operated under the same load operation. With this operation method, φ2
It is possible to improve the power factor from φ2' to φ2'.

Although the present invention uses the human-Δ switching system, it is clear that the same effect can be obtained by switching the stator windings in series and parallel.

〔Effect of the invention〕

According to the present invention, even an engine generator using a simple induction machine can prevent a decrease in power factor under light loads and achieve high power factor and high efficiency operation. In addition, the fact that it can be operated with a lower correlated voltage means that it can be easily used as a starting motor, eliminating the need for ancillary equipment such as starter motors and contactors from the engine, and eliminating the need for ancillary equipment such as batteries and charging plates. It is possible to provide a simple engine-generator operating method that can save money and improve reliability.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram of the induction generator, 2VA is a diagram showing the relationship between the phase voltage and excitation current of the induction machine, and FIG. 3 is a vector diagram showing the relationship between the load current and power factor in FIG. ■... Induction generator, 3... Selector switch, 5...
Rotation detector, 6... Load factor detector. Agent Patent Attorney Akio Takahashi Waka 2fJ Kiyoshi JflJ 513-

Claims (1)

[Claims] (2) In an induction power generation device consisting of an induction generator driven by an engine and a voltage changeover switch operated by an engine rotation detector and a load factor detector, when starting the engine, the induction generator is started at a reduced voltage. and, after acceleration, automatically switches to power generation operation, and adjusts the operating power factor of the induction generator by switching the stator winding phase voltage with the voltage changeover switch according to the load factor. How to operate a generator.