JPS60109799A - Self-excited induction generator - Google Patents

Abstract

PURPOSE:To reduce the rotating speed for establishing an output voltage by flowing a direct current through an output winding during the prescribed time before starting an induction generator, thereby increasing the magnetic flux of a rotor. CONSTITUTION:When an operation switch 18 is closed, a relay R and a timer relay T are energized. Thus, a relay X is energized, and a direct current is flowed from a battery 16 to the output winding 9 (between V-phase and W-phase terminals) of an induction generator 7. When the contact T1 of the timer is opened, the energization of the relay X is interrupted. Thus a microprocessor 20 is operated, and an engine 12 is driven. Thus, the output voltage is established at the low rotating speed, and the established voltage can be simultaneously reduced. Accordingly, the rush current generated at the voltage establishing time can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention is applicable to the operation control of a self-exciting induction generator equipped with an electric rotor, an output winding, and a self-exciting condenser. This relates particularly to control at startup.

(b) Prior Art In general, self-exciting induction generators, which are equipped with an electric rotor, an output winding, and a self-exciting capacitor, generate electricity by driving the rotor with an engine or the like. In this case, when the induction generator was self-excited by the reactive current flowing through the capacitor, its characteristics were as shown in FIG. In other words, in this figure, the horizontal axis is the exciting current (reactive current), the vertical axis is the output voltage of the induction generator, and (1) and (2) are straight lines showing the no-load saturation characteristics of the induction generator, and the rotor These are the characteristics when the rotational speed of Hf I+ is '1.51''.

(3)' and (4) are straight lines showing the charging voltage characteristics of the capacitor used for self-excitation, and the slope of this line is 6β'', where the angular velocity of the rotor is 6ω, and the capacitance of the capacitor is MC11, β=tan- 1α/azC). curve(
In 1), the capacitance of the capacitor is selected so that the straight line (3) intersects at point P, and the straight line (4)
It is a corresponding straight line to straight line (3) when the rotational speed of the induction generator is 1.5f'', and it intersects curve (2) at point P2.If the rated rotational speed of the induction generator is 6f'', then curve (1) and straight line (3)
There is 1 ktor from the induction generator to the capacitor (5).
A leading current of 9ff' expressed as follows flows, and the output voltage of this induction generator is established at a point P1 where this leading current no longer flows to the capacitor. That is, at this point P1, the output winding is self-excited by the 90° advance current (excitation current) flowing as a reactive current in the capacitor, and the generator can obtain stable power generation at the rated rotation speed. Therefore, if the capacitance of the capacitor for self-excitation is selected so that it forms a straight line (6), a 90° lead current will not flow from the induction generator to the capacitor and power generation will not occur, so the capacitance of the capacitor will be determined by the straight line (6). It is necessary to make the capacity larger than the capacity used in 6). As can be seen from FIG. 1, if the capacitance of the capacitor is increased, the value of the output voltage established by this generator/electric machine increases.

Also, the capacity of the capacitor is the same as the capacitor used for the straight line (3), and the rated rotation speed of this generator is set to '1.51'.
”, the establishment of the output voltage (■2) becomes point P2.

At this time, since the charging voltage characteristic of the capacitor is related to the frequency, the slope changes as shown by straight line (4). Therefore, when driving an induction generator with such characteristics that the voltage establishment point will change as the rotation speed of the rotor changes, the output II E n of this generator will change the number of poles of the generator by P ”,−
If the number of series coils in a phase is ``L'', the magnetic flux of the rotor is Φ'', and the rotation speed of the rotor is ``N6'', then the output voltage is generally expressed as 'E=P@φN,/60''. When the output voltage from the induction generator reaches E=e'', a reactive current begins to flow into the capacitor installed for self-excitation, and a self-excitation effect occurs, causing a sudden increase in the value of the magnetic flux ``eg''. A point is reached where the voltage builds up. In other words, when the induction generator is started while gradually increasing the rotation speed of the rotor of the induction generator, the voltage is instantaneously established at the rotation speed ``N, n'' where the output voltage of the induction generator becomes E=e''. It is something. Note that the above output voltage "C" is determined to be a constant value based on the mechanical characteristics of the induction generator and the capacitance of the capacitor.

For example, 3-phase, 2-pole, rated output is 200 (V), 20'
0 (W), rated rotation speed is 3000 ([p13) When a self-excitation capacitor with a capacity of 14 [μF] is connected to an induction generator, the output voltage "e" at which reactive current begins to flow from the induction generator to the capacitor ” is experimentally approximately ”g=5 (
V). Therefore, the output voltage "E" is E = e"
The rotational speed N is determined by the above relational expression ``E=chicken/raw/N,/
It can be seen that from 60'', the magnetic flux changes by 1 depending on the magnetic flux of 11.

In other words, when the value of "magnetic flux" is small, the rotation speed of the rotor must be increased to prevent self-excitation and power generation, and when the value of "magnetic flux" is large, the rotation speed of the rotor must be increased. Even if it is small, a self-excitation effect occurs and power generation starts. Specifically, if the rotation speed of the rotor of this induction generator is sequentially increased and started in a no-load state, the rotation speed of the rotor "
When Ng" becomes "N, = 3200 (rpm)", a reactive current begins to flow to the capacitor and the output voltage of the induction generator is established, and the established voltage at this rotational speed "N, = 3200 (A)" is 6. ■ = 230 (V)''.The value of this established voltage is determined by the intersection of the above-mentioned no-load saturation characteristic curve of the induction generator and the straight line of the charging voltage characteristic of the capacitor used for self-excitation. After this output voltage was established, the load was connected.If an R (resistive) load was used for this load, the same as above was repeated after stopping the induction generator. However, when an L (inductance) load such as a motor is used as this load, when the induction generator is stopped, the rotor is damaged due to the demagnetization effect of the L load. In this state, the value of the magnetic flux 1 strain of the rotor is extremely small (this state occurs when the induction generator is stopped for a very long time).
If the same start-up as above is performed again at a time when the output voltage becomes E=e", the rotational speed at which the output voltage becomes E=e" becomes extremely high, for example, N=4000 (rW).
There were cases where this happened. The established voltage at this time is “V=360
(V)''.When the value of magnetic flux 1g is small like this, it is necessary to make the rotational speed at startup extremely high compared to the rated rotational speed, which may damage the bearings of the induction generator. In addition, since the output voltage suddenly becomes established after the output voltage becomes E=C'', a rush current flows into the self-excitation capacitor at this time, which may damage the capacitor. Furthermore, considering the starting characteristics of such induction generators, they cannot be used for L loads.

(c) Purpose of the Invention In view of the above problems, the present invention provides a self-excited induction generator that improves the starting characteristics by increasing the magnetic flux of the rotor at the time of starting the induction generator and reducing the number of revolutions at which the output voltage is established. It provides a generator.

B) Structure of the Invention The present invention provides a self-exciting induction generator having an electromagnetic rotor, an output winding, and a self-excitation capacitor, in which the output winding is operated for a predetermined period of time before starting the induction generator. The rotor is equipped with a control circuit that applies direct current to the rotor to increase the magnetic flux of the rotor.

(e) Examples Examples of the present invention will be explained based on FIGS. 2 and 3. First, in FIG. 2, (7) is an electric type rotor (8),
It is a three-phase i-conductor generator with an output winding (9), rated output 200 (V), 200 (W), and rated rotation speed 300.
0 (rF), - phase winding resistance 6 [Ω], number of poles 2CP)
The same induction generator as used in the explanation of the conventional example is used. This is a capacitor for self-excitation of the α induction generator (7), and has a capacity of 14 [μF] and is connected between each phase. Note that (XI) and (X,) are the ■ of induction generator (7)
This is a switching contact piece provided on the phase terminal and the W-phase terminal, and it switches to the opposite side from the illustrated state when the relay (3) described later is energized. (G) is a voltage detection relay, which closes the contact piece (Y) when the voltage between the terminals exceeds a predetermined value. αB is this induction generator (which is a force load and is connected through contacts (zl), (Z2), and (Z3) of the relay (Z). 02) is the engine, which is connected to this rotating shaft. is the rotor of the induction generator (7) via the rotation speed detector α and the electromagnetic clutch (15+).
8) is connected.

Note that this electromagnetic clutch α9 is turned on when the relay (C) is energized. (16) is a battery with a rated voltage of 6 [■], and the switching contact (X
3) Contact piece (
It is connected to the cell motor α via Sl) and (Sz).

αn is a governor that controls the engine α and determines the rotational speed of the engine α based on the engine rotational speed setting signal from the control circuit described below and the output of the rotational speed detector α. The control circuit has a normally open operation start switch α barrel and a normally closed operation stop switch 0! J, a relay with a self-holding normally open contact piece <L) and normally open contacts (R6) and (R9) (the relays are connected in series to the power supply +cc. ) is connected in parallel with a timer relay (T'
), and this timer relay (T) has a normally closed timer contact (T, ) that opens after a predetermined period of time after energization. Also, the capacitors are the normally open contact (R2) and the timer contact (T,).
It is a relay that is energized via the above-mentioned switching contact (X
l ), (X, ), (X, ), (X4) and normally closed contacts (
X,).

Furthermore, (20) is a microprocessor, which starts operating when the normally open contact piece (R3) is closed and the power supply is connected, and the signal and rotation generated when the normally open contact pieces (X, ) and (Yl) are closed. Relay (Z) based on the rotation speed signal from the number detector 0th floor
, (C), (S) and at the same time, the governor (
17) outputs an engine rotation speed setting signal.

This microprocessor (a) operates based on the flowchart 1 shown in FIG. That is, the normally open contact piece (
When R5) is closed, the microprocessor screen is initialized and starts operating. Next, when the normally open contacts (X,) close, the relay (S) is energized and the normally open contacts (Sl), (S
Close 2). At this time, the relay (3) is de-energized and the switching contacts (X, ), (X4) are in the state shown in the figure. Therefore, current is supplied from the battery α6) to drive the cell motor α. Next, it is determined whether engine a has started or not, and if engine a'IJ has not started, starter motor α (a) is maintained, and if engine (1) has started, starter motor (14) is activated. At the same time, the relay (0) is energized and the electric layer clutch (151 is turned on. When the open contact piece (Y,) closes, the rotation speed of engine α2 is set to the rated rotation speed, and then the relay (Z+ is energized and the normally open contact piece (Z, )
, (Z2), and (Zs) are closed to supply current to the load.

When operating the self-exciting induction generator (7) configured as described above, first the operation switch α is turned on, and the relay (8) and timer relay (T) are energized. This closes the normally open contact piece (R2) and energizes the relay X. Therefore, switching contacts (Xl), (X, ), (X, ), (X4
) is switched and DC is energized from the batch IJ-(16) to the force output winding (9) (between the V-phase terminal and the W-phase terminal). This energization is carried out by the timer relay). This is maintained for a predetermined time (approximately 20 seconds) until the contact piece (T1) opens. When the timer contact (T,) opens, the power to the relay is cut off and the switching contacts (X,), (X,), (X3), (X
At the same time as 4) switches, the normally closed contact (X,) closes. This causes the microprocessor to operate based on the flowchart shown in FIG. 3, and the engine α2 is driven.

At this time, the terminal voltage at which the relay (g) operates is greater than the voltage at which the reactive current of the capacitor α0)K begins to flow, and is smaller than the established neutral voltage of the induction generator (7), so in effect The normally open contact (Y,) closes when the voltage of the induction generator (7) is established. Therefore, after the output voltage is established, the engine speed is controlled to the rated speed, and at the same time, current is supplied to the load (11).

When starting an induction generator (power) using this control circuit,
When the engine (2) rotational speed is approximately 2800 (rPl), a reactive current begins to flow into the capacitor QO at approximately 160 [:V].
The output voltage has been established. This allows the output voltage to be established at a lower rotational speed than the conventional startup method, and at the same time the established voltage can be lowered, making it possible to reduce the rush current that occurs when the voltage is established.

In the above embodiment, the load is kept constant, but if this load changes, the output voltage of the induction generator (7) will also change at the same time, so the capacitance of the self-excitation capacitor α0 should be made variable. Good. For example, the amount of reactive current flowing to the capacitor αα may be controlled by the triac, and at the same time, the firing angle of the triac may be controlled by the output of the microprocessor. In addition, if this induction generator (power is driven by something whose rotational speed cannot be controlled, such as a turbine), a transmission mechanism may be provided and control may be performed by changing the gear ratio of this transmission mechanism. Although the power supply for the control circuit is provided separately, if it can be supplied while performing float charging using batch IJ-10, it can be operated independently without using an external power supply. Needless to say, similar effects can be obtained when used in an excitation type induction generator.

(f) Effects of the Invention As described above, the self-exciting induction generator of the present invention includes an electric rotor, an output winding, a self-exciting capacitor, and a predetermined period of time before starting the induction generator. Since the rotor is equipped with a control circuit that supplies direct current to the output winding, a predetermined magnetic flux is always applied to the rotor during startup, and an output voltage can be established at a predetermined startup rotation speed. Therefore, the output voltage can be established at a lower rotational speed than when the magnetic flux of the rotor is small as in the conventional case. That is, the establishment voltage can be lowered, and the rush current when the voltage is established can be reduced. Furthermore, it is possible to prevent losses in various parts due to high rotation at the time of startup.

[Brief explanation of drawings]

FIG. 1 is a no-load saturation characteristic diagram of an induction generator, FIG. 2 is a schematic diagram showing an embodiment of the present invention, and FIG. 3 is a flowchart showing the operation of the microprocessor used in FIG. (7)...Self-excited induction generator, (8)...Rotor, (9)...Output winding, Q(lI capacitor).

Claims (1)

[Claims] (1) In a self-exciting induction generator having an electric type rotor, an output winding, and a self-excitation capacitor, direct current is applied to the output winding for a predetermined period of time before starting the induction generator. A self-exciting induction generator characterized by being equipped with a control circuit.