JPS635408Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a field control device for an alternator. In particular, when the generator is operating at a maximum rated output (current) or below, constant voltage control is performed, and when the generator is operating at the maximum rated output, the rotation speed is controlled. The object of the present invention is to provide a field control device having a function of lowering the output current in response to the increase. The present invention will be explained in detail below using the drawings. FIG. 1 is a circuit diagram showing one embodiment of the present invention, in which 1 is a three-phase alternating current generator, 2 is a three-phase full-wave rectifier formed by diodes D1 to D6, and 3 is a DC output of the rectifier 2. 4 is a starting switch, 5 is a field winding of the generator 1, and 6 is a battery that charges the field of the field winding 5 according to the output voltage of the generator 1 or the voltage of the storage battery 3. In the switching circuit that controls the magnetic current, voltage detection resistors R1 and R2
and the constant voltage diode DZ, and when the detected voltage reaches the Zener voltage of the constant voltage diode, conducts and short-circuits the current of the composite transistor base (side-circuit).
When the transistor Q1 is non-conducting (OFF), the resistor R
The composite transistor Q3 for field current control conducts when a base current is supplied through the field winding 5, and the moment the transistor Q3 becomes non-conductive, the field winding 5 becomes conductive.
It is formed by a field current commutating diode D7 and the like. Next, 7 is a limiter circuit that controls the switching circuit 6, and is controlled by a resistor R8 connected between the AC input terminal and the DC output terminal of the rectifier 2, the component circuit DC of the capacitor C1, and the output of the component circuit DC. It is formed of a transistor Q2 and the like that is conductive and short-circuits (bypasses) the base current of the composite transistor Q3. Note that R3 and R7 in FIG. 1 are resistors for stabilizing operation. Next, the operation of the present device will be explained with reference to FIGS. 2 and 3. First, the second
The figure shows the maximum output characteristics of generator 1 compared to the proposed device, where the horizontal axis is the rotation speed N (rPm) and the vertical axis is the output current.
(A), the output current _I0 of the generator 1 increases as the rotational speed N increases under heavy load as shown by curve A, and when it reaches the maximum output current shown at the middle point P in Figure 2, It is assumed that the current is constant regardless of the increase in the rotational speed N. (Note that this state is referred to as maximum rated operation.) Furthermore, it is assumed that the output current I ₀ of the generator 1 and the field current (hereinafter referred to as IF) are in a proportional relationship. FIG. 3 is an operational waveform diagram of each part of the apparatus according to the present invention.

<Operation 1 (Steady Operation)> When the starting switch 4 is closed while the generator 1 is not generating power, the terminal voltage of the storage battery 3 is applied to the switching circuit 6.

The Zener voltage of the constant voltage diode DZ where this terminal voltage is divided by resistors R1 and R2
The constant voltage diode DZ does not conduct when the Zener voltage VZ of VZ is not reached. Therefore, no base current flows through the transistor Q1, and the transistor Q1 is in a non-conducting state. Composite transistor Q for one-sided field current control
3, if the transistor Q1 is non-conductive, the base current flows through the resistor R5, so that the transistor Q1 becomes conductive.

When the composite transistor Q3 becomes conductive, a field current IF flows through the field winding 5, so that the generator 1 becomes ready to generate electricity. Furthermore, when the starting switch 4 is closed, the engine is started via an ignition device (not shown). The engine starts and generator 1
When started, it generates an alternating current voltage as shown in FIG. 3a. (Note that FIG. 3a shows the voltage waveform of only the W phase.) This AC voltage is full-wave rectified by the rectifier 2 to charge the storage battery 3, and is also supplied to other loads (not shown).

The following explanation will be given while ignoring the limiter circuit 7 in FIG. The terminal voltage VB of the storage battery 3 gradually increases as charging progresses, and when it reaches the Zener voltage Vz at time t1 shown in FIG. 3C, the constant voltage diode DZ becomes conductive, and the transistor Q1 also becomes conductive.
(Fig. 3 d) On the other hand, the composite transistor Q3 becomes non-conductive (Fig. 3 e), and the field current IF in the field winding 5 decreases (Fig. 2 h). As a result, the output of the generator 1 decreases. , the terminal voltage of the storage battery 3 also decreases due to load power supply, etc., and the Zener voltage increases again at time t2.
When it goes below Vz, contrary to the above, transistor Q1
is non-conductive, and the composite transistor Q3 becomes conductive, increasing the AC output and increasing the terminal voltage of the storage battery 3.
Let VB rise again. By detecting the terminal voltage of the storage battery 3 in this way, the current in the field winding 5 is increased or decreased depending on the magnitude of the voltage, and the generator 1
Adjust the output voltage to a certain value. Next, the operation of the limiter circuit 7 will be explained. First, generator 1
An AC voltage proportional to the rotation speed (Fig. 3a) is generated in each phase (UVW) of the rectifier 2, but a storage battery 3 is connected between one end of the AC input and one end of the DC output of the rectifier 2 as shown in Fig. 2b. A clamped, substantially square wave output voltage is thus generated. (Note that this voltage is a voltage waveform with a frequency proportional to the rotation speed of the generator 1.) Then, this output voltage is input as a rotation speed detection signal to the differential circuit DC of the resistor R8 and the capacitor C5, as shown in FIG. As shown in f, time t2-t
3, a component current flows. On the other hand, transistor Q2
becomes conductive as shown in FIG. 3g while the component current flows through the base. When the transistor Q2 is conductive, regardless of the non-conductive state of the transistor Q1,
In order to short-circuit (shunt) the base current of the composite transistor Q3 through the resistor R5, the composite transistor Q3 during this period is charged at a time t2 as shown by the dotted line in FIG. 3e.
It becomes non-conductive for ~t3, and the field current commutates to diode D7 and decreases. (Fig. 3h) Therefore, if the limiter circuit 7 is ignored as described above, the storage battery 3
reaches the Zener voltage Vz of the voltage regulator diode DZ at time t4 after time t2, but due to the insertion of the limiter circuit 7, the rise of the terminal voltage of the storage battery 3 is delayed, and at time t5, the Zener voltage decreases.
As a result, the composite transistor Q3 remains conductive until time t5 (the third
Figure e) Because the field current IF flows (Figure 3 h), the output voltage of the generator 1 can be adjusted to a certain constant value in the same way as above.

<Operation 2 (Maximum rated operation)> The power consumption of in-vehicle equipment, etc. increases, and the generator 1
When reaches the maximum current state shown at point p in Figure 2, the output current reaches a saturation state and can no longer be increased despite an increase in the rotational speed.

When this state is reached (t6 in FIG. 3), the terminal voltage VB of the storage battery 3 no longer reaches the Zener voltage Vz of the constant voltage diode DZ, and the transistor Q1 maintains a non-conducting state (d in FIG. 3). If the limiter circuit 7 is ignored, the composite transistor Q3 continues to conduct during this time (e in FIG. 3). As a result, the field winding 5 continues to pass current after time t6 as shown in h in FIG. 3, and the maximum rated operation of the generator 1 is maintained. In other words, the output current of the generator 1 remains almost constant regardless of the increase in the rotation speed, and since the terminal voltage of the storage battery 3 cannot be increased, the switching circuit 6 forms only a closed circuit, and as a result, the temperature of the generator 1 rises through the engine (not shown), and as a result, the generator 1 or circuit components such as the rectifier are exposed to the risk of thermal destruction. Therefore, the limiter circuit 7 turns on the transistor Q2 for a certain period of time in response to the number of revolutions of the generator 1, and turns off the composite transistor Q3 (FIG. 2e).
(t9-t10, t11-t12) The field current IF from the power source is cut off, and the output current of the generator 1 drops (dotted line B in Fig. 2). Now, if the circuit constants of the limiter circuit 7 are set so that the conductive time of the transistor Q2 (times t2-t3, t7-t8, etc. in Fig. 2) is constant regardless of the rotation speed of the generator 1, in other words, if the conductive time of the transistor Q2 in each cycle, i.e., the non-conductive time of the composite transistor Q3, is set constant regardless of the increase in the output frequency of the generator 1 that accompanies the increase in the rotation speed, the proportion of the non-conductive time of the composite transistor Q3 increases in proportion to the high speed rotation, and the amount of drop in the output current increases in proportion to the increase in the rotation speed of the generator 1, as shown in the characteristic curve of the device of this invention (B in Fig. 2). Incidentally, in Fig. 2, when the rotation speed N of the generator 1 is
At 8000 rpm, the time required for one rotation is 7.5 ms.
(8000/60sec), and in this state, the field current IF is cut off by 27%. In other words, if the output current is set to operate at a 27% drop, at 4000 rpm, the
The droop is 13% (7.5 x 0.27/4000/60). In this way, when operating at maximum rated output, the amount of output current droop can be adjusted according to the generator's rotation speed, allowing for safe operation with reduced heat generation in the generator. It is clear that the amount of droop can be freely controlled by adjusting the constant of the limiter circuit 7. However, in this case, in the differential circuit DC, the capacitor C1 is connected to the resistor R8 and
It is necessary to set it so that the discharge is completed via R7 etc. As is clear from the above explanation,
According to this invention, when the generator is operating at its maximum rated output, the amount of output current drop can be adjusted in accordance with the increase in rotation speed, making it possible to operate the generator with reduced heat generation. Furthermore, until the generator reaches its maximum rated operation, the output voltage or terminal voltage of the storage battery can be adjusted to a constant value, making this device particularly suitable for controlling on-board generators, and providing extremely significant practical benefits.

[Brief explanation of the drawing]

FIGS. 1 and 3 are circuit diagrams of an embodiment of the present invention and operation waveform diagrams of each part thereof, and FIG. 2 is a maximum output characteristic diagram of a generator compared with the apparatus of the present invention. In the figure, 1 is a three-phase alternating current generator, 5 is its field winding, 2 is a three-phase full-wave rectifier, is its AC input terminal and DC output terminal, 3 is a storage battery, 4 is a starting switch, and 6
is a switching circuit, R1, R2, R3, R5, and R7 are resistors, DZ is a constant voltage diode, Q1 is a transistor, Q3 is a composite transistor, 7 is a limiter circuit, DC is a differential circuit, and Q2 is a transistor.

Claims (1)

[Scope of utility model registration request] It consists of a storage battery that is charged through a rectifier by the output voltage of the alternating current generator, a main transistor for controlling the field current of the alternator, and a control transistor that controls the main transistor based on the detected output of the output voltage or the storage battery voltage. a limiter circuit comprising a switching circuit, a resistor and a capacitor, and a distinguishing circuit for distinguishing the output waveform of the alternator, and a transistor that is made conductive by the output pulse of the distinguishing circuit; A field control device for an alternator, characterized in that it controls a main transistor.