JPS61196735A - Power generation apparatus with voltage adjusting function - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power generation device with a voltage adjustment function used in vehicles and general industry, and particularly when the excitation coil itself is short-circuited or due to incorrect wiring etc. This invention relates to a short-circuit protection circuit that reliably shuts off and protects the switching means when a power supply voltage is accidentally applied directly to the means.

[Conventional technology]

Conventionally, a voltage regulator has a voltage regulation function equipped with a short-circuit protection circuit that forcibly shuts off the switching means when the switching means is accidentally connected to a battery terminal due to a short circuit between both ends of the excitation coil. A power generating device according to the present invention is shown in, for example, Japanese Patent Application Laid-open No. 13628/1983.

[Problem that the invention seeks to solve]

Problems with this conventional configuration will be explained below with reference to FIG. 1 related to the present invention.

In FIG. 1, when the positive side voltage of the battery is directly and erroneously applied to the output terminal F (hereinafter referred to as F terminal) of the output transistor 7 serving as the switching means (see FIG.
At time tI) in B), the conventional circuit is configured so that the output transistor 7 is reliably and forcibly controlled to be in the cut-off state at time t2. In addition, Fig. 2 (A), (B
) is a collector voltage base voltage waveform diagram of the output transistor 7, with time t plotted horizontally and voltage V plotted vertically.

When the excitation coil 4 itself is short-circuited, for example between the eyebrows, an inductive short-circuit current flows through the inductance of the excitation coil (at time t) and the transistor 7
The holes in the flywheel diode 6 flow in the forward direction from the anode side to the cathode side, and gradually decrease until they reach zero, and then the holes in the flywheel diode 6 are A recovery current flows through the flywheel diode 6 in the opposite direction (from the cathode to the anode side) until the accumulated carriers of electrons are completely moved.

Then, when the accumulated carriers in the flywheel diode 6 disappear and the recovery current stops flowing, and the flywheel diode 6 becomes reverse biased, the recovery current that has been flowing until now suddenly stops flowing (time t3), so that the excitation coil A back electromotive force e is generated at both ends. Then, the potential of the F terminal of the output transistor 7 becomes the counter electromotive force e.
Therefore, the short-circuit protection circuit that uses this F terminal potential as a short-circuit detection signal determines that the above-mentioned interlayer short circuit has become normal due to the instantaneous potential drop, and cancels the short-circuit protection. As a result, the output transistor 7 becomes conductive again at time t4.

However, in reality, the glabella short circuit mentioned above has not been normalized, so by re-conducting transistor 7,
Short circuit current flows again. Since this short-circuit current flows through a part of the excitation coil 4, it flows through the inductance of the excitation coil 4, and thus becomes an inductive short-circuit current as described above. Then, in order to detect this short circuit current by the short circuit protection circuit, the transistor 7 is forcibly cut off.
An inductive flywheel current flows through the flywheel diode 6 in the forward direction.

This flywheel current gradually decreases, and when it reaches zero, a cover current flows through the flywheel diode in the opposite direction. Next, when the flywheel diode is turned off, the recovery current suddenly stops flowing, and as a reaction, a back electromotive force e is generated.

Therefore, the potential of the F terminal decreases, and the output transistor 7
However, conduction occurs again at time t. By repeating this operation, the output transistor 7 turns on and off,
In other words, when the output transistor 7 oscillates and is on, a short circuit current flows through the output transistor 7, and the output transistor 7
has an abnormal fever. Therefore, the output transistor 7 may be destroyed.

Therefore, in view of the above-mentioned problems, it is an object of the present invention to prevent the output transistor from oscillating even if the excitation coil is short-circuited, and to reliably interrupt and protect the oscillation.

[Means for solving problems]

To this end, the present invention provides an alternating current generator including an armature coil, an exciting coil, and a rectifier that rectifies the alternating current output from the armature coil, a switching means that intermittents the exciting current of the exciting coil, and a direct current of the rectifier. a battery that is charged by the output; a voltage adjustment circuit that controls the switching means according to the voltage of the armature coil or the battery; and the switching means when a voltage higher than normal is applied to the output terminal of the switching means. is placed in a power generation device having a voltage regulation function that includes a protection circuit that forcibly shuts off the switching means to prevent the protection circuit from malfunctioning between the output terminal of the switching means and the protection circuit. It is equipped with a delay circuit.

[Function] By providing a delay circuit at the F terminal of the output transistor in this way, even if the F terminal potential momentarily drops due to a short circuit in the excitation coil itself, in other words, it remains unchanged from the normal state momentarily. Even if the voltage drops to the same voltage level, the time constant of the delay circuit, which is constructed by selecting an appropriate number, will cancel the instantaneous drop in voltage, so even if a short-circuit failure involving inductance occurs, it will be ensured. Provides short circuit protection.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is an overall circuit diagram of a vehicle power generation device including an embodiment of the voltage control device of the present invention, and FIG. 2(A).

(B) is a diagram showing an oscillation phenomenon of the output transistor in the case of a short-circuit failure involving inductance.

In Fig. 1, reference numeral 1 designates a vehicle generator, and in this embodiment, DC utility power obtained by rectifying three-phase AC voltage through a Y connection is supplied to a battery 2.
6 and a load (not shown). 2 is a voltage adjustment circuit.

Next, in each block 1.2, 3 is an armature coil,
4 is an excitation coil of the generator; 5 is a rectifier composed of a plurality of diodes for full-wave rectification of the generator output; 6 is an excitation coil 4 and a flywheel diode for absorbing back electromotive force;
7 is an output transistor as a switching means for cutting off the excitation current, and 8 is a delay circuit 21 whose inputs are a reference voltage obtained by dividing the constant voltage output of the constant voltage circuit 14 by voltage dividing resistors 19 and 20 and the F terminal voltage. Comparator 9 compares the output with the reference voltage created by the voltage dividing resistors 17 and 18 and the voltage dividing resistor 15 of the battery terminal (S terminal) voltage.
．． 10 is an inverter circuit for inverting the output of the reset pulse generation circuit 13 that generates reset pulses at a constant cycle; 11 is an inverter circuit output and a comparator 8;
A NAND AND circuit with 9 outputs as input is 12 BANA
This is an AND circuit which takes the ND circuit output and the output of the comparator 9 as inputs, and inputs the output to the output transistor 7. 25 is a key switch, and 26 is a battery. In addition,
The aforementioned delay circuit 21 includes resistors 22, 24 and capacitor 23.
This is a time constant circuit consisting of.

Since the constant voltage circuit 14 and the reset pulse generating circuit 13 are not the main part of the invention and their technology is well known, their explanation will be omitted here.

Next, its operation will be explained based on the above configuration.

In FIG. 1, when the key switch 25 is turned on, power is supplied from the battery 26 to the voltage control device 2 via the IG terminal. At this time, since the battery voltage is below the adjustment voltage, the output level of the comparator 9 becomes 1 because the voltage at the non-inverting input terminal is higher than the voltage at the inverting input terminal. On the other hand, since the output level of the NAND circuit 11 is 1 during normal operation, the output level of the AND circuit also becomes 1, turning on the output transistor 7 and causing an exciting current to flow through the exciting coil 4, so that the generator 1 starts generating electricity.

When the generator output voltage increases and the battery voltage becomes equal to or higher than the adjustment voltage, the output level of the comparator 9 becomes 0 level, so the output level of the AND circuit 12 is also inverted to 0 level, thereby making the output transistor 7 non-conductive. , interrupts the excitation current and stops power generation. When the battery voltage falls below the regulated voltage, the output transistor 7 starts conducting again, so the above operation is repeated and the battery voltage is maintained at a substantially constant value.

At this time, if terminals B and F are accidentally completely short-circuited, an excessive current flows into transistor 7 from battery 26 at the moment output transistor 7 becomes conductive, so that the F terminal voltage decreases to a value close to that of the battery. rise rapidly. Then, the output of the comparator 8 becomes Lebel. With the complete short circuit between B and F, the current in the exciting coil 4 disappears and power generation stops, so the output of the comparator 9 also becomes a level.

Therefore, since the outputs of the NAND circuit 11 and the AND circuit 12 are both at the 0 level, the output transistor 7 instantaneously becomes non-conductive, so that it is protected from power breakdown due to short-circuit current.

In addition, since a reset pulse is applied to the NAND circuit 11 at a constant period, after the short-circuit protection is activated and the power transistor 7 becomes non-conductive, the reset pulse instantly turns off the power transistor 7 at a constant period. Repeats the on state. At this time, the reset pulse is set to turn on the output transistor 7 for a very short period of time so that the output transistor 7 will not be destroyed even if the short-circuit condition continues for a long time. During this process, if a short circuit is avoided, that is, if the wrong connection between B and F is noticed and the connection is made correctly, the voltage at the F terminal will return to the low value of normal operation, so the output level of comparator 8 will be O. level, N
The output of the AND circuit 11 is returned to the normal level.

By turning the NAND circuit 11 into a level, the short circuit protection is released.

As mentioned above, if a short circuit failure such as an interlayer short circuit occurs in the excitation coil 4 itself, which has components of inductance and resistance, rather than a complete short circuit between B and F, a partial short circuit occurs between B and F with resistance and inductance intervening. A short circuit occurs, and this inductance generates an inductive short circuit current. At this time as well, the F terminal becomes at a high voltage level due to the short circuit current and exceeds the short circuit protection detection level of the comparator 8, so the comparator 8 detects a short circuit failure state and cuts off the T output transistor 7.

Therefore, the inductive short-circuit excitation current flowing through a part of the excitation coil 4 does not flow through the cut-off output transistor 7, but instead flows through the flywheel diode 6.

When this inductive current gradually decreases to zero, a recovery current flows in the flywheel diode 6 in the opposite direction until the accumulated carriers in the flywheel diode 6 are completely transferred. This recovery current is a discharge current of the capacitor component of the flywheel diode 6.

When the accumulated carriers are completely transferred and the flywheel diode 6 becomes reverse biased and turns off, a back electromotive force e is generated at both ends of the excitation coil 4 due to the sudden cutoff of the recovery current, and the voltage level of F@ Although it is instantaneous, the voltage drops to a value close to the normal voltage level.

However, this instantaneous drop in the F terminal voltage is cut off by the delay circuit 21, which is a time constant circuit of resistors 22, 24 and capacitor 23 connected to the F terminal, and therefore the output of the comparator 8 also remains at the level. , the output transistor 7 can be kept in a cut-off state, and even if a short circuit accident involving inductance occurs as in the past, the output transistor 7 will not oscillate, and short circuit protection can be ensured.

In addition, in the case of a short circuit involving inductance, the voltage drop time of the F terminal is extremely small, so the delay circuit 2
Since the time constant of 1 can be set small, short-circuit protection can be achieved without significantly affecting the responsiveness due to the provision of the delay circuit 21.

Note that in this embodiment, the circuit configurations of the NAND circuit, AND circuit, and comparator circuit are not mentioned, but any circuit that configures such logic may be used.

〔Effect of the invention〕

As described above, in the present invention, in a power generation device with a voltage adjustment function, if the excitation coil itself is short-circuited for some reason and an inductive current flows through the inductance,
Or, in any of the above cases where the F terminal (for example, the collector terminal of the output transistor) is connected to the battery terminal due to incorrect wiring and a large current attempts to flow into the output transistor, for example, the output transistor is stably cut off without causing oscillation. Since the short-circuit protection circuit is provided with a delay circuit for this purpose, it is possible to prevent destruction of, for example, an output transistor serving as a switching means.

In addition, the resistance value and capacitance, which determine the time constant of the delay circuit, can be reduced, making it possible to downsize the voltage control device, including the delay circuit, and make it possible to use semiconductors, resulting in a more reliable voltage adjustment function. This has the excellent effect of providing a power generation device with high energy efficiency.

[Brief explanation of the drawing]

Fig. 1 is an overall circuit diagram of a vehicle generator including an embodiment of the device of the present invention, and Fig. 2 shows an oscillation phenomenon of an output transistor in the case of an inductive short circuit involving inductance, which occurs in a conventional device. It is a diagram. 1... AC generator, 2... Voltage adjustment circuit, 3...
Armature coil, 4... Excitation coil, 5... Rectifier,
7... Output transistor serving as a switching means, 8
．． 11... For example, comparator 8 and N forming a protection circuit
AND circuit 11, F...output terminal, 21...delay circuit, 26...battery.

Claims (1)

[Scope of Claims] An alternating current generator comprising an armature coil, an excitation coil, and a rectifier that rectifies the alternating current output from the armature coil, a switching means for intermittent excitation current of the excitation coil,
When a voltage higher than normal is applied to a battery charged by the DC output of the rectifier, a voltage adjustment circuit that controls the switching means according to the voltage of the armature coil or the battery, and an output terminal of the switching means. installed in a power generation device having a voltage regulation function, which is equipped with a protection circuit that forcibly shuts off the switching means, when the protection circuit malfunctions between the output terminal of the switching means and the protection circuit; A power generation device with a voltage adjustment function characterized by being equipped with a delay circuit that prevents.