Electricity: single generator systems – Automatic control of generator or driving means – Voltage of generator or circuit supplied
Reexamination Certificate
2000-02-14
2001-09-25
Ponomarenko, Nicholas (Department: 2834)
Electricity: single generator systems
Automatic control of generator or driving means
Voltage of generator or circuit supplied
C322S037000
Reexamination Certificate
active
06294899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control system of an alternating current generator for charging battery for controlling output voltage of that generator so that the voltage becomes to a voltage of a predetermine valve.
2. Description of the Prior Art
FIG. 4
shows a circuit of a control system of a conventional alternating current generator, and this shows a circuit in the case where it is employed in an alternating current generator being used for vehicle.
1
is an alternating current generator comprising three generator coils
101
and a magnetic field coil
102
.
2
is a full wave rectifier for rectifying output of the generator coils
101
and consisting of six diodes and having an output terminal
201
on the positive electrode side and a grounded output terminal
202
on the negative electrode side.
3
is a voltage control circuit being connected in series to the negative electrode side of the magnetic field coil
102
and this control circuit consists of a constant voltage power supply A, which consists of a resistance
301
for limiting electric current and a zener diode
302
for fixing voltage to a fixed one, potential dividing resisters
303
and
304
for detection of the output voltage of the generator
1
, a comparator
305
for comparing the detection voltages appearing through the potential dividing resistances
303
and
304
with the predetermined voltage Ref
1
, a power transistor
308
serving as a first power transistor, resistance
306
for supplying base current and a suppression diode
307
for absorbing surge voltage of the magnetic field coil.
4
is a battery whose negative side is grounded and whose positive side is connected to one end of a key switch
5
, to one end of the resistance
303
, to cathode of the diode
307
, to positive electrode side of the magnetic field coil
102
and to the output terminal
201
on the positive electrode side of the full wave rectifier
2
.
The predetermined voltage Ref
1
serving as a first predetermined value is supplied by dividing the output voltage of the constant voltage power supply A by means of unshown resistors, and in this case, and this divided voltage is set to about 14.5V as a threshold voltage for switching output voltage of the comparator
305
to “High” or “low”.
Detailed description on the constitution of the voltage control circuit
3
will be given subsequently. One end of the resistance
301
is connected to another end of the key switch
5
and to one end of the resistance
306
, and another end of the resistance
301
is connected to the cathode of the zener diode
302
and becomes to a feeding terminal of the constant voltage power supply A. Anode of the zener diode
302
is grounded. One end of the resistance
303
is connected to the positive electrode side of the battery
4
and its another end is connected to one end of the resistance
304
whose another end is grounded. A portion between the resistances
303
and
304
is connected to the negative input electrode of the comparator
305
. The predetermined voltage Ref
1
is supplied to the positive electrode side of the comparator
305
. The output terminal of the comparator
305
is connected to the another end of the resistance
306
and to the base of the power transistor
308
. Collector of the power transistor
308
is connected to the anode of the suppression diode
307
and to the side of the negative electrode of the magnetic field coil
102
and its emitter is grounded.
Subsequently, operation of the control circuit will be described. When a driver turns on the key switch
5
, a predetermined voltage is generated at the constant voltage power supply A by the electric current flowing through the resistance
301
and the zener diode
302
resulting in generation of a predetermined voltage at the constant voltage power supply A, and thus supplied predetermined voltage Ref
1
is input to the comparator
305
. At this time, because the generator
1
has not yet generated electricity, the output voltage of the battery
4
detected through the resistances
303
and
304
is lower than the predetermined constant voltage Ref
1
. Accordingly, output of the comparator
305
becomes “High” and in turn the transistor
308
is turned on and thus the magnetic field current flows trough the magnetic field coil
102
caused by turning on the transistor
308
.
By turning on the starting switch (unshown) thereafter, the engine is started and the alternating current generator
1
starts the alternating current generation. Output of alternating current generator
1
is rectified by the full wave rectifier
2
and the battery is charged.
At this time, when the output voltage of the alternating current generator
1
is lower than the predetermined voltage Ref
1
, this lower voltage is detected through resisters
303
and
304
for potential division, and the output of comparator
305
becomes “High” and the power transistor
308
becomes conductive and thus the current flowing through the magnetic field coil
102
is increased resulting in rising up of the output voltage of the generator
1
. When this output voltage exceeds the predetermined voltage Ref
1
, operation contrary to the aforementioned is carried on. In other words, output of the comparator
305
becomes “Low” and the power transistor
308
is shut off and this causes reduction of the magnetic field current of the magnetic field coil
102
and in turn the output voltage of the alternating current generator
1
decreases.
After that, by repetition of the above mentioned operations, the control circuit controls the output voltage of the alternating current generator
1
so that it maintains a predetermined value. In this case, the magnetic field current to the magnetic field coil
102
is controlled by turning on and turning off it so as to enabling the battery
4
to maintain its voltage to the predetermined voltage Ref
1
of 14.5V.
However, in the aforementioned conventional system, suppose should a trouble is developed such that the power transistor
308
is shorted or the negative side of the magnetic field coil
102
is grounded by an extraneous metal and the like, the voltage control circuit
3
is obliged to be bypassed and this makes the magnetic field current of the magnetic field coil
102
to be uncontrollable and as a consequence the maximum magnetic field current is to flow through the magnetic field coil
102
; in turn the output voltage of the alternating current generator
1
rises unusually to an over voltage and this over voltage inevitably destroys electric loads (unshown) on board the vehicle. Further, due to this over voltage, there was a possibility of destroying devices being necessary for vehicle running and thus the vehicle will be able to run no longer.
A control system with a function of displaying overvoltage of a battery
4
disclosed in the Japanese Patent Publication No. 2579812 is known; but this system has no ability of recovery from the overvoltage at the time when the battery
4
becomes to be over voltage and further has no ability of continuing the battery charging and electricity supply to the electric loads because of stoppage of the generation of electricity.
The present invention has been made in order to solve the forgoing problems, and the object of the invention is to control, even when a malfunction is developed on the negative electrode side of the magnetic field coil, the output voltage of the alternating current generator is controlled so that the operation of charging battery and that of supplying electricity to the electric loads can be continued.
SUMMARY OF THE INVENTIONS
According to the invention as recited in claim
1
, an overvoltage protection circuit for controlling output voltage of the alternating current generator is provided on the positive electrode side of the magnetic field coil.
According the invention as recited in claim
2
, the voltage control circuit comprises a first power transistor being connected in series with the magnetic field coil on the negative electrode
Iwatani Shiro
Tokugawa Kazuya
Mitsubishi Denki & Kabushiki Kaisha
Ponomarenko Nicholas
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Control system for an alternating current generator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control system for an alternating current generator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control system for an alternating current generator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473297