Kubota J106-AUS Workshop Manual Download

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M-3

GENERATOR

J SERIES, WSM

The block diagram of J Series A.V.R.’s is shown below. The A.V.R. consists basically of the components detector

(12) through transistor (4). To run it for practical use, the other components separate excitation unit (14) through
battery (16) are combined.

W1017260

(1) Detector

The detector (12) monitors the generator’s output voltage. The generator’s detection coil (13) is connected to this

component.

(2) Controller

The controller (11) is designed to compare the voltage picked up by the detector (12) with the preset reference

voltage and to give a transistor

and

OFF

signal to the drive circuit (5). When the output voltage rises too high, it

is made to drop; if it drops too low, it is made to rise.

(3) Photocoupler

The photocoupler (6) sends a control signal to the drive circuit (5). It is internally composed of light emitter (9) and

light receiver (7) to send and receive light signals (8). Because of such wireless transmission, the light emitter circuit
and the light receiver circuit can be electrically insulated from each other (10). On the A.V.R., the drive circuit (5) with
the exciter coil (1) connected and the controller (11) with the detection coil (13) hooked up are insulated as different
blocks on the circuit board. (The printed patterns of these blocks may also be arranged at a physical distance away
from each other.) The photocoupler (6) itself is driven by the detection coil (13).

(4) Drive circuit

The drive circuit (5) is basically composed of multiple transistors. The drive signal being picked up by the

photocoupler’s light receiver is weak. To intensify this signal, the final-stage transistor (4) that switches on and off the
current to the rotor is activated. For comparison, let’s imagine a gearbox that gives a large torque from a small force.
While the engine is stopped or in the low rpm range - that is, the generator voltage is not yet established, the drive
circuit (5) behaves to keep the transistor (4) fully on. Relays behave the same way. The separate excitation unit (14)
to be connected to the drive circuit (5) works to provide for the turning on condition. When the key switch (15) is turned
on, the separate excitation unit (14) applies the battery voltage to the drive circuit (5), which in turn gets ready. In
“Controller (11)” we discussed “When the output voltage rises too high, it is made to drop; if it drops too low, it is made
to rise. “The higher the engine rpm becomes, the higher the generator’s output voltage rises. With the transistor (4)
fully on, the generator’s output voltage would be too high. To cope with this problem, the controller (11) serves to limit
the transistor’s (4) on-status to a lower range. In other words, the drive circuit (5) would not work if no signal would

(1) Exciter Coil
(2) Rectifier
(3) Rotor Coil
(4) Transistor

(5) Drive Circuit
(6) Photocoupler
(7) Light Receiver
(8) Light Signal

(9) Light Emitter

(10) Controller and drive

separately grounded

(11) Controller

(12) Detector

(13) Detection Coil
(14) Separate Excitation Unit
(15) Key Switch
(16) Battery

KiSC issued 10, 2016 A