Yamaha EF4500iSE Theory & Diagnostics Manual page 7

EF3000iSE new model guide
Power Generation
Stage 1 The rectifier circuit converts three- phase
AC into DC and it maintains stable DC
voltage using a constant voltage circuit.
Stage 2 The constant voltage DC current is
stored in a condenser.
Stage 3 The PWM, Pulse Width Modulator,
inverter circuit generates a stable sine
wave AC current.
Stage 4 The filter circuit further smoothens the
sine wave of the AC current and reduces
electrical noise.
Protective functions:
Overload (over current) protection device
■
The control unit has similar function to conven-
tional NFB (no fuse breaker). When the output
current exceeds a specified amperage, AC out-
put is interrupted.
Overheat protection
■
When the internal temperature of the control
unit becomes abnormally high, AC output is
EF3000iSE new model guide
interrupted.
Over-voltage protection device
■
AC output is interrupted when excessive current
flows into the generator from an outside power
source causing voltage to rise in the control
unit.
Other Functions of the Control Unit:
Throttle Control – Control unit commands the throttle
motor to adjust engine speed automatically in accor-
dance with the amount of the electrical consump-
tion.
Electronic Governor
An electronic governor takes the place of a conven-
tional mechanical governor, and opens and closes
the carburetor throttle valve electrically.
Components and functions:
Inverter control unit
■
The control unit constantly monitors AC output
and adjusts the throttle motor to produce the
necessary engine speed.
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Throttle motor (stepping motor)
■
The throttle motor receives pulses from the con-
trol unit and opens or closes the throttle valve
approximately 0.7° per pulse.
STEPPING MOTOR Stepping motor
Functions of the Electronic Governor
The inverter control unit is preprogrammed with the
ideal engine speed settings in relation to electrical
current output. It uses these settings as a cross-ref-
erence with the detected current output to control
the throttle motor (and consequently the throttle
3/14/03 4:20 PM
valve) to adjust engine speed to an optimum level.
Therefore, the engine speed will always be at the
appropriate level according to the load on the sys-
tem.
With an inverter generator, even if the engine
speed changes it has no effect on the output
frequency .
The electronic governor system is maintenance-free
as it cannot be adjusted externally.
THROTTLE
CONTROL
1-3
Generator Information and Theory
Page 4
ENGINE rpm
DETECTOR