The Clutch Control Strategy of EMCVT
in AC Power Generation System
Shenyang Institute of Technology, Shenyang, China
Xiumin Yang, Yangyang Zhao, Song Zhang, Lei Zhang
20/05/2017
1. Introduction
With the development of continuously variable
transmission ( CVT ) technology and the increased
strength research, the ability to transfer power of
CVT is continuously improved and the application
space also will be continuously expanded. This
paper tries to apply new-pattern EMCVT to the
frequency conversion control of the output micro
power grid interconnection in the alternator and its
corresponding clutch control strategies was studied.
2. The control requirements of EMCVT
clutch in the alternator
When the micro grid from the normal operation
turning to the isolated island operation on account of
some reason resulting in splitting of grid, or the inverse
operation, this important point is how to control the
micro grid switch smoothly and keep the system stable.
So to make sure the control strategy of the CVT
transmission of external clutch, by controlling the
generator input shaft angle, the output voltage phase
consistency with grid systems is guaranteed, avoiding
the impact in interconnection.
3. The establishment of the clutch model
3.1 Dynamic model of the clutch
By the above model, the
dynamics equations of
driving disc and driven disc
of clutch are as shown in
following formulas.
Te  Tcl  J ee  Bee
Tcl  Tl  J p p  B p p
the dynamics equation of the transmission system is as
shown in following formula.
Te 
Tl

(
Jp

 J e ) p  Be p
3
The establishment of the clutch model
3.2 Control objectives and control parameters
(1) Shock degree j.
d 2 p
rw
rw d (Tcl )
j


2
i0it dt
i0it J p dt
L
.
(2) Friction loss
t1
t2
0
t1
L  L1  L2   Tcle dt   Tcl (e   p )dt
4. The fuzzy controller design of EMCVT
4.1 Control strategy of clutch engaging fuzzy
load
current
A/D
fuzzy
quantization
fuzzy
reasoning
input shaft speed of clutch
defuzzification
PWM
signal
clutch
motor
clutch
speed sensor
4.2 Selection of input and output variable in fuzzy
control
According to the control requirements, choose power grid load current
i, source machine speed ne and EMCVT disc position variation as the
inputs and clutch motor control signal as the output.
4. The fuzzy controller design of EMCVT
4.3 Fuzzification of the input variables
In the research, the prime mover of alternator source of micro-grid uses
a gasoline engine. The fuzzy language of input and output can be described
as {very small, small, smaller, medium, bigger, big, very big}, expressed
as {VS, S, LS, M, LB, B, VB}. The PWM control signal u of clutch motor can
be described as {very low, low, lower, medium, higher, high, very high},
expressed as {VS, S, LS, M, LB, B,VB}. The set corresponds to the 13
quantitative levels[4]. The membership degree between fuzzy subset and
quantitative level is determined by experience.
4. The fuzzy controller design of EMCVT
4.4 Establishment of the fuzzy control table
The purpose of establishing the fuzzy control
table is to find out a proper accurate value
representing the fuzzy quantity.
n
n
j 1
j 1
z0  [  x ( x j )  x j ]/   x ( x j )
4.5 Solve the fuzzy process
The control voltage signal of clutch motor can be
calculate by the following formula.
u  kz0
start
load i and ne
scaling factor initialization
and loading the control table
fuzzification
query control table
defuzzification
return control results
end
5. Experimental Research
The CVT test table was built using the modified FC2000 dynamic test
system. The control test of external clutch in EMCVT was finished. The
motivation of EMCVT derived from the gasoline engine. The output shaft of
EMCVT was connected with the dynamometer and throttle actuator
achieved an automatic control by controlling a DC motor. In the
experiments, a constant output shaft speed of EMCVT was regard as a
control target. By adjusting the change rate of engine throttle and
dynamometer load, conversion control effect between power system
interconnection of micro grid and an island operation mode was simulated
while control effect of both connection and disconnection of EMCVT was
observed.
5. Experimental Research
5. Experimental Research
The transient time of connection of clutch can be controlled within
two seconds and the control accuracy of output speed of EMCVT can be
controlled within four percent in the experiment.
The theory was validated on the hardware platform. Because
common dc motors were applied to clutch control and throttle control and
mobility of mechanical transmission mechanism was not the most optimal,
the process time of clutch engagement was longer in the experiment and
the control precision and stability of output speed for EMCVT were lower. If
servo motors and scroll-type mechanical transmission mechanisms were
applied on the system, the control precision and stability would be improve
dramatically.
6. Conclusion
(1) When the EMCVT is applied into the alternating-current generator,
electric power transmission, non-harmonic transformer and high efficiency,
can have a function of constant frequency control.
(2) Experimental Research can draw a conclusion that on the
running processing of alternating-current generator system, the external
clutch of EMCVT can ensure the output power in or out stablely.
(3)The fussy control strategy of external clutch of EMCVT and the
clutch model were present, which achieves the satisfied control for external
clutch of EMCVT.
Thank you for your attention.
This research was supported by the science
and technology funds from Liaoning Education
Department (serial number: L2015375)