Experimental Verification of On-line High
Efficiency Control for a Weaving Machine
Ryo Tateno
Nagaoka University of Technology
Niigata, Japan
tryo@stn.nagaoka.ac.jp

Jun-ichi Itoh
Nagaoka University of Technology
Niigata, Japan
itoh@vos.nagaokaut.ac.jp

Abstract-This paper demonstrates an on-line control based on
the speed sensor-less vector control for a weaving machine. The
system can achieve high efficiency because the exiting current
can be obtained in corresponds to the load torque in realtime.
The proposed on-line control is analyzed by simulation andverified experimentally. The maximum efficiency is increased by
4.4% in comparison to the the direct power grid connection.

Noboru Saitoh
HOKUETU DENKEN Co.,LtdNiigata, Japan
noboru-saitoh@post.hdnet.co.jp

the copper loss of the motor. The effectiveness of thesecontrol methods are validated by the simulation results andthe experimental results.
II.

CHARACTERISTIC OF WEAVING MACHINE

A.System configuration
Fig. 1 shows the system configuration of the weavingmachine, which is driven by the inverter. The induction motor
and the weaving machine are connected to the pulley. So, theI.
INTRODUCTION
weaving machine becomes the conveyed power of theinduction motor due to the V-belt connection. The ratio of theWeaving machines are generally driven by induction
motors because of the preferable low cost structure. Generally, pulley between the induction motor and the waving machine
the induction motor is connected directly to the power grid so = 81:186 in this test case. The rated speed of the inductionthat high speed acceleration could be achieved. However, motor is 1415 r/min, and the rated speed of the weaving
there is a problem with the large rush current from the power machine is 653 r/min based on the pulley ratio and the rated
grid and causing the efficiency reduced depends on load speed of the induction motor.
The weaving machine has a speed sensor on the load side.
conditions. Due to the direct connection from the power grid,
there is no controller involves for the system. Therefore the Therefore, the speed detection includes the slip of the belt
implementation of an inverter into this system is introduced. from the pulley. As a result, the control performance becomes
In addition, the motor control uses both the vector control worse because the slip of the induction motor is not adjusted
method and the high efficiency control method to control the properly to the slip of the belt. Overall, the efficiency of theflux in according with the load torque [1]-[2].
weaving machine is further reduced.
However, the load of the weaving machine changes rapidly
B. Load characteristics of the weaving machine
because of a cam is connecting in between the weaving
Fig. 2 shows the load characteristic of the weaving machine.
machine and the induction motor. Therefore, a variable load
Theload of the weaving machine changes rapidly because ofoccurs within a short cycle in according to the motor rotationacam
is connecting between the weaving machine and thefrequency. Also, controlling the magnetic flux under ainduction
motor. Therefore, a variable load occurs within avariable load condition will further increase the copper loss
shortcyclein according to the motor rotation frequency. On
because the exciting current is changing rapidly.
theotherhand,the maximum load torque is 1.5 times of theIn this paper, since the load of the weaving machine
rated
motortorque.
In addition, the recovery torque is applied
depends on the cyclic characteristic, high efficiency control
method using average load torque is proposed [3]. The to the induction motor at approximately 50% of the rated
average high efficiency control method is examined and motor torque. Also, the load torque changes at around 10 Hz
because of the cam moves twice each time the pulley moves
analyzed by simulation and experimentally.
However, the load characteristic of the induction motor once.
first must be known in order to control the average flux by theIII.
CONTROL METHOD
average load torque. Therefore, the real load characteristic of
the induction motor must be measured. Additionally, lots of A. Average high efficiency control method
The high efficiency control method adjusts the magnetic
adjustments are very difficult because the pattern of the load
torque is difference by the kind of thread.
flux in according to the load torque. Then the exciting current
In this paper, two types of on-line control methods also are is reduced in the light load condition. As a result, the copper
proposed to control the exciting current. The first one is loss and the iron loss can be reduced in the light load region.
called “continuous estimation method”, which can control the Therefore, the exciting current is controlled in order toexciting current in term of on-line in addition to a variable change the magnetic flux depends on the load torque.
load. The second one is called “copper loss comparison However, if the load torque is varied faster than the timemethod”, which can decide the exciting current by calculating constant of the magnetic flux in secondary side of theinduction motor, then the magnetic flux changes rapidly inaccording to the load torque. In that case, the exciting current
will increase drastically in the high efficiency control.. Due tothe reason, the exciting current changes significantly because
the secondary magnetic flux is changed within a fast period.
As a result, the copper loss increases because of the root
mean square (RMS) value of the exciting current is increased.
Nevertheless, the load of the weaving machine depends onthe cyclic characteristic. If the magnetic flux is controlled at
an average value, then the variable of the magnetic flux andthe exciting current becomes small. As a result, the copper
loss can reduce. The magnetic flux declares at the minimum
loss, is given by
4Fig. 1. System diagram of the weaving machine using
the inverter.

R1  R2
TL2 ..................................................... (1),R1  Rm

where, R1 is the primary resistance, R2 is the secondary
resistance, Lm is the exciting inductance, T is the load torqueand Rc is the iron resistance, L2 is the secondary leakage
inductance. Furthermore, the average torque is given from theload characteristic. Then, the exciting current is given byI d _ min  4

R1  R2
R1  Rm

Fig. 2. Load characteristic of a weaving machine.

T............................................... (2).
Lm

Then, the average torque T is obtained as 0.54 p.u. The
exciting current can be calculated as 90% of the rated valueby (2) and T=0.54pu.
B. Speed sensorless vector control methodFig. 3 shows the speed estimation block diagram for themotor [4]-[5]. This method estimates the motor speed by thecounter electromotive force. First, the flux axis angularvelocity 1 is calculated by the counter electromotive force
and the magnetic flux on the d-axis. Next, the motor speed isestimated to subtract the slip angular velocity s from the flux
axis angular velocity.
Fig. 4 shows the vectors on the rotating frame  are therotation angle of the motor control frame, where * is therotation angle of the controller frame to adjust the motor
control frame equals to the controller axis, 1 is the angularfrequency of * and the primary angular frequency of thevector control method and 1 is the sum of the rotation
angular velocity r and the slip angular frequency s,. e is thecounter electromotive force, and 2 is the secondary magneticflux.
The vector control method assigns the secondary magnetic
flux into the d-axis, i.e. the vector control method assigns thecounter electromotive force into the q-axis. When thecontroller frame corresponds to the motor control frame, theq-axis component of the counter electromotive force becomeszero. In other words, if the q-axis component becomes zeroby controlling , then the controller axis is corresponded tothe motor control frame. This is because the angler frequency
1 is obtained by the integral , r can be estimated.
However, the frame position error occurs between motor
control frame (d-q) and controller frame (d’-q’).
In Fig. 4, if the controller frame is faster than the motor
control frame, then  will be subtracted into eq to compensateFig. 3. Block diagram of a speed sensorless vectorcontrol.

Fig. 4. Relationships among the controller frame andmotor control frame in the sensorless vector control.
the frame position error. Additionally, if the controller frame
is slower than the motor control frame, then  will be added
into the eq to compensate the control frame error. Theequations (3) and (4) show d-axis and-q axis components ofthe counter electromotive force which is observed on thecontrol frame. In addition, the compensated value of 1 isshown by (5), where, Kpem is the compensation gain of theaxis error, 2n is the rated secondary magnetic flux.
d 
ed  vd   R1  L
id  1 L iq ............................ (3)
dt 

d 

eq  vq   R1  L
iq  1 L id ............................. (4)
dt 

 eq

1  sgn( eq )  2 d

 K pem2 d * ed  ................................. (5)2 n 


C. On-line high efficiency control method
First, the load torque is estimated by the slip angularfrequency of the induction motor s. From that, the rated slip
angular frequency sn can be estimated by the parameter ofthe induction motor. Then, the estimated load torque isintegrated. Then, the average load torque based on the on–line control is estimated by
T_ all  t2t1

T_ average sdt
 sn
T_ all(t 2  t 1 )......................................................... (6)where, T_all is the integral value of the instantaneous value ofthe load torque, s is the slip angular frequency of theinduction motor, sn is the rated angular frequency, andT_average is the average load torque.
Fig. 5 shows the block diagram of the continuous
estimation method. This method controls the exciting current
in term of on-line. The variable load is estimated by theaverage load torque and (2) at every cycle. The average highefficiency control method calculates the exciting current
based on the characteristic of the load, which is shown in Fig.
2. Therefore, if the load pattern changes or if the R1 and R2change by the temperature of the induction motor, the error
occurs on the exciting current. Thereby, the continuous
estimation method controls the exciting current at every cycleof the variable load. Therefore, even if the driving condition
is change every cycle, the exciting current can be controlled
at the optimum value every time in according to the load
torque.
Fig. 6 shows the block diagram of the copper loss
comparison method. The copper loss comparison method
controls the exciting current similar to the continuous
estimation method in a constant time t_limit. From there, at thesame time as calculating the exciting current, the copper loss
Ploss is estimated by the detected motor current. In addition,
the copper loss Ploss_min is calculated bycontrol method, the rated speed is 1500 r/min. Table 1 shows
the motor parameters.
A. Operation waveforms
Fig. 7 shows the continuous estimation method operation.
The changing of the exciting current is checked at every 10Hz.
Fig. 8 shows the operation of the copper loss comparison
method. The figure shows that the minimum copper loss has
found within 2.55s. At 2.55s, the optimum exciting current Id
is checked Id=0.62pu. At that, Id is 95% of the rerated exciting
current. Id is 90% over then the rated exciting current because
the exciting current is changed not only one cycle but isapproximately 20 cycles of a variable load.
B. Calculation copper loss
Fig. 9 shows the result of the copper loss based on the direct
power grid connection, the average high efficiency control
method, the continuous estimation method and the copper
loss comparison method. The copper loss is reduced byapproximately 12% comparing the direct power gridconnection, to the on-line control methods. The copper loss isFig. 5. Continuation method block diagram.

Fig. 6. Copper loss comparison method.
Table 1. Motor parameters.

Ploss  ( I d  I q )  R1  I q 2  R2 ................................... (7),22where, Ploss is the copper loss.
Then, the exciting current where the copper loss was aminimum value in the t_limit is decided. Therefore, the copper
loss comparison method is different from the continuousestimation method. Additionally, the exciting current which
the copper loss is minimum value can be controlled.
In order to reduce the complexity, the iron loss is neglectedin this analysis because an influence of the iron loss is smaller
than an influence of the copper loss.
IV.

SIMULATION RESULTS

These proposed methods are verified by simulation using
PSIM7.1.2 (Power SIM Inc.). Simulation conditions arefollows, DC voltage is 560V, using the speed sensorlessFig. 7. Simulation results using the continuation method.

reduced based on on-line control method because the exciting
current can be controlled to the optimum value at real time.
V.

EXPERIMENTAL RESULTS

Effects of the proposed methods were tested by weavingmachine (HANGZHOU YINCHUN MACHINE JW-832C).
The experimental conditions are; DC voltage is 560V , uses
the speed sensorless control method, the rated speed is 1500
r/min. The motor parameters are same as the simulation asshown in Table 1.
A. Inverter efficiency
Fig. 10 shows the inverter efficiency based on the averagehigh efficiency control method, the continuous estimation
method and the copper loss comparison method. The inverter
efficiency is 96.3 % based on the continuous estimation
method as shown in Fig. 10. As a result, the loss is reduced
by approximately 10 % than the average high efficiency
control method.
The inverter efficiency changes because the current ischanged by the efficiency of the induction motor in theconverter. The continuous estimation method could obtain ahigher efficiency on the induction motor because the exciting
current is controlled in according to the load torque.

Fig. 8. Simulation results using the copper loss
comparison method.

Fig. 9 Copper loss comparison based on simulation
analysis.

B. Driving efficiency of the weaving machine
Fig. 11 shows the driving efficiency of the weaving
machine based on the direct power grid connection, theaverage high efficiency control method, the continuousestimation method and the copper loss comparison method.
The driving efficiency of the weaving machine was calculatedby the number of weft thread for the used power. Fig. 11
shows the continuous estimation method could achieve themaximum efficiency. The driving efficiency of the weaving
machine is improved by approximately 4.4 % than then thedirect power grid connection. In addition, the driving
efficiency of the weaving machine is approximately 0.3 %higher than the copper loss comparison method. The driving
efficiency of the waving machine is given the maximum
efficiency on the continuous estimation method because of
the exciting current can be always controlled in according tothe load torque.
VI.

Fig. 10. Inverter efficiency.

CONCLUSIONSIn this paper, the effectiveness of the proposed methods
were validated by the simulation and the experimentally. The
driving efficiency of the weaving machine was improved
because the exciting current is controlled in according to theload torque.
Future work involves the high speed accelerating method
and the application of the “hill climbing method” todetermine the minimum loss.

Fig. 11. Driving efficiency of weaving machine.
[3]

REFERENCES[1][2]

J.Itoh, H.Tajima, H.Ohsawa, “Induction Motor Drive System using Vconnection” T, IEE Japan, vol.123-D, No.3 (2003) (in Japanese).
Novo Pingnone S. P. A. “Driving Control Device of Weaving machine”
Laid open disclosure public patent bulletin(1993) (in Japan).

[4]
[5]

R.Tateno, J Itho, N.Saitoh, “Consideration Optimum Excitation Currentof Control of Inverter for a Weaving Machine”, in JIASC, I-473,
August 2010(In Japanese).
H.Tajima,Y.Matsumoto,H,Umida：”Speed Sensorless Vector Control
Method for an Industrial Drive System”Trans.IEEJ,Vol.116-D,No.11,’96
H.Umida, “The Basic Theory and the System Configuration of Vector
Control for Induction Machine”, T, IEE Japan, vol.123-D, No.3 (2003)(in Japanese).