Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Reexamination Certificate
2002-01-08
2003-11-11
Leykin, Rita (Department: 2837)
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
Reexamination Certificate
active
06646409
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for controlling the rotation speed of a motor, and more particularly, to an apparatus for controlling the rotation speed of a motor, which is capable of detecting the voltage and the current that are applied to the motor and controlling the rotation speed and torque.
2. Description of the Background Art
In general, information on the speed of the motor or flux information is essential to controlling instantaneous torque in an apparatus for controlling the speed of a motor, in particular, a synchronous reluctance motor (SYNRM). That is, a sensor of information on the rotation speed of the motor and a flux sensor such as a hall sensor, a resolver, and a pulse encoder are necessary. However, it is difficult to install the sensors and the sensors are sensitive to installation conditions. Therefore, the sensors are vulnerable to noise. Also, the sensors are expensive. According to a method for controlling a vector without a speed sensor, speed and torque are controlled without correcting speed errors with respect to change in the rotor resistance of the motor.
FIG. 1
shows the respective axes of a common SYNRM.
As shown in
FIG. 1
, in the stator side three-phase axes (U, V, and W axes), a phase difference between the U axis and the V axis is 120°. The phase difference between the V axis and the W axis is 120°. The phase difference between the W axis and the U axis is 120°. The &agr; axis and the &bgr; axis are in a stationary coordinate system. The d axis and the q axis are synchronous axes. Also, the flux axis &thgr;
e
of a rotor is an angle showing the phase difference between the U axis and the d axis. The conventional technology will now be described with reference to FIG.
2
.
FIG. 2
is a block diagram showing the structure of the apparatus for controlling the rotation speed of the SYNRM according to the conventional technology.
As shown in
FIG. 2
, the apparatus for controlling the rotation speed of the SYNRM according to the conventional technology includes a first proportional integration (PI) controller
12
for receiving an error value obtained by comparing reference speed w*
m
with estimated speed w*
m
and outputting reference torque component current i*
q
for compensating for the error value, a second PI controller
15
for receiving an error value obtained by comparing reference magnetic flux component current i*
d
with real magnetic flux component current i*
d
and outputting the reference magnetic flux component current for compensating for the error value as a reference magnetic flux component voltage v*
d
, a third PI controller
16
for receiving an error value obtained by comparing the reference torque component current i*
q
with real torque component current i*
q
and outputting the reference torque component current for compensating for the error value as a reference torque component voltage v*
q
, a synchronous/stationary coordinate converter
17
for changing the reference magnetic flux component voltage v*
d
and the reference torque component voltage v*
q
from a synchronous coordinate system to a stationary coordinate system according to sine and cosine values sin &thgr; and cos &thgr; of the real magnetic flux angle &thgr; and outputting the reference voltages v*
&agr;
and v*
&bgr;
in the stationary coordinate system, a three phase voltage generator
18
for converting the reference voltage v*
&agr;
and v*
&bgr;
in the stationary coordinate system into three phase voltages v
as
, v
bs
, and v
cs
and outputting the three phase voltages v
as
, v
bs
, and v
cs
, an inverter
19
for applying the three phase voltages v
as
, v
bs
, and v
cs
generated by the three phase voltage generator
18
to the SYNRM, a rotor position detector
22
for detecting the position of the rotor of the SYNRM, a speed operator
24
for outputting the estimated speed w
m
from the position of the detected rotor, a signal generator
23
for generating the sine and cosine values sin &thgr; and cos &thgr; of the real magnetic flux angle &thgr; from the position of the detected rotor and outputting the sine and cosine values sin &thgr; and cos &thgr;, a two phase current generator
20
for converting the three phase current detected when the SYNRM rotates into two phase current i
&agr;
and i
&bgr;
and outputting the two phase current i
&agr;
and i
&bgr;
and a stationary/synchronous coordinate converter
21
for converting the two phase current i
&agr;
and i
&bgr;
into the stationary coordinate system and outputting the real torque component current i
q
and the real magnetic flux component current i
d
. The operation of the apparatus for controlling the rotation speed of the SYNRM according to the conventional technology will now be described.
A first subtracter
11
obtains the error value by comparing reference speed w*
e
with the estimated speed w
e
detected by the rotor position detector
22
during the rotation of the SYNRM and outputs the error value to the first PI controller
12
.
A second subtracter
14
compares the reference magnetic flux component current i*
d
with the real magnetic flux component current i
d
output from the stationary/synchronous coordinate converter
21
and outputs the obtained error value to the second PI controller
15
.
The second PI controller
15
outputs the reference magnetic flux component voltage v*
d
of the reference magnetic flux component current i*
d
for compensating for the error value obtained by the second subtracter
14
to the synchronous/stationary coordinate converter
17
. At this time, a third subtracter
13
compares the reference torque component current i*
q
output from the first PI controller
12
with the real torque component current i
q
output from the stationary/synchronous coordinate converter
21
.
The third PI controller
16
outputs the reference torque component voltage v*
q
of the reference torque component current i*
q
for compensating for the error value obtained by the third subtracter
13
to the synchronous/stationary coordinate converter
17
. At this time, the reference magnetic flux component voltage v*
d
output from the second PI controller
15
is output to the synchronous/stationary coordinate converter
17
.
The synchronous/stationary coordinate converter
17
receives the reference magnetic flux component voltage v*
d
, the reference torque component voltage v*
q
, and the sine and cosine values sin &thgr; and cos &thgr; of the real magnetic flux angle &thgr; output from the signal generator
23
, generates the reference voltages v*
&agr;
and v*
&bgr;
in the stationary coordinate system, and outputs the reference voltages v*
60
and v*
&bgr;
in the stationary coordinate system to the three phase voltage generator
18
.
The three phase voltage generator
18
converts the reference voltages v*
&agr;
and v*
&bgr;
in the stationary coordinate system into the three phase voltages v
as
, v
bs
, and v
cs
in the stationary coordinate system and outputs the three phase voltages v
as
, vb
bs
, and v
cs
in the stationary coordinate system to the inverter
19
.
The inverter
19
applies the three phase voltages v
as
, v
bs
, and v
cs
output from the three phase voltage generator
18
to the SYNRM. At this time, the rotor position detector
22
for detecting the position of the rotor of the SYNRM outputs the estimated speed w
m
to the first subtracter
11
through the speed operator
24
.
The two phase current generator
20
receives the three phase current detected during the rotation of the SYNRM, generates the current i
&agr;
and i
&bgr;
in the stationary coordinate system, and outputs the current i
&agr;
and i
&bgr;
in the stationary coordinate system to the stationary/synchronous coordinate converter
21
.
FIG. 3
is a vector diagram showing the voltage of the d axis of the to SYNRM and the voltage of the q axis of the SYNRM in a steady state.
As shown in
FIG. 3
, the equations of the voltages of the SYNRM are expressed by the d axis and the q axis that are the synchro
Cheong Dal Ho
Lee Kyung Hoon
Oh Jae Yoon
Won June Hee
Fleshner & Kim LLP
Leykin Rita
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