Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Reexamination Certificate
2001-09-06
2003-11-18
Donels, Jeffrey (Department: 2837)
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
Reexamination Certificate
active
06650083
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a synchronous reluctance motor (SynRM), and more particularly, to a speed control apparatus of a synchronous reluctance motor.
2. Description of the Background Art
FIG. 1
is a sectional view of a general synchronous reluctance motor (SynRM), in which reference numeral
100
denotes a stator,
101
denotes slots of the stator
100
, and
200
denotes a rotor.
FIG. 2
is a sectional view of the rotor of
FIG. 1
, in which reference numeral
201
denotes grooves which differentiate magnetic flux passing ‘d’ axis and ‘q’ axis,
202
denotes a pinhole with silicon ferrite filled therein.
A rotational speed of the synchronous reluctance motor with such a structure is controlled by a synchronous reluctance motor controlling apparatus which detects a position of the rotor.
FIG. 3
shows the construction of the speed controlling apparatus of the synchronous reluctance motor in accordance with a conventional art.
As shown in
FIG. 3
, a rectifier
320
receiving an AC power
310
and rectifying it to a DC power, an inverter
330
for converting the DC power to three phase currents and driving the synchronous reluctance motor
340
, a controlling unit
350
controlling the inverter
330
, and a detecting unit
360
detecting a rotational speed or the synchronous reluctance motor
340
.
The detecting unit
360
includes a current detector
361
detecting two phase currents among the three phase currents flowing to the synchronous reluctance motor
340
, a rotor position detector
363
detecting angular velocity of the rotor of the synchronous reluctance motor
340
, a magnetic flux angle operating unit
362
receiving the angular velocity (&ohgr;
r
) of the rotor outputted from the rotor position detector
363
and computing a magnetic flux angle (&thgr;), and a coordinate converter
364
receiving magnetic flux angle (&thgr;) and the detected two phase currents and generating a magnetic flux current value (i
ds
) of the rotor and a current value i
qs
of torque.
The controlling unit
350
includes a comparator
358
receiving the angular velocity value (&ohgr;
r
) and a velocity command value (&ohgr;
r
*) from the rotor position detector
363
and computing a difference velocity command value, a speed controller
356
receiving the different velocity command value and generating a current command value for torque (l
qs
*), a comparator
354
receiving the current command value for torque (l
qs
*) and a current value for torque (i
qs
) outputted from the coordinate converter
364
of the detecting unit
360
and generating a difference current command value for torque, a magnetic flux command generator
357
generating a current command value for magnetic flux (i
ds
*) to differentiate a positive torque region and a positive output region according to the rotor angular velocity value (&ohgr;
r
) outputted from the rotor position detector
363
of the detecting unit
360
, a comparator
355
receiving the current command value (i
ds
*) and the current value for magnetic flux (i
ds
) outputted from the coordinate converter
364
of the detecting unit
360
and generating a difference current command value for magnetic flux, a magnetic flux controller
353
receiving the difference current command value for magnetic flux and generating a magnetic flux command value; a current controller
352
receiving the command value for magnetic flux and the difference current command value for torque and generating a voltage command value for torque (V
qs
*) and a voltage command value for magnetic flux (V
ds
*), and a voltage generator
351
receiving the voltage command value for torque (V
qs
*), the voltage command value for magnetic flux (V
ds
*) and the magnetic flux angle (&thgr;), generating three phases voltage command values (V
as
, V
bs
, V
cs
) and outputting them to the inverter
330
.
The operation of the conventional speed control apparatus of synchronous reluctance motor constructed as described above will now be explained.
In order to control the rotation speed of the synchronous reluctance motor
340
according to the velocity command value (&ohgr;
r
*), when the velocity command value (&ohgr;
r
*) is inputted to the controller
350
, the comparator
358
of the controlling unit
350
compares the velocity command value (&ohgr;
r
*) and a rotor angular velocity value (&ohgr;
r
) outputted from the rotor position detector
363
and outputs a generated error to the speed controller
356
.
Then, the comparator
355
of the controlling unit
350
receives the angular velocity value (&ohgr;
r
), receives the current command value for magnetic flux (i
ds
*) generated from the magnetic flux command generator
357
and the current value for magnetic flux (i
ds
) outputted from the coordinate converter
364
, compares them to generate a difference current command value for magnetic flux and outputs it to the magnetic flux controller
353
.
The current controller
352
receives the difference current command value for torque and the magnetic flux command value outputted from the magnetic flux controller
353
, generates a voltage command value for torque (V
qs
*) and a voltage command value (V
ds
*) for magnetic flux and outputs them to the voltage generator
351
.
Then, the voltage generator
351
receives the voltage command value for torque (V
qs
*), the voltage command value for magnetic flux (V
ds
*) and the magnetic flux (&thgr;) outputted form the magnetic flux angle operating unit
362
of the detecting unit
360
, and outputs three phase voltage command values (V
as
, V
bs
, V
cs
) for switching ON/OFF of the inverter
330
to the inverter
330
.
Thus, the synchronous reluctance motor
340
is rotated by the three phase AC powers outputted from the inverter
330
.
The coordinate converter
364
of the detecting unit
360
converts an a-phase current (l
as
) and a b-phase current (i
bs
) detected from the current detector
361
which detects a current flowing from the inverter
330
to the synchronous reluctance motor
340
into a d-axis current or a current value for magnetic flux (i
ds
) and a q-axis current or a current value for torque (i
qs
).
The rotor position detector
363
uses an encoder or a hall sensor to detect a position of the rotor.
The conventional speed control apparatus of the synchronous reluctance motor, however, has the following problems.
That is, in order to control the rotation speed of the synchronous reluctance motor, an encoder or the hall sensor is to be used to detect a position of the rotor of the synchronous reluctance motor, which causes an increase of a cost of a product. Above all, the rotor position detector is not suitable to a compressor of a refrigerator, an air-conditioner or a heater.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a speed control apparatus of a synchronous reluctance motor that is capable of controlling a rotation speed of a synchronous reluctance motor.
Another object of the present invention is to provide a speed control apparatus that is capable of controlling a rotation speed of a synchronous reluctance motor by detecting a current and a voltage supplied to a synchronous reluctance motor.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided to a speed control apparatus of a synchronous reluctance motor including: a rectifier for receiving an AC power and rectifying it to a DC power; an inverter for receiving a DC power to an AC power and supplying it to a synchronous reluctance motor; a detecting unit for operating an induction voltage generated by detecting a current and a voltage supplied to the synchronous reluctance motor and the estimated induction voltage generated from the current, and generating an estimated angular velocity of the synchronous reluctance motor; and a controller for receiving the estimated angular velocity and the velocity command value inputted by a user and controlling the
Birch & Stewart Kolasch & Birch, LLP
Donels Jeffrey
LG Electronics Inc.
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