The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
An embodiment of the present invention will now be described in further detail. The position of the sensing magnet 27 with respect to the hall sensor 28, and thus the position of the rotor with respect to the stator, can be determined based on a correlation between a voltage and a flux, a correlation between a voltage and a current, and a correlation between a current and a D-axis of the rotor, as defined by Equations 1 and 2 below:
where E denotes a voltage, Φ denotes a flux, T denotes a torque, P denotes the number of poles, Ld and Lq denotes synchronous d-axis and q-axis inductances, respectively, Is denotes a current, and θi denotes a current angle between the D-axis of the rotor and a current.
The controller 29 may be implemented with an relatively inexpensive control IC 30, and does not require a complicated current detection process or a complicated current detecting sensor.
The controller 29 outputs a 120 degree, 2-phase PWM voltage to the inverter 24 to start the motor 25. As illustrated in
A combined voltage vector Vs, which is the sum of the Vu and Vw voltage vectors, is shown in
As expressed in Equation 2, the torque of the synchronous reluctance motor is at a maximum value when the current angle θi between the D-axis of the rotor and the current vector IS is 45°.
The control IC 30 outputs a voltage based on a signal outputted by one or more hall sensors. The voltage vector applied to the motor remains constant until the D-axis of the rotor completes a substantially 60 degree rotation. If the D-axis were to lag the current vector IS by 45 degrees in the rotation direction of the voltage vector, and the rotor then rotates by 60 degrees, the current angle (θi) would become approximately −15°, and thus a negative torque would be generated. Thus, to prevent a negative torque from being generated, the D-axis of the rotor may be set at about 75 degrees from the current vector IS.
When the rotor D-axis is placed at an angle ranging from approximately 110 to approximately 120 degrees from the combined voltage vector (Vs) in the opposite direction to the rotation direction, the synchronous reluctance motor can be stably started-up and driven.
The hall sensors Ha 33, Hb 34 and Hc 32 are physically placed at 120 degree intervals around the stator 36, and output a High or a Low signal, depending on whether they sense a flux from an N pole or an S pole of the sensing magnet 35.
Here, the controlling of the inverter (S15) includes controlling the position of the rotor relative to the stator based on the detection of the poles of the sensing magnet by the hall sensors.
To control the inverter, the hall sensor is placed at the center of the coil axis of the stator, and the center of the magnetic flux vector emanating from the sensing magnet is aligned with the D-axis of the rotor.
The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.
The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.
One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.
The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.
Although the invention has been described with reference to several exemplary embodiments, it is understood that the words that have been used are words of description and illustration, rather than words of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified. Rather, the above-described embodiments should be construed broadly within the spirit and scope of the present invention as defined in the appended claims. Therefore, changes may be made within the metes and bounds of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the invention in its aspects.
Number | Date | Country | Kind |
---|---|---|---|
10-2006-0040688 | May 2006 | KR | national |