Electricity: motive power systems – Switched reluctance motor commutation control
Reexamination Certificate
2001-01-16
2002-11-12
Dang, Khanh (Department: 2837)
Electricity: motive power systems
Switched reluctance motor commutation control
C318S132000, C318S434000, C318S608000
Reexamination Certificate
active
06479956
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a controller that controls the rotational speed of a brushless motor to achieve a desired motor speed; and, more particularly, the invention relates to an air conditioner that conditions interior air by controlling the brushless motor driving its internal compressor/blower using this controller, to a refrigerator that provides refrigeration by controlling the brushless motor during its internal compressor/blower using the controller, to a washing machine that washes clothes by controlling the brushless motor during its pulsator or spin-basket using the controller, and to a vacuum cleaner that cleans rooms by controlling the brushless motor driving its blower using the controller.
Because of their easy maintenance, brushless motors, which include a combination of a permanent magnet rotor and stator coils, are used in air conditioners, refrigerators, washing machines, and the like.
Brushless motor driving control requires close linking between the magnetic pole position of the rotor and the positions of the stator coils. A sensorless position detection scheme utilizing the counter-electromotive force induced into the stator coils by their interactions with the magnetic pole of the rotor is employed to detect the magnetic pole position of the rotor; it is not detected using a rotor position detection sensor, such as a Hall element.
Brushless motor drives using the sensorless position detection scheme include those set forth in, for example, Japanese Application Patent Laid-Open Publication No. Hei-6-284783 and Hei-6-98583. For these brushless motor drives, which are so designed as to detect the crossing point (namely, the rising or falling edge) between the terminal voltages of the motor and a reference voltage, the required electrical angle (for example, 15 degrees) is calculated in one way or another immediately after commutation so that a spike voltage signal will not be detected as a rotor position detection signal, and the time corresponding to this electrical angle is set as a position detection inhibition interval. During this inhibition interval, signal detection is inhibited, and signals are acquired only after the elapse of the inhibition time. Or, the crossing point (namely, the rising or falling edge) with respect to the reference voltage is detected by modifying the pattern of chopping by only the upper and lower switching devices among all six switching devices, and motor control is based on the detection position.
For conventional brushless motor drives, since the required electrical angle must be calculated in one way or another immediately after commutation, the use of a microcomputer or the like to calculate this angle increases the processing time required, or the use of an external circuit to perform the calculation requires a complex circuit composition.
In the case of these conventional brushless motor drives, although mis-judgment based on the spike voltage developed during the inhibition interval can be prevented by providing the inhibition interval, if an abrupt load change causes output of a rotor position detection signal during the inhibition interval immediately after commutation, this signal cannot be detected. For this reason, there arises a problem in that, since a position significantly offset from the actual position of the rotor is likely to be mis-judged as the actual rotor position, the operation becomes unstable or the motor decreases in operational efficiency or steps out.
An object of the present invention is to provide a brushless motor controller that can properly detect the position of a rotor immediately after commutation, without being provided with a position detection inhibition interval immediately after commutation.
Another object of the present invention is to provide a low-cost and simplified brushless motor controller that is high in rotor magnetic pole position detection accuracy and is capable of accurately controlling the corresponding brushless motor as well.
Still another object of the present invention is to provide a motor controller that can properly control a brushless motor without stopping it, even during a very long interval of flow of a reflux current after power-on switching.
A further object of the present invention is to minimize position detection errors due to noise.
A further object of the present invention is to provide a brushless motor controller that can minimize the occurrence of a power-on malfunction due to noise.
A further object of the present invention is to provide a brushless motor controller that can automatically attach importance to more efficient or faster operation during brushless motor operational control.
A further object of the present invention is to provide a brushless motor controller that covers a larger control range.
A further object of the present invention is to provide appliances, especially an air conditioner, a refrigerator, a washing machine, and a vacuum cleaner, that are powered from the brushless motor thus controlled.
SUMMARY OF THE INVENTION
A feature of the present invention for achieving the objects described above is characterized in the fact that a first information signal pattern is stored into an information signal pattern storage means; and, when the first information signal pattern and a third information signal pattern are the same and a second information signal pattern is different from the other two patterns, a reflux current decay signal is generated by an information signal pattern comparison means.
According to this feature, when the first information signal pattern and the third information signal pattern are the same and the second information signal pattern is different from the other two patterns, since a reflux current is generated immediately after commutation and is then decayed, the information signal pattern comparison means compares the first information signal pattern, the second information signal pattern, and the third information signal pattern, and generates a reflux current decay signal. Thus, the loss of the reflux current can be detected. As a result, the position of the rotor can be properly detected immediately after commutation, without providing a rotor position detection inhibition interval, by detecting the loss of the reflux current and then detecting the rotating position of the rotor in accordance with the information signal patterns created by the corresponding information signal generation means. Even if the load changes abruptly, the corresponding brushless motor can also be driven with rapid response, since no inhibition time interval needs to be calculated.
In addition, since rotor position detection is possible without the chopping pattern of any switching device, the position of the rotor can be detected properly, even if the upper or lower three of six switching devices low operating speed devices and are inexpensive.
Another feature of the present invention resides in the fact that the first information signal pattern that has been stored into the above-mentioned information signal pattern storage means is changed to the second information signal pattern by an information signal pattern changing means using a reflux signal decay signal.
According to this feature, when the first information signal pattern and the third information signal pattern are the same, and the second information signal pattern is different from the other two patterns, since a reflux current is generated immediately after commutation and is then decayed, and since the second information signal pattern is an information signal pattern corresponding to the rotor position to be detected, the position of the rotor can be properly detected immediately after commutation, without providing a rotor position detection inhibition interval, by detecting from all information signal patterns generated by the information signal generation means, only the information signal pattern matching the second information signal pattern stored within the information signal pattern storage means, and then detecting
Ishii Makoto
Kawabata Yukio
Notohara Yasuo
Shinozaki Hiroshi
Tahara Kazuo
Antonelli Terry Stout & Kraus LLP
Dang Khanh
Hitachi , Ltd.
LandOfFree
Brushless motor control device and equipment using the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Brushless motor control device and equipment using the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brushless motor control device and equipment using the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2940563