The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 03, 2008
Filed:
Dec. 02, 2004
Shuji Endo, Gunma, JP;
Masahide Saito, Gunma, JP;
Kenji Mori, Gunma, JP;
Lilit Kovudhikulrungsri, Gunma, JP;
Toru Sakaguchi, Gunma, JP;
Shuji Endo, Gunma, JP;
Masahide Saito, Gunma, JP;
Kenji Mori, Gunma, JP;
Lilit Kovudhikulrungsri, Gunma, JP;
Toru Sakaguchi, Gunma, JP;
NSK Ltd., Tokyo, JP;
NSK Steering Systems Co., Ltd., Tokyo, JP;
Abstract
In a motor driving device where a motor having a winding wire with small inductance value is driven by a digital control means comprised of control means including a current command value calculating means, a current control means and a PWM control means whose sampling periods are different from each other, when discrete signals sampled by the respective control means are zero-order-held, a motor current includes a lot of higher harmonic waves due to a quantization error, thereby increasing a motor noise. When an n-th-order hold means is provided between the respective control means with different sampling periods, the quantization error can be reduced remarkably, and thus the higher harmonic wave components included in the motor current are reduced, thereby greatly reducing the motor noise.