Motor drive apparatus and electric power steering apparatus

(19)

(11)

EP 1 591 347 A8

(12)	CORRECTED EUROPEAN PATENT APPLICATION
	Note: Bibliography reflects the latest situation

(15)	Correction information:
	Corrected version no 1 (W1 A2)

(48)	Corrigendum issued on:
	29.03.2006 Bulletin 2006/13

(88)	Date of publication A3:
	28.12.2005 Bulletin 2005/52

(43)	Date of publication:
	02.11.2005 Bulletin 2005/44

(21)	Application number: 05103354.6

(22)	Date of filing: 26.04.2005

(51)

International Patent Classification (IPC):

B62D 5/04^(1968.09)

H02P 6/18^(1995.01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR
	Designated Extension States:
	AL BA HR LV MK YU

(30)

Priority:

28.04.2004 JP 2004133811

(71)	Applicants:
	NSK Ltd. Tokyo 141-8560 (JP) NSK Steering Systems Co. Ltd Shinagawa-ku, Tokyo 141-8560 (JP)

(72)	Inventors:
	Ta, CaoMinh Gunma 371-0845 (JP) Endo, Shuji Gunma 371-0845 (JP) Kobayashi, Hideyuki Gunma 371-0845 (JP) Saito, Masahide Gunma 371-0845 (JP)

(74)	Representative: Hooiveld, Arjen Jan Winfried
	Arnold & Siedsma Sweelinckplein 1 2517 GK Den Haag 2517 GK Den Haag (NL)

(54)	Motor drive apparatus and electric power steering apparatus

(57) The present invention provides a motor drive apparatus capable of calculating an angular velocity and a rotation angle accurately in the entire rotation velocity range of a motor using a cheap Hall sensor having an inferior accuracy without using an expensive resolver having a high accuracy. The present invention includes a first angular velocity calculating means (20) for calculating the angular velocity based on the back-EMF of the motor when it rotates at low speeds and a second angular velocity calculating means (30) for calculating the angular velocity based on a signal from the Hall sensor when it rotates at high speeds. According to the present invention, the angular velocity and rotation angle can be calculated accurately in the entire rotation speed range using the Hall sensor under hybrid usage.