Motor drive apparatus for brushless motor
AssigneesCanon Precision Inc., Canon Kabushiki Kaisha
InventorHiromasa MASUTA
Life of this patent
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Abstract
A motor drive apparatus that can be used to drive a wide range of brushless motors without any limit to a magnetic pole number of a rotor magnet. One rotational period T of the rotor magnet is obtained, and one period S of the sine wave drive signal according to a mathematical expression of S=T/(n/2). The one period S of the sine wave drive signal is updated at intervals of one period of the output signal from one magnetic pole detecting element among the three magnetic pole detecting elements.
Claims4
A motor drive apparatus that drives, by a sine wave drive signal, a three-phase n-pole brushless motor having a rotor magnet including a coil unit and magnets with a magnetic pole number n fixed to a rotary shaft, and three magnetic pole detecting elements that detect a rotational position of the rotor magnet, comprising:
- an obtaining unit configured to obtain one rotational period T of the rotor magnet;
- and
- a period updating unit configured to obtain one period S of the sine wave drive signal according to a mathematical expression of S=T/(n/2), and update the one period S of the sine wave drive signal at intervals of one period of the output signal from one magnetic pole detecting element among the three magnetic pole detecting elements.
Dependencies are inferred from the claim text.