Brushless dc motor


PURPOSE:To prevent the oversaturation of a coil drive transistor and to eliminate an oscillation upon correction of a current by detecting the operating voltage of the transistor and operating current correcting means provided with a low pass filter. CONSTITUTION:A DC motor which has a magnet 11 and 3-phase coils 12-14 is controlled by an instruction signal generator 18 by respectively applying the signals of rotor position detecting Hall elements 14-17 to differential amplifiers 43-45. In this case, the voltage A of a reference voltage generator C is compared with the outputs of transistors 51-53 which detect the operating voltages of coil drive transistors 48-50, thereby controlling the currents of the transistors 48-50 through a current mirror circuit B, a transistor 24 and a condenser 33 of a low pass filter. Accordingly, the oversaturation of the transistors 48-50 is prevented, thereby smoothly operating the current correction and preventing the drawback such as oscillation or the like.




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Patent Citations (1)

    Publication numberPublication dateAssigneeTitle
    JP-S5633986-AApril 04, 1981Mitsui Toatsu Chem IncColor developing sheet for pressure sensitive transfer paper

NO-Patent Citations (0)


Cited By (3)

    Publication numberPublication dateAssigneeTitle
    US-4494053-AJanuary 15, 1985Matsushita Electric Industrial Co., Ltd.Winding voltage balancing circuit for brushless DC motor
    US-4588933-AMay 13, 1986Motorola, Inc.Brushless direct current motor control system with protection circuitry
    US-4987352-AJanuary 22, 1991Mitsubishi Denki Kabushiki KaishaBrushless motor driver