Magnetic disk storage apparatus

Abstract

Currents of sine waveforms can be fed through coils by a relatively small-sized circuit, and thereby, highly dense magnetic storage can be realized with less rotation variations and a driving control circuit of a motor rotating at a low noise level can be provided. A coil of one phase of a three-phase brushless motor is driven with full amplitude at which an applied voltage becomes equal to a source voltage, and a coil of one of other phases is driven with gradually changing voltages so that a current of sine waveform is delivered, and a coil of the remaining phase is driven by feedback control so that a total current flowing through all coils becomes a predetermined current value.

1 - 9 . (canceled)  
   
   
       10 . A three-phase brushless motor driving circuit apparatus, comprising: 
 driving circuits that feed individually phased sine waveform current to corresponding coils of a three-phase brushless motor,    the driving circuits including:    a first voltage applying means that drives applied voltage to one of the three-phase brushless motor coils until the applied voltage becomes equal to a source voltage applied to the driving circuits,    a second voltage applying means that drives applied voltage to one of the three-phase brushless motor coils until the applied voltage becomes a lower constant voltage compared to the source voltage applied to the driving circuits, the lower constant voltage controlled such that a total current flowing through all coils to ground becomes a predetermined current, and    a third voltage applying means that drives applied voltage to one of the three-phase brushless motor coils such that the applied voltage becomes a gradually increasing voltage.    
   
   
       11 . A three-phase brushless motor driving circuit apparatus according to  claim 10 , 
 wherein the voltages applied to the coils of the three-phase brushless motor are determined by combination of the first, second and third voltage applying means, the first, second and third voltage applying means being controlled such that a voltage of each coil of the three-phase brushless motor becomes a sine wave form.    
   
   
       12 . A three-phase brushless motor driving circuit apparatus according to  claim 11 , 
 wherein the first, second and third voltage applying means are controlled by PWM signals.    
   
   
       13 . A three-phase brushless motor driving circuit apparatus according to  claim 12 , 
 wherein the PWM signals are produced by two PWM modulation circuits, each of which controls the second and third voltage applying means.    
   
   
       14 . A three-phase brushless motor driving circuit apparatus according to  claim 13 , 
 further comprising a pair of operation circuits connected to the two PWM modulation circuits.    
   
   
       15 . A three-phase brushless motor driving circuit apparatus according to  claim 10 , 
 wherein coil driving voltage fed through coils of individual phases by the motor driving control circuit are formed to have phases that are of predetermined electrical angle, corresponding to coil inductance and internal resistance, ahead of phases of back electromotive forces induced in the coils.    
   
   
       16 . A three-phase brushless motor driving circuit apparatus according to  claim 10 , 
 including a motor driving control circuit that controls the driving circuits such that a total current fed through the coils of the three-phase brushless motor becomes a pre-determined current,    the motor driving control circuit including a controller that controls so that the total current fed through the coils matches a current indication value supplied from the controller, and including a current indication value correcting circuit that corrects the current indication.    
   
   
       17 . A magnetic disc apparatus comprising: 
 a three-phase brushless motor driving circuit apparatus according to  claim 10.