Drive control system for sensor-less motor

Abstract

There is provided a drive control system for sensor-less motor wherein a multi-phase sensor-less motor is driven to rotate by switching a current to be applied to a field coil of each phase depending on the rotating phase of motor and such rotating drive is controlled with the PLL control method and the sensor-less motor is driven with higher reliability. When the motor is to be driven, a desired phase is selected as the detection phase and a voltage (Eu, Ev, Ew) induced on the coil of the detection phase is detected when the power is fed for a short period of time to the field coils except for that of the detection phase. A magnetic pole position of a rotor is detected from the amplitude condition of the detected induced voltage and the power feeding phase of the motor drive is determined based on the result of detection of the magnetic pole position. The power feeding for drive is executed depending on this determination to alternately conduct the detection of magnetic pole position and power feeding for motor drive. Moreover, error detection in the method explained above is executed accurately to quickly and adequately execute the process after generation of a fault.

1 . A drive control system for sensor-less motor for driving a motor and executing PLL control to rotary drive by switching a current of a field coil in each phase of the multi-phase motor depending on the rotating phase of the motor, comprising: 
 power feeding means for feeding electrical power, for the predetermined period, to a field coil in the phase other than the detection phase by defining a desired phase as the detection phase at the time of driving a motor;    induced voltage detecting means for detecting a voltage induced on said coil of the detection phase through said power feeding;    magnetic pole position detecting means for detecting the magnetic pole position of a rotor from the amplitude condition of said induced voltage;    driving means for determining the power feeding phase for drive of motor based on the detection result of said magnetic pole position detecting means, and executing the power feeding for drive depending on said determination; and    controlling means for alternately conducting detection of magnetic pole position by said power feeding means, induced voltage detecting means, and magnetic pole position detecting means, and power feeding to drive a motor by said driving means.    
   
   
       2 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein all phases are defined as the detection phase only for the first detection of magnetic pole position and a condition of an induced voltage is detected for each detection phase, the magnetic pole position of a rotor is detected based on said detection, a condition of an induced voltage is detected in the next detection of magnetic pole position by defining, as the detection phase, only one phase detected based on the result of preceding detection of magnetic pole position, and the magnetic pole position of the rotor is detected based on said detection.    
   
   
       3 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein a control means is also provided to execute the control for re-setting detection parameters when said detection magnetic pole position fails and to re-try said detection of magnetic pole position after said control.    
   
   
       4 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein a control means is also provided to execute the control to shift the rotor position with an open loop control when said fail of magnetic pole position detection is repeated for the predetermined number of times, and to re-try said detection of magnetic pole position after said control.    
   
   
       5 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein when the conditions of induced voltages detected in each phase are all identical or when amplitudes of induced voltages detected in all phases are smaller than the predetermined threshold value, said detection of magnetic pole position is judged to be failed.    
   
   
       6 . A drive control system for sensor-less motor according to  claim 1 , wherein detection of said induced voltage is executed by accumulating a plurality of detected values obtained in the predetermined detection section and condition of induced voltage is judged using said accumulated value.  
   
   
       7 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein a means is also provided to logically judge, when an amplitude of an induced voltage obtained in any detection phase of said induced voltage is less than the threshold value, the magnetic pole position based on the condition of said induced voltage which has been normally detected with inclusion of the preceding magnetic pole position detection result.    
   
   
       8 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein an offset voltage is detected, prior to detection of said induced voltage, from a coil in the phase as the detection object and only the induced voltage element is detected by subtracting the detected offset voltage from the detected induced voltage.    
   
   
       9 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein said induced voltage is converted to a digital value, such digital conversion is executed for a plurality of times for every detection section and results are accumulated and this accumulated value is used as the detected value.    
   
   
       10 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein unlock of the PLL control is detected when the motor rotation is accelerated with the PLL control, and the control sequence for recovery to normal condition is executed by setting a flag when unlock is detected.    
   
   
       11 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein a fault of said PLL control is judged depending on whether the zero-cross of B-EMF is detected or not in the B-EMF detection section under the control of motor rotation with the PLL control.    
   
   
       12 . A drive control system for sensor-less motor according to  claim 1 , 
 wherein the condition setting parameters for said detection of magnetic pole position are stored in a programmable non-volatile memory, and contents of this non-volatile memory can be updated or manipulated from the external side via a serial input/output port.