;*******************************************************************************
;PROGRAM			:	Closed Loop V/F control of 3-Phase Induction Motor
;MICROCONTROLLER	:	PIC18Fxx31	
;*******************************************************************************
;*******************************************************************************
;AUTHOR		:	Jon Burroughs, 
;			:	based on V/f code by Padmaraja Yedamale
;			:	Microchip Technology Inc
;DATE		:	2/11/04
;Version	:	V1.0
;*******************************************************************************
;Description:
;
;This code implements closed loop V/f control of a three-phase induction motor using
;the PIC18F4431 Microcontroller.  This code accompanies the application note
;AN890 "3-Phase AC-Induction Motor Control Using the PIC18F4431"
;
;Velocity feedback is added to standard V/f control to control speed more accurately
;with varying loads.
;
;Potentiometer connected to AN1 is used to set target velocity.  Target velocity is compared 
;to actual velocity to generate velocity error.  Velocity error used by PID algorithm to determine 
;the drive frequency.  The drive frequency is then input to V/f algorithm.
;
;Feedback from QEI in x2 velocity mode is a 16-bit value corresponding to the period of time 
;between edges of QEA signal.  To simplify error calculation, the ADC result is used to set a
;target period value, rather than velocity.  The error = target period - actual period.  The PID output
;is drive period, which is then converted to drive frequency for use with V/f algorithm.
;
;*******************************************************************************
;                    Software License Agreement                       
;                                                                     
; The software supplied herewith by Microchip Technology              
; Incorporated (the "Company") for its PICmicro