C**************************************************************
      
!  This component has been assigned Type Number 203. If that number conflicts with 
!  another user Type number, you will need to change it and recompile the appropriate
!  dll.

	SUBROUTINE TYPE203(TIME,XIN,OUT,T,DTDT,PAR,INFO,ICNTRL,*)

!DEC$ATTRIBUTES DLLEXPORT :: TYPE203
	
	

C     Version from: 12/13/89
C     SAMPLE INPUT AND OUTPUT FOLLOWS THE NOMENCLATURE
C--------------------------------------------------------------
C**** This Type represents a Ventilator type load, which is
C     designed to run with an electric motor. 
C**************************************************************
C**** Nomenclature:

C**** TRNSYS specific variables:
C     XIN == input array
C     OUT == output array
C     PAR == parameters
C     TIME == simulation time
C     T,DTDT == not used in this component
C     S	== storage array
C     NSTORE == dimension of S
C     IAV == pointer within S 
C     ISTORE == index
C     INFO == array to use TRNSYS internal information	

C**** C1,C2,C3 -- constants
C     COUNTER -- counting the number of iterations
C     CHANGE -- auxilary variable
C     EPS -- error tolerance for newton iteration   
C     FAIL -- message if operating conditions are out of range
C              :0 = everything is okay
C              :1 = max. speed is exceeded
C              :2 = Newton iteration did not converge within
C	            specified tolerance
C     FN --  objective function for Newton iteration
C     FPRIMEN -- first derivative of the objective function
C     MAXIT -- the limit on the number of iterations to find the
C              speed
C     MODE -- determines whether torque or speed is significant
C             :1 = torque is significant
C             :2 = speed is significant
C     N  -- Speed
C     NINIT -- initial value of a speed for the iterative process 
C              to find the motor speed for a given torque
C     NMAX -- maximum permitted speed
C     NOLD -- speed from previous iteration
C     P -- Fan power [watts]
C     PI - pi
C     TL -- Torque 
C**************************************************************
C
C     SAMPLE INPUT AND OUTPUT
C
C     INPUTS            SAMPLE VALUES
C     XIN(1) TL              .6
C
C     PARAMETERS        SAMPLE VALUES
C     PAR(1) C1              .3
C     PAR(2) C2              .00039
C     PAR(3) C3             1.8
C     PAR(4) NMAX        5000.0
C
C     OUTPUTS           SAMPLE VALUES
C     OUT(1) N              6.385
C     OUT(2) TL              .6
C     OUT(3) P             24.07
C     OUT(4) FAIL           0.0
C
C***************************************************************


      IMPLICIT NONE
	DOUBLE PRECISION XIN, OUT	
      INTEGER ISTORE,NSTORE,IAV	
      INTEGER INFO,COUNTER,MAXIT,FAIL
      REAL TIME,T,DTDT,ICNTRL,PAR,S
      REAL TL,N,NINIT,C1,C2,C3,FN,FPRIMEN,NNEW,CHANGE
      REAL NMAX,EPS,PI,NOLD,P
      DIMENSION XIN(1), OUT(4), PAR(4), INFO(15)

C**************************************************************

      COMMON /STORE/ NSTORE,IAV,S(5000)

!    Set the version information for TRNSYS
      IF (INFO(7).EQ.-2) THEN
	  INFO(12) = 15
	  RETURN 1
	ENDIF


C--------------------------------------------------------------
C**** Initial call in simulation
      IF (INFO(7).LT.0) THEN 

        INFO(6)=4
        INFO(9)=0

C****   storage allocation: speed from previous iteration
C****   is stored in the S-array
C****   S(ISTORE) -- NOLD
						
        INFO(10)=1
        CALL TYPECK(1,INFO,1,4,0)
        ISTORE=INFO(10)


C****   set parameters
        C1=PAR(1)
        C2=PAR(2)
        C3=PAR(3)
        NMAX=PAR(4)

	NINIT=0.01*NMAX
	NOLD=NINIT

        MAXIT=30
	EPS=0.0001

C****   accurate expression for pi
        PI=ACOS(-1.)

C--------------------------------------------------------------
C**** first and following calls in timestep
      ELSE

        FAIL=0

C****   set inputs
        TL=XIN(1)
		
        IF(TL.LT.C1)THEN
          N=0.
        ELSE
	  
C****     Iteration using Newton's method to find speed
          COUNTER=0

	  NINIT=S(ISTORE)
          NNEW=NINIT
          N=NINIT
100       CONTINUE

          FN=C1+C2*((2.*PI*N)**C3)-TL
          FPRIMEN=2.*PI*C3*C2*((2.*PI*N)**(C3-1.))
          CHANGE=-FN/FPRIMEN
          IF (ABS(CHANGE).GE.EPS) THEN
            NNEW=N+CHANGE
            IF (COUNTER.GE.MAXIT) THEN
              FAIL=2
            ELSE
              N=NNEW
              COUNTER=COUNTER+1
              GOTO 100
            ENDIF
          ELSE
            N=NNEW
          ENDIF

        ENDIF

      ENDIF
C--------------------------------------------------------------


C**** Control on speed, speed can't be negative
      IF (N.LT.0) THEN
        N=0. 
      ELSE
C****   control on max.speed
        IF(N.GT.NMAX)THEN
          FAIL=1
        ENDIF
      ENDIF         

      IF(N.NE.0.)THEN
	NOLD=N
      ENDIF
		
      S(ISTORE)=NOLD
      P=2.*PI*N*TL
	      
C**** set outputs
      OUT(1)=N
      OUT(2)=TL
      OUT(3)=P
      OUT(4)=FAIL	
      	
	RETURN 1
      END