MLX90804 Datasheet, PDF (7/12 Pages) List of Unclassifed Manufacturers – Speed regulator for universal motors

FREF
FOSC/MULT
MLX90804
Speed regulator for universal motors
input frequency
multiplier
FOSC
DIV [MULT]
N
FOSC/MULT
CE
UPCOUNTER
CONTROL
LATCH
N = (FOSC/MULT)/FREF
MULT
DIV [N]
FOUT
FOUT = FOSC/N = FREF*MULT
PX3
PX2
PX1
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Kp
8
4
2
1
1 -> 4
2 -> 4
1 -> 2
4 -> 8
SFT1
SFT0
Duration in half
periods
0
0
0
0
1
7
1
0
15
1
1
31
regulator is kept at zero. If PX[3] = 0, the Kp factor is
fixed all the time. If PX[3] = 1, the Kp factor changes
at the moment the measured speed gets higher than
the start speed, which is defined by SPE[1:0]. At
the same moment the SETP integrator (see PI
regulator) is enabled and preloaded with the value
of the measured speed.
PI regulator
The PI regulator calculates the ignition point that
corresponds to a selected speed. The signal SETP
is driven from the sets of speeds in the ROM table.
The signal REAL is driven from the frequency
meter and corresponds to the real speed.
The error signal ERR at sample time n is the
difference between the measured speed and the
desired speed for this sample time. The error is
multiplied by the proportional coefficient to form the
proportional part ERRP. The same error is
multiplied by the integral coefficient and summed
with the previous errors. The accumulated integral
error ERRI is then added to the proportional to
form the final product ERRPI. This product is
subtracted from the fixed MIN_ANGLE to form the
triac ignition point (the new estimated firing angle)
The coefficients are mask programmable: Kp is
defined by PX[3:1] and Ki is defined by SSE[1:0].
For smooth operation and to avoid overshoots, the
setpoint (desired speed) is ramped from its present
value to the a desired value:
M_ML_LX_X9₉0₀2₈xx₀₄Na_Sm_pe_eeo_df S_ree_gn_us_lo_ar_{tor for universal motors} Re_Pv_aY_g.X_{e 7}
22/Aug/98 _{Rev 1.0 3}P_0/a_Jg_ue_n7_/00