Rockwell Automation SA500 AC Power Modules - Manual (Page 39)

Installation Guidelines 4-11
4.6.1.1 Resolver Calibration
The resolver input can be used with X1 and X2 resolvers with cable distances as
shown in table 4.4.
The PMI contains circuitry to synchronize the reference waveform to within 10 degrees
of the returning waveforms. This synchronization corrects for any phase shift which
can occur between the reference and stator signal (i.e., stator signals lagging the
reference) due to unbalanced wire impedance. The impedance increases as the cable
length increases. The synchronization is done automatically at power up after the PMI
receives the configuration data from the UDC module informing it that a resolver has
been selected for speed feedback.
The programmer must use the following calibration procedures to adjust the gain to
the proper level and balance the sine/cosine waveforms. These procedures should be
performed during initial system installation, if the resolver is replaced, or if the resolver
cabling is changed (e.g., the cable is lengthened, shortened, or a different cable type
is used). After the calibration procedures are performed, the gain and balance values
are sent, along with other feedback data, to the UDC module to be stored for use at
subsequent power ups. The values are stored in local tunables with the reserved
names RES_BAL% and RES_GAN%.
Note that Distributed Power System drives are designed to be used with the standard
resolvers listed in table 4.3 and described in Appendix A. The validity of the results of
these calibration procedures is not guaranteed if resolvers other than those specified
are used.
Gain Calibration
The gain calibration is performed when the value stored in RES_GAN% equals zero
(i.e., at initial system start-up or by the operator setting the value to zero). This
procedure may be performed while the resolver is turning or stationary. Do not perform
this procedure while the minor loop is running (i.e., bit 0 of register 200/1200 is set) or
a drive fault will be generated (register 202/1202, bit 8).
The procedure adjusts the gain to bring the stator voltages to a nominal 11.8 VAC at
the board’s input. The range of the gain adjustment is 0-37 VAC at the rotor with a
resolution of 0.15V. The nominal value is 26 VAC. When the gain calibration procedure
is completed, bit 6 of UDC register 201/1201 will be set, and the gain value will be
stored in RES_GAN%. Large gain values (close to 255) may indicate a problem with
the resolver wiring or connections. Always check the value stored in RES_GAN% after
the gain calibration procedure has been completed.
Note that the resolver must be connected to the motor in order for this procedure to be
completed. If the system determines a maximum gain value (255) and detects a
broken wire (indicated by bit 8, register 202/1202) while attempting to calibrate the
gain, it will assume that a resolver is not connected. When the broken wire bit is
cleared by the operating system (indicating that a resolver has been connected), the
gain calibration will automatically re-start. If bit 6 of register 201/1201 is not set, the
calibration procedure has not been completed.