7-19
Chapter 7. PARAMETER SETUP
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(motor control method selection)
0: MFB control (conventional) + estimated position control
1: MFB control (conventional) only
2: Estimated position control only
• 0: MFB control (conventional) + estimated position control
• When MFB (Motor Feed Back) input is normal, the motor position
is controlled by the actually measured MFB.
• When MFB input is in error, the motor position is controlled by an
estimated MFB value. This state is referred to as “estimated posi-
tion control state.”
For example, when the motor rotates at a position where the feed-
back potentiometer has deteriorated, MFB input changes suddenly.
This sudden change is detected as an error, and the correct MFB
position is estimated. The motor position is also controlled by
the estimated MFB value when the MFB disconnected alarm has
occurred.
• In the estimated position control state, an error will inevitably
occur between the actual motor valve opening and estimated MFB
value.
So, set the closed-side relay to ON at all times when output (MV)
≤ 0.0 %, and the open-side relay to ON at all times when MV ≥
100.0 % to set the motor to a fully-open or fully-closed state to
compensate this error.
However, note that this error is not compensated when MV is
limited to within 0.1 to 99.9 % by the output limitter, or when MV
is 0.0 % or less or 100 % or more due to the control state.
• The following are probable causes when estimated position control
is likely to be carried out:
- Defective motor valve opening adjustment
- Deteriorated feedback potentiometer, insufficient resolution
- Defective MFB wiring.
• 1: MFB control (conventional) only
• When this setting is used, conventional MFB control is carried
out. When the MFB disconnected alarm occurs, the MFB value is
regarded as 150.0 %, and the closed-side relay is ON at all times.
• 2: Estimated position control only
• When this setting is used, control is in the estimated position
control state at all times, and the motor position is controlled by
the estimated MFB value regardless of the state of MFB wiring.
• When this setting is used, enter the correct
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item.
