Synchronous Spindle Motor Drive
EDT. DATE DESIG. DESCRIPTION PAGE /29
02 2003.10.15 K.Takahashi
dded SSM etc. Y.Toyozawa
03 2004.06.09 K.Takahashi Revised Pole detect, etc. Y.Toyozawa
7. Pole position detection function
It is necessary that Spindle software recognize the pole position for the control of synchronous motor.
Therefore, SPM must to execute the pole position detection after become the lost status of pole position.
Detection mode of pole detection and How to use
In case of spindle software 9D53/C (9D70/B) or later, the following mode of pole detection and AMR offset
function can be used. In case of spindle software except the above, pole detection can apply only DC current
mode (conventional mode).
AMR offset function is recommended to prevent unevenness of output torque by unevenness of pole detection
1) Auto mode (recommendation mode)
Behavior: The pole position is detected by minute moving of the motor. If the motor can’t move at this time,
SPM changes Minute moving mode in Stop state mode.
Application: It is applied to the machine that the motor can or can’t move during the pole detection.
Setting: No.4398#2(SELMET)=1, refer to the explanation of this chapter about other settings.
As for Minute moving mode, the current flows for a short time and SPM judges the movement of
motor, and the pole position is detected by two points of searches method. Therefore, the pole
detection is detected with about 4Hz minute moving less than 5degrees machine angle.
Note) Stop state mode (special setting of Auto mode)
Behavior: It is possible to detect the pole position at the motor stop state.
Application: It is applied to the machine that the motor movement isn’t allowed during the pole detection
Setting: No.4398#2(SELMET)=1 and the digit 4
of No.4083=0, refer to the explanation of this
chapter about other settings.
For using the Stop state mode, it is better to satisfy the following condition. If the following condition can’t
be satisfied, the accuracy of the pole detection may become to worse.
Motor inductance Lq and Ld is different more than 1mH. (Lq-Ld > 1mH)
The magnetic saturation can be observed at 70% of maximum current of amplifier.
(Torque constant becomes 5% down at 70% of maximum current)
2) DC current mode (conventional mode)
Behavior: The motor will stop with large vibration during the pole detection.
Application: The motor must be free when the pole detection is executed.
Setting: No.4398#2(SELMET)=0, refer to the explanation of this chapter about other settings.
7.1 Caution about Pole detection
It is necessary to pay attention to the following caution about Pole detection.
(1) It is necessary to detect the pole position after power on or occurred alarm of forgetting the pole position.
(2) In case of DC current mode, the motor might cause the hitting noise against the flank of the gear tooth when
the pole detection is executed, because the motor will stop with the vibration from the logic of pole detection.
Therefore, DC current mode requires free space to move the motor.
(3) In case of Auto mode (Minute moving mode + Stop state mode; 9D53/C, 9D70/B or later), the motor motion is
a few distances against DC current mode. When Auto mode is executed, Minute moving mode is executed at
first. If SPM judges the motor can not move (motor lock state), SPM changes the mode from Minute moving
mode to Stop state mode, and the pole-detection is continued.
(4) If the accuracy of the pole detection is lower, the motor output torque will be small.
(5) In the state of the lost pole-position, SPM will neglect the all of command (Speed command.
etc.) to be entered. But those commands will be enabled the moment the pole-detection is finished. Therefore,
if the pole detection is executed in the state to enter the command, the motor begins to rotate the moment the
pole-detection is finished. This behavior may be uncomfortable for the operator. Accordingly, the command
input should be executed in the state of the pole-detection complete (F048#7:EPFIX=1).