Delta VFD300C43S-HS User Manual page 404

Chapter 12 Description of Parameter SettingsC2000-HS
Slip Compensation Filter Time (V/F and SVC Control Mode)

Settings
 Change the compensation response time with Pr.07-24 and Pr.07-25.
 If you set Pr.07-24 and Pr.07-25 to 10 seconds, the compensation response time is the slowest;
however, the system may be unstable if you set the time too short.
Torque Compensation Gain (V/F and SVC control mode)

Settings
 Only applicable in IMVF and PMSVC control mode.
 With a large motor load, a part of drive output voltage is absorbed by the stator winding resistor;
therefore, the air gap magnetic field is insufficient. This causes insufficient voltage at motor
induction and results in excessive output current but insufficient output torque. Auto-torque
compensation can automatically adjust the output voltage according to the load and keep the air
gap magnetic fields stable to get the optimal operation
 In the V/F control, the voltage decreases in direct proportion with decreasing frequency. It
reduces the torque decrease at low speed due to the AC impedance while the DC resistor is
unchanged. The auto-torque compensation function increases the output voltage at low
frequency to get a higher starting torque.
 When the compensation gain is set too large, it may cause motor over-flux and result in a too
large output current, overheating the motor or triggering the protection function.
 This parameter affects the output current when the drive runs. But the effect is smaller at the
low-speed area.
 Set this parameter higher when the no-load current is too large, but the motor may vibrate if the
setting is too high. If the motor vibrates when operating, reduce the setting.
Slip Compensation Gain (V/F and SVC control mode)

Settings
 The induction motor needs constant slip to produce magnetic torque. It can be ignored at higher
motor speeds, such as rated speed or 2–3% of slip.
 In operation, the slip and the synchronous frequency are in reverse proportion to produce the
same magnetic torque. The slip is larger with the reduction of synchronous frequency. The motor
may stop when the synchronous frequency decreases to a specific value. Therefore, the slip
seriously affects the motor speed accuracy at low speed.
 In another situation, when you use an induction motor with the drive, the slip increases when the
load increases. It also affects the motor speed accuracy.
 Use this parameter to set the compensation frequency, and reduce the slip to maintain the
synchronous speed when the motor runs at the rated current in order to improve the accuracy of
the drive. When the drive output current is higher than Pr.05-05 (No-load Current of Induction
0.001–10.000 sec.
IM: 0–10 (when Pr. 05-33 = 0)
PM: 0–5000 (when Pr. 05-33 = 1 or 2)
0.00–10.00
12.1-07-13
Default: 0.100
Default: 0
Default: 0.00
(1.00 in SVC mode)