Appendix: Permanent magnet synchronous motors (PMSMs) 433Start modeThe default value of parameter 2101 START FUNCTION is 1 (AUTO). In most casesthis is suitable for starting the rotation. If fast start with low inertia is required, it isrecommended to set parameter 2101 START FUNCTION to 2 (DC MAGN).Smooth startThe Smooth start function can be used if the motor is not able to start or whenrotation at low speeds needs to be improved. The following table lists the neededparameter settings.Speed controller tuningIn vector control mode, it is recommended to tune the speed controller. Inapplications where the motor can be rotated freely, automatic tuning can be used.See parameter 2305 AUTOTUNE RUN for more information.Usually it is enough to adjust the proportional gain (parameter 2301 PROP GAIN) ofthe speed controller to a higher value. The default value is 5 which results in ratherconservative speed controller tuning. Increase the proportional gain value by 5 untilthe performance is satisfactory. If the application becomes unstable, divide the lastgain value by 2, and you have reached rather robust speed controller tuning.Note: It is recommended to use encoder feedback if accurate torque control, hightorque production, or sustained operation is required at low speeds (below 20% of themotor nominal speed). Adjusting motor speed estimation gain in case of an over currentfailureThe inertia of the PM motor application may cause over current trips. If the drive failsconstantly to over current with the PM motor (Fault 01), the speed estimation gainmay need to be adjusted. This is done by changing the parameter 2626 SPD ESTBW TRIM.No. Name Value Description Default2621 SMOOTHSTART012DisabledEnabled alwaysStart only02622 SMOOTHSTARTCUR10…100% Current applied to the motor when the Smooth startis active. Increasing the current helps enable startingwith a load or with a large inertia. Decreasing thecurrent can prevent the rotor from turning into awrong direction during the start.50%2623 SMOOTHSTARTFRQ2…100% Set the smooth start frequency range as small aspossible. This should be tuned so that the rotation isstable throughout the whole speed range.10%
