Drive control and features
41
(±360/polepairs)° in order to determine the rotor position. In case 2 (open-loop
control), the shaft is turned only in one direction and the angle is smaller.
The standstill modes can be used if the motor cannot be turned (for example, when
the load is connected). As the characteristics of motors and loads differ, testing must
be done to find out the most suitable standstill mode.
The drive is also capable of determining the rotor position when started to a running
motor in open-loop or closed-loop modes. In this situation, the setting of 11.07
AUTOPHASING MODE has no effect.
Thermal motor protection
With the parameters in group 45 MOT THERM PROT, the user can set up the motor
overtemperature protection and configure motor temperature measurement (if
present). This block also shows the estimated and measured motor temperature.
The motor can be protected against overheating by
• the motor thermal protection model
• measuring the motor temperature with PTC or KTY84 sensors. This will result in a
more accurate motor model.
Thermal motor protection model
The drive calculates the temperature of the motor on the basis of the following
assumptions:
1) When power is applied to the drive for the first time, the motor is at ambient
temperature (defined by parameter 45.05 AMBIENT TEMP). After this, when power
is applied to the drive, the motor is assumed to be at the estimated temperature
(value of 1.18 MOTOR TEMP EST, saved at power switch-off).
2) Motor temperature is calculated using the user-adjustable motor thermal time and
motor load curve. The load curve should be adjusted in case the ambient
temperature exceeds 30 °C.
It is possible to adjust the motor temperature supervision limits and select how the
drive reacts when overtemperature is detected.
Note: The motor thermal model can be used when only one motor is connected to
the inverter.
Absolute encoder/resolver
Rotor
N
S
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