4–70

Setting Motor Constants for Vector Control

Operations and Monitoring

Manual Setting of Motor Constants

With vector control, the inverter uses the output current, output voltage, and motor constants to estimate the motor torque and speed. It is possible to achieve a high starting torque and accurate speed control at low frequency

•Sensorless Vector Control – improved torque control at output frequencies down to 0.5 Hz. Use A044=03 (1st motor) or A244=03 (2nd motor) to select sensorless vector control.

•Sensorless Vector Control, 0Hz Domain – improved torque control at output frequencies from 0 to 2.5 Hz. Use A044=04 (1st motor) or A244=04 (2nd motor). For this vector control method, we recommend using a motor that is one frame size smaller than the inverter size.

•Sensorless Vector Control with Feedback – improved torque control at all speeds, while providing the most accurate speed regulation

If you do use any vector control methods, it is important that the motor constants stored in the inverter match the motor. We recommend first using the auto-tuning procedure in the previous section. If satisfactory performance through auto-tuning cannot be fully obtained, please adjust the motor constants for the observed symptoms according to the table below.

CAUTION: If the inverter capacity is more than twice the capacity of the motor in use, the inverter may not achieve its full performance specifications.

Operation StatusSymptomAdjustmentParameter

 

 

 

 

 

 

 

 

Powered running

When the speed deviation

Slowly increase the motor constant

H021 / H221

 

is negative

R2 in relation to auto-tuning data,

 

 

 

within 1 to 1.2 times preset R2

 

 

 

 

 

 

When the speed deviation

Slowly decrease the motor constant

H021 / H221

 

is positive

R2 in relation to auto-tuning data,

 

 

 

within 0.8 to 1 times preset R2

 

 

 

 

 

Regeneration

When low frequency (a

Slowly increase the motor speed

H020 / H220

(status with a decel-

few Hz) torque is insuffi-

constant R1 in relation to auto-

 

erating torque)

cient

tuning data within 1 to 1.2 times R1

 

 

 

 

 

 

 

Slowly increase the motor constant

H023 / H223

 

 

IO in relation to auto-tuning data,

 

 

 

within 1 to 1.2 times preset IO

 

 

 

 

 

During acceleration

A sudden jerk at start of

Increase motor constant J slowly

H024 / H224

 

rotation

within 1 to 1.2 times the preset

 

 

 

constant

 

 

 

 

 

During deceleration

Unstable motor rotation

Decrease the speed response

H05, H205

 

 

 

 

 

 

Set motor constant J smaller than

H024, H224

 

 

the preset constant

 

 

 

 

 

During torque

Insufficient torque during

Set the overload restriction level

B021,

limiting

torque limit at low speed

lower than the torque limit level

B041 to B044

 

 

 

 

At low-frequency

Irregular rotation

Set motor constant J larger than the

H024, H244

operation

 

preset constant

 

 

 

 

 

When using a motor one frame size smaller than the inverter rating, the torque limit value (B041 to B044) is from the following formula and the value of the actual motor torque limit is calculated by the formula. Do not set a value in B041 to B044 that results in an actual torque greater than 200% or you risk motor failure.

For example, suppose you have a 0.75kW inverter and a 0.4kW motor. The torque limit setting value that is for T=200% is set (entered) as 106%, shown by the following formula:

Torque limit setting =

Actual-------------------------------------------------------------------------torque limit

⋅

Motor capacity-

=

200% ⋅ 0.4kW

=

106%

 

------------------------------

 

Inverter capacity

 

0.75kW