Hitachi SJ300-037HFE 사용자 설명서

Setting Motor Constants for Vector Control

Oper

ations

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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.

CAUTION: You must use a carrier frequency of more than 2.1kHz. The inverter cannot 
operate in vector control mode at less than 2.1 kHz carrier frequency.

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:

Powered running

When the speed deviation 
is negative

Slowly increase the motor constant 
R2 in relation to auto-tuning data, 
within 1 to 1.2 times preset R2

H021 / H221

When the speed deviation 
is positive

Slowly decrease the motor constant 
R2 in relation to auto-tuning data, 
within 0.8 to 1 times preset R2

H021 / H221

Regeneration
(status with a decel-
erating torque)

When low frequency (a 
few Hz) torque is insuffi-
cient

Slowly increase the motor speed 
constant R1 in relation to auto-
tuning data within 1 to 1.2 times R1

H020 / H220

Slowly increase the motor constant 
IO in relation to auto-tuning data, 
within 1 to 1.2 times preset IO

H023 / H223

During acceleration

A sudden jerk at start of 
rotation

Increase motor constant J slowly 
within 1 to 1.2 times the preset 
constant

H024 / H224

During deceleration

Unstable motor rotation

Decrease the speed response

H05, H205

Set motor constant J smaller than 
the preset constant

H024, H224

During torque 
limiting

Insufficient torque during 
torque limit at low speed

Set the overload restriction level 
lower than the torque limit level

B021,

B041 to B044

At low-frequency 
operation

Irregular rotation

Set motor constant J larger than the 
preset constant

H024, H244

Torque limit setting

Actual torque limit

Motor capacity

×

Inverter capacity

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200%

0.4kW

×

0.75kW

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106%

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