3–14

“A” Group: Standard Functions

parameters A_42 and A_43. The manual boost is calculated as an addition to the standard straight V/f line (constant torque curve).

NOTE: Manual torque boost is not operational when sensorless vector control is in use.

Be aware that running the motor at a low speed for a long time can cause motor overheating. This is particularly true when manual torque boost is ON, or if the motor relies on a built-in fan for cooling.

NOTE: Manual torque boost applies only to constant torque (A_44=00) and variable torque (A_44=01) V/f control.

Voltage Gain – Using parameter A_45 you can modify the voltage gain of the inverter (see graph at right). This is specified as a percentage of the full scale setting (Automatic Voltage

V 100%

Voltage Gain

A 45

Regulation) AVR level in parameter F_03. The gain can be set from 50% to 100%. It should be adjusted in accordance with the motor specifi- cations.

50%

0

Hz

Configuring

Drive Parameters

Sensorless Vector Control (SLV) – This advanced torque control algorithm improves torque performance at very low speeds—down to 0.5 Hz. Set parameter A_44=02 to select SLV operation. The SLV algorithm must be tuned to match the characteristics of the particular motor connected to your inverter. Simply using the default motor parameters in the inverter will not work satisfactorily for these control methods. Chapter 4 discusses motor/inverter size selection and how to set the motor parameters either manually or by using the built-in auto-tuning. Before using the sensorless vector control methods, please refer to “Auto-tuning for Sensorless Vector Control” on page 4–35.

NOTE: When the inverter is in SLV (sensorless vector) mode, use B_83 to set the carrier frequency greater than 2.1 kHz for proper operation.

NOTE: You must disable sensorless vector operation when two or more motors are connected (parallel operation) to the inverter.