Toshiba instruction manual Control modes of the VF-A7 inverter, Sensor vector control Optional

3.1Control modes of the VF-A7 inverter

[Speed control mode] : The motor runs at the speed specified by a frequency command.

(1) V/f control - V/f constant (constant torque characteristic) ... [default setting]

For loads, such as belt conveyors and cranes, that require, even in low speed ranges, the same torque as that produced at their respective rated speeds.

(2) V/f control - Square reduction torque

For loads, such as fans, pumps and blowers, the torque of which are proportional to the squares of their respective rotating speeds.

(3) Automatic torque boost mode.

In this mode, the inverter automatically adjusts the supply voltage to ensure that the motor produces constant torque in any speed range.

(4) Sensor-less vector control mode,

In this mode, the inverter controls the motor so that it produces sufficiently large torque even in an extremely low speed range and it keeps its rotating speed constant even if the load torque fluctuates. This mode of operation is best suited to transportation, lifting and winding equipment.

(5) Automatic energy-saving mode.

In this mode, the inverter monitors the output voltage and passes an output current commensurate with the load. This mode of operation is used in conjunction with the above mode (3) or (4).

[Torque control mode] : The motor torque is controlled by torque command signals. The motor's rotating speed is determined by the relationship between the load torque and the torque produced by the motor.

■Sensor vector control (Optional)

When combined with a sensor-equipped motor, the inverter controls the motor with a higher accuracy.

[Speed control mode] : The motor's rotating speed is controlled with a higher accuracy, even in low speed ranges, by feedback signals.

[Torque control mode] : The motor torque can be controlled in this mode. The motor speed is determined by the relation ship between the load torque and the motor torque. The accuracy in controlling regenerative torque and power-running torque at extremely low speeds is improved by feedback signals.

[Position command mode] : Positioning control is carried out by means of pulses.

■Pre-operation check the following check again before starting operation

Pre-operation check the following check again before starting operation.

1)Are all wires and cables connected correctly?

2)Does the supply voltage agree with the rated input voltage?

C-2