Hitachi SJ700-2 instruction manual

Chapter 4 Explanation of Functions

4.2.89 Optimum accel/decel operation function

Related code

The optimum accel/decel operation function eliminates the need A044/A244/A344: V/F characteristic curve for acceleration time and deceleration time settings for the motor selection, 1st/2nd/3rd motors operation by the inverter. Conventional inverters required you to A085: Operation mode selection

b021/b024: Overload restriction operation

adjust the acceleration and deceleration time according to the mode (1) (2)

status of the load. Based on fuzzy logic, this functionb022/b025: Overload restriction setting (1) (2) automatically adjusts the acceleration and deceleration time to

minimize the inverter performance. This function adjusts the acceleration time so that during acceleration, the inverter output current does not exceed the current level specified by the deceleration rate at overload restriction (when the overload restriction is enabled) or about 150% of the inverter's rated current (when the overload restriction is disabled). This function adjusts the deceleration time so that, during deceleration, the output current does not exceed about 150% of the inverter's rated current or the DC voltage in the inverter circuits does not exceed about 370 V (in the case of 200 V class models) or about 740 V (in the case of 400 V class models). Thus, this function automatically adjusts the acceleration and deceleration time appropriately on a real-time basis even when the motor load or the motor's moment of inertia changes.

Item	Function code	Data	Description
Operation mode selection	A085	00	Normal operation
		01	Energy-saving operation
		02	Fuzzy operation

Observe the following precautions and instructions when using this function:

Note 1: This function is not suited for machines that require fixed acceleration and deceleration times. This function varies the acceleration and deceleration time according to the changes in the load and the moment of inertia.

Note 2: If the inertial force produced in the machine becomes about 20 times as high as the motor shaft capacity, the inverter may trip. If this occurs, reduce the carrier frequency.

Note 3: Even when the inverter is driving the same motor, the actual acceleration/deceleration time always changes according to current fluctuation.

Note 4: The selection of the fuzzy acceleration/deceleration function is valid only when the control mode is a V/f characteristic control mode. When a sensorless vector control mode is selected, the selection of this function is ignored (normal operation is performed).

Note 5: When the fuzzy acceleration/deceleration function is enabled, the jogging operation differs from the normal jogging operation because of fuzzy acceleration.

Note 6: When the fuzzy acceleration/deceleration function is enabled, the deceleration time may be prolonged if the motor load exceeds the inverter's rated load.

Note 7: If the inverter repeats acceleration and deceleration often, the inverter may trip.

Note 8: Do not use the fuzzy acceleration/deceleration function when the internal regenerative braking circuit of the inverter or an external braking unit is used. In such cases, the braking resistor disables the inverter from stopping deceleration at the end of the deceleration time set by the fuzzy acceleration/deceleration function.

Note 9: When using the inverter for a motor of which the capacity is one class lower than that of the inverter, enable the overload restriction function and set the overload restriction level to 1.5 times as high as the rated current of the motor.

4 - 80