Speed loop ratio gain | Toshiba E6580772 instruction

E6580772③

(1)Number of PG input pulse (f367) is the number of encoder output pulses per one motor rotation.

(2)For selection of number of PG input phases (f368), set as follows:

If the encoder pulse is single-phase: 1

If the encoder pulse is two-phase: 2 (Phase A and Phase B or Phase A and Pulse B + Z origin signal) When the settings for the above (1) and (2) are wrong, the motor rotation will become abnormal.

(3) Adjustment methods for current control proportional gain (f374) and current control integral gain (f375):

These need to be adjusted when it is necessary to fine-tune torque responses. (Normally, standard setting should be used.) For details of adjustment, refer to the inverter manual.

(4) Adjustment method for speed loop proportional gain (f376) and speed loop integral gain (f377)

The principle of the feedback control is a proportional action. This action produces output in proportion to the speed deviation. It is a simple mechanism but it takes some time until the speed becomes stable. Proportional action merely produces some offset values. (The speed deviation will not be eliminated completely with reference to the command frequency.)

In order to eliminate the offset, integration action is effective where the output is calculated by the accumulation of past deviations (from start of operation until now) and added to the proportional action.

<Speed loop ratio gain>

Adjustments are necessary in accordance with the inverter capacity and load inertia ratio. Set the ratio referring the formulae below as the rule of thumb.

Speed loop ratio gain = (50 + A x Pw) x J 0.12

A	: Coefficient by number of motor poles (2 poles: 1.8 4 poles: 2.0 6 poles: 2.2)
Pw	: Inverter capacity (Example: in case of 3.7kW unit Pw=3.7)

J: Load inertia/TOSHIBA standard motor inertia (Example: In case of inertia ratio being 4, J = 4)

<Speed loop integration gain>

Standard setting at shipment should be used usually.

In case fine-tuning of speed response is necessary, adjust parameters by the following procedure.

Measurement device needed for adjustment: Waveform measurement device such as an oscilloscope.

①Connect the probe of the measurement device to the analog monitor output terminal of the inverter (between the FM terminal and CC terminal).

Set FM terminal output to Speed Feedback (real-time value). (Refer to 3.2.5 Monitoring method for feedback amount.)

② Set the acceleration time to minimum, so that there will be no over-current stall.(c blinking)

③Set the operation command mode selection (cmod) and speed setting mode selection (fmod) to panel input effective. ( cmod = ”1”, fmod = “5”)

④Set the speed setting to about 10Hz and press (RUN) key to measure the speed response waveform at operation start. Press (STOP) key to stop operation.

⑤In order to improve the speed response, gradually make the speed ratio gain greater

(f376) and repeat above④ operation and adjust to immediately prior to motor oscillation.

⑥Adjust the speed loop integral gain (f377). Repeat the operation in④ above and adjust the parameter so that the speed deviation is contained at expected response time.

This concludes the speed loop gain setting.