GE AF-650 GP - Internal Frequency Converter Operation Principles; General Overview of Operation; Description of Converter Operation

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A good start value for par. PI-06 Speed PID Lowpass Filter Time is 5 ms (lower encoder resolution calls for a higher filter value). Typically a Max Torque Ripple of 3

% is acceptable. For incremental encoders the Encoder Resolution is found in either par. E-80 Term 32/33 Pulses Per Revolution (24V HTL on standard drive) or

par. EC-11 Resolution (PPR) (5V TTL on OPCENC Encoder Option Module).

Generally the practical maximum limit of par. PI-02 Speed PID Proportional Gain is determined by the encoder resolution and the feedback filter time but other

factors in the application might limit the par. PI-02 Speed PID Proportional Gain to a lower value.

To minimize the overshoot, par. PI-03 Speed PID Integral Time could be set to approx. 2.5 s (varies with the application).

Par. PI-04 Speed PID Differentiation Time should be set to 0 until everything else is tuned. If necessary finish the tuning by experimenting with small increments of

this setting.

3.4.3 Process PID Control

The Process PID Control can be used to control application parameters that can be measured by a sensor (i.e. pressure, temperature, flow) and be affected by

the connected motor through a pump, fan or otherwise.

The table shows the control configurations where the Process Control is possible. When a Flux Vector motor control principle is used, take care also to tune the

Speed Control PID parameters. Refer to the section about the Control Structure to see where the Speed Control is active.

Par. H-40 Configuration Mode

Par. H-41 Motor Control Principle

U/f Advanced Vector Control Flux Sensorless Flux w/ enc. feedb

[3] Process N.A. Process Process & Speed Process & Speed

Note: The Process Control PID will work under the default parameter setting, but tuning the parameters is highly recommended to optimise the application control

performance. The two Flux motor control principles are specially dependant on proper Speed Control PID tuning (prior to tuning the Process Control PID) to yield

their full potential.

Illustration 3.1: Process PID Control diagram

AF-650 GP Design Guide