Chapter 6 Applied Instructions D K : Derivative gain I K : Integral gain Suggestion: 1. Owing to the fact that the instruction PID can be used in a lot of controlled environments, users have to choose the control function appropriately. For example, to prevent the improper control from occurring, PID_MODE can not be used in the motor controlled environment when it is set to 1. 2. When users tune the parameters K P , K I , and K D ( PID_MODE is set to 0 or 2), they have to tune the K P first (according to the experience), and then set set the K I and the K D to 0. When users can handle the control, they can increase the K I and the K D , as illustrated in example four below.
When the K P is 100, it means that the proportional gain is 100%. That is, the error value is increased by a factor of one. When the proportional gain is less than 100%, the error value is decreased. When th proportional gain is larger than 100%, the error value is increased. 3. To prevent the parameters which have been tuned automatically from disappearing after a power cut, users have to store the parameters in the latched data registers when is PID_MODE set to 1. The parameters which have been tuned automatically are not necessarily suitable for every controlled environment. Therefore, users can modify the parameters which have been tuned automatically.
However, it is suggested that users only modify the K I or the K D . 4. The instruction should be used with many parameters. To prevent the improper control from occurring, please do not set the parameters randomly. Example 1: The use of the instruction PID in the position control ( PID_MODE is set to 0 or 2.) Position command (SV) Example 2: The instruction PID is used with the AC motor drives. ( PID_MODE is set to 0 or 2.) Speed command (S) Acceleration/Deceleration command (SV) Actual acceleration/ deceleration (PV=S-P) Example 3:
The use of the instruction PID in the temperature control ( PID_MODE is set to 0 or 2.) 6-172 MV PID Plant Encoder PV PID MV Plant Encoder + S+MV AC motor drives + Acceleration/Deceleration output (MV) Speed PID detector (P) AC motor drives PID Speed detector (P)