3. Operating InformationEnglish

3.8 Closed Loop Control

Closed loop control is only possible when an OPm2 or a serial link is connected to the CombiDrive

® .

3.8.1 General Description

The CombiDrive® provides a Proportional/Integral (PI) control function for closed loop control (see Figure 7). PI control is ideal for temperature or pressure control, or other applications where the controlled variable changes slowly or where transient errors are not critical. This control loop is not suitable for use in systems where fast response times are required.

Note: The closed loop function is not designed for speed control, but can be used for this provided that fast response times are not required.

When closed loop PI control is enabled (P201 = 002), all setpoints are calibrated between zero and 100%, i.e. a setpoint of 50.0 = 50%. This allows general purpose control of any process variable that is actuated by motor speed and for which a suitable transducer is available.

Setpoint

 

 

 

 

 

 

 

 

 

 

Acceleration/

 

 

LowPass

 

 

P

Deceleration

 

 

Filter

Scaling

+

Ramp

Motor

 

 

 

 

P202

 

M

Process

 

 

–

 

 

e.g. fan

 

 

 

 

 

 

 

 

 

 

 

P206

P211, P212

 

I

P002, P003

Feedback

 

 

 

 

(e.g. duct pressure)

Feedback

 

 

P203, P207

 

 

Transducer

 

 

 

 

 

Sample

 

 

 

 

 

 

 

 

 

 

 

Rate

 

 

 

 

 

P208

P205

 

 

 

 

 

 

 

Closed Loop Mode Disabled

 

 

 

 

 

 

 

 

 

 

 

 

P201 = 000

 

 

 

 

 

 

Closed Loop Mode Enabled

 

 

Feedback

 

 

 

 

 

Monitor

 

 

 

P201 = 002

P210

 

 

 

 

Figure 7: Closed Loop Control

3.8.2 Hardware Setup

Connect the signal wire from the external feedback transducer to control terminal 10. Set jumper JP303 if voltage input type is required (default) or set JP302 if current input type is required.

15 V dc power for the feedback transducer can be supplied from control terminal 8.

3.8.3 Parameter Settings

Closed loop control cannot be used unless P201 is first set to 001. Most of the parameters associated with closed loop control are shown in Figure 7. Other parameters which are also associated with closed loop control are as follows:

P001 (value = 007)P061 (value = 012 or 013)P210P220

Descriptions of all closed loop control parameters are provided in section 4. For further detailed information about PI operation, refer to the Siemens DA 64 Catalogue.

© STÖBER plc 1997

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05.02.01