Siemens A1 Benutzerhandbuch
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Advanced Applications
MICROMASTER Applications Handbook
47
8 Advanced
Applications
Information
8.1
Using Closed Loop Control
8.1.1
What is Closed Loop Control?
Closed loop control is widely used in industrial applications to control a broad
variety of processes. Control engineering is a complex subject, but a simple
closed loop control uses a feedback signal from the process (such as temperature,
pressure, speed) a desired value from a set point (often set manually) and a
control system that compares the two and derives an error signal. The error signal
is then processed and used to control the inverter and motor (in this case) to try to
reduce the error.
variety of processes. Control engineering is a complex subject, but a simple
closed loop control uses a feedback signal from the process (such as temperature,
pressure, speed) a desired value from a set point (often set manually) and a
control system that compares the two and derives an error signal. The error signal
is then processed and used to control the inverter and motor (in this case) to try to
reduce the error.
The error signal processing can be very complex because of delays in the system.
The signal is usually processed using a Proportional, Integral and Differential (PID)
calculator, and these parameters can be adjusted to optimize the performance and
stability of the system. Once a system is set up and stable, very efficient and
accurate control can be achieved.
The signal is usually processed using a Proportional, Integral and Differential (PID)
calculator, and these parameters can be adjusted to optimize the performance and
stability of the system. Once a system is set up and stable, very efficient and
accurate control can be achieved.
8.1.2
Closed Loop Control using MICROMASTER MM420
A standard PI control loop function has been incorporated in the MICROMASTER
MM420, requiring only the connection of a suitable feedback transducer, and
configuration of parameters.
MM420, requiring only the connection of a suitable feedback transducer, and
configuration of parameters.
The control loop is not suitable for fast response control systems, but is ideal
where the controlled variable changes slowly, or where transient errors are not
critical (for example temperature or pressure control).
where the controlled variable changes slowly, or where transient errors are not
critical (for example temperature or pressure control).
Note.
The system is not intended specifically for speed control but can be used in this
way, provided fast response is not required. Where fast response and accuracy
are critical, external PID control systems or higher performance Siemens inverters
should be considered.
The system is not intended specifically for speed control but can be used in this
way, provided fast response is not required. Where fast response and accuracy
are critical, external PID control systems or higher performance Siemens inverters
should be considered.
The following information relates to MM420 parameters and closed loop
functionality.
functionality.