VARIABLE FREQUENCY DRIVES

This equipment consists of a driver controlled by a PLC through a Profibus Network managed through an Ethernet network. Any registered user will be able to act on the drive (starting, stopping, specifying the acceleration time, reversing the direction of engine rotation, etc.). A configuration is implemented which allows to control a frequency inverter through a PLC receiving instructions, through the Internet, from a remote interface. The inverter has been configured so that the control of the drive is programmed in the PLC and a Profibus network is used for communication. There is also an Ethernet network between the PLC and the remote interface. The motor control system consists of two well defined parts: the PLC and the frequency inverter.

1. PLC: Communicates with the remote interface through Ethernet and translates the instructions from the interface to the drive via Profibus.
2. DRIVE: The drive receives instructions from the PLC through Profibus and actuates the motor to process the operations indicated by the remote interface.

The possible operations to process by remote interface are:

1. Start/Stop the motor.
2. Change turning direction of the motor.
3. Increase/Decrease turning speed of the motor.
4. Time selection of the ramp.
5. Enable/Disable the injection of continuous current to act as a charge.
6. The percentage of continuous current injected (resistive torque applied to the motor).

The SUPPRESS Research Group (Supervision, Control and Automation) of the University of León designed, developed and implemented this system.

1. PLC S7-300

It consists of a compact CPU with MPI, 24/16 digital I/O, 5/2 analog I/O, 4 high speed counters (60KHz), Profibus DP port and 48 kB of working memory.

2. CP 343-1 MODULE 

Siemens Communication module. Industrial Ethernet connection 10/100 Mbits/s. Auto-sensing. An IP address can be configured remotely to access to the CPU of the PLC. The FTP server can be used to host web pages.

3. SIEMENS VARIATOR MICROMASTER 440 

Frequency inverter with a 1024 pulse encoder, a Profibus card module and a card module for the encoder. It has two main control modes, a vector control and a voltage/frequency control.

4. SIEMENS MOTOR 

The motor is built into the drive. It is a Siemens motor with the following characteristics, Nominal Voltage: 230/400 V. Power: 0.37 kW. Turning speed: 1370 r.p.m.

5. PROFIBUS NETWORK

The communication between the PLC and the MM440 is done via a Profibus network at a speed of 1.5 Mbit/s (Vmax: 12 Mbit/s).

6. ETHERNET NETWORK

The communication between the PLC and the remote user interface is done through an Ethernet network.

• Simulations  
• Remote Access