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Drive amplifier

4-quadrant operation of asynchronous motors

The drive functions of the drive amplifier SD2S by Sieb & Meyer (Germany) permit the 4-quadrant operation of high-speed asynchronous motors with encoder feedback. For this application the amplifier features a high-dynamic speed control and a safe limitation of the torque.

The actuator can carry out operations with or without encoder (Photo: Sieb & Meyer)

IN THIS APPLICATION SCENARIO, TORQUE LIMITATION ALLOWS the user to test different loads at a constant speed in test stations. Another opportunity for machine tools with asynchronous motors is using high-speed manufacturing spindles as dynamic positioning axis via the CNC. The positioning accuracy depends on the encoder resolution, which is limited by the motor speed. A SIN/COS encoder or an encoder with TTL signal can be used as an encoder system for this application. The higher-ranking CNC conducts the position control. Connection with a higher-ranking control can be established in various ways: interfaces for analog reference value signals (+/-10 V), digital I/Os, EIA-232 and USB as well as CAN are available. In addition, a Servolink interface or an Anybus adapter permits the connection of Profibus and Ethercat.

Synchronous and asynchronous motors with speeds up to 480 000 rpm can be driven by the drive amplifier, especially in respect of a low motor heating in high-turning motors with small rotor volume. Depending on the application, operations can be carried out with or without encoder. For operation with an encoder the amplifier offers the possibility to evaluate the common encoder systems existing on the market. The functional spectrum of the product includes a high-dynamic drive amplifier for synchronous servomotors with encoder feedback as well as a frequency converter for sensorless operation of high-speed asynchronous and synchronous motors.

The product offers two drive functions. For asynchronous motors the drive function V/f-PWM is used. By means of the V/f characteristic curve, the user can carry out the graphically aided parameterization of the motor. The SVC drive function (Sensorless Vector Control) is provided for synchronous motors and is based on the equivalent circuit diagram usually found in the motor data sheet. This function allows the 4-quadrant operation of high-speed synchronous motors and generators so that the product can be used for applications such as turbo blowers or turbines for utilization of process energy. The integrated technology functions for gap elimination are advantageous, if an external acoustic emission evaluation is not possible for some reasons. The feature of saving up to 64 motor parameter sets in the drives enables a variable operation with different motors. The number of parameter sets can be encoded via the digital inputs or alternatively via the provided data interfaces.

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Sieb & Meyer