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Big drive technologies migrate down to micro and compact level

21 April, 2008

New families of entry-level and mid-range frequency inverter drives made their European debuts on Mitsubishi Electric’s stand at the recent Hannover Fair. The FR-D700 micro inverter and FR-E700 compact inverter ranges (shown below) incorporate control technologies previously available only on larger drives.

Mitsubishi inverters

The micro inverters offer a choice between V/f or sensorless flux vector control technology with slip compensation. They come in two series spanning ratings from 0.1–2.2kW and 0.4–15kW, and in versions for single- or three-phase operation on power supplies from 170–264V and 325–528V (50 or 60Hz).

Up to 32 of the micro drives can be linked in a low-cost serial network via RS-485 ports that support the Modbus RTU protocol. A newly-developed communications protocol supports transmission of user-definable data records to a controller, and the communications are said to be four times faster than Mitsubishi’s previous drives of this type.

Built-in functions include "secure stop", to prevent unexpected motor starts in accordance with ISO 13849-1 Cat 3, as well as dancer and traverse functions for winding operations. Models above 0.4kW have built-in braking transistors. The drives are backwardly compatible with the earlier FR-S500 models and have the same installation dimensions. They will be about 10% cheaper than their predecessors.

The larger FR-E700 drives succeed the earlier FR-E00 series and are available with output ratings from 0.4–15kW. They are said to offer improved speed and torque control facilities and flexible expansion options, creating the basis for economical, customised drives. The enhanced functions are expected to open up new application areas for compact frequency converters.

The drives offer a choice between V/f, flux vector and Mitsubishi’s "advanced magnetic flux vector control", which allows precision operation without tachometer feedback.

Removable terminal blocks and expansion modules allow the drives to be configured individually and integrated into networks. As with the micro drives, the compact models are compatible with their predecessors.