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Open-loop drives handle PM or induction motors

12 December, 2008

SPS logoFor the first time at the recent SPS/IPC/Drives show, the Japanese drive-maker Yaskawa had its own stand, separate from that of its marketing partner, Omron. The highlight of the stand was a new generation of open- or closed-loop vector inverter drives suitable not only for standard asynchronous motors, but also for permanent magnet (PM) motors with either interior or surface-mounted magnets.

Yaskawa A1000 drive

The A1000 drives – which Yaskawa is building for the European market at its Scottish plant – replace the earlier Varispeed F7 series, offering improved performance while occupying up to 55% less space. The new drives are also quieter than the earlier drives, contain fewer components and, in some cases, allow a lower-rated, smaller drive to run a motor.

The drives cover ratings from 0.4–110kW (200V) and 0.4–630kW (400V). They can deliver 200% of rated torque at 0Hz for PM motors operating in open- or closed-loop, and for induction motors operating in closed-loop. For induction motors operating in open-loop, 200% torque can be achieved at 0.3Hz.

When used with the drives, PM motors can perform positioning control without feedback. Electrical saliency in the motors is used to detect speed, direction and rotor position. The positioning can be achieved without a PLC using Yaskawa’s DriveWorksEZ visual programming software.

According to Yaskawa, using the A1000 to drive a PM motor can result in energy costs that are up to 10% lower than when using it with an induction motor. In some installations, PM motors could therefore be more cost-effective than induction motors, despite their higher initial cost.

The A1000 incorporates a Safe Torque Off function and has a safety monitoring facility. It uses new auto-tuning algorithms to adapt to changing motor characteristics and supports a variety of fieldbuses.

♦  Yaskawa was also showing an IP66-protected version of its V1000 inverter in single-phase ratings from 0.1–4kW (230V), an three-phase ratings from 0.1–18.5kW (200V) and 0.2–18.5kW (400V). The washdown-resistant drives use current vector control for high starting torque and optimised control of speed torque. They include EMC filters and offer dual-channel safety circuits.

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