Mitsubishi smart drives combine fine control and energy savings

It is widely recognised that when correctly applied to motors, smart variable speed drives like Mitsubishi FR-A800 Series make significant energy savings, and improve machine control and performance. This has been one of the main drivers for their adoption.

When reducing motor speed, you save energy proportional to the square or cube law depending on the application of the reduction. Many application, such as HVAC may never need full speed and power, so a drive can be adjusted manually or automatically to a lower level to optimise energy savings without affecting the performance of the system. Other applications may require full speed operation for part of the time of cycle, then reducing to half or a quarter speed.

A VSD can be set to provide this so provide a variable output, either based on a clock or timer. Or in response to real-time sensor measurements. Some applications may be required to stop the motor altogether for part of a cycle, and this is easily controlled by the drive. Stopping or slowing a motor down can also provide another form of energy saving.

Regenerative braking.

Many applications have deceleration stages in their duty cycle. That is when kinetic energy is removed from the moving motor load. Traditionally this energy is simply lost through braking resistors or mechanical brake. However, a regenerative drive can capture this energy and   feed it back into the mains, leading to further significant energy savings. Regeneration is also possible if a load is lowered, if a conveyor runs downhill, for example as in an escalator.

It is notable that high performance smart drives enhance an industrial motor’s dynamic performance towards servo levels of performance, making it suitable for axes where extra precision is required.

More than energy saving

Discrete parts manufacturing, process control and building management are becoming more intelligent, and all parts of the system communicate with one another to optimise overall performance.  The ability of smart VSDs to accurately control the speed of motors also makes them an important part of machine and automation control. To support this, a wide range of open and proprietary communications networking is available, ranging from Industrial Ethernet to BMS.

As an example, when drives are integrated with servos over specialist networks such as Mitsubishi Electric’s SSCNet motion network. While the servos control the precision axes in the system, they can communicate with the industrial motors on the general axes to improve overall systems performance.

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