Manufacturing News

Motor makers helping to drive down costs

The continuing emphasis on reducing production costs in the manufacturing industry means that greater attention is being given to the efficiency, flexibility and longevity of systems. Hartley Henderson reports.

Simple but effective IN response to industry’s focus on productivity, WEG Australia has developed CFW09 series of Selectable Vector Drives and the patented Optimal Flux Technology (OFT).

Product manager, Sean Richardson, says that when this technology is used on WEG’s full range of W21 series motors, which are now supplied to the Australian market under AS-NZS 1359.5-2004 (MEPS2), users will gain the benefits of a decrease in both installation and ongoing costs, as well as extending the motor’s service life.

“The software technology was developed by the relationship of motor flux or magnetism (V/f) and motor current (I) directly influencing motor torque. By modelling the relationship of the three across the entire motor load/speed condition, it was found that by optimising the flux, WEG could continuously minimise overall motor losses through the full motor speed range”, Richardson explained.

“Further to this, because motor iron losses are strongly dependant on the operating frequency, as the operation frequency is varied to a lower point, the iron losses are gradually reduced.

It was found that at low speed motor operation, by increasing the magnetic induction (flux density) of the motor, the torque can be kept constant with a reduction in motor current, which in turn causes reduced Joule losses (considering that major motor losses occur due to Joule effect on the windings).

“Thus, as the speed falls, it is possible to reduce the voltage proportionally less than the frequency, resulting in an optimal V/Hz ratio, which significantly improves the motor’s performance at low speeds with constant torque demands.

“The solution obtained was implemented within the CFW09 series and will also feature in the coming CFW11 series of drives,” said Richardson.

Payoff for the customer, he commented, is that OFT totally eliminates the need for forced cooling in WEG motors to speeds as low as 10Hz, even for constant torque loads with full torque demand.

Reducing energy costs Baldor’s MotiFlex e100 system offers a range of high performance multi-axis servo drives that can stand alone or run together on shared power.

The system integrates state-of-the-art DSP technology specifically designed for motor control, with a real-time Ethernet platform, modular construction and Baldor’s Mint motion control technology.

As Baldor managing director, Daniel Vera points out, energy generated by axes during braking or load driven operations is often wasted as heat in regeneration resisters, and the most cost effective solution is to allow other drives to consume the energy.

“Energy generated during deceleration is often discarded as heat in braking resistors, but by connecting the DC bus of drives within a system, this energy can be utilised to power other drives. Improved efficiency is the result, and often heating within the cabinet can be reduced by eliminating breaking resistors”, Vera said.

“Installation of an effective DC shared bus system means that the benefits of a simplified AC supply system design, and machine lifetime energy savings, can apply to a greater number of applications.

“All our MotiFlex drives have the ability to share DC energy as standard and, more importantly, are able to provide power to other drives,” said Vera. In other words, each MotiFlex drive can convert power from the AC supply to share with other drives.

According to Baldor, additional cost savings can also be achieved because MotiFlex shared systems reduce the number of line side components such as contactors, circuit breakers, fuses and cabling, which in turn means improved reliability through reduction of components and design complexity.

Energy saving inverters Grant Millard, product manager at Mitsubishi Electric, sees energy saving through the use of inverters as a trend within industry at the moment.

“Our new F700 series fan and pump inverters have what we call Optimised Excitation Control (OEC) aimed at increasing energy savings above what can be achieved with standard inverters.

The fundamental principle of energy savings by using an inverter is to eliminate wasted power consumption by minimising the motor output while still achieving the desired speed and torque,” Millard explained.

“The FR-F740/F746 inverters achieve massive power savings, particularly in the crucial low speed range, and the braking and acceleration phases.

“At a frequency of 35Hz, for example, the inverter achieves a saving of 57 per cent over conventional solutions. Additional savings of 10 per cent are obtainable via our OEC technology, which ensures that the optimum flux is applied to the motor at all times.

“In relation to pump systems, the FR-F740/F746 inverters can automatically integrate up to four motors in a pump system,” said Millard.

In this application, one motor is frequency-controlled by the FR-F740/746 whilst the others are automatically switched in to or out of the network in stages. The inverters are fitted with two serial ports as standard for integration in automation networks.

Baldor, 02 9674 5455.

Mitsubishi Electric, 02 9684 7316.

WEG, 03 9765 4600.

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