Efficiency in motor control

Maybe you should forget about your driven load when you first look at this problem - and evaluate the efficiency/complexity/charachteristics of the existing control network and how it was matched to the driven load - once this is known you can then look at improving the control network. Try looking at a software package called Simbol/look up a method called the de Souza method - a simple approach to the design of control networks - and modelling systems. you cannot change the efficiency of the load (if it already exists)- so start looking at the order of the control network once you understand how they were matched originally and how to improve that network.

You have a great website.

Can you be more specific about what info you want.

Just looking for ideas other than changing the motor to improve the overall efficiency of installations. Mark Empson

It will be very hard to improve the efficiency of the electric motors unless you want to spend the bucks to buy super energy-efficient motors. You will have to wait for a time-period payback, which can be good depending on what you are powering. Short term, in-house solutions include power factor correction, precision alignment of components and reducing vibration. Reduce or eliminate steam and air leaks. Infrared analysis and tribology can also benefit, depending on your particular application.

Any driving arrangement for a given load can be looked from three aspects to arrive at the optimal selection of an efficient system - Electrical (motor), electronic (control) and mechanical (transmission between the prime mover and the load). Truly speaking, there is no single system which can be called the best and a combination can be arrived at by studying the application (charecteristics and parameters of driven load)

Electrically, an optimal rating is to be arrived at depending on the load parameters. This would mean matching the prime mover characteristics with load characteristics. The result could be an AC / DC / Servo...

Electronically, the speeds or torque controlling methods (considering feedbacks and tolerences)have to be incorporated in the control scheme resulting in simple V/F, Vector control, analog/digital, servo...with application specific modules.

Mechanically, the losses in the transmissions have to be looked into. This is one aspect that people seem to overlook in most cases. A worm reduction gearbox is a highly inefficient gearbox for large reduction ratios (so much so that in many cases motors are selected more to cover the losses in the gearboxes than to drive the machine) and planetary / hellical gearboxes are much more efficient.

So, invariably it is the overlapping areas of engineering and economics that decide selection of the right combination and this overlapping area would shift from application to application.