Topics: Improve induction motor efficiency
on Automation Technologies
Improve induction motor efficiency
my final year project is efficiency improvement of an induction motor. so which parameters change for improve efficiency of induction motor????????????
09-03-2013 09:12 PM
Improving efficiency means reducing losses. You can reduce losses by
1. reducing stator resistance - usually leads to increased size
2. reducing iron losses - by using better lamination material
3. reducing rotor losses - by using copper instead of aluminum for the squirrel cage
09-03-2013 09:13 PM
Look at the loss distribution in your motor. The biggest impact will be to reduce the largest amount of losses (either stator, rotor, iron, or friction and windage) by the largest amount.
However - there are always trades to be made. Fixing one aspect (efficiency) may result in undesirable performance elsewhere ... such as starting torque, breakdown torque, inrush current, and/or power factor.
09-03-2013 09:14 PM
you can add capacitors in parallel with the motor to reduce current, power loss, and improve power factor at motor
09-03-2013 09:15 PM
For quite a number of years, the stray load losses have gained sufficient importance. Traditionally assumed to be 0.5 % of the input power, many standards have made it a part of proof testing. This single item has raised a large number of non technical arguments. In mid 1990s, an amendment to the IEC documents was under discussions. Leaving aside the small ratings, where the output and input power are measured, the real problem was in larger ratings. Till that time, any setup to test the value of stray losses would have a very high cost, and still be unreliable.
Chris, do you have an Idea of the current status.
09-03-2013 09:15 PM
Decreasing rotor and stator resistance can be accomplished by using magnetic wire of larger circular mils for your windings, which does lead to increased size and torque given an equal number of turns. You can also increase efficiency by deflecting flux warpage back into the motor by the use of rings of Stargate magnets surrounding the motor housings and or by just increasing the webers per square meter of magnetic field strength (using rare earth magnets) for any permanent magnet stator fields. As well as narrowing the distance between the rotor and stator surfaces.
09-03-2013 09:17 PM
I agree with your views. Some times my comments are based on large ratings of 500 KW and above. I am not very familiar with round wire wound machines. I know that people were trying to develop very thin coating enamels to increase copper in the stator. In larger machines, we have formed coils, using rectangular sections. The insulation on occasions is more than minimum as it has to meet the existing manufacturing practices and installed facilities. It is certain that losses can be reduced in any design by using better or more material, i.e cost. In higher capacities, due to smaller size of orders, the cost effect is much more. 20 years back a young man attempted to increase the efficiency through this process and lost his job. Now he is a consultant. Today the NC slot punching, die cast copper, magnetic wedges make it more convenient but the size of order quick deliveries are hurdles . Then there is a difference in same ratings of different makes, depending again on the level of their operations.
Here I wish to make a strong case for improving the Quality of Power, at least in India. If the Voltage and frequency variations are going to be uncontrolled, putting pressure on the designers to improve efficiency would be a bad economic and technical decision. You are not alone in the market and have to depend on material supplies (SUPPLIERS). Surprisingly the legislation on efficiency improvement was pursued by the Copper suppliers and the Electrical Sheet Steel Industry. In my life time, I have seen two phases. Around 1980, we used to go around telling customers to take Aluminum in the Stator Windings due to scarce copper. Another 20 years, the copper supplies improved, the same persons are not favoring Aluminum. Die Cast copper rotors are a definite technology improvement, provided our starting specifications are made more flexible. After all the systems are more robust now.
09-03-2013 09:18 PM
THIS MESSAGE IS FOR CHIRAG, who probably be feeling left out in our discussions. Chirag I can share with you that this is the best project you can take. It will give you an in-depth knowledge od the effect of designers on the sale ability of your product and vice versa also. Pleas go ahead with your project in full earnest. If in difficulty at any time ask me. Which City are you placed in?
My personal experience was similar. 52 years back, my teacher, Dr C S Jha , encouraged me to take the project on measurement of Stray Load Losses in large machines. In smaller machines, problem of measuring was less but the need was to control the technology. I could hardly finish my literature survey. At the end I resigned to the fate that the name Stray Loss was most suiting for this entity. Even today I remember the names of some authors. But this little extra knowledge in my brain helped me on many occasions. The peak was at IEC level, when many advanced manufacturers were talking of measuring Stray Losses. I was the only one to demand that the lower scale or developing countries should be told the Exact procedure to be followed and the sources from where the necessary equipment will come. I knew it was difficult and costly to setup testing for each individual rating, speed and slot combination. It got me the right results, which I am not well aware as I had to leave the Chairmanship of the sectional committee of BIS, under pressure from the material suppliers.
09-03-2013 09:20 PM
Yes. stray load losses are very significant. iEEE has a method as well as the 600034 standards.
Each of the losses, stator coper, rotor copper, iron, high frequency air gap, stray and friction and windage losses have to be reduced to increase efficiency. Some steels are better at small motors and some are at larger motors. Slot shapes play important role. Flux passing through shaft can also contribute, so also bearing currents. Each of these has to be studied and reduced to improve efficiency.
I am also aware that Chirag is more interested in improving the efficiency of the mono bloc water pumps used in agriculture. Here not only the motor efficiency is to be improved but also the pump efficiency by reducing the hydraulic losses in pumps.