Assignment 1: Literature and Web-based Review for More Electric Systems

The Motivation Behind More Electric Systems

The aim of Assignment 1 is to develop background knowledge and arguments for the move by many industrial sectors to “More Electric” systems. Examples of these sectors are:-

(i) Automotive – hybrid and electric vehicles

(ii) Rail – hybrid and electric trains

(iii) Marine – hybrid and electric ships

(iv) Aerospace – electro-hydrostatic and electro-mechanical actuation systems, and

(v) Manufacturing industry – replacement of hydraulic, pneumatic and other systems for industrial processes with electro-mechanical systems or systems with more electro-something!

For Assignment 1, I would like you to do a literature and web based review searching for sources that discuss the “More Electric” theme. Choose one or more of the options (i) to (v) above and study typical systems that may have been established for many years and then study the More Electric alternative. It is quite easy to find information for the automotive option (i), so have a look at this in the first instance and then choose at least one other option and see what information you can resource. What I want you to consider and discuss in a short report is why these industrial sectors are moving to these newer solutions, what are the motivating factors – try to identify them.

Take a couple of examples (i.e. 2) and study the system components, what are they, how are they interconnected, how are they controlled etc.

Can you identify the main component specifications? Put together a short report of 1-2 pages maximum including figures, tables etc. to discuss you findings.

For the “more electric” aircraft theme I have added the following references as examples:-

1. Induction Machine Literature Review.

Use on-line materials, text books etc., to study the basics of induction machine operation. Study machine general structure, applications, advantages and disadvantages etc.

2. Induction Machine Steady-state Model.

The Excel spreadsheet provided solves the approximate equivalent circuit of the induction machine. In lectures we will discuss the induction machine per phase, approximate equivalent circuit model and study the tests required to develop the model and determine parameter values.

3. Model Study

Use the approximate equivalent circuit model to investigate how torque varies with (i) supply voltage, (ii) external rotor resistance, and (iii) voltage and frequency varied together.

3.1. Vary the per unit phase voltage from 1.0 to 0.1 in 0.1 per unit steps. For each step capture the torque-speed data and plot the data sets on one graph.

3.2. For each voltage, note the peak torque. Then plot a graph of peak torque versus RMS phase voltage – what is the relationship?

3.3. Vary the rotor resistance from 1.0 to 10 per unit in 1.0 per unit steps, then in 10 per unit steps from 10 to 40 per unit. For each step capture the torque-speed data and plot the data sets on one graph.

3.4. For each value of rotor resistance, note the (a) torque at zero speed, (b) the peak torque,and

(c) the highest speed at which the mechanical output power is 2.2kW. Present the data in

Tables or graphically as best illustrates the results.

3.5. Reduce the frequency from 1.0 per unit to 0.25 per unit in 0.25 per unit steps. For each step capture the torque-speed data and plot the data sets on one graph. Comment on the results, do they look sensible.

3.6. Reduce both the voltage and frequency from 1.0 per unit to 0.25 per unit in 0.25 per unit steps. For each step capture the torque-speed data and plot the data sets on one graph. Comment on the results, do they look sensible.

3.7. Reduce the frequency from 1.0 per unit to 0.25 per unit in 0.25 per unit steps. For each step adjust the per unit voltage until the peak torque is maintained at the peak torque value produced at 1.0 per unit frequency. Comment on the results, do they look sensible. These results show how the torque versus variable speed characteristic varies when simple scalar (V/f + Vboost) control is implemented.