This module is designed to provide students with an introduction to modern electrical drive systems. An electrical drive system converts electrical energy into mechanical work (and vice-versa) and comprises an electrical power source (such as the electrical grid or a battery), an electrical machine (such as a motor or generator), and in modern systems, a power electronic converter that mediates the power flow between source and load. A drive system normally includes a mechanical system (e.g. gearbox) that connects the electrical machine to a mechanical load and a closed loop control system that improves system precision and repeatability. 

Students will have previously studied electrical machines, power electronics and automatic control and will have a basic understanding of simple mechanical systems. This module brings together these different subjects, reinforcing and extending them by placing them in the context of a whole electrical drive system design process. 

LO1. Illustrate the structure of a general electrical drive system by means of a block diagram and list examples of the contents of each block 

LO2. Describe the DC brushed servo machine, permanent magnet AC servo and the universal motor along with the common circuits used provide speed and torque control, and give examples of applications to which each type is suited 

LO3. Illustrate the principal categories of variable-speed induction machine drives: constant frequency/variable voltage (CFVV); variable frequency/variable voltage (VFVV); pole-changing; slip energy recovery and injection; external rotor resistance variation

LO4. Derive the differential equation representing motor temperature rise as a function of time, when the load on the motor varies in a specified manner and the motor is represented by a simple lumped thermal model with Newtonian cooling 

LO5. Analyse and draw nested torque-acceleration-speed-position control loops and understand why such systems are commonly used in industrial drive systems. Know how torque, speed and position can be measured for providing feedback 

LO6. Explain the design process, trade-offs and constraints encountered when tailoring an electrical drive system for a particular application, with a special emphasis on electric vehicles 

The module will be delivered in the Spring semester through a blend of on-campus face-to-face classes (tutorials, feedback sessions), online learning material, and guided study. 

The lecture series includes a guided design exercise focussing on electric vehicle drivetrains. This exercise spans two double sessions and begins with the development of a simplified specification for a consumer Battery Electric Vehicle (BEV). The exercise proceeds to a conceptual drive system design stage and concludes with a comparison with commercial vehicle offerings. 

In addition to developing your problem solving, critical thinking, reflection and communication skills, the module will support you in developing skills in: 

• Analysis of simple linear and rotating mechanical systems 

• Extraction and use of simplified models DC brushed servo machine, permanent magnet AC servo, universal motor and induction machines 

• Automatic control theory as applied to simple linear drive systems 

• Designing to a specification 

1. Selection of different electrical machines to suit specific tasks 

2. Selection of a power electronic converter for providing speed and/or torque control 

3. Selection of a suitable control structure to give torque/acceleration/speed/position control 

4. Selection of appropriate sensors to measure torque/speed/position 

• Use of the induction machine equivalent circuit to analyse methods of speed control 

• Simple thermal modelling to predict temperature rise of a machine subject to various loading scenarios 

There is only one summative assessment which will be an individual Exam (100%) (LO 1-6).   

Graduate attributes of Problem solving, Critical Thinking, Reflection and Communication are developed here  

Feedback on the summative exam will be provided in the form of generic cohort feedback and your individual grade  

Formative opportunities will be provided through class quizzes, guided design exercise, tutorials, and a mock exam (LO 1-6).   

Feedback on formative work will be verbal in class 

THE OPPORTUNITY FOR REASSESSMENT IN THIS MODULE:   

There is a potential for re-assessment in this module which will result in a 100% written assessment during the August Resit period (LO 1-6).    

Opportunities for re-assessment is only permitted provided you have not failed more credit than in the resit rule adopted by your programme.  If the amount of credit you have failed is more than permitted by the relevant resit rule, you may be permitted to repeat study if you are within the threshold set for the Repeat rule adopted by your programme.  You will be notified of your eligibility to resit/repeat any modules after the Examining Board in the Summer period.   

All resit assessments will be held in the Resit Examination period, prior to the start of the following academic session.  

• Drive systems: Structures and essential elements, electromechanical relations and their application 

• DC brushed servo machine, permanent magnet AC servo, universal motor, variable frequency induction motor drive systems: Models, schematics, operating principles, basic relations, characteristics, performance estimation, aspects of dynamic response 

• Torque/acceleration/speed/position control using nested control structures 

• Measurement of torque/speed/position 

• Basic thermal behaviour and duty cycle ratings operation 

• Electrical drive system application case study