Performance of DC Machines

In this chapter, the authors provide an overview of the issues related to losses and efficiency of D.C. machines. Speed control is then discussed. Solid state speed control is discussed afterwards. Speed Control using thyirstors. After finishing the discussion on speed control, the authors discuss braking DC motor, regenerative braking, dynamic braking, and finally this chapter concludes with plug braking.

Parallel Operations of DC Generators

There are numerous advantages of parallel operation of generators. In this chapter, the authors provide a detailed overview about advantages of parallel operation, voltage and current relations for sources of emf in parallel. Then they discuss parallel operation of shunt generators, conditions for parallel operation of shunt generators, and parallel operation of compound generators. Then they discuss the procedure of paralleling generators.

Principle of DC Generator

In this chapter, the authors discuss about principles of DC generator, variation of voltage induced in the conductor with the position of conductor. After that the authors discuss frequency of induced voltage, magnitude of induced voltage. This chapter ends with discussion of the main parts and construction of a DC machine.

Stepper Motor

A stepper motor is a digital device which is like a computer that runs on pulses. It can be directly connected with digital computer unlike D.C. motor for which A/D or D/A converters are needed. In fact, stepper motor is an electric motor which moves or rotates in series of small discrete steps. A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. In this chapter, the authors discuss the stepper motor. It starts with the definition of stepper motor, its basic function, and principle of working. They then discuss the types and construction of stepper motor. Finally, this chapter concludes with the applications of stepper motor.

Applications of DC Motors

This chapter gives the motivation behind using direct current machines and its application in various domains. The authors start discussing the applications of DC machines in toys, disk drives Steel rolling mills, Paper machines, Generator, Electrical Propulsion, Cranes, CD/DVD players, Electric vehicles, RC Vehicles, UAVs, Cement Plants, and Aircraft applications. They then provide a case study on the application of DC Chopper Motor Drive. They conclude the chapter by discussing the use of D.C. Series Motors in Electric Traction.

Types and Characteristics of DC Generators

There are several types of Direct Current machines. In this chapter, the authors highlight the types and characteristics of DC generator. Load characteristics of DC generator are then discussed. They then discuss separately excited generators, self-excited shut generators, series generators, and compound generators. Finally, they discuss voltage build-up in self-excited generators and critical field resistance.

Armature Reaction

In Direct Current machines, we have two types of windings. The first one is field winding and the second one is armature winding. Armature field, and armature reaction is about armature winding. In this chapter, we discuss the issue of armature field, Geometrical and magnetic neutral axis (G.NA & M.N.A), resultant field at load. Then we discuss shift of neutral plane in generator vs motor. After that we discuss the calculation of cross-magnetising ampere – turns per pole, compensating windings. Finally, this chapter ends with commutating or inter poles.

Electromagnetism

For Direct Current machines, Electromagnetism serves as the core. Therefore, in this chapter, the authors provide the fundamental background to the reader by giving basic information regarding electromagnetism. The chapter starts by discussing system of units, then the authors discuss regarding magnetic field, intensity of magnetic field, flux, flux density, amperes law, and units of flux. After that the authors discuss theory of magnetism, law of electromagnetic induction, Fleming's right and left hand rules, law of magnetic circuit, energy stored in a magnetic field and energy of inductive circuit. Hysteresis loop with core losses and hysteresis loss is then discussed. Finally, we discuss Eddy current loss.

DC Motor Functionality

This chapter deals with the core of direct current machines. In this chapter, the authors present a very detailed insight about the principle of operation of DC motor. They Discuss torque generated from motors. Then they discuss counter emf or back emf. Speed of rotation is then discussed. They then discuss power developed by motor, relation between torque and speed of a motor, speed-torque characteristics, torque-load characteristics, shunt motor, series motor, compound motor, speed-load characteristics, and cumulative compound motor. Differential compound motor is then discussed along with discussion of speed regulation. This chapter ends with starting of DC motor and a discussion over four point starting box.

DC Servo Motor

In this chapter, the authors discuss the DC servo motor. They first described the basic definition of DC servo motor and how it is different from other types of motors. Then they discuss armature controlled DC servo motor, and field controlled servo motor. Modelling of DC servo motor is then discussed. At the end of the chapter, performance analysis from the transfer function and applications in control is discussed.