(BQ) Part 2 book "Electric machinery fundamentals" has contents: Synchronous motors, induction motors, DC machinery fundamentals, DC motors DC and generators, single phase and special purpose motors. | CHAPTER 6 SYNCHRONOUS MOTORS ynchrono us motors are synchrono us machines used to convert electrical power to mechanical power. This chapter explores the basic operati on of synchronous motors and relates their behavior to that of synchrono us generators . S BASIC PRINCIPLES OF MOTOR OPERATION To understand the basic concept of a synchronous motor, look at Figure 6-1 , which shows a two-pole synchronous motor. 1lle field current IF of the motor produces a stead y-state magnetic field HR. A th ree- phase set of voltages is applied to the stator orthe machine, which produces a three-phase current fl ow in the windings. As was shown in Chapter 4, a three-phase sct of currents in an annature winding produces a uniform rotating mag netic fie ld Bs. Therefore, there are two magnetic field s present in the machine, and the rotor field will tend to line up with the stator field , ju st as two bar magnets will tend to line up if placed near each other. Since the stator magnetic field is rotating, the rotor magnetic field (and the rotor itself) will constantly try to catch up. TIle larger the angle between the two magnetic fi e lds (up to a certain maximum), the greater the torque on the rotor of the machine. The basic principle of synchronous motor operation is that the rotor "chases" the rotating stator magnetic field around in a circle, never quite catching up with it. Since a synchronous motor is the same physical machine as a synchronous generator, all of the basic speed, power, and torque equations of Chapters 4 and 5 apply to synchronous motors also. 346 SYNC HR ONOUS MOTORS 347 o / , 11, 0, o Tind ",k HRx n S '" counterclockwi se o FIGURE 6-1 A two-pole synchronous motor. The Equivalent Circuit of a Synchronolls Motor A synchronous motor is the same in all respects as a synchronous generator, except that the direction of power fl ow is reversed. Since the direction of power fl ow in the machine is reversed, the direction of current fl ow in the .
