KINEMATICS FUNDAMENTALS DC Motors AC Motors Permanent Magnet Shunt-Wound Series-Wound Single Phase Universal Motor Polyphase Compound-Wound Induction Synchronous Synchronous Induction Squirrel Cage Wound Rotor Split Phase Shaded Pole Shaded Pole Capacitor Start Repulsion Hysteresis Two-Value Capacitor Repulsion Start Reluctance Wound Rotor Permanent Split Capacitor Repulsion Induction Permanent Magnet Squirrel Cage FIGURE 2-31 Types of electric motors Source:Reference(14) DC MOTORS are made in different electrical configurations,such as permanent magnet (PM,shunt-wound,series-wound,and compound-wound.The names refer to the manner in which the rotating armature coils are electrically connected to the station- ary field coils-in parallel (shunt),in series,or in combined series-parallel (compound). Permanent magnets replace the field coils in a PM motor.Each configuration provides different torque-speed characteristics.The torque-speed curve of a motor describes how it will respond to an applied load and is of great interest to the mechanical designer as it predicts how the mechanical-electrical system will behave when the load varies dynam- ically with time. PERMANENT MAGNET DC MOTORS Figure 2-32a shows a torque-speed curve for a permanent magnet (PM)motor.Note that its torque varies greatly with speed,ranging from a maximum (stall)torque at zero speed to zero torque at maximum (no-load)speed. This relationship comes from the fact that power torque X angular velocity.Since the power available from the motor is limited to some finite value,an increase in torque re- TABLE 2-5 quires a decrease in angular velocity and vice versa.Its torque is maximum at stall (zero Motor Power Classes velocity),which is typical of all electric motors.This is an advantage when starting heavy loads:e.g,an electric-motor-powered vehicle needs no clutch,unlike one pow- Class P ered by an internal combustion engine which cannot start from stall under load.An en- gine's torque increases rather than decreases with increasing angular velocity. Subfractional 1/20 Figure 2-32b shows a family of load lines superposed on the torgue-speed curve of Fractional 1/20-1 a PM motor.These load lines represent a time-varying load applied to the driven mech- anism.The problem comes from the fact that as the required load torque increases,the >1 motor must reduce speed to supply it.Thus,the input speed will vary in response to load IntegralDC MOTORS are made in different electrical configurations, such as permanent magnet (PM), shunt-wound, series-wound, and compound-wound. The names refer to the manner in which the rotating armature coils are electrically connected to the station￾ary field coils-in parallel (shunt), in series, or in combined series-parallel (compound). Permanent magnets replace the field coils in a PM motor. Each configuration provides different torque-speed characteristics. The torque-speed curve of a motor describes how it will respond to an applied load and is of great interest to the mechanical designer as it predicts how the mechanical-electrical system will behave when the load varies dynam￾ically with time. PERMANENT MAGNET DC MOTORS Figure 2-32a shows a torque-speed curve for a permanent magnet (PM) motor. Note that its torque varies greatly with speed, ranging from a maximum (stall) torque at zero speed to zero torque at maximum (no-load) speed. This relationship comes from the fact that power = torque X angular velocity. Since the power available from the motor is limited to some finite value, an increase in torque re￾quires a decrease in angular velocity and vice versa. Its torque is maximum at stall (zero velocity), which is typical of all electric motors. This is an advantage when starting heavy loads: e.g., an electric-motor-powered vehicle needs no clutch, unlike one pow￾ered by an internal combustion engine which cannot start from stall under load. An en￾gine's torque increases rather than decreases with increasing angular velocity. Figure 2-32b shows a family of load lines superposed on the torque-speed curve of a PM motor. These load lines represent a time-varying load applied to the driven mech￾anism. The problem comes from the fact that as the required load torque increases, the motor must reduce speed to supply it. Thus, the input speed will vary in response to load