Figure 7.5 and Equation (7.7) show

Figure 7.5 and Equation (7.7) show us that the brushed DC motor can be very easily controlled. If the supply voltage Es is reduced, then the maximum torque falls in proportion, and the slope of the torque/speed graph is unchanged. In other words, any torque and speed can be achieved below the maximum values. We will see in Section 7.2 that the supply voltage can be controlled simply and efficiently, so this is a good way of controlling this type of motor. However, reducing the supply voltage is not the only way of controlling this type of motor. In some cases we can also achieve control by changing the magnetic flux . This is possible if coils rather than permanent magnets provide the magnetic field. If the magnetic flux is reduced then the maximum torque falls, but the slope of the torque/speed graph becomes flatter. Figure 7.5 illustrates this. Thus the motor can be made to work

Figure 7.5 and Equation (7.7) show us that the brushed DC motor can be very easily controlled. If the supply voltage Es is reduced, then the maximum torque falls in proportion, and the slope of the torque / speed graph is unchanged. In other words, any torque and speed can be achieved below the maximum values. We will see in Section 7.2 that the supply voltage can be controlled simply and ef fi ciently, so this is a good way of controlling this type of motor. However, reducing the supply voltage is not the only way of controlling this type of motor. In some cases we can also achieve control by changing the magnetic fl ux?. This is possible if coils rather than permanent magnets provide the magnetic fi eld. If the magnetic fl ux is reduced then the maximum torque falls, but the slope of the torque / speed graph becomes fl atter. Figure 7.5 illustrates this. Thus the motor can be made to work.

Figure 7.5 and Equation (7.7) show us that the brushed DC motor can be very easily controlled. If the supply voltage Es. Is reduced then the, maximum torque falls in proportion and the, slope of the torque / speed graph is unchanged. In other. Words any torque, and speed can be achieved below the maximum values. We will see in Section 7.2 that the supply voltage. Can be controlled simply and ef fi ciently so this, is a good way of controlling this type of motor. However reducing the,, Supply voltage is not the only way of controlling this type of motor. In some cases we can also achieve control by changing. The magnetic fl UX. This is possible if coils rather than permanent magnets provide the magnetic fi eld. If the magnetic fl UX. Is reduced then the maximum torque falls but the, slope of the torque / speed graph becomes fl atter. Figure 7.5 illustrates. This. Thus the motor can be made to work.