Remember the famous “war of currents” between Tesla and Edison? Here’s a brief recap; Thomas Edison was a proponent of Direct Current and he went ahead to establish a demonstration with light bulbs. Nikola Tesla, his young student highlighted how difficult it would be to use DC on a large scale and advocated AC, pitched the idea to Westinghouse, tore his patent to make the technology more affordable and ubiquitous, and ultimately won the war.
While this ‘war’ occurred a long time ago, it continues till today. Nowadays, many sources of electricity provide DC (solar and wind being the most common), and it is just right that we revisit the argument for DC. This time, there are several factors that support the use of DC motors over AC motors.
Here are 7 advantages of DC motors offer over conventional AC motors.
Advantages of Electrical DC Motors
DC Motors Have a Higher Starting Torque
DC drives are regarded as the best suited for electrical traction applications. This means that it is ideal for driving heavy loads in starting conditions. For DC series motors, the starting torque is as high 500% of the actual value of the operating torque. This is why we have several motors in use in applications such as trains and cranes.
DC Motors Give You Increased Speed Control over a Wide Range
Another feature of the DC motor that makes it attractive for industrial purposes is the fact that it offers you a wide range of speed control. This is not only when it is above the rated speed, but also below the rated speed. One way by which this is done in DC shunt motors is either via armature control method or field control method. Hence, it is widely employed in both rolling mills and paper mills.
DC Motors are Devoid of the Harmonic Effect
One of the major disadvantages of induction motors is the harmonics. This doesn’t just cause inefficiencies and losses; it also shortens the lifespan of the motor. However, DC motors do not have this issue, the harmonic problem is eliminated.
DC Motors Give You Quick Control Over the Motors
Fast and accurate control of motors has been hitherto impossible with conventional AC motors. This is especially true for applications that require the immediate start, stop, and reverse operation. DC motors, however, solve this problem aptly.
DC Motors are Ideal for Low-Cost Operation
In comparison with induction drives used for heavy-duty operations, DC motors considerably save cost.
The Electronics and Rectification Required are Minimal
When you compare a typical DC drive with an AC drive, you will observe that the power electronics circuitry is less complex. Similarly, DC drives can run on several different types of power source.
DC Motors Offer Improved Speed Regulation
Finally, DC motors are much more popular due to the flexibility it offers in terms of speed regulation when you compare it to AC motors. When it comes to higher specific speed control, DC motors are the best choice.
What is the Best DC Electric Motor?
Depending on the application, there are several types of electric motor that will fit your bill. Here are some of the most popular.
- Shunt Wound Motor
- Series Wound Motor
- Compound Wound Motor
Shunt Wound Motor
Here, the armature and the field have a shunt connection (they are connected in parallel). Hence, the motor is split into two different parts, and then we have separate current going through the armature and another going through the field. This type of motor is used in scenarios where the starting torque required is low and where the speed regulation is not as important.
Series Wound Motor
Unlike the example above, both the armature and the field windings are connected in series, meaning that they share the same current. This makes it possible to draw a high amount of current and torque concurrently.
Compound Wound Motor
This motor is both a combination of series and wound shunt designs. It offers a starting torque that is higher than shunt wound design; however, the torque provided doesn’t measure up to that of series wound motors.
DC is arguably the future of motors, electrical energy generation, and transmission. There’s no disputing the fact that significant effort is still required to make these aspirations come to fruition. However, considering the advantages of DC motors, DC transmission, and DC generation offer, this is an inevitable consensus.