We have discussed in great detail what the DC motor is and how it works. This article talks about the applications of these motors.
4 Quadrant Operation of a DC Motor
A miniature DC motor can operate in 4 different regions;
- As a motor in the forward/clockwise region
- As a generator in the forward/clockwise region
- As a motor in the reverse/anticlockwise region
- As a generator in the reverse direction.
In the first quadrant, the motor drives the load with the speed and the torque in the positive direction. This can be likened to when a motor in a crane is used to lift a load.
In the second quadrant, the motor acts as a generator in the forward direction by providing energy to the source.
In the third quadrant, the motor drives the load with speed and torque in the negative direction, like a motor controlling a crane to drop a load.
In the fourth quadrant, the generator acts in reverse mode.
Features of Miniature DC Motors
Reasons why we use DC motors for several applications.
- Full Torque Can Be Developed at Full Speed
- Motor Control is Achieved
- Easy operation
- Low cost of maintenance
Types of DC Motors and Their Applications
Geared DC Motors
With these motors, the torque is increased, but at the expense of the speed. This is a feature that comes in handy because most DC motors rotate at extremely high speed and this is usually too high for some gadgets to utilize. A geared motor would usually contain a DC brush motor and a gearbox attached to the shaft. The speed is reduced via the help of a little gear driving a large gear.
It is not expensive to design, very simple to set up, hence, is useful for applications such as industrial equipment, actuators, robots, and tools for the medical industry.
Series DC Motor
Here, the field winding is connected internally in series to the armature winding of the motor. The starting torque for this machine is extremely high, however, this machine cannot be run without a load. The high starting torque also makes it possible to move very large shaft loads as soon as it is energized.
This type of motor is also known as a series-wound motor. Because the field windings are in series with the armature windings, the strength varies with progressions in the armature current. This motor carries a large amount of current and this translates to more heat dissipated.
The application of the series DC motor is found in small electrical appliances, home equipment, and other cases where variable speed is required.
As the name implies, the field windings are connected in parallel to that of the armature windings. One reason why this motor is widely adopted is the constant speed regulation that is achievable. Because of the parallel connection, the supply voltage is the same in both the armature and the field. This means that there are discrepancies in the field current and the armature current.
Unfortunately, the shunt motor is unable to produce large starting current. Similarly, these motors have low starting torque and the load shaft is considerably small.
Shunt motors are ideal for belt-driven applications as they require constant speed in their operation. these motors are also employed in applications like machine tools and winding machines. Here, the torque precision feature is utilized.
Miniature DC Motors for Medical Purposes
There are small DC motors designed for battery-driven applications like medical and industrial pumps, systems that are used for delivering drugs, robots, small-scale industrial power tools, tattoo machines, mesotherapy guns, tools that are used for the dentist, watch winders, etc.
They are also used for automation of lab testing or diagnosis and security purposes.
Brush DC Motors for Industrial, Medical Pump Applications
There are brush DC motors that are designed for medical and industrial pumps, boasting a coreless design and improved power density. They are designed for applications such as medical and industrial pumps, gas analyzers, and access and power tools.
Disc Magnet Motor Series for Rapid Acceleration
These miniaturized motors are optimized for high torque and acceleration application. This is typically needed in applications where there are significant changes in the acceleration. Also, in applications such as robotics where there is usually a rapid change in the direction.
Brushless Slot-less Motor
This motor is ideal for applications where high performance is required. It is optimized for purposes that require high continuous torque, as well as low to medium speed. The circuit is also constructed such that the iron and recirculation losses are greatly minimized. This automatically reduces heating of the stator.
DC motors have been in existence for over 140 years now and they will continue to serve their purposes. We can only expect them to evolve and become better with time.