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A universal motor is a type of motor that can operate along both Ac & Dc power. Universal motors are wrapped in sequence (the armature and field windings are in series). Because of the series connection, universal motors may generate a lot of torque, thus they’re usually incorporated inside the item they’re supposed to drive.
The majority of universal motors are designed to run at speeds up to 3500 RPM. On a DC source, these motors spin faster than on an AC supply of the same voltage. This seems to be due to the reactance voltage drop, which only occurs in AC and not DC.
Construction of a Universal Motor
A stator upon which field poles are attached makes up a universal motor. The field poles are wrapped with a field. A universal motor’s stator field circuit and armature are layered. Eddy currents are formed when using AC power, hence sheets are required to decrease them.
The commutator and brushes are held in place by the universal motor’s rotational armature, which is made up of straight or skewed slots. Due to the general current created in the armature coils, AC transmission is worse than DC transmission. As a result, the brushes utilized are extremely durable.
The stator field coils are wired in series with the rotor windings through a commutator in a commutated series-wound motor. An AC series motor is another name for it. The universal motor’s architecture is relatively similar to that of a DC series motor, but it is significantly tweaked to allow it to run on AC power. So because current in both the field coils and the armature (and the resulting magnetic fields) flip (transverse direction) concurrently with the supply, this type of electric motor can run on AC. As a result, the resulting mechanical force will rotate in a continuous direction, regardless of the applied voltage direction, and will be decided by the commutator and polarity of the field coils.
Work of Universal Motor
- When connected by a DC source,
When a DC supply is used to power the universal motor, it becomes a DC series motor. When current runs through the field winding in this scenario, it creates an electromagnetic field. In the armature conductors, the same current flows. A current-carrying conductor is subjected to a compressive force when it is put in a magnetic field. The rotor rotates as a result of this mechanical force. The direction of this force is determined by Fleming’s Left-hand rule.
- When connected by a AC source
When AC power is applied to the universal motor, it produces a unidirectional torque. This is due to the fact that the armature and field windings are connected in series and in phase. As a result, anytime the polarities of the AC changes, the current in the armature and the field winding both change direction at the same time. The magnetic field and armature current inverted directions, while the force experienced by armature conductors stays the same. Universal motors operate along the same principle as DC series motors, irrespective of whether the power source is AC or DC.
Universal Motor’s Disadvantages
- a lot of noise
- Running a universal motor in the other way will be tricky.
- If the motor overheats, we will need fresh air to prevent this.
- It necessitates regular servicing and servicing.
Characteristics of Universal Motors
⇨Universal Motor Efficiency
Relatively small universal motors have a 30 percent efficiency, whereas bigger universal motors have a 70-75 percent efficiency.
⇨Universal Motor Speed Load Characteristics
⇨Universal Motor Speed Control
The speed of the universal motor is controlled to prevent the motor from running at a harmful speed when there is no load. Building the universal motor inside a gadget that never runs in no-load mode is one way to control the speed. These configurations are recommended for small – scale applications where the motor is connected directly to the system it drives.
There are a few different options for adjusting the motor’s speed to the appropriate value:
- To minimize the real load speed, a gear train is used.
- Controlling speed via resistance.
- Centrifugal Mechanism is a type of centrifugal mechanism.
- Field Touching is a speed control strategy.
Uses of Universal Motor
Universal motors are utilized in Uses that require high speeds and precise speed control. The following are some of the many uses for universal motors:
- Table fans, hair dryers, and grinders all employ universal motors.
- They’re found in drill machines that are portable.
- Polishers, blowers, and kitchen appliances all use them.
Conclusion:
When used in DC current mode instead of AC current phase, Universal motors can be reduced in many uses. Functioning in DC current mode extends motor lifetime and reduces motor noise, in addition to reducing motor size and weight.
The adaptable approach proposed in this essay is dependent on the use of a low-cost 8-bit ST6 microcontroller.
The ST6 microcontroller may drive a DC or AC current motor with a variety of user displays, obviously it depends on the hardware design. It allows functions like motor speed or torque control, sensor monitoring, display control, soft start, and protection to be implemented.
