What Is an AC Servo Motor?
Many of the appliances and tools that we use in our homes have AC motors. These are also found in industrial machines and robots that require precision and motion control.
An ac servo is a two-phase induction motor that has a stator and a rotor. It has two distinct windings that are 90 degrees apart, known as the main and the control winding.
Stator
An AC servo motor has a stator assembly and a rotor, like a regular induction motor. The stator is a laminated structure with two dispersed windings placed 90 degrees apart from each other, which generates a rotating magnetic field. The first of the two windings is known as the reference or fixed phase winding and receives a constant voltage supply source. The other is the control winding or control phase and is activated by a variable control voltage which comes from a servo amplifier.
When the control voltage is applied to the control winding, it produces a leading or lagging magnetic field that influences how fast and how much the rotor spins. The resulting difference in phase between the reference and control phases determines speed, torque, angular velocity and direction of rotation.
The rotor is made up of a permanent magnet. Since it does not require current to move, the rotor does not draw any power from the servo motor. This enables the motor to operate more efficiently and at lower cost than a DC motor. It also reduces radio frequency noise and the need for a commutator. As a result, AC servo motors are becoming increasingly popular in industries such as machine tools and robotics machinery as well as everyday appliances & tools around the house.
Rotor
The rotor is the revolving part of an ac servo. It’s connected to the shaft and has a control winding that is fed by a servo amplifier to produce a variable control voltage. This voltage ac servo is then fed to the rotor and creates the revolving magnetic field. The rotor usually comes in two kinds; one is called a squirrel cage type and the other is called a drag cup type. The former is a normal cage-type rotor that includes aluminum bars fixed in slots and short-circuited through end rings while the latter is a drag cup type which keeps the air gap minimal for optimal flux linking.
The main function of a servo motor is to precisely regulate linear or angular motion. In fact, many industries rely on these motors to activate various machines and tools to ensure they function properly as closed-loop systems. For instance, robotics machinery and CNC machines commonly use them due to their accuracy. They are also used in aerospace systems such as radar antennas and missile guidance systems.
The servo motor can be either two-phase or three-phase depending on the power needed. However, it is vital that it has the proper amount of voltage and frequency so it can function efficiently. Otherwise, the machine may not function as intended or even break down.
Control
An AC servo motor is able to precisely regulate linear or angular motion by receiving feedback signals and altering its operation accordingly. Functioning as a closed-loop system, they are ideal for accurate tasks such as controlling a printer’s nozzle or manipulating the arm of a robot. They run on the same AC voltage outlets commonly found in homes and offices, making them a common component of many industrial devices and automation systems.
To achieve high-precision motion control, an ac servo motor must be precisely controlled by its drive system. This is done by incorporating feedback devices such as encoders or resolvers to provide real-time position and speed information to the system. The drive then uses this information to adjust the motor’s voltage and current output based on the desired motion profile.
Precise servo control can help ensure smooth and vibration-free multi-axis coordinated motions. It is essential to carefully select a drive compatible with the motor and application demands. Then, it is important to carefully configure operating mode such as velocity/torque control through commissioning procedures verifying performance goals. Moreover, it is critical to properly calibrate the encoders and tune servo loop settings through auto-tuning or manual adjustment. With adherence to these best practices, an ac servo can deliver dynamic response and stability even under demanding operating conditions. This article was brought to you by Delta, a leading global manufacturer of AC drives and motors.
Power
In order to function, ac servo motors require a power supply which delivers alternating current to the stators of the AC servo motor. This alternating current passes through wire coils in the stator to create a rotating magnetic field. This rotating magnetic field is then influenced by the feedback system of the servo motor to control its speed & position.
These servo motors are capable of handling high amounts of torque at high speeds, making them ideal for industrial applications like conveyor belt systems in manufacturing environments. They are also constructed to withstand harsh conditions including excessive heat, humidity, and vibration by using special coverings.
Unlike DC motors which use a mechanical system called a commutator, an AC servo motor uses no brushes in its rotor and does not need a ac servo factory commutator to operate. This results in less maintenance & a longer life expectancy for the motors.
Most machines & appliances that we use on a daily basis like water heaters, ovens, pumps & off-road vehicles are powered by these types of AC motors. They are capable of moving heavy equipment & delivering the needed amount of power for each task without sacrificing efficiency or safety.