SCR controls cost less than their PWM counterparts. This intuitively makes sense since the power section of a SCR control is a simply a rectifier bridge, while the PWM control has a diode bridge that costs roughly the same, plus the additional PWM components like BUS capacitors and MOSFETs or IGBTs.
A diode is an electrical component that allows electricity to flow in one direction, but not in the other. It’s similar to a check valve that lets water flow out, but not back in. It’s also like a flap on an exhaust vent. If air is flowing in the right direction, the force of the air opens the vent and allows the fumes to escape. Once the air stops blowing, gravity closes the flap to prevent the outside air, debris, fumes, or animals from getting back in.
When someone wants to use a motor control to vary the speed of a motor, they typically use a potentiometer. A potentiometer is a variable resistor that is used to send a voltage range as a reference signal to the motor control. Most motor controls provide 3 connections for a potentiometer; a common, a reference, and a supply voltage. The illustration below shows how the potentiometer can be set to different positions to send any signal between 0 and 10 VDC, if using a 10 VDC supply voltage.
An AC motor controller is known as the device that controls the speed of the AC motor. An AC controller can also be referred to as a variable frequency drive, adjustable speed drive, frequency converter and more. The AC motor receives power, which is converted by the AC motor controller into an adjustable frequency. This adjustable output allows the motor speed to be precisely controlled.
Alternating current or AC motors are basically responsible for keeping the universe humming along. With more than 60 years of experience in the field of AC motors and electronics, American Control Electronics products and adaptations can be found, well - pretty much everywhere. From small to large, AC motors are found in the industrial, commercial and residential markets. AC motors are a great power source for a number of reasons and they are used in pumps, food and beverage machines, automated conveyer equipment, packaging operations, washing machines, electric knife sharpeners, office equipment, ovens, and water heaters - and the list goes on and on.