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An ESC can be a stand-alone unit which plugs into the receiver's throttle control channel or incorporated into the receiver itself, as is the case in most toy-grade RC vehicles. Some RC manufacturers that install proprietary hobby-grade electronics in their entry-level vehicles, vessels or aircraft use onboard electronics that combine the two on a single circuit board. Regardless of the type used, an ESC interprets control information not as mechanical motion as would be the case of a Servo , but rather interpret the information in a way that varies the switching rate of a network of Field Effect Transistors , or "FET's." The rapid switching of the transistors is what causes the motor itself to emit its characteristic high-pitched whine, especially noticeable at lower speeds. It also allows much smoother and more precise variation of motor speed in a far more efficient manner than the mechanical type with a resistive coil and moving arm once in common use. Most modern ESCs incorporate a Battery Eliminator Circuit (or BEC) to regulate a voltage for the Receiver , removing the need for extra batteries. ESCS FOR CARS ESCs designed for sport use in Cars generally have reversing capability; newer sport controls can have the reversing ability overridden so that it can be used in a race. Controls designed specifically for racing and even some sport controls have the added advantage of dynamic braking capability. Simply put, the ESC forces the motor to act as a Generator by placing an electrical load across the armature. This in turn makes the Armature harder to turn, thus slowing or stopping the model. Some controllers add the benefit of Regenerative Braking . This puts the voltage being generated by the motor back to work recharging the vehicle's drive batteries. On full-sized vehicles, regenerative braking is used in electric and hybrid Golf Cars and Hybrid Automobiles while dynamic braking is used in Diesel-electric Locomotives to help slow trains on long downgrades. ESCS FOR AIRPLANES ESCs for electric powered Airplanes are very similar to those used in cars. However, features like reverse are not needed. Dynamic brakes are used to stop a Propeller from spinning allowing folding props to fold in, therefore reducing drag. Brushless ESCs Brushless Motors have recently become very popular in the RC airplane scene. Brushless DC Motor Controllers are much more complicated than brushed motor controllers. They have to convert the DC from the battery into phased AC (usually three phase) that the brushless motor can use. The correct phase varies with the motor rotation, which is where the complication lies. Usually, Back EMF from the motor is used to detect this rotation, but variations exist that use magnetic or optical detectors. SEE ALSO |
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