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37 | technology has improved their performance considerably. Capacitive Encoders Capacitive encoders use a rotor, a transmitter, and a receiver. The rotor contains a sinusoidal pattern, and the transmitter's reference signal is modulated predictably. The encoder detects the changes in capacitance-reactance and translates them into increments of rotary motion. Capacitive encoders resist environmental contaminants and deal very well with vibration and temperature variance. They are also immune to electrical interference and noise and can deliver high levels of accuracy and resolution. Sense Resistors Current sensing is an alternative method of calculating the position of a rotor. It is a simple technique that uses a resistor placed in series with each motor winding. The voltage across the resistors is sensed and monitored by the motor controller. The resistor value is usually chosen so that the maximum voltage developed across it will be around 1V. That value is usually very low to minimize voltage drop and reduce dissipation while not affecting the stability of the loop. Conclusion This article has focused on two of the main functions electric motor systems require to operate—isolation and sensing— but there are many more parts with their own role in the design. Engineers must choose even the most basic components and connectors with care to handle the motor's interference and vibrations, as well as the high level of electromechanical interference (EMI) found when switching large voltages rapidly. R2A25110KSP Intelligent Power Device mouser.com/renesas-r2a25110ksp-pd