Motor L-C/Sinusoidal Filters

Motor L-C filters consist of filter reactor (choke) and capacitors. They are used on the output of PWM (Pulse Width Modulated) drives. Typically, they reduce the motor current ripple to much lower levels than reactors only, and they eliminate voltage pulses.

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When optimized, L-C filters can produce nearly ideal sinusoidal motor current and voltage which permits the motor to develop its full rated power (torque) without overheating. However, in order to achieve this optimum, drive control details and motor equivalent circuit values must be known. SPINDEL Electronics provide L-C filters from low to very high frequency motor applications, up to about 1000 Volts and 1000 Amps. We use modern simulation tools and an abundance of experience to specify an optimal filter for every application.

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L-C filters (sinusoidal filters) have to be sized very carefully. Improper specification of filter components may result in application problems and even motor failure, drive failure or failure of filter itself. ​Typical low frequency applications are for PWM drives in applications with very long motor wires or where very sensitive analog instrumentation is being used. Typical high frequency applications are for PWM drives where it is important to get as much power (torque) out of the motor as possible.