Technical Articles

An integrated output filter that eliminates motor problems due to the PWM waveforms in both common mode and differential mode operation is proposed. The filter includes a three phase inductor constructed with tricore laminations with six mutually coupled windings. The windings possess differential mode inductance and proportionally very large common mode inductance characteristics. The single integrated inductor with the capacitors creates a… Read more »

Reactor %Z impedance derivation The reactor is an inductive component that is identified and sized by a ratio of its reactive impedance to the applied circuit impedance: (see equations 1 & 2). Reactors by themselves don’t have a % impedance value only by applying the reactor inductance and a current rating to an application with… Read more »

Todd Shudarek, Principle Engineer – Many solutions to protect motors are present in the market. This paper presents data showing how three filters: a typical dV/dt filter, a dV/dt filter utilizing a triple defense core, and a common mode choke, perform in providing both common mode and differential mode filtering. The data shows that a… Read more »

Abstract—Passive harmonic filter topologies that mitigate harmonic problems in three-phase power system due to low DC bus capacitance of 6-pulse rectifier front end adjustable speed drives are proposed. The first filter topology is the modified typical LLCL harmonic filter with a capacitor added across the input and output reactors of each phase. The second filter…

Abstract Pulse width modulation (PWM) AC drives can generate elevated differential mode voltages due to the reflected wave phenomenon, fast rise times and peak voltages. While many users are familiar with differential mode voltages, common mode voltages created by PWM inverters are less familiar. Problems associated with common mode voltages can include erratic behavior of…

Todd Shudarek, Principal Engineer – The proliferation of variable frequency drives (VFDs) has brought increased attention to harmonic effects created by drives. A standard 6-pulse drive with no harmonic mitigation technology may interfere with neighboring equipment, reduce equipment life, and negatively impact the utility power quality. Under some circumstances the total harmonic current distortion (THID)…

Todd Shudarek, Principle Engineer – The proliferation of variable frequency drives (VFDs) has brought increased attention to harmonic effects created by drives. A standard 6-pulse drive with no harmonic mitigation technology may interfere with neighboring equipment, reduce equipment life, and negatively impact the utility power quality. Under some circumstances the total harmonic current distortion (THID)…