Micrometals, Inc. applications

Public transportation such as commuter and rapid transit trains, trams, and busses may derive primary power from a high voltage AC (up to 25kV/60Hz) or DC (600-1500VDC) power line in the form of an overhead line or a third rail. High Voltage AC line power is first stepped down and rectified to produce DC. Power from a high voltage DC link is then converted to 3-phase AC power for powering traction motors and auxiliary AC power for powering equipment such as air-conditioning compressors or fans. Further rectification and DC-DC conversion or power factor correction provide power for DC loads such as for battery charging, lighting and instrumentation.  Electrically powered public transportation affords zero-emission operation particularly advantageous when traversing long tunnels or within busy city centers. Battery power may be used for traction within select lines or city routes to avoid overhead lines. 

Class D amplifiers typically use a low-pass LC type filter to attenuate the switching noise in the output waveform while passing the audio signal to the loudspeaker.  So it is important that engineers design and specify the correct L-C filter values in addition to choosing the correct LC components for the amplifier to minimize losses and harmonic distortion. Class D Amplifier uses pulse width modulation technique to sample audio signal level for amplification. Audio input is typically compared to a high frequency (>250kHz to MHz) sawtooth to produce a square wave signal with equal amplitude and duty that varies with signal level. The high frequency pulses can then be amplified with little power loss.

Typical Applications - High Pass, Low Pass, Band Pass Filters, Broadband Transformers. RF inductors are special inductors designed to be used in radio frequency (RF) and microwave applications, which are much higher in frequency than AC or DC applications from 10 MHz to several GHz. Since these applications generally need a high Q (Quality factor) value they are best served by low permeability cores and consistent response over a wide frequency range. RF inductors are typically used in mobile communications equipment, like 5G, as high pass filters, low pass filters and bandpass filters in radio communication devices and systems. RF inductors are also used as broadband transformers in powering such devices.