History of Inverters

Inverter Systems

During the late nineteenth, early twentieth century, AC and DC current were both being produced for the mass market. It became necessary for some manufacturers (Westinghouse, GE) to create conversion circuits to allow for use of their products in either DC or AC districts.

Original designs consisted of rotary circuits. An AC engine turning a DC generator (rectifier circuit) or a DC motor turning an AC generator (inverter circuit). This method cause a high loss of power in the conversion process, and may require repair of moving parts.

However, commutators came into use soon after. Commutators put in circuit directly became commonplace. Commutators, unfortunately, still require maintainence because of the wear on the brushes. Brushless DC motors with a fixed stator corrected this problem.

However mechanical conversion systems became a thing of the past when vaccuum tubes came in 1920's and 1930's. The vaccuum tubes had a cathode and an anode. When positive voltageis applied to the anode, if the control electrode is kept at cathode potential, no current flows. When the control electrode is made slightly positive, gas between the anode and cathode ionizes and conducts current.

This was the first solid state component that could be used in an inverter circuit. Several other similar tube methods came out soon after this came out.

Developments in silicon circuitry, especially silicon diodes, during the 1950's became the most popular kind of components to be used in inverter systems, with tubes being used in high current systems until advancements in silicon circuitry overcame the effectivenes of tubes.