A resonant inverter is a special electrical power conversion circuit that is used to change direct current (DC) to alternating current (AC) for easier application. There are different types of electrical inverters which are used for different purposes. This mostly entails conversion of power supply through both direct and alternative means. For instance, resonant inverters are used in uninterruptible power supply (UPS) devices, electrical induction heaters, microwaves, surface detection devices — or sonar systems, medical diagnostic equipment, high frequency radio and communication devices, fluorescent lighting and inductive power couple transfer systems.
The main difference between typical inverters and a resonant inverter is that resonant inverters convert electrical energy through a non-modulated single phase system whose structure depends on the nature of the DC source. It can deliver electrical waves either from direct voltage or current power sources. The resonant inverter is based on an electronic oscillator with either unidirectional or bidirectional switches, depending on the type of current in use. The switches are made of controlled components that are connected to an unparallel diode. The controlled components eventually determine the exchange mechanism of the switches.
Effective operation of an electrical inverter depends on the inherent characteristics of its circuit network. These characteristics include the damping factor, the under damped natural frequency and the switching frequency of the controlled internal components. In a resonant inverter, effective energy output is determined by the oscillations of the switches. A switch with high damping factor has a low rate of energy loss since its oscillations die out more slowly. This is the ideal type of switch for electrical inverters. On the other hand, one with an under damped circuit has a higher rate of energy loss since its oscillations die out much faster.
It is possible to control the loss of energy within the inverter by the addition of passive elements to the load of the device. This will lead, however, to an increase in price and weight of the device, but this will be offset by better utilization of its internal components. Better control of energy loss can be achieved through the use of auxiliary methods such as amplitude control of the direct current that enters the device.
There are many industrial and home applications for electrical inverters. Contactless power transfer, heating through induction, DC-DC converters and uninterrupted power supplies are just a few of the areas where resonant inverter technology is applied. The power output obtained from the device can be connected to transformer windings, extended coils and other components. The remarkable manner in which a resonant inverter permits electrical power conversion can be applied in numerous electronic processes.