Series-resonant Converter System Research Articles

Generic Derivation of Dynamic Model for Half-Cycle DCM Series Resonant Converters

The series resonant converter (SRC) operated in the half-cycle discontinuous-conduction-mode (HC-DCM) provides galvanic separation and a tight coupling of its input and output voltages in an open-loop operation, i. e., with minimum control complexity, which renders it suitable for a wide range of applications that require galvanic isolation. This letter first explains the “DC transformer” behavior of the converter and then provides a generic derivation of a passive equivalent circuit that accurately models the converter's terminal behavior. The proposed generic derivation yields the known analytic results for idealized cases, but additionally allows for a parametrization of the equivalent circuit based on simulated or measured waveforms, thereby facilitating high accuracy also in nonideal cases. Furthermore, it is shown that a noninfinite magnetizing inductance results in an additional load-independent difference between the input and the output voltage, and a corresponding extension of the equivalent circuit model is proposed. The considerations are verified by simulations and measurements of a 10 kW/350 V/350 V HC-DCM SRC system.

Series resonant AC-power interface with an optimal power factor and enhanced conversion ratio

A method of power pulse modulation with internal frequencies of tens of kHz which is also suitable for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow. The power circuitry of the converter is provided with one single high-frequency resonant link in the direct energy path. Natural current commutation of the thyristors is obtained by the use of a series-resonant circuit for power transfer and control. Consequently, switching losses can be reduced to a minimum without compromising the reliability of the solid-state components. Test results of a converter system generating three-phase sinusoidal waveforms demonstrate the significant aspects of this improved series-resonant power processor and indicate the possibilities of fast-acting DC and AC converter systems with reversible power flow.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

DC-AC Series-Resonant Converter System with High Internal Frequency Generating Multiphase AC Waveforms for Multikilowatt Power Levels

A new method of power pulse modulation with internal frequencies of tens of kHz which is also suitable for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized multiphase bipolar waveforms with reversible power flow. The power circuitry of the converter is provided with one single high-frequency resonant link in the direct energy path. Natural current commutation of the thyristors is obtained by the use of a series-resonant circuit for power transfer and control. Consequently, switching losses can be reduced to a minimum without compromising the reliability of the solid-state components. The high pulse frequency allows the principle of modulation and demodulation for fast system response and output waveforms with reversible power flow with low distortion. Test results of a converter system generating three phases-sinusoidal waveforms independent of the load characteristics-demonstrate the significant aspects of this class of power conversion. The material presented indicates the possibilities for fast-acting polyphase dc-ac and ac-ac converter systems.

DC-to-AC Series-Resonant Converter System with High Internal Frequency Generating Synthesized Waveforms for Multikilowatt Power Levels

A new method of power pulse modulation with internal frequencies of tens of kHz and suited for multikilowatt power levels is applied to a series-resonant converter system for generating synthesized unipolar and bipolar waveforms. The high pulse frequency allows the principle of modulation and demodulation to be applied for fast system response and output waveforms with low distortion and prevents excessive stresses on components. Natural current commutation of the thyristors is obtained by the use of a series-resonant circuit for power transfer and control. Test results of a 4-kW thyristor converter system generating sinusoidal and nonsinusoidal waveforms independently of the load characteristics demonstrate the significant aspects for this class of power conversion. The material presented indicates the capability of the system to avoid excessive component stresses as well as the possibilities for fast-acting four-quadrant dc-to-dc, single-phase or polyphase dc-to-ac and ac-to-ac converter systems.