Impedance Control Resonant Converter Phase Shift
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Solution Overview
Problem
Conventional power electronic converters face challenges in maintaining high efficiency and power density across wide operating ranges of output power and input/output voltage due to difficulties in maintaining desirable circuit waveforms and increased switching losses at varying power levels.
Innovation Solution
The implementation of impedance control resonant (ICR) dc/dc converters with an impedance control network that adjusts the phase angle between inverter circuits to control output power and compensate for voltage variations, enabling zero or near-zero current switching and maintaining high efficiency over a wide load range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switching frequency is increased to achieve high power density, then power density is improved, but switching losses increase and efficiency deteriorates
Solution Approach 1:
The patent applies resonant oscillation principles to the power converter circuit, using the natural resonant frequency of the LC tank circuit to enable soft switching. By operating at or near the resonant frequency, the circuit achieves zero-voltage switching (ZVS) or zero-current switching (ZCS), eliminating switching losses while maintaining high switching frequencies for high power density.
Solution Approach 2:
The patent dynamically adjusts the switching frequency to match the resonant frequency of the tank circuit, which changes with operating conditions. By continuously adapting the switching frequency parameter, the system maintains resonant operation across wide load and voltage ranges, preserving both high efficiency and high power density.
2Loss of energy
If soft-switching techniques are used to reduce switching losses, then efficiency is improved, but maintaining desirable circuit waveforms across varying power levels becomes difficult
Solution Approach 1:
The patent employs dynamic frequency adjustment where the switching frequency is continuously varied to track the resonant frequency of the tank circuit as operating conditions change. This dynamic adaptation ensures that soft-switching conditions are maintained across the full operating range, from minimum to maximum load, preserving both efficiency and waveform quality.
Solution Approach 2:
The system uses feedback control to monitor operating conditions and adjust the switching frequency accordingly. By detecting changes in load, input voltage, or output voltage, the control system modifies the switching frequency to maintain resonant operation, ensuring continuous soft-switching performance across varying power levels.
3Measurement precision
If frequency control is used to regulate output voltage, then output voltage regulation is improved, but circulating currents do not back off with power reducing efficiency
Solution Approach 1:
The patent utilizes periodic resonant oscillation at the tank circuit's natural frequency to transfer power. By synchronizing the switching actions with the resonant cycle, power is transferred only when necessary during the resonant waveform, eliminating continuous circulating currents while maintaining precise output voltage regulation through frequency modulation.
4Power
If phase-shift control is used at fixed frequency, then power control is achieved, but asymmetric current levels cause transistors to turn-off at large currents losing ZVS capability
Solution Approach 1:
The patent uses resonant oscillation to create symmetric current waveforms in the tank circuit. By operating at the resonant frequency, both half-bridges experience identical sinusoidal current profiles, ensuring that transistors turn off at zero current and turn on at zero voltage, eliminating the asymmetric current problem of phase-shift control while maintaining power control capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for high-efficiency operation with reduced losses across a wide range of power and voltage variations, achieving high power density and smaller size and mass compared to conventional converters.
Implementation Method 1
Resonant power converters using impedance control networks and related techniques
Data Source
AI summary
An impedance control resonant power converter (converter) operated at a fixed switching frequency includes an impedance control network (ICN) coupled between two or more inverters operated at a fixed duty ratio with a phase shift between them and one or more rectifiers. The phase shift is used to control output power or compensate for variations in input or output voltage. The converter operates at fixed frequency yet achieves simultaneous zero voltage switching (ZVS) and zero or near zero current switching (ZCS) across a wide operating range. Output power may be controlled by: (1) changing phase shift between inverters; or (2) adjusting phase shift between inverters depending upon input and/or output voltages so that an admittance presented to the inverters is conductive and then turning the converter on and off at a frequency lower than the converter switching frequency to control output power below a value set by the phase shift.