True DC Current Source via Resonant Circuit
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Solution Overview
Problem
Current power conversion technologies primarily rely on voltage source converters, which limit the ability to generate a true direct current (DC) source, essential for efficient AC/DC and DC/AC power conversion, as they struggle to maintain infinite voltage during open circuits or infinite current during short circuits.
Innovation Solution
The implementation of a resonant circuit coupled with an AC voltage source and an inverter to convert AC voltage into AC current, and subsequently into DC current, utilizing LC circuits and thyristor bridges to achieve a true DC current source, allowing for constant current delivery independent of load resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage source converters are used for power conversion, then power conversion from AC to DC and DC to AC can be achieved, but the ability to generate a true DC source with infinite voltage during open circuit is limited
Solution Approach 1:
The invention changes the fundamental operating parameter from voltage-source-based to current-source-based power conversion. By using current source converters with series resonant circuits, the system achieves true DC source characteristics with infinite voltage capability during open circuit conditions, fundamentally altering the parameter space of power conversion operation
Solution Approach 2:
The invention introduces series resonant circuits as intermediary elements between the AC source and the DC load. These resonant circuits act as mediators that enable the conversion from AC to true DC by utilizing resonant frequency matching, thereby achieving infinite voltage capability during open circuit without requiring ideal voltage sources
2Reliability
If conventional voltage source technology is used, then power conversion objectives can be met, but the system cannot maintain constant current independent of load resistance
Solution Approach 1:
The invention inverts the conventional approach by using current source converters instead of voltage source converters. This inversion allows the system to naturally maintain constant current independent of load resistance by utilizing the inherent characteristics of current sources and series resonant circuits, eliminating the need for complex current regulation mechanisms
Solution Approach 2:
The invention changes the controlling parameter from voltage to current. By operating with current source converters and series resonant circuits tuned to the supply frequency, the system maintains constant current delivery through parameter matching rather than through complex feedback control, achieving simplicity through parameter optimization
3Productivity
If voltage source converters are used, then AC to DC conversion can be achieved, but power factor and harmonics are not optimized
Solution Approach 1:
The invention utilizes resonant vibration principles in the electrical domain by employing series resonant circuits tuned to the supply frequency. This resonant operation optimizes power transfer, improves power factor, and minimizes harmonic generation by operating at the natural resonant frequency of the circuit, thereby enhancing productivity while reducing harmful factors
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 enables efficient power conversion by maintaining constant DC current and adjustable DC voltage, reducing the need for conventional transformers and DC/DC converters, while improving power factor and minimizing harmonics, suitable for various applications including UPS and solar inverters.
Implementation Method 1
Tuning inductor 203 and capacitor 205, having a resonant frequency of 1/(2*pi*SQRT(LC)), to the voltage source frequency, e.g., 60 Hz
Implementation Method 2
an inverter, and an optional load. The AC voltage source may be a single phase or a multi-phase (e.g., three-phase) AC voltage source
Data Source
AI summary
According to one embodiment, a power converter circuit includes a resonant circuit coupled to an alternating current (AC) voltage source to convert a first AC voltage to a first AC current and an AC to direct current (AC/DC) converter coupled to the resonant circuit, where the AC/DC converter is to convert the AC current to a DC current. The power converter circuit further includes an inverter coupled to the AC/DC converter to convert the DC current to a second AC current, an AC filtering circuit coupled to an output of the inverter, and a load coupled to the output of the inverter to convert the second AC current to a second AC voltage.