Switchable Current Paths in DC/AC Power Conversion Apparatus
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Solution Overview
Problem
Resonant inverter and resonant converter circuits face issues with high voltage peak values across switching elements due to voltage resonance, requiring high withstand voltage switching elements, which increase costs and reduce conversion efficiency, and also face challenges in optimizing and stabilizing high-frequency switching operations due to independently distributed LC resonance circuits, leading to increased component costs and difficulties in miniaturization.
Innovation Solution
The power conversion apparatus changes the input inductance from a single inductor to an LC resonance circuit combining capacitance and inductance, optimizing impedance characteristics for oscillation frequency, with a second LC resonance circuit having two current paths, one with a series inductance and capacitance, to suppress voltage peaks and facilitate Class E switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a resonant inverter uses a single-ended switching element with a load network including an inductor and capacitance, then high-frequency switching operation is possible with high conversion efficiency, but the voltage peak value applied across the switching element rises to around 3.6 times the DC input voltage
Solution Approach 1:
The patent divides the load network into two separate resonant circuits: a first resonant circuit connected to the switching element that suppresses voltage peaks, and a second resonant circuit that provides the necessary load resonance for high-frequency operation. This segmentation allows each circuit to be optimized for its specific function, resolving the contradiction between voltage suppression and high-frequency performance.
2Strength
If a resonant converter attaches an LC resonant circuit to suppress the second harmonic component, then the voltage peak value is suppressed to around double the DC input voltage, but the routing of the mounting pattern is significantly influenced and it becomes difficult to optimize and stabilize resonant switching operation
Solution Approach 1:
The patent combines the voltage suppression function and the load resonance function into a single integrated resonant circuit configuration. The first and second resonant circuits are designed to work together as a unified system, eliminating the need for separate distributed LC circuits and simplifying the mounting pattern routing while maintaining voltage peak suppression.
3Reliability
If high withstand voltage switching elements are used to handle the voltage peak, then the voltage stress is managed, but the On-resistance increases which causes increased cost and reduced conversion efficiency
Solution Approach 1:
The patent introduces a first resonant circuit that acts as a cushioning mechanism before the voltage reaches the switching element. This circuit suppresses voltage peaks in advance, protecting the switching element from high voltage stress and allowing the use of lower withstand voltage devices with lower On-resistance, thereby maintaining high conversion efficiency.
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 configuration allows for the use of low withstand voltage switching elements, reducing costs and improving efficiency, while optimizing resonant switching operations and stabilizing the apparatus, enabling compact design and reduced manufacturing costs.
Implementation Method 1
the voltage peak value applied across both ends of the switching element 105 during the period where the switching element 105 is off rises due to voltage resonance to around 3.6 times the DC input voltage V1
Implementation Method 2
an LC resonance circuit (a series circuit with a capacitance 106 and an inductance 107) connected between the output terminal 103a out of the output terminals 103a and 103b and one end of the switching element 105
Implementation Method 3
high-frequency switching operations up to the RF band are possible
Implementation Method 4
a resonant inverter and a resonant converter circuit that have high conversion efficiency are well known examples of an RF power amplifier and power conversion circuit that operate in a high frequency band
Data Source
AI summary
A power conversion apparatus includes: DC input terminals for inputting a DC voltage; AC output terminals for outputting an AC voltage; a switching element; a first resonant capacitance connected across the switching element; a first LC resonance circuit that has an inductance and a capacitance connected in series and is connected together with the switching element between the AC output terminals; and a second LC resonance circuit connected in series together with the switching element between the DC input terminals. The second LC resonance circuit includes a first connector portion connected to one DC input terminal and a second connector portion connected to the switching element, and has a first current path, which includes an inductance, and a second current path, which includes a series circuit with an inductance and a capacitance, formed between the first connector portion and the second connector portion.