H-Bridge DC-AC Inverter Soft-Switching Control
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Solution Overview
Problem
H-Bridge DC-AC inverters experience significant switching loss and reduced lifetime of switching elements due to hard-switching, which also limits their conversion efficiency and requires a DC-link capacitor, making them less compact.
Innovation Solution
Implementing a voltage feed-forward compensation configuration that calculates voltage feed-forward compensation parameters in buck and boost modes to control output current waveforms, allowing for zero-voltage switching and synchronous control of active switching elements with AC current, thereby reducing switching loss and eliminating the need for a DC-link capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hard-switching is used in active switching elements, then the inverter can operate with a wide range and flexible circuit design, but switching loss increases and the lifetime of switching elements decreases
Solution Approach 1:
The patent changes the switching parameter from hard-switching to soft-switching by introducing a resonant circuit that creates zero-voltage switching conditions. This parameter change reduces switching loss while maintaining the wide operation range through voltage feed-forward compensation that adapts to different operating conditions.
Solution Approach 2:
The patent introduces a resonant circuit as an intermediary between the DC input and AC output. This resonant circuit enables soft-switching by creating zero-voltage conditions before switching occurs, thereby reducing switching loss and extending the lifetime of switching elements while preserving operational flexibility.
2Adaptability or versatility
If hard-switching is used in active switching elements, then the inverter can operate with a wide range, but the lifetime of switching elements decreases due to switching surge
Solution Approach 1:
The patent changes the switching parameter from hard-switching to soft-switching by introducing a resonant circuit that creates zero-voltage switching conditions. This parameter change reduces switching stress and extends the lifetime of switching elements while maintaining the wide operation range through voltage feed-forward compensation.
Solution Approach 2:
The patent applies beforehand cushioning by using the resonant circuit to prepare zero-voltage conditions before switching occurs. This cushioning effect protects the switching elements from surge stress, extending their lifetime while preserving the flexible operation range through adaptive voltage compensation.
3Reliability
If DC-link capacitor is used, then the inverter can filter ripple current, but the inverter size increases and becomes less compact
Solution Approach 1:
The patent extracts and removes the DC-link capacitor from the traditional inverter topology by implementing soft-switching technology. The resonant circuit and voltage feed-forward compensation work together to eliminate ripple current issues without requiring a large capacitor, thereby reducing inverter size while maintaining reliability.
4Loss of energy
If voltage feed-forward compensation is implemented, then switching loss is reduced and DC-link capacitor can be removed, but the control system complexity increases
Solution Approach 1:
The patent changes the control parameter by implementing voltage feed-forward compensation that calculates appropriate switching voltages based on operating conditions. This parameter adjustment enables soft-switching and eliminates the need for DC-link capacitor, reducing switching loss while the increased control complexity is managed through systematic voltage calculation and regulation.
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 reduces switching loss, improves power conversion efficiency, and makes the inverter more compact by eliminating the DC-link capacitor, while extending the lifespan of switching elements.
Implementation Method 1
an inductor capable of storing energy
Implementation Method 2
the output inductor LO and the output capacitor CO construct a resonance circuit
Data Source
AI summary
The present invention discloses an apparatus for controlling an H-bridge DC-AC inverter, comprising an H-bridge DC-DC converting circuit capable of converting unstable DC power into stable DC power and a full-bridge DC-AC inverting circuit capable of inverting DC power output from the H-bridge DC-DC converting circuit into AC power. The H-bridge DC-DC converting circuit comprises: a first active switching element and a second active switching element; an inductor capable of storing energy; a first passive switching element and a second passive switching element; and a first capacitor and a second capacitor. The full-bridge DC-AC inverting circuit comprises: a third active switching element, a fourth active switching element, a fifth active switching element and a sixth active switching element; an output inductor; and an output capacitor.