Inverter Load-Relieving Circuit for Switching Loss Reduction
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Solution Overview
Problem
Existing inverter technologies face inefficiencies due to high switching loads on main switches, which limit power density and efficiency, especially in photovoltaic inverters.
Innovation Solution
A method and circuit design for an inverter with a load-relieving circuit between the main switch and the midpoint of series-connected capacitors, utilizing a bidirectional circuit of switches and inductance to alternately switch on/off switches, allowing the main switch to be turned on voltage-free, and adjusting switch times based on intermediate and partial voltage ratios to achieve a 2:1 voltage ratio, thereby reducing switching loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a load-relieving circuit with auxiliary voltage source is added to reduce switching load on the main switch, then efficiency and power density are improved, but device complexity and cost increase due to additional components
Solution Approach 1:
The load-relieving circuit is designed to perform multiple functions: it provides voltage clamping during switch transitions, supplies auxiliary voltage for gate drive, and enables soft switching. By making the circuit multi-functional, the patent reduces the need for separate auxiliary components, thereby limiting the increase in device complexity while achieving significant reduction in switching losses.
Solution Approach 2:
The load-relieving circuit is designed to generate its own auxiliary voltage through the action of the main switch and circuit inductance, eliminating the need for external auxiliary voltage sources. The circuit uses the existing intermediate circuit voltage and inductance to create the required voltage for driving the main switch, making the system self-sufficient and avoiding additional power-consuming components.
2Stability of the object's composition
If switch-on time of the second switch is extended to achieve better voltage balance, then capacitor voltage symmetry is improved, but switching frequency and power density are reduced
Solution Approach 1:
The patent implements voltage detection circuits that continuously monitor the voltages across the series-connected capacitors. Based on the detected voltage imbalance, the control system adjusts the switch-on time of the second switch dynamically. This feedback mechanism allows the system to maintain capacitor voltage symmetry while adapting the switching timing to preserve high switching frequency and power density.
Solution Approach 2:
The switch-on time of the second switch is not fixed but dynamically adjusted based on real-time voltage conditions. The control system modifies the timing parameters adaptively to achieve voltage balance, allowing the system to maintain both symmetry and high switching frequency without being constrained by static timing requirements.
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 minimizes auxiliary voltage requirements, reduces losses and costs, maintains symmetrical capacitor voltages, and enhances efficiency by optimizing switching times and energy balance, resulting in improved power density and efficiency.
Implementation Method 1
a bidirectional circuit of two switches and an inductance in series
Implementation Method 2
two series-connected capacitors in the intermediate circuit
Data Source
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AI summary
The invention relates to a method for regulating an inverter and to an inverter with a DC/DC stage, which comprises at least one main switch (S2) and a discharge circuit, and with a DC/AC stage. The discharge circuit is formed by a series connection of a bidirectional switching element, which comprises two switches (SA1, SA2), and an inductor. A device is provided for regulating the switch (SA1, SA2) and is designed such that one switch (SA1, SA2) is activated in an alternating manner and the switch-on time of the switch is determined by the regulating device prior to a switch-off time of the main switch (S2).