Soft Switched Voltage Source Inverter With ZVS Network
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High switching frequency applications in uninterruptible power supplies (UPS) face challenges with silicon devices like IGBT and MOSFET switches, which experience poor switching performance and require complex timing controls, while SiC or GaN FET switches are expensive and increase costs.
Innovation Solution
The implementation of a zero-voltage switching (ZVS) inverter with resonant ZVS networks using silicon devices, such as MOSFETs and IGBTs, to provide soft switching with less complex timing controls, reduced conduction losses, and minimal EMI noise, enabling efficient power conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If silicon devices (IGBT and MOSFET) are used in high switching frequency applications, then the inverter can operate at high switching frequencies, but the switching performance deteriorates and complex timing controls are required
Solution Approach 1:
The ZVS network performs preliminary action by resonating the parasitic capacitance of the switches before the main switching event occurs. The auxiliary switches and inductors are activated in advance to charge or discharge the parasitic capacitance, ensuring that the voltage across the main switch reaches zero before it turns on, thereby achieving soft switching and improving switching performance at high frequencies
Solution Approach 2:
The ZVS network acts as an intermediary between the DC source and the main switches. It includes auxiliary switches, diodes, and inductors that mediate the switching process by providing a resonant path for the parasitic capacitance, isolating the main switches from the harsh switching transients and enabling them to operate reliably at high frequencies
2Reliability
If SiC or GaN FET switches are used to achieve soft switching, then switching performance improves, but the cost increases
Solution Approach 1:
The invention uses inexpensive silicon-based IGBT and MOSFET switches instead of expensive SiC or GaN FETs. The ZVS network components (auxiliary switches, diodes, and inductors) are designed to be cost-effective and are used temporarily during the switching transition to achieve soft switching, after which the main silicon switches take over the power handling duty
Solution Approach 2:
The invention changes the operating parameters of silicon devices by implementing zero-voltage switching through the ZVS network. This allows silicon IGBTs and MOSFETs to operate in a regime where their switching losses are minimized and their performance approaches that of wide-bandgap devices, without requiring a change in the fundamental material properties
3Device complexity
If conventional switching is used, then the inverter structure is simpler, but conduction losses increase and EMI noise is generated
Solution Approach 1:
The ZVS network utilizes electromagnetic resonance (analogous to mechanical vibration) to oscillate the parasitic capacitance at a specific frequency. By timing the main switch operation to coincide with the zero-voltage points of this resonant oscillation, the inverter achieves soft switching that reduces conduction losses and minimizes EMI noise generation
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 solution enables efficient power conversion with improved power density and reduced costs by using silicon devices in ZVS inverters, achieving performance similar to wide-bandgap device-based inverters while minimizing reverse recovery transients and EMI/RFI.
Implementation Method 1
the ZVS network including at least two inductors configured to resonate with the parasitic capacitance of at least one switch of the plurality of switches to provide soft switching
Data Source
AI summary
According to at least one aspect of the disclosure, an inverter is provided comprising an input configured to receive input DC power from a DC source, an output configured to provide output AC power to a load, a plurality of DC rails coupled to the input and configured to receive the input DC power from the DC source, a plurality of switches coupled between the plurality of DC rails and configured to convert the input DC power into the output AC power, each switch of the plurality of switches having a parasitic capacitance, and at least one ZVS network coupled across at least two switches of the plurality of switches, the ZVS network including at least two inductors configured to resonate with the parasitic capacitance of at least one switch of the plurality of switches to provide soft switching of at least one switch of the plurality of switches.