Half Bridge Circuit Voltage Limiting Inductance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High performance synchronous buck converters face challenges in maintaining efficiency and reliability due to voltage overshoots during fast switching, which can exceed the safe operating area of devices, potentially leading to avalanche conditions.
Innovation Solution
A half bridge circuit with a voltage limiting inductance designed between the switch and diode, configured to keep voltage overshoots below the breakdown voltage, and a package with a bond wire connected clip that provides additional flexibility and space efficiency for circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the FETs are switched as fast as possible to achieve high conversion efficiency, then the conversion efficiency is improved, but voltage overshoots occur which may exceed the safe operating area and cause avalanche conditions
Solution Approach 1:
The patent applies beforehand cushioning by introducing a voltage limiting inductance (comprising a first inductance between the switch and diode, and a second inductance between the diode and output connection) that acts as a protective cushion against voltage overshoots. This inductance limits the rate of voltage change (di/dt) during switching transitions, preventing voltage spikes from exceeding the breakdown voltage of the FETs while allowing fast switching for high efficiency operation.
2Reliability
If a voltage limiting inductance is introduced to limit voltage overshoots, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the voltage limiting function with existing circuit elements by integrating the first inductance into the switch-diode connection and the second inductance into the diode-output connection. This combining approach incorporates voltage limiting protection into the standard half-bridge circuit topology without adding completely separate protection circuits, thereby limiting complexity increase while achieving reliable voltage overshoot protection.
3Reliability
If the voltage overshoot is limited by increasing inductance, then the reliability is improved, but the performance of the half bridge circuit is excessively limited
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the inductance values of the first and second inductances. The inductance values are chosen to provide sufficient voltage limiting protection (keeping overshoot below breakdown voltage) while minimizing the impact on switching speed and power loss. This optimization balances reliability improvement with performance maintenance, preventing excessive limitation of circuit productivity.
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
The solution effectively reduces voltage spikes in buck converters while maintaining high conversion efficiency, ensuring reliable operation by limiting overshoots without excessively impacting performance.
Implementation Method 1
a voltage limiting inductance designed and arranged between the switch and the diode and configured for limiting a voltage upon switching the switch
Data Source
AI summary
A half bridge circuit includes an input connection configured to supply an electric input, an output connection configured to supply an electric output to a load to be connected to the output connection, a switch and a diode arranged between the input connection and the output connection and a voltage limiting inductance arranged in series between the switch and the diode. The voltage limiting inductance is configured to limit, upon switching the switch, a maximum voltage across the switch to below a breakdown voltage of the switch. A corresponding method of operating the half bridge circuit and package are also described.