Parallel Power Semiconductor Driving Circuit for SOA Switching Control
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Solution Overview
Problem
Conventional voltage converters with cascode connections suffer from increased on-resistance, leading to poor switching efficiency due to the connection of high-side and low-side power semiconductor elements.
Innovation Solution
A driving circuit that generates control signals for parallel-connected power semiconductor elements, utilizing time delay circuits and control logic to manage safe operation areas (SOA) based on temperature, ensuring optimal switching sequences and reduced on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If power semiconductor elements are connected in cascode connection to achieve high-voltage withstanding capability, then voltage withstanding capability is improved, but on-resistance increases resulting in poor switching efficiency
Solution Approach 1:
The power semiconductor elements are segmented into multiple units (first and second power semiconductor elements) that are connected in parallel rather than in cascode connection. This segmentation allows each element to handle a portion of the voltage and current, achieving high-voltage withstanding capability while maintaining low on-resistance and high switching efficiency.
2Loss of energy
If power semiconductor elements are connected in parallel to reduce on-resistance, then switching efficiency is improved, but control complexity increases due to SOA management
Solution Approach 1:
The driving circuit performs preliminary actions by pre-managing the safe operation areas (SOA) of parallel-connected power semiconductor elements through temperature-based reference voltages and time delay control. This preliminary management of switching sequences and SOA constraints simplifies the overall control complexity while maintaining high switching efficiency.
Solution Approach 2:
The driving circuit incorporates feedback mechanisms by monitoring temperature through temperature sensors and adjusting control signals based on temperature-dependent reference voltages. This feedback loop enables automatic SOA management of parallel power semiconductor elements, reducing control complexity while optimizing switching efficiency.
3Reliability
If temperature-based reference voltages are used to manage SOA, then reliability is improved, but device complexity increases due to additional temperature sensors and circuits
Solution Approach 1:
The time delay circuit serves multiple functions: it provides time delay for switching sequence control, generates temperature-dependent reference voltages for SOA management, and coordinates the operation of parallel power semiconductor elements. This multi-functionality reduces the need for separate dedicated circuits, thereby improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The patent merges the temperature sensing function, reference voltage generation, and time delay control into an integrated driving circuit. By combining these functions, the circuit achieves reliable temperature-based SOA management without proportionally increasing device complexity, as shared components serve multiple purposes.
Data Source
AI summary
A driving circuit is provided for providing first and second control signals to respective control electrode of first and second power semiconductor elements coupled in parallel. A range of a safe operation area (SOA) of the first power semiconductor element is larger than that of the second power semiconductor element. The driving circuit compares a voltage level of the second control signal with a first reference voltage or compares a drain-source voltage of the first power semiconductor element with a second reference voltage, and further generates a first voltage according to the comparison result. The first and second reference voltages are related to a temperature of the first and second power semiconductor elements. The driving circuit generates a logic signal according to the first voltage and further generates the first or second control signal according to the logic signal.