Power Conversion Device Switch Driver Control
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Solution Overview
Problem
The existing power conversion devices using MOSFETs with a super-junction structure face efficiency deterioration due to arm punch through of recovery current, which leads to losses and potential damage to switching elements.
Innovation Solution
A power conversion device with a switch driver that controls switching patterns to prevent arm punch through by reversing the current direction of switching elements and using zero-crossing operations to manage the cycle lengths of intervals, thereby suppressing the generation of recovery current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MOSFETs with super-junction structure are used in power conversion devices, then cost advantages are maintained, but efficiency deteriorates due to arm punch through of recovery current
Solution Approach 1:
The patent applies preliminary action by reversing the current direction through switching elements before the recovery current can cause arm punch through. The switching pattern controller executes a first switching pattern that reverses current flow through the first switching element, and a second switching pattern that reverses current through the second switching element, preventing the harmful recovery current effect before it occurs.
Solution Approach 2:
The patent implements periodic action through controlled zero-crossing operations. The switching pattern controller periodically switches between different patterns (first, second, and third switching patterns) based on current direction, creating periodic current reversals that prevent arm punch through while maintaining continuous operation. This periodic switching ensures that recovery current is managed at regular intervals.
2Loss of energy
If additional resonant circuits are added to prevent arm punch through, then efficiency improves, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical/resonant circuit approach with an electronic control approach. Instead of adding resonant circuits with inductors and capacitors to manage recovery current, the invention uses a switching pattern controller that electronically manages current direction through MOSFETs. This substitution eliminates the need for additional resonant components while achieving the same protective function.
Solution Approach 2:
The patent changes the operational parameters of existing switching elements rather than adding new components. By modifying the switching patterns and timing of existing MOSFETs through the switching pattern controller, the system achieves arm punch through prevention without increasing device complexity. The parameter changes involve controlling gate signals to reverse current direction at appropriate times.
Data Source
AI summary
A power conversion device includes a switching circuit and a switch driver. The switching circuit includes a plurality of switching elements including a first switching element and a second switching element that are electrically coupled in series. The switch driver includes a first, a second, and a third switching pattern controller. The first switching pattern controller executes a first switching pattern which is set such that a current in a reverse direction flows through the first switching element and the second switching element is off. The second switching pattern controller executes a second switching pattern which is set such that a direction of the current flowing through the first switching element is switched to a forward direction from the reverse direction. The third switching pattern controller executes a third switching pattern which is set such that the first switching element is off and the second switching element is on.