Parallel Switching Driver Feedback Using Combined Back-EMF
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Solution Overview
Problem
In power conversion devices with switching elements connected in parallel, variations in operation lead to difficulties in reducing power loss and surge due to inconsistent feedback using counter-electromotive force.
Innovation Solution
A power conversion device configuration that combines the counter-electromotive forces from two switching elements and adds this combined force to an external command voltage, allowing synchronized operation and feedback to reduce power loss and surge, with a simplified driver circuit design that eliminates the need for separate feedback input terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switching elements are connected in parallel to supply larger current, then current capacity increases, but variations in element operation cause inconsistent feedback and increase power loss and surge
Solution Approach 1:
The patent combines the counter-electromotive forces from multiple switching elements by connecting their detection terminals through a common connection line to a single addition circuit. This merging approach allows the feedback signal to represent the combined state of all parallel switching elements, ensuring consistent control and reducing power loss despite variations in individual element operations.
Solution Approach 2:
The patent implements feedback by detecting the counter-electromotive force produced by the parasitic inductance in each switching element, combining these forces through the common connection line, and feeding the combined signal back to the addition circuit which adjusts the gate voltage accordingly. This feedback mechanism compensates for variations in switching element operations, maintaining synchronized control and reducing both power loss and surge current.
2Measurement precision
If separate feedback circuits are used for each switching element to handle variations, then control precision improves, but device complexity increases
Solution Approach 1:
The patent merges multiple feedback paths into a single common connection line that collects counter-electromotive forces from all switching elements and delivers them to one addition circuit. This consolidation maintains the precision needed to handle variations in each element's operation while significantly reducing the complexity of the driver circuit compared to having separate feedback circuits for each switching element.
Solution Approach 2:
The common connection line serves multiple functions simultaneously: it acts as a detection line for counter-electromotive forces, a combination circuit for merging signals from multiple switching elements, and a feedback path to the addition circuit. This multi-functionality eliminates the need for separate dedicated circuits for each switching element, reducing overall system complexity while maintaining control precision.
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 configuration enables efficient reduction of power loss and surge even with variations in switching element operation, while maintaining a simple driver circuit configuration by using a common connection line to feed back the combined counter-electromotive force.
Implementation Method 1
a first parasitic inductance Ls1 through which the first applied current Id1 flows and a first detection terminal 24a used to detect a first counter-electromotive force Vb1, the first counter-electromotive force Vb1 being produced by a first inductance component L1 that includes the first parasitic inductance Ls1
Data Source
AI summary
A power conversion device includes two lower arm switching elements connected in parallel to each other and a lower arm driver circuit that drives the two lower arm switching elements. The two lower arm switching elements respectively include gate terminals and detection terminals used to detect counter-electromotive forces. The power conversion device includes a common connection line that connects the two detection terminals to each other and connects the two detection terminals to an addition circuit of the lower arm driver circuit. A combined electromotive force is transmitted via the common connection line.