Semiconductor Module Surge Voltage Reduction via Segmented Wiring
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Solution Overview
Problem
In semiconductor modules with freewheeling diodes, surge voltage at turn-off is a concern that existing technologies fail to address without increasing switching loss during the Miller period.
Innovation Solution
A semiconductor module design where the anode electrode of the high-side freewheeling diode is directly connected to the reference voltage electrode of the high-side driver circuit via a first wiring with inductance, and also connected to the reference voltage electrode of the high-side switching device via a second wiring, allowing for magnetic coupling to reduce surge voltage at turn-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gate resistance is increased to reduce surge voltage at turn-off, then surge voltage is reduced, but switching loss during the Miller period increases
Solution Approach 1:
The patent segments the reference voltage connection path into two separate wiring paths: one connecting the driver circuit reference voltage terminal to the freewheeling diode anode, and another connecting the switching device reference voltage terminal to the freewheeling diode anode. This segmentation allows independent optimization of each path's inductance to simultaneously reduce surge voltage and minimize switching loss.
Solution Approach 2:
The patent applies local quality by assigning different inductance characteristics to different parts of the circuit. Specifically, the wiring between the driver circuit and freewheeling diode is designed with one inductance value, while the wiring between the switching device and freewheeling diode is designed with a different inductance value, allowing each local region to have optimal electrical characteristics for its specific function.
2Object-affected harmful factors
If inductance is increased to reduce surge voltage, then surge voltage is reduced, but the time rate of change of collector current increases
Solution Approach 1:
The patent segments the inductance into two separate wiring inductances: L1 for the driver circuit path and L2 for the switching device path. By controlling the ratio L1/L2, the patent can reduce surge voltage while managing the time rate of change of collector current, as the segmented inductances allow independent control of voltage suppression and current transition characteristics.
Solution Approach 2:
The patent changes the electrical parameters of the wiring by carefully selecting the inductance values L1 and L2. By adjusting these inductance parameters and their ratio, the patent optimizes the balance between surge voltage reduction and control of the collector current's time rate of change, achieving both goals simultaneously.
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 design effectively reduces surge voltage at turn-off without increasing switching loss during the Miller period, utilizing the inductance and magnetic coupling to enhance the reduction in gate drive capability and slope di/dt.
Implementation Method 1
allowing for magnetic coupling to reduce surge voltage at turn-off
Data Source
AI summary
A semiconductor module includes a high-side switching device and a low-side switching device that respectively form an upper arm and a lower arm, freewheeling diodes that are respectively connected to the switching devices in anti-parallel, and a high-side driver circuit and a low-side driver circuit that respectively switch the high-side switching device and the low-side switching device ON and OFF. In the upper arm, an anode electrode of the freewheeling diode and a reference voltage electrode of the high-side driver circuit are directly connected via a first wiring, and the anode electrode of the freewheeling diode is connected to a reference voltage electrode of the high-side switching device via a second wiring having an inductance.