Solid-State Circuit Breaker Bond-Wire Inductance for Overvoltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid state circuit breakers (SSCBs) experience high overvoltages due to high di/dt during fault current interruption, which can be detrimental and are not effectively managed by conventional snubber circuits, especially when minimizing switching time.
Innovation Solution
Incorporating a magnetic body in proximity to bond wires to increase the magnetic field and induce additional inductance, reducing overvoltage by adding inductance in series with the power die and gate driver loop, thereby slowing the rate of current change and reducing the discharge rate of internal gate capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If gate resistance is minimized to reduce switching time, then switching time is reduced, but overvoltage increases
Solution Approach 1:
The patent introduces a magnetic body as an intermediary element positioned near the bond wires to generate additional inductance. This inductance acts as a mediator that opposes the rapid current change (di/dt) caused by low gate resistance, thereby reducing the overvoltage spike while allowing the gate resistance to remain low for fast switching.
Solution Approach 2:
The patent changes the inductance parameter of the circuit by introducing a magnetic body with specific magnetic properties (permeability in the range of 1-100 CGS units). This parameter change adds inductance in series with the power die, which modifies the circuit's response to rapid current changes and reduces the overvoltage penalty associated with fast switching.
2Object-affected harmful factors
If a large snubber circuit is used to accommodate overvoltage, then overvoltage is reduced, but device complexity and size increase
Solution Approach 1:
The patent extracts the inductance function from the traditional RC snubber circuit and implements it separately through a magnetic body positioned near the bond wires. This separation allows the snubber capacitor to be smaller while achieving the same overvoltage protection, as the magnetic body provides the inductive component without requiring large physical components.
Solution Approach 2:
The patent moves the inductance generation from the circuit board plane to the spatial dimension by positioning a magnetic body in three-dimensional space near the bond wires. This dimensional change allows inductance to be generated without occupying additional PCB area, effectively reducing the overall footprint of the protection circuit.
3Object-affected harmful factors
If inductance is added to reduce overvoltage, then overvoltage is reduced, but switching time increases
Solution Approach 1:
The patent applies inductance locally at the bond wire region near the power die rather than throughout the entire circuit. By positioning the magnetic body specifically where the bond wires carry the highest di/dt, the inductance is applied only where needed to suppress overvoltage, while minimizing the impact on overall switching performance.
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 enhanced SSCB structure effectively reduces overvoltage and switching time, allowing faster response to faults while protecting the power die from damage, and enables the use of lower gate resistance without increased overvoltage penalties.
Implementation Method 1
The at least one magnetic body is attached to the power substrate and disposed to increase a magnetic field produced by a current flowing through the bond wires and thereby produce a first inductance
Implementation Method 2
produce a first inductance that produces a decrease in an overvoltage at turn off of the power die
Data Source
AI summary
A solid state circuit breaker structure and electronic switching circuit is provided. The solid state circuit breaker structure includes a power substrate, a power die, a plurality of bond wires, and a magnetic body. The power die is mounted on the power substrate. The bond wires extend outwardly from the power die. The magnetic body is attached to the power substrate and disposed to increase a magnetic field produced by a current flowing through the bond wires and thereby produce a first inductance that produces a decrease in an overvoltage at turn off of the power die.