Dual Gate Solid State Switches for Reduced Switching Loss
Solution Overview
Problem
Solid state switches in electrified vehicles face switching losses and delayed transitions due to parasitic inductances, which are exacerbated by inductive coupling between power and control leads, affecting the performance of traction motors and DC-DC converters.
Innovation Solution
The implementation of a power module with a solid state switch having dual gate leads with distinct inductances for turn-on and turn-off, allowing independent tuning of common source inductances to reduce inductive voltage overshoot and enhance switching speed and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single gate lead with common inductance is used, then the device structure is simple, but switching losses increase and switching speed decreases due to inductive voltage overshoot
Solution Approach 1:
The gate lead is segmented into two separate gate leads (first gate lead and second gate lead), each with its own inductance (Lg1 and Lg2). This segmentation allows independent control of turn-on and turn-off switching processes, enabling optimization of switching losses for each transition direction without being constrained by a single common inductance value.
Solution Approach 2:
Different inductance values are assigned to different gate leads based on their specific functions. The first gate lead has inductance Lg1 optimized for turn-on switching, while the second gate lead has inductance Lg2 optimized for turn-off switching. This local quality differentiation allows each gate lead to be tailored for its specific switching direction, reducing overall switching losses.
2Speed
If common source inductance is used for both turn-on and turn-off, then the circuit design is simplified, but switching speed is limited due to inductive voltage overshoot
Solution Approach 1:
The gate control path is segmented into two separate paths with distinct inductances. The first gate lead provides a dedicated path for turn-on with inductance Lg1, while the second gate lead provides a dedicated path for turn-off with inductance Lg2. This segmentation eliminates the compromise required by common inductance design, allowing each switching transition to occur at optimal speed without inductive voltage overshoot limitations.
Solution Approach 2:
The inductance parameter is changed and differentiated for different switching directions. By setting Lg1 and Lg2 to different values, the circuit can optimize switching speed for both turn-on and turn-off operations. The parameter change allows each gate lead to be tuned for its specific function, improving overall switching speed performance.
3Productivity
If gate resistance and inductance are fixed, then the device manufacturing is simplified, but switching performance cannot be optimized for different operating conditions
Solution Approach 1:
The gate control circuit is segmented into two independent paths, each with its own resistance and inductance characteristics. This allows independent optimization of turn-on and turn-off performance, enabling the device to achieve higher power conversion efficiency by minimizing switching losses in both directions without requiring complex adjustable components.
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 reduces switching losses and improves switching speed, enabling more efficient power conversion and motor operation in electrified vehicles by optimizing the gate resistance and inductive coupling.
Implementation Method 1
a first gate lead coupled with the first gate and having a first inductance, and a second gate lead coupled with the first gate and having a second inductance greater than the first inductance
Data Source
AI summary
A vehicle includes an electric machine that provides propulsive force to the vehicle, and a power inverter that supplies power from a traction battery to the electric machine using a first and second switch configured as a half-bridge. The first switch has a first gate, a first gate lead coupled with the first gate and having a first inductance, and a second gate lead coupled with the first gate and having a second inductance greater than the first inductance.