Power Module Drive Circuit Parasitic Oscillation Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In motor drive inverters, parasitic oscillation in the gate voltage of switching elements leads to erroneous switching states and potential device failure, particularly due to high driving impedance caused by long ground wiring, which worsens with increasing switching frequency and current levels.
Innovation Solution
A power module with a built-in drive circuit incorporates a control ground switching circuit that dynamically switches the ground wiring impedance based on current detection, using a dumping resistor to increase impedance when high currents are detected, thereby reducing parasitic oscillation and optimizing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If long ground wiring is used to connect ground terminals, then the power module structure is simplified and ease of manufacture is improved, but the driving impedance increases causing parasitic oscillation and reliability deteriorates
Solution Approach 1:
The ground connection path is segmented into multiple separate ground terminals (first ground terminal, second ground terminal, third ground terminal) instead of using a single long ground wiring. This segmentation reduces the loop area and inductance, thereby reducing parasitic oscillation while maintaining manufacturing simplicity.
Solution Approach 2:
A dumping resistor is introduced as an intermediary component connected between the second ground terminal and third ground terminal. This resistor acts as a damping element that suppresses parasitic oscillation by providing a controlled impedance path, resolving the contradiction between simplified structure and reduced oscillation.
2Reliability
If ground wiring impedance is increased to suppress parasitic oscillation, then reliability is improved, but switching losses increase and energy efficiency deteriorates
Solution Approach 1:
The ground wiring impedance is made dynamic rather than fixed. The dumping resistor is selectively activated or deactivated based on operating conditions, allowing the impedance to adapt: high impedance when parasitic oscillation is present (improving reliability), and low impedance during normal operation (minimizing switching losses).
Solution Approach 2:
The impedance parameter of the ground connection is changed by introducing the dumping resistor with specific resistance value. This parameter change provides damping for parasitic oscillation suppression while the resistance value is optimized to minimize impact on switching losses, achieving a balance between reliability and energy efficiency.
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 solution effectively suppresses parasitic oscillation and optimizes switching losses by adjusting ground wiring impedance according to current levels, ensuring stable operation and reducing the risk of switching element failure.
Implementation Method 1
parasitic oscillation in the gate voltage of switching elements leads to erroneous switching states and potential device failure
Implementation Method 2
high driving impedance caused by long ground wiring, which worsens with increasing switching frequency and current levels
Implementation Method 3
A power module with a built-in drive circuit incorporates a control ground switching circuit that dynamically switches the ground wiring impedance based on current detection
Data Source
AI summary
A power module including a half bridge circuit having first and second switching elements respectively included in an upper arm and a lower arm thereof, and upper and lower arm drive circuits which respectively drive the first and second switching elements. The power module includes a first ground terminal on a ground side of the second switching element, a second ground terminal connected, via a first ground wiring, to the first ground terminal, a third ground terminal connected, via a second ground wiring including a dumping resistor, to the first ground terminal, a current detection circuit detecting a current flowing through the second switching element, and a control ground switching circuit which performs switching according to a value of the current detected by the current detection circuit, so as to connect a ground terminal of the lower arm drive circuit to the second or third ground terminal.