Power Module Stray-Capacitance Layout for Internal Noise Reduction
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Solution Overview
Problem
Existing power modules require additional noise measurement components to reduce normal-mode and common-mode noise, which complicates the design and increases the risk of erroneous operations in motor drive circuits.
Innovation Solution
The power module incorporates a configuration with upper- and lower-arm switching devices and dielectric members having different stray capacitances, allowing noise to be collected and reduced within the module without additional noise-measurement components, utilizing pseudo-capacitors that act as routes for normal-mode and common-mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional noise measurement components (X capacitors and Y capacitors) are added to reduce normal-mode and common-mode noise, then noise reduction effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent extracts the noise measurement function from external capacitors and relocates it to dielectric members integrated within the power module structure. The first dielectric member (1c) positioned between input electrodes A and B provides normal-mode noise measurement, while the second dielectric member (1d) positioned between input electrode A and ground provides common-mode noise measurement, eliminating the need for external X and Y capacitors.
Solution Approach 2:
The patent merges the noise measurement function with the existing structural components of the power module. The dielectric members that are already present for electrical insulation are designed to also serve as noise measurement elements, combining multiple functions into single components and thereby reducing overall device complexity.
2Reliability
If additional noise measurement components are added to reduce noise, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent combines the noise measurement function with existing dielectric members in the power module structure. Since these dielectric members are already integral parts of the module requiring precise manufacturing for electrical insulation, adding the noise measurement function to them does not increase manufacturing precision requirements, whereas adding separate external capacitors would require additional precision in their installation and connection.
3Object-affected harmful factors
If dielectric members with different stray capacitances are positioned strategically, then noise collection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different stray capacitance characteristics to different dielectric members based on their specific positions and functions. The first dielectric member (1c) has a first stray capacitance optimized for normal-mode noise collection between input electrodes, while the second dielectric member (1d) has a second stray capacitance optimized for common-mode noise collection between input electrode and ground, with each capacitance value tailored to its local noise measurement requirement.
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 effectively reduces noise within the power module, simplifying the design and improving the reliability and fabrication yield of motor drive circuits by eliminating the need for physical capacitors.
Implementation Method 1
a first dielectric member (1c) having a first stray capacitance and located between the first and second input portions, and a second dielectric member (1d) having a second stray capacitance and located between at least one of the first and second input portions and a cooling member (3, 4)... the first stray capacitance is different from the second stray capacitance... enables noise, such as normal-mode noise or common-mode noise, to be collected in the power module
Data Source
AI summary
In a power module, an upper-arm switching device and a lower-arm switching device are provided. The lower-arm switching device is located to face the upper-arm switching device. A first dielectric member, which has a first stray capacitance, is located in a space defined by the upper-arm switching device and the lower-arm switching device. A second dielectric member, which has a second stray capacitance, is located to be separated from the space. The second stray capacitance is different from the first stray capacitance.