Inverter Stray Capacitance Balancing for EMI Reduction
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Solution Overview
Problem
Conventional pulse-controlled inverters face challenges in minimizing electromagnetic interference emissions due to stray capacitances and inductances, which require complex symmetrical designs of sub-components to suppress common-mode interference, making it difficult to use inexpensive and asymmetric power modules without increased interference emissions.
Innovation Solution
The design balances stray capacitances and inductances across all components of the pulse-controlled inverter, allowing for the use of inexpensive, asymmetric power modules by compensating for asymmetries in the input circuit and busbar arrangement, ensuring cumulative symmetry at the commutation circuit level without requiring complex symmetrical sub-component designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If symmetrical design of sub-components is implemented to suppress common-mode interference, then electromagnetic interference emissions are minimized, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent divides the inverter system into separate functional modules (input circuit, busbar arrangement, power module) and allows each to have asymmetric stray variables, compensating for asymmetries across the entire system rather than requiring symmetry at the component level
Solution Approach 2:
The patent allows different parts of the system (input circuit, busbar, power module) to have different, asymmetric stray capacitance and inductance values, rather than requiring uniform symmetry across all components
2Object-generated harmful factors
If symmetrical design of sub-components is implemented to suppress common-mode interference, then electromagnetic interference emissions are minimized, but manufacturing cost increases due to expensive symmetrical power modules
Solution Approach 1:
The patent enables the use of inexpensive, asymmetric power modules by compensating for their asymmetries through the overall system design, rather than requiring expensive symmetric modules
Solution Approach 2:
The patent combines multiple asymmetric components (input circuit, busbar arrangement, power module) into an overall system where the stray variables compensate for each other, achieving symmetry at the system level rather than requiring symmetry at the component level
Data Source
Figure 1~2
AI summary
The invention relates to a pulse-controlled inverter (1) having an input circuit (2) that is designed to provide an input DC voltage (5) between a high-side input (2a) and a low-side input (2b), wherein the input circuit (2) has a first high-side stray capacitance (21a), a first low-side stray capacitance (21b), a first high-side stray inductance (22a, 22a') and a first low-side stray inductance (22b, 22b'); having a busbar arrangement (3) that is designed to electrically connect the high-side input (2a) to a high-side connection (4a) and to electrically connect the low-side input (2b) to a low-side connection (4b), wherein the busbar arrangement (3) has second stray capacitances (31a, 31b) and second stray inductances (32a, 32b); and having an n-phase inverter module (4), n>l, that is electrically coupled to the high-side connection (4a) and to the low-side connection (4b) and is designed to convert the input DC voltage (5) into an n-phase output AC voltage (6), wherein the inverter module (4) has third stray capacitances (41a, 41b) and third stray inductances (42a, 42b); wherein the sum of the high-side stray capacitances (21a, 31a, 41a) is equal to the sum of the low-side stray capacitances (21b, 31b, 41b) and the sum of the high-side stray inductances (22a, 22a', 32a, 42a) is equal to the sum of the low-side stray inductances (22b, 22b', 32b, 42b).