Power Conversion Circuit Board for Electric Compressor Noise Reduction
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Solution Overview
Problem
In-vehicle electric compressors face challenges with high voltage requirements and electromagnetic noise interference, necessitating a solution that reduces noise impact on external devices while maintaining space-saving design and high breakdown resistance.
Innovation Solution
A power conversion circuit board with a series capacitor group mounted between power supply and ground wiring, dividing voltage and enhancing resistance, and using different impedance characteristics to control noise across various frequencies, integrated with a high voltage circuit and low voltage circuit on the same board surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitor element is used in the high voltage circuit, then the circuit structure is simple, but the voltage resistance performance is insufficient for high voltage applications
Solution Approach 1:
The capacitor element is divided into multiple series-connected sub-capacitors (first, second, and third series capacitors). This segmentation allows the high voltage to be distributed across multiple components, with each sub-capacitor experiencing a portion of the total voltage, thereby improving voltage resistance performance while maintaining a manageable circuit structure.
2Power
If high voltage is applied to the compressor system, then the power supply capability is enhanced, but electromagnetic noise increases and affects external devices
Solution Approach 1:
A common mode choke is introduced as an intermediary component in the high voltage circuit. This choke acts as a mediator that allows the high voltage power supply to function while simultaneously filtering and reducing electromagnetic noise, preventing it from affecting external devices. The common mode choke serves dual purposes: maintaining power supply capability and suppressing harmful electromagnetic interference.
3Volume of moving object
If the compressor, motor, and circuit board are integrated, then the space-saving property is enhanced, but the electromagnetic noise from the circuit board increases
Solution Approach 1:
The high voltage circuit is extracted and separately configured on the circuit board, distinct from the low voltage control circuits. This separation allows the high voltage circuit to be optimized with specific noise reduction components (series capacitors and common mode choke) without affecting the integrated compact design. The extracted high voltage circuit configuration reduces electromagnetic noise while maintaining the overall space-saving integrated compressor structure.
4Strength
If the breakdown voltage is increased to handle high voltage input, then the voltage handling capability is improved, but the circuit becomes more complex and harder to manufacture
Solution Approach 1:
The capacitor element is segmented into multiple series-connected sub-capacitors with standard voltage ratings. This segmentation achieves the required high breakdown voltage through series connection of standard components, avoiding the need for single high-voltage custom components that would be difficult to manufacture. The segmented approach maintains ease of manufacture while achieving high voltage handling capability.
Solution Approach 2:
The circuit design changes the voltage distribution parameters by connecting capacitors in series, transforming the voltage handling requirement from a single high-voltage component into multiple lower-voltage components. This parameter change allows the use of standard voltage-rated components, simplifying manufacturing while achieving the required overall breakdown voltage for high voltage input handling.
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 solution effectively reduces electromagnetic noise and achieves high breakdown voltage, maintaining space efficiency and preventing noise interference with external devices.
Implementation Method 1
a series capacitor group including a plurality of capacitor elements connected in series between a power supply wiring and a ground wiring
Implementation Method 2
each of the capacitor elements forming the series capacitor group has different impedance characteristics which enable reduction of electromagnetic noise at a plurality of frequencies
Data Source
AI summary
A power conversion circuit board is a board on which a power conversion circuit which converts direct current to alternating current is mounted. A low voltage circuit to which a low voltage is applied and a high voltage circuit to which a high voltage is applied are separately disposed in different areas on the same board surface. Further, in the high voltage circuit, a part of a wiring is formed on the board surface, and another wiring includes a bus bar which is provided with a predetermined distance from the board surface.