Vehicle Power Converter Switching Frequency to Avoid EMI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power conversion apparatuses in vehicles face challenges in reducing size while maintaining high switching frequencies without causing communication interference, as increasing switching frequency leads to noise emissions that violate CISPR standards.
Innovation Solution
A power conversion apparatus with a switching circuit and control unit that sets the switching frequency and main frequency component of the ripple outside the communication frequency range, using multiple subcircuits with phase differences and wide-bandgap semiconductors to minimize noise and size, and incorporates a choke coil structure to reduce losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the switching frequency is increased to reduce the size of the power conversion apparatus, then the size and weight are reduced, but communication interference and noise emissions occur that violate CISPR standards
Solution Approach 1:
The patent applies parameter changes by carefully selecting and optimizing the switching frequency to fall within specific ranges (e.g., 200-500 kHz) that achieve miniaturization while avoiding communication bands. This involves adjusting electrical parameters such as switching frequency, duty cycle, and component values to balance size reduction with noise mitigation, allowing the apparatus to meet both compact form factor requirements and CISPR emission standards without additional countermeasures
2Productivity
If the switching frequency is increased to improve productivity and power density, then the power conversion efficiency and density are improved, but radiation noise increases causing communication interference
Solution Approach 1:
The patent utilizes parameter changes by optimizing the switching frequency and duty cycle parameters to achieve high power conversion efficiency and density while controlling radiation noise. By selecting specific switching frequency ranges and adjusting duty cycle values, the system maintains high productivity and power density without generating excessive radiation noise that would interfere with vehicle-mounted receivers
3Volume of moving object
If high switching frequency is used to reduce the size of magnetic components, then the apparatus size is reduced, but noise filter characteristics deteriorate and communication interference occurs
Solution Approach 1:
The patent applies parameter changes by selecting optimal switching frequencies that work effectively with the noise filter characteristics of the magnetic components. By coordinating the switching frequency with the resonant frequencies and impedance characteristics of the magnetic components and filters, the system achieves miniaturization while maintaining reliable noise filtering and avoiding communication interference
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
Enables high-frequency switching operations without communication interference, reducing the size and weight of the power conversion apparatus while adhering to CISPR standards without additional noise countermeasures, and effectively using existing semiconductor devices.
Implementation Method 1
A power conversion apparatus such as a DC-DC converter uses a switching circuit that includes a semiconductor switching element. The switching operation of the switching circuit that is performed at a high frequency causes a noise.
Implementation Method 2
incorporates a choke coil structure to reduce losses
Data Source
AI summary
A power conversion apparatus includes a switching circuit including multiple switching elements, and a control unit configured to control and switch the multiple switching elements included in the switching circuit at a predetermined switching frequency with a direct current voltage applied to an input terminal of the switching circuit. The switching circuit is configured to convert the direct current voltage applied to the input terminal and to output a converted electric current. The switching frequency is set such that the switching frequency and a main frequency component of a ripple occurring in the electric current are out of a frequency range used for communication with a vehicle-mounted receiver.