Improved Calculation Method of Coupling Factors for Low-Frequency Wireless Power Transfer Systems.

International journal of environmental research and public health · 2021 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 5661

Study snapshot

PublicationInternational journal of environmental research and public health · 2021

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

The concept of a coupling factor was introduced in International Electrotechnical Commission (IEC) 62311 and 62233 to provide a product safety assessment that considers the localized exposure when an electromagnetic field (EMF) source is close to the human body. To calculate the coupling factors between the human body and EMF source, a numerical calculation should be carried out to calculate the internal quantities of the human body models. However, at frequencies below 10 MHz, the computed current density or internal electric field has computational artifacts from segmentation or discretization errors. Specifically, coupling factors are calculated based on the maximum values, which may include computational artifacts due to abnormal peaks. In this study, we propose an improved calculation method to remove computational artifacts by applying the 99.99th percentile in calculating the coupling factors without underestimation. The performance of the proposed method is verified through a comparison based on various human body models with wireless power transfer (WPT) systems and compliance with the reference levels and basic restrictions. The results indicate that the proposed method can provide uniform coupling factors by reducing the computational errors by up to 65.3% compared to a conventional method.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureRF

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

The study proposes calculating coupling factors using the 99.99th percentile rather than maximum values to reduce computational artifacts in human body model simulations below 10 MHz. Compared with a conventional method, the proposed approach reduced computational errors by up to 65.3% and produced more uniform coupling factors across various human body models and WPT system scenarios.

Outcomes measured

Coupling factor calculation method performance (artifact reduction)
Computational error reduction in internal quantities (current density/internal electric field)
Compliance assessment approach relative to reference levels and basic restrictions

Limitations

Specific frequencies (within <10 MHz) are not provided in the abstract.
No details are given on the number/types of human body models or WPT configurations used.
Outcomes are methodological/computational; no health outcomes are assessed.

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "RF",
    "source": "wireless power transfer (WPT) systems",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Coupling factor calculation method performance (artifact reduction)",
    "Computational error reduction in internal quantities (current density/internal electric field)",
    "Compliance assessment approach relative to reference levels and basic restrictions"
  ],
  "main_findings": "The study proposes calculating coupling factors using the 99.99th percentile rather than maximum values to reduce computational artifacts in human body model simulations below 10 MHz. Compared with a conventional method, the proposed approach reduced computational errors by up to 65.3% and produced more uniform coupling factors across various human body models and WPT system scenarios.",
  "effect_direction": "unclear",
  "limitations": [
    "Specific frequencies (within <10 MHz) are not provided in the abstract.",
    "No details are given on the number/types of human body models or WPT configurations used.",
    "Outcomes are methodological/computational; no health outcomes are assessed."
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "coupling factor",
    "IEC 62311",
    "IEC 62233",
    "localized exposure",
    "human body models",
    "wireless power transfer",
    "low frequency",
    "computational artifacts",
    "segmentation error",
    "discretization error",
    "99.99th percentile",
    "reference levels",
    "basic restrictions"
  ],
  "suggested_hubs": [
    {
      "slug": "who-icnirp",
      "weight": 0.42,
      "reason": "Discusses compliance concepts (reference levels/basic restrictions) and IEC exposure assessment standards relevant to guideline-based evaluation."
    },
    {
      "slug": "occupational-exposure",
      "weight": 0.18,
      "reason": "Product safety assessment for close-to-body EMF sources may be relevant to workplace/device-use exposure assessment, though not explicitly occupational."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.3390/ijerph19010044
PubMed: 35010303

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