Hioki Achieves Tenfold Advance in High-Frequency Power Calibration, Enabling More Accurate Testing for Electric Vehicles and Clean Energy Systems

Summary

• Hioki has developed a new measurement standard for evaluating the high-frequency power measurement accuracy of power analyzers.
• Using an original calorimeter-based method, achieved uncertainty^*1 in active-power calibration^*2 of 0.006% of apparent power at 200 kHz and 0.014% at 1 MHz.
• The results of this study have been published in the IEEE Transactions on Instrumentation and Measurement. ^*3

• *1: Uncertainty refers to an index indicating the degree of variation in, or potential error of, a measured value. A smaller uncertainty indicates higher reliability of the measurement result.
• *2: Calibration of a measuring instrument means using a reference measurement standard to measure the instrument’s error relative to that standard.
• *3: M. Nakamura, "Calibration of Phase Error for a Wideband Precision Power Analyzer Using the Calorimetric Phase Standard," in IEEE Transactions on Instrumentation and Measurement, vol. 75, pp. 1-10, 2026, Art no. 1003610, doi: 10.1109/TIM.2026.3687333.

Nagano, Japan, July 8, 2026 — Hioki E.E. Corporation has developed a measurement standard that resolves a long-standing accuracy gap in high-frequency power calibration, delivering calibration accuracy approximately ten times greater than was previously achievable — including under methods used by national metrology institutes.

By exploiting the physical principle that power losses ultimately manifest as heat, Hioki’s new calorimeter-based system detects heat generation as small as 0.01% of input apparent power, hardly dependent of operating frequency.

Conventional electrical calibration methods lose accuracy as frequency rises, but heat measurement does not. Compensating continuously for ambient temperature variation and external heat inputs, Hioki’s new calorimeter-based calibration method  achieves an uncertainty of 0.006% of apparent power at 200 kHz and 0.014% at 1 MHz — compared with 0.05% under leading national-standards-class methods at 200 kHz.

This smaller uncertainty — about 9 mW on a 150 VA device — is roughly the power draw of a capacitor, producing a higher reliability on measurement results, and allowing engineers to see verifiable, visible efficiency gains.

By using calorimetric measurement largely unaffected by the frequency of electrical power, Hioki was able to maintain accuracy even in high-frequency regions. Our newly developed calorimeter builds in continuous correction for external heat influences like background temperature fluctuations, producing a calibration standard that holds its accuracy across a wide frequency range.

Applied to Hioki’s PW8001 power analyzer paired with the CT6904A current sensor, the standard confirmed measurement error below 0.04% of apparent power up to 200 kHz — a level of accuracy that existing calibration benchmarks cannot adequately verify.

A pathway to improving power measurement

Hioki’s advancement comes as power electronics — the technology that governs energy flow in electric vehicle motors, solar inverters, wind turbines, and data center power supplies — have been evolving toward higher switching frequencies and ever-smaller energy losses. As efficiency improves, the losses engineers must measure have become harder to detect. There is now a growing need to calibrate instrument accuracy more precisely across a wider frequency range, requiring measurement standards more accurate than the instrument being calibrated. 

Hioki expects that this measurement standard will become a foundational technology to support accuracies of broadband power measurement, and plans to expand into calibration services using this technology. Our company also plans to advance its measurements techniques, contributing to higher efficiency and improved reliability across power electronics applications, including electric vehicles, renewable energy, data centers, and industrial power supplies. 

As global power electronics markets grow and efficiency requirements tighten under evolving energy regulations, the ability to verify high-frequency performance with traceable accuracy represents a significant capability advantage for product developers and their customers.

Hioki is committed not only to delivering high-precision measuring instruments, but also to advancing measurement standards that underpin the reliability of measurement results. Through trusted measurements, Hioki will contribute to innovation in the power electronics field and to the realization of a sustainable society.

Information about the paper

• Title: “Calibration of Phase Error for a Wideband Precision Power Analyzer Using the Calorimetric Phase Standard”
• Author: Miyuki Nakamura
• Journal: IEEE Transactions on Instrumentation and Measurement
• DOI: 10.1109/TIM.2026.3687333
• URL: https://ieeexplore.ieee.org/document/11494752

  (This paper is licensed under the Creative Commons CC BY license. Portions of this news release use adapted content from the paper.)

A supporting technical note, “Calibration of Wideband Low Power-Factor Power Using Calorimetric Method”, can be found on our website here.

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