Product Oct. 20, 2022

Evaluating inverter efficiency in high-voltage circuits while accommodating widespread adoption of SiC power devices

Hioki is pleased to announce the launch of the AC/DC High-Voltage Divider VT1005, which divides and outputs voltages of up to 5000 V. Combined with Hioki’s Power Analyzer PW8001, the device can be used to accurately measure large, high-voltage power signals to assess efficiency improvements gained through use of SiC power devices.

Development Background

Inverters that use SiC power devices increasingly are being utilized in infrastructure that handles large amounts of power, for example rail applications and power conditioners. When power control systems like inverters convert electricity for the intended use, loss of electrical energy occurs. The more efficient the inverter, the lower the loss, allowing electrical energy to be used more effectively. Use of SiC power devices in inverters significantly reduces energy loss, improving efficiency.

Power converted by inverters contains the fundamental wave as well as the switching frequency and harmonics. When assessing efficiency improvements gained through use of SiC power devices, it’s essential to be able to measure these components accurately. 

Power analyzers are an ideal tool for measuring efficiency. However, typical power analyzers cannot directly measure voltages of 1000 V or greater. When measuring large, high-voltage power signals, such instruments must use a high-voltage differential probe or potential transformer. However, those devices are unable to accurately measure the components contained in power on the output side of inverters. As a result, they introduce a number of issues: efficiency results that exceed 100%, instability of measured values, and low reproducibility. Hioki developed the VT1005 to resolve issues such as these. The VT1005 divides and outputs voltages of up to 5000 V to a power analyzer, allowing the instrument to accurately detect all the components contained in inverter output-side power so that users can ascertain efficiency improvements on the order of 0.1%.


1. Safely Measure High Voltages up to 5000 V
The VT1005 divides voltages of up to 5000 V and outputs them to a power analyzer.

2. Detect Efficiency Improvement Effects on the Order of 0.1%
In order to measure the efficiency of high-efficiency inverters with a high degree of precision, you need to be able to accurately measure power from DC to high frequencies. Thanks to its excellent frequency flatness, the VT1005 makes possible accurate measurement at frequencies ranging from the fundamental wave to switching-frequency components.


- Evaluation of the Efficiency of Inverters That use SiC Power Devices in Electrical Railways
- Evaluation of the Efficiency of Inverters That Use SiC Power Devices in Industrial Equipment
- Evaluation of the Efficiency of Solar Inverters That Support High-Voltage Input
- Evaluation of Loss in Transformers and Reactors Designed for Use in High-Voltage Circuits
- Evaluation of the Efficiency of Wireless Power Transfer (WPT) Systems