Current Sensors Measure up to 2kA AC or DC for SiC or GaN Inverter DesignsNovember 09, 2019 by Paul Shepard
Hioki pass-through ac/dc current sensors are best-in-class devices for use with power meters, memory HiCorders and high-performance oscilloscopes. The new CT6877 is a dc to 1MHz, 2000A sensor, intended for evaluating the inverter power conversion efficiency in designs based on next-generation silicon carbide (SiC) and gallium-nitride (GaN) devices.
The CT6877 delivers a wide frequency band and excellent noise resistance, prerequisites for properly evaluating inverters motors used in electric vehicles and hybrid vehicles, a class of devices that continue to move toward ever larger currents and higher-frequency switching.
- Easily measure large 2000A currents to meet applications in EV, HEV testing
- Improved noise resistance performance through a stronger shield lets you accurately measure current buried in noise
- High accuracy measurement realized through flat frequency characteristics and CMRR performance
- More enhanced environmental resistance performance than ever before lets you measure in -40 to 85°C situations
- Improved basic accuracy of ±0.04% and phase accuracy of ±0.1°
- Superior frequency characteristics of dc to 1MHz (amplitude)
- Meet a wide range of applications from measuring battery charge/discharge to the secondary side of inverters in photovoltaic power generation and fuel cell evaluation, etc.
- Monitor waveforms when paired with oscilloscopes or Memory HiCorders and Sensor Unit
Through current sensor for 2000A
Most large currents are divided into two to four wires. In the past, it was necessary to measure wires individually using multiple current sensors due to the devices' insufficient aperture size and current ratings. The optional Sensor Unit CT9557 provided functionality for adding together the sensors' measured values in such setups and outputting the result as a single signal.
Thanks to its large, 80 mm aperture, the CT6877 can accommodate four wires with an outer diameter of 31 mm (equivalent to a cross-sectional area of 250 mm2). In this way, a single sensor can be used to collectively measure wires carrying up to 2000 A.
Technology driving the evolution of current measurement
Current sensor performance is maximized with the "Zero Flux (Fluxgate Detection)" measurement method. High frequency current is detected with windings (CT method), and direct to low frequency current is detected with fluxgates. Use of a newly developed opposed split coil (coil in which divided windings are arranged opposite each other on a magnetic core to broaden the range of current detection) for the winding (CT) makes possible a broad measurement band, while strengthened shielding boosts anti-noise performance.
Guaranteed accuracy when used in combination with a power meter
Since the company develops both current sensors and power meters, Hioki is able to guarantee the combined accuracy of the products when used together for greater customer peace of mind. Used in conjunction with a high-precision power meter such as Hioki's Power Analyzer PW6001, the CT6877 can measure currents with a high degree of accuracy.
Above is an example of the CT6877 being used with the Power Analyzer PW6001. The PW6001 measures from dc to 2MHz, and is a proven solution for high-accuracy power analysis. The PW6001 features a phase shift function for current sensors to lock in accurate measurement of high-frequency power. 5 MS/s sampling at 18-bit resolution ensures true power analysis of PWM waveforms and results that are free of aliasing error.