TUNKIA Typical Applications of AC/DC High Current Sources

With the development of China's new energy industry, there has been an increasing demand for high current testing. In fields such as electric vehicles, photovoltaic inverters, and energy storage systems, as system power levels continue to rise, there is a growing need for precise measurements of high currents, reaching thousands or even tens of thousands of amperes. For example, the peak current of the battery pack in high-performance electric vehicles with dual motors can reach 1200 A to 1500 A. In the rail transit sector, currents can even reach up to 10 kA. Therefore, establishing AC/DC high current metrology capabilities and ensuring the calibration traceability of high current measurement devices such as AC/DC sensors, DC ratio standards, current transformers, and DC shunt resistors are crucial for the development of the new energy industry. This also represents an important aspect of metrology in advancing new productive forces.

Next, this article will share a 10 kA AC/DC high current testing application case.

TUNKIA Solutions

TUNKIA AC/DC High Current Testing System consists of an AC/DC current source, sensor testing fixtures, and a measurement and control platform. It provides programmable output of AC/DC currents ranging from 0.2 A to 10 kA, making it suitable for calibrating high-precision current sensors or DC shunt resistors. This system offers technical support for establishing high-precision current and resistance measurement systems in high-level metrology laboratories.

The system adopts a modular design, allowing for flexible output of different current specifications. The accuracy of DC current reaches 0.015%, while the accuracy of AC current is 0.03%. It can calibrate DC current transformers and sensors with an accuracy of 0.05 class and below, as well as AC current transformers and sensors with an accuracy of 0.1 class and below, without the need for external standard current transformers.

Functional Features

• Versatile Usage

Supports testing of current sensors, current transformers, current transducers, clamp meters, standard resistors, through-hole ammeters, DC shunt resistors, and more.

• High Testing Efficiency

AC/DC integrated, switching between modes is done via the host software, with no need for rewiring.

• Strong Load Capacity

Meets the demands of wide-frequency, high-current load applications.

• High Economic Benefit

One system can fulfill multiple high-current testing requirements across various scenarios, and the system’s high-current source is modular, allowing for flexible upgrades and capacity expansion.

Key Technologies

• Modular Design
  

The high-current source adopts a modular design, with each module operating independently and without interference from others. When servicing a single module, there is no need to disassemble or inspect the entire system, improving maintenance efficiency.
TUNKIA solution addresses the synchronization issues of frequency and phase across multiple current output units through system structure optimization, process improvements, and precise feedback regulation of signals.

• Wideband High Current Output Technology

Conventional digital amplifiers typically have large inherent harmonic components, significant signal distortion, and a broad switching noise spectrum, all of which can directly affect high-precision measurement results. TUNKIA solution uses Class A and Class B linear amplifiers, addressing the resistance matching issue in the current output loop while reducing the effects of self-inductance and mutual inductance in the output loop. For output transformers, when high current is output, the loop's inductive reactance becomes large, preventing the high current from being delivered to the tested unit. If a single amplifier module is directly connected to the output transformer, its design and heat dissipation capabilities may not support such high currents. TUNKIA solution employs multiple wideband current output units in parallel, with each unit including an amplifier and transformer module that corresponds to the amplification needs of different ranges, achieving the goal of wideband high current output.

• Load Compensation Technology

The load impedance in the current output loop for wideband high current can be resistive, inductive, and capacitive. As the output frequency increases, the inductive impedance has a greater impact on the output load. TUNKIA solution designs a capacitive-inductive output compensation network to adapt to different frequency conditions and compensate for current output, thereby improving the overall load capacity of the system.

The compensating capacitors and inductors are in series, and when they reach series resonance, the system's equivalent impedance is minimized. However, the compensating capacitance value cannot be fully linearly adjustable. TUNKIA solution addresses this by setting responsive compensating capacitors at key frequency points to reduce their load impact. Additionally, the compensation module can be controlled via switches, allowing the operator to choose whether to use the compensation feature.

Traceability Solution

To ensure accuracy, a dedicated traceability solution has been designed specifically for the high current source.

Laboratory Layout Requirement

TUNKIA AC/DC High Current Source Product Series Overview
For testing currents above the kA level, TUNKIA has developed a full range of solutions, including DC high current sources, AC high current sources, and integrated AC/DC high current sources, to meet the diverse application needs.