How to choose the right current detection technology for your high voltage system

From self-driving cars to airplanes to factory floors, advances in electrification and automation are rapidly changing our world. Due to the improvement of performance and reliability, as well as the reduction of the total life cost, the previous manual, mechanical or hybrid systems are developing towards full automation and electrification. In fact, we are in the fourth industrial revolution focusing on automation and intelligent monitoring, also known as the industry 4.0 era. With the full development of the electrification revolution, the role of high-voltage systems in achieving higher efficiency and performance has become more and more prominent.

In high-voltage systems, signal and power isolation helps protect personnel and critical Circuits from high-voltage AC or DC power supplies and loads. As systems integrate more electrical functions, efforts are currently being made to further reduce the size of these systems. How to reduce the system cost and design complexity while reducing the volume and maintain the high performance of the system is a new challenge for engineers.

Current detection is usually used for overcurrent protection, monitoring and diagnosis, and closed-loop control in high-voltage systems. Current detection usually requires high-precision load monitoring and control to maximize efficiency. For example, power factor correction circuits need to accurately detect AC current to improve system efficiency and monitor energy consumption. High-voltage motors also require accurate motor phase line current sensing in order to accurately control the motor torque. Since the characteristics of each system will have many different requirements, this article will focus on how to choose the right current detection technology for your high voltage application.

The three main options for measuring current in high-voltage applications are to use shunt resistor-based isolation amplifiers, closed-loop Hall-effect current sensors, or open-loop Hall-effect current sensors.

As shown in Table 1, isolated current sensors and closed-loop Hall-effect current sensors have higher accuracy and isolation, but they are more expensive and larger than open-loop Hall-effect current sensors. Therefore, if high precision is your primary consideration, then either of these two methods can meet your needs.

If size and cost are critical to your design, an open-loop Hall-effect current sensor may be your best choice. As described in Table 1, they can achieve high-voltage isolation measurement in a simple, small size, and do not require external components. However, traditional open-loop Hall current sensors have a large drift with time and temperature, which limits their Accuracy.

TI’s newest TMCS1100 zero-drift Hall-effect current sensor solves this problem-this is TI’s first open-loop Hall-effect current sensor, which achieves a good balance of accuracy, size and cost. Its zero-point drift architecture, real-time sensitivity compensation and reliable 3-kV isolation can provide consistent and accurate measurement results over time and temperature in high-voltage systems.

Table 1: Comparison of isolated current detection and measurement schemes

TMCS1100 provides a total error current measurement of less than 1%, and its zero-drift high-precision signal chain structure improves the temperature drift of the device, and no additional multi-point calibration is required. In addition, this accuracy makes the system more efficient, enabling more precise control, while reducing the design complexity that requires high-precision isolated current measurement to a lower level, as shown in Figure 2. In addition, TMCS1100 provides 600-V basic working isolation and 3-kV dielectric isolation between the current path and the Circuit.

Figure 2: TMCS1100 can achieve consistent and accurate measurement of time and temperature.

You can learn more about the advantages of this magnetic-based current sensing method in the white paper “High-precision Hall Current Sensors Boosting the Performance and Efficiency of Power Systems” 3-kV isolation.

Other resources

l Please refer to the following application report:

l “Precise design with non-ratio magnetic current sensor.”

l “Low drift, precision, serial current measurement of isolated magneto.”

l Learn more about the TMCS1100 current sensor.