Summary
- Current sensors are critical components in electric vehicles for battery management systems (BMS) and motor control
- Different types of current sensors include closed-loop, open-loop, flux gate, and shunt sensors
- Closed-loop sensors provide high accuracy and stability, suitable for BMS applications
- Open-loop sensors have faster response times, ideal for motor control functions
- Considerations when selecting current sensors include accuracy, response time, environmental conditions, and ease of integration in the EV’s driving environment
Article
Electric vehicles are becoming increasingly popular and the use of electric current is considered the fuel of the future. Current sensors are crucial components in electric vehicles, serving two main applications according to Ajibola Fowowe, global offering manager at Honeywell. These applications include the battery management system (BMS) for monitoring the state of charge and health of the battery pack, as well as motor control for quickly detecting and isolating faults in the electric drive.
When selecting current sensors for electric vehicles, engineers must understand the different types available and their advantages and disadvantages. Closed loop current sensors utilize a feedback system for improved accuracy and stability, making them suitable for use in the BMS. Honeywell’s CSNV 500 is a closed loop current sensor designed for primary current measurements up to ±500 amps, featuring a proprietary temperature compensation algorithm for high accuracy readings within a temperature range of -40⁰ to 85⁰ C.
Open loop current sensors operate on the principle of magnetic induction, requiring less additional electronics and processing compared to closed loop sensors. These sensors have faster response times, making them ideal for motor control applications. Honeywell’s CSHV line of open loop sensors have a range of 100 amps to 1,500 amps and are commonly used in fault isolation, fault detection, and controlling motor speed. They can also be used in battery management systems for hybrid electric vehicles.
Flux gate current sensors measure changes in the magnetic flux of a current passing through a magnetic loop to derive current measurements. The Honeywell CSNV 700 is designed for applications between 500 A and 1,000 A, offering high accuracy and a larger sensing range compared to 500 amps sensors. However, flux gate sensors have higher power consumption, which engineers need to consider when utilizing them in the BMS. Honeywell’s CSSV 1500 combines open loop and flux gate technologies to meet high reliability and performance requirements, particularly for safety-critical applications in battery electric vehicles.
Shunt current sensors measure the voltage drop across a sense resistor placed in the conduction path between a power source and a load. While providing instantaneous current measurements, shunt sensors generate heat and contribute to power loss in the circuit. Advancements in shunt technology are making it more attractive in high voltage systems, with the potential for combining current and voltage measurements into one sensor to reduce overall BMS costs. Engineers must also consider factors like sensor integration, magnetic interference handling, zero-offset, communication protocols, and operating temperature range when selecting current sensors for electric vehicles.
Overall, current sensors play a vital role in monitoring and controlling electric currents in various components of electric vehicles. Understanding the different types of current sensors available, their advantages and disadvantages, and key considerations for selection is essential for engineers working in the electric vehicle industry. Honeywell offers a range of current sensors for electric vehicles with features like high accuracy, reliability, and performance to meet the specific requirements of BMS and motor control applications.
Read the full article here
