We know that in the past two years, with the development of new energy electric vehicles in ChinaHall current sensor in electric vehiclesToday, I need to have a discussion with an electrical engineer from Weckway about the classification and application methods of current sensors in electric vehicles. He briefly introduced the current sensor applications and product types in electric vehicles. Compared with traditional current sensors, it has many advantages such as high stability, high accuracy, and high and low temperature resistance. The application of these products in the domestic market and their customers have been explained and illustrated in reverse.

In recent years, electric vehicles have entered thousands of households. The main reason is that more and more two wheeled electric bicycles are low-carbon and environmentally friendly, with a wide range of applications. There are many types of models, including 3-wheel and 4-wheel low-speed vehicles, 4-wheel EV models, electric buses, electric trucks, sightseeing cars, etc. The single application method is basically the same, while the sensor requirements for 3-wheel and 4-wheel electric vehicles are basically the same. Usually, parallel or simple or low-end Hall sensors are used. Many domestic manufacturers manufacture their products in a simple and rough way. At present, the overall safety of this low-speed vehicle cannot be guaranteed. This article mainly introduces the selection and use of current sensing devices based on electric buses and household electric vehicles.

2. The principle of Hall current sensor

At present, the current sensors used in electric vehicles are mostly open-loop current sensors. Previously, the current sensors used in electric vehicles were closed-loop current sensors because closed-loop current sensors have high accuracy and fast response time. Compared with current sensors a few years ago, open-loop current sensors have made great progress in cost-effectiveness, structural size, high and low temperature characteristics, and greatly increased reliability, mainly due to the relatively simple internal structure of current sensors

The open-loop Hall current sensor is based on the direct measurement Hall principle, also known as the open-loop principle (also known as testing only Hall). The magnetic flux generated by the primary current IP is concentrated in the magnetic circuit by a high-quality magnetic core, and the Hall element is fixed in a small air gap to linearly detect the magnetic flux. The Hall voltage output by the Hall element is processed by a special circuit, and the secondary output follows the waveform of the primary output voltage, which can accurately reflect the changes in the primary current. The schematic diagram and appearance are as follows:

Characteristics of Hall principle sensors

Whether it is an open-loop or closed-loop principle, the basic performance difference of Hall sensors is not significant. The basic advantages are:

A. Fast response time

B. Warm and low

C. High measurement accuracy

D. Small size

E. Strong overload capacity

3. Types of electric vehicle current sensors

Electric vehicle sensors are mainly used in two parts: BMS battery management system and motor controller. Some of the current sensors in these two systems can be compatible with each other, depending on the designer's concept and the needs of the end market, as follows:

BMS Battery Management System

According to current usage requirements, the applicable models are B52, B51, and B50, among which B50 belongs to a single power single range current sensor and requires 5V power supply; The B50 current sensor is a dual power supply dual range current sensor that requires a DC ± 12-15V power supply. These two models are commonly used in medium and low-speed vehicles, and the B50 will have a larger application volume in the untapped market because of its higher reliability compared to the B50.

In addition, B51 belongs to a single power dual range current sensor, which also requires a single power supply DC+5V power supply. There are 2 magnetic cores, 2 Hall components, and 2 magnetic core sheaths inside. When the current is less than a certain current value, the sensor automatically switches to the first range, and when it is greater than this current value, it automatically switches to the second channel for measurement. This is mainly to ensure the accuracy of the current sensor.

At present, a BMS battery management system basically uses one current sensor. Unless the customer has different requirements in the high-voltage electromechanical box, adding one current sensor is sufficient. Adding more will only increase the hard cost of electric vehicles.

This product adopts the Hall open-loop working principle, programmable Hall single-chip design, and good reliability; High measurement accuracy, high linearity, low temperature drift, low zero drift; Strong anti-interference ability; High performance Hall current sensors suitable for automotive products, military power supplies, and other applications;