The role of Hall sensors in brushless DC motors (BLDC)

西安中科阿尔法

The role of Hall sensors in brushless DC motors (BLDC) [Copy link]

In our daily life, "frequency conversion" technology has become very common. As a symbol of Chinese home appliances, it has gradually occupied most of the consumer market. "DC frequency conversion" is favored by various manufacturers and has gradually replaced "AC frequency conversion". This transformation is essentially the transition of the motors used in home appliances from traditional induction motors to brushless DC motors and their controllers to achieve energy saving, environmental protection, low noise, intelligence, and high comfort. The development direction of brushless DC motors is the same as that of power electronics, sensors, control theory and other technologies. It is a product of the combination of multiple technologies, and its development depends on the innovation and progress of each related technology.

The working principle of brushless DC motor is based on the principle of AC driving DC motor. In traditional DC motor, the permanent magnets on the motor rotor will switch the current path with the windings on the stator through the motor brushes, so that the motor can rotate. However, in brushless DC motor, the electronic speed controller replaces the motor brushes to achieve the switching of current path.

The rotor in the brushless DC motor uses a Hall sensor, which has the following two functions:

1. Determine the conduction angle of the power transistor in the electronic commutation circuit drive circuit, thereby determining the magnetic state of the armature magnetic field;

Second, it detects the position of the rotor permanent magnet poles relative to the stator armature winding in order to determine the conduction sequence of the power transistors in the electronic commutation drive circuit.

Different sensors have different characteristics and different applications. In order to achieve these two goals, contactless rotary transformers, magnetoresistive element sensors, Hall switch sensors, etc. can be used.

The contactless rotary transformer is a widely used rotor position sensor at present, but it cannot be used in the home appliance industry due to its complex structure, large size and high manufacturing cost.

While the Hall switch sensor has advantages such as light weight, small size, low manufacturing cost and convenience for mass production, it also has disadvantages such as strict requirements on environmental conditions, narrow temperature adaptability range and poor reliability. Therefore, the Hall switch sensor is widely used in household electrical appliances.

AH401F/AH401N/AH402F/AH402H series Hall sensors are high voltage bipolar Hall switch sensors, all of which are manufactured using high voltage bipolar process. The chip consists of a voltage regulator unit, a Hall voltage generator, a differential amplifier circuit, a temperature compensation circuit, and an open collector output circuit. Input magnetic induction intensity, output is a digital voltage signal. It can withstand high voltage shocks and has strong anti-noise capabilities. The operating temperature range is -40℃~150℃, and the operating voltage is from 3.0V~60V. It is suitable for various consumer electronics, household appliances, industrial control and other fields.

The magnetic sensor includes a voltage modulation circuit, a Hall plate, a signal amplification circuit and a Schmitt trigger circuit. The voltage modulation circuit provides a reference voltage for the Hall plate, which senses the magnetic field perpendicular to the sensor surface and generates a Hall voltage, which is amplified and sent to the Schmitt trigger. At the same time, the chip also integrates a reverse power protection diode to protect the chip from reverse voltage breakdown.

This series of ICs is available in two package types: TO92S and SOT23-3L, and all packages comply with RoHS standards.

Product Features

(1) Operating voltage from 3.0V to 60V

(2) Overvoltage protection capability 90V

(3) ESD performance up to ±4 kV

(4) Open collector output

(5) Operating temperature range: -40℃~150℃

(6) Power pin reverse voltage protection

(7) Suitable for automotive and extreme industrial environments

(8) TO92S and SOT23-3L packages

Typical Applications

(1) Brushless DC motor commutation

(2) Speed measurement

(3) Count

(4) Angular position detection

(5) Proximity detection

led2015

Using Hall sensors to detect the rotor position can provide higher accuracy and stability, as well as longer service life and lower noise levels.

多点学习啊

I think it is worth a try. It is great here. It supports many functions in the field of Internet of Things. It supports esp32 and rp2040 raspberry pi pico picow.

lkh747566933

In order to save costs, automotive electronics now use sensorless control solutions

西安中科阿尔法

lkh747566933 posted on 2023-6-6 11:07 Nowadays, automotive electronics use sensorless control solutions to save costs

First of all, thank you for your attention and reply to our company. At the same time, I agree with your point of view. At present, sensors are unavoidable in many places on the car, such as the motor of the tailgate support rod, the side door controller, the air conditioning motor, the water pump, the shifter, the linear motor, the seat belt and other applications, which are inseparable from our Hall switches, current sensors and other products.
Xi'an Zhongke Alpha Electronic Technology Co., Ltd. was established in 2016. The company is headquartered in Xi'an High-tech Zone, and its R&D centers are located in Surrey, UK and Freiburg, Germany. It is a company that designs, develops, produces and sells magnetic sensor SOC chips. It covers device design, SOC system design, magnetic circuit design, and module design. At present, the company has more than 10 domestic and foreign patents. The company has independent and innovative core technologies and has developed various magnetic switch series chips, magnetic speed and direction sensor chips, linear sensor chips, and magnetic encoder chips. The products can be widely used in automobiles, industry, medical and home appliances. The company has passed the ISO9001 quality certification system and TS16949 automotive-grade certification system.

lkh747566933

Xi'an Zhongke Alpha published on 2023-6-7 09:37 First of all, thank you for your attention and response to our company. At the same time, I agree with your point of view. At present, it is inevitable to use sensors in many places on the car...

The water pump uses sensorless control technology and does not require a Hall sensor.

西安中科阿尔法

lkh747566933 posted on 2023-6-9 15:18 The water pump uses non-sensing control technology, so Hall sensors are not needed.

In brushless motor control, sensorless control does have the characteristics of not requiring sensors and 3 pins, but it also has problems such as non-smooth startup, too small back EMF at low speed or when the rotor is stationary, and failure to detect zero crossing. This is a common shortcoming of all back EMF methods. The back EMF method is not suitable for use in low-speed operation and scenarios with small induced EMF.
In brushless motor control, although Hall sensors have disadvantages such as increased cost and 8 pins, they can detect rotor position, start smoothly, and the motor supports 0-speed startup. Moreover, with the development of the times and the advancement of science and technology, domestic Hall sensors can perfectly replace imported Hall sensors, and are even better than imported products. In addition, the cost has been greatly reduced due to domestic production. In the cost of the entire vehicle, the price of the Hall sensor accounts for a very small proportion, or even negligible.

lkh747566933

Xi'an Zhongke Alpha published on 2023-6-12 09:45 The sensorless control in brushless motor control does have the characteristics of not requiring sensors and 3 pins, but it also has the problems of not smooth startup, low speed or rotor stationary...

Thanks for the reply, it makes a lot of sense, I've learned a lot.