Application of Hall closed current sensor in electric sightseeing bus
Abstract: This article introduces the use method of current sensor based on Hall closed principle, namely magnetic balance principle,
in electric sightseeing vehicles. It replaces traditional Hall devices, better solves the basic problems of existing Hall sensors in electric vehicle industry,
and is more superior in stability.
Key words: Hall closed loop; Current sensor; Electric sightseeing bus
Our country is extremely rich in tourism resources. In various tourist attractions, we can see the existence of electric sightseeing tour buses.
Electric sightseeing tour buses are powered by batteries. They do not emit harmful gases that pollute the atmosphere, and they can be used only after being
charged by batteries. Because most power plants are built far away from densely populated cities, causing less harm to human beings, and the power plants are
stationary and concentrated, It is easy to remove all kinds of harmful emissions, and there are relatively mature technologies. The electric sightseeing tour bus
can make full use of the surplus electricity during the low electricity consumption at night to charge, which is the advantage that the power generation equipment
can be fully used day and night, greatly improving its economic benefits, saving energy and reducing carbon dioxide emissions.
2 Specific application of Hall closed loop current sensor
2.1 Principle of Hall closed loop current sensor
The Hall current sensor is based on the magnetic balance Hall principle, that is, the closed loop principle. When the magnetic flux generated by the primary
current Ip is concentrated in the magnetic circuit through a high-quality magnetic core, the Hall element is fixed in the air gap to detect the magnetic flux,
and the reverse compensation current is output through a multi turn coil wound around the magnetic core to offset the magnetic flux generated by the primary IP,
so that the magnetic flux in the magnetic circuit is always kept at zero. After special circuit processing, the output of the sensor can accurately reflect the
current change of the primary current.
Schematic diagram of Hall closed current sensor
2.2 Dimensions and technical parameters
Rated input RMS current+300A
Measuring current range400A
Rated output effective value current Is150mA±1%
Power consumption current20mA+Is
Zero current offset±0.2mA
Secondary coil resistance26Ω
2.3 Application of Hall closed current sensor
The current detection of the motor of traditional electric sightseeing vehicles is usually realized by Hall element, which is built into the motor rotor.
Through the change of the motor's rotation speed and frequency, the signal is fed back in time, so that the operator can understand the vehicle's working
conditions. Or some manufacturers will monitor the working state of the motor through the external shunt resistance. However, due to the increase in the use
of electric sightseeing vehicles and the derivation of similar electric patrol vehicles, electric tricycles, electric motorcycles and other products, the
performance requirements for the equipment itself have also increased accordingly, and the traditional way is no longer competent for this work.
Under this condition, using Hall closed loop current sensor can solve the related problems well. The power line of the motor passes through the inner air of
the current sensor. When there is current, the current sensor will sense it and have a corresponding output. The output signal will be sent to the bus control
system for centralized processing, as shown in the figure below.
3. Problems to be noticed when selecting and using Hall closed current sensor:
1) Selection of current sensor:
A、Pay attention to whether the size of the sensor hole can ensure that the wire can pass through;
B、Try to choose products with high temperature, low temperature, high humidity, strong earthquake and other conditions;
C、 Attention shall be paid to whether the spatial structure meets the requirements;
2) Use problems of current sensor:
A. When wiring, pay attention to the exposed conductive part of the terminal block to prevent ESD impact as much as possible. Only engineers with professional
construction experience can wire the product. The connecting wires of power supply, input and output must be correctly connected, and must not be misplaced or
reversed, otherwise the product may be damaged.
B. The product shall be installed and used in an environment free from conductive dust and corrosivity
C. Severe vibration or high temperature may also lead to product damage, so we must pay attention to the use occasion.
With the development of society, energy conservation and emission reduction is the focus of current development. The requirements for electric vehicles are getting
higher and higher, and they are also required to be competent for more work. Under this condition, the use of Hall closed loop current sensors can enable vehicles
to work normally under monitoring, reducing the cost of personnel and equipment maintenance.