Shunt Resistor current sensing vs Hall Effect current sensing | Difference between Shunt Resistor current sensing and Hall Effect current sensing
This page compares Shunt Resistor current sensing vs Hall Effect current sensing and mentions difference between Shunt Resistor current sensing and Hall Effect current sensing. Advantages and disadvantages of these methods are also mentioned.
Shunt Resistor current sensing
The figure-1 depicts high side shunt resistor based current sensing. There is another type known as low side shunt resistor current sensing where in one terminal of resistor is connected to battery ground (U1) and the other is connected to the load.
The voltage drop across shunt resistor is proportional to the current flow (I) through it.
This can be expressed as follows.
U2 - U1 = RShunt x I ...Equation-1
The voltage difference is amplified using Op-Amp (i.e. Operational Amplifier) and fed to the A/D converter. The digital output can be read using microcontroller.
Advantages and Disadvantages of Shunt Resistor Current Sensing
• This method is easier to implement.
• It can be employed for both AC measurement as well as DC measurement.
• It does not require any galvanic isolation.
• Voltage drop is a big concern in this type of method.
• Power gets dissipated in the shunt resistor.
Hall Effect current sensing
The figure-2 depicts hall effect current sensing. Electric current generates magnetic field around the conductor when current (I) passes through it.
H = I/(2*π*r) ...Equation-2
The field strength (H) magnitude is proportional to current (I) and decreases as distance(r) increases. This is shown in the equation-2. The direction of H can be determined based on "right hand rule".
The equation-3 depicts relationship between B (flux density) and H.
B = μ0*μr*H ...Equation-3
=> B = μ0*μr*I/(2*π*r)
Where, μ0 = 4π x 10-7 = free space permeability
μr is relative permeability.
As shown in the figure-2, Vout is proportional to generated B-field. Hall Effect sensor IC takes Vout as input and produces digital output accordingly. This is being read using microcontroller IC.
Advantages and Disadvantages of Hall Effect Current Sensing
• Galvanic isolation can be achieved.
• There is no voltage loss.
• It can be used for both AC measurement and DC measurement.
• High cost of field concentrator is a concern in this type of method.
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