| 摘要 |
A method for measuring a magnetic field via a Hall cross (12) including two orthogonal branches (120, 122), in which, for a given state of the Hall cross, a polarization current is made to flow in one of the branches of the Hall cross, referred to as the “polarization branch”, and a voltage is measured in the other branch, referred to as the “measurement branch”, the measured voltage including a useful signal representing the magnetic field, the method including the modulation of the useful signal via a switching sequence consisting in placing the Hall cross in Nb successive states, and the demodulation of the useful signal. The switching sequence is furthermore chosen in such a way that a measurement bias and interference pulses are zero-mean after demodulation. A switching Hall-effect sensor (10) is also described. |
| 主权项 |
1. A method for measuring a magnetic field by means of a Hall cross (12) including two orthogonal branches (120, 122), in which, for a given state of the Hall cross, a polarization current is made to flow in one of the branches (120, 122) of the Hall cross, referred to as the “polarization branch”, and a voltage is measured in the other branch (120, 122), referred to as the “measurement branch”, said measured voltage comprising a useful signal (Vu) representing the magnetic field, said method comprising the modulation of the useful signal (Vu) by means of a switching sequence consisting in placing the Hall cross in a number Nb of successive states, and the demodulation of said useful signal (Vu), by defining:
a reference point x, y, z associated with the Hall cross, in which x is a unit vector parallel to one of the two branches (120, 122) of the Hall cross, y is a unit vector parallel to the other of the two branches (120, 122), and z is a unit vector equal to x̂y, where “̂” corresponds to the vector product, a state E(n) of the Hall cross at a time n in the form of unit vectors i(n) and v(n) corresponding respectively to the direction of flow of the polarization current in the polarization branch (120, 122) and to the direction of measurement of the voltage on the terminals of the measurement branch (120, 122), expressed in the reference point, a mutual orientation IV(n) of the vectors i(n) and v(n) in the reference point as being equal to (i(n)̂v(n))·z, where “·” corresponds to the scalar product, a swap P(n) between the state E(n−1) and the state E(n) as being equal to v(n)·i(n−1),the switching sequence is such that, with each transition between two successive states, the polarity of the mutual orientation is reversed, and such that the following two expressions are verified:∑n=0Nb-1(-1)n×P(n)=01+∑n=1Nb-1(-1)H(n)=0where:H(n)=∑k=1nP(k)the method being characterized in that:
in the switching sequence, the swap P(n) is zero in every other state and the polarity reversal of the mutual orientation IV(n) in relation to the mutual orientation IV(n−1) is obtained, when the swap P(n) is zero, by reversing the direction of flow of the polarization current in the polarization branch (120, 122) of the Hall cross, and Nb is equal to four, and a number k exists, such that:
P(k[Nb])=1P((k+1)[Nb])=0P((k+2)[Nb])=−1P((k+3)[Nb])=0where “[Nb]” means modulo Nb. |
