Magnetic encoder, method, system for detecting absolute electrical angle, and readable storage medium

A method for detecting an absolute electrical angle based on a magnetic encoder, the magnetic encoder being configured to detect a 2-dimension magnetic field component of a magnetic field generated by a magnet to be tested, and the 2-dimension magnetic field component comprising a magnetic field component in a first direction and a magnetic field component in a second direction, the magnetic encoder comprises a magnetoresistance sensor, a magnetic field auxiliary coil and a coil current control circuit electrically connected with the magnetic field auxiliary coil,

• the magnetoresistance sensor being a planar component,
• the coil current control circuit being configured to supply current to the magnetic field auxiliary coil, to allow the magnetic field auxiliary coil to generate an auxiliary magnetic field,
• the auxiliary magnetic field influencing the magnetic field component in the first direction and the magnetic field component in the second direction, and forming a resultant magnetic field, and
• the magnetoresistance sensor being configured to detect the resultant magnetic field and the components of the 2-dimension magnetic field generated by the magnet;
• the method comprising:
• controlling the magnetic field auxiliary coil to generate an auxiliary magnetic field influencing the magnetic field component in the first direction and the magnetic field component in the second direction, forming the resultant magnetic field, acquiring a first voltage signal of the resultant magnetic field detected by the magnetic encoder, and determining an angular position of the magnetic encoder according to the first voltage signal;
• acquiring a second voltage signal detected by the magnetic encoder of the 2-dimension magnetic field component of the magnetic field of the magnet, and calculating and obtaining a relative electric angle value according to the second voltage signal and an inverse trigonometric formula;
• and
• calculating the absolute electrical angle according to the angular position of the magnetic encoder and the relative electrical angle value;
• wherein the magnetic field auxiliary coil comprises a first coil and a second coil that are arranged in parallel,
• the first coil and the second coil are located in a same plane;
• the coil current control circuit is electrically connected with both of the first coil and the second coil,
• the method further comprises:
• supplying, by the coil current control circuit, current to the first coil and the second coil and control a direction of the current in the first coil and in the second coil, and
• generating, by the coil current control circuit, the auxiliary magnetic field influencing the magnetic components in the first direction and the second direction the operation of acquiring the second voltage signal detected by the magnetic encoder of the 2-dimension magnetic field component of the magnetic field of the magnet, and calculating and obtaining the relative electric angle value according to the second voltage signal and the inverse trigonometric formula comprises:
• acquiring the second voltage signal detected by the magnetic encoder of the 2-dimension magnetic field component of the magnetic field of the magnet, the second voltage signal comprising an angular sinusoidal signal and an angular cosine signal;
• calculating a scaling compensation sinusoidal signal and a scaling compensation cosine signal, according to the angular sinusoidal signal, the angular cosine signal and a scaling compensation formula;
• calculating and obtaining the relative electric angle value according to the scaling compensation sinusoidal signal and the scaling compensation signal,
• the scaling compensation formula being:
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• wherein,
• Vsc(θ) is a scaling compensation sinusoidal signal;
• Vcc(θ) is a scaling compensation cosine signal;
• Vs(θ) is an angular sinusoidal signal;
• Vc(θ) is an angular cosine signal;
• Vs0 is a bias error of a preset sinusoidal signal;
• Vc0 is a bias error of a preset cosine signal;
• Vm is a preset adjusting amplitude;
• Vsm is an amplitude compensation to a fundamental wave of the preset sinusoidal signal;
• and
• Vcm is an amplitude compensation to the fundamental wave of the preset cosine signal.