Calculation methods for motor electromagnetic torque and maximum torque per ampere, and motor control method based on vector magnetic circuit

A motor control method based on a vector magnetic circuit, comprising:

• introducing two vector magnetic circuit parameters, namely magductance and hysteretance C, into direct-axis (d-axis) and quadrature-axis (q-axis) vector magnetic circuit models of a surface permanent magnet synchronous motor (SPMSM), wherein the magductance and the hysteretance C are capable of causing a magnetic flux to lag behind a magnetomotive force or a current, and an angle by which the magnetic flux lags behind the magnetomotive force or the current is a magnetic impedance angle δ;
• and
• further comprising the steps of:
• sampling three-phase currents of the SPMSM to obtain sampled values
• i
• a
• *
• ,
• i
• b
• *
• ,
• and
• ⁢
• i
• c
• *
• ,
• and i*, and performing a coordinate transformation on
• i
• a
• *
• ,
• i
• b
• *
• ,
• and
• ⁢
• i
• c
• *
• to obtain current sampled values
• i
• d
• *
• ⁢
• and
• ⁢
• i
• d
• *
• in a direct-quadrature (d-q) coordinate system;
• processing an error between rotor electrical angular velocity ω* and rotor electrical angular velocity set value ω by a proportional-integral (PI) controller to obtain a stator current vector is, and obtaining a d-axis current set value id and a q-axis current set value iq through a relationship between the stator current vector and q-axis and d-axis currents, specifically:
• i
• q
• =
• i
• s
• ⁢
• sin
• ⁢
• β
• ,
• i
• d
• =
• i
• s
• ⁢
• cos
• ⁢
• β
• ,
• and
• β
• =
• arc
• ⁢
• tan
• ⁢
• (
• 1
• tan
• ⁢
• δ
• )
• ,
• where β represents a stator current vector angle, and δ represents the magnetic impedance angle;
• inputting errors between the current sampled values
• i
• d
• *
• ⁢
• and
• ⁢
• i
• q
• *
• in the d-q coordinate system and the set values id and iq into two PI controllers to obtain voltage set values and an R-L coordinate system, wherein
• the R-L coordinate system is obtained by rotating the d-q coordinate system in a lagging direction by the magnetic impedance angle δ, and
• M
• δ
• =
• [
• cos
• ⁢
• δ
• -
• sin
• ⁢
• δ
• sin
• ⁢
• δ
• cos
• ⁢
• δ
• ]
• is a coordinate transformation matrix;
• and
• performing an inverse transformation on and using the coordinate transformation matrix Mδ to obtain voltage set values ud and uq in the d-q coordinate system;
• performing an inverse Park transformation to transform the voltage set values ud and uq in the d-q coordinate system into voltage set values uα and uβ in an a-b coordinate system;
• synthesizing a voltage space vector using uα and uβ;
• inputting the voltage space vector into a voltage space vector pulse width modulation (SVPWM) module for modulation;
• and outputting state encoding values of three half-bridges to control metal-oxide-semiconductor (MOS) transistor switches of a three-phase inverter for controlling the motor.