Control method for vector flux weakening for vehicle permanent magnet synchronous motor

A control system for vector flux weakening for a vehicle permanent magnet synchronous motor, comprising a current closed-loop adjuster, a modulation ratio deviation calculator, a current command angle compensator, a current angle preset processor, a current command angle limiting comparator and a current given vector corrector;

• wherein an input of the current closed-loop adjuster is a dq current command output by the current given vector corrector, and after passing through a proportional-integral controller, a dq voltage command is output;
• an input of the modulation ratio deviation calculator is the dq voltage command output by the current closed-loop adjuster;
• after an expected modulation ratio MIref is obtained by solving a square root of a sum of squares, a difference between the expected modulation ratio and an expected maximum modulation ratio MImax of a control system is calculated, and after passing through the low-pass filter, a modulation ratio deviation ΔMI is output;
• an input of the current angle compensator is the modulation ratio deviation output by the modulation ratio deviation calculator, and after passing through a proportional-integral compensator, a correction angle Δθ is output;
• the current angle preset processor is configured to preset a current angle θpre;
• the current command angle limiting comparator is configured to limit the current angle compensated by the correction angle output by the current command angle compensator to be above the current angle preset by the current angle preset processor:
• θ+Δθ≥θpre
• where θ is the current angle before flux weakening control;
• and
• the given current vector corrector is configured to:
• calculate d-axis and q-axis current commands idref and iqref after flux weakening control based on the current angle preset by the current angle preset processor:
• {
• i
• qref
• =
• ❘
• "\[LeftBracketingBar]"
• i
• ❘
• "\[RightBracketingBar]"
• ⁢
• cos
• ⁡
• (
• θ
• +
• Δ
• ⁢
• θ
• )
• i
• dref
• =
• -
• ❘
• "\[LeftBracketingBar]"
• i
• ❘
• "\[RightBracketingBar]"
• ⁢
• sin
• ⁡
• (
• θ
• +
• Δθ
• )
• ⁢
• θ
• +
• Δθ
• >
• θ
• pre
• {
• i
• qref
• =
• ❘
• "\[LeftBracketingBar]"
• i
• ❘
• "\[RightBracketingBar]"
• ⁢
• cos
• ⁡
• (
• θ
• pre
• )
• i
• dref
• =
• -
• ❘
• "\[LeftBracketingBar]"
• i
• ❘
• "\[RightBracketingBar]"
• ⁢
• sin
• ⁡
• (
• θ
• pre
• )
• ⁢
• else
• where |i| is a current before the flux weakening control;
• and
• to drive the vehicle permanent magnet synchronous motor to rotate based on a torque determined by the d-axis and q-axis current commands idref and iqref.