Method for tracing MTPA curve of vehicle permanent magnet synchronous motor based on DC power

A method for tracing a MTPA curve of a vehicle permanent magnet synchronous motor based on a DC power, comprising a current closed-loop adjuster, a current command generator, a current command angle generator, an active power calculator, an active power storage and comparison processor 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, dq voltage command is generated after the dq current command passing through a proportional-integral controller, and the dq voltage command is output from the current closed-loop adjuster, wherein the dq voltage command comprises ud and uq;
• the current command generator is configured to gradually increase current amplitudes;
• the current angle generator is configured to gradually increase current angles;
• the active power calculator is configured to calculate a real-time active power;
• the active power storage and comparison processor is configured to store and compare a current active power of a current step and a previous active power of a previous step during an angle increase process, wherein the current active power and the previous active power are calculated by the active power calculator;
• if the active power increases after one step of current angle increase, the current angle increase is continued;
• and if the active power does not increase after one step of current angle increase, the current angle increase is stopped, and a current amplitude, a current angle of the previous step and a corresponding active power are output;
• according to the outputs of the current command generator and the current command angle generator, the current given vector corrector calculates dq current commands idref and iqref:
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• sin
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• where I(j) is the current amplitude, and j is for counting the number of steps for current amplitude increase;
• θ(k) is a current angle, and k is for counting the number of steps of angle increase;
• the method comprises that following specific steps:
• (1) starting from a current with a current of 0A and an angle of 90°;
• (2) increasing the current angle θ by the current command angle generator:
• θ(k)=θ(k−1)+θstep
• (3) inputting, by the current command angle generator, the increased current angle into the current given vector corrector upon every step of current angle increase, and at the same time inputting, by the current command generator, the current amplitude into the current given vector corrector, and calculating, by the active power calculator, the active power Pcalcu(k) corresponding to one current step k based on the current angle under the current amplitude;
• (4) repeating steps (2) to (3), increasing current angles until the active power storage and comparison processor judge that the condition Pcalcu(k)−Pcalcu(k−1)≤0 is met, stopping current angle increase, and recording the current amplitude, the current angle θ(k−1) increased in the previous step and a corresponding active power Pcalcu(k−1) thereof as an available point;
• (5) increasing, by the current command generator, the current amplitude I by taking the current amplitude as a starting point:
• I(j)=I(j−1)+Istep
• (6) repeating steps (2) to (5) until the current amplitude increased in step (5) reaches a maximum required current of the proportional-integral controller, stopping circulation, and outputting the available point recorded in step (4) for the current amplitude by results of the current command generator for all iterations for the steps (1)-(6).