Automatic Detection Method and Apparatus for Rotor Initial Position Angle of Double-Fed Machine

An apparatus for automatic detection of an initial rotor position angle of a doubly-fed electric machine, comprising:

• a reference voltage angle giving unit, a reference voltage amplitude giving unit, a first multiplier, SVPWM, a rotor mechanical angle acquisition unit, a stator voltage vector angle acquisition unit and a first comparator, wherein
• the reference voltage angle giving unit is configured to give a reference voltage angle θgiven and output it to an input of the first multiplier and a negative input of the first comparator;
• the reference voltage amplitude giving unit is configured to give a reference voltage amplitude Vref and output it to an input of the first multiplier;
• the first multiplier is configured to multiply the given reference voltage angle θgiven by the given reference voltage amplitude Vref, and to output a reference voltage vector to the SVPWM;
• the SVPWM is configured to convert the reference voltage vector into a drive signal and send it to a rotor-side PWM transformer;
• the rotor mechanical angle acquisition unit is configured to acquire a rotor mechanical angular speed n×θrutor and output it to the negative input of the first comparator;
• the stator voltage vector angle acquisition unit is configured to acquire a stator voltage vector angle θ1 and output it to a positive input of the first comparator;
• and
• the first comparator is configured to subtract the rotor mechanical angular speed n×θrutor and the given reference voltage angle θgiven from the stator voltage vector angle θ1 and to output the initial rotor position angle θinital,
• wherein n is the number of pole pairs of the doubly-fed electric machine.

A method for automatic detection of an initial rotor position angle of a doubly-fed electric machine, comprising:

• acquiring a rotor mechanical angle n×θrotor of the doubly-fed electric machine;
• acquiring a grid voltage vector angle θ2 and a grid voltage vector amplitude VR;
• calculating a given reference voltage angle θgiven by the equation of
• θgiven=θ2−θinital−n×θrotor;
• generating a reference voltage vector with the grid voltage vector amplitude VR being its amplitude and the given reference voltage angle θgiven being its phase angle;
• converting the reference voltage vector into a drive signal through SVPWM to drive a rotor-side PWM transformer to generate an AC voltage signal, and applying the AC voltage signal to a rotor winding of the doubly-fed electric machine;
• acquiring a stator voltage vector angle θ1 ;
• obtaining a phase-angle difference Δθ between the grid voltage and the stator voltage by subtracting the stator voltage vector angle θ1 from the grid voltage vector angle θ2;
• and
• converting the phase-angle difference Δθ between the grid voltage and the stator voltage into the initial rotor position angle θinital by a proportional-integral algorithm,
• wherein n is the number of pole pairs of the doubly-fed electric machine.

An apparatus for automatic detection of an initial rotor position angle of a doubly-fed electric machine, comprising:

• a rotor mechanical angle acquisition unit, a grid voltage vector angle acquisition unit, a grid voltage vector amplitude acquisition unit, a stator voltage vector angle acquisition unit, a fifth comparator, a PI controller, a fourth comparator, a second multiplier and SVPWM, wherein
• the rotor mechanical angle acquisition unit is configured to acquire a rotor mechanical angular speed n×θrutor and output it to a negative input of the fourth comparator;
• the grid voltage vector angle acquisition unit is configured to acquire a grid voltage vector angle θ2 and output it to a positive input of the fourth comparator and a positive input of the fifth comparator;
• the grid voltage amplitude acquisition unit is configured to acquire a grid voltage amplitude VR and output it to the second multiplier;
• the stator voltage vector angle acquisition unit is configured to acquire a stator voltage vector angle θ1 and output it to a negative input of the fifth comparator;
• the fifth comparator is configured to subtract the stator voltage vector angle θ1 from the grid voltage vector angle θ2 and to output a phase-angle difference Δθ between the grid voltage and the stator voltage to the PI controller;
• the PI controller is configured to apply a proportional-integral algorithm to the phase-angle difference Δθ between the grid voltage and the stator voltage, to obtain the initial rotor position angle θinital and output it to the negative input of the fourth comparator;
• the fourth comparator is configured to subtract the initial rotor position angle θinital and the rotor mechanical angular speed n×θrutor from the grid voltage vector angle θ2, and to output a given reference voltage angle θgiven to the second multiplier;
• the second multiplier is configured to multiply the received given reference voltage angle θgiven by the grid voltage amplitude VR and to output a reference voltage vector to the SVPWM;
• and
• the SVPWM is configured to convert the reference voltage vector into a drive signal and send it to a rotor-side PWM transformer.