Method and system for controlling a doubly-fed induction machine

A system comprising:

• a mixer for receiving a signal indicative of rotor currents of a doubly-fed induction machine and a signal indicative of a rotor position estimate vector, the rotor currents being represented as a 2-phase vector in a α-β coordinate frame, the mixer for processing the rotor current vector with the rotor position estimate vector;
• a detector connected to the mixer, the detector for receiving a signal indicative of stator currents of the doubly-fed induction machine, the stator currents being represented as a 2-phase vector in a α-β coordinate frame, the detector for determining a scalar error quantity in dependence upon the stator current vector and the processed rotor current vector;
• a first integrator connected to the detector for integrating the scalar error quantity;
• an adder connected to the integrator for determining an estimate of the rotor angular frequency by adding the central frequency to the integrated scalar error quantity;
• a second integrator connected to the adder for determining a rotor position estimate by integrating the estimate of the rotor angular frequency;
• and,
• a sin-cos block connected to the second integrator and to the mixer for determining a rotor position estimate vector in dependence upon the rotor position estimate;
• and,
• a first output port interposed between the adder and the second integrator for providing a signal indicative of the estimate of the rotor angular frequency and a second port connected to the sin-cos block for providing the signal indicative of the rotor position estimate vector, the first and the second output port for being connected to a control system of the doubly-fed induction machine.

A system comprising:

• a mixer for receiving a signal indicative of rotor currents of a doubly-fed induction machine and a signal indicative of a rotor position estimate vector, the rotor currents being represented as a 2-phase vector in a α-β coordinate frame, the mixer for processing the rotor current vector with the rotor position estimate vector;
• a first detector connected to the mixer, the detector for receiving a signal indicative of stator currents of the doubly-fed induction machine, the stator currents being represented as a 2-phase vector in a α-β coordinate frame, the detector for determining a scalar error quantity in dependence upon the stator current vector and the processed rotor current vector;
• a first integrator connected to the first detector for integrating the scalar error quantity;
• a first adder connected to the integrator for determining a first estimate of the rotor angular frequency by adding a central frequency to the integrated scalar error quantity;
• a second detector connected to the mixer, the detector for receiving a signal indicative of the stator currents of the doubly-fed induction machine, the stator currents being represented as a 2-phase vector in a α-β coordinate frame, the second detector for determining a second scalar error quantity in dependence upon the stator current vector and the processed rotor current vector;
• a second integrator connected to the second detector for integrating the second scalar error quantity;
• a second adder connected to the second integrator and to the first adder for determining a second estimate of the rotor angular frequency by adding the first estimate of the rotor angular frequency to the integrated second scalar error quantity;
• a third integrator connected to the second adder for determining a rotor position estimate by integrating the second estimate of the rotor angular frequency;
• a sin-cos block connected to the second integrator and to the mixer for determining a rotor position estimate vector in dependence upon the rotor position estimate;
• and,
• a first output port interposed between the adder and the second integrator for providing a signal indicative of the estimate of the rotor angular frequency and a second port connected to the sin-cos block for providing the signal indicative of the rotor position estimate vector, the first and the second output port for being connected to a control system of the doubly-fed induction machine.

A storage medium having stored therein executable commands for execution on at least a processor, the at least a processor when executing the commands performing:

• receiving signals indicative of stator currents and rotor currents of a doubly-fed induction machine, the stator currents and the rotor currents being represented as a 2-phase vector in a α-β coordinate frame;
• processing the rotor current vector with a rotor position estimate vector;
• determining a scalar error quantity in dependence upon the stator current vector and the processed rotor current vector;
• integrating the scalar error quantity;
• determining an estimate of the rotor angular frequency in dependence upon the integrated scalar error quantity;
• determining a rotor position estimate by integrating the estimate of the rotor angular frequency;
• determining a rotor position estimate vector in dependence upon the rotor position estimate;
• providing the rotor position estimate vector for processing the rotor current vector;
• and,
• providing a signal indicative of the rotor position estimate vector and a signal indicative of the estimate of the rotor angular frequency for controlling the doubly-fed induction machine.