Permanent magnet generator inductance profile identification
AssigneeVestas Wind Systems A/S
InventorsShu Yu Cao, Anshuman Tripathi, Swee Yee Fonn, Ramasamy Anbarasu, Amit Kumar Gupta
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Abstract
Parameters of PM machines, especially for IPM machine, are known to vary by significant amounts. This affects the controllability of such machines, which may lead to reduced power loading capability and increased losses. The present invention relates to a method for PM machine inductance profile identification based on voltage mode stator flux observation which could be easily integrated to the generator start-up process in wind turbine application for both stator flux vector feedback control system and current vector feedback control system.
Claims14
A method for determining an inductance of a permanent magnet (PM) machine during operation of said PM machine, the method comprising:
- (a) upon determining the PM machine is operating within a predetermined rotational speed window, ramping up a first DC level of a first reference signal until the PM machine produces a first current level,
- (b) computing a second DC level of a second reference signal,
- (c) applying a first AC test signal to each of the first and second reference signals,
- (d) computing a first self-saturation induced inductance value in response to applying the first AC test signal,
- (e) computing a first cross-saturation induced inductance value in response to applying the first AC test signal,
- (f) removing the first AC test signal,
- (g) repeating (a) through (f) until corresponding self-saturation induced inductance values and cross-saturation induced inductance values have been computed for a predetermined number of values of the first current level, and
- (h) removing the first AC test signal, and ramping down the first DC level to zero,
- wherein the first and second reference signals comprise stator flux reference signals generated using nominal Ld and Lq inductance values for the PM machine,
- wherein the PM machine comprises a PM generator controlled by a stator flux controller, and
- wherein the predetermined rotational speed window is included within one of a 1000-1500 rotations per minute (rpm) window, a 300-500 rpm window, and a 30-50 rpm window.
A method of determining an inductance profile of a permanent magnet (PM) machine while operating within a predetermined rotational speed window, the inductance profile corresponding to one or more predetermined test current levels, the method comprising, for each test current level of the predetermined test current levels:
- changing a first direct current (DC) level of a first reference signal until determining that the PM machine is producing the test current level;
- injecting respective first alternating current (AC) test signals onto the first reference signal and onto a second reference signal having a second DC level;
- and
- determining, in response to injecting the first AC test signals, a respective first self-saturation-induced inductance value and a respective first cross-saturation-induced inductance value for the PM machine,
- wherein the first and second reference signals comprise respective first and second stator flux reference signals generated using generated current reference signals and nominal inductance values for the PM machine, and
- wherein the predetermined rotational speed window is included within one of a 1000-1500 rotations per minute (rpm) window, a 300-500 rpm window, and a 30-50 rpm window.
Dependencies are inferred from the claim text.