Firstly, the static three-phase coordinate A-B-C is converted into the static two-phase coordinate α-β, and then the static two-phase coordinate α-β is converted into the rotating two-phase coordinate d-q or polar coordinate (M-T). Question 4-5: The dynamic mathematical model of three-phase asynchronous motor is a high-order, nonlinear and strongly coupled multivariable system. Question 4-6: Please write Parker's theorem.

J j 2 V= [Va+Vb e 3+Vc e 3] Vector V is called Park vector, that is, space vector, which indicates the position of the composite vector in space at a certain moment of time 32π 4π.

Three-phase electromotive force, voltage, current, magnetomotive force and magnetic flux are all three-phase electromagnetic quantities. If all three-phase electromagnetic quantities can be represented by a vector on the complex plane, three-dimensional physical quantities can be changed into two-dimensional physical quantities. Question 4-7: What is coordinate transformation? What are the two principles of coordinate transformation? Where are they used? Coordinate transformation includes: ① static three-phase coordinate (A-B-C)→ rotating two-phase coordinate (d-q-0), p2461cos λ sin λ 21c3s/2r = cos (λ-120℃) sin (λ-/kloc). → static three-phase coordinate (A-B-C) C2R /3S= C3S/2R- 1, static three-phase coordinate (A-B-C)→ static two-phase coordinate (α-β-0), zero-axis current1kloc-0/22.

C3S/2s= 0 K 3 2 K 3 2 K