Patent ID: 8450957

Claim:
A space vector based synchronous modulation method, comprising: sampling, by a sampling unit of a microprocessor, the frequency f of a reference voltage vector, and retrieving a carrier wave ratio N from a relationship table of frequencies and carrier wave ratios by using the frequency f; deriving, by a first calculation unit of the microprocessor, an angle Δθ that the reference voltage vector has undergone from Δθ=2π/N and a modulation angle θ m of the reference voltage vector from θ m =(N th −1)×Δθ, wherein N m represents the N th sampling; retrieving, by a retrieval unit of the microprocessor, a modulation ratio m from a modulation ratio vs. frequency graph; calculating, by a second calculation unit of the microprocessor, output angles of three fundamental voltage vectors synthesizing the reference voltage vector from the modulation angle θ m of the reference voltage vector, the undergone angle Δθ and the modulation ratio m; and comparing, by a comparison unit of the microprocessor, a variation Δθ f of the angle θ of the reference voltage vector with the output angles of the three fundamental voltage vectors, outputting, by an outputting unit of the microprocessor, the fundamental voltage vectors in response to a comparison result, and synthesizing the fundamental voltage vectors into an output voltage consistent with the reference voltage vector.