ABSTRACT
To improve the reliability of Two-level three phase voltage source inverters, a uniform fault tolerant strategy based on space vector pulse width modulation is proposed for different leg faults. The reconstructed topologies of inverters with different bridge arm faults are different, which makes the basic voltage vector phase of each reconstructed topology inconsistent, resulting in different calculations. Therefore, the coordinate transformation is applied to place the basic voltage vectors of each reconstructed topology on the synchronous stationary αß coordinate system so that the calculations of the reconstructed topology under different bridge arm faults are unified, thus reducing the complexity of fault-tolerant control. Aiming at the three-phase current asymmetry caused by the neutral point voltage oscillation in inverter topology reconstruction, a transient compensation method of neutral point voltage offset for the α-axis component of the reference voltage vector is introduced to suppress the adverse effects. The compensation method directly offers a neutral point voltage offset value after Clarke transformation and corrects the α-axis component of the reference voltage vector, avoiding the integral calculation in the conventional voltage compensation algorithm. The correctness and effectiveness of the proposed fault-tolerant control strategy are verified experimentally.
ABSTRACT
A new gamut boundary descriptor (GBD) is presented in this paper. Unlike the traditional methods to perform sampling in RGB space and to interpolate the data in a uniform color space (UCS), the proposed method is designed in a reverse manner, i.e., to sample the data in UCS. This unique characteristic makes it simple and yields a smooth and accurate boundary. The proposed method can be divided into three simple steps. Firstly, coarse sampling is performed to make a rough estimate of the boundary. In step two, dense sampling is conducted to refine the boundary. Finally, the cusp is identified to achieve the accurate boundary. An experiment was carried out to compare the performance of the proposed method with the two commonly used SMGBD and Mountain Range methods. The results showed that the proposed method can give the most accurate and smooth boundary. It can be considered for practical applications.
