The virtual resistance technique has been widely adopted to improve the disturbance rejection of the complex vector decoupling approach for surface-mounted permanent magnet synchronous machines at ...high speed. Its gain selection, however, has only been discussed in the continuous domain. In this study, the virtual resistance technique is analysed directly in the discrete domain. Theoretical analyses demonstrate that there is a definite upper limit for the virtual resistance selection which is only dependent on the ratio between the time constant of the machine and the sampling period. A new discrete current controller is proposed to improve the command tracking and the disturbance rejection of the current loop. A trade-off is made between the rapidity and the robustness of the proposed controller in order to achieve a parameter error tolerance of 50%. Experimental results verify that the proposed controller gains better performance at high speed, i.e. a higher bandwidth of 0.135fs without overshoots and fewer oscillations, than the controllers designed in the continuous domain. Even deadbeat responses, to both the reference signals and the disturbance, can be achieved by the proposed controller at its limits.
► We present an optimized modeling for antenna-based sensors. ► We use time-domain gain operator by overcoming current known limitations. ► FDTD technique is suitable for new classes of sensors ...serving as antenna. ► We apply the technique for millimeter-scale antenna sensors and improving sensor fabrication.
A semi-analytical methodology is presented for the accurate analysis of time-domain radiation characteristics of antenna sensors. A locally conformal finite-difference time-domain technique is adopted to derive a minimal pole/residue spherical harmonic expansion of the equivalent currents excited on a suitable Huygens surface enclosing the sensing device. In this way, by using the singularity expansion method, the time-domain gain and effective height of the structure can be evaluated analytically, in terms of the newly introduced incomplete spherical Bessel functions, as the superposition of non-uniform spherical wave contributions attenuating along with the time and space according to the complex poles accounting for the natural resonant processes occurring in the device. The accuracy of the developed technique is assessed by application to an ultrawideband bow-tie antenna-based sensor for millimeter-wave radar measurements.
The CLLC resonant converter is a popular bidirectional isolated dc-dc converter topology due to its ideal sinusoidal ac current through the high-frequency transformer, soft switching at a full range ...of loads, smaller circulation current. Since the accuracy of the gain model has a direct impact on the converter parameters design, this paper first proposed a simplified time-domain gain model for the CLLC resonant converter based on the superposition principle and the energy conservation law. Compared with the fundamental harmonic approximation (FHA) method, this gain model has higher accuracy and can be adopted with both resistance and battery load. And then, the boundary conditions between different operation modes in CLLC converter have been analyzed. Finally, the proposed time-domain gain model was verified by the simulated and experimental results of a 15 kW prototype.
