1MHz sampling high-speed single-phase PLL control using FPGA based hardware controller

Abstract

In the utility interactive system, the inverter output voltage has to synchronize to the a utility grid. In the case of a single phase system, it is difficult to detect the instantaneous phase angle of the utility voltage. A new high speed single phase PLL control for the single phase utility interactive inverter system is proposed. Quasi d-q trans formation and LPF function are applied to construct the PLL control with IMHz multi sampling parallel processing method based on FPGA based hardware controller. Evalua tions were carried out with simulations. Very fast detection response was achieved with stable transient operations. I. INTRODU CTIONAs the progress of the information society and the concerns to the global environmental problem, the dis tributed power system like PV generation, wind power generation and fuel cells generation has much attention in the worldwide. In these generation systems, the utility interactive inverter is necessary to connect the DC power source to the utility line.As for the single phase utility system, the internal phase of the controller has to synchronize to the utility grid. Differ from the three phase system, it is not easy to detect the instantaneous phase angle of the utility voltage. Authors proposed a high speed PLL control based on a quasi d-q transformation with a multi sampling parallel processing method [1]. The progress of FPGA technology makes it possible to realize very fast sampling while the control sampling intervals, so IMHz sampling and calculation can be applied continuously while the sampling interval. In this paper, a new IMHz sampling based quasi d q transformation is applied to construct the PLL control with multi sampling parallel processing method. In the case of the distorted utility voltage, the affection of the distortion was not negligible to detect the utility frequency. To avoid this affection, 1 st order LPF was also combined to suppress the affection of the distortion. Verifications were carried out through simulations. II. THE SINGLE-PHASE PLL CONTROL WI TH QUASI DQ TRANSFORMATION Fig.l shows a block diagram of the proposed method.Input wavefOim Vs is assumed as the utility voltage, which is sampled in ever y sampling period Ts, so the present sampled data Vs (k) can be described as equation (1). Also Vs (k -1) and Vs(k -2) can be expressed as (2) and (3). Here, VL is the maximum peak value of Vs, and Vs(k -l)is defined as V re 620 Vs Fig. 1. Block diagram of proposed method Vs(k) Vs(k-l) Vs(k-2) Vm cos(wt) Vm cos(w(t -Ts)) = Vre vm cos(w(t -2Ts)) (1) (2) (3) Differentiate (I) and (3), adapting the formula of trigonometric function (4), (5) can be derived.cos u -cos v Vs(k -2) -Vs(k) Vs(k -2) -Vs(k) 2wTs -2 sin u + v sin u -v (4) 2 2 Vm{cos(w(t -2Ts)) -coswt} Vm {2 sin(wTs) sin(w(t -Ts m v,--"'-{sin(wTs) sin(w(t -Tsm wTs Vm sin(w(t -Ts)) = V Im ( 5 ) It is obvious that the phase of Vim delays 90° than the phase of V re , so using only the single phase voltage with 3 sampled data. V re and Vim form the rectangular coordinates system same as the a-...

New flatness‐based control of a high‐voltage generator for medical X‐ray applications

“…Both were operated with a sample rate of 100 Msps. The zero crossing of the resonant current has been detected using a phase‐locked loop [17], as the switching of the power semiconductors in the H‐bridge has to be started in advance to the resonance current zero crossing to ensure proper commutation behaviour. To achieve very fast switching of the power semiconductors, silicon‐carbide (SiC) MOSFETs are used in the experimental set‐up.…”