As an emerging molecular imaging modality, Photoacoustic Tomography (PAT) is capable of mapping tissue physiological metabolism and exogenous contrast agent information with high specificity. Due to its ultrasonic detection mechanism, the precise localization of targeted lesions has long been a challenge for PAT imaging. The poor soft-tissue contrast of the PAT image makes this process difficult and inaccurate. To meet this challenge, in this study, we first make use of the rich and clear structural information brought about by another advanced imaging modality, Magnetic Resonance Imaging (MRI), to assist organ segmentation and correct for the light fluence attenuation of PAT. We demonstrate improved feature visibility and enhanced localization of endogenous and exogenous agents in the fluence corrected PAT images. Compared with PAT-based methods, the contrast-to-noise ratio (CNR) of our MRI-assisted method increases by 29.1% in live animal experiments. Furthermore, we show that the co-registered MRI image can also be incorporated into PAT image restoration, and achieves improved anatomical landscape and soft-tissue contrast (CNR increased by 25.36%) while preserving similar spatial resolution. This PAT-MRI combination provides excellent structural, functional and molecular images of the subject, and may enable more comprehensive analysis of various preclinical research applications.

In this paper, a current control is studied based on D-Σ digital control to improve the grid-connected performance for a three-level T-type inverter. The control principle is analyzed in accordance with the single-phase equivalent circuit of the three-level T-type inverter. The influence of the neutral-point voltage on both output current error and modulation signal is discussed, and the relationship expression is deduced. Finally, a simulation circuit of 5kVA three-level T-type grid-connected inverter is built, which proves the effectiveness of D-Σ digital control, and verifies that the control has excellent dynamic and static performances.

Due to the intermittent feature of renewable energy sources, energy storage units are needed in order to balance the electricity generation and consumption. Interface circuit is an important component of the energy storage system. This paper presents a non-isolated four-port dc-dc converter for the independent photovoltaic power generation system. The proposed four-port dc-dc convert is used to interface four power ports. These are photovoltaic cells (PV) port, battery port, super capacitor port and load port separately. The circuit topology is derived by integrating several parallel Boost converters. The operation principles and the performance are analyzed in detail. The mathematical model of the proposed converter is built. The four-port dc-dc converter can realize energy bidirectional flow among PV, energy storage medium and load. It can also realize the DC bus voltage stable and ensure balance of system power. Finally, simulation results are given to verify the validity and feasibility of the non-isolated four-port dc-dc converter in the independent photovoltaic energy generation system.

A soft-switching solution implemented to the traditional bidirectional DC/DC converter is developed. The soft-switching cell, which composed of three auxiliary switches, one resonant capacitor and one resonant inductor, is equipped in the traditional bidirectional DC/DC converter to realize circuit ZCT or ZVT operations in both energy transmission directions. Two driving methods are presented to charging energy for different storage applications according to the storage materials' electrical characteristics. There are two methods in buck mode. The first method with low conduction losses suffers from a hard turning off process in one of the auxiliary switches, while the others experience the soft operation. As for the other method, the zero voltage or zero current transmissions in all switches are realized, however, the relative higher but fixed conduction losses are introduced by the resonant circle. And the proposed topology of bidirectional soft-switching dc-dc converter(TASBC) performs ideal soft switching at boost operations. The characteristics of the proposed converter has been verified by MATLAB simulations and experimental results.

The operation of a distributed maximum power point tracking (DMPPT) photovoltaic (PV) system with a current source inverter (CSI) is confirmed. We proposed a current-linked distributed PV system instead of a voltage-linked one. All the previous studies of DMPPT PV systems use a voltage source inverter (VSI). Moreover, all commercial power optimizers that are provided by Solar Edge, Solar Magic, Tigo Energy, and so on are assumed to be connected to a VSI. The drawback of the power conditioning system (PCS) with a VSI is that it has to carry an electrolytic capacitor, which determines the life span of the PCS. By using a CSI, the reliability of the PCS is greatly improved; moreover, the module integrated converter (MIC) can consist of a buck-only converter. In this paper, we implemented two cascaded MICs with a CSI and confirmed the operation of the entire current-linked distributed PV system. The experimental results agree strongly with the theory and it proves the validity of the proposed system.

In this paper, a novel generalized discontinuous space-vector pulse width modulation (DSVPWM) strategy called DSVPWMx, which includes DSVPWMP, DSVPWMN, DSVPWMPN0, DSVPWMPN1, DSVPWMPN2, and DSVPWMPN3, is proposed for three-phase voltage source inverters. Six sectors are redivided into 12 ones based on space-vector pulse width modulation (SVPWM) and local over modulation method. The principle of the new DSVPWMx is developed, essential relationship among different DSVPWMx strategies and linear modulation ranges of DSVPWMx are discussed. The characteristics for DSVPWMx and the traditional discontinuous pulse width modulation (DPWM) strategies such as DPWMMAX, DPWMMIN, DPWM0, DPWM1, DPWM2, and DPWM3 named as DPWMx are studied on the basis of harmonic distortion and switching loss. The simulation and experimental results verify that the DSVPWMx strategies are right and feasible.

A novel Z-source dual-bridge matrix converter (ZSDBMC) topology and its control strategy are proposed to overcome two main drawbacks of conventional matrix converters: low immunity to abnormal input voltage disturbance and low voltage transfer ratio. The boost voltage characteristic of Z-source network is utilized to improve the system voltage transfer ratio and make it immune to abnormal input voltage disturbance with shoot-through duty cycle self-adjusted. Meanwhile, nonlinear PID controller is employed to eliminate effects caused by nonminimum-phase characteristic presented in Z-source network and improve system dynamic performance and robustness. Moreover, a comparison of the topology respect a standard back-to-back converter, Dual bridge matrix converter and ZSDBMC was provided. Finally the operation principles and validity of this proposed ZSDBMC topology are analyzed in details and verified by simulation and experiment results.