The three-phase single-stage differential boost inverter (DBI) has drawn significant attention in power conversion systems when feeding permanent magnet synchronous motors (PMSM). It offers advantages such as single-stage boosting, high efficiency, cost-effectiveness, and a compact structure. However, its nonlinear and non-minimum phase characteristics pose challenges for control. In this paper, the application of model predictive control (MPC) for PMSM fed by the three-phase DBI is focused on. Firstly, the modeling method of the three-phase DBI is presented. Subsequently, an MPC approach for PMSM fed by three-phase DBI is proposed. Based on the established predictive models of circuit currents and voltages, the appropriate duty cycle for the next sampling period can be predicted, which simplifies the control process and parameter design compared to traditional exclusively PI-based control. Simulation experiments are carried out to verify the effectiveness of the proposed MPC strategy for PMSM driven by the three-phase DBI.

The three-phase differential boost inverter is a special type of power inverter that offers single-stage boosting capability, combining high efficiency, low cost and compact size. However, it is complicated to control due to its non-linearity. Conventional open-loop control and dual-loop proportional-integral (PI) control is realized through the pulse width modulation (PWM). This paper reviews the basic principles and conventional control methods of the three-phase differential boost inverter. Then, a model predictive control (MPC) method of the three-phase DBI is proposed. Based on the established discrete models of circuits currents and voltages, the optimal switching state can be selected relying on a predefined cost function. Simulation studies are carried out to verify effectiveness of the proposed MPC of three-phase DBI.

The boost converter-based single-stage buck/boost inverter overcomes challenges that step-up voltage limitations of traditional voltage source inverter, the increased cost and control complexity of two-stage inverters, and the limited step-up range of single-stage impedance source inverters. Whereas, its ac output includes a dc bias at the value of dc source voltage and ac load voltage amplitude. Therefore, its boost ratio would be still limited because of the voltage rating limitation of practical power devices. This paper proposes a novel high-gain single-stage buck/boost inverter, without loss of low voltage stress and high boost ratio. The topology, operating principle, and modulation are disclosed. Simulation studies are carried out to demonstrate effectiveness of the proposed inverter.

The LC filter integrated quasi-Z source indirect matrix converter (QZS-IMC) filters the input voltages and currents while highly expanding voltage boost ratio through the combined QZS network, avoiding the additional input filter while maintaining full-silicon solution. The traditional proportional-integral (PI) control method of IMC is realized through the PI regulators with pulse width modulation (PWM), which is complicated due to elaborated vectors computation and duty cycle composition of IMC and extra control loops design is mandatory. This paper proposes a model predictive control (MPC) for the LC filter integrated QZS-IMC. Based on the established discrete models of circuit voltages and currents, the proposed control method measures the present circuit variables and predicts the variables in the next sampling period. Then, a predefined cost function is evaluated with the predictions and references at each active switching states of the IMC. An optimal switching state that ensures the smallest value of the cost function is applied to the power devices at the beginning of next sampling time. Simulation studies are carried out to demonstrate effectiveness of the proposed MPC for the LC filter integrated QZS-IMC.

The back-to-back connection of two three-to-single-phase matrix converters (MCs) through a high-frequency transformer to create the so called MC-based solid state transformer (SST) for interactive grid interfacing is proposed in this paper. The solution provides single-stage bidirectional ac-ac power conversion. There are advantages of no lifetime-limited storage capacitors, light weight, and compact volume. The conventional modulation methods of this MC-SST system require additional control design for power management. Besides, space vector modulation contains sophisticated voltage and current vectors computation and duty cycle composition, considering the two back-to-back connected three-to-single-phase MCs. In this paper, a model predictive control (MPC) is proposed for this MC-SST linking different ac grids. The proposed MPC predicts the state variables based on the discrete model of MC-SST system and the present circuit variables, and then selects an optimal switching state that ensures the smallest value of a cost function, for the next sampling time. Simulation and experimental studies are carried out to demonstrate effectiveness and simplicity of the proposed MPC for such MC-SST grid-interfacing system.

A high-frequency (HF) ac linked universal converter is proposed for distributed generations interfacing three-phase ac with single-phase ac or dc. The primary and secondary of the HF isolation transformer are, respectively, formed by a three-to-single-phase matrix converter and a cyclo converter. Based on the operating principle, a general and simple to be implemented space vector modulation (SVM) is developed from that for the conventional indirect matrix converter and constantly operated virtual dual-active-bridge converter. Simulation studies carried out on different amplitudes and frequencies of single-phase ac output and dc output demonstrate effectiveness and simplicity of the proposed converter with the SVM solution.

A dc-link voltage balancing control strategy for quasi-Z-source cascaded H-bridge (qZS-CHB) inverter photovoltaic (PV) power system is proposed by using multidimensional pulse-width modulation (MD-PWM) technique. The qZS-CHB PV system usually employs proportional-integral (PI) regulators based closed-loop control methods to balance dc-link voltages, combining with distributed maximum power point tracking and grid-tie power control. These require significant control computations and hardware resources for multiple modules based qZS-CHB system. The proposed MD-PWM for the qZS-CHB inverter performs shoot-through behavior based on geometric representation of the output voltage ranges of each H-bridge in coordinate axes. All possible switching sequences of the qZS-CHB inverter are taken into account to choose the most suitable sequence that can balance dc-link voltages of qZS modules in the qZS-CHB PV power system. When compared with the state-of-the-art of voltage balancing control methods, the proposed control strategy has advantages: 1) The computation is low because there is no PI controller, while the stability of the whole system is improved; and 2) there is a reliable balancing capability with fast regulation of dc-link voltages, owing to no extra controller parameters and handling the voltage balance in each control cycle. Simulation and experimental results of qZS-CHB inverter based grid-tie PV power system verify the proposed dc-link voltage balancing control technique.

The power decoupling strategies of single-phase Z-source/quasi-Z-source inverter (ZSI/qZSI) to handle the inherent double-line-frequency (2ω) power are overviewed. They are categorized as passive and active power decoupling methods. The former suppresses the 2ω ripple by the impedance network, modified modulation methods, or closed-loop damping control. The latter diverts the 2ω ripple to the compensation capacitor of integrated active power filters, through properly operating a half-bridge phase leg. The pros and cons of those 2ω power decoupling methods are discussed and recommendations are given for future development of such single-phase inverters.

An active power filter (APF) integrated quasi-Z-source cascaded multilevel inverter (qZS-CMI) is proposed in this paper. The purpose of incorporating the APF is to independently divert the second-order harmonic (2ω) power from dc side to APF's capacitor, for each of the cascaded single-phase quasi-Z-source inverter (qZSI) modules. The APF capacitor allows highly fluctuated ac voltage and current, with a small capacitance. The each module's qZS inductors and capacitors only handle the switching-frequency voltage and current ripple. Thus, the impedance values are as small as a three-phase qZSI, avoiding bulky inductors and capacitors in high-power applications. Operating principle and 2ω power buffering ability of the APF integrated qZS-CMI are analyzed. Design of the APF circuit parameters is illustrated. Simulation results demonstrate the validity of the proposed approach.

The single-phase quasi-Z source inverter (qZSI) topology has recently attracted attention for single-phase grid-tie photovoltaic (PV) applications. However, due to the inherent second-harmonic power flow in single-phase systems, a large qZS network is required to reduce the second-harmonic component of currents and voltages on the dc side. Minimization of the qZS network remains an open issue. This paper proposes a technique that minimizes the qZS capacitance and inductance of the single-phase qZSI topology by employing dc-side low-frequency current ripple damping control. Through analysis of power flow, a second-harmonic power model is derived and the ripple power is analyzed for minimization of the qZS network. A current ripple damping control is proposed to ensure suppression of second-harmonic power flow through the inductors. Simulation and experimental results verify the theoretical analysis, damping control, and the proposed design minimization of the qZS network for the single-phase topology.

A hybrid pulsewidth modulated single-phase quasi-Z-source grid-tie photovoltaic (PV) power system is proposed. The hybrid pulse-width modulation (HPWM) combines the pulse-width modulation (PWM) and the pulse-amplitude modulation (PAM). The PWM works when the ac output voltage is lower than the dc source voltage; otherwise, the PAM operates the single-phase quasi-Z-source inverter (qZSI). The HPWM leads to the reduction of power loss, and the quasi-Z-source capacitance and inductance. An effective control strategy is proposed for the new PV power system to manage the maximum power point tracking (MPPT) of PV panel, grid-tie power injection, and dc-link voltage. A grid-tie current controller, combining a repetitive controller and a proportional-resonant regulator, achieves strong harmonic suppression, fast dynamic, and zero tracking error. A 500-W prototype is built to verify the new system. Power loss estimation and impedance design are detailed. Experimental tests validate the HPWM, new PV power system with higher efficiency, and the related control method.

The active power filter (APF) that consists of a half-bridge leg and an ac capacitor is integrated in the single-phase quasi-Z-source inverter (qZSI) in this paper to avoid the second harmonic power flowing into the dc side. The capacitor of APF buffers the second harmonic power of the load, and the ac capacitor allows highly pulsating ac voltage, so that the capacitances of both dc and ac sides can be small. A model predictive direct power control (DPC) is further proposed to achieve the purpose of this new topology through predicting the capacitor voltage of APF at each sampling period and ensuring the APF power to track the second harmonic power of single-phase qZSI. Simulation and experimental results verify the model predictive DPC for the APF-integrated single-phase qZSI.

An effective control method, including system-level control and pulsewidth modulation for quasi-Z-source cascade multilevel inverter (qZS-CMI) based grid-tie photovoltaic (PV) power system is proposed. The system-level control achieves the grid-tie current injection, independent maximum power point tracking (MPPT) for separate PV panels, and dc-link voltage balance for all quasi-Z-source H-bridge inverter (qZS-HBI) modules. The complete design process is disclosed. A multilevel space vector modulation (SVM) for the single-phase qZS-CMI is proposed to fulfill the synthetization of the step-like voltage waveforms. Simulation and experiment based on a seven-level prototype are carried out to validate the proposed methods.

This paper proposes a new four-quadrant adjustable speed drive (ASD) system based on an induction motor fed by a three-phase quasi-Z-source direct matrix converter (QZSDMC). The quasi-Z-source (QZS) network is used to overcome the limitation of the voltage gain of the traditional direct matrix converter (DMC). The QZSDMC can provide a buck-boost operation by controlling the shoot-through (ST) duty ratio. In addition, this paper presents a four-quadrant speed control method based on vector control technique which is able to control the motor speed from zero to the rated speed with the full load torque during motoring and regenerating operation modes. The simulation results validate the proposed QZSDMC based adjustable speed drive system. The proposed ASD system overcomes the voltage gain limitation of the traditional direct matrix converter with improved efficiency and higher readability compared to the traditional back-to-back converter configuration.

As the development of Z-source / quasi-Z-source inverter (ZSI/qZSI), it appears several modified Space Vector Modulations (SVMs) for controlling them. Here, three typical SVMs are investigated and another extended one is also presented. The inductor current ripple, capacitor voltage gain, efficiency, and other performances of these control schemes are analyzed respectively. Simulation and experimental results validate the simplicity, reliability and efficiency of these SVM techniques for ZSI/qZSI, and the distinguished characteristics are reflected as well.

This paper proposes a three-phase quasi-Z-source matrix converter based induction motor adjustable-speed drives. The quasi-Z-source unique impedance network is utilized to overcome the limitation of the voltage gain of traditional matrix converter. The quasi-Z-source matrix converter can provide buck-boost function by controlling shoot-through duty ratio and modulation index. Analysis base on state-space equation shows the relationship among the shoot-through duty ratio and boost factor as well as voltage gain. Also, the proposed speed control method is able to change the motor speed from zero to the rated speed with the full load torque. The operating principle and system analysis are presented in detail. The simulation results validate the proposed quasi-Z-source matrix converter based adjustable speed drives.