Design and Development of a Class EF2 Inverter and Rectifier for Multi-megahertz Wireless Power Transfer Systems

This paper presents the design and implementation of a Class EF2 inverter and Class EF2 rectifier for two -W wireless power transfer (WPT) systems, one operating at 6.78 MHz and the other at 27.12 MHz. It will be shown that the Class EF2 circuits can be designed to have beneficial features for WPT applications such as reduced second-harmonic component and lower total harmonic distortion, higher power-output capability, reduction in magnetic core requirements and operation at higher frequencies in rectification compared to other circuit topologies. A model will first be presented to analyze the circuits and to derive values of its components to achieve optimum switching operation. Additional analysis regarding harmonic content, magnetic core requirements and open-circuit protection will also be performed. The design and implementation process of the two Class-EF2-based WPT systems will be discussed and compared to an equivalent Class-E-based WPT system. Experimental results will be provided to confirm validity of the analysis. A dc-dc efficiency of 75% was achieved with Class-EF2-based systems

AC voltage regulation of a bidirectional high-frequency link converter using a deadbeat controller

This paper presents a digital controller for AC voltage regulation of a bidirectional high-frequency link (BHFL) inverter using Deadbeat control. The proposed controller consists of inner current loop, outer voltage loop and a feed-forward controller, which imposes a gain scheduling effect according to the reference signal to compensate the steady-state error of the system. The main property of the proposed controller is that the current- and the voltage-loop controllers have the same structure, and use the same sampling period. This simplifies the design and implementation processes. To improve the overall performance of the system, additional disturbance decoupling networks are employed. This takes into account the model discretization effect. Therefore, accurate disturbance decoupling can be achieved, and the system robustness towards load variations is increased. To avoid transformer saturation due to low frequency voltage envelopes, an equalized pulse width modulation (PWM) technique has been introduced. The proposed controller has been realized using the DS1104 digital signal processor (DSP) from dSPACE. Its performances have been tested on a one kVA prototype inverter. Experimental results showed that the proposed controller has very fast dynamic and good steady-state responses even under highly nonlinear loads

A describing function for resonantly commutated H-bridge inverters

Abstract—The paper presents the derivation of a describing function to model the dynamic behavior of a metal oxide semiconductor field effect transistor-based, capacitively commutated H-bridge, including a comprehensive explanation of the various stages in the switching cycle. Expressions to model the resulting input current, are also given. The derived model allows the inverter to be accurately modeled within a control system simulation over a number of utility input voltage cycles, without resorting to computationally intensive switching-cycle level, time-domain SPICE simulations. Experimental measurements from a prototype H-bridge inverter employed in an induction heating application, are used to demonstrate a high degree of prediction accuracy over a large variation of load conditions is possible using the simplified model

Development of reliability methodology for systems engineering. Volume II - Application - Design reliability analysis of a 250 volt-ampere static inverter Final report

Design stage reliability analysis application to static inverte

Tradeoffs between AC power quality and DC bus ripple for 3-phase 3-wire inverter-connected devices within microgrids

Visions of future power systems contain high penetrations of inverters which are used to convert power from dc (direct current) to ac (alternating current) or vice versa. The behavior of these devices is dependent upon the choice and implementation of the control algorithms. In particular, there is a tradeoff between dc bus ripple and ac power quality. This study examines the tradeoffs. Four control modes are examined. Mathematical derivations are used to predict the key implications of each control mode. Then, an inverter is studied both in simulation and in hardware at the 10 kVA scale, in different microgrid environments of grid impedance and power quality. It is found that voltage-drive mode provides the best ac power quality, but at the expense of high dc bus ripple. Sinusoidal current generation and dual-sequence controllers provide relatively low dc bus ripple and relatively small effects on power quality. High-bandwidth dc bus ripple minimization mode works well in environments of low grid impedance, but is highly unsuitable within higher impedance microgrid environments and/or at low switching frequencies. The findings also suggest that the certification procedures given by G5/4, P29 and IEEE 1547 are potentially not adequate to cover all applications and scenarios

Analysis and modeling of power supply induced jitter for high speed driver and low dropout voltage regulator

”With the scaling of power supply voltage levels and improving trans-conductance of drivers, the sensitivity of drivers to power supply induced delays has increased. The power supply induced jitter (PSIJ) has become one of the major concerns for high-speed system. In this work, the PSIJ analysis and modeling method are proposed for high speed drivers and the system with on-die low dropout (LDO) voltage regulator. In addition, a jitter-aware target impedance concept is proposed for power distribution network (PDN) design to correlate the PSIJ with PDN parasitic. The proposed PSIJ analysis model is based on the driver power supply rejection ratio (PSRR) response, transition edge slope and the propagation delay. It is demonstrated that the proposed model can be generalized for different type of drivers. Following the proposed PSIJ model, a method for improving the PSIJ simulation accuracy in the input/output buffer information (IBIS) model is also proposed. A PSIJ analysis method is also proposed for system with on-die LDO. The approach relies on separate analysis of the LDO block PSRR response and the buffer block PSIJ sensitivity. This procedure allows designer to evaluate the system PSIJ with fewer and faster simulations. For the jitter-aware target impedance, a systematic procedure to develop the target impedance curves is formulated and developed for common CMOS buffer circuits. Given the transient IC switching current and the jitter specification, multiple target impedance curves can be defined for a specific circuit. The proposed design procedure can largely relieve over-constrain in the PDN designed based on the original target impedance definition”--Abstract, page iv

Smart PV Inverter Control for Distribution Systems

PV solar systems employ inverters to transform dc power from solar panels into ac power for injecting into the power grids. Inverters that perform multiple functions in addition to real power production are known as “smart inverters”. This thesis presents a novel control of PV inverter as a dynamic reactive power compensator – STATCOM. This “smart PV inverter” control enables a PV solar inverter to operate in three modes – i) Full PV, ii) Partial STATCOM, and iii) Full STATCOM, depending upon system needs. The novel control is developed and demonstrated for the objectives of a) symmetrical voltage regulation, b) temporary overvoltage reduction, c) power factor correction, and d) reactive power control. In Full PV mode, the inverter performs only real power production based on solar radiation. In Partial STATCOM mode, the controller uses the remaining capacity of the inverter for voltage control, power factor correction and reactive power control. The Full STATCOM mode is invoked in emergency scenarios, such as faults, or severe voltage fluctuations. In this mode, the real power production is shut down temporarily and the entire inverter capacity is utilized for voltage regulation or TOV curtailment for providing critical support to the power system. This thesis presents a comprehensive design of the proposed smart inverter controller with all its associated system components. The performance of the smart inverter is simulated using the electromagnetic transients software PSCAD/EMTDC. It is further validated through Real Time Digital Simulation and Control Hardware in the Loop (CHIL) simulation. Finally the successful performance of the smart inverter controller is demonstrated on a 10 kW inverter in the laboratory on a simulated feeder of Bluewater Power, Sarnia, where this smart inverter is proposed to be installed. The smart PV inverter control is further shown to enhance the connectivity of PV solar farms in a realistic 44 kV Hydro One distribution feeder. It is demonstrated that if such a novel control is implemented on a 10 MW solar farm, the need for the actually installed STATCOM for voltage regulation and TOV control can be either minimized or altogether eliminated, bringing a significant savings for the utility PV solar systems employ inverters to transform dc power from solar panels into ac power for injecting into the power grids. Inverters that perform multiple functions in addition to real power production are known as “smart inverters”. This thesis presents a novel control of PV inverter as a dynamic reactive power compensator – STATCOM. This “smart PV inverter” control enables a PV solar inverter to operate in three modes – i) Full PV, ii) Partial STATCOM, and iii) Full STATCOM, depending upon system needs. The novel control is developed and demonstrated for the objectives of a) symmetrical voltage regulation, b) temporary overvoltage reduction, c) power factor correction, and d) reactive power control. In Full PV mode, the inverter performs only real power production based on solar radiation. In Partial STATCOM mode, the controller uses the remaining capacity of the inverter for voltage control, power factor correction and reactive power control. The Full STATCOM mode is invoked in emergency scenarios, such as faults, or severe voltage fluctuations. In this mode, the real power production is shut down temporarily and the entire inverter capacity is utilized for voltage regulation or TOV curtailment for providing critical support to the power system. This thesis presents a comprehensive design of the proposed smart inverter controller with all its associated system components. The performance of the smart inverter is simulated using the electromagnetic transients software PSCAD/EMTDC. It is further validated through Real Time Digital Simulation and Control Hardware in the Loop (CHIL) simulation. Finally the successful performance of the smart inverter controller is demonstrated on a 10 kW inverter in the laboratory on a simulated feeder of Bluewater Power, Sarnia, where this smart inverter is proposed to be installed. The smart PV inverter control is further shown to enhance the connectivity of PV solar farms in a realistic 44 kV Hydro One distribution feeder. It is demonstrated that if such a novel control is implemented on a 10 MW solar farm, the need for the actually installed STATCOM for voltage regulation and TOV control can be either minimized or altogether eliminated, bringing a significant savings for the utilit

Robust H8 design for resonant control in a CVCF inverter application over load uncertainties

CVCF (constant voltage, constant frequency) inverters are electronic devices used to supply AC loads from DC storage elements such as batteries or photovoltaic cells. These devices are used to feed different kinds of loads; this uncertainty requires that the controller fulfills robust stability conditions while keeping required performance. To address this, a robust H8 design is proposed based on resonant control to track a pure sinusoidal voltage signal and to reject the most common harmonic signals in a wide range of loads. The design is based on the definition of performance bounds in error signal and weighting functions for covering most uncertainty ranges in loads. Experimentally, the H8 controller achieves high-quality output voltage signal with a total harmonic distortion less than 2%Peer ReviewedPostprint (published version

Wireless Power System Design for Maximum Efficiency

With the potential of cutting the last cord, wireless power transfer (WPT) using magnetic resonant coupling is gaining increasing popularity. Evolved from the inductive WPT techniques used in commercial products today, resonant WPT can transfer power over a longer distance with higher spatial freedom. Experimental prototypes have shown power transfer across a 2 m air gap [1], proving the viability of resonant WPT. Industrial consortia such as the AirFuel Alliance have standard specifications that enable wide application in consumer electronics.Despite the promises of high efficiency and long transfer distance, resonant WPT has significant challenges to overcome before the broad adoption will occur. One of the critical challenges is the how to design the complicated system. A WPT system consists of multiple parts: the transmitter coil and the compensation capacitor, the receiver coil and the compensation capacitor, and the power stages which consists of the inverter in the transmitter side and rectifier in the receiver side. This thesis investigates the WPT system design for maximum efficiency. It explores modeling and design of individual stages as well as the entire system design method. From the careful literature review, it is found that current design method of coils is insufficient for consumer electronics applications due to the strict sensitivity of size. The current power stage design method is insufficient or inaccurate for WPT applications where wide loading situations need to be considered. The system-level design method is based on assumptions that are not generally true due to the neglect of ZVS requirement and diode rectifier reactance. Instead, previously established techniques in coil design are applied to invent a new coil structure for reduced ESR while achieving a compact size. Previous ZVS inverter and diode rectifier topology are combined with waveform and circuit analysis to develop new accurate modeling and design method for a wide load range. From the resulting coil and converter models, an entire WPT system model and design methodology are proposed which highlights the design parameters selection and the design sequence. These techniques together contribute to a WPT system in terms of both high efficiency and compact size