Research Terms
Engineering Electrical Engineering
Keywords
Famu-Fsu College Of Engineering
In this invention, a novel single-phase single-stage grid-interactive inverter based on a discrete Fourier Transform Phase Locked Loop technique is developed to separate the real and reactive power between different energy sources/storages. The hybrid modulation technique and sophisticated power allocation strategy are developed for the power generation system to achieve wide range reactive power compensation and enhance energy conversion efficiency. One distributed energy source and two energy storages are interfaced to the inverter with three cascaded H -bridge cells used to investigate the performance of the proposed system. Different energy source/storages with wide voltage change range can be directly connected in the invention and the single-stage energy conversion can be implemented. The present invention can integrate distributed energy sources/storages in one cascaded inverter. Due to the absence of DC-DC converter, single-stage energy conversion can be achieved. The hybrid modulation technique and power allocation strategy corresponding to the proposed system are developed to achieve the wide range reactive power compensation, voltage boost function, and the optimized power management.
The proposed single-phase single-stage grid-interactive inverter is particularly suitable to meeting the increasing distributed power generation needs. It can facilitate to interface different distributed renewable energy sources or storages such as wind power, solar power, battery, fuel cell, Ultra-capacitor and so on. The switching loss will be decreased due to the cascaded structure and hybrid modulation technique.
In the present invention, different circuit-based implementations of stochastic anti-windup PI controllers are provided for a motor drive controller system. The designs can be implemented in a Field Programmable Gate Arrays (FPGA) device. The anti-windup PI controllers are implemented stochastically so as to enhance the computational capability of FPGA. The invention encompasses different circuit arrangements that implement distinct anti-windup algorithms for a digital PI speed controller. The anti-windup algorithms implemented by the circuit arrangements can significantly improve the control performance of variable-speed motor drives.
Compared with the existing technologies, the stochastic PI controller provides an efficient implementation approach that uses straightforward digital logic circuits but has the advantage of significantly reducing the circuit complexity. Therefore, the present invention notably improves the performance of the stochastic PI controller and saves digital resources in a motor drive control system. The immediate and/or future applications are motor drive controllers for induction motor systems, and more particularly, proportional-integral (PI) controllers. The use of the invention will increase the market of FPGA since the capability will be largely increased and the cost will be relatively reduced.
Two predictive-control based low-voltage ride-through methods for a grid-tied Inverter: a Finite-Control-Set Model-Predictive-Control or FCS-MPC based LVRT method, and a deadbeat control based LVRT method. Both methods can predict the grid voltage, so no voltage sensor is required. The control can operate with, or without, a phase-lock-loop. A significant cost and design complexity reduction on the grid-tied inverter is realized.
A voltage/current-sensing-less short-circuit (SC) protection for power devices that can identify which device has a SC fault within power modules or converters. It does NOT require sensing voltage or current magnitude of power device to detect and localize the SC fault, therefore it is low cost and enhances the noise immunity and reliability. This method can be applied to all switching power devices including muti-phase converters, modular converters, multilevel converters, and modular multilevel converters.
A charge pump gate driver circuit that provides an adjustable pump voltage level to achieve the active dv/dt control for wide bandgap devices. The driver circuit has two power supplies, which provides positive and negative reference voltages, two separate charge pump circuits with two capacitors, and a typical totem-pole drive with two decoupling capacitors. This achieves an online and active dv/dt regulation and eliminates extra power supplies to reduce cost and associated footprint.
A battery energy storage system (BESS) for medium voltage direct current (MVDC) or high voltage direct current (HVDC) grids or systems. The BESS comprises split-battery units and an isolated DC-DC converter interface connecting the battery units to the MVDC or HVDC system. The isolated BESS converter is a soft-switched modular multilevel dual-active-bridge (DAB) converter which has DC fault rid-through capability. The converters can be single-phase or poly-phase configurations and can be controlled to maintain a desired DC output under normal and DC grid fault conditions.
A gate driver for power semiconductors including metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs) that does not require isolated power supplies. The use of a circuit to transfer signal and power at the same time by a radio frequency (RF) transformer which works at several hundreds of a Megahertz and provides galvanic isolation. The frequency band is designed to be much larger than conducted electromagnetic interference (EM) frequency ranges, which are less than 30 Megahertz. The driver is free of standby power loss and has a built-in active gating function.
This invention presents a family of isolated battery energy storage system (BESS) topologies with multiple functions, which are suitable for high voltage and high-power DC grid application, including Medium Voltage Direct Current (MVDC) or High Voltage Direct Current (HVDC) applications. The modulation and control strategies of these topologies are also presented.
A device to solve over voltage issues caused by the reflected wave phenomenon (RWP). A motor drive connected to a motor through long cables can cause the reflection of the electromagnetic wave, resulting a voltage spikes at the motor side that is twice as high as the voltage at the drive side. This transient over voltage can damage the insulation of the motor or reduce its useful life. The canceler detects rising/following edge of the motor drive and generates a short pulse that breaks the voltage slope so that over voltage at motor side is suppressed.
A blanking-time-less desaturation protection method for power devices, by which the fault response time is shorter than the blanking time required by the existing protection methods.
