L. De Lillo

Multiphase Power Converter Drive for Fault-Tolerant Machine Development in Aerospace Applications

This paper describes an experimental tool to evaluate and support the development of fault-tolerant machines designed for aerospace motor drives. Aerospace applications involve essentially safety-critical systems which should be able to overcome hardware or software faults and therefore need to be fault tolerant. A way of achieving this is to introduce variable degrees of redundancy into the system by duplicating one or all of the operations within the system itself. Looking at motor drives, multiphase machines, such as multiphase brushless dc machines, are considered to be good candidates in the design of fault-tolerant aerospace motor drives. This paper introduces a multiphase two-level inverter using a flexible and reliable field-programmable gate-array/digital-signal-processor controller for data acquisition, motor control, and fault monitoring to study the fault tolerance of such systems.

Fault-Tolerant Matrix Converter Motor Drives With Fault Detection of Open Switch Faults

This paper describes a novel fault-tolerant matrix converter motor drive system which requires an appropriate control strategy and the application of an effective fault detection technique. Two types of fault-tolerant matrix converter, a direct matrix converter and an indirect matrix converter, are proposed for a permanent magnet synchronous motor drive against open-circuit faults in safety-critical applications. A fault-tolerant control strategy is developed in order to maintain the continuous operation of the drive system with satisfactory performance. A high-speed fault detection strategy for detecting and identifying the faulty open-circuited switches located in the fault-tolerant four-phase direct matrix converter is also proposed. Simulation and experimental results are shown to demonstrate the effectiveness of the proposed fault-tolerant matrix converters and the developed fault detection strategy applied to the motor drive system under faulty operating conditions.

Stability Study for a Hybrid AC-DC More-Electric Aircraft Power System

The paper deals with the small-signal stability analysis of aircraft ac frequency-wild power systems representing a real ac-dc hybrid distribution architecture with a multiplicity of actuators, aircraft loads, and bus geometries. The dq modelling approach is applied to derive individual power system component models and to constitute the corresponding generalized power system model as a powerful and flexible stability analysis tool. The element models can be interconnected in an algorithmic way according to a variety of the architecture selected. Intensive time-domain simulation and experimental results are used to verify the theoretical results. It is also shown how the proposed approach can be used to predict instability due to possible variations in operating points and system parameters.

Performance Evaluation of a Vector-Control Fault-Tolerant Flux-Switching Motor Drive

A novel fault-tolerant flux-switching permanent-magnet synchronous machine drive topology is presented, which is able to operate during open- and short-circuit winding and converter faults. The scheme is based on a dual winding motor supplied from two separate vector-controlled voltage-sourced inverter drives. The windings are arranged in a way so as to form two independent and isolated sets. Simulation and experimental work will detail the drives performance during both healthy and faulty scenarios including short-circuit faults and will show the drive robustness to operate in these conditions.

A comparison of the reliability of a matrix converter and a controlled rectifier-inverter

This paper compares the calculated reliability of a matrix converter with a controlled rectifier/inverter topology for an aerospace motor drive application. These topologies are functionally equivalent in terms of input power quality and regenerative capabilities. The military handbook MIL-HDBK-217F guidelines have been used to predict reliability. Although the matrix converter has a higher number of semiconductor switches, these switches are subjected to a lower voltage stress, which can shown to increase the device reliability. When this factor is taken into account it can be shown that the predicted reliability of the matrix converter is actually slightly better than the controlled rectifier-inverter solution

High speed electrical generators, application, materials and design

This paper highlights the advancement in high speed generation applications along with describing the state of the art in the materials and technologies enabling such an application uptake. Following the introduction, highlighting the current situation in the energy market, the first section describes some recent developments in materials used in the construction of a high speed drive. Various application areas are dealt with in section three and the state of the art along with design considerations of various machine topologies are discussed in section four. In section five a case study is presented highlighting the preliminary design procedure used to select a machine topology for a given application. Finally a summary discussing the design flow required when attempting such high speed design is presented in section six.

A 20 KW matrix converter drive system for an electro-mechanical aircraft (EMA) actuator

This paper describes the design, construction and testing of a 20 KW matrix converter driven electromechanical actuator for an aircraft rudder demonstrator. The converter has been built using three custom designed modules each one containing a number of 600 V, 300 A IGBTs and diodes sufficient to form a single output phase together with back to back diodes to detect the output current direction used in the commutation strategy. Practical results are shown. Description of the control structure, power circuit design, over voltage clamp circuit and practical results of the converter operating as an actuator position controller are presented

Enabling technologies for matrix converters in aerospace applications

The matrix converter is a direct AC-AC power converter topology that does not contain an intermediate DC-link stage. This paper presents different enabling technologies to enhance the suitability of the matrix converter topology for aerospace applications. The use of silicon carbide power devices to improve efficiency and reduce system weight together with an improved, high speed fault detection technique are presented. Results from different prototype matrix converters to validate the concepts are also presented.

The impact of matrix converter technology on motor design for an integrated flight control surface actuation system

This paper describes research related to producing integrated electric motor driven flight control surface actuation systems, for a More Electric Aircraft. The main requirements and motor options are discussed. The advantage of the matrix converter in terms of compactness, due to removal of energy storage elements, is highlighted. However, this advantage is shown to bring with it problems when motors which have pulsed voltage and current waveforms are employed. The resulting discontinuities in power flow during current commutations are reflected at the input terminals to the drive as supply current harmonics.

A power converter for fault tolerant machine development in aerospace applications

This paper describes an experimental tool to evaluate and support the development of fault tolerant machines designed for aerospace motor drives. Aerospace applications involve essentially safety critical systems which should be able to overcome hardware or software faults and therefore need to be fault tolerant. A way of achieving this is to introduce variable degrees of redundancy into the system by duplicating one or all of the operations within the system itself. Looking at motor drives, multiphase machines such as multiphase brushless DC machines are considered to be good candidates in the design of fault tolerant aerospace motor drives. The paper introduces a multi-phase two level inverter using a flexible and reliable FPGA/DSP controller for data acquisition, motor control and fault monitoring to study the fault tolerance of such systems.