Seang Shen Yeoh

Control design for PMM-based starter generator system for More Electric Aircraft

The paper deals with the control design of aircraft starter-generator system based on permanent magnet machine fed by active front end rectifier. The analysis of the starter-generator system can be split into 2 parts; starter and generator mode. Their respective control structures are proposed along with mathematical equations that represent the power system. Direct current field weakening method is selected for this high speed application while DC current control is considered during the generator mode. The nature of dynamic limiter employed along with the field weakening controller creates 2 states of operation. Linearized open loop plant models for both starter and generator modes are derived. The plants are verified with equivalent linear and non-linear Simulink models. Appropriate controllers are designed based on the closed loop analysis.

Aircraft starter-generator system based on permanent-magnet machine fed by active front-end rectifier

This paper deals with the control design for an aircraft electric starter-generator system that utilizes recent advances in modern power electronics allowing the use of novel machine types together with the introduction of controlled power electronics into the main path of energy flow. The paper describes the developed system and focuses on control design including flux weakening control of high-speed permanent magnet machine and droop control of the system output dc-link current. The analytical design results and the expected system performance are confirmed by time-domain simulations.

Hybrid modulated model predictive control for the more electric aircraft generator system

The More Electric Aircraft (MEA) has been identified to be a major trend for future aircrafts. One of the key improvements introduced in MEA is its electrical power generation system. The generator system studied in this paper comprises of a permanent magnet machine and an active front-end rectifier. Rather than just using PI controllers to control the generation system, Model Predictive Control (MPC) is considered due to its ability to achieve fast dynamic performance and multivariable control. A variant of MPC called Modulated Model Predictive Control (MPC with intrinsic modulator) was recently introduced that showed significantly better performance than the standard MPC method. This paper presents a control scheme that utilizes Modulated Model Predictive Control for the current inner loop and PI controllers for the outer loop. The proposed control is compared with a full cascaded PI control scheme. Simulation tests are carried out to compare the two control methods and the results are presented and analysed.

More electric aircraft starter-generator system with utilization of hybrid modulated model predictive control

The current trend for future aircraft is the adoption of the More Electric Aircraft (MEA) concept. The electrical based starter-generator (S/G) system is one of the core ideas from the MEA concept. The PI based control scheme has been investigated in various papers for the permanent magnet based S/G system. Different control schemes are to be considered to improve the control performance of the S/G system. A type of non-linear control called Model Predictive Control (MPC) is considered for its capability to accomplish fast dynamic control performance. The Modulated Model Predictive Control (variant of MPC with an intrinsic modulator) was presented that showed considerably better control performance than the standard MPC. A control scheme is presented in this paper that utilises PI controllers for the outer loop and Modulated Model Predictive Control for the inner loop that covers operation for both starter and generator modes. Simulation analyses are carried out to compare between the proposed control and a full cascaded PI control scheme. The proposed control is also subjected to parameter variation tests for performance evaluation.

Flux-Weakening Control of Electric Starter–Generator Based on Permanent-Magnet Machine

This paper presents the control analysis and design for a permanent-magnet machine (PMM) operated in the flux-weakening (FW) mode for an aircraft electric starter–generator (SG) application. Previous literature has focused on FW control of PMMs in the motoring (starting) mode; however, the system stability and control in the generating mode have been inadequately studied. This paper reports detailed, rigorous control analysis and design for a PMM-based aircraft electric SG operated in the FW mode. It is shown that an unstable area of operation exists. A novel control scheme which eliminates this instability is proposed. The key analytical findings of the paper are verified by experimental investigation. This paper therefore concludes that the presented technique is able to ensure system stability under all modes of operation. Furthermore, it is noted that the findings of this work are also valuable for any two-quadrant PMM drive with frequent change between starting and generating regimes under current-limiting operation.

Permanent-Magnet Machine-Based Starter–Generator System With Modulated Model Predictive Control

This paper describes a hybrid control scheme for a permanent magnet machine-based starter–generator (S/G) system. There has been increased usage of electric drive systems in the transportation sector for increased efficiency and reduced emissions. One of the advantages of utilizing suitable electric drives is the capability to operate as a starter or generator. The control design of such a system should be considered due to the operating requirements and fast load changes. Different control approaches should therefore be considered in order to achieve these goals, which are a current trend in the transportation sector. Model predictive control (MPC) is considered due to its very fast dynamic performance. In particular, modulated MPC (M2PC) was recently introduced and showed significantly better performance than the standard MPC. The control scheme used in this paper utilizes M2PC for the current inner loop and PI controllers for the outer loop. The use of M2PC allows very fast transient-current response for the S/G system. The proposed overall control benefits from reduced current ripple when compared with a full cascaded PI control scheme. Simulation analyzes and experimental results show the capability and performance of the designed controller across both starter and generator modes.

A detailed modular governor-turbine model for multiple-spool gas turbine with scrutiny of bleeding effect

Multiple-spool gas turbines are usually utilized for power supply in aircrafts, ships, and terrestrial electric utility plants. As a result, having a reliable model of them can aid with the control design process and stability analysis. Since several interconnected components are coupled both thermodynamically and through shafts, these engines cannot be modeled linearly as single shaft gas turbines. In this paper, intercomponent volume method (ICV) has been implemented for turbine modeling. A switched feedback control system incorporating bump-less transfer and antiwindup functionality is employed as governor for the engine. Validation with test results from a three spool gas turbine highlights high accuracy of turbine-governor model in various maneuvers. Results show that over-speed after load rejection is considerable due to the fact that in this arrangement, the power turbine (PT) is not coupled with the compressor which acts like a damper for single shaft gas turbines. To address this problem, bleed valves (mainly before combustion chamber) are used to arrest the over-speed by 20%. In addition, a switch is employed into the governor system to rapidly shift fuel to permissible minimum flow.

Stability assessment of a high speed permanent magnet machine based aircraft electrical power system

Starting an aircraft engine with an electrical machine has been one of the major trends for future aircraft. This paper studies the stability of a permanent-magnet machine (PMM) based aircraft starter/generator (S/G) system. Using control-to-output transfer functions, the stability analysis of this S/G system is thoroughly studied. The impact of the key parameters including the control parameters is analysed. Simulation and experimental results support the analytical result.

Control Design for PMM-Based Generator Fed by Active Front-End Rectifier in More-Electric Aircraft

The future aircraft electrical power system is expected to be more efficient, safer, simpler in servicing and easier in maintenance. As a result, many existing hydraulic and pneumatic power driven systems are being replaced by their electrical counterparts. This trend is known as a move towards the More-Electric Aircraft (MEA). As a result, a large number of new electrical loads have been introduced in order to power many primary functions including actuation, de-icing, cabin airconditioning, and engine start. Therefore electric power generation systems have a key role in supporting this technological trend. Advances in modern power electronics allow the concept of starter/generator (S/G) which enables electrical engine start and power generation using the same electrical machine. This results in substantial improvements in power density and reduced overall weight. One of the potential S/G solutions is to employ a permanent magnet machine (PMM) controlled by active front-end rectifier (AFE). Operation of the PMM as a generator at wide range of speed that is dictated by the engine and electrical loads connected to the aircraft bus require careful design of the controllers. Corresponding plant models are derived and verified with simulations using developed models in Matlab/Simulink. The relevant controllers are designed based on the derived plants and operating points. The controllers are tested with Simulink models and experimentally using a scaled prototype of the investigated generator system.