Design and Control of Parallel Three-Phase AC Motor Drives in Battery-Electric Heavy-Haul Freight Locomotives
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Authors
Matthews, Peter Darrach
Date
2024-09-12
Type
thesis
Language
eng
Keyword
Power Electronics , Electric Vehicles , Control Theory
Alternative Title
Abstract
The transportation sector is one of the largest contributors to global greenhouse gas emissions. Due to climate change, many companies operating within the transportation sector are seeking to reduce their emissions, including Ontario Northland Rail (ONR), who operate afreight rail network in northern Ontario. ONR currently relies on diesel powered locomotives for their freight rail operations. To reduce ONR’s greenhouse gas emissions, researchers at the ePOWER facility of Queen’s University have proposed the development of a prototype battery-electric locomotive which could work in tandem with existing diesel locomotives to hybridize a freight train.
One important component of any electric vehicle is the motor drive, which is the electronic circuit which manages the flow of power between the electric traction motors and the vehicle’s
battery. In this thesis, a parallel motor drive system suitable for high power AC traction applications, such as battery-electric locomotives, is proposed. A novel control scheme is developed which is implemented directly in the natural, abc, reference frame and overcomes the primary challenge when designing parallel motor drive systems: circulating currents. At the core of this control strategy is a proposed Resonant Proportional Integral (RPI) controller, which uses integrated plant dynamics to achieve the functionality of a second-order Proportional Resonant (PR) controller using only a first-order Proportional Integral (PI) controller. Hence the proposed control strategy is very simple, requiring only an inner first-order RPI controller for the stator currents and an outer PI controller for motor speed and maximum torque per ampere (MTPA) operation.
A theoretical analysis of the controller is given, which shows the control is robust and stable for all expected motor speeds. The proposed motor drive system is then simulated using the proposed controller and a conventional controller. The proposed control system is found to match the dynamic speed and torque performance of the conventional controller while also effectively suppressing the circulating currents. Prototype inverter modules are then designed and used to experimentally validate the proposed control scheme. The experimental results show that the proposed control method achieves the claimed performance.