Electric-drive vehicle emulation using advanced test bench

Vehicle electrification is considered to be the most promising approach toward addressing the concerns on climate change, sustainability, and rapid depletion of fossil fuel resources. As a result electric-drive vehicle (EDV) technology is becoming the subject of many research studies, from academia and research laboratories to automotive industries and their suppliers. However, a crucial step toward the success of EDV implementation is developing test platforms that closely emulate the behavior of these vehicles. In this dissertation, a new approach for emulating an EDV system on a motor/dynamometer test bench is investigated. Two different methods of emulation are discussed which are based on predefined drive cycle and unpredictable driving behavior. MATLAB/Simulink is used to model the test bench and simulations are carried out for each case. Experimental test bench results are also presented to validate hardware-in-the-loop (HIL) real-time performance for each method. Furthermore, to provide a more realistic approach towards EDV emulation a braking system suitable for motor/dynamometer architecture is proposed. The proposed brake controller represents a very close model of an actual EDV braking system and takes into account both regenerative and friction braking limitations. Finally, the challenges and restrictions of using a full scale test bench are outlined. To overcome these limitations, the development of an educational small scale hybrid electric vehicle (HEV) learning module is discussed which provides an ideal test platform to simulate and study both electric and HEV powertrains --Abstract, page iv

Modeling, Analysis, and Control Design of a Single-Stage Boost Inverter

A single-phase, single-stage, differential boost inverter comprises two independently-controlled boost DC-DC converters, with the load connected between their outputs. The net voltage on the load is sinusoidal and has a controllable frequency and magnitude that is larger than that of the DC source. The present work first derives steady-state and small-signal models of the inverter with parasitic elements. The results obtained from the line-to-output transfer function, control-to-output transfer function, open-loop input impedance, and open-loop output impedance models are compared with that of the ones obtained from the experimental testbed. Using the new models, a voltage mode controller is designed in the synchronous reference frame. The regulator design is explored through the use of an example. The results are verified against the small-signal model, then PLECS simulations, and finally a laboratory experiment. The results indicate excellent agreement between the model and experiment during transients in voltage reference, input source voltage, and output load. A sensitivity analysis is performed based on the inverter model considering the parameter variation. Finally, loss and efficiency estimations are provided in this work

An Overview of Direct Current Distribution System Architectures & Benefits

This paper examines existing and future direct current (DC) distribution systems with a wide range of applications in data centers, telecommunication systems, commercial buildings, residential homes, electric vehicles, spacecraft, and aircrafts. DC distribution systems have many advantages and disadvantages over their alternating current (AC) counterparts. There are a few surviving examples of DC distribution systems; among them are the telecommunication systems and data centers that use the low-voltage 48 Vdc systems. However, recently, there has been a move towards higher DC bus voltages. In this paper, a comparative study of different DC distribution architectures and bus structures is presented and voltage level selection is discussed for maximizing system efficiency and reliability, reducing system costs, and increasing the flexibility of the system for future expansion. Furthermore, DC distribution systems are investigated from a safety standpoint and the current global market for these distribution systems is also discussed

A New Stator Winding Inter-Turn Short Circuit Fault Detection Method For Brushless Doubly Fed Induction Machine

The brushless Doubly Fed Induction Machine (BDFIM) with high reliability and robust structure demonstrates technical and commercial advantages both as a generator and motor for variable speed drive applications. As a generator it is particularly attractive to be used in offshore wind turbines where reliability improvement and maintenance cost reduction are the key factors in wind power market growth. As a motor it can be utilized in application requiring adjustable speed operation. Inter-turn short circuit fault is one of the most frequent electrical faults in electric machines, which can also be the cause of other stator winding faults in the machine, hence its early detection can significantly reduce the maintenance cost and improve reliability. In this paper a novel fault detection method for inter-turn short circuit fault is proposed for the BDFIM based on the discrete wavelet transform of the stator winding currents. The analytical winding function method as well as the finite element analysis of an experimental D180 BDFIM is used in order to verify the proposed fault detection method

Performance Improvement of a DC-DC Converter Feeding a Telecommunication Specific Distributed Power System Using Dynamic Decoupling Design

This work analyzes the stability of a distributed dc power system commonly used in telecommunication and data center applications and proposes a new design procedure based on dynamic decoupling of the effects of the downstream network on the upstream source converter. First, the small-signal model of the upstream converter is introduced. Next, the model of the downstream network is added to the converter model and the complete system model is extracted. Then, the loop gain of the upstream converter when it is feeding the downstream network and when it is feeding a single resistor is compared and the decoupling factor is found. Finally, simulation results are provided to verify the design procedure

Dynamic Modeling and Stability Analysis of an Experimental Test Bench for Electric-Drive Vehicle Emulation

This paper describes dynamic modeling and stability analysis of one of the dynamometers in an electric drive vehicle test bench designed based on two electromechanical dynamometers. The studied dynamometer is comprised of two electric machines coupled mechanically by one shaft. One of the electric machines acts as the traction motor and injects power to the shaft; the other machine emulates the road condition and absorbs power. This machine acts as a constant power load to the traction motor and degrades system\u27s stability margins

A Robust Hybrid Multilevel Rectifier with Adjustable Output Voltage and Variable Load

In order to obtain synergic benefits by using two different semiconductors such as thyristors and IGBTs, hybrid multilevel converters have been studied recently in the literature. In a grid connected application, unity power factor (PF) control and load voltage control should be achieved. The proposed hybrid multilevel rectifier consists of a main neutral point clamped (NPC) and cell cascaded H-bridges (CHB). Each CHB has a floating capacitor. Therefore, in order to reduce costs, the system regulates the floating capacitor voltages without using independent DC power sources. Additionally, a control strategy concerning the voltage unbalance problem on the main NPC is also considered. Under load resistance changes, the hybrid multilevel rectifier accomplishes unity PF and load voltage control as well as the regulation of CHB capacitor voltages. Experimental results combining all mentioned technologies show verification of the robust hybrid multilevel rectifier in a grid connected application

Equivalent Vehicle Rotational Inertia Used for Electric Vehicle Test Bench Dynamic Studies

This paper provides an easy yet accurate approach for estimating vehicle inertia for the purpose of simulating the effect of vehicle inertia using a large flywheel. The method used to properly map the linear inertia of a vehicle to an equivalent rotational inertia is described in detail and an expression for equivalent rotational inertia of a vehicle is derived analytically using two different approaches considering kinetic energy of a moving mass in the linear and rotational context and vehicle dynamic equations. A MATLAB/Simulink model of a test bench consisting of a torque actuator connected to a large flywheel is used to emulate the effect of vehicle inertia. Using this model, the dynamic inertia effect of an electric vehicle on its traction motor is illustrated for two standard drive cycles. The results obtained from simulation are validated by ADVISOR to confirm the effectiveness of the proposed method in estimating vehicle inertia and it is shown that the use of a flywheel with a calculated rotational inertia using the proposed method can be sufficient in emulating vehicle inertia effect on a test bench

A Novel Combined Control Strategy for a Two-Stage Parallel Full-Wave ZCS Quasi Resonant Boost Converter for PV-Based Battery Charging Systems with Maximum Power Point Tracking

This work deals with the design and validation of a combined control strategy to satisfy the requirements for both soft switching and Maximum Power Point Tracking (MPPT) for a Photo Voltaic based (PV-based) battery charging system. The proposed controller is employed for a two-stage parallel full-wave Zero Current Switching (ZCS) quasi resonant boost converter to obtain maximum voltage using Perturb and Observation (P&O) method. The controller utilizes frequency modulation to regulate the output voltage, considering any changes experienced due to the intermittent nature of the PV system. Operating principles of the tow-stage parallel boost converter are thoroughly analyzed, and Matlab Simscape toolbox and its real-time workshop capability is utilized to evaluate the performance of the proposed controller for a battery charging system