Constant power loads and negative impedance instability in automotive systems: definition, modeling, stability, and control of power electronic converters and motor drives
TL;DR: Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems operating with CPLs.
Abstract: Power electronic converters and electric motor drives are being put into use at an increasingly rapid rate in advanced automobiles. However, the new advanced automotive electrical systems employ multivoltage level hybrid ac and dc as well as electromechanical systems that have unique characteristics, dynamics, and stability problems that are not well understood due to the nonlinearity and time dependency of converters and because of their constant power characteristics. The purpose of this paper is to present an assessment of the negative impedance instability concept of the constant power loads (CPLs) in automotive power systems. The main focus of this paper is to analyze and propose design criteria of controllers for automotive converters/systems operating with CPLs. The proposed method is to devise a new comprehensive approach to the applications of power electronic converters and motor drives in advanced automotive systems. Sliding-mode and feedback linearization techniques along with large-signal phase plane analysis are presented as methods to analyze, control, and stabilize automotive converters/systems with CPLs
Citations
More filters
TL;DR: In this paper, a review of control strategies, stability analysis, and stabilization techniques for dc microgrids is presented, where overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level.
Abstract: This paper presents a review of control strategies, stability analysis, and stabilization techniques for dc microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control, which relies only on local measurements, some line of communication between units needs to be made available in order to achieve the coordinated control. Depending on the communication method, three basic coordinated control strategies can be distinguished, i.e., decentralized, centralized, and distributed control. Decentralized control can be regarded as an extension of the local control since it is also based exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches using these three coordinated control strategies to achieve various control objectives are reviewed in this paper. Moreover, properties of dc MG dynamics and stability are discussed. This paper illustrates that tightly regulated point-of-load converters tend to reduce the stability margins of the system since they introduce negative impedances, which can potentially oscillate with lightly damped power supply input filters. It is also demonstrated that how the stability of the whole system is defined by the relationship of the source and load impedances, referred to as the minor loop gain. Several prominent specifications for the minor loop gain are reviewed. Finally, a number of active stabilization techniques are presented.
1,131 citations
Cites background from "Constant power loads and negative i..."
...In practice, speed regulated motor drives and electronic loads may introduce such a destabilizing effect [32]....
[...]
...of load (POL) converters present a challenge from that point of view since they introduce a negative impedance characteristic within the bandwidth of their control loops [31], [32]....
[...]
TL;DR: In this article, stability issues in dc microgrids with instantaneous constant-power loads (CPLs) are explored and mitigation strategies such as load shedding, adding resistive loads, filters, or energy storage directly connected to the main bus, and control methods are investigated.
Abstract: This paper explores stability issues in dc microgrids with instantaneous constant-power loads (CPLs). DC microgrids typically have distributed power architectures in which point-of-load converters behave as instantaneous CPLs to line regulating converters located upstream. Constant-power loads introduce a destabilizing effect in dc microgrids that may cause their main bus voltages to show significant oscillations or to collapse. This paper also discusses stabilization strategies to prevent these undesired behaviors from occurring. Mitigating strategies such as load shedding, addition of resistive loads, filters, or energy storage directly connected to the main bus, and control methods are investigated. Advantages and disadvantages of these methods are discussed and recommendations are made. The analysis is verified with simulations and hardware-based experiments.
538 citations
Cites background from "Constant power loads and negative i..."
...Most studies on CPLs rely on small signal analysis [33]–[37]; they conclude that in dc systems with CPLs, the equilibrium point (EP) of...
[...]
...called negative impedance instability [29]–[33]....
[...]
TL;DR: The implementation of novel active-damping techniques on dc/dc converters has been shown and the proposed active- damping method is used to overcome the negative impedance instability problem caused by the CPLs.
Abstract: Multi-converter power electronic systems exist in land, sea, air, and space vehicles. In these systems, load converters exhibit constant power load (CPL) behavior for the feeder converters and tend to destabilize the system. In this paper, the implementation of novel active-damping techniques on dc/dc converters has been shown. Moreover, the proposed active-damping method is used to overcome the negative impedance instability problem caused by the CPLs. The effectiveness of the new proposed approach has been verified by PSpice simulations and experimental results.
422 citations
Cites background from "Constant power loads and negative i..."
...CPLs exhibit negative incremental resistance, which tends to destabilize the power system [4]–[7]....
[...]
TL;DR: In this article, an active rectifier and voltage regulator are modeled in nonlinear state-space form, linearized around an operating point, and joined to network and inverter models, and participation analysis of the combined system identified that the low-frequency modes are associated with the voltage controller of the active rectifiers and the droop controllers of the inverters.
Abstract: Rectifiers and voltage regulators acting as constant power loads form an important part of a microgrid’s total load. In simplified form, they present a negative incremental resistance and beyond that, they have control loop dynamics in a similar frequency range to the inverters that may supply a microgrid. Either of these features may lead to a degradation of small-signal damping. It is known that droop control constants need to be chosen with regard to damping, even with simple impedance loads. Actively controlled rectifiers have been modeled in nonlinear state-space form, linearized around an operating point, and joined to network and inverter models. Participation analysis of the eigenvalues of the combined system identified that the low-frequency modes are associated with the voltage controller of the active rectifier and the droop controllers of the inverters. The analysis also reveals that when the active load dc voltage controller is designed with large gains, the voltage controller of the inverter becomes unstable. This dependence has been verified by observing the response of an experimental microgrid to step changes in power demand. Achieving a well-damped response with a conservative stability margin does not compromise normal active rectifier design, but notice should be taken of the inverter–rectifier interaction identified.
369 citations
Cites background from "Constant power loads and negative i..."
...[24] The negative incremental impedance causes the current to increase when the voltage decreases, and the current to decrease when the voltage increases....
[...]
...Many solutions have been proposed to overcome the problems of CPLs, including the solution discussed in [24] and [25]....
[...]
TL;DR: In this paper, the authors reviewed all the major stability criteria for dc distribution systems that have been developed so far: the Middlebrook Criterion, the Gain Margin and Phase Margin (GMP), the Opposing Argument Criterion (OAC), the Energy Source Analysis Consortium (ESAC), and the Three-Step Impedance Criterion.
Abstract: Power-electronics-based dc power distribution systems, consisting of several interconnected feedback-controlled switching converters, suffer from potential degradation of stability and dynamic performance caused by negative incremental impedances due to the presence of constant power loads. For this reason, the stability analysis of these systems is a significant design consideration. This paper reviews all the major stability criteria for dc distribution systems that have been developed so far: the Middlebrook Criterion, the Gain Margin and Phase Margin Criterion, the Opposing Argument Criterion, the Energy Source Analysis Consortium (ESAC) Criterion, and the Three-Step Impedance Criterion. In particular, the paper discusses, for each criterion, the artificial conservativeness characteristics in the design of dc distribution systems, and the formulation of design specifications that ensure system stability. Moreover, the Passivity-Based Stability Criterion is discussed, which has been recently proposed as an alternative stability criterion. While all prior stability criteria are based on forbidden regions for the polar plot of the so-called minor loop gain, which is an impedance ratio, the proposed criterion is based on imposing passivity of the overall bus impedance. A meaningful simulation example is presented to illustrate the main characteristics of the reviewed stability criteria.
347 citations
References
More filters
TL;DR: In this article, a canonical circuit model is proposed, whose fixed topology contains all the essential input-output and control properties of any d.c.-to-d.c. switching converter, regardless of its detailed configuration, and by which different converters can be characterized in the form of a table conveniently stored in a computer data bank.
Abstract: A method for modelling switching-converter power stages is developed, whose starting-point is the unified state-space representation of the switched notworks and whose end result is either a complete state-space description or its equivalent small-signal low-frequency linear circuit model. A new canonical circuit model is proposed, whose fixed topology contains all the essential input-output and control properties of any d.c.-to-d.c. switching converter, regardless of its detailed configuration, and by which different converters can be characterized in the form of a table conveniently stored in a computer data bank to provide a useful tool for computer-aided design and optimization. The new canonical circuit model predicts that, in general, switching action introduces both zeros and poles into the duty ratio to output transfer function in addition to those from the effective filter network.
1,827 citations
"Constant power loads and negative i..." refers background in this paper
...5, is a dc/ac inverter, which drives an electric motor and tightly regulates the speed when the rotating load has a one-to-one torque–speed characteristic....
[...]
...Some of these components behave as CPLs....
[...]
Book•
21 Sep 2009TL;DR: This document discusses the design and control principles of the Hybrid Electric Drive Trains, and the designs of the Drive Train Engine/Generator Power Design and Energy Design of Energy Storage Appendices Index.
Abstract: Environmental Impact and History of Modern Transportation Air Pollution Global Warming Petroleum Resources Induced Costs Importance of Different Transportation Development Strategies to Future Oil Supply History of EVs History of HEVs History of Fuel Cell Vehicles Fundamentals of Vehicle Propulsion and Brake General Description of Vehicle Movement Vehicle Resistance Dynamic Equation Tire-Ground Adhesion and Maximum Tractive Effort Power Train Tractive Effort and Vehicle Speed Vehicle Power Plant and Transmission Characteristics Vehicle Performance Operating Fuel Economy Brake Performance Internal Combustion Engines 4S, Spark-Ignited IC Engines 4S, Compression-Ignition IC Engines 2S Engines Wankel Rotary Engines Stirling Engines Gas Turbine Engines Quasi-Isothermal Brayton Cycle Engines Electric Vehicles Configurations of EVs Performance of EVs Tractive Effort in Normal Driving Energy Consumption Hybrid Electric Vehicles Concept of Hybrid Electric Drive Trains Architectures of Hybrid Electric Drive Trains Electric Propulsion Systems DC Motor Drives Induction Motor Drives Permanent Magnetic BLDC Motor Drives SRM Drives Design Principle of Series (Electrical Coupling) Hybrid Electric Drive Train Operation Patterns Control Strategies Design Principles of a Series (Electrical Coupling) Hybrid Drive Train Design Example Parallel (Mechanically Coupled) Hybrid Electric Drive Train Design Drive Train Configuration and Design Objectives Control Strategies Parametric Design of a Drive Train Simulations Design and Control Methodology of Series-Parallel (Torque and Speed Coupling) Hybrid Drive Train Drive Train Configuration Drive Train Control Methodology Drive Train Parameters Design Simulation of an Example Vehicle Design and Control Principles of Plug-In Hybrid Electric Vehicles Statistics of Daily Driving Distance Energy Management Strategy Energy Storage Design Mild Hybrid Electric Drive Train Design Energy Consumed in Braking and Transmission Parallel Mild Hybrid Electric Drive Train Series-Parallel Mild Hybrid Electric Drive Train Peaking Power Sources and Energy Storages Electrochemical Batteries Ultracapacitors Ultra-High-Speed Flywheels Hybridization of Energy Storages Fundamentals of Regenerative Breaking Braking Energy Consumed in Urban Driving Braking Energy versus Vehicle Speed Braking Energy versus Braking Power Braking Power versus Vehicle Speed Braking Energy versus Vehicle Deceleration Rate Braking Energy on Front and Rear Axles Brake System of EV, HEV, and FCV Fuel Cells Operating Principles of Fuel Cells Electrode Potential and Current-Voltage Curve Fuel and Oxidant Consumption Fuel Cell System Characteristics Fuel Cell Technologies Fuel Supply Non-Hydrogen Fuel Cells Fuel Cell Hybrid Electric Drive Train Design Configuration Control Strategy Parametric Design Design Example Design of Series Hybrid Drive Train for Off-Road Vehicles Motion Resistance Tracked Series Hybrid Vehicle Drive Train Architecture Parametric Design of the Drive Train Engine/Generator Power Design Power and Energy Design of Energy Storage Appendices Index
1,221 citations
01 Jun 1990
TL;DR: In this paper, a more general averaging procedure that encompasses state-space averaging and that is potentially applicable to a much broader class of circuits and systems is presented, including resonant type converters.
Abstract: A more general averaging procedure that encompasses state-space averaging and that is potentially applicable to a much broader class of circuits and systems is presented. Examples of its application in resonant and PWM power convertors are presented. The technique is shown to be effective on a number of examples. including resonant type converters. The approach offers refinements to the theory of state-space averaging, permitting a framework for analysis and design when small ripple conditions do not hold. The method may find applications in simulation and design since it is considerably easier to simulate an averaged model than a switched model. >
1,144 citations
26 Jun 1989
TL;DR: Averaging theory as discussed by the authors offers constructive tools for the analysis of oscillatory ordinary differential equations with time-discontinuous right-hand sides, if requirements of solution differentiability are relaxed.
Abstract: Averaging theory offers constructive tools for the analysis of oscillatory ordinary differential equations with time-discontinuous right-hand sides, if requirements of solution differentiability are relaxed. This theory forms a rigorous framework for evaluating, refining, and extending heuristic averaged models used in power electronics, and provides direct techniques for recovering oscillatory effects such as ripple from the averaged model. An overview of this theory is presented, and DC-DC converters are analyzed as examples. >
533 citations
12 Dec 2003
TL;DR: In this paper, the authors present a real-time state estimation of the stability of a DC vehicular distribution system with constant power and resistive loads. But, they do not discuss the effect of different types of power loads on the performance of the system.
Abstract: INTRODUCTION TO ELECTRICAL POWER SYSTEMS Fundamentals of Electric Circuits Control Systems Electrical Systems References FUNDAMENTALS OF POWER ELECTRONICS AC/DC Rectifiers DC/DC Converters DC/AC Inverters Selected Readings ELECTRIC MACHINES Electro-Mechanical Power Transfer Systems Fundamentals of Electromagnetism DC Machines Induction Machines Synchronous Machines Selected Readings AUTOMOTIVE POWER SYSTEMS Conventional 14V Electrical System Architecture Advanced Electrical Loads Increasing the System Voltage to 42V Advanced Distribution Systems Starter, Alternator, and Integrated Starter/Alternator Automobile Steering Systems Semiconductors for Automotive Applications Automotive Communication Networks and Wireless Techniques References ELECTRIC AND HYBRID ELECTRIC VEHICLES Principles of Hybrid Electric Drivetrains Architectures of Hybrid Electric Drivetrains Electrical Distribution System Architectures More Electric Hybrid Vehicles Hybrid Control Strategies Hybridization Effects 42V System for Traction Applications Heavy Duty Vehicles Electric Dragsters Modeling and Simulation of Automotive Power Systems References AIRCRAFT POWER SYSTEMS Conventional Electrical Systems Power Generation Systems Aircraft Electrical Distribution Systems Stability Analysis References SPACE POWER SYSTEMS Introduction International Space Station Spacecraft Power Systems Modeling and Analysis Real-Time State Estimation Stability Assessment References SEA AND UNDERSEA VEHICLES Power System Configurations in Sea and Undersea Vehicles Power Electronics Building Blocks (PEBBs) Controller Architecture for Power Electronic Circuits Power Management Center (PMC) Electrical Distribution System in Sea and Undersea Vehicles Advanced Electric Drives in Sea and Undersea Vehicles References FUEL CELL BASED VEHICLES Structures, Operations, and Properties of Fuel Cells Important Properties of Fuel Cells for Vehicles Light-Duty Vehicles Heavy-Duty Vehicles Current Status and Future Trends in Fuel Cell Vehicles Aerospace Applications Other Applications of Fuel Cells Conclusion References ELECTRICAL MODELING TECHNIQUES FOR ENERGY STORAGE DEVICES Battery Modeling Modeling of Fuel Cells Modeling of Photovoltaic (PV) Cells Modeling of Ultracapacitors Conclusion References ADVANCED MOTOR DRIVES FOR VEHICULAR APPLICATIONS Brushless DC Motor Drives Switched Reluctance Motor Drives References MULTI-CONVERTER VEHICULAR DYNAMICS AND CONTROL Multi-Converter Vehicular Power Electronic Systems Constant Power Loads and Their Characteristics Concept of Negative Impedance Instability Negative Impedance Instability in the Single PWM DC/DC Converters Stability of PWM DC/DC Converters Driving Several Loads Stability Condition in a DC Vehicular Distribution System Negative Impedance Stabilizing Control for PWM DC/DC Converters with Constant Power and Resistive Loads Conclusion References EFFECTS OF CONSTANT POWER LOADS IN AC VEHICULAR SYSTEMS Vehicular AC Distribution Systems Modeling of AC Constant Power Loads Negative Impedance Instability Conditions Hybrid (DC and AC) Vehicular Systems with Constant Power Loads Conclusion References INDEX
276 citations
"Constant power loads and negative i..." refers background in this paper
...Index Terms—Constant power loads (CPLs), control, electric vehicles (EVs), fuel cell vehicles (FCVs), hybrid electric vehicles (HEVs), modeling, modeling and analysis, motor drives, negative impedance instability, power converters, stability, state-space averaging....
[...]
...…toward replacement of more engine-driven mechanical and hydraulic loads with electrical loads, increasing the voltage of the system, which is 14 V in the conventional cars, to a higher voltage such as the proposed 42 V PowerNet is necessary to cope with the greater loads associated with MEVs [4]....
[...]
...Fuel cell support system loads such as water, fuel, and air circulating pumps, ventilation fan, and control system are supplied from the main dc bus [1], [2]....
[...]
...Some of these components behave as CPLs....
[...]
...In this section, descriptions of the system architectures and the role of power electronic converters and motor drives are presented....
[...]