Shaohua Lin

A Foster Network Thermal Model for HEV/EV Battery Modeling

Battery thermal management for high-power applications such as electrical/hybrid vehicles is crucial. Modeling is an indispensable tool to help engineers design better battery cooling systems. An accurate battery thermal model using a Foster network is proposed. The parameters in the Foster network, including capacitance and resistance, are extracted from computational fluid dynamics (CFD) results. The Foster network model is then shown to provide equivalent results as those from CFD under transient heat dissipation inputs. The model can be readily coupled with a battery electrical circuit model to form a complete battery system circuit model capable of predicting accurate battery temperature and the impact of temperature on battery electrical transient performance.

A linear parameter-varying model for HEV/EV battery thermal modeling

Battery thermal management for high power applications such as electrical/hybrid vehicles is crucial. Modeling is an indispensable tool to help engineers design better battery cooling systems. A fast and accurate battery thermal model capable of predicting volume-averaged cell temperature or temperature at user specified locations under transient heat dissipation and varying mass flow rate is proposed. In such an approach, several state space models are generated first from computational fluid dynamics (CFD) results for different mass flow rates. Then a linear parameter-varying (LPV) model is created out of the state space models to account for non-constant flow rates. The model is then shown to provide excellent results compared with those from CFD under transient heat dissipation and mass flow rate. Such a LPV model runs many orders of magnitude faster than the original CFD model.

A state space thermal model for HEV/EV battery using vector fitting

Battery thermal management for high power applications such as electrical/hybrid vehicles is crucial. Modeling is an indispensable tool to help engineers design better battery cooling systems. A fast and accurate battery thermal model using state space representation can be used to predict volume-averaged cell temperature or temperature at user specified locations under transient heat dissipation. The matrices of the state space model are calculated by curve-fitting the step response of the state space model to that of the battery thermal system computed from computational fluid dynamics (CFD) results. In this paper, the vector-fitting (VF) method in the frequency domain is proposed for the curve-fitting. The frequency domain VF method is shown to provide advantages over the time domain Levenberg-Marquardt (LM) method. For batteries using prismatic cells, the VF method is shown to be more accurate. For multiple-input multiple-output (MIMO) battery thermal systems, the VF method generates much smaller state space models compared with those using the LM method. Therefore, for MIMO battery thermal systems, models from the VF method run much faster than those from the LM method.

A novel thermal model for HEV/EV battery modeling based on CFD calculation

Battery thermal management for high power applications such as electrical/hybrid vehicles is crucial. Modeling is an indispensible tool to help engineers design better battery cooling systems. An accurate battery thermal model using Foster network is proposed. The parameters in the Foster network including capacitance and resistance are extracted from Computational Fluid Dynamics (CFD) results. The Foster network model is then shown to provide identical results as those from CFD under any transient power inputs. The model can be readily coupled with battery electrical circuit model to form a complete battery system circuit model capable of predicting accurate battery temperature and the impact of temperature on battery electrical transient performance.

A State Space Thermal Model for HEV/EV Non-Linear and Time-Varying Battery Thermal Systems

Battery thermal management for high power applications such as electrical vehicle (EV) or hybrid electrical vehicle (HEV) is crucial. Modeling is an indispensable tool to help engineers design better battery cooling systems. While computational fluid dynamics (CFD) has been used quite successfully for battery thermal management, CFD models can be too large and too slow for repeated transient thermal analysis, especially for a battery module or pack. A state space model based on CFD results can be used to replace the original CFD model. The state space model runs approximately two orders of magnitude faster and yet under some conditions obtains equivalent results as the original CFD model. The state space model is based on linear and time-invariant (LTI) system theory. The main limitation of the method is that the method applies strictly speaking to systems that satisfy both linearity and time invariance conditions. General battery cooling problems unfortunately do not strictly satisfy those two conditions. This paper examines quantitatively the amount of error involved if these two conditions are not met. It turns out that these conditions can be relaxed in some ways while preserving satisfactory results for non-linear and time-varying battery thermal systems. This paper also discusses non-linear curve fitting needed for the method.Copyright

Analysis and design of dynamic voltage regulation in multiphase buck converter

Dynamic voltage regulation (DVR) [1] is now widely used in microprocessors and system on chip (SOC) systems to reduce operational voltage under light load condition. With the aggressive motivation to reduce power consumption, the design specification of voltage transition (dv/dt) for the DVR is pushing the limit of the multiphase converter design and the component stress as well. In this paper, a novel control scheme is proposed for dealing with fast voltage positioning, i.e. upward and downward. The scenario of reverse current flowing is carefully studied based on the MOSFET parasitic model and experiment results. The stress on the HS MOSFET is also addressed. The effectiveness of the proposed scheme is verified by both simulation and experiment result.

Integrated Nonlinear Dynamic Modeling and Field Oriented Control of Permanent Magnet (PM) Motor for High Performance EMA

This paper describes the integrated modeling of a permanent magnet (PM) motor used in an electromechanical actuator (EMA). A nonlinear, lumped-element motor electric model is detailed. The parameters, including nonlinear inductance, rotor flux linkage, and thermal resistances, and capacitances, are tuned using FEM models of a real, commercial motor. The field-oriented control (FOC) scheme and the lumpedelement thermal model are also described.

Temperature dependent reduced order IPM motor model based on finite element analysis

The interior permanent magnet motor is the central component of modern high performance hybrid electric vehicles. During the vehicles normal operation, demagnetization can occur in the magnets due to temperature rise and high current loading, which could change the IPMs electrical and mechanical characteristic and the overall system performance significantly. To study these effects on the system level, in this paper, we propose a reduced order motor model based on FEA solution that takes into account the permanent magnets temperature dependency, current loading and nonlinear saturation effects. The proposed model runs at circuit simulation speed which is suitable for system level simulation and while having the accuracy of FEA. Using this model, we are able to quantify the current consumption during a standard drive cycle simulation due to temperature and current loading variations.

A computationally efficient transient thermal model for electric machines based on singular value decomposition

A transient reduced order model (ROM) for electric machines based on singular value decomposition (SVD) is proposed. The ROM generation process starts with computation fluid dynamics (CFD) results of an electric machine model, from which SVD is used to calculate the approximate subspace that the temperature solution belongs to. Then a ROM working in the subspace is created. The ROM is shown to provide very similar results as those from CFD under arbitrary transient loss profiles. The ROM runs orders of magnitude faster than the original CFD model.

Battery modeling based on the coupling of electrical circuit and computational fluid dynamics

A new battery model by coupling electrical circuit and computational fluid dynamics (CFD) is proposed. It provides the insight of electrical performance as well as the temperature distribution of a battery pack. The model is potentially suitable for hybrid electric vehicle (HEV)/ electric vehicle (EV) battery modeling because of the high power and high temperature nature of these applications.