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Thermal Modeling of DC/AC Inverter for Electrified Powertrain Systems

FCA US LLC-Meng Li, Bruce Geist
Gotion, Inc.-Fan He
  • Technical Paper
  • 2020-01-1384
To be published on 2020-04-14 by SAE International in United States
A DC-to-AC main Power Inverter Module (PIM) is one of the key components in electrified powertrain systems. Accurate thermal modeling and temperature prediction of a PIM is critical to the design, analysis, and control of a cooling system within an electrified vehicle. PIM heat generation is a function of the electric loading applied to the chips and the limited heat dissipation within what is typically compact packaging of the Insulated Gate Bipolar Transistor (IGBT) module inside the PIM. This work presents a thermal modeling approach for a 3-phase DC/AC PIM that is part of an automotive electrified powertrain system. Heat generation of the IGBT/diode pairs under electric load is modeled by a set of formulae capturing both the static and dynamic losses of the chips in the IGBT module. A thermal model of the IGBT module with a simplified liquid cooling system generates temperature estimates for the PIM. Temperatures of chips, baseplates, and sinks are predicted from electric input loads. A case study is provided in wh ich the PIM thermal model is coupled with…
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Equivalence Factor Calculation for Hybrid Vehicles

FCA US LLC-Dionysios Panagiotopoulos, Bruce Geist, Douglas Schoeller
  • Technical Paper
  • 2020-01-1196
To be published on 2020-04-14 by SAE International in United States
Within a hybrid electric vehicle, given a power request initiated by pedal actuation, a portion of overall power may be generated by fuel within an internal combustion engine, and a portion of power may be taken from or stored within a battery via an e-machine. Generally speaking, power taken from a vehicle battery must eventually be recharged at a later time. Recharge energy typically comes ultimately from engine generated power (and hence from fuel), or from recovered braking energy. A hybrid electric vehicle control system attempts to identify when to use each type of power, i.e., battery or engine power, in order to minimize overall fuel consumption. In order to most efficiently utilize battery and fuel generated power, many HEV control strategies utilize a concept wherein battery power is converted to a scaled fueling rate. When battery power is used to propel the vehicle and hence is positive, the scale factor for battery power is chosen to produce a fueling rate estimate that, as nearly as possible, predicts the fuel rate required to recharge battery…
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Assessing the Likelihood of Binding in Distorted Stepped Radius Cylinder Bores

Altair ProductDesign, Inc.-Kiranmaye Aluru
Chrysler Group LLC-Bruce Geist, William Resh
Published 2014-04-01 by SAE International in United States
Interference assessments of a stepped-radius power-train component moving within a deformed stepped bore often arise during engine and transmission development activities. For example, when loads are applied to an engine block, the block distorts. This distortion may cause a cam or crankshaft to bind or wear prematurely in its journals as the part rotates within them. Within an automatic transmission valve body, care must be taken to ensure valve body distortion under oil pressure, assembly, and thermal load does not cause spool valves to stick as they translate within the valve body. In both examples, the mechanical scenario to be assessed involves a uniform or stepped radius cylindrical part maintaining a designated clearance through a correspondingly shaped but distorted bore. These distortions can occur in cross-sections (“out-of-round”) or along the bore (in an “s” or “banana” shaped distortions).To assess clearance in a deformed (stepped or uniform) bore, a new optimization based technique is proposed. This paper defines an optimization process that determines an axis assessed as producing the largest clearance between the stepped surface and…
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Calibrating an Adaptive Pivoting Vane Pump to Deliver a Stepped Pressure Profile

Chrysler Group LLC-Bruce Geist, William Resh, Kiranmaye Aluru
Published 2013-04-08 by SAE International in United States
This paper presents a process for the selection of spring rate and pre-load for an adaptively controlled pivoting vane oil pump. The pivoting vane pump has two modes: high and low speed. A spring within the pump is installed to induce a torque that causes an adaptive displacement mechanism within the pump to move toward maximum oil chamber size. In low speed mode, two feedback regions are pressurized that produce torques that counter the spring generated torque. Together, both regions being pressurized by main oil gallery pressure tend to reduce pump displacement more at lower speeds than if only a single chamber is pressurized. At higher speeds, a solenoid switch turns off pressure to one of the feedback pressure chambers, thereby reducing feedback torque that counters spring torque. This enables higher pressure calibrations in this speed mode. In this paper, we identify a process for choosing the spring rate and pre-load that calibrates the adaptive displacement mechanism. For a fixed pump geometry, the objective is to choose a spring rate and installed pre-load that causes…
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A Multiple Order Conformability Model for Uniform Cross-Section Piston Rings

DaimlerChrysler Corporation-Bruce Geist
Department of Mathematics, Michigan State University-Temo Bardzimashvili, James F. Kelly, Helen Romelashvili, William T. Sledd
Published 2005-04-11 by SAE International in United States
This paper examines the conformability of elastic piston rings to a distorted cylinder bore. Several bounds are available in the literature to help estimate the maximum allowable Fourier coefficient in a Fourier expansion of bore distortion: the analytically derived bounds in [7] and [8], and the semi-empirically derived bounds discussed in [9]. The underlying assumptions for each set of analytic bounds are examined and a multiple order algorithm is derived. The proposed algorithm takes account of multiple orders of distortion at once. It is tested with finite element (FE) data and compared to the classical bound approach. The results indicate that the bounds in [7] are compatible with linear elasticity theory (LET), whereas the bounds in [8] are not. Furthermore, numerical evidence indicates that the present multiple order algorithm can predict seal breaches more accurately than either of the other analytic bounds.
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