Low Load Conditions Research Articles

Tradeoff between the efficiency penalty and load depth in a coal-fired power plant with CO2 capture under partial load conditions

With the penetration of renewable energy increasing rapidly in the power system, flexible operation of coal-fired power plants with CO2 capture is expected to play a key role in grid peak-regulating in China. However, studies on the interactions between power generation and CO2 separation units under partial load are still limited. Accordingly, in this paper, the factors that affect the system performance were investigated based on a 1000-MW post-combustion power plant under partial load. The results indicate that minimizing the difference between the quality of the steam extracted from the turbine and the minimum steam quality required for the reboiler, meanwhile resulting in no extra work losses, is the essential target for system integration. Under the IP-LP-PMV (Pressure Maintaining Valve) scheme, the irreversible loss caused by PMV led to an extra system efficiency penalty of 3.31% points under 30% load. However, for the IP-interstage-PMV scheme, the system efficiency could be improved by 0.7% and 1% points under loads of 30% and 40%, respectively, because the work losses caused by splitting and throttling under low load conditions could be reduced by adjusting the extraction location. Therefore, the system performance could be improved by altering the extraction position under partial load operation. By investigating the optimal extraction location under variable loads, it is disclosed that the IP-interstage-PMV scheme and the IP-LP-PMV scheme are the most efficient steam extraction schemes under 40% or 70% loads respectively. Therefore, the theoretical optimal steam extraction position varied under the different loads, and the extraction position should be selected based on the average operating load from the perspective of all the working conditions. This integration principle provides the highest performance improvement potential of 2% points for partial load operation. This study will be helpful to promoting the further deployment of large-scale post-combustion capture projects.

Rheological and tribological properties of polyurea greases containing additives of MoDDP and PB

Molybdenum dialkyl dithiophosphate (MoDDP) and potassium borate (PB) were selected as additives for the greases. Results show that the polar MoDDP additive cause grease colloidal stability enhanced and apparent viscosity and structural strength increased, while potassium borate has less effect on the colloidal structure and structural strength of the grease. The solid additive PB has excellent anti-wear, extreme pressure and friction reduction properties at room temperature as well as at high temperatures under low loading conditions. Due to the synergistic effect, the PB/MoDDP additive combination can achieve excellent friction reduction and anti-wear performance. Under high temperatures, the content of metal phosphates and molybdenum disulfide decreases, the adsorption capacity of additives decreases, and friction and wear on metal surfaces increase.

Effects of Alcohol-Blended Waste Plastic Oil on Engine Performance Characteristics and Emissions of a Diesel Engine

The current study aims to investigate and compare the effects of waste plastic oil blended with n-butanol on the characteristics of diesel engines and exhaust gas emissions. Waste plastic oil produced by the pyrolysis process was blended with n-butanol at 5%, 10%, and 15% by volume. Experiments were conducted on a four-stroke, four-cylinder, water-cooled, direct injection diesel engine with a variation of five engine loads, while the engine’s speed was fixed at 2500 rpm. The experimental results showed that the main hydrocarbons present in WPO were within the range of diesel fuel (C13–C18, approximately 74.39%), while its specific gravity and flash point were out of the limit prescribed by the diesel fuel specification. The addition of n-butanol to WPO was found to reduce the engine’s thermal efficiency and increase HC and CO emissions, especially when the engine operated at low-load conditions. In order to find the suitable ratio of n-butanol blends when the engine operated at the tested engine load, the optimization process was carried out by considering the engine’s load and ratio of the n-butanol blend as input factors and the engine’s performance and emissions as output factors. It was found that the multi-objective function produced by the general regression neural network (GRNN) can be modeled as the multi-objective function with high predictive performances. The coefficient of determination (R2), mean absolute percentage error (MAPE), and root mean square error (RSME) of the optimization model proposed in the study were 0.999, 2.606%, and 0.663, respectively, when brake thermal efficiency was considered, while nitrogen oxide values were 0.998, 6.915%, and 0.600, respectively. As for the results of the optimization using NSGA-II, a single optimum value may not be attained as with the other methods, but the optimization’s boundary was obtained, which was established by making a trade-off between brake thermal efficiency and nitrogen oxide emissions. According to the Pareto frontier, the engine load and ratio of the n-butanol blend that caused the trade-off between maximum brake thermal efficiency and minimum nitrogen oxides are within the approximate range of 37 N.m to 104 N.m and 9% to 14%, respectively.

Effect of methane supplementation on the performance, vibration and emissions characteristics of methane-diesel dual fuel engine

The increasing energy demands, especially in transportation sector, and the challenges of excess pollution and environmental degradation caused due to the conventional fuels, as well as their limited availability has highlighted the need to look for alternative fuels to sustain future needs. Methane is capable of catering to these demands due to its wide availability, both in renewable and non-renewable energy sources. The present work explores the effect of methane supplementation on the performance and emission characteristics as well as the vibrations in internal combustion engines. A four-stroke compression ignition engine is modified to run as a methane-diesel dual fuel engine where methane is inducted through intake manifold and diesel is directly injected into cylinder. Tests are performed by varying engine load and methane energy levels up to 75%. Our study shows that the participation of methane at lower load conditions is weak due to its higher auto ignition temperature and higher calorific value. The emissions, particularly CO and NO, are observably higher at 75% load conditions due to the efficient combustion and higher temperature at higher load conditions. The vibration studies on the dual fuel combustion indicates that the introduction of methane also suppresses the frequency spectrum of combustion noise and reduces the ringing intensity level of vibration for complete spectrum of engine loads, with the effect being prominent at higher loads. Overall, our results suggests that combustion of methane in dual fuel diesel engine shows distinct characteristics at contrasting load conditions.

Hybrid digital twin for conditional lubricant oil transport simulation and oil consumption prediction in internal combustion engines

Reducing lubricant oil consumption (LOC) has long been an interest to engine manufacturers in an effort to reduce overall emissions from internal combustion (IC) engines. However, directly correlating engine operating conditions with LOC rates is a challenging task given its complex and multi-physics nature. Building on previous experimental observations and modeling efforts, a baseline hybrid model, which combines traditional physics-based numerical simulation with modern machine learning techniques, was developed. As the first step, the model is to compute the oil exiting the top ring gap with given oil supply rate and locations to the second land. Studies performed using the model reveal a strong dependency of LOC on engine speed, load as well as the relative locations of piston ring gaps. In particular, the close proximity of the oil source on second land to the top ring gap and the reverse gas flow at low load conditions can both induce high LOC. Piston ring gap rotations and the different oil supply mechanisms to the piston ring pack are also found to heavily influence the oil consumption behavior and oil film thickness distribution pattern. The present work is the first step to a more comprehensive model for predicting LOC for healthy systems of piston ring packs. The efficiency of the model made it possible to study the oil redistribution that takes many engine cycles to reach equilibrium and rotation of the ring gaps that could happen in reality at a time scale of minutes and even longer.

Model-based Performance Study of Electrically Assisted Turbocharging Diesel Engine

Under the low load conditions, the motor drives the compressor to increase the intake of the engine, and under the high load conditions, the motor recovers the excess exhaust energy, which greatly improves the performance of the diesel engine in all aspects. In this paper, the one-dimensional simulation prediction model of TBD620V16 diesel engine is established and checked. On this basis, the external electric auxiliary turbocharging system of motor is established. The influence of motor power on the performance of diesel engine under different working conditions is studied by simulation, and the control strategy is put forward according to the influence of power and economy of diesel engine under low load. Based on this control strategy, the improvement effect of power performance and economy under low load conditions is studied. The results show that there is an optimal motor power in each load condition to make the comprehensive thermal efficiency of diesel engine reach the maximum value. Under low load condition, with the increase of diesel engine speed, the pressure ratio of electrically assisted turbocharged diesel engine is higher and the fuel consumption is lower. When the diesel engine is accelerated from 25% to 30% load condition, the supercharged pressure of electrically assisted turbocharged diesel engine is stabilized for about 3s, and the supercharged pressure is higher when it is stable, and BSFC is significantly lower than that of traditional turbocharged diesel engine.

Effect of high compression ratio on cycle-to-cycle variations of a natural gas engine under low load conditions

Through experimental and numerical simulations, it is found that the cycle-to-cycle variation (CCV) does not decrease as the compression ratio (CR) increases. The CCV of CR 11.6 is lower than that of CR 14.0 and CR 16.0.

Multimodal NDT monitoring of TRC sandwich under bending and early detection of interlaminar debonding

Textile Reinforced Cementitious (TRC) sandwich composites provide a load-bearing, noncorrosive, lightweight, and durable alternative for steel-reinforced sandwich elements, and/or traditional steel-reinforced concrete. However, the composite nature of the material and slender nature of the facings render the fracture behavior complex. Insufficient interlaminar bond can cause premature debonding, substantially reducing the loadbearing capacity of the composite. Non-Destructive Testing (NDT) techniques seem the obvious choice to monitor the damage progression of the material without affecting, nor compromising the behavior of the composite, and predict their service life. In this study, TRC sandwich composites, subjected to quasistatic four-point bending, are monitored with three NDTs. Digital Image Correlation (DIC) allows to measure the surface strains and displacements. MMW Spectrometry, used for the first time in bending damage monitoring, allowed to detect damage such as cracking, or debonding, while Acoustic Emission (AE) allowed to localize and characterize internal cracking. In order to simulate premature debonding, the bond between the tensile TRC facing and the insulation, in the central zone, where the bending moment is maximum, was artificially destroyed. Results show that a weak interlaminar bond reduced the ultimate load of the composite by more than 50%. Additionally, DIC, AE and MMW Spectrometry proved useful to monitor and characterize damage. Multimodal data gathered from the multimodal NDTs showed to be complementary. DIC allowed to interpret AE and MMW Spectrometry data from a surface viewpoint, while AE parameters permit predictions at low load conditions, and detect internal cracking. For instance, the AE behavior at early load stage (less than 15% of the maximum load) of the TRC sandwich with destroyed bond showed significant differences than for the reference TRC sandwich. Specifically, it showed higher RA values, and lower AF than the reference TRC sandwich, suggesting more shear related early activity for, promoted by the damaged bond. Results were corroborated with DIC, while MMW Spectrometry seemed to follow closely the level of damage of TRC sandwich composites under quasi-static four-point bending. EWGAE 35, Ljubljana, Slovenia, 13th – 16th Sep. www.ewg

Off-design performance analysis of a gas-supercritical carbon dioxide combined cycle under multi-stage mass flow cooperative operation

• A gas-supercritical carbon dioxide combined cycle was employed for load balance. • A reduction coefficient was proposed to build multi-stage mass flow cooperative operation. • Off-design performance models were proposed to present the performance of combined cycle. • Transcritical CO 2 cycle became more important under low-load operating conditions. • The combined cycle had good off-design performance under cooperative operation strategy. Renewable energy power plants have widely installed to supply electrical energy to power grids, which could lead to a grid load-balancing problem owning to the uncertainty of wind and solar power generations. To solve the issue of load balancing, a gas-supercritical carbon dioxide (CO 2 ) combined cycle, which has the advantages of compactness and flexibility, is employed and operated under off-design conditions with load-following operating strategies. A reduction coefficient is assumed to elucidate the multi-stage mass flow cooperative operation strategy of the combined cycle. Furthermore, off-design performance models and a solution procedure are proposed to present the off-design performance of the combined cycle under a cooperative operation strategy. The results from off-design simulations show that a large amount of recovered waste heat ensures that the transcritical CO 2 (t-CO 2 ) cycle becomes more important under low-load operating conditions. Additionally, the power ratio of the t-CO 2 cycle to the cascaded CO 2 cycle can be greater than 90% when the inlet guide vane is closed to the minimum opening, whereas the variation in the efficiency of the cascaded CO 2 cycle is relatively smooth. In general, the gas-supercritical carbon dioxide combined cycle has good off-design performance under multi-stage mass flow cooperative operation in terms of its wide load-following range and remarkably thermal efficiency improvement.

Effects of I-EGR and Pre-Injection on Performance of Gasoline Compression Ignition (GCI) at Low-Load Condition

Effects of I-EGR and Pre-Injection on Performance of Gasoline Compression Ignition (GCI) at Low-Load Condition

Evaluating the combustion performance of plastic oil in an Otto engine: A comparative analysis with premium fuel

This study examines the performance evaluation of plastic oil combustion compared to premium fuel in an Otto engine, focusing on the application of pyrolysis technology for converting plastic waste into oil. The analysis considers parameters such as the lower heating value (LHV) of the fuels, combustion characteristics observed through spark plug electrode examination, RPM requirements for power output, torque generation, and specific fuel consumption (SFC). The results show that plastic oil derived from PP has a slightly lower LHV compared to premium fuel. Visual inspection reveals cleaner combustion with plastic oil, indicating potential advantages in terms of reduced carbon build up. The engine requires a higher RPM to achieve the same power output with plastic oil compared to premium fuel. However, plastic oil generates higher torque at the same power output, suggesting better combustion efficiency. The SFC is highest for premium fuel under low-load conditions. The findings underscore the potential of plastic oil as a sustainable and environmentally friendly alternative fuel, derived from the conversion of plastic waste using pyrolysis technology. Further research and optimization are needed to enhance the fuel quality and overall performance of plastic oil.

Listen up! ADHD slows spoken-word processing in adverse listening conditions: Evidence from eye movements

BackgroundCognitive skills such as sustained attention, inhibition and working memory are essential for speech processing, yet are often impaired in people with ADHD. Offline measures have indicated difficulties in speech recognition on multi-talker babble (MTB) background for young adults with ADHD (yaADHD). However, to-date no study has directly tested online speech processing in adverse conditions for yaADHD. AimsGauging the effects of ADHD on segregating the spoken target-word from its sound-sharing competitor, in MTB and working-memory (WM) load. Methods and proceduresTwenty-four yaADHD and 22 matched controls that differ in sustained attention (SA) but not in WM were asked to follow spoken instructions presented on MTB to touch a named object, while retaining one (low-load) or four (high-load) digit/s for later recall. Their eye fixations were tracked. Outcomes and resultsIn the high-load condition, speech processing was less accurate and slowed by 140ms for yaADHD. In the low-load condition, the processing advantage shifted from early perceptual to later cognitive stages. Fixation transitions (hesitations) were inflated for yaADHD. Conclusions and implicationsADHD slows speech processing in adverse listening conditions and increases hesitation, as speech unfolds in time. These effects, detected only by online eyetracking, relate to attentional difficulties. We suggest online speech processing as a novel purview on ADHD. What this paper adds?We suggest speech processing in adverse listening conditions as a novel vantage point on ADHD. Successful speech recognition in noise is essential for performance across daily settings: academic, employment and social interactions. It involves several executive functions, such as inhibition and sustained attention. Impaired performance in these functions is characteristic of ADHD. However, to date there is only scant research on speech processing in ADHD. The current study is the first to investigate online speech processing as the word unfolds in time using eyetracking for young adults with ADHD (yaADHD). This method uncovered slower speech processing in multi-talker babble noise for yaADHD compared to matched controls. The performance of yaADHD indicated increased hesitation between the spoken word and sound-sharing alternatives (e.g., CANdle-CANdy). These delays and hesitations, on the single word level, could accumulate in continuous speech to significantly impair communication in ADHD, with severe implications on their quality of life and academic success. Interestingly, whereas yaADHD and controls were matched on WM standardized tests, WM load appears to affect speech processing for yaADHD more than for controls. This suggests that ADHD may lead to inefficient deployment of WM resources that may not be detected when WM is tested alone. Note that these intricate differences could not be detected using traditional offline accuracy measures, further supporting the use of eyetracking in speech tasks. Finally, communication is vital for active living and wellbeing. We suggest paying attention to speech processing in ADHD in treatment and when considering accessibility and inclusion.

The Impact of Fuel Injection Timing and Charge Dilution Rate on Low Temperature Combustion in a Compression Ignition Engine

Using high charge dilution low temperature combustion (LTC) strategies in a diesel engine offers low emissions of nitrogen oxides (NOx). These strategies are limited to part-load conditions and involve high levels of charge dilution, typically achieved through the use of recirculated exhaust gases (EGR). The slow response of the gas handling system, compared to load demand and fuelling, can lead to conditions where dilution levels are higher or lower than expected, impacting emissions and combustion stability. This article reports on the sensitivity of high-dilution LTC to variations in EGR rate and fuel injection timing. Impacts on engine efficiency, combustion stability and emissions are assessed in a single-cylinder engine and compared to in-cylinder flame temperatures measured using a borescope-based two-colour pyrometer. The work focuses on low-load conditions (300 kPa gross indicated mean effective pressure) and includes an EGR sweep from conventional diesel mode to high-dilution LTC, and sensitivity studies investigating the effects of variations in charge dilution and fuel injection timing at the high-dilution LTC condition. Key findings from the study include that the peak flame temperature decreased from ~2580 K in conventional diesel combustion with no EGR to 1800 K in LTC with low-NOx, low-soot operation and an EGR rate of 57%. Increasing the EGR to 64% reduced flame temperatures to 1400 K but increased total hydrocarbon (THC) and carbon monoxide (CO) emissions by 30–50% and increased fuel consumption by 5–7%. Charge dilution was found to have a stronger effect on the combustion process than the diesel injection timing under these LTC conditions. Advancing fuel injection timings at increasing dilution kept combustion instability below 2.5%. Peak in-cylinder temperatures were maintained in the 2000–2100 K range, while THC and CO emissions were controlled by delaying the onset of bulk quenching. Very early injection (earlier than 24 °CA before top-dead-centre) resulted in spray impingement on the piston crown, resulting in degraded efficiency and higher emissions. The results of this study demonstrate the potential of fuel injection timing modification to accommodate variations in charge dilution rates while maintaining low NOx and PM emissions in a diesel engine using low-temperature combustion strategies at part loads.

Analysis of combustion chamber deposit growth on temperature swing thermal barrier coatings in a spark ignition engine

Temperature swing thermal barrier coatings (TBCs) have the potential to improve efficiency and performance through thermal management of the combustion chamber. However, the effects of combustion chamber deposits (CCDs) on the surface of the TBCs are unclear. Therefore, this paper analyzes the impact of CCD formation on a temperature swing TBC. A piston and a heat flux probe coated with a novel material are installed in a single-cylinder research engine at a low-load condition for 62.5 h to promote CCD growth. Every 12.5 h, the performance at a knock limited condition is assessed and thermophysical property measurements on the heat flux probe are performed. Net thermal efficiency increased by 0.4% absolute after 12.5 h relative to the baseline condition, but further CCD growth caused a dithering of efficiency between the 12.5 h and baseline points. The KLSA retarded consistently throughout this period. External property measurements with the coated heat flux probe showed an improvement in the thermophysical properties of the TBC/CCD layer.

Investigation of PCCI combustion and emissions of biodiesel fuel at low load conditions using design of experiment (DOE)

Investigation of PCCI combustion and emissions of biodiesel fuel at low load conditions using design of experiment (DOE)

An Experimental and Computational Study on Triple Injection Strategies to Reduce Cold Start Diesel Engine Emissions

Abstract The effect of triple injection strategies in a diesel engine to reduce cold start emissions were experimentally and computationally investigated in this work. The experiments were performed using a 1.9 L four-cylinder, turbocharged compression ignition engine with diesel fuel. As a representative of the cold start condition in the diesel engine, a low load condition of 1500 rpm and 2 bar brake mean effective pressure (BMEP) was chosen as the fixed condition for this study. The injection strategy made use of a late post injection to reduce catalyst light-off time. The pilot and main injections are fixed and the post injection timing is swept later into the expansion stroke to increase exhaust enthalpy available to heat the aftertreatment system. To further understand the source of hydrocarbon (HC) emissions from late injections, equivalent experiments were conducted with a mixture of n-heptane and iso-octane that matched the reactivity of the diesel fuel. The mixture of primary reference fuels (i.e., PRF 34) obtained by matching the cetane number (CN) of diesel fuel, showed similar combustion characteristics of diesel, but is much more volatile due to lighter components in the PRF mixture. The increased volatility of PRF 34 suppressed liquid fuel impingement on the cylinder liner, which isolated liner impingement as a possible source of HC emissions. Simulations were also performed for the present engine configuration and operating conditions in a sector mesh using CONVERGE™. The physical properties of diesel fuel were modeled using a five-component surrogate. The chemical kinetics of the diesel fuel were modeled with a reduced n-heptane model. The simulations were able to capture the experimental trends of combustion characteristics and emissions. The HC emissions were observed to increase for both fuels with retarded post injection timings in engine experiments. PRF 34 had comparable HC emissions to diesel experiments, which indicated that the liner impingement is not the main source of the increase in HC emissions. Overmixing of the fuel and air was identified as the major cause of increase in HC emissions. Additionally, exhaust gas recirculation (EGR) also intensified the overmixing phenomenon and thereby increase in HC emissions.

Comparison of dimples and grooves based on friction and leakage properties of textured mechanical seals

PurposeThis study aims to obtain a design scheme of the surface texture on mechanical seal with lower friction and leakage by comparing two common texture types: dimples and grooves.Design/methodology/approachAn optimal free-form shape and an optimal circular shape were chosen by multi-objective optimization, and two types of grooves with different directions were chosen by a series of experiments. Then, the optimal free-form dimple, the optimal circular dimple, the groove perpendicular to the direction of movement (hereafter called groove-1) and the groove angled at 60° to the direction of movement (hereafter called groove-2) were compared by experiments under different loads.FindingsThe optimal free-form dimple shows a better performance in terms of a lower coefficient of friction (COF) and a lower leakage than the other shapes, especially for the high speed and low load conditions. The reduction rate of COF is up to 37.5%, and the leakage rate is reduced by about 12.5%. The dimples have a lower leakage than the grooves. The groove angled at 60° to the direction of movement is easier to pump the oil into the interface of the sealing face, leading to a lower friction but a higher leakage.Originality/valueThis study provides a feasible surface texture design scheme for improving the combination performance of mechanical seals.

Performance Evaluation of SiC-Based Two-Level VSIs with Generalized Carrier-Based PWM Strategies in Motor Drive Applications

Currently, silicon carbide (SiC) MOSFETs are several times higher in cost than the equivalent silicon (Si)-IGBTs; however, the gains in power conversion efficiency, simplification of thermal management, and energy savings in general bring the advantages of lower total cost of ownership. The implementation of discontinuous PWM (DPWM) techniques for controlling the motor drive brings further reductions for the semiconductor switching losses; however, most existing techniques have limited performance on the optimized clamping region, particularly at a low power factor, which is a common operation condition for motor drives employing the widely used V/f control, particularly at partial- or low-load conditions. This paper evaluates the performance of a SiC-based two-level voltage-source inverter (2L-VSI) motor drive operated with generalized carrier-based PWM methods. Theoretical analysis and experimental measurements are conducted in a 2.2 kW heatsink-less 2L-VSI prototype and induction machine, which demonstrates that the minimum switching losses DPWM (MSL-DPWM) is the most favorable solution in practice in terms of the achievable power conversion efficiency and harmonic distortions and also produces the least common-mode current, which is critical in motor drives.

How to support learning with multimedia instruction: Implementation intentions help even when load is high.

There is ample evidence that multimedia learning is challenging, and learners often underutilize appropriate cognitive processes. Previous research has applied prompts to promote the use of helpful cognitive processing. However, prompts still require learners to regulate their learning, which may interfere with learning, especially in situations where cognitive demands are already high. As an alternative, implementation intentions (i.e. if-then plans) are expected to help regulate behaviour automatically due to their specific wording, thereby offloading demands. Accordingly, this study aimed at investigating whether implementation intentions compared with prompts improve learning performance, especially under high cognitive load. Students (N=120) learned either in a control condition without instructional support, with prompts, or with implementation intentions. Within each condition, half of the participants studied the multimedia instruction under conditions of either high or low cognitive load, which was experimentally manipulated by instructing them to perform one of two secondary tasks. In line with our hypotheses, the results showed that under low cognitive load, both prompts and implementation intentions led to better learning than the control condition. By contrast, under high cognitive load, only implementation intentions promoted learning. Thus, implementation intentions are an efficient means to promote learning even under challenging circumstances.

Wound Rotor Synchronous Motor as Promising Solution for Traction Applications

Traction applications, such as electric and hybrid vehicles, require the electrical motor to be operated at low load conditions during most of their driving cycle. Permanent magnet (PM) motors in this case may not be an optimal choice due to their poor efficiency under low load conditions despite the fact that they exhibit the best output characteristics at the rated load. However, the wound rotor synchronous motor (WRSM) demonstrates the best efficiency at low load conditions due to their controllable excitation. This paper presents an interesting comparison of WRSM and the PM motor in terms of their efficiency over the entire drive cycle of traction applications, which demonstrates that WRSMs are more suitable compared to the apparently best performance PM motor. A WRSM with similar dimensions to the 2010 Toyota Prius interior permanent synchronous motor (IPMSM) was designed and optimized in this regard. The performance comparison of the PM motor and the WRSM was presented using 2-D finite element analysis (FEA) for the WRSM and the performance analysis report of the Toyota Prius IPMSM published by the US department of energies. The FEA analysis shows that the WRSM can achieve wide torque speed characteristics. Moreover, the WRSM exhibits better efficiency under low load conditions at the higher speed or field weakening region.