Jung-Pyo Hong

This paper proposes a design method of the high-speed multi-layer interior permanent magnet synchronous motor (HSML IPMSM) employing the ferrite permanent magnet (PM). Since the maximum speed of the traction motor in this paper is 15 krpm, the mechanical stability must be considered. Additionally, in the case of the HSML IPMSM, as the number of the PM layers increases, the thickness of the PMs must be reduced to be mechanically stable. On the other hand, because the ferrite PM has a relatively low coercive force compared to the Nd PM, an irreversible demagnetization of the ferrite PM of the HSML IPMSM is likely to occur. Therefore, the mechanical stability and irreversible demagnetization must be considered at all design steps. As the irreversible demagnetization and mechanical stability can be confirmed only by finite element analysis (FEA), the proposed method in this paper is a design method that considers the irreversible demagnetization and mechanical characteristics at all design steps using the FEA. After the design of the traction motor is completed using this design method, the designed motor is manufactured. To verify the validity of the design method, experiments are conducted on the manufactured motor, and the test results are compared with FEA results.

Owing to the high speed and frequency required in electric machine industry, the significance of AC resistance has been increasing. This study investigates the AC resistance of windings according to configuration of strands. The mechanism of generating the AC resistance in winding conductors was investigated with respect to the slot leakage flux and eddy current. Then, when applying the strands to the winding, the concept of unbalanced impedance was introduced to characterize the additional AC resistance due to circulating current. The analytic method to calculate AC resistance describing the above phenomena is derived and verified by FEA results. Afterwards, the AC resistances of varying numbers and arrangements of strands were separately studied via finite element analysis. In addition, a method to avoid increasing the AC resistance was suggested based on impedance equalization when applying strands. Finally, experiments were conducted to verify the effect of the strand configuration on AC resistance. An E- and I- shaped core, which can be the rendering of common electric machines, such as motors, generators, and transformers, was manufactured and tested with winding specimens. Consequently, the test results showed a similar trend as the analytical results.

Hybrid electric vehicles have different performance depending on power distribution and energy management. For heavy-duty vehicles, in particular, these differences will be more pronounced. This paper presents a hybrid powertrain design framework for a heavy-duty multi-purpose vehicle assuming driving conditions. A diesel-powered conventional vehicle was adopted for the hybridization target, and a series hybrid system was suggested as a suitable hybridization topology with an in-wheel motor (IWM) system. The introduced framework supplied the adequate power distribution and the IWM specification based on the speculated drive cycle and a simple energy management strategy. In particular, the reduction ratio of IWM was determined to minimize the gross mass of the motor and reduction gear. The hybridization reduced the vehicle weight by 213 kg while increasing the peak power by 53 kW. Finally, the vehicle simulation was performed using the advanced vehicle simulator for the design result from the proposed framework. The acceleration performance and gradeability limits were improved by 18 % and 10 %p, respectively, compared to the conventional vehicle. In addition, the gasoline equivalent fuel economy of the series hybrid powertrain was 53 % higher than conventional diesel powertrain for the target drive cycle.

In this paper, a method is introduced to directly calculate the reluctances of fringing fields in analyzing a magnetic equivalent circuit model for an axisymmetric solenoid actuator including radial air gaps as well as axial air gaps. The introduced method was motivated by the possibility to calculate the cross section area depending on the radial position of an infinitesimal element when the infinitesimal element is defined to be integrated in the flux flow direction in a circular-arc straight-line model of an axisymmetric model. In this method, the reluctance of fringing field near an air gap can be calculated directly. For an objective model, the MEC analysis was performed using the introduced method and an iterative method. In the iterative method, the nonlinearity of the ferromagnetic material parts is resolved. In order to validate the introduced method, MEC analysis and FEA results are compared. And for validating the method in a view of computation also, an optimized design satisfying pre-defined constraints was searched using MEC analysis, and then the results of the MEC analysis using the introduced method and FEA results are compared for the searched design and the initial design.

In this paper, the design of the concentrated fluxtype synchronous motor (CFSM) using ferrite permanent magnets to improve torque is proposed for an automotive chassis actuator. The thin pancake type CFSM of this paper has considerable axial magnetic leakage flux due to structural reasons. It is therefore necessary to improve the torque. In order to meet the required specifications in a constrained installation space, this paper proposes two methods for torque improvement. The first method is the alternate-stacking core as this structure removes the magnetic leakage flux path. The second method is the rotor overhang which increases the air-gap flux density. Furthermore, the structures require a 3-D finite element method (FEM) analysis for accuracy. However, to analyze the characteristics easily and quickly, the 3-D structure is made into the equivalent 2-D FEM through an analytical method using an equivalent magnetic circuit (EMC). Finally, in this paper, the validity of the design process and the effectiveness for torque improvement is verified through experiments.

Electrical characteristics of a typical vehicle horn are determined by its resistance and inductance. The inductance is affected by factors such as the magnetic circuit, current magnitude, eddy currents and material properties. The mechanical characteristics of the vehicle horn are also affected by its material properties, the horn structure and its natural frequency. Mechanical and electrical parameters change during the operation of a vehicle horn. Therefore, it is difficult to predict the vehicle horn performance and hence, its design. In this study, firstly, the electrical and mechanical system of a vehicle horn are mathematically modeled. Secondly, the electrical and mechanical parameters are calculated using the finite element analysis method. Thirdly, to predict the operating characteristics of the vehicle horn, the electrical/mechanical system equations are solved by applying the parameters obtained from the finite element analysis. Finally, the simulation results and experimental results are compared and verified.

This paper proposes a novel structure for the concentrated flux-type synchronous motor (CFSM) in order to improve the torque density as well as the vibration characteristics. First, the conventional surface mounted permanent magnet synchronous motor (SPMSM) as prototype for the electric booster in the brake system is investigated through tests. Then, the relationship between the vibration characteristics and the number of poles and slots is analyzed. Based on the analysis results, a pole-slot combination for an improved CFSM is determined to enhance the vibration characteristics. Furthermore, a novel structure for the improved motor that employs three different core shapes in the rotor is proposed to increase the torque density. As a result, the improved motor with excellent vibration characteristics as well as a high torque density is designed. Finally, experiments are conducted to verify the effectiveness and the feasibility of the proposed method.

The harmonics of the induced voltage under load conditions cause the deterioration of the motor performance. It occurs when the peak value of the demand voltage exceeds the DC link voltage. In this paper, thus, to reduce the induced voltage harmonics under load conditions, an asymmetric rotor design method using the advanced inverse cosine function (AICF) is proposed. Using this method, the rotor shape is determined by considering the armature reaction under certain load condition. As a result, an improved concentrated flux synchronous motor (CFSM) achieving the required performance is designed. Lastly, the induced voltages waveforms of the proposed motors under the load conditions are compared through finite-element analysis (FEA) as well as experiments.