Bon-Gwan Gu

Development and Analysis of Interturn Short Fault Model of PMSMs With Series and Parallel Winding Connections

In this study, interturn short fault models of permanent magnet synchronous motors (PMSMs) employing series and parallel winding connections are developed using deformed flux models based on both fault winding flux information and inductance variations caused by cross flux linkages that depend on the distribution of same phase windings. As these models take into account fault winding within a three-phase winding dynamics analysis, they constitute fourth-order assessments. In the parallel-winding model, an additional dynamical analysis is used to describe variations in current distribution caused by the parallel connection between fault and healthy windings. Based on deformed flux modeling and positive sequence current assumptions, the proposed model is derived in both positive and negative sequence synchronous reference frames. A finite-element method-based simulation is applied to validate the proposed PMSM model.

Start-Up Current Control Method for Three-Phase PWM Rectifiers with a Low Initial DC-Link Voltage

When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.

Robust DC-link voltage control scheme for photovoltaic power generation system PCS

A power conversion system (PCS) for photovoltaic power generation system is composed of the DC/DC converter and the DC/AC inverter. To maximize power generation, DC/DC converter operated with MPPT (Maximum Power Point Tracking) algorithm and the PCS has been developed by the method of transformer tab change. DC/AC inverter controls DC-link voltage and grid current. But, single phase grid has 120Hz (Grid voltage frequency is 60Hz.) power ripple which arise DC-link voltage ripple. This paper presents a robust DC-link voltage control scheme. The control scheme utilizes a widow averaged DC-link voltage as a feedback signal. Experiment performed with 3kW PCS and the results support the validity of the control scheme.

Study of IPMSM Interturn Faults Part I: Development and Analysis of Models With Series and Parallel Winding Connections

In this study, the interturn fault (ITF) models of interior permanent magnet synchronous motors (IPMSMs) employing series and parallel winding connections were developed through the addition of saliency modeling to the surface-mounted permanent magnet motor models presented in a previous work. The saliency model was obtained by using deformed flux models based on both the fault winding flux information and inductance variations caused by cross-flux linkages that depend on the distribution of same-phase windings. By assuming a balanced three-phase current injection, positive and negative sequence voltages, and the fault current are obtained in the positive and negative synchronous reference frames. The output torque models were developed by adding the magnet and reluctance torques, which were derived from the developed models. To verify the proposed IPMSM models with an ITF, a finite element method-based simulation and experimental measurements were performed; the results are presented in this paper.

Modeling and Analysis of PMSMs under Inter Turn Short Faults

A model of a permanent magnet synchronous motor (PMSM) with an inter turn short fault is proposed using a deformed flux model. The deformed flux model includes not only the fault winding flux information but also the inductance variation of the healthy winding considering the configuration of the winding distribution. With the deformed flux model and the positive sequence current assumption, the proposed model is derived in the positive and negative sequence synchronous reference frame (SRF). The finite elements method (FEM) simulation is applied to validate the proposed PMSM model with inter turn short fault.

A dynamic modeling and a fault detection scheme of a PMSM under an inter turn short

A PMSM stator inter turn short fault generates a back emf and an impedance unbalance. Those unbalance causes a torque ripple and an escalating partial heat defect. This paper proposes a fault detection scheme based on the PMSM dynamic model under the inter turn short which is derived in the positive and the negative sequence synchronous reference frames. To validate the proposed scheme, the finite elements method (FEM) with electric circuit is conducted on the PMSM.

Inductance Estimation of Electrically Excited Synchronous Motor via Polynomial Approximations by Least Square Method

Electrically excited synchronous motors are designed to have high power density for electric vehicle applications. During a high-torque operation, severe nonlinearities associated with a saturation are observed: change of inductances, emergence of cross-coupling effects, variation of back EMF coefficient, etc. A flux linkage map over the current plane is obtained via finite-element analysis (FEA), and it is fitted by a third-order polynomial with the use of the least square method. Then, by grouping terms of the polynomial, the inductances are expressed as functions of currents. The validity of inductance fitting is shown by comparing with FEA and experimental results. This enables us to predict inductances online instead of using premade lookup table. The torque equation is expanded by incorporating the cross-coupling inductances, for which an extended maximum torque per ampere (MTPA) is developed by using Ferraris method to a quartic equation. The extended MTPA locus is compared with the experimental optimal results.

Analysis and Design of Slotted Tubular Linear Actuator for the Eco-Pedal System of a Vehicle

This paper presents the design and analysis of a linear actuator for vehicle Eco-Pedal system. To prevent the excessive gas consumption for fuel-efficient vehicle the electric actuator produces a counter force to the vehicles pedal to be pressed stiffly. Major performances of the actuator are required such as a high force density and a low detent force. In this paper, the analysis and design technique of the actuator thrust is based on an analytical method, and the advisability of the design result is verified with both the result of the experiment and the result of the finite element method.

Simple Lead Angle Adjustment Method for Brushless DC Motors

This paper presents a simple lead angle adjustment method for brushless DC motors. The proposed method is based on the motor current dynamics analysis during the current commutation interval. With the proposed scheme, the phase current and phase back-EMF voltage are in phase and the BLDC motor and drive system have a high efficiency induced by the reduced copper and conduction losses. Experimental results are shown to validate the proposed method.

BLDC drive control of electric water pump for automotive application

This paper presents the BLDC drive design of water pump system for automotive application. Electric water pumps offer several advantages. Among them, the efficiency is the main reason for electric water pumps. Conventional mechanical water pump is directly connected by the engine belt. For this reason, regardless of coolant circulation, the conventional mechanical water pump is always operated. The way which the mechanical water pump is replaced by electric water pump could reduce energy consumption. Besides, electric vehicle (EV) do not have the internal combustion engine. Therefore, the EV needs a electric water pump for cooling traction motor and inverter. The electric water pump concept is not new and already introduced [3, 4]. However, the papers mainly introduced overall pump system. This paper deals primarily with the design aspects of the BLDC drive for the water pump. The drive requires sustain temperatures of over 110 [°C]. Rated power is 350 [W] and input voltage is 13.5 [V].