José Luis Romeral Martínez

On the effect of accessible neutral point in fault tolerant five phase PMSM drives

This study deals with the fault tolerant vector control strategies of a five-phase permanent-magnet (PM) machine. The analysis is focused on the effect of accessible neutral point under faulty conditions. Open circuit fault of one and two phases are considered, and proper control strategies are proposed to reduce the amplitude of currents in the remaining healthy phases. Simulations under both healthy and faulty conditions have been undertaken, and the effect of accessible neutral point on current amplitudes and torque ripple is evaluated.

Bearings fault detection using inference tools

The most used electric machine in the industry is the Induction Motor (IM), due to its simplicity and reduced cost. The analysis of the origin of IMs failures exhibits that the bearings are the major source of fault, and even a common cause of degradation in other kinds of motors as Permanent Magnet Synchronous Machines.

Ripple free fault tolerant control of five phase permanent magnet machines

This study is dealt with fault tolerant control of five phase permanent magnet (PM) machines. The main objectives are to increase the output power while eliminating the generated torque ripples. As a new aspect, the effect of available neutral connection is evaluated on the output power and torque ripples.

A novel broken rotor bar fault detection method using park's transform and wavelet decomposition

Detection of broken rotor bars has been an important but difficult work in fault diagnosis area of induction motors. The characteristic frequency components of faulted rotor are very close to the power frequency component but by far less in amplitude, which brings about great difficulty for accurate detection. In the present study, a new method is proposed in order to remove the main frequency component, resulting in more efficient detection of the rotor fault characteristics in the frequency spectrum of stator currents. The method is based on Parks transformation in combination with discrete wavelet decomposition to eliminate the effect of main frequency and zoom on the energy of objective fault related frequency components. In addition, the method efficiency is evaluated using Simulations in Matlab.

A Novel Active Gate Driver for Improving SiC MOSFET Switching Trajectory

The trend in power electronic applications is to reach higher power density and higher efficiency. Currently, the wide band-gap devices such as silicon carbide MOSFET (SiC MOSFET) are of great interest because they can work at higher switching frequency with low losses. The increase of the switching speed in power devices leads to high power density systems. However, this can generate problems such as overshoots, oscillations, additional losses, and electromagnetic interference (EMI). In this paper, a novel active gate driver (AGD) for improving the SiC MOSFET switching trajectory with high performance is presented. The AGD is an open-loop control system and its principle is based on gate energy decrease with a gate resistance increment during the Miller plateau effect on gate–source voltage. The proposed AGD has been designed and validated through experimental tests for high-frequency operation. Moreover, an EMI discussion and a performance analysis were realized for the AGD. The results show that the AGD can reduce the overshoots, oscillations, and losses without compromising the EMI. In addition, the AGD can control the turn-on and turn-off transitions separately, and it is suitable for working with asymmetrical supplies required by SiC MOSFETs.

Efficiency evaluation of five-phase outer- rotor fault-tolerant BLDC drives under healthy and open-circuit faulty conditions

Fault tolerant motor drives are an interesting subject for many applications such as automotive industries and wind power generation. Among different configurations of these systems, five-phase BLDC drives are gaining more importance which is because of their compactness and high efficiency. Due to replacement of field windings by permanent magnets in their rotor structure, the main sources of power losses in these drives are iron (core) losses, copper (winding) losses, and inverter unit (semiconductor) losses. Although low amplitude of power losses in five-phase BLDC drives is an important aspect for many applications, but their efficiency under faulty conditions is not considered in previous studies. In this paper, the efficiency of an outer-rotor five phase BLDC drive is evaluated under normal and different faulty conditions. Open-circuit fault is considered for one, two adjacent and two non-adjacent faulty phases. Iron core losses are calculated via FEM simulations in Flux-Cedrat® software, and moreover, inverter losses and winding copper losses are simulated in MATLAB® environment. Experimental evaluations are conducted to evaluate the efficiency of the entire BLDC drive which verifies the theoretical developments.

Impact of neutral point current control on copper loss distribution of five phase PM generators used in wind power plants

Efficiency improvement under faulty conditions is one of the main objectives of fault tolerant PM drives. This goal can be achieved by increasing the output power while reducing the losses. Stator copper loss not only directly affects the total efficiency, but also plays an important role in thermal stress generations of iron core. In this paper, the effect of having control on neutral point current is studied on the efficiency of five-phase permanent magnet machines. Open circuit fault is considered for both one and two phases, and the distribution of copper loss along the windings are evaluated in each case. It is shown that only by having access to neutral point, it is possible to generate less stator thermal stress and more mechanical power in five-phase permanent magnet generators. Wind power generation and their applications are kept in mind, and the results are verified via simulations and experimental tests on an outer-rotor type of five-phase PM machine.

Fault-tolerant model predictive control of five-phase permanent magnet motors

This paper deals with fault tolerant model predictive control (MPC) of five-phase brushless direct current (BLDC) motors. The model of machine is used to estimate the stator currents for the next modulation period, and then, the required voltages are calculated to minimize the current errors. Center aligned five-phase space vector modulation (SVM) is used in the inverter section. The proposed controlling strategy is evaluated via simulations in MATLAB environment.

Transient Analysis and Motor Fault Detection using the Wavelet Transform

Induction motors are the most common means of converting electrical power to mechanical power in the industry. Induction machines were typically considered robust machines; however, this perception began to change toward the end of the last decade as low-cost motors became available on the market. Nowadays the most widely used induction motor in the industry is a machine which works at the limits of its mechanical and physical properties. A good diagnosis system is mandatory in order to ensure proper behavior in operation. The history of fault diagnosis and protection is as outdated as the machines themselves. Initially, manufacturers and users of electrical machines used to rely on simple protection against, for instance, overcurrent, overvoltage and earth faults to ensure safe and reliable operation of the motor. However as the tasks performed by these machines became more complex, improvements were also sought in the field of fault diagnosis. It has now become essential to diagnose faults at their very inception, as unscheduled machine downtime can upset deadlines and cause significant financial losses. The major faults of electrical machines can be broadly classified as follows: Electrical faults (Singh et al., 2003): 1. Stator faults resulting in the opening or shorting of one or more stator windings; 2. Abnormal connection of the stator windings; Mechanical faults: 3. Broken rotor bars or rotor end-rings; 4. Static and/or dynamic air-gap irregularities; 5. Bent shaft (similar to dynamic eccentricity) which can result in frictions between the rotor and the stator, causing serious damage to the stator core and the windings; 6. Bearing and gearbox failures. However, as is introduced in the basic bibliography by Devaney (Devaney et al., 2004), the effect of bearing faults is, in most cases, similar to eccentricities and has the same effects on the motor. The operation during faults generates at least one of the following symptoms: 1. Unbalanced air-gap voltages and line currents 2. Increased torque pulsations 3. Decreased average torque 4. Increase in losses and decrease in efficiency 5. Excessive heating 6. Appearance of vibrations

Predictive deadbeat current control of five-phase BLDC machines

Model predictive control algorithms have recently gained more importance in the field of power electronics and motor drives. One of the important categories of model predictive control methods is improved deadbeat control in which the reverse system model is used to calculate the appropriate inputs for the next iteration of controlling process. In this paper, a new improved deadbeat algorithm is proposed to control the stator currents of a five-phase BLDC machine. Extended Kalman filter is used in the structure of proposed controlling method, and system model equations are used to calculate the appropriate voltages for the next modulation period. Proposed controlling method is evaluated by simulations in MATLAB environment.