• Journal of Power Electronics
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• v.10 no.6
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• pp.702-708
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• 2010

In this paper, a fault diagnosis algorithm for brushless DC (BLDC) motor drives is proposed to maintain control performance under switch open-damage. The proposed fault diagnosis algorithm consists of a simple algorithm using measured phase current information and it detects open-circuit faults based on the operating characteristic of BLDC motors. The proposed algorithm quickly recovers control performance due to its short detection time and its reconfiguration of the system topology. It can be embedded into existing BLDC drive software as a subroutine without additional sensors. The feasibility of the proposed fault diagnosis algorithm is proven by simulation and experimental results.

• Journal of Power Electronics
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• v.13 no.6
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• pp.985-990
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• 2013

This paper proposes a novel fault diagnosis scheme using parameter estimation of the stator resistance, especially in the case of the open-phase faults of PMSM drives. The stator resistance of PMSMs can be estimated by the recursive least square (RLS) algorithm in real time. Fault diagnosis is achieved by analyzing the estimated stator resistance of each phase according to the fault condition. The proposed fault diagnosis scheme is implemented without any extra devices. Moreover, the estimated parameter information can be used to improve the control performance. The feasibility of the proposed fault diagnosis scheme is verified by simulation and experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.100-105
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• 2003

In this paper, we propose the novel test method effectively to detect short and open faults in CMOS op-amp. The proposed method uses a sinusoidal signal with higher frequency than unit gain bandwidth. Since the proposed test method doesn't need complex algorithm to generate test pattern, the time of test pattern generation is short, and test cost is reduced because a single test pattern is able to detect all target faults. To verify the proposed method, CMOS two-stage operational amplifier with short and open faults is designed and the simulation results of HSPICE for the circuit have shown that the proposed test method can detect short and open faults in CMOS op-amp.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.3
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• pp.266-273
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• 2012

In this paper, the new open fault detection and tolerant operation method for 3 phase PWM rectifier is proposed. When open fault occurred on the inverter switches of 3 Phase PWM rectifier, the DC link voltage ripple is increased because the input current of the faulty phase is distorted. In this case, the quality of electric power would decrease, and the life time of DC link capacitor is decreased. The open fault is detected by a simple MRAS(Model Reference Adaptive System) without additional hardware sensors, and the tolerant operation carried out by turning on the opposite switch of the faulty switch without any redundancy. By the proposed method, the faulty phase input current can be controlled, so that 3-phase input current is balanced relatively under the faulty condition and the voltage ripple of DC link output is reduced. The validity of the proposed technique is proved on the 6kW 3-phase PWM rectifier system by simulation and experiment.

• Journal of Power Electronics
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• v.16 no.3
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• pp.982-993
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• 2016

A method for the fault-tolerant vector control of star-connected 3-phase Induction Motor (IM) drive systems based on Field-Oriented Control (FOC) is proposed in this paper. This method enables the control of a 3-phase IM in the presence of an open-phase failure in one of its phases without the need for control structure changes to the conventional FOC algorithm. The proposed drive system significantly reduces the speed and torque pulsations caused by an open-phase fault in the stator windings. The performance of the proposed method was verified using MATLAB (M-File) simulation as well experimental tests on a 1.5kW 3-phase IM drive system. This paper experimentally compares the operation of the proposed fault-tolerant vector controller and a conventional vector controller during open-phase fault.

• Progress in Superconductivity and Cryogenics
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• v.3 no.1
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• pp.40-44
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• 2001

Recently. the high-tc superconducting fault col-rent limiters (SFCL) are studied worldwide to be classified as a resistive type or an inductive type such as a magnetic shielding type and a inductive type. The high-tc SFCL wish an open core belongs to the magnetic shielding type SFCL. Unlike conventional magnetic shielding type SFCLS it uses the open core to reduce the mechanical vibrations and installation space, The high-tc SFCL with an open core was designed and manufactured by stacking three BSCCO 2212 tubes. It was tested in the maximum source voltage of 400 Vrms. The results such as the reduction of fault current and impedance of the SFCL are described in this paper. The results show that the fault current in the source voltage of 400 Vrms was reduced to be about 123 Apeak. about 3.9 times greater than the normal state current. Also, the impedance of the high-tc SFCL was about 9${\Omega}$ about 9 times greater than the normal state impedance. The impedance of the SFCL appears just after the fault, and its size is dependent on the source voltage. From the impedance, the inductance of the SFCL was calculated.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.217-224
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• 2013

This paper presents a diagnostic method for a sparse matrix converter that detects faults in any single switch or a pair of switches. The sparse matrix converter is functionally equivalent to the standard matrix converter but has a reduced number of switches. The proposed diagnostic method is based in the measurement of input and output currents. The currents have respective characteristic according to the location of faulty switches. This method not only detects the switches of open-circuit fault but identifies the location of the faulty switching devices without complicated calculations. The simulation and experimental results verify that, based on the proposed method, the fault of sparse matrix converter can be easily and fast detected.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.722-732
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• 2018

Dual type Independent multi-phase BLDC Motor (DI-BLDCM) is designed to be robust to faulty conditions of motor and drive system. Despite the efforts of the motor design, open-switch faults of DI-BLDCM drive system cause the torque ripple of the motor. This torque ripple makes unwanted sound noise and mechanical vibration of associated systems. This paper proposes four methods for compensating the torque ripple and compares the characteristics of each proposed method. All proposed methods are able to reduce the torque ripple to similar level of the healthy condition, although the motor operates in open-switch fault conditions. However, these methods have different characteristics in various fault conditions. Therefore, from the results of the comparison, the suitable method is selected for the various fault conditions. The feasibility of the proposed methods is proved by the several experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.601-607
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• 2010

For commercial success of emerging service robots, the fault tolerant technology for system reliability and human safety is crucial. Traditionally fault tolerance methods have been implemented in application level. However, from our studies on the common design patterns in fault tolerance, we argue that a framework-based approach provides many benefits in providing reliability for system development. To demonstrate the benefits, we build a framework-based fault tolerant engine for OPRoS (Open Platform for Robotic Services) standards. The fault manager in framework provides a set of fault tolerant measures of detection, isolation, and recovery. The system integrators choose the appropriate fault handling tools by declaring XML configuration descriptors, considering the constraints of components and operating environment. By building a fault tolerant navigation application from the non-faulttolerant components, we demonstrate the usability and benefits of the proposed framework-based approach.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.164-171
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• 2006

In this paper, the fault tolerant system for BLDC motor has been proposed to maintain control performance under an open switch fault of inverter. The fault identification is proposed to two methods, which are using the difference between reference and actual current, and adding voltage sensors across lower legs of inverter. The reconfiguration scheme is achieved by the four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. The proposed fault tolerant system quickly recovers control performance by short fault detecting time and reconfiguration of system topology. Therefore, continuous free operation of the BLDC motor drive system after faults is available. The superior performance of the proposed fault tolerant system is proved by simulation.