Ji-Su Ryu

Simple Fault Diagnosis Based on Operating Characteristic of Brushless Direct-Current Motor Drives

In this paper, a simple fault diagnosis scheme for brushless direct-current motor drives is proposed to maintain control performance under an open-circuit fault. The proposed scheme consists of a simple algorithm using the measured phase current information and detects open-circuit faults based on the operating characteristic of motors. It requires no additional sensors or electrical devices to detect open-circuit faults and can be embedded into the existing drive software as a subroutine without excessive computation effort. The feasibility of the proposed fault diagnosis algorithm is proven by simulation and experimental results.

Fault Tolerant Strategies for BLDC Motor Drives under Switch Faults

In this paper, the fault tolerant system for BLDC motors has been proposed to maintain the control performance under switching device faults of inverter. The proposed fault tolerant system provides compensation for open-circuit faults and short-circuit faults in power converter. The fault identification is quickly achieved by simple algorithm using the characteristic of BLDC motor drives. The drive system after fault identification is reconfigured by the four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. The feasibility of the proposed fault tolerant system is proved by simulation

Fuzzy back-EMF observer for improving performance of sensorless brushless DC motor drive

In this paper, a sensorless brushless DC (BLDC) motor drive using the fuzzy back-EMF observer is proposed to improve the performance of conventional sensorless drive methods. Most existing sensorless methods of the BLDC motor have low performance at transients or low speed range and occasionally require additional circuit. To cope with this problem, the estimation of a back-EMF using the fuzzy logic is suitable for high performance because the back-EMF of the BLDC motor has a trapezoidal shape. The proposed algorithm using fuzzy back-EMF observer can achieve robust control for the change of an external condition and continuously estimate speed of the rotor at transients as well as steady state. The robustness of the proposed algorithm is proved through the simulation and is compared with other sensorless drive methods.

Unknown input observer for a novel sensorless drive of brushless DC motors

In this paper, a motor control method is proposed to improve the performance of sensorless drive of BLDC motors. In the terminal voltage sensing method, which is a great portion of sensorless control, a precise rotor position cannot be obtained when excessive input is applied to the drive during synchronous operation mode. Especially in the transient state, the response characteristic decreases. To cope with this problem, the unknown input (back-EMF) is modeled as the additional state of system in this paper. Taking into account the disturbance adopted by the back-EMF, the observer can be obtained by an equation of the augmented system. An algorithm to detect the back-EMF of a BLDC motor using the state observer is constructed. As a result, a sensorless drive of BLDC motors that can strictly estimate rotor position and speed is proposed.

Fault Tolerant System under Open Phase Fault for BLDC Motor Drives

In this paper, the fault tolerant system for BLDC motor has been proposed to maintain the control performance under the open fault of inverter. The fault identification method is proposed to two different types. The one is the method by the difference between reference and actual current. The other is the method using additional 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 the control performance by short detecting time and reconfiguration of system topology. Therefore, continuous free operation of the BLDC motor drive system after faults is available. The feasibility of the proposed fault tolerant system is proved by simulation.

A simple fault detection of the open-switch damage in BLDC motor drive systems

This paper proposes a novel fault detection algorithm for a brushless DC (BLDC) motor drive system. This proposed method is configured without the additional sensor for fault detection and identification. The fault detection and identification are achieved by a simple algorithm using the operating characteristic of the BLDC motor. The drive system after the fault identification is reconfigured by four-switch topology connecting a faulty leg to the middle point of DC-link using bidirectional switches. This proposed method can also be embedded into existing BLDC motor drive systems as a subroutine without excessive computational effort. The feasibility of a novel fault detection algorithm is validated in simulation.

Sensorless drive of brushless DC motors using an unknown input observer-IECON'05

In this paper, a novel motor control method is proposed to improve the performance of sensorless drive of BLDC motors. In the terminal voltage sensing method, which is a great portion of sensorless control, a precise rotor position cannot be obtained when excessive input is applied to the drive during synchronous operation mode. Especially in the transient state, the response characteristic decreases. To cope with this problem, the unknown input (back-EMF) is modelled as the additional state of system in this paper. Taking into account the disturbance adopted by the back-EMF, the observer can be obtained by an equation of the augmented system. An algorithm to detect the back-EMF of a BLDC motor using the state observer is constructed. As a result, a novel sensorless drive of BLDC motors that can strictly estimate rotor position and speed is proposed.