Byoung-Gun Park

Robust Predictive Current Controller Based on a Disturbance Estimator in a Three-Phase Grid-Connected Inverter

This paper proposes a robust predictive current controller based on a disturbance estimator for a three-phase grid-connected inverter. The various components that deteriorate the performance of a conventional predictive current controller are regarded as disturbances, and a disturbance estimator is constructed using an inverter output voltage and current values. Furthermore, a grid angle is extracted using a phase-locked loop (PLL) with the estimated reactive component of the disturbance; therefore, sensorless grid voltage control is possible. In order to determine the relevant gains in the disturbance estimator, the frequency components corresponding to the unbalanced grid condition and low-order harmonics, as well as the PLL bandwidth, are considered. Moreover, the stability of the disturbance estimator due to parameter errors in the inductor filter is analyzed. The proposed method has an inherent rapid dynamic response due to the conventional predictive current controller, as well as low-cost implementation and robust control performance with regard to the disturbance and noise interference due to use of the combined estimation algorithm. The feasibility of the proposed predictive current control strategy is verified through the examination of experimental results.

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.

Nonisolated ZVT two-inductor boost converter with a single resonant inductor for high step-up applications

The interleaved operation of a two-inductor boost converter system is a very attractive solution for converting the low input voltage (30–50V) of distributed power sources, such as photovoltaic and fuel cells, to the high output voltage (380V/760V) required in grid-connected power conversion applications. However, a soft switching method is required in the two main switches to increase the overall power conversion efficiency. This paper proposes a zero voltage transition (ZVT) two-inductor boost converter using a single resonant inductor to meet these needs. To satisfy the requirement of soft switching in the two main switches, a resonant cell is constructed at the output side with a bidirectional switch, two auxiliary diodes, and a single resonant inductor. This converter has advantages due to its simple circuitry, reduced size, and low cost due to a single resonant inductor. Compared to a case with a resonant cell at the input side, it does not perturb the input current of the distributed sources. Therefore, it is more suitable for stable maximum power point tracking (MPPT) operation. The validity of the proposed ZVT two-inductor boost converter is verified through 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

Parallel reduced-order Extended Kalman Filter for PMSM sensorless drives

This paper proposes a speed sensorless vector control system for a permanent magnet synchronous motor (PMSM) by using a parallel reduced-order extended Kalman filter. The proposed scheme can save computation time greatly and estimate rotor speed and position by using new algorithms according to driving regions. To verify the merit of the proposed scheme, a comparison of a new reduced-order EKF algorithm with a conventional EKF algorithm has been also made in terms of computation time. Simulation and experimental results validate the theoretical analysis and show the feasibility of the proposed estimation technique.

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.

A predictive current control associated to EKF for high performance IPMSM drives

This The accurate current control is essential in high performance Interior Permanent magnet synchronous motors (IPMSM) drives. This paper proposes a predictive current control for a high accuracy and a fast dynamic response. The proposed predictive current control consists of the predictive current control and the Extended Kalman Filter (EKF). The Extended Kalman Filter provides the estimated extended electromotive force (EEMF) for sensorless control as well as the predicted current required to implement the predictive current control. To verify the merit of the proposed scheme, simulation and experimental results validate the theoretical analysis and show the feasibility of the proposed control scheme.

A Novel Short-Circuit Detecting Scheme Using Turn-On Switching Characteristic of IGBT

This paper represents a novel short-circuit detecting scheme using turn-on switching characteristic of IGBT. The proposed scheme has a simple protection circuit, fast fault detection time, and low-cost devices to protect IGBT under short-circuit faults such as fault under load (FUL) and hard switching fault (HSF). The proposed short-circuit detecting scheme using turn-on switching characteristic of IGBT can be integrated as a gate drive integrated circuit (IC) or high voltage integrated circuit (HVIC) because the proposed protection circuit supplements logic and low-voltage component. The feasibility of the proposed short-circuit detecting scheme is verified by simulation results.

Sensorless control of four-switch three-phase PMSM drive using extended kalman filter

This paper investigates performances of an extended kalman filter (EKF)-based cost-effective drive system of a permanent-magnet synchronous motor (PMSM) for low-cost applications. In this paper, the EKF is used as a speed and position estimator and the motor is fed from a four-switch three-phase (FSTP) inverter instead of a conventional six-switch three-phase (SSTP) inverter. This configuration reduces the cost of the inverter, the switching losses, and the complexity of the control algorithms. The robustness of the proposed EKF-based FSTP inverter fed PMSM drive is verified by simulation results at different operating conditions. A comparison of the proposed FSTP inverter fed PMSM drive with a conventional SSTP inverter system is also made in terms of performance and error analysis. The proposed FSTP inverter fed PMSM drive is found quite acceptable considering its performance, cost reduction and other advantages.

Open Circuit Fault Diagnosis Using Stator Resistance Variation for Permanent Magnet Synchronous Motor Drives

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.