• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1915-1919
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• 2004

In this paper, we propose a new discrete-time predictive current controller for a PMSM(Permanent Magnet Synchronous Motor). The main objectives of the current controllers are to ensure that the measured stator currents tract the command values accurately and to shorten the transient interval as much as possible, in order to obtain high-performance of ac drive system. The conventional predictive current controller is hard to implement in full digital current controller since a finite calculation time causes a delay between the current sensing time and the time that it takes to apply the voltage to motor. A new control strategy in this paper is seen the scheme that gets the fast adaptation of transient current change, the fast transient response tracking and is proposed simplified calculation. Moreover, the validity of the proposed method is demonstrated by numerical simulations and the simulation results will be verified the improvements of predictive controller and accuracy of the current controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.168-174
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• 2016

In this paper, current control using PI controller in the synchronous reference frame is analyzed through the relationship among bandwidth, resonance frequency, and sampling frequency in the grid-connected inverter with LCL filter. Stability is investigated by using bode plot in frequency domain and root locus in discrete domain. The feedback variable is the grid current, which is regulated by the PI controller in the synchronous reference frame. System delay is modeled as 1.5Ts, which contains computational and PWM modulator delay. Two resonance frequencies are given at 815 Hz and 3.16 kHz from LCL filter parameters. Sufficient phase and gain margins can be obtained to guarantee stable current control, in case that resonance frequency is above one-sixth of the sampling frequency. Unstable current control is performed when resonance frequency is below one-sixth of the sampling frequency. Analysis results of stability from frequency response and discrete response is the same regardless of resonance frequency. Finally, stability of current control based on theoretical analysis is clearly verified through simulation and experiment in grid-connected inverters with LCL filter.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2503-2508
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• 2005

In this paper, we propose a new discrete-time predictive current controller for a PMSM(Permanent Magnet Synchronous Motor). The main objectives of the current controllers are to ensure that the measured stator currents tract the command values accurately and to shorten the transient interval as much as possible, in order to obtain high-performance of ac drive system. The conventional predictive current controller is hard to implement in full digital current controller since a finite calculation time causes a delay between the current sensing time and the time that it takes to apply the voltage to motor. A new control strategy in this paper is seen the scheme that gets the fast adaptation of transient current change, the fast transient response tracking. Moreover, the validity of the proposed method is demonstrated by numerical simulations and the simulation results will present the improvements of predictive controller and accuracy of the current controller.

• Journal of Power Electronics
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• v.13 no.3
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• pp.400-408
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• 2013

This paper presents a discrete state-space controller using state feedback control and feed-forward decoupling to provide a desirable control bandwidth and control stability for dynamic voltage restorers (DVR). The paper initially discusses three typical applications of a DVR. The load-side capacitor DVR topology is preferred because of its better filtering capability. The proposed DVR controller offers almost full controllability because of the multi-feedback of state variables, including one-beat delay feedback. Feed-forward decoupling is usually employed to prevent disturbances of the load current and source voltage. Directly obtaining the feed-forward paths of the load current and source voltage in the discrete domain is a complicated process. Fortunately, the full feed-forward decoupling strategy can be easily applied to the discrete state-space controller by means of continuous transformation. Simulation and experimental results from a digital signal processor-based system are included to support theoretical analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.1220-1222
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• 2004

In this paper, we propose a new discrete-time predictive current controller for a PM-LSM(permanent magnet linear synchronous motor). The main objectives of the current controllers are to ensure that the measured stator currents tract the command values accurately and to shorten the transient interval as much as possible, in order to obtain high-performance of ac drive system. A new control strategy is seen the scheme that gets the fast adaptation of transient current change, the fast transient response tracking and is proposed simplified calculation. Moreover, the simulation results will be verified the improvements of predictive controller and accuracy of the current controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.36-45
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• 1998

A simple source voltage clamped resonant link (SVCRL) inverter is proposed to clamp the DC link voltage to the input source voltage and reduce the current rating of resonant inductor. The current control of a permanent magnet synchronous motor (PMSM) using a predictive current control technique (PCCT) employing the SVCRL inverter is also investigated to overcome the disadvantage of the current regulated delta modulation (CRDM) control technique. By using the PCCT based on the discrete model of a PMSM and estimation of back EMF, the minimized current ripple with small number of switchings can be obtained. Finally, the comparative computer simulation and experimental results are given to show the usefulness of the proposed technique.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.7
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• pp.283-288
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• 1985

This paper is concerned with the analysis of microprocessor-based PID control for the current source inverter-induction motor derive system. A linearized dynamic model of the motor is derived and is converted into the discrete-time model. With the equation, the overall system including the feedback loops is formulated into a single discrete-time state equation. The stability regions are determined at various values of controller gains. The transient responses of the motor speed are simulated by digital computer and are verified by laboratory experiments.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.309-311
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• 1996

In this paper, we propose two types of novel discrete time current control methods of modified fixed band hysteresis control and optimal control for Parallel Resonant DC Link Inverters(PRDCLI). Because zero bus voltage intervals are generated on the DC link of PRDCLI, we can obtain the information of counter electromotive force(emf) by a simple estimation strategy. The proposed current controllers predict the currents of the next resonant cycle using the obstained information of counter emf and the average values of DC link voltages. The computer simulation results for a simple equivalent circuit of induction motor show that the proposed control methods are more effective than conventional methods.

• Journal of Power Electronics
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• v.7 no.3
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• pp.213-221
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• 2007

A digital state feedback control method for the current mode control of DC-DC converters is proposed in this paper. This approach can precisely achieve interleaved current sharing among the converter modules. As the controller design and system analysis are performed in the time domain, the proposed method can easily satisfy the required converter specification by using the pole placement technique. The digital state feedback controller in the continuous and discrete time domain is derived for the robust tracking control. For the verification of the proposed control scheme, a parallel module bi-directional converter in a prototype 42V/14V hybrid automotive power system, which is a design example in the continuous time domain, and a parallel module buck converter, which is a design example in the discrete time domain, are implemented using a TMS320F2812 digital signal processor (DSP).

• Journal of Power Electronics
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• v.14 no.6
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• pp.1178-1188
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• 2014

This study proposes a finite-state model predictive controller to regulate the load current and balance the DC-link capacitor voltages of a four-leg neutral-point-clamped converter. The discrete-time model of the converter, DC-link, inductive filter, and load is used to predict the future behavior of the load currents and the DC-link capacitor voltages for all possible switching states. The switching state that minimizes the cost function is selected and directly applied to the converter. The cost function is defined to minimize the error between the predicted load currents and their references, as well as to balance the DC-link capacitor voltages. Moreover, the current regulation performance is improved by using a two-step prediction horizon. The feasibility of the proposed predictive control scheme for different references and loads is verified through real-time implementation on the basis of dSPACEDS1103.