A New Voltage Control Method for Single-Phase PWM Inverters

A new voltage control method for single-phase full-bridge PWM inverters that having an output LC filter is proposed in this paper. The proposed voltage controller has a capability to realize a zero steadystate output voltage error with fast response. The zero steady-state output voltage error is achieved by using a controller that is derived by using the virtual LC resonant circuit. Fast response is obtained by using a virtual resistance that is connected in parallel with the filter capacitor. The validity of the proposed method is verified by experimental results

A New Voltage Control Method for Single-Phase PWM Inverters

A  new  voltage  control  method  for  single-phase  full-bridge PWM inverters  that having an output LC filter  is proposed in this paper. The proposed voltage  controller has a capability to realize a zero steadystate output voltage error with fast response. The zero steady-state output voltage error is achieved by using a controller that is derived by using the virtual LC resonant circuit. Fast response is obtained by using a virtual resistance  that  is  connected  in  parallel  with  the  filter  capacitor.  The validity of the proposed method is verified by experimental results

A Microprocessor-Based Control, Scheme for a PWM Voltage-Fed Inverter with an Induction Heating Tank Load

In this paper, the flexibility of programmed control logic is exploited in the close loop control of a PWM thyristor voltage fed inverter supplying an induction heating tank load. The microprocessor used in the control is the MC6809 to which is interfaced the SY6522 versatile interface adapter (VIA). The microprocessor-based scheme performs the dual function of generating the thyristor gating signals as well as estimating and applying control actions to maintain the load power factor at unity and the power delivered to the load at a desired set-point value. The schemed also provides power circuit over-current and over-voltage protection against adverse changes in the inverter input supply and the load. The estimation  of the control variables of the control scheme proportional plus integral controllers constitute the main control program while the application of thyristor gating signals and closed loop control actions are carried out in response  to interrupts external to the microprocessor unit. Illustrative steady state and transient circuit of an experimental model of the induction heater are given

Intelligent UPS Inverter Control Design Using Microcontroller

This paper presents many control algorithms using microcontroller for an uninterruptible power supply (UPS) inverter, in order to provide pure sinusoidal wave 50 Hz, controlled by the PIC-microcontroller. The strategy is to utilize the PIC microcontroller and its special features in controlling the UPS inverter. The first approach accomplished with a classical control Proportional-Integral-Derivative (PID) algorithm. The second approach accomplished with the Fuzzy Logic Control (FLC). The third approach accomplished with nonlinear PID-fuzzy logic controller. The ability of the proposed scheme is validated via a successful implementation on a microcontroller-based UPS inverter. The proposed scheme has shown its robustness on low output voltage distortion, excellent voltage regulation, and it is insensitive to load variation, even under nonlinear loads. Experimental studies are performed to further validate the effectiveness of this scheme. This system may be used with grid-solar energy systems. Keywords: PID Controller, Fuzzy Logic Control, Nonlinear PID-Fuzzy Logic, Takagi Sugeno, Microcontroller Application

Implementation of Three Phase UPS system using Multi-Loop Fuzzy Logic Controller for Linear and Non-Linear Loads

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LQR CONTROL APPROACH APPLIED TO UNINTERRUPTIBLE POWER SUPPLY (UPS)

This paper presents a control strategy applied to high power uninterruptible power supplies with a low switching frequency. In the controller design, the gains are determined by minimizing a cost function, which reduces the tracking error and smoothes the control signal. A recursive least square estimator identifies the parameters model at different load conditions. Then the linear quadratic controller gains are adapted periodically. The output voltage is the only state variable measured.The other state variables are obtained by estimation process. Simulation results show that the proposed control strategy offers good performances for either linear and non-linear loads with low total harmonic distortions (THD) even at low frequencies making it very useful for high power applications. 

LQR CONTROL APPROACH APPLIED TO UNINTERRUPTIBLE POWER SUPPLY (UPS)

This paper presents a control strategy applied to high power uninterruptible power supplies with a low switching frequency. In the controller design, the gains are determined by minimizing a cost function, which reduces the tracking error and smoothes the control signal. A recursive least square estimator identifies the parameters model at different load conditions. Then the linear quadratic controller gains are adapted periodically. The output voltage is the only state variable measured.The other state variables are obtained by estimation process. Simulation results show that the proposed control strategy offers good performances for either linear and non-linear loads with low total harmonic distortions (THD) even at low frequencies making it very useful for high power applications

Synchronous-Frame Harmonic Control for High-Performance AC Power Supplies

In order to achieve the reduction of voltage distortion in ac power supplies (ACPSs), this paper describes an implementation of synchronous-frame control for selected frequencies in the output voltage. The regulation of the fundamental output voltage, as well as that of some low-order harmonics, is achieved using a synchronous-frame controller for each selected frequency in addition to a conventional control. The conventional part conserves good dynamic performance under load changes, while rotating-frame controllers allow a slow, but very precise compensation of the residual errors within the assumption that the harmonics produced by distorting load are slowly varying. Moreover, motivated by a fixed-point implementation, a set of refinements and modifications of the original scheme is proposed, allowing a reduction of signal processing requirements and a new control algorithm structure less sensitive to quantization and rounding errors. This solution is particularly effective for high-power fully digitally controlled ACPSs, where the voltage loop bandwidth is usually not large enough to provide regulation at harmonic frequencies. The proposed control scheme has been implemented using a fixed-point single-chip digital signal processor (ADMC401 by Analog Devices). Experimental results on a 3-kVA three-phase converter prototype show the effectiveness of the proposed approach