Control Systems of Single-Phase Voltage Source Inverters for a UPS

2016

IET Power Electronics

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The standard single-phase three-level voltage source inverter (VSI) for uninterruptible power supply systems consist of a pulse width modulation (PWM) modulator, an H-bridge, and an output inductance/capacitance filter. The design of most control systems requires the inverter small-signal model. Two approaches for the discrete modelling of the VSI can be considered. The first is based on solving the state space equations during the switching period, which yields a discrete model that depends on the single-edge or double-edge type of PWM model. The second approach is the based on the continuous model of the inverter, which is derived from measurements of the real inverter and its discretisation. Both models should regard the increase in the real value of the equivalent coil series resistance and changes in the filter coil inductance with the frequency and amplitude of the magnetising current. The design of the control system requires experimental estimation of the additional delays, which are outside of the models during the measurements and modelling. Both models are validated by comparing the closed-loop systems with the simple instantaneous controllers in the experimental model.

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Section: Discrete Inverter Model Based On Measurementsmentioning

confidence: 99%

Section: Discrete Inverter Model Based On Measurementsmentioning

confidence: 99%

Different approaches to modelling single‐phase voltage source inverters for uninterruptible power supply systems

2016

IET Power Electronics

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“…The demands of the EN 62040–3 standard are related to dynamic or static and linear or nonlinear loads. The one‐loop SISO system is generally not able to meet the output voltage quality demands for a nonlinear load ( total harmonic distortion (THD) < 8% for the rectifier RC load with power factor PF = 0.7) . Noticeable dynamic distortions of the inverter output voltage appear during step unloading.…”

Section: Control System Examples Based On the Presented Modelsmentioning

confidence: 99%

“…Figure presents the influence of a single PI SISO control loop on the inverter output voltage for a nonlinear rectifier RC load. Both approaches to the modelling give almost the same, rather unsatisfactory, result, which has been predicted in Rymarski . The control loop increases the output voltage to the reference level (compensating for the voltage drop on the output resistance of the inverter) and slightly decreases THD (from 14 to 10%) to the same degree for both models.…”

Section: Control System Examples Based On the Presented Modelsmentioning

confidence: 99%

“…The control loop increases the output voltage to the reference level (compensating for the voltage drop on the output resistance of the inverter) and slightly decreases THD (from 14 to 10%) to the same degree for both models. The problem of the output voltage distortions for the nonlinear rectifier RC load, depending on the design of the output filter (the choice of L F / C F value), is widely discussed in Rymarski , Rymarski , and Rymarski . A repetitive controller is a simple and a very efficient control system solution , , .…”

Section: Control System Examples Based On the Presented Modelsmentioning

confidence: 99%

See 1 more Smart Citation

The dynamic properties of a single‐phase transformer‐based inverter for ups systems

2015

Circuit Theory & Apps

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SUMMARYThis paper presents two algorithms for the creation of an analytical model of a single-phase transformerbased inverter, using either the measurements of the control frequency-dependent characteristics of the inverter or the initial in-circuit frequency-dependent measurements of the transformer. The paper discusses how the parameters of the line transformer influence the dynamic properties of the inverter and, as a consequence, the design of the instantaneous control feedback loop. Line transformers, widely used in industry, have not yet been analysed for use at higher than normal operating frequencies. The basic parameters of the transformer are the nonlinear functions of the primary voltage amplitude and frequency. The paper includes verification of both methods using the breadboard experimental model. In the final step, the inverter control transfer functions are calculated. To show the utility of both models, an exemplary discrete controller for the experimental inverter model has been designed and tested.

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The influence of the properties of magnetic materials on a voltage source inverter control

2014 IEEE Conference on Control Applications (CCA)

Dyga

2014