Polynomial Curve Slope Compensation for Peak-Current-Mode-Controlled Power Converters

Linear ramp slope compensation (LRC) and quadratic slope compensation (QSC) are commonly implemented in peak-current-mode-controlled dc-dc converters in order to minimize subharmonic and chaotic oscillations. Both compensating schemes rely on the linearized state-space averaged model (LSSA) of the converter. The LSSA ignores the impact that switching actions have on the stability of converters. In order to include switching events, the nonlinear analysis method based on the Monodromy matrix was introduced to describe a complete-cycle stability. Analyses on analog-controlled dc-dc converters applying this method show that system stability is strongly dependent on the change of the derivative of the slope at the time of switching instant. However, in a mixed-signal-controlled system, the digitalization effect contributes differently to system stability. This paper shows a full complete-cycle stability analysis using this nonlinear analysis method, which is applied to a mixed-signal-controlled converter. Through this analysis, a generalized equation is derived that reveals for the first time the real boundary stability limits for LRC and QSC. Furthermore, this generalized equation allows the design of a new compensating scheme, which is able to increase system stability. The proposed scheme is called polynomial curve slope compensation (PCSC) and it is demonstrated that PCSC increases the stable margin by 30% compared to LRC and 20% to QSC. This outcome is proved experimentally by using an interleaved dc-dc converter that is built for this work

SINGLE-DEGREE-OF-FREEDOM EXPERIMENTS DEMONSTRATING ELECTROMAGNETIC FORMATION FLYING FOR SMALL SATELLITE SWARMS USING PIECEWISE-SINUSOIDAL CONTROLS

This thesis presents a decentralized electromagnetic formation flying (EMFF) control method using frequency-multiplexed sinusoidal control signals. We demonstrate the EMFF control approach in open-loop and closed-loop control experiments using a single-degree-of-freedom testbed with an electromagnetic actuation system (EAS). The EAS sense the relative position and velocity between satellites and implement a frequency-multiplexed sinusoidal control signal. We use a laser-rangefinder device to capture the relative position and an ARM-based microcontroller to implement the closed-loop control algorithm. We custom-design and build the EAS that implements the formation control in one dimension. The experimental results in this thesis demonstrate the feasibility of the decentralized formation control algorithm between two satellites

AN ENERGY BASED MINIMUM-TIME OPTIMAL CONTROL OF DC-DC CONVERTERS

Time-optimal response is an important and sometimes necessary characteristic of dynamic systems for specific applications. Power converters are widely used in different electrical systems and their dynamic response will affect the whole system. In many electrical systems like microgrids or voltage regulators which supplies sensitive loads fast dynamic response is a must. Minimum time is the fastest converter to compensate the step output reference or load change. Boost converters as one of the wildly used power converters in the electrical systems are aimed to be controlled in optimal time in this study. Linear controllers are not able to provide the optimal response for a boost converter however they are still useful and functional for other applications like reference tracking or stabilization. To obtain the fastest possible response from boost converters, a nonlinear control approach based on the total energy of the system is studied in this research. Total energy of the system considers as the basis for developing the presented method, since it is easy and accurate to measure besides that the total energy of the system represents the actual operating condition of the boost converter. The detailed model of a boost converter is simulated in MATLAB/Simulink to achieve the time optimal response of the boost converter by applying the developed method. The simulation results confirmed the ability of the presented method to secure the time optimal response of the boost converter under four different scenarios

GEOPLEX: Back-to-back converter for an electrical machine application

The architecture of a back-to-back converter, needed to feed the rotor windings of a 3-phase doubly-fed induction machine and such that power can flow both ways, is described, from both the modelling and experimental viewpoints. In particular, a PCHS model using selected GSSA variables is described in detail. Some new and improved results concerning the detailed PCHS structure of a GSSA expansion of a PCHS are also presented

Design of Digital Robust Controller for a Class-D Amplifier Using A2DOF

AbstractIn recent years, it is desired that the bandwidth of a class-D amplifier is widened using sampling frequencies as low as possible. For example, it is expected in the application of the power supply of a low frequency immunity test, or an audio power amplifier, or the power amplifier of vibration generator. In this paper, it is shown that the bandwidth of the class-D amplifier can be widened to 20[kHz] by an A2DOF (Approximate 2-Degree-Of-Freedom) digital controller with 500[kHz] sampling frequencies. The controller is implemented by a DSP (digital signal processor). It is shown from experiments that 20[kHz] bandwidth can be maintained even if load changes

A Zero-Transient Dual-Frequency Control for Class-E Resonant DC-DC Converters

In this paper, a dual-frequency control method for regulating the output power in class-E resonant DC-DC converters has been introduced. As in the standard ON-OFF control or other recently proposed dual-frequency controls, the approach is based on the ability of the converter to alternately operate in a high- and a low-power state. The proposed solution has a twofold advantage: on the one hand, soft-switching capabilities (i.e., Zero-Voltage and Zero-Voltage-Derivative switching) are preserved in both operating states; on the other hand, it is possible to reduce to zero the transient time required to switch from one state to the other one. The most straightforward consequence is the possibility to increase to very large values the frequency at which the two operating states are switched, up to the same order of magnitude as the main switching frequency of the converter. In this way, the additional ripple introduced by the proposed dual-frequency control can be decreased to a negligible value. The approach has been validated by measurements on a prototype operating between 4 MHz and 8 MHz and in which it has been possible to increase the control frequency up to 500 kHz

Analysis, Design and Control of a Modular Full-Si Converter Concept for Electric Vehicle Ultra-Fast Charging

L'abstract è presente nell'allegato / the abstract is in the attachmen

Solar Charging Station

The purpose of this project was to design and develop a proof of concept Solar Charging Station capable of delivering power to up to four cell phones and two laptop computers simultaneously. A custom maximum power point tracker (MPPT) was designed to extract the maximum amount of power available from the solar panels. This MPPT sampled the voltage and current output of the solar panels and executed the “perturb and observe” algorithm to determine the maximum power point

Measurements, Models, Systems and Design

531 s.