There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This paper presents a detailed description of finite control set model predictive control (FCS-MPC) applied to power converters Several key aspects related to this methodology are, in depth, presented and compared with traditional power converter control techniques, such as linear controllers with pulsewidth-modulation-based methods The basic concepts, operating principles, control diagrams, and results are used to provide a comparison between the different control strategies The analysis is performed on a traditional three-phase voltage source inverter, used as a simple and comprehensive reference frame However, additional topologies and power systems are addressed to highlight differences, potentialities, and challenges of FCS-MPC Among the conclusions are the feasibility and great potential of FCS-MPC due to present-day signal-processing capabilities, particularly for power systems with a reduced number of switching states and more complex operating principles, such as matrix converters In addition, the possibility to address different or additional control objectives easily in a single cost function enables a simple, flexible, and improved performance controller for power-conversion systems

Model Predictive Control—A Simple and Powerful Method to Control Power Converters

Predictive control is a very wide class of controllers that have found rather recent application in the control of power converters. Research on this topic has been increased in the last years due to the possibilities of today's microprocessors used for the control. This paper presents the application of different predictive control methods to power electronics and drives. A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples. Predictive control presents several advantages that make it suitable for the control of power converters and drives. The different control schemes and applications presented in this paper illustrate the effectiveness and flexibility of predictive control.

Predictive Control in Power Electronics and Drives

This paper presents a predictive current control method and its application to a voltage source inverter. The method uses a discrete-time model of the system to predict the future value of the load current for all possible voltage vectors generated by the inverter. The voltage vector which minimizes a quality function is selected. The quality function used in this work evaluates the current error at the next sampling time. The performance of the proposed predictive control method is compared with hysteresis and pulsewidth modulation control. The results show that the predictive method controls very effectively the load current and performs very well compared with the classical solutions

Predictive Current Control of a Voltage Source Inverter

In this paper, a new control algorithm is proposed to achieve excellent dynamic performance for DC-DC converters undergoing an input-voltage change. Using the concept of capacitor charge balance, the proposed algorithm predicts the two-switching-cycle duty ratio series to drive the converter back to steady state following an input-voltage transient. The equations needed to calculate the required duty cycle series are presented. By using the proposed algorithm, good transient performance, such as small output-voltage overshoot/undershoot and short recovery time, is achieved. Simulations and experiments are performed using a synchronous buck converter to verify the effectiveness of the proposed algorithm. Results show that the proposed method produces superior dynamic performance over that of a conventional current-mode PID controller.

A Digital Two-Switching-Cycle Compensation Algorithm for Input-Voltage Transients in DC–DC Converters

Provided are circuits and methods for use with a power supply that provides a main output including a main DC voltage having a first AC voltage ripple, or a main DC current having a first AC current ripple. A ripple cancellation converter provides a second AC voltage ripple connected in series with the main output, such that the first AC voltage ripple is substantially cancelled; or a second AC current ripple connected in parallel with the main output, such that the first AC current ripple is substantially cancelled. As a result, substantially ripple-free DC output power is provided.

Ripple cancellation converter with high power factor

A novel digital controller is presented in this paper that significantly improves the dynamic response of a voltage regulator module (VRM). The controller uses a digital linear scheme during steady-state operation and an innovative non-linear scheme during transient load conditions. The proposed non-linear controller accurately calculates the optimal response to an arbitrary load step variation. This paper demonstrates the design procedure of a VRM using the proposed controller. Since the response to the load variation is predictable, an engineer is able to design (without iteration) a VRM that is guaranteed to meet a set of dynamic response criteria (voltage deviation, recovery time).

Novel Digital Controller Improves Dynamic Response and Simplifies Design Process of Voltage Regulator Module

A new predictive control strategy for PFC is presented. Its basic idea is that all of the duty cycles required to achieve unity power factor in a half line period are generated in advance by using a predictive algorithm. Based on the average output voltage in the previous half line period, the duty cycles in the current half line period can be calculated by the predictive algorithm, which is derived from the differential equations of boost topology. An optimization process is incorporated with the predictive algorithm to fine tune the parameter of model for the purpose of further reducing the harmonic current. Benefited from the proposed digital control strategy, the switching frequency of the PFC does not directly depend on the processing speed of the DSP. Simulation results show that the proposed strategy works well and unity power factor can be achieved with wide input voltage and load current variation range.

A new predictive control strategy for power factor correction

Recently, current source drivers (CSDs) have been proposed to reduce the switching loss and gate drive loss in megahertz (MHz) dc-dc converters, in which the duty cycle normally has a steady-state value. However, different from dc-dc converters, the duty cycle of the power factor correction (PFC) converters is modulated fast and has a wide operation range during a half-line period in ac-dc applications. In this paper, an adaptive full-bridge CSD is proposed for the boost PFC converters. The proposed CSD can build adaptive drive current inherently depending on the drain current of the main power MOSFET. Compared to the CSDs with the constant drive current, the advantage of the adaptive drive current is able to reduce the switching loss further when the MOSFET is with a higher switching current, while minimize the drive circuit loss when the MOSFET is with a lower switching current. Therefore, the adaptive CSD is able to realize better design tradeoff between the switching loss and drive circuit loss so that the efficiency can be optimized in a wide operation range. Furthermore, no additional auxiliary circuit and control are needed to realize the adaptive current by the proposed CSD. The experimental results verified the functionality and advantages. For a 1-MHz/300-W boost PFC converter, the proposed CSD improves the efficiency from 89% using a conventional voltage driver to 92.2% (an improvement of 3.2%) with 110 Vac input, 380 V output, and full-load condition.

Yan-Fei Liu

Papers

A Digital Two-Switching-Cycle Compensation Algorithm for Input-Voltage Transients in DC–DC Converters

Ripple cancellation converter with high power factor

Novel Digital Controller Improves Dynamic Response and Simplifies Design Process of Voltage Regulator Module

A new predictive control strategy for power factor correction

Adaptive Continuous Current Source Drivers for 1-MHz Boost PFC Converters