2002 IEEE 33rd Annual IEEE Power Electronics Specialists Conference. Proceedings (Cat. No.02CH37289)

This paper presents a single-phase three-wire (1/spl phi/3W) grid-connection photovoltaic (PV) power inverter with a feature of a partial active power filter (PAPF), which can not only deal with PV power but can filter current harmonics and improve power factor. Once the processed power exceeds the switch ratings, the inverter can reduce its output reactive power and harmonic power, while still can supply the maximum real power generated by the PV arrays. In derivation of control laws, a limit circle is defined to confine the output power of the inverter. To determine the power that the inverter can process, a criterion is proposed to find reactive power, which can avoid complex detections of phase angle and magnitude of the fundamental component of a nonlinear load current. Simulation results and experimental measurements have verified the proposed algorithm and the feasibility of the inverter.

This paper describes the developments at the University of Minnesota of new approach in teaching of electric drives, focusing on the associate state-of-the-art laboratory. The mission of these developments is to nationally revitalize courses in industrially and strategically vital fields of electric drives (and power electronics). This is accomplished by making these courses appealing to students (undergraduate enrollments have significantly increased subsequent to adopting these approaches) where they receive a first-rate education in just one undergraduate course in a way that ensures a seamless continuity to advanced courses. The laboratory is based on a dSPACE development board and several custom designed power converter boards and electric motors, working on a 42 V DC-bus voltage system.

This paper presents high voltage (HV) NMOS based level shifters, bootstraps and charge pumps in direct and cascaded topologies, which are highly useful to implement either power integrated circuits (PICs) high-side transistor floating drives or compact inductorless DC-DC power supplies. Monolithic solutions resorting to a unique HV NMOS switching cell are very important when standard CMOS technologies are intended to be used. In fact, these floating drives are fully CMOS compatible. Even while using a dedicated PIC technology this approach is a cost effective one. Furthermore, topologies based on a unique HV NMOS can be implemented in regular and simple geometry, thus, they are prone to be easily configured by top metal layers and to pave the way to mask configurable PICs. Simulation and experimental results obtained for a level shifter, a bootstrap and a charge pump used either as voltage multiplier or as a floating voltage source are presented and discussed. These low cost solutions are highly desirable for mobile applications power management and an efficient drive either for PICs or for intelligent devices.

In this paper, a low-power bidirectional DC/DC converter for inverter battery charger applications is considered. Initially, a galvanically isolated and synchronously rectified DC/DC converter topology is prototyped and its stationary performance evaluated. Next, a nonlinear dynamic model of the converter is derived using a state space averaging method. The dynamic model is nonlinear in the sense that it is a function of both converter duty cycle and load. The nonlinear model is then digitized and a proposed simulation algorithm derived and successfully validated against empirical data from the prototype converter. Finally, the large signal circuit dynamics are analyzed and an adaptive, fully digital pole placement controller is examined in adaptive and nonadaptive modes of operation.

The new edition of the IEC-1000-3-2 standard has led to the need for certain major concepts to once again come under the microscope for reconsideration. As the Class D template has disappeared, circuits designed to comply with the regulation by changing from Class D to Class A are now obsolete. The LC filter complies with the regulation in Class A with a very small inductance. To comply with Class D requirements a new circuit, which has been called a TLC rectifier, is proposed in this paper to reduce the passive device. The results obtained have been verified by computer simulation and experimental results.

Most infinite impulse response (IIR) digital filter implementations in power electronic inverter applications are based on the time shift operator q and its associated z-transform. But for higher sampling frequencies where the sample period approaches zero for z-transform discrete systems, their dynamic response does not converge smoothly to the continuous counterpart, causing substantial implementation problems. In contrast, the response of filters based on the delta operator does converge to the continuous counterpart for smaller sample periods, and hence they are much better suited for digital control applications where sampling frequencies are much higher than the system poles. This paper presents a practical overview describing the use of the delta operator for IIR digital filter systems, and shows how the operator can be used in power electronic inverter applications to achieve substantial performance benefits compared to equivalent shift-based implementations. A transformation is presented to convert shift-based implementations to the delta form, and the specific examples of an active filter and a P+ resonant current regulator are used to illustrate the improvements that can be expected. The superior performance of the delta operator for digital control of inverter applications has been verified in both simulation and experiment.

Polymer bonded magnetic materials offers many advantages compared to the conventional type of magnetic materials including shape, physical property and cost. This is a new type of materials which will form a new era of power conversion and is also a new area of research. Until today, no research has been reported on use of polymer bonded magnetic materials. This research studies the method of fabricating a micro-powder filled magnetic polymer composite, its magnetic property and electric property. The paper also describes the application in high frequency power conversion. A phase-shifted converter using self-resonance which is especially useful for transformers constructed from low permeability materials was used to examine the core. A flyback converter is also used to confirm the use as a coupled inductor. Measured characteristics of the materials and the power conversion measurement data confirm the feasibility of the proposed materials.

This paper presents a current controlled AC/DC converter for high frequency power architecture. The proposed converter employs a resonant network, a bi-direction shunt switch, an output transformer, synchronous rectifiers and an output filter. The resonant network is designed in such a way that it provides an AC current source at its output while drawing near sinusoidal input current. The operating principle of the circuit is given, and the steady state analysis is performed. It is shown that the converter has very high input power factor, low total harmonic distortion and fast transient response. Experimental and simulation results of a prototype converter converting the input AC voltage of 28 V RMS at 1 MHz, to 1.6 V DC at 20 A are given to verify the proof of concept, and analytical work reported in this paper.

An improved lumped-charge model of PIN diodes is described. This model includes reverse and forward recovery, emitter recombination and boundary-moving effects. Especially for reverse recovery, both sweeping out and recombination effects are taken into account Based on the model, most parameters can be extracted by a new accurate curve-fitting approach, and the other can be obtained by simple experiments. Comparison between simulation and experimental results for transient behavior verifies the model and the parameter extraction approach.

This paper presents a power converter for coupling photovoltaic arrays to the utility grid. The converter draws a programmable, ripple-free DC current from the photovoltaic array and injects power into the grid at unity power factor. The programmable input current feature makes this converter ideal for use with maximum power point tracking technology. The proposed converter has an additional unique feature in that the internal dc link carries a large (approximately 25%) ripple voltage. Allowing a large ripple on the DC link reduces the required size of the link capacitor. This paper includes basic system information, analysis of filter requirements, controller design and preliminary hardware results.