Patrick Bartholomeus

A Bidirectional Three-Level DC–DC Converter for the Ultracapacitor Applications

Electrochemical double-layer capacitors, which are well known as ultracapacitors, have intensively been used in power conversion applications such as controlled electric drives, active filters, power conditioners, and uninterruptible power supplies. The ultracapacitor is employed as the energy storage device that can be fully charged/discharged within a few seconds. To achieve better flexibility and efficiency, the ultracapacitor is connected to the power conversion system via an interfacing dc-dc power converter. Various topologies are used as the dc-dc power converter: nonisolated two-level single-phase or multiphase interleaved converters and many varieties of isolated soft-switched dc-dc converters. A three-level nonisolated dc-dc converter as a candidate for ultracapacitor applications is proposed and analyzed in this paper. The topology is theoretically analyzed, and design guidelines are given. The modeling and control aspects are discussed. A 5.5-kW prototype was designed, and the proposed topology was experimentally verified on a general-purpose controlled electric drive. Experimental results are presented and discussed.

The Ultracapacitor-Based Controlled Electric Drives With Braking and Ride-Through Capability: Overview and Analysis

Two issues are still a great challenge in design and application of advanced controlled electric drives: 1) recovery of the braking energy and 2) ride-through capability of the drive system. Apart from ordinary solutions, such as back-to-back and matrix converters, the ordinary drive converter equipped with an energy storage element is used in specific applications such as traction and lift drives. This approach came into focus recently with rapid development of electrochemical double-layer capacitors, so-called ultracapacitors. The ultracapacitor is an electrochemical capacitor having energy density much greater than that of standard electrolytic capacitors. Additionally, the ultracapacitor power density is much higher than that of the existing electrochemical batteries. In this paper, a regenerative controlled electric drive having extended ride-through capability is discussed. The basic principle has been extensively analyzed, including a detailed analysis of all operational modes. A bidirectional three-level dc-dc converter has been considered as the interface power converter. The ultracapacitor design guideline is given. A control algorithm that allows control of the dc bus voltage and the ultracapacitor voltage and current has been presented and briefly analyzed. The regenerative controlled drive system has been tested, and the results are presented and discussed.

Modeling and Control of the Ultracapacitor-Based Regenerative Controlled Electric Drives

Two issues are still a great challenge in the design and application of advanced controlled electric drives, namely, recovery of the braking energy and ride-through capability of the drive system. Apart from the ordinary solutions, such as back-to-back and matrix converters, an approach based on the ordinary diode front-end-drive converter equipped with an energy-storage element is used in some applications, such as traction and lift drives. This approach has come into focus recently with the rapid development of electrochemical double layer capacitors, so-called ultracapacitors. To achieve system flexibility and better efficiency, the ultracapacitor is connected to the drive via a dc-dc converter. The converter is controlled in such a way as to fulfill the control objectives: the control of the dc-bus voltage, the ultracapacitor state of charge, and peak-power filtering. In this paper, we have discussed the modeling and control aspects of the regenerative controlled electric drive using the ultracapacitor as energy-storage and emergency power-supply device. The presented model and control scheme have been verified by simulation and a set of experiments on a 5.5-kW prototype. The results are presented and discussed in this paper.

The Ultracapacitor-Based Regenerative Controlled Electric Drives With Power-Smoothing Capability

Modern controlled electric drive applications, such as lifts, port rubber tyred gantry cranes, and tooling machines, are characterized by high ratio of the peak to average power. Moreover, such applications have a need for braking at rated power. In ordinary drives, the braking energy, which represents 30%-40% of the consumed energy, is dissipated on a brake resistor. Apart from this “energetic” issue, the mains interruption, the input current quality, and the mains peak power are additional issues to be addressed. A novel ultracapacitor-based controlled regenerative electric drive with peak power-smoothing function is presented in this paper. The ultracapacitor with an interconnection dc-dc converter is used to store and recover the braking energy. In addition, the dc-dc converter controls and smooths the rectifier input power. In comparison to state-of-the-art solutions, the new solution has better performance regarding size, cost, and efficiency. The presented solution is theoretically analyzed and experimentally verified. The results are presented and discussed.

A Three-Terminal Ultracapacitor-Based Energy Storage and PFC Device for Regenerative Controlled Electric Drives

Most of modern controlled electric drive applications, such as lifts, cranes, and tooling machines, are characterized by a high ratio of the peak to average power. In addition, such applications have high demand for braking at the full rated power. In ordinary drives, the braking energy, which represents 30%-50% of the consumed energy, is dissipated on a brake resistor. Apart from this “energetic” issue, power supply interruption and the input current quality are two additional issues to be solved. A novel regenerative controlled electric drive based on an ultracapacitor as energy storage is presented in this paper. The ultracapacitor with an interface dc-dc converter is used to store and recover the braking energy. In addition, the dc-dc converter controls the rectifier current and reduces the drive input current total-harmonic-distortion factor down to 30%. Moreover, the dc bus voltage is boosted and controlled to be constant and ripple free regardless of the load and the mains voltage variation. In comparison to state-of-the-art solutions, the new solution has better performance regarding size, cost, and efficiency. The presented solution is theoretically analyzed and experimentally verified. The results are presented and discussed.