Soft-Switching High-Frequency AC-Link Universal Power Converters with Galvanic Isolation

In this dissertation the ac-link universal power converters, which are a new class of power converters, are introduced and studied in detail. The inputs and outputs of these converters may be dc, ac, single phase, or multi-phase. Therefore, they can be used in a variety of applications, including photovoltaic power generation, wind power generation, and electric vehicles. In these converters the link current and voltage are both alternating and their frequency can be high, which leads to the elimination of the dc electrolytic capacitors and the bulky low-frequency transformers. Therefore, the ac-link universal power converters are expected to have higher reliability and smaller size. Moreover, these converters are soft switching, which results in negligible switching losses and minimized current and voltage stress over devices. In the first part of the dissertation, the parallel ac-link universal power converter is studied in detail. This converter is an extension of the buck-boost converter. The series ac-link universal power converter, which is dual of the parallel ac-link universal power converter, is proposed in the second part of this dissertation. This converter is an extension of the Cuk converter. A modified configuration with fewer switches, named sparse ac-link universal power converter is proposed in the third part of this dissertation. The sparse ac-link universal power converters can appear as parallel or series. The performance of all these configurations is evaluated through simulations and experiments

E-Mobility -- Advancements and Challenges

Mobile platforms cover a broad range of applications from small portable electric devices, drones, and robots to electric transportation, which influence the quality of modern life. The end-to-end energy systems of these platforms are moving toward more electrification. Despite their wide range of power ratings and diverse applications, the electrification of these systems shares several technical requirements. Electrified mobile energy systems have minimal or no access to the power grid, and thus, to achieve long operating time, ultrafast charging or charging during motion as well as advanced battery technologies are needed. Mobile platforms are space-, shape-, and weight-constrained, and therefore, their onboard energy technologies such as the power electronic converters and magnetic components must be compact and lightweight. These systems should also demonstrate improved efficiency and cost-effectiveness compared to traditional designs. This paper discusses some technical challenges that the industry currently faces moving toward more electrification of energy conversion systems in mobile platforms, herein referred to as E-Mobility, and reviews the recent advancements reported in literature

DC capacitor-less power converters

Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally. All embodiments permit the use of smaller reactive components in the link stage and the use of AC rather than DC capacitors, which reduces size and costs of the device while increasing the reliability.U

DC capacitor-less power converters

Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally. All embodiments permit the use of smaller reactive components in the link stage and the use of AC rather than DC capacitors, which reduces size and costs of the device while increasing the reliability.U

Sparse and ultra-sparse partial resonant converters

The AC portion of the input of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-forward-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The second direction is opposite to the first direction. The AC portion of the output of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-reverse-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The forward-conducting-reverse-blocking devices can be switches or diodes.U

Sparse and ultra-sparse partial resonant converters

The AC portion of the input of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-forward-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The second direction is opposite to the first direction. The AC portion of the output of the ultra-sparse partial resonant power converter contains three pairs of forward-conducting-bidirectional-blocking switches connected in a first direction, and two pairs of forward-conducting-reverse-blocking devices connected in a second direction to the three pairs of forward-conducting-bidirectional-blocking switches. The forward-conducting-reverse-blocking devices can be switches or diodes.U

DC capacitor-less power converters

Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally. All embodiments permit the use of smaller reactive components in the link stage and the use of AC rather than DC capacitors, which reduces size and costs of the device while increasing the reliability.U

DC capacitor-less power converters

Three resonance-based universal power converter topologies are disclosed. One includes a partially resonant parallel L-C link and incorporates intermediate cross-over switching circuits between the link stage and each of the input and output stages (which are constructed using unidirectional switches), thereby permitting the partially resonant circuit to be operated bi-directionally. A second includes a partially resonant series LC link in parallel with the input and output networks. A third includes a partially resonant series LC link in series between the input and output networks. The input and output networks can be formed from either bidirectional switches or a combination of unidirectional switches and intermediate cross-over switching circuits, permitting the partially resonant circuit to be operated bi-directionally. All embodiments permit the use of smaller reactive components in the link stage and the use of AC rather than DC capacitors, which reduces size and costs of the device while increasing the reliability.U