Soft-switched high-frequency power converters for alternative energy systems

随着世界范围内能源需求的增加以及环境问题的关注，集成到现有电网或利用混合交流和直流总线的微电网中的替代能源变得流行，以确保增加的电能安全性。这些能源的输出变化很大，包括一些操作限制，例如：风力发电机中使用的永磁同步发电机（PMSG）产生电压和频率变化的交流输出;海浪能转换中使用的线性同步发电机具有波动的功率，其输出电压波形的幅度和频率变化;燃料电池产生宽变化的低压直流（22至41 V），其对负载变化的瞬态响应缓慢，同时对涟漪电流非常敏感。 * 当不同的能源连接到直流总线时，需要双向DC/DC转换器为电池或超级电容器充电以及为直流总线供电。直流到交流逆变器需要用于公用接口，以增加发电量或用于独立操作。因此，为了满足这些能源所施加的限制，低成本，高效率的电力电子变换器是这种系统不可或缺的一部分。这可以使用以低损耗和高开关频率操作的软开关转换器，其具有许多优点，例如，高效率、小尺寸、轻重量、低EMI、低元件应力等 * 因此，本文的主要工作目标是：（1）提出、分析和设计新型高频（HF）Transformer隔离软开关单相和三相功率变换器拓扑（单向和双向dc/dc、用于公用接口的dc/ac和用于PMSG和线性发电机的具有高功率因数的ac/dc）;（2）开发用于直接ac/ac转换的软开关电子变压器;（3）针对高功率应用的交错操作;以及（4）使用INTUSOFT SPICE或PSIM仿真软件并构建原型实验转换器来研究所设计的转换器的性能。 * 所提出的转换器将具有减小的尺寸和重量（由于高开关频率、低损耗和HF Transformer隔离），从而降低其成本，同时满足能源的严格要求。为风力发电机和海浪发电机开发的AC/DC和AC/AC变换器将具有高功率因数、低谐波失真，其中一些将具有高频Transformer隔离的单级功率变换。在加拿大，利用海浪和风能发电的潜力巨大，所提出的转换器将在这样的系统中有用。本提案预计培养3名博士，3电力电子领域的硕士和几名本科生，重点是替代能源系统的应用。他们将接受分析、设计、模拟和建造实验转换器方面的培训。**

World-wide increased energy demand with environmental concerns, alternative energy sources either integrated to the existing power grid or in a micro-grid utilizing hybrid ac and dc buses are becoming popular to ensure increased electrical energy security. The outputs of these energy sources vary widely including some operational limits, e.g.: permanent magnet synchronous generators (PMSG) used with wind turbines generate ac output of varying voltage and frequency; linear synchronous generators used in sea wave energy conversion have fluctuating power with varying amplitude and frequency output voltage waveform; fuel cells generate wide varying low voltage dc (22 to 41 V) having slow transient response for load changes while they are very sensitive to ripple currents.***   *When different energy sources are connected to a dc bus a bidirectional dc/dc converter is needed for battery or ultracapacitors charging as well as to supply the dc bus. A dc to ac inverter is required for utility interface to augment power generation or for standalone operation. Therefore, to satisfy the constraints imposed by these energy sources, low cost, highly efficient power electronic converters are indispensable part of such systems. This is possible using soft-switching converters operating with low losses and high switching frequencies having a number of advantages, e.g., high efficiency, small size, light weight, reduced EMI, low component stresses, etc. ***   *Therefore, main objectives of this work are: (1) to propose, analyze and design new high-frequency (HF) transformer isolated soft-switching single-phase and 3-phase power converter topologies (unidirectional and bidirectional dc/dc, dc/ac for utility interface and ac/dc with high power factor for PMSG and linear generators); (2) to develop soft-switched electronic transformers for direct ac/ac conversion; (3) interleaved operation for high power applications; and (4) to study the performance of designed converters using INTUSOFT SPICE or PSIM simulation software and building prototype experimental converters.***   *Proposed converters will have reduced size and weight (due to high switching frequency, low losses and HF transformer isolation) reducing their cost while satisfying the stringent requirements of energy sources. Ac/dc and ac/ac converters developed for wind and sea-wave generators will have high power factor, low harmonic distortion, some of them will have single stage power conversion with HF transformer isolation. With huge potential for power generation from sea wave and wind energy in Canada, proposed converters will be useful in such systems. This proposal is expected to train 3 Ph.D., 3 Master and several undergraduate students in the area of power electronics with emphasis on application to alternative energy systems. They will be trained in analysis, design, simulation and building of experimental converters.**