功率变换领域采用高频技术是当前和未来功率变换和分配技术的主要发展方向之一。高频技术越来越多的应用使得软开关技术显得日益重要，与之相应的各种调制与控制技术也得到了进一步的发展，高频交流脉冲密度调制(PDM)控制技术就是其中之一。 PDM控制策略是一种零电压技术，对开关管损耗问题的解决有着重要的意义，而且能够较容易地将高频交流信号低失真地合成幅值和频率不同的低频信号。PDM技术的特点是将高频交流脉冲信号的整数半周期作为合成低频信号的基本单元，通过比较同时刻参考波形和输出波形的面积差，控制增加或减少高频脉冲的数目使得两个曲线包围的面积可以基本维持平衡。 根据PDM基本理论，本文研究并总结了将该技术应用到三相全桥电路的具体控制方法，通过建立仿真模型验证了该方法的正确性与可行性。在此基础上，给出了该系统的硬件设计与软件设计。硬件设计包括主电路的设计和以ARM控制器为核心的控制电路的设计，软件设计主要实现了PDM控制算法及三相全桥电路的驱动控制等。 研究表明，本文提出的这种高频交流脉冲密度调制技术适用于高频交流环节功率变换分布系统，特别适合应用于空间站的电源、航空航天飞行器的辅助电源、电动汽车和矿用电机车的高级驱动系统。

With increasing requirement of small size and light weight of converter, the soft-switch technique is becoming more important. Correspondently, various controlling and modulating technologies have been developed. The pulse density modulation (PDM) is the one of them, which can reduce switching loss effectively. The main characteristic of this PDM technique is that an integral half cycle of the high-frequency link voltage becomes the basic unit of synthesis of the low-frequency signal. And an area balance between the reference signal and synthesized signal is inherently maintained by increasing or deducing the next pulse of the high-frequency link voltage. PDM can efficiently synthesize low-distortion, variable frequency, variable amplitude，and low frequency voltage signals from the fixed-frequency regulated-amplitude voltage of the high frequency link. Currently, the research on PDM technique is not as much as on the other controlling techniques, especially in aspect of application. The further study on PDM and the disclosure of the controlling principle will be useful for the extensive research in this field. In this paper, control strategy implementation is analyzed, the feasibility and correctness of PDM controller in the three phase full-bridge high frequency link converter system are investigated. And system designs on PDM converter based on ARM controller are given. The study results show that PDM control theory can be realized and used in many fields such as novel aviation power, UPS and hybrid electric vehicle with small size and light weight of power supply requirements.