【作者】 杨前；

【导师】 马宪民；

【作者基本信息】 西安科技大学 ， 控制理论与控制工程， 2003， 硕士

【摘要】 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。当交-交变频器的输入频率非常高，通常为20KHz时，为了在零电压条件下实现逆变器开关管的通断，变换器的开关时刻必须选择在高频交流电压脉冲为零时，这意味着变换器开关时刻在时间轴上成为不连续的点，而常规的硬开关PWM变换器是将开关时刻选择在任意时刻。因此，开关时刻在时间轴上仅为离散点的高频交-交变频器采用常规的PWM调制策略肯定不是最优的方案。本文阐述的高频交流脉冲密度调制(PDM)的控制策略能够较容易地将高频交流信号低失真地合成幅值和频率变换的低频信号。PDM技术的特点是将高频交流脉冲信号的一个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，使得两个曲线包围的面积可以基本维持平衡。这个面积的平衡导致输出半个周期脉冲的密度由参考信号的幅值来控制。根据交流电机在恒转矩区和恒功率区的特性，结合零电压开关技术，分别给出相应的脉宽调制控制(PWM)方式和方波控制方式下的高频交流脉冲密度调制变频器的数学模型，电压和电流的谐波分析以及输出电压、电流和功率的仿真波形。仿真结果表明，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，特别适合于作未来电动汽车的高频交流驱动系统。更多还原

【Abstract】 High-frequency link power converters are receiving increasing attention. When the input frequency of AC-AC converter is quite high, such as 20KHz or above, in order to make sure the converter switching action is restricted to the zero crossing point of the link voltage, the switching cycle becomes discrete pulse spectrums, however, the conventional PWM converters are ruled out because they would fail either to the efficiency or the low-distortion criteria. The three-phase high-frequency AC pulse density modulation (PDM) converter, which is proposed in this paper, can efficiently synthesize low-distortion variable frequency variable amplitude low frequency voltage signals from the fixed-frequency voltage of the high frequency link. The main advantage of this PDM converter is that one half-cycle of the high-frequency voltage becomes the basic unit of synthesis of the low-frequency signals. The area difference under the reference signal and synthesized signal and the next pulse with the polarity will reduce this difference. With this feedback, the density of the half-cycle pulses in the synthesized output is modulated by the amplitude of the reference signal. According to the mechanism characteristics of the AC motor, with zero-voltage switching technology, the PDM converter mathematical models both the PWM and rectangular wave control mode are given in this paper. And the voltage and current harmonic analysis and the simulation waveforms of the output voltage, current and power are also described respectively. The simulation results prove that the PDM control theory can be fit for the high frequency AC link power conversion distribution system, especially be suitable for the electric driver system of the electric vehicle in the future.更多还原