To obtain low ac line current THD, the passive techniques described in the previous chapter rely on low-frequency transformers and/or reactive elements. The large size and weight of these elements are objectionable in many applications. This chapter covers active techniques that employ converters having switching frequencies much greater than the ac line frequency. The reactive elements and transformers of these converters are small, because their sizes depend on the converter switching frequency rather than the ac line frequency.
获得足够低的网络测试THD,有两种方法：无源方法和有源方法。前一章是通过无源设备实现低频传输函数，导致无源设备体积特别大，无法在实际应用中实现。本章将引入有源控制技术，并通过电源设备在高频开关状态下工作THD由于无源器件的体积和频率平方负相关，因此使用的无源器件会减少很多。
Instead of making do with conventional diode rectifier circuits, and dealing after-the-fact with the resulting low-frequency harmonics, let us consider now how to build a rectifier that behaves as ideally as possible, without generation of line current harmonics. In this chapter, the properties of the ideal rectifier are explored, and a model is described. The ideal rectifier presents an effective resistive load to the ac power line; hence, if the supplied ac voltage is sinusoidal, then the current drawn by the rectifier is also sinusoidal and is in phase with the voltage. Converters that approximate the properties of the ideal rectifier are sometimes called power factor corrected, because their input power factor is essentially unity [244].
传统的二极管整流器通过无源滤波器减少电流谐波。现在我们考虑建立一个理想的整流器，不会产生电流谐波。本章主要探索理想整流器的特点，并建立了描述他的模型。理想的整流器相当于电网的等效电阻负载；因此，如果电网电压为正弦，则从电网吸收的等效负载的电流也为正弦，电流相位与电网相同。这种变流器通常被称为他PFC,因为它是单位功率因数。
The boost converter, as well as a variety of other converters, can be controlled such that a near-ideal rectifier system is obtained. This is accomplished by control of a high-frequency switching converter, such that the ac line current waveform follows the applied ac line voltage. Both single-phase and three-phase rectifiers can be constructed using PWM techniques. A typical dc power supply system that is powered by the single-phase ac utility contains three major power-processing elements. First, a high-frequency converter with a wide-bandwidth input current controller functions as a near-ideal rectifier. Second, an energy storage capacitor smooths the pulsating power at the rectifier output, and a low-bandwidth controller causes the average input power to follow the power drawn by the load. Finally, a dc–dc converter provides a wellregulated dc voltage to the load. In this chapter, single-phase rectifier systems are discussed, expressions for rms currents are derived, and various converter approaches are compared.
上述理想整流器可以控制各种变换器。电流跟踪电网电压是通过高频打开和关闭开关管来实现的。可以使用单相和三相整流器PWM技术构建。单相整流器有三个主要的功率处理单元，一个是高带宽输入电流控制器，旨在完成理想的整流，但能量存储电容器平滑输出电压，低带宽控制器是负载消耗的平均输入功率；三是稳定的直流电压。本章讨论单相整流系统，推导rms 表达电流，比较各种转换器方法。 The techniques developed in earlier chapters for modeling and analysis of dc–dc converters are extended in this chapter to treat the analysis, modeling, and control of low-harmonic rectifiers. The CCM models of Chap. 3 are used to compute the average losses and efficiency of CCM PWM converters operating as rectifiers. The results yield insight that is useful in power stage design. Several converter control schemes are known, including peak current programming, average current control, critical conduction mode control, and nonlinear carrier control. Ac modeling of the rectifier control system is also covered。
本章扩展了前一章介绍的建模和分析技术，以分析、建模和控制低谐波整流器。CCM 该模型用于计算平均损失和效率，这表明它对功率级设计非常有用。峰值电流控制、平均电流控制、临界导通控制和非线性载波控制等控制方法很多。最后，建立了变换器的交流模型。