Highly efficient linear power amplifier for driving fast slew rate capacitive loads
Highly efficient linear power amplifier for driving fast slew rate capacitive loads
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用于驱动快速压摆率电容负载的高效线性功率放大器
DOI：
10.1109/apec.2017.7930997
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
J. Cobos
中科院分区：
文献类型：
--
作者：
M. Vasić;E. Boere;Ó. García;P. Alou;J. Oliver;J. Eltze;J. Cobos
现代喷墨打印机能够将数百万个微小的墨滴精确地放置在纸张，织物甚至陶瓷上以创建图像。喷墨打印的压电技术采用晶体，每当向压电换能器施加电压脉冲时，晶体就会弯曲。代表性的打印头配置可以采用单个功率放大器（PA）来驱动多达1024个喷嘴，其中等效负载大约为100 nF。用于驱动喷墨打印机头的最简单的电压形式是梯形波形，其具有受控的振幅和斜坡。由于所需的电压形状，通常采用线性功率放大器（B类、AB类），为了电压脉冲的质量而牺牲效率。在本文中，我们提出了一种高效的解决方案，PA驱动喷墨头的电压脉冲高达130 V，压摆率为45 V/us，快至110 kHz。该解决方案基于包络跟踪方法，即，线性PA由变化的电源电压供电，并且以这种方式避免线性PA中的高功率损耗，同时保持输出电压的良好特性。由于极快的转换速率（45 V/us）和必须提供给负载的非常高的瞬时功率（高达800 W），因此使用多电平转换器来实现变化的电压。实验结果表明，采用该方法可以使系统的损耗降低50%以上。
The modern Inkjet printer is able to place millions of tiny ink droplets precisely on a paper, fabric or even ceramic to create an image. The piezoelectric technique of inkjet printing employs a crystal that flexes whenever a voltage pulse is applied to the piezo transducer. A representative printing head configuration might employ a single Power Amplifier (PA) to drive up to 1024 nozzles with an equivalent load of approximately 100nF. The simplest voltage form that is used for driving the ink jet printer head is a trapezoidal waveform, which has controlled amplitude and ramps. Because of the needed voltage shape, linear power amplifiers (class B, AB) are normally employed, sacrificing efficiency for the quality of the voltage pulse. In this paper we present a highly efficient solution for the PA that drives an ink jet head with voltage pulses as high as 130V with slew rates of 45V/us and as fast as 110 kHz. The solution is based on an Envelope Tracking approach, i.e. the linear PA is supplied by a varying supply voltage and in that way avoiding high power losses in the linear PA, while preserving good characteristics of the output voltage. Due to the extremely fast slew rate (45V/us) and very high instantaneous power that must be supplied to the load (up to 800W), the varying voltage is implemented using a multilevel converter. By using the proposed solution the power losses can be cut down as much as 50% as it is shown by experimental results.