针对太阳电池的输出特性随环境变化的特点,为提高电池的输出功率和系统效率,提出一种基于固定电压法的太阳电池最大功率点跟踪(maximum power point tracker,MPPT)控制芯片的设计。其特点是采用模拟电路集成实现,具有结构简单、成本低、性能稳定等特点。芯片在1.5μmBCD(Bipolar-CMOS-DMOS)工艺下设计实现,仿真验证和芯片测试结果表明,芯片性能与设计预期基本相符。采用该芯片的太阳能供电系统能够实时跟踪太阳电池的最大功率点。
This paper presents a multi-mode control scheme for a soft-switched flyback converter to achieve high efficiency and excellent load regulation over the entire load range. At heavy load, critical conduction mode with valley switching (CCMVS) is employed to realize soft switching so as to reduce turn-on loss of power switch as well as conducted electromagnetic interference (EMI). At light load, the converter operates in discontinuous conduction mode (DCM) with valley switching and adaptive off-time control (AOT) to limit the switching frequency range and maintain load regulation. At extremely light load or in standby mode, burst mode operation is adopted to provide low power consumption through reducing both switching frequency and static power dissipation of the controller. The multi-mode control is implemented by an oscillator whose pulse duration is adjusted by output feedback. An accurate valley switching control circuit guarantees the minimum turn-on voltage drop of power switch. The pro-totype of the controller IC was fabricated in a 1.5-μm BiCMOS process and applied to a 310 V/20 V, 90 W flyback DC/DC converter circuitry. Experimental results showed that all expected functions were realized successfully. The flyback converter achieved a high efficiency of over 80% from full load down to 2.5 W, with the maximum reaching 88.8%, while the total power consumption in standby mode was about 300 mW.
To meet the demands for different supply voltage levels on SOC required by digital modules like CPU core and analog modules,a novel dual-output charge pump is proposed. The charge pump can output a step-up and a step-down voltage simultaneously with a high driving capability. The multiple gain pair technique was introduced to enhance its efficiency. The proposed co-use technology for capacitors and switch arrays reduced its cost. The charge pump was designed and fabricated in a TSMC 0.35μm mixed-signal CMOS process. A group of analytical equations were derived to model its static characteristics. A state-space model was derived to describe its small-signal dynamic behavior. Analytical predictions were verified by Spectre simulation and testing. The consistency of simulated results as well as test results with analytical predictions demonstrated the high precision of the derived analytical equations and the developed models.
