恒流负载驱动电路失效抑制技术研究

发布时间：2018-06-19 12:40

本文选题：失效抑制技术 + 递进触发控制　；参考：《电子科技大学》2016年博士论文

【摘要】：本文针对恒流负载驱动电路失效抑制技术开展研究,所谓“失效”包涵两个方面:一是由于使用过程中损坏导致功能失效,二是由于驱动电路性能指标不足,导致无法满足应用要求。失效抑制技术则是在分析其失效产生原因的基础上,提出新的方法和技术,改善失效电路的性能,消除失效。发光二极管(Lighting Emitting Diode,LED)作为第三代固态光源,有着众多的优点和非常广泛的应用,在此作为典型恒流负载进行研究。LED驱动电路发展已经较为成熟,但随着LED本身的发展以及应用范围扩大,或者原有的应用市场的系统性能指标提升,使得驱动电路也一直在发展。国际上以TI和奥地利微电子等公司的产品为代表,如将LED电流调节精度和匹配度控制到1%以下,并具有良好的适用性。只有将驱动电路的性能指标和可靠性提高到国际一流产品相同,才能为其在高端市场的终端设备的应用开拓道路,完成产品市场突围。因此,本文的研究具有明显的市场前景和重要的技术意义。本文通过分析功率MOSFET及其驱动电路工作原理,进行一个方法和两项技术的创新研究:提出基于沟道宽度变化的di/dt递进触发控制方法;根据同步功率管的工作时序,提出电压自跟随控制技术;并基于电容电荷存储功能,提出占空比跟随的频率转换技术。其主要创新点如下:(1)通过分析功率MOSFET导通电流与其导通沟道宽度之间的关系,提出基于沟道宽度变化的di/dt递进触发控制方法,建立MOSFET开启与关断工作状态转换时其di/dt与沟道时变函数W(t)之间的控制关系,完成递进触发控制方法的理论分析。通过对W(t)函数的离散化处理,将此方法用于控制功率MOSFET的开关过程,实现功率MOSFET的沟道宽度递进调整,使其导通电流呈现递进式增加或者减少,达到功率MOSFET开启与关断瞬间di/dt降低的效果。通过流片测试结果证明,在相同测试条件,功率MOSFET关断di/dt降低超过50%,开启di/dt减小到原来的79%。(2)基于同步升压转换器功率转换原理,分析了功率器件开关状态转换瞬间其工作状态与各点电压波形的关系,提出了一种电压自跟随控制技术。此技术通过检测节点SW电压判断功率管工作状态,根据不同工作条件自动控制同步功率管开启时间,在确保无穿通风险条件下,极大的缩短了死区时间,有效的降低SW节点电压过冲,提高其转换效率。基于此技术的功率转换控制电路应用于同步升压转换器的设计,其流片测试结果表明,死区时间内的SW峰值电压降低超过40%,轻载效率最大提高约3%。(3)基于常规占空比跟随频率转换技术误差产生原因的分析,提出电容电荷存储频率转换技术,此技术将单计数周期的时间误差转换为电荷存储于电容,并叠加到下一计数周期,实现单周期计数时间误差自动消除,获得更为精确的占空比跟随指标。将此技术应用于LED驱动的直接PWM调光控制电路,经过流片测试验证,其输入信号频率在200Hz到10KHz范围内,转换后输出信号频率为1KHz,其占空比跟随误差小于1%。(4)通过对LED驱动电路的电流调节误差产生原因的分析,改进电流调节技术。确定模拟调节的误差由控制回路中运算放大器的失调电压而引起,通过分析模拟调节的原理,采用数字自校准技术将模拟调光的最小调节范围降低至1%的量产目标。而直接PWM调光方面,则采用改进的自动调零技术与双开关技术相结合架构,将其LED调光精度提高至1%以下,同时多通道电流输出匹配度小于±0.6%,达到与国际一流产品的参数指标。
[Abstract]:In this paper, the failure suppression technology of constant current load driving circuit is studied. The so-called "failure" includes two aspects: first, the failure of the use process leads to the failure of the function, and the two is due to the lack of performance indicators of the driving circuit, which can not meet the requirements of the application. New methods and techniques are proposed to improve the performance of the failure circuit and eliminate the failure. Lighting Emitting Diode (LED), as the third generation solid-state light source, has many advantages and very wide applications. As a typical constant current load, the development of.LED drive circuit is more mature, but with the development of LED itself As well as the expansion of the application scope and the improvement of the system performance index of the original application market, the drive circuit has been developing. The products of TI and Austria microelectronics are represented internationally, such as controlling the accuracy and matching degree of the LED current regulation to less than 1%, and having good applicability. As the standard and reliability are improved to the same international first-class products, it can open the road for the application of terminal equipment in the high-end market and complete the breakthrough of the product market. Therefore, the research of this paper has obvious market prospects and important technical significance. By analyzing the working principle of power MOSFET and its driving circuit, a method and two are carried out in this paper. Innovative research of item technology: a di/dt progressive trigger control method based on channel width change is proposed. Voltage self following control technology is proposed based on the working timing of synchronous power pipe. Based on the capacitance charge storage function, the frequency conversion technology of duty cycle following is proposed. The main innovation points are as follows: (1) through the analysis of power MOSFET conduction The relationship between the flow and the width of the channel channel is proposed. The di/dt progressive trigger control method based on the channel width change is proposed. The control relationship between the di/dt and the channel time-varying function W (T) is established when the MOSFET opening and the turn off working state is converted, and the theory analysis of the progressive trigger control method is completed. By discrete processing of the W (T) function, this method will be used. The method is used to control the switching process of the power MOSFET, realizing the progressive adjustment of the channel width of the power MOSFET, making the conduction current increasing or decreasing, reaching the effect of di/dt decreasing at the moment of power MOSFET opening and closing. The result of the flow sheet test proves that the power MOSFET turn off di/dt is reduced by more than 50% in the same test condition. The starting di/dt is reduced to the original 79%. (2) based on the principle of the power conversion of the synchronous boost converter. The relationship between the working state of the switch state and the voltage waveform of each point is analyzed. A voltage self following control technique is proposed. This technique is used to determine the working state of the power pipe by detecting the SW voltage of the node, according to the different working bars. The device automatically controls the opening time of the synchronous power pipe, greatly shortens the dead time, effectively reduces the SW node voltage overshoot and improves the conversion efficiency. The power conversion control circuit based on this technology is applied to the design of the synchronous boost converter. The flow sheet test results show that the SW peak in the dead time is found. The value voltage is reduced by more than 40% and the light load efficiency is increased by about 3%. (3). Based on the analysis of the cause of the conventional duty cycle frequency conversion error, the capacitance charge storage frequency conversion technology is proposed. This technique converts the time error of the single counting period to the charge stored in the electrical capacity and superposes the next counting period to realize the single cycle count. The time error is automatically eliminated and a more accurate duty ratio following index is obtained. This technology is applied to the direct PWM dimming control circuit driven by LED. The input signal frequency is within the range of 200Hz to 10KHz after the flow sheet test, and the frequency of the output signal is 1KHz after the conversion, and the duty cycle error is less than 1%. (4) through LED drive circuit. The analysis of the cause of current adjustment error and the improvement of the current adjustment technology. It is determined that the error of the analog adjustment is caused by the imbalance voltage of the operational amplifier in the control loop. By analyzing the principle of analog adjustment, the minimum adjustment range of the simulated dimming is reduced to 1% of the mass production target by the digital self calibration technique. By combining the improved automatic zero switching technology and the dual switch technology, the LED dimming precision is raised to less than 1%, and the matching degree of the multi channel current output is less than 0.6%, so as to reach the parameters of the international first-class products.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN386

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