剩余电压检测的关键技术研究

The Research on Key Technology of Testing Residual Voltage

剩余电压是指用插头连接电源的设备在拔掉插头的瞬时,由设备内部的储能元件产生的存在于插头上各插脚之间的残余电压。若人体触摸到插头且该电压大于某一限值,就会产生触电危险。制定剩余电压、剩余能量的限值是为了保护患者、操作者或其他人员的人身安全,防止在断电瞬间触及带电部件而发生危险。故准确地检测医疗设备的剩余电压值具有十分重要的意义。本文解决了剩余电压测量的一个关键技术问题,即设计一个零电位检测的关键电路,与可调延时设计配合能使设备在交流峰值处准确断电。这种峰值时刻断电检测系统,用于一种单片机控制的新型剩余电压测量装置,该装置将具有较好的重复性、稳定性,以克服现有的剩余电压测试仪器不能准确地在峰值处断电、测试重复性差等缺陷。该检测电路结构简单,性能稳定,能够在整流波过零的时刻可靠地产生宽度很窄的触发脉冲。采用可调延时设计,能够解决元器件带来的时延。

The residual voltage is the voltage remained between the plug pins immediately after the plug of the device disconnected from the power supply, or the voltage remained in the energy storage components such as capacitors immediately after the electrical equipment disconnected with the power grid. When someone touchs the plug with the residual voltage greater than a certain value, there will be a risk of electric shock. Setting a limit value for the residual voltage and the residual energy is aimed at guaranteeing the security for the patients, operators or others by preventing them from the danger of electric shock when they touch the charged components. Therefore accurate measurement of the residual voltage of the medical device is of significant importance. This paper provides a solution to a key technologic problem, that is, to shutoff the power supply at the peak accurately, which can be accomplished by designing a key zero-crossing detection circuit combined with an adjustable delay circuit. This new residual voltage measurement device has good repeatability and stability, and can overcome the existing devices＇ deficiencies such as inability to shutoff the power supply at the peak accurately, limitation of the testing impedance and inability to display the discharging curve. The zero-crossing detection circuit has the advantages of simple structure, stable performance, can be rectified wave zero moment reliably produce a very narrow width of trigger pulse. The adjustable delay design can solve the time delay for components.