Alternating current power failure detection method and warning circuit
A power failure alarm, alternating current technology, applied in the direction of measuring current/voltage, measuring device, measuring electrical variables, etc., can solve the problems of slow response, insufficient AC voltage detection ability, difficult power failure detection, etc., to achieve accurate results.
Active Publication Date: 2010-11-10
SHENZHEN GOLD POWER TECH
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Problems solved by technology
One of the disadvantages of this method is that the response is slow, because there is a filter capacitor in the DC detection circuit, and there is also a voltage drop time; the second is that when the AC voltage range is wide, such as 85V to 300V, the upper and lower voltage limits are very different, which is difficult to detect. Power-down detection by setting the threshold voltage
How to provide a method to overcome the inadequacy of the existing AC power failure detection method for wide-range AC voltage detection is an urgent problem in the industry
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[0022] In order to make the purpose, features and beneficial effects of the present invention more comprehensible, a preferred embodiment will be cited below, and the technical solution will be described in detail in conjunction with the accompanying drawings.
[0023] The power-down alarm circuit of the present invention includes a rectifier, a limiter circuit, a sampling filter circuit and a processor, the rectifier rectifies an AC power supply into a cosine pulse voltage, and the cosine pulse voltage is shaped into a trapezoid by the limiter circuit The pulse voltage is then transmitted to the processor, and the processor also performs voltage sampling on the cosine pulse voltage through the sampling filter circuit.
[0024] refer to figure 1 , in this preferred embodiment, the rectifier is a bridge rectifier BR, the processor is an MCU chip U1, and in this preferred embodiment, the MCU chip U1 is a PIC12F675 chip, the limiting circuit and sampling The filter circuit inclu...
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The invention discloses an alternating current power failure detection method, which comprises the following steps: a. rectifying alternating current into cosine pulse voltage; b. detecting the pulse voltage in the detection period; and c. judging whether the voltage jumping edge occurs or not, returning the step b if so, and determining the power failure of the alternating current voltage if not, wherein in the step b, the cosine pulse voltage firstly carries out amplitude limiting processing to be shaped into trapezoidal pulse voltage, and then, the detection is carried out. The alternatingcurrent power failure detection method provided by the invention judges the power failure through detecting the phase of the alternating current. Because the phase fluctuation of the alternating current is relatively little, the influence on the detection results by the wide voltage range can be avoided through the phase detection, and the alternating current power failure information can be accurately obtained.
Description
technical field [0001] The invention relates to a power failure detection method, in particular to an AC power failure detection method and an alarm circuit. Background technique [0002] In modern communication equipment, when there is an alternating current (AC) power failure, the direct current (DC) output in the system can be maintained for a period of time in order to save important data in non-volatile memory , the maintenance time generally lasts tens of milliseconds to one hundred milliseconds, and the power for this maintenance time is usually provided by the filter capacitor in the circuit. In order to reduce the impact of AC power failure on the system, in addition to having a large enough capacitance to obtain a long enough maintenance time, it is also necessary to detect the occurrence of power failure as soon as possible and issue a power failure in time when the AC power failure occurs. Alarm. [0003] The traditional AC power-off detection method is general...
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IPC IPC(8): G01R19/165G01R25/00
Inventor 马新国
Owner SHENZHEN GOLD POWER TECH