Analog circuit and method for detecting wire breaking of displacement sensor LVDT
A technology of displacement sensor and analog circuit, which is applied in the direction of measuring electric variables, measuring current/voltage, instruments, etc. It can solve problems such as hidden troubles, lack of disconnection detection function, and inability to correctly and timely judge signal failures, etc. The method is simple reliable effect
Active Publication Date: 2011-09-28
GUODIAN NANJING AUTOMATION
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Problems solved by technology
[0005] However, due to the limitations of the existing analog circuit conversion methods, these two methods do not have the function of disconnection detection, and cannot correctly and timely judge the signal failure situation in the event of wiring failure or LVDT failure.
In some applications with high reliability requirements, such as liquid level measurement of DEH system, etc., when the signal is disconnected, it cannot be judged in time and accurately, which will cause a great potential failure
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[0030] figure 1 The principle of LVDT measurement is explained. Add a certain frequency of alternating current to the primary coil P of LVDT. When the LVDT iron core moves, the output voltage difference between the two secondary coils has a linear relationship with the displacement of the iron core. When the iron core is in the middle of the secondary windings S1 and S2, E1=E2, the output voltage is 0. When the iron core moves toward S1, E1>E2; when the iron core moves toward S2, E2>E1. Therefore, the output voltage can be collected and converted according to the linear relationship between the output voltage and the displacement of the iron core to obtain the displacement of the iron core.
[0031] figure 2 The measurement principle of the commonly used LVDT transmitter is explained. The LVDT measurement circuit can also be directly replaced by the LVDT signal adjustment system AD598. OSC is an excitation signal of a certain frequency, and the alternating current is appl...
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The invention discloses an analog circuit for detecting the wire breaking of a displacement sensor LVDT, which comprises a displacement sensor LVDT, wherein a primary coil of the displacement sensor LVDT is connected with an excitation signal source. The analog circuit for detecting the wire breaking of the displacement sensor LVDT is characterized in that the output ends of the secondary coils of the displacement sensor LVDT are respectively connected with a test signal and are respectively connected with a multi-channel selection switch through a filter and rectifier circuit, and predetermined different groups and combinations of wire breaking voltages which are output when an LVDT is disconnected are simultaneously connected with the multi-channel selection switch; the two output end voltages of the secondary coils of the LVDT are respectively combined with a group of comparison voltages to be connected with each comparator, and each comparator is connected with the output control end of the multi-channel selection switch through an arithmetic logic OR unit, and the multi-channel selection switch is simultaneously connected with a servo amplifier. The invention can directly achieve the detection of wire breaking state only by a hardware circuit, and the method is simple and reliable.
Description
technical field [0001] The invention relates to a method for detecting disconnection of a displacement sensor LVDT in an industrial control system, which is specifically applied to the position measurement of some industrial control systems with high reliability requirements, such as the liquid level measurement of a digital electro-hydraulic control system (DEH), and belongs to Power system automatic control technology field. Background technique [0002] LVDT (Linear Variable Differential Transformer) is the abbreviation of Linear Variable Differential Transformer. The working principle is simply a movable iron core transformer. It consists of a primary coil, two secondary coils, iron core, coil bobbin, casing and other components. When the iron core moves from the middle to both sides, the difference between the output voltages of the two secondary coils is linear with the movement of the iron core. LVDT is mainly used to measure the position signal on a straight line ...
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IPC IPC(8): G01B7/02G01R19/165
Inventor 王丹麟
Owner GUODIAN NANJING AUTOMATION