Isolation switching system and method for array capacitance signal redundancy acquisition

Abstract

The invention relates to the technical field of capacitance type sensor redundancy measurement, in particular to an isolation switching system and method for array capacitance signal redundancy collection. The switching control module is arranged to convert a switching control switching signal into a driving current signal and drive opening and closing of the isolation module, switching of a capacitance signal channel is achieved, meanwhile, the isolation module is completely isolated from the collection module, the problem of unstable measurement caused by the collection module to the ground leakage current is solved, time-sharing connection is conducted through a time sequence switching signal, and the measurement accuracy is improved. According to the invention, acquisition is carried out one by one, physical isolation switching of capacitance signal arrays is realized, time-sharing acquisition is carried out through the acquisition module, the switching flexibility is improved, the requirements for the service life and reliability of frequent switching of capacitance acquisition signals are met, and physical isolation in the redundancy switching process is also met.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitive sensor redundancy measurement, and in particular to an isolation switching system and method for array capacitance signal redundancy acquisition. Background Art

[0002] Capacitive sensors are widely used in aerospace fields such as measuring pressure, fuel level, displacement, etc., and these fields require high-reliability measurement guarantees, that is, dual-redundancy measurement requirements are usually required: even if one channel fails to measure, the other channel can be backed up for testing to improve reliability. For other measurement signals, such as analog signals such as voltage, current or frequency, multiple high-impedance input measurement circuits can be connected to measure simultaneously, that is, the measurement acquisition of the main channel will not affect the measurement acquisition of the backup channel. Capacitive sensors usually use a capacitive bridge wall or excitation feedback capacitance-voltage or capacitance-frequency method. Either method requires an excitation to be applied to the capacitive sensing signal, and a return signal is fed back in the form of current, voltage, or frequency. This determines that capacitive sensors cannot be connected to two or more measurement circuits for simultaneous measurement. So how to achieve dual-redundancy measurement? At present, the common practice is to realize the single-pole double-throw function through an analog switch chip. The advantage of this method is that the number of switching times is not limited. The disadvantage is that the analog switch chip uses CMOS tube technology inside, and the saturation and cut-off states of the transistor are controlled in sections. There must be leakage current when the signal is disconnected, and there is equivalent contact resistance when the signal is connected, that is, it is impossible to physically connect and disconnect. Although the optocoupler device can achieve signal isolation, it cannot switch and transmit signals, which is not applicable to the technical route of redundant acquisition of capacitor signals. Therefore, it is urgent to find a method or circuit that can realize both the switching of array capacitor signals and the isolation and conversion of redundant acquisition. Summary of the invention

[0003] The invention aims at the problem that the existing capacitance signal redundancy acquisition method cannot realize the switching of capacitance signal and the isolation and conversion of redundancy acquisition at the same time, and proposes an isolation switching system and method for array capacitance signal redundancy acquisition; by converting the switching control switching signal into a driving current signal, driving the opening and closing of the isolation module, the switching of the capacitance signal channel is realized, and at the same time, it is completely isolated from the acquisition module, reducing the measurement instability caused by the ground leakage current of the acquisition module, and through the timing switching signal, time-sharing connection is performed, and acquisition is performed one by one, so as to realize the physical isolation switching of the capacitance signal array, and at the same time, time-sharing acquisition is performed through the acquisition module, so as to improve the switching flexibility, meet the life and reliability requirements of the frequent switching of the capacitance acquisition signal, and also meet the physical isolation in the redundancy switching process.

[0004] The specific implementation contents of the present invention are as follows: An isolation switching system for array capacitor signal redundancy acquisition is connected to the array capacitor; it includes a switching control module, an isolation module, and an acquisition module; The input end of the isolation module is connected to the output end of the array capacitor, and the output end of the isolation module is connected to the input end of the acquisition module; The input end of the switching control module is connected to the host computer, and the output end of the switching control module is connected between the output end of the array capacitor and the input end of the switching control module; The input end of the acquisition module is connected to the host computer, and the output end outputs a capacitance signal; The switching control module is used to convert the switching control signal obtained from the host computer into a driving current signal; The isolation module is used to switch the capacitance signal obtained from the array capacitance to the corresponding acquisition channel according to the driving current signal; The acquisition module is used to acquire capacitance signals acquired from multiple acquisition channels in a time-sharing manner according to a timing switching signal acquired from a host computer.

[0005] In order to better implement the present invention, further, the switching control module includes a filtering unit and an isolation driving unit; The input end of the filter unit inputs a switching control signal, and the output end is connected to the input end of the optical coupling isolation unit; The output end of the isolation driving unit is connected to the input end of the isolation module.

[0006] In order to better implement the present invention, further, the filtering unit includes a resistor R321 and a capacitor C306; One end of the resistor R321 is input with a switching control signal, and the other end is connected to the first input end of the isolation driving unit; One end of the capacitor C306 is connected between the output end of the resistor R321 and the first input end of the isolation driving unit, and the other end of the capacitor C306 is connected between the second input end of the isolation driving unit and the ground.

[0007] In order to better implement the present invention, further, the isolation driving unit includes a resistor R322, an optical coupler, a resistor R306, and a transistor Q1; The input end of the resistor R322 is connected between the output end of the resistor R321 and the capacitor C306, and the output end of the resistor R322 is connected to the first input end of the optical coupler; The second input end of the optical coupler is connected between the capacitor C306 and the ground end, the first output end of the optical coupler is connected to the power supply VDD through the resistor R306, and the second output end of the optical coupler is connected to the base of the transistor Q1; The emitter of the transistor Q1 is connected to the ground, and the collector of the transistor Q1 is connected to the input end of the isolation module.

[0008] In order to better implement the present invention, further, the isolation unit includes a plurality of relay units; The input ends of the plurality of relay units are connected to the output end of the array capacitor and the collector of the transistor Q1; The output ends of the plurality of relay units are connected to the input end of the acquisition module.

[0009] In order to better implement the present invention, further, the acquisition module includes multiple analog switch chips and multiple capacitance signal acquisition circuits; The input ends of the multiple analog switch chips are connected to the output ends of the multiple relay units, the controlled ends of the multiple analog switch chips input timing switching signals, and the output ends of the multiple analog switch chips are connected to the multiple capacitance signal acquisition circuits.

[0010] In order to better implement the present invention, further, the analog switch chip is an ADG408 chip.

[0011] Based on the above-mentioned AA, in order to better realize the present invention, further, an isolation switching method for array capacitor signal redundancy acquisition is proposed, which is implemented based on the above-mentioned isolation switching system for array capacitor signal redundancy acquisition; it is characterized in that the switching control signal obtained from the host computer is first converted into a driving current signal; then the capacitance signal obtained from the array capacitor is switched to the corresponding acquisition channel according to the driving current signal; finally, the capacitance signal obtained from multiple acquisition channels is collected in time-sharing according to the timing switching signal obtained from the host computer.

[0012] The present invention has the following beneficial effects: (1) The present invention combines a relay isolation switch group with an analog switch chip, and uses an external unit to send a switching control level. The logic level is converted into a driving current through a switching control circuit composed of an optocoupler isolation device and a transistor drive amplifier circuit to drive the relay isolation switch group circuit to "open" and "close", thereby achieving complete switching of the capacitor signal from channel A to channel B. At the same time, the channel A acquisition module is completely isolated from the capacitor signal, reducing the measurement instability caused by the ground leakage current and equivalent resistance of the analog switch chip.

[0013] (2) The capacitor signal array after passing through the relay isolation switch group of the present invention is connected to the analog switch chip for time-sharing connection, and is connected one by one to the capacitor signal acquisition circuit for acquisition, thereby realizing the physical isolation switching of the capacitor signal array, and at the same time, time-sharing acquisition is performed through the analog switch chip; compared with the existing capacitor analog switch chip switching, the influence of ground leakage current and equivalent resistance on capacitor measurement is solved. At the same time, compared with the full relay isolation switching switch method, the present invention improves the switching flexibility, which not only meets the life and reliability requirements of frequent switching of capacitor acquisition signals, but also meets the physical isolation during the redundancy switching process. At the same time, the CPU can control the switching control circuit to achieve flexible configuration and switching functions, that is, it can flexibly choose whether to switch the relay isolation switch group or the analog switch chip, which can be used for different needs of capacitor signal acquisition. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic block diagram of the structure of the isolation switching system for array capacitance signal redundancy acquisition provided by the present invention.

[0015] Figure 2 A schematic block diagram of the overall structure of an isolation switching system for array capacitance signal redundancy acquisition provided by an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the control switching circuit structure provided by the present invention.

[0017] Figure 4 This is a schematic diagram of the circuit structure of the isolation module provided by the present invention.

[0018] Figure 5 This is a schematic diagram of the peripheral circuit structure of the analog switch chip provided by the present invention. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] Embodiment 1: This embodiment proposes an isolation switching system for array capacitance signal redundancy acquisition, such as Figure 1 As shown, it is connected to the array capacitor; it includes a switching control module, an isolation module, and a collection module; The input end of the isolation module is connected to the output end of the array capacitor, and the output end of the isolation module is connected to the input end of the acquisition module; The input end of the switching control module is connected to the host computer, and the output end of the switching control module is connected between the output end of the array capacitor and the input end of the switching control module; The input end of the acquisition module is connected to the host computer, and the output end outputs a capacitance signal; The switching control module is used to convert the switching control signal obtained from the host computer into a driving current signal; The isolation module is used to switch the capacitance signal obtained from the array capacitance to the corresponding acquisition channel according to the driving current signal; The acquisition module is used to acquire capacitance signals acquired from multiple acquisition channels in a time-sharing manner according to a timing switching signal acquired from a host computer.

[0022] Working principle: In this implementation, a switching control module is set to convert the switching control switching signal into a driving current signal, drive the opening and closing of the isolation module, realize the switching of the capacitor signal channel, and completely isolate it from the acquisition module at the same time, reduce the measurement instability caused by the ground leakage current of the acquisition module, and realize the physical isolation switching of the capacitor signal array through time-sharing connection through the timing switching signal, and collect one by one, and realize the physical isolation switching of the capacitor signal array. At the same time, time-sharing collection is performed through the acquisition module, which improves the flexibility of switching, which not only meets the life and reliability requirements of frequent switching of capacitor acquisition signals, but also meets the physical isolation during the redundancy switching process.

[0023] like Figure 2As shown, the input of this embodiment is a capacitance signal channel array. In theory, unlimited capacitance channels can be connected as long as the interface of the CPU control circuit is sufficient. The capacitance signal of each channel is divided into two-level signals. The two-level signals are respectively connected to the same relay isolation circuit, and then the two capacitance signal channels are separated and output. The high and low levels sent by the switching control circuit determine whether the capacitance signal enters the acquisition module A or the acquisition module B for acquisition and switching. In addition, by analogy, if there are multiple capacitance signals, from Figure 2 It can be seen from the principle schematic diagram that multiple signals are connected to the relay isolation switch group at the same time, and the CPU sends a control level to switch multiple groups of capacitor signals to the capacitor signal acquisition module B for acquisition. First, the analog switch chip of module B is connected, and the time-sharing switching control logic of the internal CPU is used to realize the time-sharing acquisition of multiple capacitor signals.

[0024] Embodiment 2: This embodiment is based on the above embodiment 1. Figure 3 As shown, a specific embodiment is used to illustrate the specific structure of the switching control module.

[0025] The switching control module includes a filtering unit and an isolation driving unit; The input end of the filter unit inputs a switching control signal, and the output end is connected to the input end of the optical coupling isolation unit; The output end of the isolation driving unit is connected to the input end of the isolation module.

[0026] The filtering unit includes a resistor R321 and a capacitor C306; One end of the resistor R321 is input with a switching control signal, and the other end is connected to the first input end of the isolation driving unit; One end of the capacitor C306 is connected between the output end of the resistor R321 and the first input end of the isolation driving unit, and the other end of the capacitor C306 is connected between the second input end of the isolation driving unit and the ground.

[0027] The isolation driving unit includes a resistor R322, an optical coupler, a resistor R306, and a transistor Q1; The input end of the resistor R322 is connected between the output end of the resistor R321 and the capacitor C306, and the output end of the resistor R322 is connected to the first input end of the optical coupler; The second input end of the optical coupler is connected between the capacitor C306 and the ground end, the first output end of the optical coupler is connected to the power supply VDD through the resistor R306, and the second output end of the optical coupler is connected to the base of the transistor Q1; The emitter of the transistor Q1 is connected to the ground, and the collector of the transistor Q1 is connected to the input end of the isolation module.

[0028] Working principle: This embodiment realizes the isolation, switching and time-sharing acquisition of array capacitance signals, such as Figure 2 As shown, the relay isolation switch group is combined with the analog switch chip, and the switching control level is sent by the external CPU unit. The logic level is converted into a driving current through a switching control circuit composed of an optocoupler isolation device and a transistor drive amplifier circuit to drive the relay isolation switch group circuit to "open" and "close", so as to achieve the complete switching of the capacitance signal from channel A to channel B. At the same time, the channel A acquisition module is completely isolated from the capacitance signal, reducing the measurement instability caused by the ground leakage current and equivalent resistance of the analog switch chip. The capacitance signal array after the relay isolation switch group is connected to the analog switch chip for time-sharing connection, and is connected to the capacitance signal acquisition circuit one by one for acquisition, thereby realizing the physical isolation switching of the capacitance signal array, and at the same time, time-sharing acquisition is performed through the analog switch chip. Compared with the existing capacitor analog switch chip switching, this embodiment solves the influence of ground leakage current and equivalent resistance on capacitance measurement. At the same time, compared with the full relay isolation switching method, this embodiment improves the switching flexibility, which not only meets the life and reliability requirements of frequent switching of capacitor acquisition signals, but also meets the physical isolation during the redundancy switching process. At the same time, the CPU can control the switching control circuit to achieve flexible configuration and switching functions, that is, it can flexibly choose whether to switch the relay isolation switch group or the analog switch chip, which can be used for different needs of capacitor signal acquisition.

[0029] like Figure 3 As shown, the control switching circuit is the control input part of the principle schematic diagram. Resistors R321 and C306 form an RC filter circuit, and the parameters are adjustable. In view of the low switching frequency of the CPU switching control signal, the RC filter is mainly used to prevent signal jitter from causing false switching. Resistor R322 is a current limiting protection resistor. At the same time, according to the characteristics of the optocoupler, the resistor can adjust the current of the CPU switching control signal to ensure that the current signal above a threshold current can reliably and effectively open the optocoupler transmission. The resistance value of resistor R306 is 2K, and it is connected to the output circuit of the optocoupler through the 5V reference voltage VDDA5. According to the current transfer ratio of the selected optocoupler and the conduction voltage of the optocoupler, the voltage of the subsequent current drive amplifier 3DK9B is calculated, so that the transistor is in the conduction saturation region, thereby generating a drive current to drive the relay switch group of the next stage.

[0030] The other parts of this embodiment are the same as those of the above-mentioned embodiment 1, and thus will not be described in detail.

[0031] Embodiment 3: This embodiment is based on any one of the above embodiments 1 to 2. Figure 4 As shown, the specific structure of the isolation module is described with a specific embodiment.

[0032] The isolation unit includes a plurality of relay units; The input ends of the plurality of relay units are connected to the output end of the array capacitor and the collector of the transistor Q1; The output ends of the plurality of relay units are connected to the input end of the acquisition module.

[0033] Working principle: Figure 4 As shown in the figure, the relay and transistor 3DK9B form a relay core control circuit. When the 2nd foot of transistor 3DK9B passes through the front stage Figure 3 The control current signal input by the control switching circuit makes the transistor 3DK9B conduct, and the reference voltage VDDA15 15V voltage is pressurized through the ground loop of the transistor, so that the magnetic core inside the relay is energized to realize the pull-in of the relay. On the contrary, when the 2nd foot of the transistor 3DK9B is disconnected and presents a high-impedance state, the magnetic core of the relay is not energized, and the relay is disconnected. It is worth mentioning that in this embodiment, a fixed contact relay can be selected. Even if the relay circuit is powered off or damaged, its contacts can be optionally fixed, so that the capacitor signal is always turned on to enter the PROBEA_HI and PROBEA_LO channels, thereby improving reliability. At the same time, compared with the traditional analog switch chip switching, the switching of its signals must ensure that the same signal capacitor cannot be turned on or off at the same time. The control signal of the analog switch is relatively independent and cannot be guaranteed to be either on or off, unless a logic device such as an inverter is added, which increases the complexity of the circuit. The control input signal of the relay can realize a single on-off logic of a non-"A" channel, that is, a "B" channel, and keep "A" on under normal conditions.

[0034] In addition, if Figure 4 As shown, the circuit is expanded to a switch group circuit. After multiple capacitor signals and multiple control switching signals are combined, different capacitor signals can be switched to the signal acquisition module A or B. Flexible configuration can be achieved through the CPU unit. If a channel signal has a problem, it can also be switched separately to quickly reconstruct the fault.

[0035] The other parts of this embodiment are the same as any one of the above-mentioned embodiments 1-2, so they will not be repeated here.

[0036] Embodiment 4: In this embodiment, based on any one of the above-mentioned embodiments 1 to 3, the acquisition module includes multiple analog switch chips and multiple capacitance signal acquisition circuits; The input ends of the multiple analog switch chips are connected to the output ends of the multiple relay units, the controlled ends of the multiple analog switch chips input timing switching signals, and the output ends of the multiple analog switch chips are connected to the multiple capacitance signal acquisition circuits.

[0037] Furthermore, the analog switch chip is an ADG408 chip.

[0038] Working principle: Figure 5 The figure shows the analog switch chip and peripheral circuit design inside the capacitance signal acquisition module. Through two independent ADG408 chips with multiple selection 1 analog switches, the two-level signals of the capacitance signal are switched in time-sharing mode to achieve time-sharing acquisition. The specific implementation steps are as follows: the logic level of the control selection channel is input through Prote_A0-Prote_A2, that is, 5V high level represents 1 logic, 0 level represents 0 logic, and it is encoded through "8421 code", and channels from 000-111 can be selected, that is, 8 channels are optional. By controlling the ADG408 device at the same time, the two-level capacitance signal is simultaneously selected and connected to the capacitance measurement circuit.

[0039] like Figure 5 In the example, the signal input terminal of the analog switch ADG408 is connected to a 0 ohm resistor, which is used to set a reserved self-test channel or perform fault isolation detection, that is, to test the time-sharing switching function of the analog switch without inputting a capacitor signal. This analog switch makes up for the shortcomings of the relay switch, which has a low switching frequency and cannot achieve time-sharing fast excitation of the capacitor signal array channel.

[0040] like Figure 2 , Figure 4 and Figure 5 It can be seen that the CPU processor can comprehensively control whether any one of the capacitor signal arrays is switched to the A or B capacitor signal acquisition module, and whether it enters the acquisition circuit for acquisition, through the switching logic and timing switching logic sent by the switching control circuit. The invention is used to achieve the isolation, switching and acquisition requirements of the capacitor signal array, and can be used for fault isolation and fault reconstruction of the capacitor acquisition system.

[0041] The other parts of this embodiment are the same as any one of the above-mentioned embodiments 1 to 3, so they will not be repeated here.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An isolation switching system for array capacitor signal redundancy acquisition, connected to an array capacitor; characterized in that: Including switching control module, isolation module and acquisition module; The input end of the isolation module is connected to the output end of the array capacitor, and the output end of the isolation module is connected to the input end of the acquisition module; The input end of the switching control module is connected to the host computer, and the output end of the switching control module is connected between the output end of the array capacitor and the input end of the switching control module; The input end of the acquisition module is connected to the host computer, and the output end outputs a capacitance signal; The switching control module is used to convert the switching control signal obtained from the host computer into a driving current signal; The isolation module is used to switch the capacitance signal obtained from the array capacitance to the corresponding acquisition channel according to the driving current signal; The acquisition module is used to acquire capacitance signals acquired from multiple acquisition channels in a time-sharing manner according to a timing switching signal acquired from a host computer.

2. The isolation switching system for array capacitance signal redundancy acquisition according to claim 1, characterized in that: The switching control module includes a filtering unit and an isolation driving unit; The input end of the filter unit inputs a switching control signal, and the output end is connected to the input end of the optical coupling isolation unit; The output end of the isolation driving unit is connected to the input end of the isolation module.

3. The isolation switching system for array capacitance signal redundancy acquisition according to claim 2, characterized in that: The filtering unit includes a resistor R321 and a capacitor C306; One end of the resistor R321 is input with a switching control signal, and the other end is connected to the first input end of the isolation driving unit; One end of the capacitor C306 is connected between the output end of the resistor R321 and the first input end of the isolation driving unit, and the other end of the capacitor C306 is connected between the second input end of the isolation driving unit and the ground.

4. The isolation switching system for array capacitance signal redundancy acquisition according to claim 3 is characterized in that: The isolation driving unit includes a resistor R322, an optical coupler, a resistor R306, and a transistor Q1; The input end of the resistor R322 is connected between the output end of the resistor R321 and the capacitor C306, and the output end of the resistor R322 is connected to the first input end of the optical coupler; The second input end of the optical coupler is connected between the capacitor C306 and the ground end, the first output end of the optical coupler is connected to the power supply VDD through the resistor R306, and the second output end of the optical coupler is connected to the base of the transistor Q1; The emitter of the transistor Q1 is connected to the ground, and the collector of the transistor Q1 is connected to the input end of the isolation module.

5. The isolation switching system for array capacitance signal redundancy acquisition according to claim 4, characterized in that: The isolation unit includes a plurality of relay units; The input ends of the plurality of relay units are connected to the output end of the array capacitor and the collector of the transistor Q1; The output ends of the plurality of relay units are connected to the input end of the acquisition module.

6. The isolation switching system for array capacitance signal redundancy acquisition according to claim 5, characterized in that: The acquisition module includes multiple analog switch chips and multiple capacitance signal acquisition circuits; The input ends of the multiple analog switch chips are connected to the output ends of the multiple relay units, the controlled ends of the multiple analog switch chips input timing switching signals, and the output ends of the multiple analog switch chips are connected to the multiple capacitance signal acquisition circuits.

7. The isolation switching system for array capacitance signal redundancy acquisition according to claim 6, characterized in that: The analog switch chip is an ADG408 chip.

8. An isolation switching method for array capacitor signal redundancy acquisition, implemented based on the isolation switching system for array capacitor signal redundancy acquisition as claimed in claim 1; characterized in that: First, the switching control signal obtained from the host computer is converted into a driving current signal; then the capacitance signal obtained from the array capacitor is switched to the corresponding acquisition channel according to the driving current signal; finally, the capacitance signals obtained from multiple acquisition channels are collected in time-sharing according to the timing switching signal obtained from the host computer.

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