Non-intrusive and digitally-triggered narrow pulse current signal sampling circuit

Abstract

The invention relates to a non-intrusive and digitally-triggered narrow pulse current signal sampling circuit. The circuit comprises an integrating circuit, an amplifying and pulse broadening circuit, a sampling trigger circuit, an analog signal filter, a digital filter circuit and a main control circuit, the non-intrusive current sensor and the integrating circuit acquire narrow pulse current signal-analog quantity, the non-intrusive current sensor electromagnetically induces magnetic field change around a wire to generate induced current, and the integrating circuit integrates the induced current; the amplification and pulse broadening circuit is used for amplifying and broadening the narrow pulse current signal-analog quantity; the sampling trigger circuit sends a trigger signal-digital quantity based on the amplified and broadened narrow pulse current signal-analog quantity; the analog signal filter performs analog quantity filtering on the amplified and broadened narrow pulse current signal; the digital filter circuit filters the trigger signal-digital quantity; and the master control circuit receives the filtered trigger signal-digital quantity, and filters and samples the filtered narrow pulse current signal-analog quantity.

Description

Technical Field

[0001] The invention relates to signal sampling, and in particular to a non-invasive, digitally triggered narrow pulse current signal sampling circuit. Background Art

[0002] The acquisition of narrow pulse current signals has wide applications in communications, radar, medical and other fields, but its acquisition and processing have always faced many challenges. Traditional methods often find it difficult to simultaneously meet the requirements of high temporal resolution and high spatial resolution, and their real-time performance and accuracy are also insufficient.

[0003] The traditional current sampling method is to add a sampling resistor in the loop, which must be reserved during the design process. Sampling cannot be performed in locations without sampling reservations. The flexibility is low, and the sampling resistor is greatly affected by the environment such as temperature. Sampling at high currents is prone to heat, which poses certain safety risks. Especially for sampling in some high-voltage systems, isolation processing must be performed to ensure the reliability of the control system, which increases the complexity and cost of system design.

[0004] At the same time, narrow pulse signals have the characteristics of short pulse width and fast rising edge, which require the data acquisition module to have sufficient time resolution and spatial resolution. Specifically, time resolution refers to the minimum time interval that the sampling system can achieve, that is, the highest achievable sampling rate; spatial resolution is the minimum measurable voltage value.

[0005] Generally, signal acquisition must be performed directly at the high end or low end of the circuit. In either case, the acquisition circuit must be connected to the loop being acquired. At the same time, the pulse width of the pulse current signal may be as short as microseconds or even shorter, so the sampling system is required to have an extremely high sampling rate to capture the complete waveform of the signal.

[0006] At the same time, the voltage amplitude of narrow pulse signals is relatively small, which may be only tens of millivolts or even lower. It is difficult for ordinary data acquisition modules to distinguish tiny voltage changes, and these tiny signals are easily affected by electromagnetic interference. The lack of spatial resolution caused by these signal amplitudes may cause signal distortion or loss of important information, thus affecting subsequent signal analysis and processing.

[0007] According to the Nyquist sampling principle, the sampling frequency must be more than twice the frequency of the sampled waveform to accurately restore the sampled waveform. This means that for fast-changing narrow pulse signals, the sampling time interval must be very small.

[0008] In order to solve these problems, narrow pulse signals usually need to collect and analyze a large amount of data in a short period of time, which places high demands on the real-time and accuracy of the system. Sampling requires the selection of ADC (analog-to-digital converter) chips with high sampling rates and high resolutions to ensure that a large amount of data can be processed in a short period of time to meet the time resolution and spatial resolution requirements of narrow pulse signal acquisition. For periodic narrow pulse signals, an equivalent sampling mode can be used to reconstruct the waveform through multiple triggering and acquisition; for non-periodic narrow pulse signals, a real-time sampling mode is required to ensure that enough samples are collected in a single trigger event.

[0009] At the same time, in terms of hardware design, reasonable layout and wiring are required to reduce the impact of noise and interference on the acquisition results; in terms of software design, efficient and stable code needs to be written to achieve real-time data acquisition, storage and processing.

[0010] In summary, the difficulty of acquiring narrow pulse current signals lies in the requirements of high temporal resolution and high spatial resolution, as well as the challenges of real-time and accuracy. Summary of the invention

[0011] The invention provides a non-intrusive, digitally triggered narrow pulse current signal sampling circuit.

[0012] The technical solution of the present invention: A non-invasive narrow pulse current signal sampling circuit, the circuit comprises a non-invasive current sensor, an integration circuit, an amplification and pulse stretching circuit, an analog signal filter, and a main control circuit; the non-invasive current sensor and the integration circuit obtain a narrow pulse current signal-analog quantity, the magnetic field around the electromagnetic induction wire of the non-invasive current sensor changes and generates an induced current, and the integration circuit integrates the induced current; the amplification and pulse stretching circuit amplifies and stretches the narrow pulse current signal-analog quantity; the analog signal filter filters the amplified and stretched narrow pulse current signal-analog quantity; the main control circuit filters and samples the filtered narrow pulse current signal-analog quantity.

[0013] The above technical solution is further refined, the integration circuit is composed of a diode, a resistor, and a capacitor; the amplification and pulse stretching circuit is composed of a triode and a resistor; and the main control circuit is an MCU.

[0014] A non-invasive, digitally triggered narrow pulse current signal sampling circuit, the circuit comprising an integration circuit, an amplification and pulse stretching circuit, a sampling trigger circuit, an analog signal filter, a digital filtering circuit, and a main control circuit; the non-invasive current sensor and the integration circuit obtain the narrow pulse current signal-analog quantity, the non-invasive current sensor electromagnetically senses the magnetic field changes around the wire and generates an induced current, and the integration circuit integrates the induced current; The amplification and pulse stretching circuit amplifies and stretches the narrow pulse current signal-analog quantity; the sampling trigger circuit sends a trigger signal-digital quantity based on the amplified and stretched narrow pulse current signal-analog quantity; the analog signal filter filters the amplified and stretched narrow pulse current signal-analog quantity; the digital filtering circuit filters the trigger signal-digital quantity; the main control circuit receives the filtered trigger signal-digital quantity, and samples the filtered narrow pulse current signal-analog quantity.

[0015] The above technical solution is further refined: the integration circuit is composed of a diode, a resistor, and a capacitor; the amplification and pulse stretching circuit is composed of a transistor and a resistor; the sampling trigger circuit is composed of a resistor and a transistor; the digital filter circuit is composed of a resistor and a capacitor; and the main control circuit is an MCU.

[0016] The advantages of the present invention are reasonable design and ingenious conception. It adopts a non-invasive method to sample non-continuous narrow pulse current signals, frequency-widens the narrow pulse analog signals during signal processing, reduces the sampling speed, and uses conventional sampling methods to meet the time and space resolution requirements. At the same time, the sampling signal is triggered in the form of current to improve the anti-interference ability of the system. At the same time, in the sampling process, digital signal triggering is used, that is, when there is a trigger level, the system performs signal acquisition, avoiding the system from continuous collection in the absence of pulse current, and improving the utilization rate of the system computing power. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a non-intrusive, digitally triggered narrow pulse current signal sampling circuit diagram.

[0018] Figure 2 It is a schematic diagram of a non-intrusive, digitally triggered narrow pulse current signal sampling circuit.

[0019] In the figure, the non-intrusive current sensor T1 1, the integration circuit 2, the amplification and pulse stretching circuit 3, the sampling trigger circuit 4, the analog signal filter C2 5, the digital filtering circuit 6, and the MCU 7. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, a non-intrusive, digitally triggered narrow pulse current signal sampling circuit, a non-intrusive current sensor T1 1, a diode D1, a resistor R1, and a capacitor C1 constitute an integration circuit 2, a transistor Q1, a resistor R2, and a resistor R3 constitute an amplification and pulse broadening circuit 3, a resistor R4, a resistor R5, a resistor R6, and a transistor Q2 constitute a sampling trigger circuit 4, an analog signal filter C2 5, a resistor R6, and a capacitor C3 constitute a digital filtering circuit 6, and an MCU 7.

[0021] Principle 1: A pulse current I flows through the wire for a period of time t ( Figure 2 In the figure, the magnetic field around the wire changes. Due to electromagnetic induction, the current sensor T1 generates an induced electromotive force in the coil, which in turn generates an induced current Is. The current is integrated through R1 and C1. After integration, the voltage across C1 is Uc1. At the same time, C1 discharges through R2. Since R2 is relatively large, the discharge period t2 becomes longer, thereby widening the pulse signal ( Figure 2 In P2, the pulse signal is amplified by Q1 while being widened. (Since the current signal is generated during the discharge and signal amplification process, the anti-interference performance is strong.) After the amplified signal is filtered by C2, the MCU samples it and amplifies it to generate a digital signal ( Figure 2 P3 in the sampler) as the trigger level for sampling and as the start and end signals for sampling.

[0022] Principle 2: like Figure 1 , the current function in the wire is i(t), and the current sensor T1 will generate the corresponding induced electromotive force e(t), according to Ampere's loop theorem: (Formula 1) (Formula 2) According to formula 1 and 2, we can get: (Formula 3) Where, e is the induced voltage; N is the number of winding turns; A is the cross-sectional area of ​​the coil; M is the mutual inductance coefficient of the coil; μ0 is the relative magnetic permeability of air; From formula 3, we know that there is a differential relationship between the measured current and the coil induced voltage, and the coil is essentially equivalent to a differential link. In order to accurately reproduce the current waveform, it is necessary to establish an accurate equivalent circuit model of the sensor head and accurately integrate and restore the induced voltage e(t).

[0023] like Figure 1 , use the integration circuit composed of R1 and C1 to integrate e(t), and the voltage at the C1 terminal is UC1: (Formula 4) Assuming the transistor gain is β, the output voltage at C2 is UC2: (Formula 5) The pulse width after expansion τ: τ≈2R2*C (determined according to the specific amplification factor).

[0024] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

Claims

1. A non-intrusive narrow pulse current signal sampling circuit, characterized in that: The circuit includes a non-intrusive current sensor, an integration circuit, an amplification and pulse stretching circuit, an analog signal filter, and a main control circuit; The non-invasive current sensor and the integration circuit obtain a narrow pulse current signal-analog quantity, the magnetic field around the electromagnetic induction wire of the non-invasive current sensor changes and generates an induced current, and the integration circuit integrates the induced current; The amplification and pulse stretching circuit amplifies and stretches the narrow pulse current signal-analog quantity; The analog signal filter filters the amplified and widened narrow pulse current signal - analog quantity; The main control circuit samples the filtered narrow pulse current signal-analog quantity through filtering.

2. A non-intrusive narrow pulse current signal sampling circuit according to claim 1, characterized in that: The integration circuit is composed of a diode, a resistor and a capacitor; The amplification and pulse stretching circuit is composed of a triode and a resistor; The main control circuit is MCU.

3. A non-intrusive, digitally triggered narrow pulse current signal sampling circuit, characterized in that: The circuit includes an integration circuit, an amplification and pulse stretching circuit, a sampling trigger circuit, an analog signal filter, a digital filtering circuit, and a main control circuit; The non-invasive current sensor and the integration circuit obtain a narrow pulse current signal-analog quantity, the magnetic field around the electromagnetic induction wire of the non-invasive current sensor changes and generates an induced current, and the integration circuit integrates the induced current; The amplification and pulse stretching circuit amplifies and stretches the narrow pulse current signal-analog quantity; The sampling trigger circuit sends a trigger signal - a digital quantity based on the amplified and widened narrow pulse current signal - an analog quantity; The analog signal filter filters the amplified and widened narrow pulse current signal-analog quantity; The digital filtering circuit filters the trigger signal-digital quantity; The main control circuit receives the filtered trigger signal - a digital quantity, and filters and samples the filtered narrow pulse current signal - an analog quantity.

4. A non-intrusive, digitally triggered narrow pulse current signal sampling circuit according to claim 4, characterized in that: The integration circuit is composed of a diode, a resistor and a capacitor; The amplification and pulse stretching circuit is composed of a triode and a resistor; The sampling trigger circuit is composed of a resistor and a triode; The digital filter circuit is composed of resistors and capacitors; The main control circuit is MCU.

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