Pico-ampere level detection control circuit and performance detection system of ionization electrostatic detection device

Abstract

The application discloses a kind of pA level detection control circuit and performance detection system of ionized electrostatic detection equipment, including drive boost circuit, detection flat plate, pA level detection circuit, main control closed loop control circuit, high voltage linear switch circuit and voltage division sampling circuit.Two-way signal of detection flat plate is accessed first operational amplifier and is differentially amplified by resistive path and capacitive path respectively;High voltage linear switch circuit includes multiple high voltage switch tubes in series and working in linear amplification area;Voltage division sampling circuit attenuates main high voltage signal and feeds back to main control closed loop control circuit, to form full hardware closed loop.This application realizes the accurate detection of pA level ion current under high voltage environment and the construction of 0 to ±1000V continuous adjustable analog electrostatic environment.

Description

Technical Field

[0001] This invention belongs to the technical field of electrostatic detection equipment, specifically relating to a pA-level detection control circuit and performance testing system for an ionization electrostatic detection device. Background Technology

[0002] According to relevant IEC and GB / T electrostatic discharge (ESD) testing standards, ESD decay time is defined as the time required for an ESD voltage to decrease from 1000V to 100V. Simultaneously, the residual ESD voltage after the ionization ESD eliminator has been in operation must not exceed ±50V. Therefore, the core performance indicators for ionization ESD eliminators are ESD elimination time and residual ion voltage. The crucial prerequisite for accurately detecting these two indicators is to build a high-precision detection circuit capable of simulating a continuously adjustable ESD environment from 0 to ±1000V, and simultaneously capturing the voltage decay process and acquiring the residual voltage.

[0003] In related technologies, the industry commonly uses charged flatbed monitors (CPMs) to perform performance testing on ionization electrostatic eliminators. These devices use a built-in high-voltage generator to charge the test flatbed to simulate a charged state, then rely on a voltage monitoring unit to collect data on the flatbed voltage decay, and use a timer to calculate the electrostatic elimination time. However, in practical engineering applications, traditional CPM devices have several inherent technical defects that make it difficult to meet the requirements for high-precision testing.

[0004] First, traditional CPM equipment's high-voltage generators mostly have a switching output structure, with the high-voltage output being a chopper-type voltage. This makes it impossible to achieve continuous linear adjustment and accurately reproduce the continuous decay process of electrostatic voltage from 1000V to 100V, directly resulting in low accuracy and poor data repeatability in the detection of electrostatic discharge time. Second, traditional detection schemes rely on microcontrollers to complete data timing and equipment control. The response speed is limited by the software processing speed, making it impossible to achieve millisecond-level or sub-millisecond-level real-time signal tracking, and its ability to capture rapid electrostatic decay processes is insufficient.

[0005] Furthermore, pA-level (10⁻¹² amperes) ion currents are extremely weak signals, making them highly sensitive to ambient noise. In traditional CPM devices, the high-voltage circuit and detection circuit are grounded together. Ripple and electromagnetic noise generated by the high-voltage operation directly couple to the detection circuit, easily drowning out the weak pA-level ion signal and significantly reducing detection accuracy and reliability. Finally, the high-voltage linear regulation module and signal detection module in existing detection devices are independent, failing to form a real-time hardware closed-loop control. This results in timing deviations between the simulated electrostatic environment setup and the ion neutralization process, further affecting the detection accuracy of the residual voltage.

[0006] In summary, existing ionization electrostatic detection technologies have significant shortcomings in terms of detection accuracy, real-time performance, anti-interference capability, and system synergy, making them unsuitable for high-precision, standardized electrostatic performance testing requirements. There is an urgent need to develop a detection control circuit and system that can construct a dynamic simulated electrostatic field, achieve pA-level high-precision signal detection, and enable real-time control through a fully hardware closed-loop system. Summary of the Invention

[0007] The purpose of this application is to at least partially solve one of the aforementioned technical problems.

[0008] Therefore, the first objective of this application is to propose a pA-level detection control circuit for an ionization electrostatic detection device. This circuit can construct a continuously adjustable simulated electrostatic environment from 0 to ±1000V, achieve high-precision detection of pA-level ion current, and track the electrostatic decay process in real time through a fully hardware closed-loop system.

[0009] The second objective of this application is to provide a performance testing system for ionization electrostatic elimination equipment.

[0010] To achieve the above objectives, the first aspect of this application proposes a pA-level detection control circuit for an ionization electrostatic detection device, comprising: a drive boost circuit for generating positive and negative high voltages; a detection plate for simulating an electrostatic environment and sensing an external ion flow; a pA-level detection circuit connected to the detection plate, including a first operational amplifier, wherein two signals from the detection plate are respectively connected to the non-inverting and inverting inputs of the first operational amplifier via resistive and capacitive paths, respectively, and the first operational amplifier differentially amplifies the two input signals, outputting a detection signal at its output; and a main control closed-loop control circuit connected to the output of the pA-level detection circuit, including a two-stage negative feedback amplifier circuit composed of a second operational amplifier, for receiving the detection signal and the high voltage sampling signal and outputting... The system includes: a continuously adjustable control voltage; a high-voltage linear switching circuit connected between the drive boost circuit and the detection plate, comprising multiple high-voltage switching transistors connected in series, the high-voltage switching transistors operating in the linear amplification region, and their control terminals connected to the output terminal of the main control closed-loop control circuit, used to continuously adjust the electrostatic voltage applied to the detection plate according to the control voltage; a voltage divider sampling circuit connected between the high-voltage output terminal of the high-voltage linear switching circuit and the feedback input terminal of the main control closed-loop control circuit, used to attenuate the main high-voltage signal into a low-voltage sampling signal and feed it back to the main control closed-loop control circuit; the output terminal of the main control closed-loop control circuit is connected to the control terminal of the high-voltage linear switching circuit, and the output terminal of the voltage divider sampling circuit is connected to the feedback input terminal of the main control closed-loop control circuit.

[0011] In addition, the pA-level detection control circuit of the ionization electrostatic detection device in this application embodiment also has the following additional technical features:

[0012] Optionally, in some embodiments, the power supply circuit of the first operational amplifier of the pA-level detection circuit is provided with a clamping protection network, which is connected to a system interlock signal for clamping protection of the first operational amplifier.

[0013] Optionally, in some embodiments, the second operational amplifier of the main control closed-loop control circuit includes a first-stage amplification unit and a second-stage amplification unit. The output signal of the pA-stage detection circuit is connected to the inverting input terminal of the first-stage amplification unit. The negative power supply terminal of the first operational amplifier is connected to a -12V power supply via a first bias resistor. The -12V power supply node is connected to the non-inverting input terminal of the first-stage amplification unit via a coupling capacitor. The output terminal of the first-stage amplification unit is connected to the inverting input terminal of the second-stage amplification unit. The output terminal of the voltage divider sampling circuit is connected to the non-inverting input terminal of the second-stage amplification unit. The output terminal of the second-stage amplification unit outputs the control voltage.

[0014] Optionally, in some embodiments, the high-voltage linear switching circuit includes mutually independent positive high-voltage switching branches and negative high-voltage switching branches, each branch including multiple high-voltage switching transistors connected in series; a voltage equalization resistor network is connected in parallel between the collector and emitter of each high-voltage switching transistor to make each high-voltage switching transistor evenly share the high-voltage drop.

[0015] Optionally, in some embodiments, the base drive of each high-voltage switch tube in the positive high-voltage switch branch is controlled by a first driving tube, the collector of the first driving tube being connected to the output terminal of the positive high-voltage switch branch; the negative high-voltage switch branch is driven by optocoupler isolation, the primary side of the optocoupler being controlled by a second driving tube.

[0016] Optionally, in some embodiments, the control voltage output by the main control closed-loop control circuit is divided into two paths: the first path is connected to the base of the first driving transistor via a first directional diode, and the second path is connected to the base of the second driving transistor via a second directional diode; the first directional diode and the second directional diode have opposite conduction directions, and the control voltage controls the first driving transistor via the first directional diode and controls the second driving transistor via the second directional diode, so that the positive high voltage branch and the negative high voltage branch are mutually exclusive and conduct.

[0017] Optionally, in some embodiments, an RC network is provided in the driving circuit of the second driving transistor, and a control signal is led out from the output terminal of the RC network. The control signal is divided into three parallel paths: the first path is connected to the base bias network of the first driving transistor for turning off the positive high voltage; the second path controls the optocoupler through the second driving transistor for controlling the opening and closing of the negative high voltage; and the third path is connected to the clamping protection terminal of the first operational amplifier for protecting the first operational amplifier.

[0018] Optionally, in some embodiments, the voltage divider sampling circuit includes a high-voltage voltage divider resistor network connected between the high-voltage output terminal of the high-voltage linear switching circuit and the feedback input terminal of the main control closed-loop control circuit, for attenuating the main high-voltage signal into a low-voltage sampling signal at a fixed ratio and sending it to the feedback input terminal.

[0019] Optionally, in some embodiments, an isolation power supply circuit is also included, which provides the pA-level detection circuit and the main control closed-loop control circuit with a power supply that is electrically isolated from the high-voltage circuit; the drive boost circuit adopts a single transformer structure to synchronously generate positive and negative high voltage.

[0020] To achieve the above objectives, a second aspect of this application provides a performance testing system for an ionization electrostatic elimination device, comprising: a testing plate; a pA-level testing and control circuit as described in any one of the first aspects of the embodiment; the high-voltage output terminal of the pA-level testing and control circuit is electrically connected to the testing plate, for constructing a continuously adjustable simulated electrostatic environment on the testing plate and acquiring its voltage signal.

[0021] Optionally, in some embodiments, the pA-level detection and control circuit uses a hardware interlock structure to ensure that the positive high-voltage branch and the negative high-voltage branch are mutually exclusive and not simultaneously output.

[0022] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects:

[0023] This application connects two signals from the detection plate to the non-inverting and inverting inputs of the first operational amplifier via resistive and capacitive paths, respectively. Differential amplification is used to cancel high-voltage ripple, thereby achieving accurate extraction of pA-level ion current signals under high-voltage conditions and avoiding interference from high-voltage ripple on detection accuracy.

[0024] This application constructs a high-voltage linear switching circuit using multiple high-voltage switching transistors connected in series and operating in the linear amplification region. This circuit enables continuous linear adjustment of the electrostatic voltage within the range of 0 to ±1000V, accurately simulating the continuous decay process of the electrostatic voltage from 1000V to 100V, and improving the measurement accuracy of the extinction time.

[0025] This application outputs a continuously adjustable control voltage through a main control closed-loop control circuit, which drives a high-voltage linear switching circuit to follow the voltage changes on the detection plate in real time, forming a fully hardware closed-loop control structure. No software intervention is required, and the response speed can reach the millisecond level, realizing real-time synchronous tracking of the electrostatic decay process.

[0026] This application achieves hardware interlocking of positive and negative high voltages by controlling the driving transistors of the positive and negative high voltage branches respectively through two diodes with opposite conduction directions, as well as optocoupler isolation driving, thereby ensuring that the positive and negative high voltages are not output at the same time, avoiding the risk of high voltage collision short circuit, and improving the safety of the system.

[0027] This application provides an isolated power supply circuit for the low-voltage detection circuit and the main control circuit, which is electrically isolated from the high-voltage circuit. The drive boost circuit adopts a single transformer structure to synchronously generate positive and negative high voltages, which simplifies the power supply architecture and ensures the safety and long-term stability of the low-voltage precision detection circuit.

[0028] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0029] Figure 1 This is a block diagram of the overall architecture of the pA-level detection control circuit of an ionization electrostatic detection device proposed in this application embodiment;

[0030] Figure 2 This is a schematic diagram of an isolated power supply circuit proposed in an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of a driving boost circuit proposed in an embodiment of this application;

[0032] Figure 4 This is a schematic diagram of a detection control circuit proposed in an embodiment of this application;

[0033] Figure 5 This is a flowchart illustrating the pA-level detection control circuit of an ionization electrostatic detection device proposed in this application. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0035] It should be noted that, in the embodiments of this application, the core performance indicators of ionization electrostatic eliminators (such as ion fans, ion bars, etc.) include static discharge time and residual ion voltage. Static discharge time refers to the time required for the electrostatic voltage on the detection plate to decay from 1000V to 100V, and residual ion voltage refers to the voltage value remaining on the detection plate after the equipment has been operating. According to standards such as IEC 61340-5-1, SJ / T 11446-2013, and ANSI / ESD STM3.1, static discharge time is a key indicator for evaluating the neutralization speed of electrostatic eliminators, and residual ion voltage is a key indicator for evaluating the ion balance of the equipment, requiring it to not exceed ±50V.

[0036] Currently, the detection and control schemes for performance testing of ionization electrostatic elimination equipment are not mature enough. The detection accuracy is severely affected by high-voltage ripple interference, making it impossible to achieve accurate detection of pA-level ion current. Furthermore, the detection circuit response speed is slow, making it difficult to track the electrostatic decay process in real time. Therefore, this application provides a pA-level detection control circuit and detection system for ionization electrostatic detection equipment. This system can construct a continuously adjustable simulated electrostatic environment from 0 to ±1000V, achieve high-precision detection of pA-level ion current, and track the electrostatic decay process in real time through a fully hardware closed-loop system.

[0037] The pA-level detection control circuit and detection system of the ionization electrostatic detection device according to an embodiment of this application are described below with reference to the accompanying drawings.

[0038] Figure 1 This is a block diagram of the overall architecture of the pA-level detection control circuit of an ionization electrostatic detection device proposed in an embodiment of this application. Figure 1 As shown, the pA-level detection and control circuit mainly includes: a drive boost circuit 100, a high-voltage linear switching circuit 200, a detection plate 300, a pA-level detection circuit 400, a main control closed-loop control circuit 500, and a voltage divider sampling circuit 600.

[0039] The drive boost circuit 100 generates positive and negative high voltages. The detection plate 300 simulates an electrostatic environment and senses external ion flow. The pA-level detection circuit 400, connected to the detection plate 300, includes a first operational amplifier A2. The two signals from the detection plate 300 are respectively connected to the non-inverting and inverting inputs of the first operational amplifier A2 via resistive and capacitive paths. The first operational amplifier A2 differentially amplifies the two input signals and outputs the detection signal. The main control closed-loop control circuit 500, connected to the output of the pA-level detection circuit 400, includes a two-stage negative feedback amplifier circuit consisting of a second operational amplifier A1. It receives the detection signal and the high-voltage sampling signal and outputs a continuously adjustable control voltage. The high-voltage linear switching circuit 200, connected between the drive boost circuit 100 and the detection plate 300, includes multiple high-voltage switching transistors connected in series. The high-voltage switching transistors operate in the linear amplification region, and their control terminals are connected to the output of the main control closed-loop control circuit 500. This allows for continuous adjustment of the electrostatic voltage applied to the detection plate 300 according to the control voltage. The voltage divider sampling circuit 600 is connected between the high-voltage output terminal of the high-voltage linear switching circuit 200 and the feedback input terminal of the main control closed-loop control circuit 500. It attenuates the main high-voltage signal into a low-voltage sampling signal and feeds it back to the main control closed-loop control circuit 500. The output terminal of the main control closed-loop control circuit 500 is connected to the control terminal of the high-voltage linear switching circuit 200, and the output terminal of the voltage divider sampling circuit 600 is connected to the feedback input terminal of the main control closed-loop control circuit 500.

[0040] In one embodiment of this application, Figure 2 This is a schematic diagram of an isolated power supply circuit proposed in an embodiment of this application. Figure 2 As shown, the isolation power supply circuit outputs H_+12V and H_-12V to provide power supplies that are electrically isolated from the high-voltage circuit for the pA-level detection circuit 400 and the main control closed-loop control circuit 500. The isolation voltage is not less than 6000VDC.

[0041] In one embodiment of this application, Figure 3 This is a schematic diagram of a driving boost circuit proposed in an embodiment of this application. Figure 3 As shown, the drive boost circuit 100 is based on a single transformer architecture to boost the voltage to ±1100V, providing a total energy source for simulating an electrostatic environment.

[0042] In one embodiment of this application, Figure 4 This is a schematic diagram of a detection control circuit proposed in an embodiment of this application. The following is in conjunction with... Figure 4 Describe in detail the specific connection relationships and working principles of the pA-level detection circuit 400, the main control closed-loop control circuit 500, the high-voltage linear switching circuit 200, and the voltage divider sampling circuit 600.

[0043] like Figure 4As shown, the pA-level detection circuit 400 includes a first operational amplifier A2. The first signal from the detection plate T5 (i.e., detection plate 300) is connected to the non-inverting input (pin 3) of the first operational amplifier A2 via resistors XR4 and R16 in series. The node between resistors XR4 and R16 is grounded via a capacitor network formed by capacitors XC3 to XC9 in series, forming a resistive path. The second signal from the detection plate T5 is connected to the inverting input (pin 2) of the first operational amplifier A2 via capacitor XC1, forming a capacitive path. The first operational amplifier A2 differentially amplifies the two input signals, and its output (pin 6) outputs the detection signal. The power supply circuit of the first operational amplifier A2 is equipped with a clamping protection network, including a diode CR14 connected between the output (pin 6) and the negative power supply (pin 4) of the first operational amplifier A2, and a Zener diode CR18 connected between the interlock control signal and the negative power supply (pin 4) of the first operational amplifier A2. The negative power supply terminal (pin 4) of the first operational amplifier A2 is connected to a -12V power supply via a bias resistor R23, and the node between the bias resistor R23 and the negative power supply terminal (pin 4) of the first operational amplifier A2 is connected to a -5V bias power supply.

[0044] The output terminal (pin 6) of the first operational amplifier A2 is connected to the inverting input terminal (pin 2, i.e. the inverting input terminal of the first stage amplification unit) of the second operational amplifier A1 in the main control closed-loop control circuit 500 via resistor XR5.

[0045] The main control closed-loop control circuit 500 includes a second operational amplifier A1. The second operational amplifier A1 includes a first-stage amplification unit (op-amp A) and a second-stage amplification unit (op-amp B). The output signal of the first operational amplifier A2 is connected to the inverting input (pin 2) of the first-stage amplification unit. The negative power supply terminal (pin 4) of the first operational amplifier A2 is connected to a -12V power supply via a bias resistor R23. The -12V power supply terminal is connected to the non-inverting input (pin 3) of the first-stage amplification unit via a coupling capacitor C6. The output terminal (pin 1) of the first-stage amplification unit is connected to the inverting input (pin 6) of the second-stage amplification unit via a resistor R10. The output terminal of the voltage divider sampling circuit 600 is connected to the non-inverting input (pin 5) of the second-stage amplification unit. The output terminal (pin 7) of the second-stage amplification unit outputs the control voltage.

[0046] The high-voltage linear switching circuit 200 includes independent positive high-voltage switching branches and negative high-voltage switching branches. The positive high-voltage switching branch includes a first high-voltage switching transistor Q2, a second high-voltage switching transistor Q3, and a third high-voltage switching transistor Q4 connected in series between the positive high-voltage input terminal and the detection plate T5. The negative high-voltage switching branch includes a fourth high-voltage switching transistor Q7, a fifth high-voltage switching transistor Q5, and a sixth high-voltage switching transistor Q1 connected in series between the negative high-voltage input terminal and the detection plate T5. A voltage-equalizing resistor network is connected in parallel between the collector and emitter of each high-voltage switching transistor, and a clamping diode is connected in parallel between the base and emitter of each high-voltage switching transistor.

[0047] In one embodiment of this application, the voltage equalization resistor network includes a first voltage equalization resistor segment, a second voltage equalization resistor segment, and a third voltage equalization resistor segment. The first voltage equalization resistor segment is composed of resistors PR1, PR2, and PR3 connected in series and in parallel between the collector and emitter of the first high-voltage switching transistor Q2. The second voltage equalization resistor segment is composed of resistors PR4, PR5, and PR6 connected in series and in parallel between the collector and emitter of the second high-voltage switching transistor Q3. The third voltage equalization resistor segment is composed of resistors PR7, PR8, and PR9 connected in series and in parallel between the collector and emitter of the third high-voltage switching transistor Q4. The voltage equalization resistor network forces the total high voltage drop to be evenly distributed across each high-voltage switching transistor.

[0048] In one embodiment of this application, the base drive of each high-voltage switching transistor Q2, Q3, and Q4 in the positive high-voltage switch branch is controlled by a first driving transistor Q6. The collector of the first driving transistor Q6 is connected to the output terminal of the positive high-voltage switch branch (i.e., the emitter of the third high-voltage switching transistor Q4), and the base of the first driving transistor Q6 is connected to the control voltage output by the main control closed-loop control circuit 500 via an isolation resistor R8. The emitter of the first driving transistor Q6 is grounded via a series branch of resistor R6 and capacitor C2, and resistor R9 is connected in parallel across the series branch of resistor R6 and capacitor C2.

[0049] The negative high-voltage switch branch is driven by optocoupler XA1. The primary side of optocoupler XA1 is controlled by the second driver transistor Q8. The base of the second driver transistor Q8 is connected to the control voltage output of the main control closed-loop control circuit 500 via isolation resistor XR8. The emitter of the second driver transistor Q8 is connected to the -12V power supply via resistor XR7. The collector of the second driver transistor Q8 is connected to the primary input terminal (pin 1) of optocoupler XA1, and the primary output terminal (pin 2) of optocoupler XA1 is connected to the -12V power supply via resistor R14. The secondary output terminal (pin 4) of optocoupler XA1 is connected to the negative high-voltage input terminal, and the secondary output terminal (pin 5) of optocoupler XA1 is connected to the input terminal of the negative high-voltage switch branch.

[0050] In one embodiment of this application, the control voltage output by the main control closed-loop control circuit 500 is divided into two paths via resistor R15. The first path is connected to the base of the first driving transistor Q6 via a first-direction diode CR10, wherein the cathode of diode CR10 is connected to resistor R15, and the anode of diode CR10 is connected to the base of the first driving transistor Q6 via resistor R8. The second path is connected to the base of the second driving transistor Q8 via a second-direction diode CR13, wherein the anode of diode CR13 is connected to resistor R15, and the cathode of diode CR13 is connected to the base of the second driving transistor Q8 via resistor R8. The conduction directions of the first-direction diode CR10 and the second-direction diode CR13 are opposite. The control voltage controls the first driving transistor Q6 via the first-direction diode CR10 and controls the second driving transistor Q8 via the second-direction diode CR13, causing the positive high-voltage branch and the negative high-voltage branch to conduct mutually exclusively.

[0051] Specifically, when the control voltage is negative, the first directional diode CR10 conducts, pulling the base of the first driving transistor Q6 low and cutting it off, thus shutting off the positive high voltage; simultaneously, the second directional diode CR13 cuts off, the second driving transistor Q8 cuts off, and the optocoupler XA1 conducts, turning on the negative high voltage. When the control voltage is positive, the second directional diode CR13 conducts, the second driving transistor Q8 conducts, and the optocoupler XA1 cuts off, thus shutting off the negative high voltage; simultaneously, the first directional diode CR10 cuts off, the first driving transistor Q6 conducts, and the positive high voltage is turned on. Therefore, the positive and negative high voltages are not output simultaneously, achieving hardware interlocking.

[0052] In one embodiment of this application, the driving circuit of the second driving transistor Q8 is provided with an RC network, which is composed of a capacitor C4 and a resistor R12 connected in series, and a resistor XR13 connected in parallel across the series branch of capacitor C4 and resistor R12. The output terminal of the RC network (i.e., the node between capacitor C4 and resistor R12) leads out a control signal, which is divided into three parallel paths: the first path is connected to the base bias network of the first driving transistor Q6, used to turn off the positive high voltage in negative high voltage mode; the second path controls the optocoupler XA1 through the second driving transistor Q8, used to control the opening and closing of the negative high voltage; the third path is connected to the clamping protection terminal (i.e., Zener diode CR18) of the first operational amplifier A2, used to protect the first operational amplifier A2 in negative high voltage mode.

[0053] The voltage divider sampling circuit 600 includes a high-voltage voltage divider resistor network. The high-voltage voltage divider resistor network is connected between the high-voltage output terminal of the high-voltage linear switching circuit 200 and the feedback input terminal of the main control closed-loop control circuit 500. It is used to attenuate the main high-voltage signal into a low-voltage sampling signal at a fixed ratio and send it to the feedback input terminal (i.e., the non-inverting input terminal 5 of the second operational amplifier A1).

[0054] In one embodiment of this application, the voltage divider sampling circuit 600 further includes a bias calibration branch connected between the feedback input terminal of the main control closed-loop control circuit 500 and the external ADC conversion circuit, for providing a calibration output of the sampling signal.

[0055] In one embodiment of this application, the drive boost circuit 100 adopts a single transformer structure to synchronously generate positive and negative high voltages.

[0056] Figure 5 This is a flowchart illustrating the pA-level detection control circuit of an ionization electrostatic detection device according to an embodiment of this application. The following is in conjunction with... Figure 5 The working principle of the pA-level detection and control circuit of the present application embodiment is described in detail.

[0057] like Figure 5 As shown, the workflow of the pA-level detection control circuit in this application embodiment includes the following steps:

[0058] Step S101: A positive high voltage and a negative high voltage are generated by driving the boost circuit.

[0059] Specifically, after the boost circuit 100 is powered on, it synchronously generates positive high voltage (+1100V) and negative high voltage (-1100V) based on a single transformer architecture, providing a total energy source for the simulated electrostatic environment.

[0060] In step S102, a simulated electrostatic voltage is applied to the detection plate through a high-voltage linear switching circuit.

[0061] Specifically, the high-voltage linear switching circuit 200 controls the conduction level of multiple series-connected high-voltage switching transistors in the positive or negative high-voltage switching branch based on the control voltage output by the main control closed-loop control circuit 500. Since the high-voltage switching transistors operate in the linear amplification region, their equivalent internal resistance changes continuously with the control voltage, thereby continuously adjusting and applying the high voltage generated by the drive boost circuit 100 to the detection plate 300, constructing a continuously adjustable simulated electrostatic environment within the range of 0 to ±1000V on the detection plate 300.

[0062] Step S103: The detection plate senses the external ion flow and generates two detection signals.

[0063] Specifically, when the external ionization electrostatic elimination device is activated, the ion wind it generates blows towards the detection plate 300, neutralizing the electrostatic charge on the detection plate 300, causing a change in the electrostatic voltage on the detection plate 300. The detection plate 300 outputs two detection signals: one is connected to the non-inverting input of the first operational amplifier A2 via a resistive path (resistors XR4 and R16), and this signal contains a high-voltage DC component and an ion change component; the other is connected to the inverting input of the first operational amplifier A2 via a capacitive path (capacitor XC1), and this signal mainly contains a high-voltage ripple component.

[0064] Step S104: Differential amplification of the two detection signals is performed by the first operational amplifier to output the detection signal.

[0065] Specifically, the first operational amplifier A2 differentially amplifies the two signals at the non-inverting and inverting input terminals. Since the high-voltage ripple components in the two signals have equal amplitude and the same phase, they cancel each other out after differential amplification. The ion change component exists only in the resistive path and is effectively preserved and amplified. The output terminal of the first operational amplifier A2 outputs a detection signal containing the ion change component.

[0066] In step S105, the control voltage is amplified by the two-stage negative feedback of the second operational amplifier.

[0067] Specifically, the detection signal output from the first operational amplifier A2 is connected to the inverting input of the first-stage amplification unit of the second operational amplifier A1. Simultaneously, the voltage change at the negative power supply terminal of the first operational amplifier A2 is connected to the non-inverting input of the first-stage amplification unit via coupling capacitor C6. The output of the first-stage amplification unit is connected to the inverting input of the second-stage amplification unit. The low-voltage sampling signal output from the voltage divider sampling circuit 600 is connected to the non-inverting input of the second-stage amplification unit. The second-stage amplification unit compares and amplifies the above signals, and its output terminal outputs a continuously adjustable control voltage.

[0068] Step S106: Adjust the electrostatic voltage on the detection plate by controlling the voltage to drive the high-voltage linear switching circuit.

[0069] Specifically, the control voltage output from the main closed-loop control circuit 500 is divided into two paths via resistor R15: the first path controls the first driving transistor Q6 via the first direction diode CR10, and the second path controls the second driving transistor Q8 via the second direction diode CR13. When the control voltage is negative, the positive high voltage is off and the negative high voltage is on; when the control voltage is positive, the positive high voltage is on and the negative high voltage is off. The high-voltage linear switching circuit 200 continuously adjusts the electrostatic voltage applied to the detection plate 300 according to the control voltage, so that the electrostatic voltage on the detection plate 300 follows the changes in the external ion flow in real time.

[0070] Step S107: The high voltage status is fed back in real time through the voltage divider sampling circuit to form a closed-loop control.

[0071] Specifically, the voltage divider sampling circuit 600 acquires the main high-voltage signal from the high-voltage output terminal of the high-voltage linear switching circuit 200 in real time, attenuates it to a low-voltage sampling signal according to a fixed ratio, and then feeds it back to the feedback input terminal of the main control closed-loop control circuit 500. The main control closed-loop control circuit 500 compares the feedback signal with the detection signal and adjusts the output of the control voltage in real time, forming a fully hardware closed-loop control structure.

[0072] In one embodiment of this application, the pA-level detection and control circuit can be used to measure the discharge time of an ionization electrostatic eliminator. Specifically, a simulated electrostatic voltage of +1000V (or -1000V) is first applied to the detection plate 300 by driving the boost circuit 100 and the high-voltage linear switching circuit 200. Then, the ionization electrostatic eliminator under test is started, and the ion wind generated by it neutralizes the electrostatic charge on the detection plate 300, causing the voltage on the detection plate 300 to drop from 1000V. The voltage divider sampling circuit 600 monitors the voltage change on the detection plate 300 in real time. When the voltage drops to 100V, the external measuring device records the moment, and the time difference between this moment and the start-up moment is the discharge time.

[0073] In one embodiment of this application, the pA-level detection and control circuit can also be used to measure the residual voltage of an ionization electrostatic eliminator. Specifically, after the ion wind has been applied for a period of time, the voltage on the detection plate 300 gradually stabilizes at a fixed value and no longer changes; this stable value is the residual voltage. The voltage divider sampling circuit 600 reads the low-voltage sampling signal corresponding to this stable value and calculates the residual voltage value.

[0074] In summary, the pA-level detection control circuit and detection system of the ionization electrostatic detection equipment in this application embodiment achieves accurate extraction of pA-level ion current signals under high-voltage conditions by connecting the two signals from the detection plate to the non-inverting and inverting input terminals of the first operational amplifier via resistive and capacitive paths, respectively, and using differential amplification to cancel high-voltage ripple. A high-voltage linear switching circuit is constructed using multiple high-voltage switching transistors connected in series and operating in the linear amplification region, enabling continuous linear adjustment of the electrostatic voltage within the range of 0 to ±1000V. A continuously adjustable control voltage is output from the main control closed-loop control circuit to drive the high-voltage linear switching circuit to follow the voltage changes on the detection plate in real time, forming a fully hardware closed-loop control structure with a response speed down to the millisecond level. Hardware interlocking of the positive and negative high voltages is achieved by controlling the driving transistors of the positive and negative high-voltage branches respectively through two diodes with opposite conduction directions, and by optocoupler isolation driving. An isolated power supply circuit provides a power supply to the low-voltage detection circuit that is electrically isolated from the high-voltage circuit, and the boost circuit uses a single transformer structure to synchronously generate positive and negative high voltages, ensuring the safety and long-term stability of the low-voltage precision detection circuit.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0076] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A pA-level detection control circuit for an ionization electrostatic detection device, characterized in that, include: Drive the boost circuit to generate positive and negative high voltages; A detection plate is used to simulate an electrostatic environment and sense external ion flow. The pA-level detection circuit is connected to the detection plate and includes a first operational amplifier. The two signals of the detection plate are respectively connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier via resistive and capacitive paths. The first operational amplifier differentially amplifies the two input signals and outputs the detection signal at its output terminal. The main control closed-loop control circuit is connected to the output terminal of the pA-level detection circuit. It includes a two-stage negative feedback amplifier circuit composed of a second operational amplifier, which is used to receive the detection signal and the high voltage sampling signal and output a continuously adjustable control voltage. A high-voltage linear switching circuit is connected between the drive boost circuit and the detection plate. It includes multiple high-voltage switching transistors arranged in series. The high-voltage switching transistors operate in the linear amplification region. Their control terminals are connected to the output terminals of the main control closed-loop control circuit, and are used to continuously adjust the electrostatic voltage applied to the detection plate according to the control voltage. The voltage divider sampling circuit is connected between the high voltage output terminal of the high voltage linear switching circuit and the feedback input terminal of the main control closed-loop control circuit. It is used to attenuate the main high voltage signal into a low voltage sampling signal and feed it back to the main control closed-loop control circuit. The output terminal of the main control closed-loop control circuit is connected to the control terminal of the high-voltage linear switching circuit, and the output terminal of the voltage divider sampling circuit is connected to the feedback input terminal of the main control closed-loop control circuit.

2. The pA-level detection control circuit of the ionization electrostatic detection device according to claim 1, characterized in that, The power supply circuit of the first operational amplifier in the pA-level detection circuit is equipped with a clamping protection network. The clamping protection network is connected to the system interlock signal and is used to clamp the first operational amplifier.

3. The pA-level detection control circuit of the ionization electrostatic detection device according to claim 1, characterized in that, The second operational amplifier of the main control closed-loop control circuit includes a first-stage amplification unit and a second-stage amplification unit. The output signal of the pA-stage detection circuit is connected to the inverting input terminal of the first-stage amplification unit. The negative power supply terminal of the first operational amplifier is connected to a -12V power supply through a first bias resistor. The voltage signal of the -12V power supply node is connected to the non-inverting input terminal of the first-stage amplification unit through a coupling capacitor. The output terminal of the first-stage amplification unit is connected to the inverting input terminal of the second-stage amplification unit. The output terminal of the voltage divider sampling circuit is connected to the non-inverting input terminal of the second-stage amplification unit. The output terminal of the second-stage amplification unit outputs the control voltage.

4. The pA-level detection control circuit of the ionization electrostatic detection device according to claim 1, characterized in that, The high-voltage linear switching circuit includes independent positive high-voltage switching branches and negative high-voltage switching branches. Each branch includes multiple high-voltage switching transistors connected in series. A voltage-equalizing resistor network is connected in parallel between the collector and emitter of each high-voltage switching transistor to ensure that each high-voltage switching transistor shares the high-voltage drop evenly.

5. The pA-level detection control circuit of an ionization electrostatic detection device according to claim 4, characterized in that, The base drive of each high-voltage switch tube in the positive high-voltage switch branch is controlled by a first drive tube, and the collector of the first drive tube is connected to the output terminal of the positive high-voltage switch branch; the negative high-voltage switch branch is driven by optocoupler isolation, and the primary side of the optocoupler is controlled by a second drive tube.

6. The pA-level detection control circuit of an ionization electrostatic detection device according to claim 5, characterized in that, The control voltage output by the main control closed-loop control circuit is divided into two paths: the first path is connected to the base of the first driving transistor via a first directional diode, and the second path is connected to the base of the second driving transistor via a second directional diode; the first directional diode and the second directional diode have opposite conduction directions, and the control voltage controls the first driving transistor via the first directional diode and controls the second driving transistor via the second directional diode, so that the positive high voltage branch and the negative high voltage branch are mutually exclusive and conduct.

7. The pA-level detection control circuit of an ionization electrostatic detection device according to claim 6, characterized in that, The second driving transistor's driving circuit includes an RC network, and the output of the RC network leads to a control signal, which is then divided into three parallel paths: The first path is connected to the base bias network of the first driving transistor, which is used to control the on / off state of the positive high voltage branch. The second path controls the optocoupler via the second driving transistor, which is used to control the on / off state of the negative high voltage branch. The third path connects to the clamping protection terminal of the first operational amplifier, and is used to protect the first operational amplifier.

8. The pA-level detection control circuit of the ionization electrostatic detection device according to claim 1, characterized in that, The voltage divider sampling circuit includes a high-voltage voltage divider resistor network, which is connected between the high-voltage output terminal of the high-voltage linear switching circuit and the feedback input terminal of the main control closed-loop control circuit. The high-voltage voltage divider resistor network is used to attenuate the main high-voltage signal into a low-voltage sampling signal at a fixed ratio and feed it back to the main control closed-loop control circuit.

9. The pA-level detection control circuit of an ionization electrostatic detection device according to claim 1, characterized in that, It also includes an isolation power supply circuit, which provides the pA-level detection circuit and the main control closed-loop control circuit with electrical isolation from the high-voltage circuit; the drive boost circuit adopts a single transformer structure to synchronously generate positive and negative high voltage.

10. A performance testing system for an ionization electrostatic eliminator, characterized in that, include: Test plate; A pA-level detection control circuit for an ionization electrostatic detection device as described in any one of claims 1 to 9; The high-voltage output terminal of the pA-level detection control circuit is electrically connected to the detection plate, and is used to construct a continuously adjustable simulated electrostatic environment on the detection plate and acquire its voltage signal.

11. The performance testing system for an ionization electrostatic eliminator according to claim 10, characterized in that, The pA-level detection and control circuit uses a hardware interlock structure to ensure that the positive high voltage branch and the negative high voltage branch are mutually exclusive and cannot be output simultaneously.

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