Automatic range measuring device and measuring method for electrochemical workstation

Abstract

The present invention provides an automatic range measurement device and a measurement method for an electrochemical workstation. The device of the present invention comprises an ARM connected to a PC, an FPGA, a signal source module inside the electrochemical workstation, a low-pass filter, a voltage acquisition module, a current acquisition module, and a DSP. The method of the present invention comprises: step 1: the signal source module applies an excitation signal to the sample system, the voltage / current acquisition module converts the analog signal fed back by the sample into a digital signal, and after DSP analysis and processing, obtains real-time data and transmits it to the ARM; step 2: the ARM makes a real-time judgment on the range selection according to the data signal; step 3: the range is automatically switched; the ARM sends a command signal to the FPGA, and the FPGA sends a command to switch the circuit range. This method can collect more accurate signals, and feedback the reaction state of the sample system under excitation in real time, so as to facilitate electrochemical researchers to obtain accurate and reliable data from the measurement of the sample system.

Description

[0001] Technical field: The present invention relates to an automatic range measuring device and a measuring method for an electrochemical workstation, belonging to the technical field of circuit electronic design.

[0002] Background technology: Electrochemical workstations are widely used in electrical analysis, corrosion, impedance measurement and energy fields. In the past, due to the violent reaction of electroanalysis and the low requirement for small signals, automatic range was generally not used. However, with the rise of corrosion and impedance fields in recent years, the demand for small signals is higher, and the signal span of system feedback is larger. If a fixed range is used, the data error will be large, and the measurement results will be inaccurate, so a new technology is needed to solve the above problems.

[0003] However, the electrochemical workstations currently on the domestic market have large errors in data processing and curve drawing, so the improvement of data accuracy during the measurement process requires automatic ranging. The automatic ranging measurement system has the characteristics of real-time and high precision, which is a technical improvement for the complex measurement system of the electrochemical workstation.

[0004] SUMMARY OF THE INVENTION: The purpose of the present invention is to provide an automatic range measurement device and a measurement method for an electrochemical workstation to solve the above-mentioned problems, so as to facilitate electrochemical researchers to obtain accurate and reliable data from the measurement of sample systems.

[0005] An automatic range measurement device for an electrochemical workstation, comprising a microprocessor (ARM) connected to a PC, a control module FPGA, a signal source module inside the electrochemical workstation, a low-pass filter, a voltage acquisition module, a current acquisition module, and a sampling digital signal processing module (DSP); the microprocessor (ARM) is used to receive instructions from the PC and send them to the control module (FPGA);

[0006] The control module (FPGA) is used to receive the signal of the microprocessor ARM, and after logic processing, select the signal source module inside the electrochemical workstation to apply an excitation signal to the sample system;

[0007] The low-pass filter is used to filter the voltage and current analog signals responded by the sample system;

[0008] The voltage acquisition module is used to convert the filtered voltage signal into a digital signal and transmit it to the sampling digital signal processing module (DSP) for analysis;

[0009] The current acquisition module is used to convert the filtered current signal into a digital signal and transmit it to the sampling digital signal processing module (DSP) for analysis;

[0010] The sampling digital signal processing module (DSP) is used to upload the processed voltage and current data to the PC via the microprocessor (ARM) via Ethernet.

[0011] The automatic range measuring device for an electrochemical workstation is characterized in that the microprocessor (ARM) adopts an STM32F405RGT6 microprocessor; the control module (FPGA) adopts an EP4CGX30 FPGA; the sampling digital signal processing module (DSP) adopts TI's TSM320C6727B chip; the signal source module adopts a DAC8771 single-channel 16-bit voltage output digital-to-analog converter; the low-pass filter adopts an LTC1069-7 8th-order low-pass filter; and the voltage acquisition module and the current acquisition module both use the AD7798 chip.

[0012] A method for performing automatic range measurement of an electrochemical workstation using the automatic range measurement device of the electrochemical workstation, the method comprising the following steps: Step 1: Collecting analog signals fed back by the sample system to obtain real-time data: the PC sends a command signal to the microprocessor (ARM) through the Ethernet interface, and the microprocessor (ARM) transmits it to the control module (FPGA), and through logic processing, selects the circuit gear in the signal source module, so that the signal source module inside the electrochemical workstation applies an excitation signal to the sample system, and the voltage and current analog signals responded by the sample system are filtered by a low-pass filter, and the A / D chips in the voltage acquisition module and the current acquisition module respectively convert the filtered analog signals into digital signals, which are transmitted to the sampling digital signal processing module (DSP) for analysis, and the processed voltage and current data are uploaded to the PC through the microprocessor (ARM) via Ethernet;

[0013] Step 2: Select the range based on real-time judgment of data: The voltage signal and current signal acquired by the voltage acquisition module and the current acquisition module are analyzed and processed by the sampling digital signal processing module (DSP) and transmitted to the microprocessor (ARM). Then, the microprocessor (ARM) logic determines the range required for the next signal based on the percentage of the data size in the current range;

[0014] Step 3: Automatically switch the range: After the microprocessor (ARM) logic determines the range to be selected, the microprocessor (ARM) sends a command signal to the control module (FPGA), and the control module (FPGA) sends instructions to switch the switch position of the circuit to select the circuit range. The sample feedback signal then enters the host computer for analysis and processing, and real-time data analysis transmission and range switching are performed, and data is displayed in real time and graphs are drawn.

[0015] As a preferred technical solution: the method described in step 1 of making the signal source module inside the electrochemical workstation apply an excitation signal to the sample system is set in the software configured in the electrochemical workstation, and the sample system is established as a four-electrode system model, which includes a working electrode, a reference electrode, an auxiliary electrode, and a sensing electrode.

[0016] As a preferred technical solution: In the process of determining the range required for the next signal by the microprocessor (ARM) logic as described in step 2, the signal needs to be filtered to obtain a real signal. When comparing signal data, the currently collected data is compared with the percentage of the current full scale.

[0017] As a preferred technical solution: the signal is filtered by a filter circuit, the filter circuit adopts LTC1XXX linear phase low-pass filter, different filter gears are selected for different signal frequencies, and the selected filter gear is greater than 10 times the sampling signal frequency.

[0018] As a preferred technical solution: when comparing signal data, the optimal interval of percentage to be considered is 5% 95%.

[0019] Beneficial effects: The present invention can collect more accurate signals and provide real-time feedback on the reaction state of the sample system under stimulation, making it easier for electrochemical researchers to obtain accurate and reliable data from the measurement of the sample system.

[0020] In actual operation, users no longer need to set different current ranges for different measurement systems. Instead, the software interface directly sets the Auto range option, which is convenient and fast, and improves the efficiency of equipment use.

[0021] Description of the drawings: Figure 1 Block diagram of the overall system for signal output, acquisition and control of the electrochemical workstation.

[0022] Figure 2 D / A output circuit diagram.

[0023] Figure 3 Flow chart of range selection based on real-time judgment of data analysis.

[0024] Figure 4 Automatic range switching measurement flow chart.

[0025] Figure 5 Filter circuit diagram.

[0026] Figure 6 The Tafel polarization diagram of copper electrode in NaCl (3.5 wt.%) solution was tested with fixed current range (10 mA) and automatic current range.

[0027] Figure 7Fixed current range (1 mA) and automatic current range are used to test the electrochemical impedance of high resistance simulated electrolytic cells.

[0028] Specific implementation method: Figure 1 As shown, the automatic range measuring device for an electrochemical workstation of the present invention comprises a microprocessor (ARM) connected to a PC, a control module FPGA, a signal source module inside the electrochemical workstation, a low-pass filter, a voltage acquisition module, a current acquisition module, and a sampling digital signal processing module (DSP);

[0029] The microprocessor (ARM) is used to receive instructions from the PC and send them to the control module (FPGA);

[0030] The control module (FPGA) is used to receive the signal of the microprocessor ARM, and after logic processing, select the signal source module inside the electrochemical workstation to apply an excitation signal to the sample system;

[0031] The low-pass filter is used to filter the voltage and current analog signals responded by the sample system;

[0032] The voltage acquisition module is used to convert the filtered voltage signal into a digital signal and transmit it to the sampling digital signal processing module (DSP) for analysis;

[0033] The current acquisition module is used to convert the filtered current signal into a digital signal and transmit it to the sampling digital signal processing module (DSP) for analysis;

[0034] The sampling digital signal processing module (DSP) is used to upload the processed voltage and current data to the PC through the microprocessor (ARM) via Ethernet. Figure 1 , the dotted arrows are control transmission lines, and the solid arrows are signal or data transmission lines. See the D / A output circuit diagram in the signal source module. Figure 2 .

[0035] The microprocessor (ARM) in this embodiment is an STM32F405RGT6 microprocessor, which achieves high integration, high performance, and embedded memory in a package as small as 4*4.2mm.

[0036] The control module (FPGA) in this embodiment: the fourth generation of the Cyclone series of Altera, model EP4CGX30, is selected. Advantages: The Cyclone IV series is the industry's lowest cost and lowest power FPGA. This model has eight integrated 3.125Gbps transceivers and supports a variety of serial I / O protocols. It contains an embedded PCIe hard-core IP module that does not occupy any FPGA logic, and this model has a larger storage unit, a faster data processing unit, a higher data rate, more I / O, and supports commercial and industrial temperature grades.

[0037] The sampling digital signal processing module (DSP) in this embodiment uses TI's TMS320C6727B chip. TMS320C6727B is a 350MHz high-performance floating-point DSP chip launched by Texas Instruments. The device is fully code compatible with TI's scalable floating-point DSP series. C6727B provides 32 external storage interfaces. Compared with TMS320C6720B, the speed of SDRAM has been increased from 100 MHz to 133MHz, achieving a 33% speed increase, improving flexibility and scalability, and greatly increasing the number of channels that DSP can process. TMS320C6720B has 256K on-chip RAM, 32KB instruction cache and 384KBROM. The ROM is preloaded with the real-time DSP kernel DSP / BIOS. It also provides an optimized DSP library including commonly used functions. The device also uses a DMAXDMA engine, which can perform 1D, 2D and 3D memory transfers, allowing the DSP to focus on signal processing tasks and significantly improve system performance.

[0038] The signal source module in this embodiment uses a DAC8771 single-channel 16-bit voltage output digital-to-analog converter, which is a single-channel precision fully integrated 16-bit digital-to-analog converter (DAC) with an adaptive power management function.

[0039] The low-pass filter in this embodiment: LTC1069-7 8th-order low-pass filter is selected to make the filtering closer to the theoretical value, the cut-off frequency band becomes steeper, and the filtering effect is better. The voltage acquisition module (AD1) in this embodiment: AD7798 chip is selected, which is a low-power, low-noise, complete analog front end suitable for high-precision measurement applications, with a built-in low-noise, 16-bit Σ-Δ ADC with three differential analog inputs. It also integrates an on-chip low-noise instrument amplifier, so small signals can be directly input.

[0040] The current acquisition module (AD2) in this embodiment uses the AD7798 chip, which is a low-power, low-noise, complete analog front end suitable for high-precision measurement applications. It has a built-in low-noise, 16-bit Σ-Δ ADC with three differential analog inputs. It also integrates an on-chip low-noise instrumentation amplifier, so it can directly input small signals.

[0041] A method for performing automatic range measurement of an electrochemical workstation using the automatic range measurement device of the electrochemical workstation, the method comprising the following steps: Step 1: Collecting analog signals fed back by the sample system to obtain real-time data: the PC sends a command signal to the microprocessor (ARM) through the Ethernet interface, and the microprocessor (ARM) transmits it to the control module (FPGA), and through logic processing, selects the circuit gear in the signal source module, so that the signal source module inside the electrochemical workstation applies an excitation signal to the sample system, and the voltage and current analog signals responded by the sample system are filtered by a low-pass filter, and the A / D chips in the voltage acquisition module and the current acquisition module respectively convert the filtered analog signals into digital signals, which are transmitted to the sampling digital signal processing module (DSP) for analysis, and the processed voltage and current data are uploaded to the PC through the microprocessor (ARM) via Ethernet;

[0042] Step 2: Select the range based on real-time judgment of data: The voltage signal and current signal acquired by the voltage acquisition module and the current acquisition module are analyzed and processed by the sampling digital signal processing module (DSP) and transmitted to the microprocessor (ARM). Then, according to the percentage of the data size in the current range, the microprocessor (ARM) logic determines the range required for the next signal; see the specific process Figure 3

[0043] Step 3: Automatic range switching: After the microprocessor (ARM) logic determines the range to be selected, the microprocessor (ARM) sends a command signal to the control module (FPGA), and the control module (FPGA) sends a command to the switch position of the switching circuit to select the circuit range size. The sample feedback signal then enters the host computer for analysis and processing, real-time data analysis transmission and range switching, real-time display of data and drawing of graphics. For specific procedures, see Figure 4 .

[0044] As a preferred technical solution: the method described in step 1 for making the signal source module inside the electrochemical workstation apply an excitation signal to the sample system is set in the software configured in the electrochemical workstation. The sample system is established as a four-electrode system model, that is, a sensing electrode SE is added to the original three-electrode system (WE: working electrode; RE: reference electrode; CE: auxiliary electrode) model, in order to eliminate contact impedance and wire resistance.

[0045] As a preferred technical solution: In the process of determining the range required for the next signal by the microprocessor (ARM) logic as described in step 2, since the interference signal in the real signal will affect the selection of the actual range, it is necessary to filter the data to obtain the real signal. When comparing the signal data, the currently collected data is compared with the percentage of the current full range, so as to achieve the purpose of optimal range judgment.

[0046] As a preferred technical solution: the signal is filtered by a filter circuit, and the filter circuit adopts LTC1069-7 linear phase low-pass filter. Advantages: the 8th-order low-pass filter makes the filtering closer to the theoretical value, the cut-off frequency segment becomes steeper, and the filtering effect is better. Different filter gears are selected for different signal frequencies, and the selected filter gear is greater than 10 times the sampling signal frequency.

[0047] As a preferred technical solution: when comparing signal data, the optimal interval of percentage to be considered is 5% 95%.

[0048] This method was used in the DH7001 electrochemical workstation to test the Tafel polarization of the copper electrode in NaCl (3.5 wt.%) solution (open circuit potential of -50 mV; initial potential of -250 mV, final potential of 250 mV, scan rate of 5 mV / s. Working electrode: copper electrode, reference electrode: saturated calomel electrode, counter electrode: platinum electrode.) and the electrochemical AC impedance of the high-resistance simulated electrolytic cell (scan start frequency 1000000 Hz, end frequency 0.01 Hz, amplitude 10 mV). The Tafel polarization of the copper electrode in NaCl (3.5 wt.%) solution (the parameters of the Tafel polarization experiment are exactly the same as those mentioned above) and the electrochemical AC impedance of the high-resistance simulated electrolytic cell (the parameters of the AC impedance experiment are exactly the same as those mentioned above) were tested with a fixed range for comparison. The results are shown in the figure. Figure 6 and Figure 7 As shown, Figure 6 The Tafel polarization of copper electrode in NaCl (3.5 wt.%) solution was tested. The results showed that the curve measured by automatic current range was smoother and free of burrs than that by fixed current range (10 mA), and the data was more accurate. Figure 7 The electrochemical AC impedance of a high-resistance simulated electrolytic cell was tested using a fixed current range (1 mA) and an automatic current range. The results showed that the curve measured by the automatic current range was smoother and the data was more accurate than that by the fixed current range (1 mA) in the low-frequency range (especially when the frequency was below 1 Hz).

[0049] The test results show that this method can not only automatically select and switch the range according to the size of the current value, so that the range of the measured current value is wider, but also can collect more accurate signals, and provide real-time feedback on the reaction state of the sample system under stimulation, so as to facilitate electrochemical researchers to obtain accurate and reliable data for the measurement of the sample system. The above implementation is only for the purpose of clearly illustrating the description of the present invention, and is not a limitation on the implementation method. For technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for automatic range measurement of an electrochemical workstation, characterized in that: The device used in the method includes a microprocessor ARM connected to a PC, a control module FPGA, a signal source module inside an electrochemical workstation, a low-pass filter, a voltage acquisition module, a current acquisition module, and a sampling digital signal processing module DSP; the microprocessor ARM is used to receive instructions from the PC and send them to the control module FPGA; The control module FPGA is used to receive the signal of the microprocessor ARM, and after logic processing, select the signal source module inside the electrochemical workstation to apply an excitation signal to the sample system; The low-pass filter is used to filter the voltage and current analog signals responded by the sample system; The voltage acquisition module is used to convert the filtered voltage signal into a digital signal and transmit it to the sampling digital signal processing module DSP for analysis; The current acquisition module is used to convert the filtered current signal into a digital signal and transmit it to the sampling digital signal processing module DSP for analysis; The sampling digital signal processing module DSP is used to upload the processed voltage and current data to the PC through the microprocessor ARM via Ethernet, wherein: The method for automatic range measurement of an electrochemical workstation includes the following steps: Step 1: Collecting analog signals fed back by a sample system to obtain real-time data: a PC sends a command signal to a microprocessor ARM through an Ethernet interface, and the microprocessor ARM transmits the command signal to a control module FPGA. Through logic processing, the circuit gear in a signal source module is selected, so that the signal source module inside the electrochemical workstation applies an excitation signal to the sample system. The voltage and current analog signals responded by the sample system are filtered through a low-pass filter, and the A / D chips in the voltage acquisition module and the current acquisition module respectively convert the filtered analog signals into digital signals, which are transmitted to the sampling digital signal processing module DSP for analysis, and the processed voltage and current data are uploaded to the PC through the microprocessor ARM via Ethernet; Step 2: Select the range based on real-time judgment of data: The voltage signal and current signal acquired by the voltage acquisition module and the current acquisition module are analyzed and processed by the sampling digital signal processing module DSP and transmitted to the microprocessor ARM. Then, the microprocessor ARM logic determines the range required for the next signal based on the percentage of the data size in the current range; Step 3: Automatically switch the range: After the microprocessor ARM logic determines the range to be selected, the microprocessor ARM sends a command signal to the control module FPGA, and the control module FPGA sends instructions to the switch position of the switching circuit to select the circuit range size. The sample feedback signal then enters the host computer for analysis and processing, and performs real-time data analysis and transmission and range switching, and displays data in real time and draws graphs.

2. The automatic range measurement method for an electrochemical workstation according to claim 1, characterized in that: The microprocessor ARM adopts the STM32F405RGT6 model microprocessor; the control module FPGA adopts the EP4CGX30 model FPGA; the sampling digital signal processing module DSP adopts TI's TMS320C6727B chip; the signal source module adopts TI's DAC8771 single-channel 16-bit voltage output digital-to-analog converter; the low-pass filter adopts the LTC1069-7 8th-order low-pass filter; the voltage acquisition module and the current acquisition module both use the AD7798 chip.

3. The method for automatic range measurement of an electrochemical workstation according to claim 1, characterized in that: The method described in step 1 for making the signal source module inside the electrochemical workstation apply an excitation signal to the sample system is set in the software configured in the electrochemical workstation. The sample system is established as a four-electrode system model, which includes a working electrode, a reference electrode, an auxiliary electrode and a sensing electrode.

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