Direct current electronic load circuit

Abstract

A DC electronic load circuit relates to the technical field of electronic load control. The utility model provides a direct current electronic load circuit which integrates a dissipation MOS tube array, an analog PID loop, a digital integrated control module, a bus electrical parameter sampling and processing module and a WiFi communication module, and realizes a plurality of working modes such as constant current, constant voltage, constant resistance and constant power by accurately controlling the conduction degree of the MOS tube array. The system has the advantages of real-time monitoring, remote control, overvoltage and overcurrent protection, low power consumption design and the like, and an electronic load solution which is high in precision, high in stability and flexible to operate is provided, so that diversified test requirements are met, and the power supply test efficiency and safety are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic load control, in particular to a direct current electronic load circuit. Background Art

[0002] In the field of electronic testing, DC electronic loads are important testing tools, capable of simulating various load conditions to test and verify power supply equipment. Traditional DC electronic loads primarily rely on hardware circuits to control current, voltage, and resistance. Early electronic loads primarily employed analog control techniques, controlling current by adjusting resistors or using transistors. This approach is simple but suffers from limited accuracy, making it difficult to achieve precise current control and fast response. Many traditional electronic loads utilize discrete component designs, such as multiple resistors and transistors to build the load. This design has limitations in terms of integration density, size, and power consumption, hindering multifunctional integration and portability.

[0003] Due to the limitations of analog control, existing electronic loads lack accuracy and stability in current control, especially under dynamically changing load conditions. Furthermore, their discrete component design results in large electronic loads, high power consumption, and difficulty integrating multiple functions, limiting their adaptability to various test scenarios. Utility Model Content

[0004] The purpose of the utility model is to provide a DC electronic load circuit with high precision and good stability.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a DC electronic load circuit, comprising:

[0006] Dissipative MOS tube array, used to simulate controllable power resistor.

[0007] An analog PID loop is connected to the dissipative MOS transistor array and is used to control the MOS transistor array to operate in a linear range.

[0008] A digital integrated control module is connected to the analog PID loop and is used to adjust the analog PID loop through a DAC.

[0009] The busbar electrical parameter sampling and processing module is connected to the power monitoring IC, and is used to read the busbar electrical parameters obtained by filtering and calculating by the power monitoring IC, and pass the processing results to the digital integrated control module.

[0010] The WiFi communication module is connected to the digital integrated control module to realize remote data transmission and debugging functions.

[0011] Preferably, the digital integrated control module includes an ESP32 main control board, which reads the user's set value and switch status from the panel to control the DAC to adjust the analog PID loop.

[0012] More preferably, the processor on the ESP32 main control board is ESP32-C3.

[0013] More preferably, the digital integrated control module is further connected to a serial port screen for displaying voltage and current parameters.

[0014] More preferably, the busbar electrical parameter sampling and processing module includes a differential operational amplifier for measuring differential voltage signals, an INA226 chip for measuring load voltage and current signals, and an MCP4725 digital-to-analog converter for converting digital signals into analog voltage signals.

[0015] Compared to existing technologies, this new technology integrates an analog PID loop with a dissipative MOS transistor array to precisely control load current, maintaining a constant current and improving load control accuracy and stability. Furthermore, the use of a digital integrated control module allows the system to dynamically adjust the analog PID loop via a DAC based on user settings and switch status, achieving intelligent current control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of the DC electronic load circuit in the embodiment;

[0017] Figure 2 This is a structural diagram of a digital integrated control module in an embodiment;

[0018] Figure 3 Schematic diagram of the circuit structure of differential voltage measurement in the embodiment;

[0019] Figure 4 Schematic diagram of the voltage and current measurement circuit structure in the embodiment;

[0020] Figure 5 Schematic diagram of the circuit structure of the digital control signal generating module in the embodiment;

[0021] Figure 6 Schematic diagram of the circuit structure of the hardware constant current control loop in the embodiment. DETAILED DESCRIPTION

[0022] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention.

[0023] like Figure 1 and Figure 2As shown, the DC electronic load circuit of this embodiment is composed of the following main modules:

[0024] Dissipative MOS tube array: The array simulates a controllable power resistor and dynamically adjusts its conduction level according to the instructions of the main control unit to control the current flowing through the load.

[0025] Analog PID loop: connected to the dissipative MOS tube array, used to control the MOS tube array to operate in the linear range. The loop receives instructions from the digital integrated control module and adjusts the working state of the MOS tube array to maintain the stability of parameters such as current and voltage.

[0026] The digital integrated control module is connected to the analog PID loop, with ESP32 as the main control chip. The analog PID loop is adjusted through DAC to achieve precise control of the MOS tube array.

[0027] The busbar electrical parameter sampling and processing module uses the INA226 power monitoring IC to sample the busbar voltage and current, and transmits the sampled data to the ESP32 through the I2C bus for processing.

[0028] The WiFi communication module is connected to the digital integrated control module to realize remote data transmission and debugging functions, allowing users to remotely control and monitor the status of the electronic load circuit through the network.

[0029] The busbar electrical parameter sampling and processing module includes a differential operational amplifier for measuring differential voltage signals, an INA226 chip for measuring load voltage and current signals, and an MCP4725 digital-to-analog converter for converting digital signals into analog voltage signals. The circuit structure of each part is as follows:

[0030] like Figure 3 As shown, a differential operational amplifier (INA143) achieves precise differential voltage signal measurement, enabling differential signal extraction of high common-mode signals. A G6K-2F-Y-TR DC5 signal relay is then used to control the differential op amp's input source by switching it high or low. This is then fed into an INA226 for ADC conversion and digital output.

[0031] like Figure 4 As shown in the figure, based on the INA226 chip, the load voltage and current signals are measured with high precision and the data is transmitted to the main control chip through the I2C interface. When the current or voltage exceeds the preset threshold, the INA226 issues an alarm through the ALERT pin.

[0032] like Figure 5As shown, an MCP4725 digital-to-analog converter converts a digital signal (controlled via I²C) into an analog voltage. This analog voltage is conditioned by an operational amplifier and can be used to control downstream circuits. The operational amplifier (TLV07) is configured as a buffer and adjustable gain circuit to amplify or adjust the DAC output signal. Ultimately, the conditioned analog signal is output to the control terminal.

[0033] like Figure 6 As shown in the figure, U9 and potentiometer PR3 set a reference voltage (CV), which determines the target current. The load current flows through sampling resistor R23, generating a voltage across it that is proportional to the current. U7 compares the sampled voltage with the reference voltage and adjusts the output signal to control the conduction level of the MOSFET, thereby regulating the load current in real time. Through the feedback loop, the MOSFET's conduction state is continuously adjusted, ultimately stabilizing the load current at the target value.

[0034] The operating procedure and principle of the DC electronic load circuit provided in the above embodiment are as follows: First, connect the DC electronic load's power port to an appropriate DC power supply, ensuring that the input voltage range is within the system's design tolerances. Then, connect the device under test (such as a power adapter or battery) to the load input, ensuring a secure connection. Wait for the serial port screen to light up and connect to the network (optional). The system will complete initialization and display default parameters.

[0035] After the system boots up, the ESP32 main control unit reads user settings and switch status from the front panel. Users set desired current, voltage, and other parameters using the physical buttons and knobs on the panel. Specifically, they can switch between constant current (CC), constant voltage (CV), constant resistance (CR), and constant power (CW) modes using the physical buttons. Then, they rotate the knob to set the target parameter (e.g., V, A, Ω, W). The serial port screen displays the set value in real time. Once the system enters run mode, the serial port display shows real-time information such as load voltage, current, and power. Operational status can be monitored and adjusted from a computer using RS-485 or UDP over WiFi.

[0036] During operation, the digital integrated control module sends control signals to the analog PID loop via the DAC based on user-set parameters. Based on the control signals, the analog PID loop adjusts the conduction level of the MOS transistor array to control the load current to the set value. The INA226 power monitoring IC samples the bus voltage and current in real time and transmits the data to the ESP32 for processing. The processed data is displayed on the serial port screen, allowing users to monitor system status in real time. The WiFi communication module allows users to remotely monitor and adjust system parameters.

[0037] The system also has a protection function. First, when an abnormality is detected (such as overvoltage, overcurrent, or overtemperature), the system automatically disconnects the load, reports an alarm to each communication interface, and stops the load. Then, according to the prompts, the system is restarted after checking and eliminating the abnormality.

[0038] The DC electronic load circuit in this embodiment supports four operating modes: constant current (CC), constant voltage (CV), constant resistance (CR), and constant power (CW), meeting diverse testing requirements. It supports real-time adjustment of load parameters, making it suitable for dynamic testing scenarios. High-precision signal acquisition is achieved primarily by sampling and converting the electrical parameters on the negative bus using the INA226 monitoring IC. This data is then transmitted to the main control unit (ESP32) via an isolated I2C bus for processing. Furthermore, this circuit structure is equipped with a color serial port display for real-time display of important parameters such as voltage and current. Users can conveniently set parameters and switch modes using a variety of methods: touchscreen buttons, knobs, and panel buttons.

[0039] Considering scalability and modularity, the circuit system also features multiple I / O ports, communication interfaces, and key circuits that can be easily disconnected via jumper nodes, facilitating testing and expanding hardware functionality. It also supports OTA (Over-the-Air) technology, facilitating external firmware updates and convenient feature upgrades. It also supports automatic sleep after extended periods of no input and one-touch wake-up to meet low-power requirements. It also supports USB Type-C PD power delivery and AC200V power supply, adapting to various working environments. Both power inputs are fully protected and filtered, ensuring extremely high power supply stability and low output ripple.

[0040] This utility model patent proposes a DC electronic load circuit that integrates a dissipative MOS tube array, an analog PID loop, a digital integrated control module, a bus electrical parameter sampling and processing module, and a WiFi communication module. By precisely controlling the conduction degree of the MOS tube array, it achieves multiple operating modes such as constant current, constant voltage, constant resistance, and constant power. It has the advantages of real-time monitoring, remote control, overvoltage and overcurrent protection, and low power consumption design. It provides a high-precision, high-stability, and flexible operation electronic load solution to meet diverse testing needs and improve the efficiency and safety of power supply testing.

[0041] In order to make it easier for ordinary technicians in this field to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and the above-mentioned embodiments are better implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the scope of protection of the present invention.

Claims

1. A DC electronic load circuit, characterized in that: include: Dissipative MOS tube array, used to simulate controllable power resistor; An analog PID loop is connected to the dissipative MOS transistor array and is used to control the MOS transistor array to operate in a linear range; a digital integrated control module connected to the analog PID loop and configured to adjust the analog PID loop via a DAC; The busbar electrical parameter sampling and processing module is connected to the power monitoring IC and is used to read the busbar electrical parameters obtained by filtering and calculating by the power monitoring IC, and transmit the processing results to the digital integrated control module; The WiFi communication module is connected to the digital integrated control module to realize remote data transmission and debugging functions.

2. The DC electronic load circuit according to claim 1, wherein: The digital integrated control module includes an ESP32 main control board, which reads the user's set value and switch status from the panel to control the DAC to adjust the analog PID loop.

3. The DC electronic load circuit according to claim 2, wherein: The processor on the ESP32 main control board is ESP32-C3.

4. The DC electronic load circuit according to claim 1, wherein: The digital integrated control module is also connected to a serial port screen for displaying voltage and current parameters.

5. The DC electronic load circuit according to claim 1, wherein: The busbar electrical parameter sampling and processing module includes a differential operational amplifier for measuring differential voltage signals, an INA226 chip for measuring load voltage and current signals, and an MCP4725 digital-to-analog converter for converting digital signals into analog voltage signals.

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