Handheld large-current constant current source

Abstract

The invention provides a handheld large-current constant current source. The handheld large-current constant current source comprises a battery, a main controller, a database, a current-type DAC, a step-down voltage stabilizer, a driver, a bridge switch, a load, a current sampling module, a constant current module, an ADC and a temperature control unit, the battery is respectively connected with the main controller and the current type DAC and is used for supplying power; the output end of the main controller is connected with the input end of the database; the output end of the database is connected with the input end of the current type DAC; the output end of the step-down voltage stabilizer is respectively connected with the temperature control unit and the bridge switch; the output end of the bridge switch is connected with the input end of the load; the output end of the load is connected with the input end of the current sampling module, and the output end of the current sampling module is connected with the constant current module; the output end of the constant current module is connected with the battery, and the output end of the ADC is connected with the main controller. And higher precision can be realized while the output current range is larger.

Description

Technical Field

[0001] The invention relates to the field of current constant current sources, and in particular to a handheld large current constant current source. Background Art

[0002] The existing portable industrial frequency constant current source device has similar functions, and the output signal is AC current, which cannot meet the application scenarios of this solution, and no actual product has been seen.

[0003] The existing technology uses lithium battery + DCDC for power supply. The controller controls the constant current circuit to output to the load. The load and the current sampling circuit are connected in series in the loop. The sampling circuit and the constant current circuit form a closed loop to achieve constant current. The control circuit converts the signal of the sampling circuit into a digital signal and displays it on the LCD to be touched. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide a handheld large current constant current source that overcomes the above problems or at least partially solves the above problems.

[0005] According to one aspect of the present invention, a handheld large current constant current source is provided, the current constant current source comprising:

[0006] Battery, main controller, database, current DAC, buck regulator, driver, bridge switch, load, current sampling module, constant current module, ADC and temperature control unit;

[0007] The battery is connected to the main controller and the current-type DAC respectively to provide power;

[0008] The output end of the main controller is connected to the input end of the database, and is used to set the output current signal through human-computer interaction, search the corresponding logic in the database, and control the output of the current-type DAC;

[0009] The output end of the database is connected to the input end of the current-mode DAC;

[0010] The output end of the current-mode DAC is connected to the input end of the buck regulator to control the output voltage of the buck regulator;

[0011] The output end of the buck regulator is connected to the temperature control unit and the bridge switch respectively;

[0012] The output end of the bridge switch is connected to the input end of the load;

[0013] The output end of the load is connected to the input end of the current sampling module, and the output end of the current sampling module is connected to the constant current module;

[0014] The output end of the constant current module is connected to the battery to control the current of the loop where the load is located to the output current value set in the human-computer interaction;

[0015] The driver is connected to the bridge switch and the main controller respectively, and the main controller controls the bridge switch through the driver;

[0016] The main controller changes the current direction in the load by controlling the upper half bridge or the lower half bridge of the bridge switch to be turned on;

[0017] The current sampling module is connected to the input end of the ADC, and the output end of the ADC is connected to the main controller.

[0018] Optionally, the battery is a lithium battery.

[0019] Optionally, the database stores a relationship table between the IDAC output current and the buck regulator output voltage, and stores whole machine calibration data.

[0020] Optionally, the buck regulator reduces the battery voltage to a voltage value required by the load at a set current value.

[0021] Optionally, the current sampling module is a fluxgate current sensor DCCT, which converts a large current into a voltage signal received by the constant current module.

[0022] Optionally, the ADC collects the voltage that the DCCT gives to the constant current module, calculates and displays the actual output current value of the loop where the load is located; collects the voltage across the load, calculates the load resistance value, and is used to enable the controller to control the buck regulator to increase the output voltage when the set voltage is increased, thereby ensuring that the output of the buck regulator can enable the loop where the load is located to achieve constant current.

[0023] Optionally, the temperature control unit collects the temperature of the bridge switch, the constant current module, and the inside of the entire machine, and dynamically adjusts the output voltage of the buck regulator and shuts down the output.

[0024] The present invention provides a handheld large current constant current source, which comprises: a battery, a main controller, a database, a current type DAC, a buck regulator, a driver, a bridge switch, a load, a current sampling module, a constant current module, an ADC and a temperature control unit; the battery is respectively connected to the main controller and the current type DAC to provide power; the output end of the main controller is connected to the input end of the database; the output end of the database is connected to the input end of the current type DAC; the output end of the current type DAC is connected to the input end of the buck regulator; the output ends of the buck regulator are respectively connected to The temperature control unit is connected to the bridge switch; the output end of the bridge switch is connected to the input end of the load; the output end of the load is connected to the input end of the current sampling module, and the output end of the current sampling module is connected to the constant current module; the output end of the constant current module is connected to the battery; the driver is connected to the bridge switch and the main controller respectively; the main controller changes the current direction in the load by controlling the upper half bridge or the lower half bridge of the bridge switch to be turned on; the current sampling module is connected to the input end of the ADC, and the output end of the ADC is connected to the main controller. Higher accuracy can be achieved while the output current range is larger.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the structure of a handheld high-current constant-current source provided by an embodiment of the present invention;

[0028] Figure 2 A circuit structure diagram of a handheld high-current constant-current source provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0030] The terms "comprises" and "having" and any variations thereof in the description embodiments, claims and drawings of the present invention are intended to cover non-exclusive inclusions, for example, including a series of steps or units.

[0031] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] The purpose of the present invention is to provide a handheld constant current large current source to solve the rigid demand problem of current sensors / transformers in field experiments, online measurement and other scenarios. The current handheld constant current sources are mostly 4mA~20mA process calibrators with small output signals. They simulate the secondary output signal of the current sensor to measure the sampling device of the back stage, and cannot simulate a large range of primary current.

[0033] like Figure 1 As shown, the present invention provides a handheld constant current large current source, including: a lithium battery, a main controller, a database, a current type DAC, a buck regulator, a driver, a bridge switch, a load, a current sampling module, a constant current module, an ADC and a temperature control unit.

[0034] Lithium battery: provides continuous discharge power, and its output end is connected to the main controller and current type DAC respectively.

[0035] Main controller: It includes control logic, human-computer interaction logic, etc. It searches the database for corresponding logic through the output current signal size set by human-computer interaction, controls the output of the current-type digital-to-analog converter IDAC, controls the output voltage of the buck regulator, and adjusts the output power and the power consumption of the whole machine;

[0036] The input end is connected to the ADC to control the ADC to collect the load voltage, calculate the load resistance and the output signal size set by human-computer interaction, so as to dynamically adjust the output size of the current-type digital-to-analog converter IDAC and control the power consumption of the whole machine within a certain range;

[0037] The input terminal is also connected to the output terminal of the driving source;

[0038] Database: connected to the output end of the main controller, storing the relationship table between the IDAC output current and the buck regulator output voltage, and storing the whole machine calibration data;

[0039] Current-mode DAC: Outputs current to the buck regulator to adjust the output voltage of the buck regulator;

[0040] Buck regulator: reduces the battery voltage to the voltage required by the load at the set current value;

[0041] Driver: The main controller controls the bridge switch through the driver

[0042] Bridge switch: The main controller changes the current direction in the load by controlling the upper or lower half of the bridge switch to conduct.

[0043] Load: The load is the current receiving unit of this portable constant current source, which is the current line for calibrating the perforated current transformer, or a low-value resistor, etc.

[0044] Current sampling module: fluxgate current sensor (DCCT), converts large current into a voltage signal that the constant current module can accept;

[0045] Constant current module: controls the current of the load circuit to the output current value set by the human-computer interaction module;

[0046] ADC: collects the voltage from DCCT to the constant current module, calculates and displays the actual output current value of the load path;

[0047] The voltage across the load is collected and the load resistance value is calculated so that the controller can control the buck regulator to increase the output voltage when the set voltage increases, thereby ensuring that the buck regulator output can achieve constant current in the circuit where the load is located;

[0048] Temperature control unit: collects the temperature of the bridge switch, constant current module, and the entire machine, dynamically adjusts the output voltage of the buck regulator and shuts down the output to ensure that the entire machine does not exceed the temperature acceptable to human hands.

[0049] like Figure 2 As shown, a handheld constant current large current source, the specific circuit structure includes:

[0050] Battery BT, main controller U3, IDAC U2, buck regulator U1, driver U4, constant current module (U5, A1, Q5), current sampling module DCCT, ADC1 (U6), ADC2 (U7), bridge switch (Q1~Q4), load RL.

[0051] The positive terminal of the battery is connected to the buck regulator U1, and the negative terminal is grounded.

[0052] The main controller U3 receives the set current information, controls IDAC U2 to adjust the output voltage of the buck regulator U1 to the maximum output voltage, controls U4 to drive the half-bridge to switch to the set current value direction which is the same as the set current direction, and then the main controller U3 controls DAC to output a voltage value to drive the closed feedback loop composed of A1, R8, C1, Q5 and DCCT to obtain a constant current of 1 / 10 of the set current value, and the constant current passes through the current sampling module DCCT into ADC1 (U6), ADC1 (U6) converts the voltage into a digital signal, and the main controller U3 obtains the digital signal to calculate I1.

[0053] At the same time, the main controller U3 controls ADC2 (U7) to read the voltage V1 on the load resistor RL to obtain the resistance value of the load. The resistance value is multiplied by the set current value and then added to the voltage drop of Q1~Q5 to calculate the minimum voltage value required by the load circuit under the set current. The output voltage of the buck regulator U1 is set to be slightly larger than the minimum voltage value, thereby reducing the system's additional losses, reducing heat, and increasing system operating time and other availability.

[0054] When the main controller U3 outputs the set current, the main controller U3 reads the database data and controls the DAC (U5) to output a voltage value close to the final balance. At this time, A1 is the error amplifier. The DAC (U5) output voltage is compared with the current sampling module DCCT output voltage. If the current sampling module DCCT output current is smaller than the DAC (U5) output voltage, A1 controls the gate voltage of Q5 to increase, the current of the load-carrying loop increases, and the current sampling module DCCT output voltage increases until it is equal to the DAC (U5) output voltage.

[0055] If the output current of the current sampling module DCCT is greater than the output voltage of DAC (U5), A1 controls the gate voltage of Q5 to decrease, the current in the load loop decreases, and the output voltage of the current sampling module DCCT decreases until it is equal to the output voltage of DAC (U5), achieving dynamic balance.

[0056] The main controller MCU (U3) controls ADC1 (U6) to read the output voltage of the current sampling module DCCT, and compares the calculated actual output value with the set voltage value;

[0057] If the actual current is smaller than the set current, the PID algorithm in the main controller MCU (U3) will control the voltage of DAC (U5) to increase, and the closed-loop system where A1, Q1, and the current sampling module DCCT are located will increase the actual output current so that the actual output current is equal to the set current;

[0058] If the actual current is greater than the set current, the PID algorithm in the main controller MCU (U3) will control the voltage of DAC (U5) to decrease, and the closed-loop system where A1, Q1, and the current sampling module DCCT are located will reduce the actual output current, so that the actual output current is equal to the set current, and re-enter dynamic balance to obtain a constant current equal to the set current.

[0059] The temperature control unit turns on the micro fan when the internal temperature of the constant current source reaches a certain temperature, and turns off the output when the maximum set temperature limit is exceeded to protect the system from being burned; when the temperature is lower than a certain temperature, the fan is turned off to save energy.

[0060] Lithium batteries also use supercapacitors or external power adapters.

[0061] The current measurement module uses current sensing devices such as fluxgate current sensor, Hall current sensor, shunt, etc.

[0062] The bridge switch uses low on-resistance MOSFET and other semiconductor / non-semiconductor devices with switching capabilities.

[0063] Through special design, the required voltage is calculated by measuring the load resistance, and the output voltage of the buck regulator is adjusted with IDAC U2 to ensure maximum utilization of the system output power; switching devices with smaller on-resistance are selected to reduce dissipated power and reduce the system's heating capacity, thereby achieving miniaturization.

[0064] Using the current sampling module DCCT as the current measurement unit, compared with the shunt, there is no additional resistive device in series in the loop, which can enable the system to operate at a lower voltage and further reduce the dissipated power.

[0065] The use of a digital + analog dual closed-loop architecture allows the system to have higher accuracy and stability, and will not become unbalanced due to an increase in internal temperature during operation.

[0066] Expand the battery capacity and connect MOSFETs in parallel to achieve greater current output capability and standby capability.

[0067] Beneficial effect: The present invention provides a portable DC constant current source, which has a DC output capacity greater than that of the prior art 1.

[0068] The output current capability of the present invention is greater, and can simultaneously meet the calibration capability of the primary or secondary current of the sensor.

[0069] The present invention also uses fluxgate technology and digital + analog closed-loop control technology, which can achieve higher accuracy while increasing the output current range.

[0070] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A handheld large current constant current source, characterized in that: The constant current source comprises: Battery, main controller, database, current DAC, buck regulator, driver, bridge switch, load, current sampling module, constant current module, ADC and temperature control unit; The battery is connected to the main controller and the current-type DAC respectively to provide power; The output end of the main controller is connected to the input end of the database, and is used to set the output current signal through human-computer interaction, search the corresponding logic in the database, and control the output of the current-type DAC; The output end of the database is connected to the input end of the current-mode DAC; The output end of the current-mode DAC is connected to the input end of the buck regulator to control the output voltage of the buck regulator; The output end of the buck regulator is connected to the temperature control unit and the bridge switch respectively; The output end of the bridge switch is connected to the input end of the load; The output end of the load is connected to the input end of the current sampling module, and the output end of the current sampling module is connected to the constant current module; The output end of the constant current module is connected to the battery to control the current of the loop where the load is located to the output current value set in the human-computer interaction; The driver is connected to the bridge switch and the main controller respectively, and the main controller controls the bridge switch through the driver; The main controller changes the current direction in the load by controlling the upper half bridge or the lower half bridge of the bridge switch to be turned on; The current sampling module is connected to the input end of the ADC, and the output end of the ADC is connected to the main controller.

2. A handheld large current constant current source according to claim 1, characterized in that: The battery is a lithium battery.

3. A handheld large current constant current source according to claim 1, characterized in that: The database stores a relationship table between the IDAC output current and the buck regulator output voltage, and stores whole machine calibration data.

4. A handheld large current constant current source according to claim 1, characterized in that: The buck regulator reduces the battery voltage to the voltage value required by the load at a set current value.

5. A handheld large current constant current source according to claim 1, characterized in that: The current sampling module is a fluxgate current sensor DCCT, which converts a large current into a voltage signal received by the constant current module.

6. A handheld large current constant current source according to claim 1, characterized in that: The ADC collects the voltage given by the DCCT to the constant current module, calculates and displays the actual output current value of the loop where the load is located; collects the voltage across the load, calculates the load resistance value, and is used to enable the controller to control the buck regulator to increase the output voltage when the set voltage is increased, ensuring that the buck regulator output can achieve constant current in the loop where the load is located.

7. A handheld large current constant current source according to claim 1, characterized in that: The temperature control unit collects the temperature of the bridge switch, the constant current module, and the entire machine, and dynamically adjusts the output voltage of the buck regulator and shuts down the output.

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