Program-controlled constant current source control system
By designing a programmable constant current source control system, using three-phase power grid, PFC circuit and DC/DC circuit, high-precision, low ripple, wide range and low-cost constant current control is achieved, solving the problem of the lack of continuous adjustable function and high accuracy of existing current sources.
Patent Information
- Application Number
- CN202422048596.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2025-06-10
- Estimated Expiration
- 2034-08-22
AI Technical Summary
The existing current sources lack continuous adjustable function, and the output current range is small, low, large ripple, and expensive, making it difficult to meet the needs of high precision, low ripple, wide range, and low cost.
A program-controlled constant current source control system is designed, including three-phase power grid, PFC circuit and DC/DC circuit. The control circuit realizes real-time monitoring and regulation of current, and has local and mobile APP remote control functions.
It realizes high precision and low ripple of constant current control, adapts to wide range loads, is cheap, and has the functions of good dynamic performance and real-time alarm remote monitoring.
Smart Images
Figure CN222965606U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power electronics, and particularly to a programmable constant current source control system. Background Art
[0002] Voltage sources and current sources are two important power supply devices. The difference between them lies in the different electrical quantities output. A voltage source outputs voltage, while a current source outputs current. Additionally, the output current of a voltage source is determined by the load resistance, while a current source, according to its design characteristics, can output a constant current for any load.
[0003] As an important branch of power supplies, current sources are widely used in scientific research, electric power, metrology and testing departments, industry, and daily life. In scientific research experiments, current sources are mainly used for the amplification and detection of weak electrical signals. Using a current source can avoid signal distortion and circuit loss. In circuit testing, a current source can be used to test the output current of a circuit. In industrial production, current sources are used for constant current control and frequency conversion control (for example, providing excitation current for the excitation coil of a stepping motor and driving a precision stepping motor to operate) to ensure the normal operation of equipment. In daily life, current sources can be applied to LED drive circuits, etc.
[0004] Currently, most current sources on the market do not have a continuously adjustable function; and they have a small output current range, low output, large ripple, and high price. To meet market demand, a programmable DC current source with high precision, low ripple, wide range, and low cost has become an important research direction in the current power supply industry. Summary of the Utility Model
[0005] The technical problem to be solved by the utility model is to provide a programmable constant current source control system with a simple control structure, easy to implement, low cost, good dynamic performance, good constant current control performance, and capable of real-time alarm and remote monitoring.
[0006] To achieve the above object, the utility model provides the following technical solution: A programmable constant current source control system includes a three-phase power grid. The output end of the three-phase power grid is connected to a main circuit, and the main circuit is connected to a variable load. The main circuit includes a three-phase PFC circuit and a DC / DC circuit. The three-phase power grid, the three-phase PFC circuit, the DC / DC circuit, and the variable load are connected through a control circuit for control. The control circuit includes a voltage and current acquisition circuit, a drive circuit, and a controller.
[0007] In a preferred embodiment, the input end of the three-phase PFC circuit is connected to the three-phase power grid. The positive output end and the negative output end of the three-phase PFC circuit are respectively connected to the positive input end and the negative input end of the DC / DC circuit, and the output end of the DC / DC circuit is connected to the variable load.
[0008] In a preferred embodiment, the voltage and current acquisition circuit includes a first drive circuit and a second drive circuit. The controller is connected to the control terminal of the three-phase PFC circuit through the first drive circuit, and the controller is connected to the control terminal of the DC / DC circuit through the second drive circuit.
[0009] In a preferred embodiment, the voltage and current acquisition circuit includes a first voltage and current acquisition circuit, a second voltage and current acquisition circuit, and a third voltage and current acquisition circuit. The controller acquires the output voltage and output current of the three-phase power grid through the first voltage and current acquisition circuit, acquires the output voltage of the three-phase PFC circuit through the second voltage and current acquisition circuit, and acquires the terminal voltage and terminal current of the variable load through the third voltage and current acquisition circuit.
[0010] In a preferred embodiment, the input terminal of the controller is connected to a power-on / off key, a mobile phone APP, and an operation keyboard. The power-on / off key realizes local power-on and power-off operations, the mobile phone APP realizes remote monitoring and free setting of the constant current output value between 0A and the maximum value, and the operation keyboard realizes free setting of the constant current output value between 0A and the maximum value.
[0011] In a preferred embodiment, the controller adopts a DSP controller, and the controller is wirelessly connected to the mobile phone APP through GPRS.
[0012] In a preferred embodiment, the three-phase PFC circuit includes a three-phase bridge rectifier circuit composed of six diodes and a DC bus voltage regulation circuit composed of six switching tubes. The connection structure of the DC bus voltage regulation circuit and the three-phase power grid is a three-phase star connection. In each phase, there are two switching tubes. The inputs or outputs of the two switching tubes are connected together, and the control terminals are connected together. The inputs or outputs of the two switching tubes are respectively connected to one phase of the three-phase power grid and the common connection point of the star.
[0013] In a preferred embodiment, the DC / DC circuit includes four switching tubes, two inductors, an isolation transformer, and a filter capacitor. The four switching tubes are bridged, and the control terminals of the four switching tubes are connected to the controller and are controlled by the controller through the second drive circuit.
[0014] Compared with the prior art, the beneficial effects of the present utility model are:
[0015] 1. The constant current control scheme adopted by the present utility model starts from the perspective of the system. By monitoring the output voltage VO of the DC / DC circuit and the current IO flowing into the variable load terminal, the output voltage VO of the DC / DC circuit is adjusted, so that the current value provided to the variable load always remains at a preset level. That is, after the resistance value of the variable load changes, the voltage VO also changes accordingly, but the ratio IO of VO to the resistance value of the variable load remains constant. Therefore, after the output current is set, the output current of the current source provided by the present utility model will not drift during use and can meet very high precision requirements. Thus, it can meet the needs of high - requirement electronic devices, achieve a good constant current control effect, and at the same time, the control structure is simple and the cost is low.
[0016] 2. The present utility model has two control methods: local and remote control via mobile phone APP. The operating status of the system and the constant current output value can be remotely monitored through the mobile phone APP and freely set between 0A and the maximum value. In addition, the implementation scheme of the constant current control system of the present utility model is not only applicable to the case where the front - stage is an AC / DC converter, but also applicable to DC / DC converters, and has good scalability. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the output control of the constant current source of the present utility model;
[0018] Figure 2 It is a schematic diagram of the electrical connection structure of the constant current control system of the present utility model;
[0019] Figure 3 It is the electrical schematic diagram of the constant current control system of the present utility model.
[0020] Reference numerals in the figure: 1, three - phase power grid; 2, three - phase PFC circuit; 3, DC / DC circuit; 4, variable load; 5, first voltage - current acquisition circuit; 6, first drive circuit; 7, second voltage - current acquisition circuit; 8, second drive circuit; 9, third voltage - current acquisition circuit; 10, controller; 11, mobile phone APP; 12, power - on / off key; 13, operation keyboard. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.
[0022] Embodiment: As Figures 1 - 3As shown in the figure, the present utility model provides a technical solution, a programmable constant current source control system, including a three-phase power grid 1, the output end of the three-phase power grid 1 is connected to a main circuit, the main circuit is connected to a variable load 4, the main circuit includes a three-phase PFC circuit 2 and a DC / DC circuit 3, the three-phase power grid 1, the three-phase PFC circuit 2, the DC / DC circuit 3 and the variable load 4 are connected through a control circuit, and the control circuit includes a voltage and current acquisition circuit, a driving circuit and a controller 10.
[0023] In a preferred embodiment, the input end of the three-phase PFC circuit 2 is connected to the three-phase power grid 1, the positive output end and the negative output end of the three-phase PFC circuit 2 are respectively connected to the positive input end and the negative input end of the DC / DC circuit 3, and the output end of the DC / DC circuit 3 is connected to the variable load 4.
[0024] In a preferred embodiment, the voltage and current acquisition circuit includes a first driving circuit 6 and a second driving circuit 8, the controller 10 is connected to the control end of the three-phase PFC circuit 2 through the first driving circuit 6, and the controller 10 is connected to the control end of the DC / DC circuit 3 through the second driving circuit 8.
[0025] In a preferred embodiment, the voltage and current acquisition circuit includes a first voltage and current acquisition circuit 5, a second voltage and current acquisition circuit 7 and a third voltage and current acquisition circuit 9, the controller 10 acquires the output voltages Va, b, c and output currents Ia, b, c of the three-phase power grid 1 through the first voltage and current acquisition circuit 5, the controller 10 acquires the output voltage Vbus of the three-phase PFC circuit 2 through the second voltage and current acquisition circuit 7, and the controller 10 acquires the terminal voltage Vo and terminal current Io of the variable load 4 through the third voltage and current acquisition circuit 9.
[0026] In a preferred embodiment, the input end of the controller 10 is connected to a power on / off key 12, a mobile phone APP 11 and an operation keyboard 13. The power on / off key 12 realizes local power on / off operation, the mobile phone APP 11 realizes remote monitoring and free setting of the constant current output value between 0A and the maximum value, and the operation keyboard 13 realizes free setting of the constant current output value between 0A and the maximum value.
[0027] In a preferred embodiment, the controller 10 adopts a DSP controller, and the controller 10 is wirelessly connected to the mobile phone APP 11 through GPRS.
[0028] In a preferred embodiment, the three-phase PFC circuit 2 includes a three-phase bridge rectifier circuit composed of six diodes and a DC bus voltage regulation circuit composed of six switching tubes. The connection structure of the DC bus voltage regulation circuit and the three-phase power grid 1 is a three-phase star connection. In each phase, there are two switching tubes. The inputs or outputs of the two switching tubes are connected together, and the control terminals are connected together. The inputs or outputs of the two switching tubes are respectively connected to one phase of the three-phase power grid 1 and the common connection point of the star.
[0029] In a preferred embodiment, the DC / DC circuit 3 includes four switching tubes, two inductors, an isolation transformer, and a filter capacitor. The four switching tubes are bridged, and the control terminals of the four switching tubes are connected to the controller 10 and controlled by the controller 10 through the second drive circuit 8.
[0030] The working principle of the present invention:
[0031] The controller 10 uses the sampling signal of the third voltage and current acquisition circuit 9 as a negative feedback signal. The error between the preset output current value is processed by a digital arithmetic controller to generate a control quantity to control the PWM signal of the DC / DC circuit 3, thereby controlling the on-off time of the four fast power tubes. Finally, the output voltage Vo of the DC / DC circuit 3 is adjusted to maintain its output current value unchanged, achieving a good constant current output control effect. Specifically as follows:
[0032] The controller 10 collects the output voltages Va, b, c and output currents Ia, b, c of the three-phase power grid 1 through the first voltage and current acquisition circuit 5. By obtaining the waveforms of the three-phase voltages Va, b, c, the voltage waveforms of the positive and negative output terminals of the three-phase PF circuit 2 with respect to the virtual midpoint N are obtained, that is, the positive and negative envelopes of the waveforms of the three-phase voltages Va, b, c. The positive envelope fluctuation interval (one mains cycle can be divided into 6 intervals) is used to generate three groups of low-frequency common-emitter bidirectional IGBT tube drive signals for injecting the third harmonic into the three-phase PFC circuit 2, and the three current harmonic injection circuit network paths are switched at twice the grid frequency (i.e., 100 Hz).
[0033] The controller 10 forms closed-loop control for the feedback signals of the output voltages Vbus1 and Vbus2 of the three-phase PFC circuit 2 and their respective output set values through the second voltage and current acquisition circuit 7, so that the outputs are respectively stabilized at ±400V. At the same time, the controller 10 feeds back the output current signal Io of the DC / DC circuit 3 to the control loop of the DC / DC circuit 3 through the third voltage and current acquisition circuit 9, that is, the controller 10 calculates Ierr = Iref - Io between the output current set reference Iref and the output current feedback value Io. Ierr generates a control quantity through the loop controller, and finally generates 4-channel PWM drive signals through comparison with a comparator to control the on and off time lengths of the 4 power switching tubes of the DC / DC circuit 3, realizing real-time dynamic adjustment of the output voltage Vo of the DC / DC circuit 3, and finally realizing that the output current Io is consistent with the output current set reference Iref. Assuming that the resistance value of the variable load 4 is Rload, the relationship between Rload, the output voltage Vo, and the output current Io is Io = Vo / Rload. According to this relationship, it is not difficult to infer that after Rload changes, if the value of Io is to be maintained unchanged, the value of the output voltage Vo needs to be increased or decreased in the same proportion; similarly, when Rload remains unchanged and the output current set reference Iref changes, if the current Io is to follow Iref, the output voltage Vo also needs to be increased or decreased in the same proportion. In short, whether it is due to the change of the variable load 4 or the change of the output current set reference Iref, the relationship of maintaining Io consistent with Iref can be achieved by increasing or decreasing the output voltage Vo of the DC / DC circuit 3 in the same proportion. The controller 10 can achieve the purpose of constant current control of the system output by adjusting the output voltage Vo of the above-mentioned DC / DC circuit 3 through just a few feedback closed-loop control cycles.
[0034] For the reliable operation of the system, the controller 10 feeds the output voltage signal Vo of the DC / DC circuit 3 through the third voltage and current acquisition circuit 9, and judges whether the system is in an overvoltage or undervoltage state of the output according to the value of Vo, and then shuts down the system output and gives an alarm to indicate that the system is abnormal.
[0035] To ensure the normal operation of the system after power-on, the controller 10 acquires the supply voltage and current of the three-phase power grid (1) through the first voltage and current acquisition circuit 5. When powering on and starting up, the controller 10 first initializes each parameter of the system, and judges whether the input of the three-phase power grid 1 is normal through the first voltage and current acquisition circuit 5. It is only allowed to start working after the input of the three-phase power grid 1 is normal.
[0036] For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-mentioned exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model. Any reference signs in the claims should not be construed as limiting the claims involved.
Claims
1. A program-controlled constant current source control system, comprising a three-phase power grid (1), characterized in that: The output end of the three-phase power grid (1) is connected to a main circuit, the main circuit is connected to a variable load (4), the main circuit comprises a three-phase PFC circuit (2) and a DC / DC circuit (3), the three-phase power grid (1), the three-phase PFC circuit (2), the DC / DC circuit (3) and the variable load (4) are connected through a control circuit, and the control circuit comprises a voltage and current acquisition circuit, a drive circuit and a controller (10).
2. A program-controlled constant current source control system according to claim 1, characterized in that: The input end of the three-phase PFC circuit (2) is connected to a three-phase power grid (1), the positive output end and the negative output end of the three-phase PFC circuit (2) are respectively connected to the positive input end and the negative input end of a DC / DC circuit (3), and the output end of the DC / DC circuit (3) is connected to a variable load (4).
3. A program-controlled constant current source control system according to claim 1, characterized in that: The voltage and current acquisition circuit comprises a first drive circuit (6) and a second drive circuit (8); the controller (10) is connected to the control end of the three-phase PFC circuit (2) via the first drive circuit (6); and the controller (10) is connected to the control end of the DC / DC circuit (3) via the second drive circuit (8).
4. A program-controlled constant current source control system according to claim 1, characterized in that: The voltage and current acquisition circuit comprises a first voltage and current acquisition circuit (5), a second voltage and current acquisition circuit (7) and a third voltage and current acquisition circuit (9); the controller (10) acquires the output voltage and output current of the three-phase power grid (1) through the first voltage and current acquisition circuit (5); the controller (10) acquires the output voltage of the three-phase PFC circuit (2) through the second voltage and current acquisition circuit (7); and the controller (10) acquires the terminal voltage and terminal current of the variable load (4) through the third voltage and current acquisition circuit (9).
5. A program-controlled constant current source control system according to claim 1, characterized in that: The input end of the controller (10) is connected to a power button (12), a mobile phone APP (11) and an operation keyboard (13).
6. A program-controlled constant current source control system according to claim 5, characterized in that: The controller (10) adopts a DSP controller, and the controller (10) is wirelessly connected to a mobile phone APP (11) via GPRS.
7. A program-controlled constant current source control system according to claim 1, characterized in that: The three-phase PFC circuit (2) comprises a three-phase bridge rectifier circuit composed of six diodes and a DC bus voltage regulation circuit composed of six switch tubes. The DC bus voltage regulation circuit is connected to the three-phase power grid (1) in a three-phase star connection structure. There are two switch tubes in each phase. The inputs or outputs of the two switch tubes are connected together, and the control ends are connected together. The inputs or outputs of the two switch tubes are respectively connected to one phase of the three-phase power grid (1) and a common connection point of the star.
8. A program-controlled constant current source control system according to claim 3, characterized in that: The DC / DC circuit (3) comprises four switch tubes, two inductors, an isolation transformer and a filter capacitor. The four switch tubes are bridged, and the control ends of the four switch tubes are connected to a controller (10) and controlled by the controller (10) through a second drive circuit (8).