High-precision adjustable three-phase constant current source

Abstract

The present disclosure belongs to the technical field of power electronics, and provides a high-precision adjustable three-phase constant current source, comprising an MCU, a primary amplification circuit, a secondary amplification circuit, an output circuit, a voltage acquisition circuit and a current acquisition circuit; the MCU is connected with the primary amplification circuit, the primary amplification circuit is used for primary power amplification of three-phase sine waves output by the MCU, the secondary amplification circuit is used for secondary power amplification of the output of the primary amplification circuit, the secondary amplification circuit is connected with the output circuit, and is used for providing a constant current source externally; the voltage acquisition circuit and the current acquisition circuit are respectively used for real-time acquisition of voltage and current signals of the three-phase constant current source, and feedback to the MCU; the MCU performs multi-path PID control on the feedback voltage and current signals of the three-phase constant current source. The high-precision adjustable three-phase constant current source of the present disclosure does not need to use a DAC device, and guarantees the phase consistency and stability of the output waveform, simultaneously supports remote setting of waveform parameters, selection of constant current / constant voltage modes, control precision, and a wide output range.

Description

Technical Field

[0001] This disclosure belongs to the field of power electronics technology, and in particular relates to a high-precision adjustable three-phase constant current source. Background Technology

[0002] In terms of hardware structure, existing constant current source devices are mainly single-phase or dual-channel structures, which make it difficult to achieve three-phase synchronous output. Even if they can output three-phase signals, there are often problems such as the phase difference being difficult to maintain precisely at 120°, poor amplitude consistency, and high waveform distortion, which cannot meet the requirements of power electronics or power system simulation tests for high-precision three-phase signals.

[0003] In terms of signal amplification, existing constant current sources generally use fixed-gain amplifier circuits, which have limited voltage and current output ranges. This makes it difficult to achieve both precise control of small signals and stable driving of high power, thus limiting their application range.

[0004] In terms of feedback and control mechanisms, existing constant current sources only perform feedback control on a single parameter of current, lacking joint sampling and independent adjustment of voltage and current. Especially when there are multiple outputs, they often share a set of feedback channels, which can easily cause output fluctuations when the load changes, making it difficult to guarantee long-term stable and high-precision current output.

[0005] Regarding signal generation methods, some high-end constant current sources rely on expensive digital-to-analog converters (DACs, also known as D / A converters), while low-cost products often use simple PWM with filtering to generate approximate sine waves. These solutions not only increase hardware costs or design complexity but also tend to result in high harmonic content, large three-phase phase deviations, and narrow amplitude adjustment ranges, making it difficult to balance economy and performance.

[0006] Therefore, there is a need to provide a three-phase constant current source that simplifies the circuit structure of the constant current source, reduces hardware costs, improves control accuracy, and allows for flexible switching of operating modes. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure provides a high-precision adjustable three-phase constant current source, which simplifies the circuit structure of the constant current source, reduces hardware costs, improves control accuracy, and allows for flexible switching of operating modes, thus expanding its applicability.

[0008] The preferred technical solution adopted in this disclosure is as follows:

[0009] A high-precision adjustable three-phase constant current source includes an MCU, a primary amplifier circuit, a secondary amplifier circuit, an output circuit, a voltage acquisition circuit, and a current acquisition circuit. The MCU is connected to the primary amplifier circuit. The primary amplifier circuit is used to amplify the three-phase sine wave output by the MCU. The secondary amplifier circuit is used to amplify the output of the primary amplifier circuit. The secondary amplifier circuit is connected to the output circuit. The output circuit is used to provide a constant current source. The voltage acquisition circuit and the current acquisition circuit are used to acquire the voltage and current signals of the three-phase constant current source in real time and feed them back to the MCU. The MCU performs multi-channel PID control on the feedback voltage and current signals of the three-phase constant current source.

[0010] Furthermore,

[0011] The MCU includes a timer, a DMA function module, an active RC low-pass filter, and a DDS function module.

[0012] Furthermore,

[0013] The timer triggers the DMA function module according to the set sine wave period. The MCU generates a PWM square wave based on the pre-stored waveform parameter values, and outputs a simulated sine wave through an active RC low-pass filter. The simulated sine wave is then used by the DDS function module to generate A, B, and C three-phase sine waves.

[0014] Furthermore,

[0015] The MCU includes a dual feedback control module for multi-channel PID control of the output voltage and current of the three-phase constant current source.

[0016] Furthermore,

[0017] The MCU has 6 A / D conversion ports, which are used to receive and convert the current and voltage signals of each phase of the three-phase constant current source separately and provide them to the dual feedback control module.

[0018] Furthermore,

[0019] The MCU includes a communication module for efficient communication with the host computer, supporting remote setting of waveform parameters, selection of constant current / constant voltage mode, and real-time status monitoring.

[0020] Furthermore,

[0021] The three-phase constant current source also includes a heat dissipation device for cooling the primary and secondary amplifier circuits.

[0022] Furthermore,

[0023] The MCU, primary amplifier circuit, secondary amplifier circuit, voltage acquisition circuit, and current acquisition circuit are all powered by an external power supply.

[0024] Furthermore,

[0025] The gains of the primary amplifier circuit and the secondary amplifier circuit are adjustable.

[0026] Furthermore,

[0027] The three-phase constant current source is located inside the enclosure, which has openings for the passage of lines.

[0028] In the embodiments of this disclosure, the MCU generates a PWM square wave through an internal timer, automatically updates the duty cycle of the simulated sine wave through a DMA function module, and filters out high-frequency components in the simulated sine wave through an active RC low-pass filter. A three-phase sine wave is generated using a DDS function module. The three-phase sine wave is amplified by a primary amplifier circuit and a secondary amplifier circuit, and then output to the external electrical equipment through an output circuit. The voltage and current of the three-phase constant current source are collected by a voltage acquisition circuit and a current acquisition circuit, respectively. The MCU performs multi-channel PID control on the voltage and current of the three-phase constant current source and communicates with the host computer. The waveform parameters of the three-phase constant current source can be adjusted, the constant current or constant voltage working mode can be selected, and the output accuracy of the three-phase constant current source can be controlled through the host computer.

[0029] Compared with the prior art, this disclosure provides a high-precision adjustable three-phase constant current source, which has the following beneficial effects:

[0030] 1. By adopting dual sampling feedback of voltage and current, combined with PID control, the output signal can still maintain high accuracy and stability under different load conditions, effectively solving the problem of large current fluctuations in traditional constant current sources when the load changes.

[0031] 2. The system uses a combination of timer, DMA, active RC filter, and DDS to generate a sine wave with a three-phase phase difference of 120° and a frequency of 50Hz. This eliminates the need for expensive DAC devices and ensures the phase consistency and stability of the output waveform.

[0032] 3. It adopts a two-stage power amplifier with adjustable gain and communicates efficiently with the host computer through a serial communication module. It supports remote setting of waveform parameters, selection of constant current / constant voltage mode, control precision, wide output range, and strong applicability.

[0033] Other features and advantages of this disclosure will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram illustrating the structural principle of a high-precision adjustable three-phase constant current source according to an embodiment of the present disclosure is shown.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1-MCU; 2-Primary amplifier circuit; 3-Secondary amplifier circuit; 4-Output circuit; 5-Voltage acquisition circuit; 6-Current acquisition circuit. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0039] like Figure 1 As shown, a high-precision adjustable three-phase constant current source according to an embodiment of this disclosure includes an MCU1, a primary amplifier circuit 2, a secondary amplifier circuit 3, an output circuit 4 (port circuit), a voltage acquisition circuit 5, and a current acquisition circuit 6.

[0040] MCU1 is connected to primary amplifier circuit 2, which is used to amplify the three-phase sine wave output by MCU1.

[0041] The primary amplifier circuit 2 is connected to the secondary amplifier circuit 3, which amplifies the output of the primary amplifier circuit 2 a second time. The primary amplifier circuit preferably uses an AD603 chip, which can achieve a continuously adjustable gain of -20dB to 20dB.

[0042] The secondary amplifier circuit 3 is connected to the output circuit 4, which is a port circuit used to provide a constant current source. Preferably, the secondary amplifier circuit uses a high-power operational amplifier OPA549 to meet the needs of different application scenarios, from small signals to high-power drives. Preferably, the gain of the secondary amplifier circuit 3 can be adjusted using a potentiometer. Alternatively, in another feasible embodiment, the gain of the secondary amplifier circuit 3 is a fixed amplification factor.

[0043] Voltage acquisition circuit 5 and current acquisition circuit 6 are used to acquire the voltage and current signals of the three-phase constant current source in real time and feed them back to MCU1. MCU1 performs multi-channel PID control on the feedback voltage and current signals of the three-phase constant current source. In the embodiments of this disclosure, the dual sampling feedback of voltage and current, combined with PID control, can maintain the high accuracy and stability of the output signal under different load conditions, effectively solving the problem of large current fluctuations in traditional constant current sources when the load changes.

[0044] MCU1 includes a timer, a DMA function module, an active RC low-pass filter, and a DDS function module.

[0045] DMA (Direct Memory Access) is a technology that allows high-speed data transfer directly between peripherals and memory or other peripherals without continuous CPU intervention. In the embodiments of this disclosure, a timer triggers the DMA function module according to a set sine wave period. MCU1 generates a PWM square wave based on pre-stored waveform parameter values, which is then output as an analog sine wave via an active RC low-pass filter. The active RC low-pass filter is used to filter out high-frequency components in the PWM square wave.

[0046] DDS (Direct Digital Synthesizer) is a signal generation method based on digital electronics technology that generates arbitrary waveforms and frequencies using a single frequency source. The analog sine wave output from an active RC low-pass filter is used by the DDS module to generate three-phase sine waves (A, B, and C). The phase difference between the A, B, and C phase sine waves is 120 degrees, and the frequency is 50Hz.

[0047] MCU1 also includes a dual feedback control function module ( Figure 1 In this section, a PID feedback control module is used to perform multi-channel PID control on the output voltage and current of the three-phase constant current source. Specifically, the dual feedback control function module outputs a control voltage based on the output voltage and current (deviation) of the three-phase constant current source to adjust the gain of the primary amplifier circuit 2.

[0048] Furthermore, MCU1 has 6 A / D conversion ports, which are used to individually receive and convert the current and voltage signals of each phase of the three-phase constant current source, and provide them to the dual feedback control function module.

[0049] Furthermore, MCU1 also includes a communication module for efficient communication with a host computer, supporting remote setting of waveform parameters, selection of constant current / constant voltage modes, and real-time status monitoring. The communication module is preferably a UART serial communication module. When commands are sent from the host computer to adjust the pre-stored waveform parameter values ​​in MCU1, the DMA function module can automatically update the waveform parameters cyclically.

[0050] In the embodiments of this disclosure, MCU1 is preferably an STM32 microcontroller, which uses a "timer PWM + active RC filter + DDS function" method to generate a sine wave with a three-phase phase difference that is precisely maintained at 120° and a frequency that is stable at 50Hz, thus ensuring the phase consistency and stability of the output waveform.

[0051] Furthermore, the primary amplifier circuit 2 specifically includes: an A-phase primary sub-amplifier circuit, a B-phase primary sub-amplifier circuit, and a C-phase primary sub-amplifier circuit, corresponding to the A-phase, B-phase, and C-phase of the three-phase sine wave, respectively.

[0052] Furthermore, the secondary amplifier circuit 3 specifically includes: an A-phase secondary sub-amplifier circuit, a B-phase secondary sub-amplifier circuit, and a C-phase secondary sub-amplifier circuit, which correspond to the A-phase, B-phase, and C-phase of the three sinusoidal signals, respectively.

[0053] Optionally, MCU1, primary amplifier circuit 2, secondary amplifier circuit 3, voltage acquisition circuit 5, and current acquisition circuit 6 are all powered by an external power supply (not the three-phase constant current source itself) to reduce the impact of external load fluctuations. Preferably, Figure 1 The two "external power supply" options refer to the same power source.

[0054] Furthermore, the three-phase constant current source also includes a heat dissipation device, which is used to dissipate heat for the primary amplifier circuit 2 and the secondary amplifier circuit 3.

[0055] Optionally, the three-phase constant current source is housed within a cabinet, which has openings for wiring. These openings can also be used to install wiring interfaces.

[0056] Although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A high-precision adjustable three-phase constant current source, characterized in that, it comprises an MCU, a primary amplification circuit, a secondary amplification circuit, an output circuit, a voltage acquisition circuit and a current acquisition circuit; the MCU comprises a timer, a DMA function module, an active RC low-pass filter and a DDS function module; the timer triggers the DMA function module according to a set sine wave period, and the MCU generates a PWM square wave according to pre-stored waveform parameter values, and outputs an analog sine wave through the active RC low-pass filter; the analog sine wave generates A, B and C three-phase sine waves through the DDS function module; the MCU is connected with the primary amplification circuit, the primary amplification circuit is used for primary power amplification of the three-phase sine waves output by the MCU, the secondary amplification circuit is used for secondary power amplification of the output of the primary amplification circuit, the secondary amplification circuit is connected with the output circuit, and the output circuit is used for providing a constant current source to the outside; the voltage acquisition circuit and the current acquisition circuit are respectively used for real-time acquisition of voltage and current signals of the three-phase constant current source and feedback to the MCU; the MCU comprises a double feedback control function module, which is used for multi-path PID control of output voltage and current of the three-phase constant current source, and outputs a control voltage to adjust the gain of the primary amplification circuit according to the output voltage and current of the three-phase constant current source.

2. The three-phase constant current source according to claim 1, characterized in that, the MCU has six A / D conversion ports, which are used for separately receiving and converting the acquired three-phase constant current source current and voltage signals of each phase and providing the double feedback control module.

3. The three-phase constant current source according to claim 1, characterized in that, the MCU comprises a communication module, which is used for communication with an upper computer, supports the upper computer to remotely set waveform parameters, select constant current / constant voltage mode and real-time state monitoring.

4. The three-phase constant current source according to claim 1, characterized in that, the three-phase constant current source further comprises a heat dissipation device, which is used for heat dissipation of the primary amplification circuit and the secondary amplification circuit.

5. The three-phase constant current source according to claim 1, characterized in that, the MCU, the primary amplification circuit, the secondary amplification circuit, the voltage acquisition circuit and the current acquisition circuit are all powered by an external power supply.

6. The three-phase constant current source according to claim 1, characterized in that, the gain of the primary amplification circuit and the secondary amplification circuit is adjustable.

7. The three-phase constant current source according to claim 1, characterized in that, the three-phase constant current source is arranged in a box, and the box is provided with an opening hole for passing through a line.

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