Control method and device of current generating device

Abstract

The invention discloses a control method and device of a current generating device, and relates to the technical field of current generators. According to the invention, the direct current input voltage of the current generating device and the output signal of the PIR controller are subjected to proportional operation, so that the modulation signal output by the PIR controller can be associated with the actual working state of the current generating device; the switch control signal obtained by performing pulse width modulation on the modulation signal subsequently can reflect the actual working state of the inverter, and the output current precision of the current generation device can be improved by controlling the inverter based on the switch control signal.

Description

Technical Field

[0001] The present invention relates to the technical field of current generators, and in particular to a control method and device for a current generating device. Background Art

[0002] The current generating device is used to invert the DC voltage into AC power. The control accuracy of the switch tube of the inverter in the current generating device determines the accuracy of the output current of the current generating device. Usually, the closed-loop control strategy and pulse width modulation are used to control the switch tube of the inverter. However, the modulation signal in this strategy has nothing to do with the actual working state of the inverter. The switch control signal obtained by pulse width modulation of the modulation signal cannot reflect the actual working state of the inverter. After controlling the inverter based on the switch control signal, the output current accuracy of the current generating device is low. Summary of the invention

[0003] The present invention solves the technical problem of how to improve the accuracy of the output current of the current generating device by providing a control method and a device for the current generating device.

[0004] On the one hand, the present invention provides the following technical solutions:

[0005] A method for controlling a current generating device, comprising:

[0006] Obtaining a preset reference current, an actual output current of a current generating device, and a DC input voltage;

[0007] determining a current error between the reference current and the actual output current;

[0008] Inputting the current error into a PIR controller to obtain an output signal of the PIR controller;

[0009] Performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal;

[0010] Performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device;

[0011] Each switch tube of the inverter in the current generating device is controlled based on the switch control signal.

[0012] Optionally, performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulated signal includes:

[0013] The ratio of the output signal of the PIR controller to the DC input voltage is calculated to obtain the modulation signal.

[0014] Optionally, after performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal and before performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device, the method further includes:

[0015] The modulated signal is limited.

[0016] Optionally, the current generating device is composed of a plurality of current generators connected in series, and the DC input voltage is the sum of the DC side filter capacitor voltages of the plurality of current generators;

[0017] The step of performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device includes:

[0018] Obtain a preset triangular carrier signal;

[0019] Determine the phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of the current generators, and f is the frequency of the triangular carrier signal;

[0020] Phase shifting the triangular carrier signal according to the phase shift time input signal;

[0021] The modulation signal is compared with the phase-shifted triangular carrier signal to obtain the switch control signal.

[0022] On the other hand, the present invention also provides the following technical solutions:

[0023] A control device for a current generating device, comprising:

[0024] An acquisition module, used to acquire a preset reference current, an actual output current of a current generating device, and a DC input voltage;

[0025] A determination module, used to determine a current error between the reference current and the actual output current;

[0026] An input module, used for inputting the current error into a PIR controller to obtain an output signal of the PIR controller;

[0027] An operation module, used for performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal;

[0028] A modulation module, used for performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device;

[0029] A control module is used to control each switch tube of the inverter in the current generating device based on the switch control signal.

[0030] Optionally, the computing module is specifically used for:

[0031] The ratio of the output signal of the PIR controller to the DC input voltage is calculated to obtain the modulation signal.

[0032] Optionally, the control device of the current generating device further includes:

[0033] A limiting module is used to limit the modulated signal.

[0034] Optionally, the current generating device is composed of a plurality of current generators connected in series, and the DC input voltage is the sum of the DC side filter capacitor voltages of the plurality of current generators;

[0035] The modulation module is specifically used for:

[0036] Obtain a preset triangular carrier signal;

[0037] Determine the phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of the current generators, and f is the frequency of the triangular carrier signal;

[0038] Phase shifting the triangular carrier signal according to the phase shift time input signal;

[0039] The modulation signal is compared with the phase-shifted triangular carrier signal to obtain the switch control signal.

[0040] On the other hand, the present invention also provides the following technical solutions:

[0041] A computer device comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of any one of the above-mentioned control methods for a current generating device.

[0042] On the other hand, the present invention also provides the following technical solutions:

[0043] A computer-readable storage medium stores a computer program, wherein the computer program, when executed by a processor, implements the steps of any one of the above-mentioned control methods for a current generating device.

[0044] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0045] The present invention performs proportional operation on the DC input voltage of the current generating device and the output signal of the PIR controller, and can associate the modulation signal output by the PIR controller with the actual working state of the current generating device. The switch control signal obtained by subsequent pulse width modulation of the modulation signal can reflect the actual working state of the inverter. Controlling the inverter based on the switch control signal can improve the output current accuracy of the current generating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in 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 in the following description are 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.

[0047] Figure 1 is a circuit diagram of a current generator in an embodiment of the present invention;

[0048] Figure 2 A circuit diagram of a current generating device composed of current generators connected in series in an embodiment of the present invention;

[0049] Figure 3 is a flow chart of a control method of a current generating device according to an embodiment of the present invention;

[0050] Figure 4 A schematic diagram of the generation principle of a modulation signal in an embodiment of the present invention;

[0051] Figure 5 is a schematic diagram of the generation principle of the switch control signal of the current generating device in an embodiment of the present invention;

[0052] Figure 6 is a schematic diagram of the generation principle of a switch control signal of a single current generator in an embodiment of the present invention;

[0053] Figure 7 Schematic diagram of output current waveform and FFT result when there is no harmonic injection in an embodiment of the present invention;

[0054] Figure 8 Schematic diagram of output current waveform and FFT result when harmonics are injected in an embodiment of the present invention;

[0055] Fig. 9 Schematic diagram of a control device for a current generating device in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The embodiments of the present invention solve the technical problem of how to improve the accuracy of the output current of the current generating device by providing a control method and a device for the current generating device.

[0057] In order to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0058] A single current generator according to an embodiment of the present invention is as follows: Figure 1 As shown, the current generator may include a voltage source, a diode D, a DC side filter capacitor C1 and an inverter; the voltage source is set as an ideal DC source, the nominal voltage may be 350V, and R1 is the internal resistance of the voltage source; the main function of the diode D is to prevent the current from flowing in the reverse direction, that is, to achieve unidirectional conduction of the current and ensure the stability of the circuit operation; the capacitor C1 is used to smooth the voltage and current fluctuations from the inverter; T1, T2, T3, and T4 are the four switch tubes of the inverter, and T01, T02, T03, and T04 are the driving signals of the four switch tubes, respectively, which are used to control the on and off of the switch tubes. By controlling the on and off of T1, T2, T3, and T4 through T01, T02, T03, and T04, DC power can be converted into AC power, and vh1 and vl1 are the high-end output and low-end output of the inverter respectively. The voltmeter is connected in parallel at both ends of the DC side filter capacitor C1 to detect the voltage of the DC side filter capacitor.

[0059] The current generating device of the embodiment of the present invention may include only a single current generator, or may be composed of a plurality of current generators connected in series. For example, a current generating device composed of three current generators connected in series may be Figure 2 As shown, the inverter low-end output vl1 of current generator a is connected to the inverter high-end output vh2 of current generator b, the inverter low-end output vl2 of current generator b is connected to the inverter high-end output vh3 of current generator c, and the inverter high-end output vh1 of current generator a and the inverter low-end output vl3 of current generator c serve as the output ends of the current generating device. Ta, Tb, and Tc are the switch control signals of the inverters in the three current generators, respectively, VCa, VCb, and VCC are the output ends of the voltmeters in the three current generators, and Vc01, Vc02, and Vc03 are the DC side filter capacitor voltages output by VCa, VCb, and VCC, that is, the DC side filter capacitor voltages of the three current generators. Multiple current generators connected in series to form a current generating device can double the output voltage of the current generating device, thereby reducing the voltage stress borne by the switch tube of the inverter.

[0060] like Figure 3 As shown, the control method of the current generating device according to the embodiment of the present invention includes:

[0061] Step S1, obtaining a preset reference current, an actual output current of a current generating device, and a DC input voltage;

[0062] like Figure 4As shown, the reference current Iref represents the current expected to be output by the current generating device; when the current generating device only includes the current generator a, an ammeter, an output filter inductor and a load connected in series can be connected between vh1 and vl1 of the inverter, and the actual output current of the current generating device is detected by the ammeter; when the current generating device only includes the current generator a, Vc01 is the DC input voltage of the current generating device;

[0063] When the current generating device is composed of three current generators connected in series, Figure 2 As shown, an ammeter, an output filter inductor L and a load load connected in series can be connected between the inverter vh1 of the current generator a and the inverter vl3 of the current generator c, and the actual output current Iout of the current generating device can be detected by the ammeter; when the current generating device is composed of three current generators connected in series, as shown in FIG. Figure 4 As shown, the DC input voltage of the current generating device is the sum of Vc01, Vc02, and Vc03;

[0064] Step S2, determining a current error between a reference current and an actual output current;

[0065] like Figure 4 As shown, the current error is Ierr;

[0066] Step S3, inputting the current error into the PIR controller to obtain an output signal of the PIR controller;

[0067] The principle of PIR (proportional-integral-resonant) controller is as follows Figure 4 As shown in the figure, the PIR controller combines the advantages of proportional (P), integral (I) and resonant (R) control, and can effectively modulate the current error Ierr to quickly and accurately correct the deviation of the output current of the current generating device and suppress the interference of specific frequencies; the output of the PIR controller not only reflects the current value and historical accumulation of the current error Ierr (realized by proportional and integral terms), but also optimizes the specific frequency (realized by resonant terms), which can improve the dynamic response speed and steady-state accuracy of the current control;

[0068] Step S4, performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal;

[0069] In some embodiments, step S4 may include: calculating the ratio of the output signal of the PIR controller to the DC input voltage of the current generating device to obtain a modulation signal; when the current generating device is composed of three current generators connected in series, such as Figure 4 As shown, the modulated signal is a modulatde wave;

[0070] By performing a proportional operation on the DC input voltage of the current generating device and the output signal of the PIR controller, the modulation signal output by the PIR controller can be associated with the actual working state of the current generating device (i.e., the DC input voltage). The switch control signal subsequently obtained according to the pulse width modulation can reflect the actual working state of the inverter. Controlling the inverter based on the switch control signal can improve the output current accuracy of the current generating device.

[0071] Step S5, performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device;

[0072] When the current generating device includes only a single current generator, conventional PWM modulation or SPWM modulation may be used;

[0073] When the current generating device is composed of three current generators connected in series, step S5 may include: obtaining a preset triangular carrier signal; determining a phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of current generators, and f is the frequency of the triangular carrier signal; phase shifting the triangular carrier signal according to the phase shift time input signal; comparing the modulation signal with the phase-shifted triangular carrier signal to obtain a switch control signal;

[0074] When N = 3 and f = 1000 Hz, the phase shift time input signal pulse of the three current generators is 0, 1 / 3000 seconds, and 2 / 3000 seconds respectively; Figure 5 and Figure 6 As shown, for a single current generator, when the amplitude of the modulation signal is higher than the triangular carrier signal, the switch control signal will control the switch tubes T1 and T4 to be turned on, and T2 and T3 to be turned off; when the amplitude of the modulation signal is lower than the triangular carrier signal, the switch control signal will control the switch tubes T2 and T3 to be turned on, and T1 and T4 to be turned off; the triangular carrier signals of the three current generators are staggered in time, and the stagger amount is 1 / N of the carrier cycle. Through this carrier phase-shifted pulse width modulation technology, a higher equivalent switching frequency can be achieved in the series system, and the harmonic content of the output waveform of the current generating device can be significantly reduced;

[0075] Step S6, controlling each switch tube of the inverter in the current generating device based on the switch control signal.

[0076] It can be seen from the above that the control method of the current generating device in the embodiment of the present invention performs a proportional operation on the DC input voltage of the current generating device and the output signal of the PIR controller, and can associate the modulation signal output by the PIR controller with the actual working state of the current generating device (i.e., the DC input voltage). The switching control signal obtained by subsequently performing pulse width modulation on the modulation signal can reflect the actual working state of the inverter. Controlling the inverter based on the switching control signal can improve the output current accuracy of the current generating device.

[0077] In some embodiments, after step S4 and before step S5, Figure 4 As shown, the control method of the current generating device may further include: limiting the amplitude of the modulation signal. Amplitude limiting can ensure that the amplitude of the modulation signal is within the allowable range, thereby preventing system instability or damage caused by over-modulation.

[0078] Figure 7 The simulation results of the output current waveform and its corresponding fast Fourier transform (FFT) analysis results after the current generator is controlled without harmonic injection are presented. In the simulation, the reference current is set to 780A and the frequency is 50Hz. The simulation results show that its fundamental component reaches 779.6A, and the deviation from the reference current is only 0.051%, indicating that the current generator has extremely high output accuracy, and the total harmonic distortion (THD) is calculated to be 0.07%. This extremely low value highlights the remarkable effectiveness of the embodiments of the present invention in suppressing harmonics and maintaining the purity of the current waveform.

[0079] Figure 8The simulation results and FFT analysis results of the output current waveform of the current generator after controlling it under specific harmonic injection conditions are shown. Under this condition, the fundamental amplitude of the reference current is set to 780A and the frequency is 50Hz, and a specific proportion of harmonic components are injected, including 3% of the 3rd harmonic, 1.5% of the 6th harmonic, 1% of the 15th harmonic, and 0.5% of the 24th harmonic. The simulation results show that despite the presence of harmonic injection, the fundamental amplitude of the output current of the current generator remains at 779.6A, and the deviation from the reference current is only 0.051%, which reflects the high stability of the fundamental amplitude of the output current. Further analysis of the FFT results shows that the deviations between the actual content of each harmonic and the injected value are at extremely low levels: the actual content of the 3rd harmonic is 2.99899%, with a deviation of 0.034% from the injected value; the actual content of the 6th harmonic is 1.49948%, with a deviation of 0.035% from the injected value; the actual content of the 15th harmonic is 0.999681%, with a deviation of 0.032% from the injected value; and the actual content of the 24th harmonic is 0.498959%. Although the deviation is slightly larger at 0.21%, it is still much smaller than its injected value, indicating that the embodiments of the present invention have a good effect in suppressing the generation of non-target harmonics. In summary, Figure 8 It is verified that the embodiment of the present invention has good effects in maintaining the stability of the fundamental wave amplitude and effectively controlling the harmonic components in a complex harmonic environment.

[0080] like Fig. 9 As shown, the embodiment of the present invention also provides a control device for a current generating device, including:

[0081] An acquisition module, used to acquire a preset reference current, an actual output current of a current generating device, and a DC input voltage;

[0082] A determination module, used for determining a current error between a reference current and an actual output current;

[0083] An input module, used for inputting the current error into the PIR controller to obtain an output signal of the PIR controller;

[0084] An operation module is used to perform a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal;

[0085] A modulation module, used for performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device;

[0086] The control module is used to control each switch tube of the inverter in the current generating device based on the switch control signal.

[0087] In some implementations, the computing module may be specifically used to:

[0088] The ratio of the output signal of the PIR controller to the DC input voltage is calculated to obtain a modulation signal.

[0089] In some embodiments, the control device of the current generating device may further include:

[0090] The limiting module is used to limit the modulated signal.

[0091] In some embodiments, the current generating device is composed of a plurality of current generators connected in series, and the DC input voltage is the sum of the DC side filter capacitor voltages of the plurality of current generators;

[0092] The modulation module can be specifically used for:

[0093] Obtain a preset triangular carrier signal;

[0094] Determine the phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of current generators, and f is the frequency of the triangular carrier signal;

[0095] Phase shifting the triangular carrier signal according to the phase shift time input signal;

[0096] The modulation signal is compared with the phase-shifted triangular carrier signal to obtain a switch control signal.

[0097] Based on the same inventive concept as the control method of the current generating device mentioned above, an embodiment of the present invention also provides a computer device, including a memory, a processor and a computer program stored in the memory, and the processor executes the computer program to implement the steps of any one of the control methods of the current generating device mentioned above.

[0098] Since the computer device introduced in the embodiment of the present invention is a computer device used to implement the control method of the current generating device in the embodiment of the present invention, based on the control method of the current generating device introduced in the embodiment of the present invention, the technical personnel in the field can understand the specific implementation of the computer device in the embodiment of the present invention and its various variations, so how the computer device implements the method in the embodiment of the present invention is not described in detail here. As long as the computer device used by the technical personnel in the field to implement the control method of the current generating device in the embodiment of the present invention, it belongs to the scope of protection of the present invention.

[0099] Based on the same inventive concept as the control method of the current generating device mentioned above, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the control methods of the current generating device mentioned above.

[0100] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0101] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0102] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0103] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0104] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A control method for a current generating device, characterized in that: include: Obtaining a preset reference current, an actual output current of a current generating device, and a DC input voltage; determining a current error between the reference current and the actual output current; Inputting the current error into a PIR controller to obtain an output signal of the PIR controller; Performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal; Performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device; Each switch tube of the inverter in the current generating device is controlled based on the switch control signal.

2. The control method of the current generating device according to claim 1, characterized in that: The step of performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal comprises: The ratio of the output signal of the PIR controller to the DC input voltage is calculated to obtain the modulation signal.

3. The control method of the current generating device according to claim 1, characterized in that: After performing proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal and before performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device, the method further includes: The modulated signal is limited.

4. The control method of the current generating device according to claim 1, characterized in that: The current generating device is composed of a plurality of current generators connected in series, and the DC input voltage is the sum of the DC side filter capacitor voltages of the plurality of current generators; The step of performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device includes: Obtain a preset triangular carrier signal; Determine the phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of the current generators, and f is the frequency of the triangular carrier signal; Phase shifting the triangular carrier signal according to the phase shift time input signal; The modulation signal is compared with the phase-shifted triangular carrier signal to obtain the switch control signal.

5. A control device for a current generating device, characterized in that: include: An acquisition module, used to acquire a preset reference current, an actual output current of a current generating device, and a DC input voltage; A determination module, used to determine a current error between the reference current and the actual output current; An input module, used for inputting the current error into a PIR controller to obtain an output signal of the PIR controller; An operation module, used for performing a proportional operation on the DC input voltage and the output signal of the PIR controller to obtain a modulation signal; A modulation module, used for performing pulse width modulation on the modulation signal to obtain a switch control signal of the current generating device; A control module is used to control each switch tube of the inverter in the current generating device based on the switch control signal.

6. The control device for the current generating device according to claim 5, characterized in that: The operation module is specifically used for: The ratio of the output signal of the PIR controller to the DC input voltage is calculated to obtain the modulation signal.

7. The control device of the current generating device according to claim 5, characterized in that: Also includes: A limiting module is used to limit the modulated signal.

8. The control device for the current generating device according to claim 5, characterized in that: The current generating device is composed of a plurality of current generators connected in series, and the DC input voltage is the sum of the DC side filter capacitor voltages of the plurality of current generators; The modulation module is specifically used for: Obtain a preset triangular carrier signal; Determine the phase shift time input signal of each current generator according to the triangular carrier signal, the phase shift time of the phase shift time input signal of the nth current generator is (n-1) / Nf seconds, N is the total number of the current generators, and f is the frequency of the triangular carrier signal; Phase shifting the triangular carrier signal according to the phase shift time input signal; The modulation signal is compared with the phase-shifted triangular carrier signal to obtain the switch control signal.

9. A computer device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 1 to 4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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