A single-phase control system and method based on d-q rotating coordinate transformation

Abstract

The application discloses a single-phase control system and method based on d-q rotating coordinate transformation, adopts a double-loop architecture of a voltage outer loop and a current inner loop, the voltage outer loop filters a sampling voltage through a second-order generalized integrator, obtains d-q axis voltage components through Park transformation, and generates a d-axis current reference value by using a PI regulator; the current inner loop also filters and transforms the sampling current, inputs a current error into a PI regulator to obtain a current compensation component, eliminates the coupling influence between d-q axes through decoupling operation, and finally generates a duty cycle signal for driving an inverter through inverse coordinate transformation. Through the double-loop cooperative control and decoupling algorithm, the application realizes high-precision voltage stabilization of the inverter output voltage and fast dynamic response of the current, effectively suppresses harmonics and load disturbance, and improves the output power quality.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter control technology, and in particular to a single-phase control system and method based on dq rotating coordinate transformation. Background Technology

[0002] In residential and industrial sectors such as distributed generation, uninterruptible power supplies (UPS), and vehicle power supply, single-phase inverters have become the core device for converting DC power to AC power due to their advantages such as simple structure, controllable cost, and adaptability to single-phase load requirements. With the development of power electronics technology, users have placed increasingly stringent requirements on the output power quality (such as harmonic distortion rate THD), dynamic response speed, and disturbance rejection capability of single-phase inverters, especially under complex operating conditions such as nonlinear load connection or grid voltage distortion, where high-precision voltage regulation and rapid current tracking are required.

[0003] Compared to three-phase inverters, single-phase inverters have inherent technical bottlenecks in control: three-phase systems can flexibly switch between stationary and synchronous rotating coordinate systems through Clark transformation and Park transformation, and then use mature dq-axis decoupling control to achieve high-precision regulation. However, single-phase systems only have a single voltage / current path and cannot directly generate orthogonal components, making it difficult for three-phase control algorithms to be directly adapted. Only single-phase dedicated control strategies (such as single-loop PI control, repetitive control, etc.) can be used. Traditional single-phase control schemes generally suffer from the following drawbacks: First, there is a contradiction between dynamic response and steady-state accuracy. For example, although simple PI control has a fast response, it is weak in suppressing periodic harmonics, which can easily lead to excessive output THD. Although repetitive control can suppress periodic errors, there is a periodic delay, which can easily cause voltage drops or overshoots when the load changes abruptly. Second, there is insufficient anti-interference capability. When the grid voltage contains harmonics, DC bias, or unbalanced disturbances, traditional control algorithms cannot accurately extract the fundamental component, resulting in a significant decrease in control accuracy. Especially in weak grid environments, phase-locked loop deviations or even system instability are likely to occur. Third, power decoupling is difficult. The instantaneous power fluctuations of a single-phase system are severe, and traditional control cannot achieve accurate separation of active and reactive power. When multiple machines are connected in parallel, circulating currents are easily generated, affecting system stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a single-phase control system and method based on dq rotating coordinate transformation. Through the coordinated control of the voltage outer loop and the current inner loop, combined with a decoupling algorithm, it achieves high-precision voltage regulation of the inverter output voltage and rapid dynamic response of the current, effectively solving the problems of low control accuracy, slow dynamic response, and weak anti-interference capability of existing single-phase inverters.

[0005] The objective of this invention is achieved in one aspect as follows: a single-phase control system based on dq rotating coordinate transformation, including an H6 bridge inverter circuit, and further including a conditioning circuit, a second-order generalized integrator, a Park transformation module, an inverter voltage and current dual closed-loop controller, a decoupling operation module, an inverse Park transformation module, an inverse Clark transformation module, a PWM generator, and a drive circuit.

[0006] The conditioning circuit is used to collect the output voltage and current of the H6 bridge inverter circuit and filter them through a second-order generalized integrator to output the voltage and current components in the two-phase stationary coordinate system.

[0007] The second-order generalized integrator is used to extract the fundamental positive sequence component from the AC sampling signal and suppress harmonics and DC bias interference.

[0008] The Park transformation module is used to convert the voltage and current components in the stationary coordinate system into the d and q axis components in the synchronous rotating coordinate system.

[0009] The inverter voltage and current dual closed-loop controller is used to generate a d-axis current reference value I based on the voltage error. d_ref And generate d-axis current compensation component I based on d-axis current error signal. d_PI_ref ; Generate q-axis current compensation component I based on q-axis current error signal q_PI_ref ;

[0010] The decoupling operation module is used to eliminate the coupling effect between the d and q axes and output the decoupled d and q axis voltage components.

[0011] The inverse Park transformation module is used to convert the voltage component in the synchronous rotating coordinate system back to the α and β axis components in the stationary coordinate system.

[0012] The inverse Clark transformation module is used to convert the α and β axis voltage components into the duty cycle signal DutyD that drives the inverter switching transistors;

[0013] The PWM generator is used to generate switching transistor pulse control signals and transmit the control signals to the drive circuit.

[0014] The drive circuit is used to generate switch drive signals to control the on and off of the switching transistors in the H6 bridge inverter circuit.

[0015] Furthermore, the input terminal of the conditioning circuit is connected to the single-phase H6 bridge inverter circuit, and the output terminal of the conditioning circuit is connected to the input terminal of the second-order generalized integrator and the input terminal of the inverter voltage and current dual closed-loop controller.

[0016] Furthermore, the output of the second-order generalized integrator is connected to the input of the Park transform module; the output of the Park transform module is connected to the inverter voltage and current dual-loop controller.

[0017] The output of the inverter voltage and current dual-loop controller is connected to the decoupling calculation module.

[0018] The output of the decoupling operation module is connected to the inverse Park transform module;

[0019] The output of the inverse Park transform module is connected to the input of the PWM generator.

[0020] The output of the PWM generator is connected to the input of the drive circuit.

[0021] Another aspect of the objective of this invention is achieved as follows: a single-phase control method based on dq rotating coordinate transformation, comprising the following steps:

[0022] 1) The conditioning circuit samples the output voltage and output current of the H6 bridge inverter circuit and outputs the voltage and current sample values ​​of the inverter to the second-order generalized integrator.

[0023] 2) The AC voltage and AC current samples from the inverter output are filtered and subjected to quadrature signal processing in a second-order generalized integrator to obtain the α-axis and α-axis in the two-phase stationary coordinate system. The voltage and current components of the axis are used to extract the fundamental positive sequence component and suppress harmonics and DC bias.

[0024] 3) The voltage and current components of the α and β axes in the two-phase stationary coordinate system are transformed by the Park transformation module to obtain the voltage and current components of the d and q axes in the synchronous rotating coordinate system.

[0025] 4) The inverter voltage and current dual closed-loop controller generates the d-axis current reference value I based on the voltage error. d_ref And generate d-axis current compensation component I based on d-axis current error signal. d_PI_ref ; Generate q-axis current compensation component I based on q-axis current error signal q_PI_ref ;

[0026] 5) The d-axis current compensation component I is processed through the decoupling operation module. d_PI_ref and q-axis compensation current component I q_PI_ref Decoupling calculations were performed to obtain the decoupled d-axis voltage components. and q-axis voltage component ;

[0027] 6) The d-axis and q-axis voltage components in the synchronous rotating coordinate system are converted back to the α-axis feedback voltage in the stationary coordinate system using the inverse Park transformation module. and Shaft feedback voltage ;

[0028] 7) Feedback voltage along the α-axis and Shaft feedback voltage Input the inverse Clark transform module, which generates the duty cycle signal DutyD to drive the inverter switching transistors;

[0029] 8) The duty cycle signal DutyD is sent to the PWM generator. The PWM generator generates a switching transistor pulse control signal. The switching transistor pulse control signal is then passed through the drive circuit to generate a switching transistor drive signal. The switching transistor drive signal is used to control the switching transistors in the H6 bridge inverter circuit to turn on and off.

[0030] Furthermore, step 2) specifically includes: utilizing the orthogonal signal generation characteristics of the second-order generalized integral to output an orthogonal virtual component with the same frequency and a 90° phase difference from the original sampled signal, thereby expanding the single-phase AC quantity into an α-axis and α-axis in a two-phase stationary coordinate system. The equivalent AC component of the axis;

[0031] The AC voltage sample values ​​output by the H6 bridge inverter circuit are filtered and subjected to quadrature signal processing to obtain the α-axis voltage components in the two-phase stationary coordinate system. and Axis voltage component V β This enables the extraction of the fundamental positive sequence component and the suppression of harmonics and DC bias.

[0032] The AC current sample value output from the H6 bridge inverter circuit is filtered and subjected to quadrature signal processing to obtain the α-axis current component in the two-phase stationary coordinate system. and Axial current component I β .

[0033] Furthermore, step 3) specifically includes: processing the α-axis voltage components in the two-phase stationary coordinate system. and Axis voltage component V β Perform a Park coordinate transformation to obtain the d-axis DC voltage component in the synchronous rotating coordinate system. and q-axis DC voltage component ;

[0034] For the α-axis current component in a two-phase stationary coordinate system and Axial current component I βPerform a Park coordinate transformation to obtain the d-axis DC current component in the synchronous rotating coordinate system. and q-axis DC current component I q .

[0035] Furthermore, step 4) specifically includes: converting the d-axis voltage component... The subtractor sent to the inverter's voltage and current dual closed-loop controller is compared with the given AC voltage amplitude reference value. The difference is calculated to obtain the voltage error signal. This voltage error signal is then input to the PI controller, which outputs the d-axis current reference value. As the active current command of the inner current loop;

[0036] The d-axis current component I d The subtractor sent to the inverter voltage and current dual closed-loop controller and the d-axis current reference value I d_ ref The difference is calculated to obtain the d-axis current error signal, which is then input to the d-axis PI controller to output the d-axis current compensation component I. d_PI_ref ; the q-axis current component I q The difference between the input and the zero reference value is calculated by the subtractor to obtain the q-axis current error signal, which is then input to the q-axis PI controller, outputting the q-axis current compensation component I. q_PI_ref The q-axis current reference value is set to zero to suppress negative sequence components and harmonic distortion in the inverter output voltage and improve the output power quality.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows: by accurately generating virtual orthogonal components through second-order generalized integrals, a three-phase stationary coordinate system is constructed, so that mature control algorithms such as three-phase Park transformation and dq-axis decoupling can be directly applied to single-phase inverters, giving full play to the high-precision adjustment advantages of three-phase control algorithms.

[0038] Second-order generalized integrals can effectively extract the fundamental positive-sequence components of voltage and current, suppressing harmonics, DC bias, and grid distortion interference, providing high-quality signals for coordinate transformation and dual-loop regulation, and reducing the output power harmonic distortion rate (THD). The outer voltage loop ensures the steady-state accuracy of the output voltage, while the inner current loop achieves rapid dynamic response and current limiting. Combined with dq-axis decoupling control, the effects of cross-coupling are eliminated. Decoupling operations eliminate the coupling effects between the d and q axes, making the control loops of the d and q axes independent of each other, improving the dynamic response speed of the inner current loop, and significantly enhancing the system's resistance to load surges. The control device can be integrated into a digital signal processor (DSP) to achieve fully digital control, flexible parameter adjustment, and adaptability to single-phase inverter scenarios of different power levels. The method of this invention can achieve high precision and high stability in single-phase inverter tracking control. Furthermore, the single-phase control strategy based on dq rotating coordinate transformation of this invention uses digital control, requires fewer program resources, and does not require additional hardware, thus offering high cost-effectiveness and suitability for engineering applications. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the single-phase control strategy based on dq rotating coordinate transformation of the present invention.

[0041] Figure 2 This is the control block diagram for the second-order generalized integral of the present invention.

[0042] Figure 3 This is a schematic diagram illustrating the composition principle of an embodiment of the present invention.

[0043] Figure 4 The waveform diagram for the off-grid inverter of this invention is shown.

[0044] Figure 5 The waveform diagram is from an off-grid inverter experiment according to an embodiment of the present invention.

[0045] Figure 1 Symbol names in the code: 1 H6 bridge inverter circuit, 2 conditioning circuit, 3 inverter voltage and current dual closed-loop controller, 4 second-order generalized integrator, 5 Park converter module, 6 decoupling operation module, 7 inverse Park converter module, 8 inverse Clark converter module, 9 PWM generator, 10 drive circuit.

[0046]

[0047] Figure 2 Symbol names in:

[0048]

[0049] Figure 3 Symbol names in:

[0050]

[0051] Other symbols are the same Figure 1 .

[0052] Figure 4 Symbol names in:

[0053] Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] like Figure 1 The single-phase control system based on dq rotating coordinate transformation shown includes an H6 bridge inverter circuit 1, a conditioning circuit 2, a second-order generalized integrator 4, a Park transformation module 5, an inverter voltage and current dual closed-loop controller 3, a decoupling operation module 6, an inverse Park transformation module 7, an inverse Clark transformation module 8, a PWM generator 9, and a drive circuit 10.

[0056] The input terminal of the conditioning circuit 2 is connected to the single-phase H6 bridge inverter circuit 1, and the output terminal of the conditioning circuit 2 is connected to the input terminal of the second-order generalized integrator 4 and the input terminal of the inverter voltage and current dual closed-loop controller 3.

[0057] The output of the second-order generalized integrator 4 is connected to the input of the Park converter module 5; the output of the Park converter module 5 is connected to the inverter voltage and current dual closed-loop controller 3.

[0058] The output of the inverter voltage and current dual closed-loop controller 3 is connected to the decoupling operation module 6; the inverter voltage and current dual closed-loop controller 3 includes three subtractors and three PI regulators; the output of the decoupling operation module 6 is connected to the inverse Park transform module 7; the output of the inverse Park transform module 7 is connected to the input of the PWM generator 9; the output of the PWM generator 9 is connected to the input of the drive circuit 10.

[0059] The conditioning circuit is used to acquire the output voltage and current of the H6 bridge inverter circuit and filter them through a second-order generalized integrator to output the voltage and current components in the two-phase stationary coordinate system.

[0060] The second-order generalized integrator is used to extract the fundamental positive sequence component from the AC sampled signal and suppress harmonics and DC bias interference.

[0061] The Park transformation module is used to convert voltage and current components in a stationary coordinate system into d-axis and q-axis components in a synchronously rotating coordinate system.

[0062] The inverter voltage and current dual-loop controller is used to generate a d-axis current reference value Id_ref based on the voltage error, and to generate a d-axis current compensation component I based on the d-axis current error signal. d_PI_ref ; Generate q-axis current compensation component I based on q-axis current error signal q_PI_ref ;

[0063] The decoupling module is used to eliminate the coupling effect between the d and q axes and output the decoupled d and q axis voltage components.

[0064] The inverse Park transformation module is used to convert the voltage components in the synchronous rotating coordinate system back to the α and β axis components in the stationary coordinate system;

[0065] The inverse Clark transform module is used to convert the α and β axis voltage components into the duty cycle signal DutyD that drives the inverter switching transistors;

[0066] The PWM generator is used to generate pulse control signals for the switching transistors and transmit the control signals to the drive circuit.

[0067] The drive circuit is used to generate switch drive signals to control the on and off of the switching transistors in the H6 bridge inverter circuit.

[0068] A single-phase control method based on dq rotating coordinate transformation, for an inverter system based on an H6 bridge circuit, includes the following steps:

[0069] By real-time acquisition of the inverter's output voltage V R With the inverter's output current i R After passing through conditioning circuit 2, the corresponding output voltage sampling value and output current sampling value of the inverter are sent to the second-order generalized integrator 4.

[0070] In the second-order generalized integrator 4, the sampled AC voltage values ​​output by the inverter are first filtered and processed with orthogonal signals to obtain the α-axis voltage component V in the two-phase stationary coordinate system. α and Axis voltage component V β This achieves the extraction of the fundamental positive sequence component and the suppression of harmonics and DC bias, and then V α and V β The data is sent to the Park transformation module for Park coordinate transformation to obtain the d-axis voltage component in the synchronous rotating coordinate system. and q-axis voltage component U q d-axis voltage component The subtractor sent to the inverter voltage and current dual closed-loop controller 3 is compared with the given AC voltage amplitude reference value. The difference is calculated to obtain the voltage error signal. This voltage error signal is then input to the PI controller, which outputs the d-axis current reference value. , which serves as the active current command within the current loop.

[0071] Simultaneously, the sampled AC current value output by the inverter is input to the second-order generalized integrator 4 for filtering and quadrature signal processing to obtain the α-axis current component I in the two-phase stationary coordinate system. α and Axial current component Iβ Then and The current is sent to Park transformation module 5 for Park coordinate transformation to obtain the d-axis current component in the synchronous rotating coordinate system. and q-axis current component d-axis current component The subtractor and d-axis current reference value sent to the inverter voltage and current dual closed-loop controller 3 The difference is calculated to obtain the d-axis current error signal, which is then input to the d-axis PI controller to output the d-axis current compensation component. ; q-axis current component The difference between the current and the zero reference value is calculated by the subtractor to obtain the q-axis current error signal, which is then input to the q-axis PI controller and outputs the q-axis current compensation component. ; compensate the d-axis current component and q-axis compensation current component The voltage is sent to decoupling calculation module 6 for decoupling calculation to obtain the decoupled d-axis voltage component. and q-axis voltage component ; d-axis voltage component and q-axis voltage component The α-axis feedback voltage in the two-phase stationary coordinate system is obtained by sending the signal to the inverse Park transformation module 7. and Shaft feedback voltage ; Feedback voltage along the α axis and Shaft feedback voltage The signal is sent to the inverse Clark conversion module 8 to generate the duty cycle signal DutyD for driving the inverter switching transistors. The duty cycle signal DutyD is then sent to the PWM generator 9, which generates switching transistor pulse control signals (PWM1A, PWM1B, PWM2A, PWM2B). These switching transistor pulse control signals (PWM1A, PWM1B, PWM2A, PWM2B) are then processed by the drive circuit 10 to generate switching transistor drive signals (EPWM1A, EPWM1B, EPWM2A, EPWM2B). These switching transistor drive signals (EPWM1A, EPWM1B, EPWM2A, EPWM2B) are used to control the on and off states of the switching transistors (Q1, Q2, Q3, Q4, Q5, Q6) in the H6 bridge inverter circuit.

[0072] like Figure 2 As shown, the output voltage and current sampling signals of the single-phase inverter are input into the second-order generalized integral module. Utilizing the orthogonal signal generation characteristics of the second-order generalized integral, an orthogonal virtual component with the same frequency and a 90° phase difference from the original sampling signal is output, thereby expanding the single-phase AC quantity into an equivalent AC component in a two-phase stationary coordinate system (α-β).

[0073] Based on the α-β two-phase components of the second-order generalized integral output, the voltage and current AC quantities in the equivalent three-phase stationary coordinate system are constructed through the "virtual three-phase extension rule". Then, the virtual three-phase quantities are converted into voltage and current DC components in the synchronous rotating coordinate system (dq) through the Park transformation, thereby achieving coordinate system compatibility between the single-phase system and the three-phase control algorithm.

[0074] The commonly used strategies of dq axis decoupling control and PI regulation in three-phase inverters are directly applied to the above-mentioned virtual dq DC component. The mature algorithm of three-phase control is used to realize the closed-loop regulation of voltage and current of single-phase inverter. Finally, the control quantity is mapped back to the drive signal of single-phase system through inverse Park transformation and inverse Clark transformation to complete the control closed loop.

[0075] Through the above core implementation, this invention can directly reuse mature control algorithms for three-phase inverters (such as decoupling control and harmonic suppression strategies under synchronous rotating coordinate systems). At the same time, it leverages the orthogonal signal generation capability of second-order generalized integrals to ensure the synchronization of the virtual coordinate system, thus solving the problems of high complexity and slow dynamic response of single-phase inverter control algorithms. This achieves the universality of the control strategy and the improvement of control performance.

[0076] A specific embodiment of the present invention is as follows:

[0077] like Figure 3 As shown, the invention is applied to a single-phase photovoltaic energy storage inverter, which consists of the following components: an MPPT controller, a single-phase H6 bridge inverter circuit, a conditioning circuit 2, a drive circuit 10, and a CPU based on a TMS320F28035 controller. The CPU implements a single-phase control strategy based on dq rotating coordinate transformation and a PWM generator 9. PV photovoltaic modules are connected to the MPPT controller, and the inverter output is connected to the power grid and the load. The H6 bridge inverter has six power switches (Q1, Q2, Q3, Q4, Q5, Q6), where Q1, Q5, and Q6 are on the positive half-axis, and Q2, Q3, and Q4 are on the negative half-axis.

[0078] A single-phase H6 bridge inverter circuit with a power rating of 8KW has a filter inductance of [missing information]. Filter capacitor Bus capacitor Bus voltage in the experiment Switching frequency Interruption cycle The AC load R=6Ω, the MPPT voltage range of the PV module is 150 V~450V, and the rated output voltage is 230V.

[0079] like Figure 3and Figure 1 In the single-phase H6 bridge inverter circuit 1, the switching transistors (Q1, Q2, Q3, Q4, Q5, Q6) are Daxin's DXG75N65HS, the operational amplifier in the sampling and conditioning circuit is TI's TL047IDR, and the digital control chip is TI's TMS320F28035.

[0080] like Figure 1 As shown, the output voltage of the inverter in the H6 bridge inverter circuit 1 With the inverter's output current i R After passing through conditioning circuit 2, the voltage is sent to the AD port of the DSP TMS320F28035 to form the corresponding inverter output voltage. The output current i of the inverter R The sampled voltage values ​​of the inverter output are sent to a second-order generalized integrator. After transformation by the second-order generalized integrator, the corresponding values ​​in the two-phase stationary coordinate system can be obtained. and The fundamental positive sequence component of the sampled voltage value was extracted, and harmonics and DC bias were suppressed. The obtained voltage component was then sent to Park transformation module 5 for Park coordinate transformation to obtain the d-axis voltage component in the synchronous rotating coordinate system. and q-axis voltage component d-axis voltage component The subtractor sent to the inverter's voltage and current dual closed-loop controller is compared with the given AC voltage amplitude reference value. The difference is calculated to obtain the voltage error signal. This voltage error signal is then input to a PI controller to form the voltage outer loop, and its output is the current reference value on the d-axis. , which serves as the active current command within the current loop.

[0081] Simultaneously, the sampled AC current value output by the inverter is input to a second-order generalized integrator for filtering and quadrature signal processing to obtain the two-phase stationary coordinate system. Axis current components and Axis current components The obtained current component is then sent to Park transformation module 5 for Park coordinate transformation to obtain the d-axis current component in the synchronous rotating coordinate system. and q-axis current components d-axis current component The subtractor sent to the voltage and current dual closed-loop controller 3 and the d-axis current reference value The difference is calculated to obtain the d-axis current error signal, which is then input to the d-axis PI controller to output the d-axis current compensation component. ; q-axis current component The difference between the current and the zero reference value is calculated by the subtractor to obtain the q-axis current error signal, which is then input to the q-axis PI controller and outputs the q-axis current compensation component. ; compensate the d-axis current component and q-axis compensated current component The voltage is sent to decoupling calculation module 6 for decoupling calculation to obtain the decoupled d-axis voltage component. and q-axis voltage component d-axis voltage components and q-axis voltage component The two phases of the stationary coordinate system are obtained by sending the inverse Park transformation module 7. Shaft feedback voltage and Shaft feedback voltage .Will Shaft feedback voltage and Shaft feedback voltage The signal is sent to the inverse Clark conversion module 8 to generate the duty cycle signal DutyD for driving the inverter switching transistors. The duty cycle signal DutyD is then sent to the PWM generator 9, which generates switching transistor pulse control signals (PWM1A, PWM1B, PWM2A, PWM2B). These switching transistor pulse control signals (PWM1A, PWM1B, PWM2A, PWM2B) are then processed by the drive circuit 10 to generate switching transistor drive signals (EPWM1A, EPWM1B, EPWM2A, EPWM2B). These switching transistor drive signals (EPWM1A, EPWM1B, EPWM2A, EPWM2B) are used to control the on and off states of the switching transistors (Q1, Q2, Q3, Q4, Q5, Q6) in the H6 bridge inverter circuit.

[0082] Figure 4 The simulation waveform at rated output voltage, built according to a specific embodiment, is shown in the table below.

[0083]

[0084] according to Figure 4 The data and waveforms show that the output voltage and current waveforms have a high sinusoidal degree, and the effective value of the output voltage meets the given conditions. The control method of this invention can realize the control of a single-phase inverter using a three-phase algorithm, thereby achieving zero steady-state error control for single-phase inverters.

[0085] In Figure 5, channel 1 represents the inverter output voltage VR (200V / div), and channel 2 represents the inverter output current. (50A / div), Channel 3 shows the waveform of switch Q3 driven by EPWM2A (20V / div), and Channel 4 shows the waveform of switch Q1 driven by EPWM1A (20V / div). As can be seen from the figures, in actual operation, the inverter output voltage and output current waveforms have high sinusoidal strength, and the output voltage can be stabilized at the given value. This demonstrates that the single-phase control strategy based on dq rotating coordinate transformation of this invention achieves control of the single-phase inverter using a three-phase algorithm, realizing zero steady-state error control for single-phase operation.

[0086] The present invention has the following advantages:

[0087] (1) This invention enables mature three-phase Park transformation and dq axis decoupling control algorithms to be directly applied to single-phase inverters through virtual three-phase construction and dq coordinate transformation, giving full play to the high-precision adjustment advantages of three-phase control algorithms.

[0088] (2) The second-order generalized integral can effectively extract the fundamental positive sequence components of voltage and current, suppress harmonics, DC bias and grid distortion interference, provide high-quality signals for coordinate transformation and dual-loop regulation, and reduce the harmonic distortion rate (THD) of output power.

[0089] (3) Mature three-phase vector control and phase-locked loop (PLL) algorithm modules are directly ported, reducing the amount of code development and facilitating later upgrades to support three-phase and single-phase compatibility. Digital control is used, requiring minimal program resources and no additional hardware, thus offering high cost-effectiveness and suitability for engineering applications.

[0090] (4) The control device can be integrated into a digital signal processor (DSP) to achieve fully digital control, with flexible parameter adjustment, and adaptable to single-phase inverter scenarios with different power levels.

[0091] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A single-phase control system based on dq rotating coordinate transformation, comprising an H6 bridge inverter circuit, characterized in that, It also includes a conditioning circuit, a second-order generalized integrator, a Park transform module, an inverter voltage and current dual closed-loop controller, a decoupling operation module, an inverse Park transform module, an inverse Clark transform module, a PWM generator, and a drive circuit; The conditioning circuit is used to collect the output voltage and current of the H6 bridge inverter circuit and filter them through a second-order generalized integrator to output the voltage and current components in the two-phase stationary coordinate system. The second-order generalized integrator is used to extract the fundamental positive sequence component from the AC sampling signal and suppress harmonics and DC bias interference. The Park transformation module is used to convert the voltage and current components in the stationary coordinate system into the d and q axis components in the synchronous rotating coordinate system. The inverter voltage and current dual closed-loop controller is used to generate a d-axis current reference value I based on the voltage error. d_ref And generate the d-axis current compensation component I based on the d-axis current error signal. d_PI_ref ; Generate q-axis current compensation component I based on q-axis current error signal q_PI_ref ; The decoupling operation module is used to eliminate the coupling effect between the d and q axes and output the decoupled d and q axis voltage components. The inverse Park transformation module is used to convert the voltage component in the synchronous rotating coordinate system back to the α and β axis components in the stationary coordinate system. The inverse Clark transformation module is used to convert the α and β axis voltage components into the duty cycle signal DutyD that drives the inverter switching transistors; The PWM generator is used to generate switching transistor pulse control signals and transmit the control signals to the drive circuit. The drive circuit is used to generate switch drive signals to control the on and off of the switching transistors in the H6 bridge inverter circuit.

2. The single-phase control system based on dq rotating coordinate transformation according to claim 1, characterized in that, The input terminal of the conditioning circuit is connected to the single-phase H6 bridge inverter circuit, and the output terminal of the conditioning circuit is connected to the input terminal of the second-order generalized integrator and the input terminal of the inverter voltage and current dual closed-loop controller.

3. A single-phase control system based on dq rotating coordinate transformation according to claim 1, characterized in that, The output of the second-order generalized integrator is connected to the input of the Park transform module; the output of the Park transform module is connected to the inverter voltage and current dual closed-loop controller. The output of the inverter voltage and current dual closed-loop controller is connected to the decoupling calculation module; the inverter voltage and current dual closed-loop controller includes three subtractors and three PI regulators; The output of the decoupling operation module is connected to the inverse Park transform module; The output of the inverse Park transform module is connected to the input of the PWM generator. The output of the PWM generator is connected to the input of the drive circuit.

4. A single-phase control method based on dq rotating coordinate transformation, characterized in that, Includes the following steps: 1) The conditioning circuit samples the output voltage and output current of the H6 bridge inverter circuit and outputs the voltage and current sample values ​​of the inverter to the second-order generalized integrator. 2) The AC voltage and AC current samples from the inverter output are filtered and subjected to quadrature signal processing in a second-order generalized integrator to obtain the α-axis and α-axis in the two-phase stationary coordinate system. The voltage and current components of the axis are used to extract the fundamental positive sequence component and suppress harmonics and DC bias. 3) The voltage and current components of the α and β axes in the two-phase stationary coordinate system are transformed by the Park transformation module to obtain the voltage and current components of the d and q axes in the synchronous rotating coordinate system. 4) The inverter voltage and current dual closed-loop controller generates the d-axis current reference value I based on the voltage error. d_ref And generate d-axis current compensation component I based on d-axis current error signal. d_PI_ref ; Generate q-axis current compensation component I based on q-axis current error signal q_PI_ref ; 5) The d-axis current compensation component I is processed through the decoupling operation module. d_PI_ref and q-axis compensation current component I q_PI_ref Decoupling calculations were performed to obtain the decoupled d-axis voltage components. and q-axis voltage component ; 6) The d-axis and q-axis voltage components in the synchronous rotating coordinate system are converted back to the α-axis feedback voltage in the stationary coordinate system using the inverse Park transformation module. and Shaft feedback voltage ; 7) Feedback voltage along the α axis and Shaft feedback voltage Input the inverse Clark transform module, which generates the duty cycle signal DutyD to drive the inverter switching transistors; 8) The duty cycle signal DutyD is sent to the PWM generator. The PWM generator generates a switching transistor pulse control signal. The switching transistor pulse control signal is then passed through the drive circuit to generate a switching transistor drive signal. The switching transistor drive signal is used to control the switching transistors in the H6 bridge inverter circuit to turn on and off.

5. A single-phase control method based on dq rotating coordinate transformation according to claim 4, characterized in that, Step 2) specifically includes: utilizing the orthogonal signal generation characteristics of the second-order generalized integral, outputting an orthogonal virtual component with the same frequency and a 90° phase difference from the original sampled signal, thereby expanding the single-phase AC quantity into an α-axis and α-axis in a two-phase stationary coordinate system. The equivalent AC component of the axis; The AC voltage sample values ​​output by the H6 bridge inverter circuit are filtered and subjected to quadrature signal processing to obtain the α-axis voltage components in the two-phase stationary coordinate system. and Axis voltage component V β This enables the extraction of the fundamental positive sequence component and the suppression of harmonics and DC bias. The AC current sample value output from the H6 bridge inverter circuit is filtered and subjected to quadrature signal processing to obtain the α-axis current component in the two-phase stationary coordinate system. and Axial current component I β .

6. The single-phase control method based on dq rotating coordinate transformation according to claim 5, characterized in that, Step 3) specifically includes: processing the α-axis voltage components in the two-phase stationary coordinate system. and Axis voltage component V β Perform a Park coordinate transformation to obtain the d-axis DC voltage component in the synchronous rotating coordinate system. and q-axis DC voltage component ; For the α-axis current component in a two-phase stationary coordinate system and Axial current component I β Perform a Park coordinate transformation to obtain the d-axis DC current component in the synchronous rotating coordinate system. and q-axis DC current component .

7. A single-phase control method based on dq rotating coordinate transformation according to claim 6, characterized in that, Step 4) specifically includes: converting the d-axis voltage component The subtractor sent to the inverter's voltage and current dual closed-loop controller is compared with the given AC voltage amplitude reference value. The difference is calculated to obtain the voltage error signal. This voltage error signal is then input to the PI controller, which outputs the d-axis current reference value. As the active current command of the inner current loop; d-axis current component The subtractor and d-axis current reference value sent to the inverter voltage and current dual closed-loop controller The difference is calculated to obtain the d-axis current error signal, which is then input to the d-axis PI controller to output the d-axis current compensation component. ; q-axis current component The difference between the current and the zero reference value is calculated by the subtractor to obtain the q-axis current error signal, which is then input to the q-axis PI controller and outputs the q-axis current compensation component. .

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