Variable frequency phase shift control DAB type single-stage inverter reactive power control method, system, device and medium

Abstract

The invention discloses a variable frequency phase shift control DAB type single-stage inverter reactive power control method, system and device and a medium, and belongs to the technical field of power electronic converter control, and the method comprises the steps: setting a reactive power instruction as zero; when the reactive power instruction changes, the active power instruction and the reactive power instruction at the current moment are decomposed into a direct-axis current reference value and a quadrature-axis current reference value respectively; comparing the reference value with an actual sampling value, calculating an error compensation amount by using a PI controller, and determining the amplitude and phase of the AC side current according to the compensation amount; according to the amplitude and the phase of the voltage and the current, a DAB frequency conversion phase shift control curve is calculated; and generating a PWM (Pulse Width Modulation) signal according to the frequency conversion phase shift control curve obtained by calculation, wherein the PWM signal is used for driving a DAB inverter to carry out power transmission. According to the invention, on the premise that no extra hardware circuit is introduced, dynamic adjustment and accurate control of the instantaneous reactive power of the AC output side can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronic converter control, in particular to a reactive power control method, system, device and medium for a DAB type single-stage inverter with variable frequency phase-shift control. BACKGROUND

[0002] In recent years, a single-stage inverter topology based on the combination of a dual active bridge (DAB) and a synchronous rectifier (SR) has attracted attention in the field of AC-DC conversion. This topology rectifies the power frequency voltage on the AC side to a half-wave sinusoidal signal through the SR, and realizes DC-AC conversion by combining the high-frequency isolation characteristics of the DAB, thereby simplifying the structure of the traditional multi-stage high-frequency isolated inverter. This structure has the advantages of compact structure, simple energy path, and no need for additional cascaded inverters, and is an important topology form for high-density and high-reliability new energy applications. The control strategy for the DAB type single-stage inverter in the prior art is mostly focused on the optimization control of the DAB side inductor current. By controlling the phase difference between the two bridges of the DAB, the energy transmission efficiency is optimized, the ZVS soft switching characteristics are ensured, the switching loss is reduced, and the overall efficiency of the system is improved.

[0003] However, in the above control structure, the reactive power regulation capability is generally weak or missing. This is because the SR module operates in a power frequency switching mode, and its output voltage waveform is subject to the constraints of switching frequency and power frequency synchronization conditions, while the DAB inductor current is mainly used to transmit active power. In the existing control strategy, the control target of the DAB transmission current is to match the active power demand under the output voltage waveform, rather than considering the dynamic adjustment of the reactive component at the same time. The DAB transmits current through phase-shift control to achieve matching with the output power, and the control target mainly focuses on steady-state power balance and inductor current symmetry, and optimizes the energy transmission path. Therefore, there is still a technical gap in the reactive power control of the DAB type single-stage inverter, especially in the aspect of achieving high-precision reactive control completely relying on the internal control of the DAB without external hardware, and there is still a lack of mature and feasible method. SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, the technical problems solved by the present application are: the problem of inaccurate control of reactive power in the prior art, and how to improve the ability of the DAB type single-stage inverter to regulate the reactive power of the power grid.

[0006] To solve the above technical problems, the present application provides the following technical scheme: a reactive power control method for a DAB type single-stage inverter with variable frequency phase-shift control, comprising,

[0007] The control parameters of the inverter are adjusted by a control strategy, and the reactive power instruction is set to zero.

[0008] When the reactive power instruction changes, the active power and the reactive power instruction at the current time are respectively decomposed into direct-axis current reference values and quadrature-axis current reference values.

[0009] The reference values are compared with the actual sampling values, an error compensation amount is calculated by a PI controller, and the amplitude and phase of the alternating current side current are determined according to the compensation amount.

[0010] According to the amplitudes and phases of the voltage and the current, a DAB variable-frequency phase-shifting control curve is calculated.

[0011] According to the calculated variable-frequency phase-shifting control curve, a PWM signal is generated for driving the DAB inverter to transmit power.

[0012] As a preferred scheme of the DAB single-stage inverter reactive power control method of the variable-frequency phase-shifting control, the setting of the reactive power instruction to zero comprises calculating an initial phase angle according to the direct-axis component of the current alternating voltage and the parameters of the filter capacitor, and adjusting the reactive power instruction based on the initial phase angle to make the reactive power output by the inverter approach zero.

[0013] The preferred technical scheme has the beneficial effects that by setting the reactive power instruction to zero and calculating the initial phase angle based on the direct-axis component of the current alternating voltage and the parameters of the filter capacitor, the reactive power output by the inverter is effectively suppressed to approach zero, which helps to significantly improve the power factor of the system, reduce the reactive current injected by the inverter into the power grid, and improve the power quality of the power grid. In addition, this scheme avoids the complexity of relying on external hardware compensation devices to correct the reactive power in the traditional method, makes the control logic more concise, has a faster response speed, reduces the hardware cost and maintenance workload, and is suitable for high-density and high-efficiency new energy grid-connected scenarios.

[0014] As a preferred scheme of the DAB single-stage inverter reactive power control method of the variable-frequency phase-shifting control, the decomposition into the direct-axis current reference values and the quadrature-axis current reference values comprises operations of the active power instruction and the reactive power instruction with the direct-axis component of the current alternating voltage.

[0015] As a preferred scheme of the DAB single-stage inverter reactive power control method of the variable-frequency phase-shifting control, the comparison of the reference values with the actual sampling values comprises Park transformation of the actual sampling alternating current to obtain direct-axis and quadrature-axis current components, and synthesis of the amplitudes and phases of the alternating current after PI controller compensation of the direct-axis and quadrature-axis current errors.

[0016] As a preferred scheme of the DAB type single-stage inverter reactive power control method of the variable frequency phase shift control, the calculation of the DAB variable frequency phase shift control curve comprises the instantaneous values of the amplitude and phase of the AC side current, the DC voltage and the AC voltage, the phase shift angle value range constraint and the switching frequency value range constraint, and the non-linear function relationship between the phase shift angle and the switching frequency is calculated to obtain the phase shift control curve meeting the power balance and soft switching conditions.

[0017] As a preferred scheme of the DAB type single-stage inverter reactive power control method of the variable frequency phase shift control, the generation of the PWM signal comprises the phase shift angle and the switching frequency output by the digital controller, the generation of the frequency-adjustable sawtooth wave signal and the sine reference wave signal, and the comparison of the two to obtain the driving signal of the bridge arm switching device, wherein the sawtooth wave signal is used to determine the switching frequency, and the sine reference wave signal is used to set the phase shift angle.

[0018] As a preferred scheme of the DAB type single-stage inverter reactive power control method of the variable frequency phase shift control, the generation of the PWM signal further comprises the insertion of the dead time between the on time and the off time of each bridge arm driving signal, and the dead time is inserted into the PWM signal output by the digital controller according to the preset parameters, and is used to avoid the simultaneous conduction of the upper and lower tubes on the same bridge arm.

[0019] The beneficial effects of the preferred technical scheme are that by reasonably setting the dead time in the process of generating the PWM signal, the simultaneous conduction of the upper and lower switching devices on the bridge arm in the switching process is prevented, the problems of bridge arm short circuit and device burning caused by the simultaneous conduction are avoided, and the safety and reliability of the inverter operation are improved. The scheme not only prolongs the service life of the switching device, reduces the operation and maintenance cost caused by the fault shutdown, but also can keep the system stable under the condition of high frequency and high load, adapt to the complex power grid environment and the demand of long-time continuous operation, and guarantee the continuous power supply capacity and grid quality of the system.

[0020] The application provides a DAB type single-stage inverter reactive power control system of variable frequency phase shift control.

[0021] To solve the above technical problems, the application provides the following technical scheme: a DAB type single-stage inverter reactive power control system of variable frequency phase shift control, comprising: an instruction receiving module for receiving and processing active and reactive power instructions;

[0022] A sampling module for sampling the actual values of the current AC side voltage and current;

[0023] A controller module for realizing the decomposition and calculation of the power instructions into a variable frequency phase shift control curve;

[0024] The PWM signal conversion module generates a PWM signal based on a variable frequency phase shift control curve.

[0025] The driving module converts the output PWM signal into a driving signal for controlling the DAB switching device.

[0026] The application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of the DAB single-stage inverter reactive power control method under variable frequency phase shift control when executing the computer program.

[0027] The application provides a computer readable storage medium, which stores a computer program, wherein the computer program implements the steps of the DAB single-stage inverter reactive power control method under variable frequency phase shift control when executed by a processor.

[0028] The application has the advantages that the dynamic adjustment and accurate control of the instantaneous reactive power on the AC output side can be realized without introducing additional hardware circuits, the active and reactive power instructions are decomposed and calculated into current amplitude and phase, the variable frequency phase shift curve is calculated in combination with the actual sampling of voltage and current, the limitation that only the active power can be controlled in the traditional DAB+SR structure is broken, the control strategy has the advantages of fast response speed, high control precision, simple structure and easy engineering implementation, and is not only helpful to improve the power factor and power quality of the system, but also enhances the ability of the converter to support the grid voltage and adjust the reactive power, and has good grid-friendly nature and wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The application provides a DAB single-stage inverter main circuit topology for a DAB single-stage inverter reactive power control method under variable frequency phase shift control.

[0031] Figure 2 The application provides a DAB single-stage inverter main circuit topology for a DAB single-stage inverter reactive power control method under variable frequency phase shift control.

[0032] Figure 3A variable frequency phase shift control flow chart of a DAB type single-stage inverter reactive power control method is provided for an embodiment of the present application.

[0033] Figure 4 A PWM generation flow chart of the DAB type single-stage inverter reactive power control method of variable frequency phase shift control is provided for an embodiment of the present application.

[0034] Figure 5 A reactive power control system block diagram of the DAB type single-stage inverter reactive power control method of variable frequency phase shift control is provided for an embodiment of the present application.

[0035] Figure 6 A reactive power control effect comparison chart of the DAB type single-stage inverter reactive power control method of variable frequency phase shift control is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0037] Embodiment 1, refer to Figure 1 For an embodiment of the present application, the embodiment provides a DAB type single-stage inverter reactive power control method of variable frequency phase shift control, comprising:

[0038] Step 1, adjust the control parameters of the inverter through the control strategy, and set the reactive power command to zero;

[0039] In step 1, in a preferred embodiment of the present application, in the embodiment, the reactive power command is set to zero in the control system, and the direct-axis component and the quadrature-axis component of the alternating current side voltage are calculated based on the real-time sampled voltage and current signals of the alternating current side; then the initial phase angle is calculated through open-loop using these components, and the reactive power command is updated in real time. The controller continuously adjusts the control parameters of the inverter according to the real-time measured reactive power deviation, and adjusts the output reactive power to close to zero.

[0040] The beneficial effects of the preferred technical solution are that the technical solution realizes the rapid convergence of the inverter reactive power, improves the dynamic response capability and power factor when connected to the grid, avoids the power factor decline and power quality degradation caused by control lag, and improves the overall stability and safety of the system.

[0041] In an optional embodiment of the present application, the real-time adjustment of the reactive power instruction adopts a strategy combining prediction and correction. Specifically, the controller predicts the trend of the reactive power in the next period according to the grid voltage and current data collected in the previous period, adjusts the control parameters in advance to compensate for the expected deviation, and performs secondary correction in combination with the real-time sampling values in the current period. This method can improve the response speed in the case of rapid load change and reduce the overshoot and oscillation of the reactive power.

[0042] In another optional embodiment of the present application, the reactive power instruction is limited within the range of ±Qmax by road or software logic. Specifically, when the calculated reactive power instruction exceeds the preset upper limit or lower limit, the instruction is automatically clamped to the maximum allowable value or the minimum allowable value. In this way, the inverter is prevented from outputting excessive reactive power in the case of grid abnormality or control abnormality, thereby protecting the inverter and grid equipment.

[0043] Step 2, when the reactive power instruction changes, the active power and the reactive power instruction at the current time are respectively decomposed into the direct-axis current reference value and the quadrature-axis current reference value;

[0044] Step 3, comparing the reference values with the actual sampling values, the PI controller is used to calculate the error compensation, and the amplitude and phase of the alternating current side current are determined according to the compensation;

[0045] Step 4, according to the amplitudes and phases of the voltage and current, the DAB variable frequency phase shift control curve is calculated;

[0046] In step 4, in a preferred embodiment of the present application, in this embodiment, the calculation of the DAB variable frequency phase shift control curve adopts a piecewise constraint solving strategy. Specifically, first, according to the amplitudes of the alternating current side voltage and current obtained by sampling and the phase difference, in combination with the preset upper and lower limits of the switching frequency, the initial value of the bridge-to-bridge phase shift angle is calculated; then, according to the initial value, it is checked whether the power balance and soft switching conditions are met, if not, the secondary calculation stage is entered, and the optimal solution is searched in the constraint interval through incremental iteration, and finally the control curve meeting the conditions is output.

[0047] The beneficial effects of the preferred technical solution are that the technical solution can improve the control accuracy while ensuring the soft switching and power balance of the inverter, avoid the phase shift angle or switching frequency from exceeding the controllable range, and improve the reliability and stability of the inverter.

[0048] In an optional embodiment of the present application, a look-up table method is introduced for optimization in the calculation of the variable-frequency phase-shifting control curve. Specifically, the relationship between the optimal phase-shifting angle and the switching frequency under the combination of the voltage and current amplitude and phase is calculated offline in advance and stored as a two-dimensional or three-dimensional look-up table. During operation, the optimal solution is quickly obtained by indexing the look-up table in real time according to the sampled voltage and current. This method is particularly suitable for occasions where the hardware computing capacity is limited or the control response time is strictly required.

[0049] In another optional embodiment of the present application, the controller linearizes multiple constraint conditions such as power balance and soft switching when calculating the phase-shifting control curve, and uses a fast linear programming algorithm to solve the combined solution of the phase-shifting angle and the switching frequency. This method is fast in calculation and simple in algorithm implementation, and is suitable for deployment in high-frequency or large-scale grid-connected applications.

[0050] Step 5: Generate PWM signals according to the calculated variable-frequency phase-shifting control curve for driving the DAB inverter to perform power transmission.

[0051] Reference Figure 1 The DAB single-stage inverter main circuit topology provided by the present application is shown in FIG. 1. The DAB single-stage inverter mainly consists of a DAB and an SR. The DAB converter is composed of two full-bridge H1 and H2, a high-frequency transformer HFT and its leakage inductance Lk, and is mainly responsible for power balance and energy delivery. The SR structure is composed of a full-bridge H3, which is mainly responsible for providing a path for the flow of the positive and negative half cycles of the alternating current and voltage. The full-bridges H1, H2 and H3 are each composed of four fully controlled switching devices, which are used to realize the transformation of voltage or current. Further, the inverter main circuit also includes necessary filtering elements, including a DC side LC filter and an AC side LC filter. The capacitor Cac in the AC side LC filter is connected in parallel between the DAB and the SR, and its value is much smaller than that of the DC side filter capacitor Cdc.

[0052] It should be noted that the method of the present embodiment is aimed at the problem that the existing DAB single-stage inverter is difficult to achieve dynamic regulation of reactive power without increasing hardware. By introducing a reactive power instruction setting and real-time adjustment mechanism into the original control process, precise control of output reactive power is achieved. Traditional inverter control usually only considers the balance of active power and cannot take into account the reactive component, resulting in a low power factor after the inverter is connected to the grid and affecting the power quality of the grid. By adjusting the control parameters of the inverter, the present embodiment sets the reactive power instruction to zero and continuously corrects the output state, so that the reactive power tends to zero. When the reactive instruction changes, a new AC current reference value, amplitude and phase are quickly calculated, and the phase-shifting control curve and the PWM signal are updated accordingly to meet the high requirements of grid operation for reactive power regulation.

[0053] The method of the embodiment sets a reactive power instruction, decomposes active and reactive reference values in real time, uses a PI controller to compensate for error to calculate the amplitude and phase of the alternating current side current, and further calculates a phase shift control curve and a PWM signal, thereby realizing fast adjustment and accurate control of the reactive power output of the inverter. Overall, the method of the embodiment forms a complete control chain from reactive power setting, error correction to control signal output, not only improves the power factor of the inverter, improves the output waveform quality, but also enhances the grid stability and dynamic response capability of the inverter, and meets the strict demand of new energy power generation, energy storage and other application scenarios for reactive power regulation.

[0054] In further implementations, the method can also be adaptively adjusted for different working conditions. For example, when the grid voltage fluctuates greatly, the controller can collect the changes of the alternating current side voltage and current in real time, and update the calculation to obtain new reference values, amplitudes and phases, to realize fast compensation of reactive power; when the load changes suddenly, the PI controller parameters are adjusted to optimize the dynamic response time and steady-state error. In addition, in the PWM signal generation stage, an adjustable dead time management algorithm can be introduced to effectively avoid bridge arm shoot-through failure and improve system safety. The embodiment can ensure that the inverter has good reactive power regulation capability and high grid adaptability under various operating conditions, providing higher stability and flexibility for the system.

[0055] Embodiment 2, which is an embodiment of the present application, provides a variable frequency phase shift control DAB type single-stage inverter reactive power control method based on the previous embodiment, comprising:

[0056] Step 201: Determine the instruction active power P ref and reactive power Q ref that the inverter needs to output, and decompose into d-axis current reference value i d.ref and q-axis current reference value i q.ref based on formula (1):

[0057]

[0058] wherein, in formula (1), u d is the direct-axis component (active-axis component) of the alternating voltage u ac decomposed by Park transformation.

[0059] Step 202: Power factor correction. Before adjusting the reactive power, it is necessary to ensure that the output of the inverter is a unit power factor transmission to improve the speed and accuracy of the inverter response to the instruction power. The initial phase angle θ0 generated by the open-loop power factor correction can be calculated by formula (2):

[0060]

[0061] Where f is the power frequency.

[0062] Step 203: Collect the current i in the inverter main circuit ac The actual value is converted into a Park value and compared with the reference value to generate an error value. The error value is compensated by the PI controller and is calculated together with the reference value to generate the corresponding AC side current amplitude I js With phase θ js , the above process can be described by formula (3):

[0063]

[0064] Among them, i d and i q They are the direct-axis and quadrature-axis currents after park transformation of the actual current, where the active axis is the d-axis and the reactive axis is the q-axis. PI(*) simply means obtaining the output after PI control corresponding to the input "*".

[0065] Step 204: Reference Figure 3 The flow chart shown in the figure is based on the input DC voltage U dc , AC voltage u ac and its phase information θ, the amplitude of the AC side current I js With phase θ js , according to formula (4), the preliminary calculation of the variable frequency phase shift control curve is realized:

[0066]

[0067] Where D is the bridge phase shift angle of DAB, f s is the switching frequency of all switches in DAB, F s.max is the maximum switching frequency, F s.min is the minimum value of the switching frequency, and n is the transformer ratio.

[0068] Step 205: Reference Figure 3 The flowchart shown in the figure requires further constraints on the preliminarily calculated frequency-variable phase-shift modulation curve. The constraints are shown in (5) and (6):

[0069]

[0070] D=-D,u ac I js sin(θ-θ js )<0 (6)

[0071] Wherein, formula (5) is based on the fact that DAB transmission power is equal to AC side consumption power, and substituting D = 0.25, we can solve f s, to address the situation where the phase shift angle enters the fixed stage but the switching frequency has not yet been constrained. Formula (6) adjusts the positive and negative phase shift angle D to solve the power balance problem of the DAB converter during the stage when the instantaneous transmission power is negative. If formulas (5) and (6) cannot be satisfied, it means that the transmission power exceeds the inverter limit.

[0072] Step 206: Reference Figure 4 The flow chart shown can convert the frequency conversion phase shift control curve into the switching signal of 8 switching devices corresponding to DAB. First, generate an amplitude of 0 to 2π and a frequency of f s The sawtooth wave signal is calculated by sin operation to obtain a frequency of f s The sine wave signal; after the phase shift angle D is converted into radian units, the difference operation is performed with the sawtooth wave signal to obtain a sawtooth wave signal with a phase lag from the initial phase, and the frequency f is obtained after the sin operation. s , a sinusoidal wave signal with a phase 2πD lag; finally, the sign of the sinusoidal signal is taken to obtain a variable frequency phase-shifted PWM pulse signal.

[0073] Step 207: Control the DAB switches according to the PWM pulse signal. ac The diagonal switching devices of SR are controlled in the same way by the sign of , which can realize the reactive power control of DAB+SR structure.

[0074] Example 3, reference Figure 6 , which is an embodiment of the present invention, provides a DAB type single-stage inverter reactive power control method with variable frequency phase shift control. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0075] Reference Figure 6 This is a comparison diagram of the reactive power control effect provided by the present invention. When the DC voltage Udc = 320V, the AC voltage effective value Uac = 220V, the DAB auxiliary inductor Lk = 200μH, the HFT ratio is 1, the AC filter capacitor Cac = 30μF, the controlled active power reference value is Pref = 3kW, and the reactive power reference value Qref = ±1kVar. Figure 6 The invention describes a reactive power control method and system for a DAB type single-stage inverter with variable frequency phase shift control, which can effectively adjust the reactive power output by the inverter.

[0076] Example 4, with reference to Figure 6 , is an embodiment of the present invention, which provides a DAB type single-stage inverter reactive power control system with variable frequency phase shift control, including: an instruction receiving module for receiving and processing active and reactive power instructions;

[0077] Sampling module, used to sample the actual values ​​of the current AC side voltage and current;

[0078] a controller module for implementing the decomposition of the power instruction into a variable frequency phase shift control curve;

[0079] a PWM signal conversion module for generating a PWM signal based on the variable frequency phase shift control curve;

[0080] a driving module for converting the output PWM signal into a driving signal for controlling the DAB switching device.

[0081] Specifically, the instruction receiving module sets the current active power Pref and the reactive power Qref and sends them to the controller module.

[0082] The sampling module collects the DC side voltage Udc, the AC side current iac, and the AC side voltage uac at the current time and sends them to the controller module.

[0083] The controller module controls the calculation of the power factor correction, the calculation of the AC side current amplitude and phase, and the calculation of the variable frequency phase shift control curve in order based on the input instruction and sampling value, and outputs the variable frequency phase shift control signal to the next module.

[0084] The PWM signal conversion module generates a PWM signal based on the variable frequency phase shift control curve and sets a switching dead zone to avoid bridge arm shoot-through.

[0085] The driving module converts the output PWM signal into a driving signal for controlling the DAB switching device, and controls the eight fully controlled switching devices of the DAB to be turned on according to the variable frequency phase shift control curve.

[0086] The embodiment also provides an electronic device suitable for the variable frequency phase shift controlled DAB type single-stage inverter reactive power control method, which comprises a memory and a processor.

[0087] The embodiment also provides a storage medium having a computer program stored thereon, which is executed by a processor to implement the variable frequency phase shift controlled DAB type single-stage inverter reactive power control method.

[0088] The storage medium proposed in the embodiment and the variable frequency phase shift controlled DAB type single-stage inverter reactive power control method proposed in the above embodiment belong to the same inventive concept, and the technical details not described in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0089] From the above description of the embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software and necessary universal hardware, and of course can also be implemented by hardware, but in many cases the former is a better implementation. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a floppy disk, a ROM, a RAM, a FLASH, a hard disk, or an optical disc, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of various embodiments of the present application.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all of them should be covered in the scope of the claims of the present application.

Claims

1. A reactive power control method for a DAB type single-stage inverter with variable frequency phase shift control, characterized in that: include, Adjust the control parameters of the inverter through the control strategy and set the reactive power command to zero; When the reactive power command changes, the active power and reactive power commands at the current moment are decomposed into a direct-axis current reference value and a quadrature-axis current reference value respectively; Compare the reference value with the actual sampled value, calculate the error compensation amount using the PI controller, and determine the amplitude and phase of the AC side current based on the compensation amount; Calculate the DAB frequency conversion phase shift control curve according to the amplitude and phase of voltage and current; A PWM signal is generated according to the calculated variable frequency phase shift control curve to drive the DAB inverter for power transmission.

2. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 1, characterized in that: Setting the reactive power command to zero includes calculating an initial phase angle based on the direct-axis component of the current AC side voltage and parameters of the filter capacitor, and adjusting the reactive power command based on the initial phase angle so that the inverter output reactive power approaches zero.

3. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 2, characterized in that: The decomposition into a direct-axis current reference value and a quadrature-axis current reference value includes respectively operating the active power instruction and the reactive power instruction with the direct-axis component of the AC side voltage.

4. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 3, characterized in that: The comparison of the reference value with the actual sampled value includes performing Park transformation on the actual sampled AC current to obtain direct-axis and quadrature-axis current components, and compensating the direct-axis and quadrature-axis current errors through PI controllers to synthesize the amplitude and phase of the AC current.

5. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 4, characterized in that: The calculation of the DAB variable frequency phase shift control curve includes calculating the nonlinear functional relationship between the inter-bridge phase shift angle and the switching frequency based on the amplitude and phase of the AC side current, the instantaneous values ​​of the DC voltage and the AC voltage, combined with the phase shift angle value range constraints and the switching frequency value range constraints, to obtain a phase shift control curve that meets power balance and soft switching conditions.

6. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 5, characterized in that: The generating of the PWM signal includes using the phase shift angle and switching frequency output by the digital controller to generate a frequency-adjustable sawtooth wave signal and a sinusoidal reference wave signal, and comparing the two to obtain a driving signal for the bridge arm switching device, wherein the sawtooth wave signal is used to determine the switching frequency, and the sinusoidal reference wave signal is used to set the phase shift angle.

7. The reactive power control method of a DAB type single-stage inverter with frequency conversion and phase shift control according to claim 6, characterized in that: Generating the PWM signal also includes inserting a fixed time interval of dead time between the on time and off time of each bridge arm drive signal. The dead time is inserted into the output PWM signal by the digital controller according to preset parameters to prevent the upper and lower tubes of the same bridge arm from being turned on at the same time.

8. A DAB type single-stage inverter reactive power control system with variable frequency phase shift control, applying a DAB type single-stage inverter reactive power control method with variable frequency phase shift control as claimed in any one of claims 1 to 7, characterized in that: include: Command receiving module, used for receiving and processing active and reactive power commands; Sampling module, used to sample the actual values ​​of the current AC side voltage and current; A controller module is used to decompose and calculate the power command into a variable frequency phase shift control curve; PWM signal conversion module generates PWM signal based on variable frequency phase shift control curve; The driving module converts the output PWM signal into a driving signal for controlling the DAB switching device.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a reactive power control method of a DAB type single-stage inverter with variable frequency phase shift control according to any one of claims 1 to 7 are implemented.

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 a reactive power control method of a DAB type single-stage inverter with variable frequency phase shift control according to any one of claims 1 to 7 are implemented.

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