Dynamic parameter modulation method of three-phase energy storage converter and related device thereof

Abstract

The invention discloses a three-phase energy storage converter dynamic parameter modulation method and a related device thereof, and the method comprises the steps: configuring a modulation strategy of a grid side 3-1MC matrix converter as a current space vector modulation strategy, configuring a modulation strategy of a DC side H bridge as a phase shift modulation strategy, introducing a modulation duty ratio coefficient # imgabs0 # as a modulation parameter, and carrying out the phase shift modulation of the DC side H bridge; the modulation parameters are reduced to modulate a duty ratio coefficient # imgabs 1 # and an input reference current phase # imgabs 2 #, and the technical problems that in an existing modulation method of the AC-DC matrix converter, the modulation parameters are too many, all the parameters are difficult to coordinate through closed-loop control, no parameter can be used for closed-loop control, and meanwhile coordination control over the primary side and the secondary side is difficult to achieve are solved. On the basis, the waveform of a switching signal of the grid-side 3-1MC matrix converter is improved, so that during voltage commutation and current commutation of the grid-side 3-1MC matrix converter, power switch tubes connected in parallel with body diodes with opposite current directions in the grid-side 3-1MC matrix converter are kept on, and the soft switching characteristic of the power switch tubes is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a dynamic parameter modulation method of a three-phase energy storage converter and a related device thereof. Background Art

[0002] Traditional hard switching technology will generate large voltage and current stress at the moment of switching on and off, resulting in high loss and heat generation, and may interfere with surrounding circuit components and systems. Soft switching technology is an important method in modern power electronics technology, which aims to reduce the loss and electromagnetic interference generated during the switching process and improve conversion efficiency. Soft switching technology controls the change process of voltage or current, allowing the switching device to switch on and off under conditions of low voltage and current or even close to zero, thereby reducing loss and stress.

[0003] The research on the soft and hard switching characteristics of isolated AC-DC matrix converters mainly focuses on L-type matrix converters. The inductor current of the L-type matrix converter has eight segments, and the current control is complex. The method of using a composite modulation strategy to realize the soft switching of the matrix converter converts the current into the corresponding charge transferred in each cycle and uses it as the control target through a pulse width calculation method based on the charge transfer relationship. The method of using a variable control frequency soft switching modulation strategy to realize the soft switching of the matrix converter is based on the segmented synchronous control strategy embedded with zero vectors. On the principle of constant power in a single control frequency cycle, the cycle length is changed and the voltage vector arrangement within a control cycle is adjusted to optimize the pulse width to realize soft switching. Although the above schemes can realize soft switching, they cannot eliminate the reflux power generated by the inductor. At the same time, the modulation parameters are used to realize soft switching, resulting in no parameters that can be used for closed-loop control, that is, it is impossible to feedback compensate for it. In existing research, the LCL resonant network is introduced into the matrix converter, and the resonant current is a sinusoidal current at one end. Compared with the eight-segment inductor current of the L-type matrix converter, its control method is easier. However, the prior art does not realize the soft switching characteristics of the power switch tube of the LCL resonant three-phase AC-DC matrix converter, and there are too many modulation parameters in the modulation method, including the input reference current phase , modulation factor m, transformer primary and secondary phase shift angle and the H-bridge output voltage duty cycle Too many modulation parameters will make it difficult to coordinate the various parameters in closed-loop control, and it will also be difficult to achieve coordinated control of the primary and secondary sides. Summary of the invention

[0004] The present invention provides a three-phase energy storage converter dynamic parameter modulation method and related devices, which are used to realize the soft switching characteristics of the power switch tube of the LCL resonant three-phase AC-DC matrix converter, and solve the technical problems that there are too many modulation parameters in the modulation method of the existing AC-DC matrix converter, it is difficult to coordinate various parameters in the closed-loop control, and there are no parameters that can be used for closed-loop control, and it is also difficult to realize the coordinated control of the primary and secondary sides.

[0005] In view of this, a first aspect of the present invention provides a three-phase energy storage converter dynamic parameter modulation method, which is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, comprising:

[0006] The modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology is configured as a current space vector modulation strategy, and the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology is configured as a phase shift modulation strategy;

[0007] In the current space vector modulation strategy, the input reference current phase vector As a modulation parameter, the modulation duty cycle coefficient is introduced into the phase shift modulation strategy. As a modulation parameter, the modulation duty factor Defined as:

[0008]

[0009] Wherein, m is the modulation factor used in the current space vector modulation strategy, is the DC side H-bridge output positive voltage duty cycle;

[0010] The switching signal waveform of the grid-side 3-1MC matrix converter is improved so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes with opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

[0011] Optionally, in the LCL resonant three-phase AC-DC matrix converter topology, the input voltage expression and the output voltage expression of the LCL resonant network are:

[0012]

[0013]

[0014] in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side.

[0015] Optionally, the space vector action time duty cycle expression of the current space vector modulation strategy is:

[0016]

[0017] in, is the duty cycle of the positive line voltage output by the grid-side 3-1MC matrix converter, is the input reference current phase.

[0018] Optionally, the DC side output current expression of the grid-side 3-1MC matrix converter is:

[0019]

[0020] in, is the DC side output current of the grid-side 3-1MC matrix converter, is the input voltage of the grid-side 3-1MC matrix converter, is the resonant inductance value of the LCL resonant network, is the resonant angular frequency of the LCL resonant network, is the power factor angle.

[0021] Optionally, in the LCL resonant three-phase AC-DC matrix converter topology, the reflux power of the LCL resonant network is:

[0022]

[0023] in, is the return power of the LCL resonant network.

[0024] A second aspect of the present invention provides a three-phase energy storage converter dynamic parameter modulation device, the three-phase energy storage converter dynamic parameter modulation device is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, comprising:

[0025] A modulation strategy configuration module, configured to configure the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure to a current space vector modulation strategy, and to configure the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology structure to a phase shift modulation strategy;

[0026] The modulation parameter configuration module is used to input the reference current phase vector in the current space vector modulation strategy. As a modulation parameter, the modulation duty cycle coefficient is introduced into the phase shift modulation strategy. As a modulation parameter, the modulation duty factor Defined as:

[0027]

[0028] Wherein, m is the modulation factor used in the current space vector modulation strategy, is the DC side H-bridge output positive voltage duty cycle;

[0029] The soft switch implementation module is used to improve the switching signal waveform of the grid-side 3-1MC matrix converter, so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes with opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

[0030] Optionally, in the LCL resonant three-phase AC-DC matrix converter topology, the input voltage expression and the output voltage expression of the LCL resonant network are:

[0031]

[0032]

[0033] in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side.

[0034] Optionally, the space vector action time duty cycle expression of the current space vector modulation strategy is:

[0035]

[0036] in, is the duty cycle of the positive line voltage output by the grid-side 3-1MC matrix converter, is the input reference current phase.

[0037] Optionally, the DC side output current expression of the grid-side 3-1MC matrix converter is:

[0038]

[0039] in, is the DC side output current of the grid-side 3-1MC matrix converter, is the input voltage of the grid-side 3-1MC matrix converter, is the resonant inductance value of the LCL resonant network, is the resonant angular frequency of the LCL resonant network, is the power factor angle.

[0040] Optionally, in the LCL resonant three-phase AC-DC matrix converter topology, the reflux power of the LCL resonant network is:

[0041]

[0042] in, is the return power of the LCL resonant network.

[0043] A third aspect of the present invention provides a three-phase energy storage converter dynamic parameter modulation device, the device comprising a processor and a memory:

[0044] The memory is used to store program code and transmit the program code to the processor;

[0045] The processor is used to execute the dynamic parameter modulation method of the three-phase energy storage converter described in any one of the first aspects according to the instructions in the program code.

[0046] A fourth aspect of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the dynamic parameter modulation method of the three-phase energy storage converter described in any one of the first aspects.

[0047] It can be seen from the above technical solutions that the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention has the following advantages:

[0048] The dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention configures the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure as a current space vector modulation strategy, and the modulation strategy of the DC-side H bridge is configured as a phase-shift modulation strategy, and a modulation duty cycle coefficient is introduced into the phase-shift modulation strategy. As the modulation parameter, the original input reference current phase , modulation factor m, transformer primary and secondary phase shift angle and the H-bridge output voltage duty cycle The four modulation parameters are reduced to modulate the duty cycle factor and the input reference current phase At the same time, the switching signal waveform of the grid-side 3-1MC matrix converter is improved so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes of the body diodes connected in parallel with opposite current directions in the grid-side 3-1MC matrix converter remain turned on to achieve soft switching. While realizing the soft switching characteristics of the power switch tubes of the LCL resonant three-phase AC-DC matrix converter, it also solves the technical problems of too many modulation parameters in the modulation method of the existing AC-DC matrix converter, it is difficult to coordinate various parameters in the closed-loop control, and there are no parameters that can be used for closed-loop control, and it is also difficult to achieve coordinated control of the primary and secondary sides.

[0049] At the same time, the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention achieves the technical effect of improving the efficiency of the three-phase energy storage converter while maintaining the three-phase energy storage converter operating at close to unity power factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 A schematic diagram of a flow chart of a dynamic parameter modulation method of a three-phase energy storage converter provided in the present invention;

[0052] Figure 2 A schematic diagram of the topological structure of the LCL resonant three-phase AC-DC matrix converter provided in the present invention;

[0053] Figure 3The present invention provides Figure 2 The equivalent circuit diagram of the LCL resonant network in;

[0054] Figure 4 A voltage-current phase relationship diagram of the LCL resonant network provided in the present invention;

[0055] Figure 5 A current vector sector division diagram provided in the present invention;

[0056] Figure 6 A schematic diagram of the phase voltage of the first sector after synthesis provided in the present invention;

[0057] Figure 7 A schematic diagram of the switching signal waveforms of the first sector of the MC side and the H-bridge side provided by the present invention;

[0058] Figure 8 A schematic diagram of the voltage and current at the port of the LCL resonant network within a switching cycle provided by the present invention;

[0059] Fig. 9 The soft switching theory waveform diagram provided in the present invention;

[0060] Fig.10 The first sector of the 3-1MC provided in the present invention switches from zero level to Schematic diagram of the process;

[0061] Fig.11 This is an improved waveform diagram of twelve power switch tubes on the 3-1MC side provided in the present invention;

[0062] Fig.12 The present invention provides only control and Realize soft switching to limit output voltage and current waveforms;

[0063] Fig.13 The present invention provides only control and Realize soft switching to limit the input of phase a voltage and current waveform;

[0064] Fig.14 The present invention provides only control and Realize soft switching to limit the harmonic distortion rate of phase a input current;

[0065] Fig.15 The open-loop input voltage and current waveform diagram provided in the present invention;

[0066] Fig.16 It is the open-loop input a-phase current harmonic distortion rate diagram provided in the present invention;

[0067] Fig.17 The voltage and current waveform diagram of the open-loop LCL resonant network provided in the present invention;

[0068] Fig.18 It is a soft switching waveform diagram of the open-loop switch tube provided in the present invention;

[0069] Fig.19 The open-loop output voltage and current waveform diagram provided in the present invention;

[0070] Fig. 20 is the modulation parameter m provided in the present invention, , Waveform diagram of parameter changes during open-loop operation;

[0071] Fig.21 It is an open-loop PF (Power Factor) value diagram provided in the present invention;

[0072] Fig. 22 It is the open-loop transmission efficiency diagram provided in the present invention;

[0073] Fig.23 The closed-loop output voltage and current waveform diagram provided in the present invention;

[0074] Fig.24 The input side voltage and current waveform diagram provided in the present invention;

[0075] Fig.25 It is the input current harmonic distortion rate diagram provided in the present invention;

[0076] Fig.26 The voltage and current waveforms on both sides of the LCL resonant network in the closed-loop test provided in the present invention;

[0077] Fig. 27 It is a soft switching waveform diagram of the closed-loop control switch tube provided in the present invention;

[0078] Fig.28 is the modulation parameter m provided in the present invention, , Waveform diagram of parameter changes during closed-loop control operation;

[0079] Fig.29 A closed-loop PF (Power Factor) value diagram provided in the present invention;

[0080] Fig.30 A closed-loop transmission power diagram provided in the present invention;

[0081] Fig.31 A schematic structural diagram of a dynamic parameter modulation device for a three-phase energy storage converter provided in the present invention;

[0082] Fig.32 The present invention provides a schematic structural diagram of a three-phase energy storage converter dynamic parameter modulation device. DETAILED DESCRIPTION

[0083] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0084] For easier understanding, see Figure 1 The present invention provides an embodiment of a three-phase energy storage converter dynamic parameter modulation method, which is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, including:

[0085] Step 101: configure the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure to a current space vector modulation strategy, and configure the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology structure to a phase shift modulation strategy.

[0086] Step 102: In the current space vector modulation strategy, the input reference current phase vector As a modulation parameter, the modulation duty cycle coefficient is introduced in the phase shift modulation strategy as a modulation parameter.

[0087] Step 103: Improve the switching signal waveform of the grid-side 3-1MC matrix converter so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes having opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

[0088] It should be noted that the dynamic parameter modulation method of the three-phase energy storage converter provided in the present invention is implemented on the LCL resonant three-phase AC-DC matrix converter topology structure. The LCL resonant three-phase AC-DC matrix converter topology structure is as follows: Figure 2 As shown, with the three-phase power end as the input and the DC side as the output port: after the three-phase power is connected, it is filtered and enters the AC-DC matrix converter for modulation. The modulated current is transmitted to the DC side through a high-frequency transformer after filtering. The DC side rectifies the high-frequency AC through an H-bridge and then outputs the DC side power supply. Figure 2The equivalent circuit of the LCL resonant network is as follows: Figure 3 As shown, Figure 3 In the example, the resonant inductance of the two resonant networks is the same. Using the phasor analysis method, the input voltage and current relationship expression of the two ports of the LCL resonant network can be obtained as follows:

[0089]

[0090] in, is the input voltage phasor of the LCL resonant network, is the output voltage phasor of the LCL resonant network, j is the sign of the imaginary part, is the resonant capacitor, is the grid angular frequency, is the resonant frequency, , is the input current phasor of the LCL resonant network, is the output current phasor of the LCL resonant network.

[0091] Define the resonant angular frequency of the resonant network for:

[0092]

[0093] Defining the characteristic impedance of a resonant network for:

[0094]

[0095] When the operating frequency of the LCL resonant three-phase AC-DC matrix converter is equal to the resonant frequency of the LCL resonant network, that is, the input voltage phasor of the LCL resonant network and the output voltage phasor of the LCL resonant network When the frequency is equal to the resonant frequency, the phasor expressions of the voltage and current components of each frequency can be obtained as follows:

[0096]

[0097] Where x represents the order of the harmonic component.

[0098] Since the LCL resonant network has the characteristics of high impedance, the higher harmonic components are ignored and only the fundamental component is considered, that is, x=1, then the above formula can be simplified to:

[0099]

[0100] It can be seen that for the fundamental component, the output current phasor of the LCL resonant network is Input voltage phasor with LCL resonant network Linear relationship with phase lag , the input current phasor of the LCL resonant network Output voltage phasor with LCL resonant network Linear relationship and phase leading ,like Figure 4 shown.

[0101] In the present invention, the modulation strategy of the grid-side 3-1MC matrix converter (i.e., three-phase-single-phase matrix converter) in the LCL resonant three-phase AC-DC matrix converter topology is configured as a current space vector modulation strategy. The three-phase symmetrical voltage expression is defined as:

[0102]

[0103] in, is the a-phase AC voltage, is the b-phase AC voltage, is the c-phase AC voltage, t is the time, is the three-phase AC voltage angular frequency, is the amplitude of the three-phase AC voltage.

[0104] The modulated current expression is defined as:

[0105]

[0106] in, is the power factor angle, is the a-phase alternating current, is the b-phase AC current, is the c-phase AC current, is the amplitude of the three-phase alternating current.

[0107] In order to ensure the normal operation of the AC-DC matrix converter, it is necessary to ensure that the three-phase power supply input end is not short-circuited and the output port is not disconnected. Figure 2 From the circuit topology, it can be seen that the power switch tubes of the upper and lower bridge arms of the AC-DC matrix converter need to be turned on at the same time. Therefore, 3-1MC has 9 valid switch states. 1 represents switch on, and 0 represents switch off. Among them, , , , , , are 6 valid vectors, , , There are three zero vectors. The switch turn-on sequence is shown in Table 1.

[0108] Table 1

[0109]

[0110] In Table 1, Sap includes Figure 2 Switching tube in and , Sbp includes Figure 2 Switching tube in and , Scp includes Figure 2 Switching tube in and , San includes Figure 2 Switching tube in and , Sbn includes Figure 2 Switching tube in and , Scn includes Figure 2 Switching tube in and .

[0111] The entire current vector can be divided into six sectors by the classification of the switching sequence table, and the defined current can be vector synthesized by different current vectors, such as Figure 5 shown.

[0112] The primary side of the resonant AC-DC converter adopts the current space vector modulation strategy. The principle is to calculate the mathematical formula of the synthetic current vector and then open the power switch tubes on the grid side and the DC side at different duty cycle time periods to achieve the synthesis of the current in the circuit. The current of each phase is derived:

[0113]

[0114] in, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the DC side H-bridge output positive voltage duty cycle, n is the high-frequency transformer turns ratio, is the output DC voltage rating.

[0115] It can be seen from the above formula that the current of each phase is affected by and Influence. While keeping other factors unchanged, and The synthetic current can be controlled. The duty ratios obtained by this modulation method are:

[0116]

[0117] in, is the input current reference phase, m is the modulation factor used in the current space vector modulation strategy, is the positive line voltage duty cycle output by the grid-side 3-1MC matrix converter, and N is the current vector sector number of the current space vector modulation strategy.

[0118] Due to the stacking relationship of the modulation method, the above scheme is applicable to all six sectors, and only the input needs to be adjusted to the corresponding phase voltage. The synthesized phase voltage of the first sector is as follows: Figure 6 In shown.

[0119] Depend on Figure 6 Combined with mathematical derivation, the expression of the key time point of the grid-side 3-1MC output voltage can be obtained as follows:

[0120]

[0121] in, Respectively represent the grid side 3-1MC output voltage The time point of each voltage change, is the first zero voltage duty cycle in the grid-side 3-1MC output voltage, is the switching cycle.

[0122] In the present invention, the modulation strategy of the DC side H bridge in the LCL resonant three-phase AC-DC matrix converter topology is configured as a phase-shift modulation strategy. After the three-phase industrial frequency sinusoidal AC passes through the grid-side 3-1MC, it becomes a high-frequency bipolar rectangular signal and is connected to the H bridge through a transformer. To achieve energy transmission, the H bridge must also output a high-frequency bipolar rectangular signal with the same frequency as the switching frequency. The H bridge modulation adopts a phase-shift modulation method and a dual phase-shift control strategy. By controlling the primary and secondary phase shift angles and the duty cycle generated by the phase shift in the H-bridge To control the size and direction of the transmission power. Figure 5 , after mathematical derivation, it can be concluded that each key time point is and Function:

[0123]

[0124] in, Respectively represent the H-bridge input voltage The time point at which each voltage changes.

[0125] The corresponding switching signal waveforms on the grid side 3-1MC side and H-bridge side are as follows: Figure 7As shown in the figure. Since the three-phase input voltage phase difference is 120° and the bridge arms of 3-1MC are symmetrical, the switching signal waveforms of the other five sectors of 3-1MC can be derived accordingly. According to the switching signal waveform diagram, the Figure 6 The waveform shown in the figure can also be obtained and The piecewise function expression of and Fourier decomposition is performed separately. Due to the high impedance characteristics of the LCL resonant network, only and The fundamental component can be obtained and The expression is:

[0126]

[0127]

[0128] in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side.

[0129] According to the phase relationship between voltage and current at each frequency in the LCL resonant network, it can be concluded that:

[0130]

[0131]

[0132]

[0133]

[0134] For half cycle current Integrate and get the average current expression of phase current in one cycle:

[0135]

[0136] right , , Perform park transformation and get:

[0137]

[0138] in, is the input reference current. Input current reference phase The calculation method is: input three-phase reference current The 3 / 2 transformation of the stationary coordinate system converts the transformed Axis vector and The axis vectors are synthesized into complex numbers, and then the complex phase angle is calculated to obtain the input reference current phase.

[0139] The expression of the action time duty cycle of the space vector can be solved as:

[0140]

[0141] Will and Substitution We can get:

[0142]

[0143] Output current in one cycle Integrate and get the average current in one cycle:

[0144]

[0145] Depend on Combining the above equations, we can get the DC side output current expression of the AC-DC matrix converter:

[0146]

[0147] in, is the DC side output current of the grid-side 3-1MC matrix converter, It is the input voltage of the grid-side 3-1MC matrix converter.

[0148] The system active power expression is have to:

[0149]

[0150] Where P is the active power of the LCL resonant three-phase AC-DC matrix converter topology system, and the power factor is , is the output reference voltage phase, The calculation method is: input three-phase reference voltage The 3 / 2 transformation of the stationary coordinate system converts the transformed Axis vector and The axis vectors are synthesized into complex numbers, and then the complex phase angle is calculated to obtain the output reference voltage phase.

[0151] To achieve the soft switching characteristics of the power switch tube, its essence is to first let the body diode conduct before the power switch tube is turned on or off, and clamp the voltage difference between the drain and the source to near 0V, so as to achieve the soft switching characteristics of the power switch tube. Figure 8 As shown in Figure 2. Mathematically, the requirement for achieving soft switching depends on the sign of the current at the moment when each power switch is actuated. Assume that in the first sector, In the positive half cycle, if the power switch tube When in action, the current , then the power switch tube Soft switching can be achieved if the power switch tube Current during operation , then the power switch tube Soft switching can be achieved. In the negative half cycle, if the power switch tube Current during operation , then the power switch tube Soft switching can be achieved if the power switch tube Action , then the power switch tube Soft switching can be achieved. The other sectors have similar conditions due to symmetry. Similarly, for the four power switches in the H-bridge side , , and ,exist In the positive half cycle, if the power switch tube Action , then the power switch tube Soft switching can be achieved if the power switch tube Current during operation , then the power switch tube Soft switching can be achieved. In the negative half cycle, if the power switch tube Current during operation , then the power switch tube Soft switching can be achieved if the power switch tube Current during operation , then the power switch tube Soft switching can be achieved.

[0152] In order to achieve soft switching of the power switch tube in the 3-1MC side full bridge, the current Shift right and , since the first and second half periods are symmetrical, we only need to satisfy Then, because the current Leading voltage The phase is , so we only need to increase The current Similarly, in order to achieve soft switching of the power switch tube on the H-bridge side, the current should be Shift left and , since the first and second half periods are symmetrical, we only need to satisfy Then, because the current Hysteresis voltage The phase is , so we only need to increase The current Relative voltage Shift to the left. But if The increase leads to and , and If there is an event of opposite polarity between The larger the value, the greater the return power, which reduces the transformer's power transmission efficiency. It should be the minimum value to achieve soft switching conditions, that is, when and When the power switch tube of the H bridge of the LCL resonant matrix converter 3-1MC can realize soft switching, the magnitude of the reflux power is affected by The theoretical waveform for achieving soft switching is as follows: Fig. 9 As shown. The return power of the LCL resonant network for:

[0153]

[0154] The return power and , Combined, we get:

[0155]

[0156] because , and when When the return power is infinitely close to 0, it is only necessary to control When it is greater than 0, soft switching can be achieved while reflux power can be controlled to the maximum extent. When the LCL resonant three-phase AC-DC matrix converter performs soft switching modulation, the reflux power loss is taken into account and the reflux power is calculated, which can minimize the reflux power on the basis of achieving soft switching.

[0157] Since the 3-1MC side uses a four-quadrant switch, its back-to-back connected body diodes cannot provide a freewheeling channel for it, and soft switching cannot be achieved directly. Therefore, a freewheeling channel must be provided for this purpose, so the 3-1MC switch signal waveform must be improved. In the process of voltage commutation and current commutation, as long as the power switch tube with body diodes in opposite current directions is kept turned on in parallel, soft switching can be achieved. Fig.10 It shows the 3-1MC switching from zero level to Since the first sector ,so , Can be normally open, and No, otherwise the body diode current will flow backwards, so the switch operation state before commutation is as follows Fig.10 The switch operation status during the commutation process is shown in (a). Fig.10 As shown in (b), in order to ensure the same current direction during commutation, the C phase current will first pass through The body diode of the Fig.10 As shown in (c), The conduction realizes zero voltage turn-on. Due to the symmetry, other sectors also have similar turn-on processes, which will not be described here.

[0158] Therefore, under the premise of keeping the synthetic voltage vector unchanged, the waveforms of the twelve power switches on the 3-1MC side are adjusted to Fig.11 As shown in the figure, since the three-phase input voltage phase difference is 120° and the bridge arms of 3-1MC are symmetrical, the switching signal waveforms of the other five sectors of 3-1MC can be derived accordingly. After adjustment, the synthetic voltage vector remains unchanged, so the power transmission characteristics remain unchanged, and it also provides the possibility of realizing zero voltage turn-on of the power switch tube.

[0159] consider , find the limit case, Substitution And setting its value to 0, we can conclude that the conditions for the grid-side 3-1MC power switch to achieve soft switching are as follows:

[0160]

[0161] Will Substitution And setting its value to 0, we can get the following conditions for the DC side H-bridge power switch to achieve soft switching:

[0162]

[0163] Lian Li and , it can be concluded that the conditions for the grid-side 3-1MC and the DC-side H-bridge power switch tube to achieve soft switching at the same time are:

[0164]

[0165]

[0166] If only based on and control and Although the soft switching characteristics of the power switch tube can be realized, and All of these affect the system power output, and the changes and It will cause a large steady-state error, resulting in excessive input three-phase current harmonics and output power and output voltage ripple. Fig.12 , Fig.13 and Fig.14 As shown. Fig.12 It can be seen that the output voltage and current ripples are too large and do not meet the design requirements. Fig.13 It can be seen that the input current distortion rate is serious. Fig.14 It can be seen that the input current harmonic distortion rate is 11.15%, which exceeds the grid requirement of 5% and does not meet the design requirements. Therefore, this is unacceptable.

[0167] In the formula In the If we can If the control parameters are limited to a fixed value, the influence of the two variables on the output can be eliminated. The basic idea is that although the output is determined by multiple control variables, as long as the overall gain remains unchanged, the output will not change regardless of how these control variables change. Therefore, the present invention introduces a new control parameter , is the modulation duty cycle coefficient, .

[0168] Assuming operation at unity power factor, we have:

[0169]

[0170] At this time, under the condition of system design parameter setting, the output active power is only Control, so The introduction reduces the feedback control variables, enhances the ability of coordinated modulation between the original modulation parameters, and realizes the soft switching characteristics of the power switch tube in the closed-loop feedback compensation process.

[0171] Will As a new modulation parameter, a given value is set, and As a constraint equation, and Combined, we can get the following about The constraint equations are:

[0172]

[0173] Through the above analysis, it can be seen that the modulation factor m, the primary and secondary phase shift angle of the transformer and the H-bridge output voltage duty cycle Duty cycle coefficient and the input reference current phase It can be calculated that, therefore, in the grid-side 3-1MC flow space vector modulation strategy, it is only necessary to change the input reference current phase As a modulation parameter, in the phase-shift modulation strategy of the DC-side H-bridge, it is only necessary to change the modulation duty cycle coefficient As a modulation parameter, the original four modulation parameters can be reduced to two modulation parameters.

[0174] The dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention configures the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure as a current space vector modulation strategy, and the modulation strategy of the DC-side H bridge is configured as a phase-shift modulation strategy, and a modulation duty cycle coefficient is introduced into the phase-shift modulation strategy. As the modulation parameter, the original input reference current phase , modulation factor m, transformer primary and secondary phase shift angle and the H-bridge output voltage duty cycle The four modulation parameters are reduced to modulate the duty cycle factor and the input reference current phase At the same time, the switching signal waveform of the grid-side 3-1MC matrix converter is improved so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes of the body diodes connected in parallel with opposite current directions in the grid-side 3-1MC matrix converter remain turned on to achieve soft switching. While realizing the soft switching characteristics of the power switch tubes of the LCL resonant three-phase AC-DC matrix converter, it also solves the technical problems of too many modulation parameters in the modulation method of the existing AC-DC matrix converter, it is difficult to coordinate various parameters in the closed-loop control, and there are no parameters that can be used for closed-loop control, and it is also difficult to achieve coordinated control of the primary and secondary sides.

[0175] At the same time, the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention achieves the technical effect of improving the efficiency of the three-phase energy storage converter while maintaining the three-phase energy storage converter operating at close to unity power factor.

[0176] In order to verify the technical effect achieved by the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention, an open-loop simulation verification is performed on the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention:

[0177] An open-loop simulation environment is built in Simulink, and the parameters of the input side voltage and current waveforms are shown in Table 2.

[0178] Table 2

[0179]

[0180] The open-loop input voltage and current waveform is as follows: Fig.15 The harmonic distortion rate of the open-loop input a-phase current is as follows: Fig.16 As shown. Fig.15 and Fig.16 It can be seen that the harmonic distortion rate of the grid-side input current is 3.02%, which meets the design requirements.

[0181] The voltage and current waveforms of the primary and secondary sides of LCL are as follows: Fig.17 As shown, from Fig.17 It can be seen that at the key time point for realizing soft switching in the above analysis, the corresponding current value meets the above conditions, which minimizes the return power and realizes the soft switching characteristics of the power switch tube.

[0182] Fig.18 This is the soft switching waveform of the open-loop switch tube. It can be seen that the power switch tube It drops to 0 before the driving signal comes, achieving zero voltage turn-on.

[0183] Fig.19The output voltage and current waveforms are open-loop. The output voltage and current ripples are very small, and the output can be stable. The static error is small and meets the design requirements. However, due to the open-loop operation, the output voltage does not reach the given value of 400V, and there is a certain deviation, which is a normal effect of open-loop operation.

[0184] Fig. 20 is the modulation parameter m, , Parameter change waveform during open loop operation. Fig. 20 It can be obtained that the modulation parameters show periodic changes with a small amplitude and smooth changes, and have the same shape, which is beneficial to the smooth control of the system and to reducing the system output voltage and current ripple and input current harmonic distortion rate, and will not cause system mutations, high-frequency harmonic interference and other problems.

[0185] Fig.21 This is the open loop PF (Power Factor) value diagram, from Fig.21 It can be seen that the open-loop operation power factor is as high as 0.998, which is higher than the open-loop operation power factor of 0.981 in the prior art. There is basically no phase difference between the input voltage and current, the system loss is very low, and the system margin is extremely high.

[0186] Fig. 22 is the open-loop transmission efficiency diagram. Fig. 22 It can be seen that the average open-loop transmission efficiency is 99.1%, and the lowest value is also higher than the highest efficiency of 96.9% of the existing technology.

[0187] The present invention also conducts closed-loop simulation verification on the dynamic parameter modulation method of the three-phase energy storage converter provided by the present invention:

[0188] The output voltage is controlled in a closed loop using a virtual voltage direct control method. The control model is:

[0189]

[0190] in, is the output voltage given value, Output voltage and Output virtual voltage value after PI controller.

[0191] The closed-loop control effect is as follows: Fig.23 As shown, Fig.23 It shows that the output voltage reaches the given value of 400V and the ripple is small, and the performance is greatly improved compared with the open loop. The formed dynamic parameter coordinated closed-loop control shows good control performance.

[0192] Fig.24 and Fig.25They are the input side voltage and current waveforms and the input current harmonic distortion rate diagram. Fig.24 and Fig.25 It can be seen that the current harmonic distortion rate is very small, at 2.94%, which is lower than the requirement of 5% and meets the design requirements. The introduction of closed-loop control also reduces the current harmonic distortion rate.

[0193] Fig.26 The voltage and current waveforms on both sides of the LCL resonant network in the closed-loop test. The figure shows that the voltage and current relationship of the LCL resonant network in the closed-loop feedback control process still meets the soft switching characteristics of the grid-side power switch tube and the DC-side power switch tube, that is, in the closed-loop control, the power switch tubes on both sides still have soft switching characteristics. It is consistent with the theoretical analysis and meets the zero voltage conduction conditions of the 3-1MC and H-bridge power switch tubes.

[0194] Fig. 27 This is the closed-loop control switch tube soft switching waveform diagram, Fig. 27 It can be seen that the voltage Vds on both sides of the power switch tube drops to 0 before the driving signal comes, achieving zero voltage turn-on.

[0195] Fig.28 is the modulation parameter m, , The parameter change waveform diagram during closed-loop control operation. Fig.28 It can be seen that the modulation parameters show periodic changes with a small amplitude and have the same shape, which is beneficial to the smooth control of the system and to reducing the system output voltage and current ripple and input current harmonic distortion rate.

[0196] Fig.29 This is a closed-loop PF (Power Factor) value diagram. It can be seen that the closed-loop power factor is close to 0.999, which is higher than 0.981 of the prior art. There is basically no phase difference between the input voltage and current, the system loss is low, and the system margin is high.

[0197] Fig.30 is the closed-loop transmission power diagram, from Fig.30 It can be seen that the average closed-loop transmission efficiency is 99.3%, which improves the transmission power efficiency.

[0198] The present invention also provides an embodiment of a three-phase energy storage converter dynamic parameter modulation device, which is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, including:

[0199] A modulation strategy configuration module, used to configure the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure to a current space vector modulation strategy, and to configure the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology structure to a phase shift modulation strategy;

[0200] Modulation parameter configuration module, used to input reference current phase vector in current space vector modulation strategy As a modulation parameter, the modulation duty cycle coefficient is introduced in the phase shift modulation strategy As a modulation parameter, the modulation duty factor Defined as:

[0201]

[0202] Where m is the modulation factor used in the current space vector modulation strategy, is the DC side H-bridge output positive voltage duty cycle;

[0203] The soft switch implementation module is used to improve the switching signal waveform of the grid-side 3-1MC matrix converter, so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes with opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

[0204] In one embodiment, in the LCL resonant three-phase AC-DC matrix converter topology, the input voltage expression and the output voltage expression of the LCL resonant network are:

[0205]

[0206]

[0207] in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side;

[0208] The expression of the space vector action time duty cycle of the current space vector modulation strategy is:

[0209]

[0210] in, is the duty cycle of the positive line voltage output by the grid-side 3-1MC matrix converter, is the input reference current phase.

[0211] The DC side output current expression of the grid-side 3-1MC matrix converter is:

[0212]

[0213] in, is the DC side output current of the grid-side 3-1MC matrix converter, is the input voltage of the grid-side 3-1MC matrix converter, is the resonant inductance value of the LCL resonant network, is the resonant angular frequency of the LCL resonant network, is the power factor angle.

[0214] In one embodiment, in the LCL resonant three-phase AC-DC matrix converter topology, the reflux power of the LCL resonant network is:

[0215]

[0216] in, is the return power of the LCL resonant network.

[0217] The present invention also provides an embodiment of a three-phase energy storage converter dynamic parameter modulation device, the device comprising a processor and a memory:

[0218] The memory is used to store program codes and transmit the program codes to the processor;

[0219] The processor is used to execute the dynamic parameter modulation method of the three-phase energy storage converter provided in the present invention according to the instructions in the program code.

[0220] The present invention also provides an embodiment of a computer-readable storage medium, where the computer-readable storage medium is used to store program codes, and the program codes are used to execute the dynamic parameter modulation method of the three-phase energy storage converter provided in the present invention.

[0221] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-phase energy storage converter dynamic parameter modulation method, characterized in that: The three-phase energy storage converter dynamic parameter modulation method is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, comprising: The modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology is configured as a current space vector modulation strategy, and the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology is configured as a phase shift modulation strategy; In the current space vector modulation strategy, the input reference current phase vector As a modulation parameter, the modulation duty cycle coefficient is introduced into the phase shift modulation strategy. As a modulation parameter, the modulation duty factor Defined as: Wherein, m is the modulation factor used in the current space vector modulation strategy, is the DC side H-bridge output positive voltage duty cycle; The switching signal waveform of the grid-side 3-1MC matrix converter is improved so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes with opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

2. The dynamic parameter modulation method of the three-phase energy storage converter according to claim 1 is characterized in that: In the LCL resonant three-phase AC-DC matrix converter topology, the input voltage expression and output voltage expression of the LCL resonant network are: in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side.

3. The dynamic parameter modulation method of the three-phase energy storage converter according to claim 2 is characterized in that: The space vector action time duty cycle expression of the current space vector modulation strategy is: in, is the duty cycle of the positive line voltage output by the grid-side 3-1MC matrix converter, is the input reference current phase.

4. The dynamic parameter modulation method of the three-phase energy storage converter according to claim 3 is characterized in that: The DC side output current expression of the grid side 3-1MC matrix converter is: in, is the DC side output current of the grid-side 3-1MC matrix converter, is the input voltage of the grid-side 3-1MC matrix converter, is the resonant inductance value of the LCL resonant network, is the resonant angular frequency of the LCL resonant network, is the power factor angle.

5. The dynamic parameter modulation method of the three-phase energy storage converter according to claim 4 is characterized in that: In the LCL resonant three-phase AC-DC matrix converter topology, the reflux power of the LCL resonant network is: in, is the return power of the LCL resonant network.

6. A three-phase energy storage converter dynamic parameter modulation device, characterized in that: The three-phase energy storage converter dynamic parameter modulation device is applied to an LCL resonant three-phase AC-DC matrix converter topology structure, comprising: A modulation strategy configuration module, configured to configure the modulation strategy of the grid-side 3-1MC matrix converter in the LCL resonant three-phase AC-DC matrix converter topology structure to a current space vector modulation strategy, and to configure the modulation strategy of the DC-side H-bridge in the LCL resonant three-phase AC-DC matrix converter topology structure to a phase shift modulation strategy; The modulation parameter configuration module is used to input the reference current phase vector in the current space vector modulation strategy. As a modulation parameter, the modulation duty cycle coefficient is introduced into the phase shift modulation strategy. As a modulation parameter, the modulation duty factor Defined as: Wherein, m is the modulation factor used in the current space vector modulation strategy, is the DC side H-bridge output positive voltage duty cycle; The soft switch implementation module is used to improve the switching signal waveform of the grid-side 3-1MC matrix converter, so that when the voltage of the grid-side 3-1MC matrix converter is commutated and the current is commutated, the power switch tubes in parallel with the body diodes with opposite current directions in the grid-side 3-1MC matrix converter remain turned on.

7. The dynamic parameter modulation device of the three-phase energy storage converter according to claim 6, characterized in that: In the LCL resonant three-phase AC-DC matrix converter topology, the input voltage expression and output voltage expression of the LCL resonant network are: in, is the input voltage of the LCL resonant network, is the output voltage of the LCL resonant network, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase b in the grid-side 3-1MC matrix converter, is the output voltage corresponding to the current vector from the power switch tube to the colleague in the upper bridge arm of phase a and the lower bridge arm of phase c in the grid-side 3-1MC matrix converter, is the duty cycle of the maximum positive line voltage output by the grid-side 3-1MC matrix converter, is the duty cycle of the second largest positive line voltage output by the grid-side 3-1MC matrix converter, is the phase shift angle of the input and output voltage of the LCL resonant network, n is the turns ratio of the high-frequency transformer, is the output voltage of the H-bridge on the DC side; The space vector action time duty cycle expression of the current space vector modulation strategy is: in, is the duty cycle of the positive line voltage output by the grid-side 3-1MC matrix converter, is the input reference current phase; The DC side output current expression of the grid side 3-1MC matrix converter is: in, is the DC side output current of the grid-side 3-1MC matrix converter, is the input voltage of the grid-side 3-1MC matrix converter, is the resonant inductance value of the LCL resonant network, is the resonant angular frequency of the LCL resonant network, is the power factor angle.

8. The dynamic parameter modulation device of the three-phase energy storage converter according to claim 7, characterized in that: In the LCL resonant three-phase AC-DC matrix converter topology, the reflux power of the LCL resonant network is: in, is the return power of the LCL resonant network.

9. A three-phase energy storage converter dynamic parameter modulation device, characterized in that: The device comprises a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the dynamic parameter modulation method of the three-phase energy storage converter according to any one of claims 1-4 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the dynamic parameter modulation method of the three-phase energy storage converter according to any one of claims 1-4.

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