Direct-current side double passive harmonic suppression method and system for series multi-pulse rectifier

Abstract

The invention relates to a direct-current side double passive harmonic suppression method and system for a series-connection type multi-pulse rectifier, and the method comprises the following steps: constructing the series-connection type multi-pulse rectifier, and adding a passive harmonic injection circuit at a direct-current side; determining the working mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit in the corresponding mode by using the output current of the three-phase full-bridge rectifier circuit; determining the switching function of each phase and the voltage of two groups of three-phase full-bridge rectification circuits relative to a reference point in each mode according to the conduction condition of each diode in the three-phase full-bridge rectification circuits, and determining the voltage value of each step of the primary side input voltage; according to the step voltage value of the primary side input voltage, the voltage effective value and the fundamental wave amplitude are determined, the optimal transformation ratio of the transformer is determined by calculating the total harmonic distortion rate, and the passive harmonic injection circuit achieves harmonic suppression according to the obtained optimal transformation ratio.

Description

Technical Field

[0001] This invention relates to the field of rectifier technology, specifically to a method and system for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Rectifier circuits using diodes or thyristors as basic power devices have advantages such as simple structure, low cost, and high reliability. They are the most important power electronic devices for connecting power system networks and performing AC / DC conversion, and are widely used in electrochemical treatment, uninterruptible power supplies, high-voltage DC transmission, and AC / DC drives. However, rectifiers exhibit strong nonlinearity and time-varying characteristics, generating a large number of harmonics in the public power grid. Harmonics increase reactive power losses in the power network, reduce the efficiency and power factor of the rectifier circuit, distort voltage on the grid side, and affect nearby equipment.

[0004] Harmonics can increase losses in transmission lines, reducing the efficiency of power generation, transmission, and utilization; cause malfunctions in relay protection and automatic control equipment; lead to parallel or series resonance in the public power grid, increasing the overall losses of the power network; cause additional heat loss and mechanical vibration in motors, local overheating and insulation aging in transformers; and generate electromagnetic interference to communication equipment. Summary of the Invention

[0005] To address the technical problems mentioned above, this invention provides a method and system for suppressing dual passive harmonics on the DC side of a series-connected multi-pulse rectifier. A set of dual passive harmonic injection circuits is added to the DC side of a basic series-connected 12-pulse rectifier. Injected harmonics are generated by utilizing the current difference between two sets of three-phase rectifier bridges connected in series, thereby increasing the order of the isolation transformer's input voltage and making the AC input current closer to a sine wave, thus improving the rectifier's harmonic suppression capability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier, comprising the following steps: Construct a series-type multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series-type multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor. By using the output current of the three-phase full-bridge rectifier circuit, the operating mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode are determined. By determining the conduction status of each diode in the three-phase full-bridge rectifier circuit, the switching function of each phase is determined, as well as the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point under each mode, and the step voltage values ​​of the primary input voltage are determined. Based on the step voltage values ​​of the primary input voltage, the effective voltage value and fundamental amplitude are determined. By calculating the total harmonic distortion rate, the optimal transformer ratio is determined. The passive harmonic injection circuit suppresses harmonics based on the obtained optimal ratio.

[0007] Furthermore, a series-type multi-pulse rectifier is constructed by adding a passive harmonic injection circuit on the DC side. Specifically, the primary winding of the isolation transformer is connected to the three-phase power supply through an inductor, and the two sets of secondary windings are respectively connected to the corresponding three-phase full-bridge rectifier circuits. The three-phase full-bridge rectifier circuits are connected to the DC-side capacitor and the load. The secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC-side capacitor.

[0008] Furthermore, using the output current of the three-phase full-bridge rectifier circuit, the operating mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode are determined, as shown in the following formula: ; ; ; ; in, , These represent the output currents of the two rectifier bridges, Rec1 and Rec2, respectively. u o1 , u o2 These are the DC-side series filter capacitors. C 1. C 2. Voltage on both sides; u o This is the load voltage; u d The diode voltage; take the connection point of the two rectifier bridges Rec1 and Rec2 as F, and the two filter capacitors... C 1. C 2. If the connection point is P, then u FP That is, the voltage between the two; N 2 / N 1 and N 3 / N 4 represents the turns ratio of the transformer windings in the two single passive injection circuits.

[0009] Furthermore, by determining the conduction status of each diode in the three-phase full-bridge rectifier circuit, the switching function of each phase is determined, as shown in the following formula: ; ; in, S a1 , S b1 , S c1 , S a2 , S b2 , S c2 These are the switching functions for each phase of the two sets of three-phase rectifier bridges, with phase A of Rec1 as an example, Sa1(ωt)=sgn(ia1); This represents the phase difference between the voltage source and the voltage injected into the isolation transformer.

[0010] Furthermore, the voltages of the two sets of three-phase full-bridge rectifier circuits relative to the reference point are determined for each mode, as shown in the following formula: ; ; in, u A1P The voltage of rectifier bridge Rec1 relative to reference point P. u x = ( u o + u d )× N 3 / N 4; u A2G This represents the voltage across the rectifier bridge Rec2 relative to the reference point G, where G is the voltage between Rec2 and the filter capacitor. C 2 connection points; u y = u x × N 2 / N 1; u o This is the load voltage. u d For diode voltage, u x and u y These are the parameters used in the calculation process.

[0011] Furthermore, the step voltage values ​​of the primary input voltage are determined as shown in the following formula: ; ; in, u An1 The primary input voltage, u AB , u BC , u CA The original line voltage, u A1B1 , u B1C1 , u C1A1 This is the line voltage of rectifier bridge Rec1. u A2n2 , u B2n2 , u C2n2 This is the phase voltage of rectifier bridge Rec2.

[0012] Furthermore, based on the step voltage values ​​of the primary input voltage, the effective voltage value and fundamental amplitude are determined. By calculating the total harmonic distortion rate, the optimal transformer ratio is determined, as shown in the following formula: ; ; ; in, U An1 This is the effective value of phase A voltage. U m This is the instantaneous voltage value. U s1 Here, represents the fundamental amplitude of the voltage, and THD represents the total harmonic distortion. Let n be the nth term in the Fourier series expansion.

[0013] A second aspect of the present invention provides a dual passive harmonic suppression system on the DC side of a series-type multi-pulse rectifier, comprising: The equivalent model construction module is configured to: construct a series multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor; The operating mode analysis module is configured to: use the output current of the three-phase full-bridge rectifier circuit to determine the operating mode of the passive harmonic injection circuit, and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode; The step voltage determination module is configured to: determine the switching function of each phase and the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point in each mode by the conduction status of each diode in the three-phase full-bridge rectifier circuit, and determine the step voltage values ​​of the primary input voltage. The transformer ratio optimization module is configured to: determine the effective voltage value and fundamental amplitude based on the step voltage values ​​of the primary input voltage, determine the optimal transformer ratio by calculating the total harmonic distortion rate, and the passive harmonic injection circuit achieves harmonic suppression based on the obtained optimal transformer ratio.

[0014] A third aspect of the present invention provides a computer program product including computer-readable instructions that, when executed on an electronic device, cause the electronic device to implement the above-described method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier.

[0015] A fourth aspect of the present invention provides an electronic device including at least one processor and a memory connected to the processor, the memory being used to store a computer program; the processor being used to execute the computer program, enabling the electronic device to implement the above-described method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier.

[0016] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects: By incorporating at least two sets of passive harmonic injection circuits into a basic 12-pulse rectifier, the AC input current is made closer to a sine wave by increasing the order of the isolation transformer input voltage. A topology model is established to analyze the operation of the injection circuits and determine the operating modes. Based on the operating modes and the switching functions of each phase of the rectifier bridge, the output voltage waveform is analyzed. This allows for the optimization design of the transformer in the passive harmonic injection circuit, obtaining the optimal turns ratio and improving the rectifier's harmonic suppression capability. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a topology diagram of a series multi-pulse rectifier based on dual passive harmonic injection method provided by one or more embodiments of the present invention; Figure 2 This is a schematic diagram of the working modes I and VI of the dual passive harmonic injection circuit provided in one or more embodiments of the present invention; Figure 3 This is a schematic diagram of the operating modes II and V of the dual passive harmonic injection circuit provided in one or more embodiments of the present invention; Figure 4This is a schematic diagram of the operating modes III and IV of the dual passive harmonic injection circuit provided in one or more embodiments of the present invention; Figure 5 This is an ideal operating waveform diagram of the injection circuit provided in one or more embodiments of the present invention; Figure 6 This is a schematic diagram of the AC side input voltage 36-step waveform formation process provided by one or more embodiments of the present invention; Figure 7 The THD and turns ratio of the input voltage provided in one or more embodiments of the present invention n 1. n 2. Relationship diagram; Figure 8 This is a schematic diagram of the input voltage waveform of an isolation transformer provided in one or more embodiments of the present invention; Figure 9 This is a schematic diagram of the input current waveform of an isolation transformer provided in one or more embodiments of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] As introduced in the background section, improving the harmonic suppression performance of rectifiers, ensuring normal equipment operation, and reducing harmonic pollution to the power grid are current research hotspots. The following embodiment presents a method and system for dual passive harmonic suppression on the DC side of a series-type multi-pulse rectifier. A set of dual passive harmonic injection circuits is added to the DC side of a basic series-type 12-pulse rectifier. Injected harmonics are generated using the current difference between the two sets of three-phase rectifier bridges connected in series, thereby increasing the order of the isolation transformer's input voltage and making the AC input current closer to a sine wave, thus improving the rectifier's harmonic suppression capability.

[0022] Example 1: A method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier includes the following steps: Construct a series-type multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series-type multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor. By using the output current of the three-phase full-bridge rectifier circuit, the operating mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode are determined. By determining the conduction status of each diode in the three-phase full-bridge rectifier circuit, the switching function of each phase is determined, as well as the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point under each mode, and the step voltage values ​​of the primary input voltage are determined. Based on the step voltage values ​​of the primary input voltage, the effective voltage value and fundamental amplitude are determined. By calculating the total harmonic distortion rate, the optimal transformer ratio is determined. The passive harmonic injection circuit suppresses harmonics based on the obtained optimal ratio.

[0023] like Figure 1 The multi-pulse rectifier topology diagram shown is based on the dual passive harmonic injection method, including a three-phase power supply, an isolation transformer, a first three-phase full-bridge rectifier circuit Rec1, a second three-phase full-bridge rectifier circuit Rec2, passive harmonic injection circuit I, passive harmonic injection circuit II, and a DC-side capacitor. C P and load u o .

[0024] like Figure 1 As shown, u a , u b , u c A three-phase power supply is formed.

[0025] The primary winding of the isolation transformer is connected to the three-phase power supply via an inductor. The two sets of secondary windings are connected to the corresponding three-phase full-bridge rectifier circuits. The isolation transformer consists of three core columns (core 1, core 2, and core 3) with a symmetrical structure. Each core column has three windings: one primary winding and two secondary windings. The turns ratio of the three windings is as follows: windings a, b, and c are the primary windings of isolation transformer 2, connected in a delta configuration; windings a1, b1, and c1 are the secondary windings connected in a delta configuration; and windings a2, b2, and c2 are the secondary windings connected in a star configuration. Windings a, a1, and a2 are located on the same core column, as are windings b, b1, and b2. Windings c, b1, and c2 are located on the same core column. The winding C2 is located on the same magnetic core column, which can provide a loop for the third harmonic. The two secondary windings adopt delta connection and star connection respectively, and output two sets of three-phase voltages with a phase difference of 30°. The isolation transformer has a symmetrical structure, which is conducive to harmonic suppression, and the electrical isolation structure makes the transformer have high safety.

[0026] The two sets of three-phase full-bridge rectifier circuits have the same structure and both use diodes as rectifier devices. The two sets of three-phase full-bridge rectifier circuits are connected in series, which not only solves the problem of current imbalance, but also doubles the output voltage, making them suitable for high-power rectification applications with high output voltage.

[0027] DC side capacitor C P It has two sets connected in series, the first three-phase full-bridge rectifier circuit and the second three-phase full-bridge rectifier circuit, the first DC-side capacitor and the second DC-side capacitor and the load are connected in parallel, and the output voltage becomes twice. Both three-phase full-bridge rectifier circuits use uncontrolled rectifier devices, which has high reliability.

[0028] One set of DC-side capacitors C P The upper end is connected to the positive output terminal of the first three-phase full-bridge rectifier circuit and the positive terminal of the load, and the lower end is connected to another set of DC-side capacitors. C P The upper end of the capacitor is connected to the lower end of the DC-side capacitor, which is connected to the negative terminal of the output of the second three-phase full-bridge rectifier circuit and the negative terminal of the load.

[0029] Two sets of DC-side capacitors C P With equal magnitude and small load voltage ripple, it is equivalent to a constant voltage load. The rectifier output voltage is DC after being filtered by a capacitor.

[0030] In this embodiment, an inductor is connected in series on the AC side of the three-phase power supply. The isolation transformer adopts a Δ / Δ / Y structure with a turns ratio of √3:√3:1. Two sets of three-phase rectifier bridges are connected in series, and two filter capacitors are connected in series on the DC side. At this time, the load voltage and current ripple is small, and the load can be equivalent to a constant voltage load.

[0031] The two sets of passive harmonic injection circuits consist of two sets of single passive harmonic injection circuits. The secondary side of the transformer in injection circuit I is connected in series between the two rectifier bridges, and the primary side is connected between the output of rectifier bridge Rec1 and the midpoint of the filter capacitor.

[0032] In the two sets of passive harmonic injection circuits, the secondary side of the transformer in injection circuit I, i.e. the tapped side, is connected in series between the two sets of rectifier bridges Rec1 and Rec2, and the primary side is connected between the output point F of rectifier bridge Rec1 and the midpoint P of the two filter capacitors; the primary side of the transformer in injection circuit II is connected between points F and P, and the secondary side is connected to both ends of the load.

[0033] The harmonic suppression method for a series multi-pulse rectifier based on dual passive harmonic injection was verified using Simulink simulation, including the following steps: First, a series-type multi-pulse rectifier is built, and a harmonic injection circuit is added to the DC side; Secondly, the operating modes of the dual passive harmonic injection circuit are analyzed to determine the formation process of the multi-pulse voltage. Then, the transformer of the injection circuit is optimized by calculating the total harmonic distortion rate; Finally, the results were verified through simulation experiments.

[0034] By following the steps above, the transformer turns ratio is optimized, thereby reducing the harmonic distortion rate.

[0035] Specifically, follow these steps: Step 1: Analyze the operating modes of the dual passive harmonic injection circuit.

[0036] Step 1.1: Analyze the operation of the injection circuit according to the following formula to determine the operating mode of the injection circuit: ; In the formula, , These represent the output currents of the two rectifier bridges, Rec1 and Rec2, respectively.

[0037] Step 1.2: Analyze the operating modes and determine the corresponding relationships of the rectifier bridge output voltage under different operating modes: ; ; ; In the formula, u o1 , u o2 These are the DC-side series filter capacitors. C 1. C 2. Voltage on both sides; u o This is the load voltage; u d The diode voltage; take the connection point of the two rectifier bridges Rec1 and Rec2 as F, and the two filter capacitors... C 1. C 2. If the connection point is P, then u FP That is, the voltage between the two; N 2 / N 1 and N 3 / N 4 represents the turns ratio of the transformer windings in the two single passive injection circuits.

[0038] Step 2: Analyze the formation process of multi-pulse voltage.

[0039] Step 2.1: Determine the conduction status of each diode in the two sets of rectifier bridges to obtain the switching function of each phase: ; ; In the formula, S a1 , S b1 , S c1 , S a2 , S b2 , S c2 These are the switching functions for each phase of the two sets of three-phase rectifier bridges, with phase A of Rec1 as an example, Sa1(ωt)=sgn(ia1); This represents the phase difference between the voltage source and the voltage injected into the isolation transformer.

[0040] Step 2.2: Taking phase A as an example, determine the voltage of the two sets of rectifier bridges relative to the reference point in each mode: ; ; In the formula, u A1P The voltage of rectifier bridge Rec1 relative to reference point P. u x = ( u o + u d )× N 3 / N 4; u A2G This represents the voltage across the rectifier bridge Rec2 relative to the reference point G, where G is the voltage between Rec2 and the filter capacitor. C 2 connection points; u y = u x × N 2 / N 1; u o This is the load voltage. u d For diode voltage, u x and u y These are the parameters used in the calculation process.

[0041] Step 2.3: Based on the following formula, combined with the modal analysis in Step 1 and Step 2.2, determine the step voltage values ​​of the primary input voltage: ; ; In the formula, u An1 The primary input voltage, u AB , u BC , u CA The original line voltage, u A1B1 , u B1C1 , u C1A1 This is the line voltage of rectifier bridge Rec1. u A2n2 , u B2n2 , u C2n2 This is the phase voltage of rectifier bridge Rec2.

[0042] The obtained step voltage values ​​are shown in Table 1.

[0043] Table 1 u An1 Level values ​​of each step

[0044] Step 3: Optimize the transformer turns ratio in the harmonic injection circuit.

[0045] Step 3.1: Based on the voltage values ​​of the primary input voltage of each phase obtained in Step 2, calculate the effective voltage value and fundamental amplitude using the following formula: ; In the formula, U An1 This is the effective value of phase A voltage. U m This is the instantaneous voltage value.

[0046] The fundamental amplitude is obtained by performing a Fourier transform on the voltage: ; In the formula, The nth term of the Fourier series expansion Step 3.2: Calculate the total harmonic distortion (THD) using the following formula to determine the optimal transformer turns ratio: ; In the formula, U s1 This represents the fundamental amplitude of the voltage.

[0047] Figure 1This is the topology of a series-type multi-pulse rectifier based on the dual passive harmonic injection method. An inductor is connected in series on the AC side, and the isolation transformer adopts a Δ / Δ / Y structure with an assumed turns ratio of √3:√3:1. Two sets of three-phase rectifier bridges are connected in series, and two filter capacitors are connected in series on the DC side. At this point, the load voltage and current ripple are relatively small, and the load can be equivalent to a constant voltage load.

[0048] The dual passive harmonic injection circuit consists of two sets of single passive harmonic injection circuits. In the injection circuit I, the secondary side of the transformer is connected in series between the two rectifier bridges, and the primary side is connected between the output of rectifier bridge Rec1 and the midpoint of the filter capacitor. The average values ​​of the rectifier bridge output currents iRec1 and iRec2 are the same, but their phase difference is π / 6. Therefore, the DC-side passive harmonic injection circuit generates injected harmonics.

[0049] Based on the relationship between currents iRec1 and iRec2, analysis of the injection circuit's operation reveals that it operates in six modes, such as... Figures 2-4 As shown. Figure 5 By obtaining the ideal operating waveform diagram of the injection circuit and combining it with the switching functions of each phase of the rectifier bridge, the step-level values ​​of the input voltage can be obtained, and thus the waveform of the multi-pulse voltage can be obtained. Figure 6 This is a schematic diagram illustrating the formation process of the 36-step waveform of the AC input voltage. The relationship between THD and the transformer turns ratios n1 and n2 is obtained by calculating the total harmonic distortion (THD), as shown below. Figure 7 As shown. Figure 8 and Figure 9 The simulated input voltage and input current waveforms are basically consistent with the theoretical analysis.

[0050] In summary, after adding the injection circuit, the input voltage of the rectifier becomes a 36-step wave, and the input current waveform is closer to a sine wave. By optimizing the transformer of the injection circuit, it can be seen that under the optimal turns ratio, the total harmonic distortion rate of the rectifier is 4.931% (derived from simulation), which effectively improves the harmonic suppression capability of the rectifier.

[0051] Example 2: A series-type multi-pulse rectifier DC-side dual passive harmonic suppression system includes: The equivalent model construction module is configured to: construct a series multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor; The operating mode analysis module is configured to: use the output current of the three-phase full-bridge rectifier circuit to determine the operating mode of the passive harmonic injection circuit, and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode; The step voltage determination module is configured to: determine the switching function of each phase and the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point in each mode by the conduction status of each diode in the three-phase full-bridge rectifier circuit, and determine the step voltage values ​​of the primary input voltage. The transformer ratio optimization module is configured to: determine the effective voltage value and fundamental amplitude based on the step voltage values ​​of the primary input voltage, determine the optimal transformer ratio by calculating the total harmonic distortion rate, and the passive harmonic injection circuit achieves harmonic suppression based on the obtained optimal transformer ratio.

[0052] By incorporating at least two sets of passive harmonic injection circuits into a basic 12-pulse rectifier, the AC input current is made closer to a sine wave by increasing the order of the isolation transformer input voltage. A topology model is established to analyze the operation of the injection circuits and determine the operating modes. Based on the operating modes and the switching functions of each phase of the rectifier bridge, the output voltage waveform is analyzed. This allows for the optimization design of the transformer in the passive harmonic injection circuit, obtaining the optimal turns ratio and improving the rectifier's harmonic suppression capability.

[0053] Example 3: A computer program product includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to implement the aforementioned method for dual passive harmonic suppression on the DC side of a series-type multi-pulse rectifier.

[0054] Example 4: An electronic device includes at least one processor and a memory connected to the processor, the memory being used to store a computer program; the processor is used to execute the computer program, enabling the electronic device to implement the above-described method for dual passive harmonic suppression on the DC side of a series-type multi-pulse rectifier.

[0055] Example 5: A computer storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device is able to implement the above-mentioned method for dual passive harmonic suppression on the DC side of a series multi-pulse rectifier.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier, characterized in that, Includes the following steps: Construct a series-type multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series-type multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor. By using the output current of the three-phase full-bridge rectifier circuit, the operating mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode are determined. By determining the conduction status of each diode in the three-phase full-bridge rectifier circuit, the switching function of each phase is determined, as well as the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point under each mode, and the step voltage values ​​of the primary input voltage are determined. Based on the step voltage values ​​of the primary input voltage, the effective voltage value and fundamental amplitude are determined. By calculating the total harmonic distortion rate, the optimal transformer ratio is determined. The passive harmonic injection circuit suppresses harmonics based on the obtained optimal ratio.

2. The DC-side passive harmonic suppression method for a series-type multi-pulse rectifier as described in claim 1, characterized in that, A series-type multi-pulse rectifier is constructed by adding a passive harmonic injection circuit on the DC side. Specifically, the primary winding of the isolation transformer is connected to the three-phase power supply through an inductor, and the two sets of secondary windings are respectively connected to the corresponding three-phase full-bridge rectifier circuits. The three-phase full-bridge rectifier circuits are connected to the DC-side capacitor and the load. The secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC-side capacitor.

3. The DC-side passive harmonic suppression method for a series-type multi-pulse rectifier as described in claim 1, characterized in that, Using the output current of the three-phase full-bridge rectifier circuit, the operating mode of the passive harmonic injection circuit and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode are determined, as shown in the following formula: ； ； ； ； in, , These represent the output currents of the two rectifier bridges, Rec1 and Rec2, respectively. u o1 , u o2 These are the DC-side series filter capacitors. C 1. C 2. Voltage on both sides; u o This is the load voltage; u d The diode voltage; take the connection point of the two rectifier bridges Rec1 and Rec2 as F, and the two filter capacitors... C 1. C 2. If the connection point is P, then u FP That is, the voltage between the two; N 2 / N 1 and N 3 / N 4 represents the turns ratio of the transformer windings in the two single passive injection circuits.

4. The DC-side passive harmonic suppression method for a series-type multi-pulse rectifier as described in claim 1, characterized in that, The switching function of each phase is determined by the conduction status of each diode in the three-phase full-bridge rectifier circuit, as shown in the following formula: ； ； in, S a1 , S b1 , S c1 , S a2 , S b2 , S c2 These are the switching functions for each phase of the two sets of three-phase rectifier bridges, with phase A of Rec1 as an example, Sa1(ωt)=sgn(ia1); This represents the phase difference between the voltage source and the voltage injected into the isolation transformer.

5. The DC-side passive harmonic suppression method for a series-type multi-pulse rectifier as described in claim 1, characterized in that, The voltages of the two sets of three-phase full-bridge rectifier circuits relative to the reference point under each mode are determined as follows: ； ； in, u A1P The voltage of rectifier bridge Rec1 relative to reference point P. u x = ( u o + u d )× N 3 / N 4; u A2G This represents the voltage across the rectifier bridge Rec2 relative to the reference point G, where G is the voltage between Rec2 and the filter capacitor. C 2 connection points; u y = u x × N 2 / N 1; u o This is the load voltage. u d For diode voltage, u x and u y These are the parameters used in the calculation process.

6. The method for suppressing dual passive harmonics on the DC side of a series-type multi-pulse rectifier as described in claim 1, characterized in that, The step voltage values ​​of the primary input voltage are determined as shown in the following formula: ； ； in, u An1 The primary input voltage, u AB , u BC , u CA The original line voltage, u A1B1 , u B1C1 , u C1A1 This is the line voltage of rectifier bridge Rec1. u A2n2 , u B2n2 , u C2n2 This is the phase voltage of rectifier bridge Rec2.

7. The DC-side passive harmonic suppression method for a series-type multi-pulse rectifier as described in claim 1, characterized in that, Based on the step voltage values ​​of the primary input voltage, the effective voltage value and fundamental amplitude are determined. By calculating the total harmonic distortion rate, the optimal transformer turns ratio is determined, as shown in the following formula: ； ； ； in, U An1 This is the effective value of phase A voltage. U m This is the instantaneous voltage value. U s1 Here, represents the fundamental amplitude of the voltage, and THD represents the total harmonic distortion. Let n be the nth term in the Fourier series expansion.

8. A series-type multi-pulse rectifier DC-side dual passive harmonic suppression system, characterized in that, include: The equivalent model construction module is configured to: construct a series multi-pulse rectifier and add a passive harmonic injection circuit on the DC side; wherein, the series multi-pulse rectifier has at least two sets of three-phase full-bridge rectifier circuits, the secondary side of the transformer of the passive harmonic injection circuit is connected in series between the two sets of three-phase full-bridge rectifier circuits, and the primary side is connected between the output of one set of three-phase full-bridge rectifier circuits and the midpoint of the DC side capacitor; The operating mode analysis module is configured to: use the output current of the three-phase full-bridge rectifier circuit to determine the operating mode of the passive harmonic injection circuit, and the corresponding output voltage of the three-phase full-bridge rectifier circuit under the corresponding mode; The step voltage determination module is configured to: determine the switching function of each phase and the voltage of the two sets of three-phase full-bridge rectifier circuits relative to the reference point in each mode by the conduction status of each diode in the three-phase full-bridge rectifier circuit, and determine the step voltage values ​​of the primary input voltage. The transformer ratio optimization module is configured to: determine the effective voltage value and fundamental amplitude based on the step voltage values ​​of the primary input voltage, determine the optimal transformer ratio by calculating the total harmonic distortion rate, and the passive harmonic injection circuit achieves harmonic suppression based on the obtained optimal transformer ratio.

9. A computer program product, characterized in that, Includes computer-readable instructions that, when executed on an electronic device, cause the electronic device to perform the steps in the DC-side dual passive harmonic suppression method for a series multi-pulse rectifier as claimed in any one of claims 1-7.

10. An electronic device, characterized in that, It includes at least one processor and a memory connected to the processor, the memory being used to store computer programs; the processor is used to execute the computer programs, enabling the electronic device to perform the steps in the DC-side dual passive harmonic suppression method for any one of claims 1-7.

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