54-pulse uncontrolled rectifier for unconventional balancing reactor and rectification method thereof

Abstract

The present invention provides a 54-pulse uncontrolled rectifier of an unconventional balancing reactor and a rectification method thereof, belonging to the field of power electronics technology, including a phase-shifting transformer, a full-bridge rectifier circuit I, a full-bridge rectifier circuit II, a full-bridge rectifier circuit III, an unconventional balancing reactor I, an unconventional balancing reactor II, and an unconventional balancing reactor III; wherein the full-bridge rectifier circuit is connected to a DC load via an unconventional balancing reactor; and the unconventional balancing reactor is composed of a single-phase transformer with a center tap and a clamping diode. The present invention combines a rectifier transformer with a harmonic suppression method of a multi-pulse rectifier technology, and achieves the effect of reducing input current harmonics and output voltage ripple without using active devices, thereby greatly improving the power quality of the rectifier.

Description

Technical Field

[0001] The invention relates to the field of power electronics, and in particular to a 54-pulse uncontrolled rectifier of an unconventional balanced reactor and a rectification method thereof. Background Art

[0002] In today's high-power applications, multi-pulse rectifiers are a common interface between DC power electronic loads and AC power grids, used to improve power factor and reduce harmonic pollution. Multi-pulse rectifiers have the advantages of simple structure and strong robustness. However, the nonlinearity of the rectifier device will make the rectifier a strong nonlinear load of the power grid, generating a large number of current harmonics, which will cause serious pollution to the power grid. In order to improve the harmonic suppression capability of the rectifier, the multi-pulse rectifier uses a phase-shifting transformer to phase-shift multiple connections of multiple three-phase rectifier circuits, and the harmonics generated by each rectifier circuit offset each other to achieve a better harmonic suppression effect.

[0003] The design purpose of the multi-pulse rectifier is to complete the rectification task while increasing the number of rectification pulses. Increasing the phase-shifting transformer can increase the number of pulses of the rectifier, but the manufacturing accuracy of the phase-shifting transformer has a great impact on the rectifier. Excessive increase in the number of phases of the transformer will make its structure complex and increase the difficulty of manufacturing. Using active conversion technology to suppress input current harmonics will introduce a control drive module to increase system complexity and reduce system reliability. Therefore, how to effectively reduce the input current harmonic content and output voltage ripple coefficient of the multi-pulse rectifier without basically increasing the difficulty of phase-shifting transformer design and diode conduction loss needs to be solved urgently. Summary of the invention

[0004] In view of the above-mentioned deficiencies, the present invention solves the problems of input current harmonics, system reliability, and high-efficiency transmission of the existing multi-pulse rectification technology, and provides a 54-pulse uncontrolled rectifier using an unconventional balancing reactor and a rectification method thereof, so as to enhance the harmonic suppression effect and improve the power quality of the multi-pulse rectifier.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0006] 54-pulse uncontrolled rectifier for unconventional balancing reactor, including:

[0007] The phase-shifting transformer is used to shift the phase of the input voltage of the power grid to generate three-phase voltages with a phase difference of 20° and the same amplitude, and the voltage generated by the phase-shifting transformer is respectively sent to the full-bridge rectifier circuit I, the full-bridge rectifier circuit II, and the full-bridge rectifier circuit III for three-phase rectification of each phase angle;

[0008] A full-bridge rectifier circuit, comprising a full-bridge rectifier circuit I, a full-bridge rectifier circuit II and a full-bridge rectifier circuit III, wherein the three DC negative voltages outputted are connected to the negative end of the output end, and the three DC positive voltages outputted are respectively connected to the primary sides of the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III;

[0009] A combined unconventional balancing reactor includes an unconventional balancing reactor I, an unconventional balancing reactor II and an unconventional balancing reactor III. The primary sides of the three reactors are connected to the positive end of the output terminal through a first clamping diode to form a DC side output. Both ends of the secondary windings of the three reactors are connected to the positive end of the output terminal through a second clamping diode to form a DC side auxiliary circuit positive output. The central taps of the secondary windings of the three reactors are connected together to form a DC side auxiliary circuit negative output and a negative end of the output terminal.

[0010] A further improvement of the present invention is that the phase-shifting transformer is an autotransformer; the transformer is composed of three core columns, each of which has three windings, including one primary winding and two secondary windings, and there is a direct electrical connection between the windings. The primary winding is connected in a triangle shape, and the secondary winding is tapped to the primary winding to generate three groups of three-phase voltages of equal size and a phase difference of 20°.

[0011] A further improvement of the present invention is that the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III all use uncontrolled rectifying devices.

[0012] A further improvement of the present invention is that the three unconventional balancing reactors are all equipped with a single-phase transformer with a center tap, comprising a core column, a primary winding and a secondary winding on the core column, the primary winding has two taps symmetrical about the primary center, the primary turns ratio is defined as the ratio of the number of turns between the two taps to the number of turns of the primary winding, and its primary turns ratio is q=0.227; the secondary winding has a center tap, and the secondary turns ratio is defined as the ratio of the number of turns of the primary winding to the number of turns of the secondary winding, and its secondary turns ratio is k=0.0244.

[0013] A further improvement of the present invention is that the uncontrolled rectifying device includes a diode VD1, a diode VD2, a diode VD7 and a diode VD8 of the unconventional balancing reactor I, a diode VD3, a diode VD4, a diode VD9 and a diode VD10 of the unconventional balancing reactor II, and a diode VD5, a diode VD6, a diode VD11 and a diode VD12 of the unconventional balancing reactor III.

[0014] The rectification method of the 54-pulse uncontrolled rectifier based on the above-mentioned unconventional balancing reactor includes a full-bridge rectifier circuit having a 6-pulse rectified output for the three-phase voltage, a phase-shifting transformer generating 3 groups of three-phase voltages of equal size and a phase difference of 20°, and an 18-pulse rectified output is obtained through the coordinated output of the full-bridge rectifier circuit; and then the 18-pulse rectified output is processed by the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III respectively, the number of rectified pulses is increased, and a 54-pulse rectified output is obtained. For the output voltage V of the unconventional balancing reactor I dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 and the output voltage V of the unconventional balancing reactor III dc3 There are three working modes: working mode I, working mode II, and working mode III. For the output voltage V dc2 ≥ Output voltage V of unconventional balancing reactor I dc1 and the output voltage V of the unconventional balancing reactor III dc3 There are three working modes: working mode IV, working mode V, and working mode VI. For the output voltage V of the unconventional balancing reactor III, dc3 ≥ Output voltage V of unconventional balancing reactor I dc1 and the output voltage V of the unconventional balancing reactor II dc2 When , there are three working modes, which are respectively recorded as working mode VII, working mode VIII, and working mode IX.

[0015] The further improvement of the method is that: the working mode I: when the output voltage V of the unconventional balancing reactor I is dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 >>Output voltage V of unconventional balancing reactor II dc2 When the unconventional balancing reactor I: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 | Smaller than the rectifier system output voltage V L , so diodes VD7 and VD8 are not conducting; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3=0, and because the voltage on the diode VD9 and diode VD10 is |V s1 | Smaller than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balancing reactor III: Because q(V dc3 -V dc1 )≥q(V dc1 -V dc2 ), because of the diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work;

[0016] Working mode II: When the output voltage V of the unconventional balancing reactor I dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , and the output voltage V of the unconventional balancing reactor I dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 When the unconventional balancing reactor I: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 |Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because at this time the voltage on the diode VD9 and diode VD10 side -|V s2 |Greater than the rectifier system output voltage V L , so the secondary side diode VD10 is forward biased and turned on; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work;

[0017] Working mode III: When the output voltage V of the unconventional balancing reactor I dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 >>Output voltage V of unconventional balancing reactor III dc3 When the unconventional balancing reactor I: Because the output voltage V dc1≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 |Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage on the diode VD9 and diode VD10 is |V s1 | Smaller than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work;

[0018] The method is further improved in that: in the working mode IV, the unconventional balancing reactor I does not work; in the unconventional balancing reactor II, VD3 is turned on, VD4 is reversely cut off, and both diodes VD9 and VD10 are not turned on; in the unconventional balancing reactor III, VD5 is reversely cut off, so VD6 is turned on, and diodes VD11 and VD12 are not turned on;

[0019] Working mode V: unconventional balancing reactor I does not work; unconventional balancing reactor II: VD3 is turned on, VD4 is reverse cutoff, diode VD9 is turned on, and diode VD10 is reverse cutoff; unconventional balancing reactor III: VD5 is reverse cutoff, so VD6 is turned on, diode VD11 is not turned on, and diode VD12 is turned on;

[0020] Working mode VI: unconventional balancing reactor I does not work; unconventional balancing reactor II: VD3 is turned on, VD4 is reverse cutoff, diode VD9 is turned on, and diode VD10 is reverse cutoff; unconventional balancing reactor III: VD5 is reverse cutoff, so VD6 is turned on, and diodes VD11 and VD12 are not turned on.

[0021] The further improvement of the method is that: the working mode VII: unconventional balancing reactor I: VD1 is reversely cut off, VD2 is turned on, and diodes VD7 and VD8 are not turned on; unconventional balancing reactor II does not work; unconventional balancing reactor III: VD5 is turned on, VD6 is reversely cut off, and diodes VD11 and VD12 are not turned on;

[0022] Working mode VIII: Unconventional balancing reactor I: VD1 is reverse cut-off, VD2 is turned on, diode VD7 is not turned on, and diode VD8 is turned on; Unconventional balancing reactor II does not work; Unconventional balancing reactor III: VD5 is turned on, VD6 is reverse cut-off, diode VD11 is turned on, and diode VD12 is reverse cut-off;

[0023] Working mode IX: Unconventional balancing reactor I: VD1 is reverse cut-off, VD2 is turned on, and both diodes VD7 and VD8 are not turned on; unconventional balancing reactor II does not work; unconventional balancing reactor III: VD5 is turned on, VD6 is reverse cut-off, diode VD11 is turned on, and diode VD12 is reverse cut-off.

[0024] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is: without using active devices, the effect of reducing input current harmonics and output voltage ripple is achieved, thereby greatly improving the power quality of the rectifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 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 drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 A schematic diagram of the structure of a 54-pulse uncontrolled rectifier using an unconventional balancing reactor according to the present invention;

[0027] Figure 2 is a schematic diagram of a current loop of the unconventional balancing reactor combination of the present invention in working mode I;

[0028] Figure 3 is a schematic diagram of a current loop of the unconventional balancing reactor combination of the present invention in working mode II;

[0029] Figure 4 is a schematic diagram of a current loop of the unconventional balancing reactor combination of the present invention in working mode III;

[0030] Figure 5 It is a working waveform diagram of the 54-pulse uncontrolled rectifier using an unconventional balancing reactor according to the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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.

[0032] (1) Rectifier circuit topology: Figure 1 As shown, where i dc1 is the positive output current of the DC side of the full-bridge rectifier circuit I, i dc11 The current of the primary winding of the unconventional balancing reactor I is injected into the positive output terminal of the full-bridge rectifier circuit I, i dc12 The current of the primary winding of the unconventional balancing reactor II is injected into the positive output terminal of the full-bridge rectifier circuit I; i dc2 is the positive output current of the DC side of the full-bridge rectifier circuit II, i dc21 The current of the primary winding of the unconventional balancing reactor II is injected into the positive output of the full-bridge rectifier circuit II, i dc22 The current of the primary winding of the unconventional balancing reactor III is injected into the positive output terminal of the full-bridge rectifier circuit II; i dc3 is the positive output current of the DC side of the full-bridge rectifier circuit III, i dc31 The current of the primary winding of the unconventional balancing reactor I is injected into the positive output of the full-bridge rectifier circuit III, i dc32 The current of the primary winding of the unconventional balancing reactor III is injected into the positive output terminal of the full-bridge rectifier circuit III.

[0033] in,

[0034]

[0035] i d1 、i d2 、i d3 、i d4 、i d5 、i d6 They are the currents on the diodes VD1, VD2, VD3, VD4, VD5 and VD6 on the primary side tap of the unconventional balanced reactor; u L is the output voltage of the rectifier system, u s1 is the voltage on the secondary side diodes VD7 and VD8 of the unconventional balanced reactor I, u s2 is the voltage on the secondary side diodes VD9 and VD10 of the unconventional balanced reactor II, u s3 It is the voltage on the secondary side diodes VD11 and VD12 of the unconventional balancing reactor III.

[0036] The present invention provides a 54-pulse uncontrolled rectifier using an unconventional balancing reactor, the topology of which includes a phase-shifting transformer, a full-bridge rectifier circuit I, a full-bridge rectifier circuit II, and a full-bridge rectifier circuit III; wherein the full-bridge rectifier circuit is connected to a DC load via an unconventional balancing reactor; the unconventional balancing reactor is composed of a single-phase transformer with a center tap and a clamping diode;

[0037] A phase-shifting transformer is used to shift the phase of the input voltage of the power grid to generate three-phase voltages with a phase difference of 20° and the same amplitude, and the voltage generated by the phase-shifting transformer is respectively sent to the full-bridge rectifier circuit I, the full-bridge rectifier circuit II, and the full-bridge rectifier circuit III for three-phase rectification of each phase angle, and form three DC voltage positive output terminals and three DC voltage negative output terminals;

[0038] The three negative output terminals of the DC voltages output by the full-bridge rectifier circuit I, the full-bridge rectifier circuit II, and the full-bridge rectifier circuit III are connected together and connected to the negative terminal of the output terminal;

[0039] The three DC voltage positive output terminals output by the full-bridge rectifier circuit I, the full-bridge rectifier circuit II, and the full-bridge rectifier circuit III are connected to the primary side of the combined unconventional balancing reactor, and the primary side of the combined unconventional balancing reactor forms a DC side output terminal connected to the positive terminal of the output terminal through a clamping diode;

[0040] The two ends of the secondary winding of the combined unconventional balancing reactor are connected to the positive end of the output end through the clamping diode to form the positive output end of the DC side auxiliary circuit;

[0041] The center taps of the secondary windings of the combined unconventional balancing reactor are connected together to form a negative output terminal of a DC side auxiliary circuit connected to the negative end of the output terminal; the negative end of the output terminal and the positive end of the output terminal are used to connect an external load to provide electrical energy.

[0042] (2) Rectifier magnetic device, further, the phase-shifting transformer is an autotransformer; the transformer is composed of three core columns, each core column has three windings, including one primary winding and two secondary windings, there is a direct electrical connection between the windings, the primary winding is a delta connection, the secondary winding is tapped to the primary winding, and generates three groups of three-phase voltages of equal size and a phase difference of 20°.

[0043] Furthermore, the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III all adopt uncontrolled rectifying devices.

[0044] Furthermore, the unconventional balancing reactor is composed of a core column with a primary winding and a secondary winding on the core column. The primary winding has two taps symmetrical about the primary center. The primary turns ratio is defined as the ratio of the number of turns between the two taps to the number of turns of the primary winding, and its primary turns ratio is q=0.227. The secondary winding has a center tap, and the secondary turns ratio is defined as the ratio of the number of turns of the primary winding to the number of turns of the secondary winding, and its secondary turns ratio is k=0.0244.

[0045] (3) Furthermore, the uncontrolled rectifying device includes a diode VD1, a diode VD2, a diode VD3, a diode VD4, a diode VD5, a diode VD6, a diode VD7, a diode VD8, a diode VD9, a diode VD10, a diode VD11, and a diode VD12, wherein the diode VD1 and the diode VD2 are respectively located at two taps of the primary side of the unconventional balancing reactor I, the diode VD7 and the diode VD8 are respectively located at two ends of the secondary winding of the unconventional balancing reactor I, the diode VD3 and the diode VD4 are respectively located at two taps of the primary side of the unconventional balancing reactor II, the diode VD9 and the diode VD10 are respectively located at two ends of the secondary winding of the unconventional balancing reactor II, the diode VD5 and the diode VD6 are respectively located at two taps of the primary side of the unconventional balancing reactor III, and the diode VD11 and the diode VD12 are respectively located at two ends of the secondary winding of the unconventional balancing reactor III;

[0046] The rectification method of the 54-pulse uncontrolled rectifier based on the above-mentioned unconventional balancing reactor includes: the three-phase full-bridge rectification has a 6-pulse rectification output for the three-phase voltage, the phase-shifting transformer generates 3 groups of three-phase voltages of equal magnitude and a phase difference of 20°, and the three-phase full-bridge rectification cooperates to output to obtain an 18-pulse rectification output;

[0047] Furthermore, three unconventional balanced reactors are used to output a 54-pulse rectifier output. dc1 ≥V dc2 &V dc1 ≥V dc3 There are three working modes: working mode I, working mode II, and working mode III. dc2 ≥V dc1 &V dc2 ≥V dc3 There are three working modes: working mode IV, working mode V, and working mode VI. dc3 ≥V dc1 &V dc3 ≥V dc2 When , there are three working modes, which are respectively recorded as working mode VII, working mode VIII, and working mode IX;

[0048] like Figure 2As shown, working mode I: when V dc1 ≥V dc3 V dc2 When the unconventional balancing reactor I: because V dc1 ≥V dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 | Smaller than the rectifier system output voltage V L , so diode VD7 and diode VD8 are not conducting; Unconventional balanced reactor II: Because V dc1 ≥V dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage on the diode VD9 and diode VD10 is |V s2 | Smaller than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balancing reactor III: Because q(V dc3 -V dc1 )≥q(V dc1 -V dc2 ), because of the diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work; at this time, the output voltage V o Relationship with the output voltage of the full-bridge output circuit: V o =2 / 3V dc3 +1 / 3V dc1 (Ignore the tiny voltage on the secondary side of the unconventional balancing reactor);

[0049] like Figure 3 As shown, working mode II: when V dc1 ≥V dc2 &V dc1 ≥V dc3 When the unconventional balancing reactor I: because V dc1 ≥V dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 |Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balanced reactor II: because V dc1 ≥V dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage on the diode VD9 and diode VD10 is |V s2|Greater than the rectifier system output voltage V L , so the secondary side diode VD10 is forward biased and turned on; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work; at this time, the output voltage V o Relationship with the output voltage of the full-bridge output circuit: V o =2 / 3V dc2 +1 / 3V dc3 (Ignore the tiny voltage on the secondary side of the unconventional balancing reactor);

[0050] like Figure 4 As shown, working mode III: when V dc1 ≥V dc2 V dc3 When the unconventional balancing reactor I: because V dc1 ≥V dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage on the diode VD7 and diode VD8 is |V s1 |Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balanced reactor II: because V dc1 ≥V dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage on the diode VD9 and diode VD10 is |V s2 | Smaller than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work; at this time, the output voltage V o Relationship with the output voltage of the full-bridge output circuit: V o =2 / 3V dc1 +1 / 3V dc2 (Ignore the tiny voltage on the secondary side of the unconventional balancing reactor);

[0051] The feasibility of the topological structure and theoretical analysis in the above steps (1), (2) and (3) is verified by using power electronic simulation software, where the input is a voltage source input with an input voltage of 380V and a frequency of 50Hz;

[0052] Figure 2The current loop diagram of the unconventional balancing reactor combination in working mode I shows that at this time: the primary side diode VD1 of the unconventional balancing reactor I is forward biased and turned on, and the secondary side diodes are not turned on; the primary side diode VD4 of the unconventional balancing reactor II is forward biased and turned on, and the secondary side diodes are not turned on; the unconventional balancing reactor III does not work;

[0053] Figure 3 This is a current loop diagram of the unconventional balancing reactor combination in working mode II. It can be seen that at this time: the primary side diode VD1 of the unconventional balancing reactor I is forward biased and turned on, and the secondary side diode VD7 is forward biased and turned on; the primary side diode VD4 of the unconventional balancing reactor II is forward biased and turned on, and the secondary side diode VD10 is forward biased and turned on; the unconventional balancing reactor III does not work;

[0054] Figure 4 The current loop diagram of the unconventional balancing reactor combination in working mode III shows that at this time: the primary side diode VD1 of the unconventional balancing reactor I is forward biased and turned on, and the secondary side diode VD7 is forward biased and turned on; the primary side diode VD4 of the unconventional balancing reactor II is forward biased and turned on, and the secondary side diodes are not turned on; the unconventional balancing reactor III does not work;

[0055] Figure 5 This is the input side current and output side voltage waveform diagram of the present invention. It can be seen that at this time, the input side current of the rectifier has a high sinusoidal degree and the output side voltage ripple is small.

[0056] The 54-pulse uncontrolled rectifier using unconventional balancing reactors of the present invention and the rectification method thereof have no active devices involved in the structure, are highly reliable and easy to implement, and need to add three unconventional balancing reactors on the basis of 18-pulse rectification to form an auxiliary passive pulse multiplication circuit, so as to realize the multiplication of the rectifier pulse number and obtain the 54-pulse rectifier. When the secondary side of the unconventional balancing reactor is in the on state, the output current and voltage of the uncontrolled rectification unit are adjusted, and its working mode is increased to realize pulse multiplication, and finally a specific current is generated on the AC side of the full-bridge rectifier to eliminate the characteristic subharmonics of the grid-side input current, thereby realizing the function of suppressing the grid-side current harmonics and reducing the output voltage ripple factor.

[0057] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. 54-pulse uncontrolled rectifier for unconventional balancing reactor, characterized in that: include: The phase-shifting transformer is used to shift the phase of the input voltage of the power grid to generate three-phase voltages with a phase difference of 20° and the same amplitude, and the voltage generated by the phase-shifting transformer is respectively sent to the full-bridge rectifier circuit I, the full-bridge rectifier circuit II, and the full-bridge rectifier circuit III for three-phase rectification of each phase angle; A full-bridge rectifier circuit, comprising a full-bridge rectifier circuit I, a full-bridge rectifier circuit II and a full-bridge rectifier circuit III, wherein three DC negative voltages outputted are connected to the negative end of the output terminal, and three DC positive voltages outputted are connected to the primary sides of the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III respectively; The combined unconventional balancing reactor includes unconventional balancing reactor I, unconventional balancing reactor II and unconventional balancing reactor III. The primary side of each unconventional balancing reactor has two taps, each tap passes through a clamping diode to form a DC side output terminal and is connected to the positive end of the output end load. Both ends of the secondary winding of each unconventional balancing reactor pass through a clamping diode to form a DC side auxiliary circuit positive output terminal and is connected to the output end load positive terminal. The central taps of the secondary windings of the three reactors are connected together to form a DC side auxiliary circuit negative output terminal and is connected to the negative end of the output end load.

2. The 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 1, characterized in that: The phase-shifting transformer is an autotransformer; the transformer consists of three core columns, each of which has three windings, including one primary winding and two secondary windings. There is a direct electrical connection between the windings. The primary winding is connected in a triangle shape, and the secondary winding is connected to the primary winding tap to generate three groups of three-phase voltages of equal size and a phase difference of 20°.

3. The 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 1, characterized in that: The unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III all adopt uncontrolled rectifier devices.

4. The 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 1, characterized in that: The three unconventional balancing reactors are all equipped with a single-phase transformer with a center tap, which includes a core column, a primary winding and a secondary winding on the core column, the primary winding has two taps symmetrical about the primary center, the primary turns ratio is defined as the ratio of the number of turns between the two taps to the number of turns of the primary winding, and the primary turns ratio is q=0.227; the secondary winding has a center tap, and the secondary turns ratio is defined as the ratio of the number of turns of the primary winding to the number of turns of the secondary winding, and the secondary turns ratio is k=0.0244.

5. The 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 3, characterized in that: The uncontrolled rectifying devices include diodes VD1, VD2, VD7 and VD8 of the unconventional balancing reactor I, diodes VD3, VD4, VD9 and VD10 of the unconventional balancing reactor II, and diodes VD5, VD6, VD11 and VD12 of the unconventional balancing reactor III.

6. A rectification method of a 54-pulse uncontrolled rectifier of an unconventional balancing reactor, based on the rectifier according to any one of claims 1 to 5, characterized in that: The full-bridge rectifier circuit has a 6-pulse rectified output for the three-phase voltage, and the phase-shifting transformer generates 3 groups of three-phase voltages of equal size and a phase difference of 20°. After the full-bridge rectifier circuit cooperates with the output, an 18-pulse rectified output is obtained; and then the 18-pulse rectified output is processed by the unconventional balancing reactor I, the unconventional balancing reactor II and the unconventional balancing reactor III respectively, the number of rectified pulses is increased, and a 54-pulse rectified output is obtained. For the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 and the output voltage V of the unconventional balancing reactor III dc3 There are three working modes: working mode Ⅰ, working mode Ⅱ, and working mode Ⅲ. For the output voltage V dc2 ≥ Output voltage V of unconventional balancing reactor I dc1 and the output voltage V of the unconventional balancing reactor III dc3 There are three working modes: working mode Ⅳ, working mode Ⅴ, and working mode Ⅵ; for the output voltage V of the unconventional balancing reactor Ⅲ dc3 ≥ Output voltage V of unconventional balancing reactor I dc1 and the output voltage V of the unconventional balancing reactor II dc2 There are three working modes, namely working mode VII, working mode VIII and working mode IX.

7. The rectification method of the 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 6, characterized in that: The working mode I: When the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 >>Output voltage V of unconventional balancing reactor II dc2 When the unconventional balancing reactor I: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage V on the diode VD7 and diode VD8 is s1 Less than the rectifier system output voltage V L , so diode VD7 and diode VD8 are not conducting; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage V on the diode VD9 and diode VD10 is s1 Less than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balancing reactor III: because q (V dc3 -V dc1 )≥q(V dc1 -V dc2 ), because of the diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work; Working mode II: When the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , and the output voltage V of the unconventional balancing reactor I dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 When the unconventional balancing reactor I: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage V on the diode VD7 and diode VD8 is s1 Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage on the diode VD9 and diode VD10 is -V s1 Greater than the rectifier system output voltage V L , so the secondary side diode VD10 is forward biased and turned on; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time, the unconventional balancing reactor III does not work; Working mode III: When the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 >>Output voltage V of unconventional balancing reactor III dc3 When the unconventional balancing reactor I: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor III dc3 , so VD1 is turned on, VD2 is reversed and cut off, i d2 =0, and because the voltage V on the diode VD7 and diode VD8 is s1 Greater than the rectifier system output voltage V L , so the secondary side diode VD7 is forward biased and turned on; Unconventional balancing reactor II: Because the output voltage V dc1 ≥ Output voltage V of unconventional balancing reactor II dc2 , so VD4 is turned on, VD3 is reversed and cut off, i d3 =0, and because the voltage V on the diode VD9 and diode VD10 is s1 Less than the rectifier system output voltage V L , so diode VD9 and diode VD10 are not conducting; Unconventional balanced reactor III: diode clamping effect i d5 =0, i d6 =0, at this time the unconventional balancing reactor III does not work.

8. The rectification method of the 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 6, characterized in that: The working mode IV: the unconventional balancing reactor I does not work; the unconventional balancing reactor II: VD3 is turned on, VD4 is reversely cut off, and both diodes VD9 and VD10 are not turned on; the unconventional balancing reactor III: VD5 is reversely cut off, so VD6 is turned on, and diodes VD11 and VD12 are not turned on; Working mode V: Unconventional balancing reactor I does not work; Unconventional balancing reactor II: VD3 is turned on, VD4 is reversely cut off, diode VD9 is turned on, and diode VD10 is reversely cut off; Unconventional balancing reactor III: VD5 is reversely cut off, so VD6 is turned on, diode VD11 is not turned on, and diode VD12 is turned on; Working mode VI: unconventional balancing reactor I does not work; unconventional balancing reactor II: VD3 is turned on, VD4 is reverse cutoff, diode VD9 is turned on, and diode VD10 is reverse cutoff; unconventional balancing reactor III: VD5 is reverse cutoff, so VD6 is turned on, and diodes VD11 and VD12 are not turned on.

9. The rectification method of the 54-pulse uncontrolled rectifier of the unconventional balancing reactor according to claim 6, characterized in that: The working mode VII: unconventional balancing reactor I: VD1 is reversely cut off, VD2 is turned on, and diodes VD7 and VD8 are not turned on; unconventional balancing reactor II does not work; unconventional balancing reactor III: VD5 is turned on, VD6 is reversely cut off, and diodes VD11 and VD12 are not turned on; Working mode VIII: Unconventional balancing reactor I: VD1 is reverse cutoff, VD2 is conducting, diode VD7 is not conducting, diode VD8 is conducting; Unconventional balancing reactor II does not work; Unconventional balancing reactor III: VD5 is turned on, VD6 is reversely cut off, diode VD11 is turned on, and diode VD12 is reversely cut off; Working mode IX: Unconventional balancing reactor I: VD1 is reverse cutoff, VD2 is turned on, diodes VD7 and VD8 are not turned on; unconventional balancing reactor II does not work; unconventional balancing reactor III: VD5 is turned on, VD6 is reverse cutoff, diode VD11 is turned on, and diode VD12 is reverse cutoff.

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