36-Pulse Rectifier Based on Low-Loss Passive Current Injection Pulse Multiplication

Abstract

36-pulse rectifier based on low-loss passive current injection pulse multiplication, which relates to the technical field of transformers. The 36-pulse rectifier includes a 12-pulse rectifier and a multiplication circuit. The multiplication circuit is located on the DC side of the 12-pulse rectifier and is used to multiply the pulses into 36 pulses. Among them, the output end of the multiplication circuit is used to connect the load. The 12-pulse rectifier is configured with the positive output end, negative input end and common output end of the 36-pulse rectifier. The multiplication circuit includes an auxiliary single-phase transformer, a first double-secondary-winding transformer, a second double-secondary-winding transformer, a single-phase full-wave rectifier circuit, and an auxiliary diode assembly. According to the voltage and current relationship between the AC and DC sides, the pulse number of the conventional series-type 12-pulse rectifier is multiplied into 36 pulses, effectively suppressing the distortion of the input current and output voltage of the rectifier.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and more particularly, to a 36-pulse rectifier based on low-loss passive current injection pulse multiplication. Background Art

[0002] The series-connected 12-pulse rectifier has the advantages of simple circuit structure, high reliability, low electromagnetic interference (EMI), and strong overload capacity. Therefore, it is usually used as an interface circuit for medium and high-voltage electronic devices to obtain energy from the power grid.

[0003] However, the input current of the series-connected 12-pulse rectifier still contains a large amount of 12n±1 order harmonics, and the typical total harmonic distortion (THD) is greater than 10%, which fails to meet the requirements of the IEEE-519 harmonic standard. To effectively suppress the input current harmonics of the series-connected 12-pulse rectifier, various solutions have been proposed in the prior art.

[0004] The first is to increase the number of pulses of the rectification system by adjusting the design of the phase-shifting transformer, which can effectively reduce the total harmonic distortion (THD) of the input current. However, as the number of pulses increases, the windings of the transformer become more complex. The complex winding structure may lead to the imbalance of the equivalent impedance of the transformer, and then lead to the imbalance of system parameters and increase the content of non-primary harmonics. In addition, the effect of reducing the input current THD by only increasing the number of pulses also has limitations. Therefore, relying solely on changing the structure of the phase-shifting transformer to increase the number of pulses of the rectification system, the harmonic suppression effect is limited.

[0005] The second is to add active harmonic suppression on the DC side of the rectifier. The active harmonic suppression technology on the DC side can modulate the system input current to be in phase with the input voltage, making it closer to a sine wave. However, it requires sampling the input voltage phase, load current, and compensation injection current, and the control circuit is complex, and it cannot increase the number of pulses of the load output voltage.

[0006] The third is to use a DC-side hybrid harmonic suppression strategy, combined with the use of auxiliary circuits and active switching tubes. By controlling the conduction state of the current injection circuit, the harmonic modulation of the voltage and current waveforms on the DC side is carried out to increase the number of steps of the waveforms, so as to achieve the goal of increasing the number of pulses of the rectifier. This method optimizes the power quality on the DC side by precisely controlling the injection of current and improves the rectification efficiency at the same time.

[0007] Based on the above analysis, an auxiliary circuit is set on the DC side of a 12-pulse rectifier to multiply the pulses of the input three-phase current, which can solve problems such as high harmonic content in the input current of the rectification system and distortion of the output voltage. However, this kind of pulse multiplication technology uses a relatively large number of parallel diodes in the structure, resulting in a complex structure and an increase in additional losses, and the capacity occupied by the auxiliary transformer is large. Moreover, the turns ratio of the primary and secondary windings of the auxiliary transformer in the auxiliary circuit is relatively large, which will cause a large leakage inductance in the transformer and reduce the harmonic suppression effect. Summary of the Invention

[0008] The present invention provides a 36-pulse rectifier based on low-loss passive current injection pulse multiplication, aiming to improve at least one of the above technical problems.

[0009] To solve the above technical problems, the present invention provides a 36-pulse rectifier based on low-loss passive current injection pulse multiplication, which includes a 12-pulse rectifier and a multiplication circuit. The multiplication circuit is located on the DC side of the 12-pulse rectifier for multiplying the pulses to 36 pulses. Among them, the output end of the multiplication circuit is used to connect to the load. The 12-pulse rectifier is configured with the positive output end, negative input end, and common output end of the 36-pulse rectifier.

[0010] The multiplication circuit includes an auxiliary single-phase transformer, a first double-secondary-winding transformer, a second double-secondary-winding transformer, a single-phase full-wave rectification circuit, and an auxiliary diode assembly.

[0011] One end of the primary winding of the auxiliary single-phase transformer is connected to the common output end, and the other end is connected to the auxiliary diode assembly, as well as the primary windings of the first double-secondary-winding transformer and the second double-secondary-winding transformer.

[0012] The secondary winding of the auxiliary single-phase transformer is provided with a left tap and a right tap connected to the single-phase full-wave rectification, and an adjustment tap connected to the negative input end of the 36-pulse rectifier.

[0013] The primary winding of the first double-secondary-winding transformer is connected to the positive output end of the 36-pulse rectifier through a first capacitor.

[0014] The secondary winding of the first double-secondary-winding transformer is provided with an upper winding and a lower winding, and is connected between the auxiliary diode assembly and the secondary winding of the second double-secondary-winding transformer.

[0015] The primary winding of the second double-secondary-winding transformer is connected to the negative input end of the 36-pulse rectifier through a second capacitor.

[0016] The secondary winding of the second double-secondary-winding transformer is provided with an upper winding and a lower winding, and is connected between the secondary winding of the first double-secondary-winding transformer and the positive output end of the 36-pulse rectifier.

[0017] The turn ratios of the primary and secondary windings of the auxiliary single-phase transformer, the first double-secondary-winding transformer, and the second double-secondary-winding transformer are configured such that the conduction time of the single-phase full-wave rectifier circuit and the auxiliary diode assembly is 1 / 2 of the voltage period received at the AC input terminal.

[0018] In an alternative embodiment, the first capacitor and the second capacitor have the same size.

[0019] In an alternative embodiment, the negative terminal of the primary winding of the auxiliary single-phase transformer is connected to the common output terminal. The positive terminal of the primary winding of the auxiliary single-phase transformer is connected to the common anode of the single-phase full-wave rectifier circuit and is circuit-connected to the negative terminal of the primary winding of the first double-secondary-winding transformer and the positive terminal of the primary winding of the second double-secondary-winding transformer.

[0020] The secondary winding of the auxiliary single-phase transformer is provided with a left tap, a right tap, and an adjustment tap. The left tap and the right tap are connected to the single-phase full-wave rectifier circuit, and the adjustment tap and the negative electrode of the second capacitor are connected to the negative input terminal of the 36-pulse rectifier.

[0021] In an alternative embodiment, the auxiliary diode assembly includes a first auxiliary diode and a second auxiliary diode . The first auxiliary diode and the second auxiliary diode have their anodes connected to the common output terminal.

[0022] In an alternative embodiment, the positive terminal of the primary winding of the first double-secondary-winding transformer is connected to the negative terminal of the first capacitor . The secondary winding of the first double-secondary-winding transformer is provided with an upper winding and a lower winding. The positive terminal of the upper winding of the secondary winding of the first double-secondary-winding transformer is connected to the cathode of the second auxiliary diode . The negative terminal of the upper winding of the secondary winding of the first double-secondary-winding transformer is connected to the negative terminal of the upper winding of the secondary winding of the second double-secondary-winding transformer. The negative terminal of the lower winding of the secondary winding of the first double-secondary-winding transformer is connected to the cathode of the first auxiliary diode . The positive terminal of the secondary winding of the first double-secondary-winding transformer is connected to the positive terminal of the lower winding of the secondary winding of the second double-secondary-winding transformer.

[0023] In an alternative embodiment, the negative terminal of the primary winding of the second double-secondary-winding transformer is connected to the second capacitor is connected to the positive electrode. The secondary winding of the second double-secondary winding transformer is provided with an upper winding and a lower winding. The anodic end of the upper winding of the secondary winding of the second double-secondary winding transformer, the cathodic end of the lower winding of the secondary winding of the second double-secondary winding transformer, and the positive electrode of the first capacitor are all connected to the positive output terminal of the 36-pulse rectifier. Among them, the positive output terminal of the 36-pulse rectifier is adapted to be connected to the positive input terminal of the load.

[0024] In an optional embodiment, the single-phase full-wave rectification circuit includes a first diode and a second diode . The cathode of the first diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer. The cathode of the second diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer. The anodes of the first diode and the second diode are both used to be connected to the negative output terminal of the load.

[0025] In an optional embodiment, the 12-pulse rectifier includes a phase-shifting transformer, a first diode rectifier bridge, and a second diode rectifier bridge. The phase-shifting transformer is adapted to adjust the three-phase voltage input from the power grid to generate two sets of three-phase voltage signals with a phase difference of 30° and the same amplitude, and then transmit these two sets of voltages to the first and second diode rectifier bridges respectively.

[0026] The positive output terminal of the first diode rectifier bridge is configured as the positive output terminal of the 36-pulse rectifier. The negative input terminal of the second diode rectifier bridge is configured as the negative input terminal of the 36-pulse rectifier. The negative input terminal of the first diode rectifier bridge is connected to the positive output terminal of the second diode rectifier bridge, and is configured as the common output terminal of the DC side bus of the 36-pulse rectifier.

[0027] In an optional embodiment, the 36-pulse rectifier is configured to have a first operating mode, a second operating mode, and a third operating mode. The first operating mode is: a non-operating state in which the first auxiliary diode and the second auxiliary diode are reverse-biased and cut off. The second operating mode is: a first power supply state in which the first auxiliary diode is reverse-biased and cut off, and the second auxiliary diode is forward-conducting. The third operating mode is: a second power supply state in which the first auxiliary diode is forward-conducting and the second auxiliary diode is reverse-biased and cut off.

[0028] In an optional embodiment, the first operating mode is specifically: when , And When, in the single-phase full-wave rectifier circuit, the first diode and the second diode are forward-conducting, the first auxiliary diode in the auxiliary diode assembly and the second auxiliary diode are reverse-biased and cut off. The current flowing through the first capacitor and the current flowing through the second capacitor are defaulted to 0. At this time, the auxiliary single-phase transformer, the first double-secondary-winding transformer, and the second double-secondary-winding transformer are all in a non-operating state.

[0029] In an alternative embodiment, the second operating mode is: when , And When, in the single-phase full-wave rectifier circuit, the second diode is forward-conducting, the first diode is reverse-biased and cut off. The second auxiliary diode in the auxiliary diode assembly is forward-conducting, and the first auxiliary diode is reverse-biased and cut off. At this time, the auxiliary single-phase transformer, the first double-secondary-winding transformer, and the second double-secondary-winding transformer are all in a normal operating state, and the first double-secondary-winding transformer and the second double-secondary-winding transformer jointly supply power to the load.

[0030] In an alternative embodiment, the third operating mode is: when , And When, in the single-phase full-wave rectifier circuit, the first diode is forward-conducting, the second diode is reverse-biased and cut off. The first auxiliary diode in the auxiliary diode assembly is forward-conducting, and the second auxiliary diode is reverse-biased and cut off. At this time, the auxiliary single-phase transformer, the first double-secondary-winding transformer, and the second double-secondary-winding transformer are all in a normal operating state, and the first double-secondary-winding transformer and the second double-secondary-winding transformer jointly supply power to the load.

[0031] Wherein: Is the voltage across the secondary winding of the auxiliary single-phase transformer, Is the voltage across the load, Is the voltage output by the first diode rectifier bridge, Is the voltage output by the second diode rectifier bridge, And Are the voltages across the two secondary windings of the first double-secondary-winding transformer respectively, and are the terminal voltages at both ends of the two secondary windings of the second dual-secondary-winding transformer respectively.

[0032] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0033] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication on the DC side in this embodiment does not require increasing the complexity of the phase-shifting transformer, and the number of diodes used is also reduced. In each working state, only two diodes in the low-loss passive current injection pulse multiplication circuit on the DC side are in the working state, and the auxiliary diodes and are connected in parallel with the DC bus and the positive input terminal of the load, and are not directly connected to the load, which greatly reduces the conduction loss of the diodes. Moreover, the turns ratio of the primary and secondary windings of the auxiliary single-phase transformer is small, reducing the leakage inductance, and the power capacity of the auxiliary single-phase transformer accounts for a small proportion of the system capacity, which is convenient for manufacturing, achieving the effect of reducing both the input current harmonics and the output voltage ripple of the 36-pulse rectifier simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the specific embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 is a schematic structural diagram of a 36-pulse rectifier.

[0036] Figure 2 is a schematic structural diagram of a phase-shifting transformer.

[0037] Figure 3 is a schematic structural diagram of an auxiliary single-phase transformer.

[0038] Figure 4 is a schematic structural diagram of a dual-secondary-winding transformer.

[0039] Figure 5 is a schematic diagram of the 36-pulse rectifier in the first working mode.

[0040] Figure 6 is a schematic diagram of the 36-pulse rectifier in the second working mode.

[0041] Figure 7 is a schematic diagram of the 36-pulse rectifier in the third working mode.

[0042] Figure 8Is the input current , and waveform diagrams.

[0043] Figure 9 Is the Fourier analysis diagram of the input current of.

[0044] Markings in the figure: 1 - phase-shifting transformer, 2 - first diode rectifier bridge, 3 - second diode rectifier bridge, 4 - auxiliary single-phase transformer, 5 - single-phase full-wave rectifier circuit, 6 - first double-secondary winding transformer, 7 - second double-secondary winding transformer, 8 - auxiliary diode assembly, 9 - load. Specific embodiments

[0045] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0046] As Figures 1 to 9 shown, the embodiment of the present invention provides a 36-pulse rectifier based on low-loss passive current injection pulse multiplication. It includes a series-type 12-pulse rectifier and a DC-side low-loss passive current injection pulse multiplication circuit. The low-loss passive current injection pulse multiplication circuit is located on the DC side of the series-type 12-pulse rectifier, and is used to multiply the output of the series-type 12-pulse rectifier to 36 pulses. Among them, the output end of the low-loss passive current injection pulse multiplication circuit is used to connect to the load 9. The series-type 12-pulse rectifier and the low-loss passive current injection pulse multiplication circuit are combined to form a 36-pulse rectifier. The 36-pulse rectifier includes a positive output end, a negative input end, and a DC-side bus common output end K. This 36-pulse rectifier can meet the industrial application standard of IEEE-519 for harmonic content in high-power applications such as industrial metallurgy and industrial hydrogen production.

[0047] The series-connected 12-pulse rectifier includes a phase-shifting transformer 1, a first diode rectifier bridge 2, and a second diode rectifier bridge 3. The function of the phase-shifting transformer 1 is to adjust the three-phase voltage input from the power grid to generate two sets of three-phase voltage signals with a 30° phase difference and the same amplitude, and then transmit these two sets of voltages to the first and second diode rectifier bridges 3 respectively.

[0048] The structure of the phase-shifting transformer 1 in this embodiment is as Figure 2 shown. The input end of the phase-shifting transformer 1 is used to input a three-phase AC power supply. The output ends of the phase-shifting transformer 1 are respectively electrically connected to the first diode rectifier bridge 2 and the second diode rectifier bridge 3 to generate two sets of three-phase voltages with a 30° phase difference and the same amplitude. Among them, the AC-side input currents are respectively , , . , , The waveform schematic diagrams of are as Figure 8 shown. The Fourier spectrum schematic diagram of the waveform is as Figure 9 shown.

[0049] The positive output end of the first diode rectifier bridge 2 is configured as the positive output end of the 36-pulse rectifier. The negative input end of the second diode rectifier bridge 3 is configured as the negative input end of the 36-pulse rectifier. The negative input end of the first diode rectifier bridge 2 is connected to the positive output end of the second diode rectifier bridge 3 to form the common output end K of the DC-side bus of the 36-pulse rectifier.

[0050] The low-loss passive current injection pulse multiplication circuit includes an auxiliary single-phase transformer 4, a first double-secondary-winding transformer 6, a second double-secondary-winding transformer 7, a single-phase full-wave rectifier circuit 5, an auxiliary diode assembly 8, and first capacitors and second capacitors with equal magnitudes. Among them, the auxiliary diode assembly 8 includes a first auxiliary diode and a second auxiliary diode . The anodes of the first auxiliary diode and the second auxiliary diode are connected to the DC bus. The DC bus is the line directly electrically connected to the common output end.

[0051] One end of the primary winding of the auxiliary single-phase transformer 4 is connected to the common output end, and the other end is connected to the auxiliary diode assembly 8, as well as the primary windings of the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7. The secondary winding of the auxiliary single-phase transformer 4 is provided with a left tap and a right tap connected to the single-phase full-wave rectifier, and an adjustment tap connected to the negative input end of the 36-pulse rectifier.

[0052] Specifically, the negative electrode end of the primary winding of the auxiliary single-phase transformer 4 is connected to the common output terminal K of the DC side of the 36-pulse rectifier. The positive electrode end of the primary winding of the auxiliary single-phase transformer 4 is connected to the common anode of the auxiliary diode assembly 8. The positive electrode end of the primary winding of the auxiliary single-phase transformer 4 is electrically connected to the negative electrode end of the primary winding of the first double-secondary winding transformer 6 and the positive electrode end of the primary winding of the second double-secondary winding transformer 7. And the connection point is constructed as a common terminal M. The secondary winding of the auxiliary single-phase transformer 4 is provided with a left tap, a right tap, and an adjustable tap. The left tap and the right tap are connected to the single-phase full-wave rectifier circuit 5, and the adjustable tap and the negative electrode of the second capacitor are connected to the negative input terminal of the 36-pulse rectifier.

[0053] The primary winding of the first double-secondary winding transformer 6 is connected to the positive output terminal of the 36-pulse rectifier through a first capacitor. The secondary winding of the first double-secondary winding transformer 6 is provided with an upper winding and a lower winding, and is connected between the auxiliary diode assembly 8 and the secondary winding of the second double-secondary winding transformer 7.

[0054] Specifically, the positive electrode end of the primary winding of the first double-secondary winding transformer 6 is connected to the negative electrode end of the first capacitor. The secondary winding of the first double-secondary winding transformer 6 is provided with an upper winding and a lower winding. The positive electrode end of the upper winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the cathode of the second auxiliary diode. The negative electrode end of the upper winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the negative electrode end of the upper winding of the secondary winding of the second double-secondary winding transformer 7. The negative electrode end of the lower winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the cathode of the first auxiliary diode. The positive electrode end of the secondary winding of the first double-secondary winding transformer 6 is connected to the positive electrode end of the lower winding of the secondary winding of the second double-secondary winding transformer 7.

[0055] The primary winding of the second double-secondary winding transformer 7 is connected to the negative input terminal of the 36-pulse rectifier through a second capacitor. The secondary winding of the second double-secondary winding transformer 7 is provided with an upper winding and a lower winding, and is connected between the secondary winding of the first double-secondary winding transformer 6 and the positive output terminal of the 36-pulse rectifier.

[0056] Specifically, the negative electrode end of the primary winding of the second double-secondary winding transformer 7 is connected to the positive electrode of the second capacitor. The secondary winding of the second double-secondary winding transformer 7 is provided with an upper winding and a lower winding. The positive electrode end of the upper winding of the secondary winding of the second double-secondary winding transformer 7, the negative electrode end of the lower winding of the secondary winding of the second double-secondary winding transformer 7, and the first capacitor The positive electrodes are all connected to the positive output terminal of the 36-pulse rectifier. Among them, the positive output terminal of the 36-pulse rectifier is adapted to be connected to the positive input terminal of the load 9.

[0057] Based on the above embodiments, in an optional embodiment of the present invention, as Figure 1 shown, the single-phase full-wave rectifier circuit 5 includes a first diode and a second diode . The cathode of the first diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer 4. The cathode of the second diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer 4. The anodes of the first diode and the second diode are both used to be connected to the negative output terminal of the load 9. That is: the common anode of the single-phase full-wave rectifier circuit 5 is used to be connected to the negative output terminal of the load 9.

[0058] By setting the turns ratio of the primary and secondary windings of the auxiliary single-phase transformer 4, the turns ratio of the primary and secondary windings of the first double-secondary-winding transformer 6, and the turns ratio of the primary and secondary windings of the second double-secondary-winding transformer 7, the conduction time of the single-phase full-wave rectifier circuit 5 and the auxiliary diode assembly 8 is 1 / 2 of the voltage cycle received by the two AC input terminals of the single-phase full-wave rectifier circuit 5 and the auxiliary diode assembly 8, and the injection current = 0 and = 0 for the time of the grid-side input current , , is one-twelfth of the power frequency cycle. It should be noted that the more pulse numbers, the closer it is to the ideal sine wave, reducing the harmonic distortion of the input-side current , , . Among them, is the current at the negative terminal of the primary winding of the input auxiliary single-phase transformer 4. is the current at the input common terminal M.

[0059] Specifically, by setting the turns ratio of the primary and secondary windings of the auxiliary single-phase transformer 4, the turns ratio of the primary and secondary windings of the first transformer with double-secondary windings, and the turns ratio of the primary and secondary windings of the second transformer with double-secondary windings, the conduction time of the single-phase full-wave rectifier circuit 5 and the auxiliary diode assembly 8 is 1 / 2 of the voltage cycle received by the two AC input terminals of the single-phase full-wave rectifier circuit 5 and the auxiliary diode assembly 8, and the injection current = 0 and = 0 for the time of the grid-side input current , , One twelfth of the power frequency period.

[0060] The above circuit structure can be understood as using two isolation transformers as the phase-shifting transformer 1 to prevent faults (such as short circuits) on the power supply side from being transmitted to the load 9 side, thereby improving the safety of the entire system. When the isolation transformer is used as the phase-shifting transformer 1, by shifting the phase of the high-voltage side of the rectifier transformer, low-order harmonics with relatively large amplitudes can be basically eliminated, thereby reducing harmonic pollution. The AC-side input current is doubled from 12 pulses to 36 pulses through a low-loss passive current injection pulse multiplication circuit, and the auxiliary circuit structure is simple. The turns ratio of the primary and secondary windings of the auxiliary single-phase transformer 4 is small, the conduction loss of the diode is low, and it has high reliability and harmonic suppression performance.

[0061] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to the embodiment of the present invention uses all passive devices. It has a simple structure, low cost, high operating reliability, and low maintenance cost. Two large capacitors on the DC output side can reduce the DC voltage ripple, improve the power factor, improve the power quality, reduce electromagnetic interference, improve the system stability, reduce the cost of harmonic suppression, and improve the input power factor of the rectifier and reduce the harmonic content of the input current. Preferably, the turns ratio of the primary and secondary sides of the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7 is the same, which balances the current of the input capacitor and makes the output voltage of the rectifier remain constant during steady-state operation.

[0062] Based on the above embodiment, in an optional embodiment of the present invention, the 36-pulse rectifier is configured to have a first operating mode, a second operating mode, and a third operating mode. The first operating mode is: the non-operating state in which the first auxiliary diode and the second auxiliary diode are reverse-biased and cut off. The second operating mode is: the first power supply state in which the first auxiliary diode is reverse-biased and cut off, and the second auxiliary diode is forward-conducting. The third operating mode is: the second power supply state in which the first auxiliary diode is forward-conducting and the second auxiliary diode is reverse-biased and cut off.

[0063] Preferably, as Figure 5 shown, the first operating mode is specifically: when , and , the first diode and the second diode in the single-phase full-wave rectifier circuit 5 are forward-conducting, and the first auxiliary diode and the second auxiliary diode in the auxiliary diode assembly 8 Reverse bias cutoff, current flowing through the first capacitor and the current through the second capacitor are both defaulted to 0. At this time, the auxiliary single-phase transformer 4, the first double-secondary-winding transformer 6, and the second double-secondary-winding transformer 7 are all in a non-operating state. Preferably, as shown in, the second operating mode is: when, and, the second diode in the single-phase full-wave rectifier circuit 5 is forward-conducting, the first diode is reverse-bias cutoff, the second auxiliary diode in the auxiliary diode assembly 8 is forward-conducting, and the first auxiliary diode is reverse-bias cutoff. At this time, the auxiliary single-phase transformer 4, the first double-secondary-winding transformer 6, and the second double-secondary-winding transformer 7 are all in a normal operating state, and the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7 jointly supply power to the load 9.

[0064] Preferably, as shown in, the third operating mode is: when, and, the first diode in the single-phase full-wave rectifier circuit 5 is forward-conducting, the second diode is reverse-bias cutoff, the first auxiliary diode in the auxiliary diode assembly 8 is forward-conducting, and the second auxiliary diode is reverse-bias cutoff. At this time, the auxiliary single-phase transformer 4, the first double-secondary-winding transformer 6, and the second double-secondary-winding transformer 7 are all in a normal operating state, and the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7 jointly supply power to the load 9. Figure 6 shown, the second operating mode is: when , and when, the second diode in the single-phase full-wave rectifier circuit 5 is forward-conducting, the first diode is reverse-bias cutoff, the second auxiliary diode in the auxiliary diode assembly 8 is forward-conducting, and the first auxiliary diode is reverse-bias cutoff. At this time, the auxiliary single-phase transformer 4, the first double-secondary-winding transformer 6, and the second double-secondary-winding transformer 7 are all in a normal operating state, and the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7 jointly supply power to the load 9.

[0065] Preferably, as shown in Figure 7 shown, the third operating mode is: when , and when, the first diode in the single-phase full-wave rectifier circuit 5 is forward-conducting, the second diode is reverse-bias cutoff, the first auxiliary diode in the auxiliary diode assembly 8 is forward-conducting, and the second auxiliary diode is reverse-bias cutoff. At this time, the auxiliary single-phase transformer 4, the first double-secondary-winding transformer 6, and the second double-secondary-winding transformer 7 are all in a normal operating state, and the first double-secondary-winding transformer 6 and the second double-secondary-winding transformer 7 jointly supply power to the load 9.

[0066] Wherein: is the voltage across the secondary winding of the auxiliary single-phase transformer 4, is the voltage across the load 9, is the voltage output by the first diode rectifier bridge 2, is the voltage output by the second diode rectifier bridge 3, and are the voltages across the two secondary windings of the first double-secondary-winding transformer 6 respectively, and are the voltages across the two secondary windings of the second double-secondary-winding transformer 7 respectively.

[0067] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication on the DC side in the embodiment of the present invention includes a series-connected 12-pulse rectifier, a low-loss passive current injection pulse multiplication circuit, and a load 9. The low-loss passive current injection pulse multiplication circuit is located on the DC side of the series-connected 12-pulse rectifier. Through the loop formed by this circuit, the input / output current of the rectifier bridge is modulated into a three-level stepped wave, doubling the 12-pulse rectifier to 36 pulses.

[0068] The 36-pulse rectifier in the embodiment of the present invention uses a dual-tapped auxiliary single-phase transformer 4 and two transformers with dual-secondary windings, simplifying the circuit structure of the existing pulse multiplication technology with an auxiliary circuit. The primary winding of the auxiliary single transformer is directly connected in series on the DC side bus, reducing the voltage level and conduction loss. The secondary winding of the first transformer with dual-secondary windings is connected in parallel with the secondary winding of the second transformer with dual-secondary windings between the DC bus and the positive input terminal of the load 9, and is not directly connected to the circuit on the load 9 side, reducing the loss of the auxiliary diode.

[0069] In each working state, only two diodes are working, greatly reducing the conduction loss of the auxiliary diodes, and the capacity occupied by the auxiliary single-phase transformer 4 is small. Moreover, the turns ratio of the primary and secondary sides of the three transformers is small, and the leakage inductance is small, effectively improving the harmonic suppression effect. According to the voltage and current relationship between the AC and DC sides, the pulse number of the conventional series-connected 12-pulse rectifier is doubled to 36 pulses, effectively suppressing the distortion of the input current and output voltage of the rectifier.

[0070] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication on the DC side in this embodiment does not require increasing the complexity of the phase-shifting transformer 1, and the number of diodes used is also reduced. In each working state, only two diodes in the low-loss passive current injection pulse multiplication circuit on the DC side are in the working state, and the auxiliary diode and are connected in parallel with the DC bus and the positive input terminal of the load 9, and are not directly connected to the load 9, greatly reducing the conduction loss of the diode. Moreover, the turns ratio of the primary and secondary windings of the auxiliary single-phase transformer 4 is small, reducing the leakage inductance, and the power capacity of the auxiliary single-phase transformer 4 accounts for a small proportion of the system capacity, which is convenient for manufacturing, achieving the effect of reducing both the input current harmonics and output voltage ripple of the 36-pulse rectifier.

[0071] The rectifier of the present invention is a voltage source multi-pulse rectifier based on a DC-side passive auxiliary circuit, which does not require three large inductors to be connected in series on the input side, does not need to use active switching devices, and does not require a complex control circuit. At the same time, it avoids the problems of factor reduction and softening of output characteristics caused by series inductors. Moreover, when the second and third transformers with double secondary windings are in a damaged or non-operating state, the entire circuit can still operate normally in a 36-pulse state relying on the auxiliary single-phase transformer 4 and the single-phase full-wave rectifier circuit 5. And the present invention has great advantages in aspects such as harmonic control, efficiency, reliability, and reduction of grid pollution.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A 36-pulse rectifier based on low-loss passive current injection pulse multiplication, characterized in that, It includes a 12-pulse rectifier and a pulse multiplication circuit; the pulse multiplication circuit is located on the DC side of the 12-pulse rectifier for multiplying the pulses into 36 pulses; wherein, the output end of the pulse multiplication circuit is used to connect to a load (9); the 12-pulse rectifier is configured with a positive output end, a negative input end and a common output end of a 36-pulse rectifier; The pulse multiplication circuit includes an auxiliary single-phase transformer (4), a first double-secondary-winding transformer (6), a second double-secondary-winding transformer (7), a single-phase full-wave rectifier circuit (5), and an auxiliary diode assembly (8); One end of the primary winding of the auxiliary single-phase transformer (4) is connected to the common output end, the other end is connected to the auxiliary diode assembly (8), and the primary windings of the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7); The secondary winding of the auxiliary single-phase transformer (4) is provided with a left tap, a right tap connected to the single-phase full-wave rectifier, and an adjustment tap connected to the negative input end of the 36-pulse rectifier; The primary winding of the first double-secondary-winding transformer (6) is connected to the positive output end of the 36-pulse rectifier through a first capacitor; The secondary winding of the first double-secondary-winding transformer (6) is provided with an upper winding and a lower winding, and is connected between the auxiliary diode assembly (8) and the secondary winding of the second double-secondary-winding transformer (7); The primary winding of the second double-secondary-winding transformer (7) is connected to the negative input end of the 36-pulse rectifier through a second capacitor; The secondary winding of the second double-secondary-winding transformer (7) is provided with an upper winding and a lower winding, and is connected between the secondary winding of the first double-secondary-winding transformer (6) and the positive output end of the 36-pulse rectifier; The turns ratio of the primary and secondary windings of the auxiliary single-phase transformer (4), the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) is configured to enable the conduction time of the single-phase full-wave rectifier circuit (5) and the auxiliary diode assembly (8) to be 1 / 2 of the voltage cycle received by the AC input end; The 36-pulse rectifier is configured to have a first operating mode, a second operating mode and a third operating mode; The first operating mode is that the first auxiliary diode and the second auxiliary diode are in a non-operating state of reverse-biased cut-off; The second operating mode is: the first auxiliary diode is reverse-biased and cut off, and the second auxiliary diode is in the first power supply state of forward conduction; The third operating mode is: the first auxiliary diode is forward-conducting, and the second auxiliary diode is in a reverse-biased cut-off second power supply state.

2. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, characterized in that, The first capacitor and the second capacitor are of the same size; The cathode end of the primary winding of the auxiliary single-phase transformer (4) is connected to the common output end; the anode end of the primary winding of the auxiliary single-phase transformer (4) is connected to the common anode of the single-phase full-wave rectifier circuit (5), and is circuit-connected to the cathode end of the primary winding of the first double-secondary-winding transformer (6) and the anode end of the second double-secondary-winding transformer (7); The secondary winding of the auxiliary single-phase transformer (4) is provided with a left tap, a right tap, and an adjustment tap; the left tap and the right tap are connected to the single-phase full-wave rectifier circuit (5), and the adjustment tap and the negative electrode of the second capacitor are connected to the negative input end of the 36-pulse rectifier.

3. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, wherein The auxiliary diode assembly (8) includes a first auxiliary diode and a second auxiliary diode ; the anodes of the first auxiliary diode and the second auxiliary diode are connected to a common output terminal; The positive terminal of the primary winding of the first dual-secondary winding transformer (6) is connected to the negative terminal of the first capacitor ; The secondary winding of the first double-secondary winding transformer (6) is provided with an upper winding and a lower winding; the anodic end of the upper winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the cathode of the second auxiliary diode ; the cathodic end of the upper winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the cathodic end of the upper winding of the secondary winding of the second double-secondary winding transformer (7); the cathodic end of the lower winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the cathode of the first auxiliary diode ; the anodic end of the secondary winding of the first double-secondary winding transformer (6) is connected to the anodic end of the lower winding of the secondary winding of the second double-secondary winding transformer (7).

4. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 3, wherein The negative terminal of the primary winding of the second dual-secondary winding transformer (7) is connected to the positive electrode of the second capacitor ; The secondary winding of the second dual-secondary-winding transformer (7) is provided with an upper winding and a lower winding; the anodic end of the upper winding of the secondary winding of the second dual-secondary-winding transformer (7), the cathodic end of the lower winding of the secondary winding of the second dual-secondary-winding transformer (7), and the positive electrode of the first capacitor are all connected to the positive output terminal of the 36-pulse rectifier; wherein, the positive output terminal of the 36-pulse rectifier is adapted to be connected to the positive input terminal of the load (9).

5. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, characterized in that, The single-phase full-wave rectifier circuit (5) includes a first diode and a second diode ; the cathode of the first diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer (4); the cathode of the second diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer (4); the anodes of the first diode and the second diode are both used to be connected to the negative output terminal of the load (9).

6. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to any one of claims 1 to 4, characterized in that, The 12-pulse rectifier includes a phase-shifting transformer (1), a first diode rectifier bridge (2) and a second diode rectifier bridge (3); the phase-shifting transformer (1) is adapted to adjust the three-phase voltage input from the power grid to generate two sets of three-phase voltage signals with a 30° phase difference and the same amplitude, and then transmit these two sets of voltages to the first and second diode rectifier bridges (3) respectively; The positive output terminal of the first diode rectifier bridge (2) is configured as the positive output terminal of the 36-pulse rectifier; the negative input terminal of the second diode rectifier bridge (3) is configured as the negative input terminal of the 36-pulse rectifier; the negative input terminal of the first diode rectifier bridge (2) is connected to the positive output terminal of the second diode rectifier bridge (3) to form the common output terminal of the DC side bus of the 36-pulse rectifier.

7. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, characterized in that, The specific first working mode is as follows: When , and , the first diode and the second diode in the single-phase full-wave rectifier circuit (5) are forward-conducting, the first auxiliary diode and the second auxiliary diode in the auxiliary diode assembly (8) are reverse-biased and cut off, and the current flowing through the first capacitor and the current flowing through the second capacitor are defaulted to 0; at this time, the auxiliary single-phase transformer (4), the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) are all in a non-operating state; Wherein: is the voltage across the two ends of the secondary winding of the auxiliary single-phase transformer (4), is the voltage across the load (9), is the voltage output by the first diode rectifier bridge (2), is the voltage output by the second diode rectifier bridge (3), and are respectively the voltages across the two ends of the two secondary windings of the first double-secondary-winding transformer (6), and are respectively the voltages across the two ends of the two secondary windings of the second double-secondary-winding transformer (7).

8. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, wherein The second working mode is as follows: When , and at this time, the second diode in the single-phase full-wave rectifier circuit (5) is forward-conducting, the first diode is reverse-biased and cut off, the second auxiliary diode in the auxiliary diode assembly (8) is forward-conducting, the first auxiliary diode is reverse-biased and cut off; at this time, the auxiliary single-phase transformer (4), the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) are all in normal working states, and the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) jointly supply power to the load (9); Wherein: is the voltage across the two ends of the secondary winding of the auxiliary single-phase transformer (4), is the voltage across the load (9), is the voltage output by the first diode rectifier bridge (2), is the voltage output by the second diode rectifier bridge (3), and are the voltages across the two ends of the two secondary windings of the first dual-secondary-winding transformer (6) respectively, and are the voltages across the two ends of the two secondary windings of the second dual-secondary-winding transformer (7) respectively.

9. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, wherein The third working mode is as follows: When , and at this time, the first diode in the single-phase full-wave rectifier circuit (5) is forward-conducting, and the second diode is reverse-biased and cut off. The first auxiliary diode in the auxiliary diode assembly (8) is forward-conducting, and the second auxiliary diode is reverse-biased and cut off; at this time, the auxiliary single-phase transformer (4), the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) are all in normal working states, and the first double-secondary-winding transformer (6) and the second double-secondary-winding transformer (7) jointly supply power to the load (9); Wherein: is the voltage across the two ends of the secondary winding of the auxiliary single-phase transformer (4), is the voltage across the load (9), is the voltage output by the first diode rectifier bridge (2), is the voltage output by the second diode rectifier bridge (3), and are the voltages across the two ends of the two secondary windings of the first double-secondary-winding transformer (6) respectively, and are the voltages across the two ends of the two secondary windings of the second double-secondary-winding transformer (7) respectively.

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