36-pulse rectifier based on low-loss passive current injection pulse multiplication

Abstract

The invention discloses a 36-pulse rectifier based on low-loss passive current injection pulse multiplication, and relates to the technical field of transformers. The 36-pulse rectifier comprises a 12-pulse rectifier and a multiplication circuit. The multiplication circuit is located on the direct current side of the 12-pulse rectifier and used for multiplying the pulse waves into 36 pulse waves. The output end of the multiplication circuit is used for being connected with a load. The 12-pulse rectifier is configured with a positive output, a negative input, and a common output of a 36-pulse rectifier. The multiplication circuit comprises an auxiliary single-phase transformer, a first double-secondary-side winding transformer, a second double-secondary-side winding transformer, a single-phase full-wave rectification circuit and an auxiliary diode assembly. According to the voltage and current relation of the alternating current side and the direct current side, the number of pulse waves of a conventional series 12-pulse rectifier is multiplied into 36 pulse waves, and distortion of input current and output voltage of the rectifier is effectively restrained.

Description

Technical Field

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

[0002] The series 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 equipment to obtain energy from the power grid.

[0003] However, the input current of the series 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. In order to effectively suppress the input current harmonics of the series 12-pulse rectifier, the prior art has proposed a variety of solutions.

[0004] The first method is to increase the number of pulses of the rectifier 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 winding of the transformer becomes more complex. The complex winding structure may lead to an imbalance in the equivalent impedance of the transformer, which in turn leads to an imbalance in the system parameters and increases the content of non-main harmonics. In addition, there are limitations to the effect of reducing the THD of the input current by simply increasing the number of pulses. Therefore, the harmonic suppression effect is limited by relying solely on changing the structure of the phase-shifting transformer to increase the number of pulses of the rectifier system.

[0005] The second method 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, which is closer to a sine wave. However, it requires sampling the input voltage phase, load current and compensation injection current. The control circuit is complex and the number of pulses of the load output voltage cannot be increased. The third is to use the DC side hybrid harmonic suppression strategy, combined with the use of auxiliary circuits and active switching tubes, to control the conduction state of the current injection circuit, to harmonically modulate the voltage and current waveforms on the DC side, and to increase the number of steps of the waveform, thereby achieving the goal of increasing the number of rectifier pulses. This method optimizes the power quality on the DC side by precisely controlling the injection of current, while also improving rectification efficiency.

[0006] Based on the above analysis, setting an auxiliary circuit on the DC side of the 12-pulse rectifier to multiply the input three-phase current pulses can solve the problems of high harmonic content of the input current and distortion of the output voltage of the rectifier system. However, this pulse multiplication technology uses more parallel diodes in the structure, which leads to complex structure and increased additional losses. The auxiliary transformer occupies a large capacity, and the primary and secondary winding turns of the auxiliary transformer in the auxiliary circuit are relatively large, which will cause a large leakage inductance of the transformer and reduce the harmonic suppression effect. Summary of the invention

[0007] 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.

[0008] In order 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 and is used to multiply the pulse into 36 pulses. The output end of the multiplication circuit is used to connect a load. The 12-pulse rectifier is configured with a positive output end, a negative input end and a common output end of the 36-pulse rectifier.

[0009] 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 component.

[0010] 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, and the primary windings of the first double-secondary winding transformer and the second double-secondary winding transformer.

[0011] 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 rectifier, and a regulating tap connected to the negative input terminal of the 36-pulse rectifier.

[0012] 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.

[0013] 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 component and the secondary winding of the second double-secondary winding transformer.

[0014] The primary winding of the second double-secondary winding transformer is connected to the negative input terminal of the 36-pulse rectifier through a second capacitor.

[0015] 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 terminal of the 36-pulse rectifier.

[0016] The turns ratio 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 is constructed to enable the conduction time of the single-phase full-wave rectifier circuit and the auxiliary diode component to be 1 / 2 of the voltage cycle received by the AC input end.

[0017] In an optional implementation, the first capacitor and the second capacitor are of the same size.

[0018] In an optional embodiment, the cathode end of the primary winding of the auxiliary single-phase transformer is connected to the common output terminal. The anode end 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 connected to the cathode end of the primary winding of the first double-secondary winding transformer and the anode end circuit of the second double-secondary winding transformer.

[0019] The secondary winding of the auxiliary single-phase transformer is provided with a left tap, a right tap, and an adjusting tap. The left tap and the right tap are connected to the single-phase full-wave rectifier circuit, and the adjusting tap and the negative electrode of the second capacitor are connected to the negative input terminal of the 36-pulse rectifier.

[0020] In an optional embodiment, the auxiliary diode assembly includes a first auxiliary diode and the second auxiliary diode The first auxiliary diode and the second auxiliary diode The anode is connected to the common output terminal.

[0021] In an optional implementation, the anode terminal of the primary winding of the first double-secondary winding transformer is connected to the first capacitor The secondary winding of the first double-secondary winding transformer is provided with an upper winding and a lower winding. The anode terminal of the upper winding of the secondary winding of the first double-secondary winding transformer is connected to the negative terminal of the second auxiliary diode The cathode end of the upper winding of the secondary winding of the first double-secondary winding transformer is connected to the cathode end of the upper winding of the secondary winding of the second double-secondary winding transformer. The cathode end of the lower winding of the secondary winding of the first double-secondary winding transformer is connected to the cathode end of the first auxiliary diode. The anode terminal of the secondary winding of the first double-secondary winding transformer is connected to the anode terminal of the lower winding of the secondary winding of the second double-secondary winding transformer.

[0022] In an optional implementation, the cathode end of the primary winding of the second double-secondary winding transformer is connected to the second capacitor The positive electrode of the second double-secondary winding transformer is connected. The secondary winding of the second double-secondary winding transformer is provided with an upper winding and a lower winding. The anode end of the upper winding of the secondary winding of the second double-secondary winding transformer, the cathode end of the lower winding of the secondary winding of the second double-secondary winding transformer, and the first capacitor The positive poles of the loads are connected to the positive output terminals of the 36-pulse rectifiers, wherein the positive output terminals of the 36-pulse rectifiers are suitable for connecting to the positive input terminals of the loads.

[0023] In an optional embodiment, the single-phase full-wave rectifier circuit includes a first diode and the second diode The first diode The cathode of the second diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer. The cathode of the first diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer. The anode of the second diode The anodes are connected to the negative output terminal of the load.

[0024] 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 suitable for adjusting 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 consistent amplitudes, and then the two sets of voltages are respectively transmitted to the first and second diode rectifier bridges.

[0025] 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.

[0026] 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: the first auxiliary diode and the second auxiliary diode The second working mode of the reverse bias cut-off non-working state is: the first auxiliary diode Reverse bias cutoff, the second auxiliary diode The first power supply state is forward conduction; the third working mode is: the first auxiliary diode Forward conduction, the second auxiliary diode The second power supply state is reverse biased and cut off.

[0027] In an optional implementation manner, the first working mode is specifically: when , and When the first diode in the single-phase full-wave rectifier circuit and the second diode Forward conduction, the first auxiliary diode in the auxiliary diode assembly and the second auxiliary diode Reverse bias cutoff, flows through the first capacitor Current and the second capacitor Current The default value is 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.

[0028] In an optional implementation, the second working mode is: , and When the second diode in the single-phase full-wave rectifier circuit Forward conduction, the first diode Reverse bias cutoff, the second auxiliary diode in the auxiliary diode assembly Forward conduction, the first auxiliary diode At this time, the auxiliary single-phase transformer, the first double-secondary winding transformer and the second double-secondary winding transformer are all in normal working state, and the first double-secondary winding transformer and the second double-secondary winding transformer jointly supply power to the load.

[0029] In an optional implementation, the third working mode is: , and When the first diode in the single-phase full-wave rectifier circuit Forward conduction, the second diode Reverse bias cutoff, the first auxiliary diode in the auxiliary diode assembly Forward conduction, the second auxiliary diode At this time, the auxiliary single-phase transformer, the first double-secondary winding transformer and the second double-secondary winding transformer are all in normal working state, and the first double-secondary winding transformer and the second double-secondary winding transformer jointly supply power to the load.

[0030] in: 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 at both ends of the two secondary windings of the first double-secondary winding transformer, and are respectively the voltages at both ends of the two secondary windings of the second double-secondary winding transformer.

[0031] By adopting the above technical solution, the present invention can achieve the following technical effects: The 36-pulse rectifier based on the DC side low-loss passive current injection pulse multiplication of this embodiment does not need to increase the complexity of the phase-shifting transformer, and the number of diodes used is also reduced. In each working state, the DC side low-loss passive current injection pulse multiplication circuit has only two diodes in the working state, and the auxiliary diode and It is connected in parallel with the DC bus and the positive input terminal of the load, but not directly connected to the load, which greatly reduces the conduction loss of the diode. The primary and secondary winding turns ratio of the auxiliary single-phase transformer is small, which reduces the leakage inductance. The power capacity of the auxiliary single-phase transformer occupies a small system capacity and is easy to manufacture, thereby achieving the effect of reducing the input current harmonics and output voltage pulsation of the 36-pulse rectifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the specific embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 It is a structural diagram of a 36-pulse rectifier.

[0034] Figure 2 It is a schematic diagram of the phase-shifting transformer structure.

[0035] Figure 3 It is a structural diagram of the auxiliary single-phase transformer.

[0036] Figure 4 It is a structural diagram of a double secondary winding transformer.

[0037] Figure 5 is a schematic diagram of a 36-pulse rectifier in a first operating mode.

[0038] Figure 6 is a schematic diagram of a 36-pulse rectifier in the second working mode.

[0039] Figure 7 is a schematic diagram of a 36-pulse rectifier in the third operating mode.

[0040] Figure 8 is the input current , and Waveform graph.

[0041] Fig. 9 is the input current Fourier analysis diagram of .

[0042] 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. DETAILED DESCRIPTION

[0043] In order to make the purpose, 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 drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] like Figures 1 to 9 As shown, an 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 into 36 pulses. Among them, the output end of the low-loss passive current injection pulse multiplication circuit is used to connect a 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 terminal, a negative input terminal, and a DC-side bus common output terminal K. The 36-pulse rectifier can meet the industrial application standard of IEEE-519 for harmonic content in high-power occasions such as industrial metallurgy and industrial hydrogen production.

[0045] The series-connected 12-pulse rectifier comprises a phase-shifting transformer 1, a first diode rectifier bridge 2 and a second diode rectifier bridge 3. The phase-shifting transformer 1 is used 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 consistent amplitude, and then transmit the two sets of voltages to the first and second diode rectifier bridges 3 respectively.

[0046] The structure of the phase-shifting transformer 1 in this embodiment is as follows Figure 2 As shown. The input end of the phase-shifting transformer 1 is used to input a three-phase AC power supply. The output end of the phase-shifting transformer 1 is electrically connected to the first diode rectifier bridge 2 and the second diode rectifier bridge 3 respectively, so as to generate two three-phase voltages with a phase difference of 30° and the same amplitude. Among them, the input current on the AC side is respectively , , . , , The waveform diagram is as follows Figure 8 shown. The Fourier spectrum diagram of the waveform is as follows Fig. 9 shown.

[0047] 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, and is configured as the common output terminal K of the DC side bus of the 36-pulse rectifier.

[0048] 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 component 8, and a first capacitor of equal size. and the second capacitor The auxiliary diode assembly 8 includes a first auxiliary diode and the second auxiliary diode The first auxiliary diode and the second auxiliary diode The anode of the power supply is connected to a DC bus bar, which is a line directly electrically connected to the common output terminal.

[0049] One end of the primary winding of the auxiliary single-phase transformer 4 is connected to the common output terminal, and 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 and a right tap connected to the single-phase full-wave rectifier, and a regulating tap connected to the negative input terminal of the 36-pulse rectifier.

[0050] Specifically, the cathode 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 anode 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 anode end of the primary winding of the auxiliary single-phase transformer 4 is electrically connected to the cathode end of the primary winding of the first double-secondary winding transformer 6 and the anode 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 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 terminal of the 36-pulse rectifier.

[0051] The primary winding of the first double-secondary winding transformer 6 is connected to the positive output terminal of the 36-pulse rectifier through the 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 component 8 and the secondary winding of the second double-secondary winding transformer 7.

[0052] Specifically, the anode terminal of the primary winding of the first double-secondary winding transformer 6 is connected to 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 anode terminal of the upper winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the negative terminal of the second auxiliary diode. The cathode end of the upper winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the cathode end of the upper winding of the secondary winding of the second double-secondary winding transformer 7. The cathode end of the lower winding of the secondary winding of the first double-secondary winding transformer 6 is connected to the cathode end of the first auxiliary diode The anode terminal of the secondary winding of the first double-secondary winding transformer 6 is connected to the anode terminal of the lower winding of the secondary winding of the second double-secondary winding transformer 7.

[0053] 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.

[0054] Specifically, the cathode end of the primary winding of the second double-secondary winding transformer 7 and 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 anode end of the upper winding of the secondary winding of the second double-secondary winding transformer 7, the cathode end of the lower winding of the secondary winding of the second double-secondary winding transformer 7, and the first capacitor The positive poles of the load 9 are connected to the positive output terminal of the 36-pulse rectifier. The positive output terminal of the 36-pulse rectifier is suitable for connecting to the positive input terminal of the load 9.

[0055] Based on the above embodiments, in an optional embodiment of the present invention, as Figure 1 As shown, the single-phase full-wave rectifier circuit 5 includes a first diode and the second diode The first diode The cathode of the second diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer 4. The cathode of the first diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer 4. The anode of the second diode The anodes of the single-phase full-wave rectifier circuit 5 are 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 connected to the negative output terminal of the load 9.

[0056] 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 component 8 is made 1 / 2 of the voltage cycle received by the two AC input ends of the single-phase full-wave rectifier circuit 5 and the auxiliary diode component 8, and the injected current =0 and =0 is the grid-side input current , , One twelfth of the power frequency cycle. It should be noted that the more pulses there are, the closer they are to the ideal sine wave, reducing the input current. , , The harmonic distortion of It is the current input into the cathode end of the primary winding of the auxiliary single-phase transformer 4. is the current input to the common terminal M.

[0057] Specifically, the turns ratio of the primary and secondary windings of the auxiliary single-phase transformer 4 is set , the turns ratio of the primary and secondary windings of the first transformer with double secondary windings , the turns ratio of the primary and secondary windings of the second transformer with double secondary windings , so that 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 ends of the single-phase full-wave rectifier circuit 5 and the auxiliary diode assembly 8, and the injected current =0 and =0 is the grid-side input current , , One twelfth of the power frequency period.

[0058] The above circuit structure can be understood as using two isolation transformers as phase-shifting transformers 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 large amplitudes can be basically eliminated, thereby reducing harmonic pollution. The input current on the AC side 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 primary-to-secondary winding turns ratio of the auxiliary single-phase transformer 4 is small, the diode conduction loss is low, and it has high reliability and harmonic suppression performance.

[0059] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication of the embodiment of the present invention adopts all-passive devices. It has a simple structure, low cost, high operational reliability and low maintenance cost. The two large capacitors on the DC output side have the functions of reducing DC voltage ripple, improving power factor, improving power quality, reducing electromagnetic interference, improving system stability, reducing harmonic suppression cost, and improving the input power factor of the rectifier and reducing the harmonic content of the input current. Preferably, the primary and secondary turns ratios of the first double-secondary winding transformer 6 and the second double-secondary winding transformer 7 are consistent, which balances the current of the input capacitor, so that the output voltage of the rectifier remains constant during steady-state operation.

[0060] Based on the above embodiment, in an optional embodiment of the present invention, the 36-pulse rectifier is configured to have a first working mode, a second working mode and a third working mode. The first working mode is: the first auxiliary diode and the second auxiliary diode The second working mode of the reverse bias cut-off non-working state is: the first auxiliary diode Reverse bias cutoff, the second auxiliary diode The first power supply state is forward conduction. The third working mode is: the first auxiliary diode Forward conduction, the second auxiliary diode The second power supply state is reverse biased and cut off.

[0061] Preferably, Figure 5 As shown, the first working mode is specifically: when , and When the first diode in the single-phase full-wave rectifier circuit 5 and the second diode Forward conduction, the first auxiliary diode in the auxiliary diode assembly 8 and the second auxiliary diode Reverse bias cutoff, flows through the first capacitor Current and the second capacitor Current The default value is 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.

[0062] Preferably, Figure 6 As shown, the second working mode is: when , and When the second diode in the single-phase full-wave rectifier circuit 5 Forward conduction, the first diode The second auxiliary diode in the auxiliary diode assembly 8 is reverse biased and cut off. Forward conduction, the first auxiliary diode 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 state, and the first double-secondary winding transformer 6 and the second double-secondary winding transformer 7 jointly supply power to the load 9 .

[0063] Preferably, Figure 7 As shown, the third working mode is: when , and When the first diode in the single-phase full-wave rectifier circuit 5 Forward conduction, the second diode The first auxiliary diode in the auxiliary diode assembly 8 is reverse biased and cut off. Forward conduction, the second auxiliary diode 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 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] in: 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 at both ends of the two secondary windings of the first double-secondary winding transformer 6, and They are respectively the voltages at both ends of the two secondary windings of the second double-secondary winding transformer 7.

[0065] The 36-pulse rectifier based on low-loss passive current injection pulse multiplication on the DC side of the embodiment of the present invention comprises 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, and the circuit formed by this circuit modulates the input and output currents of the rectifier bridge into a three-level step wave, so that the 12-pulse rectifier is multiplied to 36 pulses.

[0066] The 36-pulse rectifier of the embodiment of the present invention uses a double-tapped auxiliary single-phase transformer 4 and two transformers with dual secondary windings, simplifying the circuit structure of the existing pulse multiplication technology with auxiliary circuits. The primary winding of the auxiliary single transformer is directly connected in series to the DC bus, reducing the voltage level and conduction loss. The secondary winding of the first transformer with dual secondary windings and the second transformer with dual secondary windings are connected in parallel between the DC bus and the positive input terminal of the load 9, and are not directly connected to the circuit on the load 9 side, reducing the loss of the auxiliary diode.

[0067] In each working state, only two diodes are working, which greatly reduces the conduction loss of the auxiliary diodes, and the auxiliary single-phase transformer 4 occupies a small capacity. In addition, the primary-secondary turns ratio of the three transformers is small, the leakage inductance is small, and the harmonic suppression effect is effectively improved. According to the voltage-current relationship on the AC and DC sides, the pulse number of the conventional series-type 12-pulse rectifier is multiplied to 36 pulses, which effectively suppresses the distortion of the input current and output voltage of the rectifier.

[0068] The 36-pulse rectifier based on the DC side low-loss passive current injection pulse multiplication of this embodiment does not need to increase the complexity of the phase-shifting transformer 1, and the number of diodes used is also reduced. In each working state, the DC side low-loss passive current injection pulse multiplication circuit has only two diodes in the working state, and the auxiliary diode and It is connected in parallel with the DC bus and the positive input terminal of the load 9, but not directly connected to the load 9, which greatly reduces the conduction loss of the diode. The primary-to-secondary winding turns ratio of the auxiliary single-phase transformer 4 is small, which reduces the leakage inductance. The power capacity of the auxiliary single-phase transformer 4 occupies a small system capacity, which is convenient for manufacturing, thereby achieving the effect of reducing the input current harmonics and output voltage pulsation of the 36-pulse rectifier.

[0069] The rectifier of the present invention is a voltage source type multi-pulse rectifier based on a DC side passive auxiliary circuit. It does not need to connect three large inductors in series on the input side, nor does it need to use active switching devices or complex control circuits. It also avoids the problems of factor reduction and output characteristic softening caused by series inductance. When the second and third transformers with double secondary windings are damaged or non-operating, the entire circuit can still rely on the auxiliary single-phase transformer 4 and the single-phase full-wave rectifier circuit 5 to operate normally in a 36-pulse state. The present invention has great advantages in harmonic control, efficiency, reliability, and reduction of power grid pollution.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in 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 comprises a 12-pulse rectifier and a multiplier circuit; the multiplier circuit is located on the DC side of the 12-pulse rectifier and is used to multiply the pulse into 36 pulses; wherein the output end of the multiplier circuit is used to connect a load (9); the 12-pulse rectifier is constructed with a positive output end, a negative input end and a common output end of a 36-pulse rectifier; The multiplication circuit comprises 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, and 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 and a right tap connected to the single-phase full-wave rectifier, and a regulating 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 via 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 component (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 terminal of the 36-pulse rectifier via 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 ratios 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) are constructed so as to enable the conduction time of the single-phase full-wave rectifier circuit (5) and the auxiliary diode component (8) to be 1 / 2 of the voltage cycle received by the AC input end.

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 have 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 adjusting tap; the left tap and the right tap are connected to the single-phase full-wave rectifier circuit (5), and the adjusting tap and the negative electrode of the second capacitor are connected to the negative input terminal of the 36-pulse rectifier.

3. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 1, characterized in that: The auxiliary diode assembly (8) comprises a first auxiliary diode and the second auxiliary diode The first auxiliary diode and the second auxiliary diode The anode is connected to the common output terminal; The anode terminal of the primary winding of the first double-secondary winding transformer (6) and the first capacitor The negative terminal is connected; The secondary winding of the first double-secondary winding transformer (6) is provided with an upper winding and a lower winding; the anode end of the upper winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the second auxiliary diode The cathode end of the upper winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the cathode end of the upper winding of the secondary winding of the second double-secondary winding transformer (7); the cathode end of the lower winding of the secondary winding of the first double-secondary winding transformer (6) is connected to the cathode end of the first auxiliary diode The cathode of the first double-secondary winding transformer (6) is connected; the anode end of the secondary winding of the first double-secondary winding transformer (6) is connected to the anode 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, characterized in that: The cathode end of the primary winding of the second double-secondary winding transformer (7) and the second capacitor The positive pole is connected; The secondary winding of the second double-secondary winding transformer (7) is provided with an upper winding and a lower winding; an anode end of the upper winding of the secondary winding of the second double-secondary winding transformer (7), a cathode end of the lower winding of the secondary winding of the second double-secondary winding transformer (7), and a first capacitor The positive poles of the load (9) are connected to the positive output terminal of the 36-pulse rectifier; wherein the positive output terminal of the 36-pulse rectifier is suitable for connecting 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) comprises a first diode and the second diode The first diode The cathode of the second diode is connected to the left tap of the secondary winding of the auxiliary single-phase transformer (4); The cathode of the diode is connected to the right tap of the secondary winding of the auxiliary single-phase transformer (4); The anode of the second diode The anodes are 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 comprises a phase-shifting transformer (1), a first diode rectifier bridge (2) and a second diode rectifier bridge (3); the phase-shifting transformer (1) is suitable for adjusting the three-phase voltage input from the power grid so as to generate two sets of three-phase voltage signals with a phase difference of 30° and consistent amplitudes, and then the two sets of voltages are respectively transmitted to the first and second diode rectifier bridges (3); 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) and is configured as the common output end 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 36-pulse rectifier is configured to have a first operating mode, a second operating mode and a third operating mode; The first working mode is: the first auxiliary diode and the second auxiliary diode Non-working state of reverse bias cutoff; The second working mode is: the first auxiliary diode Reverse bias cutoff, the second auxiliary diode A first power supply state of forward conduction; The third working mode is: the first auxiliary diode Forward conduction, the second auxiliary diode The second power supply state is reverse biased and cut off.

8. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 7, characterized in that: The first working mode is specifically: when , and When the first diode in the single-phase full-wave rectifier circuit (5) and the second diode Forward conduction, the first auxiliary diode in the auxiliary diode assembly (8) and the second auxiliary diode Reverse bias cutoff, flows through the first capacitor Current and the second capacitor Current The default value is 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-working state; in: 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 respectively the voltages at both ends of the two secondary windings of the first double-secondary winding transformer (6), and They are respectively the voltages at both ends of the two secondary windings of the second double-secondary winding transformer (7).

9. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 7, characterized in that: The second working mode is: when , and When the second diode in the single-phase full-wave rectifier circuit (5) Forward conduction, the first diode The second auxiliary diode in the auxiliary diode assembly (8) is reverse biased and cut-off. Forward conduction, the first auxiliary diode Reverse bias is 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 a normal working state, and the first double-secondary winding transformer (6) and the second double-secondary winding transformer (7) jointly supply power to the load (9); in: 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 respectively the voltages at both ends of the two secondary windings of the first double-secondary winding transformer (6), and They are respectively the voltages at both ends of the two secondary windings of the second double-secondary winding transformer (7).

10. The 36-pulse rectifier based on low-loss passive current injection pulse multiplication according to claim 7, characterized in that: The third working mode is: when , and When the first diode in the single-phase full-wave rectifier circuit (5) Forward conduction, the second diode Reverse bias cutoff, the first auxiliary diode in the auxiliary diode assembly (8) Forward conduction, the second auxiliary diode Reverse bias is 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 a normal working state, and the first double-secondary winding transformer (6) and the second double-secondary winding transformer (7) jointly supply power to the load (9); in: 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 respectively the voltages at both ends of the two secondary windings of the first double-secondary winding transformer (6), and They are respectively the voltages at both ends of the two secondary windings of the second double-secondary winding transformer (7).

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