Power supply circuits and their applications

Abstract

This invention discloses a power supply circuit and its application, which uses the electromagnetic induction relationship between conductive winding coils on a conductive iron core to generate a multi-phase AC power supply from a given AC power supply, and directly outputs DC voltage and current as a DC voltage source with a low ripple rate through a multi-phase bridge rectifier circuit without capacitor filtering, thereby fundamentally eliminating high-order harmonics caused by capacitor filtering. In addition, the current of the multi-phase bridge rectifier circuit input from the power grid is a sine wave or a step wave very close to a sine wave, so that high-order harmonics generated on the AC side are reduced to a minimum without power factor calibration.

Description

[Technical field]

[0001] The present invention relates to the field of power supply technology, and in particular to a power supply circuit and its applications. [Background technology]

[0002] The current power grid provides AC electricity to thousands of homes, but the electrical equipment we commonly use, such as lighting, televisions, electric audio, and computers, all require DC electricity. Furthermore, power-driven devices that require speed adjustment (such as elevators, electric vehicles, high-speed trains, precision machine tools, etc.) and devices that require precise control all require DC electricity, and in all cases the AC electricity must first be converted to DC electricity on the device side before it can be used.

[0003] In order to convert AC electricity to DC electricity, the equipment needs to perform rectification and capacitor filtering. The pulsating DC voltage obtained after rectification can be filtered to become a stable DC voltage. When capacitor filtering is used, the AC current becomes a pulsed current, and many high-order harmonics appear, which require further removal by power factor calibration to meet the high-order harmonics provisions in the relevant standards (National Standard GB 17625.1-2012 of the People's Republic of China / IEC 61000-3-2:2009: Electromagnetic Compatibility Limit Values ​​Harmonic Current Transmission Limit Values ​​(Equipment Phase Input Current ≦ 16A)). This national standard is a compulsory standard, and any products that do not meet the compulsory standard are prohibited from being produced, sold, or imported. Therefore, if it is an electrical equipment, it is necessary to consider whether it is necessary to remove high-order harmonics by power factor calibration.

[0004] However, power factor calibration is very complicated and adds significant cost to the DC power supply, especially for high power supplies. Summary of the Invention

[0005] In view of the above, the present invention provides a power supply circuit and its application. A multi-phase AC power supply is generated from a given AC power supply by utilizing the electromagnetic induction relationship between conductive winding coils in a conductive iron core, and then the multi-phase bridge rectifier circuit passes through the multi-phase bridge rectifier circuit and directly outputs DC voltage and current as a DC voltage source with a low ripple rate without performing capacitor filtering. This fundamentally eliminates high-order harmonics caused by capacitor filtering. In addition, the current of the multi-phase bridge rectifier circuit input from the power grid is a sine wave or a step wave very close to a sine wave, so that the high-order harmonics generated on the AC side are reduced to a minimum without performing power factor calibration.

[0006] In one aspect, the present invention provides a power supply circuit that utilizes the electromagnetic induction relationship between conductive winding coils on a conductive iron core to generate n-phase AC power from a given AC power source, and then passes through an n-phase bridge rectifier circuit to directly output DC voltage and current as a DC voltage source with a low ripple rate without capacitor filtering, where n is an odd number equal to or greater than 5.

[0007] The n-phase AC power source is a source of n sinusoidal voltages, each having the same amplitude and initial phases uniformly distributed at intervals of 360° / n.

[0008] The n-phase bridge rectifier circuit is composed of n sets of two rectifier diodes connected in series, and in each of the n sets of two rectifier diodes connected in series, the cathode of one diode is connected to the anode of the other diode. Each of the connection points is connected to an n-phase output end of the n-phase AC power source. The other cathodes of all of the n sets of two rectifier diodes connected in series are connected to form an output positive electrode of the n-phase bridge rectifier circuit. The other anodes of all of the n sets of two rectifier diodes connected in series are connected to form an output negative electrode of the n-phase bridge rectifier circuit.

[0009] As with any one of the above-mentioned aspects and possible implementations, a further implementation is provided, where n may be an odd number greater than or equal to 7.

[0010] As an embodiment of the present invention, a 3m-phase AC power supply may be used, which is generated by inducing a rotating magnetic field in a stator winding of a three-phase AC motor, and outputs DC voltage and current through a 3m-phase bridge rectifier circuit, where m is an odd number equal to or greater than 3, and 3m=n.

[0011] As with any one of the above-mentioned aspects and possible implementations, a further implementation is provided: where m may be an odd number greater than or equal to 5.

[0012] As described above, in accordance with any one of the possible implementations, a further implementation is provided. During operation of a single-phase AC asynchronous motor, a rotating magnetic field is induced in a stator winding to generate an n-phase AC power source, which may be used to output DC voltage and current via an n-phase bridge rectifier circuit.

[0013] As with any one of the above-mentioned aspects and possible implementations, a further implementation is provided, where n may be an odd number greater than or equal to 7.

[0014] As described above, in accordance with any one of the possible implementations of the aspects, the present invention further provides an implementation, in which the n-phase AC power source is a 3h-phase AC power source, which is composed of 3h sets of different winding combinations of a secondary winding of a three-phase AC transformer, and the 3h AC voltage sources output thereby may output DC voltages and currents through a 3h-phase bridge rectifier circuit, where h is an odd number equal to or greater than 3.

[0015] As with any one of the above-described aspects and possible implementations, a further implementation is provided in which h may be an odd number greater than or equal to 5.

[0016] In addition to the above-mentioned aspects and any one of the possible implementations, the present invention provides a further implementation, in which the 3h sets of different winding combinations of the secondary winding of the three-phase AC transformer adopt a star-connection manner, specifically, one end of each of the 3h winding combinations is connected to one point, and the other end is an output end of a 3h-phase AC power source, and a DC voltage and current are output through a 3h-phase bridge rectifier circuit.

[0017] As described above, in accordance with any one of the possible implementations of the aspects and the three-phase AC transformer, the 3h sets of different winding combinations of the secondary winding are connected in a polygonal connection manner, specifically, the 3h sets of winding combinations are connected in sequence to the beginning and end, and the end of the last set is connected to the beginning of the first set to form a closed loop, to obtain 3h connection points, which are output terminals of a 3h-phase AC power source, and may further output DC voltage and current through a 3h-phase bridge rectifier circuit.

[0018] In another aspect, the present invention provides an application of any one of the above power supply circuits, which is applied to a product end and is connected to an AC electrical input end as the whole or part of the product power supply.

[0019] Compared with the prior art, the advantages or beneficial effects of one of the above technical solutions are as follows: The rectifier circuit of the present invention can rectify multi-phase AC electricity and obtain a stable DC voltage without filtering.

[0020] Another advantage or beneficial effect of the above technical solutions is as follows: The rectifier circuit of the present invention eliminates the filtering step, and fundamentally eliminates many high-order harmonics caused by filtering. There is no need to consider the elimination of high-order harmonics in electrical equipment, and the power factor calibration step is eliminated, simplifying the design and production costs of electrical equipment.

[0021] The merit or beneficial effect of another measure in the above technical solutions is as follows: The rectifier circuit of the present invention can be applied to the power supply end or the intermediate end of the power supply path, allowing the power grid to supply power to each home in the form of DC, and facilitating the connection between the user's DC equipment and the power source. [Brief description of the drawings]

[0022] In order to make the technical solution of the present invention clearer, the following briefly introduces the drawings used. The following drawings are part of the embodiments of the present invention, and it is obvious for those skilled in the art that they can obtain other drawings based on these drawings without any creative effort. [Figure 1] FIG. 1 is a block diagram of a multi-phase bridge rectifier circuit according to one embodiment of the present invention, in which a star-connection method is adopted between combinations of secondary windings of n three-phase AC transformers. [Diagram 2] FIG. 2 is a voltage waveform diagram of a nine-phase AC power supply according to one embodiment of the present invention. [Diagram 3] FIG. 2 is a waveform diagram of an output DC voltage after rectification of a nine-phase bridge rectifier circuit according to one embodiment of the present invention. [Figure 4] FIG. 11 is a diagram showing the relationship between step wave magnetomotive forces W·I on the primary and secondary sides in a three-phase transformer core when a nine-phase AC power supply formed by a combination of three-phase transformer secondary windings according to one embodiment of the present invention is connected to a nine-phase bridge rectifier circuit. [Diagram 5] FIG. 2 is a diagram of a multi-phase bridge rectifier circuit of a nine-phase AC power supply obtained by adopting a polygonal connection method between the secondary winding combinations of a three-phase AC transformer according to one embodiment of the present invention. [Figure 6] This figure shows the relationship between the exterior angles of a regular polygon (regular nonagon) and the central angle of a circumscribed circle according to one embodiment of the present invention. It corresponds to the fact that a nine-phase AC power supply can be obtained whether the secondary windings of the same three-phase AC transformer are connected using the polygonal connection method or the star connection method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] In the following, specific embodiments will be described by taking as an example a nine-phase bridge rectifier circuit of a nine-phase AC power supply obtained by utilizing a secondary winding of a three-phase transformer.

[0024] A block diagram of a nine-phase bridge rectifier circuit is shown in Figure 1, where n=9.

[0025] Here, the secondary windings of all three-phase AC transformers have five different numbers of turns, and the ratio of the numbers of turns to each other is as follows: N1:N2:N3:N4:N5=Sin90°:Sin50°:Sin10°:Sin30°:Sin70°.

[0026] By adding positive and negative polarities to these five types of windings, and connecting them in series in groups of three, we can construct the nine types of transformer secondary winding combinations required. They are as follows: Transformer secondary winding combination 1: Phase A N1, Phase B N4, Phase C N4, Transformer secondary winding combination 2: Phase A - N2 turns, Phase B - N3 turns, Phase C - N5 turns, Transformer secondary winding combination 3: Phase A - N3 turns, Phase B - N2 turns, Phase C - N5 turns, Transformer secondary winding combination 4: Phase A-N4, Phase B-N1, Phase C-N4, Transformer secondary winding combination 5: Phase A - N5 turns, Phase B - N2 turns, Phase C - N3 turns, Transformer secondary winding combination 6: Phase A - N5 turns, Phase B - N3 turns, Phase C - N2 turns, Transformer secondary winding combination 7: Phase A-N4, Phase B-N4, Phase C-N1, Transformer secondary winding combination 8: Phase A N3 turns, Phase B N5 turns, Phase C N2 turns, Transformer secondary winding combination 9: Phase A - N2 turns, Phase B - N5 turns, Phase C - N3 turns.

[0027] Figure 1 shows a combination of n windings connected by star connection. When the N-phase AC power supply is input to an N-phase rectifier bridge consisting of 2N rectifier diodes of the present invention, a pulsating DC voltage with a low ripple factor can be obtained without a filter capacitor. As can be seen from Figure 3, the ripple factor in Figure 4 is clearly reduced compared to the ripple factor of conventional three-phase rectification.

[0028] As we all know, the rate of change of the extreme values ​​of a continuously differentiable function is 0. To be more specific, the change in the value of the sine function at its maximum and minimum values ​​is very small, and its absolute value is close to 1. For example, Sin80°=Sin100°=0.98481.

[0029] Taking a 9-phase bridge rectifier circuit as an example, since Sin80°=Sin100°=0.984819, the output DC ripple voltage at this time varies between extreme values ​​of 0.984819, and the ripple factor is less than 1%. With such a low ripple factor, filtering is not necessary. Also, when n=15, Sin84°=0.99452, so the ripple factor is less than 0.3%, and filtering is not necessary.

[0030] This nine-phase AC power supply can be obtained by combining the secondary windings of a three-phase AC transformer. By JPEG2025503218000002.jpg6182, Because JPEG2025503218000003.jpg882, therefore, JPEG2025503218000004.jpg1382

[0031] moreover, As shown in JPEG2025503218000005.jpg1382, the three secondary windings of a three-phase transformer belong to three phases, and the voltages at the windings with a given ratio of turns are added together to obtain an arbitrary initial phase. You can get the sine value of JPEG2025503218000006.jpg1011.

[0032] JPEG2025503218000007.jpg626 (where N is an integer greater than 5, n=0,1,2,……N-1) to get N sine quantities JPEG2025503218000008.jpg624.

[0033] JPEG2025503218000009.jpg1082, where n=0, 1, 2, …N-1.

[0034] This is a so-called n-phase AC power source, which is a source of n sinusoidal voltages that are equal in amplitude and have initial phases spaced apart by 360° / n in sequence and are uniformly distributed.

[0035] From the above, we can conclude that the secondary winding of a three-phase AC transformer can be used to obtain the N-phase AC power supply required for multi-phase bridge rectification.

[0036] In particular, when N = 3·3 = 9, the secondary winding of a three-phase transformer can be configured to provide a nine-phase AC power supply by using nine sets of windings (three windings in each set).

[0037] All of the secondary windings of this three-phase AC transformer have five different numbers of turns, and the ratio of the numbers of turns is N1:N2:N3:N4:N5 = Sin90°:Sin50°:Sin10°:Sin30°:Sin70°.

[0038] Based on this ratio of the number of turns and the positive and negative winding polarity, it is possible to ensure that a nine-phase AC power supply is formed by nine sets of windings (three windings in each set), and at the same time, it is ensured that when DC current is output, three step wave currents that approximate sine waves with a phase difference of 120° are induced in the three primary windings of the transformer.

[0039] When looking at a polyphase AC power supply from the rectifier bridge side, we can see the following:

[0040] The current flowing out from the DC positive pole flows out from the phase with the highest voltage of the AC power supply, and the instantaneous value of the three-phase voltage on the secondary side at this time is proportionally induced in the three windings, and the sum of these three voltages is exactly the voltage value of the AC power supply of the phase with the highest voltage. The situation at the DC negative output terminal is completely similar, and the current flowing from the DC negative pole flows into the phase with the most negative voltage of the AC power supply. The instantaneous value of the three-phase voltage on the secondary side at this time is proportionally induced in the three windings, and the sum of these three voltages is exactly the voltage value of the AC power supply of the phase with the most negative voltage. At this time, the same current flows through both combinations of windings in these two sets (three in each set), but the number of turns (including positive and negative polarity) of the three windings are different. Furthermore, as the nine winding combinations conduct electricity in sequence, the number of turns and polarity of the three windings through which current flows also change in sequence. As a result, the product of the number of turns of the conducting windings and the DC current generates step magnetomotive forces in the three iron cores of the transformer that approximate three sine waves.

[0041] Figure 4 shows the approximate relationship between the step wave magnetomotive forces W·I on the primary and secondary sides of a three-phase transformer core (taking one phase with an initial phase of 0 as an example). In the figure, the current flowing from one phase with the highest voltage of the AC power supply generates a magnetomotive force W in the secondary winding of the transformer. 二次· I 出 The magnetomotive force generated in the secondary winding of the transformer by the current flowing from the phase where the voltage of the AC power supply is the most negative is W 二次· I 入 , and the magnetomotive force generated by the current induced in the transformer primary winding is W 一次· I 一次 This indicates that.

[0042] The relationship between the three is W 一次· I 一次 =W 二次· I 出 +W 二次· I 入 It is.

[0043] The nine different combinations of the secondary windings of the three-phase AC transformer may adopt a star connection method or a polygonal connection method. Since the exterior angle of a regular polygon is equal to the central angle of the inscribed circle, whether the star connection method or the polygonal connection method is adopted, each nine-phase AC voltage power source can be obtained from the nine different combinations of the secondary windings of the same three-phase AC transformer. However, the voltage amplitudes of the two methods are different, and the voltage amplitude ratio of the two methods is as follows:

[0044] Voltage amplitude for polygonal connection: Voltage amplitude for star connection = 1:2·Sin20°.

[0045] In addition, the rotating magnetic field generated by the stator winding of a three-phase AC motor is used to induce a 3h-phase (where h is an odd number greater than or equal to 3) AC power supply in the stator winding, which is then passed through a 3h-phase bridge rectifier circuit to output DC voltage and current.

[0046] When a three-phase AC motor is connected to a three-phase AC power source, its stator winding generates a rotating magnetic field in the iron core. If this rotating magnetic field cuts the coils that are uniformly distributed in the stator core slots in sequence, we can obtain the 3h-phase (where h is an odd number greater than or equal to 3) AC power source that we require.

[0047] Also, when a single-phase AC asynchronous motor is in operation, an n-phase AC power supply (where n is an odd number equal to or greater than 5) is induced in the stator winding by the rotating magnetic field, and DC voltage and current are output through an n-phase bridge rectifier circuit. This is the case when only a single-phase AC power supply exists, and no three-phase AC power supply exists, and it is necessary to generate an n-phase AC power supply from the single-phase AC power supply.

[0048] The alternating magnetic field generated by the stator coil of a single-phase AC asynchronous motor, which has a constant direction, can be decomposed into two rotating magnetic fields of equal magnitude and opposite direction. When a single-phase AC asynchronous motor is in operation, the magnetic field generated by the induced current in the rotor coil can cancel the magnetic field rotating in the opposite direction, and finally combines with the stator coil to form a rotating magnetic field. When this rotating magnetic field cuts the coils uniformly distributed in the stator core groove in sequence, we can obtain the n-phase (where n is an odd number greater than or equal to 5) AC power supply we need.

[0049] Figure 5 shows the nine winding combinations connected in a polygonal connection. The ratio of the number of turns of the three windings inside the nine winding combinations is the same as that of the star connection, but the number of turns should be compressed as (2·Sin20°:1).

[0050] It is clear that the above-described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative labor are within the scope of protection of the present invention.

Claims

1. A power supply circuit, which utilizes an electromagnetic induction relationship between conductive winding coils in a conductive iron core to generate an n-phase AC power supply from a predetermined AC power supply, and after passing through an n-phase bridge rectifier circuit, directly outputs a DC voltage and current as a DC voltage source with a low ripple factor, where n is an odd number equal to or greater than 5; The n-phase AC power source is a sinusoidal voltage source having n sinusoidal voltages, each having the same amplitude and an initial phase that is uniformly distributed at intervals of 360° / n in sequence; The n-phase bridge rectifier circuit is composed of n sets of two rectifier diodes connected in series, and in each of the n sets of two rectifier diodes connected in series, the cathode of one diode is connected to the anode of the other diode, and each connection point is connected to an n-phase output end of the n-phase AC power supply, and the other cathode of all of the n sets of two rectifier diodes connected in series is connected as an output positive electrode of the n-phase bridge rectifier circuit, and the other anode of all of the n sets of two rectifier diodes connected in series is connected as an output negative electrode of the n-phase bridge rectifier circuit.

2. 2. The power supply circuit according to claim 1, wherein n is an odd number equal to or greater than seven.

3. 2. The power supply circuit according to claim 1, wherein a 3m-phase AC power supply is generated by inducing a rotating magnetic field in a stator winding of a three-phase AC motor, and outputs DC voltage and current through a 3m-phase bridge rectifier circuit, where m is an odd number equal to or greater than 3, and 3m=n.

4. 4. The power supply circuit according to claim 3, wherein m is an odd number equal to or greater than five.

5. 2. The power supply circuit according to claim 1, wherein, during operation of the single-phase AC asynchronous motor, an n-phase AC power supply generated by a rotating magnetic field being induced in a stator winding is utilized, and DC voltage and current are outputted through an n-phase bridge rectifier circuit.

6. 6. The power supply circuit according to claim 5, wherein n is an odd number equal to or greater than seven.

7. 2. The power supply circuit according to claim 1, wherein the n-phase AC power supply is a 3h-phase AC power supply, which is formed by a combination of 3h sets of different windings of a secondary winding of a three-phase AC transformer, and the 3h AC voltage sources output thereby output DC voltages and currents through a 3h-phase bridge rectifier circuit, where h is an odd number equal to or greater than 3.

8. 8. The power supply circuit according to claim 7, wherein the 3h sets of different winding combinations of the secondary winding of the three-phase AC transformer adopt a star-connection manner, specifically, one end of each of the 3h winding combinations is connected together at one point, and the other end is an output end of a 3h-phase AC power supply, and outputs DC voltage and current through a 3h-phase bridge rectifier circuit.

9. 8. The power supply circuit according to claim 7, wherein the 3h sets of different winding combinations of the secondary winding of the three-phase AC transformer adopt a polygonal connection manner, and specifically, the 3h winding combinations are connected in sequence by their beginning and end, and the end of the last set is connected to the beginning of the first set to form a closed loop, thereby obtaining 3h connection points, which are output ends of a 3h-phase AC power supply, and output DC voltage and current through a 3h-phase bridge rectifier circuit.

10. The application of the power supply circuit according to any one of claims 1 to 9, characterized in that the power supply circuit is applied to a product end and connected to an AC electrical input end as the whole or part of the product power supply.

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