Power circuit

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] This invention relates to the field of power supply technology, and more particularly to power supply circuits and their applications. [Background technology]

[0002] While the current power grid provides alternating current (AC) electricity to thousands of homes, the electrical equipment we commonly use, such as lighting, televisions, electro-acoustics, and computers, all require direct current (DC) electricity. Furthermore, power-driven devices requiring speed control (e.g., elevators, electric vehicles, high-speed trains, precision machine tools) and devices requiring precise control all require DC electricity, and in all cases, the AC electricity must first be converted to DC electricity before use.

[0003] On the device side, rectification and capacitor filtering are necessary to convert AC electricity to DC electricity. The pulsating DC voltage obtained after rectification can become a stable DC voltage after filtering. When capacitor filtering is used, the AC current becomes a pulsed current, and many high-order harmonics appear. Further removal by power factor calibration is necessary to satisfy the high-order harmonic requirements in the relevant standards (National Standard of the People's Republic of China GB 17625.1-2012 / IEC 61000-3-2:2009: Electromagnetic compatibility limit value, harmonic current transmission limit value (each phase input current of the device ≤ 16A)). This national standard is a mandatory standard, and any product that does not meet the mandatory standard is prohibited from production, sale, and import. Therefore, for electrical equipment, it is necessary to consider whether removal of high-order harmonics by power factor calibration is required.

[0004] However, power factor calibration is very complex, and it significantly increases the cost of DC power supplies, especially high-power power factor calibration. [Overview of the project]

[0005] Based on the above, the present invention provides a power supply circuit and its applications. By utilizing the electromagnetic induction relationship between conductive winding coils in a magnetic core, a multiphase AC power supply is generated from a predetermined AC power supply, and further, after passing through a multiphase bridge rectifier circuit, a DC voltage and current are directly output as a DC voltage source with a low pulsation rate without capacitor filtering. This fundamentally eliminates high-order harmonics caused by capacitor filtering. In addition, since the current of the multiphase bridge rectifier circuit input from the power grid is a sine wave or a step wave very close to a sine wave, high-order harmonics generated on the AC side are reduced to a minimum without power factor calibration.

[0006] In one respect, the present invention provides a power supply circuit that generates an n-phase AC power supply from a predetermined AC power supply by utilizing the electromagnetic induction relationship between conductive winding coils in a magnetic core, and further outputs a DC voltage and current as a DC voltage source with a low pulsation rate through an n-phase bridge rectifier circuit without capacitor filtering, where n is an odd number of 5 or more.

[0007] The aforementioned n-phase AC power supply consists of n sinusoidal voltage sources with equal amplitude and initial phases distributed evenly at intervals of 360° / n.

[0008] The n-phase bridge rectifier circuit consists of n pairs of rectifier diodes connected in series, where in each of the n pairs of series-connected rectifier diodes, the cathode of one diode is connected to the anode of the other diode. Each of these connection points is connected to the n-phase output terminal of the n-phase AC power supply. The other cathode of all the n pairs of series-connected rectifier diodes is connected to form the output positive terminal of the n-phase bridge rectifier circuit. The other anode of all the n pairs of series-connected rectifier diodes is connected to form the output negative terminal of the n-phase bridge rectifier circuit.

[0009] In addition to the perspectives described above and any one possible implementation, we will provide further implementations. Here, n may be an odd number greater than or equal to 7.

[0010] In addition to the viewpoints described above and one possible implementation, further implementation forms are provided. A 3m-phase AC power supply, which is induced in the stator windings by the rotating magnetic field generated by the stator windings of a 3-phase AC motor, may be used to output a DC voltage and current through a 3m-phase bridge rectifier circuit. Here, m is an odd number greater than or equal to 3, and 3m = n.

[0011] In addition to the perspectives described above and any one possible implementation, we will provide further implementations. Here, m may be an odd number greater than or equal to 5.

[0012] In addition to the viewpoints described above and any one possible implementation, further implementation forms are provided. When a single-phase AC asynchronous motor is in operation, the n-phase AC power generated by the rotational magnetic field induced in the stator winding may be used to output a DC voltage and current via an n-phase bridge rectifier circuit.

[0013] In addition to the perspectives described above and any one possible implementation, we will provide further implementations. Here, n may be an odd number greater than or equal to 7.

[0014] In addition to the viewpoints described above, we further provide implementation forms, such as any one possible implementation form. The n-phase AC power supply is a 3h-phase AC power supply, consisting of 3h sets of different winding combinations of the secondary windings of a 3-phase AC transformer, and the 3h AC voltage sources output therefrom may output DC voltage and current through a 3h-phase bridge rectifier circuit. Here, h is an odd number greater than or equal to 3.

[0015] As described above and as any one possible implementation, we can provide further implementations where h may be an odd number greater than or equal to 5.

[0016] In addition to the viewpoints described above, we further provide implementation forms, such as any one possible implementation form. The combination of three different windings of the 3h set of secondary windings of the three-phase AC transformer employs a star connection method, specifically, one end of each of the 3h winding combinations is connected to the same location, and the other end is the output terminal of the 3h-phase AC power supply, which may output DC voltage and current via a 3h-phase bridge rectifier circuit.

[0017] In addition to the viewpoints described above, we further provide implementation forms, such as any one possible implementation form. The combination of three different windings of the three-phase AC transformer's secondary winding employs a polygonal connection method. Specifically, the start and end of the three winding combinations are connected in order, with the end of the last combination connected to the start of the first combination to form a closed loop, resulting in three connection points. These three connection points serve as the output terminals of the three-phase AC power supply, and may further output DC voltage and current via a three-phase bridge rectifier circuit.

[0018] In another respect, the present invention provides an application of any one of the power supply circuits described above. The power supply circuit is applied to a product terminal and connected to an AC electrical input terminal as all or part of the product power supply.

[0019] Compared to conventional technologies, the advantages or beneficial effects of one of the above technical solutions are as follows: The rectifier circuit of the present invention can rectify multiphase AC electricity and obtain a stable DC voltage without filtering.

[0020] The advantages or beneficial effects of another means in the above technical solutions are as follows: The rectifier circuit of the present invention eliminates the filtering step and fundamentally eliminates many of the higher harmonics that are produced by filtering. This eliminates the need to consider the removal of higher harmonics in electrical installations, eliminates the power factor calibration step, and simplifies the design and production costs of electrical installations.

[0021] Another merit or beneficial effect of the above technical solution 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, enabling the power grid to supply power to each household in the form of direct current, making it easier for users to connect their DC equipment to the power source.

Brief Description of the Drawings

[0022] To make the technical solution of the present invention clearer, the drawings used will be briefly introduced below. The following drawings are part of the embodiments of the present invention, and it is obvious that those skilled in the art can obtain other drawings based on these drawings without creative effort. [Figure 1] It is a block diagram of a polyphase bridge rectifier circuit according to an embodiment of the present invention. Among the combinations of the secondary windings of n three-phase AC transformers, the star connection method is adopted. [Figure 2] It is a voltage waveform diagram of a 9-phase AC power supply according to an embodiment of the present invention. [Figure 3] It is a waveform diagram of the output DC voltage after rectification of a 9-phase bridge rectifier circuit according to an embodiment of the present invention. [Figure 4] It is a corresponding relationship diagram of the step wave magnetomotive force W·I between the primary side and the secondary side in the iron core of a three-phase transformer when a 9-phase AC power supply composed of a combination of the secondary windings of a three-phase transformer according to an embodiment of the present invention is connected to a 9-phase bridge rectifier circuit. [Figure 5] It is a diagram of a polyphase bridge rectifier circuit of a 9-phase AC power supply obtained by adopting the polygon connection method among the combinations of the secondary windings of a three-phase AC transformer according to an embodiment of the present invention. [Figure 6] It is a diagram showing the relationship between the exterior angle of a regular polygon (regular nonagon) and the central angle of the circumscribed circle according to an embodiment of the present invention. Whether the combinations of the secondary windings of the same three-phase AC transformer are connected by the polygon connection method or the star connection method, it corresponds to obtaining a 9-phase AC power supply respectively.

Modes for Carrying Out the Invention

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

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

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

[0026] These five types of winding lengths are combined with positive and negative polarity, and three are grouped together and connected in series to form the nine required combinations of secondary windings for transformers. These are as follows: Transformer secondary winding combination 1: A phase N 1 time, B phase - N 4 times, C phase - N 4 times, Transformer secondary winding combination 2: A phase N 2 times, B phase N 3 times, C phase - N 5 times, Transformer secondary winding combination 3: A phase N 3 times, B phase N 2 times, C phase - N 5 times, Transformer secondary winding combination 4: A phase - N 4 times, B phase - N 1 time, C phase - N 4 times, Transformer secondary winding combination 5: A phase - N 5 times, B phase N 2 times, C phase N 3 times, Transformer secondary winding combination 6: A phase - N 5 times, B phase N 3 times, C phase N 2 times, Transformer secondary winding combination 7: A phase - N 4 times, B phase - N 4 times, C phase - N 1 time, Transformer secondary winding combination 8: A phase N 3 times, B phase - N 5 times, C phase N 2 times, Transformer secondary winding combination 9: A phase N 2 times, B phase - N 5 times, C phase N 3 times.

[0027] Figure 1 shows how the combination of n windings is connected using a star connection method. When this N-phase AC power supply is input to the N-phase rectifier bridge consisting of 2N rectifier diodes according to the present invention, a pulsating DC voltage with a low pulsation rate can be obtained without a filter capacitor. As can be seen from Figure 3, the pulsation rate in Figure 4 shows a clear reduction compared to the pulsation rate of conventional three-phase rectification.

[0028] As is well known, the rate of change of the extrema of a continuous differentiable function is 0. Specifically, the change in value at the maximum and minimum values ​​of a sine function is very small, and its absolute value is close to 1. For example, Sin 80° = Sin 100° = 0.98481.

[0029] Taking a 9-phase bridge rectifier circuit as an example, since Sin80° = Sin100° = 0.984819, the output DC pulsating voltage at this point fluctuates between the extreme values ​​of 0.984819, and the pulsation rate is less than 1%. With such a low pulsation rate, filtering becomes unnecessary. Also, when n=15, Sin84° = 0.99452, so the pulsation rate becomes less than 0.3%, and filtering is unnecessary.

[0030] This nine-phase AC power supply can be obtained from a combination of the secondary windings of a three-phase AC transformer. According to JPEG0007843960000001.jpg6182, Because it is JPEG0007843960000002.jpg882, therefore, JPEG0007843960000003.jpg1382

[0031] moreover, As shown in JPEG0007843960000004.jpg1382, by assigning each of the three secondary windings of a three-phase transformer to one of the three phases and adding the voltages in the windings with a predetermined ratio of turns, an arbitrary initial phase can be created. The sine value of JPEG0007843960000005.jpg1011 can be obtained.

[0032] By saving the image as JPEG0007843960000006.jpg626 (where N is an integer greater than 5, n=0, 1, 2, ..., N-1), we obtain N sine quantities. JPEG0007843960000007.jpg624.

[0033] JPEG0007843960000008.jpg1082 (where n=0,1,2,...N-1).

[0034] This is a so-called n-phase AC power supply, consisting of n sinusoidal voltage sources with equal amplitude, initial phases spaced 360° / n apart, and evenly distributed.

[0035] From the above, we can conclude that the N-phase AC power supply necessary for multiphase bridge rectification can be obtained by utilizing the secondary winding of a three-phase AC transformer.

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

[0037] The secondary windings of all three-phase AC transformers here have five different number of turns, and the ratio of the number of turns to each other is N1:N2:N3:N4:N5 = Sin90°:Sin50°:Sin10°:Sin30°:Sin70°.

[0038] Based on this ratio of turns and the polarity of the windings, it is ensured that a 9-phase AC power supply is constructed using 9 sets of windings (3 windings in each set), and at the same time, when outputting DC current, it is ensured that three step wave currents approximating a sine wave with a phase difference of 120° are induced in the three primary windings of the transformer.

[0039] When viewing a multiphase AC power supply from the rectifier bridge side, the following can be observed:

[0040] The current flowing out from the DC positive electrode flows out from the phase with the highest voltage of the AC power supply. Among the three windings, the instantaneous values of the three-phase voltages on the secondary side at this time are induced proportionally, and the sum of these three voltages is exactly the voltage value of the AC power supply of the phase that is at the highest value. The situation of the DC negative electrode output terminal is also completely similar. The current flowing from the DC negative electrode flows to the phase with the most negative voltage of the AC power supply. Among its three windings, the instantaneous values of the three-phase voltages on the secondary side at this time are also induced proportionally, and the sum of these three voltages is exactly the voltage value of the AC power supply of the phase that is the most negative. At this time, the same current flows through each of these two sets (three in each set) of windings, but the number of turns (including the positive and negative polarities) of the three windings is different. Furthermore, corresponding to the sequential conduction of the combinations of the nine windings, the number of turns and polarities of the three windings through which the current flows also change sequentially. Thereby, the product of the number of turns of the conducting windings and the DC current generates a step magnetomotive force that approximates three sine waves in the three iron cores of the transformer.

[0041] Figure 4 roughly shows the correspondence relationship of the step wave magnetomotive force W·I on the primary side and the secondary side in the iron core of a three-phase transformer (taking one phase with an initial phase of 0 as an example). In the figure, the magnetomotive force generated by the current flowing out from the phase with the highest voltage of the AC power supply in the secondary winding of the transformer is W 二次· I 出 , the magnetomotive force generated by the current flowing into the transformer from the phase with the most negative voltage of the AC power supply in the secondary winding of the transformer is W 二次· I 入 , and the magnetomotive force of the current induced and generated in the primary winding of the transformer is W 一次· I 一次 are shown.

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

[0043] The nine different combinations of secondary windings of the aforementioned three-phase AC transformer may be arranged in a star configuration or a polygonal configuration. Since the exterior angles of a regular polygon are equal to the central angles of the inscribed circles corresponding to each side, whether a star configuration or a polygonal configuration is used, each nine-phase AC voltage power supply can be obtained from the nine different combinations of secondary windings of the same three-phase AC transformer. However, the voltage amplitudes of the two methods differ, and the ratio of the voltage amplitudes of the two methods is as follows.

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

[0045] Furthermore, the rotating magnetic field generated by the stator windings of the 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 windings, and then a DC voltage and current are output via a 3h-phase bridge rectifier circuit.

[0046] When a three-phase AC motor is connected to a three-phase AC power supply, its stator windings generate a rotating magnetic field in the core. By sequentially cutting the coils in which this rotating magnetic field is uniformly distributed in the stator core grooves, we can obtain the three h-phase (where h is an odd number greater than or equal to 3) AC power supply we need.

[0047] Furthermore, during the operation of a single-phase AC asynchronous motor, the n-phase AC power supply (where n is an odd number greater than or equal to 5) induced in the stator winding by the rotating magnetic field is used to output DC voltage and current via an n-phase bridge rectifier circuit. This is the case when only a single-phase AC power supply is available, a three-phase AC power supply is not available, and it is necessary to generate an n-phase AC power supply from the single-phase AC power supply.

[0048] The alternating magnetic field with a constant direction, generated by the stator coils of a single-phase AC asynchronous motor, can be decomposed into two rotating magnetic fields of equal magnitude but opposite directions. During the operation of the single-phase AC asynchronous motor, the magnetic field generated by the induced current in the rotor coils can cancel out the magnetic field rotating in the opposite direction, and ultimately combines with the stator coils to form a rotating magnetic field. By sequentially cutting the coils, which are uniformly distributed in the core grooves of the stator by this rotating magnetic field, 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 how nine winding combinations are connected using the polygonal connection method. The ratio of turns of the three internal windings in each of the nine winding combinations is the same as in the star connection method, but the number of turns should be compressed to (2·Sin20°:1).

[0050] It is clear that the embodiments described above are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments derived from the embodiments of the present invention, without the need for creative work by those skilled in the art, are all within the scope of the protection of the present invention.

Claims

1. A power supply circuit that utilizes the electromagnetic induction relationship between conductive winding coils in a magnetic core to generate an n-phase AC power supply from a predetermined AC power supply, and then, after passing through an n-phase bridge rectifier circuit, directly outputs a DC voltage and current as a DC voltage source with a low pulsation rate without capacitor filtering. This fundamentally eliminates high-order harmonics caused by capacitor filtering, and at the same time, since the current input from the predetermined AC power supply is a sine wave or a step wave very close to a sine wave, high-order harmonics generated on the AC side are reduced to a minimum without power factor calibration, where n is an odd number of 5 or more. The aforementioned n-phase AC power supply consists of n sinusoidal voltage sources with equal amplitude and initial phases distributed evenly at intervals of 360° / n. The n-phase bridge rectifier circuit comprises n sets of two rectifier diodes connected in series, wherein 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 the n-phase output terminal of the n-phase AC power supply, the other cathode of all the n sets of two rectifier diodes connected in series is connected as the output positive terminal of the n-phase bridge rectifier circuit, and the other anode of all the n sets of two rectifier diodes connected in series is connected as the output negative terminal of the n-phase bridge rectifier circuit.

2. The power supply circuit according to claim 1, wherein n is an odd number greater than or equal to 7.

3. The power supply circuit according to claim 1, characterized in that it utilizes a 3m-phase AC power supply induced in the stator winding by a rotating magnetic field generated by the stator winding of a three-phase AC motor, and outputs a DC voltage and current directly as a DC voltage source with a low pulsation rate, passing through a 3m-phase bridge rectifier circuit without capacitor filtering, with a pulsation rate of less than 1%, and with such a low pulsation rate there is no need for filtering, thereby fundamentally eliminating higher harmonics caused by capacitor filtering, and at the same time, the current input from the predetermined AC power supply is a sine wave or a step wave very close to a sine wave, thereby reducing higher harmonics generated on the AC side to a minimum without power factor calibration, where m is an odd number of 3 or more, and 3m = n.

4. A power supply circuit that utilizes the electromagnetic induction relationship between conductive winding coils in a magnetic core to generate an n-phase AC power supply from a predetermined AC power supply, and then, after passing through an n-phase bridge rectifier circuit, directly outputs a DC voltage and current as a DC voltage source with a low pulsation rate, where n is an odd number of 5 or more. The aforementioned n-phase AC power supply consists of n sinusoidal voltage sources with equal amplitude and initial phases distributed evenly at intervals of 360° / n. The n-phase bridge rectifier circuit consists of n pairs of rectifier diodes connected in series, where in each of the n pairs of series-connected rectifier diodes, the cathode of one diode is connected to the anode of the other diode, and each connection point is connected to the n-phase output terminal of the n-phase AC power supply, the other cathode of all the n pairs of series-connected rectifier diodes is connected as the output positive terminal of the n-phase bridge rectifier circuit, and the other anode of all the n pairs of series-connected rectifier diodes is connected as the output negative terminal of the n-phase bridge rectifier circuit. A power supply circuit characterized by utilizing an n-phase AC power source induced in the stator winding by a rotating magnetic field during the operation of a single-phase AC asynchronous motor, and outputting a DC voltage and current through an n-phase bridge rectifier circuit.

5. The power supply circuit according to claim 4, wherein n is an odd number greater than or equal to 7.

6. The power supply circuit according to claim 1, characterized in that the n-phase AC power supply is a 3h-phase AC power supply, consisting of a combination of 3h sets of different windings of the secondary winding of a 3-phase AC transformer, and the 3h AC voltage sources output therefrom pass through a 3h-phase bridge rectifier circuit and directly output DC voltage and current as a DC voltage source with a low pulsation rate without capacitor filtering, with a pulsation rate of less than 1%, and with such a low pulsation rate there is no need for filtering, thereby fundamentally eliminating higher harmonics caused by capacitor filtering, and at the same time, the current input from the predetermined AC power supply is a sine wave or a step wave very close to a sine wave, thereby reducing higher harmonics generated on the AC side to a minimum without power factor calibration, where h is an odd number of 3 or more.

7. The power supply circuit according to claim 6, characterized in that the combination of three different windings of the three-phase AC transformer's secondary winding is arranged in a star configuration, one end of each of the three winding combinations is connected to the same location, and the other end is the output terminal of the three-phase AC power supply, and the DC voltage and current are directly output as a DC voltage source with a low pulsation rate without capacitor filtering via a three-phase bridge rectifier circuit.

8. The power supply circuit according to claim 6, characterized in that the combination of three different windings in the 3h sets of the secondary winding of the three-phase AC transformer employs a polygonal connection method, the start and end of the 3h winding combinations are connected sequentially, and the end of the last set is connected to the start of the first set to form a closed loop, obtaining 3h connection points, the 3h connection points are used as the output terminals of the 3h-phase AC power supply, and the DC voltage and current are directly output as a DC voltage source with a low pulsation rate, without capacitor filtering, via a 3h-phase bridge rectifier circuit.

9. The power supply circuit according to any one of claims 1-8, characterized in that it is applied to the product terminal and connected to the AC electrical input terminal as all or part of the product power supply.

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