A Method and Device for Implementing Single-Phase Power Supply Conversion and Voltage Compensation

Abstract

The present invention discloses a method and device for realizing single-phase power conversion and voltage compensation, which relates to the technical field of power phase conversion. The method includes: three-phase currents flow through the three-phase power input winding to form a rotating magnetic field; after a load is connected to the single-phase power output winding, a current flows through the single-phase power output winding to form a pulsating magnetic field; the negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifier circuit to form a rotor magnetic field; the rotating magnetic field, the positive-sequence magnetic field formed by the decomposition of the pulsating magnetic field, and the rotor magnetic field are synthesized to obtain a synthesized magnetic field; the rotor magnetic field compensates the synthesized magnetic field; the synthesized magnetic field cuts the three-phase power input winding and the single-phase power output winding to generate an induced electromotive force. The present invention realizes the conversion from three-phase power to single-phase power and the automatic compensation of the output voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of power phase conversion, and particularly to a method and device for realizing single-phase power conversion and voltage compensation. Background Art

[0002] The power supply system of modern power systems is mainly in the three-phase system. The power supply systems that are most easily obtained by users are three-phase power supplies or using one phase out of the three-phase neutralization as a single-phase power supply. Therefore, the electrical equipment used in industry mainly includes three-phase or single-phase electrical equipment. For example, in the field of AC electrical drive such as industrial and agricultural production, three-phase motors are mainly used; while for household appliances, since the power supply for residents is mainly single-phase power, and the power supply lines provided by power supply enterprises to residents only provide single-phase power, household appliances are mainly powered by single-phase power.

[0003] Currently, although three-phase motor drive systems have been widely used in electrical drive applications in industry, in some occasions where single-phase power is required, such as electrified railway traction power supply systems and civil power systems, the common practice is to take one phase from the three-phase public power system as the power supply, and balance the asymmetry of the three-phase load through the electricity consumption probability of the load. However, it is difficult to ensure the complete symmetry of the three-phase load through this method, and even serious negative sequence components will be caused in the three-phase public power system, affecting the safe operation of the system and generating large negative sequence losses in electrical equipment. For example, in the electrified railway power supply system, since in-phase through power supply cannot be adopted, the common method is to use a traction transformer to convert the 110 kV or 220 kV three-phase public high voltage into two-phase 27.5 kV voltages and connect them to the power supply arms on both sides respectively. This power supply method not only brings a series of power quality problems such as negative sequence, reactive power and harmonics to the three-phase public power system, but also the existing electrical phase separation in itself causes losses to the traction force and speed of electric locomotives, which is not conducive to the development of electrified railways towards high speed and heavy load.

[0004] To realize the conversion of the number of phases through power electronics technology requires complex rectification and inversion processes, and in order to reduce the influence of harmonics, relevant filtering devices also need to be set up. Since the basic principle of this technology is to perform area equivalent cutting on current or voltage, it is easy to introduce harmonics into the system. At the same time, this technology is based on power electronic devices, and the stability of its output voltage is limited. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for realizing single-phase power conversion and voltage compensation, which can realize the conversion from three-phase power to single-phase power and the automatic compensation of the output voltage.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] A method for realizing single-phase power supply conversion and voltage compensation, the method for realizing single-phase power supply conversion and voltage compensation specifically includes:

[0008] A three-phase power supply input winding is arranged on the stator. After the three-phase power supply input winding is connected to a three-phase power supply, the three-phase power supply input winding and the three-phase power supply form a loop, and three-phase current flows through the three-phase power supply input winding to form a rotating magnetic field.

[0009] A single-phase power supply output winding is arranged on the stator. After the single-phase power supply output winding is connected to a load, current flows through the single-phase power supply output winding to form a pulsating magnetic field.

[0010] A direct-axis excitation winding, a quadrature-axis excitation winding and a rectifying circuit are arranged in the rotor. The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding and the rectifying circuit to form a rotor magnetic field.

[0011] The rotating magnetic field, the positive-sequence magnetic field formed by the decomposition of the pulsating magnetic field, and the rotor magnetic field are synthesized to obtain a synthesized magnetic field.

[0012] The rotor magnetic field compensates the synthesized magnetic field.

[0013] The synthesized magnetic field cuts the three-phase power supply input winding and the single-phase power supply output winding to generate induced electromotive force.

[0014] Optionally, the calculation formula of the rotating magnetic field is:

[0015]

[0016] In the formula, F 旋 is the rotating magnetic field; is the amplitude of the magnetomotive force of the single-phase power supply output winding; θ s is the mechanical electrical angle of the motor in space; ω is the power supply frequency; t is the time of power supply conversion.

[0017] Optionally, the negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding and the rectifying circuit to form a rotor magnetic field, which specifically includes:

[0018] The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field cuts the direct-axis excitation winding and the quadrature-axis excitation winding to generate alternating voltage in the direct-axis excitation winding and the quadrature-axis excitation winding;

[0019] The alternating voltage forms the excitation current in the direct-axis excitation winding and the quadrature-axis excitation winding through the rectifying circuit;

[0020] The excitation current forms a rotor magnetic field.

[0021] Optionally, the three-phase power input winding is a three-phase symmetrical winding.

[0022] To achieve the above object, the present invention also provides the following solution:

[0023] A device for realizing single-phase power conversion and voltage compensation, the device for realizing single-phase power conversion and voltage compensation applies the method for realizing single-phase power conversion and voltage compensation described above, the device is connected to a three-phase power supply, a motor and a load, and the device for realizing single-phase power conversion and voltage compensation includes: a three-phase power input winding, a single-phase power output winding, a rectifier circuit, a direct-axis excitation winding and a quadrature-axis excitation winding;

[0024] The three-phase power input winding is connected to the three-phase power supply and wound on the stator of the motor;

[0025] The single-phase power output winding is connected to the load and wound on the stator of the motor;

[0026] Both the direct-axis excitation winding and the quadrature-axis excitation winding are connected to the rectifier circuit; the direct-axis excitation winding, the quadrature-axis excitation winding and the rectifier circuit are all arranged on the rotor of the motor.

[0027] Optionally, the three-phase power input winding is a three-phase symmetrical winding.

[0028] Optionally, the rectifier circuit includes a first diode, a second diode, a third diode and a fourth diode;

[0029] The anode of the first diode is connected to the anode of the fourth diode; the cathode of the first diode is connected to the anode of the second diode; the cathode of the second diode is connected to the cathode of the third diode; the cathode of the fourth diode and the anode of the third diode are connected.

[0030] Optionally, the direct-axis excitation winding is respectively connected to the connection points of the first diode and the second diode, and the connection points of the third diode and the fourth diode; the quadrature-axis excitation winding is respectively connected to the connection points of the first diode and the fourth diode, and the connection points of the second diode and the third diode.

[0031] According to the specific embodiments provided by the present invention, the following technical effects of the present invention are disclosed:

[0032] The present invention provides a method and a device for realizing single-phase power conversion and voltage compensation. The method realizes the conversion of three-phase power to single-phase power by respectively arranging a three-phase power input winding and a single-phase power output winding on the stator, and arranging a direct-axis excitation winding, a quadrature-axis excitation winding and a rectifier circuit in the rotor.

[0033] After the three-phase power input winding is connected to a three-phase power supply, a circuit is formed between the three-phase power input winding and the three-phase power supply, and three-phase current flows through the three-phase power input winding to form a rotating magnetic field; after the single-phase power output winding is connected to a load, current flows through the single-phase power output winding to form a pulsating magnetic field; the negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifier circuit to form a rotor magnetic field; the rotating magnetic field, the positive-sequence magnetic field formed by the decomposition of the pulsating magnetic field, and the rotor magnetic field are synthesized to obtain a synthesized magnetic field; the rotor magnetic field compensates for the synthesized magnetic field, realizing automatic compensation of the output voltage; the synthesized magnetic field cuts the three-phase power input winding and the single-phase power output winding to generate induced electromotive force.

[0034] Compared with the prior art where the stability of the output voltage is limited, the present invention realizes automatic compensation of the output voltage and maintains the stability of the output voltage; at the same time, the present invention realizes the transformation from a three-phase power supply to a single-phase power supply while ensuring the symmetry of the three-phase load. Brief Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic flowchart of the method for realizing single-phase power supply transformation and voltage compensation of the present invention;

[0037] Figure 2 It is a schematic structural diagram of an embodiment of the device for realizing single-phase power supply transformation and voltage compensation of the present invention;

[0038] Figure 3 It is a schematic diagram of the three-phase power input winding and the single-phase power output winding of the present invention;

[0039] Figure 4 It is a schematic diagram of the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifier circuit of the present invention.

[0040] Symbol Description:

[0041] Three-phase power input winding - 1, single-phase power output winding - 2, direct-axis excitation winding - 3, quadrature-axis excitation winding - 4, rectifier circuit - 5. Detailed Embodiments

[0042] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The object of the present invention is to provide a method and device for realizing single-phase power supply conversion and voltage compensation, which realizes the conversion of three-phase power supply to single-phase power supply and the automatic compensation of the output voltage.

[0044] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] As Figure 1 shown, a method for realizing single-phase power supply conversion and voltage compensation according to the present invention, the method for realizing single-phase power supply conversion and voltage compensation specifically includes:

[0046] S1. A three-phase power input winding 1 is provided on the stator. When the three-phase power input winding 1 is connected to a three-phase power supply, the three-phase power input winding 1 forms a loop with the three-phase power supply, and three-phase current flows through the three-phase power input winding 1 to form a rotating magnetic field.

[0047] S2. A single-phase power output winding 2 is provided on the stator. When the single-phase power output winding 2 is connected to a load, current flows through the single-phase power output winding 2 to form a pulsating magnetic field.

[0048] S3. A direct-axis excitation winding 3, a quadrature-axis excitation winding 4, and a rectifier circuit 5 are provided in the rotor. The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding 3, the quadrature-axis excitation winding 4, and the rectifier circuit 5 to form a rotor magnetic field.

[0049] S4. The rotating magnetic field, the positive-sequence magnetic field formed by the decomposition of the pulsating magnetic field, and the rotor magnetic field are synthesized to obtain a synthesized magnetic field.

[0050] S5. The rotor magnetic field compensates the synthesized magnetic field.

[0051] S6. The synthesized magnetic field cuts the three-phase power input winding 1 and the single-phase power output winding 2 to generate induced electromotive force.

[0052] The negative sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding 3 and the quadrature-axis excitation winding 4 to generate induced electromotive forces. After rectification through the rectifier circuit 5, a DC pulsating current is formed in the direct-axis excitation winding 3; the DC pulsating current generates the main pole excitation magnetic field of the motor (i.e., the rotor magnetic field), thereby realizing the automatic compensation of the output voltage.

[0053] Furthermore, the negative sequence magnetic field formed by the decomposition of the pulsating magnetic field in step S3 acts on the direct-axis excitation winding 3, the quadrature-axis excitation winding 4, and the rectifier circuit 5 to form the rotor magnetic field, specifically including:

[0054] S301, the negative sequence magnetic field formed by the decomposition of the pulsating magnetic field cuts the direct-axis excitation winding 3 and the quadrature-axis excitation winding 4, generating alternating voltages in the direct-axis excitation winding 3 and the quadrature-axis excitation winding 4.

[0055] S302, the alternating voltages form the excitation currents in the direct-axis excitation winding 3 and the quadrature-axis excitation winding 4 through the rectifier circuit 5.

[0056] S303, the excitation currents form the rotor magnetic field.

[0057] Preferably, the three-phase power input winding 1 is a three-phase symmetric winding. The three-phase symmetric windings are spatially offset by 120 electrical degrees (in motor theory, electrical degrees = number of motor pole pairs * 360 degrees).

[0058] During the phase conversion operation, no mechanical load is connected to the rotor shaft end or driven by a prime mover; when no load is connected to the single-phase power output winding 2, the rotating magnetic field formed by passing three-phase currents through the three-phase power input winding 1 will be cut by the single-phase power output winding 2, thereby generating a single-phase induced electromotive force in the single-phase power output winding 2 and forming a single-phase output no-load voltage.

[0059] In addition, the number of motor poles corresponding to the three-phase power input winding 1 and the single-phase power output winding 2 is equal.

[0060] Optionally, the calculation formula for the rotating magnetic field is:

[0061]

[0062] In the formula, F 旋 is the rotating magnetic field; is the amplitude of the magnetomotive force of the single-phase power output winding; θ s is the mechanical electrical angle of the motor in space; ω is the power supply frequency; t is the time of power supply conversion.

[0063] Optionally, the calculation formula for the pulsating magnetic field is:

[0064] F1 = F 1+ + F 1-。

[0065] In the formula, F1 is the pulsating magnetic field, and F 1+ is the positive-sequence magnetic field of the pulsating magnetic field, and F 1- is the negative-sequence magnetic field of the pulsating magnetic field.

[0066] Among them, the calculation formula for the positive-sequence magnetic field of the pulsating magnetic field is:

[0067]

[0068] The calculation formula for the negative-sequence magnetic field of the pulsating magnetic field is:

[0069]

[0070] As Figure 2 shown, the present invention provides a device for realizing single-phase power supply conversion and voltage compensation. The device for realizing single-phase power supply conversion and voltage compensation applies the above method for realizing single-phase power supply conversion and voltage compensation. The device is connected to a three-phase power supply, a motor, and a load. The device for realizing single-phase power supply conversion and voltage compensation includes: a three-phase power supply input winding 1, a single-phase power supply output winding 2, a rectifier circuit 5, a direct-axis excitation winding 3, and a quadrature-axis excitation winding 4.

[0071] The three-phase power supply input winding 1 is connected to the three-phase power supply and wound on the stator of the motor (as Figure 3 shown).

[0072] The single-phase power supply output winding 2 is connected to the load and wound on the stator of the motor (as Figure 3 shown).

[0073] The direct-axis excitation winding 3 and the quadrature-axis excitation winding 4 are both connected to the rectifier circuit 5; the direct-axis excitation winding 3, the quadrature-axis excitation winding 4, and the rectifier circuit 5 are all arranged on the rotor of the motor (as Figure 4 shown).

[0074] In addition, the single-phase power supply output winding 2 can be uniformly arranged; the single-phase power supply output winding 2 can also be arranged by occupying some stator slots according to needs. The relative spatial positions of the single-phase power supply output winding 2 and the three-phase power supply input winding 1 can be set according to actual needs. The conversion of the input power supply voltage can be realized through the design of the number of turns of the two sets of windings.

[0075] At the same time, A, B, and C are respectively the connection points of the three-phase power supply input winding 1 and the three-phase power supply; a and x are respectively the connection points of the single-phase power supply output winding 2 and the load.

[0076] In a specific embodiment, the three-phase power supply input winding 1 is a three-phase symmetrical winding.

[0077] Optionally, the rectifier circuit 5 includes a first diode, a second diode, a third diode, and a fourth diode (as Figure 2 shown).

[0078] The anode of the first diode is connected to the anode of the fourth diode; the cathode of the first diode is connected to the anode of the second diode; the cathode of the second diode is connected to the cathode of the third diode; the cathode of the fourth diode and the anode of the third diode are connected.

[0079] Optionally, the direct-axis exciting winding 3 is respectively connected to the connection points of the first diode and the second diode, and the connection points of the third diode and the fourth diode; the quadrature-axis exciting winding 4 is respectively connected to the connection points of the first diode and the fourth diode, and the connection points of the second diode and the third diode.

[0080] The first diode, the second diode, the third diode, and the fourth diode in the rectifier circuit 5 are all single-phase conducting diodes; among them, D1 is the first diode, D2 is the second diode, D3 is the third diode, and D4 is the fourth diode; the rectifier circuit 5 rotates together with the rotor.

[0081] As Figure 2 shown, a schematic structural diagram of an embodiment of the device for realizing single-phase power supply conversion and voltage compensation according to the present invention; the direct-axis exciting winding 3 and the quadrature-axis exciting winding 4 adopt distributed windings. In addition, the direct-axis exciting winding 3 and the quadrature-axis exciting winding 4 can also adopt concentrated windings. The connection manner among the direct-axis exciting winding 3, the quadrature-axis exciting winding 4, and the rectifier circuit 5 is not affected by the winding manner.

[0082] The present invention realizes the conversion from a three-phase power supply to a single-phase power supply; and as the load increases, the negative-sequence magnetic field of the pulsating magnetic field compensates the synthetic magnetic field, achieving the effect of stabilizing the output voltage; at the same time, a new method is provided for a single-phase power supply that requires strong anti-shock and overload capabilities, ensuring the reliability of the single-phase power supply conversion equipment and the stability of the output voltage. In addition, the present invention fundamentally eliminates the load asymmetry problem caused by supplying power to a single-phase load system using a three-phase power supply system, improving the quality of the single-phase power supply.

[0083] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the relevant parts, reference can be made to the description in the method part.

[0084] In this article, specific examples are used to elaborate on the principles and implementation modes of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation modes and application scopes. To sum up, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for realizing single-phase power supply conversion and voltage compensation, characterized in that, The method for realizing single-phase power conversion and voltage compensation specifically includes: A three-phase power input winding is arranged on the stator. After the three-phase power input winding is connected to a three-phase power supply, a loop is formed between the three-phase power input winding and the three-phase power supply, and three-phase current flows through the three-phase power input winding to form a rotating magnetic field; A single-phase power output winding is arranged on the stator. After the single-phase power output winding is connected to a load, current flows through the single-phase power output winding to form a pulsating magnetic field; A direct-axis excitation winding, a quadrature-axis excitation winding, and a rectifying circuit are arranged in the rotor. The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifying circuit to form a rotor magnetic field; The rotating magnetic field, the positive-sequence magnetic field formed by the decomposition of the pulsating magnetic field, and the rotor magnetic field are synthesized to obtain a synthesized magnetic field; The rotor magnetic field compensates the synthesized magnetic field; The synthesized magnetic field cuts the three-phase power input winding and the single-phase power output winding to generate induced electromotive force.

2. The method for realizing single-phase power supply conversion and voltage compensation according to claim 1, wherein The calculation formula for the rotating magnetic field is: Where, F 旋 is the rotating magnetic field; is the amplitude of the magnetomotive force of the single-phase power supply output winding; θ s is the mechanical electrical angle of the motor in space; ω is the power supply frequency; t is the time of power supply conversion.

3. The method for realizing single-phase power supply conversion and voltage compensation according to claim 1, wherein The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field acts on the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifying circuit to form a rotor magnetic field, specifically including: The negative-sequence magnetic field formed by the decomposition of the pulsating magnetic field cuts the direct-axis excitation winding and the quadrature-axis excitation winding to generate alternating voltage in the direct-axis excitation winding and the quadrature-axis excitation winding; The alternating voltage forms excitation current in the direct-axis excitation winding and the quadrature-axis excitation winding through the rectifying circuit; The excitation current forms a rotor magnetic field.

4. The method for realizing single-phase power supply conversion and voltage compensation according to claim 1, wherein, The three-phase power input winding is a three-phase symmetrical winding.

5. A device for realizing single-phase power supply conversion and voltage compensation Characterized in that, the device for realizing single-phase power conversion and voltage compensation applies the method for realizing single-phase power conversion and voltage compensation according to any one of claims 1-4. The device is connected to a three-phase power supply, a motor, and a load. The device for realizing single-phase power conversion and voltage compensation includes: a three-phase power input winding, a single-phase power output winding, a rectifying circuit, a direct-axis excitation winding, and a quadrature-axis excitation winding; The three-phase power input winding is connected to the three-phase power supply and wound on the stator of the motor; The single-phase power output winding is connected to the load and wound on the stator of the motor; Both the direct-axis excitation winding and the quadrature-axis excitation winding are connected to the rectifying circuit; the direct-axis excitation winding, the quadrature-axis excitation winding, and the rectifying circuit are all arranged on the rotor of the motor.

6. The device for realizing single-phase power supply conversion and voltage compensation according to claim 5, wherein, The three-phase power input winding is a three-phase symmetrical winding.

7. The device for realizing single-phase power supply conversion and voltage compensation according to claim 5, characterized in that, The rectifying circuit includes a first diode, a second diode, a third diode, and a fourth diode; The anode of the first diode is connected to the anode of the fourth diode; the cathode of the first diode is connected to the anode of the second diode; the cathode of the second diode is connected to the cathode of the third diode; the cathode of the fourth diode and the anode of the third diode are connected.

8. The device for realizing single-phase power supply conversion and voltage compensation according to claim 7, wherein, The direct-axis excitation winding is connected to the connections between the first diode and the second diode, and between the third diode and the fourth diode respectively; the quadrature-axis excitation winding is connected to the connections between the first diode and the fourth diode, and between the second diode and the third diode respectively.

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