CN104506098A - Low-power four-phase switched reluctance generator power converter - Google Patents

Abstract

The invention discloses a low-power four-phase switched reluctance generator power converter. A main circuit of the converter consists of a separately excited asymmetric half-bridge four-phase winding power converter main circuit and a Zeta chopper circuit which are in end-to-end connection in parallel; a generation output side of the separately excited asymmetric half-bridge four-phase winding power converter main circuit is in parallel connection with an input side of the Zeta chopper circuit; and an output side of the Zeta chopper circuit is in parallel connection with an excitation input side of the separately excited asymmetric half-bridge four-phase winding power converter main circuit. The converter has a simple structure, two windings can work at the same time, so that power density is increased, the voltage and current pulsation is reduced, the wide adjustable range of the exciting voltage is beneficial to the control of the maximum power output, and the converter can be used in the fields of small-scale wind power generation and direct current power supply.

Description

Small power four-phase switched reluctance generator power converter

technical field

The invention relates to the field of motor control, in particular to a power converter of a low-power four-phase winding switched reluctance generator and its control.

Background technique

Switched Reluctance Generator (Switched Reluctance Generator, referred to as: SRG) has a simple structure, no brush, no winding, no permanent magnet on the rotor; within a certain speed range, the output terminal voltage will not change with the speed change, very suitable for It is used for wind power generation and as a DC power supply; during operation, the switched reluctance generator has many controllable parameters, such as switching angle control, current chopping control, PWM control, etc., which can easily realize more complex control strategies and is flexible The control output DC voltage and current.

The working process of the switched reluctance generator is divided into two stages of excitation and power generation, and it is carried out in time-sharing. The excitation method is divided into separate excitation and self-excitation. The separate excitation method realizes separate circuits for excitation and power generation, and has high reliability. However, a special battery or other DC power supply is generally required as the excitation power supply. The self-excitation method does not require an external power supply, but the output voltage and current fluctuate greatly, causing greater pressure on the filter.

In view of the fact that increasing the excitation voltage is conducive to increasing the winding current during subsequent freewheeling power generation and thus increasing the output power, and to change the problem that the traditional excitation voltage cannot be adjusted online, some new types of excitation input voltages that can be adjusted online according to the requirements of the control system have emerged in recent years. The circuit structure of the excitation part of the power converter, such as: 1. Peng Hanmei, Yi Lingzhi, etc. New excitation mode of switched reluctance generator based on Buck converter [J]. Solar Energy Sinica, 2012, 33(3). 2. Duan Lihua. Research on the hardware structure of offshore drilling platform wind power generation system based on variable power converters[J]. Ship Electric Technology, 2012, 32(2). The former has a relatively unidirectional change in excitation voltage and output power generation voltage and current pulsation The biggest disadvantage is that the latter must be equipped with a dedicated excitation power supply, which increases the filter pressure and maintenance costs.

In addition, the switched reluctance generator currently only considers the situation that only one phase winding is energized at any moment, but according to the structural relationship between the stator and rotor of the switched reluctance motor, in the case of more than or equal to four-phase windings, the possibility of two-phase windings working at the same time can be considered sex.

Contents of the invention

According to the above background technology, the present invention proposes a main circuit and control method of a power converter for a four-phase winding switched reluctance generator that satisfies two-phase winding energization at the same time. The excitation voltage is adjustable, the structure is simple and easy to maintain, and the increase Increased power density and reduced voltage and current ripple.

Technical scheme of the present invention is:

A small-power four-phase switched reluctance generator power converter, the main circuit of which is composed of a separately excited asymmetrical half-bridge four-phase winding power converter main circuit 1 and a Zeta chopper circuit 2, characterized in that the separately excited The main circuit 1 of the asymmetrical half-bridge four-phase winding power converter and the Zeta chopper circuit 2 are connected head to tail in parallel, wherein the generator output side of the main circuit 1 of the separately excited asymmetrical half-bridge four-phase winding power converter The input side of the Zeta chopper circuit 2 is connected in parallel, and the output side of the Zeta chopper circuit 2 is connected in parallel with the excitation input side of the main circuit 1 of the separately excited asymmetrical half-bridge four-phase winding power converter.

The main circuit 1 of the separately excited asymmetrical half-bridge four-phase winding power converter is composed of four groups of asymmetrical half-bridge circuits, each of which is connected to and controls the windings of a one-phase switched reluctance generator, respectively A , B, C, and D phase windings are uniformly and symmetrically distributed on the salient poles of the stator inside the switched reluctance generator, in which the A phase winding is adjacent to the B phase and D phase windings, and the C phase winding is adjacent to the B phase and D phase windings. The phase windings are adjacent, according to the corresponding relationship between the stator and rotor of the switched reluctance motor and the current position of the rotor, as well as the time-sharing law of the excitation and power generation of the switched reluctance motor, and according to the working mode of AB-BC-CD-DA-AB, the cycle of working at the same time Two-phase winding, one phase is in the excitation stage, and the other phase is in the freewheeling power generation stage. After the winding current in the freewheeling power generation stage is reduced to zero before the electric torque is generated, the next phase is in the center of the salient pole of the stator and rotor. The winding where the lines overlap enters the excitation stage, and the windings in the aforementioned excitation stage enter the freewheeling power generation stage, and the working law is changed in this order.

Technical effect of the present invention mainly contains:

1. Due to the double-winding working mode in which the other phase winding generates power when one phase winding is excited, there is a winding generating output at any time, thereby increasing the average value of the output voltage and current, and improving the output power density and total power of the generator. In the single-winding working mode, because there is no power output in the excitation stage, the average output voltage and current are low, the output power density is small, and the total power is small;

2. In the double-winding working mode as mentioned above, the pulsation of the output voltage and current is also much smaller;

3. In practice, the excitation power source comes from its own power generation output, which should belong to the self-excitation mode, but as mentioned above, it does not have the disadvantage of large output voltage and current pulsation in the traditional self-excitation mode.

4. The Zeta chopper circuit 2 of the present invention can realize its output voltage higher or lower than the input voltage through the duty cycle adjustment of the only internal power electronic switch tube, and the voltage regulation range is wide, which is beneficial to realize a better power converter The control of the main circuit, especially the control of the maximum power output.

Description of drawings

Fig. 1 shows the main circuit diagram of the power converter of the low-power four-phase switched reluctance generator of the present invention.

Fig. 2 is a diagram showing the relationship between the stator winding inductance and the rotor position angle of the four-phase 8/6 pole structure switched reluctance generator of the present invention.

In the figure: 1. Main circuit of separately excited asymmetrical half-bridge four-phase winding power converter, 2. Zeta chopper circuit.

Detailed ways

Accompanying drawing 1 is the main circuit of the low-power four-phase switched reluctance generator power converter of the present invention, and A, B, C, D four-phase windings are the center and form separately excited type not according to asymmetrical half bridge type and traditional separately excited mode. Symmetrical half-bridge four-phase winding power converter main circuit 1, the excitation part is completed by Zeta chopper circuit 2 alone.

In this embodiment, the switched reluctance generator is selected as a four-phase 8/6-pole structure, that is, a low-power switched reluctance generator with 8 poles in the stator and 6 poles in the rotor. The relationship between the inductance of the stator winding and the position angle of the rotor is shown in Figure 2; At the origin position of 0°, the minimum inductance is L _min . At this time, the salient pole of the stator coincides with the center line of the rotor groove. At 30°, the air gap between the salient pole center lines of the stator and rotor is the smallest, and the maximum inductance is L _max . The minimum inductance appears to complete a cycle change. When the inductance rises at 0°-30°, the winding is energized to generate forward torque for motor operation. In the range of 30°-60°, reverse torque can be generated for power generation, but it must be at 30° When the current is around °, the current excitation is first connected, and then the excitation power is cut off after the current is established. The rotor will generate a larger generating current under the action of an external force. The angle of cutting off the excitation power is about 45°.

In the initial operation, the residual magnetism is firstly used, and the power generated by the winding of a certain phase of the rotor position at the initial stage of generator starting is output through the Zeta chopper circuit 2 as the next excitation power supply, and then the value of the freewheeling current and voltage is further increased. Thereby establishing power generation and excitation system power supply, eliminating the conventional initial excitation battery and diode branch.

The following is a detailed explanation of its working process according to Figure 1:

Assuming that according to the position of the rotor, firstly, the salient pole where the B-phase winding is located coincides with the center line of the salient pole of the rotor, which meets the conditions for the start of excitation, and the generated voltage established by the other phase winding due to residual magnetism at the initial start-up is output through the Zeta chopper circuit 2 as Excitation power supply, at this time the third power electronic switch tube V3 and the fourth power electronic switch tube V4 are closed and turned on for excitation; after the rotation of about 15°, the above two power electronic switch tubes are turned off, then at this time in the B-phase winding The stored magnetic energy will continue to flow along the third power diode D3 and the fourth power diode D4 and output electric energy. Note that at this time, according to the rotation of the rotor, the adjacent A-phase winding or C-phase winding will have a corresponding salient pole of the stator and the rotor. The position where the center lines of the salient poles coincide is assumed to be a C-phase winding. At this time, the fifth power electronic switch tube V5 and the sixth power electronic switch tube V6 need to be closed at the same time to excite the C-phase winding. Within the range of 15°, the two sets of windings, the freewheeling power generation of the B-phase winding and the excitation of the C-phase winding, work at the same time; after the above BC windings work at the same time for about 15°, the power generation current in the B-phase winding must be controlled to stop to prevent energy consumption. In the motoring state, at this time, the two power electronic switch tubes that control the excitation of the C-phase winding are disconnected, and the fifth power diode D5 and the sixth power diode D6 are freewheeling to generate power. At the same time, the center line of the stator salient pole and the rotor salient pole where the D-phase winding is located The coincidence meets the excitation conditions, so the seventh power electronic switch tube V7 and the eighth power electronic switch tube V8 are closed to excite the D-phase winding when the C-phase winding is excited and forwarded, and this stage is the simultaneous working stage of the CD-phase winding; Next, Similarly, the DA windings work at the same time, and the excitation of the A-phase winding is undertaken by the first power electronic switching tube V1 and the second power electronic switching tube V2, and flows through the first power diode D1 and the second power diode D2 during power generation; DA phase Then it is AB phase, and then back to BC, and so on.

Zeta chopper circuit 2 completes the supply and transformation of excitation voltage, and its working process is as follows:

When the ninth power electronic switch tube V9 is closed and turned on, the input-side current charges and stores energy in the first reactor L1 through the ninth power electronic switch tube V9, and at the same time, the input-side current also passes through the second reactance together with the first capacitor C1 After the ninth power electronic switch tube V9 is turned off, the first reactor L1 charges the first capacitor C1 through the ninth power diode D9, and the stored energy is transferred to the first capacitor C1, and at the same time The current of the second reactor L2 freewheels through the ninth power diode D9; the formula can be used to obtain the Zeta chopper circuit 2 Wherein α is the PWM control duty ratio of the ninth power electronic switching tube V9, it can be seen that when α<0.5, the voltage is reduced, and when α>0.5, the voltage is boosted.

All power electronic switching tubes described in this embodiment are IGBTs or power MOSFETs.

Claims (2)

1. Low-power four-phase switched reluctance generator power converter, its main circuit is composed of separately excited asymmetrical half-bridge four-phase winding power converter main circuit (1) and Zeta chopper circuit (2), its characteristics That is, the main circuit (1) of the separately excited asymmetrical half-bridge four-phase winding power converter and the Zeta chopper circuit (2) are connected end to end in parallel, wherein the separately excited asymmetrical half-bridge four-phase winding The power generation output side of the power converter main circuit (1) is connected in parallel with the input side of the Zeta chopper circuit (2), and the output side of the Zeta chopper circuit (2) is connected to the main circuit of the separately excited asymmetric half-bridge four-phase winding power converter. The excitation input side of the circuit (1) is connected in parallel. 2. The low-power four-phase switched reluctance generator power converter according to claim 1, wherein the main circuit (1) of the separately excited asymmetrical half-bridge four-phase winding power converter consists of four It consists of a set of asymmetrical half-bridge circuits, each of which is connected to and controls the windings of a switched reluctance generator, which are A, B, C, and D phase windings and are arranged on the salient poles of the stator inside the switched reluctance generator according to the law. Uniform and symmetrical winding distribution, in which the A-phase winding is adjacent to the B-phase and D-phase windings, and the C-phase winding is adjacent to the B-phase and D-phase windings. The time-sharing law of the excitation and power generation of the resistance generator is cycled according to the working mode of AB-BC-CD-DA-AB. The two-phase windings that work at the same time, one phase is in the excitation phase, and the other phase is in the freewheeling power generation phase. After the winding current in the freewheeling power generation phase drops to zero before the motor torque is generated, the winding of the next phase at the coincidence of the centerlines of the salient poles of the stator and rotor enters the excitation phase, and the windings in the previous excitation phase enter the freewheeling power generation phase, so Sequential transformation work rules.