CN107026590A - A kind of switching magnetic-resistance current transformer of wind-driven generator and its control method - Google Patents

Abstract

A switched reluctance wind power generator converter, which is composed of a converter main circuit, an output bus capacitor, an isolated DC/DC converter, and an excitation and discharge main circuit. The input of the DC/DC converter, the output of the isolated DC/DC converter is connected to the input of the excitation and discharge main circuit, the output of the excitation and discharge main circuit is connected to the input of the inverter main circuit, and the positive terminal of the output of the inverter main circuit is also connected to the excitation and discharge main circuit. The discharge input terminal of the circuit, the positive terminal of the excitation and discharge main circuit output, the negative terminal of the output of the main converter circuit, and the positive terminal of the main converter circuit are short-circuited; under this structure, through three types of control modes under different conditions, a wide power generation range, High power generation capacity, multi-angle flexible control, suitable for various wind power generation fields.

Description

A switched reluctance wind generator converter and its control method

technical field

The invention relates to the field of wind power generation, in particular to a converter circuit topology system of a switched reluctance wind power generator and a control method thereof.

Background technique

The use of switched reluctance generators to generate electricity is a new type of power generation; at present, there are no real commercial cases of using switched reluctance generators in power generation systems adapted to wind characteristics at home and abroad. The reason is that switched reluctance generators The unique structure and variable flow system are relatively special, and are being studied in recent years.

Wind power generation is a sunshine industry. Most of the current wind power generators use permanent magnet synchronous or doubly-fed asynchronous generators. The former has shown the disadvantage of high cost in recent years, especially the extensive use of rare earth permanent magnet materials. The latter requires double-fed stator and rotor. Winding, double converter system; and the switched reluctance generator is simple in structure, durable, low in cost, strong in fault tolerance and high in reliability, and its efficiency is higher than that of double-fed asynchronous generator, so it has broad application prospects.

In the wind power industry, the maximum power output capability is the key to the operation and control of generating units in this industry. Higher efficiency and benefits, greater power density of power generation capacity, and wider power generation range are especially needed in this field.

The switched reluctance generator converter is the central link in the operation and control of the switched reluctance generator system. In the existing converter structure, if the two stages of excitation and power generation are independently operated and controlled, they are separately excited. If The power required for excitation comes from the electric energy generated in the power generation stage, which is self-excited. The traditional self-excited type uses the generated voltage directly as the excitation voltage, and the voltage and current fluctuate greatly. Although the voltage and current fluctuations of the separately excited type are small, special other The excitation power increases the maintenance workload.

At present, there are also some decoupled self-excited switched reluctance generator converter systems in the industry. The excitation voltage can also be adjusted independently, which enhances the adaptability of the system in the wind power field, but the flexibility is insufficient. For example, if the excitation power supply fails or the control Due to the limitation of the excitation voltage, the variation range of the excitation voltage is not wide, or the voltage and current of the excitation stage of the winding are adjusted solely by the change of the excitation power supply. If necessary, there is a lack of multi-directional strengthening control capabilities for the rapid response of the system.

In addition, in terms of adapting to extremely low wind speed, extremely high wind speed, extremely high speed, and extremely low load, etc., new systems are also required to take these into consideration, so that the operating width of the entire power generation system can be increased, and the power generation efficiency of the system can be improved. and efficiency.

Among the current considerations in the industry, a big trend is to make the converter more and more complex, requiring more and more switching tubes, and the frequent switching actions of the switching tubes, especially PWM control, etc., resulting in a large number of switching tubes. Loss, consumes a lot of electric energy, reduces the power generation efficiency.

Contents of the invention

According to the above background technology, the present invention proposes a wide range of excitation voltage adjustment, two ways of separate regulation to improve the excitation strengthening ability, multiple switching tubes but less switching frequency, special freewheeling circuit to improve the winding current before the power generation stage, etc. The structure of the converter system and its control method have improved the wide-range power generation range and power generation output capacity adapted to the wind characteristics, and improved the power generation efficiency and benefit, while simplifying the structure.

Technical scheme of the present invention is:

A switched reluctance wind power generator converter, which is composed of a converter main circuit, an output bus capacitor, an isolated DC/DC converter, and an excitation and discharge main circuit. The positive and negative ends of the output of the converter main circuit are connected to the The positive and negative ends of the output busbar capacitor are simultaneously used as the positive and negative ends of the input of the isolated DC/DC converter, and the positive and negative ends of the output of the isolated DC/DC converter are connected to the positive and negative ends of the excitation and discharge main circuit input. The positive and negative ends of the output of the excitation and discharge main circuit are connected to the positive and negative ends of the input of the inverter main circuit, the positive end of the output of the inverter main circuit is also connected to the discharge input end of the excitation and discharge main circuit, the output , The output negative terminal of the inverter main circuit and the positive input terminal of the inverter main circuit are short-circuited;

The converter main circuit is composed of three or four converter branches connected in parallel, and each converter branch is internally connected to a phase winding of the switched reluctance generator, and each phase winding contains two sets of windings, which are connected separately, specifically For example, each converter branch is composed of the first set of windings, the second set of windings, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, and the first diode , wherein one end of the first set of windings, the anode of the first switch tube, and the cathode of the second switch tube are short-circuited and used as the input positive terminal of the inverter main circuit, and the cathode of the first switch tube is connected to the first diode tube cathode and one end of the second set of windings, the other end of the first set of windings is connected to the anode of the first diode and the anode of the third switching tube, the other end of the second set of windings is connected to the cathode of the third switching tube, the fourth The anode of the switching tube, the anode of the second switching tube, the anode of the fifth switching tube, the cathode of the fourth switching tube is used as the input negative terminal of the inverter main circuit, and the cathode of the fifth switching tube is used as the output positive terminal of the inverter main circuit;

The isolated DC/DC converter includes an electromagnetic isolation link, and its output DC voltage value is equal to the input DC voltage value;

The excitation and discharge main circuit consists of a sixth switch tube, a seventh switch tube, an eighth switch tube, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, and a capacitor Composition, wherein, the anode of the sixth switching tube is used as the input positive terminal of the excitation and discharge main circuit, the cathode of the sixth switching tube is connected to the cathode of the second diode and one end of the first inductor, and the other end of the first inductor is connected to The anode of the seventh switching tube is connected to the anode of the third diode, and the cathode of the third diode is connected to the positive pole of the capacitor and one end of the second inductance as an output positive terminal of the excitation and discharge main circuit. The other end of the inductance is connected to the cathode of the fourth diode and the cathode of the eighth switch tube, the anode of the eighth switch tube is used as the discharge input end of the excitation and discharge main circuit and connected to the output positive terminal of the inverter main circuit, and the second diode The anode of the tube, the cathode of the seventh switch tube, the negative pole of the capacitor, and the anode of the fourth diode are short-circuited and used as the input and output negative terminals of the excitation and discharge main circuit.

A control method for a switched reluctance wind power generator converter, which is divided into three types of working modes:

The first type of working mode, when the load of the generator set suddenly increases, or when the generator starts, or the maximum power tracking, etc., it is necessary to quickly strengthen the excitation, that is, to quickly strengthen the input current of the main circuit of the converter to improve the power output capacity of the generator set. , this type of working mode is divided into two types:

(1) According to the position of the rotor of the switched reluctance generator, the first switching tube, the third switching tube, and the fourth switching tube of the inverter branch connected to the phase winding to be worked are closed, and the second switching tube and the fifth switching tube are turned off. Open, the sixth switch tube is closed, the eighth switch tube is turned off, the seventh switch tube works in PWM control mode, and its duty cycle is adjusted according to the current value demand of the control system for the working phase winding. It is the excitation stage of the phase winding of the switched reluctance generator. When the generator rotor position detection situation reaches the end position of the excitation stage, the first switch tube, the third switch tube, and the fourth switch tube are disconnected, and the fifth switch tube is closed. Enter the power generation stage, and when the power generation stage ends according to the position of the generator rotor, disconnect the fifth switching tube, and the winding of this phase ends;

(2) In the above first type of working mode (1), even if the excitation and discharge main circuit can reach the maximum output voltage under the adjustment of the duty ratio of the seventh switching tube, it still cannot make the phase winding at the end of the excitation phase of the generator The current meets the demand and enters this working mode: the action mode of each switch tube at the beginning of the excitation phase is the same as that of the first type of working mode (1) at the beginning of the excitation phase, and when the excitation phase is about to end, it is 10% earlier When the original excitation time detects that the winding current cannot reach 80% of the required excitation current, the first switching tube, the third switching tube, and the fourth switching tube are disconnected at this time, and the second switching tube is closed, so that the phase winding enters the freewheeling stage, thereby In the case of no reverse voltage, the current of the phase winding increases rapidly. When it reaches the beginning of the power generation stage, the second switching tube is turned off, and the fifth switching tube is closed at the same time, and the same power generation as the first type (1) of the working mode is entered. phase, if the phase winding current has met the demand during the freewheeling phase before the power generation phase, enter the power generation phase in advance;

In this type of working mode, the sixth switch tube is always closed, the eighth switch tube is always kept open, the second switch tube is only closed during the freewheeling stage, the first switch tube, the third switch tube, and the fourth switch tube are closed. The tube is only closed during the excitation phase, and the fifth switch tube is closed only during the power generation phase;

In the second type of working mode, when the speed and output power of the wind turbine are within the range of ±10% of their respective rated values:

The first switching tube, the second switching tube, the third switching tube, and the eighth switching tube are always in the off state, there is no freewheeling phase during the working period, and the excitation directly enters the power generation phase; according to the detection result of the generator rotor position, a certain transformer is required When the current branch is put into operation, the fourth switch tube of the current conversion branch is closed and enters the excitation stage first, and the switching states of the sixth switch tube and the seventh switch tube of the excitation and discharge main circuit are adjusted according to the following principle: according to the required winding Current situation, when the excitation voltage is required, that is, the output voltage of the excitation and discharge main circuit is reduced relative to the bus voltage, that is, the output voltage of the converter main circuit, the seventh switching tube is turned off, and the sixth switching tube works in accordance with the PWM control mode. The specific duty cycle is based on The required winding current closed-loop control needs to be determined; when the excitation voltage is required to increase relative to the bus voltage, that is, to increase the winding current, the sixth switch tube is closed, and the seventh switch tube works according to the PWM control mode. The specific duty cycle depends on the required winding current closed-loop control. The control needs to be determined; when the sixth switch tube is always closed and the seventh switch tube is always open during the excitation phase, the winding current at the end of the excitation phase is just within the error range that meets the demand value, and PWM control is not performed;

The third type of working mode, when the load at the output end of the wind turbine suddenly decreases, or the high-speed bus voltage of the generator set is too high, etc., it is necessary to reduce the output power of the wind turbine, that is, reduce the excitation voltage, enter this type of working mode:

In this type of working mode, the first switch tube, the second switch tube, the third switch tube, and the seventh switch tube are always in the disconnected state. According to the rotor position, the fourth switch tube is closed when the excitation stage of the pre-working converter branch comes, and the fourth switch tube is closed. The six switching tubes adopt the PWM control method, and the output excitation voltage of the excitation and discharge main circuit is changed through the adjustment of its duty ratio. According to the rotor position, after the excitation phase is over, the fourth switching tube is turned off and the fifth switching tube is closed to enter the power generation phase. When the power generation stage of the converter branch that has just finished working is completed, the voltage across the output bus capacitor for power generation output rises, or when the voltage across the output bus capacitor exceeds the rated bus voltage by 5% or more, the subsequent converter branch is excited. During the stage, the duty cycle of the sixth switch tube is adjusted proportionally to become smaller. During this period, the eighth switch tube is closed to discharge the electric energy on both sides of the output bus capacitor to the second inductor. When it is detected that the current of the discharge circuit reaches the limit value, the switch tube turns off the second switch tube. Eight switching tubes.

Technical effect of the present invention mainly contains:

(1) Two ways to achieve enhanced excitation can be superimposed and used to achieve a strong combination, that is, in the excitation stage, the first switch tube and the third switch tube are closed, the sixth switch tube is closed, and the seventh switch tube is controlled by PWM, and then When the fourth switching tube is closed and enters the excitation stage, each set of windings of the excited phase windings bears the entire excitation voltage value, and the excitation voltage is relatively doubled, while the excitation and discharge main circuit works in boost mode, that is, the output excitation voltage The mode in which the voltage is greater than the bus voltage strengthens the excitation, thereby improving the rapid power generation output capability of the entire power generation system.

(2) The setting of the second switching tube in the converter structure of the present invention, when the excitation current, that is, the phase winding current before the power generation stage, cannot reach the required value, closing the second switching tube increases a freewheeling stage without back pressure, The winding current can be rapidly increased in a short period of time, thereby increasing the initial winding current in the power generation stage, which is conducive to improving the power output capability of the power generation system.

(3) For the structure of the main circuit of the converter, you can choose the enhanced excitation (i.e. the first switch and the third switch closed excitation) working mode according to the needs, or you can choose the normal excitation (i.e. the first The switching tube and the third switching tube are disconnected (excitation) mode, which broadens the adaptability of the converter to external conditions.

(4) Under the excitation structure and its control method of the present invention, that is, under the excitation and discharge main circuit and its control method, not only the decoupling of the generating bus voltage and the excitation voltage is realized, but also the adjustment range of the excitation voltage is wide, and the excitation voltage can also be kept The voltage stability is equal to the bus voltage.

(5) In the discharge link of the present invention, when the load is too small, the wind force is too large, or the speed is too high, etc., and the converter does not need too much energy, it can quickly discharge and provide relevant protection measures, and the second After the inductance absorbs and discharges electric energy, after the eighth switching tube discharges for a period of time and is turned off, the electric energy stored in the second inductance can be fed back to charge the capacitor, so that the electric energy can be effectively used for the work of the subsequent excitation stage without waste, and the entire power generation can be improved. System effectiveness and efficiency.

(6) It can be seen from the working mode of the present invention that, unless in relatively extreme circumstances, otherwise, when working near the rated area, the first switching tube, the second switching tube, and the third switching tube are normally open switching states, If it is not easy to close and work, the switching loss and on-state loss of these switching tubes are generally small, and the other switching tubes often appear in the disconnected state, and most of the switching tubes work in single-pulse switching mode. Therefore, although this The structure of the invention requires a large number of switch tubes, but the resulting increase in loss is not obvious.

Description of drawings

Fig. 1 shows the circuit structure diagram of the switched reluctance wind generator converter of the present invention.

In Fig. 1: 1. Converter main circuit, 2. Isolated DC/DC converter, 3. Excitation and discharge main circuit.

detailed description

A switched reluctance wind power generator converter. Accompanying drawing 1 is a circuit structure diagram of the converter of the present invention, which consists of a converter main circuit 1, an output bus capacitor Cm, an isolated DC/DC converter 2, an excitation and discharge main The circuit 3 is composed of the positive and negative ends of the output of the main converter circuit 1 connected to the positive and negative ends of the output bus capacitor Cm, and at the same time as the positive and negative ends of the input of the isolated DC/DC converter 2, and the output of the isolated DC/DC converter 2 The positive and negative ends are connected to the positive and negative ends of the excitation and discharge main circuit 3 input, the positive and negative ends of the excitation and discharge main circuit 3 output are connected to the positive and negative ends of the inverter main circuit 1 input, and the positive and negative ends of the output of the inverter main circuit 1 are also connected The discharge input terminal of the excitation and discharge main circuit 3, the positive terminal of the output of the main excitation and discharge circuit 3, the negative terminal of the output of the main converter circuit 1, and the positive terminal of the input of the main converter circuit 1 are short-circuited.

The switched reluctance generator of this embodiment is a four-phase 8/6-pole double-set winding type, and its main converter circuit 1 is composed of four converter branches connected in parallel, and each converter branch is internally connected to a switched reluctance generator Each phase winding contains two sets of windings, which are connected separately. Specifically, each branch is composed of the first set of windings M1/N1/P1/Q1 and the second set of windings M2/N2/P2/Q2 , the first switching tube V1/V6/V11/V16, the second switching tube V2/V7/V12/V17, the third switching tube V3/V8/V13/V18, the fourth switching tube V4/V9/V14/V19, the Five switching tubes V5/V10/V15/V20 and the first diode D1/D2/D3/D4, wherein one end of the first set of winding M1/N1/P1/Q1, the first switching tube V1/V6/V11/ The anode of V16 and the cathode of the second switch tube V2/V7/V12/V17 are short-circuited and used as the input positive terminal of the main converter circuit 1, and the cathode of the first switch tube V1/V6/V11/V16 is connected to the first diode D1/D2/ D3/D4 cathode and one end of the second set of winding M2/N2/P2/Q2, the other end of the first set of winding M1/N1/P1/Q1 is connected to the anode of the first diode D1/D2/D3/D4 and the third switch tube The anode of V3/V8/V13/V18, the other end of the second set of winding M2/N2/P2/Q2 is connected to the cathode of the third switching tube V3/V8/V13/V18, the anode of the fourth switching tube V4/V9/V14/V19, the The anode of the second switch tube V2/V7/V12/V17, the anode of the fifth switch tube V5/V10/V15/V20, the cathode of the fourth switch tube V4/V9/V14/V19 as the input negative terminal of the inverter main circuit 1, the fifth switch The cathode of the tube V5/V10/V15/V20 is used as the output positive terminal of the main converter circuit 1.

The isolated DC/DC converter 2 includes an electromagnetic isolation link, and its output DC voltage value is equal to the input DC voltage value, that is, it functions as electromagnetic isolation and filtering at both ends of the input and output.

Excitation and discharge main circuit 3 is composed of sixth switch tube V21, seventh switch tube V22, eighth switch tube V23, second diode D5, third diode D6, fourth diode D7, first inductor L1 , the second inductor L2, and a capacitor C, wherein the anode of the sixth switch tube V21 is used as the positive terminal of the excitation and discharge main circuit 3 input, the cathode of the sixth switch tube V21 is connected to the cathode of the second diode D5, and one end of the first inductor L1 , the other end of the first inductor L1 is connected to the anode of the seventh switch tube V22 and the anode of the third diode D6, the cathode of the third diode D6 is connected to the positive electrode of the capacitor C, and one end of the second inductor L2 is used as the excitation and discharge main circuit 3 Output the positive terminal, the other end of the second inductance L2 is connected to the cathode of the fourth diode D7 and the cathode of the eighth switching tube V23, and the anode of the eighth switching tube V23 is used as the discharge input terminal of the excitation and discharge main circuit 3 to connect to the converter main circuit 1 The positive terminal of the output, the anode of the second diode D5, the cathode of the seventh switch tube V22, the negative terminal of the capacitor C, and the anode of the fourth diode D7 are short-circuited and used as the input and output negative terminals of the excitation and discharge main circuit 3 .

According to the structure of the converter and its control system of this embodiment, the control methods are divided into three types of working modes, which are selected according to the requirements of the control system under different loads and different working conditions.

The first type of working mode is to cut in when the load of the generator set suddenly increases, or at the stage of generator start-up, or when the maximum power tracking needs to quickly strengthen the excitation, that is, to quickly strengthen the input current of the converter main circuit to improve the power output capacity of the generator set. There are two types of working modes:

(1) According to the rotor position of the switched reluctance generator, assuming that the M-phase winding has the working conditions, first control the first switching tube V1, the third switching tube V3, and the fourth switching tube V4 to close, and the second switching tube V2, the fifth switching tube The switch tube V5 is turned off, the sixth switch tube V21 is closed, the eighth switch tube V23 is turned off, the seventh switch tube V22 works in a PWM control mode, and its duty cycle is adjusted according to the current value demand in the M-phase winding. The above stage is the excitation stage of the phase winding of the switched reluctance generator. In this stage, since the sixth switch tube V21 is always closed, the first inductor L1 is charged when the seventh switch tube V22 is closed, and the capacitor C provides excitation to the M phase winding. voltage, and when the seventh switching tube V22 is turned off, the first inductor L1 and the capacitor C jointly provide the excitation voltage to the M-phase winding, which has the effect of enhancing the excitation; in addition, the first switching tube V1 and the third switching tube V3 After the excitation is closed, the excitation voltage borne by each set of windings of M1 and M2 is respectively equal to the output voltage of the excitation and discharge main circuit 3. If the excitation of the first switching tube V1 and the third switching tube V3 is off, then M1 and M2 The excitation voltage at both ends of each set of windings is only half of the output voltage value of the excitation and discharge main circuit 3, so that the voltage of the windings in the excitation stage of the converter branch of this mode is doubled;

When the position of the generator rotor reaches the end position of the excitation phase, the first switching tube V1, the third switching tube V3, and the fourth switching tube V4 are disconnected, and the fifth switching tube V5 is closed to enter the power generation phase. When the rotor position reaches the end of the power generation phase, the fifth switching tube V5 is turned off, and the M-phase winding ends its work.

(2) In the above first type of operation mode (1), even if the excitation and discharge main circuit 3 can reach the maximum output voltage under the adjustment of the duty ratio of the seventh switching tube V22, it still cannot make the excitation phase of the generator end. The current of the phase winding meets the demand, and the subsequent phase winding that enters the working state enters this working mode, assuming that it is the converter branch where the N-phase winding is located: at the beginning of the excitation phase, it is the same as the first working mode (1) working mode At the beginning of the excitation phase, the action modes of the switching tubes are the same. When the excitation phase is about to end, the original excitation time 10% ahead of time detects that the winding current cannot reach 80% of the required excitation current. At this time, the first switching tube V6 and the third switching tube are disconnected. The switching tube V8 and the fourth switching tube V9 close the second switching tube V7, so that the phase winding enters the freewheeling stage. At this time, the current loop of the N-phase winding is N1-D2-N2-V7-N1, so the N-phase winding has no external In the reverse voltage (the bus voltage will give the winding a reverse voltage during the power generation stage), the current of the loop winding will increase more quickly. When it reaches the beginning of the power generation stage, the second switch tube V7 will be disconnected, and the fifth switch will be closed at the same time The tube V10 enters the same power generation stage as the first mode (1) of the first working mode. If the phase winding current has met the demand during the freewheeling stage before the power generation stage starts, it will enter the power generation stage in advance.

In this type of working mode, the sixth switch tube V21 is always closed, the eighth switch tube V23 is always kept open, the second switch tube V2/V7/V12/V17 is only closed during the freewheeling phase, and the first switch tube V1/V6/V11/V16, the third switch tube V3/V8/V13/V18, the fourth switch tube V4/V9/V14/V19 are only closed during the excitation phase, the fifth switch tube V5/V10/V15/V20 Closed only during the generating phase.

In the second type of working mode, when the speed and output power of the wind generator set are within the range of ±10% of their respective rated values:

According to the position of the rotor, when the M-phase winding needs to enter the working state, the first switching tube V1, the second switching tube V2, the third switching tube V3, and the eighth switching tube V23 of the converter branch are always in the off state. There is no freewheeling phase, and the excitation ends and it directly enters the power generation phase; when the excitation starts, the fourth switching tube V4 is closed and first enters the excitation phase, and the switching states of the sixth switching tube V21 and the seventh switching tube V22 are adjusted according to the following principles: according to the required winding current When the excitation voltage is required, that is, the output voltage of the excitation and discharge main circuit 3 is reduced relative to the bus voltage, that is, the output voltage of the converter main circuit, the seventh switch tube V22 is turned off, and the sixth switch tube V21 works according to the PWM control mode. At this time, the excitation The voltage is lower than the bus voltage, and the specific excitation voltage, that is, the duty ratio of the sixth switch tube V21 needs to be adjusted according to the required winding current closed-loop control; when the excitation voltage is required to increase relative to the bus voltage, that is, to increase the winding current, the sixth switch tube V21 is closed , the seventh switch tube V22 works according to the PWM control mode. Under this working condition, the excitation voltage will be greater than the bus voltage, and the specific duty cycle is adjusted according to the required winding current closed-loop control; When the switch tube V22 is always off, the winding current at the end of the excitation phase is just within the error range of the required value, and no PWM control is performed.

The third type of working mode, when the load at the output end of the wind turbine suddenly decreases, or the high-speed bus voltage of the generator set is too high, etc., it is necessary to reduce the output power of the wind turbine, that is, reduce the excitation voltage, enter this type of working mode:

In this type of working mode, the first switch tube V1/V6/V11/V16, the second switch tube V2/V7/V12/V17, the third switch tube V3/V8/V13/V18, and the seventh switch tube V22 are always off According to the rotor position, it is assumed that the fourth switch tube V4 is closed when the excitation phase of the converter branch of the M-phase winding comes, and the sixth switch tube V21 adopts PWM control mode. At this time, the excitation voltage will be smaller than the bus voltage, specifically through its duty cycle The regulation changes, the smaller the demand for the excitation voltage is, the smaller the duty cycle is. According to the rotor position, after the excitation phase is over, the fourth switch tube V4 is turned off and the fifth switch tube V5 is closed to enter the power generation phase. When the power generation phase is over, it makes When the voltage across the output bus capacitor Cm of the power generation output rises, or when the voltage across the output bus capacitor Cm exceeds the rated bus voltage by 5%, the sixth switching tube in the subsequent work, such as the excitation stage of the N-phase winding converter branch The duty cycle of V21 is proportionally adjusted to become smaller. During this period, the eighth switch tube V23 is closed to discharge the electric energy on both sides of the output bus capacitor Cm to the second inductor L2, and the bus voltage decreases. When it is detected that the discharge circuit current reaches the limit value, Turn off the eighth switch tube V23.

Claims (2)

1. A switched reluctance wind-driven generator converter is composed of a main circuit for converting, an output busbar capacitor, an isolated DC/DC converter, an excitation and discharging main circuit, and is characterized in that the main circuit for converting is output positive The negative ends are connected to the positive and negative ends of the output bus capacitor, and at the same time as the positive and negative ends of the input of the isolated DC/DC converter, the positive and negative ends of the output of the isolated DC/DC converter are connected to the excitation and discharge The positive and negative terminals of the input of the main circuit, the positive and negative terminals of the output of the excitation and discharge main circuit are connected to the positive and negative terminals of the input of the inverter main circuit, and the positive terminals of the output of the inverter main circuit are also connected to the discharge input of the excitation and discharge main circuit. The positive output terminal of the discharge main circuit, the negative output terminal of the inverter main circuit, and the positive input terminal of the inverter main circuit are short-circuited; The converter main circuit is composed of three or four converter branches connected in parallel, and each converter branch is internally connected to a phase winding of the switched reluctance generator, and each phase winding contains two sets of windings, which are connected separately, specifically For example, each converter branch is composed of the first set of windings, the second set of windings, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, and the first diode , wherein one end of the first set of windings, the anode of the first switch tube, and the cathode of the second switch tube are short-circuited and used as the input positive terminal of the inverter main circuit, and the cathode of the first switch tube is connected to the first diode tube cathode and one end of the second set of windings, the other end of the first set of windings is connected to the anode of the first diode and the anode of the third switching tube, the other end of the second set of windings is connected to the cathode of the third switching tube, the fourth The anode of the switching tube, the anode of the second switching tube, the anode of the fifth switching tube, the cathode of the fourth switching tube is used as the input negative terminal of the inverter main circuit, and the cathode of the fifth switching tube is used as the output positive terminal of the inverter main circuit; The isolated DC/DC converter includes an electromagnetic isolation link, and its output DC voltage value is equal to the input DC voltage value; The excitation and discharge main circuit consists of a sixth switch tube, a seventh switch tube, an eighth switch tube, a second diode, a third diode, a fourth diode, a first inductor, a second inductor, and a capacitor Composition, wherein, the anode of the sixth switching tube is used as the input positive terminal of the excitation and discharge main circuit, the cathode of the sixth switching tube is connected to the cathode of the second diode and one end of the first inductor, and the other end of the first inductor is connected to The anode of the seventh switching tube is connected to the anode of the third diode, and the cathode of the third diode is connected to the positive pole of the capacitor and one end of the second inductance as an output positive terminal of the excitation and discharge main circuit. The other end of the inductance is connected to the cathode of the fourth diode and the cathode of the eighth switch tube, the anode of the eighth switch tube is used as the discharge input end of the excitation and discharge main circuit and connected to the output positive terminal of the inverter main circuit, and the second diode The anode of the tube, the cathode of the seventh switch tube, the negative pole of the capacitor, and the anode of the fourth diode are short-circuited and used as the input and output negative terminals of the excitation and discharge main circuit. 2. A control method for a switched reluctance wind generator converter, which is divided into three types of operating modes, characterized in that: The first type of working mode, when the load of the generator set suddenly increases, or when the generator starts, or the maximum power tracking, etc., it is necessary to quickly strengthen the excitation, that is, to quickly strengthen the input current of the main circuit of the converter to improve the power output capacity of the generator set. , this type of working mode is divided into two types: (1) According to the position of the rotor of the switched reluctance generator, the first switching tube, the third switching tube, and the fourth switching tube of the inverter branch connected to the phase winding to be worked are closed, and the second switching tube and the fifth switching tube are turned off. Open, the sixth switch tube is closed, the eighth switch tube is turned off, the seventh switch tube works in PWM control mode, and its duty cycle is adjusted according to the current value demand of the control system for the working phase winding. It is the excitation stage of the phase winding of the switched reluctance generator. When the generator rotor position detection situation reaches the end position of the excitation stage, the first switch tube, the third switch tube, and the fourth switch tube are disconnected, and the fifth switch tube is closed. Enter the power generation stage, and when the power generation stage ends according to the position of the generator rotor, disconnect the fifth switching tube, and the winding of this phase ends; (2) In the above first type of working mode (1), even if the excitation and discharge main circuit can reach the maximum output voltage under the adjustment of the duty ratio of the seventh switching tube, it still cannot make the phase winding at the end of the excitation phase of the generator The current meets the demand and enters this working mode: the action mode of each switch tube at the beginning of the excitation phase is the same as that of the first type of working mode (1) at the beginning of the excitation phase, and when the excitation phase is about to end, it is 10% earlier When the original excitation time detects that the winding current cannot reach 80% of the required excitation current, the first switching tube, the third switching tube, and the fourth switching tube are disconnected at this time, and the second switching tube is closed, so that the phase winding enters the freewheeling stage, thereby In the case of no reverse voltage, the current of the phase winding increases rapidly. When it reaches the beginning of the power generation stage, the second switching tube is turned off, and the fifth switching tube is closed at the same time, and the same power generation as the first type (1) of the working mode is entered. phase, if the phase winding current has met the demand during the freewheeling phase before the power generation phase, enter the power generation phase in advance; In this type of working mode, the sixth switch tube is always closed, the eighth switch tube is always kept open, the second switch tube is only closed during the freewheeling stage, the first switch tube, the third switch tube, and the fourth switch tube are closed. The tube is only closed during the excitation phase, and the fifth switch tube is closed only during the power generation phase; In the second type of working mode, when the speed and output power of the wind turbine are within the range of ±10% of their respective rated values: The first switching tube, the second switching tube, the third switching tube, and the eighth switching tube are always in the off state, there is no freewheeling phase during the working period, and the excitation directly enters the power generation phase; according to the detection result of the generator rotor position, a certain transformer is required When the current branch is put into operation, the fourth switch tube of the current conversion branch is closed and enters the excitation stage first, and the switching states of the sixth switch tube and the seventh switch tube of the excitation and discharge main circuit are adjusted according to the following principle: according to the required winding Current situation, when the excitation voltage is required, that is, the output voltage of the excitation and discharge main circuit is reduced relative to the bus voltage, that is, the output voltage of the converter main circuit, the seventh switching tube is turned off, and the sixth switching tube works in accordance with the PWM control mode. The specific duty cycle is based on The required winding current closed-loop control needs to be determined; when the excitation voltage is required to increase relative to the bus voltage, that is, to increase the winding current, the sixth switch tube is closed, and the seventh switch tube works according to the PWM control mode. The specific duty cycle depends on the required winding current closed-loop control. The control needs to be determined; when the sixth switch tube is always closed and the seventh switch tube is always open during the excitation phase, the winding current at the end of the excitation phase is just within the error range that meets the demand value, and PWM control is not performed; The third type of working mode, when the load at the output end of the wind turbine suddenly decreases, or the high-speed bus voltage of the generator set is too high, etc., it is necessary to reduce the output power of the wind turbine, that is, reduce the excitation voltage, enter this type of working mode: In this type of working mode, the first switch tube, the second switch tube, the third switch tube, and the seventh switch tube are always in the disconnected state. According to the rotor position, the fourth switch tube is closed when the excitation stage of the pre-working converter branch comes, and the fourth switch tube is closed. The six switching tubes adopt the PWM control method, and the output excitation voltage of the excitation and discharge main circuit is changed through the adjustment of its duty ratio. According to the rotor position, after the excitation phase is over, the fourth switching tube is turned off and the fifth switching tube is closed to enter the power generation phase. When the power generation stage of the converter branch that has just finished working is completed, the voltage across the output bus capacitor for power generation output rises, or when the voltage across the output bus capacitor exceeds the rated bus voltage by 5% or more, the subsequent converter branch is excited. During the stage, the duty cycle of the sixth switch tube is adjusted proportionally to become smaller. During this period, the eighth switch tube is closed to discharge the electric energy on both sides of the output bus capacitor to the second inductor. When it is detected that the current of the discharge circuit reaches the limit value, the switch tube turns off the second switch tube. Eight switches.