CN112003517A

CN112003517A - Two-stage brushless electric excitation starting power generation system topology and control strategy thereof

Info

Publication number: CN112003517A
Application number: CN202010711145.8A
Authority: CN
Inventors: 焦宁飞; 刘卫国; 张小科; 韩旭; 梁培鑫
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2020-07-22
Filing date: 2020-07-22
Publication date: 2020-11-27
Anticipated expiration: 2040-07-22
Also published as: CN112003517B

Abstract

The invention relates to a two-stage brushless electric excitation starting power generation system topology and a control strategy thereof. In the system starting stage, the power output end of the starting controller is connected with the exciter and a stator winding of the main motor to provide excitation for the exciter and drive the main motor to operate in an electric state to drive the aircraft engine to start; after the starting is finished, the starting controller is disconnected with the stator winding of the main motor, and excitation is not provided for the exciter any more; when the power generation stage is started, the armature winding of the stator of the main motor is connected with the airborne power system bus bar, the starting controller provides direct-current excitation for the exciter, after the input voltage of the to-be-generated control unit meets the excitation control requirement of the exciter, the excitation winding of the exciter is connected and switched to the output end of the power generation control unit from the starting controller, and the power generation control unit provides excitation for the exciter.

Description

Two-stage brushless electric excitation starting power generation system topology and control strategy thereof

Technical Field

The invention belongs to the field of motor systems, and particularly relates to a novel structural topology of a two-stage brushless electric excitation starting power generation system and a control strategy thereof.

Background

The aviation starting power generation system can save a special starting mechanism used for starting a traditional engine, reduce the volume and weight of the system and improve the integration level of the system, and is an important development trend of an aviation engine-power supply system. By virtue of excellent reliability and power generation quality, the three-stage starting power generation system becomes the key point of integrated research and application of aviation starting power generation. Research and application fields of European and American national research institutions on aviation three-stage starting power generation systems are always in the front of the world, and the aviation three-stage starting power generation systems are successfully applied to the Boeing 787 aircraft which is the highest level of the existing large multi-electric aircraft. In China, no installed application condition exists in an aviation three-stage starting power generation system, and the system is still in the stages of basic theory exploration and key technology attack.

The three-stage brushless synchronous generator consists of an auxiliary exciter, an exciter, a rotating rectifier, a main generator and a power generation control unit. The auxiliary exciter is a low-power permanent magnet generator, and direct-current excitation is provided for the exciter through a GCU (general control unit); the exciter is a pivot type electric excitation generator and provides excitation current for the main motor through a rotating rectifier; the main motor is an electrically excited synchronous motor, and the engine drives the main motor to operate in a power generation state to supply power to the airborne equipment. The three motor rotors are coaxially arranged, and the rotating rectifier is also arranged on the rotor side to form a rotating part of the system. The significance that the three-level brushless synchronous generator needs a three-level structure is as follows: in order to realize the brushless performance and the adjustable exciting current of a main motor (an electric excitation synchronous motor), an exciter (an electric excitation generator) and a rotary rectifier are added to provide the adjustable exciting current for a rotor winding of the main motor; in order to eliminate external power supply of the exciter to realize the generator system as an independent power generation source, a secondary exciter (permanent magnet generator) is added to provide excitation for the exciter through a power generation control unit.

From the structure and the operation principle of the three-stage brushless synchronous generator, the advantages of the application of the motor system in the aviation big aircraft are as follows: 1) when short circuit fault occurs to the motor or load, direct de-excitation of the main motor can be realized by cutting off excitation of the exciter, so that fault spreading is prevented, and reliability is high. 2) The exciting current of the main motor can be adjusted in real time through the excitation control of the exciter, the system power factor is high, and the power generation quality is good. 3) The advantage that the exciting current of the main motor is convenient to adjust enables the system to be applicable to various aviation power systems, including variable speed variable frequency systems, constant speed constant frequency systems, high voltage direct current systems and the like, and the applicability is wide.

On the basis of a three-stage brushless synchronous generator, a three-stage starting power generation system can be realized by adding a starting function. Compared with a pure generator, the three-stage starting power generation system is additionally provided with a starting controller, wherein the starting controller is used for system starting control. In the starting stage of the system, the exciter is subjected to alternating current excitation (or is directly excited by an external alternating current power supply) by the starting controller, and the auxiliary exciter is not connected to the system; the main motor is controlled in an electric running mode by a starting controller, and the aero-engine is driven to start by output torque. After the start is completed, the system is switched to a state consistent with a simple generator structure through start/power generation switching. Therefore, the three-stage starting power generation system realizes the integration of starting and power generation on the basis of keeping the advantages of high reliability and high quality power generation of the three-stage brushless synchronous generator. However, the configuration structure is complex, the volume and the weight are large, the power density of the system is influenced, and optimization and improvement are urgently needed.

Disclosure of Invention

Technical problem to be solved

The relatively complex structural topology of the traditional three-stage starting power generation system directly influences the power density and reliability of the system. In order to improve the power density and high reliability of a starting power generation system, the structural topology and the control strategy of the traditional three-stage starting power generation system need to be redesigned on the premise of ensuring that the starting function and the power generation characteristic of the system meet the requirements, so that the requirements of high power density and high reliability in aviation application can be better met.

Technical scheme

A two-stage brushless electric excitation starting power generation system topology comprises an exciter, a rotary rectifier, a main motor, a starting controller and a power generation control unit, and is characterized by further comprising a No. 1 switch and a No. 2 switch, wherein the No. 1 switch is connected with an exciter stator excitation winding, the No. 1 switch is provided with two contacts E1 and E2, an E1 contact is connected with the output of the power generation control unit, and an E2 contact is connected with the excitation control output of the starting controller; the No. 2 switch is connected with a stator armature winding of a main motor, the No. 2 switch is provided with two contacts G1 and G2, a G1 contact is connected with a starting control output of the main motor of the starting controller, a G2 contact is connected with an onboard power system bus bar, and the input side of the power generation control unit is connected with a G2 contact of the No. 2 switch.

The types of the No. 1 switch and the No. 2 switch comprise: relays, contactors, power electronic switching devices.

The exciter types include: single-phase exciter, two-phase exciter, three-phase exciter.

A control strategy of a two-stage brushless electric excitation starting power generation system topology is characterized by comprising the following steps:

step 1: in the starting stage, the starting controller is powered by an external power supply, the E2 contact of the No. 1 switch is connected with the starting controller, and the G1 contact of the No. 2 switch is connected with the starting controller, namely, an exciter stator exciting winding and a main motor stator armature winding are connected to the output end of the starting controller; the starting controller outputs alternating current or direct current to provide excitation for the exciter on one hand, and inputs variable frequency alternating current for the main motor according to the rotating speed of the motor and the position of the rotor on the other hand, so that the main motor generates electromagnetic torque to drive the aircraft engine to start;

step 2: after the starting is finished, namely the aeroengine reaches the starting finishing rotating speed; the E2 contact of the No. 1 switch is continuously connected with the starting controller, and the G1 contact of the No. 2 switch is disconnected and in a suspended state, namely the starting controller is disconnected with the armature winding of the main motor and continuously connected with the excitation winding of the exciter; at the moment, the starting controller does not supply power to the exciter any more, and the starting power generation system is driven by the aircraft engine to accelerate to a system power generation stage;

and step 3: when the system enters a power generation stage, namely the aero-engine reaches the power generation operation rotating speed; the E2 contact of the No. 1 switch is continuously connected with the starting controller, and the No. 2 switch is switched to the G2 contact, namely the armature winding of the main motor is connected with the power generation control unit; at the moment, the starting controller provides direct-current exciting current for the exciter again, and after the input voltage of the control unit to be generated reaches the exciting control requirement of the exciter, the No. 1 switch is switched from the E2 contact to the E1 contact, namely, the exciting winding of the exciter is disconnected with the starting controller and is connected with the output of the generation control unit; and finally, the system completely enters a power generation stage, and the power generation control unit provides direct-current excitation for the exciter.

Advantageous effects

The two-stage brushless electric excitation starting power generation system topology provided by the invention removes the auxiliary exciter in the traditional three-stage brushless electric excitation motor topology, and brings advantages on the basis of keeping the advantages of high-reliability and high-quality power generation of the system, and the advantages are represented as follows: 1) the weight of the auxiliary exciter is directly reduced; 2) the weight of a structural component for mounting and fixing the auxiliary exciter is directly reduced; 3) the axial length of the motor system is shortened, and the motor system is easy to install; 4) the three motors are coaxially and serially mounted to be simplified into two motors which are coaxially and serially mounted, so that the complexity of the system is reduced; 5) the auxiliary exciter (permanent magnet motor) is removed, so that the system does not have a permanent magnet which is relatively fragile and easy to break down, and the reliability of the system is improved.

Drawings

FIG. 1 is a schematic diagram of a two-stage brushless electric excitation starting power generation system topology;

FIG. 2 is a schematic diagram of a two-stage brushless electric excitation starting power generation system based on a single-phase exciter;

fig. 3 is a schematic control flow diagram of a two-stage brushless electric excitation starting power generation system.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

the topological structure schematic diagram of the proposed two-stage brushless electric excitation starting power generation system is shown in fig. 1. The system consists of an exciter, a rotating rectifier, a main motor, a starting controller, a power generation control unit and a change-over switch, wherein the input end of the power generation control unit is connected with the power generation output end of a stator winding of the main motor. The starting controller is powered by an external power supply and mainly realizes the starting control of the system; the power generation control unit mainly realizes power generation control of the system. The structural functions of the exciter, the rotating rectifier, the main motor, the starting controller and the power generation control unit are the same as those of the traditional three-stage brushless electric excitation starting power generation system, and the invention content of the patent is not regarded.

The No. 1 switch connected with the exciter stator excitation winding is provided with two contacts, the E1 contact is connected with the output of the power generation control unit, and the E2 contact is connected with the excitation control output of the starting controller. The No. 2 switch connected with the armature winding of the main motor stator has two contacts, the G1 contact is connected with the starting control output of the main motor of the starting controller, and the G2 contact is connected with the bus bar of the onboard power system. The input side of the power generation control unit is also connected to the G2 contact of switch No. 2.

A two-stage brushless electrically-excited starting power generation system based on a single-phase exciter will be described in detail as an example, and its schematic configuration is shown in fig. 2. The system consists of an exciter, a rotating rectifier, a main motor, a starting controller, a power generation control unit and a change-over switch. The main motor is an electrically excited synchronous motor, the rotor winding is a single-phase excitation winding, and the stator winding is a three-phase armature winding; the rotary rectifier is a diode rectifier; the exciter is a pivot type generator, the rotor winding is a three-phase armature winding, and the stator winding is a single-phase excitation winding. The exciter and the rotor of the main motor are coaxially mounted, and the rotating rectifier is also mounted on the rotating shaft. The exciter rotor three-phase winding is connected with the input side of the rotary rectifier, and the main motor rotor winding is connected with the output side of the rotary rectifier. The input end of the power generation control unit is connected with the power generation output end of the main motor stator winding.

The No. 1 switch connected with the exciter stator exciting winding selects two paths of single-pole double-throw switches, the No. E1 contact is connected with the output of the power generation control unit, and the No. E2 contact is connected with the excitation control output of the starting controller. The No. 2 switch connected with the armature winding of the main motor stator selects a three-way single-pole double-throw switch, a G1 contact is connected with the starting control output of the main motor of the starting controller, a G2 contact is connected with an airborne load, and in addition, the input side of the power generation control unit is also connected with a G2 contact of the No. 2 switch.

The starting controller is powered by an external power supply and mainly realizes the starting control of the system; the power generation control unit mainly realizes power generation control of the system. The starting controller and the power generation control unit can select related hardware structures used in the three-stage starting power generation system.

For the two-stage brushless electric excitation starting power generation system based on the single-phase exciter shown in fig. 2, the flow diagram of the adopted control strategy is shown in fig. 3, and specifically includes:

(1) in the starting stage, the starting controller is powered by an external power supply, the No. 1 switch is connected with the E2 contact, and the No. 2 switch is connected with the G1 contact, namely the exciter stator exciting winding and the main motor stator armature winding are connected to the output end of the starting controller. The starting controller outputs 210V/200Hz single-phase alternating current to provide alternating current excitation for the single-phase winding of the exciter on one hand, and inputs variable-frequency alternating current for the main motor according to the rotating speed of the motor by adopting a vector control strategy on the other hand, so that the main motor generates electromagnetic torque to drive the aircraft engine to start.

(2) And after the starting power generation system accelerates the aeroengine to 4000r/min, the aeroengine is started completely. Switch No. 1 continues to be connected to the E2 contact, while switch No. 2 is disconnected from the G1 contact and is in a floating state, i.e., the start controller is disconnected from the main motor armature winding and continues to be connected to the exciter field winding. At the moment, the starting controller does not supply power to the exciter any more, and the starting power generation system is driven by the aircraft engine to accelerate to the system power generation stage.

(3) When the aero-engine drives the starting power generation system to accelerate to 8000r/min, the system enters a power generation stage. Switch No. 1 continues to be connected to the E2 contact and switch No. 2 to the G2 contact, i.e. the main motor armature winding is connected to the power generation control unit. At this time, the starting controller outputs 5A direct current to provide direct current excitation for the exciter exciting winding, and after the effective value of the input voltage of the control unit to be generated (namely the output voltage of the main motor stator winding) reaches 115V, the No. 1 switch is switched from the E2 contact to the E1 contact, namely the exciter exciting winding is disconnected with the starting controller and is connected with the output of the generation control unit. And then, starting the power generation system to completely enter a power generation stage, and performing closed-loop regulation on the exciter exciting current by the power generation control unit according to the output voltage of the main motor stator winding, so that the effective value of the output voltage of the main motor is stabilized at 115V.

Claims

1. A two-stage brushless electric excitation starting power generation system topology comprises an exciter, a rotary rectifier, a main motor, a starting controller and a power generation control unit, and is characterized by further comprising a No. 1 switch and a No. 2 switch, wherein the No. 1 switch is connected with an exciter stator excitation winding, the No. 1 switch is provided with two contacts E1 and E2, an E1 contact is connected with the output of the power generation control unit, and an E2 contact is connected with the excitation control output of the starting controller; the No. 2 switch is connected with a stator armature winding of a main motor, the No. 2 switch is provided with two contacts G1 and G2, a G1 contact is connected with a starting control output of the main motor of the starting controller, a G2 contact is connected with an onboard power system bus bar, and the input side of the power generation control unit is connected with a G2 contact of the No. 2 switch.

2. The two-stage brushless electrically excited starting power generation system topology of claim 1, wherein the type of switch No. 1 and switch No. 2 comprises: relays, contactors, power electronic switching devices.

3. A two-stage brushless electrically-excited start-up power generation system topology according to claim 1, wherein the exciter type comprises: single-phase exciter, two-phase exciter, three-phase exciter.

4. A control strategy of the two-stage brushless electrically excited starting power generation system topology of claim 1, characterized by the steps of: