CN108123646A - The fault-tolerant electricity generation system of electric excitation biconvex electrode electric machine excitation fault and its control method - Google Patents

Abstract

The invention discloses an electric excitation double salient pole motor excitation fault-tolerant power generation system and a control method thereof. The system consists of an electric excitation double salient pole motor, a fault-tolerant power converter, a controller, a position sensor, and a load side energy storage capacitor. And excitation side power supply. The control method is: disconnect the excitation circuit after detecting the excitation fault and switch to the fault-tolerant operation mode. In the fault-tolerant operation mode, the switching tube on the power converter is controlled to provide positive and negative excitation currents for each phase to realize the motor. Fault-tolerant power generation for excitation faults. The fault-tolerant power converter used in the control method disclosed in the present invention is the most commonly used full-bridge converter for electrically excited double salient pole motors, which significantly improves the power generation efficiency of electrically excited double salient pole motors in important occasions such as aerospace and automobiles. Reliable, electrically excited doubly salient motors suitable for multi-quadrant operation.

Description

Electric excitation doubly salient pole motor excitation fault-tolerant power generation system and its control method

technical field

The invention relates to an electric excitation double salient motor fault-tolerant power generation system and a control method thereof for excitation faults, belonging to the field of motor systems and controls.

Background technique

Electric excitation double salient pole motor is a new type of brushless DC motor that has been developed in recent years. The structure of its stator and rotor is similar to that of the switched reluctance motor. Centralized three-phase armature winding. The main difference between it and the switched reluctance motor is that there is an excitation winding on the stator for excitation. The existence of the excitation winding makes the electrically excited double salient pole motor and the switched reluctance motor fundamentally different. When the electric excitation double salient pole motor is running for power generation, only rectifier bridge is used for rectification, and there are no windings and permanent magnets on the rotor, so its power generation operation has high reliability, low cost, and high power density, and it can still maintain its power when operating under harsh conditions. High reliability, when the load or speed changes, the current of the excitation winding can be adjusted by the generator control unit to maintain a constant voltage output.

Aging, damp, heat, corrosion, foreign matter intrusion, impact of external force, etc. may cause damage to the excitation winding of the electric excitation doubly salient pole motor. At the same time, the excitation power circuit that controls the excitation winding may also fail due to overcurrent, reverse voltage impact, etc., and even cause the generator to lose its excitation in severe cases. If the electric excitation doubly salient motor has a loss of field failure during power generation, it will bring serious safety and reliability problems to the entire power generation system.

The electrically excited double salient pole motor is equivalent to a switched reluctance motor when the excitation winding fails, and the three-phase asymmetrical half-bridge converter used in the switched reluctance motor is not suitable for the electrically excited double salient pole motor. The power converter used by the excitation double salient pole motor is a three-phase full-bridge converter, so the authorized Chinese invention patent: electric excitation double salient pole motor excitation fault-tolerant power generation system and its control method, authorized announcement number: CN104579067A, proposed to use The three-phase four-leg converter is composed of a three-phase full-bridge converter and a fourth bridge arm to realize loss-of-excitation fault-tolerant power generation of an electrically excited double salient pole motor. Although the use of a three-phase four-leg converter can achieve loss-of-excitation fault-tolerant power generation, it requires an additional bridge arm compared to a three-phase full-bridge converter, which is bulky and expensive.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to propose a fault-tolerant power generation system for an electrically excited double salient motor based on the most commonly used three-phase full-bridge power converter for excitation faults. and its control methods. To achieve the above object, the present invention adopts the following technical solutions:

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

The control method of the electric excitation double salient pole motor excitation fault fault-tolerant power generation system, the current detection circuit detects the excitation current of the electric excitation double salient pole motor, and when no excitation fault is detected, the electric excitation double salient pole motor generates power according to the normal power generation mode; After the excitation fault is detected, the loss-of-excitation power generation control method is adopted, and the motor enters the fault-tolerant power generation operation mode of the excitation fault by controlling the switch tube on the three-phase full-bridge converter.

In the loss-of-excitation power generation control method, θ is set to represent the excitation opening angle of A phase, 0<θ<120°, and the direction of the current flowing into the midpoint of the winding is set as the positive direction. In the fault-tolerant operation mode, each phase of the motor operates between two Under the cycle, there are four states: positive excitation, positive power generation, negative excitation, and negative power generation. The source of the excitation current of each phase is divided into two parts, one part of the excitation current is provided by the current generation phase, and the other part of the excitation current is provided by The load side energy storage capacitor is provided.

In one inductance cycle, the described demagnetization power generation control method is specifically:

When the electrical angle of the motor is from θ to 120°, the switching tube S1 is controlled to conduct,

When the electrical angle of the motor is 120° to θ+120°, the switch tubes S1 and S4 are turned on, and the switch tube S1 is turned off when the electrical angle of the motor is equal to θ+120°;

When the electrical angle of the motor is θ+120° to 240°, the control switch S4 is turned on,

When the electrical angle of the motor is 240° to θ+240°, the switch tubes S4 and S5 are turned on, and when the electrical angle of the motor is equal to θ+240°, the switch tube S4 is turned off.

When the electrical angle of the motor is θ+240° to 360°, the control switch S5 is turned on,

When the electrical angle of the motor is 360° to θ+360°, the switching tubes S2 and S5 are controlled to be turned on, and when the electrical angle of the motor is equal to θ+360°, the switching tube S5 is turned off.

Electric excitation doubly salient motor excitation fault-tolerant fault-tolerant power generation system, the system includes an excitation-side power supply, a load-side energy storage capacitor, a fault-tolerant power converter, an electrically excited doubly salient motor, a controller and a position sensor; wherein, the The three-phase armature windings of the electrically excited double salient pole motor are star-connected, and the outlets of the A, B, and C phase windings are respectively connected to the fault-tolerant power converter; the excitation side power supply is connected to both ends of the excitation winding to provide the excitation current; The energy storage capacitor on the load side is connected in parallel with the load.

The fault-tolerant power converter is a three-phase full-bridge converter, which includes a first bridge arm formed by connecting the first and second IGBT switches S1-S2, and a bridge arm formed by connecting the third and fourth IGBT switches S3-S4. The second bridge arm, the third bridge arm formed by connecting the fifth and sixth IGBT switches S5-S6, the DC side of the converter is connected to both ends of the load, and the A, B, and C phase windings of the electrically excited double salient pole motor The outlet ends of the bridges are respectively connected to intermediate points on the first bridge arm, the second bridge arm and the third bridge arm.

The controller includes a voltage and current detection and conditioning circuit, a main control unit and an isolation drive circuit. The voltage and current detection and conditioning circuit collects the excitation winding current, the three-phase winding current and the load side terminal voltage, and the position sensor collects the rotor voltage. position signal, the main control unit processes the collected current, voltage and rotor position information, and provides drive signals for the switch tubes on the three-phase full-bridge circuit through the isolated drive circuit.

Compared with the prior art, the present invention adopts the above technical scheme and has the following technical effects:

The fault-tolerant power converter used in the present invention is the most commonly used three-phase full-bridge converter for electrically excited double salient motors, and is also the most widely used power converter for mainstream motor control today, with low price, high integration and mature technology The advantage of this invention is that it can not only drive the double salient pole motor with electric excitation for electric operation, but also enable the motor to generate electricity under normal excitation and excitation failure. The reliability of the electric excitation doubly salient pole motor suitable for multi-quadrant operation.

Description of drawings

Figure 1 is a general block diagram of an electric excitation double salient pole motor excitation fault-tolerant fault-tolerant power generation system;

Figure 2 shows the control law of the switching tube of the full bridge converter;

Figure 3 is a schematic diagram of the C-phase power generation circuit and the A-phase excitation circuit at θ-120°;

Figure 4 is a schematic diagram of the excitation circuit of the phase A winding at 120°-(θ+120°);

Figure 5 is a schematic diagram of the A-phase power generation circuit and the B-phase excitation circuit at (θ+120°)-240°;

Figure 6 is a schematic diagram of the excitation circuit of the B-phase winding at 240°-(θ+240°);

Figure 7 is a schematic diagram of the B-phase power generation circuit and the C-phase excitation circuit at (θ+240°)-360°;

Fig. 8 is a schematic diagram of the excitation circuit of the C-phase winding at 360°-(θ+360°).

Detailed ways

Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

A structural block diagram of an electric excitation double salient motor fault-tolerant power generation system for excitation failure according to the present invention is shown in Figure 1, which mainly includes an excitation side power supply, a load side energy storage capacitor, a three-phase full-bridge converter, an electric excitation double Salient pole motors, controllers and position sensors. The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

The three-phase armature windings of the electric excitation doubly salient motor are star-connected, the IGBT switches S ₁ -S ₂ in the three-phase full-bridge converter are connected to form bridge arm 1, and the connections S ₃ -S ₄ form bridge arm 2, S ₅ -S ₆ connections form the bridge arm 3, the DC side of the converter is connected to both ends of the load, and the outlet terminals of the A, B, and C phase windings of the electrically excited double salient pole motor are respectively connected to the converter bridge arm 1, bridge arm 2, and bridge arm 3. on arm 3. The power supply on the excitation side is connected to both ends of the excitation winding to provide the excitation current; the energy storage capacitor on the load side is connected in parallel with the load, which mainly plays the role of voltage stabilization and filtering in the case of normal power generation, and also plays the role of energy storage in the case of excitation fault power generation.

The controller in the fault-tolerant power generation system consists of voltage and current detection and conditioning circuits, a main control unit and an isolated drive circuit. The voltage and current detection and conditioning circuit collects the excitation winding current, the three-phase phase winding current and the load side terminal voltage, the position sensor collects the rotor position signal, the main control unit processes the collected current, voltage and rotor position information, and through the isolation drive circuit Provide driving signals for the switching tubes on the three-phase full-bridge circuit.

The current detection circuit detects the excitation current. When no excitation fault is detected, the electrically excited double salient pole motor generates power in the normal power generation mode; The switching tube of the electric excitation doubly salient motor enters the operation mode of excitation fault tolerance power generation.

In the fault-tolerant power generation operation mode, set θ to indicate the excitation opening angle of phase A, 0<θ<120°, and set the direction of current flowing into the midpoint of the winding as the positive direction.

As shown in Figure 2, when the electrical angle of the electrically excited doubly salient motor is from θ to 120°, the self-inductance of phase A is on the rise Phase C self-inductance is in the decline stage At this time, phase C is in the negative power generation state (the current of phase C flows out of the midpoint), and the back electromotive force of the phase C winding And greater than U _dc (the negative sign indicates that the current direction is the outflow midpoint), from the self-inductance change direction and the C-phase current direction, it can be judged that the e _c direction at this time is positive on the left and negative on the right as marked in Figure 3, and the inductance of phase B changes at this moment rate is 0, so e _b ≈ 0, so diodes D4 and D5 are turned on under positive pressure, forming a C-phase power generation circuit as shown by the solid line in Figure 3. At this time, the control switch S1 is turned on, and the A-phase winding forms a circuit through the switch S1, diode D5 and the C-phase winding, as shown by the dotted line in Fig. 3, this circuit is the excitation circuit of the A-phase winding, because in the In the excitation circuit, the direction of the phase A current flows into the midpoint, so it is called the positive excitation of the phase A winding. It can be seen from Figure 3 that part of the electric energy generated by phase C is positively excited by the winding of phase A, and part of it is provided to the load terminal through the power generation circuit of phase C.

When the electrical angle of the electrically excited double salient motor is 120° to θ+120°, the switching tubes S1 and S4 are controlled to be turned on. At this time, the change rate of the inductance of phase C is 0, the power generation process of phase C ends, and the current of phase B and C begins to decrease. Small, before the current decreases to 0, the above-mentioned excitation circuit still excites the A-phase winding. After the B-phase winding current drops to 0, the load-side energy storage capacitor continues to excite the A-phase winding, and the A-phase current continues to increase positively. Large, the excitation circuit is shown in Figure 4 of the accompanying drawings. When θ+120°, the switching tube S1 is turned off, after which the phase A excitation process ends, and the power generation state begins.

When the electrical angle of the electrically excited doubly salient motor is θ+120° to 240°, the phase B self-inductance is on the rise Phase A self-inductance is in the decline stage After the previous positive excitation, at this time, phase A is in the state of positive power generation (the current of phase A flows into the midpoint), and the back electromotive force of the phase A winding And it is greater than U _dc . From the change direction of the self-inductance and the current direction of phase A, it can be judged that the direction of e _a at this time is negative on the left and positive on the right as marked in Figure 5. At this moment, the change rate of the inductance of phase C is 0, so e _c ≈ 0, so The diodes D2 and D5 are turned on by the positive voltage, forming a phase A power generation circuit as shown by the solid line in Fig. 5 . At this time, the control switch S4 is turned on, and the B-phase winding forms a circuit through the switch S4, diode D2 and the A-phase winding, as shown by the dotted line in Figure 5. The B-phase current direction in the excitation circuit is the outflow midpoint, so it is called B-phase winding negative excitation. It can be seen from Figure 5 that part of the electric energy generated by phase A is negatively excited by the winding of phase B, and part of it is provided to the load terminal through the power generation circuit of phase A.

When the electrical angle of the electric excitation doubly salient motor is 240° to θ+240°, the switching tubes S4 and S5 are controlled to conduct. At this time, the inductance change rate of phase A is 0, the power generation process of phase A ends, and the current of phase A and C begins to decrease. Small, before the current decreases to 0, the above-mentioned excitation circuit still excites the B-phase winding. After the C-phase winding current drops to 0, the load-side energy storage capacitor continues to excite the B-phase winding, and the B-phase current continues to increase negatively. Large, the excitation circuit is shown in Figure 6 of the accompanying drawings. When the electrical angle θ+240°, the switching tube S4 is turned off, after which the B-phase excitation process ends, and it starts to enter the power generation state.

When the electrical angle of the electrically excited doubly salient motor is θ+240° to 360°, the phase C self-inductance is on the rise Phase B self-inductance is in the decline stage After the previous negative excitation, at this time, phase B is in the state of negative power generation (the current of phase B flows out of the midpoint), and the back electromotive force of the phase B winding And greater than U _dc (the negative sign indicates that the current direction is the outflow midpoint), from the self-inductance change direction and the B-phase current direction, it can be judged that the direction of e _b at this time is positive on the left and negative on the right as marked in Figure 7, and the inductance of phase A changes at this moment rate is 0, so e _a ≈ 0, so diodes D2 and D3 are turned on by positive pressure, forming a B-phase power generation circuit as shown by the solid line in Figure 3. At this time, the control switch S5 is turned on, and the C-phase winding forms a circuit through the switch S5, diode D3 and the B-phase winding, as shown by the dotted line in Figure 7. This circuit is the excitation circuit of the C-phase winding, because the C-phase In the excitation circuit, the direction of the C-phase current flows into the midpoint, so the C-phase winding is called positive excitation. It can be seen from Figure 7 that part of the electric energy generated by phase B is positively excited by the winding of phase C, and part of it is provided to the load terminal through the power generation circuit of phase B.

When the electrical angle of the electrically excited doubly salient motor is 360° to θ+360°, the switching tubes S2 and S5 are controlled to conduct. At this time, the change rate of the B-phase inductance is 0, the B-phase power generation process ends, and the B-phase and A-phase currents begin to decrease. Small, before the current decreases to 0, the above-mentioned excitation circuit still excites the C-phase winding. After the A-phase winding current drops to 0, the load-side energy storage capacitor continues to excite the C-phase winding, and the C-phase current continues to increase positively. Large, the excitation circuit is shown in Figure 8 of the accompanying drawings. When θ+360°, the switching tube S5 is turned off, after which the C-phase excitation process ends, and it starts to enter the power generation state.

In the next 360° electrical angle, the full-bridge converter can be controlled according to the above rules so that the three phases experience the positive power generation of phase C, the negative excitation of phase A, the negative power generation of phase A, the positive excitation of phase B, and the positive power generation of phase B. Phase C negative excitation, phase C negative power generation process. Under the control method of the present invention, since the current directions of the windings on two adjacent inductance cycles of each phase are opposite, the two inductance cycles with an electrical angle of 720° are used as a control cycle to drive the full-bridge converter according to the law shown in Figure 2 of the accompanying drawings. The switching tube and the cycle can realize the electric excitation double salient pole motor to continue to generate electricity under the excitation fault.

In the excitation stage, the magnitude of the excitation magnetic field can be controlled by chopper control of the excitation current of each phase, so that the output voltage can be controlled. It is also possible to control the length of the excitation time of each phase by controlling the initial excitation angle of each phase, so as to realize the control of the output voltage of the electrically excited double salient pole motor.

It can be understood that those skilled in the art can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention, and all these changes or replacements should belong to the protection scope of the appended claims of the present invention.

Claims (6)

1. The control method of the electric excitation double salient pole motor excitation fault-tolerant fault-tolerant power generation system, characterized in that the current detection circuit detects the excitation current of the electric excitation double salient pole motor, and when no excitation fault is detected, the electric excitation double salient pole motor follows Power generation in normal power generation mode; when an excitation fault is detected, the loss-of-excitation power generation control method is used to control the switching tube on the three-phase full-bridge converter to make the motor enter the excitation fault-tolerant power generation operation mode. 2. The control method of an electric excitation double salient pole motor excitation fault-tolerant fault-tolerant power generation system according to claim 1, characterized in that, the loss-of-excitation power generation control method sets θ to represent the excitation opening angle of phase A, and 0<θ<120 °, set the direction of the current flowing into the midpoint of the winding as the positive direction. In the fault-tolerant operation mode, each phase of the motor has four states of positive excitation, positive power generation, negative excitation, and negative power generation under two inductance cycles. The source of the excitation current of each phase is divided into two parts, one part of the excitation current is provided by the current generation phase, and the other part of the excitation current is provided by the load-side energy storage capacitor. 3. The control method of the electric excitation doubly salient motor excitation fault-tolerant power generation system according to claim 2, characterized in that, within one inductance cycle, the demagnetization power generation control method is specifically: When the electrical angle of the motor is from θ to 120°, the switching tube S1 is controlled to conduct, When the electrical angle of the motor is 120° to θ+120°, the switch tubes S1 and S4 are turned on, and the switch tube S1 is turned off when the electrical angle of the motor is equal to θ+120°; When the electrical angle of the motor is θ+120° to 240°, the control switch S4 is turned on, When the electrical angle of the motor is 240° to θ+240°, the switch tubes S4 and S5 are turned on, and when the electrical angle of the motor is equal to θ+240°, the switch tube S4 is turned off. When the electrical angle of the motor is θ+240° to 360°, the control switch S5 is turned on, When the electrical angle of the motor is 360° to θ+360°, the switching tubes S2 and S5 are controlled to be turned on, and when the electrical angle of the motor is equal to θ+360°, the switching tube S5 is turned off. 4. Electric excitation doubly salient motor excitation fault-tolerant power generation system, characterized in that the system includes excitation side power supply, load side energy storage capacitor, fault-tolerant power converter, electric excitation doubly salient motor, controller and position sensor wherein, the three-phase armature windings of the electrically excited doubly salient motor are star-connected, and the outgoing terminals of the A, B, and C phase windings are respectively connected to the fault-tolerant power converter; The terminal is responsible for providing the excitation current; the energy storage capacitor on the load side is connected in parallel with the load. 5. The electric excitation doubly salient pole motor excitation fault-tolerant fault-tolerant power generation system according to claim 4 is characterized in that, the fault-tolerant power converter is a three-phase full-bridge converter, which includes first and second IGBT switches The first bridge arm formed by connecting S1-S2, the second bridge arm formed by connecting the third and fourth IGBT switches S3-S4, and the third bridge arm formed by connecting the fifth and sixth IGBT switches S5-S6, so The DC side of the above-mentioned converter is connected to both ends of the load, and the outlet terminals of the A, B, and C phase windings of the electrically excited double salient pole motor are connected to the middle points of the first bridge arm, the second bridge arm, and the third bridge arm respectively. . 6. The electric excitation double salient pole motor excitation fault-tolerant power generation system according to claim 4, wherein the controller includes a voltage and current detection and conditioning circuit, a main control unit and an isolation drive circuit, the voltage, The current detection and conditioning circuit collects the excitation winding current, the three-phase winding current and the load side terminal voltage, the position sensor collects the rotor position signal, the main control unit processes the collected current, voltage and rotor position information, and through the isolation drive circuit for the three The switching tubes on the phase full bridge circuit provide drive signals.