CN206323316U - A kind of synchronous electric motor rotor field circuit with fault-tolerant operation - Google Patents

Abstract

The utility model patent discloses a synchronous motor rotor excitation circuit with fault-tolerant operation. The circuit can realize: when some components of the excitation circuit of the electric excitation synchronous motor fail, the faulty bridge arm is cut off and the non-faulty bridge arm is used to maintain normal operation. The rotor excitation circuit includes two bridge arms, each bridge arm has a switch that can cut off the bridge arm, and the output terminals of the bridge arms are connected to the negative pole of the DC bus through a switch. When it is detected that there is a faulty device in the rotor excitation circuit, the switch of the bridge arm where the faulty device is located is turned off, so that the faulty bridge arm is cut off, and at the same time, the switch connecting the output end of the faulty bridge arm to the negative pole of the DC bus is closed. By adjusting the duty cycle of the trigger pulse of the IGBT of the non-faulty bridge arm, normal excitation can be realized by using the non-faulty bridge arm.

Description

A Synchronous Motor Rotor Exciting Circuit with Fault Tolerant Operation

technical field

The utility model patent relates to an excitation circuit of an electric excitation synchronous motor, which can maintain the normal operation of the motor when some components of the excitation circuit of the electric excitation synchronous motor fail.

Background technique

Synchronous motors are widely used in the field of AC transmission. According to the different excitation methods of synchronous motor rotors, they can be divided into two types: electric excitation synchronous motors and permanent magnet synchronous motors. Among them, the DC excitation magnetic field of the rotor of the electrically excited synchronous motor is provided by an external power supply, and the excitation current is adjustable. The electric excitation synchronous motor has the characteristics of adjustable power factor and high working efficiency of the motor. In large-capacity and high-performance electric drive occasions, electric excitation synchronous motors are more widely used.

In actual operation, due to the failure of the power electronic devices in the excitation circuit, the electric excitation synchronous motor will not work normally. When the electric excitation synchronous motor loses its excitation, it will cause the motor to lose its step and fail to run normally, and in severe cases, it will also endanger the motor body. The failure of the motor will also cause risks to the personal safety of the operator, so it is necessary to design an excitation circuit with a fault-tolerant operation function. Most of the existing excitation circuits are DC chopper circuits, but the fault tolerance method is not considered in the circuit. When a fault occurs, it can only be shut down for processing, so the reliability is low.

Utility model content

Aiming at the excitation circuit of electric excitation synchronous motor without fault tolerance, the utility model designs an electric excitation synchronous utility model motor rotor excitation circuit with fault-tolerant operation. The excitation circuit proposed by the utility model is mainly aimed at providing excitation to the rotor of an electrically excited synchronous motor and maintaining the normal operation of the motor when part of the fully controlled power electronic device (IGBT) in the excitation circuit is damaged.

The technical scheme adopted by the utility model is: after detecting that some components of the excitation circuit are faulty, the faulty bridge arm can be cut off, and the non-faulty bridge arm can be used to maintain the fault-tolerant operation of the rotor excitation circuit. As shown in Figure 1, the rotor excitation circuit includes a first bridge arm and a second bridge arm. In the first bridge arm, the first fully-controlled power electronic device V ₁ is connected in antiparallel with the first power diode D ₁ , and the second fully-controlled power electronic device V ₂ is connected with the second power diode D ₂ anti-parallel connection, the IGBTs of these two groups of anti-parallel diodes are connected in series with the first switch S _1a , the middle of the IGBTs of the two groups of anti-parallel diodes leads to the output end of the bridge arm, and the output end of the bridge arm passes through the second switch S _1b Connect to the negative pole of the DC bus. In the second bridge arm, the third fully-controlled power electronic device V ₃ is connected in antiparallel with the third power diode D ₃ , and the fourth fully-controlled power electronic device V ₄ is antiparallel to the fourth power diode D ₄ The IGBTs of the two groups of anti-parallel diodes are connected in series with the third switch S _2a , the middle of the _IGBTs of the two groups of anti-parallel diodes leads to the output end of the bridge arm, and the output end of the bridge arm is connected to the Negative pole of the DC bus. The output ends of the first bridge arm and the second bridge arm are connected to both ends of the excitation winding.

The utility model effect:

In the faulty running state, the faulty bridge arm can be cut off, and the non-faulty bridge arm can be used to maintain operation. The utility model has a simple structure and is easy to realize. When a power electronic device in the excitation circuit of an electric excitation synchronous motor fails, it can remove the fault and make the motor run normally.

Description of drawings

Fig. 1 is the electrical excitation synchronous motor system diagram of the rotor excitation circuit with fault-tolerant operation function of the utility model;

Figure 2a is a circuit switch state diagram when the excitation circuit is in normal operation;

Figure 2b is an equivalent circuit diagram of the excitation circuit in normal operation;

Figure 3a is a switch state diagram after the second bridge arm of the excitation circuit is faulty and the faulty bridge arm is removed;

Fig. 3b is an equivalent circuit diagram after the second bridge arm of the excitation circuit is faulty and the faulty bridge arm is cut off.

detailed description

The specific implementation method of the present utility model will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a system diagram of an electric excitation synchronous motor with a fault-tolerant operation rotor excitation circuit designed by the utility model. The rotor excitation circuit designed by the utility model consists of 4 full control devices IGBT (V ₁ , V ₂ , V ₃ , V ₄ ), 4 anti-parallel diodes (D ₁ , D ₂ , D ₃ , D ₄ ), 4 switch (S _1a , S _1b , S _2a , S _2b ). in:

The DC bus voltage of the rotor excitation circuit with fault-tolerant operation of the utility model is provided by a DC voltage source E, and the excitation circuit is composed of two bridge arms. In the first bridge arm, the first fully-controlled power electronic device V ₁ is connected in antiparallel with the first power diode D ₁ , and the second fully-controlled power electronic device V ₂ is connected in reverse with the second power diode D ₂ The IGBTs of these two groups of anti-parallel diodes are connected in series with the first switch S _1a , the middle of the IGBTs of the two groups of anti-parallel diodes leads to the output terminal A of the bridge arm, and the output terminal A of the bridge arm is connected through the second switch S _1b to the negative pole of the DC bus. In the second bridge arm, the third fully-controlled power electronic device V ₃ is connected in antiparallel with the third power diode D ₃ , and the fourth fully-controlled power electronic device V ₄ is antiparallel to the fourth power diode D ₄ The IGBTs of these two groups of anti-parallel diodes are connected in series with the third switch S _2a , and the middle of the IGBTs of the two groups of anti-parallel diodes leads to the output terminal B of the bridge arm, and the output terminal B of the bridge arm is connected through the fourth switch S _2b to the negative pole of the DC bus. The rotor of an electric excitation synchronous motor can be equivalently simplified as a resistive load with a resistance value of _Rf and an inductance value of _Lf . The output ports A and B of the two bridge arms of the utility model are loaded to the resistive load of the electric excitation synchronous motor rotor ends.

When the excitation circuit is in normal operation, the switches S _1a and S _2a are closed, and the switches S _1b and S _2b are opened. Figure 2a shows the switching state of the circuit under normal operation. Figure 2b is the equivalent circuit during normal operation. During normal operation, the switching states of V1 and _{V4 of} the full _- control device are the same, the switching states of V2 and _V3 are the same, and the switching states of the switching tubes of the same bridge arm are complementary, that is, when V1 is turned _on , the switching state _of V2 The state is off state, the state of V2 is _on state when V1 is off _; the state of _V4 is off state when _V3 is on, and the state of _V4 is on state when _V3 is off. According to the value of the target output voltage and the DC bus voltage, the duty cycle of each switching tube can be obtained.

When a switching device in the excitation circuit fails, here we take the failure of the full control device V ₃ as an example for illustration. Figure 3a shows that after V ₃ fails, the bridge arm where V ₃ is located is cut off to maintain operation with a single bridge arm. Figure 3b is the equivalent circuit under fault-tolerant operation. When V ₃ fails, the switches S _1a and S _2b of the non-faulty bridge arm maintain the state of normal operation, the switch S _2a in the faulty bridge arm where V ₃ is located is switched to an open state, and the switch S _2b is switched to a closed state , so the faulty bridge arm is cut off and the output terminal of the faulty bridge arm is connected to the negative pole of the DC bus voltage. It can be seen from the equivalent circuit shown in Figure 3b that the excitation circuit still constitutes a DC chopper circuit. After the bridge arm is cut off, the switching states of the fully controlled devices V ₁ and V ₂ still need to meet the complementary conditions. According to the ratio of the target output voltage to the DC bus voltage, the corresponding duty cycle of each switch tube of the normal working bridge arm can be obtained.

The summary can be summarized as follows: (1) In the normal and fault-free operation state, the switch S _1a is closed, S _1b is open, S _2a is closed, and S _2b is open; (2) When V ₁ or V ₂ in the first bridge arm occurs When a fault occurs, the switch S _1a is open, S _1b is closed, S _2a is closed, and S _2b is open; (3) When V ₃ or V ₄ in the second bridge arm fails, the switch S _1a is closed, S _1b is closed Open, S _2a is open, S _2b is closed. Then change the duty cycle of the corresponding full control devices V ₁ , V ₂ or V ₃ , V ₄ to realize the normal excitation function. (4) After a fault occurs, the excitation device of the full-bridge structure becomes a half-bridge structure. Although the excitation device of the half-bridge structure cannot realize bidirectional excitation, it can realize positive and negative rotation by changing the rotation direction of the space vector in the motor control unit. Therefore, after a switch tube of the excitation circuit fails, the electric excitation synchronous motor can still realize the function before the failure.

Claims (2)

1. A synchronous motor rotor excitation circuit with fault-tolerant operation, characterized in that: the rotor excitation circuit includes a first bridge arm and a second bridge arm; in the first bridge arm, the first full control The IGBT of the type power electronic device is connected in antiparallel with the first power diode, and the second fully controlled power electronic device IGBT is connected in antiparallel with the second power diode. The middle of the IGBT of the anti-parallel diode leads to the output end of the bridge arm, and the output end of the bridge arm is connected to the negative pole of the DC bus through the second switch; in the second bridge arm, the third fully-controlled power electronic device IGBT and the third The first power diode is connected in reverse parallel, and the fourth fully controlled power electronic device IGBT is connected in reverse parallel with the fourth power diode. The output end of the bridge arm is led out in the middle, and the output end of the bridge arm is connected to the negative pole of the DC bus through the fourth switch, and the output ends of the first bridge arm and the second bridge arm supply power to the rotor of the electrically excited synchronous motor. 2. A synchronous motor rotor excitation circuit with fault-tolerant operation according to claim 1, characterized in that, under normal operating conditions, the first switch is closed, the second switch is open, and the third switch is closed , the fourth switch is open; in the faulty operating state, when the faulty device appears in the first bridge arm, the first switch is open, the second switch is closed, the third switch is closed, and the fourth switch is open; When the faulty device appears in the second bridge arm, the first switch is closed, the second switch is open and closed, the third switch is open, and the fourth switch is closed; when a switch tube fails, the circuit can Cut off the bridge arm where the faulty switch tube is located, adjust the trigger pulse duty cycle of the IGBT of the non-faulty bridge arm, and use the non-faulty bridge arm to realize excitation.