CN101272125A - A Motor Drive System with Fault Tolerance - Google Patents

Abstract

A motor drive system with fault-tolerant function, including an inverter and a motor, the motor can be an asynchronous motor, a permanent magnet motor or a reluctance motor, the motor stator has multiple sets of windings, leading to 4 terminals U, V, W, O, the windings connected to any three terminals can form a rotating magnetic field in the air gap of the motor by passing current. The inverter is a three-phase full-bridge inverter, which leads to the DC neutral point N at the same time. The terminals A, B, and C of the three bridge arms of the inverter and the DC neutral point N are connected to the 4 terminals of the motor. U, V, W, O are connected. When a problem occurs in any phase of the motor drive system of the present invention, fault-tolerant control can be realized by simply changing the control algorithm, and the fault-tolerant operation state can be quickly entered without the participation of a hardware switch and without shutting down.

Description

A Motor Drive System with Fault Tolerance

technical field

The invention relates to a motor drive system with high reliability.

Background technique

Motor windings and power electronic converters are the weak links in drive systems that are prone to failure. Once one of them breaks down, the whole system will lose the ability to work normally, which will bring economic losses in general civilian occasions, but in important occasions such as aviation and military, it will cause catastrophic accidents, so it is of great significance to study fault tolerance of power generation systems . A common measure is to provide redundant motor windings or controllers. Such a system will be costly and bulky, and it is not suitable for occasions with high volume requirements. Aiming at common faults such as open circuit or short circuit of power switches, in the article "Research on Direct Torque Control of Fault-Tolerant Four-Switch Three-phase Converter Asynchronous Power Generation System" ("Chinese Journal of Electrical Engineering", Issue 18, 2005, Zhang Lanhong and Hu Yuwen), proposed A fault-tolerant method is proposed: the bridge arm where the faulty switch is located is disconnected, the six-switch three-phase converter is reconstructed into a four-switch three-phase converter, and then the system continues to run by adjusting the control strategy. The disadvantage of this scheme is that it can only provide redundancy for the power electronic converter, the motor winding is damaged, and the system cannot work; secondly, this scheme needs to judge which phase is faulty, so as to realize the fault-tolerant control of the faulty system through the switch. It is complex and increases the cost and volume of the system at the same time; due to the need to implement fault-tolerant control through switches, the real-time performance is poor, and the fault recovery time is long, so it is difficult to meet the needs of some occasions that require high real-time performance. How to improve the fault tolerance and reliability of the system without increasing the size and cost of the system has always been a difficult problem.

Contents of the invention

The purpose of the invention is to solve the problems of low fault tolerance capacity and complex fault tolerance scheme of the existing motor system. A new type of motor drive system is proposed. This drive system is composed of three-phase inverter, which has good fault tolerance, high reliability, low system cost, simple structure and small volume.

The driving system of the present invention includes an inverter and a motor.

Wherein the motor of the present invention can be a permanent magnet motor, or an asynchronous motor, or a reluctance motor. Different from the traditional three-phase motor, the motor stator of the present invention has multiple sets of windings, but only has 4 lead-out terminals. And if the windings connected to any three terminals are supplied with appropriate current, a rotating magnetic field can be formed in the air gap.

The inverter adopts a traditional three-phase full-bridge inverter, and at the same time leads to the DC neutral point, so that the inverter can lead to 4 terminals to connect with the above-mentioned motor. In this way, the system constitutes a motor drive system. When there is a problem with any one of the phases, fault-tolerant control can be realized through a simple control algorithm change, without the participation of hardware switches, and it can quickly enter the fault-tolerant operation state without shutting down.

The beneficial effects of the present invention are: this high-reliability drive system adopts simple three-phase bridge inverter hardware, and uses simple control algorithm changes without significantly increasing the system volume, weight and control difficulty. Effectively improve the reliability and safety of the drive system. The present invention can provide redundancy for any one phase of the motor with short recovery times from faults.

Description of drawings

Figure 1 is a schematic diagram of a traditional three-phase motor drive system;

Fig. 2 is a schematic diagram of one embodiment of the present invention;

Fig. 3 is a schematic diagram of the second embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 shows a traditional three-phase motor drive system. The three bridge arms of the inverter lead out three terminals A, B and C respectively, which are connected with the three leading terminals U, V and W of the three-phase motor, and the three-phase windings pass current to form a rotating magnetic field to drive the motor to work. When any one of the motor windings or any bridge arm of the inverter fails, the system stops working immediately.

Shown in Fig. 2 is one of specific embodiment of the present invention. In this system, the neutral point N of the DC power supply is directly drawn out, and together with the terminals A, B, and C of the three bridge arms, power is supplied to the motor. In this example, the stator of the motor adopts the method of four-phase winding star connection to form a four-phase motor, and the four-phase motor is connected to the terminals A, B, and C of the three bridge arms of the inverter and the neutral point N. According to Kirchhoff's theorem, the sum of the currents in the four-phase windings at any time is zero. During normal operation, by controlling the current in the OU, OV, and OW phase windings, the purpose of controlling the current of the OX phase winding is achieved, so that a rotating magnetic field is formed in the air gap of the motor to drive the motor to work. Assuming that the OU phase motor winding is faulty, by controlling the current in the OV and OW windings, the purpose of controlling the current of the OX winding is achieved, so that a rotating magnetic field is formed in the air gap of the motor to drive the motor to work normally. Also assuming that the A phase of the inverter is faulty, by controlling the current in the OV and OW windings, the purpose of controlling the current in the OX winding is achieved, so that a rotating magnetic field is formed in the air gap of the motor to drive the motor to work normally. Similarly, if any other phase fails, the system can work normally. Compared with the traditional three-phase system, the reliability has been greatly improved, and the system requires little modification.

Figure 3 shows another specific embodiment of the present invention. In this system, the DC bus support capacitor of the inverter uses two identical capacitors C1 and C2 in series, and the neutral point N is drawn from the series connection of the two capacitors C1 and C2, and the terminals A and B of the three bridge arms are connected in series. , C together supply power to the motor. The motor stator in this embodiment is connected by six sets of windings to form six edges of a tetrahedron, and four fixed points are used as lead-out terminals U, V, W, O to form a multi-phase motor, respectively connected to the three bridge arms of the inverter The leading ends A, B, C and the neutral point N are connected. According to Kirchhoff's theorem, the sum of the currents in the six sets of windings at any time is zero. During normal operation, by controlling the current in the OU, OV, and OW phase windings, the purpose of controlling the current of the UV, VW, and WU phase windings is achieved, so that a rotating magnetic field is formed in the air gap of the motor to drive the motor to work. Assuming that the OU phase motor winding is faulty, the motor becomes a motor composed of UV, VW, WU phase delta windings and OV, VW, WO phase delta windings. By controlling UV, VW, WU phase delta windings and OV, VW, WO The phase delta connects the current in the winding to form a rotating magnetic field in the air gap of the motor and drive the motor to work normally. Also assume that the A phase of the inverter is faulty, and the winding UW, UV, and UO phases cannot supply power. By controlling the current in the OV, VW, and WO phase delta-connected windings, a rotating magnetic field is formed in the air gap of the motor to drive the motor to work normally. Similarly, if any other phase fails, the system can work normally. Compared with the traditional three-phase system, the reliability has been greatly improved, and the system requires little modification.

The invention only makes simple changes to the system hardware, keeps the volume unchanged, and at the same time the cost is low, while the reliability is greatly improved, and has important practical value.

Claims (3)

1, a kind of motor driven systems with fault tolerance, it is characterized in that comprising an inverter and a motor, motor is asynchronous machine, magneto or reluctance motor, its stator has many cover windings, draw 4 terminal U, V, W, O, wherein any three windings that terminal connected pass to electric current and just can form rotating magnetic field in motor gas-gap; Inverter is a three-phase full-bridge inverter, draws DC point N simultaneously, the exit A of three brachium pontis of inverter, and B, C and DC point N, with 4 leading-out terminal U of motor, V, W, O links to each other.

2, the motor driven systems with fault tolerance according to claim 1 is characterized in that the method that adopts four phase winding stars to connect constitutes one four phase motor, 4 leading-out terminal U of four phase motors, V, W, the exit A of three brachium pontis of O and inverter, B, C and DC point N link to each other.

3, the motor driven systems with fault tolerance according to claim 1 is characterized in that motor adopts six cover windings to link to each other, and forms tetrahedral six ribs, and four fixed points are as leading-out terminal U, V, and W, O constitutes a polyphase machine; The dc bus of inverter supports electric capacity and adopts two identical capacitor C 1, the C2 series connection, and with two capacitor C 1, neutral point N is drawn in C2 series connection place; The leading-out terminal U of motor, V, W, O respectively with the exit A of three brachium pontis of inverter, B, C and neutral point N link to each other.

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