A starting method of ship electric propulsion permanent

magnet synchronous motor

Qingshan Ji, Guoping Liu

Electromechanical College of Zhejiang Ocean University, zhoushan 316000, China

Zhejiang ship Advanced Manufacturing Technology R amp; D Center, zhoushan 316000, China

Abstract

The propulsion system consisted of the AC - AC Converter and permanent magnet synchronous motor used more often in the current ship electric propulsion. The firstly solving problem is the PMSM starting. In this paper, based on briefly describing the ship electric propulsion system, analyzed the characteristics of the PMSM starting, the system used open-loop frequency starting mode. The analysis shows that the way in ship propulsion PMSM starting running condition, is simple, reliable, good starting performance. The starting mode can also be used as the starting method of a large PMSM for other purposes.

copy; 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license

Selection and/or peer-review under responsibilityof [CEIS2011]

Keywords: ship electric propulsion; PMSM, starting; frequency;open-loop

1.Introduction

The ship Electric propulsion is a propulsion way that propulsion motor directly drives the propellers.The propulsion device generally is consisted of propellers, motors, generators, prime mover and the control conditioning and other components. Electric propulsion has low noise, good mobility, flexibility shipping space and other advantages.

Using electric propulsion can avoid the prime movers wide range speed regulation, and improve its efficiency. But, on the other hand, in the machine - electric - machine conversion process, it also increases energy consumption [1]. Therefore, the propulsion motors must have high efficiency, and can meet the ship promoting conditions. With the development of the power electronics technology and magnetic materials, in the ship electric propulsion system, the permanent magnet synchronous motor was usually used. Compared with the conventional motor, it has high power density, high torque density, high efficiency, high power factor and so on. The propulsion system consisted by the permanent magnet synchronous motor, is low noise, high efficiency, maintenance and performance better.

Because the ship propulsion is large power and low speed, currently CYCLO propulsion systems is most widely used[2]. The system is consists of AC- AC converter AC synchronous motor. According to the control requirements, the converter selects the different Phase intervals of AC power, and provides alternating current to the synchronous motor. Its upperlimit of the speed regulation is generally not more than 40% of the base frequency.

The first condition of PMSM running is starting. According to the principle of synchronous motor shows that: only in the synchronous condition, the average electromagnetic torque can consist. The starting process is that the motorrsquo;s rotor speed increases from zero. It is non-synchronous operation state. The average electromagnetic torque is zero, which can not make the rotor accelerating. So the synchronous motor is not self-starting. On literature [3], a variety of medium and large synchronous motor starting modes have been conducted recapitulative discussion. For large synchronous motor, the modern inverter technology is used in the static frequency converter starting. Either efficiency or control performance are relatively good. In this paper, based on the actual working conditions of the large ship propulsion, the open loop variable frequency start method was used.

2.the Theoretical Analysis of PMSM Starting Characteristics

When the Electrically excited synchronous motor started asynchronously, in order to successfully start and ensure safety, the field-winding must string the current limiting resistor closed. When it will reach synchronized, and then excitation is begun. However, in the permanent magnet synchronous motor, the excitation can not be adjusted.No matter what running condition of the motor, a certain excitation is always provided. Therefore, during the permanent magnet synchronous motorrsquo;s starting process, its physical phenomena is much more complex than the asynchronous motor or electrically excited synchronous motor.

In the PMSM starting process, when the stator winding is applied the three phase AC current at frequency f1. This current establish the air-gap magnetic field that it rotates at the synchronize speed n1. In the rotor conductors, the air-gap magnetic field induces AC current at frequency f2= sf1. The AC current produces asynchronous electromagnetic torque, which it is same with the general asynchronous motor. It is known as asynchronous torque.

The permanent magnet magnetic field and the rotating magnetic field produced by stator current is asynchronous operation. Having relative motion between the two can not form synchronized torque. However, considering the superposition principle,the permanent magnetic field and the rotor windings can form a synchronous generator.In the Stator winding, besides the current of fundamental frequency f1,the induced current that its frequency is (1-s) f1appears.The stator rotating magnetic field and permanent magnet field created by the current can form generator brake torque.The curve 2 is shown in figure 1. Because the reactance of quadrature axis and direct axis is not equal, the induced current that its frequency is (1-2s) f1appears.The stator rotating magnetic field and permanent magnet field created by the current can generate Reluctance torque. The curve 3 is shown in figure 1. After the above-mentioned three kinds of torque were synthesized, the total starting torque of PMSM can be obtained. The curve 4 is shown in figure 1.

Fig.1. Starting characteristics

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A starting method of ship electric propulsion permanent

magnet synchronous motor

Qingshan Ji, Guoping Liu

Electromechanical College of Zhejiang Ocean University, zhoushan 316000, China

Zhejiang ship Advanced Manufacturing Technology R amp; D Center, zhoushan 316000, China

Abstract

The propulsion system consisted of the AC - AC Converter and permanent magnet synchronous motor used more often in the current ship electric propulsion. The firstly solving problem is the PMSM starting. In this paper, based on briefly describing the ship electric propulsion system, analyzed the characteristics of the PMSM starting, the system used open-loop frequency starting mode. The analysis shows that the way in ship propulsion PMSM starting running condition, is simple, reliable, good starting performance. The starting mode can also be used as the starting method of a large PMSM for other purposes.

copy; 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license

Selection and/or peer-review under responsibilityof [CEIS2011]

Keywords: ship electric propulsion; PMSM, starting; frequency;open-loop

船舶电力推进永磁同步电动机

的一种启动方法

季青山，刘国平

中国浙江海洋大学机电学院，舟山 316000，

中国浙江省船舶先进制造技术研发中心、舟山 316000

摘要

由交流-交流变换器和永磁同步电动机组成的推进系统更常用于当前的船舶电力推进。首先要解决是永磁同步电动机起动的问题。本文在简要描述船舶电力推进系统的基础上，分析了永磁同步电动机起动特点及系统使用的开环频率起动方式。分析表明，这种船舶推进永磁同步电动机的起动方式简单、 可靠、 有良好的起动性能。这种起动方式也可以用作大型永磁同步电机的起动方法而用于其他目的。

copy; 2011年发布由爱思唯尔有限公司开放存取下 CC BY-数控-ND 许可证

选择和/或同行审查责任下[CEIS2011]

关键词 ︰ 船舶电力推进系统 ；永磁同步电动机，起动；频率；开环

1.Introduction

The ship Electric propulsion is a propulsion way that propulsion motor directly drives the propellers.The propulsion device generally is consisted of propellers, motors, generators, prime mover and the control conditioning and other components. Electric propulsion has low noise, good mobility, flexibility shipping space and other advantages.

Using electric propulsion can avoid the prime movers wide range speed regulation, and improve its efficiency. But, on the other hand, in the machine - electric - machine conversion process, it also increases energy consumption [1]. Therefore, the propulsion motors must have high efficiency, and can meet the ship promoting conditions. With the development of the power electronics technology and magnetic materials, in the ship electric propulsion system, the permanent magnet synchronous motor was usually used. Compared with the conventional motor, it has high power density, high torque density, high efficiency, high power factor and so on. The propulsion system consisted by the permanent magnet synchronous motor, is low noise, high efficiency, maintenance and performance better.

Because the ship propulsion is large power and low speed, currently CYCLO propulsion systems is most widely used[2]. The system is consists of AC- AC converter AC synchronous motor. According to the control requirements, the converter selects the different Phase intervals of AC power, and provides alternating current to the synchronous motor. Its upperlimit of the speed regulation is generally not more than 40% of the base frequency.

The first condition of PMSM running is starting. According to the principle of synchronous motor shows that: only in the synchronous condition, the average electromagnetic torque can consist. The starting process is that the motorrsquo;s rotor speed increases from zero. It is non-synchronous operation state. The average electromagnetic torque is zero, which can not make the rotor accelerating. So the synchronous motor is not self-starting. On literature [3], a variety of medium and large synchronous motor starting modes have been conducted recapitulative discussion. For large synchronous motor, the modern inverter technology is used in the static frequency converter starting. Either efficiency or control performance are relatively good. In this paper, based on the actual working conditions of the large ship propulsion, the open loop variable frequency start method was used.

1.介绍

船舶电力推进是推进电机直接驱动螺旋桨的推进方式。推进装置一般是由螺旋桨、 电动机、 发电机、 原动机和控制设备及其他组件组成的。电力推进具有低噪音、良好的机动性、灵活的装载空间等特点。

使用电力推进可以避免原动机速度调节范围宽，并提高其效率。但是，另一方面，在机-电-机转换过程中，它也增加了能源消耗 [1]。因此，推进电机必须效率高，能满足船舶推进条件。随着电力电子技术和磁性材料的发展，在船舶电力推进系统中，通常使用永磁同步电动机。它与传统电机相比，具有高功率密度、 高转矩密度、 高效率、 高功率因数等优点。推进系统由永磁同步电机组成，噪音低、 效率高、 维护性能更好。

因为船舶推进功率大和转速低，所以目前交-交变频推进系统是使用最广泛的 [2]。该系统是由交-交变频器 交流同步电机组成的。根据控制要求，转换器选择不同的相位时间间隔的交流电源，并给同步电动机提供交变电流。速度调节其上限是一般不超过 40%的基频。

永磁同步电动机运行的首要条件是启动。根据同步电动机的原理表明：只有在同步的条件下，平均电磁转矩才能形成。启动过程是电机转子速度从零开始增加。它是非同步运行状态。平均的电磁转矩为零，不能使转子加速。所以同步电动机不会自启动。在文献 [3]，各种中型和大型同步电动机起动方式已经进行概括性的讨论。对于大型同步电动机，现代逆变器技术用于静态变频器，效率或控制性能均较好。本文基于实际工作条件的大型船用推进器，使用开环变频启动方法。

2.the Theoretical Analysis of PMSM Starting Characteristics

When the Electrically excited synchronous motor started asynchronously, in order to successfully start and ensure safety, the field-winding must string the current limiting resistor closed. When it will reach synchronized, and then excitation is begun. However, in the permanent magnet synchronous motor, the excitation can not be adjusted.No matter what running condition of the motor, a certain excitation is always provided. Therefore, during the permanent magnet synchronous motorrsquo;s starting process, its physical phenomena is much more complex than the asynchronous motor or electrically excited synchronous motor.

In the PMSM starting process, when the stator winding is applied the three phase AC current at frequency f1. This current establish the air-gap magnetic field that it rotates at the synchronize speed n1. In the rotor conductors, the air-gap magnetic field induces AC current at frequency f2= sf1. The AC current produces asynchronous electromagnetic torque, which i

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