Course work on asynchronous motor calculation

Contents

Contents

SUMMARY

INTRODUCTION

1 DESIGN BASIS

2 MAGNETIC CIRCUIT OF ENGINE. DIMENSIONS, CONFIGURATION, MATERIAL

2.1 Main Dimensions

2.2 Stator Core

2.3 Rotor core

3 STATOR WINDING

3.1 Stator winding with trapezoidal semi-closed slots

4 SHORT-CIRCUITED ROTOR WINDING

4.1 Dimensions of oval closed slots

4.2 Dimensions of short-circuiting ring

5 MAGNETIC CIRCUIT CALCULATION

5.1 MDS for air clearance

5.2 MDS for teeth at trapezoidal semi-closed slots of stator

5.3 MDS for rotor teeth at oval closed rotor slots

5.4 MDS for stator back

5.5 MDS for rotor back

5.6 Magnetic Circuit Parameters

6 ACTIVE AND INDUCTIVE RESISTANCE OF WINDINGS

6.1 Stator winding resistance

6.2 Resistance of short-circuited rotor winding with oval semi-closed slots

6.3 Resistance of windings of converted motor replacement circuit

7 IDLING MODE AND NOMINAL

7.1 Idle mode

7.2 Calculation of nominal operation mode parameters

8 PIE CHART AND PERFORMANCE

8.1 Pie Chart

8.2 Performance

9 MAXIMUM TORQUE

10 START-UP CURRENT AND START-UP TORQUE

10.1 Active and inductive resistances corresponding to start-up mode

10.2 Start-up current and torque

11 THERMAL AND VENTILATION CALCULATIONS

11.1 Thermal calculation

11.1.1 Stator winding

11.2 Engine ventilation calculation with degree of protection IP44 and cooling method IC

12 ENGINE WEIGHT AND DYNAMIC MOMENT OF INERTIA

12 MECHANICAL SHAFT CALCULATION

12.1 Calculation of shaft for stiffness

12.2 Determination of critical speed

12.3 Shaft Strength Calculation

LIST OF LITERATURE

Summary

Asynchronous motor was calculated.

Electromagnetic calculation of the motor is performed. Dimensions, configuration, materials of magnetic system of asynchronous motor are determined. Types of stator and rotor windings, insulation, winding wires are defined. Motor magnetic circuit is calculated, active and inductive resistances of stator and rotor windings are determined. Engine operation at idling, nominal mode, and during start-up is calculated. The pie chart and performance characteristics of the designed engine are built. Thermal and ventilation calculations of the engine were made. Mass of designed engine and its components and dynamic moment of rotor inertia are determined. Mechanical calculation of the designed engine shaft was performed.

The design of the machine was developed and drawings were made: assembly drawing of the designed engine, assembly drawing of the rotor on the shaft, drawing of the rotor sheet, drawing of the shaft.

Introduction

State and prospects of asynchronous motors development

(Authors: Lazarevsky N.A., Martynov S.A. - Central Research Institute of SETs)

ELECTRONIC ELECTRICAL JOURNAL "I am an electrician!" Issue No. 8 November-December 2007

The simplicity of design, reliability, high efficiency of asynchronous motors (BP) with a power of 0.025 to 350 kW explain the widespread use in electric drives. It is known, in particular, that drives using BP consume about 60% of the world's electricity production.

In the early 1990s, with the collapse of the USSR, the acquisition of asynchronous motors became a problem for the Russian consumer. In the Russian Federation, there was no production of BP with heights of the axis of rotation 63, 71, 80, 90, 200, 225, 250 mm. Electric motors of such dimensions were produced only by the factories of the Ukrelektromash and Yuzhelektromash production associations (Ukraine), the Electric Motor plant (Belarus), Armelektrozavod and Yerevan ETZ (Armenia), Azerelektromash (Azerbaijan). In general, about 80% capacities for the production of electric motors of the single 4AM and AIR series were located already outside our country.

Taking into account the current situation, specialists of OJSC NIPTIEM, the leading Russian institute working in the field of electrical engineering, developed a new general industrial series AD5A at the height of the axis of rotation from 71 to 355 mm (this row combined fourteen dimensions).

The development was based on the ideas of increasing efficiency and resource, reducing noise levels and operating temperature, improving the starting and weight and size characteristics of electric motors. According to the technical assignment of FSUE TsNII SET, on the basis of this series, a working design of AD was developed that meets the requirements of the Russian Maritime Register of Shipping (PC), at the height of the axis of rotation from 63 to 250 mm with the number of pairs of poles 2p = 2, 4, 6. Two dimensions from this series (5A80 and 5A100) have been tested (MVI) and are now supplied by the Vladimir Electric Machine Building Plant (VEMZ). Their purpose is to complete drives; they can be exploited on ships and in fishermen.

One of the tasks of the near future is to produce prototypes of the remaining dimensions of the series, conduct MVI and issue technical specifications (TS) for ship electric motors that meet the requirements of PC. In parallel with the development of the 5A series, NIPTIEM specialists were engaged in improving the built-in temperature protection of engines. Built-in thermal devices have been developed

protection unit, actuating unit of which is located directly on BP housing. A version with remote control was developed.

At each stage of development, their approaches to choosing optimal design solutions were implemented. Both the latest developments in the field of electrical technology and the unfavourable features of the current economic state of the country were taken into account. For example, if earlier, in a planned economy, the cost of labor, material and energy resources often did not correspond to their consumer properties, then in a market economy the situation has become different. By April 1999, the cost of 1 ton of copper winding wires increased from 1.5 to 75.0 thousand rubles - ninety times. The cost of 1 ton of electrical steel increased from 380 rubles to 5.7 thousand rubles - fifteen times, 1 kWh of electricity rose from 1.36 to 41 kopecks - thirty times.

The relatively low cost of winding copper, characteristic of previous years, made it possible to make the BP of all previously developed series "copper" - with a relatively low magnetic induction in the air gap (0.65.. .0.75 Tl) and a relatively large air gap. It is believed that at present, taking into account the action of known economic factors, BP, the so-called "steel" machines, should be optimal.

Based on these circumstances, the production of asynchronous motors of the new RA series was mastered at the Yaroslavl Electric Machine Building Plant (OJSC ELDIN). During its development, the following guidelines were chosen: obtaining high energy indicators while reducing the mass of the engine and achieving its greater compactness; increase of starting moments at decrease of starting current multiplicity; improving vibration acoustic characteristics of engines by reducing magnetic, mechanical and ventilation noise; simplicity and safety of maintenance of such engines; increasing the competitiveness of new BP.

RA series asynchronous motors meet the requirements of international standards. They were successfully exhibited at international exhibitions in Hanover (1995-1999). They are supplied to industrialized countries: to Germany, Italy, France, etc. In the nearest plans - testing them for compliance with PC requirements, expanding the scope of their application (on sea and river vessels).

The BP values ​ ​ of the classical design have so far been brought to levels that practically ensure the achievement of limit values ​ ​ of electromagnetic loads with an acceptable consumption of active materials. Further development of BP is carried out along the path of structural splicing of electric drives with technical objects in which they are installed. There are also specific requirements for BP.

So, at present, a traction electric drive based on a BP with a short-circuited rotor, used in ground electrified transport (tram, trolleybus), in the metro, electric trains, has received development.

Frequency converters (IF) with DC link are used to control traction electric drive, output signals of which are generated on the basis of PWM. A series of rectangular pulses of constant amplitude but varying duration is formed at the output of the converter. The useful component has the form of a sinusoid of a given frequency and amplitude.

Currently, as a rule, bipolar insulated gate transistors (IGBT) with a pulse front duration in the range of 0.11.0 μs are used as a key element. As a result, rectangular pulses with a high peak value are supplied to the BP winding, resulting in significant overvoltage in the windings. The magnitude of the overvoltage amplitude increases as the carrier frequency of the PWM increases (in order to improve energy parameters and approach the useful component of the IF output voltage to the sinusoid.)

Such overvoltage provokes rapid aging of insulation, which ultimately leads to a decrease in reliability and service life of BP [3]. Obviously, both when issuing the technical assignment and when developing the BP, it is necessary to take into account the requirements for increasing the insulation strength .

An important specific requirement applied to traction electric drive is the requirement to ensure the operation of AP without overheating in the frequency range up to 150 Hz. As a rule, acceleration of AP in the traction electric drive of transport is carried out by changing the frequency in the range of 050 Hz, reaching a speed of up to 70 km/h - in the range of 50150 Hz. When designing specialized BP for a traction electric drive, it is necessary to provide for an expansion of the operating frequency range to 150 Hz.

Conclusion

1. Domestic industry has developed, and currently mass-delivered BP series 5A and RA in the general industrial version.

2. In order to determine whether the 5A and RA series BP can operate on vessels and fish farms, it is necessary to carry out tests for their compliance with PC requirements.

3. When issuing technical tasks, as well as when designing specialized BP intended for use in a traction electric drive, it is necessary to provide for the following: increasing their functional capabilities by expanding the operating frequency range to 150 Hz; high requirements for insulation strength (taking into account possible overvoltages, which sometimes reach values ​ ​ more than one and a half times the amplitude of the initial effect on individual sections of the BP winding operating from IF under frequency control from PWM).