Designing manufacturing and controlling brushless dc motor for circulation systems which has low power

In the recent years energy efficiency topic has gained importance both in European Union and Turkey. This trend led home appliances and industrial product producers to various research, design and development activities in this field. Energy efficient products are supported by the goverments and by legal obligations consumers are being canalized to those energy efficient products. Thanks to this, the companies that tries to establish a market presence should develop their products and improve their technology in terms of energy efficiency. Energy efficiency index, which has been accepted by European Union and Turkey, was studied detailly on circulation systems. Four operation levels of a pump which has different head and flowth are determined in order to calculate energy efficiency index on circulation pumps. The calculation of referance power for the four levels of a pump is explained in the standards. In the mean time, legal obligations are given and new legal obligation which will be announced for upcoming years is explained. In this study,the importance of energy efficiency index was examined, literature search was done about pumps which are a part of those circulation systems and detialed information was given, the meanings of head and flow in circulation systems was explained and a combined drive system design for a circulation pump driven by a burshless DC motor is performed. Literature review also done for electrical motors in detail and brushless DC type electrical motor was decided to be designed in order to make the circulation system more efficient. The structure, operartional principles and control strategies of the BLDC electrical motors were examined detailly. The advantages and disadvantages of BLDC type electrical motors was given in comparative results. At the same time, the pump was analyzed by a computer software and calculated performance rates were given for different rpm values. Energy Efficiency Curve is obtained by combining the mechanical numerical simulation results and a BLDC motor was designed according to the pump characteristics which was analysed by a obtained calculation results. The pump was analysed with CFD software to construct the whole circulation system, then the parameters like pump efficiency, head, flow etc. was determined for different angular velocities. These parameters refer to the maximum head and maximum flow of the pump. After deciding the maximum head and flow, the needed points were obtained for EEI calculation. Therefore, the most efficienct points of pump was derived. Energy efficiency index calculation for circulation systems which is accepted by standards in European Union and Turkey was evaluated and efficiency index according to existing system was calculated. This calculation was also done for the designed system and difference between the two was emphasized. Brushless DC motor design was performed by using a highly reliable design software. The software was supplied from the distributor company. Motor design software was used to design the targetted motor in accordance with the desired moment and rpm values. Special drives for brushless DC motors were checked and sensorless drive was selected since the system is to be operated as wet-rotor and sensors can cause problems during wet applications. Selected drive parameters, magnetical properties of the materials were also recorded as inputs for the complete design. Raw material is selected according to threshold limits of the motor and availability in the market. Also different available materials were analyzed and final design is obtained in comparison. At the beginning of the BLDC design, attention was paid to pump's CFD analysis and decided operation points regarding to EEI calculation. Later on, required shaft power, rpm and torque was used for the new designed BLDC motor. Different parameters were studied and difference was applied on the software to rapidly analyze performance influence. Finite element analysisis completed in the software in order to foresee the highly importance properties like flux density, cogging torque, etc. The design is improved according to the calculations. Three designs were performed with different slot and pole numbers and were compared to obtain the most convenient design. After comparison, the design having 12 slots and 4 poles was chosen depending on its low cogging torque value and high efficiency. After optimisation, the design is produced by a domestic company with the obtained BLDC motor parameters. Depending on the feedback of the company, several design parameteres like outer diameter of the stator was changed in order to match with the production limits of the company to reduce production time and cost of the motor. Renewed BLDC motor was produced with an decreased slot diameter and cogging torque, an increased lamination stack. Designed brushless DC motor was produced by using modern production techniques. A high speed laser cutting machine which is mainly available in motor prototyping companies is used to cut the high magnetic permeability steel in order to reduce the unwanted effects of heat on steel while cutting. Magnets were made of rare earth elements was dimensioned and magnetized abroad and was sent to the producer company. Magnets were sticked on the rotor by applying a special glue. Stator and rotor stacks were produced by laser welding. Different types of BLDC drivers was analyzed to control the designed motor. Using Hall-effect sensors is difficult to use on BLDC motors, since circulation pump motors have a wet rotor structure that means the rotor of electrical motor operates in the water completely causing problems in insulation. Since applying Hall-effect sensors is too difficult and too expensive, sensorless control was chosen to be the most convenient method for driving electrical motors in the circulation system. In this study, a sensorless driver was chosen and supplied from the driver company. Finally, the system designed for the pump parameters was analyzed with CFD software , required driver and the motor was designed in SPEED software. All the parameters of driver, pump and motor were influenced the whole system design. In order to see the benefits of the usage of a BLDC motor, EEI value was re-calculated for a needed induction motor and newly designed BLDC motor. It was seen that newly designed system has a highly greater EEI in comparison with that of an induction motor. After producing the prototype motor, practical tests were performed in production facilities and ITU Electrical Machinery Laboratory to verify the results. Differences between the actual performance and software outputs for cogging torque and back-emf values was measured. It is realized that the actual cogging torque is greater than the calculated one. Back-emf values for the phase windings are seemed to be as expected. The test bench was constructed in ITU Electrical Machinery Laboratory. For this construction the BLDC motor was coupled with a Eddy current brake as a load and connected with the driver. The rectifier over a variable transformer generated DC supply. Driver circuit is connected to the DC supply and a computer. The motor parameters were set on the driver software and stored into the driver. Motor is operated at no load without a problem. This project is supported by ITU Scientific Research Projects department. With this project both in European Uniun and Turkey circulation system ensure that compliance with legal requirements of EEI. A high efficient circulation system driven by permanent magnet electrical motor was designed. Outputs of the computitional fluid dynamics analysis of a chosen pump was used to design a BLDC motor. After designing the BLDC motor, prototype was produced and tested. A new circulation system having a great contribution in efficiency for Turkey is designed.