A quantitative comparison between BLDC, PMSM, brushed DC and stepping motor technologies

Brushless DC machines (BLDC), Permanent Magnet Synchronous Machines (PMSM), Stepping Motors and Brushed DC machines (BDC) usage is ubiquitous in the power range below 1,5kW. There is a lot of common knowledge on these technologies. Stepping Motors are ideally suited for open loop positioning, BLDC machines are the most obvious candidate for high-speed applications, etc. However, literature lacks comprehensive research comparing these machines over a large range of applications. In this paper, more than 100 motors are considered. Their characteristics are compared and presented in a comprehensive way. These results support the common knowledge concerning the field of application of each technology and new insights follow from this quantitative comparison

Design of dual-magnet memory machines

The memory machine, which adopts the aluminum-nickel-cobalt (AlNiCo) as the permanent magnet (PM) material, has attracted a wide attention. In this paper, by incorporating two kinds of PM materials including the neodymium-iron-boron (NdFeB) and the AlNiCo, the dual-magnet memory machine is proposed, which has more distinguished merits than its single-magnet counterpart. Due to the high coercivity of the NdFeB, the overall power density is augmented notably. Also, the risk of accidental demagnetization is significantly reduced. Most importantly, the design on how to combine these two kinds of PMs is discussed in detail, with emphasis on their shape, thickness and relative position. Both simulation and experimentation are given to illustrate the validity of the proposed design. © 2011 IEEE.published_or_final_versionThe 2011 International Conference on Electrical Machines and Systems (ICEMS 2011), Beijing, China, 20-23 August 2011. In Proceedings of ICEMS, 2011, p. 1-

Quality of life satisfaction among converted Kelantan Chinese Muslims

This article investigates the quality of life of the Kelantan Chinese Muslim community before and after conversion to Islam, focusing on their level of satisfaction in term of economic aspect. This research was carried out using the sequential explanatory mixed method design involving 75 respondents selected for quantitative and five respondents for qualitative. The sampling method adopted was convenience and snowball samplings. The research data was collected using questionnaires and semi-structured interviews. The results revealed that respondents were moderately satisfied before conversion and satisfied after conversion. Besides that, there is no significant difference of quality of life before and after conversion to Islam (F = 0.868, p = 0.355) and it was not influenced by the period of conversion to Islam (F = 0.832, p = 0.589). This analysis indicates numerous respondents are still moderately satisfied in their quality of life even though the average data shows they are satisfied after conversion

Simulation of a linear permanent magnet vernier machine for direct-drive wave power generation

This paper proposes a linear permanent magnet (PM) vernier machine for direct-drive wave power generation. Firstly, the machine structure is proposed and its parameters are indentified by finite element analysis (FEA). Secondly, the mathematical modeling of wave power absorption system was established. The control strategy for maximizing absorbed wave power is discussed. Then, by using Matlab/Simulink, the wave power generator system is modeled and simulated. A vector control scheme is implemented which controls power flow between the generator and the load via a bi-directional AC/DC converter. The simulation results verify the feasibility of the proposed machine used for direct-drive wave power generation. © 2011 IEEE.published_or_final_versionThe 2011 International Conference on Electrical Machines and Systems (ICEMS 2011), Beijing, China, 20-23 August 2011. In Proceedings of ICEMS, 2011, p. 1-

State-of-art on permanent magnet brushless DC motor drives

Permanent magnet brushless DC (PMBLDC) motors are the latest choice of researchers due to their high efficiency, silent operation, compact size, high reliability and low maintenance requirements. These motors are preferred for numerous applications; however, most of them require sensorless control of these motors. The operation of PMBLDC motors requires rotor-position sensing for controlling the winding currents. The sensorless control would need estimation of rotor position from the voltage and current signals, which are easy to be sensed. This paper presents a state of art on PMBLDC motor drives with emphasis on sensorless control of these motors

A dual-memory permanent magnet brushless machine for automotive integrated starter-generator application

This paper presents a dual-memory permanent magnet brushless machine for automotive integrated starter-generator (ISG) application. The key is that the proposed machine adopts two kinds of PM materials, namely NdFeB and AlNiCo for hybrid excitations. Due to the non-linear characteristic of demagnetization curve, AlNiCo can be regulated to operate at different magnetization levels via a magnetizing winding. With this distinct merit, AlNiCo can provide the assistance for online tuning the air-gap flux density. Firstly, the configuration of proposed machine is presented. Secondly, the finite element method (FEM) is applied for the field calculation and performance verification. Finally, both simulation and experimental results confirm that the proposed machine is very suitable for the ISG application. © 2012 IEEE.published_or_final_versio

Maximum power point tracking control of a linear magnetic-geared generator for direct-drive wave energy conversion

This paper deals with control of a linear magneticgeared permanent-magnet generator for wave power generation using maximum power point tracking (MPPT) algorithm. Firstly, the linear magnetic-geared permanent-magnet generator structure is presented. The machine modeling is established based on the finite element analysis (FEA). Secondly, by analyzing the dynamic model of the wave power, the MPPT algorithm for directdrive wave power generation is discussed. Then, the performance for maximizing wave power absorption is verified and evaluated by the circuit simulator. The results verify that the MPPT algorithm is valid for the direct-drive wave power generation.postprin

Advanced Electrical Machines and Machine-Based Systems for Electric and Hybrid Vehicles

The paper presents a number of advanced solutions on electric machines and machine-based systems for the powertrain of electric vehicles (EVs). Two types of systems are considered, namely the drive systems designated to the EV propulsion and the power split devices utilized in the popular series-parallel hybrid electric vehicle architecture. After reviewing the main requirements for the electric drive systems, the paper illustrates advanced electric machine topologies, including a stator permanent magnet (stator-PM) motor, a hybrid-excitation motor, a flux memory motor and a redundant motor structure. Then, it illustrates advanced electric drive systems, such as the magnetic-geared in-wheel drive and the integrated starter generator (ISG). Finally, three machine-based implementations of the power split devices are expounded, built up around the dual-rotor PM machine, the dual-stator PM brushless machine and the magnetic-geared dual-rotor machine. As a conclusion, the development trends in the field of electric machines and machine-based systems for EVs are summarized

Pressurized Lunar Rover

The pressurized lunar rover (PLR) consists of a 7 m long, 3 m diameter cylindrical main vehicle and a trailer which houses the power and heat rejection systems. The main vehicle carries the astronauts, life support systems, navigation and communication systems, directional lighting, cameras, and equipment for exploratory experiments. The PLR shell is constructed of a layered carbon-fiber/foam composite. The rover has six 1.5 m diameter wheels on the main body and two 1.5 m diameter wheels on the trailer. The wheels are constructed of composites and flex to increase traction and shock absorption. The wheels are each attached to a double A-arm aluminum suspension, which allows each wheel 1 m of vertical motion. In conjunction with a 0.75 m ground clearance, the suspension aids the rover in negotiating the uneven lunar terrain. The 15 N-m torque brushless electric motors are mounted with harmonic drive units inside each of the wheels. The rover is steered by electrically varying the speeds of the wheels on either side of the rover. The PLR trailer contains a radiosotope thermoelectric generator providing 6.7 kW. A secondary back-up energy storage system for short-term high-power needs is provided by a bank of batteries. The trailer can be detached to facilitate docking of the main body with the lunar base via an airlock located in the rear of the PLR. The airlock is also used for EVA operation during missions. Life support is a partly regenerative system with air and hygiene water being recycled. A layer of water inside the composite shell surrounds the command center. The water absorbs any damaging radiation, allowing the command center to be used as a safe haven during solar flares. Guidance, navigation, and control are supplied by a strapdown inertial measurement unit that works with the on-board computer. Star mappers provide periodic error correction. The PLR is capable of voice, video, and data transmission. It is equipped with two 5 W X-band transponder, allowing simultaneous transmission and reception. An S-band transponder is used to communicate with the crew during EVA. The PLR has a total mass of 6197 kg. It has a nominal speed of 10 km/hr and a top speed of 18 km/hr. The rover is capable of towing 3 metric tons (in addition to the RTG trailer)

Design, modeling, and analysis of a brushless doubly fed doubly salient machine for electric vehicles

This paper presents a new three-phase 12/8-pole brushless doubly fed doubly salient (BDFDS) machine for application to electric vehicles. It consists of two types of stator windings-polyphase armature winding and dc field winding. The key is to design, model, and analyze the proposed BDFDS machine. The output power equation is derived analytically, and the initial calculation of machine dimensions and parameters are also discussed. When we use finite-element analysis, the field distributions of the BDFDS machine at different loads and field currents are obtained, in which magnetic saturation and armature reaction are considered. Static characteristics of the proposed machine are also obtained. Based on these characteristics, the system mathematical model can be established. Hence, the evaluation of system performance is conducted by computer simulation. A 12/8-pole BDFDS machine is designed and built for experimentation. Experimental results are given to verify the theoretical analysis and simulation. © 2008 IEEE.published_or_final_versio