Permanent Magnet Direct Current Motor Research Articles

Design of a Flux-Shunt Permanent Magnet DC Motor With Hybrid Magnetomotive Force and Anti-Demagnetization Property

Rare-earth magnets of high-energy products have been widely used to improve the efficiency, as well as the power and torque per unit weight, of permanent-magnet machines. In addition to the drawbacks of limited resources and high prices, the rare-earth magnet may risk irreversible demagnetization during field weakening or malfunctioning in machine operation. To solve this problem, we investigate the antidemagnetization property due to the flux shunt mechanism and hybrid magnetomotive force in a permanent-magnet direct-current motor. The hybrid magnetomotive force is provided by low-grade permanent magnets and additional field windings, between which are ferromagnetic media that shunt the adjustable magnetic flux in the machine. We performed an optimal machine design and verified it with a finite-element analysis. We fabricated a prototype, and the experimental results show that machine efficiency and torque are increased by increasing the current of the field winding and that machine speed can be extended by reducing the field current. Finally, we proved that the antidemagnetization mechanism is effective by investigating the reduction of back electromagnetic force after demagnetization.

Electric motor-assisted pedal-driven tricycle

Tricycles or cycle rickshaws are driven by manual pedalling, which is a very strenuous job for rickshaw pullers. On the other hand, auto rickshaws are driven by fossil fuel, which produces too much environmental pollution, especially in the busiest streets of a city, where the average running speed cannot be more than 15 km hr−1. The electric three-wheelers, which contribute less towards air pollution, are completely driven by electric motors and require a large-capacity motor and battery. The drive system of these electric vehicles in general is very complicated, as it includes a heavyweight Permanent Magnet Direct Current (PMDC) motor, gearbox, gear-changing mechanism, clutch and others. Considering the above facts, a novel three-wheeled vehicle or pedicab was developed at Central Mechanical Engineering Research Institute (CMERI), Durgapur, India. It is lightweight and can be driven manually with the assistance of an electric motor. It is called the electric motor-assisted pedal-driven tricycle. The combination of pedal and electric motor reduces the drudgery of rickshaw pullers as well as minimises the utilisation of electric energy. Also, due to simultaneous utilisation of electric and manual power, this tricycle produces almost zero greenhouse gases and thus it may be considered one of the future green vehicles, suitable for short-distance transport.

Injection molded asymmetric spur gear — development and preliminary performance evaluation

Innovative gear designs are essential to meet the increasing demands of high load carrying capacity, high endurance, low cost, long life, and high speeds in automobile, aerospace, and wind turbine industries. Conventional gears are having symmetric teeth; however most of the applications necessitate power/motion transmission in one direction. This unidirectional transmission leads to the design of asymmetric teeth in a gear. Extensive research work on design and optimization and asymmetric gear tooth profile for improved bending and contact strength has been attempted. However, very little experimental investigation has been attempted and no work has been attempted in the experimental investigation of asymmetric polymeric gears. In this work, unreinforced polypropylene material is injection molded for the asymmetric spur gears. Gears are molded to the size of 3 mm module, 18 number of teeth and having pressure angle of 34° and 20° at drive and coast side respectively. To examine surface durability and the kinematic characteristics of asymmetric gear, a gear test rig is developed in the laboratory with permanent magnet direct current motor and powder clutch dynamometer as driving and power absorption unit with necessary inline torque sensors and non contact temperature sensor. Preliminary transmission efficiency and surface temperature of test gears promises wide scope for asymmetric composite gears in motion transmission application. Due to the increase in pressure angle at drive side of gear tooth, relative sliding velocity found to decrease and hence asymmetric gear exhibit superior gear pair efficiency and less surface temperature.

Design and experiment of electric bus

Performance and reliability experiments on BJD-6100EV electric buses, jointly developed by Beijing Institute of Technology and Beijing Public Transport Company, are introduced. Output power model of battery pack is established and maximum output power is analyzed. A permanent magnetic direct current (PMDC) motor with enhanced windings is developed for the bus. Torque-speed characteristics of the motor are modeled and performance of electric bus is analyzed. Computational method of the range of electric bus is proposed and discussed. Experiments show that electric bus can realize design requirements. Computational methods are verified with the help of field test. It is expected that design and computation method will provide helpful reference to development of electric vehicles.

Modelling of the steady state thermal behaviour of a permanent magnet direct current motor with commutator. 3D finite elements study

The aim of this work concerns the development and the validation of a thermal steady state model applied to a permanent magnet direct current motor with commutator. The rated power of the machine is 120 W. Design has been realized thanks to the thermal modulus of the computation software with the finite element method Flux3D. It is shown in this work how it is possible to use only the heat equation to simulate the thermal behaviour of the motor. It implies calculating of new fluid conductivities (considering also all thermal modes) by comparison of calculated and experimental temperatures. To realize these 3D modelizations, it is necessary to know and to locate all the losses of the motor which are considered as thermal sources. The experimental temperatures are given by 40 chromel-alumel thermocouples of 100 μm diameter located in the rotor and the stator of the machine. Numerical computations use Dirichlet boundary layer conditions given by an IR camera.

The effects of the number of rules on the output of a fuzzy logic controller employed to a PM d.c. motor

This paper investigates the effects of the number of the rules in a fuzzy logic controller (FLC). In addition, a novel approach to form the linguistic fuzzy subsets and fuzzy rule decision tables is also introduced. The proposed method to form the fuzzy rule tables is based on the comparison of possible transient responses of the controlled system output and the reference set point. The relationship between the number of fuzzy rules and the controlled output signal for a permanent magnet direct current (pmdc) motor circuit is investigated using a three-dimensional output expression. Since the relationship between the input and output is smooth, the effect of the number of the rules are negligible as long as they express a similar relationship. The sensitivity of the FLC with respect to variations in the rule decision tables is also tested by changing the original decision table values in the range of ±30%. It is observed that these variations in the rule decision tables do not cause any instability in the proposed fuzzy logic controller.

A method to form fuzzy logic control rules for a PMDC motor drive system

This paper investigates the application of a fuzzy-logic-based high performance speed control system for a permanent magnet direct current (PMDC) motor. The main contribution of this paper is the approach that is used to form the linguistic fuzzy subsets and fuzzy rule decision table for the fuzzy logic controller (FLC). The proposed method for the fuzzy rules is based on the comparison of possible transient responses of the system output and the reference set point. Desired performance of the overall scheme was obtained by simulation, and the related results are given in the paper.

Self-starting permanent-magnet a.c. motors

Many of the earliest dynamo-electric machines had permanent-magnet excitation. Gradually, however, this form of excitation was replaced by excitation from electromagnets, which seemed to offer the advantage of stronger magnetic fields and so more power from a total volume of material. Since then, many signs have appeared that indicate a reversal of this trend. Small permanent-magnet direct-current motors are commonplace in automobiles. Perhaps most interestingly, new forms of alternating-current machine using permanent magnets have begun to appear, and these show some interesting advantages compared with alternative drive systems. The self-starting permanent-magnet synchronous motor is essentially a new form of motor with a wide variety of applications