brushless dc motor
There are no generalized data on the motor performance maps in the literature. The only data available are the separate results for different motors obtained from test beds run under constant loading conditions. Accordingly, one of the goals of this effort is to generalize the data in a form of generalized motor perfo rmance maps which could cover the whole family of the specific motor of different rated power under dynamic load operation. In practice, motors operate in the factories with a changing environment such as different room temperatures, load and velocity profiles, and the type of tasks. As a result, the motor loading happens to be non-stationary and stochastic variables. However, the influence of load variation on motor performance has not received proper attention from engineers. That is, the motor catalogs and brochures are not presenting enough information about the response to non- linear, periodic loadings . Therefore, the first goal of this study will be development of the test protocols to generate the motor performance maps under variable loadings. Additionally, the parasitic motor characteristic like torque ripple will be identified in different operating ranges. Finally, in order to cover completely the operational range of the specific motor, the test regime for the response time will be presented. All of the test regimes established in this report are based on the performance criteria developed in
Before the test methods for Brushless DC Motor (BLDCM) are further discussed, the origin of the performance criteria should be mentioned in this section. From discussions with prime mover suppliers (motor catalogs), it is apparent tha t only general performance descriptions are provided. Examples of these are motor power, torque-speed relationship, motor efficiency, etc. Most of these parameters are one-dimensional and rarely twodimensional. In reality, a prime mover has a multitude of parameters that affect overall performance. A detailed understanding of these cross-couplings and parameters is an essential first step towards improved performance. Development of these criteria and the relationships among them is the foundation to this problem. An initial listing of l0 actuator performance criteria is given in Table 2. For example, the torque generated by a motor is closely tied to its temperature. Understanding of this relationship allows us to better address the cooling needs of the actuator for various duty cycles.
response of a motor under a given load. Analysis of this property can provide us with an operational acceleration margin that can tell us how fast the acceleration follows the input torque command (i.e., in terms of step input). The difference between real output power and theoretical power computed via an analytical model is important for CBM. Such information can also allow us to anticipate power drop at higher temperatures. Sudden imp acts can often result in actuator failure. As such, the torque/force impulse response of an actuator could be an essential decision making tool for an operator.
Superimposed variations in the normal load (called torque ripple) affect actuator performance. This torque ripple has a distinct sound signature that can be detrimental for low noise applications such as deployment on submarines. At low speeds, a robot arm follows the desired path with some offset that causes tracking error. Friction in the bearings inside the actuator contributes to this offset. A detailed description of the proposed actuator criteria is presented in [10]. In this report, 6 out of 10 operational criteria for a prime mover are considered and 6 test regimes for them are suggested to obtain experimental data.