tailieunhanh - Recent Developments of Electrical Drives - Part 21

Recent Developments of Electrical Drives - Part 21. The book stating the recent developments of electrical drives, can be useful for engineers and researchers investigating and designing electrical and electronic devices as well as for students and young researchers dealing with electrical and electronic engineering, computer sciences (advanced computer modelling, sophisticated control systems with artificial intelligence tools applied, optimal design bye use of classical and genetic algorithms employed), applied mathematics and all the topics where electromagnetic, thermal, mechanical phenomena occur | 192 D hulster et al. determined according to an optimization criterion. The current can be controlled using a hysteresis or PWM control technique. With a PWM current controller the system produces less acoustic noise due to the fixed switching period but its PI control parameters must be selected carefully. In addition to this basic structure also different torque ripple reduction principles can be implemented of which examples in 4 5 . Voltage-speed relationship So far not much research is done on the control of SRMs under different supply voltage conditions. Reference 6 proposes a maximum torque control strategy during short disturbances in the dc-link voltage due to voltage sags or load transients. For steady state behavior 7 describes the similarity between supply voltage decrease and rotor speed increase on the current waveform of SR generators. This reduces the number of parameter sets in the drive. Equation 1 can be rewritten to Ç u di d 1 df i e di - Ri d i 0 d0 5 Relation 5 states that for a given phase current behavior a relation exists between the phase voltage and the rotor speed u - Ri ------ cst 6 For a given voltage u speed oi u and reference torque the optimal control parameters can be obtained from the parameter set defined for uref using an equivalent rotor speed m uref uref R iref uref -------- u 7 u R iref 7 with -iref. reference phase current A - uref. reference phase voltage V . An example of this relation between supply voltage and rotor speed is given in Fig. 5 with the numerical simulation results in Table 1. If the control is to be optimized for a supply voltage range u uref in a motor speed range 0 max then the equivalent optimal control parameters must be calculated for the uref R iref supply voltage uref in a speed range 0 max d if _ Table 1. Numerical steady state simulation results rad s u V Tm Nm Pm W Peu W PFe W nm 432 290 928 119 59 200 145 450 122 20 193 II-5. Optimal Switched Reluctance Motor Control .