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Control of Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
Jin Ye, Haoding Li, James Weisheng Jiang
The EMF cannot be directly measured across the phase windings of the SRM. In a brushed direct current (DC) motor, the back EMF can be seen by rotating the armature in a constant magnetic field using a prime mover and measuring the voltage on the terminals. However, with the SRM, since the EMF is also dependent on the phase current, simply rotating the rotor will not produce any voltage. Should the phase be excited, only the phase voltage from the DC-link can be seen. Therefore, for the SRM, the motional EMF is fundamentally different from the back EMF on a brushed DC motor. As the motor rotates, the motional EMF is induced in the phase. This limits the growth of phase current and makes the motional EMF (induced voltage) relevant to the discussion of the dynamics of phase current in SRMs, as is outlined in (9.4). () V−εL=∂i∂t
Preliminaries for Motor Control
Published in Richard E. Neapolitan, Kwang Hee Nam, AC Motor Control and Electrical Vehicle Applications, 2018
Richard E. Neapolitan, Kwang Hee Nam
The back EMF increases as the motor speed increases. In general, motors are designed such that the back EMF reaches the maximum armature voltage vamax $ v_a^{max} $ at a rated speed ωrrated $ \omega _{r}^{rated} $ . That is, the back EMF reaches the maximum allowable source voltage at the rated speed, i.e., vamax≈Kbωrrated $ v_a^{max} \approx K_b \omega _r^{rated} $ . Then the question is “How can we increase the speed above the rated speed?” The answer is to use the field weakening control which is illustrated in the following:
Preliminaries for Motor Control
Published in Kwang Hee Nam, and Electric Vehicle Applications, 2017
The back EMF increases as the motor speed increases. The motor is designed such that back EMF eb reaches the maximum armature voltage, υamax, at a rated speed, ωrrated,i.e.,υamax≈Kbωrrated. If the speed is higher than ωrrated, the source (armature) voltage is not high enough to accommodate the back EMF. Then, the question is how to increase the speed above the rated speed.
Study on dual redundant PMSM drive design and fault-tolerant control strategy
Published in Australian Journal of Electrical and Electronics Engineering, 2019
Pan Wei, Lei Xiao, Sun Yajian, Wang Lei
The main purpose of consistency experiment is to compare the characteristics of two redundant armature winding to determine the consistency between the inherent characteristics of the redundancy. It chooses the Back electromotive force (EMF) coefficient as the test parameters. Because the back EMF coefficient is the ratio of back EMF to rotational speed and an inherent characteristic of the motor itself. The back EMF of motor is the voltage produced by the armature winding cutting the rotating magnet field and the back EMF of the motor increases with its speed. Before reaching the rated speed, the induction EMF of the motor is basically linear with the speed. The relation of back EMF and rotational speed is as follows:
Experimental Validation of Torque Ripple Reduction in MMC-Fed BLDC Motor Using the Proposed Phase Modulated Model Predictive Control
Published in IETE Journal of Research, 2023
Rahul Jaiswal, Anshul Agarwal, Richa Negi
The back EMFs of all the controllers at different switching frequencies have been analyzed. The back EMF is directly proportional to the speed of the motor. If the speed is changed, then the back EMF will change correspondingly. The back EMF is constant for PMMPC, MPC, and PI controllers due to the constant speed. From Figure 12, it has been observed that the back EMF is constant for all controllers at 1 kHz switching frequency. Similarly, the back EMF is also constant at switching frequencies of 5 and 10 kHz for all controllers, as depicted in Figures 13 and 14, respectively. Thus, these back EMFs are not affecting the performance of the BLDC motor due to its constant speed.
Introducing Analytical Formulas for Calculating Back EMF of the Contra-Rotating Double-Rotor Axial Flux Permanent Magnet Synchronous Machine
Published in Electric Power Components and Systems, 2023
Elham Rahimi Namaghi, Hamid Reza Izadfar
As mentioned earlier, the back EMF is one of the most important performance characteristics of the machine that affects machine current, efficiency, power factor, and power angle, significantly. Therefore, it is important to calculate the back EMF using analytical methods since they have less running time. The spinning magnetic fields opposing each other can be produced on both sides of the stator when two rotors rotate in two separate directions. Each of these fields causes a voltage to be induced in the arm of each coil that is positioned on each side of the stator. In the following, the back EMF waveform in each phase of the CRDR-AFPMSM is analytically formulated.