Performance of power-electronic drives with respect to speed and torque

At the outset closed-form and numerical solution techniques for variable-speed, variable-torque drives, and review of circuit approximations suitable for numerical solutions are discussed. Equivalent circuits for nonideal lead-acid and lithium-ion batteries as well as nonideal fuel cells are introduced and relied on for storage components supplying energy to electric cars and distribution systems. Operating-point–dependent equivalent circuits of synchronous, induction, and permanent-magnet machines are introduced. In particular, the leakage reactance definition from stator to rotor of permanent-magnet is explained by introducing a virtual rotor winding replacing the permanent magnet of the rotor. For inverter-fed machines, the proper design of waveshaping inductance is important. Energy savings of heat pumps, renewable power plants (e.g., WP and PV plants), and the need for nuclear plants as well as for electric cars supplied either by batteries or fuel cells are addressed. The charging and discharging properties of batteries from and into the three- and single-phase power systems are investigated, whereby harmonic filters play an important role for improving power quality of AC to DC and DC to AC transformations. Selection of appropriate transformers and rectifiers/inverters is needed. The energy support of the distribution system via inverter-controlled batteries will gain importance for the operation of a system with renewable sources: Batteries and fuel cells can serve as energy storage devices. Speed and torque control of electric drives—based on induction, synchronous, and inverter-fed permanent-magnet machines also called brushless DC machines—is critical for the success of electric automobiles, buses, and trains. To keep the battery and fuel cell voltage as low as possible compensation of flux weakening is advantageous. Of utmost importance are the performance issues of drives with batteries and fuel cells.