Harmonic Analysis and Suppression for Electrical Systems Supplying Static Power Converters and Other Nonlinear Loads

A review of active filters for power quality improvement

“…A major volume of work is reported [167]- [192] on the theories related to the detection and measurement of the various quantities, such as real power, reactive power, etc., in the presence of harmonics in the supply systems with nonlinear loads. These theories and concepts are quite relevant to extract the control signals for AF's and for the development of instruments to measure conventional and newly defined quantities in the presence of harmonics and unbalance.…”

“…In the first stage, the essential voltage and current signals are sensed using power transformers (PT's), CT's, Hall-effect sensors, and isolation amplifiers to gather accurate system information. In the second stage, compensating commands in terms of current or voltage levels are derived based on control methods [167]- [192] and AF configurations. In the third stage of control, the gating signals for the solidstate devices of the AF are generated using PWM, hysteresis, sliding-mode, or fuzzy-logic-based control techniques.…”

“…Subtracting load currents from reference supply currents, compensating commands are derived. The different theories and concepts reported to support the various control methods can be found in [167]- [192].…”

“…The first [1]- [25] is on general development and survey of harmonic problems, while the second to fourth categories are on two-wire (single phase) [26]- [55], three-wire (three phase without neutral) [56]- [155], and four-wire (three phase with neutral) [156]- [166] AF's. The fifth category [167]- [192] includes the publications on theories of harmonics and reactive power associated with nonlinear loads. The sixth and final category of publications [193]- [223] is on the reactive power and load-balancing compensators.…”

A novel efficiency‐enhancement topology: GaN high‐electron mobility transistors with waveform‐modulation structure composed of Schottky diodes

“…Assuming the signal injecting the GaN HEMT is monosonic cosine signal and the voltage amplitude is A, due to the nonlinearity of the gate capacitance of the GaN HEMT, the voltage response of V g has the form of a polynominal formula of , in which the high‐order terms are nonlinearity induced components. Derivation based on De Moivre's theorem in shows that the odd order terms will affect the amplitude of the fundamental wave, and the even order terms will increase the dc component causing larger average drain current as shown in Formula ; a more detailed analysis of the relationship between drain current and nonlinearity of gate capacitance is demonstrated in Kheirkhahi et al When the antiparallel SBD is put at the input of the GaN HEMT, the high‐order terms in Formula produced by the junction capacitance of the SBD will partially offset the high‐order terms produced by the gate capacitance of the GaN HEMT; specially, the reduction of the even terms will reduce the dc component of the gate voltage, which is beneficial to reducing the operating current and improve PAE. …”