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A Novel Soft Switching ZVS, Sinusoidal Input Boundary Current Mode Control of 6-Switch Three-Phase 2-Level Boost Rectifier for Active and Active + Reactive Power Generation
Year: 2018 | Author: Nidhi Haryani | Paper: T2.2
Fig. 1. Phase currents in soft switching TCM (a) UPF; (b) 30° phase lag; and (c) 90° phase lag.
Conventional CRM for a three phase single switch boost power factor correction (PFC) does not generate sinusoidal average input current. This issue has been addressed for a Vienna rectifier (VR) operating as a PFC, and it is shown that sinusoidal average input current can be achieved by adding one more switching state in between three switching states of conventional CRM. The three phase 6-switch boost converter has lesser semiconductors and thus lower losses as compared to VR. However, the above modulation cannot be directly applied to a three phase 6-switch 2-level boost converter.
A new BCM/transition conduction mode (TCM) control with different switching states, a complete ZVS turn-on, and sinusoidal average input current for three phase 6-switch 2-level boost PFC is presented in this paper. This modulation is further extended for varying power factors. Two cases, active and reactive power, are elaborated. The basic idea of TCM in unity power factor (UPF) mode comes from expressing average phase currents as directly proportional to phase voltages as shown in Fig. 2 (a). The reactive power generation case can be expressed as the sum of two voltage phasors as shown in Fig. 2 (b). The loss breakdown comparison between CCM and TCM for UPF mode is shown in Fig. 2 (c).
Fig. 2. (a) Phasor average currents for u.p.f. mode (b) Phasor average currents with a phase lag (c) Loss comparison of three phase 2-level converter between CCM at 50 kHz and TCM at 1 MHz in u.p.f. mode.
