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Analysis on Closed Loop Control for GaN-Based CRM Totem-Pole PFC

Year: 2023 | Author: Xingyu Chen | Paper: H5.4
2.2kW two-phase
Fig 1: 2.2kW two-phase interleaving GaN-based CRM totem-pole PFC prototype.
  Power factor correction (PFC) rectifiers are widely used in electric vehicle (EV) chargers and in the power supplies for telecom or data centers in order to achieve unity power factor (PF) and to restrain total harmonic distortion (THD). The totem-pole PFC rectifier is well known for its simple topology. Recently, the totem-pole PFC rectifier has become popular again with the help of the high-voltage gallium-nitride (GaN) high-electron-mobility transistor (HEMT).

  In this paper, a microcontroller-based control method for the GaN-based critical conduction mode (CRM) totem-pole PFC is proposed. A simple digital control method based on a synchronous rectifier (SR) on-time calculation -- which ensures zero-voltage switching (ZVS) without zero-current detection (ZCD) -- is proposed. Average current-mode control is discussed and a compensator gain adjustment method is introduced to improve PF and restrain THD. Finally, all control functions are integrated into a microcontroller unit (MCU) and demonstrated on a 2.2kW GaN-based two-phase interleaved CRM totem-pole PFC prototype, as shown in Fig. 1. Fig. 2 shows the control diagram. Also, the proposed control strategy is compared to the traditional ZCD-based control.

  The prototype with proposed control method can reach a peak efficiency of 98.96% and full-load efficiency of 98.55%. The converter reaches a PF of 0.996 at full load.

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