2 kW active power factor correction circuit design - Power Circuit - Circuit Diagram

Abstract: Active power factor correction (PFC) technology can significantly reduce harmonic pollution caused by power equipment to the power grid while improving the power factor at the input end of electrical devices. This paper delves into the principles of active power factor correctors (APFC) and designs a 2 kW active PFC circuit utilizing the average current control mode. Experimental results demonstrate that the APFC circuit, with TDA16888 as its core, can produce a stable 380V DC output voltage across an input voltage range of 90-270V, achieving a power factor as high as 0.99. The system's performance is exceptional. Keywords: Average current control; Power factor correction; Harmonic pollution; Active power factor correction (APFC)


1. Introduction: Currently, the power preamplifiers of household appliances commonly use diode full-bridge rectification, which generates harmonic pollution to the power grid, resulting in a decreased power factor. The reactive component primarily consists of high-order harmonics, where the third harmonic amplitude is about 95% of the fundamental frequency, the fifth harmonic is around 70%, and the seventh harmonic is roughly 45%. These higher-order harmonics can damage the power grid, reduce the input power factor of electrical equipment, and generate significant electromagnetic interference (EMI), posing potential risks to the safe operation of the grid and other devices. Active power factor correction (APFC) transforms the input current of the power supply into a sine wave synchronized with the input mains voltage, thus enhancing the power factor of the equipment and minimizing harmonic pollution to the grid. Theoretically, various converter topologies like Buck, Boost, Boost-Buck, and Flyback can serve as the main circuit for APFC. Among these, Boost APFC stands out due to its simplicity, high power factor, low total harmonic distortion (THD), and efficiency. Although the output voltage exceeds the input voltage, it is ideal for applications ranging from 75W to 2000W, making it widely adopted. Given the continuous inductor current in Boost APFC, the energy storage inductor functions as a filter to suppress radio frequency interference (RFI) and EMI noise, protecting the main circuit from high-frequency transients originating from the power grid. Furthermore, the Boost topology expands the allowable input voltage range to 90-270V, improving adaptability, simplifying control, and offering a broad power range. Therefore, this paper proposes a 2kW Boost-based APFC circuit controlled by the TDA16888, capable of boosting the power factor above 0.99.

2. Boost APFC Circuit Principle: There are three primary methods of controlling Boost APFC: (1) Peak Current Control: The switch frequency remains constant, operating in Continuous Conduction Mode (CCM). By detecting the switch current and controlling the peak value of the inductor current (as the reference), this method is sensitive to noise and prone to control errors. (2) Hysteresis Current Control: The switch frequency varies, also operating in CCM. By detecting the inductor current, this method is highly dependent on the load size, leading to a large variation in switching frequency. When designing the output filter, one must consider the minimum frequency, making it challenging to achieve a compact and lightweight design. (3) Average Current Control: The switch frequency is fixed, allowing for arbitrary working modes. By detecting the inductor current and amplifying the current error signal, this method ensures that the peak value of the power frequency current equals the average of the high-frequency current. The peak value of the high-frequency current is higher than that of the power frequency current, resulting in minimal THD, insensitivity to noise, and small errors between the peak and average inductor current values. It can operate in both CCM and Discontinuous Conduction Mode (DCM) and is suitable for any topology.

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