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In order to implement a high-efficiency bridgeless power factor correction converter, a new topology and operation principles of continuous conduction mode (CCM) and DC steady-state character of the converter are analyzed, which show that the converter not only has bipolar-gain characteristic but also has the same characteristic as the traditional Boost converter, while the voltage transfer ratio is not related with the resonant branch parameters and switching frequency. Based on the above topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. With this converter, the diode rectifier bridge of traditional AC-DC converter is eliminated, and zero-current switching of fast recovery diode is achieved. Thus, the efficiency is improved. Next, we also propose the one-cycle control policy of this converter. Finally, experiments are provided to verify the accuracy and feasibility of the proposed converter.

A great number of harmonic currents, which are caused by nonlinear loads connected to grid, are main pollution sources of power system and important factors in the safe operation of the grid. In order to reduce the harmonic pollution, the active power filter (APF) and power factor correction (PFC) are required, which are applied to control the harmonic and reactive current generated from rectifier loads. PFC converter can realize the AC input current control and DC output voltage control at the same frequency and phase with AC voltage, and thus it is widely used in server power [

In order to improve efficiency of the traditional PFC converter, an effective method named as bridgeless PFC technology without front-end bridge rectifier is proposed [

In this paper, we research a novel Pseudo-Boost converter, which has bipolar-gain characteristic; that is, no matter if the input voltage is positive or negative, the output voltage is always positive, and the converter also has the same characteristic as the traditional Boost converter. Although the converter has a resonant branch, the difference from the traditional resonant converter is that the voltage transfer ratio is not relevant to the resonant branch parameters and switching frequency; it only depends on the switching duty cycle. Based on the Bipolar-Gain Pseudo-Boost converter, a bridgeless Bipolar-Gain Pseudo-Boost PFC converter in continuous conduction mode (CCM) is investigated. The converter adopts one bidirectional controllable switch and two fast-recovery diodes instead of bridge rectifier, and the zero-current switching of the fast-recovery diodes is achieved. Therefore, the efficiency of the converter is improved. Meanwhile, the one-cycle control technology is adopted to control the Bipolar-Gain Pseudo-Boost PFC converter.

The topology of the Bipolar-Gain Pseudo-Boost converter consists of switch

All of the switches, diodes, inductors, and capacitors are ideal.

Output capacitor

Resonant inductor

The converter operates in CCM.

The topology of Bipolar-Gain Pseudo-Boost converter.

The operation modes of Bipolar-Gain Pseudo-Boost converter operate in CCM with positive input voltage (Figure

Equivalent circuit of operation mode of the converter with positive input voltage.

Mode 1

Mode 2

Mode 3

The key waveform of the converter with positive input voltage.

(1) Mode 1 [

(2) Mode 2 [

(3) Mode 3 [

When the resonant capacitor voltage rises to

Figure

Equivalent circuit of operation mode of the converter with negative input voltage.

Mode 4

Mode 5

Mode 6

The key waveform of the converter with negative input voltage.

(1) Mode 4 [

(2) Mode 5 [

(3) Mode 6 [

When the resonant capacitor voltage decreases to

There are four state variables in Bipolar-Gain Pseudo-Boost converter. One is the energy storage state variable

For positive input voltage, from Figures

From Figure

The above analysis shows that the resonant capacitor voltage satisfies (

The matrix representation of the state variables is

According to GSSA approach, for positive input voltage, the GSSA equation of the Bipolar-Gain Pseudo-Boost converter can be obtained as

The equation

For negative input voltage, from Figure

From Figure

From Figure

According to the above analysis, it can be seen that the resonant capacitor voltage satisfies (

The matrix representation of the state variables is

Therefore, for negative input voltage, the GSSA equation of the Bipolar-Gain Pseudo-Boost converter can be obtained as

The equation

According to (

The voltage transfer ratio of traditional DC-DC converter is unipolar, which means that it only makes positive and negative input voltage transfer to positive output voltage. However, the PFC converter belongs to AC-DC converter, which makes AC input voltage transfer to DC output voltage. Hence, the traditional DC-DC converter cannot be used as PFC converter. To realize PFC, the most direct way is combining a front-end bridge rectifier with a DC-DC converter. Assume that the voltage transfer ratio of DC-DC converter is bipolar; that is, no matter if the input voltage is positive or negative, the output voltage is always positive. This DC-DC converter can realize AC-DC transformation, which eliminates the bridge of traditional AC-DC converter and improves the efficiency of the converter.

According to the steady state characteristic of Bipolar-Gain Pseudo-Boost converter, it is shown that the converter has bipolar-gain characteristic. So the Bipolar-Gain Pseudo-Boost converter can be used as PFC converter. From Figure

The topology of bridgeless Bipolar-Gain Pseudo-Boost PFC converter.

From the preceding analysis, the achievement conditions of bridge Pseudo-Boost PFC converter are as follows.

From Figures

The choice of inductor

The input current effective value is

The choice of resonant branch parameters: from (

From (

Figure

Block diagram of one-cycle control bridgeless Bipolar-Gain Pseudo-Boost PFC converter.

The output voltage

According to the principle of one-cycle control, it can be obtained that

When (

In order to verify the accuracy of the theoretical analysis, a set of experiments are designed. According to (

Figure

Waveforms of DC output voltage

Figure

Efficiency of the converter with 100 V DC output voltage.

Figures

The key operation waveforms of the converter (a) with positive input voltage and (b) with negative input voltage.

The measured harmonic contents of the line current at 100 V AC input voltage are shown in Figure

Measured harmonic contents of the proposed converter.

Measured PF value at full load of the proposed converter as the function of input voltage.

In this paper, we research the Bipolar-Gain Pseudo-Boost converter, and the topology and operation principles in CCM and DC steady-state character of this converter are analyzed. Based on this topology, a novel bridgeless Bipolar-Gain Pseudo-Boost PFC converter is proposed. In addition, the implement condition of the bridgeless PFC and control technology of the converter is studied. The experiments show that the proposed converter is capable of achieving the PFC better, and zero-current switching of the fast recovery diode is achieved. Moreover, the reverse-recovery loss of the diode is reduced and the efficiency of the converter is improved.

The authors declare that there is no conflict of interests regarding the publication of this paper.

This work was supported by the Applied Basic Research Programs of Technology Department under Foundation of Sichuan Province of China (no. 2012JY0120/12209596), Technology Support Programs of Technology Department of Sichuan Province (no. 2013GZ0130), the Educational Commission of the Sichuan Province of China (no. 11ZA003/11209435), the Key Programs of Xihua University (no. Z1120940), and Key Laboratory of University Project of Sichuan Provincial (application promotion and solar technology integration).