Chongming Qiao

A topology survey of single-stage power factor corrector with a boost type input-current-shaper

A topological review of the single stage power factor corrected (PFC) rectifiers is presented in this paper. Most of reported single-stage PFC rectifiers cascade a boost type converter with a forward or a flyback DC-DC converter so that input current shaping, isolation, and fast output voltage regulation are performed in one single stage. The cost and performance of a single-stage PFC converters depend greatly on how its input current shaper (ICS) and the DC-DC converter are integrated together. For the cascade connected single-stage PFC rectifiers, the energy storage capacitor is found in either series or parallel path of energy flow. The second group appears to represent the main stream. Therefore, the focus of this paper is on this group. It is found that many of these topologies can be implemented by combining a 2-terminal or 3-terminal boost ICS cell with DC-DC converter along with an energy storage capacitor in between. A general rule is observed that translates a 3-terminal ICS cell to a 2-terminal ICS cell using an additional winding from the transformer and vice versa. According to the translation rule, many of reported single-stage PFC topologies can be viewed as electrically equivalent to one another. Several new PFC converters were derived from some existing topologies using the translation rule.

A general three-phase PFC controller for rectifiers with a parallel-connected dual boost topology

A general constant-frequency power-factor-correction (PFC) controller is proposed for three-phase rectifiers with parallel-connected dual-boost topologies. This paper shows that unity power factor and low current distortion in all three phases can be realized by one-cycle control using one integrator with reset along with a few near and logic components. This new extension of one-cycle control provides the core PFC function to the dual-boost topologies. It does not require multipliers, as used in most other control approaches to scale the current reference according to the output power level. In each 60/spl deg/ of AC line cycle, only two switches are switched at high frequency; therefore the switching losses are significantly reduced. All switches are switched at low current, which results in reduced current ratings. This control method is simple and general. It is applicable to three-phase rectifiers that can be decoupled into parallel-connected dual-boost topologies by slight modification of the logic circuit. This control method is verified by experimental results. The proposed controller is suitable to be integrated into a three-phase PFC control chip.

Three-phase unity-power-factor star-connected switch (VIENNA) rectifier with unified constant-frequency integration control

A unified constant-frequency integration (UCI) controller for a three-phase star-connected switch three-level rectifier (VIENNA) with unity-power-factor-correction is proposed. One of advantages of this rectifier is that the switch voltage stress is one half of the total output voltage. The proposed control approach is based on one-cycle control and features great simplicity and reliability: all three phases will be power factor corrected using one or two integrators with reset along with several flips-flops, comparators and logic and linear components. It does not require multipliers to scale the current reference according to the output power level as used in many other control approaches. In addition, the input voltage sensor is eliminated. It employs constant switching frequency modulation that is desirable for industrial applications. The proposed controller can operate by sensing either the inductor currents or the switching currents. If the switching currents are sensed, the cost is further reduced because switching currents are easier to sense comparing with inductor currents. The proposed approach is supported by experimental results.

Unified constant-frequency integration control of three-phase standard bridge boost rectifiers with power-factor correction

In this paper, a three-phase six-switch standard boost rectifier with unity-power-factor correction is investigated. A general equation is derived that relates the input phase voltages, output DC voltage, and duty ratios of the switches in continuous conduction mode. Based on one of the solutions and using one-cycle control, a unified constant-frequency integration controller for PFC is proposed. For the standard bridge boost rectifier, a unity power factor and low total harmonic distortion can be realized in all three phases with a simple circuit that is composed of one integrator with reset along with several flips-flops, comparators, and some logic and linear components. It does not require multipliers and three-phase voltage sensors, which are required in many other control approaches. In addition, it employs constant-switching-frequency modulation that is desirable for industrial applications. The proposed control approach is simple and reliable. All findings are supported by experiments.

One-cycle control of three-phase active power filter with vector operation

Active power filters (APFs) provides an effective measure to eliminate the power line harmonic/reactive currents generated by nonlinear loads or by distributed energy sources that are connected to the grid. Active power filters are typically connected in parallel to the harmonic/reactive current sources and cancel the harmonic/reactive components in the line current so that the current flow into and from the grid is sinusoidal and in phase with the grid voltage. Since the APFs process only the harmonic/reactive power, their power-handling capability can be much higher than that of the cascade power-factor-correction methods. In this paper, the one-cycle control method is extended to control three-phase APFs. The proposed control approach employs one integrator with reset along with several logic and linear components to control a voltage-source converter to achieve three-phase unity power factor for the current to and from the power grid. No multipliers or sensors for the load current and the APF inductor current are required. Furthermore, there is no need to calculate the reference for controlling APF inductor current so that complicated digital computation is eliminated. The operation switching frequency is constant that is desirable for industrial applications. The proposed control approach features great simplicity, excellent harmonic/reactive current cancellation, and solid stability. It is a cost-effective solution for power quality control for electronic equipment, buildings, industrial facilities, ships, airplanes, distributed power generation stations, etc. All findings are supported by experimental results.

Three-phase grid-connected inverters interface for alternative energy sources with unified constant-frequency integration control

A new control approach for three-phase grid-connected inverters is presented. The inverter stage is a standard three-phase half bridge. During each 60/spl deg/ of line cycle, the three-phase half bridge can be de-coupled into parallel-connected dual-buck inverter. Based on one-cycle control, a unified constant-frequency integration controller (UCI) is proposed for the dual-buck inverter. The controller is comprised of an integrator with reset, along with some linear and logic components. No multipliers are required. Low current distortion and unity-power-factor are achieved in the control loop. The input to the inverter can be fuel cells, photovoltaic power, wind power, etc. The three-phase currents injected to the grid are sinusoidal. The simplicity and performance of the proposed inverter make it a good candidate for grid-connected alternative energy generation.

Three-phase bipolar mode active power filters

In this paper, a unified constant-frequency integration control method for a three-phase bipolar mode active power filter is proposed. The proposed control method eliminates the use of any multipliers, the need of sensing three-phase load current, and the nontrivial task of calculating the harmonies and reactive current components, as required by previously reported control methods. By applying one-cycle control and sensing the mains line current, unity power factor and low input current distortion can be realized by one integrator with reset along with a few linear components such as flip-flops, comparators, and clock. The proposed controller is simple, robust, and reliable. All findings are supported by simulation and experiments.

Three-phase unity-power-factor VIENNA rectifier with unified constant-frequency integration control

A unified constant-frequency integration (UCI) controller for a three-phase three-switch three-level rectifier (VIENNA) with unity-power-factor-correction is proposed. One advantage of the VIENNA rectifier is that the switch voltage stress is one half of the total output voltage so that MOSFETs can be used. The proposed control approach is based on one-cycle control and features great simplicity and reliability: all three phases will be power factor corrected using one integrator with reset along with several flips-flops, comparators and logic and linear components. It does not require multipliers to scale the current reference according to the output power level as used in many other control approaches. In addition, the input voltage sensor is eliminated. It employs constant switching frequency modulation that is desirable for industrial applications. The proposed controller can operate by sensing either the inductor currents or the switching currents. If the switching currents are sensed, the cost is further reduced because switching currents are easier to sense compared with inductor currents. The proposed approach is supported by experimental results.

Unified constant-frequency integration control of three-phase standard bridge boost rectifier

In this paper, a three-phase six-switch standard boost rectifier with unity-power-factor-correction is investigated. A general equation is derived that relates input phase voltage and duty ratios of switches in continuous conduction mode. Based on one of solutions and using one-cycle control, a unified constant-frequency integration (UCI) controller for power-factor-correction (PFC) is proposed. For the standard bridge boost rectifier, unity-power-factor and low total-harmonic distortion (THD) can be realized in all three phases with a simple circuit that is composed of one integrator with reset along with several flips-flops, comparators, and some logic and linear components. It does not require multipliers and three-phase voltage sensors, which are used in many other control approaches. In addition, it employs constant switching frequency modulation that is desirable for industrial applications. The proposed control approach is simple and reliable. Theoretical analysis is verified by simulation and experimental results.

A single-phase active power filter with double-edge integration control

A control method for a single-phase active power filter (APF) is presented. The proposed method controls a half bridge shunt APF based on double-edge one-cycle control and mains current sensing. The half-bridge APF is connected in parallel to one or a group of nonlinear loads. The control goal is for the half-bridge APF to produce reactive and harmonic current that cancels the one generated by the nonlinear load. This control method dose not need to create a current reference, hence the burdensome obligation of dynamically sensing the load current as well as calculating the harmonics and reactive current components of the load, as required by most previously reported control methods, is eliminated. The control circuit contains an integrator with reset along with a few linear and logic components. No multipliers are used. No input voltage sensor is required. The operation switching frequency is nearly constant in most of the load range that is desirable for industry applications. The control method features wide stability, great simplicity, high reliability, and low cost. A 200 W prototype was built and experimental results are provided.