CN111030441B - Single-phase power factor correction circuit based on three-tube five-level topology - Google Patents

Abstract

A single-phase power factor correction circuit based on a three-tube five _- level topology relates to the field of power factor correction circuits, including switching tubes Q1, _Q2 , _Q3 , and the AC side of the AC power supply is respectively connected to the anode _of diode _D1 and the cathode of diode D2 , its connection node constitutes the end point b; the other side of the AC power supply AC is connected to one end of the inductor L, the other end of the inductor L is respectively connected to the anode of the diode _D3 and the cathode of the diode D4, and the connection node constitutes the end point a _; the cathode of the diode _D7 is connected to _one end of the capacitor C1 , its connection node forms the end point p; the other end of the capacitor _C1 is connected to one end of the capacitor _C2 , and its connection node forms the end point n; the other end of the capacitor _C2 is connected to the anode of the diode _D8 , and its connection node forms the end point m _; the drain of the switch tube Q1 Connect the cathode _of the diode D1 and the anode of the diode _D7 respectively, and the connection node constitutes the terminal c; the source of the switch tube _Q3 is _respectively connected to the anode of the diode D2 and the cathode of the diode _D8 , and the connection node constitutes the terminal d. The endpoints a, c, d, and n form a symmetrical four-port. The correction circuit of the present invention adopts multi-level, and has the advantages of small voltage stress of the switch tube.

Description

Single-phase power factor correction circuit based on three-tube five-level topology

technical field

The invention relates to a single-phase power factor correction circuit topology, in particular to a single-phase power factor correction circuit based on a three-tube five-level topology.

Background technique

Single-phase high power factor or power factor correction (PFC) boost converters are one of the most popular areas of research today. The main concern of this type of converter is low unity power factor and total harmonics. Usually, power factor correction is achieved by applying a boost circuit after rectification. The existing three-level topology has the shortage of the number of levels; the existing five-level topology has the disadvantages of a large number of tubes and complicated control.

SUMMARY OF THE INVENTION

The invention provides a single-phase power factor correction circuit based on a three-tube five-level topology, which is suitable for applications in medium and small power occasions. The circuit structure of the invention has the characteristics of boosting, rectifying and five-level power factor correction at the same time. Since the correction circuit of the present invention adopts a three-tube five-level topology and uses fewer switching tubes to complete the five-level rectification, the number of components required by the topology structure is less; due to the use of multi-level, the voltage stress of the switching tubes is relatively high. Small advantage.

The technical scheme adopted in the present invention is:

A single-phase power factor correction circuit based on a three-tube five-level topology includes an inductor L, switch tubes Q ₁ , Q ₂ , Q ₃ , diodes D ₁ to D ₁₁ , a capacitor C ₁ , and a capacitor C ₂ ;

_The AC side of the AC power supply is respectively connected to the anode _of the diode D1 and the cathode of the diode D2, and the connection nodes thereof constitute the terminal b;

The other side of the AC power supply AC is connected to one end of the inductor L, and the other end of the inductor L is connected to the anode of the diode _D3 and the cathode of the diode D4 respectively _; the other end of the inductor L and the connection node of the diodes _D3 and _D4 form the endpoint a;

The drain of the switch tube _Q2 is respectively connected to the cathode of the diode _D3 , the cathode of the diode _D9 , and the source _of the switch tube Q1;

_The source of the switch tube _Q2 is respectively connected to the anode of the diode D4, the anode of the diode _D10 , and the drain of the switch tube _Q3 ;

_The cathode of the diode D7 is connected to _one end of the capacitor C1, and its connection node constitutes the terminal p;

The other end of the capacitor _C1 is connected to one end of the capacitor _C2 , and its connection node constitutes the end point n;

_The other end of the capacitor C2 is connected to the anode of the diode _D8 , and its connection node constitutes the end point m;

_The drain of the switch tube Q1 is respectively connected to the cathode _of the diode D1 and the anode of the diode _{D7 ;} the connection node _of the drain of the switch tube Q1 and the diodes D1 and _D7 constitutes a terminal c;

_The source of the switch tube _Q3 is _respectively connected to the anode of the diode D2 and the cathode of the diode _D8 , and the connection node of the source of the switch tube _Q3 and the diodes D2 and _D8 forms a terminal d;

The switch tube Q1 has _an anti-parallel diode D ₅ , the switch tube Q ₂ has an anti-parallel diode D ₁₁ , and the switch tube Q ₃ has an anti-parallel diode D ₆ ;

_One end of the capacitor C1 and the other end of the capacitor C2 are respectively connected to the _two ends of the load _RL .

The endpoint a, the endpoint c, the endpoint d, and the endpoint n constitute a symmetrical four-port.

The switching transistors Q ₁ , Q ₂ , and Q ₃ are fully controlled devices, using insulated gate bipolar transistor IGBT, integrated gate commutated thyristor IGCT, or power field effect transistor MOSFET.

The capacitors C ₁ and C ₂ are series-connected DC bus split capacitors.

The present invention is a single-phase power factor correction circuit based on three-tube five-level topology, and the technical effects are as follows:

1: The innovative point of the topology structure of the power factor correction circuit: the topology structure of the present invention adopts three switch tubes to form a five-level topology structure. Since the five-level structure has a four-port symmetrical network structure and the structure is simple, it is easy to realize the control loop. design. In addition, the invented four-port network structure utilizes switch tube and diode circuit structure to realize bidirectional flow of power, and utilizes diodes D ₇ and D ₈ to realize unidirectional flow of DC bus power. This inventive topology also has the characteristics of boost boost, rectification, and five-level power factor correction.

2: A single-phase power factor correction circuit based on a three-tube five-level topology in the present invention, this topology can be used as a modular multi-level power unit due to its four-port symmetrical structure, which is easy to be extended to multi-cascade single-phase Multilevel power factor correction circuit.

3: The five-level power factor correction is integrated into the single-phase power factor correction circuit; the boost process and rectification process are introduced into the three-tube five-level topology topology, and the fusion of the application structure makes it more scalable in structure and practicability; in the topology structure, the body diode of the switch tube is used as the conduction loop for many times, and the normal power supply to the load can still be realized in the case of the loss of the switch tube turn-on pulse, and the fault loss can be reduced to a certain extent.

4: The present invention mainly realizes the function of single-phase five-level rectification by using three tubes, the topology structure is simple, and can be used as a power unit in a multi-cascade topology structure.

5: A single-phase power factor correction circuit based on a three-tube five-level topology proposed by the present invention adopts a PI double closed-loop method for control, and the outer loop adopts a voltage control loop, which is mainly used for DC side voltage stability control, and its output The result is used as the reference given quantity of the inner loop of the current; the inner loop adopts the current control loop, which is mainly used to realize unity power factor correction and reduce the harmonic content; DC voltage is stable.

Description of drawings

Below in conjunction with accompanying drawing and embodiment, the present invention will be further described:

FIG. 1 is a circuit topology structure 1 of the present invention.

FIG. 2 is a flow diagram of the switching mode of the present invention.

FIG. 3 is a second flow diagram of the switching mode of the present invention.

FIG. 4 is a three-flow diagram of the switching mode of the present invention.

FIG. 5 is a four-flow diagram of the switching mode of the present invention.

FIG. 6 is a flow diagram of five switching modes of the present invention.

FIG. 7 is a six-flow diagram of the switching mode of the present invention.

FIG. 8 is a block diagram of the topology control strategy of the present invention

FIG. 9 is a voltage waveform diagram of the input voltage V _ab of the topological rectifier of the present invention.

FIG. 10 is a topological input voltage and current waveform diagram of the present invention.

FIG. 11 is a waveform diagram of the topology output DC side current of the present invention.

FIG. 12 is a waveform diagram of the topological output DC side voltage of the present invention.

FIG. 13 is a waveform diagram of the input voltage and current of the topology load halving according to the present invention.

FIG. 14 is a waveform diagram of the output DC side current of the topology load halving according to the present invention.

FIG. 15 is a waveform diagram of the output DC side voltage of the topology load halving according to the present invention.

Detailed ways

As shown in Figure ₁ , the single-phase power factor correction circuit based on the three-tube five-level topology includes an inductor L, switch tubes Q1, _Q2 , _Q3 , diodes D1 _{- D11} , capacitor _C1 , capacitor _C2 ;

_The AC side of the AC power supply is respectively connected to the anode _of the diode D1 and the cathode of the diode D2, and the connection nodes thereof constitute the terminal b;

The other side of the AC power supply AC is connected to one end of the inductor L, and the other end of the inductor L is connected to the anode of the diode _D3 and the cathode of the diode D4 respectively _; the other end of the inductor L and the connection node of the diodes _D3 and _D4 form the endpoint a;

The drain of the switch tube _Q2 is respectively connected to the cathode of the diode _D3 , the cathode of the diode _D9 , and the source _of the switch tube Q1;

_The source of the switch tube _Q2 is respectively connected to the anode of the diode D4, the anode of the diode _D10 , and the drain of the switch tube _Q3 ;

_The cathode of the diode D7 is connected to _one end of the capacitor C1, and its connection node constitutes the terminal p;

The other end of the capacitor _C1 is connected to one end of the capacitor _C2 , and its connection node constitutes the end point n;

_The other end of the capacitor C2 is connected to the anode of the diode _D8 , and its connection node constitutes the end point m;

_The drain of the switch tube Q1 is respectively connected to the cathode _of the diode D1 and the anode of the diode _{D7 ;} the connection node _of the drain of the switch tube Q1 and the diodes D1 and _D7 constitutes a terminal c;

_The source of the switch tube _Q3 is _respectively connected to the anode of the diode D2 and the cathode of the diode _D8 , and the connection node of the source of the switch tube _Q3 and the diodes D2 and _D8 forms a terminal d;

The switch tube Q1 has _an anti-parallel diode D ₅ , the switch tube Q ₂ has an anti-parallel diode D ₁₁ , and the switch tube Q ₃ has an anti-parallel diode D ₆ ;

_One end of the capacitor C1 and the other end of the capacitor C2 are respectively connected to the _two ends of the load _RL .

The endpoint a, the endpoint c, the endpoint d, and the endpoint n constitute a symmetrical four-port. The new topology is suitable for high-voltage applications, and the topology has a four-port structure, which can be used as a modular multi-level power unit.

The switching transistors Q ₁ , Q ₂ , and Q ₃ are fully controlled devices, using insulated gate bipolar transistor IGBT, integrated gate commutated thyristor IGCT, or power field effect transistor MOSFET.

The capacitors C ₁ and C ₂ are series-connected DC bus splitting capacitors. The splitting capacitor is formed by two capacitors with the same capacitance value connected in series. It can be known from the voltage division of the capacitors in series that the capacitors with the same capacitance value in series can bear half of the series voltage, which is mainly To divide the voltage of the DC side to construct a midpoint of half of the bus voltage, the purpose is to complete the rise of the level.

As shown in Figure 1, the current i _l is the inductor output current, i _dc is the load current output value, and V _dc is the output voltage value at both ends of the load _RL . The topology uses the switching tube MOSFET anti-parallel diode as the conduction of the circuit for many times. circuit, saving design cost to a certain extent.

Single-phase power factor correction circuit based on three-tube five-level topology, including the following switching modes:

Switching mode 1: As shown in Figure 2, this time is the positive half cycle of the AC power supply AC, the switch tubes Q ₂ and Q ₃ are turned on, the current flows through the inductor L, the switch tubes Q ₂ , Q ₃ , and finally flows back through the diode D ₂ , the inductor L stores energy during this process, and the load R _L is powered by the capacitors C ₁ and C ₂ ;

Switching mode 2: As shown in Figure 3, this time is the positive half cycle of the AC power supply AC, the switch tube _Q2 is turned _on , the current passes through the inductor L, the diodes _D3 , _D10 , _D8 , D2 and the capacitor _C2 , this During the process, the AC power supply AC and the inductor L charge the capacitor C ₂ at the same time, and the load _RL is powered by the capacitor C _1. The switching process of switching mode 1 and switching mode 2 is a Boost boosting process;

Switching mode 3: As shown in Figure 4, this time is the positive half cycle of the AC power supply, and the current passes through the inductor L, diodes D ₃ , D ₅ , D ₇ , D ₈ , D ₂ and capacitors. During this process, the AC power supply AC Together with the inductor L, it supplies power to the load R _L and the capacitors C ₁ and C ₂ at the same time, and the capacitors C ₁ and C ₂ are charged;

Switching mode ₄ : As shown in Figure ₅ , this time is the negative half cycle of the AC power supply, the switching tubes Q1, _Q2 are turned _on , the current passes through the diodes D1, D4, the switching tubes _Q1 , _Q2 , and finally passes through the inductor L returns to the AC power source AC, during this process, the inductor L stores energy, and the load _RL is powered by the capacitors C ₁ and C ₂ ;

Switching mode 5: As shown in Figure ₆ , this time is the negative half cycle of the AC power supply, the switch _Q2 is turned _on , and the current passes through the diodes D1, _D8 , D4, _D7 , _D8 , _D9 and the split capacitor C ₁ , and finally, it flows through the inductor L and returns to the AC power source AC. During this process, the AC power source AC and the inductor L charge the capacitor C ₁ at the same time, and the conversion process from switch mode four to switch mode five is a boosting process;

Switching mode 6: As shown in Figure 7, this time is the negative half cycle of the AC power supply, and the current passes through the diodes D ₁ , D ₄ , D ₇ , D ₈ , D ₆ and the capacitors C ₁ , C ₂ , and returns to the inductance L. The alternating current power supply AC, in this process, the alternating current power supply AC and the inductor L supply power to the load _RL and the capacitors C ₁ and C ₂ at the same time, and the capacitors C ₁ and C ₂ are charged.

Experimental parameters:

The peak value of the AC power supply is 220V, the output DC voltage v _dc is 250V, the resistive load is 40Ω, the filter inductance is 2mH, the split capacitor C ₁ =C ₂ =1000μF, and the switching frequency is 100kHz. The topology control method is implemented as shown in Figure 8, and can be obtained from the steady-state loop voltage equation of the topology:

=γv _dc -ri _l -λv _dc

Among them, L is the linear inductance L=2mH, r is the equivalent resistance of the inductance r=0.3Ω, λ and γ are a switching function quantity 0<γ, λ<1, the pull transformation of formula (1) can be obtained:

From the proposed steady-state loop current equation, we can get:

i _l = i _c + i _dc (3)

k为一个开关比例系数0<k<1。in,

k is a switch proportional coefficient 0<k<1.

Pull transformation of equation (4) can be obtained:

The main function of the voltage outer loop is to stabilize the output voltage of the DC bus, and at the same time provide a reference current value for the inner loop. The voltage outer loop realizes voltage stability through PI control. The voltage outer loop transfer function:

Wherein, k _pv is the proportional coefficient of the voltage loop PI, and k _pv =15, k _iv is the integral coefficient of the voltage loop PI, and k _iv =0.01.

The main purpose of the application of the current inner loop is to sinusoidal the input current. The inner loop reference current value is obtained by multiplying the voltage outer loop output value and the phase-locked loop (PLL) output. The current loop PI transfer function:

Wherein, k _pc is the current loop PI proportional coefficient k _pc =10, k _ic is the current loop PI integral coefficient k _ic =0.1.

It can be seen from the control block diagram that the current loop transfer function is:

Then the closed-loop transfer function of the control system is:

9 to 12 are simulation waveform diagrams of the present invention when the medium load is 40 ohms.

FIG. 9 is a voltage waveform diagram in the series branch of the AC power supply and the inductor. It can be clearly seen in FIG. 9 that the V _ab voltage achieves five levels.

Figure 10 shows the voltage and current waveforms on both sides of the AC power supply. It can be seen that the voltage and current are in the same phase to achieve power factor correction.

Figures 11 and 12 are the waveform diagrams of the topological rectification output voltage and current, respectively. From Figures 11 and 12, it can be seen that the voltage and current changes in the waveform diagrams are consistent.

13 to 15 are waveform diagrams of the present invention when the load is reduced from 40 ohms to 20 ohms at 0.15s.

Figure 13 is a waveform diagram of the load shedding change process on both sides of the AC power supply. The load shedding is only a large change in the current waveform.

Figure 14 and Figure 15 are the current and voltage waveform diagrams during the load shedding process on both sides of the DC power supply. The load shedding doubles the current value, while the fluctuation range of the current and voltage waveforms becomes larger. The fluctuation is mainly caused by the poor filtering effect.

It can be seen from Fig. 13 to Fig. 15 that the present invention has good stability and the circuit structure can work normally and reliably.

Use diodes D ₇ , D ₈ for circuit protection as follows:

First, two diodes D ₇ and D ₈ are used to ensure the unidirectional flow of power, so that the currents of the capacitors C ₁ and C ₂ can only flow to the load _RL , and will not flow backward;

Second, when the circuit fails, it can play a good protective role;

Thirdly, in the process of mode switching, it acts as a boost clamp diode; fourthly, in switching mode 1 and switching mode 4, when the voltage of the inductor L is lower than the voltage of capacitors C ₁ and C ₂ during the energy storage process, the voltage reaches the voltage. Clamping effect.

Claims (7)

1. A single-phase power factor correction circuit based on a three-tube five-level topology, comprising an inductor L, switching tubes Q ₁ , Q ₂ , Q ₃ , diodes D ₁ to D ₁₁ , a capacitor C ₁ , and a capacitor C ₂ ; it is characterized in that : _The AC side of the AC power supply is respectively connected to the anode _of the diode D1 and the cathode of the diode D2, and the connection nodes thereof constitute the terminal b; The other side of the AC power supply AC is connected to one end of the inductor L, and the other end of the inductor L is connected to the anode of the diode _D3 and the cathode of the diode D4 respectively _; the other end of the inductor L and the connection node of the diodes _D3 and _D4 form the endpoint a; The drain of the switch tube _Q2 is respectively connected to the cathode of the diode _D3 , the cathode of the diode _D9 , and the source _of the switch tube Q1; _The source of the switch tube _Q2 is respectively connected to the anode of the diode D4, the anode of the diode _D10 , and the drain of the switch tube _Q3 ; _The cathode of the diode D7 is connected to _one end of the capacitor C1, and its connection node constitutes the terminal p; The other end of the capacitor _C1 is connected to one end of the capacitor _C2 , and its connection node constitutes the end point n; _The other end of the capacitor C2 is connected to the anode of the diode _D8 , and its connection node constitutes the end point m; _The drain of the switch tube Q1 is respectively connected to the cathode _of the diode D1 and the anode of the diode _{D7 ;} the connection node _of the drain of the switch tube Q1 and the diodes D1 and _D7 constitutes a terminal c; _The source of the switch tube _Q3 is _respectively connected to the anode of the diode D2 and the cathode of the diode _D8 , and the connection node of the source of the switch tube _Q3 and the diodes D2 and _D8 forms a terminal d; The switch tube Q1 has _an anti-parallel diode D ₅ , the switch tube Q ₂ has an anti-parallel diode D ₁₁ , and the switch tube Q ₃ has an anti-parallel diode D ₆ ; _One end of the capacitor C1 and the other end of the capacitor C2 are respectively connected to the _two ends of the load _RL . 2 . The single-phase power factor correction circuit based on the three-tube five-level topology according to claim 1 , wherein the endpoint a, the endpoint c, the endpoint d and the endpoint n form a symmetrical four-port. 3 . 3. The single-phase power factor correction circuit based on three-tube five-level topology according to claim ₁ , characterized in that: the switching tubes Q1, _Q2 , _Q3 are fully controlled devices, using insulated gate type dual IGBT, integrated gate commutated thyristor IGCT, or power field effect transistor MOSFET. 4 . The single-phase power factor correction circuit based on the three-tube five-level topology according to claim 1 , wherein the capacitors C ₁ and C ₂ are series-connected DC bus split capacitors. 5 . 5. The single-phase power factor correction circuit based on the three-tube five-level topology according to any of claims 1 to 4, characterized in that it comprises the following switching modes: Switching mode 1: At this time, it is the positive half cycle of the AC power supply AC, the switch tubes Q ₂ and Q ₃ are turned on, the current passes through the inductor L, the switch tubes Q ₂ , Q ₃ , and finally flows back through the diode D ₂ . In this process, the inductor L is stored. can, the load _RL is powered by the capacitors C ₁ and C ₂ ; Switching mode 2: At this time, it is the positive half cycle of the AC power supply AC, the switch tube Q ₂ is turned on, and the current passes through the inductor L, the diodes D ₃ , D ₁₀ , D ₈ , D ₂ and the capacitor C ₂ . During this process, the AC power supply AC The capacitor C ₂ is charged at the same time as the inductor L, and the load _RL is powered by the capacitor C _1. The switching process of switching mode 1 and switching mode 2 is a boosting process; Switching mode 3: At this time, it is the positive half cycle of the AC power supply, and the current passes through the inductor L, the diodes D ₃ , D ₅ , D ₇ , D ₈ , D ₂ and the capacitor. During this process, the AC power supply AC and the inductor L supply the load at the same time. R _L and capacitors C ₁ and C ₂ supply power, and capacitors C ₁ and C ₂ charge; Switching mode 4: At this time, it is the negative half cycle of the AC power supply AC, the switching tubes Q ₁ and Q ₂ are turned on, the current passes through the diodes D ₁ , D ₄ , the switching tubes Q ₁ , Q ₂ , and finally returns to the AC power supply AC through the inductor L , in this process, the inductor L stores energy, and the load _RL is powered by the capacitors C ₁ and C ₂ ; Switching mode 5: At this time, it is the negative half cycle _of the AC power supply, the switch tube _Q2 is turned _on , and the current passes through the diodes D1, _D8 , D4, _D7 , _D8 , _D9 and the split capacitor _C1 , and finally, the current flows Return to the AC power source AC through the inductor L. During this process, the AC power source AC and the inductor L charge the capacitor C ₁ at the same time. The conversion process from switch mode four to switch mode five is a boosting process; Switching mode 6: At this time, it is the negative half cycle of the AC power supply. The current passes through the diodes D ₁ , D ₄ , D ₇ , D ₈ , D ₆ and the capacitors C ₁ and C ₂ , and returns to the AC power supply AC through the inductor L. This process In the process, the AC power source AC and the inductor L supply power to the load _RL and the capacitors C ₁ and C ₂ at the same time, and the capacitors C ₁ and C ₂ are charged. 6. the single-phase power factor correction circuit based on three-tube five-level topology according to claim 5, is characterized in that, uses diode _D7 , _D8 to carry out following circuit protection: First, two diodes D ₇ and D ₈ are used to ensure the unidirectional flow of power, and to ensure that the currents of the capacitors C ₁ and C ₂ will only flow to the load _RL , and will not cause it to flow backward; Second, when the circuit fails, the capacitors C ₁ and C ₂ can be well protected; Third, in the process of mode switching, it acts as a voltage clamping diode; Fourth, in switching mode 1 and switching mode 4, when the voltage of the inductor L is lower than the DC bus voltage during the energy storage process, it acts as a voltage clamp. 7. The single-phase power factor correction circuit based on the three-tube five-level topology according to any of claims 1 to 4, characterized in that, The PI double closed-loop method is used for control, in which: The outer loop adopts a voltage control loop, which is used for DC side voltage stability control, and the output result is used as the reference given value of the current inner loop; The inner loop adopts a current control loop to achieve unity power factor correction and reduce harmonic content; The PI double closed-loop control realizes the sinusoidal current on the input side, the phase and the power supply voltage are in the same phase, and the DC voltage is stable.

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