CN118199419A - Three-phase AC-DC converter based on high power factor and high frequency quasi-resonance - Google Patents

Abstract

The present invention belongs to the technical field of AC/DC converters, and discloses a three-phase AC/DC converter based on high power factor and high frequency quasi-resonance, including: a separate three-phase DC voltage input circuit is connected in parallel and then output through a π-type filter circuit, and its output end is connected to the load end; wherein each phase DC input circuit includes: an input filter circuit, which filters the input industrial frequency AC voltage through a first filter capacitor, a common mode inductor, and a second filter capacitor; an industrial frequency AC-high frequency AC cycle inverter, which is used to convert the input industrial frequency AC voltage into a high frequency AC voltage; a high frequency transformer, which is used to boost the high frequency AC voltage; and a high frequency cycle power factor corrector, which is used to convert the boosted high frequency AC voltage into a DC voltage. The three-phase AC/DC converter based on high power factor and high frequency quasi-resonance provided in this embodiment has a circuit topology structure with only two-stage switching circuits, and the DC link is removed in the middle, which can effectively reduce switching losses.

Description

Three-phase AC-DC converter based on high power factor and high frequency quasi-resonance

Technical Field

The invention relates to the technical field of AC/DC converters, and in particular to a three-phase AC/DC converter based on high power factor and high frequency quasi-resonance.

Background technique

All power converters with three-phase AC/DC converter topology and their derivatives, including switching power supplies, have a wide range of applications, such as single crystal furnace power supplies, electrolytic power supplies, charging power supplies, etc.

AC/DC converters generally adopt a two-stage series structure, the front-stage circuit is an AC/DC rectifier structure, the rear-stage circuit is a DC/DC chopper structure, and the output is a DC voltage. The traditional front-stage three-phase input topology adopts a three-phase uncontrolled rectifier circuit. This rectification method has low cost and low power factor, and will generate a large number of harmonics, causing pollution to the power grid. In order to improve the power factor, an active power filter (APF) or a power factor corrector (PFC) is added to the traditional three-phase uncontrolled rectifier circuit to improve the power factor. The disadvantage is that additional devices must be added to each phase. At the same time, due to the limitations of hardware characteristics, when the input side changes greatly or the load side fluctuates violently, resonant voltage and current will be generated, thereby damaging the equipment. Vienna rectifiers have been widely used in AC/DC converters due to their simple topology, small harmonics, small number of power switch tubes, and small voltage stress of switch tubes. The disadvantage is that since more switch tubes are connected in series in each phase circuit, the switching loss of the circuit increases and the rectification conversion efficiency decreases. At the same time, Vienna rectifiers also have a high failure rate. Pulse Width Modulation (PWM) high-frequency rectifier circuits are divided into two categories: voltage and current types. The voltage-type PWM rectifier circuit is currently the most widely used. Through proper control of the PWM rectifier circuit, the input current can be very close to a sine wave and in phase with the input voltage, and the power factor is approximately 1. This rectifier circuit is also called a unity power factor converter or a high power factor rectifier. The three-phase voltage-type PWM high-frequency rectifier circuit consists of six power switch tubes, which can also be regarded as a combination of multiple boost circuits. Therefore, it is a boost rectifier circuit. Its output DC voltage is adjusted from the peak value of the AC power supply voltage to a high level. If it is adjusted to a low level, the input current waveform will be distorted, the power factor will be reduced, and it may even fail to work. Therefore, the withstand voltage of the switch tube is required to be 3 to 4 times higher than the peak value of the three-phase line voltage. The traditional post-stage DC/DC topology structure adopts a flyback inverter, a half-bridge PWM pulse width modulation inverter, a full-bridge PWM pulse width modulation inverter, a half-bridge resonant inverter, a full-bridge resonant inverter, etc. After the inverter passes through a high-frequency transformer, it is converted into a DC voltage through a diode bridge high-frequency rectifier or a switch tube high-frequency synchronous rectifier.

The above topological structures show that the traditional three-phase input AC/DC conversion circuit has to undergo five conversions: AC-DC-AC-high-frequency transformer-AC-DC. The topological structure is complex, the switching loss is very large, it is easy to fail, and it is difficult to meet the actual application requirements.

Summary of the invention

In view of this, an embodiment of the present invention provides a three-phase AC/DC converter based on high power factor and high frequency quasi-resonance to solve the problem that the traditional three-phase input AC/DC conversion circuit in the prior art has a complex topology structure, large switching losses and is prone to failure, which makes it difficult to meet actual application requirements.

The embodiment of the present invention provides a three-phase AC-DC converter based on high power factor and high frequency quasi-resonance, comprising:

The separate three-phase DC voltage input circuits are connected in parallel and then output through a π-type filter circuit, and the output end is connected to the load end;

Wherein, each phase DC input circuit includes:

An input filter circuit filters the input power frequency AC voltage through a first filter capacitor, a common mode inductor and a second filter capacitor;

Industrial frequency AC-high frequency AC cycle inverter, used to convert the input industrial frequency AC voltage into high frequency AC voltage;

High-frequency transformer, used to boost high-frequency AC voltage;

A high frequency cycle power factor corrector is used to convert a stepped-up high frequency AC voltage into a DC voltage.

Optionally, the industrial frequency AC-high frequency AC cycle inverter comprises:

The input end of the first high-frequency switch tube and the input end of the second high-frequency switch tube are connected in parallel to the first output end of the input filter circuit;

The output end of the third high-frequency switch tube is connected to the output end of the second high-frequency switch tube to form a reverse series structure;

The output end of the fourth high-frequency switch tube is connected to the output end of the first high-frequency switch tube to form a reverse series structure;

A first high-frequency capacitor, one end of which is connected to the input end of the fourth high-frequency switch tube, and the other end of the first high-frequency capacitor is connected to the second output end of the input filter circuit;

One end of the second high-frequency capacitor is connected to the input end of the third high-frequency switch tube, and the other end of the second high-frequency capacitor is connected to the second output end of the input filter circuit.

Optionally, the first terminal of the primary coil of the high-frequency transformer is connected between the second high-frequency switch tube and the first high-frequency capacitor; the second terminal of the primary coil of the high-frequency transformer is connected between the fourth high-frequency switch tube and the second high-frequency capacitor.

Optionally, it also includes:

One end of the first high-frequency current transformer is connected between the fourth high-frequency switch tube and the first high-frequency capacitor, and the other end of the first high-frequency current transformer is connected to the first terminal of the primary coil of the high-frequency transformer.

Optionally, the high frequency cycle power factor corrector comprises:

A boost inductor, one end of which is connected to a first terminal of a secondary coil of a high-frequency transformer;

A quasi-resonant capacitor, one end of which is connected to the second terminal of the secondary coil of the high-frequency transformer;

A fifth high-frequency switch tube, an input end of which is connected to the other end of the boost inductor;

A sixth high-frequency switch tube, an input end of which is connected to the other end of the quasi-resonance capacitor;

A first high-frequency diode, an anode of which is connected to the input end of the fifth high-frequency switch tube;

a second high-frequency diode, the anode of which is connected to the input end of the sixth high-frequency switch tube;

The cathode of the first high-frequency diode and the cathode of the second high-frequency diode are connected to the first input end of the π-type filter circuit;

The output end of the fifth high-frequency switch tube and the output end of the sixth high-frequency switch tube are connected to the second input end of the π-type filter circuit.

Optionally, it also includes:

One end of the second high-frequency current transformer is connected to the other end of the quasi-resonant capacitor, and the other end of the second high-frequency current transformer is connected to the input end of the sixth high-frequency switch tube.

Optionally, the π-type filter circuit includes:

A filter inductor, one end of which is connected to the cathode of the first high-frequency diode and the cathode of the second high-frequency diode; one end of the filter inductor is the first input end of the π-type filter circuit;

A first filter capacitor, one end of which is connected to one end of the filter inductor; the other end of the first filter capacitor is connected to the output end of the fifth high-frequency switch tube; the other end of the first filter capacitor is the second input end of the π-type filter circuit;

One end of the second filter capacitor is connected to the other end of the filter inductor; the other end of the second filter capacitor is connected to the other end of the first filter capacitor.

Optionally, the first high-frequency switch tube is composed of an N-channel MOS tube and a parasitic diode; the structures of the second high-frequency switch tube, the third high-frequency switch tube, the fourth high-frequency switch tube, the fifth high-frequency switch tube and the sixth high-frequency switch tube are the same as the first high-frequency switch tube; wherein the gate of the N-channel MOS tube is connected to the DSP chip; the N-channel MOS tube is driven by the DSP chip to control its switching state.

Optionally, it also includes:

A first voltage sensor is arranged between the first phase DC voltage input terminal and the second phase DC voltage input terminal;

A second voltage sensor is arranged between the second phase DC voltage input terminal and the third phase DC voltage input terminal;

The third voltage sensor is arranged between the third-phase DC voltage input terminal and the first-phase DC voltage input terminal.

Optionally, it also includes:

A fourth voltage sensor is arranged at the output end of the π-type filter circuit;

The current sensor is arranged at the output end of the π-type filter circuit.

Beneficial effects of the present invention:

The embodiment of the present invention provides a three-phase AC-DC converter based on high power factor high frequency quasi-resonance, which divides the three phases into three single-phase line voltages. The first stage converts the industrial frequency AC voltage into a high frequency AC voltage through a cyclic inverter, and the second stage converts it into a DC voltage through a high frequency transformer and a high frequency cyclic power factor corrector, and performs power factor correction at the same time. The three independent DC voltages are connected in parallel and output through a π-type filter. The circuit topology has only two switching circuits, and the DC link is removed in the middle, which can effectively reduce the switching loss.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

FIG1 shows a structural diagram of a three-phase AC-DC converter based on high power factor and high frequency quasi-resonance in an embodiment of the present invention;

FIG2 shows a DSP module wiring diagram of a three-phase AC-DC converter based on high power factor and high frequency quasi-resonance in an embodiment of the present invention;

FIG3 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage positive half-wave, a quasi-resonant current positive half-wave, and a boost inductor energy storage in an embodiment of the present invention;

FIG4 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage positive half-wave, a quasi-resonant current positive half-wave, and a boost inductor energy discharge in an embodiment of the present invention;

FIG5 shows a first high-frequency capacitor discharge equivalent circuit diagram in an embodiment of the present invention;

FIG6 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage positive half-wave, a quasi-resonant current negative half-wave, and a boost inductor energy storage in an embodiment of the present invention;

FIG7 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage positive half-wave, a quasi-resonant current negative half-wave, and a boost inductor energy release in an embodiment of the present invention;

FIG8 shows a second high-frequency capacitor discharge equivalent circuit diagram according to an embodiment of the present invention;

FIG9 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage negative half-wave, a quasi-resonant current positive half-wave, and a boost inductor energy storage in an embodiment of the present invention;

FIG10 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage negative half-wave, a quasi-resonant current positive half-wave, and a boost inductor energy discharge in an embodiment of the present invention;

FIG11 shows a second high-frequency capacitor discharge equivalent circuit diagram according to an embodiment of the present invention;

FIG12 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage negative half-wave, a quasi-resonant current negative half-wave, and a boost inductor energy storage in an embodiment of the present invention;

FIG13 shows an equivalent circuit diagram of an AB phase power frequency AC input voltage negative half-wave, a quasi-resonant current negative half-wave, and boost inductor energy release in an embodiment of the present invention;

FIG14 shows a first high-frequency capacitor discharge equivalent circuit diagram in an embodiment of the present invention;

FIG15 shows a three-phase quasi-resonant current sampling circuit diagram in an embodiment of the present invention;

FIG16 shows a three-phase boost inductor current sampling circuit diagram in an embodiment of the present invention;

FIG17 shows a three-phase inverter bridge PWM control circuit diagram according to an embodiment of the present invention;

FIG18 shows a three-phase PFC PWM control circuit diagram in an embodiment of the present invention;

FIG19 shows a main operating waveform diagram of the AB phase main circuit of a three-phase AC/DC converter based on high power factor and high frequency quasi-resonance in an embodiment of the present invention;

Reference numerals:

1110, 2110, 3110: input filter circuit; 1111, 2111, 3111: filter capacitor; 1112, 2112, 3112: common mode inductor; 1113, 2113, 3113: filter capacitor; 1114, 2114, 3114: LV voltage sensor; 1120, 2120, 3120: industrial frequency AC-high frequency AC cycle inverter; 1121, 1122, 1123, 1124, 2121, 212 2. 2123, 2124, 3121, 3122, 3123, 3124: high-frequency switch tube with parasitic diode; 1125, 1126, 2125, 2126, 3125, 3126: high-frequency capacitor; 1130, 2130, 3130: high-frequency transformer module; 1131, 2131, 3131: high-frequency transformer; 1132, 2132, 3132: quasi-resonant capacitor; 1133, 2133, 3133: high-frequency current Transformer; 1140, 2140, 3140: high-frequency cycle power factor corrector; 1141, 1142, 2141, 2142, 3141, 3142: high-frequency switch tube with parasitic diode; 1143, 1144, 2143, 2144, 3143, 3144: high-frequency diode; 1145, 2145, 3145: boost inductor; 150: π-type filter circuit; 151, 153: filter capacitor; 152: filter inductor ; 154: LV voltage sensor; 155: LA current sensor; 410, 420, 430: AC input voltage sampling module; 440, 450, 460: high-frequency inverter current sampling module; 47-, 480, 490: boost inductor current sampling module; 500: output DC voltage sampling module; 510: output DC current sampling module; 520: ADC interface; 1530, 2530, 3530: single-phase line voltage inverter bridge PWM control module ; 1540, 2540, 3540: transformer secondary cycle PFC control module; 550: inverter bridge control PWM output interface; 560: cycle PFC control PWM output interface; 570: inverter bridge drive circuit; 580: PFC drive circuit; 1531, 2531, 3531: pulse oscillator; 1532, 1534, 1535, 2532, 2534, 2535, 3532, 3534, 3535: comparator; 15 33, 2533, 3533: inverter PWM pulse width modulation module; 1536, 2536, 3536: system overvoltage and overcurrent protection; 1537, 2537, 3537: AND gate logic circuit; 441, 442, 451, 452, 461, 462, 471, 472, 481, 482, 491, 492: operational amplifier; R441, R442, R443, R444, R445, Ria1, R451, R452 , R453, R454, R455, Rib1, R461, R462, R463, R464, R465, Ric1, R471, R472, R473, R474, R475, Ria2, R481, R482, R483, R484, R485, Rib2, R491, R492, R493, R494, R495, Ric2: resistor; D441, D442, D451, D452 , D461, D462, D471, D472, D481, D482, D491, D492: diodes; 1541, 2541, 3541: output voltage regulator; 1542, 2542, 3542: multiplier; 1543, 2543, 3543: boost inductor current regulator; 1544, 1545, 2544, 2545, 3544, 3545: comparator; 1546, 2546, 3546: PFC PWM pulse width modulator.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

The embodiment of the present invention provides a three-phase AC-DC converter based on high power factor and high frequency quasi-resonance, comprising:

The separate three-phase DC voltage input circuits are connected in parallel and then output through a π-type filter circuit, and the output end thereof is connected to the load end.

Wherein, each phase DC input circuit comprises: an input filter circuit, which filters the input power frequency AC voltage through a first filter capacitor, a common mode inductor and a second filter capacitor.

The industrial frequency AC-high frequency AC cycle inverter is used to convert the input industrial frequency AC voltage into a high frequency AC voltage.

High-frequency transformer, used to boost high-frequency AC voltage.

A high frequency cycle power factor corrector is used to convert a stepped-up high frequency AC voltage into a DC voltage.

As shown in FIG1 , in this embodiment, three single-phase line voltage inputs are included:

The AB phase includes an input filter circuit 1110 , an industrial frequency AC-high frequency AC cycle inverter 1120 , a high frequency transformation module 1130 and a high frequency cycle power factor corrector 1140 .

The BC phase includes an input filter circuit 2110 , an industrial frequency AC-high frequency AC cycle inverter 2120 , a high frequency transformation module 2130 and a high frequency cycle power factor corrector 2140 .

The CA phase includes an input filter circuit 3110 , an industrial frequency AC-high frequency AC cycle inverter 3120 , a high frequency transformation module 3130 and a high frequency cycle power factor corrector 3140 .

As shown in FIG2 , the voltage and current at each position of the three-phase AC/DC converter are collected through the AC input AB phase line voltage sampling circuit 410, the BC phase line voltage sampling circuit 420, the CA phase line voltage sampling circuit 430, the AB phase high-frequency inverter current sampling circuit 440, the BC phase high-frequency inverter current sampling circuit 450, the CA phase high-frequency inverter current sampling circuit 460, the AB phase boost inductor current sampling circuit 470, the BC phase boost inductor current sampling circuit 480, the CA phase boost inductor current sampling circuit 490, the output DC voltage sampling circuit 500, and the output DC current sampling circuit 510, and the analog signal is converted into a digital signal through the ADC interface 520 of the DSP processor.

The on/off frequency of each high-frequency switch tube in the DSP processor control circuit is controlled. The DSP processor includes three single-phase line voltage inverter bridge PWM controls 1530, 2530, and 3530, and three transformer secondary cycle PFC controls 1540, 2540, and 3540. The PWM output interface 560, the inverter bridge drive circuit 570, and the PFC drive circuit 580 are connected to the gate of each high-frequency switch tube through the cycle PFC control.

This embodiment proposes a three-phase AC-DC converter based on high power factor high frequency quasi-resonance, which divides the three phases into three single-phase line voltages. The first stage converts the industrial frequency AC voltage into a high frequency AC voltage through a cyclic inverter, and the second stage converts it into a DC voltage through a high frequency transformer and a high frequency cyclic power factor corrector, and performs power factor correction at the same time. The three independent DC voltages are connected in parallel and output through a π-type filter. The circuit topology has only two switching circuits, and the DC link is removed in the middle, which can effectively reduce the switching loss.

As shown in Figure 1, the three inputs of the three-phase DC voltage are u _A , u _B and u _C. The input circuit of the first-phase DC voltage u _A is used as an example for explanation:

The input filter circuit 1110 includes a first filter capacitor 1111, a common mode inductor 1112, and a second filter capacitor 1113. The first filter capacitor 1111 is connected in parallel to the input end of the common mode inductor 1112, and the second filter capacitor 1113 is connected in parallel to the output end of the common mode inductor 1112. The first phase DC voltage ua _is input through both ends of the first filter capacitor 1111 and output through both ends of the second filter capacitor 1113.

The structure of the industrial frequency AC-high frequency AC cycle inverter 1120 is:

The input end of the first high-frequency switch tube 1121 and the input end of the second high-frequency switch tube 1122 are connected in parallel to the first output end of the input filter circuit 1110;

The output end of the third high-frequency switch tube 1123 is connected to the output end of the second high-frequency switch tube 1122 to form a reverse series structure;

The output end of the fourth high-frequency switch tube 1124 is connected to the output end of the first high-frequency switch tube 1121 to form a reverse series structure;

A first high-frequency capacitor 1125, one end of which is connected to the input end of the fourth high-frequency switch tube 1124, and the other end of the first high-frequency capacitor 1125 is connected to the second output end of the input filter circuit 1110;

One end of the second high-frequency capacitor 1126 is connected to the input end of the third high-frequency switch tube 1123 , and the other end of the second high-frequency capacitor 1126 is connected to the second output end of the input filter circuit 1110 .

The first terminal of the primary coil of the high-frequency transformer 1131 is connected between the second high-frequency switch tube 1122 and the first high-frequency capacitor 1125 ; the second terminal of the primary coil of the high-frequency transformer 1131 is connected between the fourth high-frequency switch tube 1124 and the second high-frequency capacitor 1126 .

One end of the first high-frequency current transformer 1133 is connected between the fourth high-frequency switch tube 1124 and the first high-frequency capacitor 1125 , and the other end of the first high-frequency current transformer 1133 is connected to the first terminal of the primary coil of the high-frequency transformer 1131 .

The structure of the high frequency cycle power factor corrector 1140 includes:

A boost inductor 1145, one end of which is connected to a first terminal of a secondary coil of the high-frequency transformer 1131;

A quasi-resonant capacitor 1132, one end of which is connected to the second terminal of the secondary coil of the high-frequency transformer 1131;

A fifth high-frequency switch tube 1141, whose input end is connected to the other end of the boost inductor 1145;

A sixth high-frequency switch tube 1142, an input end of which is connected to the other end of the quasi-resonance capacitor 1132;

A first high-frequency diode 1143, an anode of which is connected to the input end of the fifth high-frequency switch tube;

A second high-frequency diode 1144, whose anode is connected to the input end of the sixth high-frequency switch tube;

The cathode of the first high-frequency diode 1143 and the cathode of the second high-frequency diode 1144 are connected to the first input terminal of the π-type filter circuit 150;

An output end of the fifth high-frequency switch tube 1141 and an output end of the sixth high-frequency switch tube 1142 are connected to a second input end of the π-type filter circuit 150 .

The high frequency cycle power factor corrector 1140 converts the AB phase input current i _ab into a sinusoidal current, and the peak envelope of the boost inductor current i _{ab 3} is a power frequency sinusoidal wave.

One end of the second high-frequency current transformer 1146 is connected to the other end of the quasi-resonant capacitor 1132 , and the other end of the second high-frequency current transformer 1146 is connected to the input end of the sixth high-frequency switch tube 1142 .

The π-type filter circuit 150 includes:

A filter inductor 152, one end of which is connected to the cathode of the first high-frequency diode 1143 and the cathode of the second high-frequency diode 1144; one end of the filter inductor 152 is the first input end of the π-type filter circuit;

The first filter capacitor 151 has one end connected to one end of the filter inductor 152; the other end of the first filter capacitor 151 is connected to the output end of the fifth high-frequency switch tube 1141; the other end of the first filter capacitor 151 is the second input end of the π-type filter circuit;

One end of the second filter capacitor 153 is connected to the other end of the filter inductor 152 ; the other end of the second filter capacitor 153 is connected to the other end of the first filter capacitor 151 .

As an optional implementation, the first high-frequency switch tube is composed of an N-channel MOS tube and a parasitic diode; the structures of the second high-frequency switch tube, the third high-frequency switch tube, the fourth high-frequency switch tube, the fifth high-frequency switch tube and the sixth high-frequency switch tube are the same as the first high-frequency switch tube; wherein the gate of the N-channel MOS tube is connected to the DSP chip; the N-channel MOS tube is driven by the DSP chip to control its switching state.

The parasitic diode is connected in parallel to the source and drain of the N-channel MOS tube, the anode of the parasitic diode is connected to the source of the N-channel MOS tube, and the cathode of the parasitic diode is connected to the drain of the N-channel MOS tube. Due to the need to realize the function of the switch tube, when the N-channel MOS tube is in the off state, the drain is used as the input end and the source is used as the output end, the N-channel MOS tube is not turned on, and the direction of the parasitic diode is from the negative pole to the positive pole, and it is not turned on.

Taking the AB phase as an example, the working principle of the PWM control of the three-phase AC-DC converter based on high power factor and high frequency quasi-resonance provided in this embodiment is described as follows:

1. The AB phase line voltage is a positive half-wave, and the quasi-resonant current is a positive half-wave. The equivalent circuit is shown in Figures 3 and 4:

The pulse oscillator 1531 of the AB phase inverter bridge PWM control 1530 outputs a pulse Fp, the inverter PWM control 1533 outputs a PWM pulse Pf1, the AB phase sampling voltage u _abi is positive, the comparator 1534 outputs Up is positive, the comparator 1535 outputs Un is zero, and when the system works normally, the overvoltage and overcurrent protection is open, the start signal RUN is in the start state, Runb is high level, Q1121 outputs a high level, and through the inverter bridge drive circuit 570, the first high-frequency switch tube 1121 is driven to turn on.

2. The first high-frequency capacitor 1125 is discharged, and the equivalent circuit is shown in FIG5 :

When the current i _{ab 2} drops to the minimum setting value, the sampled current I _{a 1-} is compared with the setting value I _a1s , and the setting value I _a1s determines that the voltage on the first high-frequency capacitor 1125 is discharged to zero when the first high-frequency switch tube 1121 is turned off. The comparator 1532 outputs a low level, the inverter PWMM control 1533 outputs a PWM pulse Pf1 outputs a low level, and Q1121 outputs a low level, and the inverter bridge drive circuit 570 drives the first high-frequency switch tube 1121 to turn off. At this time, the first high-frequency capacitor 1125 discharges to zero.

3. The B-phase line voltage is a positive half-wave, and the quasi-resonant current is a negative half-wave. The equivalent circuit diagrams are shown in Figures 6 and 7:

When the current i _{ab 3} drops to zero, the sampling current I _{a2 -} is zero, the comparator 1544 outputs P _sy zero level, the control pulse oscillator 1531 outputs zero level, the inverter PWMM control 1533 outputs PWM pulse Pf2, Q1122 outputs a high level, and drives the second high-frequency switch tube 1122 to turn on through the inverter bridge drive circuit 570.

4. The second high-frequency capacitor 1126 is discharged, and the equivalent circuit is shown in FIG8 :

When the current i _{ab 2} drops to the minimum setting value, the sampled current I _a1- is compared with the setting value I _a1s , and the setting value I _a1s determines that the voltage on the second high-frequency capacitor 1126 is discharged to zero when the second high-frequency switch tube 1122 is turned off. The comparator 1532 outputs a low level, the inverter PWM control 1533 outputs a PWM pulse Pf2 outputs a low level, and Q1122 outputs a low level, and the second high-frequency switch tube 1122 is driven to turn off through the inverter bridge drive circuit 570. At this time, the second high-frequency capacitor 1126 is discharged to zero.

5. The AB phase line voltage is a negative half-wave, and the quasi-resonant current is a positive half-wave. The equivalent circuit is shown in Figures 9 and 10:

When the AB phase line voltage is a negative half-wave, the AB phase sampling voltage u _abi is negative, the comparator 1534 outputs Un is positive, the comparator 1535 outputs Up is zero, Q1123 outputs a high level, and drives the third high-frequency switch tube 1123 to turn on through the inverter bridge drive circuit 570.

6. The second high-frequency capacitor 1126 is discharged, and the equivalent circuit is shown in FIG11 :

When the current i _{ab 2} drops to the minimum setting value, the sampled current I _{a1 -} is compared with the setting value I _a1s , and the setting value I _a1s determines that when the third high-frequency switch tube 1123 is turned off, the voltage on the second high-frequency capacitor 1126 is discharged to zero. The comparator 1532 outputs a low level, the inverter PWMM control 1533 outputs a PWM pulse Pf1 outputs a low level, and Q1123 outputs a low level, and the third switch tube 1123 is driven to turn off through the inverter bridge drive circuit 570. At this time, the second high-frequency capacitor 1126 is discharged to zero.

7. The AB phase line voltage is a negative half-wave, and the quasi-resonant current is a negative half-wave. The equivalent circuit is shown in Figures 12 and 13:

When the current i _{ab 3} drops to zero, the sampling current I _{a 2-} is zero, the comparator 1544 outputs P _sy zero level, the control pulse oscillator 1531 outputs zero level, the inverter PWM control 1533 outputs PWM pulse Pf2, Q1124 outputs a high level, and drives the fourth high-frequency switch tube 1124 to turn on through the inverter bridge drive circuit 570.

8. The first high-frequency capacitor 1125 is discharged, and the equivalent circuit is shown in FIG14 :

When the current i _{ab 2} drops to the minimum setting value, the sampled current I _{a1 -} is compared with the setting value I _a1s , and the setting value I _a1s determines that the voltage on the first high-frequency capacitor 1125 is discharged to zero when the fourth high-frequency switch tube 1124 is turned off. The comparator 1532 outputs a low level, the inverter PWM control 1533 outputs a PWM pulse Pf2 outputs a low level, and Q1124 outputs a low level. Through the inverter bridge drive circuit 570, the fourth high-frequency switch tube 1124 is driven to turn off. At this time, the first high-frequency capacitor 1125 is discharged to zero.

Taking the AB phase as an example, the working principle of the PFC control of the three-phase AC-DC converter based on high power factor and high frequency quasi-resonance provided by this embodiment is described as follows:

1. AB phase boost inductor energy storage:

The pulse oscillator 1531 of the AB phase inverter bridge PWM control 1530 outputs a pulse Fp to control the PFC PWM pulse width modulator 1546. Q1141 and Q1142 output a high level, and output a driving pulse through the PFC driving circuit 580 to drive the fifth high-frequency switch tube 1141 and the sixth high-frequency switch tube 1142 to be turned on at the same time. The sampled output voltage U _oc of the AB phase PFC PWM pulse width modulator 1540 is subtracted from the given value U ^* _oc , and the error value is subjected to PI operation through the output voltage regulator 1541, and its output is sent to the multiplier 1542. At the same time, the multiplier 1542 receives the AB phase line voltage sampling value u _abi and the inverter current sampling value I _{a1 -} , and the three values are multiplied and output as the dynamic setting value of the boost inductor current, and its value is subtracted from the boost inductor sampling current I _{a2 -} . The error value is subjected to PI operation through the boost inductor current regulator 1543 to control the pulse width of the PFC PWM pulse width modulator 1546.

2. AB phase boost inductor discharge:

When the boost inductor current i _{ab 3} reaches the peak value of the dynamic setting value of the boost inductor current output by the multiplier, the dynamic setting value drops instantly, the output of the boost inductor current regulator 1543 drops rapidly, the output pulse of the PFC PWM pulse width modulator 1546 quickly becomes zero, Q1141 and Q1142 output zero level, and the PFC drive circuit 580 outputs a low level to drive the fifth high-frequency switch tube 1141 and the sixth high-frequency switch tube 1142 to be turned off at the same time; when the current i _{ab 3} drops to zero, the sampling current I _{a2 -} is zero, the comparator 1544 outputs P _sy zero level, and the control pulse oscillator 1531 outputs zero level.

As an optional implementation, it also includes:

A first voltage sensor 1114 is provided between a first-phase DC voltage input terminal and a second-phase DC voltage input terminal;

A second voltage sensor 2114 is provided between the second phase DC voltage input terminal and the third phase DC voltage input terminal;

The third voltage sensor 3114 is arranged between the third-phase DC voltage input terminal and the first-phase DC voltage input terminal.

As an optional implementation, it also includes:

A fourth voltage sensor 154 is provided at the output end of the π-type filter circuit;

The current sensor 155 is arranged at the output end of the π-type filter circuit.

As shown in Fig. 2, the voltage collected by the AC input AB phase line voltage sampling circuit 410 corresponds to the sampling voltage of the first voltage sensor 1114; the voltage collected by the BC phase line voltage sampling circuit 420 corresponds to the sampling voltage of the second voltage sensor 2114; and the voltage collected by the CA phase line voltage sampling circuit 430 corresponds to the sampling voltage of the third voltage sensor 3114. In a specific embodiment, the voltage sampling circuit is composed of a Hall voltage sensor.

The AB phase high frequency inverter current sampling circuit 440 collects the current flowing through the first high frequency current transformer 1133 ; the BC phase high frequency inverter current sampling circuit 450 collects the current flowing through the high frequency current transformer 2133 ; and the CA phase high frequency inverter current sampling circuit 460 collects the current flowing through the high frequency current transformer 3133 .

The AB phase boost inductor current sampling circuit 470 collects the current flowing through the second high-frequency current transformer 1146 ; the BC phase boost inductor current sampling circuit 480 collects the current flowing through the high-frequency current transformer 2148 ; and the CA phase boost inductor current sampling circuit 490 collects the current flowing through the high-frequency current transformer 3148 .

The voltage sampled by the output DC voltage sampling circuit 500 corresponds to the sampled voltage of the fourth voltage sensor 154 .

The current collected by the output DC current sampling circuit 510 corresponds to the current collected by the current sensor 155 .

As shown in FIG. 15 and FIG. 16 , the current sampling circuit is a precision rectifier circuit based on an operational amplifier, which converts the AC sampling current into a DC sampling voltage.

In a specific embodiment, the three-phase inverter bridge PWM control circuit is shown in FIG. 17 , and the three-phase PFC PWM control is shown in FIG. 18 .

As shown in FIG19 , the main working waveforms of the AB phase of the three-phase AC/DC converter based on high power factor high frequency quasi-resonance are listed, where u _ab is the input AC voltage waveform, i _ab1 is the unfiltered AC input power frequency current with high frequency components, i _ab is the filtered AC input power frequency current, G1121, G1122, G1123, G1124 are the gate drives of the high frequency switches 1121, 1122, 1123, 1124 of the power frequency AC-high frequency AC cycle inverter 1120, u _a1b1 is the high frequency square wave voltage output by the quasi-resonant converter, and the amplitude envelope is the power frequency sine wave, i _ab2 is the resonant current of the power frequency AC-high frequency AC cycle inverter, and the amplitude envelope is the power frequency sine wave, u _c1d1 is the secondary voltage of the high frequency transformer 1131, G1141, G1142 are the gate drive pulses of the high frequency switches 1141, 1142, u _e1d1 is the input voltage of the high frequency cycle power factor corrector 1140, i _ab3 is the current of the boost inductor 1145, the amplitude envelope is a power frequency sine wave, and Uo is the output DC voltage.

As described above, the present invention provides a three-phase AC-DC converter based on high power factor high frequency quasi-resonance, which divides three phases into three single-phase line voltages, converts the industrial frequency AC voltage into high frequency AC voltage through a cyclic inverter in the first stage, and converts it into DC voltage through a high frequency transformer and a high frequency cyclic power factor corrector in the second stage, and performs power factor correction at the same time, and the three independent DC voltages are connected in parallel and output through π-type filtering. The circuit topology has only two switching circuits, and the DC link is removed in the middle, which can effectively reduce the switching loss.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims (10)

1. A three-phase AC-DC converter based on high power factor and high frequency quasi-resonance, characterized in that it comprises: The separate three-phase DC voltage input circuits are connected in parallel and then output through a π-type filter circuit, and the output end is connected to the load end; Wherein, each phase DC input circuit includes: An input filter circuit filters the input power frequency AC voltage through a first filter capacitor, a common mode inductor and a second filter capacitor; A power frequency AC-high frequency AC cycle inverter, used for converting the input power frequency AC voltage into a high frequency AC voltage; A high-frequency transformer, used for stepping up the high-frequency AC voltage; The high-frequency cycle power factor corrector is used to convert the high-frequency AC voltage that has been boosted into a DC voltage. 2. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 1, characterized in that the industrial frequency AC-high frequency AC cycle inverter comprises: The input end of the first high-frequency switch tube and the input end of the second high-frequency switch tube are connected in parallel to the first output end of the input filter circuit; The output end of the third high-frequency switch tube is connected to the output end of the second high-frequency switch tube to form a reverse series structure; The output end of the fourth high-frequency switch tube is connected to the output end of the first high-frequency switch tube to form a reverse series structure; a first high-frequency capacitor, one end of which is connected to the input end of the fourth high-frequency switch tube, and the other end of which is connected to the second output end of the input filter circuit; A second high-frequency capacitor has one end connected to the input end of the third high-frequency switch tube, and the other end of the second high-frequency capacitor is connected to the second output end of the input filter circuit. 3. According to claim 2, the three-phase AC-DC converter based on high power factor high frequency quasi-resonance is characterized in that the first terminal of the primary coil of the high-frequency transformer is connected between the second high-frequency switch tube and the first high-frequency capacitor; the second terminal of the primary coil of the high-frequency transformer is connected between the fourth high-frequency switch tube and the second high-frequency capacitor. 4. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 3, characterized in that it also includes: A first high-frequency current transformer has one end connected between the fourth high-frequency switch tube and the first high-frequency capacitor, and the other end of the first high-frequency current transformer is connected to the first terminal of the primary coil of the high-frequency transformer. 5. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 4, characterized in that the high frequency cycle power factor corrector comprises: A boost inductor, one end of which is connected to the first terminal of the secondary coil of the high-frequency transformer; A quasi-resonant capacitor, one end of which is connected to the second terminal of the secondary coil of the high-frequency transformer; a fifth high-frequency switch tube, whose input end is connected to the other end of the boost inductor; a sixth high-frequency switch tube, whose input end is connected to the other end of the quasi-resonant capacitor; a first high-frequency diode, the anode of which is connected to the input end of the fifth high-frequency switch tube; a second high-frequency diode, the anode of which is connected to the input end of the sixth high-frequency switch tube; The cathode of the first high-frequency diode and the cathode of the second high-frequency diode are connected to the first input end of the π-type filter circuit; The output end of the fifth high-frequency switch tube and the output end of the sixth high-frequency switch tube are connected to the second input end of the π-type filter circuit. 6. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 5, characterized in that it also includes: A second high-frequency current transformer has one end connected to the other end of the quasi-resonant capacitor, and the other end of the second high-frequency current transformer is connected to the input end of the sixth high-frequency switch tube. 7. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 5, characterized in that the π-type filter circuit comprises: A filter inductor, one end of which is connected to the cathode of the first high-frequency diode and the cathode of the second high-frequency diode; one end of the filter inductor is the first input end of the π-type filter circuit; A first filter capacitor, one end of which is connected to one end of the filter inductor; the other end of the first filter capacitor is connected to the output end of the fifth high-frequency switch tube; the other end of the first filter capacitor is the second input end of the π-type filter circuit; A second filter capacitor, one end of which is connected to the other end of the filter inductor; and the other end of the second filter capacitor is connected to the other end of the first filter capacitor. 8. According to the three-phase AC-DC converter based on high power factor high frequency quasi-resonance as described in claim 5, it is characterized in that the first high frequency switch tube is composed of an N-channel MOS tube and a parasitic diode; the structure of the second high frequency switch tube, the third high frequency switch tube, the fourth high frequency switch tube, the fifth high frequency switch tube and the sixth high frequency switch tube is the same as that of the first high frequency switch tube; wherein the gate of the N-channel MOS tube is connected to the DSP chip; the N-channel MOS tube is driven by the DSP chip to control its switching state. 9. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 1, characterized in that it also includes: A first voltage sensor is arranged between the first phase DC voltage input terminal and the second phase DC voltage input terminal; A second voltage sensor is arranged between the second-phase DC voltage input terminal and the third-phase DC voltage input terminal; The third voltage sensor is arranged between the third-phase DC voltage input terminal and the first-phase DC voltage input terminal. 10. The three-phase AC-DC converter based on high power factor and high frequency quasi-resonance according to claim 1, characterized in that it also includes: A fourth voltage sensor is arranged at the output end of the π-type filter circuit; The current sensor is arranged at the output end of the π-type filter circuit.