CN210327379U - Single-phase electric input circuit based on three-phase Vienna PFC topology - Google Patents

Abstract

The utility model provides a single-phase electricity input circuit and control method based on PFC topology is received in three-phase vienna, through adjusting the duty cycle of a unsettled corresponding switch pipe in the PFC topology is received in the three-phase vienna, the reverse recovery problem of low frequency device in the suppression bidirectional switch, the reverse recovery loss of low frequency device in the PFC topology bidirectional switch is received in the three-phase vienna has been reduced, the heating of PFC topology is received in the three-phase vienna has been reduced, reliable operation when single-phase electricity or direct current input of PFC topology is received in the three-phase vienna has been provided solution.

Description

Single-phase electric input circuit based on three-phase Vienna PFC topology

Technical Field

The utility model belongs to the technical field of power control, concretely relates to single-phase electricity input circuit based on PFC topology is received in three-phase vienna.

Background

With the rapid development of the automobile industry in the field of new energy, people have higher and higher requirements on reliable operation of AC \ DC power conversion equipment in each charging scene, and a pfc (power Factor correction), i.e., a power Factor correction measure, needs to be adopted to improve the conversion efficiency of the power conversion equipment and reduce conduction loss; at present, a VIENNA (VIENNA) rectifier, namely a three-phase three-level three-switch PFC rectifier, is adopted. The vienna rectifier has the advantages that: the required power tube devices are few, the voltage stress is only half of the direct current bus voltage, the problem of direct connection of bridge arm output voltage is solved, the driving dead time is not required to be set, and the control circuit is simple.

In some application environments, the AC \ DC power conversion equipment needs to meet the requirements of single-phase power or direct-current input charging in addition to the requirement of normal operation when three-phase power is input. Referring to fig. 2, the bidirectional switch of the vienna PFC topology is composed of a bridge rectifier or a fast recovery diode and a switching tube, wherein the bridge rectifier or the fast recovery diode belongs to a low-frequency device, and the switching tube belongs to a high-frequency device. When three-phase electricity is input, two diodes of each bridge stack are directly connected with the inductor to work in a power frequency state, and the other two diodes are connected with the midpoint of the bus and work in a high-frequency state along with the action of the switching tube. Because the two diodes working in the high-frequency state are both turned off at zero voltage, and the current can naturally zero when the diodes are turned off, the thermal stress problem caused by the reverse recovery of the high-frequency turn-off current does not exist in all the diodes of the bridge stack when the three-phase power is input.

Referring to fig. 3, when single-phase power or direct current is input to the vienna PFC topology, the circuit is equivalent to an equivalent circuit model in which the single-phase power is input between a first input branch connected in series with the first inductor and a second input branch connected in series with the second inductor, and a third input branch connected in series with the third inductor is suspended. In order to ensure that the input voltage works normally, a first switching tube and a second switching tube in the rectifier bridge stacks of the first input branch and the second input branch are switched at a certain duty ratio, and a third switching tube in the rectifier bridge stacks of the third input branch is normally kept in an off state.

However, in practical applications, it is found that the switching state of the third switching tube has a very significant influence on the thermal stress of the bridge stack of the third input branch: if the third switch tube keeps the off state all the time, the equivalent junction capacitance of the third switch tube forms two resonant circuits in the circuit along with the switching actions of the first switch tube and the second switch tube: when the front end voltage of the first inductor is greater than that of the second inductor, one resonant loop is an equivalent junction capacitor, a fourteenth diode, a third inductor and a second equivalent capacitor which are sequentially connected with the first switch tube, the fifteenth diode and the third switch tube from the first inductor and returns to the first inductor; the other resonant loop is formed by sequentially passing the third inductor to a thirteenth diode, an equivalent junction capacitor of a third switching tube, a sixteenth diode, a second switching tube, a second inductor, a third equivalent capacitor and returning to the third inductor. When the front end voltage of the first inductor is smaller than that of the second inductor, one resonant loop is an equivalent junction capacitor, a fourteenth diode, a third inductor and a third equivalent capacitor which are sequentially connected with the second inductor to the second switching tube, the fifteenth diode and the third switching tube from the second inductor, and returns to the second inductor; the other resonant loop is formed by sequentially passing the third inductor to a thirteenth diode, an equivalent junction capacitor of a third switching tube, a sixteenth diode, a first switching tube, a first inductor, a second equivalent capacitor and returning to the third inductor.

Referring to fig. 4, since the equivalent junction capacitance of the third switch tube is pF stage and the third inductance is uF stage, the generated resonance frequency is several hundred kHz; the potential at the two ends of the third switching tube is changed violently, the voltage of the rectifier bridge stack connected in parallel with the equivalent junction capacitor of the third switching tube generates high-frequency oscillation, and a strong and stable clamping position cannot be formed on the rectifier bridge stack; the current of the rectifier bridge stack connected with the third inductor in series generates high-frequency oscillation of hundreds of kHz; the high-frequency oscillating voltage and current generate a reverse recovery problem on the rectifier bridge stack, so that dynamic loss of diodes forming the rectifier bridge stack is caused, the diodes are seriously heated, and the problem becomes a heat dissipation bottleneck of power supply conversion equipment.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is: the single-phase power input circuit and the control method based on the three-phase Vienna PFC topology are provided, when single-phase power or direct current is input, the reverse recovery loss of a low-frequency device in a two-way switch of the three-phase Vienna PFC topology is reduced, the heat generation of the three-phase Vienna PFC topology is reduced, and the working reliability of power conversion equipment is improved.

The utility model discloses a solve the technical scheme who above-mentioned technical problem took and be: the single-phase power input circuit based on the three-phase Vienna PFC topology comprises an input unit, a three-phase Vienna PFC unit and a control unit; the input unit is used for accessing an alternating current power supply of a power grid; the three-phase vienna PFC unit includes a first inductor (L1), a second inductor (L2), a third inductor (L3), a first switching tube (S1), a second switching tube (S2), a third switching tube (S3), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), a fifth diode (D5), a sixth diode (D6), a seventh diode (D7), an eighth diode (D8), a ninth diode (D9), a twelfth diode (D10), an eleventh diode (D11), a twelfth diode (D12), a thirteenth diode (D13), a fourteenth diode (D13), a fifteenth diode (D13), a sixteenth diode (D13), a seventeenth diode (D13), an eighteenth diode (D13), a first bus (C13), a second capacitor (C13), a first inductor (L13), a first bus (L13), a second inductor (L13), a second bus (L13), and a third diode (D2) The front ends of a second inductor (L2) and a third inductor (L3) are respectively connected to the phase A, the phase B and the phase C of the three-phase alternating current power supply output end of the input unit to form a first input branch, a second input branch and a third input branch, the rear end of the first inductor (L1) is connected with the anode of a first diode (D1) and the cathode of a second diode (D2), the rear end of the second inductor (L2) is connected with the anode of a seventh diode (D7) and the cathode of an eighth diode (D8), the rear end of the third inductor (L3) is connected with the anode of a thirteenth diode (D13) and the cathode of a fourteenth diode (D14), the cathode of a first diode (D1) and the cathode of a third diode (D3) are connected with the anode of a fifth diode (D5), the cathode of the seventh diode (D7) and the cathode of a ninth diode (D9) are connected with the anode of an eleventh diode (D11), a cathode of the thirteenth diode (D13), a cathode of the fifteenth diode (D15) and an anode of the seventeenth diode (D17) are connected, a cathode of the fifth diode (D5) and a cathode of the eleventh diode (D11) and a cathode of the seventeenth diode (D17) are connected to form a common cathode structure and are connected to a positive terminal of the first bus capacitor (C1), an anode of the second diode (D2) and an anode of the fourth diode (D4) are connected to a cathode of the sixth diode (D6), an anode of the eighth diode (D8) and an anode of the twelfth diode (D10) are connected to a cathode of the twelfth diode (D12), an anode of the fourteenth diode (D14) and an anode of the sixteenth diode (D16) are connected to a cathode of the eighteenth diode (D18), and an anode of the sixth diode (D6) and an anode of the twelfth diode (D12) and an anode of the eighteenth diode (D18) are connected to form a common cathode structure, and is connected to the negative terminal of the second bus capacitor (C2), the anode of the third diode (D3), the cathode of the fourth diode (D4), the anode of the ninth diode (D9), the cathode of the twelfth diode (D10), an anode of a fifteenth diode (D15), a cathode of a sixteenth diode (D16), a negative terminal of a first bus capacitor (C1), and a positive terminal of a second bus capacitor (C2) are connected to a point O of the midpoint of the ac power source, a source and a drain of the first switching tube (S1) are connected to an anode of the fifth diode (D5) and a cathode of the sixth diode (D6), respectively, a source and a drain of the second switching tube (S2) are connected to an anode of the eleventh diode (D11) and a cathode of the twelfth diode (D12), respectively, and a source and a drain of the third switching tube (S3) are connected to an anode of the seventeenth diode (D17) and a cathode of the eighteenth diode (D18), respectively; three signal output ends of the control unit are respectively connected with the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3) and used for respectively loading PWM pulse signals to the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3).

The control unit may be a DSP or ARM control unit, for example a control unit based on a DSP of the TMS320F2803X model TI.

According to the scheme, the temperature sensor unit comprises at least three temperature sensors which are respectively clung to the circuits of the first input branch, the second input branch and the third input branch, and the signal output ends of the three temperature sensors are respectively connected to the three signal input ends of the control unit and are used for detecting the circuit temperatures of the first input branch, the second input branch and the third input branch and uploading data to the control unit.

According to the scheme, a first resistor (R1) is further connected in series between a connecting point of an anode of the first diode (D1) and a cathode of the second diode (D2) and the rear end of the first inductor (L1), a second resistor (R2) is further connected in series between a connecting point of an anode of the seventh diode (D7) and a cathode of the eighth diode (D8) and the rear end of the second inductor (L2), and a third resistor (R3) is further connected in series between a connecting point of an anode of the thirteenth diode (D13) and a cathode of the fourteenth diode (D14) and the rear end of the third inductor (L3) and used for limiting the input current.

According to the scheme, the input unit outputs a single-phase voltage Vac to the three-phase Vienna PFC unit between the A phase and the B phase, when the C phase is suspended, in an equivalent circuit of the three-phase Vienna PFC unit, a connection point of a negative end of a first bus capacitor (C1) and a positive end of a second bus capacitor (C2) is an O1 point, and the front end of a third inductor (L3) is an O2 point; a first equivalent junction capacitor (Cs1) of a first switching tube (S1) of the three-phase Vienna PFC unit is connected between the source electrode and the drain electrode of the first switching tube (S1) in parallel, a second equivalent junction capacitor (Cs2) of a second switching tube (S2) is connected between the source electrode and the drain electrode of the second switching tube (S2) in parallel, and a third equivalent junction capacitor (Cs3) of a third switching tube (S3) is connected between the source electrode and the drain electrode of the third switching tube (S3) in parallel; a first equivalent capacitor (X1) is connected in parallel between the front end of the first inductor (L1) and the front end of the second inductor (L2), a second equivalent capacitor (X2) is connected in parallel between the front end of the first inductor (L1) and the front end of the third inductor (L3), and a third equivalent capacitor (X3) is connected in parallel between the front end of the second inductor (L2) and the front end of the third inductor (L3).

The single-phase electric input control method based on the three-phase Vienna PFC topology comprises the following steps:

step S1: the input unit outputs single-phase electric voltage Vac to the three-phase Vienna PFC unit between the A phase and the B phase, the C phase is suspended, and the three-phase Vienna PFC unit is equivalent to an equivalent circuit for inputting single-phase electricity;

step S2: the control unit sends PWM pulse signals to the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3), controls the first switching tube (S1) and the second switching tube (S2) to be switched on and off at a certain duty ratio, and controls the third switching tube (S3) to be switched on at a duty ratio larger than 0% for meeting the temperature control requirement of the circuit.

Further, in step S1, the three-phase vienna PFC unit is equivalent to an equivalent circuit inputting single-phase power, and the specific steps include:

step S11: setting the connection point of the negative end of the first bus capacitor (C1) and the positive end of the second bus capacitor (C2) as a point O1, and setting the front end of the third inductor (L3) as a point O2;

step S12: a first equivalent capacitor (X1) is connected in parallel between the front end of the first inductor (L1) and the front end of the second inductor (L2), a second equivalent capacitor (X2) is connected in parallel between the front end of the first inductor (L1) and the front end of the third inductor (L3), a third equivalent capacitor (X3) is connected in parallel between the front end of the second inductor (L2) and the front end of the third inductor (L3), in the first input branch, the rear end of the first inductor (L1) is connected with the anode of a fifth diode (D5), in the second input branch, the rear end of the second inductor (L2) is connected with the cathode of a twelfth diode (D12), in the third input branch, the rear end of the third inductor (L3) is connected with the anode of the thirteenth diode (D13), the cathode of the fourteenth diode (D14), the cathode of the thirteenth diode (D13), the cathode of the fifteenth diode (D15) is connected with the anode of the seventeenth diode (D17), an anode of a fourteenth diode (D14), an anode of a sixteenth diode (D16) and a cathode of an eighteenth diode (D18), a cathode of a fifth diode (D5) and a cathode of a seventeenth diode (D17) are connected with a positive terminal of the first bus capacitor (C1), an anode of a twelfth diode (D12) and an anode of an eighteenth diode (D18) are connected with a negative terminal of the second bus capacitor (C2), an anode of a fifteenth diode (D15) and a cathode of the sixteenth diode (D16) are connected at a point O1, a source and a drain of the first switching tube (S1) and the first equivalent junction capacitor (Cs1) are connected in parallel between the anode of the fifth diode (D5) and a point O1, a source and a drain of the second switching tube (S2) and the second equivalent junction capacitor (Cs2) are connected in parallel between the cathode of the twelfth diode (D12) and a point O24, a source and a drain of the third diode (S5928) are connected in parallel with the anode of the seventeenth diode (D599) and the anode of the seventeenth diode (D599) Three signal output ends of the control unit are respectively connected with the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3) among the cathodes of the eighteen diodes (D18).

Further, in step S2, the control unit controls the third switching tube (S3) to conduct at a duty ratio greater than 0% for meeting the temperature control requirement of the circuit, and the specific steps are as follows:

step S21: the control unit receives the signal sent by the temperature sensor unit and analyzes the signal into the temperature T3 of the third input branch circuit;

step S22: setting the operating temperature to be T0, and controlling a third switching tube (S3) to be disconnected if the control unit judges that T3 is not more than T0; if T3 > T0, the third switch tube (S3) is controlled to be conducted.

Further, in step S22, the T0 is set to 25 ℃ of ambient temperature or 80 ℃ of maximum circuit temperature.

The utility model has the advantages that:

the utility model discloses a PFC topology and control method are received in three-phase vienna of adjustable duty cycle, through adjusting the duty cycle of a unsettled corresponding switch tube in the PFC topology in the three-phase vienna, the reverse recovery problem of low frequency device in the suppression bidirectional switch has reduced the reverse recovery loss of low frequency device in the PFC topology bidirectional switch is received in the three-phase vienna, the heating of PFC topology is received in the three-phase vienna has been reduced, reliable operation when single-phase electricity or direct current input for the PFC topology is received in the three-phase vienna has provided the solution.

Drawings

Fig. 1 is a functional block diagram of an embodiment of the present invention.

Fig. 2 is a circuit diagram of a three-phase vienna PFC unit according to an embodiment of the present invention.

Fig. 3 is an equivalent circuit diagram of the single-phase power input by the three-phase vienna PFC unit according to the embodiment of the present invention.

Fig. 4 is a simulated waveform diagram of the third input branch current and the voltage of the equivalent junction capacitor Cs3 of the third switching tube S3 according to the background of the invention.

Fig. 5 is an equivalent circuit diagram of the three-phase vienna PFC unit according to the embodiment of the present invention when single-phase power is input and the third switching tube S3 is turned on.

Wherein: l1. a first inductor; l2, a second inductor; l3, a third inductor; s1, a first switch tube; s2, a second switching tube; s3, a third switching tube; D1. a first diode; D2. a second diode; D3. a third diode; D4. a fourth diode; D5. a fifth diode; D6. a sixth diode; D7. a seventh diode; D8. an eighth diode; D9. a ninth diode; D10. a twelfth pole tube; D11. an eleventh diode; D12. a twelfth diode; D13. a thirteenth diode; D14. a fourteenth diode; D15. a fifteenth diode; D16. a sixteenth diode; D17. a seventeenth diode; D18. an eighteenth diode; C1. a first bus capacitor; C2. a second bus capacitor; r1, a first resistor; r2, a second resistor; r3. a third resistor; cs1. first equivalent junction capacitance; cs2. a second equivalent junction capacitance; cs3. third equivalent junction capacitance; x1. a first equivalent capacitance; x2. second equivalent capacitance; x3. third equivalent capacitance.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 and 2, the present invention provides a single-phase electrical input circuit based on a three-phase vienna PFC topology, including an input unit, a three-phase vienna PFC unit, and a control unit; the input unit is used for accessing an alternating current power supply of a power grid; the three-phase vienna PFC unit includes a first inductor L1, a second inductor L2, a third inductor L3, a first switch tube S1, a second switch tube S2, a third switch tube S3, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a ninth diode D9, a twelfth diode D10, an eleventh diode D11, a twelfth diode D12, a thirteenth diode D13, a fourteenth diode D14, a fifteenth diode D15, a sixteenth diode D16, a seventeenth diode D17, an eighteenth diode D18, a first bus capacitor C1 and a second bus capacitor C2, wherein front ends of the first inductor L1, the second inductor L2 and the third inductor L3 are respectively connected to an ac input end of the three-phase input unit, a phase input end of the three-phase input branch, a phase input end of the three-phase input unit, a phase input end B branch and a branch of the three-phase input unit, A third input branch, a rear end of the first inductor L1 is connected to an anode of the first diode D1 and a cathode of the second diode D2, a rear end of the second inductor L2 is connected to an anode of the seventh diode D7 and a cathode of the eighth diode D8, a rear end of the third inductor L3 is connected to an anode of the thirteenth diode D13 and a cathode of the fourteenth diode D14, a cathode of the first diode D1 and a cathode of the third diode D3 are connected to an anode of the fifth diode D5, a cathode of the seventh diode D7 and a cathode of the ninth diode D9 are connected to an anode of the eleventh diode D11, a cathode of the thirteenth diode D13 and a cathode of the fifteenth diode D15 are connected to an anode of the seventeenth diode D17, a cathode 573 of the fifth diode D5 is connected to a cathode of the eleventh diode D5 and a cathode of the seventeenth diode D17 to form a common cathode structure, and is connected to a bus bar 1 of the first positive capacitor C24, an anode of the second diode D2 and an anode of the fourth diode D4 are connected to a cathode of the sixth diode D6, an anode of the eighth diode D8 and an anode of the twelfth diode D10 are connected to a cathode of the twelfth diode D12, an anode of the fourteenth diode D14 and an anode of the sixteenth diode D16 are connected to a cathode of the eighteenth diode D18, an anode of the sixth diode D6 is connected to an anode of the twelfth diode D12 and an anode of the eighteenth diode D18 to form a common anode structure and is connected to a negative terminal of the second bus capacitor C2, an anode of the third diode D3, a cathode of the fourth diode D4, an anode of the ninth diode D9, a cathode of the twelfth diode D10, an anode of the fifteenth diode D15, a cathode of the sixteenth diode D16, a negative terminal of the first bus capacitor C1 and a positive terminal O of the second capacitor C2 are connected to a midpoint O of the ac power source/drain switch S56 and a cathode of the sixth diode D828653, a source and a drain of the second switching tube S2 are respectively connected to an anode of the eleventh diode D11 and a cathode of the twelfth diode D12, and a source and a drain of the third switching tube S3 are respectively connected to an anode of the seventeenth diode D17 and a cathode of the eighteenth diode D18; three signal output ends of the control unit are respectively connected with the gates of the first switch tube S1, the second switch tube S2 and the third switch tube S3, and are used for respectively loading the PWM pulse signals to the gates of the first switch tube S1, the second switch tube S2 and the third switch tube S3.

The temperature sensor unit comprises three temperature sensors which are respectively and tightly fixed on the rectifier bridge stack circuits of the first input branch, the second input branch and the third input branch, and the signal output ends of the three temperature sensors are respectively connected to the three signal input ends of the control unit and used for detecting the temperatures of the rectifier bridge stack circuits of the first input branch, the second input branch and the third input branch and uploading the data to the control unit.

A first resistor R1 is further connected in series between a connection point of an anode of the first diode D1 and a cathode of the second diode D2 and the rear end of the first inductor L1, a second resistor R2 is further connected in series between a connection point of an anode of the seventh diode D7 and a cathode of the eighth diode D8 and the rear end of the second inductor L2, and a third resistor R3 is further connected in series between a connection point of an anode of the thirteenth diode D13 and a cathode of the fourteenth diode D14 and the rear end of the third inductor L3 and is used for limiting an input current.

Referring to fig. 3, when the input unit outputs a single-phase voltage Vac to the three-phase vienna PFC unit between the a phase and the B phase, and when the C phase is suspended, in an equivalent circuit of the three-phase vienna PFC unit, a connection point between a negative terminal of the first bus capacitor C1 and a positive terminal of the second bus capacitor C2 is an O1 point, and a front end of the third inductor L3 is an O2 point; a first equivalent junction capacitor Cs1 of a first switch tube S1 of the three-phase vienna PFC unit is connected in parallel between the source and the drain of the first switch tube S1, a second equivalent junction capacitor Cs2 of a second switch tube S2 is connected in parallel between the source and the drain of the second switch tube S2, and a third equivalent junction capacitor Cs3 of a third switch tube S3 is connected in parallel between the source and the drain of the third switch tube S3; a first equivalent capacitor X1 is connected in parallel between the front end of the first inductor L1 and the front end of the second inductor L2, a second equivalent capacitor X2 is connected in parallel between the front end of the first inductor L1 and the front end of the third inductor L3, and a third equivalent capacitor X3 is connected in parallel between the front end of the second inductor L2 and the front end of the third inductor L3.

The single-phase electric input control method based on the three-phase Vienna PFC topology comprises the following steps:

step S1: the input unit outputs single-phase electric voltage Vac to the three-phase Vienna PFC unit between the A phase and the B phase, the C phase is suspended, and the three-phase Vienna PFC unit is equivalent to an equivalent circuit for inputting single-phase electricity;

step S11: setting the connection point of the negative end of the first bus capacitor C1 and the positive end of the second bus capacitor C2 as a point O1, and the front end of the third inductor L3 as a point O2;

step S12: a first equivalent capacitor X1 is connected in parallel between the front end of the first inductor L1 and the front end of the second inductor L2, a second equivalent capacitor X2 is connected in parallel between the front end of the first inductor L1 and the front end of the third inductor L3, a third equivalent capacitor X3 is connected in parallel between the front end of the second inductor L2 and the front end of the third inductor L3, in the first input branch, the rear end of the first inductor L1 is connected with the anode of a fifth diode D5, in the second input branch, the rear end of the second inductor L2 is connected with the cathode of a twelfth diode D6327, in the third input branch, the rear end of the third inductor L3 is connected with the anode of a thirteenth diode D13 and the cathode of a fourteenth diode D14, in the thirteenth input branch, the cathode of a thirteenth diode D13 and the cathode of a fifteenth diode D15 are connected with the anode of a seventeenth diode D17, the anode of a fourteenth diode D5 and the anode of a sixteenth diode D18D 57324 are connected with the cathode of an eighteenth diode 58573 diode D57324, a cathode of the fifth diode D5 and a cathode of the seventeenth diode D17 are connected to a positive terminal of the first bus capacitor C1, an anode of the twelfth diode D12 and an anode of the eighteenth diode D18 are connected to a negative terminal of the second bus capacitor C2, an anode of the fifteenth diode D15 and a cathode of the sixteenth diode D16 are connected to a point O1, a source and a drain of the first switching tube S1 and the first equivalent junction capacitor Cs1 are connected in parallel between an anode of the fifth diode D5 and a point O1, a source and a drain of the second switching tube S2 and the second equivalent junction capacitor Cs2 are connected in parallel between a cathode of the twelfth diode D12 and a point O1, a source and a drain of the third switching tube S3 and the third equivalent junction capacitor Cs3 are connected in parallel between an anode of the seventeenth diode D17 and a cathode of the eighteenth diode D18, three signal output terminals of the control unit are respectively connected to the first switching tube S1, the gates of the second switching tube S2 and the third switching tube S3 are connected;

step S2: the control unit sends PWM pulse signals to the gates of the first switch tube S1, the second switch tube S2 and the third switch tube S3, controls the first switch tube S1 and the second switch tube S2 to be switched on and off at a certain duty ratio, and controls the third switch tube S3 to be switched on at a duty ratio larger than 0% for meeting the temperature control requirement of the circuit;

step S21: the control unit receives the signal sent by the temperature sensor unit and analyzes the signal into the temperature T3 of the third input branch circuit;

step S22: setting the operating temperature to be T0, and controlling the third switching tube S3 to be switched off when the control unit judges that T3 is not more than T0; if T3 > T0, controlling the third switch tube S3 to be conducted; t0 is set at 25 deg.C or 80 deg.C.

Referring to fig. 5, an equivalent circuit diagram of the three-phase vienna PFC unit according to an embodiment of the present invention when a single-phase power is input to the PFC unit and the third switching tube S3 is turned on is shown, where Vac is an input dc voltage or a single-phase power frequency input voltage equivalent to the dc voltage, if the switching tube S3 is turned on at a 100% duty ratio, potentials of the source and the drain of the third switching tube S3 are always equal and strongly clamped by a bus voltage in the vicinity of a half bus voltage, and points (including a point O1, a point O2, and a point of the source and a point of the drain of the third switching tube S3) directly connected to the rectifier bridge stack are clamped by the bus voltage. Through actual measurement, the temperature of the rectifier bridge stack can be remarkably reduced by controlling the third switching tube S3 to be conducted according to the duty ratio larger than 0%; setting the duty cycle to 100% achieves the optimum effect when the case temperature of the rectifier bridge stack has been reduced to a level close to the ambient temperature, and is no longer the thermal bottleneck of the entire power conversion device.

If the duty ratio of the switching tube S3 is not 100%, when S3 is in the off state, the duration of the reverse recovery problem is related to the duty ratio, and in practical applications, the duty ratio of the switching tube S3 is adjusted according to the heat generation condition and the heat dissipation requirement of the device. For example, due to the fact that Vienna PFC topology generates heat seriously, the temperature exceeds the highest temperature of the circuit by 80 ℃, and the duty ratio of the switching tube S3 is adjusted to be close to 100% when the heat dissipation effect of equipment is poor; the heat dissipation effect of the equipment is good, and when the temperature is close to the ambient temperature of 25 ℃, the duty ratio of the switching tube S3 is properly adjusted to be low.

To sum up, the utility model discloses a single-phase electricity input circuit and control method based on PFC topology are received in three-phase vienna through adjusting the duty cycle of a unsettled corresponding switch tube in the PFC topology in the three-phase vienna, restrain the reverse recovery problem of low frequency device in the bidirectional switch, reduced the reverse recovery loss of low frequency device in the PFC topology bidirectional switch is received in the three-phase vienna, reduced the three-phase vienna PFC topology generate heat, reliably operated when single-phase electricity or direct current input for the three-phase vienna PFC topology provides the solution.

The above embodiments are only used for illustrating the design ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all the equivalent changes or modifications made according to the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims (4)

1. Single-phase electric input circuit based on three-phase vienna PFC topology, characterized in that: the power supply comprises an input unit, a three-phase Vienna PFC unit and a control unit;

the input unit is used for accessing an alternating current power supply of a power grid;

the three-phase Vienna PFC unit comprises a first inductor (L1), a second inductor (L2), a third inductor (L3), a first switching tube (S1), a second switching tube (S2), a third switching tube (S3), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), a fifth diode (D5), a sixth diode (D6), a seventh diode (D7), an eighth diode (D8), a ninth diode (D9), a twelfth diode (D10), an eleventh diode (D11), a twelfth diode (D12), a thirteenth diode (D13), a fourteenth diode (D14), a fifteenth diode (D15), a sixteenth diode (D16), a seventeenth diode (D17), an eighteenth diode (D18), a first bus bar (C1) and a second bus bar 2,

the front ends of the first inductor (L1), the second inductor (L2) and the third inductor (L3) are respectively connected to the A phase, the B phase and the C phase of the three-phase alternating current power output end of the input unit to form a first input branch, a second input branch and a third input branch,

the rear end of the first inductor (L1) is connected with the anode of the first diode (D1) and the cathode of the second diode (D2),

the rear end of the second inductor (L2) is connected with the anode of the seventh diode (D7) and the cathode of the eighth diode (D8),

the rear end of the third inductor (L3) is connected with the anode of the thirteenth diode (D13) and the cathode of the fourteenth diode (D14),

the cathode of the first diode (D1) and the cathode of the third diode (D3) are connected with the anode of the fifth diode (D5),

the cathode of the seventh diode (D7), the cathode of the ninth diode (D9) and the anode of the eleventh diode (D11) are connected,

a cathode of the thirteenth diode (D13), a cathode of the fifteenth diode (D15) and an anode of the seventeenth diode (D17),

the cathode of the fifth diode (D5) is connected with the cathode of the eleventh diode (D11) and the cathode of the seventeenth diode (D17) to form a common cathode structure and is connected with the positive terminal of the first bus capacitor (C1),

the anode of the second diode (D2), the anode of the fourth diode (D4) and the cathode of the sixth diode (D6) are connected,

the anode of the eighth diode (D8) and the anode of the twelfth diode (D10) are connected with the cathode of the twelfth diode (D12),

the anode of the fourteenth diode (D14) and the anode of the sixteenth diode (D16) are connected to the cathode of the eighteenth diode (D18),

the anode of the sixth diode (D6), the anode of the twelfth diode (D12) and the anode of the eighteenth diode (D18) are connected to form a common anode structure and are connected to the negative end of the second bus capacitor (C2),

an anode of the third diode (D3), a cathode of the fourth diode (D4), an anode of the ninth diode (D9), a cathode of the twelfth diode (D10), an anode of the fifteenth diode (D15), a cathode of the sixteenth diode (D16), a negative terminal of the first bus capacitor (C1) and a positive terminal of the second bus capacitor (C2) are connected to the midpoint O of the alternating current power supply,

the source and the drain of the first switching tube (S1) are respectively connected with the anode of the fifth diode (D5) and the cathode of the sixth diode (D6),

the source and the drain of the second switching tube (S2) are respectively connected with the anode of the eleventh diode (D11) and the cathode of the twelfth diode (D12),

the source and the drain of the third switching tube (S3) are connected with the anode of the seventeenth diode (D17) and the cathode of the eighteenth diode (D18), respectively;

the control unit is a DSP or ARM control unit, three signal output ends of the control unit are respectively connected with the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3) and used for respectively loading PWM pulse signals to the grids of the first switching tube (S1), the second switching tube (S2) and the third switching tube (S3).

2. The single-phase electrical input circuit based on a three-phase vienna PFC topology of claim 1, wherein: the temperature sensor unit comprises at least three temperature sensors which are respectively clung to the circuits of the first input branch, the second input branch and the third input branch, and the signal output ends of the three temperature sensors are respectively connected to the three signal input ends of the control unit and used for detecting the circuit temperatures of the first input branch, the second input branch and the third input branch and uploading data to the control unit.

3. The single-phase electrical input circuit based on a three-phase vienna PFC topology of claim 1, wherein: a first resistor (R1) is further connected in series between a connection point of an anode of the first diode (D1) and a cathode of the second diode (D2) and the rear end of the first inductor (L1), a second resistor (R2) is further connected in series between a connection point of an anode of the seventh diode (D7) and a cathode of the eighth diode (D8) and the rear end of the second inductor (L2), and a third resistor (R3) is further connected in series between a connection point of an anode of the thirteenth diode (D13) and a cathode of the fourteenth diode (D14) and the rear end of the third inductor (L3) and is used for limiting an input current.

4. The single-phase electrical input circuit based on a three-phase vienna PFC topology of claim 1, wherein: when the input unit outputs a single-phase voltage Vac to the three-phase Vienna PFC unit between an A phase and a B phase and the C phase is suspended, in an equivalent circuit of the three-phase Vienna PFC unit, a connection point of a negative end of a first bus capacitor (C1) and a positive end of a second bus capacitor (C2) is an O1 point, and the front end of a third inductor (L3) is an O2 point; a first equivalent junction capacitor (Cs1) of a first switching tube (S1) of the three-phase Vienna PFC unit is connected between the source electrode and the drain electrode of the first switching tube (S1) in parallel, a second equivalent junction capacitor (Cs2) of a second switching tube (S2) is connected between the source electrode and the drain electrode of the second switching tube (S2) in parallel, and a third equivalent junction capacitor (Cs3) of a third switching tube (S3) is connected between the source electrode and the drain electrode of the third switching tube (S3) in parallel; a first equivalent capacitor (X1) is connected in parallel between the front end of the first inductor (L1) and the front end of the second inductor (L2), a second equivalent capacitor (X2) is connected in parallel between the front end of the first inductor (L1) and the front end of the third inductor (L3), and a third equivalent capacitor (X3) is connected in parallel between the front end of the second inductor (L2) and the front end of the third inductor (L3).

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