CN214900650U - PFC circuit compatible with single-phase and three-phase working modes - Google Patents
PFC circuit compatible with single-phase and three-phase working modes Download PDFInfo
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- CN214900650U CN214900650U CN202120736416.5U CN202120736416U CN214900650U CN 214900650 U CN214900650 U CN 214900650U CN 202120736416 U CN202120736416 U CN 202120736416U CN 214900650 U CN214900650 U CN 214900650U
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Abstract
The utility model provides a compatible single-phase and three-phase mode's PFC circuit, it includes AC power grid side circuit, switching circuit, three-phase bridge type PFC circuit and high voltage direct current side circuit, wherein, AC power grid side circuit includes U phase line, V phase line, W phase line and N line, and U phase line, V phase line and W phase line connect switching circuit's first input, second input and third input respectively, and the high voltage direct current side circuit is connected to the N line; a first contact of a single-pole double-throw relay of the switching circuit is connected with the U-phase line, a second contact of the single-pole double-throw relay is connected with a second input end of the three-phase bridge type PFC circuit, and a fixed contact of the single-pole double-throw relay is connected with a first input end of the three-phase bridge type PFC circuit. The utility model discloses a control to switching circuit can realize the switching of single-phase mode and the three-phase mode of work of PFC circuit, and can save the relay figure, need not to set up parallelly connected diode by the switch tube simultaneously, can reduce the circuit volume and practice thrift the cost.
Description
Technical Field
The utility model relates to a power electronic technology field, in particular to compatible single-phase and three-phase mode's PFC circuit.
Background
The electric energy promotes the rapid development of national economy and the rapid progress of society. The development progress and innovation of the power electronic technology play a significant role in the development of the whole power system, and the power electronic technology is not only beneficial to improving the transmission efficiency of the power system and reducing the energy loss, but also can ensure the power quality of a user side.
While power electronics technology is being developed, it inevitably brings about many problems, such as harmonic pollution and the solution of reactive power problems, which have become urgent. The problems of harmonic pollution and reactive power are most serious with the power electronic rectifying device. Most of the rectifying devices adopt diode uncontrolled rectification and thyristor controlled rectification, and due to the fact that strong nonlinearity exists on the load side of the topological structures, a large amount of harmonic current and reactive power are easily generated on the network side, and the overall performance of the rectifying devices is greatly influenced. As a common rectifying device, an on-board charger has become increasingly serious in terms of harmonic pollution to the power grid and the increase of reactive power of the power grid. Therefore, how to reduce the harmonic content of the input current at the grid side of the vehicle-mounted charger and make the input current at the grid side of the vehicle-mounted charger and the grid voltage have the same phase (power factor correction, PFC) to reduce the reactive power has become an important research content in the field of vehicle-mounted chargers.
When a traditional PFC circuit realizes a Power Factor Correction (PFC) function, in a three-phase working mode, the voltage on the left side of an inductor can have a working mode exceeding the voltage range of a high-voltage direct-current bus, so that the topological circuit cannot increase the energy released by a surge diode to a bus capacitor, and the failure risk of a switching tube in the surge process is high; in addition, in order to suppress the starting inrush current of the PFC circuit and realize the switching between the three-phase operation mode and the single-phase operation mode, five relays are required, which is not favorable for simplifying the circuit and reducing the cost; and under single-phase mode, power frequency switch tube control is very complicated, and the drive is disturbed easily and leads to the switch tube to become invalid when the input voltage distorts very much, consequently is unfavorable for reduce cost at the other parallelly connected diode of power frequency switch tube.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a compatible single-phase and three-phase mode's PFC circuit to realize the switching of the single-phase mode of PFC circuit and three-phase mode, can save the relay figure simultaneously, need not to set up parallelly connected diode by the switch tube, and then reduce the circuit volume and practice thrift the cost.
In order to achieve the above and other related objects, the present invention provides a PFC circuit compatible with single-phase and three-phase operation modes, the PFC circuit including an ac power grid side circuit, a switching circuit provided with a single-pole double-throw relay, a three-phase bridge PFC circuit, and a high-voltage dc side circuit, wherein,
the alternating current network side circuit comprises a U-phase line, a V-phase line, a W-phase line and an N-phase line, the U-phase line is connected with the first input end of the switching circuit, the V-phase line is connected with the second input end of the switching circuit, the W-phase line is connected with the third input end of the switching circuit, and the N-phase line is connected with the high-voltage direct current side circuit;
the three output ends of the switching circuit are respectively connected with the three input ends of the three-phase bridge PFC circuit, a first contact of a single-pole double-throw relay of the switching circuit is connected with the U-phase line, a second contact of the single-pole double-throw relay is connected with a second input end of the three-phase bridge PFC circuit, a fixed contact of the single-pole double-throw relay is connected with the first input end of the three-phase bridge PFC circuit, and switching between a single-phase working mode and a three-phase working mode of the PFC circuit is achieved through control over the switching circuit;
and the output end of the three-phase bridge PFC circuit is connected with the high-voltage direct-current side circuit.
Optionally, in the PFC circuit, the switching circuit is further provided with a first relay, a second relay and a third relay, wherein,
the first end of the first relay is connected with a U-phase line of the alternating current network side circuit, and the second end of the first relay is connected with a first input end of the three-phase bridge type PFC circuit;
the first end of the second relay is connected with a V-phase line of the alternating current network side circuit, and the second end of the second relay is connected with the second input end of the three-phase bridge type PFC circuit;
and the first end of the third relay is connected with the W phase line of the alternating current network side circuit, and the second end of the third relay is connected with the third input end of the three-phase bridge type PFC circuit.
Optionally, in the PFC circuit, the switching circuit is further provided with a thermistor, the thermistor is connected between a first contact of the single-pole double-throw relay and the U-phase line, and is connected in parallel with the first relay, and the thermistor is configured to suppress a start-up inrush current of the PFC circuit.
Optionally, in the PFC circuit, the three-phase bridge PFC circuit includes an inductance circuit and a three-phase full-bridge switching tube circuit, a first input end of the inductance circuit is connected to the fixed contact of the single-pole double-throw relay, a second input end of the inductance circuit is connected to the second contact of the single-pole double-throw relay, a third input end of the inductance circuit is connected to a second end of the third relay, an output end of the inductance circuit is connected to an input end of the three-phase full-bridge switching tube circuit, and an output end of the three-phase full-bridge switching tube circuit is connected to the high-voltage direct-current side circuit.
Optionally, in the PFC circuit, the inductor circuit includes a first inductor, a second inductor, and a third inductor, and a first end of the first inductor, a first end of the second inductor, and a first end of the third inductor are respectively connected to the fixed contact of the single-pole double-throw relay, the second contact of the single-pole double-throw relay, and a second end of the third relay.
Optionally, in the PFC circuit, the three-phase full-bridge switching tube circuit includes a first switching tube to a sixth switching tube, a source of the first switching tube is connected to a drain of the second switching tube, and a second end of the first inductor is connected to a connection line between the source of the first switching tube and the drain of the second switching tube; the source electrode of the third switching tube is connected with the drain electrode of the fourth switching tube, the drain electrode of the third switching tube is connected with the drain electrode of the first switching tube, the source electrode of the fourth switching tube is connected with the source electrode of the second switching tube, and the second end of the second inductor is connected to a connecting line of the source electrode of the third switching tube and the drain electrode of the fourth switching tube; the source electrode of the fifth switching tube is connected with the drain electrode of the sixth switching tube, the drain electrode of the fifth switching tube is connected with the drain electrode of the third switching tube, the source electrode of the sixth switching tube is connected with the source electrode of the fourth switching tube, and the second end of the third inductor is connected with the connecting line of the source electrode of the fifth switching tube and the drain electrode of the sixth switching tube.
Optionally, in the PFC circuit, the high-voltage dc side circuit includes at least two capacitors connected in series, a first end of a first capacitor connected in series is connected to a drain of the fifth switching tube, a second end of a last capacitor connected in series is connected to a source of the sixth switching tube, and an N line of the ac power grid side circuit is connected to a midpoint of a capacitor corresponding to all capacitors connected in series.
Optionally, in the PFC circuit, the high-voltage dc side circuit includes a first capacitor and a second capacitor, wherein a first end of the first capacitor is connected to the drain of the fifth switching tube, and a second end of the first capacitor is connected to a first end of the second capacitor; the second end of the second capacitor is connected with the source electrode of the sixth switching tube, and the N line of the alternating current network side circuit is connected with the capacitor midpoint corresponding to the first capacitor and the second capacitor.
Optionally, in the PFC circuit, the single-pole double-throw relay is connected to the first contact, and when the first relay, the second relay, and the third relay are turned off, the current of the U-phase line charges the first capacitor and the second capacitor.
Optionally, in the PFC circuit, the three-phase bridge PFC circuit further includes a surge circuit, and the surge circuit includes first to sixth surge diodes, wherein an anode of the first surge diode is connected to a cathode of the second surge diode, and a fixed contact of the single-pole double-throw relay is connected to an anode of the first surge diode and then to the first end of the first inductor; the anode of the third surge diode is connected with the cathode of the fourth surge diode, the cathode of the third surge diode is connected with the cathode of the first surge diode, the anode of the fourth surge diode is connected with the anode of the second surge diode, and the second contact of the single-pole double-throw relay is connected with the anode of the third surge diode and then connected with the first end of the second inductor; the positive pole of fifth surge diode with the negative pole of sixth surge diode is connected, the negative pole of fifth surge diode is connected the negative pole of third surge diode, the positive pole of sixth surge diode is connected the positive pole of fourth surge diode, the second end of third switching tube is connected the positive pole of fifth surge diode, reconnection the first end of third inductance, surge circuit is used for absorbing lightning surge current
In the PFC circuit provided by the utility model, the switching between the single-phase working mode and the three-phase working mode of the PFC circuit can be realized by arranging the single-pole double-throw relay in the switching circuit, and the number of the relays can be saved; the high-voltage direct-current side circuit is directly connected through the N line, and a diode connected in parallel is not required to be arranged beside the switch tube, so that the utility model can reduce the circuit volume and save the cost; the thermistor is arranged in the switching circuit, so that the starting impact current of the PFC circuit can be inhibited, and the damage to a power device in the PFC circuit caused by overlarge starting impact current can be avoided; the surge diode is arranged in the three-phase bridge type PFC circuit, so that lightning surge current of the PFC circuit can be absorbed, and damage to the circuit caused by lightning surge is avoided.
Drawings
FIG. 1 is a schematic diagram of a PFC circuit;
fig. 2 is a schematic diagram of a PFC circuit according to an embodiment of the present invention;
fig. 3a is an equivalent circuit diagram of a single-phase rectification mode according to an embodiment of the present invention;
fig. 3b is an equivalent circuit diagram of a single-phase inverter mode according to an embodiment of the present invention;
fig. 4a is an equivalent circuit diagram of a three-phase rectification mode according to an embodiment of the present invention;
fig. 4b is an equivalent circuit diagram of a three-phase inverter mode according to an embodiment of the present invention;
fig. 5a is a circuit diagram illustrating start-up surge suppression of a PFC circuit for a positive half cycle of a U-phase according to an embodiment of the present invention;
fig. 5b is a circuit diagram of the PFC circuit start-up surge suppression according to an embodiment of the present invention.
Detailed Description
The PFC circuit compatible with single-phase and three-phase operation modes according to the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.
Referring to fig. 1, a conventional PFC circuit is shown, in which a circuit can be operated in a single-phase operation mode and a three-phase mode by controlling a switch of a relay, respectively, so as to achieve compatibility of single phase and three phase of the PFC circuit. The PFC circuit comprises an alternating current network side circuit, a switching circuit, a three-phase bridge type PFC circuit and a high-voltage direct current side circuit, wherein the alternating current network side circuit comprises a U-phase line, a V-phase line, a W-phase line and an N line. The switching circuit includes a first relay RL1, a second relay RL2, a third relay RL3, a fourth relay RL4, a fifth relay RL5, and a thermistor R1. The three-phase bridge PFC circuit comprises a first inductor L1, a second inductor L2, a third inductor L3, a first switching tube Q1-a sixth switching tube Q6, a first diode and a second diode. The high-voltage direct-current side circuit comprises a first capacitor C1 and a second capacitor C2.
A first end of the third relay RL3 is connected with the U-phase line, and a second end of the third relay RL3 is connected with the V-phase line; a first end of the second relay RL2 is connected with a first end of the third relay RL3, and a second end of the second relay RL2 is connected with a first end of a first inductor L1; the first relay RL1 and the thermistor R1 are connected in series between a first end of the third relay RL3 and a first end of a first inductor L1; a first end of the fourth relay RL4 is connected with the W-phase line, and a second end of the fourth relay RL4 is connected with a first end of the third inductor L3; a first end of the fifth relay RL5 is connected to the N line, and a second end thereof is connected to the second end of the third inductor L3. The source of the first switch transistor Q1 is connected to the drain of the second switch transistor Q2, and the second end of the first inductor L1 is connected to the connection line between the source of the first switch transistor Q1 and the drain of the second switch transistor Q2; a source electrode of the third switching tube Q3 is connected with a drain electrode of the fourth switching tube Q4, a drain electrode of the third switching tube Q3 is connected with a drain electrode of the first switching tube Q1, a source electrode of the fourth switching tube Q4 is connected with a source electrode of the second switching tube Q2, a second end of the second inductor L2 is connected with a connecting line of a source electrode of the third switching tube Q3 and a drain electrode of the fourth switching tube Q4, and a first end of the second inductor L2 is connected with a second end of the third relay RL 3; a source of the fifth switching tube Q5 is connected to a drain of the sixth switching tube Q6, a drain of the fifth switching tube Q5 is connected to a drain of the third switching tube Q3, a source of the sixth switching tube Q6 is connected to a source of the fourth switching tube Q4, and a second end of the third inductor L3 is connected to a connection line between the source of the fifth switching tube Q5 and the drain of the sixth switching tube Q6. The gates of the first switching tube Q1 to the sixth switching tube Q6 are connected with an external control circuit; the first diode is connected with the fifth switch tube Q5 in parallel, and the second diode is connected with the sixth switch tube Q6 in parallel; the first capacitor C1 and the second capacitor C2 are connected in series between the drain of the fifth switch tube Q5 and the source of the sixth switch tube Q6.
When the first relay RL1, the third relay RL3 and the fifth relay RL5 are switched off and the second relay RL2 and the fourth relay RL4 are switched on, the PFC circuit works in a three-phase working mode, and energy can be transferred from an alternating current power grid side to a high-voltage direct current side (rectification) or from the high-voltage direct current side to a power grid side (inversion) by controlling the duty ratios of the first switching tube Q1 to the sixth switching tube Q6. When the first relay RL1 and the fourth relay RL4 are disconnected and the second relay RL2, the third relay RL3 and the fifth relay RL5 are closed, the circuit works in a single-phase working mode and can be equivalent to a Boost (boosting) circuit connected in parallel in a staggered mode, when the circuit works in a rectification state, currents of the first inductor L1 and the second inductor L2 are staggered by 180 degrees through a corresponding control algorithm, and the harmonic content of the current on the input side of a single-phase power grid can be reduced. Meanwhile, the duty ratio of the first switching tube Q1 to the fourth switching tube Q4 can be controlled, so that the circuit works in an inversion state, and energy is inverted from the high-voltage direct current side to the power grid.
When a conventional PFC circuit realizes a Power Factor Correction (PFC) function, in a three-phase working mode, the left side voltage of a first inductor L1, a second inductor L2 and a third inductor L3 can have a working mode exceeding the voltage range of a high-voltage direct-current bus, so that the topological circuit cannot increase the energy released by surge diodes to bus capacitors, namely a first capacitor C1 and a second capacitor C2, and the first switching tube Q1 to a sixth switching tube Q6 have high failure risk in a surge process; in addition, in order to suppress the starting inrush current of the PFC circuit and realize the switching between the three-phase operation mode and the single-phase operation mode, the PFC circuit needs five relays, which is not beneficial to simplifying the circuit and reducing the cost; in addition, under the single-phase working mode, the power frequency switching tubes (namely the fifth switching tube Q5 and the sixth switching tube Q6) are controlled in a complex mode, and particularly, when the input voltage is distorted, the driving is easy to interfere to cause the failure of the switching tubes, so that diodes are connected in parallel beside the power frequency switching tubes, and the cost is not reduced.
In order to realize the switching of single-phase mode and the three-phase mode of PFC circuit, can restrain simultaneously PFC circuit's start-up impulse current and absorption PFC circuit's thunderbolt surge current, and can save relay figure, need not to set up parallelly connected diode by the switch tube, the utility model provides a novel PFC circuit, compatible single-phase and three-phase mode's PFC circuit promptly.
Referring to fig. 2, the PFC circuit includes an ac power grid side circuit, a switching circuit provided with a single-pole double-throw relay, a three-phase bridge PFC circuit, and a high-voltage dc side circuit.
Alternating current network side circuit includes U phase line, V phase line, W phase line and N line, the U phase line is connected switching circuit's first input, the V phase line is connected switching circuit's second input, the W phase line is connected switching circuit's third input, the N line connection high voltage direct current side circuit.
The three output ends of the switching circuit are respectively connected with the three input ends of the three-phase bridge PFC circuit, and the three output ends of the switching circuit correspond to the three input ends of the switching circuit, namely a first output end corresponds to a first input end, and the first input end and the first output end are on the same branch; the second output end corresponds to the second input end, and the second input end and the second output end are on the same branch; the third output end corresponds to the third input end, and the third input end and the third output end are on the same branch. And three input ends of the three-phase bridge PFC circuit are in one-to-one correspondence with three output ends of the switching circuit.
The switching circuit is provided with a single-pole double-throw relay RL0, the single-pole double-throw relay RL0 having a first contact 1, a second contact 2, and a fixed contact. A first contact 1 of the single-pole double-throw relay RL0 is connected with the U-phase line, and a second contact 2 of the single-pole double-throw relay RL0 is connected with a second input end of the three-phase bridge PFC circuit, that is, the second contact 2 of the single-pole double-throw relay RL0 is connected to a branch where the V-phase line is located. And a fixed contact of the single-pole double-throw relay is connected with a first input end of the three-phase bridge type PFC circuit.
The switching circuit is also provided with a first relay RL1, a second relay RL2, and a third relay RL 3. The first end of the first relay RL1 is connected to the U-phase line of the ac power grid side circuit, the second end of the first relay RL1 is connected to the first input end of the three-phase bridge PFC circuit, and the first relay RL1, in combination with the single-pole double-throw relay RL0, can control the on/off of the branch where the U-phase line is located. The first end of the second relay RL2 is connected with the V-phase line of the ac power grid side circuit, the second end of the second relay RL2 is connected with the second input end of the three-phase bridge PFC circuit, and the second relay RL2, in combination with the single-pole double-throw relay RL0, can control the on/off of the branch where the V-phase line is located. The first end of the third relay RL3 is connected to the W-phase line of the ac power grid side circuit, and the second end thereof is connected to the third input end of the three-phase bridge PFC circuit, so as to control the on-off of the branch where the W-phase line is located.
Due to the single-pole double-throw relay RL0, five relays are not needed in the circuit of the embodiment, the number of relays used is reduced, the cost is reduced, and the size of the circuit is reduced.
When the single-pole double-throw relay RL0 is turned on to position 2 (second contact), the first relay RL1 is closed, and the second relay RL2 and the third relay RL3 are opened, the PFC circuit can work in a single-phase working mode; when the single-pole double-throw relay RL0 is opened or closed and the first relay RL1, the second relay RL2 and the third relay RL3 are closed, the PFC circuit operates in a three-phase operation mode. Therefore, the switching between the single-phase operation mode and the three-phase operation mode of the PFC circuit can be realized through the control of the switching circuit.
The three-phase bridge type PFC circuit comprises an inductance circuit and a three-phase full-bridge switching tube circuit. The inductor circuit comprises a first inductor L1, a second inductor L2 and a third inductor L3. The first end of the first inductor L1 is connected with a fixed contact of the single-pole double-throw relay RL0, the first end of the second inductor L2 is connected with a second contact of the single-pole double-throw relay RL0, and the first end of the third inductor L3 is connected with the second end of the third relay RL 3.
The three-phase full-bridge switching tube circuit comprises a first switching tube Q1-a sixth switching tube Q6, namely a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a fifth switching tube Q5 and a sixth switching tube Q6. The source of the first switch transistor Q1 is connected to the drain of the second switch transistor Q2, and the second end of the first inductor L1 is connected to the connection line between the source of the first switch transistor Q1 and the drain of the second switch transistor Q2; the source of the third switching tube Q3 is connected with the drain of the fourth switching tube Q4, the drain of the third switching tube Q3 is connected with the drain of the first switching tube Q1, the source of the fourth switching tube Q4 is connected with the source of the second switching tube Q2, and the second end of the second inductor L2 is connected to the connecting line between the source of the third switching tube Q3 and the drain of the fourth switching tube Q4; a source of the fifth switching tube Q5 is connected to a drain of the sixth switching tube Q6, a drain of the fifth switching tube Q5 is connected to a drain of the third switching tube Q3, a source of the sixth switching tube Q6 is connected to a source of the fourth switching tube Q4, and a second end of the third inductor L3 is connected to a connection line between the source of the fifth switching tube Q5 and the drain of the sixth switching tube Q6. The gates of the first to sixth switching tubes Q1 to Q6 are connected to an external control circuit.
And the output end of the three-phase bridge PFC circuit is connected with the high-voltage direct-current side circuit. The high-voltage direct-current side circuit comprises at least two capacitors which are connected in series, the first end of the first capacitor which is connected in series is connected with the drain electrode of the fifth switch tube Q5, the second end of the last capacitor which is connected in series is connected with the source electrode of the sixth switch tube Q6, and the N line of the alternating-current side circuit is connected with the middle points of the capacitors which are connected in series and correspond to the capacitors. For example, in fig. 2, the high-voltage dc-side circuit includes a first capacitor C1 and a second capacitor C2, wherein a first end of the first capacitor C1 is connected to the drain of the fifth switch tube Q5, a second end of the first capacitor C2 is connected to the first end of the second capacitor C3838, a second end of the second capacitor C2 is connected to the source of the sixth switch tube Q6, and an N line of the ac power grid-side circuit is connected to a connection line between the second end of the first capacitor C1 and the first end of the second capacitor C2, specifically, the N line of the ac power grid-side circuit is connected to a capacitor midpoint corresponding to the first capacitor C1 and the second capacitor C2.
The first switch tube Q1 to the sixth switch tube Q6 may be a MOSFET (metal-oxide semiconductor field effect transistor) or an IGBT (insulated gate bipolar transistor). The parameters of the power switch tube, the inductor, the relay and the filter capacitor at the high-voltage direct-current side are determined according to the specific requirements of the circuit. The first to sixth switching tubes Q1 to Q6 operate in a Pulse Width Modulation (PWM) mode regardless of whether the PFC circuit is in a single-phase operation mode or a three-phase operation mode.
Fig. 3a and 3b show equivalent circuit diagrams for the single-phase mode of operation. When the PFC circuit works in a single-phase working mode, the single-pole double-throw relay RL0 is turned on to the position 2 (a second contact), the first relay RL1 is closed, the second relay RL2 and the third relay RL3 are opened, and the PFC circuit is a single-phase staggered parallel PFC circuit.
By controlling the first switch tube Q1 to the fourth switch tube Q4, energy can flow from the filter capacitor of the single-phase alternating current network side circuit to the high-voltage direct current side circuit (single-phase rectification mode), and energy can also flow from the filter capacitor of the high-voltage direct current side circuit to the single-phase alternating current network side circuit (single-phase inversion mode). In the single-phase operation mode of the circuit, the first switching tube Q1 to the fourth switching tube Q4 all operate at high frequency, so that the power frequency switching tubes (i.e. the fifth switching tube Q5 and the sixth switching tube Q6) and the parallel diodes thereof are not needed in the present embodiment. Therefore, the cost can be reduced while reducing the volume of the circuit.
Referring to fig. 3a, when the PFC circuit operates in the single-phase rectification operating state, the external control circuit adjusts the first switching tube Q1 to the fourth switching tube Q4 to convert the single-phase grid ac power into the high-voltage dc power. Energy is transferred from the single-phase alternating-current power grid side circuit to the high-voltage direct-current side circuit through the boosting inductor (namely the first inductor L1 and the second inductor L2) and the single-phase full bridge circuit consisting of the first switch tube Q1 to the fourth switch tube Q4. The duty ratios of the first switching tube Q1 to the fourth switching tube Q4 are adjusted through a corresponding control algorithm and an external control circuit, so that the output voltage of the high-voltage direct-current side circuit can be adjusted, and the purpose of input power factor correction can be achieved. The duty ratios of the first switching tube Q1 to the fourth switching tube Q4 are adjusted by a corresponding control algorithm and an external control circuit, so that the harmonic content of the input-side current of the single-phase power grid can be reduced.
Referring to fig. 3b, when the PFC circuit operates in a single-phase inversion operating state, the external control circuit may enable the high-voltage dc side circuit to output a single-phase ac by inversion under different dc input voltage effective values and different output load operating conditions by adjusting duty ratios of the first switching tube Q1 to the fourth switching tube Q4.
Fig. 4a and 4b show equivalent circuit diagrams of the three-phase operating mode. When the PFC circuit works in a three-phase working mode, when the single-pole double-throw relay RL0 is switched off and the first relay RL1, the second relay RL2 and the third relay RL3 are switched on, energy can flow from a three-phase alternating current network side circuit to a high-voltage direct current side circuit (three-phase rectification) or from the high-voltage direct current side circuit to the three-phase alternating current network side circuit (three-phase inversion) by controlling the first switching tube Q1 to the sixth switching tube Q6. Of course, the single-pole double-throw relay RL0 may also be in a closed state, the first relay RL1, the second relay RL2 and the third relay RL3 are closed, and the PFC circuit also operates in a three-phase operating mode, where the single-pole double-throw relay RL0 is short-circuited.
Referring to fig. 4a, when the PFC circuit operates in a three-phase rectification operating state, the external control circuit controls the first switch Q1 to the sixth switch Q6, so as to convert a three-phase ac power into a dc power. By controlling the duty ratios of the first switching tube Q1 to the sixth switching tube Q6, the output voltage of the high-voltage direct current side can be adjusted, and the purpose of input power factor correction can be achieved.
Referring to fig. 4b, when the PFC circuit operates in a three-phase inversion operating state, the external control circuit converts the high-voltage direct current into a three-phase alternating current by adjusting duty ratios of the first switching tube Q1 to the sixth switching tube Q6, and can ensure that the circuit can invert and output the three-phase alternating current under different ac output loads and different dc input voltage effective values.
The utility model discloses in, can also include Surge circuit among the PFC circuit, it is concrete, Surge circuit sets up among the three-phase bridge type PFC circuit, through increase Surge diode (Surge diode) in the three-phase bridge type PFC circuit absorb the thunderbolt Surge current of PFC circuit. The surge circuit comprises a first surge diode D1-a sixth surge diode D6, wherein the anode of the first surge diode D1 is connected with the cathode of the second surge diode D2, and the fixed contact of the single-pole double-throw relay RL0 is connected with the anode of the first surge diode D1 and then connected with the first end of the first inductor L1; an anode of the third surge diode D3 is connected to a cathode of the fourth surge diode D4, a cathode of the third surge diode D3 is connected to a cathode of the first surge diode D1, an anode of the fourth surge diode D4 is connected to an anode of the second surge diode D2, a second contact of the single-pole double-throw relay RL0 is connected to an anode of the third surge diode D3, and further connected to a first end of the second inductor L2; an anode of the fifth surge diode D5 is connected to a cathode of the sixth surge diode D6, a cathode of the fifth surge diode D5 is connected to a cathode of the fifth surge diode D5, an anode of the sixth surge diode D6 is connected to an anode of the fourth surge diode D4, and a second end of the third switching tube Q3 is connected to an anode of the fifth surge diode D5 and to a first end of the third inductor L3.
The PFC circuit can absorb lightning surge current through the first surge diode D1 to the sixth surge diode D6, and damage to the PFC circuit caused by lightning surge is avoided. When the PFC circuit is in forward operation, the first surge diode D1 to the sixth surge diode D6 always bear back voltage and are not turned on, so that no matter the circuit is in a three-phase or single-phase ac power grid, the first surge diode D1 to the sixth surge diode D6 do not shunt current from the first switching tube Q1 to the sixth switching tube Q6, and thermal failure of the surge diodes due to the participation of shunting can be avoided.
Referring to fig. 5a and 5b, the PFC circuit of the present invention may further include a thermistor (PTC) R, specifically, the thermistor R is disposed in the switching circuit. The thermistor is connected between a first contact of the single-pole double-throw relay RL0 and the U-phase line and is connected with the first relay RL1 in parallel, namely the single-pole double-throw relay RL0 is connected with the thermistor R firstly and then connected with the U-phase line. The thermistor is used for inhibiting the starting impact current of the PFC circuit. Fig. 5a shows a schematic diagram of a U-phase positive half cycle PFC start-up surge suppression circuit, and fig. 5b shows a schematic diagram of a U-phase negative half cycle PFC start-up surge suppression circuit.
When the PFC circuit is started, the single-pole double-throw relay RL0 is closed on a first contact 1, the first relay RL1, the second relay RL2 and the third relay RL3 are disconnected, external U-shaped alternating current passes through the thermistor R and the surge diode and then charges the first capacitor C1 and the second capacitor C2 until the first capacitor C1 and the second capacitor C2 reach set values, and then the PFC circuit is enabled to enter a single-phase working mode or a three-phase working mode by controlling the first relay RL1 to the third relay RL3 and the single-pole double-throw relay RL 0.
The thermistor R in the PFC circuit can inhibit the starting impact current of the PFC circuit to realize the soft start of the circuit. No matter the PFC circuit works in a single-phase working mode or a three-phase working mode, the PFC circuit can achieve starting impact current suppression through the U phase. External U alternating current passes through a thermistor R and a surge diode and then charges a PFC filter capacitor (for example, a first capacitor C1 and a second capacitor C2), and the thermistor R limits the instantaneous surge current of the PFC circuit during starting, so that damage to a power device due to overlarge starting surge current can be avoided.
The utility model provides a PFC circuit compatible with single-phase and three-phase input and lightning surge and starting impact current suppression, which can well suppress lightning surge current through a lightning surge diode; the starting impact current of the PFC circuit can be well inhibited through the cooperation of the PTC (thermistor) and the relay; by controlling the first switch tube Q1 to the sixth switch tube Q6, single-phase and three-phase rectification and inversion functions can be realized.
Compared with the prior art, the utility model discloses a surge diode stability is higher, use relay quantity still less, need not power frequency switch tube and parallelly connected diode thereof, and harmonic content is low when single three-phase operation, power factor is high, and the circuit is small, with low costs, has good application prospect.
In addition, it should be noted that the terms "first", "second", and the like in the specification are used for distinguishing various components, elements, steps, and the like in the specification, and are not used for representing a logical relationship or a sequential relationship between the various components, elements, steps, and the like, unless otherwise specified or indicated.
It is to be understood that while the present invention has been disclosed in terms of the preferred embodiment, it is not intended to limit the invention to the disclosed embodiment. To anyone skilled in the art, without departing from the scope of the present invention, the technical solution disclosed above can be used to make many possible variations and modifications to the technical solution of the present invention, or to modify equivalent embodiments with equivalent variations. Therefore, any simple modification, equivalent change and modification made to the above embodiments by the technical entity of the present invention all still fall within the protection scope of the technical solution of the present invention, where the technical entity does not depart from the content of the technical solution of the present invention.
It is to be further understood that the present invention is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses, and applications described herein, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. Thus, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Structures described herein are to be understood as also referring to functional equivalents of such structures. Language that can be construed as approximate should be understood as such unless the context clearly dictates otherwise.
Claims (10)
1. A PFC circuit compatible with single-phase and three-phase working modes is characterized by comprising an alternating current network side circuit, a switching circuit provided with a single-pole double-throw relay, a three-phase bridge PFC circuit and a high-voltage direct current side circuit, wherein,
the alternating current network side circuit comprises a U-phase line, a V-phase line, a W-phase line and an N-phase line, the U-phase line is connected with the first input end of the switching circuit, the V-phase line is connected with the second input end of the switching circuit, the W-phase line is connected with the third input end of the switching circuit, and the N-phase line is connected with the high-voltage direct current side circuit;
the three output ends of the switching circuit are respectively connected with the three input ends of the three-phase bridge PFC circuit, a first contact of a single-pole double-throw relay of the switching circuit is connected with the U-phase line, a second contact of the single-pole double-throw relay is connected with a second input end of the three-phase bridge PFC circuit, a fixed contact of the single-pole double-throw relay is connected with the first input end of the three-phase bridge PFC circuit, and switching between a single-phase working mode and a three-phase working mode of the PFC circuit is achieved through control over the switching circuit;
and the output end of the three-phase bridge PFC circuit is connected with the high-voltage direct-current side circuit.
2. The PFC circuit of claim 1, wherein the switching circuit is further provided with a first relay, a second relay, and a third relay, wherein,
the first end of the first relay is connected with a U-phase line of the alternating current network side circuit, and the second end of the first relay is connected with a first input end of the three-phase bridge type PFC circuit;
the first end of the second relay is connected with a V-phase line of the alternating current network side circuit, and the second end of the second relay is connected with the second input end of the three-phase bridge type PFC circuit;
and the first end of the third relay is connected with the W phase line of the alternating current network side circuit, and the second end of the third relay is connected with the third input end of the three-phase bridge type PFC circuit.
3. The PFC circuit of claim 2, wherein the switching circuit is further provided with a thermistor connected between a first contact of the single-pole double-throw relay and the U-phase line and in parallel with the first relay, the thermistor being configured to suppress a start-up inrush current of the PFC circuit.
4. The PFC circuit of claim 3, wherein the three-phase bridge PFC circuit comprises an inductive circuit and a three-phase full-bridge switching tube circuit, wherein a first input terminal of the inductive circuit is connected to the fixed contact of the single-pole double-throw relay, a second input terminal of the inductive circuit is connected to the second contact of the single-pole double-throw relay, a third input terminal of the inductive circuit is connected to the second terminal of the third relay, an output terminal of the inductive circuit is connected to an input terminal of the three-phase full-bridge switching tube circuit, and an output terminal of the three-phase full-bridge switching tube circuit is connected to the high-voltage DC side circuit.
5. The PFC circuit of claim 4, wherein the inductive circuit comprises a first inductor, a second inductor, and a third inductor, wherein a first terminal of the first inductor, a first terminal of the second inductor, and a first terminal of the third inductor are connected to a fixed contact of the single-pole double-throw relay, a second contact of the single-pole double-throw relay, and a second terminal of the third relay, respectively.
6. The PFC circuit of claim 5, wherein the three-phase full-bridge switching tube circuit comprises a first switching tube to a sixth switching tube, a source electrode of the first switching tube is connected with a drain electrode of the second switching tube, and a second end of the first inductor is connected with a connecting line of the source electrode of the first switching tube and the drain electrode of the second switching tube; the source electrode of the third switching tube is connected with the drain electrode of the fourth switching tube, the drain electrode of the third switching tube is connected with the drain electrode of the first switching tube, the source electrode of the fourth switching tube is connected with the source electrode of the second switching tube, and the second end of the second inductor is connected to a connecting line of the source electrode of the third switching tube and the drain electrode of the fourth switching tube; the source electrode of the fifth switching tube is connected with the drain electrode of the sixth switching tube, the drain electrode of the fifth switching tube is connected with the drain electrode of the third switching tube, the source electrode of the sixth switching tube is connected with the source electrode of the fourth switching tube, and the second end of the third inductor is connected with the connecting line of the source electrode of the fifth switching tube and the drain electrode of the sixth switching tube.
7. The PFC circuit of claim 6, wherein the high-voltage DC side circuit comprises at least two capacitors connected in series, a first end of a first capacitor connected in series is connected with a drain electrode of the fifth switching tube, a second end of a last capacitor connected in series is connected with a source electrode of the sixth switching tube, and N lines of the AC power grid side circuit are connected with middle points of capacitors corresponding to all capacitors connected in series.
8. The PFC circuit of claim 7, wherein the HVDC side circuit comprises a first capacitor and a second capacitor, wherein a first end of the first capacitor is connected to the drain of the fifth switching tube, and a second end of the first capacitor is connected to a first end of the second capacitor; the second end of the second capacitor is connected with the source electrode of the sixth switching tube, and the N line of the alternating current network side circuit is connected with the capacitor midpoint corresponding to the first capacitor and the second capacitor.
9. The PFC circuit of claim 8, wherein the single pole, double throw relay is connected to the first contact and wherein current from the U-phase line charges the first capacitor and the second capacitor when the first relay, the second relay, and the third relay are open.
10. The PFC circuit of claim 5, wherein the three-phase bridge PFC circuit further comprises a surge circuit, and the surge circuit comprises first to sixth surge diodes, wherein an anode of the first surge diode is connected to a cathode of the second surge diode, and a fixed contact of the single-pole double-throw relay is connected to the anode of the first surge diode and then to the first terminal of the first inductor; the anode of the third surge diode is connected with the cathode of the fourth surge diode, the cathode of the third surge diode is connected with the cathode of the first surge diode, the anode of the fourth surge diode is connected with the anode of the second surge diode, and the second contact of the single-pole double-throw relay is connected with the anode of the third surge diode and then connected with the first end of the second inductor; the positive pole of fifth surge diode with the negative pole of sixth surge diode is connected, the negative pole of fifth surge diode is connected the negative pole of third surge diode, the positive pole of sixth surge diode is connected the positive pole of fourth surge diode, the second end of third switching tube is connected the positive pole of fifth surge diode, reconnection the first end of third inductance, surge circuit is used for absorbing the thunderbolt surge current.
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| CN202120736416.5U CN214900650U (en) | 2021-04-12 | 2021-04-12 | PFC circuit compatible with single-phase and three-phase working modes |
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| CN202120736416.5U CN214900650U (en) | 2021-04-12 | 2021-04-12 | PFC circuit compatible with single-phase and three-phase working modes |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114301273A (en) * | 2021-12-23 | 2022-04-08 | 深圳威迈斯新能源股份有限公司 | Slow starting circuit compatible with single-phase two-phase three-phase power and control method |
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- 2021-04-12 CN CN202120736416.5U patent/CN214900650U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114301273A (en) * | 2021-12-23 | 2022-04-08 | 深圳威迈斯新能源股份有限公司 | Slow starting circuit compatible with single-phase two-phase three-phase power and control method |
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