Three-phase active PFC circuit, circuit board, controller and air conditioner

Abstract

Disclosed in the present application are a three-phase active PFC circuit, a circuit board, a controller and an air conditioner. The three-phase active PFC circuit comprises an input filter module (100), a bidirectional switch module (200), a three-phase rectification module (300), an output filter module (400) and a clamping module (500). The input filter module (100) comprises three input filter inductors and three input filter capacitors; the bidirectional switch module (200) comprises three bidirectional controllable switches; one end of each of the three bidirectional controllable switches is connected to a connection point of one of the three input filter inductors and one of the three input filter capacitors, while the other ends of the three bidirectional controllable switches are respectively connected to alternating current input ends of the three-phase rectification module (300). A first clamping midpoint in the clamping module (500) is connected to an input filter neutral point in the input filter module (100) or a neutral point of a three-phase alternating current power supply.

Description

Three-phase active PFC circuit, circuit board, controller and air conditioner

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202410386131.1, filed on April 1, 2024, entitled “Three-phase active PFC circuit, circuit board, controller and air conditioner”. The entire contents of the above patent application are incorporated into this application by reference. Technical Field

[0003] The present application relates to the technical field of air-conditioning circuits, and in particular to a three-phase active PFC circuit, a circuit board, a controller, and an air conditioner. Background Art

[0004] Active PFC circuits include boost active PFC and buck active PFC. Common three-phase boost active PFC circuits increase the DC voltage on the load side, requiring high-voltage power devices on the load side, increasing costs. Furthermore, higher clearances are required for traces to meet safety regulations, increasing product size. Furthermore, high losses in high-voltage devices reduce system efficiency.

[0005] Using a three-phase buck active PFC circuit can reduce the DC voltage on the load side, thus avoiding the aforementioned problems. However, the three legs of the controlled rectifier bridge in a commonly used three-phase buck active PFC circuit each include an upper and lower switching transistor, resulting in a total of six independently controlled controllable switches. This, in turn, requires six independent drive circuits, making driving difficult and costly. Furthermore, when all six switches are turned off during power factor correction, they are connected in series, two by two, between the line voltages. Therefore, one switch must withstand the highest line voltage, necessitating the use of a switch with a higher voltage rating. Summary of the Invention

[0006] The purpose of the present application is to at least partially solve one of the technical problems existing in the prior art, and to this end provide a three-phase active PFC circuit, a circuit board, a controller and an air conditioner.

[0007] In a first aspect, an embodiment of the present application provides a three-phase active PFC circuit, comprising an input filter module, a bidirectional switch module, a three-phase rectifier module, an output filter module, and a clamp module. The input filter module comprises three input filter inductors and three input filter capacitors; one end of each of the three input filter inductors is connected to a three-phase AC power supply, and the other end is connected to one end of each of the three input filter capacitors; the other ends of the three input filter capacitors are connected together to form an input filter neutral point; the bidirectional switch module comprises three bidirectional controllable switches, one end of each of the three bidirectional controllable switches is connected to the connection point between the three input filter inductors and the three input filter capacitors; the other ends of the three bidirectional controllable switches are connected to the AC input end of the three-phase rectifier module; the output filter module is connected to the DC output end of the three-phase rectifier module; and the clamp module is connected to the DC output end of the three-phase rectifier module and comprises a first freewheeling device and a second freewheeling device connected in series, wherein the connection point between the first freewheeling device and the second freewheeling device is connected to the input filter neutral point or the neutral point of the three-phase AC power supply as a first clamp midpoint.

[0008] According to the three-phase active PFC circuit provided in some embodiments of the present application, the first freewheeling device and the second freewheeling device are both diodes.

[0009] According to the three-phase active PFC circuit provided in some embodiments of the present application, both the first freewheeling device and the second freewheeling device are switching tubes.

[0010] According to the three-phase active PFC circuit provided in some embodiments of the present application, the first freewheeling device and the second freewheeling device both use switching tubes with anti-parallel diodes.

[0011] According to the three-phase active PFC circuit provided in some embodiments of the present application, the output filter module includes a first output filter inductor and a first output filter capacitor connected in series.

[0012] According to the three-phase active PFC circuit provided in some embodiments of the present application, the output filter module includes a first output filter inductor, a first output filter capacitor, and a second output filter inductor connected in series.

[0013] According to the three-phase active PFC circuit provided in some embodiments of the present application, the output filter module includes a first output filter inductor, a first output filter capacitor, a second output filter capacitor and a second output filter inductor connected in series in sequence.

[0014] According to the three-phase active PFC circuit provided by some embodiments of the present application, the connection point of the first output filter capacitor and the second output filter capacitor serves as the second clamping midpoint and is connected to the first clamping midpoint.

[0015] According to the three-phase active PFC circuit provided in some embodiments of the present application, the three-phase rectifier module includes a first bridge arm, a second bridge arm and a third bridge arm connected in parallel, and the first bridge arm, the second bridge arm and the third bridge arm are each formed by two diodes connected in series.

[0016] According to the three-phase active PFC circuit provided in some embodiments of the present application, the first bridge arm, the second bridge arm, and the third bridge arm are each formed by two switching tubes connected in series.

[0017] According to the three-phase active PFC circuit provided in some embodiments of the present application, the first bridge arm, the second bridge arm, and the third bridge arm are each formed by two switching tubes with anti-parallel diodes connected in series.

[0018] According to some embodiments of the present application, the three-phase active PFC circuit includes a bidirectional controllable switch including a first switch tube and a second switch tube connected in series. The first switch tube and the second switch tube have opposite conduction directions and are each provided with an anti-parallel diode.

[0019] According to some embodiments of the present application, a three-phase active PFC circuit is provided, wherein the bidirectional controllable switch includes a forward conducting branch and a reverse conducting branch connected in parallel, wherein the forward conducting branch includes a third switching tube and a first diode connected in series, and wherein the reverse conducting branch includes a fourth switching tube and a second diode connected in series.

[0020] According to some embodiments of the present application, the three-phase active PFC circuit provided by the bidirectional controllable switch includes a fourth bridge arm formed by a third diode and a fourth diode connected in series, a fifth bridge arm formed by a fifth diode and a sixth diode connected in series, and a sixth bridge arm formed by a fifth switch tube. The fourth bridge arm, the fifth bridge arm, and the sixth bridge arm are connected in parallel to each other.

[0021] According to the three-phase active PFC circuit provided by some embodiments of the present application, the bidirectional controllable switch includes a RB-IGBT device.

[0022] According to the three-phase active PFC circuit provided in some embodiments of the present application, the bidirectional switch module alternately switches between a first state, a second state, and a third state. The first state is when the three bidirectional controllable switches are off. The second state is when one of the three bidirectional controllable switches whose corresponding phase voltage is greater than zero and one of the three bidirectional controllable switches whose corresponding phase voltage is less than zero are simultaneously turned on. The third state is when the three bidirectional controllable switches are simultaneously turned on.

[0023] In a second aspect, an embodiment of the present application provides a circuit board comprising the three-phase active PFC circuit as described in the embodiment of the first aspect above.

[0024] In a third aspect, an embodiment of the present application provides a controller comprising the circuit board described in the embodiment of the second aspect above.

[0025] In a fourth aspect, an embodiment of the present application provides an air conditioner, comprising the circuit board as described in the embodiment of the second aspect above or the controller as described in the embodiment of the third aspect above.

[0026] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purposes and other advantages of the present application can be achieved and obtained through the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0028] The present application is further described below with reference to the accompanying drawings and embodiments;

[0029] Figure 1 is a schematic diagram of a commonly used three-phase Boost active PFC circuit;

[0030] Figure 2 is a schematic diagram of a commonly used three-phase Buck active PFC circuit;

[0031] FIG3 is a schematic diagram of the phase sequence and sector division of a three-phase AC power supply;

[0032] FIG4 a is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0033] FIG4 b is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0034] FIG4 c is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0035] FIG5 is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0036] FIG6 a is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0037] FIG6 b is a circuit schematic diagram of a three-phase active PFC circuit provided in an embodiment of the present application;

[0038] FIG7 is a circuit diagram of an implementation of a three-phase rectifier module provided in an embodiment of the present application;

[0039] FIG8 a is a device schematic diagram of an implementation of a bidirectional controllable switch provided in an embodiment of the present application;

[0040] FIG8 b is a device schematic diagram of another implementation of a bidirectional controllable switch provided in an embodiment of the present application;

[0041] FIG8 c is a device schematic diagram of another implementation of a bidirectional controllable switch provided in an embodiment of the present application;

[0042] FIG8 d is a device schematic diagram of another implementation of a bidirectional controllable switch provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] This section will describe the specific embodiments of the present application in detail. The preferred embodiments of the present application are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present application, but it cannot be understood as a limitation on the scope of protection of the present application.

[0044] In the description of the embodiments of this application, "several" means one or more, "more" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. "At least one" means one or more, "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. If "first," "second," or the like is used in the description, it is only for the purpose of distinguishing technical features and is not to be understood as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0045] It should be noted that the terms "dispose," "install," and "connect" in the embodiments of this application should be interpreted broadly. Those skilled in the art can reasonably determine the specific meanings of these terms in the embodiments of this application based on the specific content of the technical solution. For example, the term "connect" can refer to mechanical connection, electrical connection, or communication; it can refer to direct connection or indirect connection through an intermediary.

[0046] It should be noted that the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0047] As power grid requirements for harmonics increase, power factor correction (PFC) circuits have become standard for all electrical products. There are two common methods for power factor correction: passive and active. Passive PFC primarily uses a large reactor connected in series with the power input to filter the current, but generally results in a lower power factor. Compared to passive PFC, active PFC uses high-frequency switching devices, achieving a power factor of 0.99 while significantly reducing the size and weight of the reactor, effectively increasing the product's power density.

[0048] Boost is the most common approach in the industry for active PFC. Three-phase active PFC circuits include three-phase boost active PFC and three-phase buck active PFC. Common three-phase boost active PFC topologies include two-level and three-level. Both topologies boost the DC voltage on the load side when converting AC to DC.

[0049] Currently, the commonly used three-phase Boost active PFC circuit is shown in Figure 1. This circuit uses a three-phase Vienna topology. The DC voltage on the load side increases, which requires high-voltage power devices on the load side, increasing costs. In addition, the wiring requires a higher clearance to meet safety regulations, resulting in an increase in product size. In addition, the high-voltage device loss is large, reducing system efficiency. Specifically, when the line voltage of the three-phase AC power input is 380V, with PFC turned on, if the A phase voltage v a >B phase voltage v b , switch tubes T1 to T4 are turned on, and the current from phase A passes through inductor L1, switch tube T1, switch tube T2, switch tube T4, switch tube T3, inductor L2 in sequence, and finally flows into phase B. During this stage, inductor L1 and inductor L2 store energy; when switch tubes T1 to T4 are turned off, the current from phase A passes through inductor L1, diode D1, capacitor C1, capacitor C2, diode D4, inductor L2 in sequence, and finally flows into phase B. During this stage, inductor L1 and inductor L2 release energy, and the voltage loaded on capacitor C1 and capacitor C2 is the output voltage v o , then v AB +v L1 +v L2 -v o =0, in this mode, the switch tubes T1 to T4 are switched according to v AB (t) Real-time adjustment of the conduction duty cycle D(t), the output voltage Since 0≤D(t)<1, the output voltage v o ≥v AB In three-phase applications, the output voltage will reach over 600V. Such a high voltage is a great challenge for the devices on the load side.

[0050] Therefore, a three-phase Buck active PFC circuit as shown in Figure 2 is proposed, in which the three bridge arms of the controlled rectifier bridge each include an upper switch tube and a lower switch tube, with a total of six controllable switch tubes that need to be individually controlled. In other words, six independent drive circuits are required, which has great driving difficulty and high driving cost. Specifically, as shown in Figure 2, the three-phase AC power supply is first filtered by LC, such as inductor L1 and capacitor C1, inductor L2 and capacitor C2, inductor L3 and capacitor C3 in Figure 2, and then enters the controlled rectifier bridge. Each bridge arm of the controlled rectifier bridge is a reverse resistance type, consisting of a controllable switch device and a diode in series, such as switch tube T1 and diode D1, switch tube T2 and diode D2, switch tube T3 and diode D3, switch tube T4 and diode D4, switch tube T5 and diode D5, and switch tube T6 and diode D6 in Figure 2. After rectification, the current is filtered by LC and then output, such as the inductor L4, inductor L5 and capacitor C4 in Figure 2. When the controlled rectifier bridge is closed, the current on the inductor L4 and inductor L5 is freewheeling through the diode D7. According to the characteristics of the voltage waveform of the three-phase AC power supply, as shown in Figure 3, it is divided into 12 sectors within one cycle and controlled separately. Referring to the phase sequence and sector division of the three-phase AC power supply shown in Figure 3, For example, within the sector, v a >0, v b <v c <0, when the switch tube on the controlled rectifier bridge is turned on, the current flows from phase A (phase voltage greater than 0) to phase B and phase C (phase voltage less than 0). Among them, when phase A flows into phase B, the upper bridge switch tube T1 of phase A and the lower bridge switch tube T4 of phase B are turned on, and the current flows from the phase A power supply through the inductor L1, diode D1, switch tube T1, inductor L4, capacitor C4, inductor L5, switch tube T4, diode D4, inductor L2 and then flows into the phase B power supply. At this time, v AB -v L1 -v L4 -v L5 -v L2 -v o =0; when the current flows from phase A to phase C, the upper bridge switch T1 of phase A and the lower bridge switch T6 of phase C are turned on, and the current flows from the power supply of phase A through the inductor L1, diode D1, switch T1, inductor L4, capacitor C4, inductor L5, switch T6, diode D6, and inductor L3 to the power supply of phase C. At this time, v AC -v L1 -v L4 -v L5 -v L3 -v o=0; When the switch tubes T1 to T6 are all turned off, the inductors L1 to L3 continue to flow through the capacitors C1 to C3 respectively, while the inductors L4 and L5 continue to flow through the diode D7. At this time, v L4 +v L5 +v D7 -v o = 0. In this sector, the on-duty cycle of the switch is D(t), and the output voltage is v o =v(t)×D(t), v(t)∈(v AB ,v AC ), since D(t) ≤ 1, the output voltage is lower than the input voltage. In this circuit topology, the controlled rectifier bridge consists of six controllable switches, T1 through T6, and these six switches switch independently. Therefore, six independent drive circuits are required, increasing the difficulty and cost of driving.

[0051] In addition, when the three-phase Buck active PFC circuit shown in Figure 2 causes the current to flow from phase A to phase B during power factor correction, v P =v A , v N =v B , then the voltage on the switch tube T6 is the line voltage v BC When all six switches T1 to T6 are turned off, the inductors L1 to L3 continue to flow through the capacitors C1 to C3 respectively, and the six switches T1 to T6 are combined in pairs and connected in series to the line voltage v AB 、v AB 、v BC 、v CA 、v CB 、v BA Therefore, one switch must always withstand the maximum line voltage, necessitating the use of a switch with a higher withstand voltage. Based on the above analysis, in the circuit topology shown in Figure 2, when the circuit performs power factor correction to control the on / off of each switch, one of the six switches T1 to T6 that are not turned on must withstand two phase voltages. When the three-phase line voltage is 380V, the spike voltage experienced by the device can reach over 600V, necessitating the use of a high-voltage withstand device, resulting in increased losses and higher costs.

[0052] Based on this, the embodiments of the present application provide a three-phase active PFC circuit, circuit board, controller and air conditioner, which can simplify the control logic and reduce the driving difficulty, thereby saving the driving circuit and reducing the driving cost; it can also reduce the withstand voltage of the switching device, reduce costs and losses, and improve the reliability of the circuit system.

[0053] The embodiments of the present application are further described below with reference to the accompanying drawings.

[0054] 4a to 4c , a first embodiment of the present application provides a three-phase active PFC circuit, including an input filter module 100 , a bidirectional switch module 200 , a three-phase rectifier module 300 , an output filter module 400 , and a clamping module 500 , wherein:

[0055] The input filter module 100 includes three input filter inductors and three input filter capacitors; one end of the three input filter inductors is connected to the three-phase AC power supply, and the other end is connected to one end of the three input filter capacitors; the other ends of the three input filter capacitors are connected together to form the input filter neutral point; specifically, as shown in Figures 4a to 4c, the three input filter inductors are inductor L1, inductor L2 and inductor L3, and the three input filter capacitors are capacitor C1, capacitor C2 and capacitor C3; one end of the inductor L1 is connected to phase A of the three-phase AC power supply, and the other end of the inductor L1 is connected to capacitor One end of C1; one end of the inductor L2 is connected to phase B of the three-phase AC power supply, and the other end of the inductor L2 is connected to one end of the capacitor C2; one end of the inductor L3 is connected to phase C of the three-phase AC power supply, and the other end of the inductor L3 is connected to one end of the capacitor C3; the other end of the capacitor C1, the other end of the capacitor C2 and the other end of the capacitor C3 are connected together to form the input filter neutral point N'; in addition, the end of the phase A power supply not connected to the inductor L1, the end of the phase B power supply not connected to the inductor L2, and the end of the phase C power supply not connected to the inductor L3 are connected together to form the neutral point N of the three-phase AC power supply.

[0056] The bidirectional switch module 200 includes three bidirectional controllable switches, one end of each of which is connected to the connection point of the three input filter inductors and the three input filter capacitors, respectively; the other ends of each of the three bidirectional controllable switches are respectively connected to the AC input end of the three-phase rectifier module 300. Specifically, as shown in Figures 4a to 4c, the bidirectional switch module 200 includes a first bidirectional controllable switch 210, a second bidirectional controllable switch 220, and a third bidirectional controllable switch 230. One end of the first bidirectional controllable switch 210 is connected to the connection point of the inductor L1 and the capacitor C1, one end of the second bidirectional controllable switch 220 is connected to the connection point of the inductor L2 and the capacitor C2, and one end of the third bidirectional controllable switch 230 is connected to the connection point of the inductor L3 and the capacitor C3. The other ends of the first bidirectional controllable switch 210, the second bidirectional controllable switch 220, and the third bidirectional controllable switch 230 are respectively connected to the AC input end of the three-phase rectifier module 300, that is, respectively connected to the midpoints of the three rectifier bridge arms of the three-phase rectifier module 300.

[0057] The output filter module 400 is connected to the DC output end of the three-phase rectifier module 300; specifically, the output filter module 400 includes a first output filter inductor L4 and a first output filter capacitor C4, and their connection relationship is shown in Figure 4b or Figure 4c; Referring to Figure 4b, the positive pole of the DC output end of the three-phase rectifier module 300 is connected to one end of the first output filter inductor L4, the other end of the first output filter inductor L4 is connected to one end of the first output filter capacitor C4, and the other end of the first output filter capacitor C4 is connected to the negative pole of the DC output end of the three-phase rectifier module 300; Referring to Figure 4c, the positive pole of the DC output end of the three-phase rectifier module 300 is connected to one end of the first output filter capacitor C4, the other end of the first output filter capacitor C4 is connected to one end of the first output filter inductor L4, and the first output filter inductor The other end of L4 is connected to the negative pole of the DC output terminal of the three-phase rectifier module 300; in addition, referring to Figure 4a, the output filter module 400 may further include a second output filter inductor L5 on the basis of including the first output filter inductor L4 and the first output filter capacitor C4, that is, the output filter module 400 includes the first output filter inductor L4, the first output filter capacitor C4 and the second output filter inductor L5 at the same time, the positive pole of the DC output terminal of the three-phase rectifier module 300 is connected to one end of the first output filter inductor L4, the other end of the first output filter inductor L4 is connected to one end of the first output filter capacitor C4, the other end of the first output filter capacitor C4 is connected to one end of the second output filter inductor L5, and the other end of the second output filter inductor L5 is connected to the negative pole of the DC output terminal of the three-phase rectifier module 300.

[0058] The clamping module 500 is connected to the DC output end of the three-phase rectifier module 300, and includes a first freewheeling device and a second freewheeling device connected in series. The connection point of the first freewheeling device and the second freewheeling device is connected to the neutral point of the input filter or the neutral point of the three-phase AC power supply as the first clamping midpoint; specifically, as shown in Figure 4a, the clamping module 500 includes a diode D7 and a diode D8 connected in series, that is, the first freewheeling device is the diode D7, the second freewheeling device is the diode D8, the negative pole of the DC output end of the three-phase rectifier module 300 is connected to the anode of the diode D8, the cathode of the diode D8 is connected to the anode of the diode D7, the cathode of the diode D8 is connected to the positive pole of the DC output end of the three-phase rectifier module 300, and the diode The connection point of diode D7 and diode D8 is connected to the input filter neutral point N' as the first clamping midpoint O, as shown by the dotted line X1 in Figure 4a, or the connection point of diode D7 and diode D8 is connected to the neutral point N of the three-phase AC power supply as the first clamping midpoint O, as shown by the dotted line X2 in Figure 4a; in addition, in addition to diodes, the first and second freewheeling devices in the clamping module 500 can also use switching tubes, or switching tubes with anti-parallel diodes, that is, the diode D7 and diode D8 connected in series in Figure 4a can be replaced by two switching tubes connected in series, or replaced by two switching tubes connected in series with anti-parallel diodes, for example, as shown by the switching tube T7 and the switching tube T8 in Figure 5.

[0059] According to the three-phase active PFC circuit provided by some embodiments of the present application, a bidirectional switch module 200 is provided between the input filter module 100 and the three-phase rectifier module 300, and power factor correction is achieved by controlling the on and off of the three bidirectional controllable switches in the bidirectional switch module 200. When the bidirectional switch module 200 is turned on, the current flows from the phase voltage greater than zero to the phase voltage less than zero. When the bidirectional switch module 200 is turned off, the three input filter inductors are freewheeling through the three input filter capacitors, and at the same time, the output filter module 400 can be freewheeling through the three-phase rectifier module 300. Since the three bidirectional controllable switches are connected in series between the input filter module 100 and the three-phase rectifier module 300, there is no distinction between the upper and lower bridge arms. When the current flows into or out of a phase, the corresponding current is controlled. The bidirectional controllable switches only need to be turned on and off, and only three drive signals need to be configured to control the three bidirectional controllable switches respectively. There is no need to control the upper switch tubes and the lower switch tubes of the three rectifier bridge arms respectively according to the current flow direction. That is, compared with the three-phase buck active PFC circuit in the related art, it can simplify the control logic and reduce the driving difficulty, thereby saving the driving circuit and reducing the driving cost; in addition, a clamping module 500 is provided and the first clamping midpoint of the clamping module 500 is connected to the input filter neutral point or to the neutral point of the three-phase AC power supply, so that when the three bidirectional controllable switches are all turned off, they only need to withstand the corresponding phase voltage without having to withstand a large line voltage, thereby reducing the withstand voltage of the switching device, reducing cost and loss, and improving the reliability of the circuit system.

[0060] Specifically, taking FIG4a as an example, combined with the phase sequence and sector division of the three-phase AC power supply shown in FIG3, Inside the fan room, v a >0, v b <v c <0, when the bidirectional switch module 200 is turned on, the current flows from the phase A whose phase voltage is greater than 0 into the phase B and phase C whose phase voltage is less than 0 respectively; wherein when the current flows from phase A into phase B, the first bidirectional controllable switch 210 corresponding to A and the second bidirectional controllable switch 220 corresponding to B are turned on, and the third bidirectional controllable switch 230 corresponding to C is turned off, and the current flows from the phase A power supply through the inductor L1, the switch tube T1, the switch tube T2, the diode D1, the inductor L4, the capacitor C4, the inductor L5, the diode D4, the switch tube T4, the switch tube T3, and the inductor L2 into the phase B power supply. At this time, v p =v A , v n =v B The voltage borne by the third bidirectional controllable switch 230 that is not turned on is v BC , because v b <v c <0, so v BC <v b, that is, the voltage borne by the third bidirectional controllable switch 230 is less than the phase voltage; in addition, when the first bidirectional controllable switch 210 corresponding to A, the second bidirectional controllable switch 220 corresponding to B, and the third bidirectional controllable switch 230 corresponding to C are all turned off, the inductors L1 to L3 are respectively freewheeling through the capacitors C1 to C3, while the inductors L4 and L5 are freewheeling through the diodes D8 and D7, or through the three bridge arms in the three-phase rectifier module 300. At this time, v p =v n It is also equal to the voltage of the input filter neutral point N′ or the neutral point N of the three-phase AC power supply. The first bidirectional controllable switch 210 , the second bidirectional controllable switch 220 , and the third bidirectional controllable switch 230 all bear the corresponding phase voltage.

[0061] In addition, in the three-phase active PFC circuit provided in some embodiments of the present application, the implementation of the output filter module 400 may include the implementation shown in Figures 6a and 6b in addition to the several embodiments shown in Figures 4a to 4c. In addition to Figure 4a, the output filter module 400 further includes a second output filter capacitor C5. That is, the output filter module 400 includes a first output filter inductor L4, a first output filter capacitor C4, a second output filter capacitor C5, and a second output filter inductor L5 connected in series. It will be understood that the use of the first output filter capacitor C4 and the second output filter capacitor C5 in series in the output filter module 400 can increase the withstand voltage of the output filter module 400 compared to using a single output filter capacitor, thereby preventing capacitor damage caused by overvoltage.

[0062] In the three-phase active PFC circuit shown in FIG6 b , the connection point between the first output filter capacitor C4 and the second output filter capacitor C5 serves as the second clamping midpoint O′ and is connected to the first clamping midpoint O.

[0063] It is understandable that the second clamping midpoint O' can play the same role as the first clamping midpoint O, that is, it can ensure that when the three bidirectional controllable switches of the bidirectional switch module 200 are all turned off, they only need to withstand the corresponding phase voltage without having to withstand a large line voltage, thereby reducing the withstand voltage of the switching device, reducing costs and losses, and improving the reliability of the circuit system.

[0064] In the following, various implementations of the bidirectional controllable switches in the three-phase rectifier module 300 and the bidirectional switch module 200 are introduced in combination with the aforementioned embodiments.

[0065] Referring to Figures 4a to 6b, in some embodiments of the present application, a three-phase active PFC circuit includes a first bridge arm, a second bridge arm, and a third bridge arm connected in parallel. The first bridge arm is formed by a diode D1 and a diode D2 connected in series, the second bridge arm is formed by a diode D3 and a diode D4 connected in series, and the third bridge arm is formed by a diode D5 and a diode D6 connected in series. The other end of the first bidirectional controllable switch 210 is connected to the midpoint of the first bridge arm, i.e., the connection point of the diodes D1 and D2; the other end of the second bidirectional controllable switch 220 is connected to the midpoint of the second bridge arm, i.e., the connection point of the diodes D3 and D4; and the other end of the third bidirectional controllable switch 230 is connected to the midpoint of the third bridge arm, i.e., the connection point of the diodes D5 and D6. It is understood that the three-phase rectifier module 300 formed by diodes D1 to D6 is an uncontrolled rectifier.

[0066] In the three-phase active PFC circuits provided in some other embodiments of the present application, the diodes D1 to D6 included in the three-phase rectifier module 300 in Figures 4a to 6b can be replaced by six switching tubes, or replaced by six switching tubes with anti-parallel diodes, for example, as shown by the switching tubes Q1 to Q6 in Figure 7.

[0067] It is understandable that there are multiple ways to implement the bidirectional controllable switch. It can be implemented by a single bidirectional switch controllable device, or by a circuit composed of multiple controllable devices and uncontrolled devices.

[0068] In the three-phase active PFC circuit provided in some embodiments of the present application, the implementation of the bidirectional controllable switch includes the following cases:

[0069] Case 1: including a first switching transistor and a second switching transistor connected in series, the first switching transistor and the second switching transistor having opposite conduction directions and each having an anti-parallel diode; for example, referring to Figures 4a to 6b, the first bidirectional controllable switch 210 includes a switching transistor T1 and a switching transistor T2 connected in series; the second bidirectional controllable switch 220 includes a switching transistor T3 and a switching transistor T4 connected in series; and the third bidirectional controllable switch 230 includes a switching transistor T5 and a switching transistor T6 connected in series; wherein, referring to Figure 4a, the switching transistors T1 to T6 all have anti-parallel diodes;

[0070] Case 2: including a forward conducting branch and a reverse conducting branch connected in parallel, the forward conducting branch including a third switch and a first diode connected in series, and the reverse conducting branch including a fourth switch and a second diode connected in series. For example, referring to FIG8 a , the forward conducting branch includes a switch T9 and a diode D9 connected in series, and the reverse conducting branch includes a switch T10 and a diode D10 connected in series. In addition, by swapping the positions of the switch T9 and the diode D9 in the forward conducting branch, and swapping the positions of the switch T10 and the diode D10 in the reverse conducting branch, a bidirectional controllable switch as shown in FIG8 b can be obtained.

[0071] Case 3: including a fourth bridge arm formed by a third diode and a fourth diode in series, a fifth bridge arm formed by a fifth diode and a sixth diode in series, and a sixth bridge arm formed by a fifth switch tube. For example, referring to FIG8c , the fourth bridge arm is formed by a diode D11 and a diode D12 in series; the fifth bridge arm is formed by a diode D13 and a diode D14 in series; and the sixth bridge arm is formed by a switch tube T11. The fourth bridge arm, the fifth bridge arm, and the sixth bridge arm are connected in parallel.

[0072] Case 4: including RB-IGBT devices, as shown in FIG. 8 d .

[0073] It should be noted that the above four situations are examples of some feasible embodiments of the bidirectional controllable switch, and do not limit the bidirectional controllable switch in the bidirectional switch module 200 of the invention to only adopt the above four implementation methods. Any other circuit with bidirectional opening and closing controllable functions can be adopted, as long as the bidirectional opening and closing controllable between the input filter module 100 and the three-phase rectifier module 300 can be achieved.

[0074] In the three-phase active PFC circuit provided in some embodiments of the present application, the bidirectional switch module 200 alternately switches between a first state, a second state, and a third state. In the first state, the three bidirectional controllable switches are turned off. In the second state, one of the three bidirectional controllable switches whose corresponding phase voltage is greater than zero and one of the three bidirectional controllable switches whose corresponding phase voltage is less than zero are simultaneously turned on. In the third state, the three bidirectional controllable switches are simultaneously turned on.

[0075] Specifically, the embodiment shown in FIG4a is used as an example for description, and the phase sequence and sector division of the three-phase AC power supply shown in FIG3 are combined. Inside the fan room, v a >0, v b <v c<0, when the bidirectional switch module 200 is turned on, the current flows from the phase A whose phase voltage is greater than 0 into the phase B and phase C whose phase voltage is less than 0 respectively; it can be understood that within this sector, the second state may include two situations. The first is that the first bidirectional controllable switch 210 corresponding to A and the second bidirectional controllable switch 220 corresponding to B are turned on, and the third bidirectional controllable switch 230 corresponding to C is turned off. The current flows from the A phase power supply through the inductor L1, the switch tube T1, the switch tube T2, the diode D1, the inductor L4, the capacitor C4, the inductor L5, the diode D4, the switch tube T4, the switch tube T3, and the inductor L2 to the B phase power supply. At this time, v AB -v L1 -v L4 -v L5 -v L2 -v o = 0, and v p =v A , v n =v B The voltage borne by the third bidirectional controllable switch 230 that is not turned on is v BC , because v b <v c <0, so v BC <v b , that is, the voltage borne by the third bidirectional controllable switch 230 is less than the phase voltage; the second situation is that the first bidirectional controllable switch 210 corresponding to A is turned on, the second bidirectional controllable switch 220 corresponding to B is turned off, and the third bidirectional controllable switch 230 corresponding to C is turned on. The current flows from the A phase power supply through the inductor L1, the switch tube T1, the switch tube T2, the diode D1, the inductor L4, the capacitor C4, the inductor L5, the diode D6, the switch tube T6, the switch tube T5, and the inductor L3 and then flows into the C phase power supply. At this time, v AC -v L1 -v L4 -v L5 -v L3 -v o =0; In addition, in this sector, the third state is that the first bidirectional controllable switch 210 corresponding to A, the second bidirectional controllable switch 220 corresponding to B, and the third bidirectional controllable switch 230 corresponding to C are all turned on; the first state is that the first bidirectional controllable switch 210 corresponding to A, the second bidirectional controllable switch 220 corresponding to B, and the third bidirectional controllable switch 230 corresponding to C are all turned off, and the inductors L1 to L3 are freewheeling through the capacitors C1 to C3 respectively, while the inductors L4 and L5 are freewheeling through the diode D13. At this time, v L4 +v L5 +v D13 -v o = 0, and v p =v nAnd it is also equal to the voltage of the input filter neutral point N' or the neutral point N of the three-phase AC power supply. The first bidirectional controllable switch 210, the second bidirectional controllable switch 220, and the third bidirectional controllable switch 230 all bear the corresponding phase voltage. In this sector, the conduction duty cycle of the switch tube is D(t), and the output voltage is v o =v(t)×D(t), v(t)∈(v AB ,v AC ), since D(t)≤1, the output voltage is lower than the input voltage, thus achieving voltage step-down rectification. Moreover, since the three bidirectional controllable switches are connected in series between the input filter module 100 and the three-phase rectifier module 300, there is no distinction between upper and lower bridge arms. When current flows into or out of a phase, the corresponding bidirectional controllable switch can be controlled to be on or off. Only three drive signals need to be configured to control the three bidirectional controllable switches respectively, without having to control the upper and lower switches of the three rectifier bridge arms according to the current flow direction. In other words, compared with the three-phase buck active PFC circuit in the related art, the control logic can be simplified, the driving difficulty can be reduced, and the driving circuit can be saved, thereby reducing the driving cost. The first clamping midpoint O of the clamping module 500 is connected to the input filter neutral point N' or to the neutral point N of the three-phase AC power supply. Therefore, when the three bidirectional controllable switches of the bidirectional switch module 200 alternately switch between the first state, the second state, and the third state, they only need to withstand the corresponding phase voltage and do not need to withstand the large line voltage. This can reduce the withstand voltage of the switching devices, reduce costs and losses, and improve the reliability of the circuit system.

[0076] In addition, it should be noted that when only one of the first bidirectional controllable switch 210, the second bidirectional controllable switch 220, and the third bidirectional controllable switch 230 is turned on, v p =v A , v n The voltage of the neutral point N' of the input filter or the neutral point N of the three-phase AC power supply is equal to the voltage of the neutral point L' of the input filter or the neutral point N of the three-phase AC power supply. The current of the inductor L4 and the inductor L5 continues to flow through the neutral point N' of the input filter or the neutral point N of the three-phase AC power supply. At this time, the AC power supply is connected in series, resulting in the AC power supply being unable to be turned off.

[0077] It is understandable that the working conditions of the three-phase active PFC circuit shown in FIG4a in other sectors can be determined based on the The working conditions in the fan room can be derived in the same way, so I will not go into details here.

[0078] In addition, a second embodiment of the present application provides a circuit board, including the three-phase active PFC circuit of the first embodiment, for example, including any one of the three-phase active PFC circuits in Figures 4a to 6b.

[0079] In addition, a third embodiment of the present application provides a controller, comprising the circuit board of the second embodiment above.

[0080] In addition, the fourth embodiment of the present application provides an air conditioner, including the circuit board of the second embodiment or the controller of the third embodiment.

[0081] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on computer-readable media, which can include computer storage media or non-transitory media and communication media or transient media. As is well known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVDs) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0082] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A three-phase active PFC circuit, comprising: Input filter module, including three input filter inductors and three input filter capacitors; One end of the three input filter inductors is respectively connected to a three-phase AC power supply, and the other end is respectively connected to one end of the three input filter capacitors; the other ends of the three input filter capacitors are connected together to form an input filter neutral point; a bidirectional switch module, comprising three bidirectional controllable switches, one end of each of the three bidirectional controllable switches being connected to a connection point between the three input filter inductors and the three input filter capacitors, respectively; A three-phase rectifier module, wherein the other ends of the three bidirectional controllable switches are respectively connected to the AC input ends of the three-phase rectifier module; an output filter module, the output filter module being connected to a DC output terminal of the three-phase rectifier module; and A clamping module is connected to the DC output end of the three-phase rectifier module, and includes a first freewheeling device and a second freewheeling device connected in series. The connection point of the first freewheeling device and the second freewheeling device is connected to the input filter neutral point or the neutral point of the three-phase AC power supply as a first clamping midpoint.

2. The three-phase active PFC circuit according to claim 1, wherein: The implementation of the first freewheeling device and the second freewheeling device includes the following situations: Case 1: Diodes are used; Case 2: Both use switching tubes; Case 3: Both use switching tubes with anti-parallel diodes.

3. The three-phase active PFC circuit according to claim 1 or 2, wherein: The implementation of the output filter module includes the following situations: Case 1: including a first output filter inductor and a first output filter capacitor connected in series; Case 2: comprising a first output filter inductor, a first output filter capacitor, and a second output filter inductor connected in series in sequence; Case 3: including a first output filter inductor, a first output filter capacitor, a second output filter capacitor, and a second output filter inductor connected in series in sequence.

4. The three-phase active PFC circuit according to claim 3, wherein: In the third scenario, the connection point between the first output filter capacitor and the second output filter capacitor serves as a second clamping midpoint and is connected to the first clamping midpoint.

5. The three-phase active PFC circuit according to any one of claims 1 to 4, wherein: The three-phase rectifier module includes a first bridge arm, a second bridge arm, and a third bridge arm connected in parallel. The implementation of the first bridge arm, the second bridge arm, and the third bridge arm includes the following situations: Case 1: Both are formed by two diodes connected in series; Case 2: Both are formed by two switching tubes connected in series; Case 3: Both are formed by two switching tubes with anti-parallel diodes connected in series.

6. The three-phase active PFC circuit according to any one of claims 1 to 5, wherein: The implementation of the bidirectional controllable switch includes the following situations: Case 1: comprising a first switching tube and a second switching tube connected in series, wherein the first switching tube and the second switching tube have opposite conduction directions and are respectively provided with an anti-parallel diode; Case 2: comprising a forward conducting branch and a reverse conducting branch connected in parallel, wherein the forward conducting branch comprises a third switch tube and a first diode connected in series, and the reverse conducting branch comprises a fourth switch tube and a second diode connected in series; Case 3: including a fourth bridge arm formed by a third diode and a fourth diode in series, a fifth bridge arm formed by a fifth diode and a sixth diode in series, and a sixth bridge arm formed by a fifth switch tube, wherein the fourth bridge arm, the fifth bridge arm, and the sixth bridge arm are connected in parallel; Case 4: Including RB-IGBT devices.

7. The three-phase active PFC circuit according to any one of claims 1 to 6, wherein: The bidirectional switch module alternately switches between a first state, a second state, and a third state. The first state is when the three bidirectional controllable switches are turned off. The second state is when one of the three bidirectional controllable switches whose corresponding phase voltage is greater than zero and one of the three bidirectional controllable switches whose corresponding phase voltage is less than zero are simultaneously turned on. The third state is when the three bidirectional controllable switches are simultaneously turned on.

8. A circuit board comprising the three-phase active PFC circuit according to any one of claims 1 to 7.

9. A controller comprising the circuit board according to claim 8.

10. An air conditioner comprising the circuit board according to claim 8 or the controller according to claim 9.

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