Z-source network inverter circuit, circuit board, controller and air conditioner

Abstract

The utility model discloses a Z-source network inverter circuit, a circuit board, a controller and an air conditioner, the Z-source network inverter circuit comprises a rectifier module, an X-type impedance network, an IPM module and an AC power supply module used for accessing an AC power supply, and the rectifier module comprises a filter inductor, a follow current capacitor and a rectifier bridge. One output end of the alternating current power supply module is connected with one input end of the rectifier bridge through the filter inductor, the other input end of the rectifier bridge is connected with the other output end of the alternating current power supply module, and two ends of the follow current capacitor are correspondingly connected with two output ends of the rectifier bridge; the two input ends of the X-type impedance network are connected to the two ends of the follow current capacitor, and the two input ends of the IPM module are connected to the two output ends of the X-type impedance network, so that the follow current capacitor provides reverse follow current when the IPM module is in a non-straight-through zero vector state. The Z-source network inverter circuit provided by the embodiment of the utility model can effectively improve the stability of current output under the condition that an alternating current power supply is used as input.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a Z-source network inverter circuit, a circuit board, a controller and an air conditioner. Background Art

[0002] At present, the Z-source network inverter circuit may include an X-type impedance network and an intelligent power module (IPM). The input power supply, the X-type impedance network and the IPM module are connected in parallel in sequence, so that the DC link voltage output by the X-type impedance network can be increased by controlling the IPM module to provide a high-voltage power supply for the high-voltage load. Due to the power supply characteristics of the AC power supply, when the rectifier bridge is used for power conversion, the output current will be pulsed and the current will be intermittent, which will affect the power output stability of the Z-source network inverter circuit. Therefore, the Z-source network inverter circuit in the related art usually uses a DC current source as the power input. Utility Model Content

[0003] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art, and to provide a Z-source network inverter circuit, a circuit board, a controller and an air conditioner, which can effectively improve the stability of current output when an AC power supply is used as input.

[0004] In a first aspect, an embodiment of the utility model provides a Z-source network inverter circuit, comprising:

[0005] AC power module, used to connect to AC power;

[0006] A rectifier module, comprising a filter inductor, a freewheeling capacitor and a rectifier bridge, wherein one output end of the AC power supply module is connected to one input end of the rectifier bridge through the filter inductor, the other input end of the rectifier bridge is connected to the other output end of the AC power supply module, and the two ends of the freewheeling capacitor are correspondingly connected to the two output ends of the rectifier bridge;

[0007] An X-type impedance network, wherein two input ends of the X-type impedance network are connected to two ends of the freewheeling capacitor;

[0008] An IPM module, wherein two input terminals of the IPM module are connected to two output terminals of the X-type impedance network, so that when the IPM module is in a non-through zero vector state, the freewheeling capacitor provides a reverse freewheeling current.

[0009] According to the Z-source network inverter circuit provided by the embodiment of the utility model, at least the following beneficial effects are achieved: the connected AC power is converted by the rectifier bridge in the rectifier module to provide a DC power supply for the subsequent X-type impedance network and IPM module. At the same time, the AC power module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than that of the capacitor of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0010] In the Z-source network inverter circuit provided in an embodiment of the utility model, the X-type impedance network includes a first inductor, a second inductor, a first capacitor and a second capacitor; one end of the freewheeling capacitor, one end of the first inductor and one end of the first capacitor are connected at the same time, an input end of the IPM module, the other end of the first inductor and one end of the second capacitor are connected at the same time, the other input end of the IPM module, the other end of the first capacitor and one end of the second inductor are connected at the same time, and the other end of the freewheeling capacitor, the other end of the second capacitor and the other end of the second inductor are connected at the same time.

[0011] In the Z-source network inverter circuit provided in an embodiment of the utility model, it also includes a first switch tube for switching the conduction state between the rectifier module and the X-type impedance network, and one end of the freewheeling capacitor is connected to the connection point between the first inductor and the first capacitor through the first switch tube.

[0012] In the Z-source network inverter circuit provided in an embodiment of the utility model, it also includes a guide diode, the cathode end of the guide diode is connected to the connection point between the first inductor and the first capacitor, and the anode end of the guide diode is connected to one end of the freewheeling capacitor.

[0013] In the Z-source network inverter circuit provided in an embodiment of the utility model, it also includes a positive DC bus and a negative DC bus, one end of the filter capacitor is connected to the connection point between the first inductor and the first capacitor through the positive DC bus, and the other end of the filter capacitor is connected to the connection point between the second inductor and the second capacitor through the negative DC bus.

[0014] In the Z-source network inverter circuit provided in an embodiment of the utility model, the IPM module includes multiple parallel bridge arms, each of which includes an upper bridge arm switch tube, a lower bridge arm switch tube, and a reverse diode connected in parallel with each of the bridge arm switch tubes, and the midpoint of each of the bridge arms is provided with a power supply port for supplying power to the load.

[0015] In the Z-source network inverter circuit provided in an embodiment of the utility model, the rectifier bridge includes two rectifier half-bridges connected in parallel, each of the rectifier half-bridges includes two rectifier devices connected in series, one output end of the AC power supply module is connected to the midpoint of one of the rectifier half-bridges through the filter inductor, and the other output end of the AC power supply module is connected to the midpoint of the other rectifier half-bridge.

[0016] In a second aspect, an embodiment of the utility model provides a circuit board, comprising the Z-source network inverter circuit as described in the embodiment of the first aspect above.

[0017] According to the circuit board provided by the embodiment of the utility model, at least the following beneficial effects are achieved: a Z-source network inverter circuit is arranged on the circuit board, and the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module, and provides a DC power supply for the subsequent X-type impedance network and IPM module. At the same time, the AC power supply module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than that of the capacitor of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when the AC power supply is used, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0018] In a third aspect, an embodiment of the utility model provides a controller, comprising the circuit board as described in the embodiment of the second aspect above.

[0019] According to the controller provided by the embodiment of the utility model, at least the following beneficial effects are achieved: a Z-source network inverter circuit is arranged in the controller, and the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module, and provides a DC power supply for the subsequent X-type impedance network and the IPM module. At the same time, the AC power supply module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than that of the capacitor of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when the AC power supply is used, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0020] In a fourth aspect, an embodiment of the utility model provides an air conditioner, comprising the circuit board as described in the embodiment of the second aspect or the controller as described in the embodiment of the third aspect.

[0021] The air conditioner provided according to the embodiment of the utility model has at least the following beneficial effects: a Z-source network inverter circuit is arranged in the air conditioner, and the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module, and provides a DC power supply for the subsequent X-type impedance network and IPM module. At the same time, the AC power supply module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than the capacitance of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0022] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by practicing the utility model. The purpose and other advantages of the utility model can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the technical solution of the utility model and constitute a part of the specification. Together with the embodiments of the utility model, they are used to explain the technical solution of the utility model and do not constitute a limitation on the technical solution of the utility model.

[0024] The utility model is further described below in conjunction with the accompanying drawings and embodiments;

[0025] Figure 1 It is a circuit structure diagram of a Z-source network inverter circuit provided by an embodiment of the utility model;

[0026] Figure 2 It is a circuit connection diagram of a Z-source network inverter circuit provided by an embodiment of the utility model;

[0027] Figure 3 It is an equivalent circuit diagram of the IPM module provided by the embodiment of the utility model in a non-through zero vector state;

[0028] Figure 4 It is an equivalent circuit diagram of the DC side of the Z source network inverter circuit provided by the embodiment of the utility model;

[0029] Figure 5 It is an equivalent circuit diagram of the DC side of the Z source network inverter circuit when the IPM module provided by the embodiment of the utility model is in a non-through zero vector state;

[0030] Figure 6 It is an equivalent circuit diagram of the DC side of the Z source network inverter circuit when the IPM module provided by the embodiment of the utility model is in a direct zero vector state. DETAILED DESCRIPTION

[0031] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model 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 the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0032] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, "above", "below", "within", etc. are understood to include the number itself, "any 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 there is a description of the first and the second, it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0033] It should be noted that the words such as setting, installing, and connecting in the embodiments of the present invention should be understood in a broad sense, and the technical personnel in the relevant technical field can reasonably determine the specific meanings of the above words in the embodiments of the present invention in combination with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected or indirectly connected through an intermediate medium.

[0034] It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] At present, the Z-source network inverter circuit may include an X-type impedance network and an intelligent power module (IPM). The input power supply, the X-type impedance network and the IPM module are connected in parallel in sequence, so that the DC link voltage output by the X-type impedance network can be increased by controlling the IPM module to provide a high-voltage power supply for the high-voltage load. Due to the power supply characteristics of the AC power supply, when the rectifier bridge is used for power conversion, the output current will be pulsed and the current will be intermittent, which will affect the power output stability of the Z-source network inverter circuit. Therefore, the Z-source network inverter circuit in the related art usually uses a DC current source as the power input.

[0036] Based on this, the embodiment of the utility model proposes a Z-source network inverter circuit, a circuit board, a controller and an air conditioner. The Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module to provide a DC power supply for the subsequent X-type impedance network and the IPM module. At the same time, the AC power module is connected to the rectifier bridge through a filter inductor. The filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor. The capacitance of the freewheeling capacitor is smaller than that of the capacitor of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when the AC power supply is used, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0037] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings.

[0038] Reference Figure 1 , Figure 1It is a circuit structure diagram of the Z source network inverter circuit provided by the embodiment of the utility model. It can be understood that the Z source network inverter circuit includes an AC power supply module, a rectifier module, an X-type impedance network and an IPM module. The AC power supply module is used to access an external AC power supply, so that the Z source network inverter circuit can obtain an AC power supply as a power supply for the circuit. The AC power supply module has two output terminals, namely a positive output terminal and a negative output terminal, one of which is connected to the filter inductor Lp in the rectifier module, and is connected to an input terminal of the rectifier bridge through the filter inductor Lp, and the other output terminal is connected to the other input terminal of the rectifier bridge. Therefore, after the AC power supply module is connected to the AC power supply, it will flow through the filter inductor Lp for filtering, and then flow to the rectifier bridge, so that the input current can be prevented from changing suddenly, so that the current flowing to the next stage is more stable, and at the same time, the rectifier bridge can rectify and convert the AC power supply connected to the AC power supply module, and output the rectified DC power supply through the output terminal of the rectifier bridge, and provide a DC power supply for the freewheeling capacitor Cp, the X-type impedance network and the IPM module of the next stage.

[0039] In addition to the filter capacitor and the rectifier bridge, the rectifier module also includes a freewheeling capacitor Cp. The freewheeling capacitor Cp is a small-capacitance capacitor. Compared with the filter capacitor used in the rectifier circuit of the related technology, the freewheeling capacitor Cp is different. The capacitance of the freewheeling capacitor Cp is smaller and the main function of the freewheeling capacitor Cp is to provide reverse freewheeling current for the Z source network inverter circuit when the subsequent IPM module is in a non-through zero vector state, rather than filtering out the second harmonic, thereby effectively avoiding the occurrence of current discontinuity when using AC power as input, and then providing a stable current input for the X-type impedance network, improving the stability and reliability of the Z source network inverter circuit when using AC power input.

[0040] The two input ends of the X-type impedance network are connected to the two ends of the freewheeling capacitor Cp, which is equivalent to the two input ends of the X-type impedance network being connected to the two output ends of the rectifier module to obtain the rectified DC power supply. The two output ends of the IPM module are connected to the two output ends of the X-type impedance network to obtain the DC link voltage after buck-boost.

[0041] It should be noted that when the IPM module operates in different voltage vector states, the DC link voltage output by the X-type impedance network is different. Specifically, when the IPM module operates in the direct-through zero vector state, the DC link voltage output by the X-type impedance network will be higher than the input voltage of the X-type impedance network, thereby being able to increase the input voltage of the IPM module; when the IPM module operates in the non-direct-through zero vector state, the DC link voltage output by the X-type impedance network will not be higher than the input voltage of the X-type impedance network.

[0042] Reference Figure 2 , Figure 2It is a schematic diagram of the topological structure of the Z source network inverter circuit provided by the embodiment of the utility model. It can be understood that the X-type impedance network includes two identical inductors (i.e., the first inductor L1 and the second inductor L2) and two identical X-type connected capacitors (i.e., the first capacitor C1 and the second capacitor C2), specifically, one end of the first inductor L1 is simultaneously connected to one end of the freewheeling capacitor and one end (anode end) of the first capacitor C1, the other end of the first inductor L1 is simultaneously connected to one end (anode end) of the second capacitor C2 and an input end (positive input end) of the IPM module, one end of the second inductor L2 is simultaneously connected to an input end (negative input end) of the IPM module and the other end (cathode end) of the first capacitor C1, and the other end of the second inductor L2 is simultaneously connected to the other end of the freewheeling capacitor and the other end (cathode end) of the second capacitor C2. The IPM module can be driven by changing the PWM modulation signal so that the first inductor L1 and the second inductor L2 can store electric energy, thereby increasing the output side voltage of the X-type impedance network, so that the output side voltage of the X-type impedance network can be greater than the input side voltage, that is, the X-type impedance network can operate in a boost state.

[0043] It can be understood that the IPM module includes a plurality of bridge arms connected in parallel, specifically, the IPM module may include a first bridge arm, a second bridge arm and a third bridge arm, wherein the first bridge arm includes a first upper bridge arm switch tube and a first lower bridge arm switch tube; the second bridge arm includes a second upper bridge arm switch tube and a second lower bridge arm switch tube; the third bridge arm includes a third upper bridge arm switch tube and a third lower bridge arm switch tube. Power supply ports are provided at the midpoint A of the first bridge arm (i.e., the connection point of the first upper bridge arm switch tube and the first lower bridge arm switch tube), the midpoint B of the second bridge arm (i.e., the connection point of the second upper bridge arm switch tube and the second lower bridge arm switch tube), and the midpoint C of the third bridge arm (i.e., the connection point of the third upper bridge arm switch tube and the third lower bridge arm switch tube), so the load can obtain the power after the IPM module inversion process by connecting the power supply port. In addition, the switch tubes of each bridge arm are connected in parallel with reverse diodes. The conduction direction of the reverse diodes is opposite to the conduction direction of the switch tubes. When the switch tubes are turned off, due to the presence of parasitic inductance in the circuit, a high voltage shutdown surge voltage will be generated at both ends of the switch tubes, which can easily damage the switch tubes of the bridge arms. The reverse diodes can provide a freewheeling path for the reverse electromotive force generated by the parasitic inductance, suppress the shutdown surge voltage, and protect the switch tubes.

[0044] Among them, the switching state of each switch tube in the IPM module is controlled by the PWM modulation signal, and the switching state of each switch tube in the IPM module is different, and the generated voltage vector is also different, so that the operation of the load (compressor) can be adjusted. These voltage vectors include zero vector and non-zero vector. The zero vector refers to a voltage vector that does not generate voltage, and the non-zero vector refers to a voltage vector that can generate a specific voltage and phase. The non-zero vector can drive the compressor to generate torque operation. The role of the zero vector is to provide a transition when switching between non-zero vectors to ensure that the voltage waveform output by the IPM module is continuous and smooth. Specifically, when one of the switch tubes in each bridge arm is turned on and the other switch tube is turned off, and the upper / lower bridge arm switch tubes of all bridge arms are not turned on or off at the same time, the IPM module can be in a non-zero vector state, and the IPM module forms a non-zero vector voltage vector through each switch tube to drive the compressor to operate; and when all upper bridge arm switch tubes are turned on at the same time and all lower bridge arm switch tubes are turned off at the same time, or when all upper bridge arm switch tubes are turned on at the same time and all lower bridge arm switch tubes are turned off at the same time, the IPM module can be in a zero vector state, that is, the IPM module can generate a zero vector voltage vector at this time. In addition, when the upper bridge arm switch tube and the lower bridge arm switch tube of any bridge arm in the IPM module are turned on at the same time, the IPM module can be in a direct zero vector state, that is, the IPM module can generate a direct zero vector voltage vector at this time, and the direct zero vector also refers to a voltage vector that does not generate voltage. Among them, when the IPM module is in a straight-through zero vector state, due to a short circuit in the bridge arm of the IPM module, the AC power supply module, the rectifier module, the X-type impedance network and the short-circuited bridge arm in the IPM module form a loop, so that the inductance and capacitance in the X-type impedance network are charged, so that when the IPM module is in a non-zero vector state, the inductance and capacitance in the X-type impedance network are discharged, and at this time, the input voltage of the X-type impedance network is greater than the output voltage.

[0045] Therefore, the IPM module can store electric energy in the first inductor L1, the second inductor L2, the first capacitor C1 and the second capacitor C2 under the drive of the PWM modulation signal, thereby increasing the output voltage of the X-type impedance network and making the output voltage of the X-type impedance network greater than the input voltage, that is, the X-type impedance can operate in a boost state.

[0046] like Figure 2As shown, a first switch tube is also provided between the X-type impedance network and the freewheeling capacitor, one end of the first switch tube is connected to the connection point between the first inductor L1 and the first capacitor C1 in the X-type impedance network, and the other end of the first switch tube is connected to one end of the freewheeling capacitor. The first switch tube can switch the conduction state between the rectifier module and the X-type impedance network. When the first switch tube is turned on, the current can flow reversely from the X-type impedance network to the rectifier module, that is, the current can flow reversely from the connection point between the first inductor L1 and the first capacitor C1 to the freewheeling capacitor. When the first switch tube is in the cut-off state, the current cannot flow reversely from the X-type impedance network to the rectifier module, so that the first switch tube can switch the current flow direction between the rectifier module and the X-type impedance network.

[0047] It can be understood that the Z source network inverter circuit also includes a guide diode, which is connected in reverse parallel to the first switch tube, which is equivalent to connecting the anode end of the guide diode to one end of the freewheeling capacitor, and the cathode end to the connection point of the first inductor L1 and the first capacitor C1. At this time, due to the setting of the guide diode, when the first switch tube is in the cut-off state, the current can only flow from the rectifier module to the X-type impedance network. When the first switch tube is in the on state, the current can flow bidirectionally between the X-type impedance network and the rectifier module.

[0048] like Figure 2 As shown, the filter capacitor Cp is connected to the connection point between the first inductor L1 and the first capacitor C1 in the X-type impedance network through the positive DC bus, and the other end of the filter capacitor Cp is connected to the connection point between the second inductor L2 and the second capacitor C2 through the negative DC bus. By connecting the filter capacitor Cp to the positive and negative DC bus, the voltage amplitude of the positive and negative DC bus can be reduced to achieve a higher input power factor.

[0049] refer to Figure 3 , Figure 3 It is an equivalent circuit diagram of the IPM module provided by the embodiment of the utility model in a non-straight-through zero vector state. It can be seen that compared with the Z-source network inverter circuit in the related art, the Z-source network inverter circuit provided by the embodiment of the utility model has an additional rectifier module to be suitable for the case of connecting to an AC power supply. At the same time, a filter inductor Lp and a freewheeling capacitor Cp are additionally added on the basis of the rectifier bridge. Due to the single-phase conductivity of the rectifier module, even if the first switch tube is turned on and reverse freewheeling is expected, it is also turned on due to the lack of power supply. Therefore, by adding the freewheeling capacitor Cp, when the first switch tube is turned on, the freewheeling capacitor Cp can provide a reverse current for the Z-source network inverter circuit. In addition, by introducing the filter inductor Lp and the freewheeling capacitor Cp in the rectifier module, an LC passive network can be formed, so that the rectified voltage on the freewheeling capacitor Cp can be kept in the form of a steamed bun wave, so that the input current provided to the X-type impedance network can be kept in the form of a sine wave with the same phase as the input voltage.

[0050] It can be understood that the rectifier bridge includes two rectifier half-bridges connected in parallel, namely, a first rectifier half-bridge and a second rectifier half-bridge, wherein the first rectifier half-bridge includes a first rectifier device and a second rectifier device connected in series, and the second rectifier half-bridge includes a third rectifier device and a fourth rectifier device connected in series, and these rectifier devices can be diodes. One output end of the AC power supply module is connected to the midpoint of the first rectifier half-bridge, namely, the connection point between the first rectifier device and the second rectifier device connected in series, through a filter inductor Lp, and the other output end of the AC power supply module is directly connected to the midpoint of the second rectifier half-bridge, namely, the connection point between the third rectifier device and the fourth rectifier device connected in series.

[0051] refer to Figure 4 , Figure 4 This is the equivalent circuit topology diagram observed from the DC side of the Z source network inverter circuit. Figure 4 As shown, the IPM module can be regarded as a controlled current source I in Since the X-type impedance network is a symmetrical circuit structure, the inductance of the first inductor L1 is the same as the inductance of the second inductor L2, and the capacitance of the first capacitor C1 is the same as the capacitance of the second capacitor C2, then the relationship (1) can be obtained:

[0052] V L1 =V L2 =V L ,V C1 =V C2 =V C (1)

[0053] Therefore, in the X-type impedance network, the voltage across the first inductor L1 is equal to the voltage across the second inductor L2, and the voltage across the first capacitor C1 is equal to the voltage across the second capacitor C2.

[0054] When the IPM module is in a non-straight-through zero vector state (i.e., a voltage vector other than the straight-through zero vector), the IPM module can provide an output voltage V in ,like Figure 5 As shown, the IPM module can be regarded as a reverse current source that provides a voltage opposite to the DC power supply that is integrated with the AC power module and the rectifier module. Therefore, equations (2) and (3) can be derived:

[0055] V dc =V C1 +V L2 =V C2 +V L1 =V C +V L (2)

[0056] V in=V C1 -V L1 =V C2 -V L2 =V C -V L (3)

[0057] Among them, V dc Represents the DC link voltage, and by combining equation (2) and equation (3), we can derive equation (4):

[0058] V in =2V C -V dc (4)

[0059] Therefore, it can be deduced that the input bus voltage of the Z source network inverter circuit is 2V C -V dc .

[0060] When the IPM module is in the direct zero vector state, a short-circuited bridge arm appears in the IPM module. At this time, when the first switch tube is turned off, the current-conducting diode is turned off due to the reverse voltage. Therefore, the following can be obtained: Figure 6 The equivalent circuit diagram shown is as follows: Figure 6 As shown, the AC power supply module and the rectifier module are disconnected from the X-type impedance network, and the relationship between each inductor and capacitor in the X-type impedance network can be derived (5):

[0061] V L1 =V L2 =V L =V C1 =V C2 =V C (5)

[0062] When the IPM module is in the straight-through zero vector state, the voltages of each inductor and each capacitor in the X-type impedance network are equal. At the same time, in a switching cycle T of the IPM module driven by the PWM modulation signal, s In the example, the running time of the direct zero vector state is T0, and the running time of the non-direct zero vector state is T1, where T s =T1+T0. Based on the inductance in a switching cycle T s The volt-second characteristic is satisfied, so we can get formula (6):

[0063]

[0064] Therefore, by combining equation (4) and equation (6), the average value of the bus voltage of the inverter circuit of the Z source network can be derived. The specific calculation method is shown in the following equation (7):

[0065]

[0066] It can be seen that although the bus voltage of the Z source network inverter circuit is in a switching cycle T s It is not a fixed value, but the average value of the bus voltage of the Z source network inverter circuit is equal to the capacitor voltage of the X-type impedance network. Then, when the IPM module is in a non-through zero vector state, the bus voltage of the Z source network inverter circuit can be converted by combining equation (4) and equation (7), and the relationship (8) is obtained:

[0067]

[0068] Wherein, B is the boost factor, which is related to the direct duty cycle D0. The specific relationship is shown in the following formula (9):

[0069]

[0070] Therefore, through equations (8) and (9), the relationship between the capacitor and the voltage can be transformed to obtain a new relationship between the capacitor and the voltage, as shown in equation (10):

[0071]

[0072] Since the peak value of the fundamental wave of the output phase voltage of the Z source network inverter circuit and the bus voltage of the Z source network inverter circuit satisfy the relationship (11):

[0073]

[0074] Among them, V 1m It is expressed as the peak value of the fundamental wave of the output phase voltage. Then, by combining equation (8) and equation (11), the relationship between the output voltage and input voltage of the Z source network inverter circuit in steady state can be derived. The specific relationship is shown in equation (12):

[0075]

[0076] Therefore, when the IPM module in the Z-source network inverter circuit is in a non-straight-through zero vector state, the bus voltage of the Z-source network inverter circuit is 2V. C -V dc , which can be used for three-phase inverter PWM modulation. At the same time, the IPM module in the Z-source network inverter circuit can operate in the direct zero vector state, at which time the input bus voltage is 0. Therefore, the output voltage of the Z-source network inverter circuit is only affected by its input DC peak voltage, rather than by the input voltage when the IPM module operates in the direct zero vector state. Therefore, the Z-source network inverter circuit can be equivalent to a bus voltage of 2V. C -V dc Three-phase voltage source inverter.

[0077] In a second aspect, an embodiment of the utility model provides a circuit board, comprising the Z-source network inverter circuit as described in the embodiment of the first aspect above.

[0078] According to the circuit board provided by the embodiment of the utility model, a Z-source network inverter circuit is laid on the circuit board, and the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module to provide a DC power supply for the subsequent X-type impedance network and IPM module. At the same time, the AC power module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than the capacitance of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0079] In a third aspect, an embodiment of the utility model provides a controller, comprising the circuit board as described in the embodiment of the second aspect above.

[0080] According to the controller provided by the embodiment of the utility model, a Z-source network inverter circuit is laid on the circuit board set in the controller, and the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module to provide a DC power supply for the subsequent X-type impedance network and IPM module. At the same time, the AC power supply module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than the capacitance of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0081] In a fourth aspect, an embodiment of the utility model provides an air conditioner, comprising the circuit board as described in the embodiment of the second aspect or the controller as described in the embodiment of the third aspect.

[0082] According to the air conditioner provided by the embodiment of the utility model, the air conditioner may include a circuit board or a controller, and the circuit board and the controller are both provided with a Z-source network inverter circuit, the Z-source network inverter circuit converts the connected AC power supply through the rectifier bridge in the rectifier module, and provides a DC power supply for the subsequent X-type impedance network and IPM module, and at the same time, the AC power module is connected to the rectifier bridge through a filter inductor, and the filter inductor can filter the input AC power supply to avoid sudden changes in the input current, so that the rectifier module can output a stable rectified power supply. In addition, the freewheeling capacitor in the rectifier module is a small-capacitance capacitor, and the capacitance of the freewheeling capacitor is smaller than the capacitance of the rectifier circuit in the related art, which can effectively reduce the voltage amplitude at the output end and reduce the voltage stress of the capacitor in the X-type impedance network. At the same time, the freewheeling capacitor can provide a reverse freewheeling current for the circuit when the IPM module is in a non-straight-through zero vector state, avoiding the occurrence of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can stably operate on the AC power supply, and improve the stability of the Z-source network inverter circuit.

[0083] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A Z-source network inverter circuit, characterized in that: include: AC power module, used to connect to AC power; A rectifier module, comprising a filter inductor, a freewheeling capacitor and a rectifier bridge, wherein one output end of the AC power supply module is connected to one input end of the rectifier bridge through the filter inductor, the other input end of the rectifier bridge is connected to the other output end of the AC power supply module, and the two ends of the freewheeling capacitor are correspondingly connected to the two output ends of the rectifier bridge; An X-type impedance network, wherein two input ends of the X-type impedance network are connected to two ends of the freewheeling capacitor; An IPM module, wherein two input terminals of the IPM module are connected to two output terminals of the X-type impedance network, so that when the IPM module is in a non-through zero vector state, the freewheeling capacitor provides a reverse freewheeling current.

2. The Z-source network inverter circuit according to claim 1, characterized in that: The X-type impedance network includes a first inductor, a second inductor, a first capacitor and a second capacitor; one end of the freewheeling capacitor, one end of the first inductor and one end of the first capacitor are connected simultaneously, an input end of the IPM module, the other end of the first inductor and one end of the second capacitor are connected simultaneously, the other input end of the IPM module, the other end of the first capacitor and one end of the second inductor are connected simultaneously, and the other end of the freewheeling capacitor, the other end of the second capacitor and the other end of the second inductor are connected simultaneously.

3. The Z-source network inverter circuit according to claim 2, characterized in that: It also includes a first switch tube for switching the conduction state between the rectifier module and the X-type impedance network, and one end of the freewheeling capacitor is connected to the connection point between the first inductor and the first capacitor through the first switch tube.

4. The Z-source network inverter circuit according to claim 3, characterized in that: It also includes a current guiding diode, wherein a cathode terminal of the current guiding diode is connected to a connection point between the first inductor and the first capacitor, and an anode terminal of the current guiding diode is connected to one end of the freewheeling capacitor.

5. The Z-source network inverter circuit according to claim 2, characterized in that: It also includes a positive DC bus and a negative DC bus, one end of the filter capacitor is connected to the connection point between the first inductor and the first capacitor through the positive DC bus, and the other end of the filter capacitor is connected to the connection point between the second inductor and the second capacitor through the negative DC bus.

6. The Z-source network inverter circuit according to claim 1, characterized in that: The IPM module includes multiple bridge arms connected in parallel, each of which includes an upper bridge arm switch tube, a lower bridge arm switch tube, and a reverse diode connected in parallel with each of the bridge arm switch tubes. The midpoint of each bridge arm is provided with a power supply port for supplying power to a load.

7. The Z-source network inverter circuit according to claim 1, characterized in that: The rectifier bridge includes two rectifier half-bridges connected in parallel, each of the rectifier half-bridges includes two rectifier devices connected in series, one output end of the AC power supply module is connected to the midpoint of one of the rectifier half-bridges through the filter inductor, and the other output end of the AC power supply module is connected to the midpoint of the other rectifier half-bridge.

8. A circuit board, characterized in that: It comprises the Z-source network inverter circuit as claimed in any one of claims 1 to 7.

9. A controller, characterized in that: Comprising the circuit board as claimed in claim 8.

10. An air conditioner, characterized in that: Includes the circuit board as claimed in claim 8 or the controller as claimed in claim 9.

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