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 rectifier bridge and a follow current capacitor. The two input ends of the rectifier bridge are correspondingly connected with the two output ends of the alternating current power supply module, and the follow current capacitor is connected to the two output ends of the rectifier bridge; one end of the X-type impedance network is connected with one end of the follow current capacitor, one input end of the IPM module is connected with the other end of the X-type impedance network, and the other input end of the IPM module is connected with the other end of the follow current capacitor, 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 be suitable for the power supply condition of an alternating current power supply, and effectively reduces the voltage stress of a capacitor in an X-type impedance network at the same time.

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. However, after the DC link peak voltage is increased, the voltage stress of the capacitor in the X-type impedance network is large, which is easy to damage the capacitor in the X-type impedance network. 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 be suitable for AC power supply and effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[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 rectifier bridge and a freewheeling capacitor, wherein two input ends of the rectifier bridge are correspondingly connected to two output ends of the AC power supply module, and the freewheeling capacitor is connected to two output ends of the rectifier bridge;

[0007] An X-type impedance network, one end of which is connected to one end of the freewheeling capacitor;

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

[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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[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 is simultaneously connected to one end of the first inductor and the cathode end of the first capacitor, the other end of the first inductor is connected to the cathode end of the second capacitor, the anode end of the first capacitor is connected to one end of the second inductor, and an input end of the IPM module is simultaneously connected to the anode end of the second capacitor and the other end of the second inductor.

[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 direction of current flow in the X-type impedance network, one end of the first switch tube is connected to the connection point between the first inductor and the second capacitor, and the other end of the first switch tube is connected to the connection point between the second inductor and the first capacitor.

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

[0013] In the Z-source network inverter circuit provided in the embodiment of the utility model, the rectifier module further includes an input inductor, and an output end of the AC power supply module is connected to an input end of the rectifier bridge through the input inductor.

[0014] In the Z-source network inverter circuit provided in an embodiment of the utility model, one end of the freewheeling capacitor is connected to one end of the X-type impedance network through a positive DC bus, and the other end of the freewheeling capacitor is connected to the other input end of the IPM module through a negative DC bus.

[0015] In the Z-source network inverter circuit provided in an embodiment of the utility model, one end of the freewheeling capacitor is connected to one end of the X-type impedance network through a negative DC bus, and the other end of the freewheeling capacitor is connected to the other input end of the IPM module through a positive DC bus.

[0016] 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 input inductor, and the other output end of the AC power supply module is connected to the midpoint of the other rectifier half-bridge.

[0017] 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.

[0018] 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.

[0019] 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0020] 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.

[0021] 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 provided 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0022] 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.

[0023] The air conditioner provided by 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using AC power, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0024] 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

[0025] 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.

[0026] The utility model is further described below in conjunction with the accompanying drawings and embodiments;

[0027] Figure 1 It is a circuit structure diagram of a Z-source network inverter circuit provided by an embodiment of the utility model;

[0028] Figure 2 It is a schematic diagram of a partial topological structure of a Z-source network inverter circuit provided by an embodiment of the utility model;

[0029] Figure 3 It is an equivalent circuit diagram of a Z source network inverter circuit when the IPM module provided by the embodiment of the utility model is in a straight-through zero vector state;

[0030] Figure 4 It is an equivalent circuit diagram of a 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;

[0031] Figure 5 It is a schematic diagram of the topological structure of a parallel inverter circuit in the related art;

[0032] Figure 6 This is a schematic diagram of the capacitor voltage comparison effect provided by the embodiment of the utility model;

[0033] Figure 7 It is a circuit connection diagram of a Z-source network inverter circuit provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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. However, after the DC link peak voltage is increased, the voltage stress of the capacitor in the X-type impedance network is large, which is easy to damage the capacitor in the X-type impedance network. At the same time, since the use of AC power as the input power supply cannot provide a stable DC link voltage for the X-type impedance network, the stability of the Z-source network inverter circuit is affected.

[0039] 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, which converts the connected AC power supply through the rectifier bridge in the rectifier module to provide a DC power supply for the X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using AC power, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0040] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings.

[0041] Reference Figure 1 , Figure 1 It 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 the AC power supply as the power supply of 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 an input terminal of a rectifier bridge, and the other output terminal is connected to the other input terminal of the rectifier bridge, so that the rectifier bridge can rectify and convert the AC power 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 Cdc, the X-type impedance network and the IPM module of the subsequent stage. In addition to the rectifier bridge, the rectifier module also includes a freewheeling capacitor Cdc. The freewheeling capacitor Cdc is a small-capacitance capacitor. Compared with the filter capacitor used in the rectifier circuit of the related technology, the freewheeling capacitor Cdc is different. The capacitance of the freewheeling capacitor Cdc is smaller and the main function of the freewheeling capacitor Cdc 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.

[0042] One end of the X-type impedance network is connected to one end of the freewheeling capacitor Cdc, and one input end of the IPM module is connected to the other end of the freewheeling capacitor Cdc. At the same time, the other end of the X-type impedance network is connected to the other input end of the IPM module, so that the X-type impedance network, the IPM module and the rectifier module are connected in series. The circuit structure of the three connected in series can effectively reduce the voltage stress of the capacitor in the X-type impedance network compared to the circuit structure of the X-type impedance network, the IPM module and the power access module connected in parallel in the related art, thereby effectively avoiding the damage of the capacitor in the X-type impedance network due to excessive voltage stress of the capacitor in the X-type impedance network after the DC link voltage is boosted, thereby improving the stability of the circuit.

[0043] 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.

[0044] Reference Figure 2 , Figure 2 It 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 Cdc and the cathode end of the first capacitor C1, the other end of the first inductor L1 is connected to the cathode end of the second capacitor C2, one end of the second inductor L2 is connected to the anode end of the first capacitor C1, and the other end of the second inductor L2 is simultaneously connected to an input end of the IPM module and the anode end of the second capacitor C2.

[0045] 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.

[0046] Among them, the switching state of each switch tube in the IPM module can be controlled by the PWM modulation signal, thereby driving the IPM module to generate different voltage vectors to control the operation of the load (compressor), wherein these voltage vectors include zero vectors and non-zero vectors, zero vectors refer to voltage vectors that do not generate voltage, and non-zero vectors refer to voltage vectors that can generate specific voltages and phases, and non-zero vectors can drive the compressor to generate torque operation, and 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 straight-through zero vector state, that is, the IPM module can generate a straight-through zero vector voltage vector at this time, and the straight-through 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 the short circuit of the bridge arm in 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.

[0047] Therefore, by changing the PWM modulation signal to drive the IPM module, the first inductor L1, the second inductor L2, the first capacitor C1 and the second capacitor C2 can store electric energy, increase the output voltage of the X-type impedance network, and make 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. It should be noted that a diode is also provided in the X-type impedance network, the anode end of the diode is connected to the connection point of the first inductor L1 and the second capacitor C2, and the cathode end of the diode is connected to the connection point of the second inductor L2 and the first capacitor C1.

[0048] like Figure 2As shown, the AC power supply module and the rectifier module are integrated as a DC power supply providing a DC voltage V0, and the positive terminal of the rectifier module is connected to an input terminal of the IPM module, which is equivalent to one end of the freewheeling capacitor Cdc being connected to the positive input terminal of the IPM module (the input terminal of the first upper bridge arm switch tube) through the positive DC bus; and the negative terminal of the rectifier module is connected to one end of the X-type impedance network, which is equivalent to the other end of the freewheeling capacitor Cdc being connected to one end of the X-type impedance network (the connection point of the second inductor L2 and the second capacitor C2) through the negative DC bus; at the same time, the other input terminal of the IPM module is connected to the other end of the X-type impedance network, which is equivalent to the negative input terminal of the IPM module (the output terminal of the first lower bridge arm switch tube) and the other end of the X-type impedance network (the connection point of the first inductor L1 and the first capacitor C1). Therefore, the DC power supply, the X-type impedance network and the IPM module are integrated as a series Z-source network inverter circuit in which the three are connected in series. Assuming that the inductance of the first inductor L1 is the same as that of the second inductor L2, and the capacitance of the first capacitor C1 is the same as that of the second capacitor C2, then the relationship (1) can be obtained:

[0049] V L1 =V L2 =V L ,V C1 =V C2 =V C (1)

[0050] 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.

[0051] When the IPM module is in the straight-through zero vector state, a short-circuited bridge arm appears in the IPM module. Therefore, the following can be obtained: Figure 3 The equivalent circuit diagram shown. The AC power supply module and the rectifier module are integrated as a DC power supply that can provide a DC voltage V0. The DC current provided flows through the first inductor L1 and the diode in sequence, and then is divided into two currents. One current flows through the first capacitor C1 and then returns to the first inductor L1. After converging with the DC current initially provided by the DC power supply, it flows to the first inductor L1, while the other current flows to the second inductor L2. The current flowing through the second inductor L2 will be divided into two currents again. One current flows to the negative terminal of the DC power supply, and the other current flows through the second capacitor C2, and after converging with the current flowing through the first inductor L1, it returns to the second inductor L2. Therefore, the relationship (2) can be obtained:

[0052] V L =V0+V C (2)

[0053] It can be seen that the voltage V across the first inductor L1 L is equal to the DC voltage V0 and the voltage V across the first capacitor C1 C The sum of the voltage V across the second inductor L2 is L is equal to the DC voltage V0 and the voltage V across the second capacitor C2 C sum.

[0054] When the IPM module is in a non-zero vector state, the IPM module can provide output power V to the load. i , then you can Figure 4 As shown, the IPM module can be regarded as a reverse current source V i , providing a voltage opposite to the DC power supply considered as the integration of the AC power module and the rectifier module. When the IPM module is in a non-straight-through zero vector state, that is, a zero vector state, the IPM module cannot provide output power to the load. At this time, it can be regarded as providing a power supply with a current value of zero. Therefore, the relationship (3) can be derived:

[0055] V L =-V C (3)

[0056] It can be seen that when the IPM module is in a non-straight-through zero vector state, the AC power module, the rectifier module and the IPM module are regarded as input power with a zero current value. Therefore, at this time, the voltage V across the first inductor L1 is L The voltage V across the first capacitor C1 C On the contrary, the voltage V across the second inductor L2 is L The voltage V across the second capacitor C2 C on the contrary.

[0057] In addition, according to the volt-second principle of the first inductor L1 and the second inductor L2, the average value of the voltage across the first inductor L1 and the second inductor L2 in a switching cycle of the PWM modulation signal driving the IPM module is zero. Therefore, the relationship (4) can be derived:

[0058]

[0059] Where D0 refers to the duty cycle of the direct zero vector in the PWM modulation signal within a switching cycle, that is, the direct duty cycle. It can be seen that when the direct duty cycle is 0, the voltage V between the capacitors in the X-type impedance network, that is, the first capacitor C1 and the second capacitor C2, is C Therefore, by gradually increasing the through duty cycle, the voltage V of the first capacitor C1 and the second capacitor C2 can be CIt also gradually increases, so that the soft start of the Z source network inverter circuit can be realized, the voltage stress of the capacitor in the X-type impedance network can be reduced, and the reliability of the Z source network inverter circuit can be improved. At this time, the DC link voltage and peak output phase voltage of the Z source network inverter circuit can be expressed by the following equations (5) and (6):

[0060]

[0061]

[0062] Among them, V PN Represents the DC link voltage of the Z-source inverter circuit, V P It is represented by the peak output phase voltage, B represents the boost factor determined by the direct duty cycle, and B ≥ 1, and M represents the modulation ratio, that is, the amplitude V of the output voltage of the IPM module i The relationship between the maximum output voltage amplitude that the IPM module can provide.

[0063] In the related art, a parallel inverter circuit is formed by connecting a DC power supply, an X-type impedance network and an IPM module in sequence, and the two output ends of the DC power supply are connected to the two input ends of the X-type impedance network, and the two output ends of the X-type impedance network are connected to the two input ends of the IPM module. The two output ends of the IPM module can provide inverted power for the subsequent load. By changing the PWM modulation signal to drive the IPM module, the output voltage of the two output ends of the X-type impedance network can be changed. For example, by adjusting the direct-pass duty cycle, the PWM modulation signal carrying the direct-pass zero vector drives the IPM module, so that the IPM module is in a direct-pass zero vector state, that is, any bridge arm in the IPM module is direct-passed, thereby increasing the output voltage of the X-type impedance network, that is, increasing the DC link voltage. Figure 5 As shown, the DC power supply of the parallel inverter circuit in the related art can provide a DC voltage V′0, so that the DC link voltage of the parallel inverter circuit can be derived as shown in the following formula (7):

[0064]

[0065] Among them, V′ PN It is represented as the DC link voltage of the parallel inverter circuit, and B′ is represented as the boost factor, which can be determined by the direct duty cycle D0. At this time, by comparing formula (5) with formula (7), it can be seen that the voltage boost effect of the Z source network inverter circuit provided by the embodiment of the utility model is the same as the voltage boost effect of the parallel inverter circuit in the related art.

[0066] Next, in the related art, the two capacitors of the X-type impedance network of the parallel inverter circuit are the same, so it can be deduced that the capacitor voltage of the X-type impedance network is as shown in formula (8):

[0067]

[0068] Among them, V′ C The capacitor voltage of the X-type impedance network of the parallel inverter circuit is represented. Since the pass-through duty cycle will not be greater than 0.5, the capacitor voltage of the X-type impedance network of the parallel inverter circuit will be greater than the input voltage of the parallel inverter circuit. Therefore, the voltage stress of the capacitor of the X-type impedance network of the parallel inverter circuit is large, which is easy to damage the capacitor. By comparing formula (8) with formula (4), it can be seen that when maintaining the same voltage boost, the voltage stress of the capacitor of the X-type impedance network inverter circuit in the Z-source network inverter circuit provided in the embodiment of the utility model is less than the voltage stress of the capacitor of the X-type impedance network of the parallel inverter circuit. Specifically, you can refer to Figure 6 , Figure 6 It is a comparison effect diagram of the capacitor voltage of the X-type impedance network in the Z-source network inverter circuit provided by the embodiment of the utility model and the capacitor voltage of the X-type impedance network in the parallel inverter circuit in the related art. It can be seen that when the direct duty cycle D0 is zero, the capacitor voltage of the X-type impedance network in the Z-source network inverter circuit provided by the embodiment of the utility model is zero, while the capacitor voltage of the X-type impedance network in the parallel inverter circuit in the related art is equal to the input voltage; as the direct duty cycle D0 continues to increase, the capacitor voltage of the X-type impedance network in the parallel inverter circuit in the related art is always higher than the capacitor voltage of the X-type impedance network in the Z-source network inverter circuit provided by the embodiment of the utility model. Therefore, the Z-source network inverter circuit provided by the embodiment of the utility model, compared with the parallel inverter circuit in the related art, can effectively reduce the voltage stress of the capacitor in the X-type impedance network and improve the safety and reliability of the circuit. At the same time, the Z-source network inverter circuit provided by the embodiment of the utility model can use capacitors with smaller capacitance in the X-type impedance network, thereby reducing the circuit cost.

[0069] Reference Figure 7 , Figure 7It is a circuit connection diagram of the Z source network inverter circuit provided by the embodiment of the utility model. It can be seen that the Z source network inverter circuit also includes a first switch tube K, one end of the first switch tube K is connected to the connection point of the first inductor L1 and the second capacitor C2, and the other end of the first switch tube K is connected to the connection point of the second inductor L2 and the first capacitor C1. Among them, the first switch tube K can switch the current flow direction in the X-type impedance network. When the first switch tube K is in the on state, the current in the X-type impedance network can flow from the connection point of the second inductor L2 and the first capacitor C1 to the connection point of the first inductor L1 and the second capacitor C2, that is, the current in the X-type impedance network can flow from the second inductor L2 to the first inductor L1 in reverse, realizing reverse current conduction. When the first switch tube K is in the off state, the current in the X-type impedance network cannot flow from the second inductor L2 to the first inductor L1 in reverse, that is, the flow of reverse current in the X-type impedance network is prohibited.

[0070] 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 K, which is equivalent to the anode end of the guide diode being connected to the connection point between the first inductor L1 and the second capacitor C2, and the cathode end being connected to the connection point between the second inductor L2 and the first capacitor C1. At this time, due to the setting of the guide diode, when the first switch tube K is in the cut-off state, the current in the X-type impedance network can only flow from the connection point between the first inductor L1 and the second capacitor C2 to the connection point between the second inductor L2 and the first capacitor C1, that is, the current in the X-type impedance network can only flow from the first inductor L1 to the second inductor L2. When the first switch tube K is in the on state, the current in the X-type impedance network can flow bidirectionally between the first inductor L1 and the second inductor L2.

[0071] It can be understood that the rectifier module also includes an input inductor Lin, one end of the input inductor Lin can be connected to an output end of the AC power supply module, and the other end of the input inductor Lin is connected to an input end of the rectifier bridge. Therefore, after the AC power supply module is connected to the AC power supply, it will flow through the input inductor Lin for filtering, and then flow to the rectifier bridge, thereby avoiding sudden changes in the input current and making the current flowing to the next stage more stable.

[0072] It can be understood that one end of the freewheeling capacitor Cdc can be connected to the X-type impedance network through the positive DC bus, and the other end is connected to the IPM module through the negative DC bus, which is equivalent to Figure 7 As shown, the rectified DC current flows to the X-type impedance network and the IPM module in sequence.

[0073] It can be understood that one end of the freewheeling capacitor Cdc can be connected to the X-type impedance network through the negative DC bus, and the other end is connected to the IPM module through the positive DC bus, which is equivalent to Figure 2As shown, the rectified DC current flows to the IPM module and the X-type impedance network in sequence.

[0074] 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 an input inductor Lin, 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.

[0075] 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.

[0076] 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using AC power, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0077] 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.

[0078] 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using AC power, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0079] 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.

[0080] 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 X-type impedance network and the IPM module of the subsequent stage, and the rectifier module, the X-type impedance network and the IPM module are connected in series, which can effectively reduce the voltage stress of the capacitor in the X-type impedance network. 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, and the freewheeling capacitor as the output end of the rectifier module can effectively reduce the voltage amplitude of 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 situation of intermittent input current when using an AC power supply, so that the Z-source network inverter circuit can be suitable for the situation of AC power supply, and can also effectively reduce the voltage stress of the capacitor in the X-type impedance network.

[0081] 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 rectifier bridge and a freewheeling capacitor, wherein two input ends of the rectifier bridge are correspondingly connected to two output ends of the AC power supply module, and the freewheeling capacitor is connected to two output ends of the rectifier bridge; An X-type impedance network, one end of which is connected to one end of the freewheeling capacitor; An IPM module, wherein one input end of the IPM module is connected to the other end of the X-type impedance network, and the other input end is connected to the other end of the freewheeling capacitor, so that the freewheeling capacitor provides a reverse freewheeling current when the IPM module is in a non-through zero vector state.

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 is simultaneously connected to one end of the first inductor and the cathode end of the first capacitor, the other end of the first inductor is connected to the cathode end of the second capacitor, the anode end of the first capacitor is connected to one end of the second inductor, and an input end of the IPM module is simultaneously connected to the anode end of the second capacitor and the other end of the second inductor.

3. The Z-source network inverter circuit according to claim 2, characterized in that: It also includes a first switch tube for switching the direction of current flow in the X-type impedance network, one end of the first switch tube is connected to the connection point between the first inductor and the second capacitor, and the other end of the first switch tube is connected to the connection point between the second inductor and the first capacitor.

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

5. The Z-source network inverter circuit according to claim 1, characterized in that: The rectifier module further includes an input inductor, and an output end of the AC power supply module is connected to an input end of the rectifier bridge through the input inductor.

6. The Z-source network inverter circuit according to claim 1, characterized in that: One end of the freewheeling capacitor is connected to one end of the X-type impedance network through a positive DC bus, and the other end of the freewheeling capacitor is connected to the other input end of the IPM module through a negative DC bus.

7. The Z-source network inverter circuit according to claim 1, characterized in that: One end of the freewheeling capacitor is connected to one end of the X-type impedance network through a negative DC bus, and the other end of the freewheeling capacitor is connected to the other input end of the IPM module through a positive DC bus.

8. The Z-source network inverter circuit according to claim 5, 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 input inductor, and the other output end of the AC power supply module is connected to the midpoint of the other rectifier half-bridge.

9. 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.

10. A circuit board, characterized in that: It comprises the Z-source network inverter circuit as claimed in any one of claims 1 to 9.

11. A controller, characterized in that: Comprising the circuit board as claimed in claim 10.

12. An air conditioner, characterized in that: Includes the circuit board as claimed in claim 10 or the controller as claimed in claim 11.

Images