An inverter system and a control method thereof

Abstract

The embodiment of the application discloses an inverter system and a control method, the inverter system comprising a direct current power supply, a DC / DC converter, a direct current bus capacitor, a DC / AC converter and a control module, the control module, the input end of the DC / DC converter is linked with the direct current power supply, the output end of the DC / DC converter is connected with the direct current bus capacitor, the input end of the DC / AC converter is connected with the direct current bus capacitor; the control module is electrically connected with the DC / AC converter and the DC / DC converter, by applying a driving signal in the DC / AC converter and the DC / DC converter, the driving voltage wave crest of the DC / AC converter and the DC / DC converter is staggered with each other, the current waveform in the DC / AC converter and the DC / DC converter and the current in the direct current bus capacitor are controlled.

Description

Technical Field

[0001] This application relates to the fields of communication and positioning, and more particularly to an inverter system and its control method. Background Technology

[0002] The inverter system is a crucial component of photovoltaic (PV) power generation modules, converting the direct current (DC) input from the solar panels into alternating current (AC). In existing inverters, significant current ripple is generated in the bus capacitor, causing it to overheat, shortening its lifespan, and affecting inverter operation. Current technologies include hardware modifications such as increasing the bus capacitor or altering the inverter's operating mode to reduce current ripple; however, these methods are costly and can also negatively impact the inverter's functionality.

[0003] Therefore, there is an urgent need to find an inverter system and its control method to reduce the current ripple of the bus capacitor in the inverter and overcome the above problems. Summary of the Invention

[0004] This application provides an inverter system and its control method to reduce the current ripple of the bus capacitor in the inverter.

[0005] To solve the above-mentioned technical problems, the embodiments of this application adopt the following technical solutions:

[0006] First, an inverter system is provided, the inverter system comprising:

[0007] The system includes a DC power supply, a DC / DC converter, a DC bus capacitor, a DC / AC converter, and a control module. The input terminal of the DC / DC converter is connected to the DC power supply, the output terminal of the DC / DC converter is connected to both ends of the DC bus capacitor, and the input terminal of the DC / AC converter is connected to both ends of the DC bus capacitor.

[0008] The control module is electrically connected to the DC / AC converter and the DC / DC converter. By applying a drive signal to the DC / AC converter and the DC / DC converter, the peaks of the drive voltages of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the DC bus capacitor and reducing the current flowing through the DC bus capacitor.

[0009] Optionally, the DC power supply includes multiple high-level output terminals and one low-level output terminal, and the DC / DC converter includes multiple boost groups. Each boost group includes a first switching transistor and a diode. One end of the first switching transistor of each boost group is connected to a high-level output terminal, and the other end is connected to the low-level output terminal. One end of the diode of each boost group is connected to a high-level output terminal, and the other end is connected to the DC / AC converter.

[0010] Optionally, the DC / AC converter is a single-phase type, including a first inverter group and a second inverter group connected in parallel. Each inverter group includes a second switch and a third switch connected in series. One end of the second switch is connected to the current inflow terminal of the DC bus capacitor, and one end of the third switch is connected to the current outflow terminal of the DC bus capacitor. The second switch and the third switch of each inverter group are connected to a conversion node. The conversion node of the first inverter group corresponds to a high-level output terminal and a low-level output terminal. The current passing through the conversion node is converted into the output AC current of the inverter through an inductor and a capacitor.

[0011] Optionally, a level midpoint node is provided between the DC bus capacitors. The DC / AC converter is a three-phase type, comprising three inverter groups. Each inverter group includes a second and a third switch connected in series. One end of the second switch is connected to the current inflow terminal of the DC bus capacitor, and one end of the third switch is connected to the current outflow terminal of the DC bus capacitor. A conversion node is located between the second and third switches in each inverter group. Each inverter group also includes a fourth and a fifth switch connected in series. The fourth switch in each inverter group is connected to the level midpoint node, and the fifth switch is connected to the conversion node. Each conversion node in the inverter group corresponds to a high-level output, and the level midpoint node corresponds to a low-level output. The current passing through the conversion node is converted into the output AC current of the inverter through inductors and capacitors.

[0012] Optionally, the control module controls the operation of the inverter group and the boost group respectively. The control module controls the on / off state of each of the first and second switching transistors. When the first switching transistor is on, the diode is off, the current Id flowing into the first and second inverter groups is 0, and the current Iq flowing into the first switching transistor is not 0. When the first switching transistor is off, the diode is on, the current Id flowing into the first and second inverter groups is not 0, and when the second switching transistor is on, it becomes current Iq' after passing through the second switching transistor and flows into the high-level output terminal from the conversion node.

[0013] Optionally, the control module is a PWM drive module, and the boost group includes a first boost group to an nth boost group. The PWM drive module controls the boost group and the inverter group by controlling the drive signals of the first and second switching transistors. The PWM drive module controls the drive signals of the first boost group to the nth boost group to keep them synchronized, and the drive signals of the first inverter group and the second inverter group to keep them synchronized. The drive signal QV1 of the first boost group and the drive signal QV1' of the first inverter group are staggered by a phase angle of 180 degrees.

[0014] Optionally, the three inverter groups are the A-phase inverter group, the B-phase inverter group, and the C-phase inverter group.

[0015] Optionally, the DC power supply includes two high-level output terminals, the DC / DC converter includes a first boost group and a second boost group corresponding to the two high-level output terminals, the control module is a PWM drive module, the PWM drive module controls the drive signals of the first and second switching transistors, so that the drive signal QV1 of the first boost group and the drive signal QV2 of the second boost group are staggered by 180 degrees phase angle, the drive signal QV1 of the first boost group and the drive signal QV1' of the A-phase inverter group are staggered by 180 degrees phase angle, the drive signal QV2 of the second boost group and the drive signal QV2' of the B-phase inverter group are staggered by 180 degrees phase angle, and the drive signal QV3' of the C-phase inverter group and the drive signal QV2' of the B-phase inverter group are synchronized.

[0016] Optionally, the DC power supply includes n high-level output terminals, and the DC / DC converter includes a first boost group to an nth boost group corresponding to the n high-level output terminals respectively. The PWM drive module controls the drive signals of the first, second, and third switching transistors, so that the drive signal QV(3m+1) of the (3m+1)th boost group, the drive signal QV(3m+2) of the (3m+2)th boost group, and the drive signal QV(3m+3) of the (3m+3)th boost group are... The phase angles of the two phases are staggered by 120 degrees; the driving signal QV(3m+1) of the (3m+1)th boost group and the driving signal QV1' of the A-phase inverter group are staggered by 180 degrees, the driving signal QV(3n+2) of the (3m+2)th boost group and the driving signal QV2' of the B-phase inverter group are staggered by 180 degrees, and the driving signal QV(3m+3) of the (3m+3)th boost group and the driving signal QV3' of the C-phase inverter group are staggered by 180 degrees.

[0017] The present invention also provides a control method for an inverter system, used in the inverter system provided by the present invention, comprising:

[0018] The control module is electrically connected to the DC / AC converter and the DC / DC converter. By applying drive signals to the DC / AC converter and the DC / DC converter, the drive voltage peaks of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the DC bus capacitor.

[0019] Optionally, the DC power supply includes multiple high-level output terminals and one low-level output terminal, the DC / DC converter includes multiple boost converters, the DC / AC converter includes at least two inverters, the control module is a PWM drive module, and the method for controlling the current waveforms in the DC / AC converter and the DC / DC converter includes:

[0020] The PWM drive module samples the DC / AC converter signal to determine whether the DC / AC converter is a single-camera or three-camera type.

[0021] If the DC / AC converter is a single-camera type, the drive signals of the two inverter groups are kept synchronized, and the drive signals of the boost group and the inverter group are staggered by 180 degrees phase angle.

[0022] If the DC / AC converter is a three-phase type, and the inverter groups are three inverter groups connected in parallel, namely the A-phase inverter group, the B-phase inverter group and the C-phase inverter group, then continue to determine the number of high-level output terminals of the DC power supply.

[0023] If the number of high-level output terminals of the DC power supply is 2, and the DC / DC converter includes a first boost group and a second boost group, then the drive signals of the first boost group and the second boost group are staggered by 180 degrees phase angle, the drive signal of the first boost group and the drive signal of the A-phase inverter group are staggered by 180 degrees phase angle, the drive signal of the second boost group and the drive signal of the B-phase inverter group are staggered by 180 degrees phase angle, and the drive signal of the C-phase inverter group is synchronized with the drive signal of the B-phase inverter group.

[0024] If the number of high-level output terminals of the DC power supply is greater than 2, and the DC / DC converter includes the first boost group to the nth boost group, then the drive signals of the (3m+1)th boost group, the (3m+2)th boost group, and the (3m+3)th boost group are staggered by a phase angle of 120 degrees; the drive signal of the (3m+1)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the A-phase inverter group, the drive signal of the (3m+2)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the B-phase inverter group, and the drive signal of the (3m+3)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the C-phase inverter group.

[0025] The above-described technical solutions adopted in the embodiments of this application can achieve the following beneficial effects:

[0026] The control module is electrically connected to the DC / AC converter and the DC / DC converter. By applying a drive signal to the DC / AC converter and the DC / DC converter, the peaks of the drive voltages of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the current in the DC bus capacitor. When the DC / DC converter outputs current to the DC bus capacitor and the DC / AC converter, the staggered drive voltage peaks increase the current flowing into the DC / AC converter and decrease the current flowing into the DC bus capacitor. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of an inverter system provided in an embodiment of this application;

[0029] Figure 2 for Figure 1 A schematic diagram of a single-phase inverter system is shown.

[0030] Figure 3 for Figure 2 The diagram shows the drive signal waveforms of the inverter system.

[0031] Figure 4 for Figure 1 A schematic diagram of a three-phase inverter system is shown.

[0032] Figure 5 for Figure 4 The diagram shows the drive signal waveforms under a single input in the inverter system.

[0033] Figure 6 for Figure 4 The diagram shows the drive signal waveforms under multiple inputs in the inverter system shown.

[0034] Figure 7 A schematic diagram illustrating a control method for an inverter system provided in this application embodiment. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments in this specification clearer, the technical solutions of the embodiments in this specification will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments in this specification, and not all of them. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the embodiments in this specification.

[0036] The technical solutions provided in the various embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0037] refer to Figure 1 The diagram shows a schematic of an inverter system provided in an embodiment of this application. The inverter system in this embodiment includes:

[0038] The system includes a DC power supply 101, a DC / DC converter 102, a DC bus capacitor 103, a DC / AC converter 104, and a control module 106. The input terminal of the DC / DC converter 102 is connected to the DC power supply 101, and the output terminal of the DC / DC converter 102 is connected to both ends of the DC bus capacitor 103. The input terminal of the DC / AC converter 104 is connected to both ends of the DC bus capacitor 103.

[0039] The control module 106 is electrically connected to the DC / AC converter 104 and the DC / DC converter 102. By applying a drive signal to the DC / AC converter 104 and the DC / DC converter 102, the peaks of the drive voltages of the DC / AC converter 104 and the DC / DC converter 102 are staggered, thereby controlling the current waveforms in the DC / AC converter 104 and the DC / DC converter 102.

[0040] When the DC / DC converter 102 outputs current to the DC bus capacitor 103 and the DC / AC converter 104, the current flowing into the DC / AC converter 104 is increased and the current flowing into the DC bus capacitor is reduced because the peaks of the driving voltage are staggered, thus making the inverter of the present invention have a longer service life.

[0041] It should be noted that in this invention, the inverter part of the inverter system, namely the DC / DC converter 102, the DC bus capacitor 103, and the DC / AC converter 104, are all common structures in the prior art, and their connection methods are also common connection methods in the prior art, such as T-type / I-type / full-bridge / half-bridge topologies. This invention does not limit these, and the full-bridge topology is used in this embodiment.

[0042] In this embodiment, the DC power supply 101 is a solar photovoltaic module, and the DC / AC converter 104 is connected to the power grid 105. That is to say, the inverter system in this embodiment is used for current inversion between the solar photovoltaic module and the power grid. The power grid 105 can be an industrial power grid, a household power grid, or a national power grid. However, this invention does not limit the specific application scenario of the inverter system.

[0043] The following is a detailed description of this embodiment with reference to the accompanying drawings. Figure 2 This is a detailed schematic diagram of the inverter system in this embodiment, as shown below. Figure 2 As shown, the inverter in this embodiment is a single-phase inverter, meaning that the DC / AC converter 104 of the inverter outputs single-phase AC power.

[0044] In this embodiment, the DC power supply 101, which is the solar photovoltaic module, includes multiple high-level output terminals PV1 to PVn and a low-level output terminal PV-.

[0045] Reference Figure 1 and Figure 2 The DC / DC converter includes multiple boost groups 201. Each boost group 201 includes a first switching transistor 301 and a diode 302. One end of the first switching transistor 301 of each boost group 201 is connected to a high-level output terminal, and the other end is connected to a low-level output terminal. One end of the diode 302 of each boost group is connected to a high-level output terminal, and the other end is connected to the DC / AC converter 104. In this embodiment, the diodes 302 of all boost groups 201 output current to the DC / AC converter 104 from the same node.

[0046] The DC / AC converter 104 described in this embodiment is a single-camera type DC / AC converter, including a first inverter group 202 and a second inverter group 203 connected in parallel. Each inverter group includes a second switch 303 and a third switch 304 connected in series. One end of the second switch 303 is connected to the current inflow terminal of the DC bus capacitor 103, and one end of the third switch 304 is connected to the current outflow terminal of the DC bus capacitor. There is a conversion node (not labeled) between the second switch 303 and the third switch 304 of each inverter group. The conversion node of the first inverter group corresponds to a high-level output terminal and a low-level output terminal. The current passing through the conversion node is converted into the output AC current of the inverter through an inductor and a capacitor (not labeled).

[0047] In this embodiment, the high-level output terminal of the DC / AC converter 104 corresponds to the L terminal of the power grid 105, and the high-level output terminal of the DC / AC converter 104 corresponds to the N terminal of the power grid 105.

[0048] In this embodiment, the control module 106 controls the operation of the inverter group and the boost group respectively. The control module controls the on / off state of each of the first switch transistors 301 and the second switch transistor 303. When the first switch transistor 301 is on, the diode 302 is off, the current Id flowing into the first inverter group 202 and the second inverter group 203 is 0, and the current Iq flowing into the first switch transistor 301 is not 0. When the first switch transistor 301 is off, the diode 302 is on, the current Id flowing into the first inverter group and the second inverter group is not 0, and when the second switch transistor 303 is on, it becomes a current Iq' after passing through the second switch transistor 303 and flows into the high-level output terminal from the conversion node. Let the currents flowing through the diodes of each boost group be ID1, ID2 to IDn, and the currents flowing through the first switch transistor 301 of each boost group be IQ1' and IQ2', respectively.

[0049] At this time, the current Ic through the DC bus capacitor 103 is Ic = ID1 + ID2 + ... + IDn - (IQ1' + IQ2')

[0050] It can be seen that when the first switch 301 of each boost group is turned off, if the second switch 303 of each inverter group is turned on, the current Id flowing into the first inverter group 202 and the second inverter group 203 will flow directly into the power grid 105 through the second switch 303. At this time, the current Ic through the DC bus capacitor 103 will decrease.

[0051] Therefore, by using a control module to control the gate drive voltages of the first switch 301 and the second switch 303 on the DC / DC converter 102 and the DC / AC converter 104, and adjusting the on / off state of each of the first switch 301 and the second switch 303, the current Ic through the DC bus capacitor 103 can be reduced.

[0052] It should also be noted that in this embodiment, the DC / DC converter 102 is a Boost converter circuit, but the present invention does not limit this.

[0053] In this embodiment, the control module is a PWM drive module.

[0054] The boost converter group includes a first boost converter group to an nth boost converter group. The PWM drive module controls the boost converter group and the inverter group by controlling the drive signals of the first switch 301 and the second switch 303. In this embodiment, for simplicity, the drive signal applied to the first switch 301 is referred to as the drive signal for the boost converter group, and the drive signal applied to the second switch 303 is referred to as the drive signal for the inverter group. In practice, the drive signals for the boost converter group and the inverter group may also include drive signals for other switches. The drive signals of other embodiments in this application can also refer to the description method of this embodiment.

[0055] Please refer to Figure 3 The diagram shows the drive signal waveforms of the inverter system in this embodiment. The horizontal axis represents time, and the vertical axis represents the drive signal voltage value. From top to bottom, the waveforms represent the drive signals for the first boost group to the nth boost group. Some signals are omitted, but QV1, QV2, and QVn, as well as the drive signal QV1' for the first inverter group, are retained. In this embodiment, the PWM drive module controls the drive signals of the first boost group to the nth boost group to remain synchronized, and the drive signals of the first inverter group and the second inverter group to remain synchronized. The drive signals QV1 and QV1' of the first boost group are staggered by a 180-degree phase angle. Through the control of the drive signals, when the first switch 301 is off, if the second switch 303 of each inverter group is on, the current ripple in the DC bus capacitor is reduced. Furthermore, in this embodiment, the drive signals are all between 10kHz and 100kHz, which does not affect the boost operation of the boost group or the inverter output effect of the inverter group. Additionally, the pulse widths of the drive signals for the first boost group to the nth boost group can be unequal. The frequencies are the same, but the pulse widths will differ depending on the input voltage.

[0056] The following is in conjunction with the appendix Figure 4-6 Another example of the present invention will be described. In another embodiment, the inverter of this embodiment is a three-phase inverter, that is, the DC / AC converter 104 of the inverter outputs three-phase alternating current. In this embodiment, the DC / AC converter 104 has a T-type three-level topology. Since the three-phase DC / AC converter 104 is different from the single-phase converter, the differences from the previous embodiment will be described in this embodiment.

[0057] Please refer to Figure 4This is a schematic diagram of a three-camera inverter system in this embodiment. In this embodiment, a level midpoint node (not shown) is provided between the DC bus capacitors 103. The DC / AC converter 104 is a three-phase DC / AC converter, which includes three inverter groups. Each inverter group includes a second switch 303 and a third switch 304 connected in series. One end of the second switch 303 is connected to the current inflow terminal of the DC bus capacitor 103, and one end of the third switch 304 is connected to the current outflow terminal of the DC bus capacitor 103. A conversion node (not shown) is located between the second switch 303 and the third switch 304 of each inverter group. Each inverter group also includes a fourth switch 305 and a fifth switch 306 connected in series. The fourth switch 305 of each inverter group is connected to the level midpoint node, and the fifth switch 306 is connected to the conversion node. The conversion node of each inverter group corresponds to a high-level output, that is, to the L1, L2, and L3 terminals of the power grid 105. The level midpoint node corresponds to a low-level output, which is the N terminal of the power grid 105. The current passing through the conversion node is converted into the three-phase output AC current of the inverter through inductors and capacitors.

[0058] It should be noted that the three-camera DC / AC converter structure in this embodiment is a common structure in the field, and modifications to the DC / AC converter structure in this embodiment do not affect the scope of protection of the invention.

[0059] In this embodiment, the three inverter groups are designated as Phase A inverter group, Phase B inverter group, and Phase C inverter group. The DC power supply 101, i.e., the solar photovoltaic module, includes multiple high-level output terminals PV1 to PVn and one low-level output terminal PV-. To effectively reduce the DC bus capacitor current, the drive signal applied by the PWM drive module differs depending on the number of high-level output terminals of the DC power supply 101. Therefore, when the inverter system is a three-phase type, the PWM drive module must first sample the DC / DC converter signal to determine the number of high-level output terminals in the DC power supply 101.

[0060] Please refer to Figure 4 In conjunction with references Figure 5 , Figure 5This is a waveform diagram of the drive signal under a single input in the inverter system of this embodiment. Based on signal sampling, it is determined that the DC power supply includes two high-level output terminals, namely PV1 and PV2. The DC / DC converter 102 includes a first boost group and a second boost group corresponding to the two high-level output terminals respectively. The control module is calculated to be a PWM drive module. The PWM drive module controls the drive signals of the first switch 301 and the second switch 303, so that the drive signals QV1 and QV2 of the first boost group are staggered by 180 degrees. The drive signals QV1 and QV1' of the first boost group inverter are staggered by 180 degrees, the drive signals QV2 and QV2' of the second boost group inverter are staggered by 180 degrees, and the drive signals QV3' of the C-phase inverter and QV2' of the B-phase inverter are synchronized.

[0061] In this embodiment, the drive signals between each boost group and the three inverter groups are staggered by 180 degrees. When each boost group is working, a portion of the current Id flowing into the three inverter groups flows directly into the power grid 105 through the second switch 303, which can also reduce the current ripple in the DC bus capacitor.

[0062] Please refer to Figure 4 In conjunction with references Figure 6 , Figure 6 This is a waveform diagram of the drive signals under multiple inputs in the inverter system of this embodiment. According to signal sampling, if it is determined that the DC power supply 101 includes n high-level output terminals, i.e., PV1 to PVn, where n is greater than or equal to 3. The DC / DC converter includes a first boost group to the nth boost group corresponding to the n high-level output terminals respectively. The (3m+1)th boost group, the (3m+2)th boost group, and the (3m+3)th boost group represent three adjacent boost groups. The PWM drive module controls the drive signals of the first switch 301 and the second switch 303, so that the drive signal QV(3m+1) of the (3m+1)th boost group, the drive signal QV(3m+2) of the (3m+2)th boost group, and the drive signal QV(3m+3) of the (3m+3)th boost group are... The driving signals QV(3m+3) are staggered by a phase angle of 120 degrees; the driving signal QV(3m+1) of the (3m+1) boost group and the driving signal QV1' of the A-phase inverter group are staggered by a phase angle of 180 degrees, the driving signal QV(3m+2) of the (3m+2) boost group and the driving signal QV2' of the B-phase inverter group are staggered by a phase angle of 180 degrees, and the driving signal QV(3m+3) of the (3m+3) boost group and the driving signal QV3' of the C-phase inverter group are staggered by a phase angle of 180 degrees.

[0063] In the inverter system of this embodiment, the drive signal of each boost group is offset by 180 degrees from the drive signal of at least one inverter group. In this way, when the first switch of a boost group is turned off, the second switch of at least one inverter group will be turned on, so that the inverter system can reduce the current ripple in the DC bus capacitor.

[0064] Furthermore, in this embodiment, since the drive signals QV(3m+2) and QV(3m+3) of the (3m+2) boost group are staggered by 120 degrees, the frequency of the capacitor ripple current can be increased, further reducing the peak value of the ripple current. Therefore, even in single-stage mode, if the boost group in the DC / DC converter is not working and the current directly enters the DC / AC converter, it can still reduce the capacitor ripple current.

[0065] It should be noted that the specific descriptions provided in the two embodiments above correspond to the output operating during the positive half-cycle of the mains power (that is, the ripple of the positive BUS capacitor), while the negative half-cycle corresponds to the negative half-cycle of the mains power (that is, the ripple of the negative BUS capacitor), which is symmetrical to the positive half-cycle.

[0066] Figure 7 The present invention provides a schematic diagram of a control method for an inverter system. The present invention also provides a control method for an inverter system, used in the inverter system provided by the present invention, comprising:

[0067] By applying drive signals to the DC / AC converter and the DC / DC converter, the drive voltage peaks of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the DC bus capacitor.

[0068] refer to Figure 7 The DC power supply includes multiple high-level output terminals and one low-level output terminal; the DC / DC converter includes multiple boost converters; the DC / AC converter includes at least two inverters; the control module is a PWM drive module; and the method for controlling the current waveforms in the DC / AC converter and the DC / DC converter in this embodiment includes:

[0069] In step S1, the PWM drive module samples the DC / AC converter signal and determines whether the DC / AC converter is a single-camera or three-camera type.

[0070] If the DC / AC converter is a single-camera type, execute step S21 to control the drive signals of the two inverter groups to keep them synchronized, and the drive signals of the boost group and the inverter group are staggered by 180 degrees phase angle.

[0071] If the DC / AC converter is a three-phase type, and the inverter groups are three inverter groups connected in parallel, namely the A-phase inverter group, the B-phase inverter group, and the C-phase inverter group, then in step S22, the number of high-level output terminals of the DC power supply is determined.

[0072] If the DC power supply 101 has two high-level output terminals, step S31 is executed. The DC / DC converter 102 includes a first boost group and a second boost group. The drive signals of the first boost group and the second boost group are staggered by 180 degrees phase angle. The drive signals of the first boost group and the A-phase inverter group are staggered by 180 degrees phase angle. The drive signals of the second boost group and the B-phase inverter group are staggered by 180 degrees phase angle. The drive signals of the C-phase inverter group and the B-phase inverter group are synchronized.

[0073] If the number of high-level output terminals of the DC power supply is greater than 2, execute step S32. The DC / DC converter 102 includes a first boost group to an nth boost group. Then, the drive signals of the (3m+1)th boost group, the (3m+2)th boost group, and the (3m+1)th boost group are staggered by a phase angle of 120 degrees; the drive signals of the (3m+1)th boost group and the A-phase inverter group are staggered by a phase angle of 180 degrees; the drive signals of the (3m+2)th boost group and the B-phase inverter group are staggered by a phase angle of 180 degrees; and the drive signals of the (3m+3)th boost group and the C-phase inverter group are staggered by a phase angle of 180 degrees.

[0074] According to the control method of this embodiment, when the DC / DC converter outputs current to the DC bus capacitor and the DC / AC converter, the current flowing into the DC / AC converter can be increased and the current flowing into the DC bus capacitor can be reduced because the driving voltage peaks are staggered, thus making the inverter of the present invention have a longer service life.

[0075] The above description is merely a preferred embodiment of the embodiments in this specification and is not intended to limit the scope of protection of the embodiments in this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments in this specification should be included within the scope of protection of the embodiments in this specification.

[0076] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0077] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0078] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0079] The embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. An inverter system characterized by comprising: include: The system includes a DC power supply, a DC / DC converter, a DC bus capacitor, a DC / AC converter, and a control module. The input terminal of the DC / DC converter is connected to the DC power supply, the output terminal of the DC / DC converter is connected to both ends of the DC bus capacitor, and the input terminal of the DC / AC converter is connected to both ends of the DC bus capacitor. The control module is electrically connected to the DC / AC converter and the DC / DC converter. By applying a drive signal to the DC / AC converter and the DC / DC converter, the drive voltage peaks of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the DC bus capacitor and reducing the current flowing through the DC bus capacitor. The DC power supply includes multiple high-level output terminals and one low-level output terminal. The DC / DC converter includes multiple boost groups. Each boost group includes a first switching transistor and a diode. One end of the first switching transistor of each boost group is connected to a high-level output terminal, and the other end is connected to the low-level output terminal. One end of the diode of each boost group is connected to a high-level output terminal, and the other end is connected to the DC / AC converter. The DC / AC converter is a single-phase type, including a first inverter group and a second inverter group connected in parallel. Each inverter group includes a second switch and a third switch connected in series. One end of the second switch is connected to the current inflow terminal of the DC bus capacitor, and one end of the third switch is connected to the current outflow terminal of the DC bus capacitor. The second switch and the third switch of each inverter group are connected to a conversion node. The conversion node of the first inverter group corresponds to a high-level output terminal and a low-level output terminal. The current passing through the conversion node is converted into the output AC current of the inverter through an inductor and a capacitor. The control module controls the operation of the inverter group and the boost group respectively. The control module controls the on / off state of each first and second switch. When the first switch is turned on, the diode is turned off, the current Id flowing into the first and second inverter groups is 0, and the current Iq flowing into the first switch is not 0. When the first switch is turned off, the diode is turned on, the current Id flowing into the first and second inverter groups is not 0, and when the second switch is turned on, it becomes current Iq' after passing through the second switch and flows into the high-level output terminal from the conversion node. The control module is a PWM drive module. The boost group includes a first boost group to an nth boost group. The PWM drive module controls the boost group and the inverter group by controlling the drive signals of the first and second switching transistors. The PWM drive module controls the drive signals of the first boost group to the nth boost group to keep them synchronized. The drive signals of the first inverter group and the second inverter group to keep them synchronized. The drive signal QV1 of the first boost group and the drive signal QV1' of the first inverter group are staggered by a phase angle of 180 degrees.

2. The inverter system according to claim 1, characterized in that, A level neutral node is provided between the DC bus capacitors. The DC / AC converter is a three-phase type, comprising three inverter groups. Each inverter group includes a second and a third switch connected in series. One end of the second switch is connected to the current inflow terminal of the DC bus capacitor, and one end of the third switch is connected to the current outflow terminal of the DC bus capacitor. A conversion node is located between the second and third switches in each inverter group. Each inverter group also includes a fourth and a fifth switch connected in series. The fourth switch in each inverter group is connected to the level neutral node, and the fifth switch is connected to the conversion node. Each conversion node in the inverter group corresponds to a high-level output, and the level neutral node corresponds to a low-level output. The current passing through the conversion node is converted into the output AC current of the inverter through inductors and capacitors.

3. The inverter system according to claim 2, characterized in that, The three inverter groups are the A-phase inverter group, the B-phase inverter group, and the C-phase inverter group.

4. The inverter system according to claim 3, characterized in that, The DC power supply includes two high-level output terminals. The DC / DC converter includes a first boost group and a second boost group corresponding to the two high-level output terminals. The control module is a PWM drive module. The PWM drive module controls the drive signals of the first and second switching transistors, so that the drive signals QV1 and QV2 of the first boost group are staggered by 180 degrees. The drive signals QV1 and QV1' of the first boost group and QV2' of the A-phase inverter group are staggered by 180 degrees. The drive signals QV2 and QV2' of the second boost group and QV2' of the B-phase inverter group are staggered by 180 degrees. The drive signals QV3' of the C-phase inverter group and QV2' of the B-phase inverter group are synchronized.

5. The inverter system according to claim 4, characterized in that, The DC power supply includes n high-level output terminals. The DC / DC converter includes a first boost group to the nth boost group, each corresponding to one of the n high-level output terminals. The PWM drive module controls the drive signals of the first, second, and third switching transistors, such that the drive signal QV(3m+1) of the (3m+1)th boost group, the drive signal QV(3m+2) of the (3m+2)th boost group, and the drive signal QV(3m+3) of the (3m+3)th boost group are mutually... The phase angles are staggered by 120 degrees; the drive signal QV(3m+1) of the (3m+1)th boost group and the drive signal QV1' of the A-phase inverter group are staggered by 180 degrees, the drive signal QV(3m+2) of the (3m+2)th boost group and the drive signal QV2' of the B-phase inverter group are staggered by 180 degrees, and the drive signal QV(3m+3) of the (3m+3)th boost group and the drive signal QV3' of the C-phase inverter group are staggered by 180 degrees.

6. A control method for an inverter system, used to control the inverter system as described in any one of claims 1-5, characterized in that, include: By applying drive signals to the DC / AC converter and the DC / DC converter, the drive voltage peaks of the DC / AC converter and the DC / DC converter are staggered, thereby controlling the current waveforms in the DC / AC converter and the DC bus capacitor, and reducing the current flowing through the DC bus capacitor.

7. The control method according to claim 6, characterized in that, The DC power supply includes multiple high-level output terminals and one low-level output terminal; the DC / DC converter includes multiple boost converters; the DC / AC converter includes at least two inverters; the control module is a PWM drive module; and the method for controlling the current waveforms in the DC / AC converter and the DC / DC converter includes: The PWM drive module samples the DC / AC converter signal to determine whether the DC / AC converter is a single-camera or three-camera type. If the DC / AC converter is a single-camera type, the drive signals of the two inverter groups are kept synchronized, and the drive signals of the boost group and the inverter group are staggered by 180 degrees phase angle. If the DC / AC converter is a three-phase type, and the inverter groups are three inverter groups connected in parallel, namely the A-phase inverter group, the B-phase inverter group and the C-phase inverter group, then continue to determine the number of high-level output terminals of the DC power supply. If the number of high-level output terminals of the DC power supply is 2, and the DC / DC converter includes a first boost group and a second boost group, then the drive signals of the first boost group and the second boost group are staggered by 180 degrees phase angle, the drive signal of the first boost group and the drive signal of the A-phase inverter group are staggered by 180 degrees phase angle, the drive signal of the second boost group and the drive signal of the B-phase inverter group are staggered by 180 degrees phase angle, and the drive signal of the C-phase inverter group is synchronized with the drive signal of the B-phase inverter group. If the number of high-level output terminals of the DC power supply is greater than 2, and the DC / DC converter includes the first boost group to the nth boost group, then the drive signals of the (3m+1)th boost group, the (3m+2)th boost group, and the (3m+3)th boost group are staggered by a phase angle of 120 degrees; the drive signal of the (3m+1)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the A-phase inverter group, the drive signal of the (3m+2)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the B-phase inverter group, and the drive signal of the (3m+3)th boost group is staggered by a phase angle of 180 degrees from the drive signal of the C-phase inverter group.

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