Buck-Boost Three-Phase Inverter Control Device and Control Method

Abstract

The present invention discloses a buck-boost three-phase inverter control device and a control method. The control device includes a buck-boost three-phase inverter and a control driving unit. The buck-boost three-phase inverter includes a filter capacitor, an input power supply, a filter inductor, a load, and a switching tube driving circuit composed of a plurality of switching tubes and diodes. Among them, the filter capacitor, the input power supply, the filter inductor, the load, the plurality of switching tubes, and the diodes form a plurality of closed loops and freewheeling loops. The control driving unit is used to collect the voltage feedback signals of the filter capacitor and the load, the negative half-cycle bus voltage signal output from the negative half-cycle bus output terminal, and the current feedback signal of the filter inductor, and perform on-off control on the plurality of switching tubes according to the above signals to connect each closed loop and freewheeling loop for load voltage regulation control. The present invention can eliminate the common-mode leakage current phenomenon, and solve the problems that the traditional inverter cannot achieve buck-boost transformation and the problem of bridge arm short-circuiting.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter control, and particularly to a buck-boost three-phase inverter control device and a control method. Background Art

[0002] Facing the increasingly severe challenges of the climate crisis, it has become inevitable to vigorously develop new energy power.

[0003] Inverters are an important part of power generation systems. Traditional non-isolated inverters have the advantages of light weight, low cost, and high efficiency. However, the traditional non-isolated inverter topology will generate common-mode leakage current and electromagnetic interference, endangering personal safety; moreover, traditional inverters have the problem of shoot-through of the bridge arm, damaging equipment components, and greatly reducing the reliability of inverter operation; in addition, if the voltage of the input power supply is low, it will cause the inverter to fail to operate, and thus it is required that the non-isolated inverter can achieve the function of buck-boost conversion.

[0004] Therefore, traditional non-isolated inverters cannot fundamentally eliminate common-mode leakage current, solve the problem of shoot-through of the bridge arm, and achieve the function of buck-boost conversion, and there is also a lack of a control device and a control method for inverters that can achieve the above functions. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, the first object of the present invention is to provide a buck-boost three-phase inverter control device to eliminate the phenomenon of common-mode leakage current and solve the problems of the traditional inverter that cannot achieve buck-boost conversion and the problem of shoot-through of the bridge arm.

[0006] The second object of the present invention is to provide a buck-boost three-phase inverter control method.

[0007] To achieve the above object, the present invention is realized by the following technical solutions:

[0008] A buck-boost three-phase inverter control device includes:

[0009] A buck-boost three-phase inverter, the buck-boost three-phase inverter includes a filter capacitor, an input power supply, a filter inductor, a load, and a switch tube driving circuit composed of a plurality of switch tubes and a plurality of diodes. Among them, the filter capacitor, the input power supply, the filter inductor, the load, the plurality of switch tubes, and the diodes form a plurality of closed loops and freewheeling loops;

[0010] A control and drive unit, the input end of the control and drive unit is connected to the filter capacitor, the filter inductor, the load and the negative half-cycle bus output end of the input power supply, the output end of the control and drive unit is connected to the control ends of a plurality of the switching tubes, the control and drive unit is used to collect the voltage feedback signal of the filter capacitor, the load, the negative half-cycle bus voltage signal output by the negative half-cycle bus output end and the current feedback signal of the filter inductor, and perform on-off control on the plurality of the switching tubes according to the voltage feedback signal, the negative half-cycle bus voltage signal and the current feedback signal, so as to connect each closed loop and freewheeling loop to perform load voltage regulation control.

[0011] Optionally, the buck-boost three-phase inverter specifically includes: the input power supply, first to eighth filter inductors, first to eighth switching tubes, first to ninth diodes, first to fifth filter capacitors, first to third loads; the first end of the second filter capacitor, the drain of the second switching tube, the positive output terminal of the input power supply, the first end of the first filter inductor, and the anode of the ninth diode are connected; the cathodes of the first diode, the fourth diode, the sixth diode, the eighth diode, the ninth diode, the drain of the third switching tube, the fifth switching tube, the seventh switching tube, and the first end of the first filter capacitor are connected; the anodes of the second diode, the third diode, the fifth diode, the seventh diode, the source of the fourth switching tube, the sixth switching tube, the eighth switching tube, and the second end of the second filter capacitor are connected; the source of the second switching tube, the cathode of the second diode, and the first end of the second filter inductor are connected; the second end of the first filter inductor, the drain of the first switching tube, and the anode of the first diode are connected; the third filter capacitor is connected in parallel with the first load, the fourth filter capacitor is connected in parallel with the second load, the fifth filter capacitor is connected in parallel with the third load, the second ends of the first load, the second load, the third load, the second end of the first filter capacitor, the source of the first switching tube, and the second end of the second filter inductor are connected and grounded; and, the first end of the third filter inductor is connected to the source of the third switching tube and the cathode of the third diode, and the second end of the third filter inductor is connected to the first end of the first load; the first end of the fourth filter inductor is connected to the anode of the fourth diode and the drain of the fourth switching tube, and the second end of the fourth filter inductor is connected to the first end of the first load; the first end of the fifth filter inductor is connected to the source of the fifth switching tube and the cathode of the fifth diode, and the second end of the fifth filter inductor is connected to the first end of the second load; the first end of the sixth filter inductor is connected to the anode of the sixth diode and the drain of the sixth switching tube, and the second end of the sixth filter inductor is connected to the first end of the second load; the first end of the seventh filter inductor is connected to the source of the seventh switching tube and the cathode of the seventh diode, and the second end of the seventh filter inductor is connected to the first end of the third load; the first end of the eighth filter inductor is connected to the anode of the eighth diode and the drain of the eighth switching tube, and the second end of the eighth filter inductor is connected to the first end of the third load.

[0012] Optionally, the control and drive unit includes:

[0013] A sensor assembly, whose input ends are respectively connected to the first filter capacitor, the first load, the second load, the third load, the second end of the first filter inductor and the second filter inductor, and the negative half-cycle bus output end of the input power supply. The sensor assembly is used to collect the first filter capacitor voltage feedback signal, the first to third output voltage feedback signals, the first current feedback signal, the second current feedback signal and the negative half-cycle bus voltage feedback signal respectively;

[0014] A digital signal processor, whose input end is connected to the output end of the sensor assembly. The digital signal processor is used to process the first current feedback signal, the second current feedback signal, the first filter capacitor voltage feedback signal, the negative half-cycle bus voltage feedback signal, the first to third output voltage feedback signals respectively, and generate the first current feedback digital signal, the second current feedback digital signal, the first to fifth voltage feedback digital signals respectively, and generate the first to fourth voltage reference digital signals by itself. And perform voltage comparison control on the signals obtained by subtracting the first voltage reference digital signal from the first voltage feedback digital signal and the second voltage feedback digital signal respectively, to obtain the first current reference digital signal and the second current reference digital signal. Then perform current comparison control on the signals obtained by subtracting the first current reference digital signal and the second current reference digital signal from the first current feedback digital signal and the second current feedback digital signal respectively, to generate the first switch tube logic signal and the second switch tube logic signal. The digital signal processor also performs voltage comparison control on the signals obtained by subtracting the second to fourth voltage reference digital signals from the third to fifth voltage feedback digital signals respectively, to generate the third to eighth switch tube logic signals, where the third switch tube logic signal, the fifth switch tube logic signal, the seventh switch tube logic signal and the fourth switch tube logic signal, the sixth switch tube logic signal, the eighth switch tube logic signal are complementary signals;

[0015] A drive circuit, whose input end is connected to the output end of the digital signal processor, and the output ends of the drive circuit are respectively connected to the first to eighth switch tubes. The drive circuit is used to generate the first to eighth drive signals respectively according to the first to eighth switch tube logic signals to drive the opening and closing of each switch tube accordingly.

[0016] Optionally, the sensor assembly includes:

[0017] A first voltage sensor, whose input end is connected to the first filter capacitor, and the output end of the first voltage sensor is connected to the input end of the digital signal processor. The first voltage sensor is used to collect the first filter capacitor voltage feedback signal and transmit it to the digital signal processor;

[0018] A second voltage sensor, whose input terminal is connected to the negative pole of the input power supply, and whose output terminal is connected to the input terminal of the digital signal processor. The second voltage sensor is used to collect the negative half-cycle bus voltage feedback signal and transmit it to the digital signal processor;

[0019] A third voltage sensor, whose input terminal is connected to the first load, and whose output terminal is connected to the input terminal of the digital signal processor. The third voltage sensor is used to collect the first output voltage feedback signal and transmit it to the digital signal processor;

[0020] A fourth voltage sensor, whose input terminal is connected to the second load, and whose output terminal is connected to the input terminal of the digital signal processor. The fourth voltage sensor is used to collect the second output voltage feedback signal and transmit it to the digital signal processor;

[0021] A fifth voltage sensor, whose input terminal is connected to the third load, and whose output terminal is connected to the input terminal of the digital signal processor. The fifth voltage sensor is used to collect the third output voltage feedback signal and transmit it to the digital signal processor;

[0022] A first current sensor, whose input terminal is connected to the first filter inductor, and whose output terminal is connected to the input terminal of the digital signal processor. The first current sensor is used to collect the first current feedback signal and transmit it to the digital signal processor;

[0023] A second current sensor, whose input terminal is connected to the second filter inductor, and whose output terminal is connected to the input terminal of the digital signal processor. The second current sensor is used to collect the second current feedback signal and transmit it to the digital signal processor.

[0024] Optionally, the digital signal processor includes:

[0025] A first analog-to-digital conversion module, whose input terminal is connected to the output terminal of the first voltage sensor. The first analog-to-digital conversion module is used to perform analog-to-digital conversion on the first filter capacitor voltage feedback signal to obtain a first voltage feedback digital signal;

[0026] A second analog-to-digital conversion module, whose input terminal is connected to the output terminal of the second voltage sensor. The second analog-to-digital conversion module is used to perform analog-to-digital conversion on the negative half-cycle bus voltage feedback signal to obtain a second voltage feedback digital signal;

[0027] A third analog-to-digital conversion module, whose input end is connected to the output end of the third voltage sensor, and the third analog-to-digital conversion module is used to perform analog-to-digital conversion on the first output voltage feedback signal to obtain a third voltage feedback digital signal;

[0028] A fourth analog-to-digital conversion module, whose input end is connected to the output end of the fourth voltage sensor, and the fourth analog-to-digital conversion module is used to perform analog-to-digital conversion on the second output voltage feedback signal to obtain a fourth voltage feedback digital signal;

[0029] A fifth analog-to-digital conversion module, whose input end is connected to the output end of the fifth voltage sensor, and the fifth analog-to-digital conversion module is used to perform analog-to-digital conversion on the third output voltage feedback signal to obtain a fifth voltage feedback digital signal;

[0030] A sixth analog-to-digital conversion module, whose input end is connected to the output end of the first current sensor, and the sixth analog-to-digital conversion module is used to perform analog-to-digital conversion on the first current feedback signal to obtain a first current feedback digital signal;

[0031] A seventh analog-to-digital conversion module, whose input end is connected to the output end of the second current sensor, and the seventh analog-to-digital conversion module is used to perform analog-to-digital conversion on the second current feedback signal to obtain a second current feedback digital signal;

[0032] A first voltage reference calculation module, used to obtain and determine a first voltage reference digital signal according to the rated output peak voltage:

[0033] Second to fourth voltage reference calculation modules, respectively used to obtain and determine second to fourth voltage reference digital signals according to the rated output peak voltage and angular frequency.

[0034] Optionally, the digital signal processor further includes:

[0035] A first voltage regulator, whose first input end is connected to the output end of the first voltage reference calculation module, and whose second input end is connected to the output end of the first analog-to-digital conversion module. The first voltage regulator is used to perform voltage regulation on the first voltage feedback digital signal and the first voltage reference digital signal to obtain a first current reference digital signal;

[0036] A second voltage regulator, whose first input end is connected to the output end of the first voltage reference calculation module, and whose second input end is connected to the output end of the second analog-to-digital conversion module. The second voltage regulator is used to perform voltage regulation on the second voltage feedback digital signal and the first voltage reference digital signal to obtain a second current reference digital signal;

[0037] The first current regulator, whose first input terminal is connected to the output terminal of the first voltage regulator, and whose second input terminal is connected to the output terminal of the sixth analog-to-digital conversion module. The first current regulator is used to perform current regulation on the first current feedback digital signal and the first current reference digital signal to obtain a first high-frequency switching signal;

[0038] The second current regulator, whose first input terminal is connected to the output terminal of the second voltage regulator, and whose second input terminal is connected to the output terminal of the seventh analog-to-digital conversion module. The second current regulator is used to perform current regulation on the second current feedback digital signal and the second current reference digital signal to obtain a second high-frequency switching signal;

[0039] The third voltage regulator, whose first input terminal is connected to the output terminal of the second voltage reference calculation module, and whose second input terminal is connected to the output terminal of the third analog-to-digital conversion module. The third voltage regulator is used to perform voltage regulation on the third voltage feedback digital signal and the second voltage reference digital signal to obtain a third high-frequency switching signal;

[0040] The fourth voltage regulator, whose first input terminal is connected to the output terminal of the third voltage reference calculation module, and whose second input terminal is connected to the output terminal of the fourth analog-to-digital conversion module. The fourth voltage regulator is used to perform voltage regulation on the fourth voltage feedback digital signal and the third voltage reference digital signal to obtain a fourth high-frequency switching signal;

[0041] The fifth voltage regulator, whose first input terminal is connected to the output terminal of the fourth voltage reference calculation module, and whose second input terminal is connected to the output terminal of the fifth analog-to-digital conversion module. The fifth voltage regulator is used to perform voltage regulation on the fifth voltage feedback digital signal and the fourth voltage reference digital signal to obtain a fifth high-frequency switching signal;

[0042] The first PWM generator, whose input terminal is connected to the output terminal of the first current regulator. The first PWM generator is used to obtain a first switch tube logic signal according to the first high-frequency switching signal and transmit it to the first drive circuit;

[0043] The second PWM generator, whose input terminal is connected to the output terminal of the second current regulator. The second PWM generator is used to obtain a second switch tube logic signal according to the second high-frequency switching signal and transmit it to the second drive circuit;

[0044] The third PWM generator, whose input terminal is connected to the output terminal of the third voltage regulator. The third PWM generator is used to obtain a third switch tube logic signal and a fourth switch tube logic signal according to the third high-frequency switching signal and transmit them to the third drive circuit and the fourth drive circuit;

[0045] A fourth PWM generator, whose input terminal is connected to the output terminal of the fourth voltage regulator, and the fourth PWM generator is configured to obtain a fifth switch tube logic signal and a sixth switch tube logic signal according to the fourth high-frequency switch signal, and transmit them to a fifth driving circuit and a sixth driving circuit;

[0046] A fifth PWM generator, whose input terminal is connected to the output terminal of the fifth voltage regulator, and the fifth PWM generator is configured to obtain a seventh switch tube logic signal and an eighth switch tube logic signal according to the fifth high-frequency switch signal, and transmit them to a seventh driving circuit and an eighth driving circuit.

[0047] To achieve the above object, a second aspect of the present invention provides a buck-boost three-phase inverter control method, which is applied to the voltage regulation of the first load, and the voltage regulation methods of the second load and the third load are the same as that of the first load. The buck-boost three-phase inverter control method includes:

[0048] Step S1: Real-time collect a first voltage feedback digital signal of the first filter capacitor, and compare it with a first voltage reference digital signal generated by a digital signal processor;

[0049] Step S2: When the first voltage feedback digital signal is less than the first voltage reference digital signal, control the driving unit to regulate the first switch tube and / or the third switch tube to conduct the first closed loop and / or the first freewheeling loop, and the first current feedback digital signal tracks the first current reference digital signal to provide an input voltage for the positive half-cycle operation of the subsequent load;

[0050] Step S3: When the first voltage feedback digital signal is greater than the first voltage reference digital signal, the ninth diode conducts, and control the driving unit to regulate the third switch tube to conduct the third closed loop and / or the third freewheeling loop;

[0051] Step S4: When the power frequency period of the first output voltage feedback signal is in the negative half-cycle, the control driving unit regulates the second switch tube and / or the fourth switch tube to conduct the second closed loop and / or the second freewheeling loop, and the second current feedback digital signal tracks the second current reference digital signal to provide an input voltage for the negative half-cycle operation of the subsequent load.

[0052] Optionally, in the step S2, the step of the control driving unit regulating the first switch tube and / or the third switch tube includes:

[0053] Step S2.1: The control driving unit controls the first switch tube to conduct and the first closed loop to conduct so that the first filter inductor stores energy;

[0054] Step S2.2: Collect the first voltage feedback digital signal of the first filter capacitor in real time and compare it with the first voltage reference digital signal generated by the digital signal processor;

[0055] Step S2.3: If the first voltage feedback digital signal is less than the first voltage reference digital signal, the control and drive unit controls the first switch tube to turn off and the third switch tube to switch at high frequency. The input power supply and the first filter inductor jointly charge the first filter capacitor, so that the first filter capacitor provides voltage for the positive half-cycle operation of the load and completes the positive half-cycle regulation of the first output voltage. The first output voltage is the voltage across the first load;

[0056] Step S2.4: If the first voltage feedback digital signal is greater than the first voltage reference digital signal, the control and drive unit controls the third switch tube to switch at high frequency, so that the first freewheeling circuit conducts, and the first filter capacitor releases energy to complete the positive half-cycle regulation of the first output voltage.

[0057] Optionally, in step S3, the steps for the control and drive unit to regulate the third switch tube include:

[0058] Step S3.1: The control and drive unit controls the first switch tube to turn off and the third closed loop to conduct, so that the third filter inductor stores energy;

[0059] Step S3.2: Collect the third voltage feedback digital signal in real time and compare it with the second voltage reference digital signal generated by the digital signal processor;

[0060] Step S3.3: If the third voltage feedback digital signal is less than the second voltage reference digital signal, the control and drive unit controls the third switch tube to switch at high frequency, and the input power supply directly provides voltage for the positive half-cycle operation of the load to complete the positive half-cycle regulation of the first output voltage;

[0061] Step S3.4: If the third voltage feedback digital signal is greater than the second voltage reference digital signal, the control and drive unit controls the third switch tube to turn off and the third freewheeling circuit to conduct to complete the positive half-cycle regulation of the first output voltage.

[0062] Optionally, in step S4, the steps for the control and drive unit to regulate the second switch tube and / or the fourth switch tube include:

[0063] Step S4.1: The control and drive unit controls the second switch tube to conduct and the second closed loop to conduct to store energy in the second filter inductor;

[0064] Step S4.2: Collect the second voltage feedback digital signal in real time and compare it with the first voltage reference digital signal generated by the digital signal processor;

[0065] Step S4.3: If the second voltage feedback digital signal is less than the first voltage reference digital signal, the control and drive unit controls the second switch tube to turn off, the fourth switch tube to perform high-frequency switching, and the input power supply to charge the second filter capacitor, so that the second filter capacitor provides voltage for the negative half-cycle operation of the load, in order to complete the negative half-cycle regulation of the first output voltage;

[0066] Step S4.4: If the second voltage feedback digital signal is greater than the first voltage reference digital signal, the control and drive unit controls the second switch tube to turn on, the fourth switch tube to perform high-frequency switching, so that the second freewheeling loop conducts, and the second filter capacitor releases energy, in order to complete the negative half-cycle regulation of the first output voltage.

[0067] The present invention has at least the following technical effects:

[0068] The three-phase inverter provided by the present invention is a dual-buck full-bridge inverter, which solves the problem of shoot-through of the bridge arm of the traditional inverter, and commonly grounds the input power supply and the load, which can effectively eliminate the common-mode leakage current phenomenon of the inverter. In addition, the present invention provides a corresponding control device and control method, which can enable the three-phase inverter to achieve the step-up and step-down conversion function, thereby improving the operation stability of the inverter system.

[0069] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0070] Figure 1 It is a structural block diagram of a step-up / step-down three-phase inverter control device provided by an embodiment of the present invention;

[0071] Figure 2 It is a controlled circuit topology diagram of a step-up / step-down three-phase inverter provided by an embodiment of the present invention;

[0072] Figure 3 It is a circuit topology diagram of a control and drive unit provided by an embodiment of the present invention;

[0073] Figure 4 It is a flowchart of a step-up / step-down three-phase inverter control method provided by an embodiment of the present invention. Detailed Embodiment

[0074] The following details this embodiment. The examples of the embodiment are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0075] The buck-boost three-phase inverter control device and control method of this embodiment will be described below with reference to the accompanying drawings.

[0076] Figure 1 It is a structural block diagram of the buck-boost three-phase inverter control device provided by an embodiment of the present invention. As Figure 1 shown, the buck-boost three-phase inverter control device 1 includes a control and drive unit 10 and a buck-boost three-phase inverter 20.

[0077] Among them, the buck-boost three-phase inverter 20 includes a filter capacitor, an input power supply, a filter inductor, a load, and a switch tube drive circuit composed of several switch tubes and several diodes. Among them, the filter capacitor, the input power supply, the filter inductor, the load, several switch tubes, and diodes form multiple closed loops and freewheeling loops; the input end of the control and drive unit 10 is connected to the filter capacitor, the filter inductor, the load, and the negative half-cycle bus output end of the input power supply, and the output end of the control and drive unit 10 is connected to the control ends of several switch tubes. The control and drive unit 10 is used to collect the voltage feedback signals of the filter capacitor and the load, the negative half-cycle bus voltage signal output from the negative half-cycle bus output end, and the current feedback signal of the filter inductor, and perform on-off control on several switch tubes according to the voltage feedback signal, the negative half-cycle bus voltage signal, and the current feedback signal to connect each closed loop and freewheeling loop for load voltage regulation control.

[0078] In this embodiment, as Figure 2 shown, the buck-boost three-phase inverter 20 specifically includes: an input power supply U in , first to eighth filter inductors L1 to L8, first to eighth switch tubes S1 to S8, first to ninth diodes D1 to D9, first to fifth filter capacitors C1 to C5, and first to third loads R1 to R3.

[0079] Among them, the first end of the second filter capacitor C2, the drain of the second switch tube S2, the input power supply U inThe positive output terminal, the first end of the first filter inductor L1, and the anode of the ninth diode D9 are connected. The cathodes of the first diode D1, the fourth diode D4, the sixth diode D6, the eighth diode D8, the ninth diode D9, the drains of the third switch S3, the fifth switch S5, the seventh switch S7, and the first end of the first filter capacitor C1 are connected. The anodes of the second diode D2, the third diode D3, the fifth diode D5, the seventh diode D7, the sources of the fourth switch S4, the sixth switch S6, the eighth switch S8, and the second end of the second filter capacitor C2 are connected. The source of the second switch S2, the cathode of the second diode D2, and the first end of the second filter inductor L2 are connected. The second end of the first filter inductor L1, the drain of the first switch S1, and the anode of the first diode D1 are connected. The third filter capacitor C3 is connected in parallel with the first load R1, the fourth filter capacitor C4 is connected in parallel with the second load R2, the fifth filter capacitor C5 is connected in parallel with the third load R3. The second ends of the first load R1, the second load R2, the third load R3, the second end of the first filter capacitor C1, the source of the first switch S1, and the second end of the second filter inductor L2 are connected and grounded. And, the first end of the third filter inductor L3 is connected to the source of the third switch S3 and the cathode of the third diode D3, and the second end of the third filter inductor L3 is connected to the first end of the first load R1. The first end of the fourth filter inductor L4 is connected to the anode of the fourth diode D4 and the drain of the fourth switch S4, and the second end of the fourth filter inductor L4 is connected to the first end of the first load R1. The first end of the fifth filter inductor L5 is connected to the source of the fifth switch S5 and the cathode of the fifth diode D5, and the second end of the fifth filter inductor L5 is connected to the first end of the second load R2. The first end of the sixth filter inductor L6 is connected to the anode of the sixth diode D6 and the drain of the sixth switch S6, and the second end of the sixth filter inductor L6 is connected to the first end of the second load R2. The first end of the seventh filter inductor L7 is connected to the source of the seventh switch S7 and the cathode of the seventh diode D7, and the second end of the seventh filter inductor L7 is connected to the first end of the third load R3. The first end of the eighth filter inductor L8 is connected to the anode of the eighth diode D8 and the drain of the eighth switch S8, and the second end of the eighth filter inductor L8 is connected to the first end of the third load R3.

[0080] Wherein, the first filter inductor L1 and the input power supply U in , the first switch S1 are connected in series to form a first closed loop. Taking the first load R1 as an example, the first closed loop is that when the voltage U C1 of the first filter capacitor is less than the reference voltage U ref1 of the first filter capacitor, the positive half-cycle working loop of the first output voltage feedback signal u o1f in the power frequency period; the second filter inductor L2 and the input power supply U in, the second switching tube S2 is connected in series to form a second closed loop, and the second closed loop is the first output voltage feedback signal u o1f The negative half-cycle working loop of the power frequency period; the ninth diode D9 and the input power supply U in , the third switching tube S3, the third filter inductor L3, and the first load R1 are connected in series to form a third closed loop, and the third closed loop is the voltage U of the first filter capacitor C1 When it is greater than the reference voltage U of the first filter capacitor ref1 , the first output voltage feedback signal u o1f The positive half-cycle working loop of the power frequency period; the first filter capacitor C1 is connected in series with the third switching tube S3, the third filter inductor L3, and the first load R1 to form a first freewheeling loop, and the first freewheeling loop is the first output voltage feedback signal u o1f The positive half-cycle working loop of the power frequency period; the second diode D2 is connected in series with the fourth switching tube S4, the fourth filter inductor L4, the first load R1, and the second filter inductor L2 to form a second freewheeling loop, and the second freewheeling loop is the first output voltage feedback signal u o1f The negative half-cycle working loop of the power frequency period; the input power supply U in is connected in series with the second filter capacitor C2, the third diode D3, the third filter inductor L3, and the first load R1 to form a third freewheeling loop, and the third freewheeling loop is the first output voltage feedback signal u o1f The positive half-cycle working loop of the power frequency period.

[0081] It should be noted that the first filter capacitor C1 to the fifth filter capacitor C5 in this embodiment are non-polar capacitors. The first switching tube S1 to the eighth switching tube S8 are all metal-oxide-semiconductor field-effect transistors and / or insulated gate bipolar transistors.

[0082] In this embodiment, the input power supply U in is used to provide electrical energy for the three-phase inverter, and the input power supply U in is grounded together with the load, which can effectively eliminate the common-mode leakage current of the three-phase inverter.

[0083] As Figure 3 shown, the control drive unit 10 includes: a sensor component 1, a digital signal processor 2, and a drive circuit 3.

[0084] Among them, for the sensor component 1, its input terminals are respectively connected to the second ends of the first filter capacitor C1, the first load R1, the second load R2, the third load R3, the first filter inductor L1, and the second filter inductor L2 in the buck-boost three-phase inverter circuit and the negative half-cycle bus output terminal, and are used to respectively collect the first filter capacitor voltage feedback signal U C1f , the negative half-cycle bus voltage feedback signal U 1f, the first output voltage feedback signal u o1f to the third output voltage feedback signal u o3f , the first current feedback signals i L1f and the second current feedback signals i L2f .

[0085] A digital signal processor 2, whose input terminal is connected to the output terminal of the sensor assembly 1, is used to process signals of the first current feedback signal i L1f , the second current feedback signal i L2f , the first filter capacitor voltage feedback signal U C1f , the negative half-cycle bus voltage feedback signal U 1f , the first output voltage feedback signal u o1f to the third output voltage feedback signal u o3f , generate the first current feedback digital signal i L1fd , the second current feedback digital signal i L2fd , the first voltage feedback digital signal U C1fd , the second voltage feedback digital signal U 1fd , the third voltage feedback digital signal u o1fd , the fourth voltage feedback digital signal u o2fd , the fifth voltage feedback digital signal u o3fd , and self-generate the first voltage reference digital signal U ref1 , the second voltage reference digital signal u ref2 , the third voltage reference digital signal u ref3 , the fourth voltage reference digital signal u ref4 , and perform voltage comparison control on the signals obtained by subtracting the first voltage reference digital signal U ref1 from the first voltage feedback digital signal U C1fd and the second voltage feedback digital signal U 1fd respectively, to obtain the first current reference digital signal i ref1 and the second current reference digital signal i ref2 . Further, the first current reference digital signal i ref1 and the second current reference digital signal i ref2 can be respectively subtracted from the first current feedback digital signal i L1fd and the second current feedback digital signal i L2fd again, and perform current comparison control on the obtained signals to generate the first switch tube logic signal PWM1 (Pulse Width Modulation) and the second switch tube logic signal PWM2, and for the second voltage reference digital signal u ref2 , the third voltage reference digital signal u ref3, the fourth voltage reference digital signal u ref4 , respectively subtract from the third voltage feedback digital signal u o1fd , the fourth voltage feedback digital signal u o2fd , the fifth voltage feedback digital signal u o3fd , and perform voltage comparison control on the subtracted signals to generate the third switch transistor logic signal PWM3 to the eighth switch transistor logic signal PWM8. Among them, the third switch transistor logic signal PWM3, the fifth switch transistor logic signal PWM5, and the seventh switch transistor logic signal PWM7 are complementary signals to the fourth switch transistor logic signal PWM4, the sixth switch transistor logic signal PWM6, and the eighth switch transistor logic signal PWM8, respectively.

[0086] The drive circuit 3, whose input end is connected to the output end of the digital signal processor 2, and whose output end is respectively connected to the first switch transistor S1 to the eighth switch transistor S8, is used to respectively generate the first drive signal to the eighth drive signal according to the first switch transistor logic signal PWM1 to the eighth switch transistor logic signal PWM8, so as to drive the opening and closing of each switch transistor accordingly.

[0087] Please continue to refer to Figure 3 , the sensor assembly 1 includes: the first voltage sensor 101 to the second current sensor 107. Among them, the input end of the first voltage sensor 101 is connected to the first filter capacitor C1, and the output end is connected to the input end of the digital signal processor 2, and it is used to collect the first filter capacitor voltage feedback signal U C1f and transmit it to the digital signal processor 2; the input end of the second voltage sensor 102 is connected to the negative pole of the input power supply U in , that is, the input end is connected to the negative half-cycle bus, and its output end is connected to the input end of the digital signal processor 2. The second voltage sensor 102 is used to collect the negative half-cycle bus voltage feedback signal U 1f and transmit it to the digital signal processor 2; the input end of the third voltage sensor 103 is connected to the first load R1, and its output end is connected to the input end of the digital signal processor 2, and it is used to collect the first output voltage feedback signal u o1f and transmit it to the digital signal processor 2; the input end of the fourth voltage sensor 104 is connected to the second load R2, and its output end is connected to the input end of the digital signal processor 2, and it is used to collect the second output voltage feedback signal u o2f and transmit it to the digital signal processor 2; the input end of the fifth voltage sensor 105 is connected to the third load R3, and its output end is connected to the input end of the digital signal processor 2, and it is used to collect the third output voltage feedback signal u o3fand transmit it to the digital signal processor 2; the input end of the first current sensor 106 is connected to the first filter inductor L1, and its output end is connected to the input end of the digital signal processor 2, which is used to collect the first current feedback signal i L1f and transmit it to the digital signal processor 2; the input end of the second current sensor 107 is connected to the second filter inductor L2, and its output end is connected to the input end of the digital signal processor 2, which is used to collect the second current feedback signal i L2f and transmit it to the digital signal processor 2.

[0088] Please continue to refer to Figure 3 , the digital signal processor 2 includes: the first analog-to-digital conversion module AD1 to the seventh analog-to-digital conversion module AD7, the first voltage reference calculation module 201 to the fifth PWM generator 216.

[0089] Among them, the input end of the first analog-to-digital conversion module AD1 is connected to the output end of the first voltage sensor 101, and is used to perform analog-to-digital conversion on the first filter capacitor voltage feedback signal U C1f to obtain the first voltage feedback digital signal U C1fd ; the input end of the second analog-to-digital conversion module AD2 is connected to the output end of the second voltage sensor 102, and is used to perform analog-to-digital conversion on the negative half-cycle bus voltage feedback signal U 1f to obtain the second voltage feedback digital signal U 1fd ; the input end of the third analog-to-digital conversion module AD3 is connected to the output end of the third voltage sensor 103, and is used to perform analog-to-digital conversion on the first output voltage feedback signal u o1f to obtain the third voltage feedback digital signal u o1fd ; the input end of the fourth analog-to-digital conversion module AD4 is connected to the output end of the input fourth voltage sensor 104, and is used to perform analog-to-digital conversion on the second output voltage feedback signal u o2f to obtain the fourth voltage feedback digital signal u o2fd ; the input end of the fifth analog-to-digital conversion module AD5 is connected to the output end of the fifth voltage sensor 105, and is used to perform analog-to-digital conversion on the third output voltage feedback signal u o3f to obtain the fifth voltage feedback digital signal u o3fd ; the input end of the sixth analog-to-digital conversion module AD6 is connected to the output end of the first current sensor 106, and is used to perform analog-to-digital conversion on the first current feedback signal i L1f to obtain the first current feedback digital signal i L1fd ; the input end of the seventh analog-to-digital conversion module AD7 is connected to the output end of the second current sensor 107, and is used to perform analog-to-digital conversion on the second current feedback signal i L2f to obtain the second current feedback digital signal i L2fd .

[0090] Further, the first voltage reference calculation module 201 is used for calculating the first voltage reference digital signal. From the rated output peak voltage U p , through the formula U ref1 = 1.2U p , the first voltage reference digital signal U ref1 is determined; the second voltage reference calculation module 202 is used for calculating the second voltage reference digital signal. From the rated output peak voltage U p and the angular frequency ω, through the formula u ref2 = U p sin(ωt), the second voltage reference digital signal u ref2 is determined; the third voltage reference calculation module 203 is used for calculating the third voltage reference digital signal. From the rated output peak voltage U p and the angular frequency ω, through the formula , the third voltage reference digital signal u ref3 is determined; the fourth voltage reference calculation module 204 is used for calculating the fourth voltage reference digital signal. From the rated output peak voltage U p and the angular frequency ω, through the formula , the fourth voltage reference digital signal u ref4 .

[0091] Further, the first input end of the first voltage regulator 205 is connected to the output end of the first voltage reference calculation module 201, and the second input end is connected to the output end of the first analog-to-digital conversion module AD1. It is used for voltage regulation of the first voltage feedback digital signal U C1fd and the first voltage reference digital signal U ref1 to obtain the first current reference digital signal i ref1 ; the first input end of the second voltage regulator 206 is connected to the output end of the first voltage reference calculation module 201, and its second input end is connected to the output end of the second analog-to-digital conversion module AD2. It is used for voltage regulation of the second voltage feedback digital signal U 1fd and the first voltage reference digital signal U ref1 to obtain the second current reference digital signal i ref2 .

[0092] Further, the first input end of the first current regulator 207 is connected to the output end of the first voltage regulator 205, and its second input end is connected to the output end of the sixth analog-to-digital conversion module AD6. It is used for regulating the first current feedback digital signal i L1fd and the first current reference digital signal i ref1Perform current regulation to obtain a first high-frequency switching signal; a second current regulator 208, with its first input terminal connected to the output terminal of the second voltage regulator 206 and its second input terminal connected to the output terminal of the seventh analog-to-digital conversion module AD7, for performing current regulation on the second current feedback digital signal i L2fd and the second current reference digital signal i ref2 to obtain a second high-frequency switching signal.

[0093] Furthermore, the first input terminal of a third voltage regulator 209 is connected to the output terminal of the second voltage reference calculation module 202, and its second input terminal is connected to the output terminal of the third analog-to-digital conversion module AD3, for performing voltage regulation on the third voltage feedback digital signal u o1fd and the second voltage reference digital signal u ref2 to obtain a third high-frequency switching signal; the first input terminal of a fourth voltage regulator 210 is connected to the output terminal of the third voltage reference calculation module 203, and its second input terminal is connected to the output terminal of the fourth analog-to-digital conversion module AD4, for performing voltage regulation on the fourth voltage feedback digital signal u o2fd and the third voltage reference digital signal u ref3 to obtain a fourth high-frequency switching signal; the first input terminal of a fifth voltage regulator 211 is connected to the output terminal of the fourth voltage reference calculation module 204, and its second input terminal is connected to the output terminal of the fifth analog-to-digital conversion module AD5, for performing voltage regulation on the fifth voltage feedback digital signal u o3fd and the fourth voltage reference digital signal u ref4 to obtain a fifth high-frequency switching signal.

[0094] Further, the input end of the first PWM generator 212 is connected to the output end of the first current regulator 207, and is configured to obtain a first switch tube logic signal PWM1 according to the first high-frequency switching signal and transmit it to the first drive circuit 301; the input end of the second PWM generator 213 is connected to the output end of the second current regulator 208, and is configured to obtain a second switch tube logic signal PWM2 according to the second high-frequency switching signal and transmit it to the second drive circuit 302; the input end of the third PWM generator 214 is connected to the output end of the third voltage regulator 209, and is configured to obtain a third switch tube logic signal PWM3 and a fourth switch tube logic signal PWM4 which are complementary signals according to the third high-frequency switching signal and transmit them to the third drive circuit 303 and the fourth drive circuit 304; the input end of the fourth PWM generator 215 is connected to the output end of the fourth voltage regulator 210, and is configured to obtain a fifth switch tube logic signal PWM5 and a sixth switch tube logic signal PWM6 which are complementary signals according to the fourth high-frequency switching signal and transmit them to the fifth drive circuit 305 and the sixth drive circuit 306; the input end of the fifth PWM generator 216 is connected to the output end of the fifth voltage regulator 211, and is configured to obtain a seventh switch tube logic signal PWM7 and an eighth switch tube logic signal PWM8 which are complementary signals according to the fifth high-frequency switching signal and transmit them to the seventh drive circuit 307 and the eighth drive circuit 308.

[0095] The drive circuit 3 further includes: a first drive circuit 301 to an eighth drive circuit 308, whose output ends are respectively connected to the first switch tube S1 to the eighth switch tube S8, and are configured to drive the corresponding switch tubes to open and close.

[0096] It should be noted that the first voltage regulator 205, the second voltage regulator 206, the first current regulator 207, the second current regulator 208, the third voltage regulator 209, the fourth voltage regulator 210 and the fifth voltage regulator 211 in this embodiment adopt any one of PI control, hysteresis control or proportional resonance control.

[0097] Figure 4 It is a flowchart of a buck-boost three-phase inverter control method provided by an embodiment of the present invention. As Figure 4 shown, the method includes:

[0098] Step S1: Real-time collect a first voltage feedback digital signal of the first filter capacitor and compare it with a first voltage reference digital signal generated by a digital signal processor.

[0099] Step S2: When the first voltage feedback digital signal is less than the first voltage reference digital signal, control the driving unit to regulate the first switching tube and / or the third switching tube to turn on the first closed loop and / or the first freewheeling loop, so that the first current feedback digital signal tracks the first current reference digital signal, and provide an input voltage for the positive half-cycle operation of the subsequent-stage load.

[0100] Among them, the control of the driving unit 10 to regulate the first switching tube S1 and / or the third switching tube S3 includes the following steps:

[0101] Step S2.1: The control driving unit 10 controls the first switching tube S1 to turn on, and the first closed loop turns on so that the first filter inductor L1 stores energy;

[0102] Step S2.2: Real-time collect the first voltage feedback digital signal U C1fd of the first filter capacitor C1, and compare it with the first voltage reference digital signal U ref1 generated by the digital signal processor 2;

[0103] Step S2.3: If the first voltage feedback digital signal U C1fd is less than the first voltage reference digital signal U ref1 , the control driving unit 10 controls the first switching tube S1 to turn off, and the third switching tube S3 performs high-frequency switching. The input power supply U in and the first filter inductor L1 jointly charge the first filter capacitor C1 to provide a voltage for the positive half-cycle operation of the load, and then complete the positive half-cycle regulation of the first output voltage. The first output voltage is the voltage across the first load;

[0104] Step S2.4: If the first voltage feedback digital signal U C1fd is greater than the first voltage reference digital signal U ref1 , the control driving unit 10 controls the third switching tube S3 to perform high-frequency switching, the first freewheeling loop turns on, and the first filter capacitor C1 releases energy to complete the positive half-cycle regulation of the first output voltage.

[0105] Step S3: When the first voltage feedback digital signal is greater than the first voltage reference digital signal, the ninth diode turns on, and the control driving unit regulates the third switching tube to turn on the third closed loop and / or the third freewheeling loop.

[0106] Among them, the control of the driving unit 10 to regulate the third switching tube S3 includes the following steps:

[0107] Step S3.1: The control driving unit 10 controls the first switching tube S1 to turn off, and the third closed loop turns on so that the third filter inductor L3 stores energy;

[0108] Step S3.2: Real-time collect the third voltage feedback digital signal uo1fd and compare it with the second voltage reference digital signal u generated by the digital signal processor ref2 ;

[0109] Step S3.3: If the third voltage feedback digital signal u o1fd is less than the second voltage reference digital signal u ref2 , control the driving unit 10 to control the third switching tube S3 to switch at high frequency, and the input power supply U in directly provides voltage for the positive half-cycle operation of the load, thereby completing the positive half-cycle regulation of the first output voltage;

[0110] Step S3.4: If the third voltage feedback digital signal u o1fd is greater than the second voltage reference digital signal u ref2 , control the driving unit 10 to control the third switching tube S3 to turn off, and the third freewheeling circuit conducts, thereby completing the positive half-cycle regulation of the first output voltage.

[0111] Step S4: When the power frequency period of the first output voltage feedback signal is in the negative half-cycle, the control driving unit regulates the second switching tube and / or the fourth switching tube to conduct the second closed loop and / or the second freewheeling circuit, and the second current feedback digital signal tracks the second current reference digital signal to provide input voltage for the negative half-cycle operation of the subsequent load.

[0112] Among them, the control driving unit 10 regulating the second switching tube S2 and / or the fourth switching tube S4 includes the following steps:

[0113] Step S4.1: Control the driving unit 10 to control the second switching tube S2 to conduct, and the second closed loop conducts so that the second filter inductor L2 stores energy;

[0114] Step S4.2: Real-time collect the second voltage feedback digital signal U 1fd , and compare it with the first voltage reference digital signal generated by the digital signal processor U ref1 ;

[0115] Step S4.3: If the second voltage feedback digital signal U 1fd is less than the first voltage reference digital signal U ref1 , control the driving unit 10 to control the second switching tube S2 to turn off, and the fourth switching tube S4 switches at high frequency, and the input power supply U in charges the second filter capacitor C2 so that it provides voltage for the negative half-cycle operation of the load, thereby completing the negative half-cycle regulation of the first output voltage.

[0116] Specifically, the first voltage feedback digital signal U of the first filter capacitor C1 can be collected in real time C1fd , and compare it with the first voltage reference digital signal U generated by the digital signal processor 2 ref1Compare. When the operating mode of the inverter is the boost mode, that is, when the first voltage feedback digital signal U C1fd is less than the first voltage reference digital signal U ref1 , the control drive unit 10 regulates the first switch tube S1 and / or the third switch tube S3 to turn on the first closed loop and / or the first freewheeling loop, and the first current feedback digital signal i L1fd tracks the first current reference digital signal i ref1 , providing a relatively large input voltage for the positive half-cycle operation of the subsequent-stage load. When the operating mode of the inverter is the buck mode, that is, when the first voltage feedback digital signal U C1fd is greater than the first voltage reference digital signal U ref1 , the ninth diode D9 conducts, and the control drive unit 10 regulates the third switch tube S3 to turn on the third closed loop and / or the third freewheeling loop. When the operating mode of the inverter is the buck-boost mode, that is, when the power frequency period of the first output voltage feedback signal u o1f is the negative half-cycle, the control drive unit 10 regulates the second switch tube S2 and / or the fourth switch tube S4 to turn on the second closed loop and / or the second freewheeling loop, and the second current feedback digital signal i L2fd tracks the second current reference digital signal i ref2 , providing an input voltage for the negative half-cycle operation of the subsequent-stage load.

[0117] In summary, the three-phase inverter provided by the present invention is a dual-buck full-bridge inverter, which solves the problem of shoot-through of the bridge arm of the traditional inverter, and jointly grounds the input power supply and the load, effectively eliminating the common-mode leakage current phenomenon of the inverter. In addition, the present invention provides a corresponding control device and control method, which can enable the three-phase inverter to achieve the buck-boost conversion function, thereby improving the operation stability of the inverter system.

[0118] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0119] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be construed as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention shall be defined by the appended claims.

Claims

1. A buck-boost three-phase inverter control device, characterized in that Comprising: A buck-boost three-phase inverter, which includes a filter capacitor, an input power supply, a filter inductor, a load, a switching tube driving circuit composed of a plurality of switching tubes and a plurality of diodes. Among them, the filter capacitor, the input power supply, the filter inductor, the load, a plurality of the switching tubes and the diodes form a plurality of closed loops and freewheeling loops; A control driving unit, the input end of the control driving unit is connected to the filter capacitor, the filter inductor, the load and the negative half-cycle bus output end of the input power supply, the output end of the control driving unit is connected to the control ends of a plurality of the switching tubes, and the control driving unit is used to collect the voltage feedback signal of the filter capacitor, the load, the negative half-cycle bus voltage signal output by the negative half-cycle bus output end and the current feedback signal of the filter inductor, and according to the voltage feedback signal, the negative half-cycle bus voltage signal and the current feedback signal, perform on-off control on a plurality of the switching tubes to connect each closed loop and freewheeling loop to perform load voltage regulation control; The load includes: a first load, a second load and a third load; the buck-boost three-phase inverter control device adjusts the voltage of the first load, and the voltage regulation of the second load and the third load is the same as that of the first load. The specific steps for the buck-boost three-phase inverter control device to adjust the voltage of the load include: Step S1: Real-time collect the first voltage feedback digital signal of the first filter capacitor and compare it with the first voltage reference digital signal generated by the digital signal processor; Step S2: When the first voltage feedback digital signal is less than the first voltage reference digital signal, the control driving unit regulates the first switching tube and / or the third switching tube to conduct the first closed loop and / or the first freewheeling loop, and the first current feedback digital signal tracks the first current reference digital signal to provide an input voltage for the positive half-cycle operation of the subsequent load; Step S3: When the first voltage feedback digital signal is greater than the first voltage reference digital signal, the ninth diode conducts, and the control driving unit regulates the third switching tube to conduct the third closed loop and / or the third freewheeling loop; Step S4: When the power frequency period of the first output voltage feedback signal is the negative half-cycle, the control driving unit regulates the second switching tube and / or the fourth switching tube to conduct the second closed loop and / or the second freewheeling loop, and the second current feedback digital signal tracks the second current reference digital signal to provide an input voltage for the negative half-cycle operation of the subsequent load.

2. The buck-boost three-phase inverter control device according to claim 1, characterized in that The buck-boost three-phase inverter specifically includes: the input power supply, the first to eighth filter inductors, the first to eighth switching tubes, the first to ninth diodes, the first to fifth filter capacitors, the first to third loads; The first end of the second filter capacitor, the drain of the second switching transistor, the positive output terminal of the input power supply, the first end of the first filter inductor, and the anode of the ninth diode are connected. The cathodes of the first diode, the fourth diode, the sixth diode, the eighth diode, the ninth diode, the third switching transistor, the fifth switching transistor, the seventh switching transistor, and the first end of the first filter capacitor are connected. The anodes of the second diode, the third diode, the fifth diode, the seventh diode, the source electrodes of the fourth switching transistor, the sixth switching transistor, and the eighth switching transistor, and the second end of the second filter capacitor are connected. The source electrode of the second switching transistor, the cathode of the second diode, and the first end of the second filter inductor are connected. The second end of the first filter inductor, the drain of the first switching transistor, and the anode of the first diode are connected. The third filter capacitor is connected in parallel with the first load, the fourth filter capacitor is connected in parallel with the second load, the fifth filter capacitor is connected in parallel with the third load, the second ends of the first load, the second load, the third load, the second end of the first filter capacitor, the source electrode of the first switching transistor, and the second end of the second filter inductor are connected and grounded. And, The first end of the third filter inductor is connected to the source electrode of the third switching transistor and the cathode of the third diode, and the second end of the third filter inductor is connected to the first end of the first load. The first end of the fourth filter inductor is connected to the anode of the fourth diode and the drain of the fourth switching transistor, and the second end of the fourth filter inductor is connected to the first end of the first load. The first end of the fifth filter inductor is connected to the source electrode of the fifth switching transistor and the cathode of the fifth diode, and the second end of the fifth filter inductor is connected to the first end of the second load. The first end of the sixth filter inductor is connected to the anode of the sixth diode and the drain of the sixth switching transistor, and the second end of the sixth filter inductor is connected to the first end of the second load. The first end of the seventh filter inductor is connected to the source electrode of the seventh switching transistor and the cathode of the seventh diode, and the second end of the seventh filter inductor is connected to the first end of the third load. The first end of the eighth filter inductor is connected to the anode of the eighth diode and the drain of the eighth switching transistor, and the second end of the eighth filter inductor is connected to the first end of the third load.

3. The buck-boost three-phase inverter control device according to claim 2, characterized in that, The control and drive unit includes: A sensor assembly, whose input terminals are respectively connected to the second end of the first filter capacitor, the first load, the second load, the third load, the first filter inductor, the second filter inductor, and the negative half-cycle bus output terminal of the input power supply. The sensor assembly is used to respectively collect a first filter capacitor voltage feedback signal, first to third output voltage feedback signals, a first current feedback signal, a second current feedback signal, and a negative half-cycle bus voltage feedback signal; A digital signal processor, whose input end is connected to the output end of the sensor assembly. The digital signal processor is used to perform signal processing on the first current feedback signal, the second current feedback signal, the first filter capacitor voltage feedback signal, the negative half-cycle bus voltage feedback signal, and the first to third output voltage feedback signals respectively, and generate a first current feedback digital signal, a second current feedback digital signal, and first to fifth voltage feedback digital signals accordingly. Moreover, it self-generates first to fourth voltage reference digital signals, and performs voltage comparison control on the signals obtained by subtracting the first voltage reference digital signal from the first voltage feedback digital signal and the second voltage feedback digital signal respectively, to obtain a first current reference digital signal and a second current reference digital signal. Then, it performs current comparison control on the signals obtained by subtracting the first current reference digital signal and the second current reference digital signal from the first current feedback digital signal and the second current feedback digital signal respectively, to generate a first switch tube logic signal and a second switch tube logic signal. The digital signal processor also performs voltage comparison control on the signals obtained by subtracting the second to fourth voltage reference digital signals from the third to fifth voltage feedback digital signals respectively, to generate third to eighth switch tube logic signals, where the third switch tube logic signal, the fifth switch tube logic signal, and the seventh switch tube logic signal are complementary signals to the fourth switch tube logic signal, the sixth switch tube logic signal, and the eighth switch tube logic signal respectively; A drive circuit, whose input end is connected to the output end of the digital signal processor. The output end of the drive circuit is connected to the first to eighth switch tubes respectively. The drive circuit is used to generate first to eighth drive signals respectively according to the first to eighth switch tube logic signals, so as to drive the opening and closing of each switch tube accordingly.

4. The buck-boost three-phase inverter control device according to claim 3, wherein The sensor assembly includes: A first voltage sensor, whose input end is connected to the first filter capacitor, and the output end of the first voltage sensor is connected to the input end of the digital signal processor. The first voltage sensor is used to collect the first filter capacitor voltage feedback signal and transmit it to the digital signal processor; A second voltage sensor, whose input end is connected to the negative pole of the input power supply, and the output end of the second voltage sensor is connected to the input end of the digital signal processor. The second voltage sensor is used to collect the negative half-cycle bus voltage feedback signal and transmit it to the digital signal processor; A third voltage sensor, whose input end is connected to the first load, and the output end of the third voltage sensor is connected to the input end of the digital signal processor. The third voltage sensor is used to collect the first output voltage feedback signal and transmit it to the digital signal processor; A fourth voltage sensor, whose input end is connected to the second load, and the output end of the fourth voltage sensor is connected to the input end of the digital signal processor. The fourth voltage sensor is used to collect the second output voltage feedback signal and transmit it to the digital signal processor; A fifth voltage sensor, whose input end is connected to the third load, and the output end of the fifth voltage sensor is connected to the input end of the digital signal processor. The fifth voltage sensor is used to collect the third output voltage feedback signal and transmit it to the digital signal processor; A first current sensor, whose input end is connected to the first filter inductor, and the output end of the first current sensor is connected to the input end of the digital signal processor. The first current sensor is used to collect the first current feedback signal and transmit it to the digital signal processor; A second current sensor, whose input end is connected to the second filter inductor, and the output end of the second current sensor is connected to the input end of the digital signal processor. The second current sensor is used to collect the second current feedback signal and transmit it to the digital signal processor.

5. The buck-boost three-phase inverter control device according to claim 4, wherein The digital signal processor includes: A first analog-to-digital conversion module, whose input end is connected to the output end of the first voltage sensor. The first analog-to-digital conversion module is used to perform analog-to-digital conversion on the first filter capacitor voltage feedback signal to obtain a first voltage feedback digital signal; A second analog-to-digital conversion module, whose input end is connected to the output end of the second voltage sensor. The second analog-to-digital conversion module is used to perform analog-to-digital conversion on the negative half-cycle bus voltage feedback signal to obtain a second voltage feedback digital signal; A third analog-to-digital conversion module, whose input end is connected to the output end of the third voltage sensor. The third analog-to-digital conversion module is used to perform analog-to-digital conversion on the first output voltage feedback signal to obtain a third voltage feedback digital signal; A fourth analog-to-digital conversion module, whose input end is connected to the output end of the fourth voltage sensor. The fourth analog-to-digital conversion module is used to perform analog-to-digital conversion on the second output voltage feedback signal to obtain a fourth voltage feedback digital signal; A fifth analog-to-digital conversion module, whose input end is connected to the output end of the fifth voltage sensor. The fifth analog-to-digital conversion module is used to perform analog-to-digital conversion on the third output voltage feedback signal to obtain a fifth voltage feedback digital signal; A sixth analog-to-digital conversion module, whose input end is connected to the output end of the first current sensor. The sixth analog-to-digital conversion module is used to perform analog-to-digital conversion on the first current feedback signal to obtain a first current feedback digital signal; A seventh analog-to-digital conversion module, whose input end is connected to the output end of the second current sensor. The seventh analog-to-digital conversion module is used to perform analog-to-digital conversion on the second current feedback signal to obtain a second current feedback digital signal; A first voltage reference calculation module, which is used to obtain and determine a first voltage reference digital signal according to the rated output peak voltage; Second to fourth voltage reference calculation modules, which are respectively used to obtain and determine second to fourth voltage reference digital signals according to the rated output peak voltage and the angular frequency.

6. The buck-boost three-phase inverter control device according to claim 5, characterized in that, The digital signal processor further includes: The first voltage regulator, whose first input terminal is connected to the output terminal of the first voltage reference calculation module, and whose second input terminal is connected to the output terminal of the first analog-to-digital conversion module. The first voltage regulator is used to regulate the first voltage feedback digital signal and the first voltage reference digital signal to obtain a first current reference digital signal; The second voltage regulator, whose first input terminal is connected to the output terminal of the first voltage reference calculation module, and whose second input terminal is connected to the output terminal of the second analog-to-digital conversion module. The second voltage regulator is used to regulate the second voltage feedback digital signal and the first voltage reference digital signal to obtain a second current reference digital signal; The first current regulator, whose first input terminal is connected to the output terminal of the first voltage regulator, and whose second input terminal is connected to the output terminal of the sixth analog-to-digital conversion module. The first current regulator is used to regulate the first current feedback digital signal and the first current reference digital signal to obtain a first high-frequency switching signal; The second current regulator, whose first input terminal is connected to the output terminal of the second voltage regulator, and whose second input terminal is connected to the output terminal of the seventh analog-to-digital conversion module. The second current regulator is used to regulate the second current feedback digital signal and the second current reference digital signal to obtain a second high-frequency switching signal; The third voltage regulator, whose first input terminal is connected to the output terminal of the second voltage reference calculation module, and whose second input terminal is connected to the output terminal of the third analog-to-digital conversion module. The third voltage regulator is used to regulate the third voltage feedback digital signal and the second voltage reference digital signal to obtain a third high-frequency switching signal; The fourth voltage regulator, whose first input terminal is connected to the output terminal of the third voltage reference calculation module, and whose second input terminal is connected to the output terminal of the fourth analog-to-digital conversion module. The fourth voltage regulator is used to regulate the fourth voltage feedback digital signal and the third voltage reference digital signal to obtain a fourth high-frequency switching signal; The fifth voltage regulator, whose first input terminal is connected to the output terminal of the fourth voltage reference calculation module, and whose second input terminal is connected to the output terminal of the fifth analog-to-digital conversion module. The fifth voltage regulator is used to regulate the fifth voltage feedback digital signal and the fourth voltage reference digital signal to obtain a fifth high-frequency switching signal; The first PWM generator, whose input terminal is connected to the output terminal of the first current regulator. The first PWM generator is used to obtain a first switch tube logic signal according to the first high-frequency switching signal and transmit it to the first drive circuit; The second PWM generator, whose input terminal is connected to the output terminal of the second current regulator. The second PWM generator is used to obtain a second switch tube logic signal according to the second high-frequency switching signal and transmit it to the second drive circuit; A third PWM generator, whose input terminal is connected to the output terminal of the third voltage regulator. The third PWM generator is configured to obtain a third switch tube logic signal and a fourth switch tube logic signal according to the third high-frequency switching signal, and transmit them to a third driving circuit and a fourth driving circuit; A fourth PWM generator, whose input terminal is connected to the output terminal of the fourth voltage regulator. The fourth PWM generator is configured to obtain a fifth switch tube logic signal and a sixth switch tube logic signal according to the fourth high-frequency switching signal, and transmit them to a fifth driving circuit and a sixth driving circuit; A fifth PWM generator, whose input terminal is connected to the output terminal of the fifth voltage regulator. The fifth PWM generator is configured to obtain a seventh switch tube logic signal and an eighth switch tube logic signal according to the fifth high-frequency switching signal, and transmit them to a seventh driving circuit and an eighth driving circuit.

7. The buck-boost three-phase inverter control device according to claim 1, wherein In the step S2, the steps for the control and drive unit to regulate the first switch tube and / or the third switch tube include: Step S2.1: The control and drive unit controls the first switch tube to conduct, and the first closed loop conducts to enable the first filter inductor to store energy; Step S2.2: The first voltage feedback digital signal of the first filter capacitor is collected in real time and compared with the first voltage reference digital signal generated by the digital signal processor; Step S2.3: If the first voltage feedback digital signal is less than the first voltage reference digital signal, the control and drive unit controls the first switch tube to turn off and the third switch tube to perform high-frequency switching. The input power supply and the first filter inductor jointly charge the first filter capacitor, so that the first filter capacitor provides voltage for the positive half-cycle operation of the load, and the positive half-cycle regulation of the first output voltage is completed. The first output voltage is the voltage across the first load; Step S2.4: If the first voltage feedback digital signal is greater than the first voltage reference digital signal, the control and drive unit controls the third switch tube to perform high-frequency switching, so that the first freewheeling loop conducts, and the first filter capacitor releases energy, so as to complete the positive half-cycle regulation of the first output voltage.

8. The buck-boost three-phase inverter control device according to claim 7, characterized in that, In the step S3, the steps for the control and drive unit to regulate the third switch tube include: Step S3.1: The control and drive unit controls the first switch tube to turn off, and the third closed loop conducts to enable the third filter inductor to store energy; Step S3.2: The third voltage feedback digital signal is collected in real time and compared with the second voltage reference digital signal generated by the digital signal processor; Step S3.3: If the third voltage feedback digital signal is less than the second voltage reference digital signal, the control and drive unit controls the third switch tube to perform high-frequency switching, and the input power supply directly provides voltage for the positive half-cycle operation of the load, so as to complete the positive half-cycle regulation of the first output voltage; Step S3.4: If the third voltage feedback digital signal is greater than the second voltage reference digital signal, the control and drive unit controls the third switch tube to turn off, and the third freewheeling loop conducts, so as to complete the positive half-cycle regulation of the first output voltage.

9. The buck-boost three-phase inverter control device according to claim 8, characterized in that, In the step S4, the steps for the control and drive unit to regulate the second switch tube and / or the fourth switch tube include: Step S4.1: The control and drive unit controls the second switch tube to conduct, and the second closed loop conducts to enable the second filter inductor to store energy; Step S4.2: The second voltage feedback digital signal is collected in real time and compared with the first voltage reference digital signal generated by the digital signal processor; Step S4.3: If the second voltage feedback digital signal is less than the first voltage reference digital signal, the control and drive unit controls the second switch tube to turn off, and the fourth switch tube performs high-frequency switching, and the input power supply charges the second filter capacitor, so that the second filter capacitor provides voltage for the load to operate in the negative half cycle, so as to complete the negative half cycle regulation of the first output voltage; Step S4.4: If the second voltage feedback digital signal is greater than the first voltage reference digital signal, the control and drive unit controls the second switch tube to conduct, and the fourth switch tube performs high-frequency switching, so that the second freewheeling loop conducts, and the second filter capacitor releases energy, so as to complete the negative half cycle regulation of the first output voltage.

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