Boost three-leg inverter and boost regulation method

Abstract

Boost three-bridge-arm inverter and boost regulation method. Usually, in a 380V system, the withstand voltage of the power tube is generally above 800V, the lower tube of the full-bridge inverter circuit often generates serious heat, and the harmonic content in the power grid is also very high. The present invention comprises a power supply device module (101), the power supply device module is connected to a push-pull boost module (102), the push-pull boost module is connected to a rectifier filter module (103), the rectifier filter module is connected to a three-bridge-arm inverter bridge module (104), and the three-bridge-arm inverter bridge module is connected to an LCL filter module (105); the power supply device module, the push-pull boost module, and the LCL filter module respectively output signals to the A / D conversion end of the DSP main controller (108), and the PWM output port of the DSP main controller is respectively connected to an isolation drive module A (107) and an isolation drive module B (111). The present invention is applied to a boost three-bridge-arm inverter.

Description

Technical Field

[0001] The invention relates to a boost three-bridge-arm inverter and a boost regulation method. Background Art

[0002] An inverter is a device that converts direct current into alternating current. It is often used in active filters, reactive power compensators, and high-voltage frequency conversion devices. The power tubes selected generally have a relatively high withstand voltage. Usually in a 380V system, the withstand voltage of the power tube is generally above 800V. In addition, the lower tube of the full-bridge inverter circuit often used also has the function of current follow-up. The lower tube often generates a lot of heat. When the system is connected to the power grid, the full-bridge inverter circuit and the power grid exchange energy, which increases the harmonic content in the power grid.

[0003] Therefore, how to provide an inverter circuit topology that can reduce circuit costs, improve conversion efficiency, reduce the withstand voltage of the power tube and change the freewheeling loop is the research focus in this field.

[0004] Attached Figure 2 The content displayed is the commonly used full-bridge inverter topology. In a 380V system, the withstand voltage of the power tube is generally above 800V, and the lower tube of the full-bridge inverter circuit often used also has the function of current follow-up, which often generates a lot of heat and Figure 1 When the converter 102 is non-isolated, leakage current will be generated when the power supply load 101 is a solar panel, and a discharge loop will be generated when the electrical equipment shares a common ground. Summary of the invention

[0005] In order to overcome the above problems existing in the prior art, an object of the present invention is to provide a boost three-bridge-arm inverter and a boost regulation method.

[0006] The above purpose is achieved through the following technical solutions:

[0007] A boost three-bridge-arm inverter, comprising: a power supply device module, the power supply device module is connected to a push-pull boost module, the push-pull boost module is connected to a rectifier filter module, the rectifier filter module is connected to a three-bridge-arm inverter bridge module, the three-bridge-arm inverter bridge module is connected to an LCL filter module, and the LCL filter module is connected to a power supply load;

[0008] The power supply equipment module, the push-pull boost module, and the LCL filter module respectively output signals to the A / D conversion end of the DSP main controller. The PWM output port of the DSP main controller is respectively connected to the isolation drive module A and the isolation drive module B. The isolation drive module A is connected to the push-pull boost module, and the isolation drive module B is connected to the three-arm inverter bridge module. The DSP main controller is connected to the data communication module, and the data communication module is connected to the host computer module. The isolation drive module A has the same structure as the isolation drive module B.

[0009] The boost three-arm inverter, the isolation drive module includes a signal conversion module, the signal conversion module is respectively connected to the drive module, the voltage rectification and filtering module, and the DSP main controller, the voltage rectification and filtering module feeds back the rectified voltage to the IC control module through the coupling of the electrical isolation signal, the IC control module is connected to the power conversion circuit module, and the power conversion circuit module is connected to the voltage rectification and filtering module.

[0010] The boost three-bridge-arm inverter, the three-bridge-arm inverter bridge module includes a left bridge arm, a middle bridge arm and a right bridge arm, the left bridge arm includes MOS tubes Q1 and Q2, the middle bridge arm includes IGBT tubes QT1, QT2, MOS tubes Q3 and Q4, and the right bridge arm includes MOS tubes Q5 and Q6;

[0011] The drain pin L1 of the left bridge arm MOS tube Q1 is connected to the positive input end of the capacitor, and the source pin L2 of the left bridge arm MOS tube Q2 is connected to the negative input end of the capacitor;

[0012] The source pin L3 of the MOS tube Q1 of the left bridge arm is connected to the drain pin M1 of the MOS tube Q3 of the middle bridge arm and the collector pin M2 of the IGBT tube QT2 of the middle bridge arm;

[0013] The drain L4 pin of the MOS tube Q2 of the left bridge arm is connected to the M3 of the middle bridge arm, and the M3 is simultaneously connected to the emitter pin of the IGBT tube QT2 of the middle bridge arm and the source of the MOS tube Q4 of the middle bridge arm;

[0014] The drain pin R1 of the MOS tube Q5 of the right bridge arm is connected to the positive input end of the capacitor, and the source pin R2 of the MOS tube Q6 of the right bridge arm is connected to the negative input end of the capacitor;

[0015] The source R3 pin of the right bridge arm MOS tube Q5 is connected to the collector pin M4 of the middle bridge arm IGBT tube QT1 and the drain M5 of the middle bridge arm MOS tube Q4, and the drain R4 pin of the right bridge arm MOS tube Q6 is connected to M6, and M6 is simultaneously connected to the source of the middle bridge arm MOS tube Q3 and the emitter pin of the middle bridge arm IGBT tube QT1;

[0016] The host computer module is connected, and the isolation drive module A and the isolation drive module B have the same structure.

[0017] In the boost regulation method of the boost three-bridge-arm inverter, the power supply device is connected to a high-frequency switch boost circuit, and then connected to the three-bridge-arm inverter bridge through a rectifier filter circuit and finally connected to the grid or load;

[0018] The battery push-pull boost circuit passes through the rectifier and filter circuit and finally outputs AC power through the three-arm inverter bridge. The DSP sampling pin is connected to the power sampling part, and the DSP outputs PWM drive waveforms to the isolation drive circuit respectively. After isolation and power amplification of the isolation drive circuit, the power tubes of the push-pull boost circuit and the three-arm inverter bridge are controlled;

[0019] The front feedback end of the main control DSP collects the output signal after rectification and filtering of the boost transformer, and the rear feedback end collects the inverter output voltage and current signal and the grid-connected voltage signal. The drive waveform is generated through feedback. The drive waveform controls the left bridge arm, the middle bridge arm and the right bridge arm of the three-arm inverter in real time. The main control DSP communication end and the FPGA communication end are connected through a 16-bit data line, and the FPGA is connected to the server and display interface through 4G wireless transmission.

[0020] The boost regulation method of the boost three-arm inverter includes an isolation drive module including a control IC part, the IC part is connected to the input end of the power conversion part, the output end of the power conversion part is connected to the input end of the waveform rectifier, the output end of the waveform rectifier is connected to the input end of the voltage feedback, the output end of the voltage feedback is connected to the feedback pin of the control IC, the output end of the waveform rectifier is simultaneously connected to the bipolar voltage receiving end of the signal conversion, the input drive pin of the signal conversion is connected to the DSP drive signal, the output pin of the signal conversion is connected to the power switch tube, and the drive signal of the DSP converts the unipolar power supply into a bipolar voltage drive output through the isolation drive module. Beneficial Effects

[0021] The present invention adopts a three-bridge-arm inverter topology, which introduces two MOS tubes and two IGBT tubes on the basis of a traditional full-bridge inverter circuit. When a freewheeling loop is formed, the DC side and the grid side are isolated, which greatly reduces the grid harmonics caused by freewheeling, and the withstand voltage of the two MOS tubes Q1 and Q6 at the lower end can be half of the withstand voltage value of the upper MOS tubes Q1 and Q5. The present invention has the advantages of simple topology control, low cost, and low THD with unipolar modulation. At the same time, an isolation drive circuit is adopted, which completely isolates the drive and power parts of the DSP, greatly reducing the difficulty of layout. The drive system only needs one power supply to meet the drive requirements, preventing interference from the power part from entering the DSP drive part, and greatly improving the stability of long-term operation.

[0022] The present invention includes an inverter part, a push-pull boost part, a rectifier filter part, a power feedback part, an isolation drive part and an externally controlled DSP of a three-arm structure. The battery push-pull boost circuit passes through a rectifier filter circuit and finally outputs AC power through a novel three-arm inverter bridge. The DSP sampling pin is connected to the power sampling part, and the DSP outputs PWM drive waveforms to the isolation drive circuit respectively. The isolation drive circuit is isolated and the power amplification controls the push-pull boost circuit and the power tube of the three-arm inverter bridge. The present invention reduces the withstand voltage of the lower tube, reduces the loss by changing the inverter's freewheeling circuit, reduces the output voltage ripple, improves the system efficiency, and improves the system stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 It is a principle block diagram of the inverter circuit of the present invention.

[0024] Attached Figure 2 This is the existing H4 single-phase inverter circuit diagram.

[0025] Attached Figure 3 It is a circuit schematic diagram of the three-arm inverter bridge of the present invention.

[0026] Attached Figure 4 It is a schematic diagram of the current flow direction when the positive half-cycle capacitor of the three-arm inverter bridge of the present invention provides electric energy to the load.

[0027] Attached Figure 5 It is a schematic diagram of the current flow direction during the positive half-cycle freewheeling of the three-arm inverter bridge of the present invention.

[0028] Attached Figure 6 It is a schematic diagram of the current flow direction when the negative half-cycle capacitor of the three-arm inverter bridge of the present invention provides electric energy to the load.

[0029] Attached Figure 7 It is a schematic diagram of the current flow direction during the negative half-cycle freewheeling of the three-arm inverter bridge of the present invention.

[0030] Attached Figure 8It is a block diagram of the isolation driving principle of the isolation driving module of the present invention.

[0031] Attached Fig. 9 It is the operation workflow diagram of the present invention. DETAILED DESCRIPTION

[0032] Embodiment 1:

[0033] A boost three-bridge-arm inverter, comprising: a power supply device module, the power supply device module is connected to a push-pull boost module, the push-pull boost module is connected to a rectifier filter module, the rectifier filter module is connected to a three-bridge-arm inverter bridge module, the three-bridge-arm inverter bridge module is connected to an LCL filter module, and the LCL filter module is connected to a power supply load;

[0034] The power supply equipment module, the push-pull boost module, and the LCL filter module respectively output signals to the A / D conversion end of the DSP main controller. The PWM output port of the DSP main controller is respectively connected to the isolation drive module A and the isolation drive module B. The isolation drive module A is connected to the push-pull boost module, and the isolation drive module B is connected to the three-arm inverter bridge module. The DSP main controller is connected to the data communication module, and the data communication module is connected to the host computer module. The isolation drive module A has the same structure as the isolation drive module B.

[0035] Power supply device module 101: A battery, solar panel or other low-voltage power source with a voltage range of 12V to 48V is connected to the power supply device module. A part of the power supply device module will be converted into a 15V control system power supply voltage and an input power supply for the isolated drive, and another part of the power supply device module will provide the voltage to the boost topology.

[0036] The push-pull boost module 102 converts the voltage provided by the power supply device module into high-voltage alternating current through the driving output of the DSP, and completely electrically isolates the low-voltage direct current part from the high-voltage alternating current part.

[0037] Rectification and filtering module 103: converts high-voltage AC power into DC power through fast recovery diodes and filter capacitors to ensure the stability of DC power supply.

[0038] The three-bridge-arm inverter bridge module 104 generates direct current through the DSP drive and isolates the output of the drive to turn on each bridge arm, thereby converting the direct current into the required high-frequency alternating current.

[0039] LCL filter module 105: The high-frequency AC power is filtered out through LCL low-pass filtering to remove high-frequency harmonics and output a sinusoidal AC signal.

[0040] Power supply load 106: The alternating current generated by the inverter can be directly connected to the power grid to provide electrical energy or connected to electrical equipment for use.

[0041] Isolation drive module A107 and isolation drive module B111: drive the corresponding power tubes of the three bridge arms through the drive waveform input by DSP and the conversion of voltage and power.

[0042] Main controller DSP module 108: The DSP controls the power tube of the boost module and the switch tube in the inverter bridge arm by sampling the output voltage of the boost transformer and the output current and voltage of the inverter bridge.

[0043] Data communication module 109: FPGA is mainly responsible for data communication, realizing remote data interaction and improving DSP operation processing speed.

[0044] Host computer module 110: remotely monitors and controls the output state of the inverter through the host computer to realize the human-computer interaction function.

[0045] Embodiment 2:

[0046] According to the boost three-arm inverter described in Example 1, the isolation drive module includes a signal conversion module, and the signal conversion module is respectively connected to the drive module, the voltage rectification and filtering module, and the DSP main controller. The voltage rectification and filtering module feeds back the rectified voltage to the IC control module through the coupling of the electrical isolation signal. The IC control module is connected to the power conversion circuit module, and the power conversion circuit module is connected to the voltage rectification and filtering module.

[0047] Figure 8 This is the isolation driver principle block diagram, including:

[0048] Main control IC module 301: controls the output of PWM through IC, and performs chip enable, overvoltage, undervoltage, overcurrent and other controls.

[0049] Power conversion module 302: controls the power part through PWM output, and excites and demagnetizes the transformer through high-frequency PWM.

[0050] Voltage rectification part 303: The voltage and current coupled by the transformer are rectified and filtered, and converted into +15V, 0V, -15V DC voltage.

[0051] The isolated feedback part 304 feeds back the rectified voltage to the main control IC module through the coupling of the electrical isolation signal, thereby performing voltage stabilization.

[0052] Signal conversion module 305: Pins 1 and 2 of the signal module are connected to the PWM signal output by the DSP, pins 3, 4, and 5 of the signal module are connected to the +15V, 0V, and -15V DC voltages of the voltage rectification part, and pins 6 and 7 of the signal module are signal outputs.

[0053] Driving module 306: 1 and 2 of the driving module are connected to pins 6 and 7 of the signal module, and 3 and 4 of the driving module are respectively connected to the gate and drain of the MOS tube or the base and emitter of the IGBT tube.

[0054] Embodiment 3:

[0055] According to the boost three-bridge-arm inverter described in Example 1 or 2, the three-bridge-arm inverter bridge module includes a left bridge arm, a middle bridge arm and a right bridge arm, the left bridge arm includes MOS tubes Q1 and Q2, the middle bridge arm includes IGBT tubes QT1, QT2, MOS tubes Q3 and Q4, and the right bridge arm includes MOS tubes Q5 and Q6; the pin L1 of the left bridge arm is connected to the positive input end of the capacitor, the pin L2 of the left bridge arm is connected to the negative input end of the capacitor, the pin L3 of the left bridge arm is connected to M1 and M2 of the middle bridge arm, the pin L4 of the left bridge arm is connected to M3 of the middle bridge arm, the pin R1 of the right bridge arm is connected to the positive input end of the capacitor, the pin R2 of the right bridge arm is connected to the negative input end of the capacitor, the pin R3 of the right bridge arm is connected to M4 and M5 of the middle bridge arm, and the pin R4 of the right bridge arm is connected to M6 of the middle bridge arm.

[0056] Figure 4 is the direction of current flow in the positive half cycle, Figure 5 is the direction of the current freewheeling in the positive half cycle, Figure 6 is the direction of the negative half-cycle current, Figure 7 is the direction of the freewheeling current in the negative half cycle. Q1, Q2, Q3, Q4, Q5 and Q6 are high-frequency PWM control signals, and QT1 and QT2 are trigger signals for the synchronous output voltage frequency. Figure 4 As shown, the current flows through 301a, Q1, LS1, 302, LS2, QT1, Q5, Q6 and 301b in sequence. When the power tubes Q1 and Q6 are turned off, as shown in FIG. Figure 5 As shown, the positive half-cycle freewheeling path flows through Q3, LS1, 302, LS2 and QT1 in sequence. Compared with the full-bridge inverter, the positive half-cycle freewheeling loop is improved. Figure 6 As shown, it flows through 301a, Q5, LS2, 302, LS1, QT2, Q2 and 301b in sequence. When the power tubes Q5 and Q2 are turned off, as shown in FIG. Figure 7 As shown, the negative half-cycle freewheeling path flows through Q4, LS2, 302, LS1 and QT2 in sequence, and the negative half-cycle freewheeling loop is improved compared with the full-bridge inverter.

[0057] Embodiment 4:

[0058] In the boost regulation method of the boost three-bridge-arm inverter, the power supply device is connected to a high-frequency switch boost circuit, and then connected to the three-bridge-arm inverter bridge through a rectifier filter circuit and finally connected to the grid or load;

[0059] The battery push-pull boost circuit passes through the rectifier and filter circuit and finally outputs AC power through the three-arm inverter bridge. The DSP sampling pin is connected to the power sampling part, and the DSP outputs PWM drive waveforms to the isolation drive circuit respectively. After isolation and power amplification of the isolation drive circuit, the power tubes of the push-pull boost circuit and the three-arm inverter bridge are controlled;

[0060] The front feedback end of the main control DSP collects the output signal after rectification and filtering of the boost transformer, and the rear feedback end collects the inverter output voltage and current signal and the grid-connected voltage signal. The drive waveform is generated through feedback. The drive waveform controls the left bridge arm, the middle bridge arm and the right bridge arm of the three-arm inverter in real time. The main control DSP communication end and the FPGA communication end are connected through a 16-bit data line, and the FPGA is connected to the server and display interface through 4G wireless transmission.

[0061] Embodiment 5:

[0062] According to the boost regulation method of the boost three-arm inverter described in Example 4, the isolation drive module includes a control IC part, the IC part is connected to the input end of the power conversion part, the output end of the power conversion part is connected to the input end of the waveform rectifier, the output end of the waveform rectifier is connected to the input end of the voltage feedback, the output end of the voltage feedback is connected to the feedback pin of the control IC, the output end of the waveform rectifier is also connected to the bipolar voltage receiving end of the signal conversion, the input drive pin of the signal conversion is connected to the DSP drive signal, the output pin of the signal conversion is connected to the power switch tube, and the DSP drive signal converts the unipolar power supply into a bipolar voltage drive output through the isolation drive module.

[0063] Fig. 9 To run the workflow diagram, include:

[0064] Step 501: Normal connection of the power supply device The DSP checks whether the voltage of the power supply device is normal, and supplies power to the primary side of the system through the power supply device.

[0065] Step 502: When the voltage of the power supply device is normal, the push-pull boost circuit is driven by the DSP to convert the low-voltage direct current into high-voltage and high-frequency alternating current.

[0066] Step 503: The DSP checks the high-voltage DC signal to determine the voltage range of the DC high voltage by rectifying and filtering the high-voltage and high-frequency AC power.

[0067] Step 504: using the interaction between the controller and the host computer, select whether the system is connected to the grid or operates offline, determine the magnitude of the output current when connected to the grid, and determine the magnitude of the output voltage when operating independently.

[0068] Step 505: Generate PWM waves through DSP calculation to drive the power tubes of the three-leg inverter, and convert the high-voltage direct current into the required alternating current through the LCL filter circuit.

Claims

1. A boost three-bridge-arm inverter, comprising: A power supply equipment module, characterized in that: the power supply equipment module is connected to a push-pull boost module, the push-pull boost module is connected to a rectifier filter module, the rectifier filter module is connected to a three-bridge arm inverter bridge module, the three-bridge arm inverter bridge module is connected to an LCL filter module, and the LCL filter module is connected to a power supply load; The power supply equipment module, the push-pull boost module, and the LCL filter module respectively output signals to the A / D conversion end of the DSP main controller, and the PWM output port of the DSP main controller is respectively connected to the isolation drive module A and the isolation drive module B, the isolation drive module A is connected to the push-pull boost module, the isolation drive module B is connected to the three-bridge arm inverter bridge module, the DSP main controller is connected to the data communication module, the data communication module is connected to the host computer module, and the isolation drive module A has the same structure as the isolation drive module B; The three-bridge-arm inverter bridge module includes a left bridge arm, a middle bridge arm and a right bridge arm. The left bridge arm includes MOS tubes Q1 and Q2, the middle bridge arm includes IGBT tubes QT1, QT2, MOS tubes Q3 and Q4, and the right bridge arm includes MOS tubes Q5 and Q6. The drain pin L1 of the left bridge arm MOS tube Q1 is connected to the positive input end of the capacitor, and the source pin L2 of the left bridge arm MOS tube Q2 is connected to the negative input end of the capacitor; The source pin L3 of the MOS tube Q1 of the left bridge arm is connected to the drain pin M1 of the MOS tube Q3 of the middle bridge arm and the collector pin M2 of the IGBT tube QT2 of the middle bridge arm; The drain L4 pin of the MOS tube Q2 of the left bridge arm is connected to the M3 of the middle bridge arm, and the M3 is simultaneously connected to the emitter pin of the IGBT tube QT2 of the middle bridge arm and the source of the MOS tube Q4 of the middle bridge arm; The drain pin R1 of the MOS tube Q5 of the right bridge arm is connected to the positive input end of the capacitor, and the source pin R2 of the MOS tube Q6 of the right bridge arm is connected to the negative input end of the capacitor; The source R3 pin of the right bridge arm MOS tube Q5 is connected to the collector pin M4 of the middle bridge arm IGBT tube QT1 and the drain M5 of the middle bridge arm MOS tube Q4, and the drain R4 pin of the right bridge arm MOS tube Q6 is connected to M6, and M6 is simultaneously connected to the source of the middle bridge arm MOS tube Q3 and the emitter pin of the middle bridge arm IGBT tube QT1.

2. The boost three-bridge-arm inverter according to claim 1, characterized in that: The isolation driving module includes a signal conversion module, which is respectively connected to the driving module, the voltage rectification and filtering module, and the DSP main controller. The voltage rectification and filtering module feeds back the rectified voltage to the IC control module through the coupling of the electrical isolation signal. The IC control module is connected to the power conversion circuit module, and the power conversion circuit module is connected to the voltage rectification and filtering module.

3. A boost regulation method for a boost three-leg inverter according to any one of claims 1-2, characterized in that: The power supply equipment is connected to the high-frequency switch boost circuit, then connected to the three-arm inverter bridge through the rectifier filter circuit and finally connected to the grid or load; The battery push-pull boost circuit passes through the rectifier and filter circuit and finally outputs AC power through the three-arm inverter bridge. The DSP sampling pin is connected to the power sampling part, and the DSP outputs PWM drive waveforms to the isolation drive circuit respectively. After isolation and power amplification of the isolation drive circuit, the power tubes of the push-pull boost circuit and the three-arm inverter bridge are controlled; The front feedback end of the main control DSP collects the output signal after rectification and filtering of the boost transformer, and the rear feedback end collects the inverter output voltage and current signal and the grid-connected voltage signal. The drive waveform is generated through feedback. The drive waveform controls the left bridge arm, the middle bridge arm and the right bridge arm of the three-arm inverter in real time. The main control DSP communication end and the FPGA communication end are connected through a 16-bit data line, and the FPGA is connected to the server and display interface through 4G wireless transmission.

4. The boost regulation method of the boost three-bridge-arm inverter according to claim 3 is characterized in that: The isolation drive module includes a control IC part, the IC part is connected to the input end of the power conversion part, the output end of the power conversion part is connected to the input end of the waveform rectifier, the output end of the waveform rectifier is connected to the input end of the voltage feedback, the output end of the voltage feedback is connected to the feedback pin of the control IC, and the output end of the waveform rectifier is also connected to the bipolar voltage receiving end of the signal conversion. The input drive pin of the signal conversion is connected to the DSP drive signal, and the output pin of the signal conversion is connected to the power switch tube. The DSP drive signal converts the unipolar power supply into a bipolar voltage drive output through the isolation drive module.

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