CN209267468U - Step-up three-leg inverter - Google Patents

Abstract

Boost three-leg inverter.The pressure resistance of power tube is generally in 800V or more usually in the system of 380V, and often calorific value is serious for the down tube of full bridge inverter, and the content of harmonic wave is also very high in power grid.The utility model composition includes power supply unit module (101), power supply unit module is connect with boost module (102) is recommended, boost module is recommended to connect with rectification filtering module (103), rectification filtering module is connect with three bridge arm inverter bridge modules (104), and three bridge arm inverter bridge modules are connect with LCL filter module (105)；Power supply unit module, recommend boost module, LCL filter module outputs signal to the A/D end of convert of DSP master controller (108) respectively, the PWM output port of DSP master controller respectively with isolation drive modules A (107), isolation drive module B(111) connect.The utility model is applied to boosting three-leg inverter.

Description

Step-up three-leg inverter

Technical field:

The utility model relates to a step-up three-bridge arm inverter.

Background technique:

The 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. Generally, the withstand voltage of the power tube is relatively high, usually in a 380V system. The withstand voltage is generally above 800V, and the lower tube of the long-term used full-bridge inverter circuit also has the function of current continuous flow, often the heat generated by the lower tube is serious, and when the system is connected to the power grid, the full-bridge inverter circuit and The grid exchanges energy, which increases the content of harmonics in the grid.

Therefore, how to provide an inverter circuit topology, reduce the cost of the circuit, improve the conversion efficiency and reduce the withstand voltage of the power tube while changing the freewheeling circuit is the focus of research in this field.

Attached Figure 2 shows the topology of the commonly used full-bridge inverter. In a 380V system, the withstand voltage of the power tube is generally above 800V, and the lower tube of the long-used full-bridge inverter circuit still has a continuous current flow. As a result, the calorific value of the lower tube is often serious, and when the converter 102 in Figure 1 is non-isolated, leakage current will be generated when the power supply load 101 is a solar panel, and a discharge circuit will be generated when the electrical equipment is shared with the ground.

Utility model content:

In order to overcome the above-mentioned problems existing in the prior art, the purpose of the utility model is to provide a step-up three-leg inverter.

Above-mentioned purpose realizes by following technical scheme:

A step-up three-leg inverter, which consists of: a power supply equipment module, the power supply equipment module is connected to a push-pull boost module, the push-pull boost module is connected to a rectification and filtering module, and the The rectifier filter module is connected to the three-arm inverter bridge module, the three-arm inverter bridge module is connected to the LCL filter module, and the LCL filter module is connected to the power supply load;

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

In the step-up three-leg inverter, the isolated drive module includes a signal conversion module, and the signal conversion module is respectively connected with the drive module, the voltage rectification and filtering module, and the DSP main controller, and the voltage rectification The filter module feeds back the rectified voltage to the IC control module through the coupling of the electrically isolated 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 filter module .

In the step-up three-leg inverter, the three-leg inverter bridge module includes a left bridge arm, an intermediate bridge arm, and a right bridge arm, and the left bridge arm includes a MOS transistor Q1 and a MOS transistor Q2, The middle bridge arm includes IGBT tube QT1, IGBT tube QT2, MOS tube Q3, and MOS tube Q4, and the right bridge arm includes MOS tube Q5 and MOS tube Q6; the pin L1 of the left bridge arm is connected to the positive input terminal of the capacitor, and the left bridge arm The L2 pin of the left bridge arm is connected to the negative input terminal of the capacitor, the L3 pin of the left bridge arm is connected to the M1 and M2 of the middle bridge arm, the L4 pin of the left bridge arm is connected to the M3 of the middle bridge arm, and the pin of the right bridge arm R1 is connected to the positive input terminal of the capacitor, the R2 pin of the right bridge arm is connected to the negative input terminal of the capacitor, the R3 pin of the right bridge arm is connected to the M4 and M5 of the middle bridge arm, the R4 pin of the right bridge arm is connected to the middle M6 connection of the bridge arm.

The beneficial effects of the utility model:

The utility model adopts the three-bridge arm inverter topology, which introduces two MOS tubes and two IGBT tubes on the basis of the traditional full-bridge inverter circuit. The power grid harmonics caused by current flow, and the withstand voltage of the two MOS transistors Q1 and Q6 at the lower end can be half of the withstand voltage value of the upper MOS transistors Q1 and Q5. The utility model has the advantages of simple topology control, low cost and low THD of unipolar modulation. At the same time, an isolated drive circuit is used, which completely isolates the DSP drive and the power part, which greatly reduces the difficulty of layout. The drive system only needs one power supply to meet the drive requirements, preventing the interference of the power part from entering the DSP drive part. , greatly improving the stability of long-term operation.

The utility model includes an inverter part of a three-bridge arm structure, a push-pull boost part, a rectification filter part, a power feedback part, an isolation drive part and an externally controlled DSP. The bridge arm inverter bridge outputs alternating current, the DSP sampling pin is connected to the power sampling part, and the DSP respectively outputs PWM driving waveforms to the isolation drive circuit, and the push-pull boost circuit and the three-arm inverter are controlled by the isolation and power amplification of the isolation drive circuit. Transformer power tube. The utility model reduces the withstand voltage of the lower tube, reduces the loss by changing the freewheeling circuit of the inverter, reduces the output voltage ripple, improves the system efficiency, and improves the system stability.

Description of drawings:

Accompanying drawing 1 is the functional block diagram of the inverter circuit of the present utility model.

Accompanying drawing 2 is the existing H4 single-phase inverter circuit diagram.

Accompanying drawing 3 is the circuit schematic diagram of the utility model three bridge arm inverter bridge.

Accompanying drawing 4 is the schematic diagram of the current flow when the positive half cycle capacitor of the three-arm inverter bridge of the present invention provides electric energy to the load.

Accompanying drawing 5 is the schematic diagram of the current flow direction of the three-arm inverter bridge of the present invention during positive half cycle freewheeling.

Accompanying drawing 6 is the schematic diagram of the current flow when the negative half cycle capacitor of the three-arm inverter bridge of the utility model provides electric energy to the load.

Accompanying drawing 7 is the schematic diagram of the current flow direction during negative half-cycle freewheeling of the three-arm inverter bridge of the present invention.

Accompanying drawing 8 is the principle block diagram of the isolation drive of the isolation drive module of the present invention.

Accompanying drawing 9 is the operation work flowchart of the present utility model.

Detailed ways:

Example 1:

A step-up three-leg inverter, which consists of: a power supply equipment module, the power supply equipment module is connected to a push-pull boost module, the push-pull boost module is connected to a rectification and filtering module, and the The rectifier filter module is connected to the three-arm inverter bridge module, the three-arm inverter bridge module is connected to the LCL filter module, and the LCL filter module is connected to the power supply load;

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

Power supply equipment module 101: connect batteries with a voltage range of 12V to 48V, solar panels or other low-voltage power sources into the power supply equipment module, part of the power supply equipment module will be converted into 15V control system power supply voltage and input power for isolated drive, and the other part will supply power The device module supplies the voltage to the boost topology.

Push-pull boost module 102: Convert the voltage provided by the power supply equipment module through the drive output of the DSP to convert low-voltage direct current into high-voltage alternating current, and completely electrically isolate the low-voltage direct current part and the high-voltage alternating current part.

Rectification and filtering module 103: convert high-voltage alternating current to direct current through fast recovery diode and filter capacitor to ensure the stability of direct current power supply.

The three-arm inverter bridge module 104: the direct current is generated through the DSP drive and the output of the isolation drive is used to conduct the respective bridge arms, and convert the direct current into the required high-frequency alternating current.

Filtering module 105: the high-frequency alternating current is filtered by the LCL low-pass filter to filter out the high-frequency harmonics, and output a sinusoidal alternating current signal.

Power supply load 106: the alternating current generated by the inverter can be directly connected to the grid to provide electric energy or connected to electric equipment for use.

Isolation drive module A107 and isolation drive module B111: drive the drive waveform input by DSP and convert the voltage and power to the corresponding power transistors of the three bridge arms for driving.

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

Data communication module 109: FPGA is mainly responsible for data communication, realizes remote data interaction, and improves DSP operation processing speed.

Host computer module 110: Remotely monitor and control the output status of the inverter through the host computer to realize the human-computer interaction function.

Example 2:

According to the step-up three-leg inverter described in Embodiment 1, the isolated 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 described above feeds back the rectified voltage to the IC control module through the coupling of electrically isolated signals, and the IC control module is connected to the power conversion circuit module, and the power conversion circuit module is connected to the voltage Rectifier filter module connection.

Figure 8 is a block diagram of the isolation drive, including:

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

The power conversion module 302: controls the power part through the output of PWM, and excites and demagnetizes the transformer through high-frequency PWM.

Voltage rectification part 303: rectifies and filters the voltage and current coupled by the transformer, and converts it into +15V, 0V, -15V DC voltage.

Isolated feedback part 304: feeds back the rectified voltage to the main control IC module through the coupling of electrically isolated signals, and stabilizes the voltage from there.

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

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 transistor or the base and emitter of the IGBT transistor.

Example 3:

According to the step-up three-leg inverter described in Embodiment 1 or 2, the three-leg inverter bridge module includes a left bridge arm, an intermediate bridge arm and a right bridge arm, and the left bridge arm includes a MOS tube Q1, MOS tube Q2, the middle bridge arm includes IGBT tube QT1, IGBT tube QT2, MOS tube Q3, MOS tube Q4, the right bridge arm includes MOS tube Q5, MOS tube Q6; the pin L1 of the left bridge arm and the positive input of the capacitor Terminal connection, the L2 pin of the left bridge arm is connected to the negative input terminal of the capacitor, the L3 pin of the left bridge arm is connected to the M1 and M2 of the middle bridge arm, the L4 pin of the left bridge arm is connected to the M3 of the middle bridge arm, The pin R1 of the right bridge arm is connected to the positive input terminal of the capacitor, the R2 pin of the right bridge arm is connected to the negative input terminal of the capacitor, the R3 pin of the right bridge arm is connected to the M4 and M5 of the middle bridge arm, and the right bridge arm The R4 pin is connected to the M6 of the middle bridge arm.

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

Example 4:

In the step-up regulation method of the above-mentioned step-up three-leg inverter, the power supply equipment is connected to a high-frequency switch boost circuit, and then connected to the three-leg inverter bridge through a rectification and filtering circuit, and finally connected to the grid or load;

The battery push-pull boost circuit passes through the rectification and filtering 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 driving waveforms to the isolation driving circuit respectively. After the isolation and isolation of the isolation driving circuit The power amplifier controls the push-pull boost circuit and the power tube of the three-arm inverter bridge;

The pre-feedback terminal of the main control DSP collects the output signal after rectification and filtering of the step-up transformer, and the post-feedback terminal collects the output voltage and current signals of the inverter and the grid-connected voltage signal, generates driving waveforms through feedback, and drives the waveforms to control the three bridge arms in real time The left bridge arm, the middle bridge arm and the right bridge arm of the inverter, the main control DSP communication terminal and the FPGA communication terminal are connected through 16bit data lines, and the FPGA is connected to the server and display interface through 4G wireless transmission.

Example 5:

According to the step-up regulation method of the step-up three-leg inverter described in Embodiment 4, the isolation drive module includes a control IC part, the IC part is connected to the input end of the power conversion part, and the output end of the power conversion part is connected to the waveform rectifier The input terminal, the output terminal of waveform rectification is connected to the input terminal of voltage feedback, the output terminal of voltage feedback is connected to the feedback pin of the control IC, the output terminal of waveform rectification is connected to the bipolar voltage receiving terminal of signal conversion at the same time, the signal conversion The input driving pin is connected to the DSP driving signal, and the output pin of the signal conversion is connected to the power switch tube. The driving signal of the DSP converts the unipolar power supply into a bipolar voltage driving output through the isolated driving module.

Figure 9 is a flow chart of running work, including:

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

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

Step 503: Make the DSP check the high-voltage DC signal to determine the voltage range of the high-voltage DC by rectifying and filtering the high-voltage and high-frequency AC.

Step 504: Use the interaction between the controller and the host computer to select grid-connected or offline operation of the system, determine the magnitude of the output current when selecting grid-connected, and determine the magnitude of the output voltage when operating independently.

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 required alternating current through the LCL filter circuit.

Claims (3)

1. a kind of boosting three-leg inverter, composition includes: power supply unit module, it is characterized in that: the power supply unit mould Block is connect with boost module is recommended, and the boost module of recommending is connect with rectification filtering module, the rectification filtering module It is connect with three bridge arm inverter bridge modules, the three bridge arm inverter bridge modules are connect with LCL filter module, the LCL filtering Module is connect with for electric loading；

The power supply unit module, it is described recommend boost module, the LCL filter module outputs signal to DSP respectively The A/D end of convert of master controller, the PWM output port of DSP master controller respectively with isolation drive modules A, isolation drive module B Connection, the isolation drive modules A connect with the boost module of recommending, the isolation drive module B with it is described The connection of three bridge arm inverter bridge modules, the DSP master controller connect with data communication module, the data communication module and Upper computer module connection, the isolation drive modules A are identical as the isolation drive module B structure.

2. boosting three-leg inverter according to claim 1, it is characterized in that: isolation drive module includes signal modulus of conversion Block, the signal conversion module are connect with drive module, voltage commutation filter module, the DSP master controller respectively, institute The voltage commutation filter module stated is by the coupling of electrical isolation signal by the Voltage Feedback after voltage commutation to IC control module In, the IC control module is connect with power conversion circuit module, the power conversion circuit module and the voltage Rectification filtering module connection.

3. boosting three-leg inverter according to claim 1 or 2, it is characterized in that: the three bridge arm inverter bridge modules Including left bridge arm, intermediate bridge arm and right bridge arm, the left bridge arm includes metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2, and intermediate bridge arm includes IGBT Pipe QT1, IGBT pipe QT2, metal-oxide-semiconductor Q3, metal-oxide-semiconductor Q4, right bridge arm include metal-oxide-semiconductor Q5, metal-oxide-semiconductor Q6；The pin L1 and electricity of left bridge arm The positive input terminal of appearance connects, and the L2 pin of left bridge arm is connected with the negative input end of capacitor, the L3 pin of left bridge arm and intermediate bridge arm M1, M2 connection, the M3 of the L4 pin of left bridge arm and intermediate bridge arm connects, the pin R1 of right bridge arm and the positive input terminal company of capacitor It connects, the R2 pin of right bridge arm is connected with the negative input end of capacitor, and the R3 pin of right bridge arm is connected with M4, M5 of intermediate bridge arm, right The R4 pin of bridge arm is connected with the M6 of intermediate bridge arm.