A pure sine wave inverter with DC input isolated by a high-frequency transformer and output

Abstract

This invention provides a pure sine wave inverter with DC input isolated by a high-frequency transformer and output, comprising an energy storage inductor current sampling circuit, a filter inductor current sampling circuit, an output sampling comparison and overcurrent / overvoltage protection circuit, an inverter input / output main circuit, and an isolation amplifier circuit. The inverter input / output main circuit is connected to the energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent / overvoltage protection circuit, and the isolation amplifier circuit, respectively. The energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent / overvoltage protection circuit, and the isolation amplifier circuit are all connected to an external STM32F103RCT6 microcontroller. This invention features a reasonable structural design, stable and reliable operation, effectively reduces energy consumption and heat dissipation requirements, and offers good compatibility, high safety, and flexibility.

Description

Technical Field

[0001] This utility model relates to the field of electrical technology, specifically to a pure sine wave inverter with DC input isolated by a high-frequency transformer and output. Background Technology

[0002] Currently, mainstream inverters employ soft-switching technology at the output, but the output power components have not yet truly achieved zero-voltage turn-on and zero-voltage turn-off. Soft-switching technology significantly reduces switching losses and electromagnetic interference (EMI) by achieving zero-voltage turn-on (ZVS) or zero-current turn-off (ZCS) during the switching transition. However, it still has the following key drawbacks:

[0003] Excessive peak resonant voltage: The resonant process in soft-switching circuits often results in peak voltages that are more than twice the input voltage, which increases the withstand voltage requirements of switching devices (such as IGBTs or MOSFETs), thereby increasing device cost and failure risk.

[0004] Increased circuit complexity and cost: Additional resonant components (such as inductors and capacitors) are required, increasing the cost of hard switching solutions by about 20%, and making PCB layout and heat dissipation design more difficult.

[0005] High sensitivity to resonant parameters: Resonant network parameters (such as inductance and capacitance values) need to be precisely matched, are prone to failure under light loads (such as ZVS cannot be achieved), and are significantly affected by parasitic parameters, making debugging and maintenance complex.

[0006] Performance degradation under specific loads: The soft-switching effect weakens under light load conditions, and switching losses may rebound; at the same time, improper dead-time control will lead to duty cycle loss and reduce power density.

[0007] High-frequency applications are limited: Although higher switching frequencies (e.g., >500kHz) are supported, resonant losses and thermal management challenges limit efficiency gains in high-power scenarios (e.g., inverters), especially before the widespread adoption of SiC / GaN devices.

[0008] In conclusion, it is necessary to further improve the existing technology. Utility Model Content

[0009] To address the technical problems existing in the background art mentioned above, this utility model proposes a pure sine wave inverter with DC input isolated by a high-frequency transformer. Its structure is reasonably designed, stable and reliable in use, and can effectively reduce energy consumption and heat dissipation requirements. It also has good compatibility, high safety and good flexibility.

[0010] To solve the above-mentioned technical problems, this utility model provides a pure sine wave inverter with DC input isolated by a high-frequency transformer and output, which includes an energy storage inductor current sampling circuit, a filter inductor current sampling circuit, an output sampling comparison and overcurrent and overvoltage protection circuit, an inverter input and output main circuit, and an isolation amplifier circuit;

[0011] The energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent and overvoltage protection circuit, and the isolation amplifier circuit are all electrically connected to the peripheral microcontroller STM32F103RCT6.

[0012] The inverter input and output main circuits are respectively electrically connected to the energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent and overvoltage protection circuit, and the isolation amplifier circuit.

[0013] The isolation amplifier circuit includes four isolation amplifier chips; the isolation amplifier chips receive the square wave signal output by the microcontroller STM32F103RCT6 of the peripheral device, and after isolating and amplifying the square wave signal, output it to the control electrode of the switching component MOS transistor of the inverter input and output main circuit.

[0014] The energy storage inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device;

[0015] The filter inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device;

[0016] The output sampling comparison and overcurrent / overvoltage protection circuit is used to receive the AC power output from the main output circuit of the inverter, compare it with the sinusoidal signal voltage, and then send the comparison result to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device after voltage division.

[0017] The DC input is isolated by a high-frequency transformer to output a pure sine wave inverter, wherein: the isolation amplifier circuit is composed of chip IC9 and chips IC13~IC15; chip IC9 and chips IC13~IC15 all adopt the isolation amplifier chip SI8235;

[0018] The IC9 chip is connected to a 5V power supply through pins 3 and 8, grounded through pins 4 and 5, connected to power supply V2+ through pin 16, connected to power supply V2- through pin 14, connected to power supply V1+ through pin 11, connected to power supply V1- through pin 9, connected to the output pin PB4 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PB3 of the STM32F103RCT6 microcontroller through pin 2.

[0019] The IC13 chip is grounded through pins 4, 5, 9 and 14, connected to a 12V power supply through pins 11 and 16, connected to the output pin PA8 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PC6 of the STM32F103RCT6 microcontroller through pin 2.

[0020] The IC14 chip is grounded through pins 4 and 5, connected to a 5V power supply through pins 3 and 8, connected to power supply V3+ through pins 11 and 16, connected to power supply V3- through pins 9 and 14, connected to the output pin PA2 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PA3 of the STM32F103RCT6 microcontroller through pin 2.

[0021] The IC15 chip is grounded through pins 4 and 5, connected to a 5V power supply through pins 3 and 8, connected to power supply V4+ through pins 11 and 16, connected to power supply V4- through pins 9 and 14, connected to the output pin PA0 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PA1 of the STM32F103RCT6 microcontroller through pin 2.

[0022] The DC input is isolated by a high-frequency transformer, resulting in a pure sine wave inverter. The inverter's main input / output circuit consists of field-effect transistors Q2-Q9, a high-frequency switching transformer T1, resistors R01-R08, R9, R17, R19-R28, R30-R32, energy storage inductors L4 and L7, differential-mode inductor L5, common-mode inductor L6, filter inductor L1, sampling inductors L7-L10 and L12, capacitor C8, filter capacitor C10, capacitor C11, capacitor C12, and electrolytic capacitor C30. All field-effect transistors Q2-Q9 are N-MOS type.

[0023] The drain of the field-effect transistor Q2 is connected to a 12V-400VDC power supply, and the drain is connected to the resistor R24, which in turn connects to pin 15 of the chip IC9. The source is connected to one end of the energy storage inductor L4; the other end of the energy storage inductor L4 is connected to one end of the primary winding of the high-frequency switching transformer T1; one end of the resistor R01 is connected to the source of the field-effect transistor Q2, and the other end is connected to the gate of the field-effect transistor Q2; the anode of the diode D2 is grounded, and the cathode is connected to the source of the field-effect transistor Q2; one end of the sampling inductor L8... The sampling inductor current sampling circuit is connected at one end, and the other end is connected to a +2.5V power supply. The drain of the field-effect transistor Q3 is connected to one end of the primary winding of the high-frequency switching transformer T1, the gate is connected to the resistor R26 and then to pin 15 of the chip IC13, and the source is grounded. One end of the resistor R02 is connected to the gate of the field-effect transistor Q3, and the other end is grounded. One end of the capacitor C8 is connected to the drain of the field-effect transistor Q3, and the other end is grounded. One end of the sampling inductor L9 is connected to the sampling inductor current sampling circuit, and the other end is connected to +2V.A 5V power supply; the cathode of the polarized capacitor C30 is grounded, and the anode is connected to a 12V-400VDC power supply; the source of the field-effect transistor Q4 is connected to one end of the energy storage inductor L7, the drain is connected to the 12V-400VDC power supply, and the gate is connected to the resistor R25 and then to pin 10 of the chip IC9; the other end of the energy storage inductor L7 is connected to the other end of the primary winding of the high-frequency switching transformer T1; one end of the resistor R03 is connected to the source of the field-effect transistor Q4, and the other end is connected to the gate of the field-effect transistor Q4; the diode... The anode of transistor D3 is grounded, and the cathode is connected to the source of the field-effect transistor Q4. The drain of the field-effect transistor Q5 is connected to the other end of the energy storage inductor L7, the source is grounded, and the gate is connected to the resistor R27 and then to pin 10 of the chip IC13. One end of the resistor R04 is connected to the gate of the field-effect transistor Q5, and the other end is grounded. One end of the capacitor C11 is connected to the drain of the field-effect transistor Q5, and the other end is grounded. The drain of the field-effect transistor Q6 is connected to one end of the secondary winding of the high-frequency switching transformer T1, and the source is connected to the resistor R04. Resistor R28 is connected to pin 15 of chip IC14; one end of resistor R05 is connected to the source of MOSFET Q6, and the other end is connected to the gate of MOSFET Q6; the source of MOSFET Q7 is connected to the source of MOSFET Q6, and its gate is connected to resistor R30, which in turn connects to pin 10 of chip IC14; one end of resistor R06 is connected to the source of MOSFET Q7, and the other end is connected to the gate of MOSFET Q7; the drain of MOSFET Q8 is connected to the high-frequency switching transformer. The other end of the secondary winding of device T1 has its gate connected to resistor R31 and then to pin 15 of chip IC15 via resistor R31; one end of resistor R07 is connected to the gate of field-effect transistor Q8, and the other end is connected to the source of field-effect transistor Q8; the source of field-effect transistor Q9 is connected to the source of field-effect transistor Q8, and its gate is connected to resistor R32 and then to pin 10 of chip IC15 via resistor R32; one end of resistor R08 is connected to the source of field-effect transistor Q9, and the other end is connected to the gate of field-effect transistor Q9.

[0024] One end of the sampling inductor L10 is connected to one end of resistor R88 in the sampling inductor current sampling circuit 1, and the other end is connected to a +2.5V power supply; one end of the sampling inductor L12 is connected to the sampling inductor current sampling circuit, and the other end is connected to a +2.5V power supply; one end of the filter inductor L1 is connected to the drain of the field-effect transistor Q7; one end of resistor R22 is connected to the other end of the filter inductor L1, and the other end is connected in series with resistors R21, R20, R19, and R23, and then connected to the center tap of the secondary winding of the high-frequency switching amplifier T1; the signal line at the output of the high-frequency switching amplifier T1 is also connected to the output sampling comparison and overcurrent / overvoltage protection circuit; the series connection point between resistors R19 and R23 is also connected to the output sampling comparison... The resistor R17 is connected to the overcurrent and overvoltage protection circuit 3; one end of the resistor R17 is connected to the signal line of the output terminal of the high-frequency switching amplifier T1, and the other end is connected to one end of one coil of the differential mode inductor L5 and the output sampling comparison and overcurrent and overvoltage protection circuit 3 respectively; the filter capacitor C10 is connected between one end of the two coils of the differential mode inductor L5, and the capacitor C12 is connected between the other ends of the two coils of the differential mode inductor L5; the forward signal line of the dual winding coil of the common mode inductor L6 is connected to the other end of the two coils of the differential mode inductor L5 respectively, and the reverse signal line of the dual winding coil of the common mode inductor L6 is connected to the live wire L and the neutral wire N respectively; the resistor R9 is connected between the reverse signal lines of the dual winding coil of the common mode inductor L6.

[0025] The DC input is isolated by a high-frequency transformer to output a pure sine wave inverter, wherein: the energy storage inductor current sampling circuit consists of chip IC16, resistors R80~R87, and diodes D6~D9; the chip IC16 is a TLV3502, which is connected to a +2.6V supply voltage through pins 2 and 4, a 5V supply voltage through pin 8, and grounded through pin 5; one end of resistor R80 is connected to one end of the sampling inductor L9, and the other end is connected to pin 3 of chip IC16; one end of resistor R81 is connected to one end of the sampling inductor L8, and the other end is connected to pin 1 of chip IC16; one end of resistor R82 is connected to a +2.5V supply voltage, and the other end is connected to pin 1 of chip IC16. Pin 1 of IC16 is connected to resistor R82, which is also connected in parallel with diodes D6 and D7. The anode of diode D6 is connected to a +2.5V power supply, and the cathode is connected to pin 1 of IC16. The anode of diode D7 is connected to pin 1 of IC16, and the cathode is connected to a +2.5V power supply. One end of resistor R83 is connected to a +2.5V power supply, and the other end is connected to pin 3 of IC16. Diodes D8 and D9 are also connected in parallel with resistor R83. The anode of diode D8 is connected to a +2.5V power supply, and the cathode is connected to pin 3 of IC16. The anode of diode D9 is connected to pin 3 of IC16, and the cathode is connected to a +2.5V power supply.

[0026] One end of resistor R84 is grounded, and the other end is connected in series with resistor R86 and then connected to pin 6 of chip IC16; the connection point between resistors R84 and R86 is connected to input pin PC4 of microcontroller STM32F103RCT6; one end of resistor R85 is grounded, and the other end is connected in series with resistor R87 and then connected to pin 7 of chip IC16; the connection point between resistors R85 and R87 is connected to input pin PC3 of microcontroller STM32F103RCT6.

[0027] The DC input is isolated by a high-frequency transformer and outputs a pure sine wave inverter, wherein: the filter inductor current sampling circuit is composed of chip IC1, resistors R88, R89, R94, R95, R103~R106, diodes D1, D10, D17 and D18.

[0028] The chip IC1 is model TLV3502. It is connected to a +2.6V supply voltage through pins 2 and 4, a 5V supply voltage through pin 8, and grounded through pin 5. One end of the resistor R88 is connected to the main input / output circuit of the inverter, and the other end is connected to pin 3 of the chip IC1. One end of the resistor R89 ​​is connected to one end of the sampling inductor L12, and the other end is connected to pin 1 of the chip IC1.

[0029] One end of resistor R94 is connected to a +2.5V power supply, and the other end is connected to pin 1 of chip IC1. Resistor R94 is also connected in parallel with diodes D1 and D10. The anode of diode D1 is connected to a +2.5V power supply, and the cathode is connected to pin 1 of chip IC1. The anode of diode D10 is connected to pin 1 of chip IC1, and the cathode is connected to a +2.5V power supply. One end of resistor R95 is connected to a +2.5V power supply, and the other end is connected to pin 3 of chip IC1. Resistor R95 is also connected in parallel with diodes D18 and D17. The anode of diode D17 is connected to a +2.5V power supply, and the cathode is connected to... The diode D18 is connected to pin 3 of IC1; the anode of the diode D18 is connected to pin 3 of IC1, and the cathode is connected to the +2.5V supply voltage; one end of resistor R103 is grounded, and the other end is connected in series with resistor R105 and then connected to pin 6 of IC1; the connection point between resistors R103 and R105 is connected to the input pin PC1 of the STM32F103RCT6 microcontroller; one end of resistor R104 is grounded, and the other end is connected in series with resistor R106 and then connected to pin 7 of IC1; the connection point between resistors R104 and R106 is connected to the input pin PC2 of the STM32F103RCT6 microcontroller.

[0030] The DC input is isolated by a high-frequency transformer and outputs a pure sine wave inverter, wherein: the output sampling comparison and overcurrent and overvoltage protection circuit consists of an overcurrent and overvoltage protection circuit and a sine wave output current sampling circuit and a sine wave output voltage sampling circuit connected to the overcurrent and overvoltage protection circuit;

[0031] The overcurrent and overvoltage protection circuit consists of chip IC2, resistors R107~R109, resistors R111~R114 and adjustable resistor R115;

[0032] The sinusoidal output voltage sampling circuit consists of chip IC3, resistors R10, R18, R13, R14 and capacitor C1.

[0033] The sinusoidal output current sampling circuit consists of chip IC4, resistors R11~R12, resistors R15~R16, and capacitors C3~C4.

[0034] The IC2 chip is a comparator chip TLV3502, with pin 5 grounded and pin 8 connected to a 5V power supply. One end of resistor R107 is connected to pin PA4, and the other end is connected to pins 1 and 4 of IC2. One end of resistor R111 is grounded, and the other end is connected in series with resistor R113 and then to pin 6 of IC2. The connection point between resistors R111 and R113 is connected to the input pin PB2 of the STM32F103RCT6 microcontroller. One end of resistor R112 is grounded, and the other end is connected in series with... The resistor R114 is connected to pin 7 of the IC2 chip; the series connection between the resistors R112 and R114 is connected to the input pin PC0 of the STM32F103RCT6 microcontroller; one end of the resistor R108 is connected to pin 5 of the IC2 chip, and the other end is connected to one end of the coil of the adjustable resistor R115; the other end of the coil of the adjustable resistor R115 is connected to the resistor R109 and then connected to a 5V power supply through the resistor R109; the tab of the adjustable resistor R115 is connected to pin 2 of the IC2 chip.

[0035] The chip IC3 is an isolation amplifier chip AMC1301. Its pin 1 is connected to power supply V5+, pin 4 to power supply V5-, pin 5 to power supply V6-, pin 8 to power supply V6+, and pin 3 is connected to resistor R10. One end of capacitor C1 is connected to pin 3 of chip IC2, and the other end is connected to pin 2 of chip IC2. One end of resistor R13 is connected to pin 2 of chip IC2, and the other end is connected to pin 6 of chip IC3. One end of resistor R14... Connect one end of the resistor R10 to the analog input pin PA5 of the STM32F103RCT6 microcontroller, and the other end to pin 7 of the IC3 chip; connect one end of the resistor R10 to pin 3 of the IC3 chip, and the other end to the center tap of the secondary winding of the high-frequency switching amplifier T1; connect one end of the resistor R18 to pin 2 of the IC3 chip, and the other end to the series connection point between the resistors R19 and R23; connect the two ends of the capacitor C2 to pins 2 and 3 of the IC3 chip, respectively.

[0036] The chip IC4 is an isolation amplifier chip AMC1301. Its pin 1 is connected to power supply V5+, pin 4 to power supply V5-, pin 5 to power supply V6-, and pin 8 to power supply V6+. One end of the resistor R12 is connected to pin 7 of the chip IC4, and the other end is connected to the analog input pin PB0 of the STM32F103RCT6 microcontroller. One end of the capacitor C4 is connected to the analog input pin PB0 of the STM32F103RCT6 microcontroller, and the other end is split into two paths, one of which is connected to the capacitor C4. Resistor R16 is connected to pin 6 of chip IC4, and another path is connected to pin 2 of chip IC2; one end of resistor R11 is connected to pin 3 of chip IC4, and the other end is connected to the series connection point between resistors R19 and R23; one end of resistor R15 is connected to pin 2 of chip IC4, and the other end is connected to the other end of resistor R17; one end of capacitor C3 is connected to pin 2 of chip IC4, and the other end is connected to pin 3 of chip IC4.

[0037] By adopting the above technical solution, this utility model has the following beneficial effects:

[0038] This new inverter design integrates high-frequency switching technology, synchronous rectification, and digital control, and has significant advantages in the following aspects:

[0039] (1) Energy efficiency and thermal management optimization

[0040] (1.1) Dual-tube synchronous rectification to reduce losses

[0041] Back-to-back MOSFETs replace traditional diodes for rectification, utilizing milliohm-level on-resistance to reduce the rectified voltage drop to below 0.1V (compared to about 0.7V for diodes), reducing conduction losses by more than 60%. Combined with primary control of quantitative charge injection in 5μs (and even shorter times are possible), precise delivery of secondary energy is achieved, reducing switching losses.

[0042] (1.2) High-frequency soft-switching technology

[0043] The 5μs-level charge injection cycle enables the switching transformer to operate at a high frequency (>100kHz). Combined with the zero-voltage switching (ZVS) condition of the MOSFET, the switching loss is significantly reduced, and the overall efficiency can reach over 98%.

[0044] (2) Improved output power quality

[0045] (2.1) Pure Sine Wave Synthesis

[0046] Using a software-generated 50Hz sine wave as a reference, the sine wave output is achieved by comparing and controlling the turn-on timing of back-to-back MOSFETs in real time. The output voltage amplitude is strictly proportional to the reference wave, achieving a high-purity sine wave with THD < 3%, which is compatible with sensitive loads such as medical equipment and motors.

[0047] (2.2) Dynamic voltage regulation capability

[0048] The output voltage is linearly adjusted by changing the reference waveform amplitude, and it can be adapted to 110V / 220V systems without hardware modifications, with a response speed of microseconds.

[0049] (3) Enhanced safety and reliability

[0050] (3.1) Electrical isolation design

[0051] The isolating switch transformer completely blocks the electrical connection between the DC side and the AC side, preventing DC faults from affecting the load;

[0052] (3.2) Symmetrical zero-line topology

[0053] Using the neutral line as the neutral line ensures symmetrical balance of the positive and negative half-waves of the output voltage, reduces the risk of common-mode interference, and improves equipment safety.

[0054] (3.3) Multiple protection mechanisms

[0055] The software monitors overvoltage / undervoltage status in real time and dynamically shuts off the input (cuts off charge injection when the reference voltage is overvoltage), combined with MOSFET short-circuit protection to prevent device damage.

[0056] This invention reduces energy consumption by 10% and heat dissipation requirements by 30% through synchronous rectification and quantitative charge injection; the waveform is synthesized by software closed-loop control of sine wave, which is compatible with 99% of electrical equipment and eliminates motor noise; the use of isolation transformer and symmetrical neutral line can avoid the risk of electric shock, extend equipment life and improve safety; the software adjustable amplitude / frequency is globally voltage adaptive, requiring no hardware modification and providing greater flexibility. Attached Figure Description

[0057] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is a block diagram illustrating the structural connection principle of the pure sine wave inverter with DC input isolated by a high-frequency transformer and output according to this utility model.

[0059] Figure 2 The circuit diagram shows the energy storage inductor current sampling circuit of the pure sine wave inverter with DC input isolated by a high-frequency transformer according to this utility model.

[0060] Figure 3 This is a circuit diagram of the filter inductor current sampling circuit of the pure sine wave inverter with DC input isolated by a high-frequency transformer according to this utility model;

[0061] Figure 4 The circuit diagram shows the output sampling comparison and overcurrent and overvoltage protection circuit of the pure sine wave inverter with DC input isolated by a high-frequency transformer according to this utility model.

[0062] Figure 5 This is a circuit diagram of the main input and output circuit of the inverter of the present invention, which is a pure sine wave inverter with DC input isolated by a high-frequency transformer.

[0063] Figure 6 This is a circuit diagram of the isolation amplifier circuit of the pure sine wave inverter with DC input isolated by a high-frequency transformer. Detailed Implementation

[0064] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0065] The present invention will be further explained below with reference to specific embodiments.

[0066] like Figure 1 As shown in the figure, this embodiment provides a pure sine wave inverter with DC input isolated by a high-frequency transformer and output, which includes an energy storage inductor current sampling circuit 1, a filter inductor current sampling circuit 2, an output sampling comparison and overcurrent and overvoltage protection circuit 3, an inverter input and output main circuit 4, and an isolation amplifier circuit 5.

[0067] The inverter's input and output main circuit 4 is connected to the energy storage inductor current sampling circuit 1, the filter inductor current sampling circuit 2, the output sampling comparison and overcurrent / overvoltage protection circuit 3, and the isolation amplifier circuit 5, respectively. The energy storage inductor current sampling circuit 1, the filter inductor current sampling circuit 2, the output sampling comparison and overcurrent / overvoltage protection circuit 3, and the isolation amplifier circuit 5 are also connected to the peripheral microcontroller STM32F103RCT6.

[0068] The isolation amplifier circuit contains four isolation amplifier chips. Each isolation amplifier chip receives the square wave signal output by the microcontroller STM32F103RCT6 of the peripheral device, performs isolation amplification on the square wave signal, and outputs it to the control electrode of the MOS transistor, the switching component of the inverter input / output main circuit.

[0069] This energy storage inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the peripheral microcontroller STM32F103RCT6.

[0070] This filter inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the peripheral microcontroller STM32F103RCT6.

[0071] The output sampling comparison and overcurrent / overvoltage protection circuit receives the AC power output from the inverter's main output circuit, compares it with a sinusoidal signal voltage, and then sends the comparison result to the signal input pin of the peripheral microcontroller STM32F103RCT6 after voltage division.

[0072] like Figure 2As shown, the energy storage inductor current sampling circuit 1 consists of chip IC16, resistors R80~R87, and diodes D6~D9. The IC16 chip is a TLV3502, connected to a +2.6V supply voltage via pins 2 and 4, a 5V supply voltage via pin 8, and grounded via pin 5. One end of resistor R80 is connected to the inverter input / output main circuit 4, and the other end is connected to pin 3 of chip IC16; one end of resistor R81 is connected to the inverter input / output main circuit 4, and the other end is connected to pin 1 of chip IC16. Resistor R82 has one end connected to a +2.5V power supply and the other end connected to pin 1 of chip IC16. Diodes D6 and D7 are connected in parallel with resistor R82. The anode of diode D6 is connected to the +2.5V power supply, and the cathode is connected to pin 1 of chip IC16. The anode of diode D7 is connected to pin 1 of chip IC16, and the cathode is connected to the +2.5V power supply. Resistor R83 has one end connected to a +2.5V power supply and the other end connected to pin 3 of chip IC16. Diodes D8 and D9 are connected in parallel with resistor R83. The anode of diode D8 is connected to the +2.5V power supply, and the cathode is connected to pin 3 of chip IC16. The anode of diode D9 is connected to pin 3 of chip IC16, and the cathode is connected to the +2.5V power supply. One end of resistor R84 is grounded, and the other end is connected in series with resistor R86 to pin 6 of chip IC16. The connection point between resistors R84 and R86 is connected to input pin PC4 of the microcontroller STM32F103RCT6. One end of resistor R85 is grounded, and the other end is connected in series with resistor R87 to pin 7 of chip IC16. The connection point between resistors R85 and R87 is connected to input pin PC3 of microcontroller STM32F103RCT6.

[0073] like Figure 3As shown, the filter inductor current sampling circuit 2 consists of chip IC1, resistors R88, R89, R94, R95, resistors R103~R106, diodes D1, D10, D17, and D18. Chip IC1 is a TLV3502, connected to a +2.6V supply voltage via pins 2 and 4, a 5V supply voltage via pin 8, and grounded via pin 5. One end of resistor R88 is connected to the inverter input / output main circuit 4, and the other end is connected to pin 3 of chip IC1; one end of resistor R89 ​​is connected to the inverter input / output main circuit 4, and the other end is connected to pin 1 of chip IC1. Resistor R94 has one end connected to a +2.5V power supply and the other end connected to pin 1 of chip IC1. Diodes D1 and D10 are connected in parallel with resistor R94. The anode of diode D1 is connected to the +2.5V power supply, and the cathode is connected to pin 1 of chip IC1. The anode of diode D10 is connected to pin 1 of chip IC1, and the cathode is connected to the +2.5V power supply. Resistor R95 has one end connected to a +2.5V power supply and the other end connected to pin 3 of chip IC1. Diodes D18 and D17 are connected in parallel with resistor R95. The anode of diode D17 is connected to the +2.5V power supply, and the cathode is connected to pin 3 of chip IC1. The anode of diode D18 is connected to pin 3 of chip IC1, and the cathode is connected to the +2.5V power supply. One end of resistor R103 is grounded, and the other end is connected in series with resistor R105 to pin 6 of chip IC1. The connection point between resistors R103 and R105 is connected to input pin PC1 of the STM32F103RCT6 microcontroller. One end of resistor R104 is grounded, and the other end is connected in series with resistor R106 to pin 7 of chip IC1. The connection point between resistors R104 and R106 is connected to input pin PC2 of the STM32F103RCT6 microcontroller.

[0074] like Figure 4 As shown, the output sampling comparison and overcurrent / overvoltage protection circuit 3 consists of a sinusoidal output current sampling circuit, a sinusoidal output voltage sampling circuit, and an overcurrent / overvoltage protection circuit.

[0075] The overcurrent and overvoltage protection circuits are connected to the sinusoidal output current sampling circuit and the sinusoidal output voltage sampling circuit, respectively.

[0076] The sine wave output current sampling circuit consists of chip IC4, resistors R11-R12, resistors R15-R16, and capacitors C3-C4; the sine wave output voltage sampling circuit consists of chip IC3, resistors R10, R18, R13, R14, and capacitor C1; the overcurrent and overvoltage protection circuit consists of chip IC2, resistors R107-R109, resistors R111-R114, and adjustable resistor R115. Resistors R11, R15, and capacitor C3 step down and current-limit the output sine wave signal before sending it to pins 2 and 3 of chip IC4. After isolation and amplification, the signal is output from pins 6 and 7. After current limiting by resistor R12 and filtering by capacitor C4, the signal is sent to the input pin PB0 of the STM32F103RCT6 microcontroller. The sine wave output voltage sampling circuit uses resistors R10 and R18, and capacitor C2 to step down and limit the current of the output sine wave signal before sending it to pins 2 and 3 of chip IC3. After isolation and amplification, the signal is output from pins 6 and 7. After current limiting by resistor R14 and filtering by capacitor C1, one path is sent to the analog input pin PA5 of the STM32F103RCT6 microcontroller, and the other path is sent to pin 3 of chip IC2 in the overcurrent and overvoltage protection circuit. The waveform is compared with the reference waveform at pin 4, processed by the internal circuit, and output from pin 6. After voltage division by resistors R113 and R111, the signal is sent to the input pin PB2 of the STM32F103RCT6 microcontroller as a voltage signal for chip logic processing.

[0077] like Figure 4 As shown, the IC2 chip is a comparator chip TLV3502, with pin 5 grounded and pin 8 connected to a 5V power supply; one end of resistor R107 is connected to pin PA4, and the other end is connected to pins 1 and 4 of IC2; one end of resistor R111 is grounded, and the other end is connected to pin 6 of IC2 via series with resistor R113; the connection point between resistors R111 and R113 is connected to the input pin PB2 of the STM32F103RCT6 microcontroller; one end of resistor R112 is grounded. The other end is connected to pin 7 of chip IC2 via a series resistor R114; the connection point between resistor R112 and resistor R114 is connected to the input pin PC0 of the microcontroller STM32F103RCT6 of the peripheral; one end of resistor R108 is connected to pin 5 of chip IC2, and the other end is connected to one end of the coil of adjustable resistor R115; the other end of the coil of adjustable resistor R115 is connected to resistor R109 and then connected to a 5V power supply through resistor R109; the tab of adjustable resistor R115 is connected to pin 2 of chip IC2.

[0078] like Figure 4As shown, chip IC3 is an isolation amplifier chip AMC1301. Its pin 1 is connected to power supply V5+, pin 4 is connected to power supply V5-, pin 5 is connected to power supply V6-, pin 8 is connected to power supply V6+, and pin 3 is connected to resistor R10. One end of capacitor C1 is connected to pin 3 of chip IC2, and the other end is connected to pin 2 of chip IC2. One end of resistor R13 is connected to pin 2 of chip IC2, and the other end is connected to pin 6 of chip IC3. One end of resistor R14 is connected to the analog input pin PA5 of microcontroller STM32F103RCT6, and the other end is connected to pin 7 of chip IC3. One end of resistor R10 is connected to pin 3 of chip IC3, and the other end is connected to the inverter input / output main circuit 4. One end of resistor R18 is connected to pin 2 of chip IC3, and the other end is connected to the inverter input / output main circuit 4. The two ends of capacitor C2 are connected to pins 2 and 3 of chip IC3, respectively.

[0079] like Figure 4 As shown, the model of the chip IC4 is AMC1301. Its pin 1 is connected to power supply V5+, pin 4 is connected to power supply V5-, pin 5 is connected to power supply V6-, and pin 8 is connected to power supply V6+. One end of the resistor R12 is connected to pin 7 of the chip IC4, and the other end is connected to the analog input pin PB0 of the STM32F103RCT6 microcontroller. One end of the capacitor C4 is connected to the analog input pin PB0 of the STM32F103RCT6 microcontroller, and the other end is split into two paths. One path is connected to resistor R16 and then to pin 6 of the chip IC4, and the other path is connected to pin 2 of the chip IC2. One end of the resistor R11 is connected to pin 3 of the chip IC4, and the other end is connected to the inverter input / output main circuit 4. One end of the resistor R15 is connected to pin 2 of the chip IC4, and the other end is connected to the inverter input / output main circuit 4. One end of the capacitor C3 is connected to pin 2 of the chip IC4, and the other end is connected to pin 3 of the chip IC4.

[0080] like Figure 6 As shown, the isolation amplifier circuit 5 is composed of chip IC9 and chips IC13~IC15; all of these chips IC9 and IC13~IC15 are isolation amplifier chips SI8235.

[0081] The IC9 chip is connected to a 5V power supply via pins 3 and 8, grounded via pins 4 and 5, connected to power supply V2+ via pin 16, connected to power supply V2- via pin 14, connected to power supply V1+ via pin 11, connected to power supply V1- via pin 9, connected to the output pin PB4 of the STM32F103RCT6 microcontroller via pin 1, and connected to the output pin PB3 of the STM32F103RCT6 microcontroller via pin 2.

[0082] The IC13 chip is grounded via pins 4, 5, 9, and 14; connected to a 12V power supply via pins 11 and 16; connected to the output pin PA8 of the STM32F103RCT6 microcontroller via pin 1; and connected to the output pin PC6 of the STM32F103RCT6 microcontroller via pin 2. The IC14 chip is grounded via pins 4 and 5; connected to a 5V power supply via pins 3 and 8; connected to power supply V3+ via pins 11 and 16; connected to power supply V3- via pins 9 and 14; connected to the output pin PA2 of the STM32F103RCT6 microcontroller via pin 1; and connected to the output pin PA3 of the STM32F103RCT6 microcontroller via pin 2.

[0083] The IC15 chip is grounded through pins 4 and 5, connected to a 5V power supply through pins 3 and 8, connected to power supply V4+ through pins 11 and 16, connected to power supply V4- through pins 9 and 14, connected to the output pin PA0 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PA1 of the STM32F103RCT6 microcontroller through pin 2.

[0084] like Figure 5As shown, the main input / output circuit 4 of the inverter consists of field-effect transistors Q2~Q9, high-frequency switching transformer T1, resistors R01~R08, resistor R9, resistor R17, resistors R19~R28, resistors R30~R32, filter inductor L1, energy storage inductor L4, energy storage inductor L7, differential mode inductor L5, common mode inductor L6, sampling inductors L7~L10, sampling inductor L12, capacitor C8, filter capacitor C10, capacitor C11, and polarized capacitor C30. The inductance of the primary and secondary windings of the high-frequency switching transformer T1 ranges from 0.01H to 100UH, adjusted according to the designed output power. Resistors R01-R08 have values ​​between 5KΩ and 10KΩ, R9 is 1MΩ, R17 is between 0.01Ω and 0.1Ω, R19-R22 have values ​​between 50KΩ and 100KΩ, R23 has a value between 100Ω and 1000Ω, and R24-R28 and R30-R32 have values ​​between 1Ω and 10Ω. The filter inductor L1... The inductance values ​​are between 100uH and 10MH. The energy storage inductors L4 and L7 have nearly identical inductance values, between 10uH and 100MH. The differential-mode inductor L5 and the common-mode inductor L6 have inductance values ​​between 1mH and 10mH. The sampling inductors L8, L9, L10, and L12 are wound only 1-3 turns in the magnetic ring, with inductance values ​​between 1uH and 20uH. Capacitors C8 and C11 have capacitance values ​​between 103 and 474 ohms, capacitors C10 and C12 have capacitance values ​​between 1uF and 20uF, and capacitor C30 has capacitance values ​​between 100uF and 500uF. All MOSFETs Q2 to Q9 are N-MOS type.

[0085] The drain of the field-effect transistor Q2 is connected to a 12V-400VDC power supply, and the drain is connected to resistor R24, which in turn connects to pin 15 of the isolation amplifier circuit 5. The source is connected to one end of the energy storage inductor L4; the other end of the energy storage inductor L4 is connected to one end of the primary winding of the high-frequency switching transformer T1; one end of resistor R01 is connected to the source of the field-effect transistor Q2, and the other end is connected to the gate of the field-effect transistor Q2; the anode of the diode D2 is grounded, and the cathode is connected to the source of the field-effect transistor Q2; one end of the sampling inductor L8 is connected to the energy storage inductor current sampling... One end of resistor R81 in sample circuit 1 is connected to a +2.5V power supply; the drain of the field-effect transistor Q3 is connected to one end of the primary winding of the high-frequency switching transformer T1, the gate is connected to resistor R26 and then to pin 15 of chip IC13 in the isolation amplifier circuit 5, and the source is grounded; one end of resistor R02 is connected to the gate of field-effect transistor Q3, and the other end is grounded; one end of capacitor C8 is connected to the drain of field-effect transistor Q3, and the other end is grounded; one end of sampling inductor L9 is connected to one end of resistor R80 in energy storage inductor current sampling circuit 1, and the other end is connected to +2V.5V power supply; the cathode of the polarized capacitor C30 is grounded, and the anode is connected to a 12V-400VDC power supply; the source of the field-effect transistor Q4 is connected to one end of the energy storage inductor L7, the drain is connected to the 12V-400VDC power supply, and the gate is connected to resistor R25 and then to pin 10 of the isolation amplifier circuit 5 chip IC9; the other end of the energy storage inductor L7 is connected to the other end of the primary winding of the high-frequency switching transformer T1; one end of the resistor R03 is connected to the source of the field-effect transistor Q4, and the other end is connected to the gate of the field-effect transistor Q4; the diode... The anode of transistor D3 is grounded, and the cathode is connected to the source of transistor Q4. The drain of transistor Q5 is connected to the other end of the energy storage inductor L7, the source is grounded, and the gate is connected to resistor R27, which in turn connects to pin 10 of the isolation amplifier circuit 5. One end of resistor R04 is connected to the gate of transistor Q5, and the other end is grounded. One end of capacitor C11 is connected to the drain of transistor Q5, and the other end is grounded. The drain of transistor Q6 is connected to one end of the secondary winding of the high-frequency switching transformer T1, and the source is connected to resistor R2. 8. Connect resistor R28 to pin 15 of IC14 in the isolation amplifier circuit 5; one end of resistor R05 is connected to the source of MOSFET Q6, and the other end is connected to the gate of MOSFET Q6; the source of MOSFET Q7 is connected to the source of MOSFET Q6, and the gate is connected to resistor R30, which in turn connects to pin 10 of IC14 in the isolation amplifier circuit 5; one end of resistor R06 is connected to the source of MOSFET Q7, and the other end is connected to the gate of MOSFET Q7; the drain of MOSFET Q8 is connected to the high-frequency switching transformer. The other end of the secondary winding of T1 is connected to the gate by resistor R31, which in turn connects to pin 15 of chip IC15 in the isolation amplifier circuit 5. One end of resistor R07 is connected to the gate of MOSFET Q8, and the other end is connected to the source of MOSFET Q8. The source of MOSFET Q9 is connected to the source of MOSFET Q8, and its gate is connected to resistor R32, which in turn connects to pin 10 of chip IC15 in the isolation amplifier circuit 5. One end of resistor R08 is connected to the source of MOSFET Q9, and the other end is connected to the gate of MOSFET Q9.

[0086] One end of the sampling inductor L10 is connected to one end of resistor R88 in the energy storage inductor current sampling circuit 1, and the other end is connected to a +2.5V power supply; one end of the sampling inductor L12 is connected to one end of resistor R89 ​​in the filter inductor current sampling circuit 2, and the other end is connected to a +2.5V power supply; one end of the filter inductor L1 is connected to the drain of the field-effect transistor Q7; one end of resistor R22 is connected to the other end of the filter inductor L1, and the other end is connected in series with resistors R21, R20, R19, and R23, and then connected to the center tap of the secondary winding of the high-frequency switching amplifier T1; the signal line at the output of the high-frequency switching amplifier T1 is also connected to the other end of resistor R10 in the output sampling comparison and overcurrent / overvoltage protection circuit 3; the series connection point between resistors R19 and R23 is also connected to the output sampling comparison and overcurrent / overvoltage protection circuit 3 respectively. The other ends of resistor R18 and resistor R11 in circuit 3 are connected; one end of resistor R17 is connected to the center tap of the secondary winding of high-frequency switching amplifier T1, and the other end is connected to one end of one coil of differential mode inductor L5 and the other end of resistor R15 in output sampling comparison and overcurrent and overvoltage protection circuit 3; the filter capacitor C10 is connected between one end of the two coils of differential mode inductor L5, and the capacitor C12 is connected between the other ends of the two coils of differential mode inductor L5; the forward signal line of the dual winding coil of common mode inductor L6 is connected to the other ends of the two coils of differential mode inductor L5, and the reverse signal line of the dual winding coil of common mode inductor L6 is connected to the live wire L and the neutral wire N; resistor R9 is connected between the reverse signal lines of the dual winding coil of common mode inductor L6.

[0087] like Figure 1-5 As shown, the working principle of this utility model is as follows:

[0088] The square wave signals output from pins PA8 and PC6 of the peripheral microcontroller STM32F103RCT6 are sent to pins 1 and 2 of the IC13 isolation amplifier chip SI8235, respectively. After amplification, the signals are limited by current-limiting resistors R26 and R27 and then sent to the gates of field-effect transistors Q3 and Q5 to drive them to turn on and off.

[0089] The high and low level signals output from pins PB4 and PB3 of the peripheral microcontroller STM32F103RCT6 are sent to pins 1 and 2 of the IC9 isolation amplifier chip SI8235, respectively. After amplification, the signals are limited by current-limiting resistors R26 and R27 and then sent to the gates of field-effect transistors Q3 and Q5 to drive them to turn on and off.

[0090] The high and low level signals output from the PA2 and PA3 pins of the STM32F103RCT6 microcontroller are sent to pins 1 and 2 of the IC14 isolation amplifier chip SI8235, respectively. After amplification, the signals are limited by current-limiting resistors R26 and R27 and then sent to the gates of MOSFETs Q3 and Q5 to drive MOSFETs Q3 and Q5 to turn on and off.

[0091] The high and low level signals output from the PA0 and PA1 pins of the STM32F103RCT6 microcontroller are sent to pins 1 and 2 of the IC15 isolation amplifier chip SI8235, respectively. After amplification, the signals are limited by current-limiting resistors R26 and R27 and then sent to the gates of MOSFETs Q3 and Q5 to drive MOSFETs Q3 and Q5 to turn on and off.

[0092] The switching on and off of the field-effect transistor Q2 is controlled by pin PB4 of the STM32F103RCT6 microcontroller. The logic output is controlled by the signals from pins PC0 and PB2 of the STM32F103RCT6 microcontroller. After the inverter starts, when pin PC0 of the STM32F103RCT6 is high and pin PB2 is low, or when pin PC0 is low and pin PB2 is high, pin PB4 outputs a high level; when pins PC0 and PB2 of the STM32F103RCT6 are both high, or when pins PC0 and PB2 are both low, pin PB4 outputs a low level.

[0093] The switching on and off of the field-effect transistor Q4 is controlled by pin PB3 of the STM32F103RCT6 microcontroller. The logic output is controlled by the output signals of pins PC6 and PB4 of the STM32F103RCT6 microcontroller. When pins PC6 and PB4 are high, pin PB3 outputs a high level; when pin PC6 is high and pin PB4 is low, pin PB3 outputs a low level.

[0094] The peripheral microcontroller STM32F103RCT6 continuously outputs square wave waveforms with the same frequency, a duty cycle of 51:49 (51% high level and 49% low level in one cycle), and a phase difference of 50 duty cycles through pins PA8 and PC6. It controls the on and off of field-effect transistors Q3 and Q5 to supply electrical energy to both ends of the primary winding of the high-frequency switching transformer T1, thereby realizing the transfer of energy to the secondary winding.

[0095] The center tap of the secondary winding of the high-frequency switching transformer T1 is generally called the neutral line, also known as the zero line. The field-effect transistors Q6 and Q7 at the upper end of the secondary winding of the high-frequency switching transformer T1 and the field-effect transistors Q8 and Q9 at the lower end of the secondary winding are connected to terminal 1 of the filter inductor L1 to form a 50Hz AC output circuit. The 50Hz sinusoidal AC waveform with an amplitude of ±1.65V output from pin PA4 of the STM32F103RCT6 microcontroller is applied to pins 1 and 4 of chip IC2. The 1.65V voltage generated by the voltage divider circuit composed of resistors R109, R115, and R108 is applied to pin 2 of chip IC2 as a reference voltage and compared with the sinusoidal signal at pin 1 of IC2. The comparison result is output from pin 7 of chip IC2 and sent to the STM32F103RCT6 microcontroller. When the input pin PC0 is high, the program logic determines it as a positive half-wave; when the input pin 7 of chip IC2 is low, the program logic determines it as a negative half-wave. The processed sampling voltage signal from the input pin 7 of chip IC3 is sent to the sine wave signal voltage comparison between the input pins 3 and 4 of chip IC2 via the current limiting resistor R14. The comparison result is output from the input pin 6 of IC2, and after voltage division, it is sent to the input pin PB2 of the microcontroller STM32F103RCT6. When the output is high, if the sine wave signal is in the positive half-wave, the program logic determines that the output AC positive half-wave waveform is greater than the reference waveform, and stops the primary input; when the output is low, if the sine wave signal is in the negative half-wave, the program logic determines that the output AC negative half-wave waveform is greater than the reference waveform, and stops the primary input; when the output is high, if the sine wave signal is in the negative half-wave, the program logic determines that the output AC negative half-wave waveform is less than the reference waveform, and enables the primary input; when the output is low, if the sine wave signal is in the positive half-wave, the program logic determines that the output AC positive half-wave waveform is less than the reference waveform, and enables the primary input.

[0096] The voltage signal from the output sampling circuit, consisting of chip IC4 and external resistors R11~R12, R15~R16, and capacitors C3~C4, is sent to pins 2 and 3 of chip IC3. After internal isolation and amplification, it is output from pins 3 and 7 of chip IC3. After passing through the current-limiting resistor R14, one path is sent to input pin PA5 of the microcontroller STM32F103RCT6 as a reference signal for the overvoltage protection circuit; the other path is sent to pin 3 of chip IC2.

[0097] The working principle of two sets of back-to-back MOSFETs (Q6 and Q7 in the upper group and Q8 and Q9 in the lower group) to achieve zero-voltage turn-on and zero-voltage turn-off is as follows:

[0098] When the 50Hz AC positive half-wave is confirmed, the primary winding of the high-frequency switching transformer T1 stops working, and the output voltage is zero. The front transistors of the upper back-to-back MOSFETs (Q6 and Q8) and the front transistors of the lower back-to-back MOSFETs (Q8) are turned on, achieving zero-voltage turn-on. When the upper end of the high-frequency transformer output winding is positive, the body diode of the field-effect transistor Q7 is turned on. At this time, the high-level signal from pin PA3 of the STM32F103RCT6 microcontroller is sent to pin 2 of the IC14 chip SI8235. After isolation and amplification, it is output from pin 10 of the IC14 and sent to the gate of the MOSFET Q7 through the current-limiting resistor R30, achieving zero-voltage turn-on for the field-effect transistor Q7. When the on-current of the field-effect transistor Q7 decreases to zero, the filter inductor L1 begins to discharge. At this time, the drain voltage of the field-effect transistor Q7 is lower than the source voltage. At this time, the low-level signal of the output pin PA3 of the STM32F103RCT6 microcontroller is sent to pin 2 of the IC14 chip SI8235. After isolation and amplification, it is output from pin 10 of the IC14 chip and sent to the gate of the field-effect transistor Q7 through the current-limiting resistor R30. The field-effect transistor Q7 achieves zero-voltage turn-off.

[0099] When the lower end of the output winding of the high-frequency switching transformer T1 is positive, the body diode of the field-effect transistor Q9 is turned on. At this time, the high-level signal of the output pin PA1 of the STM32F103RCT6 microcontroller is sent to pin 2 of the IC15 chip. After isolation and amplification, it is output from pin 10 of the IC15 chip and sent to the gate of the field-effect transistor Q9 through the current-limiting resistor R32, achieving zero-voltage turn-on of the field-effect transistor Q9. When the conduction current of the field-effect transistor Q9 decreases to zero, the filter inductor L1 begins to discharge. At this time, the drain voltage of the field-effect transistor Q9 is lower than the source voltage. At this time, the low-level signal of the output pin PA1 of the STM32F103RCT6 microcontroller is sent to pin 2 of the IC15 chip. After isolation and amplification, it is output from pin 10 of the IC15 chip and sent to the gate of the field-effect transistor Q9 through the current-limiting resistor R32, achieving zero-voltage turn-off of the field-effect transistor Q9.

[0100] When the 50Hz AC negative half-wave is confirmed, the primary winding of the switching transformer stops working, the output voltage is zero, and the upper back-to-back MOSFETs (i.e., field-effect transistor Q7) and the lower back-to-back MOSFETs (i.e., field-effect transistor Q9) are turned on, achieving zero-voltage turn-on. When the upper end of the output winding of the high-frequency switching transformer T1 is negative, the body diode of the field-effect transistor Q6 is turned on. At this time, the high-level signal of the output pin PA2 of the STM32F103RCT6 microcontroller is sent to pin 1 of the IC14 chip, amplified by isolation, and output from pin 15 of the IC14 chip. It is then sent to the gate of the field-effect transistor Q6 through the current-limiting resistor R28, achieving zero-voltage turn-on for the field-effect transistor Q6. When the conduction current of the field-effect transistor Q6 decreases to zero, the filter inductor L1 begins to discharge. At this time, the drain voltage of the field-effect transistor Q6 is lower than the source voltage. At this time, the low-level signal of the output pin PA2 of the STM32F103RCT6 microcontroller is sent to pin 1 of the IC14 chip SI8235. After isolation and amplification, it is output from pin 15 of IC14 and sent to the gate of the field-effect transistor Q6 through the current-limiting resistor R28. The field-effect transistor Q6 achieves zero-voltage turn-off.

[0101] When the lower end of the output winding of the high-frequency switching transformer T1 is negative, the body diode of the field-effect transistor Q8 is turned on. At this time, the high-level signal of the output pin PA0 of the STM32F103RCT6 microcontroller is sent to pin 1 of the IC15 chip. After isolation and amplification, it is output from pin 15 of the IC15 chip and sent to the gate of the field-effect transistor Q8 through the current-limiting resistor R31, thus achieving zero-voltage turn-on of the field-effect transistor Q8. When the conduction current of the field-effect transistor Q8 decreases to zero, the filter inductor L1 begins to discharge. At this time, the drain voltage of the field-effect transistor Q8 is lower than the source voltage. At this time, the low-level signal of the output pin PA0 of the STM32F103RCT6 microcontroller is sent to pin 1 of the IC15 chip. After isolation and amplification, it is output from pin 15 of the IC15 chip and sent to the gate of the field-effect transistor Q8 through the current-limiting resistor R31, thus achieving zero-voltage turn-off of the field-effect transistor Q8.

[0102] This utility model has a reasonable structural design, is stable and reliable in use, can effectively reduce energy consumption and heat dissipation requirements, and has good compatibility, high safety and flexibility.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A pure sine wave inverter with DC input isolated by a high-frequency transformer and output, characterized in that: The pure sine wave inverter includes an energy storage inductor current sampling circuit, a filter inductor current sampling circuit, an output sampling comparison and overcurrent / overvoltage protection circuit, an inverter input / output main circuit, and an isolation amplifier circuit; The energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent and overvoltage protection circuit, and the isolation amplifier circuit are all electrically connected to the peripheral microcontroller STM32F103RCT6. The inverter input and output main circuits are respectively electrically connected to the energy storage inductor current sampling circuit, the filter inductor current sampling circuit, the output sampling comparison and overcurrent and overvoltage protection circuit, and the isolation amplifier circuit. The isolation amplifier circuit includes four isolation amplifier chips; the isolation amplifier chips receive the square wave signal output by the microcontroller STM32F103RCT6 of the peripheral device, and after isolating and amplifying the square wave signal, output it to the control electrode of the switching component MOS transistor of the inverter input and output main circuit. The energy storage inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device; The filter inductor current sampling circuit is used to collect the energy storage inductor current and output it to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device; The output sampling comparison and overcurrent / overvoltage protection circuit is used to receive the AC power output from the main output circuit of the inverter, compare it with the sinusoidal signal voltage, and then send the comparison result to the signal input pin of the microcontroller STM32F103RCT6 of the peripheral device after voltage division.

2. The pure sine wave inverter with DC input isolated by a high-frequency transformer as described in claim 1, characterized in that: The isolation amplifier circuit is composed of chip IC9 and chips IC13~IC15; all of chips IC9 and IC13~IC15 are isolation amplifier chips SI8235. The IC9 chip is connected to a 5V power supply through pins 3 and 8, grounded through pins 4 and 5, connected to power supply V2+ through pin 16, connected to power supply V2- through pin 14, connected to power supply V1+ through pin 11, connected to power supply V1- through pin 9, connected to the output pin PB4 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PB3 of the STM32F103RCT6 microcontroller through pin 2. The IC13 chip is grounded through pins 4, 5, 9 and 14, connected to a 12V power supply through pins 11 and 16, connected to the output pin PA8 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PC6 of the STM32F103RCT6 microcontroller through pin 2. The IC14 chip is grounded through pins 4 and 5, connected to a 5V power supply through pins 3 and 8, connected to power supply V3+ through pins 11 and 16, connected to power supply V3- through pins 9 and 14, connected to the output pin PA2 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PA3 of the STM32F103RCT6 microcontroller through pin 2. The IC15 chip is grounded through pins 4 and 5, connected to a 5V power supply through pins 3 and 8, connected to power supply V4+ through pins 11 and 16, connected to power supply V4- through pins 9 and 14, connected to the output pin PA0 of the STM32F103RCT6 microcontroller through pin 1, and connected to the output pin PA1 of the STM32F103RCT6 microcontroller through pin 2.

3. The pure sine wave inverter with DC input isolated by a high-frequency transformer as described in claim 2, characterized in that: The inverter's input / output main circuit consists of field-effect transistors Q2-Q9, a high-frequency switching transformer T1, resistors R01-R08, R9, R17, R19-R28, R30-R32, energy storage inductors L4 and L7, differential-mode inductor L5, common-mode inductor L6, filter inductor L1, sampling inductors L8-L10 and L12, non-polarized filter capacitors C10 and C12, capacitors C8 and C11, electrolytic capacitor C30, and diodes D2-D3; all field-effect transistors Q2-Q9 are N-MOS type. The drain of the field-effect transistor Q2 is connected to a 12V-400VDC power supply, and is connected to resistor R24, which in turn connects to pin 15 of the chip IC9. The source of Q2 is connected to one end of the energy storage inductor L4; the other end of the energy storage inductor L4 is connected to one end of the primary winding of the high-frequency switching transformer T1. One end of resistor R01 is connected to the source of the field-effect transistor Q2, and the other end is connected to the gate of Q2. The anode of diode D2 is grounded, and the cathode is connected to the source of the field-effect transistor Q2. One end of the sampling inductor L8 is connected to the current sampling circuit of the energy storage inductor, and the other end is connected to a +2.5V power supply. The drain of the field-effect transistor Q3 is connected to one end of the primary winding of the high-frequency switching transformer T1, and the gate is connected to resistor R26, which in turn connects to pin 15 of the chip IC13. The source of the field-effect transistor Q3 is grounded; one end of the resistor R02 is connected to the gate of the field-effect transistor Q3, and the other end is grounded; one end of the capacitor C8 is connected to the drain of the field-effect transistor Q3, and the other end is grounded; one end of the sampling inductor L9 is connected to the current sampling circuit of the filter inductor, and the other end is connected to the +2.5V power supply; the cathode of the electrolytic capacitor C30 is grounded, and the anode is connected to the 12V-400VDC power supply; the source of the field-effect transistor Q4 is connected to one end of the energy storage inductor L7, the drain is connected to the 12V-400VDC power supply, and the gate is connected to the resistor R25 and then connected to pin 10 of the chip IC9; the other end of the energy storage inductor L7 is connected to the other end of the primary winding of the high-frequency switching transformer T1; one end of the resistor R03 is connected to the source of the field-effect transistor Q4, and the other end is connected to the gate of the field-effect transistor Q4; The anode of diode D3 is grounded, and the cathode is connected to the source of field-effect transistor Q4. The drain of the field-effect transistor Q5 is connected to the other end of the energy storage inductor L7, the source is grounded, and the gate is connected to the resistor R27 and then to pin 10 of the chip IC13. One end of the resistor R04 is connected to the gate of the field-effect transistor Q5, and the other end is grounded. One end of the capacitor C11 is connected to the drain of the field-effect transistor Q5, and the other end is grounded. The drain of the field-effect transistor Q6 is connected to one end of the secondary winding of the high-frequency switching transformer T1, and the source is connected to the resistor R28 and then to pin 15 of the chip IC14. One end of the resistor R05 is connected to the source of the field-effect transistor Q6, and the other end is connected to... The gate of the field-effect transistor Q6; the source of the field-effect transistor Q7 is connected to the source of the field-effect transistor Q6, and its gate is connected to the resistor R30 and then to pin 10 of the chip IC14; one end of the resistor R06 is connected to the source of the field-effect transistor Q7, and the other end is connected to the gate of the field-effect transistor Q7; the drain of the field-effect transistor Q8 is connected to the other end of the secondary winding of the high-frequency switching transformer T1, and its gate is connected to the resistor R31 and then to pin 15 of the chip IC15; one end of the resistor R07 is connected to the gate of the field-effect transistor Q8, and the other end is connected to the source of the field-effect transistor Q8; The source of the field-effect transistor Q9 is connected to the source of the field-effect transistor Q8, and the gate is connected to the resistor R32 and then to pin 10 of the chip IC15; one end of the resistor R08 is connected to the source of the field-effect transistor Q9, and the other end is connected to the gate of the field-effect transistor Q9. One end of the sampling inductor L10 is connected to one end of resistor R88 in the current sampling circuit of the filter inductor, and the other end is connected to a +2.5V power supply; one end of the sampling inductor L12 is connected to the current sampling circuit of the filter inductor, and the other end is connected to a +2.5V power supply; one end of the filter inductor L1 is connected to the drain of the field-effect transistor Q7; one end of resistor R22 is connected to the other end of the filter inductor L1, and the other end is connected in series with resistors R21, R20, R19, and R23, and then connected to the center tap of the secondary winding of the high-frequency switching transformer T1; the signal line at the output of the high-frequency switching transformer T1 is also connected to the output sampling comparison and overcurrent / overvoltage protection circuit; the series connection point between resistors R19 and R23 is also connected to the output... The output sampling comparison and overcurrent / overvoltage protection circuit 3 is connected; one end of the resistor R17 is connected to the signal line of the output terminal of the high-frequency switching transformer T1, and the other end is connected to one end of one coil of the differential mode inductor L5 and the output sampling comparison and overcurrent / overvoltage protection circuit 3 respectively; the filter capacitor C10 is connected between one end of the two coils of the differential mode inductor L5, and the capacitor C12 is connected between the other ends of the two coils of the differential mode inductor L5; the forward signal line of the dual winding coil of the common mode inductor L6 is connected to the other end of the two coils of the differential mode inductor L5 respectively, and the reverse signal line of the dual winding coil of the common mode inductor L6 is connected to the live wire L and the neutral wire N respectively; the resistor R9 is connected between the reverse signal lines of the dual winding coil of the common mode inductor L6.

4. The pure sine wave inverter with DC input isolated by a high-frequency transformer as described in claim 3, characterized in that: The energy storage inductor current sampling circuit consists of chip IC16, resistors R80~R87, and diodes D6~D9; The IC16 chip is a TLV3502. It is connected to a +2.6V supply voltage via pins 2 and 4, a 5V supply voltage via pin 8, and ground via pin 5. One end of resistor R80 is connected to one end of the sampling inductor L9, and the other end is connected to pin 3 of the IC16 chip. One end of resistor R81 is connected to one end of the sampling inductor L8, and the other end is connected to pin 1 of the IC16 chip. One end of resistor R82 is connected to a +2.5V supply voltage, and the other end is connected to pin 1 of the IC16 chip. Resistor R82 also has diodes D6 and D7 connected in parallel. The anode of diode D6 is connected to the +2.5V supply voltage, and the cathode is connected to pin 1 of the IC16 chip. The anode of diode D7 is connected to pin 1 of the IC16 chip, and the cathode is connected to the +2.5V supply voltage. One end of resistor R83 is connected to... The resistor R83 is connected to a 2.5V power supply, with one end connected to pin 3 of the IC16 chip. Diodes D8 and D9 are connected in parallel with resistor R83. The anode of diode D8 is connected to the +2.5V power supply, and the cathode is connected to pin 3 of the IC16 chip. The anode of diode D9 is connected to pin 3 of the IC16 chip, and the cathode is connected to the +2.5V power supply. One end of resistor R84 is grounded, and the other end is connected in series with resistor R86 and then to pin 6 of the IC16 chip. The connection point between resistors R84 and R86 is connected to the input pin PC4 of the STM32F103RCT6 microcontroller. One end of resistor R85 is grounded, and the other end is connected in series with resistor R87 and then to pin 7 of the IC16 chip. The connection point between resistors R85 and R87 is connected to the input pin PC3 of the STM32F103RCT6 microcontroller.

5. The pure sine wave inverter with DC input isolated by a high-frequency transformer as described in claim 3, characterized in that: The filter inductor current sampling circuit consists of chip IC1, resistors R88, R89, R94, R95, R103~R106, diodes D1, D10, D17 and D18. The chip IC1 is model TLV3502. It is connected to a +2.6V supply voltage through pins 2 and 4, a 5V supply voltage through pin 8, and grounded through pin 5. One end of the resistor R88 is connected to the main input / output circuit of the inverter, and the other end is connected to pin 3 of the chip IC1. One end of the resistor R89 ​​is connected to one end of the sampling inductor L12, and the other end is connected to pin 1 of the chip IC1. One end of resistor R94 is connected to a +2.5V power supply, and the other end is connected to pin 1 of chip IC1. Diodes D1 and D10 are also connected in parallel with resistor R94. The anode of diode D1 is connected to a +2.5V power supply, and the cathode is connected to pin 1 of chip IC1. The anode of diode D10 is connected to pin 1 of chip IC1, and the cathode is connected to a +2.5V power supply. One end of resistor R95 is connected to a +2.5V power supply, and the other end is connected to pin 3 of chip IC1. Diodes D18 and D17 are also connected in parallel with resistor R95. The anode of diode D17 is connected to a +2.5V power supply, and the cathode is connected to… Pin 3 of the chip IC1; the anode of the diode D18 is connected to pin 3 of the chip IC1, and the cathode is connected to the +2.5V supply voltage; one end of the resistor R103 is grounded, and the other end is connected in series with the resistor R105 and then connected to pin 6 of the chip IC1; the series connection point between the resistors R103 and R105 is connected to pin PC1 of the peripheral microcontroller STM32F103RCT6; one end of the resistor R104 is grounded, and the other end is connected in series with the resistor R106 and then connected to pin 7 of the chip IC1; the series connection point between the resistors R104 and R106 is connected to the input pin PC2 of the microcontroller STM32F103RCT6.

6. The pure sine wave inverter with DC input isolated by a high-frequency transformer as described in claim 3, characterized in that: The output sampling comparison and overcurrent / overvoltage protection circuit consists of an overcurrent / overvoltage protection circuit, a sinusoidal output current sampling circuit, and a sinusoidal output voltage sampling circuit connected to the overcurrent / overvoltage protection circuit. The overcurrent and overvoltage protection circuit consists of chip IC2, resistors R107~R109, resistors R111~R114 and adjustable resistor R115; The sinusoidal output voltage sampling circuit consists of chip IC3, resistors R10, R18, R13, R14 and capacitor C1. The sinusoidal output current sampling circuit consists of chip IC4, resistors R11~R12, resistors R15~R16, and capacitors C3~C4. The IC2 chip is a comparator chip TLV3502, with pin 5 grounded and pin 8 connected to a 5V power supply. One end of resistor R107 is connected to pin PA4, and the other end is connected to pins 1 and 4 of IC2. One end of resistor R111 is grounded, and the other end is connected in series with resistor R113 and then to pin 6 of IC2. The connection point between resistors R111 and R113 is connected to the input pin PB2 of the STM32F103RCT6 microcontroller. One end of resistor R112 is grounded, and the other end is connected in series with... The resistor R114 is connected to pin 7 of the IC2 chip; the series connection between the resistors R112 and R114 is connected to the input pin PC0 of the STM32F103RCT6 microcontroller; one end of the resistor R108 is connected to pin 5 of the IC2 chip, and the other end is connected to one end of the coil of the adjustable resistor R115; the other end of the coil of the adjustable resistor R115 is connected to the resistor R109 and then connected to a 5V power supply through the resistor R109; the tab of the adjustable resistor R115 is connected to pin 2 of the IC2 chip. The chip IC3 is an isolation amplifier chip AMC1301. Its pin 1 is connected to power supply V5+, pin 4 to power supply V5-, pin 5 to power supply V6-, pin 8 to power supply V6+, and pin 3 is connected to resistor R10. One end of capacitor C1 is connected to pin 3 of chip IC2, and the other end is connected to pin 2 of chip IC2. One end of resistor R13 is connected to pin 2 of chip IC2, and the other end is connected to pin 6 of chip IC3. One end of resistor R14... Connect one end of the resistor R10 to the analog input pin PA5 of the STM32F103RCT6 microcontroller, and the other end to pin 7 of the IC3 chip; connect one end of the resistor R10 to pin 3 of the IC3 chip, and the other end to the center tap of the secondary winding of the high-frequency switching transformer T1; connect one end of the resistor R18 to pin 2 of the IC3 chip, and the other end to the series connection point between the resistors R19 and R23; connect the two ends of the capacitor C2 to pins 2 and 3 of the IC3 chip, respectively. The chip IC4 is an isolation amplifier chip AMC1301. Its pin 1 is connected to power supply V5+, pin 4 to power supply V5-, pin 5 to power supply V6-, and pin 8 to power supply V6+. One end of the resistor R12 is connected to pin 7 of the chip IC4, and the other end is connected to pin PB0 of the STM32F103RCT6 microcontroller. One end of the capacitor C4 is connected to the analog input pin PB0 of the STM32F103RCT6 microcontroller, and the other end is split into two paths, one of which is connected to the resistor R12. 16 is connected to pin 6 of chip IC4 via resistor R16, and another path is connected to pin 2 of chip IC2; one end of resistor R11 is connected to pin 3 of chip IC4, and the other end is connected to the series connection point between resistor R19 and resistor R23; one end of resistor R15 is connected to pin 2 of chip IC4, and the other end is connected to the other end of resistor R17; one end of capacitor C3 is connected to pin 2 of chip IC4, and the other end is connected to pin 3 of chip IC4.

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