A single-stage dcac inverter circuit based on hybrid mode

Abstract

This invention discloses a hybrid-mode single-stage DCAC inverter circuit, comprising: a transformer module, a secondary power transmission module disposed on a first winding of the transformer module, and a primary power transmission module disposed on a second winding of the transformer module; the secondary power transmission module is connected to a mains power supply to supply mains voltage, and the primary power transmission module is connected to a DC power supply to receive DC voltage; when the DC voltage is greater than the peak value of the mains voltage, or when the DC voltage is less than the peak value of the mains voltage and a first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode; when the DC voltage is less than the peak value of the mains voltage and a second condition is met, the single-stage DCAC inverter circuit operates in phase-shifting mode. This invention can ensure high efficiency while maintaining a high power factor (PF) and can continuously operate in single-stage power conversion mode, thereby improving efficiency.

Description

Technical Field

[0001] This invention relates to the field of DCAC rectifier circuits, and more specifically, to a single-stage DCAC inverter circuit based on a hybrid mode. Background Technology

[0002] In the grid-connected inverter function of traditional V2G power products, a two-stage topology is generally used to balance the high power factor (PF) compatibility on the grid side and the wide range of voltage output on the DC side. Although the PF circuit on the AC side and the DCDC circuit on the DC side of the DC AC inverter circuit with a two-stage topology are functionally independent and simple to control, they are costly and inefficient. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a single-stage DCAC inverter circuit based on hybrid mode, which not only can be compatible with high PF value and wide range voltage output, but also can ensure circuit efficiency and maintain low cost.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to construct a single-stage DCAC inverter circuit based on hybrid mode, including: a transformer module, a secondary power transmission module disposed on the first side winding of the transformer module, and a primary power transmission module disposed on the second side winding of the transformer module. The secondary power transmission module is connected to the grid power supply to supply grid voltage, and the primary power transmission module is connected to the DC power supply to receive DC voltage. When the DC voltage is greater than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode; When the DC voltage is less than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode and phase-shifting mode.

[0005] In the hybrid-mode-based single-stage DCAC inverter circuit of the present invention, the secondary power transmission module includes a first power inductor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch. The control terminals of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch receive control signals. The first end of the first switch, the first end of the second switch, and the first end of the fifth switch are connected to the first end of the first power inductor. The second end of the first power inductor is connected to the first end of the mains power supply. The second end of the first switch is connected to the same-name terminal of the first winding of the transformer module. The second end of the second switch is connected to the opposite-name terminal of the first winding of the transformer module. The second end of the fifth switch is connected to the second end of the sixth switch. The first end of the sixth switch, the first end of the third switch, and the first end of the fourth switch are connected to the second end of the mains power supply. The second end of the third switch is connected to the same-name terminal of the first winding of the transformer module. The second end of the fourth switch is connected to the opposite-name terminal of the first winding of the transformer module.

[0006] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, the primary-side power transmission module includes a seventh switch, an eighth switch, a ninth switch, a tenth switch, a diode, and a second power inductor. The control terminals of the seventh, eighth, ninth, and tenth switches receive control signals. The first terminal of the seventh switch is connected to the second terminal of the eighth switch and the same-name terminal of the second winding of the transformer module. The second terminal of the seventh switch is connected to the second terminal of the ninth switch, the first terminal of the second power inductor, and the anode of the diode. The second terminal of the second power inductor and the cathode of the diode are connected to the positive terminal of the DC power supply. The first terminal of the ninth switch is connected to the second terminal of the tenth switch and the opposite-name terminal of the second winding of the transformer module. The first terminals of the eighth and tenth switches are connected to the negative terminal of the DC power supply.

[0007] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the DC voltage is greater than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode: The DC power supply, the second power inductor, the seventh switch, the eighth switch, the ninth switch, the tenth switch, and the transformer module constitute a BUCK secondary full-bridge circuit; The transformer module, the first switch, the second switch, the third switch, the fourth switch, the first power inductor, and the mains power supply constitute the primary circuit.

[0008] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the positive half-cycle: The DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the mains power supply, the fourth switch, and the tenth switch constitute the first inverter circuit; The DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the mains power supply, the third switch, and the eighth switch constitute the second inverter circuit; During the dead time, the diode provides a freewheeling path for the second power inductor, and the fifth and sixth switches provide a freewheeling path for the first power inductor.

[0009] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the negative half-cycle: The DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the mains power supply, the second switch, and the tenth switch constitute the first inverter circuit; The DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the mains power supply, the first switch, and the eighth switch constitute the second inverter circuit; During the dead time, the diode provides a freewheeling path for the second power inductor, and the fifth and sixth switches provide a freewheeling path for the first power inductor.

[0010] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the DC voltage is less than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode and phase-shifting mode: When the grid voltage is near the grid zero point, the single-stage DCAC inverter circuit operates in BUCK mode; When the grid voltage is close to the DC voltage, the duty cycle of the seventh switch and the tenth switch reaches the maximum duty cycle and the single-stage DCAC inverter circuit operates in BUCK mode. When the grid voltage exceeds the DC voltage, the single-stage DCAC inverter circuit operates in phase-shift mode, the duty cycles of the seventh and ninth switches remain unchanged, and the duty cycles of the eighth and tenth switches are phase-shifted with lag.

[0011] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the grid voltage is in the positive half-cycle and the grid voltage is less than the DC voltage: The DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the mains power supply, the fourth switch, and the tenth switch constitute a first inverter circuit; the DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the mains power supply, the third switch, and the eighth switch constitute a second inverter circuit. When the grid voltage is in the positive half-cycle and the grid voltage is greater than the DC voltage: During the first stage of energy transfer, the eighth switch lags behind the seventh switch in phase shift and stores energy in the second power inductor through a first energy storage circuit consisting of the DC power supply, the second power inductor, the seventh switch, and the eighth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, it transfers energy through a third inverter circuit, wherein the third inverter circuit consists of the DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the grid power supply, the fourth switch, and the tenth switch. During the second stage of energy transfer, the tenth switch is phase-shifted and lags behind the ninth switch. Energy is stored in the second power inductor through a second energy storage circuit consisting of the DC power supply, the second power inductor, the ninth switch, and the tenth switch. At this time, the first, second, third, and fourth switches are turned off. After the second power inductor completes energy storage, energy is transferred through a fourth inverter circuit, which is composed of the DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the grid power supply, the third switch, and the eighth switch. During the dead time, the fifth and sixth switches provide a freewheeling path for the first power inductor.

[0012] In the hybrid-mode-based single-stage DCAC inverter circuit described in this invention, when the grid voltage is in the negative half-cycle and the grid voltage is less than the DC voltage: The DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the mains power supply, the second switch, and the tenth switch constitute a first inverter circuit; the DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the mains power supply, the first switch, and the eighth switch constitute a second inverter circuit. When the grid voltage is in the negative half-cycle and the grid voltage is greater than the DC voltage: During the first stage of energy transfer, the eighth switch lags behind the seventh switch in phase shift and stores energy in the second power inductor through a first energy storage circuit consisting of the DC power supply, the second power inductor, the seventh switch, and the eighth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, it transmits energy through a third inverter circuit, wherein the third inverter circuit consists of the DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the grid power supply, the second switch, and the tenth switch. During the second stage of energy transfer, the tenth switch is phase-shifted and lags behind the ninth switch. Energy is stored in the second power inductor through a second energy storage circuit consisting of the DC power supply, the second power inductor, the ninth switch, and the tenth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, energy is transferred through a fourth inverter circuit, which is composed of the DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the grid power supply, the first switch, and the eighth switch. During the dead time, the fifth and sixth switches provide a freewheeling path for the first power inductor.

[0013] The single-stage DCAC inverter circuit based on hybrid mode described in this invention further includes a secondary capacitor. The positive terminal of the secondary capacitor is connected to the positive terminal of the DC power supply, and the negative terminal of the secondary capacitor is grounded.

[0014] This invention discloses a hybrid-mode single-stage DCAC inverter circuit, comprising: a transformer module, a secondary power transmission module disposed on a first winding of the transformer module, and a primary power transmission module disposed on a second winding of the transformer module; the secondary power transmission module is connected to a grid power supply to supply grid voltage, and the primary power transmission module is connected to a DC power supply to receive DC voltage; when the DC voltage is greater than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode; when the DC voltage is less than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in both BUCK mode and phase-shifting mode. This hybrid-mode single-stage DCAC inverter circuit of the present invention can ensure high efficiency while maintaining a high power factor (PF); simultaneously, the single-stage DCAC inverter circuit can switch between BUCK mode and phase-shifting mode according to the DC voltage and grid voltage, thus it can always operate in single-stage power conversion mode, thereby improving efficiency. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic block diagram of a preferred embodiment of the hybrid-mode single-stage DCAC inverter circuit of the present invention; Figure 2 This is a circuit diagram of a preferred embodiment of the hybrid-mode single-stage DCAC inverter circuit of the present invention; Figure 3 yes Figure 2 The diagram shows the grid voltage and DC voltage waveforms of a hybrid-mode single-stage DCAC inverter circuit in BUCK mode. Figure 4A yes Figure 2 The diagram shows the drive signal waveform of the switching transistor Q9 in BUCK mode of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit. Figure 4B yes Figure 2 The diagram shows the drive signal waveform of the switching transistor Q10 in BUCK mode of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit. Figure 5A yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transmission module of a hybrid-mode single-stage DCAC inverter circuit, including switches Q5 and Q8, as well as switches Q1 and Q4, in BUCK mode. Figure 5B yes Figure 2The diagram shows the drive signal waveforms of switches Q8 and Q6, as well as switches Q2 and Q3, in BUCK mode for the secondary power transmission module of a hybrid-mode single-stage DCAC inverter circuit. Figure 6 yes Figure 2 The diagram shows the grid voltage and DC voltage waveforms of a hybrid-mode single-stage DCAC inverter circuit in BUCK and phase-shift modes. Figure 7A yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q5 and Q8, in BUCK and phase-shift modes. Figure 7B yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q7 and Q6, in BUCK and phase-shift modes. Figure 7C yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q1 and Q4, in BUCK and phase-shift modes. Figure 7D yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q2 and Q3, in BUCK and phase-shift modes. Figure 8A yes Figure 2 The diagram shows the drive signal waveforms of the switching transistors Q5 to Q8 in phase-shift mode at 5ms in the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit. Figure 8B yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit at 5ms in phase-shift mode for switches Q5, Q8, Q1, and Q4. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] Figure 1 This is a schematic block diagram of a preferred embodiment of the hybrid-mode single-stage DCAC inverter circuit of the present invention. Figure 1As shown, the hybrid-mode-based single-stage DCAC inverter circuit includes: a transformer module 100, a secondary power transmission module 300 disposed on the first winding of the transformer module 100, and a primary power transmission module 200 disposed on the second winding of the transformer module 100; the secondary power transmission module 300 is connected to the grid power supply to supply grid voltage, and the primary power transmission module 200 is connected to a DC power supply to receive DC voltage; when the DC voltage is greater than the peak value of the grid voltage, or when the DC voltage is less than the peak value of the grid voltage and a first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode, wherein the first condition is that the instantaneous voltage is between the DC voltage and the zero point of the grid voltage; when the DC voltage is less than the peak value of the grid voltage and a second condition is met, the single-stage DCAC inverter circuit operates in phase-shifting mode, wherein the second condition is that the instantaneous voltage is between the peak value of the DC voltage and the peak value of the grid voltage.

[0018] In a preferred embodiment of the present invention, the transformer module 100 may include a single transformer or multiple transformers connected in series, wherein the turns ratio of its first winding and second winding is 1:1. The secondary-side power transmission module 300 may include a first power inductor and a switching transistor unit (e.g., a switching transistor unit composed of multiple switching transistor bridge arms), and a switching transistor rectifier bridge (e.g., a switching transistor full bridge). The primary-side power transmission module 400 may include a switching transistor rectifier bridge (e.g., multiple switching transistor full bridges or half bridges), a second power inductor, and diodes.

[0019] The present invention discloses a hybrid-mode-based single-stage DCAC inverter circuit, comprising: a transformer module, a secondary power transmission module disposed on a first winding of the transformer module, and a primary power transmission module disposed on a second winding of the transformer module; the secondary power transmission module is connected to a grid power supply to supply grid voltage, and the primary power transmission module is connected to a DC power supply to receive DC voltage; when the DC voltage is greater than the peak value of the grid voltage, or when the DC voltage is less than the peak value of the grid voltage and a first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode, wherein the first condition is that the instantaneous voltage is between the DC voltage and the zero point of the grid voltage; when the DC voltage is less than the peak value of the grid voltage and a second condition is met, the single-stage DCAC inverter circuit operates in phase-shifting mode, wherein the second condition is that the instantaneous voltage is between the DC voltage and the peak value of the grid voltage. Therefore, the hybrid-mode-based single-stage DCAC inverter circuit of the present invention can ensure high efficiency while maintaining a high power factor (PF) through a single-stage DCAC inverter circuit; at the same time, the single-stage DCAC inverter circuit can switch between BUCK mode and phase-shifting mode according to DC voltage and grid voltage, so it can always operate in single-stage power conversion mode, thereby improving efficiency.

[0020] Figure 2 This is a circuit diagram of a preferred embodiment of the hybrid-mode single-stage DCAC inverter circuit of the present invention. Combined with... Figures 1-2 It is understood that the hybrid-mode-based single-stage DCAC inverter circuit includes: a transformer module 100, a secondary power transmission module 300 disposed on the first winding of the transformer module 100, and a primary power transmission module 200 disposed on the second winding of the transformer module 100; the secondary power transmission module 300 is connected to the grid power supply to supply grid voltage, and the primary power transmission module 200 is connected to a DC power supply to receive DC voltage; when the DC voltage is greater than the peak value of the grid voltage, or when the DC voltage is less than the peak value of the grid voltage and a first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode, wherein the first condition is that the instantaneous voltage is between the DC voltage and the zero point of the grid voltage; when the DC voltage is less than the peak value of the grid voltage and a second condition is met, the single-stage DCAC inverter circuit operates in phase-shifting mode, wherein the second condition is that the instantaneous voltage is between the peak value of the DC voltage and the peak value of the grid voltage.

[0021] The secondary power transmission module 300 includes a first power inductor L1, a switch Q1, a switch Q2, a switch Q3, a switch Q4, a switch Q9, and a switch Q10; the control terminals of the switches Q1, Q2, Q3, Q4, Q9, and Q10 receive control signals. The first ends of the switching transistors Q1, Q2, and Q9 are connected to the first end of the first power inductor L1. The second end of the first power inductor L1 is connected to the first end of the mains power supply. The second end of the switching transistor Q1 is connected to the same-name end of the first winding of the transformer module 100. The second end of the switching transistor Q2 is connected to the opposite-name end of the first winding of the transformer module 100. The second end of the switching transistor Q9 is connected to the second end of the switching transistor Q10. The first ends of the switching transistors Q10, Q3, and Q4 are connected to the second end of the mains power supply. The second end of the switching transistor Q3 is connected to the same-name end of the first winding of the transformer module 100. The second end of the switching transistor Q4 is connected to the opposite-name end of the first winding of the transformer module 100. The primary-side power transmission module 200 includes switching transistors Q5, Q7, Q6, and Q8, a diode D1, and a second power inductor L2. The control terminals of switching transistors Q5, Q7, Q6, and Q8 receive control signals. The first terminal of switching transistor Q5 is connected to the second terminal of switching transistor Q7 and the same-name terminal of the second winding of the transformer module 100. The second terminal of switching transistor Q5 is connected to the second terminal of switching transistor Q6, the first terminal of the second power inductor L2, and the anode of diode D1. The second terminal of the second power inductor L2 and the cathode of diode D1 are connected to the positive terminal of the DC power supply. The first terminal of switching transistor Q6 is connected to the second terminal of switching transistor Q8 and the opposite-name terminal of the second winding of the transformer module 100. The first terminals of switching transistors Q7 and Q8 are connected to the negative terminal of the DC power supply.

[0022] exist Figure 2 In the preferred embodiment shown, the hybrid-mode-based single-stage DCAC inverter circuit further includes a secondary capacitor C2; the positive terminal of the secondary capacitor C2 is connected to the positive terminal of the DC power supply, and the negative terminal of the secondary capacitor C2 is grounded. In a preferred embodiment of the present invention, the switching transistors Q1, Q2, Q3, Q4, Q9, Q10, Q5, Q7, Q6, and Q8 can be MOSFETs, IGBTs, or transistors. Figure 2 In the preferred embodiment shown, the transformer module 100 includes a transformer T1.

[0023] In this invention, the peak value of the DC voltage is compared with the peak value of the grid voltage. When the DC voltage is greater than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode: the DC power supply, the second power inductor L2, the switching transistors Q5, Q7, Q6, Q8, and the transformer T1 constitute a BUCK secondary-side full-bridge circuit; the circuits formed by the second power inductor L2, Q5, transformer T1, and Q8, and the circuits formed by the second power inductor L2, Q6, transformer T1, and Q7, alternately transmit power to the secondary side of the transformer T1. The transformer T1, the switching transistors Q1, Q2, Q3, Q4, the first power inductor L1, and the grid power supply constitute the primary-side circuit. During the dead time, diode D1 provides a freewheeling path for the second power inductor L2, and switching transistors Q9 and Q10 provide a freewheeling path for the first power inductor L1.

[0024] When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the positive half-cycle (positive at the top, negative at the bottom), the DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q1, the first power inductor L1, the grid power supply, the switch Q4, and the switch Q8 constitute the first inverter circuit; the DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q2, the first power inductor L1, the grid power supply, the switch Q3, and the switch Q7 constitute the second inverter circuit. Power is supplied to the grid power supply alternately through the transformer T1, the switch Q1, the second power inductor L2, the grid power supply, and the switch Q4, and through the transformer T1, the switch Q2, the second power inductor L2, the grid power supply, and the switch Q3.

[0025] When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the negative half-cycle: the DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q3, the first power inductor L1, the grid power supply, the switch Q2, and the switch Q8 constitute the first inverter circuit; the DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q4, the first power inductor L1, the grid power supply, the switch Q1, and the switch Q7 constitute the second inverter circuit. Power is supplied to the grid power supply alternately through transformer T1, switch Q3, grid power supply, L2, and switch Q2, and also through transformer T1, switch Q4, grid power supply, L2, and switch Q1.

[0026] When the grid voltage is near the grid zero point, the single-stage DCAC inverter circuit operates in BUCK mode, and its operating principle is the same as that of the aforementioned BUCK mode. When the grid voltage is close to the DC voltage, the duty cycles of the switching transistors Q5 and Q8 reach their maximum duty cycles, and the single-stage DCAC inverter circuit operates in BUCK mode, with the same operating principle as that of the aforementioned BUCK mode.

[0027] When the grid voltage exceeds the DC voltage, the single-stage DCAC inverter circuit operates in phase-shift mode. The duty cycles of switches Q5 and Q6 remain constant, while the duty cycles of switches Q7 and Q8 are phase-shifted and lagging. Here, the duty cycles of switches Q5 and Q6 remain constant, while the duty cycles of switches Q7 and Q8 are phase-shifted and lagging by a certain angle. This lag angle is proportional to the difference between the grid voltage and the DC voltage (where grid voltage refers to the instantaneous grid voltage). To ensure a high power factor (PF) value for the inverter current, the lag angle exhibits a sinusoidal variation. During the lag angle, switches Q5, Q7, Q6, and Q8 are alternately short-circuited, allowing the second power inductor L2 to continue storing energy. This energy is then connected in series with the DC voltage of the DC power supply and superimposed on the transformer T1 to achieve a boost output.

[0028] Figure 3 yes Figure 2 The diagram shows the grid voltage and DC voltage waveforms of a hybrid-mode single-stage DCAC inverter circuit in BUCK mode. Figure 4A yes Figure 2 The diagram shows the drive signal waveform of the switching transistor Q9 in BUCK mode of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit. Figure 4B yes Figure 2The diagram shows the drive signal waveform of the switching transistor Q10 in BUCK mode of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit. Figure 5A yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transmission module of a hybrid-mode single-stage DCAC inverter circuit, including switches Q5 and Q8, as well as switches Q1 and Q4, in BUCK mode. Figure 5B yes Figure 2 The diagram shows the drive signal waveforms of switches Q8 and Q6, as well as switches Q2 and Q3, in BUCK mode for the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit. Figure 6 yes Figure 2 The diagram shows the grid voltage and DC voltage waveforms of a hybrid-mode single-stage DCAC inverter circuit in BUCK and phase-shift modes. Figure 7A yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q5 and Q8, in BUCK and phase-shift modes. Figure 7B yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q7 and Q6, in BUCK and phase-shift modes. Figure 7C yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q1 and Q4, in BUCK and phase-shift modes. Figure 7D yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of the hybrid-mode single-stage DCAC inverter circuit, specifically the switching transistors Q2 and Q3, in BUCK and phase-shift modes. Figure 8A yes Figure 2 The diagram shows the drive signal waveforms of the switching transistors Q5 to Q8 in phase-shift mode at 5ms in the secondary power transmission module of the hybrid-mode single-stage DCAC inverter circuit. Figure 8B yes Figure 2 The diagram shows the drive signal waveforms of the secondary power transfer module of a hybrid-mode single-stage DCAC inverter circuit at 5ms in phase-shift mode for switches Q5, Q8, Q1, and Q4.

[0029] The following will combine Figures 3-5B The workflow of the hybrid-mode-based single-stage DCAC inverter circuit of the present invention in BUCK mode is described below. Figure 3As shown, assuming the DC voltage of the DC power supply Bat is 600Vdc and the peak voltage of the 220Vac mains power supply is 311Vdc, the single-stage DCAC inverter circuit operates in BUCK mode when the DC voltage is greater than the peak voltage of the mains voltage. Figure 4A ~ Figure 5B yes Figure 2 The diagram shows the drive signal waveforms of each switch in the BUCK mode of a hybrid-mode single-stage DCAC inverter circuit, with the horizontal axis representing time.

[0030] After phase-locking with the power grid, the battery-side switches Q5-Q8 modulate the output according to a sine wave pattern. The DC power supply, the second power inductor L2, the switches Q5, Q7, Q6, Q8, and the transformer T1 constitute a BUCK secondary-side full-bridge circuit with a sine wave output pattern. The driving waveforms of each switch are as follows: Figures 4A-5B As shown.

[0031] When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the positive half-cycle (positive at the top and negative at the bottom), there are two corresponding complete inverter circuits: the DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q1, the first power inductor L1, the grid power supply, the switch Q4, and the switch Q8 constitute the first inverter circuit; and the DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q2, the first power inductor L1, the grid power supply, the switch Q3, and the switch Q7 constitute the second inverter circuit. During the dead time, diode D1 provides a freewheeling circuit for the second power inductor L2, and switches Q9 and Q10 provide a freewheeling circuit for the first power inductor L1.

[0032] When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the negative half-cycle (negative on top, positive on bottom), there are two corresponding complete inverter circuits. The DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q3, the first power inductor L1, the grid power supply, the switch Q2, and the switch Q8 constitute the first inverter circuit. The DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q4, the first power inductor L1, the grid power supply, the switch Q1, and the switch Q7 constitute the second inverter circuit. During the dead time, diode D1 provides a freewheeling circuit for the second power inductor L2, and switches Q9 and Q10 provide a freewheeling circuit for the first power inductor L1.

[0033] The following will combine Figures 6-8B The operating process of the hybrid-mode single-stage DCAC inverter circuit of the present invention in BUCK and phase-shift modes is described below. Figure 6 As shown, assuming the DC voltage of the DC power supply Bat is 200Vdc and the peak voltage of the 220Vac grid power supply is 311Vdc, the single-stage DCAC inverter circuit operates in BUCK and phase-shifting modes when the DC voltage is less than the peak voltage of the grid voltage. Figure 7A ~ Figure 8B yes Figure 2 The diagram shows the drive signal waveforms of each switch in the hybrid-mode single-stage DCAC inverter circuit under BUCK and phase-shift modes, with the horizontal axis representing time.

[0034] When the DC voltage is less than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode and phase-shift mode: when the grid voltage is near the grid zero point, the single-stage DCAC inverter circuit operates in BUCK mode; when the grid voltage is close to the DC voltage, the duty cycles of the switches Q5 and Q8 reach their maximum duty cycles and the single-stage DCAC inverter circuit operates in BUCK mode; when the grid voltage exceeds the DC voltage, the single-stage DCAC inverter circuit operates in phase-shift mode, the duty cycles of the switches Q5 and Q6 remain unchanged, and the duty cycles of the switches Q7 and Q8 are phase-shifted with lag.

[0035] When the grid voltage is near the grid zero point and when the grid voltage is close to the DC voltage but less than the DC voltage, the single-stage DCAC inverter circuit operates in BUCK mode, and the operating logic is the same as the BUCK mode above.

[0036] When the grid voltage exceeds the DC voltage, the single-stage DCAC inverter circuit operates in phase-shift mode. The duty cycles of the switches Q5 and Q6 remain unchanged, while the duty cycles of the switches Q7 and Q8 are phase-shifted and delayed. This forms two inverter loops in a time-sharing manner: the second power inductor L2 + the switches Q5 and Q8, and the second power inductor L2 + the switches Q7 and Q6. Energy is stored in these loops, and then the voltage obtained by connecting the second power inductor L2 and the DC power supply in series is transmitted to the subsequent circuit through the transformer T1.

[0037] When the grid voltage is in the positive half-cycle (positive at the top and negative at the bottom) and the grid voltage is less than the DC voltage, there are two corresponding complete inverter grid-connected circuits. The DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q1, the first power inductor L1, the grid power supply, the switch Q4, and the switch Q8 constitute the first inverter circuit; the DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q2, the first power inductor L1, the grid power supply, the switch Q3, and the switch Q7 constitute the second inverter circuit.

[0038] When the grid voltage is in the positive half-cycle and is greater than the DC voltage, the complete inverter circuit has two phases in sequence. In the first phase of energy transfer, switch Q7 is phase-shifted and lags behind switch Q5. Energy is stored in the second power inductor L2 through a first energy storage circuit consisting of the DC power supply, the second power inductor L2, switch Q5, and switch Q7. At this time, switches Q1, Q2, Q3, and Q4 are turned off. After the second power inductor L2 has completed energy storage, energy is transferred through a third inverter circuit. The duration of energy storage is determined by the peak value of the grid voltage and the voltage difference of the DC voltage. The third inverter circuit consists of the DC power supply, the second power inductor L2, switch Q5, transformer T1, switch Q1, the first power inductor L1, the grid power supply, switch Q4, and switch Q8.

[0039] In the second stage of energy transfer, switch Q8 initially lags behind switch Q6 in phase shift. Energy is stored in the second power inductor L2 through a second energy storage circuit consisting of the DC power supply, the second power inductor L2, switch Q6, and switch Q8. During this time, switches Q1, Q2, Q3, and Q4 are turned off. After energy storage is complete, the second power inductor L2 transfers energy through a fourth inverter circuit. The energy storage time is determined by the peak value of the grid voltage and the DC voltage difference. The fourth inverter circuit consists of the DC power supply, the second power inductor L2, switch Q6, transformer T1, switch Q2, the first power inductor L1, the grid power supply, switch Q3, and switch Q7. During the dead time, switches Q9 and Q10 provide a freewheeling circuit for the first power inductor L1.

[0040] When the grid voltage is in the negative half-cycle (negative at the top, positive at the bottom) and the grid voltage is less than the DC voltage, there are two corresponding complete inverter grid-connected circuits. The DC power supply, the second power inductor L2, the switch Q5, the transformer T1, the switch Q3, the first power inductor L1, the grid power supply, the switch Q2, and the switch Q8 constitute the first inverter circuit; the DC power supply, the second power inductor L2, the switch Q6, the transformer T1, the switch Q4, the first power inductor L1, the grid power supply, the switch Q1, and the switch Q7 constitute the second inverter circuit.

[0041] When the grid voltage is in the negative half-cycle (negative at the top, positive at the bottom) and the grid voltage is greater than the DC voltage, the complete inverter circuit has two phases in sequence. In the first phase of energy transfer, switch Q7 is phase-shifted and lags behind switch Q5. Energy is stored in the second power inductor L2 through a first energy storage circuit consisting of the DC power supply, the second power inductor L2, switch Q5, and switch Q7. At this time, switches Q1, Q2, Q3, and Q4 are turned off. After the second power inductor L2 has completed energy storage, energy is transferred through a third inverter circuit. The duration of energy storage is determined by the peak value of the grid voltage and the voltage difference of the DC voltage. The third inverter circuit consists of the DC power supply, the second power inductor L2, switch Q5, transformer T1, switch Q3, the first power inductor L1, the grid power supply, switch Q2, and switch Q8.

[0042] In the second stage of energy transfer, switch Q8 initially lags behind switch Q6 in phase shift. Energy is stored in the second power inductor L2 through a second energy storage circuit consisting of the DC power supply, the second power inductor L2, switch Q6, and switch Q8. During this time, switches Q1, Q2, Q3, and Q4 are turned off. After energy storage is complete, the second power inductor L2 transfers energy through a fourth inverter circuit. The energy storage time is determined by the peak value of the grid voltage and the DC voltage difference. The fourth inverter circuit consists of the DC power supply, the second power inductor L2, switch Q6, transformer T1, switch Q4, the first power inductor L1, the grid power supply, switch Q1, and switch Q7. During the dead time, switches Q9 and Q10 provide a freewheeling circuit for the first power inductor L1.

[0043] Therefore, the hybrid-mode-based single-stage DCAC inverter circuit of the present invention can ensure high efficiency while maintaining a high power factor (PF). Simultaneously, the single-stage DCAC inverter circuit can switch between BUCK mode and phase-shifting mode according to the DC voltage and grid voltage, thus allowing it to operate continuously in single-stage power conversion mode, thereby improving efficiency. Furthermore, the secondary-side power transmission module of the present invention includes a first power inductor, a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch; the primary-side power transmission module includes a seventh switch, an eighth switch, a ninth switch, a tenth switch, a diode, and a second power inductor. Thus, the present invention uses switches instead of mechanical relays for switching, enabling rapid charging high / low voltage switching with a microsecond-level response time, far faster than the millisecond-level response time of mechanical switches. In addition, the present invention reduces the number of switches compared to a two-stage topology, lowering costs.

[0044] Although the present invention has been described through specific embodiments, those skilled in the art will understand that various modifications and equivalent substitutions can be made to the invention without departing from its scope. Furthermore, various modifications can be made to the invention for specific situations or materials without departing from its scope. Therefore, the present invention is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single-stage DCAC inverter circuit based on hybrid mode, characterized in that, Includes: a transformer module, a primary power transmission module disposed on the primary winding of the transformer module, and a secondary power transmission module disposed on the secondary winding of the transformer module; The secondary power transmission module is connected to the grid power supply to supply grid voltage, and the primary power transmission module is connected to the DC power supply to receive DC voltage. When the DC voltage is greater than the peak value of the grid voltage, or when the DC voltage is less than the peak value of the grid voltage and a first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode, wherein the first condition is that the instantaneous voltage is between the DC voltage and the zero point of the grid voltage. When the DC voltage is less than the peak value of the grid voltage and the second condition is met, the single-stage DCAC inverter circuit operates in phase-shift mode, wherein the second condition is that the instantaneous voltage is between the peak value of the DC voltage and the peak value of the grid voltage.

2. The single-stage DCAC inverter circuit based on hybrid mode according to claim 1, characterized in that, The secondary power transmission module includes a first power inductor, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a fifth switching transistor, and a sixth switching transistor; The control terminals of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch receive control signals. The first end of the first switch, the first end of the second switch, and the first end of the fifth switch are connected to the first end of the first power inductor. The second end of the first power inductor is connected to the first end of the mains power supply. The second end of the first switch is connected to the same-name terminal of the first winding of the transformer module. The second end of the second switch is connected to the opposite-name terminal of the first winding of the transformer module. The second end of the fifth switch is connected to the second end of the sixth switch. The first end of the sixth switch, the first end of the third switch, and the first end of the fourth switch are connected to the second end of the mains power supply. The second end of the third switch is connected to the same-name terminal of the first winding of the transformer module. The second end of the fourth switch is connected to the opposite-name terminal of the first winding of the transformer module.

3. The single-stage DCAC inverter circuit based on hybrid mode according to claim 2, characterized in that, The primary-side power transmission module includes a seventh switch, an eighth switch, a ninth switch, a tenth switch, a diode, and a second power inductor; The control terminals of the seventh, eighth, ninth, and tenth switches receive control signals. The first terminal of the seventh switch is connected to the second terminal of the eighth switch and the same-name terminal of the second winding of the transformer module. The second terminal of the seventh switch is connected to the second terminal of the ninth switch, the first terminal of the second power inductor, and the anode of the diode. The second terminal of the second power inductor and the cathode of the diode are connected to the positive terminal of the DC power supply. The first terminal of the ninth switch is connected to the second terminal of the tenth switch and the opposite-name terminal of the second winding of the transformer module. The first terminals of the eighth and tenth switches are connected to the negative terminal of the DC power supply.

4. The single-stage DCAC inverter circuit based on hybrid mode according to claim 3, characterized in that, When the DC voltage is greater than the peak value of the grid voltage, the single-stage DCAC inverter circuit operates in BUCK mode: The DC power supply, the second power inductor, the seventh switch, the eighth switch, the ninth switch, the tenth switch, and the transformer module constitute a BUCK secondary full-bridge circuit; The transformer module, the first switch, the second switch, the third switch, the fourth switch, the first power inductor, and the mains power supply constitute the primary circuit.

5. The single-stage DCAC inverter circuit based on hybrid mode according to claim 4, characterized in that, When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the positive half-cycle: The DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the mains power supply, the fourth switch, and the tenth switch constitute the first inverter circuit; The DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the mains power supply, the third switch, and the eighth switch constitute the second inverter circuit; During the dead time, the diode provides a freewheeling path for the second power inductor, and the fifth and sixth switches provide a freewheeling path for the first power inductor.

6. The single-stage DCAC inverter circuit based on hybrid mode according to claim 4, characterized in that, When the single-stage DCAC inverter circuit operates in BUCK mode and the grid voltage is in the negative half-cycle: The DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the mains power supply, the second switch, and the tenth switch constitute the first inverter circuit; The DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the mains power supply, the first switch, and the eighth switch constitute the second inverter circuit; During the dead time, the diode provides a freewheeling path for the second power inductor, and the fifth and sixth switches provide a freewheeling path for the first power inductor.

7. The single-stage DCAC inverter circuit based on hybrid mode according to claim 3, characterized in that, When the DC voltage is less than the peak value of the grid voltage and the first condition is met, the single-stage DCAC inverter circuit operates in BUCK mode, including: When the grid voltage is near the grid zero point, the single-stage DCAC inverter circuit operates in BUCK mode; When the grid voltage is close to the DC voltage, the duty cycle of the seventh switch and the tenth switch reaches the maximum duty cycle and the single-stage DCAC inverter circuit operates in BUCK mode. When the DC voltage is less than the peak value of the grid voltage and the second condition is met, the single-stage DCAC inverter circuit operates in phase-shift mode, including: When the grid voltage exceeds the DC voltage, the single-stage DCAC inverter circuit operates in phase-shift mode, the duty cycles of the seventh and ninth switches remain unchanged, and the duty cycles of the eighth and tenth switches are phase-shifted with lag.

8. The single-stage DCAC inverter circuit based on hybrid mode according to claim 7, characterized in that, When the grid voltage is in the positive half-cycle and the grid voltage is less than the DC voltage: The DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the mains power supply, the fourth switch, and the tenth switch constitute a first inverter circuit; the DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the mains power supply, the third switch, and the eighth switch constitute a second inverter circuit. When the grid voltage is in the positive half-cycle and the grid voltage is greater than the DC voltage: During the first stage of energy transfer, the eighth switch lags behind the seventh switch in phase shift and stores energy in the second power inductor through a first energy storage circuit consisting of the DC power supply, the second power inductor, the seventh switch, and the eighth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, it transfers energy through a third inverter circuit, wherein the third inverter circuit consists of the DC power supply, the second power inductor, the seventh switch, the transformer module, the first switch, the first power inductor, the grid power supply, the fourth switch, and the tenth switch. During the second stage of energy transfer, the tenth switch is phase-shifted and lags behind the ninth switch. Energy is stored in the second power inductor through a second energy storage circuit consisting of the DC power supply, the second power inductor, the ninth switch, and the tenth switch. At this time, the first, second, third, and fourth switches are turned off. After the second power inductor completes energy storage, energy is transferred through a fourth inverter circuit, which is composed of the DC power supply, the second power inductor, the ninth switch, the transformer module, the second switch, the first power inductor, the grid power supply, the third switch, and the eighth switch. During the dead time, the fifth and sixth switches provide a freewheeling path for the first power inductor.

9. The single-stage DCAC inverter circuit based on hybrid mode according to claim 7, characterized in that, When the grid voltage is in the negative half-cycle and the grid voltage is less than the DC voltage: The DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the mains power supply, the second switch, and the tenth switch constitute a first inverter circuit; the DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the mains power supply, the first switch, and the eighth switch constitute a second inverter circuit. When the grid voltage is in the negative half-cycle and the grid voltage is greater than the DC voltage: During the first stage of energy transfer, the eighth switch lags behind the seventh switch in phase shift and stores energy in the second power inductor through a first energy storage circuit consisting of the DC power supply, the second power inductor, the seventh switch, and the eighth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, it transmits energy through a third inverter circuit, wherein the third inverter circuit consists of the DC power supply, the second power inductor, the seventh switch, the transformer module, the third switch, the first power inductor, the grid power supply, the second switch, and the tenth switch. During the second stage of energy transfer, the tenth switch is phase-shifted and lags behind the ninth switch. Energy is stored in the second power inductor through a second energy storage circuit consisting of the DC power supply, the second power inductor, the ninth switch, and the tenth switch. At this time, the first switch, the second switch, the third switch, and the fourth switch are turned off. After the second power inductor completes energy storage, energy is transferred through a fourth inverter circuit, which is composed of the DC power supply, the second power inductor, the ninth switch, the transformer module, the fourth switch, the first power inductor, the grid power supply, the first switch, and the eighth switch. During the dead time, the fifth and sixth switches provide a freewheeling path for the first power inductor.

10. The single-stage DCAC inverter circuit based on hybrid mode according to any one of claims 3 to 9, characterized in that, It further includes a secondary capacitor; the positive terminal of the secondary capacitor is connected to the positive terminal of the DC power supply, and the negative terminal of the secondary capacitor is grounded.

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