A flyback circuit, controller, electric drive assembly and vehicle

Abstract

This invention relates to the field of power supply technology and discloses a flyback circuit, a controller, an electric drive assembly, and a vehicle. The flyback circuit includes a transformer, a first switching device, and a control circuit. A first terminal on the primary side of the transformer is coupled to a power source. A first terminal of the first switching device is coupled to a second terminal on the primary side of the transformer, and a second terminal of the first switching device is coupled to a first voltage reference terminal. A first terminal of the control circuit is coupled to a first terminal on the secondary side of the transformer, and a second terminal of the control circuit is coupled to a third terminal of the first switching device. The control circuit outputs a pulse modulation signal to the third terminal of the first switching device based on a first voltage output from the first terminal on the secondary side of the transformer, thereby driving the first switching device to operate according to the duty cycle of the pulse modulation signal. Applying the technical solution of this invention enables precise control of the transformer's output voltage.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, specifically to a flyback circuit, a controller, an electric drive assembly, and a vehicle. Background Technology

[0002] In new energy vehicles, transformers are widely used in multiple modules to provide isolated drive for these modules or devices. The output voltage of the transformer affects the vehicle's power performance, energy conversion efficiency, and operational safety. To stabilize the transformer's output voltage, a flyback circuit is typically required to adjust the input voltage of the planar transformer, thereby adjusting its output voltage.

[0003] In related technologies, an auxiliary winding is usually set on the primary side of a planar transformer to transmit feedback signals to the control module, thereby controlling the input voltage on the primary side.

[0004] However, since the secondary side outputs through the transformer turns ratio, the output voltage cannot be precisely controlled due to issues with winding process and consistency. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a flyback circuit, controller, electric drive assembly and vehicle, which aims to solve the technical problem of the inability to accurately control the output voltage in the prior art.

[0006] In a first aspect, embodiments of this application provide a flyback circuit, including: a transformer, a first switching device, and a control circuit. A first terminal on the primary side of the transformer is coupled to a power supply; a first terminal of the first switching device is coupled to a second terminal on the primary side of the transformer; a second terminal of the first switching device is coupled to a first voltage reference terminal; a first terminal of the control circuit is coupled to a first terminal on the secondary side of the transformer; and a second terminal of the control circuit is coupled to a third terminal of the first switching device. The control circuit is configured to: output a pulse modulation signal to the third terminal of the first switching device based on a first voltage output from the first terminal on the secondary side of the transformer, thereby driving the first switching device to operate according to the duty cycle of the pulse modulation signal.

[0007] In this embodiment, the flyback circuit directly acquires the first voltage output from the secondary side of the transformer through a control circuit, and generates a pulse modulation signal based on this voltage to regulate the duty cycle of the first switching device. Since the first voltage directly reflects the actual output voltage state, using it as a feedback signal avoids the output voltage being affected by the transformer windings. This enables precise and real-time adjustment of the on / off state of the first switching device, thereby stabilizing the output voltage on the secondary side of the transformer and effectively improving the accuracy and stability of the circuit's output voltage. Furthermore, this embodiment eliminates the need for an auxiliary winding on the primary side of the transformer and requires no additional power supply, reducing transformer costs.

[0008] In one possible embodiment, the second terminal on the secondary side of the transformer is coupled to a second voltage reference terminal.

[0009] In conjunction with the above embodiments, the second terminal on the secondary side of the transformer is coupled to the second voltage reference terminal, which can effectively fix the voltage reference at the transformer output terminal and eliminate potential drift and static electricity accumulation caused by floating potential. Simultaneously, it can significantly improve the system's electromagnetic compatibility performance, suppress the influence of external electromagnetic interference on the output signal, enhance the stability and safety of the load operation on the secondary side of the transformer, and reduce the overall system cost and complexity.

[0010] In one possible embodiment, the third terminal of the control circuit is coupled to the first voltage reference terminal, and the fourth terminal of the control circuit is coupled to the second voltage reference terminal.

[0011] In the above embodiment, one side of the transformer is low-voltage and the other side is high-voltage. The first terminal of the control circuit is coupled to the first terminal on the secondary side of the transformer, and the fourth terminal of the control circuit is coupled to the second voltage reference terminal. The second terminal of the control circuit is coupled to the third terminal of the first switching device, and the third terminal of the control circuit is coupled to the first voltage reference terminal. This allows the control circuit to achieve precise potential matching and electrical isolation between the high and low voltage circuits, effectively blocking interference crosstalk between the high and low voltage sides and ensuring the stability and accuracy of control signal transmission. Simultaneously, it clearly defines the electrical boundaries between high and low voltage, reducing insulation risks caused by potential differences, improving the electrical safety performance of the circuit, and enhancing the overall reliability and anti-interference capability of the circuit operation.

[0012] In one possible embodiment, the control circuit is specifically configured to: output a first pulse modulation signal to the third terminal of the first switching device when the first voltage equals the first target voltage; output a second pulse modulation signal to the third terminal of the first switching device when the first voltage is greater than the first target voltage; and output a third pulse modulation signal to the third terminal of the first switching device when the first voltage is less than the first target voltage. The duty cycle of the second pulse modulation signal is less than the duty cycle of the first pulse modulation signal, and the duty cycle of the third pulse modulation signal is greater than the duty cycle of the first pulse modulation signal.

[0013] In this embodiment, the first voltage output from the first terminal of the secondary side of the transformer is proportional to the input voltage of the primary side. Therefore, when the first voltage equals the first target voltage, the input voltage of the primary side of the transformer remains unchanged; when the first voltage is greater than the first target voltage, the input voltage of the primary side of the transformer needs to be reduced; and when the first voltage is less than the first target voltage, the input voltage of the primary side of the transformer needs to be increased. By comparing the first voltage and the first target voltage, the control circuit adjusts the pulse modulation signal output to the first switching device, thereby achieving precise control of the output voltage.

[0014] In one possible embodiment, the third terminal on the secondary side of the transformer is used to output a second voltage, where the first voltage is greater than the voltage corresponding to the second voltage reference terminal, and the voltage corresponding to the second voltage reference terminal is greater than the second voltage.

[0015] In this embodiment, the first voltage is greater than the voltage corresponding to the second voltage reference terminal, and the voltage corresponding to the second voltage reference terminal is greater than the second voltage. The transformer adopts a bipolar output mode with positive and negative voltage output, which can directly provide symmetrical dual power supply to loads such as differential circuits and power drive modules without the need for additional polarity conversion or level boosting circuits. This effectively simplifies the topology and expands the load adaptability range of the transformer, meeting the power supply needs of more high-voltage and high-precision electrical equipment.

[0016] In one possible embodiment, the flyback circuit further includes a voltage regulator circuit coupled between the second and third terminals of the transformer's secondary side, used to stabilize the second voltage output from the third terminal of the transformer's secondary side at the second target voltage.

[0017] In this embodiment, the second voltage between the third and second terminals on the secondary side of the transformer depends entirely on the turns ratio of the transformer windings. To prevent the second voltage from shifting under load fluctuations or input disturbances, a voltage regulator circuit is installed between the second and third terminals on the secondary side of the transformer to accurately stabilize the output of the second voltage. This suppresses the interference of negative voltage drift on the circuit's operating state, ensures accurate and reliable signal transmission and control logic, reduces the risk of circuit failure caused by abnormal negative voltage fluctuations, and improves the overall circuit's anti-interference capability and operational reliability.

[0018] In one possible embodiment, the voltage regulator circuit includes: a linear regulator and a voltage divider circuit, wherein a first terminal of the linear regulator is coupled to a third terminal on the secondary side of the transformer, a second terminal of the linear regulator is coupled to a second terminal on the secondary side of the transformer, a first terminal of the voltage divider circuit is coupled to a first terminal of the linear regulator, a second terminal of the voltage divider circuit is coupled to a second terminal of the linear regulator, and a third terminal of the voltage divider circuit is coupled to a third terminal of the linear regulator.

[0019] This embodiment employs a voltage regulation structure combining a linear regulator and a voltage divider circuit. The linear regulator is directly coupled to the secondary side of the transformer, enabling stable output voltage and effectively suppressing the effects of voltage fluctuations, load changes, and temperature drift on the secondary side of the transformer, significantly improving output voltage accuracy and stability. Simultaneously, the adjustment of the voltage divider circuit further optimizes the voltage regulation response speed, adapting to the precise requirements of high-voltage power supply, and comprehensively improving the system's power supply reliability and operational stability.

[0020] In one possible embodiment, the voltage regulator circuit further includes a second switching device, which is used to release voltage through a linear regulator when the second voltage is greater than the second target voltage.

[0021] In conjunction with the above embodiments, the voltage regulator circuit also includes a second switching device. When the second voltage exceeds the second target voltage, this device, in conjunction with the linear regulator, enables rapid voltage and current discharge, effectively preventing overvoltage surges from damaging downstream components and forming a comprehensive overvoltage protection mechanism. Simultaneously, the second switching device, together with the voltage divider circuit and the linear regulator, constitutes a closed-loop regulation architecture. This retains the original precise voltage regulation function while dynamically adapting to voltage fluctuations and load changes, further improving the stability and reliability of the output voltage. This strengthens the circuit's safety protection capabilities while ensuring long-term stable system operation.

[0022] In one possible embodiment, the voltage divider circuit includes: a first resistor and a second resistor, a first end of the first resistor being coupled to a second end of a second switching device, a first end of the second resistor being coupled to a second end of the first resistor, and a second end of the second resistor being coupled to a second end of a linear regulator.

[0023] In conjunction with the above embodiments, the voltage divider circuit adopts a pure resistive voltage divider structure composed of a first resistor and a second resistor connected in series. This results in a simple circuit topology, reducing hardware costs and layout complexity. This voltage divider circuit directly couples to the second switching device and the linear regulator, enabling stable transmission of the real-time voltage signal to the voltage regulation terminal. This ensures accurate response and coordinated operation of the linear regulator's voltage regulation and the second switching device's overvoltage relief action, effectively improving voltage control accuracy. The resistive voltage divider structure exhibits low temperature drift and strong anti-interference capability, making it suitable for high-voltage side operating environments. This further enhances the overall stability and reliability of the voltage regulator circuit and ensures high compatibility with high- and low-voltage isolation and symmetrical output circuit architectures.

[0024] In one possible embodiment, the flyback circuit further includes: a first diode, a first end of which is coupled to a first end of the secondary side of the transformer, a second end of which is coupled to a first end of the control circuit, and the first diode being turned on from the first end to the second end.

[0025] In this embodiment, a unidirectional conducting first diode is provided at the first end of the transformer secondary side. Its unidirectional conductivity enables directional energy transfer and rectified output from the transformer secondary side, effectively preventing reverse current from flowing back to the transformer secondary side and avoiding circuit malfunctions caused by reverse surges. Furthermore, the first diode can block crosstalk between high and low voltage sides, providing a stable and clean feedback signal to the control circuit and improving the accuracy of the output pulse modulation signal. Moreover, the diode has a simple structure and strong adaptability, enhancing system stability and safety.

[0026] In one possible embodiment, the flyback circuit further includes: a second diode, the first end of which is coupled to the first end of the second switching device, the second end of which is coupled to the third end of the secondary side of the transformer, and the second diode being turned on from the first end to the second end.

[0027] In conjunction with the above embodiments, a unidirectional second diode is installed on the secondary side of the transformer. Its unidirectional conduction characteristic effectively blocks reverse voltage and current flow between the secondary side of the transformer and the second switching device, preventing abnormal reverse potential from causing damage to core voltage regulator components such as the second switching device and the linear regulator. Simultaneously, the second diode, in conjunction with the voltage relief regulation function of the second switching device, enables directional transmission and orderly discharge of energy in the negative voltage side voltage regulation circuit, further improving the accuracy and response speed of voltage regulation, and optimizing the voltage waveform and operational stability on the secondary side of the flyback circuit.

[0028] Secondly, embodiments of this application provide a controller including the flyback circuit described in the first aspect.

[0029] Thirdly, embodiments of this application provide an electric drive assembly, including a flyback circuit as described in the first aspect, or a controller as described in the second aspect.

[0030] Fourthly, embodiments of this application provide a vehicle including a flyback circuit as described in the first aspect, a controller as described in the second aspect, or an electric drive assembly as described in the third aspect. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application will be described below.

[0032] Figure 1 This is a schematic diagram of the structure of an electric drive assembly provided in an embodiment of this application; Figure 2 This is a schematic diagram of a transformer control circuit provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of a controller provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a flyback circuit disclosed in an embodiment of this application; Figure 5 This is a schematic diagram of another flyback circuit disclosed in an embodiment of this application; Figure 6 This is a schematic diagram of another flyback circuit disclosed in an embodiment of this application; Figure 7 This is a schematic diagram of another flyback circuit disclosed in an embodiment of this application; Figure 8 This is a schematic diagram of another flyback circuit disclosed in an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures: 1000-Electric drive assembly; 100 - Controller; 200 - Drive motor; 10 - Transformer control circuit; 20 - Flyback circuit; 30 - Control circuit; 40 - Inverter drive module; 101 - First control module; 102 - Second control module; 201 - Control circuit; 202 - Voltage regulator circuit; 2021 - Voltage divider circuit; VDD - Power supply; G1 - First voltage reference terminal; G2 - Second voltage reference terminal; T0 - Planar transformer; T1 - Transformer; L1 - Input winding; L2 - Auxiliary winding; L3 - Output winding; Q1 - First switching device; Q2 - Second switching device; Q3 - Third switching device; Q21 - Transistor; Q22 - Switching transistor; D0 - Output diode; D1 - First diode; D2 - Second diode; D3 - Linear regulator; Dz - Zener diode; R1 - First feedback resistor; R2 - Second feedback resistor; R3 - Current-limiting resistor; R4 - First resistor; R5 - Second resistor. Detailed Implementation

[0034] The terms “first,” “second,” etc., are used for descriptive purposes only and have no sequential or technical meaning, nor should they be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0035] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the terms "coupled" and "connected" refer to the flow of current or signal from one conductor to another. A connection between A and B means that current or signal can flow from A to B and vice versa. A connection between A and B includes direct electrical connection and indirect electrical connection. A direct electrical connection between A and B means that A and B are electrically connected through physical contact. An indirect electrical connection between A and B means that A and B are electrically connected through C, where C can be at least one wire or device.

[0036] The embodiments of this application are described below with reference to the accompanying drawings.

[0037] In new energy vehicles, the electric drive assembly (EDA) serves as the core power unit, used to convert electrical energy into mechanical energy to drive the vehicle.

[0038] like Figure 1 As shown, the electric drive assembly 1000 mainly includes a controller (also known as a motor controller) 100, a drive motor 200, and related auxiliary units. Among them, the controller 100 serves as the control core, regulating the transmission of electrical energy, and the drive motor 200 receives the control signals from the controller and outputs mechanical energy.

[0039] Planar transformers are widely used in controllers and related collaborative modules, enabling the conversion between high and low voltage. When converting high voltage to low voltage, the planar transformer outputs electrical signals to the controller's control circuitry and the vehicle's low-voltage electrical equipment. Conversely, when converting low voltage to high voltage, it outputs electrical signals to the drive motor and inverter drive module, meeting the power drive requirements of the electric drive assembly.

[0040] The on-board charger (OBC), DC-DC converter, and high-voltage power distribution system all work together with the electric drive assembly. The internal power conversion and drive modules rely on planar transformers to achieve voltage conversion and electrical signal transmission, ensuring the stable operation of the electric drive assembly.

[0041] The accuracy and stability of the planar transformer directly affect the control effect of the controller and the operating efficiency of the electric drive assembly, which in turn directly affect the vehicle's power performance, energy conversion efficiency, and operational safety.

[0042] To ensure a stable output voltage from a planar transformer, a flyback circuit is typically required to adjust the input voltage of the planar transformer, thereby adjusting its output voltage.

[0043] In some embodiments, an auxiliary winding is typically provided on the primary side of the planar transformer to transmit feedback signals to the control module, thereby controlling the input voltage on the primary side.

[0044] Example, Figure 1 This is a schematic diagram of a transformer control circuit (also known as a flyback circuit; to distinguish it from the flyback circuit provided in this application, it is referred to as a transformer control circuit) provided in an embodiment of this application.

[0045] The transformer control circuit 10 includes: power supply VDD, first control module 101, second control module 102, planar transformer T0, third switching device Q3, output diode D0, Zener diode Dz (also known as reverse breakdown diode or Zener diode), first feedback resistor R1, second feedback resistor R2, and current limiting resistor R3.

[0046] The primary side of the planar transformer T0 is provided with an input winding L1 and an auxiliary winding L2, and the secondary side is provided with an output winding L3.

[0047] Among them, the third switching device Q3 is usually a controllable MOSFET.

[0048] The first control module 101 uses a power supply chip, and the second control module 102 uses a low dropout regulator (LDO).

[0049] The power supply VDD can be a single-ended primary inductor converter (Sepic) from the front-end, a buck-boost converter, or a constant power supply from the vehicle level (such as KL30).

[0050] The first terminal (positive terminal) of the power supply VDD is coupled to the first terminal of the input winding L1, the first terminal (drain terminal) of the third switching device Q3 is coupled to the second terminal of the input winding L1, the second terminal (source terminal) of the third switching device Q3 is coupled to the second terminal (negative terminal) of the power supply VDD, and the third terminal (gate terminal) of the third switching device Q3 is coupled to the first control module 101.

[0051] The first end of the auxiliary winding L2 is coupled to the first control module 101, the second end of the auxiliary winding L2 is coupled to the first voltage reference terminal G1, and the first control module 101 is also coupled to the first voltage reference terminal G1.

[0052] The auxiliary winding L2, after being transformed from the input winding L1 through magnetic induction and turns ratio, inputs a first feedback signal to the first control module 101 through the first terminal of the auxiliary winding L2. The first control module 101 determines a pulse width modulation (PWM) signal based on the voltage value of the first feedback signal, thereby driving the third switching device Q3 to operate according to the duty cycle of the PWM signal, and thus modifying the input voltage input to both ends of the input winding L1.

[0053] The first end of the output winding L3 is coupled to the first end of the second control module 102 through the output diode D0. Specifically, the first end of the output diode D0 is coupled to the first end of the output winding L3, and the second end of the output diode D0 is coupled to the second control module 102. The output diode D0 is turned on from the first end to the second end.

[0054] The first end of the current-limiting resistor R3 is coupled to the second end of the output diode D0, and the second end of the current-limiting resistor R3 is coupled to the second voltage reference terminal G2.

[0055] The first terminal of the Zener diode Dz is coupled to the second terminal of the output winding L3, serving as the negative voltage output terminal of the planar transformer T0. The second terminal of the Zener diode Dz is coupled to the second voltage reference terminal G2.

[0056] A first feedback resistor R1 is provided between the second and third terminals of the second control module 102, and a second feedback resistor R2 is provided between the third terminal of the second control module 102 and the second voltage reference terminal G2. The second terminal of the second control module 102 serves as the positive voltage output terminal of the planar transformer T0.

[0057] Among them, the planar transformer T0 is a high-frequency transformer composed of printed circuit board (PCB) windings or thin copper sheet windings and a flat magnetic core. The first voltage reference terminal G1 and the second voltage reference terminal G2 are the grounding terminals of the low-voltage side and the high-voltage side, respectively.

[0058] As can be seen from the above, in related technologies, an auxiliary winding needs to be added to the primary side of the transformer to achieve voltage regulation control. However, since the secondary side outputs through the transformer turns ratio, the output voltage cannot be precisely controlled due to issues with winding technology and consistency. When the output voltage cannot meet the high-voltage drive requirements in vehicles, an integrated circuit (IC) power supply needs to be added to make the output voltage meet the requirements, thereby increasing the cost of the transformer.

[0059] Based on this, embodiments of this application provide a flyback circuit that can be integrated into the controller of the electric drive assembly for integration into a vehicle. The vehicle can be, but is not limited to, a pure electric vehicle (PEV / BEV), a hybrid electric vehicle (HEV), a range-extended electric vehicle (REEV), a plug-in hybrid electric vehicle (PHEV), or a new energy vehicle.

[0060] Combination Figure 1 ,like Figure 3 As shown, the controller 100 includes a flyback circuit 20, a control circuit 30, and an inverter drive module 40. The flyback circuit 20 is used to perform voltage conversion and provide electrical energy to the control circuit 30 and the inverter drive module 40.

[0061] Combination Figure 3 ,like Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of the flyback circuit 20 disclosed in the embodiments of this application.

[0062] The flyback circuit 20 includes: a transformer T1, a first switching device Q1, a first diode D1, and a control circuit 201.

[0063] Among them, transformer T1 can be a planar transformer.

[0064] The first switching device Q1 can be a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT).

[0065] IGBT is a composite fully controllable voltage-driven power semiconductor device composed of a bipolar junction transistor (BJT) and an insulated-gate field-effect transistor (MOS). It combines the advantages of high input impedance of MOSFET and low on-state voltage drop of power transistor (GTR).

[0066] The primary side of transformer T1 receives a low-voltage input (typically AC less than 30V) and the secondary side outputs a high-voltage output (typically AC greater than or equal to 30V). Therefore, the control circuit 201 can use an isolation chip to achieve electrical isolation between the low-voltage and high-voltage circuits.

[0067] The first terminal of the primary side of transformer T1 is used to couple to the first terminal (i.e., the positive terminal) of power supply VDD. The first terminal of the first switching device Q1 is coupled to the second terminal of the primary side of transformer T1, and the second terminal of the first switching device Q1 is coupled to the first voltage reference terminal G1.

[0068] The first terminal of the control circuit 201 is coupled to the first terminal of the secondary side of the transformer T1, and the second terminal of the secondary side of the transformer T1 is coupled to the second voltage reference terminal G2.

[0069] The second terminal of the control circuit 201 is coupled to the third terminal of the first switching device Q1, the third terminal of the control circuit 201 is coupled to the first voltage reference terminal G1, and the fourth terminal of the control circuit 201 is coupled to the second voltage reference terminal G2.

[0070] The first diode D1 has its first end coupled to the first end of the secondary side of the transformer T1, and its second end coupled to the first end of the control circuit 201. The first diode D1 is turned on from its first end to its second end.

[0071] In this embodiment, the power supply VDD can be from the Sepic converter, Buck-Boost converter, or constant power supply in the vehicle level.

[0072] The control circuit 201 is used to output a pulse modulation signal to the third terminal of the first switching device Q1 according to the first voltage output from the first terminal of the secondary side of the transformer T1, so as to drive the first switching device Q1 to work according to the duty cycle of the pulse modulation signal.

[0073] Specifically, the control circuit 201 can output a pulse modulation signal to the third terminal of the first switching device Q1 based on the first voltage and the first target voltage (i.e., the voltage required by the electrical device coupled to the first terminal of the secondary side) output from the first terminal of the transformer T1.

[0074] In this embodiment, since the power supply VDD forms a power supply circuit with the primary winding L2 of transformer T1 and the first switching device Q1, the input voltage on the primary side of transformer T1 satisfies the following formula: V in =V×D; Among them, V inV is the input voltage on the primary side of transformer T1, V is the output voltage of power supply VDD, and D is the duty cycle of the pulse modulation signal that drives the first switching device Q1.

[0075] Furthermore, the first voltage output from the first terminal of the secondary side of transformer T1 is proportional to the input voltage of the primary side of transformer T1. Therefore, when the first voltage equals the first target voltage, the current input voltage of the primary side of transformer T1 remains unchanged; when the first voltage is greater than the first target voltage, the input voltage of the primary side of transformer T1 needs to be reduced; and when the first voltage is less than the first target voltage, the input voltage of the primary side of transformer T1 needs to be increased.

[0076] Specifically, when the first voltage equals the first target voltage, the control circuit 201 outputs a first pulse modulation signal to the third terminal of the first switching device Q1. The first pulse modulation signal is the pulse modulation signal currently driving the first switching device Q1.

[0077] When the first voltage is greater than the first target voltage, the control circuit 201 outputs a second pulse modulation signal to the third terminal of the first switching device Q1. The duty cycle of the second pulse modulation signal is less than the duty cycle of the first pulse modulation signal.

[0078] When the first voltage is less than the first target voltage, the control circuit 201 outputs a third pulse modulation signal to the third terminal of the first switching device Q1. The duty cycle of the third pulse modulation signal is greater than the duty cycle of the first pulse modulation signal.

[0079] For example, taking a first target voltage of 100V as an example, assume that the duty cycle of the pulse modulation signal is 0.75 at this time.

[0080] If the control circuit 201 detects that the first voltage is 100V, it means that the input voltage of the input transformer meets the requirements and no adjustment is needed. At this time, the pulse modulation signal is the first pulse modulation signal.

[0081] If the control circuit 201 detects a first voltage of 115V, it indicates that the input voltage of the input transformer T1 is too high. In this case, the duty cycle of the pulse modulation signal can be adjusted to 0.70, or even 0.65, to reduce the input voltage of the input transformer T1, thereby decreasing the first voltage. The pulse modulation signal at this point is the second pulse modulation signal. If the first voltage is still not equal to the first target voltage after adjustment, the duty cycle of the pulse modulation signal needs to be further adjusted based on the first voltage and the first target voltage until the first voltage equals the first target voltage.

[0082] If the control circuit 201 detects a first voltage of 85V, it indicates that the input voltage of the input transformer T1 is too low. In this case, the duty cycle of the pulse modulation signal can be adjusted to 0.80, or even 0.85, to increase the input voltage of the input transformer T1, thereby increasing the first voltage. The pulse modulation signal at this time is the third pulse modulation signal. If the first voltage is still not equal to the first target voltage after adjustment, the duty cycle of the pulse modulation signal needs to be adjusted further based on the first voltage and the first target voltage until the first voltage equals the first target voltage. In the above embodiment, a unidirectional conducting first diode D1 is provided at the first end of the secondary side of transformer T1. Its unidirectional conductivity allows for directional energy transfer and rectification output from the secondary side of transformer T1, effectively preventing reverse current from flowing back to the secondary side of transformer T1 and avoiding reverse surges that could cause abnormal circuit operation.

[0083] Transformer T1 has low-voltage electricity on one side and high-voltage electricity on the other side. Control circuit 201 can achieve precise potential matching and electrical isolation between the high and low voltage circuits, effectively blocking interference crosstalk between the high and low voltage sides, and ensuring the stability and accuracy of control signal transmission.

[0084] As can be seen from the above, based on the flyback circuit provided in this application embodiment, the flyback circuit 20 directly acquires the first voltage output from the secondary side of transformer T1 through the control circuit 201, and generates a pulse modulation signal based on this voltage to regulate the duty cycle of the first switching device. Since the first voltage directly reflects the actual output voltage state, using the first voltage as a feedback signal avoids the output voltage being affected by the winding of transformer T1, enabling precise and real-time adjustment of the on and off states of the first switching device, thereby stabilizing the output voltage on the secondary side of transformer T1 and effectively improving the accuracy and stability of the circuit output voltage. Moreover, this application embodiment does not require adding an auxiliary winding to the primary side of transformer T1, nor does it require adding an additional IC power supply, which can reduce the cost of transformer T1.

[0085] Combination Figure 4 ,like Figure 5 As shown, the secondary winding of transformer T1 includes three taps. The first tap, which is the first terminal of the secondary winding of transformer T1, is used to output the first voltage. The second tap, which is the second terminal of the secondary winding of transformer T1, is used to connect to the second voltage reference terminal. The third tap, which is the third terminal of the secondary winding of transformer T1, is used to output the second voltage.

[0086] Wherein, the first voltage is greater than the voltage corresponding to the second voltage reference terminal G2, and the voltage corresponding to the second voltage reference terminal G2 is greater than the second voltage.

[0087] The first voltage is the voltage between the first terminal of the secondary side of transformer T1 and the second voltage reference terminal, and the second voltage is the voltage between the second terminal of the secondary side of transformer T1 and the second voltage reference terminal. That is, the first voltage is usually positive, and the second voltage is usually negative.

[0088] In this way, positive voltage can be output through the first terminal of transformer T1, and negative voltage can be output through the third terminal. Transformer T1 adopts a bipolar output mode with both positive and negative voltages, which can directly provide symmetrical dual power supply to loads such as differential circuits and power drive modules without the need for additional polarity conversion or level shifting circuits. This effectively simplifies the topology and broadens the load adaptability range of the transformer, meeting the power supply needs of more high-voltage and high-precision electrical equipment. By using transformer T1, various application scenarios in vehicles can be met.

[0089] In this embodiment, the first voltage between the first and second terminals of the secondary side of transformer T1 is input as a feedback signal to the control circuit 201, enabling precise control of the first voltage. The second voltage between the third and second terminals of the secondary side of transformer T1 depends entirely on the turns ratio of the windings in transformer T1. To prevent the second voltage from shifting under load fluctuations or input disturbances, [further details are needed]. Figure 5 In the embodiment shown, the flyback circuit 20 further includes a voltage regulator circuit 202.

[0090] The voltage regulator circuit 202 is coupled between the second and third terminals of the secondary side of transformer T1, and is used to stabilize the second voltage output from the third terminal of the secondary side of transformer T1 to the second target voltage.

[0091] In this embodiment, the second voltage between the third and second terminals of the secondary side of transformer T1 depends entirely on the turns ratio of the transformer windings. To prevent the second voltage from shifting under load fluctuations or input disturbances, a voltage regulator circuit 202 is provided between the second and third terminals of the secondary side of transformer T1, which can accurately stabilize the output of the second voltage. This suppresses the interference of negative voltage drift on the circuit's operating state, ensures accurate and reliable signal transmission and control logic, reduces the risk of circuit failure caused by abnormal negative voltage fluctuations, and improves the overall circuit's anti-interference capability and operational reliability.

[0092] In some embodiments, such as Figure 5 As shown, the voltage regulator circuit 202 includes: a Zener diode, a Zener diode Dz, the first end of which is coupled to the third end of the secondary side of the transformer T1, and the second end of which is coupled to the second end of the secondary side of the transformer T1, for stabilizing the second voltage output from the third end of the secondary side of the transformer T1 to the second target voltage.

[0093] In some embodiments, such as Figure 6 As shown, the flyback circuit 20 also includes a second diode D2, and the voltage regulator circuit 202 includes a linear regulator D3 and a voltage divider circuit 2021.

[0094] The first end of the second diode D2 is coupled to the first end of the linear regulator D3, and the second end of the second diode D2 is coupled to the third end of the secondary side of the transformer T1. The second diode D2 is turned on from the first end to the second end.

[0095] The first terminal of the linear regulator D3 is coupled to the third terminal of the secondary side of the transformer T1, the second terminal of the linear regulator D3 is coupled to the second terminal of the secondary side of the transformer T1, the first terminal of the voltage divider circuit 2021 is coupled to the first terminal of the linear regulator D3, the second terminal of the voltage divider circuit 2021 is coupled to the second terminal of the linear regulator D3, and the third terminal of the voltage divider circuit 2021 is coupled to the third terminal of the linear regulator D3.

[0096] The voltage divider circuit 2021 includes: a first resistor R4 and a second resistor R5. The first end of the first resistor R4 serves as the first end of the voltage divider circuit 2021. The first end of the second resistor R5 is coupled to the second end of the first resistor R4 and serves as the third end of the voltage divider circuit 2021. The second end of the second resistor R5 serves as the second end of the voltage divider circuit 2021.

[0097] In this configuration, the second diode D2 is used to conduct during the negative half-cycle of the AC circuit, working in conjunction with the first diode D1 to achieve full-wave rectification. Since the first voltage output from the first terminal of the secondary side of transformer T1 is greater than the second voltage reference terminal G2, the second voltage output from the third terminal of the secondary side of transformer T1 is less than the second voltage reference terminal G2. During the positive half-cycle of the AC circuit, the first diode D1 conducts, rectifying the voltage output from the first terminal of the secondary side of transformer T1 into DC. During the negative half-cycle of the AC circuit, the second diode D2 conducts, rectifying the voltage output from the second terminal of the secondary side of transformer T1 into DC for use by the load.

[0098] In this embodiment, a voltage regulation structure using a linear regulator D3 paired with a voltage divider circuit 2021 is employed. The linear regulator D3 is directly coupled to the secondary side of transformer T1, enabling stable output voltage and effectively suppressing the effects of voltage fluctuations, load changes, and temperature drift on the secondary side of transformer T1, thus significantly improving the accuracy and stability of the output voltage. Simultaneously, the adjustment of the voltage divider circuit 2021 further optimizes the voltage regulation response speed, adapting to the precise requirements of high-voltage power supply and comprehensively improving the system's power supply reliability and operational stability.

[0099] Since the voltage between the third terminal and the first terminal of the linear regulator D3 is a fixed voltage Vref, the second voltage can be stabilized at the second target voltage through the combination of the linear regulator D3 and the voltage divider circuit 2021.

[0100] Since the voltage between the third terminal and the first terminal of the linear regulator D3 is a fixed voltage Vref (typically 2.5V), in this embodiment, the second voltage satisfies the following formula: Vout2 = -Vref × (1 + R5 / R4); Where Vref is a fixed voltage between the third terminal and the first terminal of the linear regulator D3, R4 is the resistance value of the first resistor R4, and R5 is the resistance value of the second resistor R5.

[0101] In other embodiments, such as Figure 7 As shown, the flyback circuit 20 also includes a second diode D2, and the voltage regulator circuit 202 includes a linear regulator D3, a voltage divider circuit 2021, and a second switching device Q2. Figure 7 The following explanation uses a transistor as an example of the second switching device Q2.

[0102] Transistor Q21 can be a PNP type transistor.

[0103] The first end of the second diode D2 is coupled to the first end of the linear regulator D3, and the second end of the second diode D2 is coupled to the third end of the secondary side of the transformer T1. The second diode D2 is turned on from the first end to the second end.

[0104] The first terminal of the linear regulator D3 is coupled to the third terminal of the secondary side of the transformer T1, the second terminal of the linear regulator D3 is coupled to the second terminal of the secondary side of the transformer T1, the first terminal of the voltage divider circuit 2021 is coupled to the first terminal of the linear regulator D3, the second terminal of the voltage divider circuit 2021 is coupled to the second terminal of the linear regulator D3, and the third terminal of the voltage divider circuit 2021 is coupled to the third terminal of the linear regulator D3.

[0105] The voltage divider circuit 2021 includes: a first resistor R4 and a second resistor R5. The first end of the first resistor R4 is coupled to the second end of the transistor Q21. The first end of the second resistor R5 is coupled to the second end of the first resistor R4. The second end of the second resistor R5 is coupled to the second end of the linear regulator D3.

[0106] The first terminal (collector) of transistor Q21 is coupled to the third terminal on the secondary side of transformer T1. The second terminal (emitter) of transistor Q21 is coupled to the first terminal of voltage divider circuit 2021. The third terminal (base) of transistor Q21 is coupled to the first terminal of linear regulator D3. This is used to release voltage through linear regulator D3 when the second voltage is greater than the second target voltage.

[0107] In this embodiment, the linear regulator D3 only needs to provide the turn-on current of the transistor Q21, which can increase the maximum load capacity by several times and output a stable second voltage.

[0108] In addition, the voltage regulator circuit 202 can add current limiting and over-temperature protection functions to protect the flyback circuit 20.

[0109] In some instances, if the second voltage exceeds the second target voltage, transistor Q21 conducts, allowing voltage relief through the linear regulator D3. Because transistor Q21 has excellent heat dissipation characteristics, it can dissipate heat and prevent damage to the voltage regulator circuit.

[0110] In this embodiment, since the voltage between the second and third terminals of transistor Q21 is a fixed voltage (typically 0.7V) when transistor Q21 is cut off, the second voltage satisfies the following formula: Vout2=(-Vref+0.7)×(1+R4 / R5); Where Vref is a fixed voltage between the third and first terminals of the linear regulator D3, 0.7 is the voltage between the second and third terminals of the transistor Q21, R4 is the resistance value of the first resistor R4, and R5 is the resistance value of the second resistor R5.

[0111] As can be seen from the above, in this embodiment, transistor Q21, in conjunction with linear regulator D3, can achieve rapid voltage and current discharge, effectively preventing overvoltage surges from damaging downstream devices and forming a complete overvoltage protection mechanism. Simultaneously, transistor Q21, voltage divider circuit 2021, and linear regulator D3 work together to form a closed-loop regulation architecture, retaining the original precise voltage regulation function while dynamically adapting to voltage fluctuations and load changes, further improving the stability and reliability of the output voltage. This strengthens circuit safety protection capabilities while ensuring long-term stable system operation.

[0112] Combination Figure 7 ,like Figure 8 As shown, Figure 8 The following explanation uses the second switching device Q2, which uses switching transistor Q22, as an example.

[0113] The first end of the second diode D2 is coupled to the first end of the linear regulator D3, and the second end of the second diode D2 is coupled to the third end of the secondary side of the transformer T1. The second diode D2 is turned on from the first end to the second end.

[0114] The first terminal of the linear regulator D3 is coupled to the third terminal of the secondary side of the transformer T1, the second terminal of the linear regulator D3 is coupled to the second terminal of the secondary side of the transformer T1, the first terminal of the voltage divider circuit 2021 is coupled to the first terminal of the linear regulator D3, the second terminal of the voltage divider circuit 2021 is coupled to the second terminal of the linear regulator D3, and the third terminal of the voltage divider circuit 2021 is coupled to the third terminal of the linear regulator D3.

[0115] In the voltage divider circuit 2021: there is a first resistor R4 and a second resistor R5. The first end of the first resistor R4 is coupled to the second end of the transistor Q21, the first end of the second resistor R5 is coupled to the second end of the first resistor R4, and the second end of the second resistor R5 is coupled to the second end of the linear regulator D3.

[0116] The first terminal of the switching transistor Q22 is coupled to the first terminal of the linear regulator D3, the second terminal of the switching transistor Q22 is coupled to the first terminal of the second diode D2, and the third terminal of the switching transistor Q22 (i.e. the controlled terminal) is coupled to the control circuit 201.

[0117] In this embodiment, the second voltage between the third terminal and the second terminal on the secondary side of transformer T1 is input to the control circuit 201 as a feedback signal, which can achieve precise control of the second voltage.

[0118] The control circuit 201 is used to output a pulse modulation signal to the third terminal of the switching transistor Q22 according to the second voltage output from the third terminal of the secondary side of the transformer T1, so as to drive the switching device switching transistor Q22 to turn on or off.

[0119] For example, when the second voltage is greater than the second target voltage, the control switch Q22 is turned on to relieve pressure through the linear regulator D3. This application also provides a vehicle including the flyback circuit described in the above embodiments.

[0120] Based on the flyback circuit described in the above embodiments, this application also provides a control method for the flyback circuit.

[0121] The control method of the flyback circuit includes: obtaining the first voltage output from the first terminal of the secondary side of the transformer, and outputting a pulse modulation signal to the third terminal of the first switching device according to the first voltage output from the first terminal of the secondary side of the transformer, so as to drive the first switching device to work according to the duty cycle of the pulse modulation signal.

[0122] In some embodiments, outputting a pulse modulation signal to the third terminal of the first switching device based on the first voltage output from the first terminal on the secondary side of the transformer includes: When the first voltage equals the first target voltage, a first pulse modulation signal is output to the third terminal of the first switching device. When the first voltage is greater than the first target voltage, a second pulse modulation signal is output to the third terminal of the first switching device, the duty cycle of the second pulse modulation signal being less than the duty cycle of the first pulse modulation signal. When the first voltage is less than the first target voltage, a third pulse modulation signal is output to the third terminal of the first switching device, the duty cycle of the third pulse modulation signal being greater than the duty cycle of the first pulse modulation signal.

[0123] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. A flyback circuit, characterized in that, include: Transformer (T1), the first end of the primary side of the transformer (T1) is used to couple to a power source; A first switching device (Q1) has a first terminal coupled to a second terminal on the primary side of the transformer (T1), and a second terminal coupled to a first voltage reference terminal (G1). The control circuit (201) has a first terminal coupled to the first terminal of the secondary side of the transformer (T1) and a second terminal coupled to the third terminal of the first switching device (Q1). The control circuit (201) is configured to output a pulse modulation signal to the third terminal of the first switching device (Q1) based on the first voltage output from the first terminal on the secondary side of the transformer (T1), so as to drive the first switching device (Q1) to operate according to the duty cycle of the pulse modulation signal.

2. The flyback circuit according to claim 1, characterized in that, The second terminal of the secondary side of the transformer (T1) is coupled to the second voltage reference terminal (G2), the third terminal of the control circuit (201) is coupled to the first voltage reference terminal (G1), and the fourth terminal of the control circuit (201) is coupled to the second voltage reference terminal (G2).

3. The flyback circuit according to claim 1 or 2, characterized in that, The control circuit (201) is specifically configured as follows: When the first voltage is equal to the first target voltage, a first pulse modulation signal is output to the third terminal of the first switching device (Q1); When the first voltage is greater than the first target voltage, a second pulse modulation signal is output to the third terminal of the first switching device (Q1), and the duty cycle of the second pulse modulation signal is less than the duty cycle of the first pulse modulation signal. When the first voltage is less than the first target voltage, a third pulse modulation signal is output to the third terminal of the first switching device (Q1), and the duty cycle of the third pulse modulation signal is greater than the duty cycle of the first pulse modulation signal.

4. The flyback circuit according to claim 2, characterized in that, The third terminal on the secondary side of the transformer (T1) is used to output a second voltage. The first voltage is greater than the voltage corresponding to the second voltage reference terminal (G2), and the voltage corresponding to the second voltage reference terminal (G2) is greater than the second voltage.

5. The flyback circuit according to claim 4, characterized in that, Also includes: A voltage regulator circuit (202) is coupled between the second and third terminals of the secondary side of the transformer (T1) and is used to stabilize the second voltage output from the third terminal of the secondary side of the transformer (T1) to the second target voltage.

6. The flyback circuit according to claim 5, characterized in that, The voltage regulator circuit (202) includes: A linear regulator (D3) has its first terminal coupled to the third terminal on the secondary side of the transformer (T1), and its second terminal coupled to the second terminal on the secondary side of the transformer (T1). A voltage divider circuit (2021) is provided, wherein the first terminal of the voltage divider circuit (2021) is coupled to the first terminal of the linear regulator (D3), the second terminal of the voltage divider circuit (2021) is coupled to the second terminal of the linear regulator (D3), and the third terminal of the voltage divider circuit (2021) is coupled to the third terminal of the linear regulator (D3).

7. The flyback circuit according to claim 6, characterized in that, The voltage regulator circuit (202) also includes: The second switching device (Q2) is used to release voltage through the linear regulator (D3) when the second voltage is greater than the second target voltage.

8. The flyback circuit according to claim 4, characterized in that, Also includes: The first diode (D1) has its first end coupled to the first end of the secondary side of the transformer (T1), and its second end coupled to the first end of the control circuit (201). The first diode (D1) is turned on from the first end to the second end.

9. The flyback circuit according to claim 7, characterized in that, Also includes: The second diode (D2) has its first end coupled to the first end of the second switching device (Q2), and its second end coupled to the third end of the secondary side of the transformer (T1). The second diode (D2) is conducting from its first end to its second end.

10. A controller, characterized in that, include: The flyback circuit as described in any one of claims 1-9.

11. An electric drive assembly, characterized in that, include: The flyback circuit as described in any one of claims 1-9, or the controller as described in claim 10.

12. A vehicle, characterized in that, include: The flyback circuit as described in any one of claims 1-9, or the controller as described in claim 10, or the electric drive assembly as described in claim 11.

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