A bidirectional converter pair top circuit and a control method thereof

Abstract

The application relates to a bidirectional converter pair-topping circuit and a control method thereof, which comprises a main power circuit, the main power circuit comprising MOS tubes Q8, MOS tubes Q10 and a bidirectional circuit topology; a control circuit comprising a switching circuit and an overcurrent detection circuit, the switching circuit comprising a balancing resistor; when an input driving signal is a high level, the switching circuit controls the MOS tubes Q8 and the MOS tubes Q10 of the main power circuit to be turned on; when the input driving signal is a low level, the on-off of the MOS tubes Q8 and the MOS tubes Q10 in the main power circuit is controlled by adjusting the resistance value of the balancing resistor; the overcurrent detection circuit is used for detecting the current of the main power circuit, and when the current of the main power circuit exceeds a preset value, the switching circuit controls the on-off of the MOS tubes Q8 and the MOS tubes Q10 in the main power circuit. The application has the advantages of fast response speed, no conduction delay, real-time overcurrent monitoring function, reduced control circuit power loss by adopting a current source and a Darlington tube principle, greatly enhanced anti-interference capability, reduced driving current and improved performance of the bidirectional frequency converter.

Description

Technical Field

[0001] This invention relates to the field of bidirectional converter technology, and more specifically to a bidirectional converter top circuit and its control method. Background Technology

[0002] With the rapid development of the new energy industry and the increasing complexity and diversity of application scenarios, the requirements for high power density, high efficiency, and reliability of power systems are becoming increasingly stringent in fields such as electric vehicles, smart grids, and renewable energy storage. As a key component of new energy systems, the performance of power converters directly affects the overall system's operating efficiency and stability.

[0003] Traditional unidirectional converters, due to their inherent limitations such as single function, low energy conversion efficiency, and inability to allow bidirectional energy flow, are gradually failing to meet the high-performance and multi-functional requirements of new energy systems. Therefore, research on bidirectional converters has become a hot topic in the industry. Bidirectional converters not only possess the functions of unidirectional converters but also enable bidirectional energy flow, improving system flexibility and energy utilization.

[0004] In the implementation of bidirectional converters, the existing top-side MOS (Metal-Oxide-Semiconductor) circuit control circuit has problems such as turn-on delay, large drive current, insufficient anti-interference capability, and lack of protection against main power overcurrent, which affect the performance of the converter.

[0005] Therefore, there is an urgent need to provide a bidirectional converter top circuit and its control method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings and defects of the prior art and provide a bidirectional converter top circuit and its control method, which solves the problems of top control circuit conduction delay, large drive current, insufficient anti-interference ability, and lack of protection against main power overcurrent.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A bidirectional converter top circuit and its control method, including a main power circuit, including MOSFET Q8, MOSFET Q10 and a bidirectional circuit topology;

[0009] The control circuit includes a switching circuit and an overcurrent detection circuit. The switching circuit includes a balancing resistor.

[0010] When the input drive signal is high, the switching circuit controls the MOSFETs Q8 and Q10 in the main power circuit to turn on; when the input drive signal is low, the switching on and off of the MOSFETs Q8 and Q10 in the main power circuit is controlled by adjusting the resistance of the balancing resistor.

[0011] The overcurrent detection circuit is used to detect the current of the main power circuit. When the current of the main power circuit exceeds the preset value, the switching circuit controls the switching on and off of MOSFETs Q8 and Q10 in the main power circuit.

[0012] As a preferred embodiment of the present invention, the switching circuit further includes a Darlington transistor, a MOSFET Q1, a transistor Q2, a transistor Q7, a MOSFET Q20, a transistor Q21, and a transistor Q26; the Darlington transistors include Darlington transistor 1, Darlington transistor 2, Darlington transistor 3, and Darlington transistor 4; the overcurrent detection circuit includes a current sampling resistor R9, a current sampling resistor R11, a transistor Q9, and a transistor Q27; the base and emitter of transistor Q9 are connected to both sides of current sampling resistor R9, and the base and emitter of transistor Q27 are connected to both sides of current sampling resistor R11.

[0013] As a preferred embodiment of the present invention, the bidirectional circuit topology is used to receive a positive power-on signal and a reverse power-on signal. When the bidirectional circuit topology receives a positive power-on signal, it operates in the forward direction, with Q8 being an input-paired MOSFET and Q10 being an output-paired MOSFET. When the bidirectional circuit topology receives a reverse power-on signal, it operates in the reverse direction, with Q10 being an input-paired MOSFET and Q8 being an output-paired MOSFET.

[0014] As a preferred embodiment of the present invention, the top-side circuit further includes diodes D3, D4, D12, and D13. The anode of diode D3 is connected to the collector of transistor Q2, and the cathode of diode D3 is connected to resistor R18. The anode of diode D4 is connected to a power supply, and the cathode of diode D4 is connected to resistor R21. The anode of diode D12 is connected to the collector of transistor Q21, and the cathode of diode D12 is connected to resistor R45. The anode of diode D13 is connected to a power supply, and the cathode of diode D4 is connected to resistor R48.

[0015] As a preferred embodiment of the present invention, the top-side circuit further includes resistors R14, R17, and R23, diodes D1 and D2, resistors R21, R44, and R50, diode D10, and diode D11. The anode of diode D1 is connected to resistor R17, and the cathode of diode D1 is connected to the drain of MOSFET Q8. The anode of diode D2 is connected to resistor R23, and diode D2 is connected to the positive input terminal of the bidirectional circuit topology. The anode of diode D10 is connected to resistor R44, and the cathode of diode D10 is connected to the drain of MOSFET Q10. The anode of diode D11 is connected to resistor R50, and diode D11 is connected to the inverting input terminal of the bidirectional circuit topology.

[0016] As a preferred embodiment of the present invention, the overcurrent detection circuit further includes a resistor R12, the two ends of which are respectively connected to the base and collector of the transistor Q9.

[0017] A bidirectional converter top circuit control method based on any one of claims 1-6, comprising:

[0018] S1. When the input drive signal B is high, MOSFETs Q8 and Q10 are turned on; when the input drive signal B is low, MOSFETs Q8 and Q10 are turned off.

[0019] S2. When the input drive signal B is low, increasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be low, and MOSFETs Q8 and Q10 to be cut off; decreasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be high, and MOSFETs Q8 and Q10 to be turned on.

[0020] S3. The overcurrent detection circuit detects the current of the main power circuit. When the current of the main power circuit exceeds the preset value, transistor Q9 is turned on and MOSFET Q8 is turned off. When the current of the main power circuit does not exceed the preset value, transistor Q9 is turned off and MOSFET Q8 is turned on.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The top-side circuit control method of this invention is simple and has a fast response speed. Whether operating in the forward or reverse direction, MOSFETs Q8 and Q10 are turned on simultaneously, meaning they are turned on immediately upon power-up without delay. It has a real-time overcurrent monitoring function, which can monitor the current changes of the main power circuit in real time. When the change value exceeds the parameter setting range, the overcurrent protection is activated until the current returns to the set range, at which point the overcurrent protection is deactivated and normal operation is automatically restored. By adopting the current source and Darlington transistor principle, the power loss of the control circuit is reduced, the anti-interference capability is greatly enhanced, the drive current is reduced, and the performance of the bidirectional frequency converter is improved. Attached Figure Description

[0023] Figure 1 This is the schematic diagram of the main power circuit of the present invention.

[0024] Figure 2 This is a schematic diagram of the control circuit for turning on the MOSFET Q8 in this invention.

[0025] Figure 3 This is a schematic diagram of the control circuit for turning on the MOSFET Q10 in this invention.

[0026] Figure 4 This is a schematic diagram of the steps of the top circuit control method of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0028] The specific implementation process of this invention is as follows:

[0029] This invention employs the principles of current source and Darlington transistor, and solves the problems of conduction delay, large drive current, insufficient anti-interference capability, and lack of protection against main power overcurrent with delay in the top circuit control circuit of bidirectional converters through dual control of level and current.

[0030] The bidirectional circuit topology receives both forward and reverse power-on signals. When it receives a forward power-on signal, it operates in the forward direction, with Q8 as the input MOSFET and Q10 as the output MOSFET. When it receives a reverse power-on signal, it operates in the reverse direction, with Q10 as the input MOSFET and Q8 as the output MOSFET. The forward and reverse operating principles are the same, as follows: Figures 1 to 3 As shown, the specific working principle is as follows:

[0031] When the drive signal B is high or floating, MOSFETs Q1, Q2, and Q7 are cut off, while MOSFETs Q3, Q4, Q5, and Q6 are turned on, and the switching circuit does not work. The gate of MOSFET Q8 is high, and MOSFET Q8 is turned on.

[0032] When the drive signal B is high or floating, MOSFETs Q20, Q21, and Q26 are cut off, while MOSFETs Q22, Q23, Q24, and Q25 are turned on, and the switching circuit does not work. MOSFET Q10 is also turned on when its gate is high.

[0033] When the input current is abnormal and the voltage drop across the current sampling resistor R9 exceeds the parameter setting value, transistor Q9 conducts, and the gate and source potentials of MOSFET Q8 become equal. MOSFET Q8 then turns off, limiting the current of the main power circuit and protecting the downstream circuitry. When the voltage drop across the current sampling resistor R9 exceeds the parameter setting value, the main power circuit returns to normal, transistor Q9 turns off, and MOSFET Q8 conducts, releasing the current limit.

[0034] When the drive signal B is low, MOSFETs Q1, Q2, and Q7 are turned on, as are MOSFETs Q3, Q4, Q5, and Q6, and the switching circuit operates. MOSFET Q8's gate is low, and Q8 is turned off. When the resistance of the balancing resistor R6 increases, MOSFET Q2 turns on, the current flowing through the pull-down resistor R19 branch of MOSFET Q7 increases, the base voltage of MOSFET Q7 rises, MOSFET Q7 turns on, the gate of MOSFET Q8 is low, and MOSFET Q8 is turned off. When the resistance of the balancing resistor R6 decreases, MOSFETs Q2 and Q7 are turned off, the current flowing through the resistor R23 branch increases, the gate of MOSFET Q8 is high, and MOSFET Q8 turns on.

[0035] When the drive signal B is low, MOSFETs Q20, Q21, and Q26 are turned on, as are transistors Q22, Q23, Q24, and Q25, and the switching circuit operates. MOSFET Q10's gate is low, and Q10 is turned off. When the resistance of the balancing resistor R6 increases, transistor Q21 turns on, the current flowing through the pull-down resistor R46 branch of transistor Q26 increases, the base voltage of transistor Q26 rises, and Q26 turns on. MOSFET Q10's gate is low, and Q10 is turned off. When the resistance of the balancing resistor R6 decreases, transistors Q21 and Q26 are turned off, the current flowing through the R50 branch increases, the gate of MOSFET Q10 is high, and Q10 turns on.

[0036] When the input current is abnormal, and the voltage drop across the current sampling resistor R11 exceeds the parameter setting value, transistor Q27 conducts, and the gate and source potentials of MOSFET Q10 become equal. MOSFET Q10 is then cut off, limiting the current of the main power circuit and protecting the subsequent circuitry. Q10 is an output-side MOSFET; when the current is abnormal, it will not trigger transistor Q27 to turn on falsely, causing MOSFET Q10 to be falsely cut off, resulting in damage to MOSFET Q10. When the voltage drop across the current sampling resistor R11 exceeds the parameter setting value, the main power circuit returns to normal, transistor Q27 turns off, MOSFET Q10 conducts, and the limitation is lifted.

[0037] This invention employs dual control of level and current. A balancing resistor R6 is connected in series between the switching circuit and the power supply. When the drive signal B is low, adjusting the parameters of the balancing resistor R6 regulates the base current of transistors Q7 and Q26, thereby controlling the on / off state of MOSFETs Q8 and Q10 in the main power circuit. When the drive signal B is high, the balancing resistor R6 can be set to a parameter that does not affect the circuit. Specifically, the balancing resistor R6 can be a surface-mount resistor or a switch configured according to actual needs, supporting continuous adjustment, range selection adjustment, manual adjustment, or software control. In a pure hardware implementation, when the drive signal B is directly set low via hardware, the top circuit is controlled by the balancing resistor R6, and the resistance value of R6 is selected based on the circuit parameters. During the debugging phase, a continuously adjustable switch can be used to facilitate finding the optimal parameters. In practical applications, the balancing resistor R6 can be used as an emergency stop switch. For example, when the drive signal B is controlled externally and the external control is interfered with during operation, causing it to be unable to stop working, the balancing resistor R6 can be used as an emergency switch to quickly cut off the circuit.

[0038] When multiple high-power power supplies are connected in parallel, and communication interference is severe, making software control impossible, the external drive signal B can be set to a low level via hardware and controlled using a balancing resistor R6. This effectively solves the problem of having to disconnect the power supply externally under severe interference. Furthermore, when the software is interfered with, the internal power supply can be safely disconnected via hardware, ensuring uninterrupted operation of the downstream equipment while it is powered on. The use of a Darlington transistor ensures circuit stability and reduces jitter when using the R6 switch. This invention can be applied to high-power bidirectional converters, reducing power loss in the control circuit, significantly enhancing anti-interference capabilities, reducing drive current, and improving the performance of the bidirectional frequency converter.

[0039] Whether operating in the forward or reverse direction, MOSFETs Q8 and Q10 conduct simultaneously, meaning they turn on immediately upon power-up, resulting in a fast response with no delay, effectively solving the conduction delay problem in existing control circuits.

[0040] The overcurrent detection circuit monitors the current changes of the main power circuit in real time. When the change value exceeds the parameter setting range, the overcurrent protection is activated until the current returns to the setting range. Then the overcurrent protection is deactivated and normal operation is automatically restored.

[0041] In an embodiment of the present invention, Darlington transistor 1 is composed of transistors Q3 and Q4, Darlington transistor 2 is composed of transistors Q5 and Q6, Darlington transistor 3 is composed of transistors Q22 and Q23, and Darlington transistor 4 is composed of transistors Q24 and Q25. Darlington transistors 1 and 2 are located in the switching circuit that drives MOSFET Q8 to conduct, and Darlington transistors 3 and 4 are located in the switching circuit that drives MOSFET Q10 to conduct, so that the control circuit can achieve lower power consumption, stronger anti-interference capability, and smaller drive current.

[0042] In embodiments of the present invention, the control circuit includes diodes D1, D2, D10, and D11 to prevent large currents from flowing back into the control circuit from the main power circuit, thus preventing damage to the Darlington transistor. Diodes D3, D4, D12, and D13 are included to prevent high-voltage backflow and protect the preceding drive circuit. The overcurrent detection circuit, by using resistor R12, prevents transistor Q9 from mis-conducting, ensuring the stability and reliability of the control circuit.

[0043] like Figure 4 As shown, the present invention also includes a method for controlling the top circuit of a bidirectional converter, comprising:

[0044] S1. When the input drive signal B is high, MOSFETs Q8 and Q10 are turned on; when the input drive signal B is low, MOSFETs Q8 and Q10 are turned off.

[0045] S2. When the input drive signal B is low, increasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be low, and MOSFETs Q8 and Q10 to be cut off; decreasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be high, and MOSFETs Q8 and Q10 to be turned on.

[0046] S3. The overcurrent detection circuit detects the current of the main power circuit. When the current of the main power circuit exceeds the preset value, transistor Q9 is turned on and MOSFET Q8 is turned off. When the current of the main power circuit does not exceed the preset value, transistor Q9 is turned off and MOSFET Q8 is turned on.

[0047] The control method of this invention is simple, has a fast response speed, no turn-on delay, and has a real-time overcurrent monitoring function to achieve overcurrent protection. It reduces the power loss of the control circuit, greatly enhances the anti-interference capability, and is applicable to all bidirectional converters.

[0048] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A bidirectional converter top-side circuit, characterized in that, include: The main power circuit includes MOSFET Q8, MOSFET Q10 and a bidirectional circuit topology, wherein MOSFET Q8 and MOSFET Q10 are respectively connected to the two ends of the bidirectional circuit topology; The control circuit includes a switching circuit and an overcurrent detection circuit. The switching circuit includes a balancing resistor. When the input drive signal is high, the switching circuit controls the MOSFETs Q8 and Q10 of the main power circuit to turn on; When the input drive signal is low, the switching on and off of MOSFETs Q8 and Q10 in the main power circuit is controlled by adjusting the resistance of the balancing resistor. The overcurrent detection circuit is used to detect the current of the main power circuit. When the current of the main power circuit exceeds the preset value, the switching circuit controls the MOSFETs Q8 and Q10 in the main power circuit to turn off. When the input drive signal is low, increasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be low, and MOSFETs Q8 and Q10 to be cut off; decreasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be high, and MOSFETs Q8 and Q10 to be turned on.

2. The bidirectional converter top-side circuit according to claim 1, characterized in that, For MOSFET Q8, the switching circuit also includes Darlington transistors, MOSFET Q1, transistor Q2, and transistor Q7. The Darlington transistors include Darlington transistor 1 and Darlington transistor 2. Darlington transistor 1 includes transistors Q3 and Q4, and Darlington transistor 2 includes transistors Q5 and Q6. The source of MOSFET Q1 is connected to the power supply, and the gate of MOSFET Q1 is connected to one end of resistor R1 and the drive signal. The other end of resistor R1 is connected to the power supply. The drain of MOSFET Q1... The base of transistor Q2 is connected to one end of resistor R5, the collector of transistor Q2 is connected to one end of resistor R18, the emitter of transistor Q2 is connected to the other end of resistor R5 and one end of balancing resistor R6, the collector of transistor Q7 is connected to one end of resistor R21, and the other end of resistor R21 is connected to the power supply; the base of transistor Q7 is connected to the other end of resistor R18 and one end of resistor R19, respectively. The emitter of transistor Q7 is connected to one end of resistor R20; the other ends of balancing resistor R6, resistor R15, the collectors of transistors Q6 and Q5 are connected, and then connected to the power supply through resistor R14; the emitter of transistor Q6 is connected to the base of transistor Q5; the emitter of transistor Q5 is connected to one end of resistor R23, the other end of resistor R23 is connected to the other ends of resistors 19 and 20; the base of transistor Q6 is connected to one end of resistor R16. The other end of resistor R16 is connected to one end of resistor R13 and one end of resistor R8. The other end of resistor R13 is connected to the collector of transistor Q3 and the collector of transistor Q4, and is connected to the power supply through resistor R7. The base of transistor Q3 is connected to the other end of resistor R8. The emitter of transistor Q3 is connected to the base of transistor Q4. The emitter of transistor Q4 is connected to one end of resistor R17. The other end of resistor R17 is connected to the input of the top circuit and the drain of MOSFET Q8. The overcurrent detection circuit includes a current sampling resistor R9 and a transistor Q9. The current sampling resistor R9 is located on the main power circuit. One end of the resistor R9 is connected to the source of the MOSFET Q8, the base of the transistor Q9, and one end of the resistor R10. The other end of the resistor R9 is connected to the bidirectional circuit topology, the emitter of the transistor Q9, and the other end of the resistor R20. The collector of the transistor Q9 is connected to the gate of the MOSFET Q8, the other end of the resistor R10, and one end of the resistor R22. The other end of the resistor R22 is connected to the collector of the transistor Q7. For MOSFET 10, its switching circuit and overcurrent detection circuit have the same topology as MOSFET 8.

3. The bidirectional converter top-side circuit according to claim 2, characterized in that, The bidirectional circuit topology is used to receive a positive power-on signal and a reverse power-on signal. When the bidirectional circuit topology receives a positive power-on signal, it operates in the forward direction, with Q8 being the input MOSFET and Q10 being the output MOSFET. When the bidirectional circuit topology receives a reverse power-on signal, it operates in the reverse direction, with Q10 being the input MOSFET and Q8 being the output MOSFET.

4. The bidirectional converter top-side circuit according to claim 2, characterized in that, The top-side circuit also includes diodes D3 and D4. The anode of diode D3 is connected to the collector of transistor Q2, the cathode of diode D3 is connected to one end of resistor R18, the anode of diode D4 is connected to the power supply, and the cathode of diode D4 is connected to the other end of resistor R21.

5. The bidirectional converter top-side circuit according to claim 2, characterized in that, The top-side circuit also includes diodes D1 and D2. The anode of diode D1 is connected to the other end of resistor R17, and the cathode of diode D1 is connected to the drain of MOSFET Q8.

6. The bidirectional converter top-side circuit according to claim 2, characterized in that, The overcurrent detection circuit also includes a resistor R12, one end of which is connected to the source of the MOSFET Q8, and the other end of which is connected to the base of the transistor Q9.

7. A method for controlling the top circuit of a bidirectional converter based on any one of claims 2-6, characterized in that, include: S1. When the input drive signal B is high, MOSFETs Q8 and Q10 are turned on; when the input drive signal B is low, MOSFETs Q8 and Q10 are turned off. S2. When the input drive signal B is low, increasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be low, and MOSFETs Q8 and Q10 to be cut off; decreasing the value of the balancing resistor will cause the gates of MOSFETs Q8 and Q10 to be high, and MOSFETs Q8 and Q10 to be turned on. S3. The overcurrent detection circuit detects the current of the main power circuit. When the current of the main power circuit exceeds the preset value, transistor Q9 is turned on and MOSFET Q8 is turned off. When the current of the main power circuit does not exceed the preset value, transistor Q9 is turned off and MOSFET Q8 is turned on.

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