A multifunctional isolated dc / dc converter and a control method thereof

Abstract

The application relates to a multifunctional isolated DC / DC converter and a control method thereof, which comprises a main circuit, a control system and a control power supply; the main circuit comprises a first capacitor, a second capacitor, a third capacitor, a high-frequency transformer and a first switch assembly S1-S8; the first capacitor is a low-voltage side of the DC / DC converter, and the third capacitor is a high-voltage side of the DC / DC converter; the control system comprises a first control module, a second control module, a third control module and a fourth control module; the fourth control module is connected with the first control module, the second control module and the third control module through a selection switch Switch; the fourth control module outputs corresponding duty cycles to control the work of the first switch assembly S1-S8; and the control power supply comprises a first DC / DC module, a second DC / DC module, a first diode and a second diode. Through the application, the technical problem that the single-machine cost is high and the adaptability is poor caused by the corresponding isolated DC / DC converter customized and developed for specific application scenarios can be solved.

Description

Technical Field

[0001] This invention relates to the field of DC / DC converter technology, and more specifically to a multifunctional isolated DC / DC converter and its control method. Background Technology

[0002] With the gradual promotion of DC power supplies, DC loads, and DC power supply systems, isolated DC / DC converters have been widely used. The energy exchange between different voltage levels in DC power supply systems is achieved through isolated DC / DC converters; the charging module in new energy vehicle charging piles is implemented using isolated DC / DC converters; and the external output interface of low-voltage energy storage systems is implemented using isolated DC / DC converters. It can be said that wherever there is a DC application, there is a use for isolated DC / DC converters. Due to the widespread use of isolated DC / DC converters in DC applications, the requirements and functions of isolated DC / DC converters vary across different application scenarios. Currently, the main approach in DC applications is to develop corresponding isolated DC / DC converters to meet different application needs. This has resulted in a large variety of isolated DC / DC converters with poor versatility, hindering their rapid application and promotion.

[0003] In the process of realizing this invention, the inventors discovered that the prior art has at least the following technical problems:

[0004] Regarding isolated DC / DC converters that meet specific application scenarios, these converters can meet the power exchange between different voltage levels in DC power supply systems. However, the customized development of corresponding isolated DC / DC converters for specific application scenarios inevitably leads to disadvantages such as high unit cost and poor adaptability. In particular, the isolated DC / DC converters required by various application scenarios in DC systems are not interchangeable, which to some extent affects the progress and standardization of DC systems. Summary of the Invention

[0005] The purpose of this invention is to propose a multifunctional isolated DC / DC converter and its control method, so as to solve the technical problems of high unit cost and poor adaptability caused by traditional isolated DC / DC converters that are customized for specific application scenarios.

[0006] To achieve the above objectives, this invention proposes a multifunctional isolated DC / DC converter, including a main circuit, a control system, and a control power supply;

[0007] The main circuit includes a first capacitor, a second capacitor, a third capacitor, a high-frequency transformer, a first switching assembly S1, a second switching assembly S2, a third switching assembly S3, a fourth switching assembly S4, a fifth switching assembly S5, a sixth switching assembly S6, a seventh switching assembly S7, and an eighth switching assembly S8; the first capacitor is the low-voltage side of the DC / DC transformer, and the third capacitor is the high-voltage side of the DC / DC transformer.

[0008] Wherein, the first end of the first switch assembly S1 is simultaneously connected to the first end of the first capacitor and the first end of the third switch assembly S3; the second end of the first switch assembly S1 is simultaneously connected to the first end of the second switch assembly S2 and the first end of the second capacitor; the second end of the second switch assembly S2 is simultaneously connected to the second end of the first capacitor and the second end of the fourth switch assembly S4; the second end of the third switch assembly S3 is connected to the first end of the fourth switch assembly S4; the first end of the fifth switch assembly S5 is simultaneously connected to the first end of the third capacitor and the first end of the seventh switch assembly S7; the second end of the fifth switch assembly S5 is connected to the first end of the sixth switch assembly S6; the second end of the sixth switch assembly S6 is simultaneously connected to the second end of the eighth switch assembly S8 and the second end of the third capacitor; the second end of the seventh switch assembly S7 is connected to the first end of the eighth switch assembly S8; the first end of the primary winding of the high-frequency transformer is connected to the second end of the second capacitor; the second end of the primary winding of the high-frequency transformer is connected to the second end of the third switch assembly S3; the first end of the secondary winding of the high-frequency transformer is connected to the second end of the fifth switch assembly S5; and the second end of the secondary winding of the high-frequency transformer is connected to the second end of the seventh switch assembly S7.

[0009] The control system includes a first control module, a second control module, a third control module, and a fourth control module. The fourth control module is connected to the first, second, and third control modules via a selector switch. The first, second, and third control modules each have different control modes. The selector switch is used to switch the switch state so that the first control module is connected to the fourth control module to achieve a first control mode, the second control module is connected to the fourth control module to achieve a second control mode, or the third control module is connected to the fourth control module to achieve a third control mode. The fourth control module outputs a corresponding duty cycle to control the operation of the first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8.

[0010] The control power supply includes a first DC / DC module, a second DC / DC module, a first diode, and a second diode. The input terminal of the first DC / DC module is used to input the low-voltage side voltage V. L The output terminal of the first DC / DC module is connected to the anode of the first diode, the cathode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the output terminal of the second DC / DC module, and the input terminal of the second DC / DC module is used to input the low-voltage side voltage V. H The cathodes of the first diode and the second diode are connected to the control system.

[0011] Preferably, the first control mode is a dual-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop.

[0012] Preferably, the second control mode is a dual-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop.

[0013] Preferably, the third control mode is a low-voltage side current closed-loop control mode.

[0014] Preferably, the first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8 have the same structure, each consisting of a transistor connected in parallel with a diode.

[0015] This invention also proposes a control method for a multifunctional isolated DC / DC converter, comprising the following steps:

[0016] When the selection switch is in the first state, the isolated DC / DC converter operates at a stable high-voltage side voltage V. H In this operating mode, the low-voltage side terminal V of the isolated DC / DC converter... L Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of high-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle, and controls the operation of switching devices S1 to S8 in the main circuit.

[0017] Preferably, the method further includes the following steps:

[0018] When the selection switch is in the second state, the isolated DC / DC converter operates to stabilize the low-voltage side voltage V. L In this operating mode, the high-voltage side terminal V of the isolated DC / DC converter...H Upon power-up, the control power supply is supplied by V H After passing through the second DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of low-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle, and controls the operation of switching devices S1 to S8 in the main circuit.

[0019] Preferably, the method further includes the following steps:

[0020] When the selector switch is in the third state, the isolated DC / DC converter operates in a mode that controls the power flow on the high and low voltage sides; in this operating mode, the low voltage side terminal V of the isolated DC / DC converter... L Power on, high voltage side terminal V H Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V and V are generated. H After passing through the second DC / DC module, 24V is generated, and the two 24V voltages power the control system. The control system adopts a low-voltage side current closed-loop control mode, calculates the duty cycle, and controls the operation of switching devices S1 to S8 in the main circuit.

[0021] The present invention has at least the following beneficial effects:

[0022] This invention utilizes a single isolated DC / DC converter to achieve three functions: stabilizing the high-voltage side bus voltage, stabilizing the low-voltage side bus voltage, and controlling power flow. It exhibits strong adaptability to different application scenarios of isolated DC / DC converters, making it easier to standardize and universalize isolated DC / DC converters in DC power supply systems.

[0023] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a circuit diagram of a multifunctional isolated DC / DC converter according to an embodiment of the present invention.

[0026] Figure 2 This is a circuit diagram of the control system in an embodiment of the present invention. Detailed Implementation

[0027] The various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, numerous specific details are set forth in the following detailed embodiments to better illustrate the invention. Those skilled in the art will understand that the invention can be practiced without certain specific details. In some instances, means well known to those skilled in the art have not been described in detail in order to highlight the spirit of the invention.

[0028] See Figure 1-2 One embodiment of the present invention provides a multifunctional isolated DC / DC converter, including a main circuit, a control system, and a control power supply;

[0029] The main circuit includes a first capacitor, a second capacitor, a third capacitor, a high-frequency transformer, a first switching assembly S1, a second switching assembly S2, a third switching assembly S3, a fourth switching assembly S4, a fifth switching assembly S5, a sixth switching assembly S6, a seventh switching assembly S7, and an eighth switching assembly S8; the first capacitor is the low-voltage side of the DC / DC transformer, and the third capacitor is the high-voltage side of the DC / DC transformer. Figure 1 In the diagram, N1 represents the number of turns in the secondary winding of the high-frequency transformer, and N2 represents the number of turns in the primary winding of the high-frequency transformer.

[0030] Wherein, the first end of the first switch assembly S1 is simultaneously connected to the first end of the first capacitor and the first end of the third switch assembly S3; the second end of the first switch assembly S1 is simultaneously connected to the first end of the second switch assembly S2 and the first end of the second capacitor; the second end of the second switch assembly S2 is simultaneously connected to the second end of the first capacitor and the second end of the fourth switch assembly S4; the second end of the third switch assembly S3 is connected to the first end of the fourth switch assembly S4; the first end of the fifth switch assembly S5 is simultaneously connected to the first end of the third capacitor and the first end of the seventh switch assembly S7; the second end of the fifth switch assembly S5 is connected to the first end of the sixth switch assembly S6; the second end of the sixth switch assembly S6 is simultaneously connected to the second end of the eighth switch assembly S8 and the second end of the third capacitor; the second end of the seventh switch assembly S7 is connected to the first end of the eighth switch assembly S8; the first end of the primary winding of the high-frequency transformer is connected to the second end of the second capacitor; the second end of the primary winding of the high-frequency transformer is connected to the second end of the third switch assembly S3; the first end of the secondary winding of the high-frequency transformer is connected to the second end of the fifth switch assembly S5; and the second end of the secondary winding of the high-frequency transformer is connected to the second end of the seventh switch assembly S7.

[0031] The control system includes a first control module, a second control module, a third control module, and a fourth control module. The fourth control module is connected to the first, second, and third control modules via a selector switch. The first, second, and third control modules each have different control modes. The selector switch is used to switch the switch state so that the first control module is connected to the fourth control module to achieve a first control mode, the second control module is connected to the fourth control module to achieve a second control mode, or the third control module is connected to the fourth control module to achieve a third control mode. The fourth control module outputs a corresponding duty cycle to control the operation of the first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8.

[0032] The control power supply includes a first DC / DC module, a second DC / DC module, a first diode, and a second diode. The input terminal of the first DC / DC module is used to input the low-voltage side voltage V. L The output terminal of the first DC / DC module is connected to the anode of the first diode, the cathode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the output terminal of the second DC / DC module, and the input terminal of the second DC / DC module is used to input the low-voltage side voltage V. H The cathodes of the first diode and the second diode are connected to the control system.

[0033] Furthermore, the first control mode is a dual-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop.

[0034] Furthermore, the second control mode is a dual-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop.

[0035] Furthermore, the third control mode is a low-voltage side current closed-loop control mode.

[0036] Furthermore, the first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8 have the same structure, each consisting of a transistor connected in parallel with a diode.

[0037] Specifically, the control power supply for the multi-functional DC / DC converter adopts a dual-side power supply configuration, as shown in the control power supply section of the block diagram. The control power supply is supplied from the high-voltage side terminal V. Hand low voltage side terminal V L V H After passing through an isolated DC / DC power module, it generates 24V. L After passing through the isolated DC / DC power module, 24V is generated. The two 24V power supplies are interconnected through diodes to power the control system. Dual-side power supply ensures that the control power supply section of the isolated DC / DC converter can work and supply power to the control system as long as one side is powered on. This is the premise for the isolated DC / DC converter to realize multiple functions.

[0038] It should be noted that, in this embodiment of the invention, the isolated DC / DC converter control power supply has the ability to draw power from both sides, and the voltages on both sides of the isolated DC / DC converter (high voltage side voltage V) are... H and low-voltage side voltage V L Both supply voltages are generated by an isolated DC / DC module and then connected in parallel with diodes to power the control system. This dual-side power supply ensures a 24V control power supply and a high-voltage side voltage of V. H and low-voltage side voltage V L Mutual isolation; the isolated DC / DC converter control system has a built-in stable high-voltage side voltage V. H Stabilize the low-voltage side voltage V L It controls power flow in three modes: high and low voltage sides, and allows setting and switching between different modes via a mode selection switch.

[0039] Based on the multifunctional isolated DC / DC converter of the above embodiments, another embodiment of the present invention proposes a control method for the multifunctional isolated DC / DC converter, including the following steps:

[0040] When the selection switch is in the first state, i.e. Figure 1 When Switch=1, the isolated DC / DC converter operates at a stable high-voltage side voltage V. H In this operating mode, the low-voltage side terminal V of the isolated DC / DC converter... L Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of high-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle and controls the operation of switching devices S1 to S8 in the main circuit.

[0041] Specifically, the principle of the dual-closed-loop control mode, consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop, has been established. Figure 1 As shown in the figure, where V H-ref For the high-voltage side voltage command to be stabilized and controlled as planned, I L-refThe output of the high-voltage side voltage closed loop is the input command for the low-voltage side current closed loop.

[0042] When the selection switch is in the second state, i.e. Figure 1 When Switch=2, the isolated DC / DC converter operates at a stable low-side voltage V. L In this operating mode, the high-voltage side terminal V of the isolated DC / DC converter... H Upon power-up, the control power supply is supplied by V H After passing through the second DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of low-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle and controls the operation of switching devices S1 to S8 in the main circuit.

[0043] Specifically, the principle of the dual-loop control mode, consisting of a low-voltage side voltage closed loop and a low-voltage side current closed loop, has been established. Figure 1 As shown in the figure, where V L-ref For the planned stable control of the low-voltage side voltage command, I L-ref It is the output of the low-voltage side voltage closed loop (i.e., the input command of the low-voltage side current closed loop).

[0044] When the selection switch is in the third state, i.e. Figure 1 When Switch=3, the isolated DC / DC converter operates in a mode that controls the power flow on both the high and low voltage sides; in this operating mode, the low-voltage side terminal V of the isolated DC / DC converter... L Power on, high voltage side terminal V H Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V and V are generated. H After passing through the second DC / DC module, 24V is generated, and the two 24V voltages power the control system. The control system adopts a low-voltage side current closed-loop control mode, calculates the duty cycle, and controls the operation of switching devices S1 to S8 in the main circuit.

[0045] Specifically, the principle of the low-voltage side current closed-loop control mode has been established. Figure 1 As shown in the figure, P ref The high and low voltage side power flow commands are to be controlled according to the plan, and the input command I for the low voltage side current closed loop is calculated. L-ref .

[0046] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A multi-functional isolated DC / DC converter, characterized in that, Includes the main circuit, control system, and control power supply; The main circuit includes a first capacitor, a second capacitor, a third capacitor, a high-frequency transformer, a first switching assembly S1, a second switching assembly S2, a third switching assembly S3, a fourth switching assembly S4, a fifth switching assembly S5, a sixth switching assembly S6, a seventh switching assembly S7, and an eighth switching assembly S8; the first capacitor is the low-voltage side of the DC / DC transformer, and the third capacitor is the high-voltage side of the DC / DC transformer. Wherein, the first end of the first switch assembly S1 is simultaneously connected to the first end of the first capacitor and the first end of the third switch assembly S3; the second end of the first switch assembly S1 is simultaneously connected to the first end of the second switch assembly S2 and the first end of the second capacitor; the second end of the second switch assembly S2 is simultaneously connected to the second end of the first capacitor and the second end of the fourth switch assembly S4; the second end of the third switch assembly S3 is connected to the first end of the fourth switch assembly S4; the first end of the fifth switch assembly S5 is simultaneously connected to the first end of the third capacitor and the first end of the seventh switch assembly S7; the second end of the fifth switch assembly S5 is connected to the first end of the sixth switch assembly S6; the second end of the sixth switch assembly S6 is simultaneously connected to the second end of the eighth switch assembly S8 and the second end of the third capacitor; the second end of the seventh switch assembly S7 is connected to the first end of the eighth switch assembly S8; the first end of the primary winding of the high-frequency transformer is connected to the second end of the second capacitor; the second end of the primary winding of the high-frequency transformer is connected to the second end of the third switch assembly S3; the first end of the secondary winding of the high-frequency transformer is connected to the second end of the fifth switch assembly S5; and the second end of the secondary winding of the high-frequency transformer is connected to the second end of the seventh switch assembly S7. The control system includes a first control module, a second control module, a third control module, and a fourth control module. The fourth control module is connected to the first, second, and third control modules via a selector switch. The first, second, and third control modules each have different control modes. The selector switch is used to switch the switch state so that the first control module is connected to the fourth control module to achieve a first control mode, the second control module is connected to the fourth control module to achieve a second control mode, or the third control module is connected to the fourth control module to achieve a third control mode. The fourth control module outputs a corresponding duty cycle to control the operation of the first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8. The control power supply includes a first DC / DC module, a second DC / DC module, a first diode, and a second diode. The input terminal of the first DC / DC module is used to input the low-voltage side voltage V. L The output terminal of the first DC / DC module is connected to the anode of the first diode, the cathode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the output terminal of the second DC / DC module, and the input terminal of the second DC / DC module is used to input the high-voltage side voltage V. H The cathodes of the first diode and the second diode are connected to the control system. The first control mode is a dual closed-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop. In this mode, the selector switch is in the first state, and the isolated DC / DC converter operates at a stable high-voltage side voltage V. H In this mode, the low-voltage side terminal V of the isolated DC / DC converter L Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V is generated and used to power the control system; The second control mode is a dual-loop control mode consisting of a high-voltage side voltage closed loop and a low-voltage side current closed loop. In this mode, the selector switch is in the second state, and the isolated DC / DC converter operates to stabilize the low-voltage side voltage V. L In this mode, the high-voltage side terminal V of the isolated DC / DC converter H Upon power-up, the control power supply is supplied by V H After passing through the second DC / DC module, 24V is generated and used to power the control system; The third control mode is a low-voltage side current closed-loop control mode. In this mode, the selector switch is in the third state, and the isolated DC / DC converter operates in a mode that controls the power flow on both the high and low voltage sides. The low-voltage side terminal V of the isolated DC / DC converter... L Power on, high voltage side terminal V H Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V and V are generated. H After passing through the second DC / DC module, 24V is generated, and the two 24V voltages power the control system.

2. The multifunctional isolated DC / DC converter according to claim 1, characterized in that, The first switch assembly S1, the second switch assembly S2, the third switch assembly S3, the fourth switch assembly S4, the fifth switch assembly S5, the sixth switch assembly S6, the seventh switch assembly S7, and the eighth switch assembly S8 have the same structure, each consisting of a transistor connected in parallel with a diode.

3. The control method for the multifunctional isolated DC / DC converter as described in any one of claims 1-2, characterized in that, Includes the following steps: When the selection switch is in the first state, the isolated DC / DC converter operates at a stable high-voltage side voltage V. H In this mode, the low-voltage side terminal V of the isolated DC / DC converter... L Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of high-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle, and controls the operation of switching components S1~S8 in the main circuit.

4. The control method for the multifunctional isolated DC / DC converter as described in claim 3, characterized in that, Includes the following steps: When the selector switch is in the second state, the isolated DC / DC converter operates at a stable low-voltage side voltage V. L In this mode, the high-voltage side terminal V of the isolated DC / DC converter... H Upon power-up, the control power supply is supplied by V H After passing through the second DC / DC module, 24V is generated and used to power the control system. The control system adopts a dual closed-loop control mode of low-voltage side voltage closed loop + low-voltage side current closed loop, calculates the duty cycle, and controls the operation of switching components S1~S8 in the main circuit.

5. The control method for the multifunctional isolated DC / DC converter as described in claim 4, characterized in that, Includes the following steps: When the selector switch is in the third state, the isolated DC / DC converter operates in a mode that controls the power flow on the high and low voltage sides; in this mode, the low voltage side terminal V of the isolated DC / DC converter... L Power on, high voltage side terminal V H Upon power-up, the control power supply is supplied by V L After passing through the first DC / DC module, 24V and V are generated. H After passing through the second DC / DC module, 24V is generated, and the two 24V voltages power the control system. The control system adopts a low-voltage side current closed-loop control mode, calculates the duty cycle, and controls the operation of the switching components S1~S8 in the main circuit.

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