Bidirectional dc-dc circuit and control method thereof

Abstract

The application provides a bidirectional DCDC circuit and a control method thereof. In the bidirectional DCDC circuit, a first power module, a second power module, a main circuit, a first sampling circuit, a second sampling circuit, a first driving circuit, a second driving circuit and a controller are correspondingly connected, so that the topology structure and the circuit loop can be simplified, and the device cost is reduced. When the power is transmitted between the first power module and the second power module, the controller determines the target ratio combination of the main circuit according to the first regulating signal and the second regulating signal, and then controls the main circuit to switch to the target ratio combination based on the switching control signal through the first driving circuit and the second driving circuit, so that the input and output voltage and the input and output current of the main circuit are controlled according to the target ratio combination, the unified driving signal is used for driving, and the stability of the output voltage and current is ensured.

Description

Bidirectional DC-DC circuit and its control method Technical Field

[0001] This invention relates to the field of battery energy management and energy storage technology, and in particular to a bidirectional DC-DC circuit and its control method. Background Technology

[0002] Currently, in the fields of battery energy management and energy storage, isolated bidirectional DC-DC converters are designed to achieve battery charging and discharging. This means the converter can both charge and discharge the battery while ensuring isolation between the battery and the external power source for safety. However, the number of batteries connected in series varies in different scenarios, and the external power supply fluctuates significantly. Therefore, this bidirectional DC-DC converter needs to adapt to a wide input / output range.

[0003] In related technologies, bidirectional DC-DC converters that adapt to a wide input and output range are usually achieved by cascading multiple converters or by using a wide-range PWM pulse width modulation. As shown in Figure 1, a two-stage converter architecture is adopted. The first-stage converter 1 uses a non-isolated topology to achieve a wide-range voltage regulation effect, while the second-stage converter 2 uses an isolated topology to complete the electrical isolation between the battery side and the outside.

[0004] However, the topology in Figure 1 is complex, requiring numerous switching and filtering devices, resulting in a large device size and high cost. Furthermore, the topology in Figure 1 requires many drive signals, leading to complex control algorithms and loops, placing high demands on the system control section. Moreover, electromagnetic compatibility design is complex and difficult to rectify. Additionally, the large duty cycle variation of PWM results in high current and voltage stress on the switching devices, making selection difficult and costly. Furthermore, the PWM duty cycle needs to exceed 50%, requiring ramp compensation in peak current control mode, increasing circuit complexity and degrading the single-cycle current limiting effect.

[0005] Therefore, how to simplify the topology and circuit loop, reduce device costs, use a unified driving signal for driving, and ensure the stability of output voltage and current has become a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, embodiments of the present invention provide a bidirectional DC-DC circuit and its control method to simplify the topology and circuit loop, reduce device costs, and use a unified driving signal to drive the circuit, thereby ensuring the stability of the output voltage and current.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of this invention discloses a bidirectional DC-DC circuit, comprising: a first power module, a second power module, a main circuit, a first sampling circuit, a second sampling circuit, a first driving circuit, a second driving circuit, and a controller;

[0009] The two power supply terminals of the main circuit are respectively connected to the positive and negative terminals of the first power supply module and the positive and negative terminals of the second power supply module, and the two drive control terminals of the main circuit are respectively connected to the controller through the first drive circuit and the second drive circuit.

[0010] The sampling terminal of the first sampling circuit is connected to the first power module, and the output terminal of the first sampling circuit is connected to the controller.

[0011] The sampling terminal of the second sampling circuit is connected to the second power module, and the output terminal of the second sampling circuit is connected to the controller;

[0012] The controller is used to obtain a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit when power is transmitted between the first power module and the second power module. Based on the first conditioning signal and the second conditioning signal, the controller determines the target turns ratio combination of the main circuit. Through the first driving circuit and the second driving circuit, the controller controls the main circuit to switch to the target turns ratio combination based on the output switching control signal. Based on the target turns ratio combination, the controller controls the input and output voltage and input and output current of the main circuit through the first driving circuit and the second driving circuit based on the output driving control signal. The first conditioning signal is obtained by the first sampling circuit sampling and conditioning the input and output voltage and current of the first power module, and the second conditioning signal is obtained by the second sampling circuit sampling and conditioning the input and output voltage and current of the second power module.

[0013] Optionally, the main circuit includes: a transformer, a first single-pole double-throw relay, a first switching transistor, a first absorption circuit, and a first filter capacitor;

[0014] The two ends of the primary winding of the transformer are connected to the positive terminal of the first power module through the two contacts of the first single-pole double-throw relay.

[0015] The first end of the first absorption circuit is connected to the first single-pole double-throw relay, and the second end is connected to the second end of the primary side second winding;

[0016] The first end of the first switching transistor is connected to the second end of the primary side second winding, the second end is connected to the negative terminal of the first power module, and the third end is connected to the first driving circuit.

[0017] The first filter capacitor is connected in parallel to the positive and negative terminals of the first power module.

[0018] Optionally, the main circuit further includes: a second single-pole double-throw relay, a second switching transistor, a second absorption circuit, and a second filter capacitor;

[0019] The two ends of the first winding of the secondary side of the transformer are connected to the positive terminal of the second power module through the two contacts of the second single-pole double-throw relay;

[0020] The first end of the second absorption circuit is connected to the second single-pole double-throw relay, and the second end is connected to the second end of the secondary winding.

[0021] The first end of the second switching transistor is connected to the second end of the secondary winding, the second end is connected to the negative terminal of the second power module, and the third end is connected to the second drive circuit.

[0022] The second filter capacitor is connected in parallel to the positive and negative terminals of the second power module.

[0023] Optionally, the controller is also used for:

[0024] When power is transferred from the first power module to the second power module, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained.

[0025] The target positive turns ratio combination of the main circuit is determined based on the first conditioning signal and the second conditioning signal;

[0026] Through the first driving circuit and the second driving circuit, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target positive transformation ratio combination based on the output switching control signal;

[0027] Based on the target forward ratio combination, the first driving circuit and the second driving circuit control the input and output voltage and input and output current of the first switching transistor in the main circuit based on the output driving control signal.

[0028] Optionally, the controller is also used for:

[0029] When power is transferred from the second power module to the first power module, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained.

[0030] The target reverse turns ratio combination of the main circuit is determined based on the first conditioning signal and the second conditioning signal;

[0031] Through the first driving circuit and the second driving circuit, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target reverse transformation ratio combination based on the output switching control signal;

[0032] According to the target reverse ratio combination, the input and output voltage and input and output current of the second switch in the main circuit are controlled by the first drive circuit and the second drive circuit based on the output drive control signal.

[0033] Optionally, the sampling terminal of the first sampling circuit is also connected to the connection line between the power supply terminal of the main circuit and the negative terminal of the first power module.

[0034] The sampling terminal of the second sampling circuit is also connected to the line between the power supply terminal of the main circuit and the negative terminal of the second power module.

[0035] Optionally, the controller is also used for:

[0036] The output voltage feedback value and the output current feedback value output from the main circuit to the first power module are obtained. The output voltage feedback value and the output current feedback value are obtained by the first sampling circuit sampling and conditioning the voltage and current output from the main circuit.

[0037] Based on the output voltage feedback value and the output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output voltage or output current.

[0038] Optionally, the controller is also used for:

[0039] The output voltage feedback value and the output current feedback value output from the main circuit to the second power module are obtained. The output voltage feedback value and the output current feedback value are obtained by the second sampling circuit sampling and conditioning the voltage and current output from the main circuit.

[0040] Based on the output voltage feedback value and the output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output voltage or output current.

[0041] A second aspect of this invention discloses a control method for a bidirectional DC-DC circuit, applied to a controller in a bidirectional DC-DC circuit as described in any one of the first aspects of this invention, comprising:

[0042] When power is transmitted between the first power module and the second power module, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained. The first conditioning signal is obtained by the first sampling circuit sampling and conditioning the voltage and current input and output of the first power module, and the second conditioning signal is obtained by the second sampling circuit sampling and conditioning the voltage and current input and output of the second power module.

[0043] The target turns ratio combination of the main circuit is determined based on the first conditioning signal and the second conditioning signal.

[0044] The main circuit is controlled to switch to the target transformer ratio combination based on the output switching control signal through the first drive circuit and the second drive circuit.

[0045] Based on the target turns ratio combination, the main circuit is controlled by the first drive circuit and the second drive circuit, using the output drive control signal to control the input and output voltage and input and output current.

[0046] Optional, also includes:

[0047] Obtain the input / output voltage feedback values ​​and input / output current feedback values ​​of the main circuit;

[0048] Based on the input / output voltage feedback value and the input / output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0049] Optionally, when power is transmitted between the first power module and the second power module, obtaining the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit includes:

[0050] When power is transferred from the first power module to the second power module, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained.

[0051] Optionally, determining the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal includes:

[0052] Calculate the first lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal;

[0053] Determine all possible combinations of forward turns ratio for the transformer;

[0054] Select the target positive ratio combination that matches the first lower limit value from all the positive ratio combinations.

[0055] Optionally, controlling the main circuit to switch to the target transformer ratio combination based on the output switching control signal via the first and second driving circuits includes:

[0056] The output switching control signal is sent to the main circuit through the first driving circuit and the second driving circuit.

[0057] Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target positive transformation ratio combination.

[0058] Optionally, the step of controlling the output voltage and output current of the main circuit based on the output drive control signal through the first drive circuit and the second drive circuit, according to the target turns ratio combination, includes:

[0059] According to the target positive ratio combination, the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit;

[0060] Based on the drive control signal, the input and output voltage and input and output current of the first switching transistor in the main circuit are controlled.

[0061] Optional, also includes:

[0062] Obtain the input / output voltage feedback value and input / output current feedback value of the first switching transistor;

[0063] Based on the input / output voltage feedback value of the first switching transistor and the input / output current feedback value, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0064] Optionally, when power is transmitted between the first power module and the second power module, obtaining the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit includes:

[0065] When power is transferred from the second power module to the first power module, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained.

[0066] Optionally, determining the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal includes:

[0067] Calculate the second lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal;

[0068] Determine all possible combinations of reverse turns ratio for the transformer;

[0069] Select the target reverse ratio combination that matches the second lower limit value from all the reverse ratio combinations.

[0070] Optionally, controlling the main circuit to switch to the target transformer ratio combination based on the output switching control signal via the first and second driving circuits includes:

[0071] The output switching control signal is sent to the main circuit through the first driving circuit and the second driving circuit.

[0072] Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target reverse transformation ratio combination.

[0073] Optionally, the step of controlling the output voltage and output current of the main circuit based on the output drive control signal through the first drive circuit and the second drive circuit, according to the target turns ratio combination, includes:

[0074] According to the target reverse ratio combination, the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit;

[0075] Based on the drive control signal, the input and output voltage and input and output current of the second switching transistor in the main circuit are controlled.

[0076] Optional, also includes:

[0077] Obtain the input / output voltage feedback value and input / output current feedback value of the second switch transistor;

[0078] Based on the input / output voltage feedback value of the second switching transistor and the input / output current feedback value, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0079] Based on the above embodiments of the present invention, a bidirectional DC-DC circuit and its control method are provided. The bidirectional DC-DC circuit includes: a first power module, a second power module, a main circuit, a first sampling circuit, a second sampling circuit, a first driving circuit, a second driving circuit, and a controller. The two power terminals of the main circuit are respectively connected to the positive and negative terminals of the first power module and the second power module. The two drive control terminals of the main circuit are respectively connected to the controller through the first driving circuit and the second driving circuit. The sampling terminal of the first sampling circuit is connected to the first power module, and the output terminal of the first sampling circuit is connected to the controller. The sampling terminal of the second sampling circuit is connected to the second power module, and the output terminal of the second sampling circuit is connected to the controller. The controller is used to control the power supply when the power supply is applied to the first power module and the second power module. During transmission between the second power modules, a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit are obtained. Based on the first conditioning signal and the second conditioning signal, a target turns ratio combination of the main circuit is determined. The main circuit is controlled to switch to the target turns ratio combination based on the output switching control signal through the first driving circuit and the second driving circuit. Based on the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled by the first driving circuit and the second driving circuit based on the output driving control signal. The first conditioning signal is obtained by the first sampling circuit sampling and conditioning the input and output voltage and current of the first power module, and the second conditioning signal is obtained by the second sampling circuit sampling and conditioning the input and output voltage and current of the second power module. In this scheme, the first power module, the second power module, the main circuit, the first sampling circuit, the second sampling circuit, the first drive circuit, the second drive circuit, and the controller are connected accordingly, thereby simplifying the topology and circuit loop and reducing device costs. Moreover, when power is transmitted between the first power module and the second power module, the controller determines the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal. Then, through the first drive circuit and the second drive circuit, the controller controls the main circuit to switch to the target turns ratio combination based on the switching control signal. Thus, according to the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled, so as to achieve driving with a unified drive signal and ensure the stability of output voltage and current. Attached Figure Description

[0080] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0081] Figure 1 is a schematic diagram of a conventional wide-range bidirectional DC-DC converter provided in an embodiment of the present invention;

[0082] Figure 2 is a schematic diagram of a bidirectional DC-DC circuit provided in an embodiment of the present invention;

[0083] Figure 3 is a schematic diagram of another bidirectional DC-CDC circuit provided in an embodiment of the present invention;

[0084] Figure 4 is a schematic diagram of the structure of a bidirectional DC-DC circuit in a practical application scenario provided by an embodiment of the present invention;

[0085] Figure 5 is a flowchart illustrating a control method for a bidirectional DC-DC circuit provided in an embodiment of the present invention;

[0086] Figure 6 is a flowchart illustrating another control method for a bidirectional DC-DC circuit provided in an embodiment of the present invention;

[0087] Figure 7 is a flowchart illustrating another control method for a bidirectional DC-DC circuit provided in an embodiment of the present invention. Detailed Implementation

[0088] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0089] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0090] As can be seen from the background technology, existing methods for implementing bidirectional DC-DC converters to adapt to a wide input and output range have complex topologies and circuit loops, increasing device costs. They also do not use a unified driving signal, which cannot guarantee the stability of output voltage and current.

[0091] Therefore, this invention provides a bidirectional DC-DC circuit and its control method. In this solution, a first power module, a second power module, a main circuit, a first sampling circuit, a second sampling circuit, a first driving circuit, a second driving circuit, and a controller are connected accordingly, thereby simplifying the topology and circuit loop and reducing device costs. Moreover, when power is transmitted between the first power module and the second power module, the controller determines the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal. Then, through the first driving circuit and the second driving circuit, the controller controls the main circuit to switch to the target turns ratio combination based on the switching control signal. Thus, according to the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled, achieving the use of a unified driving signal for driving and ensuring the stability of the output voltage and current.

[0092] Figure 2 shows a schematic diagram of a bidirectional DC-DC circuit provided in an embodiment of the present invention. The bidirectional DC-DC circuit 1 includes: a first power module 10, a second power module 11, a main circuit 12, a first sampling circuit 13, a first driving circuit 14, a second sampling circuit 15, a second driving circuit 16, and a controller 17.

[0093] In this embodiment of the invention, the first power module 10, the second power module 11, the main circuit 12, the first sampling circuit 13, the first driving circuit 14, the second sampling circuit 15, the second driving circuit 16, and the controller 17 are electrically connected.

[0094] In this embodiment of the invention, the controller 17 can be understood as a control circuit.

[0095] Specifically, the two power supply terminals of the main circuit 12 are connected to the positive and negative terminals of the first power module 10 and the second power module 11, respectively, and the two drive control terminals of the main circuit 12 are connected to the controller 17 through the first drive circuit 14 and the second drive circuit 16, respectively.

[0096] In this embodiment of the invention, the first power module 10 can be represented as U1, and the second power module 11 can be represented as U2.

[0097] In a specific implementation, the first power supply terminal of the main circuit 12 is connected to the positive and negative terminals of the first power module 10 through two DC buses, and the second power supply terminal is connected to the positive and negative terminals of the second power module 11 through two DC buses.

[0098] In one specific embodiment, the first power supply terminal of the main circuit 12 is connected to the positive and negative terminals of the second power module 11 via two DC buses, and the second power supply terminal is connected to the positive and negative terminals of the first power module 10 via two DC buses.

[0099] The first drive control terminal of the main circuit 12 is connected to the controller 17 through the first drive circuit 14, and the second drive control terminal is connected to the controller 17 through the second drive circuit 16.

[0100] In one specific embodiment, the first drive control terminal of the main circuit 12 is connected to the controller 17 through the second drive circuit 16, and the second drive control terminal is connected to the controller 17 through the first drive circuit 14.

[0101] Specifically, the sampling terminal of the first sampling circuit 13 is connected to the first power supply module 10, and the output terminal of the first sampling circuit 13 is connected to the controller 17.

[0102] In one specific embodiment, the sampling terminal of the first sampling circuit 13 is connected to the second power module 11, and the output terminal of the first sampling circuit 13 is connected to the controller 17.

[0103] Specifically, the sampling terminal of the second sampling circuit 15 is connected to the second power supply module 11, and the output terminal of the second sampling circuit 15 is connected to the controller 17.

[0104] In one specific embodiment, the sampling terminal of the second sampling circuit 15 is connected to the first power module 10, and the output terminal of the second sampling circuit 15 is connected to the controller 17.

[0105] However, the specific connection method described above is not limited to this. As long as the first power module 10, the second power module 11, the main circuit 12, the first sampling circuit 13, the first driving circuit 14, the second sampling circuit 15, the second driving circuit 16, and the controller 17 are electrically connected, it is acceptable.

[0106] The first power module 10 and the second power module 11 provide power to the main circuit.

[0107] In some embodiments, the first power module 10 can be a battery or a DC voltage source.

[0108] In some embodiments, the second power module 11 can be a battery or a DC voltage source.

[0109] The main circuit 12 is used to perform corresponding control operations based on the control signals from the controller 17.

[0110] The first sampling circuit 13 and the second sampling circuit 15 are used to sample the input and output voltage and current, condition the sampled voltage and current, and send the conditioned signal to the controller 17.

[0111] In some embodiments, the first sampling circuit 13 and the second sampling circuit 15 are provided with a conditioning module, which conditions the sampled voltage and current to obtain a voltage signal or current signal that meets the output requirements.

[0112] In some embodiments, the controller 17 is preferably a PWM (Pulse Width Modulation) driver chip.

[0113] In some embodiments, the controller 17 is preferably an MCU (Microcontroller Unit) chip.

[0114] When controller 17 uses a PWM driver chip to drive the main circuit, the stability of the output voltage and current is controlled by a closed-loop hardware analog circuit. See below for details.

[0115] When controller 17 uses an MCU chip to drive the main circuit, the stability of the output voltage and current is achieved by digital control of the MCU. See below for details.

[0116] Specifically, when power is transmitted between the first power module 10 and the second power module 11, the first sampling circuit 13 samples the voltage and current input and output of the first power module 10, conditions the sampled voltage and current to obtain a first conditioning signal, and outputs the first conditioning signal to the controller 17.

[0117] The second sampling circuit 15 samples the voltage and current input and output of the second power module 11, conditions the sampled voltage and current to obtain a second conditioning signal, and outputs the second conditioning signal to the controller 17.

[0118] The controller 17 obtains the first conditioning signal output by the first sampling circuit 13 and the second conditioning signal output by the second sampling circuit 15, and determines the target turns ratio combination of the main circuit 12 based on the first conditioning signal and the second conditioning signal.

[0119] The controller 17 controls the main circuit 12 to switch to the target ratio combination based on the output switching control signal through the first drive circuit 14 and the second drive circuit 16.

[0120] According to the target turns ratio combination, the controller 17 controls the input and output voltage and input and output current of the main circuit 12 based on the output drive control signal through the first drive circuit 14 and the second drive circuit 16.

[0121] It should be noted that power can be transmitted from the first power module 10 to the second power module 11, or from the second power module 101 to the first power module 10.

[0122] In this context, "power source" can be understood as "energy".

[0123] In other words, energy can be transferred from U1 to U2, or from U2 to U1.

[0124] It should be noted that determining the target turns ratio combination of the main circuit 12 can be either the target forward turns ratio combination or the target reverse turns ratio combination, depending on the power transmission direction. Please refer to the following description for details.

[0125] Referring again to Figure 2, the sampling terminal of the first sampling circuit 13 is also connected to the connection line between the power supply terminal of the main circuit 12 and the negative terminal of the first power module 10.

[0126] At this time, the controller 17 is also used to: obtain the output voltage feedback value and output current feedback value of the main circuit 12 to the first power module 10, and modulate the duty cycle of the drive control signal in real time according to the output voltage feedback value and output current feedback value of the main circuit 12 to obtain a stable output voltage or output current.

[0127] The output voltage feedback value and the output current feedback value are obtained by the first sampling circuit 13 sampling and conditioning the voltage and current output by the main circuit 12.

[0128] The sampling terminal of the second sampling circuit 15 is also connected to the line between the power supply terminal of the main circuit 12 and the negative terminal of the second power module 11.

[0129] At this time, the controller 17 is also used to: obtain the output voltage feedback value and output current feedback value of the main circuit 12 to the second power module 11, and modulate the duty cycle of the drive control signal in real time according to the output voltage feedback value and output current feedback value of the main circuit 12 to obtain a stable output voltage or output current.

[0130] The output voltage feedback value and the output current feedback value are obtained by the second sampling circuit 15 sampling and conditioning the voltage and current output by the main circuit 12.

[0131] In this embodiment of the invention, the main circuit includes: a transformer, a first single-pole double-throw relay, a first switching transistor, a first absorption circuit, and a first filter capacitor.

[0132] Figure 3 shows a schematic diagram of another bidirectional DC-DC circuit provided in an embodiment of the present invention. The main circuit 12 includes: a transformer T, a first single-pole double-throw relay RL1, a first switching transistor S1, a first absorption circuit, and a first filter capacitor C1.

[0133] Specifically, the two ends of the primary winding of transformer T are connected to the positive terminal of the first power module 10 through the two contacts of the first single-pole double-throw relay RL1;

[0134] The first end of the first absorption circuit is connected to the first single-pole double-throw relay RL1, and the second end is connected to the second end of the primary side second winding.

[0135] The first terminal of the first switching transistor S1 is connected to the second terminal of the primary side second winding, the second terminal is connected to the negative terminal of the first power module 10, and the third terminal is connected to the first driving circuit 14.

[0136] The first filter capacitor C1 is connected in parallel to the positive and negative terminals of the first power module 10.

[0137] Among them, transformer T is a device that uses the principle of electromagnetic induction to change AC voltage.

[0138] The primary winding of transformer T has two windings with turns np1 and np2 respectively, that is, the first winding of the primary winding is np1 and the second winding of the primary winding is np2.

[0139] The first single-pole double-throw relay RL1 can avoid the problem of short circuits between transformer turns caused by contact sticking.

[0140] The first switching transistor S1 uses an electronic switching device (such as the first single-pole double-throw relay RL1) to continuously "turn on" and "turn off" the electronic switching device through a control circuit (i.e., controller 12), so that the electronic device can pulse modulate the input voltage, thereby realizing DC / AC and DC / DC voltage conversion, as well as adjustable and automatic voltage regulation of the output voltage.

[0141] The first absorption circuit is used to absorb the energy stored in the leakage inductance of the transformer T to avoid excessively high voltage spikes when the first switching transistor S1 is turned off.

[0142] The first filter capacitor C1 is used to remove noise and interference from the circuit, provide a stable power supply voltage, and protect the normal operation of other electronic components.

[0143] Referring again to Figure 3, the main circuit 12 also includes: a second single-pole double-throw relay RL2, a second switching transistor S2, a second absorption circuit, and a second filter capacitor C2.

[0144] Specifically, the two ends of the first winding of the secondary side of transformer T are connected to the positive terminal of the second power module 11 through the two contacts of the second single-pole double-throw relay RL2;

[0145] The first end of the second absorption circuit is connected to the second single-pole double-throw relay RL2, and the second end is connected to the second end of the secondary winding.

[0146] The first end of the second switch S2 is connected to the second end of the secondary winding, the second end is connected to the negative terminal of the second power module 11, and the third end is connected to the second drive circuit 16.

[0147] The second filter capacitor C2 is connected in parallel to the positive and negative terminals of the second power module 11.

[0148] The functions of the second single-pole double-throw relay RL1, the second switching transistor S2, the second absorption circuit, and the second filter capacitor C2 are similar to those of the first single-pole double-throw relay RL1, the first switching transistor S1, the first absorption circuit, and the first filter capacitor C1 described above, and can be referred to therefor; they will not be repeated here.

[0149] The secondary side of transformer T has two windings with turns of ns1 and ns2, respectively. That is, the first winding of the secondary side is ns1 and the second winding of the secondary side is ns2.

[0150] Furthermore, the first switch S1 and the second switch S2 include, but are not limited to, PMOS switches, NMOS switches, and transistors.

[0151] According to Figure 3, in a specific implementation, when power is transmitted from the first power module 10 to the second power module 11, the controller 17 obtains the first conditioning signal output by the first sampling circuit 13 and the second conditioning signal output by the second sampling circuit 15.

[0152] It should be noted that the power is transmitted from the first power module 10 to the second power module 11, which means that the bidirectional DC-DC circuit is working in the forward direction, and energy is transferred from U1 to U2.

[0153] The controller 17 determines the target positive turns ratio combination of the main circuit 12 based on the first conditioning signal and the second conditioning signal;

[0154] It should be noted that when the circuit is operating in the forward direction, the transformer can form four turns ratio relationships, namely (ns1+ns2) / np2, (ns1+ns2) / (np1+np2), ns2 / np2, and ns2 / (np1+np2).

[0155] When working in the forward direction, the relationship between U2 and U1 is: U2 = U1 * Nsp * D / (1 - D),

[0156] Where Nsp is the transformer turns ratio, D is the duty cycle of switch S1, and D < 0.5.

[0157] In practical applications, after the controller 17 obtains the values ​​of U1 and U2, that is, after the controller 17 obtains the first conditioning signal and the second conditioning signal, it calculates the lower limit of the value of Nsp through the relationship between U2 and U1. Then, it selects the combination that is closest to the lower limit of the value of Nsp from the four possible turns ratio combinations to determine the target positive turns ratio combination of the main circuit.

[0158] The controller 17 controls the first single-pole double-throw relay RL1 and the second single-pole double-throw relay RL2 in the main circuit 12 to switch from the current ratio combination to the target positive ratio combination based on the output switching control signal through the first drive circuit 14 and the second drive circuit 16.

[0159] According to the target positive transformation ratio combination, the controller 17 controls the input and output voltage and input and output current of the first switch S1 in the main circuit 12 based on the output drive control signal through the first drive circuit 14 and the second drive circuit 16.

[0160] According to Figure 3, in a specific implementation, when power is transmitted from the second power module 11 to the first power module 10, the controller 17 obtains the first conditioning signal output by the first sampling circuit 13 and the second conditioning signal output by the second sampling circuit 15.

[0161] It should be noted that the power is transmitted from the second power module 11 to the first power module 10, which means that the bidirectional DC-DC circuit is working in reverse, and energy is transferred from U2 to U1.

[0162] The controller 17 determines the target reverse ratio combination of the main circuit 12 based on the first conditioning signal and the second conditioning signal;

[0163] It should be noted that when the circuit operates in reverse, the transformer can form four turns ratio relationships, namely (np1+np2) / ns2, (np1+np2) / (ns1+ns2), np2 / ns2, and np2 / (ns1+ns2).

[0164] When working in reverse, the relationship between U1 and U2 is: U1 = U2 * Nps * D / (1 - D),

[0165] Where Nps is the transformer turns ratio, D is the duty cycle of switch S2, and D < 0.5.

[0166] In practical applications, after the controller 17 obtains the values ​​of U1 and U2, that is, after the controller 17 obtains the first conditioning signal and the second conditioning signal, it calculates the lower limit of the value of Nps through the relationship between U1 and U2. Then, it selects the combination that is closest to the lower limit of the value of Nps from the four possible turns ratio combinations to determine the target reverse turns ratio combination of the main circuit.

[0167] The controller 17 controls the first single-pole double-throw relay RL1 and the second single-pole double-throw relay RL2 in the main circuit 12 to switch from the current ratio combination to the target reverse ratio combination based on the output switching control signal through the first drive circuit 14 and the second drive circuit 16.

[0168] According to the target reverse ratio combination, the controller 17 controls the input and output voltage and input and output current of the second switch S2 in the main circuit 12 based on the output drive control signal through the first drive circuit 14 and the second drive circuit 16.

[0169] To better understand the bidirectional DC-DC circuit described above, Figure 4 shows a schematic diagram of the structure of a bidirectional DC-DC circuit in a practical application scenario provided by an embodiment of the present invention.

[0170] In Figure 4, the two ends of the primary winding np1 of transformer T are connected to U1 through the two contacts of single-pole double-throw relay RL1. The two ends of the secondary winding ns1 of transformer T are connected to U2 through the two contacts of single-pole double-throw relay RL2.

[0171] The first end of the absorption circuit 1 is connected to the single-pole double-throw relay RL1, and the second end is connected to the second end of the primary winding np2.

[0172] The first terminal of the switching transistor S1 is connected to the second terminal of the primary winding np2, the second terminal is connected to the negative terminal of U1, and the third terminal is connected to the drive circuit 1.

[0173] The filter capacitor C1 is connected in parallel to the positive and negative terminals of U1.

[0174] The first end of the absorption circuit 2 is connected to the single-pole double-throw relay RL2, and the second end is connected to the second end of the secondary winding ns2.

[0175] The first terminal of the switching transistor S2 is connected to the second terminal of the secondary winding ns2, the second terminal is connected to the negative terminal of U2, and the third terminal is connected to the drive circuit 2.

[0176] The filter capacitor C2 is connected in parallel to the positive and negative terminals of U2.

[0177] In practical applications, when the circuit is operating in the forward direction (U1 is transmitted to U2), the transformer can form four turns ratio relationships, namely (ns1+ns2) / np2, (ns1+ns2) / (np1+np2), ns2 / np2, and ns2 / (np1+np2).

[0178] When working in the forward direction, the relationship between U2 and U1 is: U2 = U1 * Nsp * D / (1 - D),

[0179] Where Nsp is the transformer turns ratio, D is the duty cycle of switch S1, and D < 0.5.

[0180] After the controller obtains the values ​​of U1 and U2, that is, after the controller 17 obtains the first conditioning signal and the second conditioning signal, it calculates the lower limit of the value of Nsp through the relationship between U2 and U1, and selects the combination that is closest to the lower limit of the value of Nsp from the four possible turns ratio combinations.

[0181] Then, controller 17 sends a signal to switch the states of RL1 and RL2 to the determined combination.

[0182] After the relay state switching is completed, the controller 17 generates a drive signal to control S1, and adjusts the duty cycle of the drive signal in real time according to the input and output voltage and current feedback values ​​to obtain a stable current or voltage.

[0183] In practical applications, when the circuit operates in reverse (U2 is transmitted to U1), the transformer can form four turns ratio relationships, namely (np1+np2) / ns2, (np1+np2) / (ns1+ns2), np2 / ns2, and np2 / (ns1+ns2).

[0184] When working in reverse, the relationship between U1 and U2 is: U1 = U2 * Nps * D / (1 - D),

[0185] Where Nps is the transformer turns ratio, D is the duty cycle of switch S2, and D < 0.5.

[0186] After the controller obtains the values ​​of U1 and U2, that is, after the controller 17 obtains the first conditioning signal and the second conditioning signal, it calculates the lower limit of the value of Nps through the relationship between U1 and U2, and selects the combination that is closest to the lower limit of the value of Nps from the four possible turns ratio combinations.

[0187] Then, controller 17 sends a signal to switch the states of RL1 and RL2 to the determined combination.

[0188] After the relay state switching is completed, the controller 17 generates a drive signal to control S2, and adjusts the duty cycle of the drive signal in real time according to the input and output voltage and current feedback values ​​to obtain a stable current or voltage.

[0189] As can be seen from the above description, the bidirectional DC-DC circuit described above adopts a single-stage bidirectional flyback topology, which has a simple architecture, requires only two switching transistors and one main transformer, and has a small size and low cost.

[0190] Moreover, the transformer uses two windings on the primary and secondary sides, and each winding is switched using a single-pole double-throw relay. The single-pole double-throw relay can avoid the problem of inter-turn short circuits in the transformer caused by contact sticking.

[0191] Furthermore, the transformation ratios of the primary and secondary sides can be combined in four different ways by using different single-pole double-throw relay switching states. The system determines which combination of primary and secondary transformation ratios to use by sampling the input and output voltages and calculating the relationship between the input and output voltages. The flexible configuration of the primary and secondary transformation ratios allows the circuit's drive duty cycle to be maintained below 0.5, reducing the current and voltage stress during circuit operation, making the circuit loop control design simpler and more reliable, the protection more timely, and the electromagnetic compatibility performance better.

[0192] Alternatively, the controller can use an integrated PWM driver chip or an MCU / DSP to generate the drive signal. When using an integrated PWM chip to drive the primary and secondary switches, the stability of the output voltage and current is achieved through closed-loop control by hardware analog circuitry; when using an MCU to generate the signal to drive the primary and secondary switches, the stability of the output voltage and current is achieved through digital control by the MCU.

[0193] Based on the bidirectional DC-DC circuit provided by the above embodiments of the present invention, the first power module, the second power module, the main circuit, the first sampling circuit, the second sampling circuit, the first driving circuit, the second driving circuit, and the controller are correspondingly connected, thereby simplifying the topology and circuit loop and reducing device costs. Moreover, when power is transmitted between the first power module and the second power module, the controller determines the target turns ratio combination of the main circuit according to the first conditioning signal and the second conditioning signal, and then controls the main circuit to switch to the target turns ratio combination based on the switching control signal through the first driving circuit and the second driving circuit. Thus, according to the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled, and a unified driving signal is used for driving to ensure the stability of the output voltage and current.

[0194] Corresponding to the bidirectional DC-DC circuit shown in the above embodiments of the present invention, the present invention also provides a control method for a bidirectional DC-DC circuit, which is applied to the controller in the bidirectional DC-DC circuit as described in any of the above embodiments. The specific structure and working principle of the bidirectional DC-DC circuit can be found in the above embodiments, and will not be described in detail here.

[0195] As shown in Figure 5, the control method of this bidirectional DC-DC circuit mainly includes the following steps:

[0196] Step S501: When power is transferred between the first power module and the second power module, execute step S502; otherwise, end the operation.

[0197] In the specific implementation of step S501, if there is power transmission between the first power module and the second power module, it indicates that the bidirectional DC-DC circuit is in working state, and step S502 is executed; if there is no power transmission between the first power module and the second power module, it indicates that the bidirectional DC-DC circuit is in shutdown state, and the operation is terminated directly.

[0198] Step S502: Obtain the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit.

[0199] In step S502, the first conditioning signal is obtained by the first sampling circuit sampling and conditioning the voltage and current input and output of the first power module.

[0200] The second conditioning signal is obtained by the second sampling circuit sampling and conditioning the voltage and current input and output of the second power module.

[0201] In the specific implementation of step S502, when it is determined that the power supply is transmitted between the first power supply module and the second power supply module, the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit are obtained.

[0202] Step S503: Determine the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal.

[0203] It should be noted that the target ratio combination can be a target forward ratio combination or a target reverse ratio combination.

[0204] In the specific implementation of step S503, the lower limit of the transformer ratio is calculated based on the first conditioning signal and the second conditioning signal, all transformer ratio combinations are determined, and the target transformer ratio combination that matches the lower limit value is selected from all transformer ratio combinations.

[0205] Step S504: The main circuit is controlled to switch to the target transformer ratio combination based on the output switching control signal through the first drive circuit and the second drive circuit.

[0206] In the specific implementation of step S504, based on the target transformation ratio combination, a switching control signal is output. Through the first driving circuit and the second driving circuit, the output switching control signal is sent to the main circuit to determine the current transformation ratio combination of the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit. Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target transformation ratio combination.

[0207] In practical applications, when the target turns ratio combination is the target forward turns ratio combination, a switching control signal is output based on the target forward turns ratio combination. The output switching control signal is sent to the main circuit through the first drive circuit and the second drive circuit to determine the current turns ratio combination of the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit. Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current turns ratio combination to the target forward turns ratio combination.

[0208] When the target turns ratio combination is the target reverse turns ratio combination, a switching control signal is output based on the target reverse turns ratio combination. The output switching control signal is sent to the main circuit through the first drive circuit and the second drive circuit to determine the current turns ratio combination of the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit. Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current turns ratio combination to the target reverse turns ratio combination.

[0209] Step S505: Based on the target turns ratio combination, the input and output voltages and currents of the main circuit are controlled by the first and second drive circuits based on the output drive control signals.

[0210] In the specific implementation of step S505, after the relay state switching is completed, a drive control signal is output according to the target transformation ratio combination. Through the first drive circuit and the second drive circuit, the input and output voltage and input and output current of the main circuit are controlled based on the output drive control signal.

[0211] In practical applications, when the target turns ratio combination is the target forward turns ratio combination, after the relay state switching is completed, a drive control signal is output according to the target forward turns ratio combination. Through the first drive circuit and the second drive circuit, the input and output voltage and input and output current of the first switch in the main circuit are controlled based on the output drive control signal.

[0212] When the target turns ratio combination is the target reverse turns ratio combination, after the relay state switching is completed, a drive control signal is output according to the target reverse turns ratio combination. Through the first drive circuit and the second drive circuit, the input and output voltage and input and output current of the second switch in the main circuit are controlled based on the output drive control signal.

[0213] Preferably, after executing step S505, which controls the input / output voltage and input / output current of the main circuit based on the output drive control signal, the method further includes:

[0214] The input and output voltage feedback values ​​and input and output current feedback values ​​of the main circuit are obtained. Based on the input and output voltage feedback values ​​and input and output current feedback values ​​of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0215] It should be noted that the flexible configuration of the primary and secondary winding ratios allows the circuit's drive duty cycle to be maintained below 0.5.

[0216] Based on the above-described control method for a bidirectional DC-DC circuit provided by the present invention, when power is transmitted between the first power module and the second power module, the controller determines the target turns ratio combination of the main circuit according to the first conditioning signal and the second conditioning signal, and then controls the main circuit to switch to the target turns ratio combination based on the switching control signal through the first driving circuit and the second driving circuit. Thus, according to the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled, so as to achieve driving with a unified driving signal and ensure the stability of output voltage and current.

[0217] Based on the above-described embodiment of the present invention, a control method for a bidirectional DC-DC circuit is provided. Figure 6 shows a flowchart illustrating another control method for a bidirectional DC-DC circuit provided by the present invention. This control method for the bidirectional DC-DC circuit mainly includes the following steps:

[0218] Step S601: When power is transferred from the first power module to the second power module, execute step S602; otherwise, end the operation.

[0219] In the specific implementation of step S601, if power is transmitted from the first power module to the second power module, it indicates that the bidirectional DC-DC circuit is in working state, and step S602 is executed; if no power is transmitted from the first power module to the second power module, it indicates that the bidirectional DC-DC circuit is in shutdown state, and the operation is terminated directly.

[0220] Step S602: Obtain the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit.

[0221] In the specific implementation of step S602, when it is determined that the power supply is transmitted from the first power supply module to the second power supply module, the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit are obtained.

[0222] Step S603: Calculate the first lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal.

[0223] In the specific implementation of step S603, when the circuit is working in the forward direction, after the controller obtains the values ​​of U1 and U2, that is, after obtaining the first conditioning signal and the second conditioning signal, it calculates the first lower limit value of the transformer ratio according to the relationship between U2 and U1: U2=U1*Nsp*D / (1-D).

[0224] Where Nsp is the transformer turns ratio, D is the duty cycle of switch S1, and D < 0.5.

[0225] Step S604: Determine all forward turns ratio combinations of the transformer.

[0226] In the specific implementation of step S604, when the circuit is working in the forward direction (U1 transmits to U2), it is determined that the transformer can form four turns ratio relationships, that is, all the forward turns ratio combinations of the transformer are determined to be: (ns1+ns2) / np2, (ns1+ns2) / (np1+np2), ns2 / np2 and ns2 / (np1+np2).

[0227] Step S605: Select the target positive ratio combination that matches the first lower limit value from all positive ratio combinations.

[0228] In the specific implementation of step S605, the target forward ratio combination of the main circuit can be determined by selecting the combination closest to the lower limit of Nsp from the four possible forward ratio combinations. For example, the target forward ratio combination that matches the first lower limit value can be selected from all forward ratio combinations as (ns1+ns2) / np2.

[0229] Step S606: The output switching control signal is sent to the main circuit through the first driving circuit and the second driving circuit.

[0230] In the specific implementation of step S606, based on the target forward ratio combination, a switching control signal is output, and the output switching control signal is sent to the main circuit through the first drive circuit and the second drive circuit.

[0231] Step S607: Based on the switching control signal, control the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current transformation ratio combination to the target positive transformation ratio combination.

[0232] In the specific implementation of step S607, the current transformation ratio combination of the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit is determined. Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target positive transformation ratio combination.

[0233] Step S608: Based on the target forward ratio combination, the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit.

[0234] In the specific implementation of step S608, after the relay state switching is completed, a drive control signal is output according to the target positive transformation ratio combination, and the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit.

[0235] Step S609: Based on the drive control signal, control the input and output voltage and input and output current of the first switching transistor in the main circuit.

[0236] Preferably, after performing step S609, which controls the input / output voltage and input / output current of the first switching transistor in the main circuit based on the drive control signal, the method further includes:

[0237] The input-output voltage feedback value and input-output current feedback value of the first switching transistor are obtained. Based on the input-output voltage feedback value and input-output current feedback value of the first switching transistor, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0238] Based on the above-described control method for a bidirectional DC-DC circuit provided by the present invention, when power is transmitted from the first power module to the second power module, the controller determines the target positive turns ratio combination of the main circuit according to the first conditioning signal and the second conditioning signal, and then controls the main circuit to switch to the target positive turns ratio combination based on the switching control signal through the first driving circuit and the second driving circuit. Thus, according to the target positive turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled, so as to achieve the use of a unified driving signal for driving and ensure the stability of output voltage and current.

[0239] Based on the above embodiments of the present invention, a control method for a bidirectional DC-DC circuit is provided. As shown in Figure 7, this is a flowchart illustrating another control method for a bidirectional DC-DC circuit provided by the present invention. The control method for this bidirectional DC-DC circuit mainly includes the following steps:

[0240] Step S701: When power is transferred from the second power module to the first power module, execute step S702; otherwise, end the operation.

[0241] In the specific implementation of step S701, if power is transmitted from the second power module to the first power module, it indicates that the bidirectional DC-DC circuit is in working state, and step S702 is executed; if no power is transmitted from the second power module to the first power module, it indicates that the bidirectional DC-DC circuit is in shutdown state, and the operation is terminated directly.

[0242] Step S702: Obtain the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit.

[0243] In the specific implementation of step S702, when it is determined that the power supply is transmitted from the second power supply module to the first power supply module, the first conditioning signal output by the first sampling circuit and the second conditioning signal output by the second sampling circuit are obtained.

[0244] Step S703: Calculate the second lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal.

[0245] In the specific implementation of step S703, when the circuit works in reverse, after the controller obtains the values ​​of U1 and U2, that is, after obtaining the first conditioning signal and the second conditioning signal, it calculates the second lower limit value of the transformer ratio according to the relationship between U1 and U2: U1=U2*Nps*D / (1-D).

[0246] Where Nsp is the transformer turns ratio, D is the duty cycle of switch S1, and D < 0.5.

[0247] Step S704: Determine all reverse turns ratio combinations of the transformer.

[0248] In the specific implementation of step S704, when the circuit operates in reverse (U2 transmits to U1), it is determined that the transformer can form four turns ratio relationships, that is, all reverse turns ratio combinations of the transformer are determined as: (np1+np2) / ns2, (np1+np2) / (ns1+ns2), np2 / ns2, and np2 / (ns1+ns2).

[0249] Step S705: Select the target reverse ratio combination that matches the second lower limit value from all reverse ratio combinations.

[0250] In the specific implementation of step S705, the target reverse turns ratio combination of the main circuit can be determined by selecting the combination closest to the lower limit of Nsp from the four possible reverse turns ratio combinations. For example, the target reverse turns ratio combination that matches the second lower limit value can be selected from all reverse turns ratio combinations as (np1+np2) / ns2.

[0251] Step S706: The output switching control signal is sent to the main circuit through the first driving circuit and the second driving circuit.

[0252] In the specific implementation of step S706, based on the target reverse ratio combination, a switching control signal is output, and the output switching control signal is sent to the main circuit through the first driving circuit and the second driving circuit.

[0253] Step S707: Based on the switching control signal, control the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current transformation ratio combination to the target reverse transformation ratio combination.

[0254] In the specific implementation step S707, the current transformation ratio combination of the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit is determined. Based on the switching control signal, the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit are controlled to switch from the current transformation ratio combination to the target reverse transformation ratio combination.

[0255] Step S708: Based on the target reverse ratio combination, the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit.

[0256] In the specific implementation of step S708, after the relay state switching is completed, a drive control signal is output according to the target reverse ratio combination, and the output drive control signal is sent to the main circuit through the first drive circuit and the second drive circuit.

[0257] Step S709: Based on the drive control signal, control the input and output voltage and input and output current of the second switching transistor in the main circuit.

[0258] Preferably, after performing step S709, which controls the input / output voltage and input / output current of the second switching transistor in the main circuit based on the drive control signal, the method further includes:

[0259] The input-output voltage feedback value and input-output current feedback value of the second switching transistor are obtained. Based on the input-output voltage feedback value and input-output current feedback value of the second switching transistor, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

[0260] Based on the above-described control method for a bidirectional DC-DC circuit provided by the present invention, when power is transmitted from the second power module to the first power module, the controller determines the target inverting turns ratio combination of the main circuit according to the first conditioning signal and the second conditioning signal. Then, through the first driving circuit and the second driving circuit, the controller controls the main circuit to switch to the target inverting turns ratio combination based on the switching control signal. Thus, according to the target inverting turns ratio combination, the controller controls the input and output voltage and input and output current of the main circuit, thereby achieving the use of a unified driving signal for driving and ensuring the stability of the output voltage and current.

[0261] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions in the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0262] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0263] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bidirectional DC-DC circuit, characterized in that, include: The system comprises a first power module, a second power module, a main circuit, a first sampling circuit, a second sampling circuit, a first drive circuit, a second drive circuit, and a controller. The two power terminals of the main circuit are respectively connected to the positive and negative terminals of the first and second power modules. The two drive control terminals of the main circuit are respectively connected to the controller through the first and second drive circuits. The sampling terminal of the first sampling circuit is connected to the first power module, and its output terminal is connected to the controller. The sampling terminal of the second sampling circuit is connected to the second power module, and its output terminal is connected to the controller. The controller is used to obtain the first sampling circuit data when power is transmitted between the first and second power modules. The first conditioning signal output by the sampling circuit and the second conditioning signal output by the second sampling circuit are used to determine the target turns ratio combination of the main circuit. The main circuit is controlled to switch to the target turns ratio combination based on the output switching control signal through the first driving circuit and the second driving circuit. Based on the target turns ratio combination, the input and output voltage and input and output current of the main circuit are controlled by the first driving circuit and the second driving circuit based on the output driving control signal. The first conditioning signal is obtained by the first sampling circuit sampling and conditioning the input and output voltage and current of the first power module, and the second conditioning signal is obtained by the second sampling circuit sampling and conditioning the input and output voltage and current of the second power module.

2. The bidirectional DC-DC circuit according to claim 1, characterized in that, The main circuit includes: a transformer, a first single-pole double-throw relay, a first switching transistor, a first absorption circuit, and a first filter capacitor; the two ends of the primary winding of the transformer are connected to the positive terminal of the first power module through the two contacts of the first single-pole double-throw relay; the first end of the first absorption circuit is connected to the first single-pole double-throw relay, and the second end is connected to the second end of the primary winding; the first end of the first switching transistor is connected to the second end of the primary winding, the second end is connected to the negative terminal of the first power module, and the third end is connected to the first drive circuit; the first filter capacitor is connected in parallel to the positive and negative terminals of the first power module.

3. The bidirectional DC-DC circuit according to claim 2, characterized in that, The main circuit further includes: a second single-pole double-throw relay, a second switching transistor, a second absorption circuit, and a second filter capacitor; the two ends of the first winding of the secondary side of the transformer are connected to the positive terminal of the second power module through the two contacts of the second single-pole double-throw relay; the first end of the second absorption circuit is connected to the second single-pole double-throw relay, and the second end is connected to the second end of the second winding of the secondary side; the first end of the second switching transistor is connected to the second end of the second winding of the secondary side, the second end is connected to the negative terminal of the second power module, and the third end is connected to the second drive circuit; the second filter capacitor is connected in parallel to the positive and negative terminals of the second power module.

4. The bidirectional DC-DC circuit according to any one of claims 1 to 3, characterized in that, The controller is further configured to: when power is transmitted from the first power module to the second power module, obtain a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit; determine a target positive turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal; and control the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current turns ratio combination to the target positive turns ratio combination based on the output switching control signal through the first drive circuit and the second drive circuit. Based on the target forward ratio combination, the first driving circuit and the second driving circuit control the input and output voltage and input and output current of the first switching transistor in the main circuit based on the output driving control signal.

5. The bidirectional DC-DC circuit according to any one of claims 1 to 3, characterized in that, The controller is further configured to: when power is transmitted from the second power module to the first power module, obtain a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit; determine a target reverse turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal; control the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current turns ratio combination to the target reverse turns ratio combination based on the output switching control signal through the first driving circuit and the second driving circuit; and control the input and output voltage and input and output current of the second switching transistor in the main circuit based on the output driving control signal through the first driving circuit and the second driving circuit according to the target reverse turns ratio combination.

6. The bidirectional DC-DC circuit according to claim 1, characterized in that, The sampling terminal of the first sampling circuit is also connected to the connection line between the power supply terminal of the main circuit and the negative terminal of the first power module; the sampling terminal of the second sampling circuit is also connected to the connection line between the power supply terminal of the main circuit and the negative terminal of the second power module.

7. The bidirectional DC-DC circuit according to claim 6, characterized in that, The controller is further configured to: obtain the output voltage feedback value and the output current feedback value output from the main circuit to the first power module, wherein the output voltage feedback value and the output current feedback value are obtained by the first sampling circuit sampling and conditioning the voltage and current output from the main circuit; Based on the output voltage feedback value and the output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output voltage or output current.

8. The bidirectional DC-DC circuit according to claim 6, characterized in that, The controller is further configured to: obtain the output voltage feedback value and the output current feedback value of the main circuit to the second power module, wherein the output voltage feedback value and the output current feedback value are obtained by the second sampling circuit sampling and conditioning the voltage and current output by the main circuit; Based on the output voltage feedback value and the output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output voltage or output current.

9. A control method for a bidirectional DC-DC circuit, characterized in that, A controller applied in a bidirectional DC-DC circuit according to any one of claims 1 to 8, comprising: when power is transmitted between a first power module and a second power module, obtaining a first conditioning signal output by a first sampling circuit and a second conditioning signal output by a second sampling circuit, wherein the first conditioning signal is obtained by the first sampling circuit sampling and conditioning the voltage and current input and output of the first power module, and the second conditioning signal is obtained by the second sampling circuit sampling and conditioning the voltage and current input and output of the second power module; determining a target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal; controlling the main circuit to switch to the target turns ratio combination based on an output switching control signal via a first driving circuit and a second driving circuit; and controlling the input and output voltage and input and output current of the main circuit based on an output driving control signal via the first driving circuit and the second driving circuit according to the target turns ratio combination.

10. The method according to claim 9, characterized in that, Also includes: Obtain the input / output voltage feedback values ​​and input / output current feedback values ​​of the main circuit; Based on the input / output voltage feedback value and the input / output current feedback value of the main circuit, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

11. The method according to claim 9, characterized in that, The step of obtaining a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit when the power supply is transmitted between the first power module and the second power module includes: obtaining a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit when the power supply is transmitted from the first power module to the second power module.

12. The method according to claim 11, characterized in that, The step of determining the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal includes: calculating a first lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal; determining all forward turns ratio combinations of the transformer; and selecting a target forward turns ratio combination that matches the first lower limit value from all forward turns ratio combinations.

13. The method according to claim 12, characterized in that, The step of controlling the main circuit to switch to the target transformer ratio combination based on the output switching control signal through the first driving circuit and the second driving circuit includes: sending the output switching control signal to the main circuit through the first driving circuit and the second driving circuit; and controlling the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current transformer ratio combination to the target forward transformer ratio combination based on the switching control signal.

14. The method according to claim 13, characterized in that, The step of controlling the output voltage and output current of the main circuit based on the output drive control signal through the first drive circuit and the second drive circuit according to the target turns ratio combination includes: sending the output drive control signal to the main circuit through the first drive circuit and the second drive circuit according to the target forward turns ratio combination; and controlling the input and output voltage and input and output current of the first switching transistor in the main circuit based on the drive control signal.

15. The method according to claim 14, characterized in that, Also includes: Obtain the input / output voltage feedback value and input / output current feedback value of the first switching transistor; Based on the input / output voltage feedback value of the first switching transistor and the input / output current feedback value, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

16. The method according to claim 9, characterized in that, The step of obtaining a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit when the power supply is transmitted between the first power module and the second power module includes: obtaining a first conditioning signal output by the first sampling circuit and a second conditioning signal output by the second sampling circuit when the power supply is transmitted from the second power module to the first power module.

17. The method according to claim 16, characterized in that, The step of determining the target turns ratio combination of the main circuit based on the first conditioning signal and the second conditioning signal includes: calculating a second lower limit value of the transformer turns ratio based on the first conditioning signal and the second conditioning signal; determining all reverse turns ratio combinations of the transformer; and selecting a target reverse turns ratio combination that matches the second lower limit value from all the reverse turns ratio combinations.

18. The method according to claim 17, characterized in that, The step of controlling the main circuit to switch to the target transformer ratio combination based on the output switching control signal through the first driving circuit and the second driving circuit includes: sending the output switching control signal to the main circuit through the first driving circuit and the second driving circuit; and controlling the first single-pole double-throw relay and the second single-pole double-throw relay in the main circuit to switch from the current transformer ratio combination to the target reverse transformer ratio combination based on the switching control signal.

19. The method according to claim 18, characterized in that, The step of controlling the output voltage and output current of the main circuit based on the output drive control signal through the first drive circuit and the second drive circuit according to the target inverted turns ratio combination includes: sending the output drive control signal to the main circuit through the first drive circuit and the second drive circuit according to the target inverted turns ratio combination; and controlling the input and output voltage and input and output current of the second switch in the main circuit based on the drive control signal.

20. The method according to claim 19, characterized in that, Also includes: Obtain the input / output voltage feedback value and input / output current feedback value of the second switch transistor; Based on the input / output voltage feedback value of the second switching transistor and the input / output current feedback value, the duty cycle of the drive control signal is modulated in real time to obtain a stable output current or output voltage.

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