Bidirectional LLC converter control method and device and bidirectional LLC converter

Abstract

The invention relates to a bidirectional LLC converter control method and device and a bidirectional LLC converter. The bidirectional LLC converter comprises a transformer, an LLC resonance circuit, a primary side bridge circuit and a secondary side bridge circuit. The secondary side bridge circuit comprises first, second, third and fourth power tubes; the primary bridge circuit comprises a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, and the control method comprises the steps that when the secondary bridge circuit is connected with power input, the first power tube and the fourth power tube are driven through a first driving signal, the first driving signal is delayed by a first phase shift angle to generate a second driving signal, and the sixth power tube is driven through the second driving signal; driving a second power tube and a third power tube through a third driving signal, delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, and driving a fifth power tube through the fourth driving signal; wherein the third driving signal and the first driving signal are opposite in phase. According to the invention, the gain of the bidirectional LLC converter during reverse working can be increased.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and more specifically, to a bidirectional LLC converter control method and device, and a bidirectional LLC converter. Background Art

[0002] In a traditional bidirectional LLC converter, the gain of the system is usually adjusted by adjusting the switching frequency of each power tube. This process ensures that the maximum gain of the bidirectional LLC converter does not exceed 1 when working in reverse, so that the output voltage range obtained when the bidirectional LLC converter works in reverse is narrow, which cannot be used in some application scenarios that require a wider output voltage range. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a bidirectional LLC converter control method, device and bidirectional LLC converter in view of the above-mentioned technical defects of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a bidirectional LLC converter control method, the bidirectional LLC converter comprising a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side bridge circuit connected to the LLC resonant circuit and a secondary side bridge circuit connected to the secondary side of the transformer;

[0005] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0006] The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit;

[0007] The control method comprises:

[0008] When the secondary bridge circuit is connected to the power input,

[0009] driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal;

[0010] driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal;

[0011] The third driving signal has a phase opposite to that of the first driving signal.

[0012] Preferably, in the bidirectional LLC converter control method described in the present invention, the first phase shift angle is the same as the second phase shift angle.

[0013] Preferably, in the bidirectional LLC converter control method of the present invention, the first phase shift angle and the second phase shift angle are both smaller than 180 degrees.

[0014] Preferably, in the bidirectional LLC converter control method of the present invention, the duty cycle of the first drive signal and the third drive signal are both 50%.

[0015] Preferably, in the bidirectional LLC converter control method of the present invention, the control method further comprises:

[0016] When the primary bridge circuit is connected to the power input,

[0017] driving the sixth power tube and the seventh power tube by a fifth driving signal, and generating a sixth driving signal according to the fifth driving signal, so as to drive the first power tube and the fourth power tube by the sixth driving signal;

[0018] driving the fifth power tube and the eighth power tube by a seventh driving signal, and generating an eighth driving signal according to the seventh driving signal, so as to drive the second power tube and the third power tube by the eighth driving signal;

[0019] The seventh driving signal has a phase opposite to that of the fifth driving signal.

[0020] Preferably, in the bidirectional LLC converter control method of the present invention, the fifth drive signal has the same phase as the sixth drive signal, and the seventh drive signal has the same phase as the eighth drive signal.

[0021] Preferably, in the bidirectional LLC converter control method of the present invention, the duty cycle of the fifth drive signal and the seventh drive signal are both 50%.

[0022] The present invention also constructs a bidirectional LLC converter control device for a bidirectional LLC converter, wherein the bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer;

[0023] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0024] The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit;

[0025] The control device is used for connecting the secondary bridge circuit to the power input.

[0026] driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal;

[0027] driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal;

[0028] The third driving signal has a phase opposite to that of the first driving signal.

[0029] Preferably, in the bidirectional LLC converter control device of the present invention, the control device is further configured to, when the primary bridge circuit is connected to a power input,

[0030] driving the sixth power tube and the seventh power tube by a fifth driving signal, and generating a sixth driving signal according to the fifth driving signal, so as to drive the first power tube and the fourth power tube by the sixth driving signal;

[0031] driving the fifth power tube and the eighth power tube by a seventh driving signal, and generating an eighth driving signal according to the seventh driving signal, so as to drive the second power tube and the third power tube by the eighth driving signal;

[0032] The seventh driving signal has a phase opposite to that of the fifth driving signal.

[0033] The present invention also constructs a bidirectional LLC converter, comprising: a controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer;

[0034] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0035] The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit;

[0036] The controller is used for connecting the secondary bridge circuit to the power input.

[0037] driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal;

[0038] driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal;

[0039] The third driving signal has a phase opposite to that of the first driving signal.

[0040] A bidirectional LLC converter control method, device and bidirectional LLC converter implementing the present invention have the following beneficial effects: the gain of the bidirectional LLC converter during reverse operation can be increased, and the application scenarios of the bidirectional LLC converter can be expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0042] Figure 11 is a schematic structural diagram of an embodiment of a bidirectional LLC converter in a bidirectional LLC converter control method of the present invention;

[0043] Figure 2 is a program flow chart of an embodiment of a bidirectional LLC converter control method of the present invention;

[0044] Figure 3 1 is a schematic diagram of working waveforms of an embodiment of a bidirectional LLC converter control method of the present invention;

[0045] Figure 4 It is a program flow chart of another embodiment of the bidirectional LLC converter control method of the present invention. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0047] like Figure 1 , shows an embodiment of a bidirectional LLC converter in a bidirectional LLC converter control method of the present invention, Figure 2 An embodiment of the bidirectional LLC converter control method of the present invention is shown. Figure 2 In the embodiment of the bidirectional LLC converter control method of the present invention shown in FIG. Figure 1As shown, it includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit includes a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are the upper bridge arm of the secondary bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary bridge circuit; the primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube, and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube The fifth power tube and the sixth power tube are connected in series, and the seventh power tube and the eighth power tube are the lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are the upper bridge arms of the primary bridge circuit; the control method includes: when the secondary bridge circuit is connected to the power input, S1, driving the first power tube and the fourth power tube through a first drive signal, and delaying the first drive signal by a first phase shift angle to generate a second drive signal, so as to drive the sixth power tube through the second drive signal; S2, driving the second power tube and the third power tube through a third drive signal, and delaying the third drive signal by a second phase shift angle to generate a fourth drive signal, so as to drive the fifth power tube through the fourth drive signal; wherein the third drive signal is opposite in phase to the first drive signal.

[0048] Specifically, in a bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, i.e., a power tube Q1, a second power tube, i.e., a power tube Q2, a third power tube, i.e., a power tube Q3, and a fourth power tube, i.e., a power tube Q4. The primary side of the transformer is connected to the primary side bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include a resonant inductor, i.e., an inductor Lr, and a resonant capacitor, i.e., a capacitor Cr, connected in series, and the primary side bridge circuit is a full-bridge circuit composed of a fifth power tube, i.e., a power tube Q5, a sixth power tube, i.e., a power tube Q6, a seventh power tube, i.e., a power tube Q7, and an eighth power tube, i.e., a power tube Q8. It is defined that when the power input is input from the primary side bridge circuit to the converter, the converter is in a forward working state, and at this time, after the power input passes through the primary side bridge circuit, the LLC resonant circuit, and the transformer, the corresponding voltage output is obtained through the secondary side bridge circuit. When the power input is input from the secondary bridge circuit to the converter, the converter is in reverse working state. At this time, the power input passes through the secondary bridge circuit, the transformer and the LLC resonant circuit, and obtains the corresponding voltage output through the primary bridge circuit.

[0049] In the specific control process, the working state of the corresponding power tube is driven by the driving signal to achieve the required working voltage output. For example, when the converter is in the reverse working state, the first power tube and the fourth power tube can be driven to work, such as being turned on, by the first driving signal, and the first driving signal is delayed by a certain first phase shift angle to obtain the second driving signal, and the sixth power tube is driven by the second driving signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the first phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1. Similarly, the second power tube and the third power tube can be driven to work, for example, to be turned on, by the third drive signal, and the third drive signal is delayed by a certain second phase shift angle to obtain a fourth drive signal, and the fifth power tube is driven by the fourth drive signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the second phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1.

[0050] In the process of the sixth power tube being driven to work, the eighth power tube can form a driving working state opposite to the sixth power tube, or it can be always in a turned-off state, and the current is continued through the body diode. In the process of the fifth power tube being driven to work, the seventh power tube can form a driving working state opposite to the fifth power tube, or it can be always in a turned-off state, and the current is continued through the body diode.

[0051] Furthermore, the first phase shift angle is the same as the second phase shift angle. In a specific setting, the first phase shift angle and the second phase shift angle can be set to be the same, that is, when the power tube is switched, the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit, and the delay is the same.

[0052] Optionally, the first phase shift angle and the second phase shift angle are both less than 180 degrees. Specifically, when setting the first phase shift angle and the second phase shift angle, the phase angle is less than 180 degrees to avoid the bridge circuit and the secondary bridge circuit from having completely opposite working states.

[0053] In a specific embodiment, if Figure 3As shown, the first phase shift angle and the second phase shift angle are both set to 30 degrees. When the input voltage is 50V and the transformer turns ratio is 6, the final reverse output voltage Vrms≈385V, and the reverse gain is 1.283, which is greater than 1. And when the reverse gain remains unchanged at the frequency, the reverse gain increases with the increase of the phase shift angle. Among them, the horizontal axis is time, I (Lr) is the resonant cavity current, or the current flowing through the resonant inductor Lr, the unit is A. VP1 is the output voltage of the converter when it works in reverse, the unit is V; the two curves located below are respectively a schematic diagram of the relationship between the phase shift of the drive signal of the power tube Q1 and the drive signal of the power tube Q6, and a schematic diagram of the relationship between the phase shift of the drive signal of the power tube Q2 and the drive signal of the power tube Q5. Among them, the drive signal of the power tube Q1 is complementary to the drive signal of the power tube Q2, and the duty cycle is 50%.

[0054] Optionally, the duty ratios of the first drive signal and the third drive signal are both 50%. In specific settings, the duty ratios of the first drive signal and the third drive signal are both 50%, so that the power tube utilization rate is maximized and the basic gain of the converter is improved during operation.

[0055] like Figure 4 As shown, in the embodiment of the bidirectional LLC converter control method of the present invention, it also includes: when the primary bridge circuit is connected to the power input, S3, driving the sixth power tube and the seventh power tube through the fifth drive signal, and generating a sixth drive signal according to the fifth drive signal, so as to drive the first power tube and the fourth power tube through the sixth drive signal; S4, driving the fifth power tube and the eighth power tube through the seventh drive signal, and generating an eighth drive signal according to the seventh drive signal, so as to drive the second power tube and the third power tube through the eighth drive signal; wherein the seventh drive signal is opposite in phase to the fifth drive signal. Specifically, when the converter is in the forward working state, the sixth power tube and the seventh power tube can be driven to work, for example, to be turned on, by the fifth drive signal, and a sixth drive signal can be generated for the fifth drive signal, and the first power tube and the fourth power tube can be driven by the sixth drive signal, so that the working state of the secondary bridge circuit cooperates with the working state of the primary bridge circuit to realize the forward output of the converter. Similarly, the fifth power tube and the eighth power tube can be driven to work, for example, to be turned on, by the seventh drive signal, and at the same time, an eighth drive signal is generated according to the seventh drive signal, and the second power tube and the third power tube are driven by the eighth drive signal, so that the working state of the secondary side bridge circuit cooperates with the working state of the primary side bridge circuit to realize the forward output of the converter.

[0056] Optionally, the fifth drive signal has the same phase as the sixth drive signal, and the seventh drive signal has the same phase as the eighth drive signal. Specifically, by setting the fifth drive signal and the sixth drive signal to have the same phase, the working state of the secondary bridge circuit is the same as the working state of the primary bridge circuit, and similarly, by setting the seventh drive signal and the eighth drive signal to have the same phase, the working state of the secondary bridge circuit is the same as the working state of the primary bridge circuit.

[0057] Optionally, the duty cycles of the fifth driving signal and the seventh driving signal are both 50%, so that the utilization rate of the power tube is maximized and the basic gain of the converter is improved when it is working.

[0058] In addition, in an embodiment of a bidirectional LLC converter control device of the present invention, the control device is used for a bidirectional LLC converter, the bidirectional LLC converter includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit includes a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; the primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube, and an eighth power tube, the fifth power tube and The seventh power tube is connected in series, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are the lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are the upper bridge arms of the primary bridge circuit; the control device is used to drive the first power tube and the fourth power tube through a first drive signal when the secondary bridge circuit is connected to a power input, and delay the first drive signal by a first phase shift angle to generate a second drive signal, so as to drive the sixth power tube through the second drive signal; drive the second power tube and the third power tube through a third drive signal, and delay the third drive signal by a second phase shift angle to generate a fourth drive signal, so as to drive the fifth power tube through the fourth drive signal; wherein the third drive signal is opposite in phase to the first drive signal.

[0059] Specifically, Figure 1As shown, in the bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, i.e., power tube Q1, a second power tube, i.e., power tube Q2, a third power tube, i.e., power tube Q3, and a fourth power tube, i.e., power tube Q4. The primary side of the transformer is connected to the primary side bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include a resonant inductor, i.e., an inductor Lr, and a resonant capacitor, i.e., a capacitor Cr, connected in series, and the primary side bridge circuit is a full-bridge circuit composed of a fifth power tube, i.e., power tube Q5, a sixth power tube, i.e., power tube Q6, a seventh power tube, i.e., power tube Q7, and an eighth power tube, i.e., power tube Q8. It is defined that when the power input is input from the primary side bridge circuit to the converter, the converter is in a forward working state, and at this time, after the power input passes through the primary side bridge circuit, the LLC resonant circuit, and the transformer, the corresponding voltage output is obtained through the secondary side bridge circuit. When the power input is input from the secondary bridge circuit to the converter, the converter is in reverse working state. At this time, the power input passes through the secondary bridge circuit, the transformer and the LLC resonant circuit, and obtains the corresponding voltage output through the primary bridge circuit.

[0060] Among them, the control device is used to control the working process of each power tube in the bidirectional LLC converter. For example, the control device drives the working state of the corresponding power tube through a driving signal to achieve the required working voltage output. For example, when the converter is in the reverse working state, the first power tube and the fourth power tube can be driven to work, such as being turned on, by a first driving signal, and the first driving signal is delayed by a certain first phase shift angle to obtain a second driving signal, and the sixth power tube is driven by the second driving signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the first phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1. Similarly, the second power tube and the third power tube can be driven to work, for example, to be turned on, by the third driving signal, and the third driving signal is delayed by a certain second phase shift angle to obtain a fourth driving signal, and the fifth power tube is driven by the fourth driving signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the first phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1. In the process of the sixth power tube being driven to work, the eighth power tube can form a driving working state opposite to the sixth power tube, or it can be in a turned-off state all the time, and the current is continued through the body diode. In the process of the fifth power tube being driven to work, the seventh power tube can form a driving working state opposite to the fifth power tube, or it can be in a turned-off state all the time, and the current is continued through the body diode.

[0061] Optionally, the control device is also used to drive the sixth power tube and the seventh power tube through a fifth drive signal when the primary bridge circuit is connected to the power input, and generate a sixth drive signal based on the fifth drive signal to drive the first power tube and the fourth power tube through the sixth drive signal; drive the fifth power tube and the eighth power tube through a seventh drive signal, and generate an eighth drive signal based on the seventh drive signal to drive the second power tube and the third power tube through the eighth drive signal; wherein the seventh drive signal is opposite in phase to the fifth drive signal.

[0062] Specifically, when the converter is in the forward working state, the control device can drive the sixth power tube and the seventh power tube to work, for example, to be turned on, through the fifth drive signal, and generate a sixth drive signal for the fifth drive signal, and drive the first power tube and the fourth power tube through the sixth drive signal, so that the working state of the secondary bridge circuit cooperates with the working state of the primary bridge circuit to achieve the forward output of the converter. Similarly, the fifth power tube and the eighth power tube can be driven to work, for example, to be turned on, through the seventh drive signal, and generate an eighth drive signal according to the seventh drive signal, and drive the second power tube and the third power tube through the eighth drive signal, so that the working state of the secondary bridge circuit cooperates with the working state of the primary bridge circuit to achieve the forward output of the converter.

[0063] In an embodiment of a bidirectional LLC converter of the present invention, the converter comprises: a controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit comprises a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; the primary bridge circuit comprises a fifth power tube, a sixth power tube, a seventh power tube, and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, The sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are the lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are the upper bridge arms of the primary bridge circuit; the controller is used to drive the first power tube and the fourth power tube through a first drive signal when the secondary bridge circuit is connected to a power input, and delay the first drive signal by a first phase shift angle to generate a second drive signal, so as to drive the sixth power tube through the second drive signal; drive the second power tube and the third power tube through a third drive signal, and delay the third drive signal by a second phase shift angle to generate a fourth drive signal, so as to drive the fifth power tube through the fourth drive signal; wherein the third drive signal is opposite in phase to the first drive signal.

[0064] Specifically, Figure 1As shown, in the bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, i.e., power tube Q1, a second power tube, i.e., power tube Q2, a third power tube, i.e., power tube Q3, and a fourth power tube, i.e., power tube Q4. The primary side of the transformer is connected to the primary side bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include a resonant inductor, i.e., an inductor Lr, and a resonant capacitor, i.e., a capacitor Cr, connected in series, and the primary side bridge circuit is a full-bridge circuit composed of a fifth power tube, i.e., power tube Q5, a sixth power tube, i.e., power tube Q6, a seventh power tube, i.e., power tube Q7, and an eighth power tube, i.e., power tube Q8. It is defined that when the power input is input from the primary side bridge circuit to the converter, the converter is in a forward working state, and at this time, after the power input passes through the primary side bridge circuit, the LLC resonant circuit, and the transformer, the corresponding voltage output is obtained through the secondary side bridge circuit. When the power input is input from the secondary bridge circuit to the converter, the converter is in reverse working state. At this time, the power input passes through the secondary bridge circuit, the transformer and the LLC resonant circuit, and obtains the corresponding voltage output through the primary bridge circuit.

[0065] The controller is used to control the working process of the converter. In the specific control process, the working state of the corresponding power tube can be driven by the driving signal to achieve the required working voltage output. For example, when the converter is in the reverse working state, the first driving signal can be used to drive the first power tube and the fourth power tube to work, such as to be turned on, and the first driving signal is delayed by a certain first phase shift angle to obtain a second driving signal. The sixth power tube is driven by the second driving signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the first phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1. Similarly, the second power tube and the third power tube can be driven to work, for example, to be turned on, by the third drive signal, and the third drive signal is delayed by a certain second phase shift angle to obtain a fourth drive signal, and the fifth power tube is driven by the fourth drive signal, so that the working state of the primary bridge circuit is equivalent to the working state of the secondary bridge circuit with a preset delay, so that the resonant inductor and the resonant capacitor store energy to increase the output voltage of the primary bridge circuit, that is, to increase the reverse output gain of the converter. In one embodiment, the second phase shift angle can be reasonably set so that the reverse output gain of the converter is greater than 1.

[0066] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A bidirectional LLC converter control method, characterized in that: The bidirectional LLC converter includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit; The control method comprises: When the secondary bridge circuit is connected to the power input, driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal; driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal; The third driving signal has a phase opposite to that of the first driving signal.

2. The bidirectional LLC converter control method according to claim 1, characterized in that: The first phase shift angle is the same as the second phase shift angle.

3. The bidirectional LLC converter control method according to claim 1, characterized in that: The first phase shift angle and the second phase shift angle are both smaller than 180 degrees.

4. The bidirectional LLC converter control method according to claim 1, characterized in that: The duty cycles of the first driving signal and the third driving signal are both 50%.

5. The bidirectional LLC converter control method according to claim 1, characterized in that: The control method further comprises: When the primary bridge circuit is connected to the power input, driving the sixth power tube and the seventh power tube by a fifth driving signal, and generating a sixth driving signal according to the fifth driving signal, so as to drive the first power tube and the fourth power tube by the sixth driving signal; driving the fifth power tube and the eighth power tube by a seventh driving signal, and generating an eighth driving signal according to the seventh driving signal, so as to drive the second power tube and the third power tube by the eighth driving signal; The seventh driving signal has a phase opposite to that of the fifth driving signal.

6. The bidirectional LLC converter control method according to claim 5, characterized in that: The fifth driving signal has the same phase as the sixth driving signal, and the seventh driving signal has the same phase as the eighth driving signal.

7. The bidirectional LLC converter control method according to claim 1, characterized in that: The duty cycles of the fifth driving signal and the seventh driving signal are both 50%.

8. A bidirectional LLC converter control device, characterized in that: For a bidirectional LLC converter, the bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit; The control device is used for connecting the secondary bridge circuit to the power input. driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal; driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal; The third driving signal has a phase opposite to that of the first driving signal.

9. The bidirectional LLC converter control device according to claim 8, characterized in that: The control device is also used for, when the primary bridge circuit is connected to the power input, driving the sixth power tube and the seventh power tube by a fifth driving signal, and generating a sixth driving signal according to the fifth driving signal, so as to drive the first power tube and the fourth power tube by the sixth driving signal; driving the fifth power tube and the eighth power tube by a seventh driving signal, and generating an eighth driving signal according to the seventh driving signal, so as to drive the second power tube and the third power tube by the eighth driving signal; The seventh driving signal has a phase opposite to that of the fifth driving signal.

10. A bidirectional LLC converter, characterized in that: include: A controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary bridge circuit includes a fifth power tube, a sixth power tube, a seventh power tube and an eighth power tube, the fifth power tube is connected in series with the seventh power tube, the sixth power tube is connected in series with the eighth power tube, and the fifth power tube and the sixth power tube are lower bridge arms of the primary bridge circuit, and the seventh power tube and the eighth power tube are upper bridge arms of the primary bridge circuit; The controller is used for connecting the secondary bridge circuit to the power input. driving the first power tube and the fourth power tube by a first driving signal, and delaying the first driving signal by a first phase shift angle to generate a second driving signal, so as to drive the sixth power tube by the second driving signal; driving the second power tube and the third power tube by a third driving signal, and delaying the third driving signal by a second phase shift angle to generate a fourth driving signal, so as to drive the fifth power tube by the fourth driving signal; The third driving signal has a phase opposite to that of the first driving signal.

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