A method for suppressing common-mode voltage of a three-level dual active bridge converter

Abstract

The invention discloses a common-mode voltage suppression method for a three-level dual-active bridge converter, comprising: replacing a single-side phase-shift inductor in a three-level dual-active bridge converter with a symmetrically coupled phase-shift inductor; controlling d1, d2, and d5 so that the intermediate node voltages of the upper and lower half-bridge arms of the A bridge arm and the B bridge arm of the primary full bridge cancel each other, and the output node voltages of the A bridge arm and the B bridge arm cancel each other; controlling d3, d4, and d6 so that the intermediate node voltages of the upper and lower half-bridge arms of the C bridge arm and the D bridge arm of the secondary full bridge cancel each other, and the output node voltages of the C bridge arm and the D bridge arm cancel each other; the phase-shift duty ratios of the driving signals between the inner and outer switch tubes of each bridge arm are d1, d2, d3, and d4 respectively; the phase-shift duty ratios between the two bridge arms of each side full bridge are d5 and d6 respectively; and the phase-shift duty ratio between the primary full bridge and the secondary full bridge is d7, which is a non-zero value. The invention can suppress the common-mode voltage of the three-level dual-active bridge converter to be zero.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics, and more specifically, relates to a common-mode voltage suppression method for a three-level dual-active bridge converter. Background Art

[0002] The three-level dual-active-bridge (DAB) converter consists of two three-level active full-bridge circuits connected via a phase-shifting inductor and a high-frequency transformer. It has the advantages of bidirectional power transmission, electrical isolation, voltage matching, and flexible control. It has been widely used as the main interconnection component in medium-voltage distributed power generation systems, smart grids, electric vehicles, and energy storage systems.

[0003] However, since the power devices in the three-level DAB converter are in a high-frequency switching state, the continuous switching action will inevitably emit conducted electromagnetic interference. For the three-level DAB converter, the high-frequency switching node voltage jump in the circuit and the resulting voltage jump of the phase-shift inductor will excite the overall common-mode voltage, and generate common-mode current through stray capacitance, causing obvious common-mode conducted interference, affecting surrounding equipment, and threatening the safety of electronic information and power systems. In order to ensure the safe and stable operation of the converter system, the common-mode voltage of the three-level DAB converter must be suppressed. The mainstream suppression method is to add a common-mode filter to the converter, but the addition of additional filter hardware will greatly increase the overall cost and volume weight of the three-level DAB converter. Therefore, economically and effectively suppressing the common-mode voltage without adding additional hardware is of great significance to the cost, power density and safety reliability of the three-level DAB converter. Summary of the invention

[0004] In view of the defects and improvement needs of the prior art, the present invention provides a common-mode voltage suppression method for a three-level dual active bridge converter, the purpose of which is to effectively suppress the common-mode voltage of the three-level dual active bridge converter without adding additional hardware.

[0005] To achieve the above object, according to one aspect of the present invention, a common mode voltage suppression method for a three-level dual active bridge converter is provided, comprising:

[0006] A symmetrically coupled phase-shifting inductor is used to replace the single-side phase-shifting inductor located between the two three-level active full-bridge circuits on the original secondary side in the three-level dual active bridge converter, so as to eliminate the excitation of the inductor voltage on the common mode voltage.

[0007] The common-mode voltage cancellation modulation control d1, d2, and d5 of the switch node make the intermediate node voltage of the upper and lower half bridge arms in the A bridge arm and the intermediate node voltage of the upper and lower half bridge arms in the B bridge arm cancel each other, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm cancel each other, so as to eliminate the excitation of the common-mode voltage by the node voltage of the primary full bridge; and control d3, d4, and d6 so that the intermediate node voltage of the upper and lower half bridge arms in the C bridge arm and the intermediate node voltage of the upper and lower half bridge arms in the D bridge arm cancel each other, and the node voltage at the output end of the C bridge arm and the node voltage at the output end of the D bridge arm cancel each other. The voltages of the nodes of the secondary full bridge cancel each other, thereby eliminating the excitation of the common mode voltage by the voltage of each node of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0008] Furthermore, d1, d2, and d5 satisfy: d1=d2, d5=0; and d3, d4, and d6 satisfy: d3=d4, d6=0.

[0009] Furthermore, the same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

[0010] The present invention also provides a three-level dual active bridge converter common mode voltage suppression system, comprising: a three-level dual active bridge converter and a controller;

[0011] The phase-shift inductor located between the two three-level active full-bridge circuits on the primary and secondary sides in the three-level dual active bridge converter is a symmetrically coupled phase-shift inductor, so as to eliminate the excitation of the common mode voltage by the inductor voltage;

[0012] The controller is used for, when the three-level dual active bridge converter is working, the switch node common mode voltage cancellation modulation module controls d1, d2, and d5, so that the intermediate node voltages of the upper and lower half bridge arms in the A bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the B bridge arm are mutually cancelled, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm are mutually cancelled, so as to eliminate the excitation of the common mode voltage by the node voltages of the primary full bridge; and controls d3, d4, and d6, so that the intermediate node voltages of the upper and lower half bridge arms in the C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the D bridge arm are mutually cancelled, and the node voltage at the output end of the C bridge arm is mutually cancelled. The voltage and the node voltage at the output end of the D bridge arm cancel each other, thereby eliminating the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0013] Furthermore, d1, d2, and d5 satisfy: d1=d2, d5=0; and d3, d4, and d6 satisfy: d3=d4, d6=0.

[0014] Furthermore, the same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

[0015] The present invention also provides a three-level dual active bridge converter, wherein the phase-shifting inductor located between the two three-level active full-bridge circuits on the primary and secondary sides is a symmetrically coupled phase-shifting inductor, the same-name ends of the windings on both sides of the symmetrically coupled phase-shifting inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

[0016] The present invention also provides a controller for controlling the three-level dual active bridge converter as described above. When the three-level dual active bridge converter is working, the switch node common mode voltage cancellation modulation module controls d1, d2, and d5, so that the intermediate node voltages of the upper and lower half bridge arms in the A bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the B bridge arm cancel each other, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm cancel each other, so as to eliminate the excitation of the common mode voltage by the node voltages of the primary full bridge; and controls d3, d4, and d6, so that the intermediate node voltages of the upper and lower half bridge arms in the C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the D bridge arm are mutually cancelled. Mutual cancellation, and mutual cancellation of the node voltage at the output end of the C bridge arm and the node voltage at the output end of the D bridge arm, to achieve the elimination of the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, and the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0017] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0018] (1) The present invention eliminates the excitation of the common-mode voltage of the three-level dual active bridge converter by the inductor voltage through symmetrically coupled phase-shifted inductors, and realizes the mutual cancellation of the voltage jumps of each switch node through the common-mode voltage cancellation modulation of the switch nodes, thereby eliminating the excitation of the common-mode voltage by the switch node voltage, and effectively suppressing the common-mode voltage of the three-level dual active bridge converter without adding additional hardware.

[0019] (2) The present invention proposes a symmetrically coupled phase-shifted inductor core with the same-name ends of the windings on both sides in opposite directions, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph ; The mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph ; Replace the original inductance value L by symmetrically coupled phase-shifting inductance ph The unilateral phase-shifting inductor eliminates the excitation of the inductor voltage on the common-mode voltage based on the symmetrical structure of the symmetrically coupled phase-shifting inductor, and does not affect the function of the phase-shifting inductor in the three-level active bridge converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of an existing conventional three-level dual active bridge converter provided by an embodiment of the present invention;

[0021] Figure 2Schematic diagram of a three-level dual active bridge converter with symmetrically coupled phase-shifted inductors and switch node common-mode voltage cancellation modulation provided by an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the relationship between 7 phase-shift duty ratios and driving signals of each switch tube provided in an embodiment of the present invention;

[0023] Figure 4 is a schematic diagram of the common mode voltage of a conventional three-level dual active bridge under conventional phase-shift modulation provided by an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of inductor voltage cancellation of symmetrically coupled phase-shifted inductors provided in an embodiment of the present invention;

[0025] Figure 6 Schematic diagram of voltage cancellation of each switch node of the primary three-level full bridge provided by an embodiment of the present invention;

[0026] Figure 7 Schematic diagram of voltage cancellation of each switch node of the secondary three-level full bridge provided by an embodiment of the present invention;

[0027] Figure 8 It is a common-mode voltage schematic diagram of a common-mode voltage suppression method for a three-level dual active bridge converter provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Before describing the implementation in detail, the topology of the three-level dual active bridge converter is briefly described first. Figure 1 The figure shows the conventional three-level dual active bridge converter, which consists of a single-side phase-shift inductor L ph The primary three-level full bridge-1 and the secondary three-level full bridge-2 connected to the high-frequency isolation transformer T are composed. Each bridge arm contains 4 switch tubes (S x1 -S x4 , x=a,b,c,d), 2 clamping diodes (such as D c1 and D c2 ) and a flying capacitor (e.g. C ss1 ), where A and B are the midpoints of the primary bridge arm, and C and D are the midpoints of the secondary bridge arm. V1 and V2 represent the DC bus voltages of the primary and secondary sides, and O1 and O2 are the DC voltage divider capacitors (C11 and C 12 , C 21 and C 22 )’s midpoint.

[0030] Embodiment 1

[0031] A common mode voltage suppression method for a three-level dual active bridge converter, such as Figure 2 As shown, including:

[0032] A symmetrically coupled phase-shifting inductor is used to replace the single-side phase-shifting inductor located between the two three-level active full-bridge circuits on the original secondary side in the three-level dual active bridge converter, so as to eliminate the excitation of the inductor voltage on the common mode voltage.

[0033] The common-mode voltage cancellation modulation control d1, d2, and d5 of the switch node make the intermediate node voltage of the upper and lower half bridge arms in the A bridge arm cancel each other with the intermediate node voltage of the upper and lower half bridge arms in the B bridge arm, and the node voltage at the output end of the A bridge arm cancels each other with the node voltage at the output end of the B bridge arm, so as to eliminate the excitation of the common-mode voltage by the node voltage of each primary full bridge; and control d3, d4, and d6 so that the intermediate node voltage of the upper and lower half bridge arms in the C bridge arm cancels each other with the intermediate node voltage of the upper and lower half bridge arms in the D bridge arm, and the node voltage at the output end of the C bridge arm cancels each other with the node voltage at the output end of the D bridge arm. The voltages cancel each other to eliminate the excitation of the common-mode voltage by the voltages of the nodes of the secondary full bridge; wherein, the phase-shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase-shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase-shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase-shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0034] The same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L. ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

[0035] The relationship between the 7 phase shift duty ratios and the drive signals of each switch tube is as follows: Figure 3 As shown in Figure 1, all driving signals are 50% duty cycle pulses. The two outer switch tubes (S x1 and S x4 , x=a,b,c,d) are complementary turned on, and the two inner switches (S x2 and S x3 , x=a,b,c,d) are complementary conduction, Indicates S x4 The signal is inverted, so With S x1 The phase shift time between the driving signals of the internal and external switch tubes of bridge arm A is d1T hs (T hs is half of the switching cycle), and the other three bridge arms are d2T hs ,d3T hs and d4T hs The phase shift time between the two bridge arms of the primary full bridge is d5T hs , and the phase shift time between the bridge arms of the secondary side is d6T hs The phase shift time of the driving signal between the full bridges on both sides is d7T hs .

[0036] Combination Figure 2 As shown, the common-mode voltage cancellation modulation control of the switch node d1, d2, and d5 three phase shift duty ratios makes the intermediate node voltage V A1 and V A3 The voltage V between the middle nodes of the upper and lower bridge arms in the B bridge arm B1 and V B3 cancel each other, and the A bridge arm output node voltage V A2 and the node voltage V at the output end of the bridge arm B B2 The mutual cancellation can eliminate the excitation of the common mode voltage by the node voltage of the primary full bridge; the three phase shift duty ratios of d3, d4, and d6 are controlled so that the intermediate node voltage V C1 and V C3 The voltage V between the middle nodes of the upper and lower half bridge arms of the D bridge arm D1 and V D3 cancel each other, and the C bridge arm output node voltage V C2 The voltage V D2 The mutual cancellation can eliminate the excitation of the common mode voltage by the node voltage of the secondary full bridge.

[0037] The common-mode voltage suppression method of the three-level dual-active bridge converter provided in this embodiment uses a symmetrically coupled phase-shifting inductor to replace the single-sided phase-shifting inductor located between the two three-level active full-bridge circuits on the primary and secondary sides in the three-level dual-active bridge converter, which can eliminate the influence of the phase-shifting inductor voltage on the overall common-mode voltage of the three-level active bridge converter, and partially suppress the common-mode voltage. In addition, the switch node common-mode voltage cancellation modulation controls each phase-shift duty cycle, which can eliminate the influence of each switch node voltage that jumps over time on the common-mode voltage, and further suppress the common-mode voltage. The common-mode voltage suppression method of the three-level dual-active bridge converter provided in this embodiment only requires very small hardware changes, and is combined with the switch node common-mode voltage cancellation modulation to achieve common-mode voltage suppression of zero. Compared with traditional common-mode filters and other means, it does not increase the system volume and is more economical and effective.

[0038] As a preferred implementation, d1, d2, and d5 satisfy: d1=d2, d5=0; d3, d4, and d6 satisfy: d3=d4, d6=0.

[0039] Control the three phase shift duty ratios of the primary full bridge d1, d2, and d5 to satisfy d1 = d2, d5 = 0. At this time, V A2 With V B2 , voltage jumps occur at the same time, but the two jumps are in opposite phases, so the two add up to cancel each other out, presenting a constant voltage state; V A1 With V B3 , V A3 With V B1 The four voltages jump at the same time, but the sum of the four remains constant. The three phase shift duty ratios of the secondary full bridge d3, d4, and d6 satisfy d3 = d4, d6 = 0. At this time, V C2 With V D2 , voltage jumps occur at the same time, but the two jumps are in opposite phases, so the two add up to cancel each other out, presenting a constant voltage state; V C1 With V D3 , V C3 With V D1 The four voltages jump at the same time, but the sum of the four remains constant.

[0040] In addition, it is also necessary to pay attention to controlling the phase shift duty cycle d1-d4 and d7≠0 to achieve power transmission of the three-level dual active bridge converter.

[0041] An example, Figure 3-Figure 8 The operating conditions of the corresponding scheme are as follows: the primary DC bus voltage is 250V, the secondary DC bus voltage is 160V, the switching frequency is 10kHz, and the converter output power is 1kW. Figure 1 The conventional three-level dual active bridge converter shown in FIG. Figure 2 The common-mode voltage suppression method of the three-level dual active bridge converter shown in the figure is verified by simulation experiments.

[0042] The common-mode voltage of the three-level dual active bridge converter under the traditional method and circuit structure is as follows: Figure 4 As shown, it can be observed that obvious common-mode voltage spikes change with time; using the common-mode voltage suppression method provided in this embodiment, the primary side voltage and the secondary side voltage of the symmetrically coupled phase-shifted inductor are canceled as shown in FIG. Figure 5 As shown in the figure, it can be noticed that due to the symmetrical inductor structure, the excitation of the inductor voltage in the common-mode loop cancels each other, eliminating the influence on the common-mode voltage. The voltage waveforms and cancellation effects of each switch node of the primary and secondary three-level full bridge under the control of the common-mode voltage cancellation modulation of the switch node are shown in the figure. Figure 6 , Figure 7 As shown, it can be noted that the sum of the intermediate node voltages of the upper and lower half bridge arms in the A and B bridge arms of the primary full bridge (V A1 +V A3 +V B1 +V B3 ) and the sum of the output node voltage (V A2 +V B2 ) are constant quantities that do not change with time. The sum of the intermediate node voltages of the upper and lower half bridge arms in the secondary full bridge C and D bridge arms (V C1 +V C3 +V D1 +V D3 ) and the sum of the output node voltage (V C2 +V D2 ) are constant quantities that do not change with time, and the DC quantity contained in the voltage will not cause common-mode voltage. The common-mode voltage of the three-level dual active bridge converter under the common-mode voltage suppression method provided in this embodiment is as follows Figure 8 As shown, the common mode voltage is zero, which effectively and significantly suppresses the common mode voltage.

[0043] Embodiment 2

[0044] A three-level dual-active bridge converter common-mode voltage suppression system comprises: a three-level dual-active bridge converter and a controller; wherein the phase-shift inductor located between two three-level active full-bridge circuits on the primary and secondary sides in the three-level dual-active bridge converter is a symmetrically coupled phase-shift inductor, so as to eliminate the excitation of the inductor voltage on the common-mode voltage; the controller is used for controlling d1, d2, and d5 of a switch node common-mode voltage cancellation modulation module when the three-level dual-active bridge converter is working, so that the intermediate node voltages of the upper and lower half-bridge arms in the A bridge arm and the intermediate node voltages of the upper and lower half-bridge arms in the B bridge arm are mutually cancelled, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm are mutually cancelled, so as to eliminate the excitation of the common-mode voltage by the node voltages of the primary full-bridge; and controlling d3, d4, and d6 so that The intermediate node voltages of the upper and lower half bridge arms in the C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the D bridge arm cancel each other, and the node voltages at the output end of the C bridge arm and the node voltages at the output end of the D bridge arm cancel each other, thereby eliminating the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, and the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0045] As a preferred implementation, d1, d2, and d5 satisfy: d1=d2, d5=0; d3, d4, and d6 satisfy: d3=d4, d6=0.

[0046] As a preferred implementation, the same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

[0047] The relevant technical solution is the same as that in Embodiment 1 and will not be described in detail here.

[0048] Embodiment 3

[0049] A three-level dual active bridge converter, wherein the phase-shifting inductor located between the two three-level active full-bridge circuits on the primary and secondary sides is a symmetrically coupled phase-shifting inductor, the same-name ends of the windings on both sides of the symmetrically coupled phase-shifting inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L phis the inductance value of the unilateral phase-shift inductor.

[0050] The relevant technical solution is the same as that in Embodiment 1 and will not be described in detail here.

[0051] Embodiment 4

[0052] A controller for controlling the three-level dual active bridge converter as described above, when the three-level dual active bridge converter is working, the switch node common mode voltage cancellation modulation module controls d1, d2, and d5, so that the intermediate node voltages of the upper and lower half bridge arms in the A bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the B bridge arm cancel each other, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm cancel each other, so as to eliminate the excitation of the common mode voltage by the node voltages of the primary full bridge; and controls d3, d4, and d6, so that the intermediate node voltages of the upper and lower half bridge arms in the C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the D bridge arm cancel each other. , and the node voltage at the output end of the C bridge arm and the node voltage at the output end of the D bridge arm cancel each other, thereby eliminating the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, and the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

[0053] The relevant technical solution is the same as that in Embodiment 1 and will not be described in detail here.

[0054] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A common mode voltage suppression method for a three-level dual active bridge converter, characterized in that: include: A symmetrically coupled phase-shifting inductor is used to replace the single-side phase-shifting inductor located between the two three-level active full-bridge circuits on the original secondary side in the three-level dual active bridge converter, so as to eliminate the excitation of the inductor voltage on the common mode voltage. The common-mode voltage cancellation modulation control d1, d2, and d5 of the switch node are used to cancel the intermediate node voltages of the upper and lower half-bridge arms in the primary A bridge arm and the intermediate node voltages of the upper and lower half-bridge arms in the primary B bridge arm, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm are canceled, so as to eliminate the excitation of the common-mode voltage by the node voltages of the primary full bridge; and d3, d4, and d6 are controlled to cancel the intermediate node voltages of the upper and lower half-bridge arms in the secondary C bridge arm and the intermediate node voltages of the upper and lower half-bridge arms in the secondary D bridge arm, and the node voltage at the output end of the C bridge arm and the node voltage at the output end of the D bridge arm. The node voltages cancel each other to eliminate the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

2. A common mode voltage suppression method for a three-level dual active bridge converter according to claim 1, characterized in that: d1, d2, d5 satisfy: d1=d2, d5=0; d3, d4, d6 satisfy: d3=d4, d6=0.

3. The common mode voltage suppression method of a three-level dual active bridge converter according to claim 1, characterized in that: The same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

4. A three-level dual active bridge converter common mode voltage suppression system, characterized in that: include: Three-level dual active bridge converter and controller; The phase-shift inductor located between the two three-level active full-bridge circuits on the primary and secondary sides in the three-level dual active bridge converter is a symmetrically coupled phase-shift inductor, so as to eliminate the excitation of the common-mode voltage by the inductor voltage; The controller is used for, when the three-level dual active bridge converter is working, the switch node common mode voltage cancellation modulation module controls d1, d2, and d5, so that the intermediate node voltages of the upper and lower half bridge arms in the primary side A bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the primary side B bridge arm are mutually cancelled, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm are mutually cancelled, so as to eliminate the excitation of the common mode voltage by the node voltages of the primary full bridge; and controls d3, d4, and d6, so that the intermediate node voltages of the upper and lower half bridge arms in the secondary side C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the secondary side D bridge arm are mutually cancelled, and the C bridge arm output The terminal node voltage and the D bridge arm output terminal node voltage cancel each other, thereby eliminating the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

5. A three-level dual active bridge converter common mode voltage suppression system according to claim 4, characterized in that: d1, d2, d5 satisfy: d1=d2, d5=0; d3, d4, d6 satisfy: d3=d4, d6=0.

6. A three-level dual active bridge converter common mode voltage suppression system according to claim 4, characterized in that: The same-name ends of the windings on both sides of the symmetrically coupled phase-shifted inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shift inductor.

7. A controller for controlling a three-level dual active bridge converter, characterized in that: The phase-shift inductor located between the two three-level active full-bridge circuits on the primary and secondary sides in the three-level dual active bridge converter is a symmetrically coupled phase-shift inductor. The same-name ends of the windings on both sides of the symmetrically coupled phase-shift inductor core are opposite, and the self-inductance of the windings on both sides is equal, and the inductance value is equal to 0.25L. ph , the mutual inductance between the windings on both sides of the symmetrically coupled phase-shift inductor is equal to 0.25L ph , L ph is the inductance value of the unilateral phase-shifting inductor; When the three-level dual active bridge converter is working, the switch node common mode voltage cancellation modulation module controls d1, d2, and d5, so that the intermediate node voltages of the upper and lower half bridge arms in the primary side A bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the B bridge arm cancel each other, and the node voltage at the output end of the A bridge arm and the node voltage at the output end of the B bridge arm cancel each other, so as to eliminate the excitation of the common mode voltage by the node voltages of the primary full bridge; and controls d3, d4, and d6, so that the intermediate node voltages of the upper and lower half bridge arms in the secondary side C bridge arm and the intermediate node voltages of the upper and lower half bridge arms in the secondary side D bridge arm cancel each other, and the node voltage at the output end of the C bridge arm The voltage and the node voltage at the output end of the D bridge arm cancel each other, thereby eliminating the excitation of the common mode voltage by the node voltages of the secondary full bridge; wherein, the phase shift duty ratios of the drive signals between the inner and outer switch tubes of each bridge arm in the three-level dual active bridge converter are d1, d2, d3 and d4 respectively; the phase shift duty ratio between the two bridge arms A and B of the primary side is d5, the phase shift duty ratio between the two bridge arms C and D of the secondary side is d6; and the phase shift duty ratio between the primary full bridge and the secondary full bridge is d7; the value of d7 is not 0, and the values ​​of d1, d2, d3, d4 and d7 ensure that the three-level dual active bridge converter realizes power transmission.

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