DC / DC converter for high efficiency conversion

Abstract

Examples of the present disclosure include a DC / DC converter including an input configured to be coupled to a DC power source, a sparse active neutral point clamped converter (SANPC) coupled to the input, a plurality of transformers coupled to the SANPC, and a controller coupled to the plurality of transformers. The plurality of transformers includes a first transformer and a second transformer, a first AC / DC converter coupled to the first transformer, a second AC / DC converter coupled to the second transformer, and at least one output coupled to the first AC / DC converter and the second AC / DC converter and configured to provide DC output power to one or more loads.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Serial No. 63 / 557,678, filed on February 26, 2024, entitled “DC / DC CONVERTER FOR HIGH-EFFICIENCY CONVERSION,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] At least one example according to the present disclosure generally relates to power converters. Background Art

[0004] Power devices such as power converters can be used to provide power to one or more loads. A power converter can convert power from one form (e.g., AC power) to another form (e.g., DC power). A power converter can also modify the parameters of the converted power, such as by increasing or decreasing the voltage level of the converted power. Summary of the Invention

[0005] The examples of the methods and systems discussed herein are not limited in application to the details of construction and component arrangement set forth in the following description or shown in the accompanying drawings. These methods and systems can be implemented in other embodiments and can be practiced or executed in various ways. The examples of specific implementations provided herein are for illustrative purposes only and are not intended to be limiting. The actions, components, elements, and features discussed in conjunction with any one or more examples can be configured to operate and / or be implemented in similar roles in any other examples.

[0006] The wording and terminology used herein are for descriptive purposes. The examples, embodiments, parts, elements or actions of the systems and methods mentioned herein in the singular may also encompass embodiments comprising a plurality. Similarly, plural references to embodiments, parts, elements or actions may be implemented as singular. Therefore, references in the singular or plural form are not intended to limit the currently disclosed systems or methods, their components, actions or elements. "Include," "comprise," "contain," "have," "contain," "involve," and variations used herein may encompass projects and their equivalents and additional projects listed thereafter.

[0007] References to "or" should be interpreted as inclusive, such that any term described using "or" can refer to any of the described terms individually, more than one, and all of them. For example, the phrase "at least one of A or B" can refer to A and / or B, i.e., only A, only B, or both. Furthermore, if there is any inconsistency in the usage of a term between this document and a document incorporated by reference, the usage of the term in the incorporated document supplements that of this document. For irreconcilable differences, the usage of the term in this document controls.

[0008] According to at least one aspect of the present disclosure, a DC / DC converter is provided, comprising: an input configured to be coupled to a DC power source, a sparse active neutral point clamped converter (SANPC) coupled to the input, a plurality of transformers coupled to the SANPC, the plurality of transformers including a first transformer and a second transformer, a first AC / DC converter coupled to the first transformer, a second AC / DC converter coupled to the second transformer, and at least one output coupled to the first AC / DC converter and the second AC / DC converter and configured to provide DC output power to one or more loads.

[0009] In at least one example, at least one output includes three output connections. In at least one example, the three output connections are configured to couple to one or more loads in a bipolar configuration. In at least one example, the one or more loads include at least one load coupled to each of the three output connections in a bipolar configuration. In at least one example, the three output connections are configured to couple to the one or more loads in a symmetrical monopolar configuration. In at least one example, a first set of two of the three output connections are configured to couple to a first load in a symmetrical monopolar configuration, and a second set of two of the three output connections are configured to couple to a second load in a symmetrical monopolar configuration.

[0010] In at least one example, a converter includes at least one controller, wherein the SANPC includes a plurality of switches, and wherein the at least one controller is configured to operate at least one of the plurality of switches with zero current switching. In at least one example, the plurality of switches includes a first group of one or more switches and a second group of one or more switches, and wherein the at least one controller is configured to operate the first group of one or more switches with zero current switching and not operate the second group of one or more switches with zero current switching. In at least one example, the switches of the first group of one or more switches have a first rated voltage, and the switches of the second group of one or more switches have a second rated voltage, and wherein the first rated voltage is greater than the second rated voltage.

[0011] In at least one example, the converter includes a positive input bus and a negative input bus coupled to the input, wherein the SANPC includes an intermediate positive bus, an intermediate negative bus, and a reference node, and wherein the second set of one or more switches includes: a first switch coupled between the positive input bus and the intermediate positive bus, a second switch coupled between the negative input bus and the intermediate negative bus, a third switch coupled between the intermediate positive bus and the reference node, and a fourth switch coupled between the intermediate negative bus and the reference node.

[0012] In at least one example, the first set of one or more switches includes: a fifth switch coupled between the intermediate positive bus and the plurality of transformers; a sixth switch coupled between the plurality of transformers and the intermediate negative bus; a seventh switch coupled between the intermediate positive bus and the plurality of transformers; and an eighth switch coupled between the plurality of transformers and the intermediate negative bus. In at least one example, the fifth and sixth switches are coupled to the primary winding of the first transformer, and the seventh and eighth switches are coupled to the primary winding of the second transformer.

[0013] In at least one example, at least one controller is configured to: operate the fifth switch and the seventh switch only in a complementary state, and to operate the sixth switch and the eighth switch only in a complementary state. In at least one example, the converter includes a positive input bus and a negative input bus coupled to the input, wherein the SANPC includes: an intermediate positive bus, an intermediate negative bus, a reference node, a first switch coupled between the positive input bus and the intermediate positive bus, a second switch coupled between the negative input bus and the intermediate negative bus, a third switch coupled between the intermediate positive bus and the reference node, and a fourth switch coupled between the intermediate negative bus and the reference node.

[0014] In at least one example, the SANPC further includes: a fifth switch coupled between the intermediate positive bus and the plurality of transformers; a sixth switch coupled between the plurality of transformers and the intermediate negative bus; a seventh switch coupled between the intermediate positive bus and the plurality of transformers; and an eighth switch coupled between the plurality of transformers and the intermediate negative bus. In at least one example, the fifth and sixth switches are coupled to the primary winding of the first transformer, and the seventh and eighth switches are coupled to the primary winding of the second transformer. In at least one example, the at least one controller is configured to operate the fifth and seventh switches only in a complementary state, and to operate the sixth and eighth switches only in a complementary state.

[0015] In at least one example, a converter includes at least one controller, wherein the SANPC includes: a first switch coupled to an input, a second switch coupled to the first switch and a plurality of transformers, and a third switch coupled to the first switch and the plurality of transformers, and wherein the at least one controller is configured to operate the second switch and the third switch only in a complementary state such that current passing through the first switch passes through the second switch or the third switch. In at least one example, the SANPC includes: a fourth switch coupled to the input, a fifth switch coupled to the fourth switch and the second switch, and a sixth switch coupled to the fourth switch and the third switch, and wherein the at least one controller is further configured to operate the fifth switch and the sixth switch only in a complementary state such that current passing through the fourth switch passes through the fifth switch or the sixth switch.

[0016] According to at least one example, at least one non-transitory computer-readable medium having stored thereon a sequence of computer-executable instructions for operating a DC / DC converter having a sparse active neutral point clamped converter (SANPC), a plurality of transformers coupled to the SANPC, and a plurality of AC / DC converters coupled to the plurality of transformers is provided, the sequence of computer-executable instructions including instructions instructing at least one processor to: operate a first switch and a second switch of the SANPC with zero current switching, operate a third switch of the SANPC without zero current switching, the third switch being coupled to the first switch and the second switch, and operate the first switch and the second switch in complementary states such that a current passing through the third switch passes through the first switch or the second switch.

[0017] According to at least one example, a method of operating a DC / DC converter having a sparse active neutral point clamped converter (SANPC), a plurality of transformers coupled to the SANPC, and a plurality of AC / DC converters coupled to the plurality of transformers is provided, the method comprising operating a first switch and a second switch of the SANPC with zero current switching, operating a third switch of the SANPC without zero current switching, the third switch coupled to the first switch and the second switch, and operating the first switch and the second switch in complementary states such that a current passing through the third switch passes through the first switch or the second switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which may not be drawn to scale. The accompanying drawings are included to provide illustration and a further understanding of the various aspects and embodiments and are incorporated into and constitute a part of the specification, but are not intended as a definition of the limits of any particular embodiment. The accompanying drawings, together with the rest of the specification, serve to explain the principles and operation of the described and claimed aspects and embodiments. In the drawings, each identical or substantially similar component shown in various figures may be represented by the same numeral. For clarity, not every component is labeled in every figure. In the drawings:

[0019] Figure 1 shows a block diagram of a power system according to an example;

[0020] Figure 2 shows a schematic diagram of a power system according to an example;

[0021] Figure 3 a diagram illustrating switching states of a power converter according to an example; and

[0022] Figure 4 According to an example, the Figure 3 a schematic diagram of a power converter indicating example switching states; and

[0023] Figure 5 A set of graphs describing the operation of a power converter according to an example is shown. DETAILED DESCRIPTION

[0024] As mentioned above, a power converter can provide power to one or more loads. For example, a DC / DC power converter can receive DC power, convert the DC power, and provide the converted DC power to one or more loads. However, different DC / DC converters can have different output configurations depending on the requirements of the one or more loads.

[0025] For example, one output configuration includes a symmetrical unipolar configuration, while another output configuration includes a bipolar configuration. In a symmetrical unipolar configuration, the power converter has two output connections to the load: a positive connection and a negative connection. In a bipolar configuration, the power converter has three output connections to the load: a positive connection, a neutral connection, and a negative connection. A unipolar power converter provides a single output at full voltage, while a bipolar power converter provides two outputs at half the full voltage.

[0026] Different loads may be better suited to different power module configurations. For example, a symmetrical unipolar configuration may be more suitable for electric vehicle (EV) charging stations, among other types of loads. A bipolar configuration may be more suitable for information technology (IT) loads in data centers. It may be advantageous to provide a power converter that can operate in both a symmetrical unipolar configuration and a bipolar configuration. Such a power converter can be used to power more types of loads (e.g., EV charging stations and IT loads, rather than one or the other), and therefore may be more useful than a power converter that can only operate in one configuration.

[0027] Examples of the present disclosure include power converters that can accommodate loads compatible with bipolar or symmetrical unipolar configurations. The example power converter can power any number of loads, each of which can operate at a different voltage level. In addition, efficiency can be improved by implementing an efficient switching scheme with switches of different voltage ratings. Higher-rated switches can only switch at zero current. Lower-rated switches can switch at currents greater than zero, but the current is kept at a minimum level by prohibiting switching states that would result in higher currents. Thus, examples of the present disclosure provide flexible and efficient power converters.

[0028] Figure 1 A block diagram of a power converter 100 according to an example is shown. Converter 100 can be a DC / DC power converter. Power converter 100 includes an input 102, a positive output connection 104, a first neutral output connection 106a and a second neutral output connection 106b (collectively referred to as neutral output connection 106), a negative output connection 108, a primary side converter 110, any number of at least two transformers 112 ("transformers 112"), and any number of at least two secondary side converters 114. In various examples, the number of transformers 112 can be equal to the number of secondary side converters 114. In various examples, primary side converter 110 can be implemented as a sparse active neutral point clamped (SANPC) power converter.

[0029] For ease of explanation, an example is provided regarding a configuration in which the transformer 112 includes two transformers (including a first transformer 116a and a second transformer 116b) and the secondary-side converter 114 includes two converters (including a primary-side converter 118a and a secondary-side converter 118b). In other examples, other numbers of transformers 112 and secondary-side converters 114 (e.g., more than two of each) are within the scope of the present disclosure. The power converter 100 also includes at least one controller 120 ("controller 120") that can be communicatively coupled to one or more of the primary-side converter 110, the transformer 112, and / or the secondary-side converter 114. To simplify the illustration, the communication connection with the controller 120 is not explicitly shown.

[0030] Input 102 is coupled to primary-side converter 110 and may be configured to be coupled to a DC power source. For example, input 102 may be configured to be coupled to an AC / DC converter configured to receive AC power from an AC utility grid, convert the AC power to DC power, and provide the DC power to input 102.

[0031] The output connections 104-108 are configured to be coupled to one or more loads. Two or more output connections 104-108 can collectively function as at least one output. One or more loads can be coupled to the output connections 104-108 in any of a variety of configurations. For example, a single load can be coupled to the output connections 104-108 in a bipolar configuration, or a single load can be coupled to the output connections 104-108 in a redundant unipolar configuration, or multiple loads can be coupled to the output connections 104-108 in a symmetrical unipolar configuration (e.g., one load coupled to the output connection 104, 106a, which functions as one output, and one load coupled to the output connection 106b, 108, which functions as the other output), etc. In some examples, the output connections 106a, 106b can be electrically coupled to each other and thus be considered a single neutral output connection 106.

[0032] The primary side converter 110 is coupled between the input 102 and the transformer 112 . The primary side converter 110 receives DC power from the input 102 , converts the DC power to AC power, and provides the AC power to the transformer 112 .

[0033] The transformer 112 is coupled between the primary-side converter 110 and the secondary-side converter 114. For example, a first transformer 116a is coupled to the primary-side converter 110 (e.g., on the primary winding side) and the primary-side converter 118a (e.g., on the secondary winding side), and a second transformer 116b is coupled to the primary-side converter 110 (e.g., on the primary winding side) and the secondary-side converter 118b (e.g., on the secondary winding side). The transformer 112 receives AC power from the primary-side converter 110 and provides induced AC power to the secondary-side converter 114.

[0034] The secondary-side converter 114 is coupled between the transformer 112 and the output connections 104 - 108. For example, the primary-side converter 118a is coupled to the first transformer 116a at its input and to the positive output connection 104 and the first neutral output connection 106a at its output, and the secondary-side converter 118b is coupled to the second transformer 116b at its input and to the second neutral output connection 106b and the negative output connection 108 at its output.

[0035] Output connections 104-108 are coupled to secondary-side converter 114 and configured to be coupled to at least one load. For example, positive output connection 104 may be coupled to primary-side converter 118a and configured to be coupled to a load. Neutral output connections 106a, 106b may be coupled to secondary-side converters 118a, 118b and configured to be coupled to at least one load. Negative output connection 108 may be coupled to secondary-side converter 118b and configured to be coupled to a load.

[0036] As described above, the power converter 100 can support various load configurations. In one example, a single load can be coupled to the positive output connection 104 and the negative output connection 108. A single load can receive the full voltage output Vdc from the power converter 100. In another example, one load can be coupled to the positive output connection 104 and the first neutral output connection 106a, and another load can be coupled to the second neutral output connection 106b and the negative output connection 108. Each load can receive half of the full voltage output Vdc / 2 from the power converter 100. Although the neutral output connections 106a, 106b can be electrically coupled together in some examples, in examples where a first load is coupled to the connections 104, 106a and a second load is coupled to the connections 106b, 108, the two loads can draw power independently of each other; therefore, the neutral output connections 106a, 106b are shown as separate connections.

[0037] In yet another example, a single load may be coupled to the positive output connection 104 and the first neutral output connection 106a, and may be redundantly coupled to the second neutral output connection 106b and the negative output connection 108. In this example, the load may receive a Vdc / 2 output across the positive output connection 104 and the first neutral output connection 106a, and if power ceases to be available at some future point (e.g., due to a failure of the primary-side converter 118a), the load may instead draw the Vdc / 2 output across the second neutral output connection 106b and the negative output connection 108. Thus, the single load drawing Vdc / 2 may use redundant power.

[0038] Figure 2A schematic diagram of a power converter 200 according to an example is shown. The power converter 200 can be an example of the power converter 100. Therefore, examples of components from the power converter 100 are labeled accordingly in the power converter 200. The power converter 200 includes an input 102, a positive output connection 104, a neutral output connection 106, a negative output connection 108, a primary side converter 110, transformers 116a, 116b, secondary side converters 118a, 118b, and a controller 120. In some examples, the neutral output connection 106 can include a single connection or multiple connections (e.g., first and second neutral output connections 106a, 106b) that can be electrically coupled together. As shown in FIG. Figure 2 As shown, the primary side converter 110 is a sparse active neutral point clamped (SANPC) power converter.

[0039] Input 102 includes a first input connection 102a and a second input connection 102b. Primary-side converter 100 includes a positive capacitor 202, a negative capacitor 204, a first set of switching devices 206 ("first set of switches 206"), and a second set of switching devices 208 ("second set of switches 208"). First set of switches 206 includes a first switch 210a, a second switch 210b, a third switch 212a, and a fourth switch 212b. Second set of switches 208 includes a fifth switch 214a, a sixth switch 214b, a seventh switch 216a, and an eighth switch 216b.

[0040] The first transformer 116a includes a first primary winding 218 and a first secondary winding 220. The second transformer 116b includes a second primary winding 222 and a second secondary winding 224. The primary-side converter 118a can be configured as a full-bridge DC / AC inverter and includes a first switching branch 226 and a second switching branch 228. The first switching branch 226 includes a first switch 230a and a second switch 230b. The second switching branch 228 includes a third switch 232a and a fourth switch 232b.

[0041] Secondary-side converter 118b can be configured as a full-bridge DC / AC inverter and includes a third switching leg 234 and a fourth switching leg 236. Third switching leg 234 includes a fifth switch 238a and a sixth switch 238b. Fourth switching leg 236 includes a seventh switch 240a and an eighth switch 240b. Secondary-side converter 114 also includes a first capacitor 242 and a second capacitor 244.

[0042] The first input connection 102a is coupled to the positive input bus 246. The second input connection 102b is coupled to the negative input bus 248. The first capacitor 202 is coupled to the positive input bus 246 at a first connection and to a reference node 250 (e.g., a neutral node) at a second connection. The second capacitor 204 is coupled to the reference node 250 at a first connection and to the negative input bus 248 at a second connection. The first switch 210a is coupled to the positive input bus 246 at a first connection and to the third switch 212a, the fifth switch 214a, and the seventh switch 216a at a second connection via an intermediate positive bus 252. The second switch 210b is coupled to the fourth switch 212b, the sixth switch 214b, and the eighth switch 216b at a first connection via an intermediate negative bus 254 and to the negative input bus 248 at a second connection.

[0043] The third switch 212a is coupled to the first switch 210a at a first connection and to the reference node 250 at a second connection. The fourth switch 212b is coupled to the reference node 250 at a first connection and to the second switch 210b at a second connection. The fifth switch 214a is coupled to the first switch 210a at a first connection and to the first primary winding 218 at a second connection. The sixth switch 214b is coupled to the first primary winding 218 at a first connection and to the second switch 210b at a second connection.

[0044] The seventh switch 216a is coupled to the first switch 210a at a first connection and to the second primary winding 222 at a second connection. The eighth switch 216b is coupled to the second primary winding 222 at a first connection and to the second switch 210b at a second connection.

[0045] The first primary winding 218 is coupled to the midpoint of the fifth switch 214 a and the sixth switch 216 b with a dashed connection, is coupled to the reference node 250 with a non-dashed connection, and is inductively coupled to the first secondary winding 220. The second primary winding 222 is coupled to the reference node 250 with a non-dashed connection, is coupled to the midpoint of the seventh switch 216 a and the eighth switch 216 b with a dashed connection, and is inductively coupled to the second secondary winding 224.

[0046] The first secondary winding 220 is coupled to the midpoint of the first switch 230a and the second switch 230b with a dashed line connection, is coupled to the midpoint of the third switch 232a and the fourth switch 232b with a non-dashed line connection, and is inductively coupled to the first primary winding 218. The second secondary winding 224 is coupled to the midpoint of the fifth switch 238a and the sixth switch 238b with a dashed line connection, is coupled to the midpoint of the seventh switch 240a and the eighth switch 240b with a non-dashed line connection, and is inductively coupled to the second primary winding 222.

[0047] The first switch 230a is coupled to the positive output connection 104 at a first connection and to the first secondary winding 220 and the second switch 230b at a second connection. The second switch 230b is coupled to the first secondary winding 220 and the first switch 230a at a first connection and to the reference node 256 (e.g., a neutral node) at a second connection. The third switch 232a is coupled to the positive output connection 104 at a first connection and to the first secondary winding 220 and the fourth switch 232b at a second connection. The fourth switch 232b is coupled to the third switch 232a and the first secondary winding 220 at a first connection and to the reference node 256 at a second connection.

[0048] Fifth switch 238a is coupled to reference node 256 at a first connection and to second secondary winding 224 and sixth switch 238b at a second connection. Sixth switch 238b is coupled to fifth switch 238a and second secondary winding 224 at a first connection and to negative output connection 108 at a second connection. Seventh switch 240a is coupled to reference node 256 at a first connection and to second secondary winding 224 and eighth switch 240b at a second connection. Eighth switch 240b is coupled to second secondary winding 224 and seventh switch 240a at a first connection and to negative output connection 108 at a second connection.

[0049] The first capacitor 242 is coupled at a first connection to the positive output connection 104 and at a second connection to the reference node 256. The second capacitor 244 is coupled at a first connection to the reference node 256 and at a second connection to the negative output connection 108. In various examples, the controller 120 can be coupled to the control connection of each switch 210a, 210b, 212a, 212b, 214a, 214b, 216a, 216b, 230a, 230b, 232a, 232b, 238a, 238b, 240a, 240b to control the switching state of each respective switch.

[0050] The power converter 200 may receive DC power at the input connections 102a, 102b. The controller 120 may operate the switches of the primary-side converter 110 to draw DC power from the input connections 102a, 102b, convert the DC power to AC power, and provide the AC power to the primary windings 218, 222 to induce a voltage on the secondary windings 220, 224. The controller 120 may operate the switches of the secondary-side converters 118a, 118b to draw induced power from the secondary windings 220, 224, convert the induced power to power at a desired voltage level, and provide the converted power to the output connections 104-108.

[0051] In some examples, neutral output connection 106 may include multiple neutral output connections coupled to reference node 256. For example, a first neutral output connection (e.g., first neutral output connection 106a) may be coupled to reference node 256 to serve as the neutral connection for primary side converter 118a, and a second neutral output connection (e.g., second neutral output connection 106b) may be coupled to reference node 256 to serve as the neutral connection for secondary side converter 118b. However, the individual neutral output connections may all be coupled to reference node 256 and therefore may be at the same potential. In other examples, such as Figure 2 In the example shown, the neutral output connection 106 may include a single neutral output connection that may serve as the neutral connection for both secondary-side converters 118 .

[0052] It may be advantageous for controller 120 to switch the switches of power converter 200 under zero current conditions, i.e., to implement zero current switching. For example, it may be advantageous for controller 120 to switch the switches of primary-side converter 110 under zero current conditions. Implementing zero current switching in primary-side converter 110 may improve the efficiency of primary-side converter 110. However, providing zero current switching for all switches of primary-side converter 110 may not be feasible.

[0053] In various examples, zero current switching is provided for the second switch 208 but may not be provided for the first switch 206. However, while zero current switching may not be provided for the first switch 206, the first switch 206 may be rated lower than the second switch 208 and, therefore, the first switch 206 may experience reduced losses from the switching event compared to the switching losses that would exist if the second switch 208 did not switch at zero current. For example, the first switch 206 may be rated for approximately 1.2 kV and the second switch 208 may be rated for approximately 1.7 kV. Thus, efficiency may be supported by providing zero current switching for the second switch 208, which would otherwise experience greater losses.

[0054] Furthermore, certain switching states associated with higher losses are prohibited. For example, the current through the first switch 210a may be equal to the sum of the currents through the fifth switch 214a and the seventh switch 216a. If both switches 214a and 216a are closed when the first switch 210a is switched, the current through the first switch 210a may be greater than if one of the switches 214a and 216a is open when the first switch 210a is switched. Therefore, it is possible to prohibit switches 214a and 216a from being closed or opened simultaneously to prevent high current from flowing through the first switch 210a, so that the first switch 210a is not switched when conducting excessive current. Similarly, it is possible to prohibit switches 214b and 216b from being closed or opened simultaneously to prevent high current from flowing through the second switch 210b.

[0055] In this manner, the controller 120 can operate the fifth switch 214a and the seventh switch 216a in complementary states (e.g., only in complementary states), and can operate the sixth switch 214b and the eighth switch 216b in complementary states (e.g., only in complementary states), so that the current through the first switch 210a and the second switch 210b is minimized. Thus, at any given time when current is passing through the first switch 210a, the current passing through the first switch 210a may pass through either the fifth switch 214a or the seventh switch 216a, but not both. Similarly, at any given time when current is passing through the second switch 210b, the current passing through the second switch 210b may pass through either the sixth switch 214b or the eighth switch 216b, but not both. Although the first switch 210a and the second switch 210b may not switch at zero current switching, losses are minimized by operating the switches 214a, 216a and 214b, 216b in complementary states.

[0056] To explain the modulation state in more detail, Figure 3 A diagram 300 illustrates the switching states of the primary-side converter 110 according to an example. A first column 302 indicates the switching state number. A second column 304 indicates the value of the first switching signal u1. The first switching signal is provided to the first switch 210a. An inverted version of the first switching signal is provided to the third switch 212a. A third column 306 indicates the value of the second switching signal u2. The second switching signal is provided to the fourth switch 212b. An inverted version of the second switching signal is provided to the second switch 210b.

[0057] Fourth column 308 shows the value of third switching signal u3. The third switching signal is provided to fifth switch 214a. An inverted version of the third switching signal is provided to sixth switch 214b. Fifth column 310 shows the value of fourth switching signal u4. The fourth switching signal is provided to seventh switch 216a. An inverted version of the fourth switching signal is provided to eighth switch 216b.

[0058] The sixth column 312 represents the voltage V between the second set of switches 208 and switches 212a, 212b from the intermediate negative bus 254 to the intermediate positive bus 252. m,p The seventh column 314 represents the voltage V across the first primary winding 218. + m,p The eighth column 216 represents the voltage V across the second primary winding 220. - m,p Voltage V m,p 、V + m,p and V - m,pEach of is denoted by Vdc, which is the voltage across the primary side converter 100 from the second input connection 102b to the first input connection 102a.

[0059] As described above, columns 304-310 correspond to the switch states of switches 210a-216b. For example, a "0" indicates that controller 120 provides a control signal to a given switch, causing the switch to be open and non-conductive. A "1" indicates that controller 120 provides a control signal to a given switch, causing the switch to be closed and conductive. The inverse of a "0" switch signal is a "1" switch signal, and the inverse of a "1" switch signal is a "0" switch signal.

[0060] As described above, the fifth switch 214a and the seventh switch 216a can operate in complementary states (and, in some examples, can only operate in complementary states), and the sixth switch 214b and the eighth switch 216b can operate in complementary states (and, in some examples, can only operate in complementary states). Therefore, the third switch signal u3 (which is provided to the fifth switch 214a and its inverted signal is provided to the sixth switch 214b) and the fourth switch signal u4 (which is provided to the seventh switch 216a and its inverted signal is provided to the eighth switch 216b) have complementary states, as shown in the graph 300. In other words, the third switch signal u3 can be prohibited from having the same state as the fourth switch signal u4, and vice versa.

[0061] Using the first row 318 corresponding to the first state labeled "1" in the first column 302 as an example of the chart 300, the first switch signal u1, the second switch signal u2, and the third switch signal u3 all have a state of "0." Therefore, the first switch 210a, the fourth switch 212b, and the fifth switch 214a are open and non-conductive (in response to receiving a control signal corresponding to the state "0" from the controller 120), and the third switch 212a, the second switch 210b, and the sixth switch 214b are closed and conductive (in response to receiving an inverted control signal corresponding to the state "0" from the controller 120). The fourth switch signal u4 has a state of "1." Therefore, the seventh switch 216a is closed and conductive (in response to receiving a control signal corresponding to the state "1" from the controller 120), and the eighth switch 216b is open and non-conductive (in response to receiving an inverted control signal corresponding to the state "1" from the controller 120).

[0062] Every other row of the graph 300 corresponds to a respective switching state of the primary side converter 110. The second row 320 corresponds to the second state labeled "2", the third row 322 corresponds to the third state labeled "3", the fourth row 324 corresponds to the fourth state labeled "4", the fifth row 326 corresponds to the fifth state labeled "5", the sixth row 328 corresponds to the sixth state labeled "6", the seventh row 330 corresponds to the seventh state labeled "7", and the eighth row 332 corresponds to the eighth state labeled "8".

[0063] Figure 4 A schematic diagram of power converter 200 is shown in a state corresponding to first row 318, wherein non-conducting switches 210a, 212b, 214a, and 216b are overlaid with an "X" to indicate that they are non-conducting. Because second switch 210b is closed, fourth switch 212b is coupled to negative input bus 248. Because fourth switch 212b is open, a voltage of Vdc / 2 is dropped across open fourth switch 212b. Because third switch 212a is closed, zero voltage is dropped across closed third switch 212a. Therefore, the voltage from intermediate negative bus 254 to intermediate positive bus 252 (i.e., the voltage across switches 212a, 212b) is equal to Vdc / 2, as shown in sixth column 312 of first row 318.

[0064] Similarly, because the second switch 210 b and the sixth switch 214 b are closed, the dashed pole of the first primary winding 218 is coupled to the negative input bus 248. The non-dashed pole of the first primary winding 218 is coupled to the reference node 250. Therefore, as shown in the seventh column 314 of the first row 318, the voltage across the first primary winding 218 from the non-dashed pole to the dashed pole is -Vdc / 2.

[0065] Similarly, because third switch 212 a and seventh switch 216 a are closed, the dashed pole of second primary winding 222 is coupled to reference node 250. The non-dashed pole of second primary winding 222 is coupled to reference node 250. Therefore, the voltage across second primary winding 222 is zero, as shown in eighth column 316 of first row 318.

[0066] Thus, diagram 300 provides a state of each switch of primary-side converter 110. Thus, diagram 300 provides a list of possible switch states for primary-side converter 110, i.e., a list of switch states from which prohibited switch states (e.g., where u3=u4) are omitted. In some examples, controller 120 can implement a trapezoidal modulation scheme to switch through at least a subset of the allowed switch states.

[0067] Figure 5A set of graphs 500 is shown, depicting the operation of the primary-side converter 110 according to an example. Graphs 500 include a first graph 502 and a second graph 504. First graph 502 corresponds to the first transformer 116a. Second graph 504 corresponds to the second transformer 116b. Graphs 500 also correspond to a switch state list 506, which shows the states of switching signals u1, u2, u3, and u4.

[0068] The first curve 502 includes a first current trace 508 depicting the current through the first primary winding 218, a first voltage trace 510 indicating the voltage across the first primary winding 218, and a second voltage trace 512 indicating the voltage across the first secondary winding 220. The second curve 504 includes a second current trace 514 depicting the current through the second primary winding 222, a third voltage trace 516 indicating the voltage across the second primary winding 222, and a fourth voltage trace 518 indicating the voltage across the second secondary winding 224.

[0069] As shown in the first curve 502, during the first time period 520, the primary-side converter 110 operates in the sixth state corresponding to the sixth row 328, as shown in the switch state list 506. As shown in the seventh column 314 and the first voltage trace 510, the voltage across the first primary winding 218 is Vdc / 2. As shown in the second voltage trace 512, the voltage across the first secondary winding 220 is zero. As shown in the first current trace 508, the current through the first primary winding 218 rises to a maximum positive value i during the first time period 520. max .

[0070] During a second time period 522 that begins immediately after the first time period 520, the primary side converter 110 remains in the sixth state corresponding to the sixth row 328. As shown in the second voltage trace 512, the voltage across the first secondary winding 220 transitions from zero to Vdc / 2 due to switching in the primary side converter 118a. As shown in the first current trace 508, the current through the first primary winding 218 remains at a maximum positive current i max .

[0071] During the third time period 524 that begins immediately after the second time period 524, the primary side converter 110 switches from the sixth state to the fourth state corresponding to the fourth row 324, as shown in the switch state list 506. Therefore, the first switching signal u1 and the second switching signal u2 switch states, causing the first switch 210a, the second switch 210b, the third switch 212a, and the fourth switch 212b to switch states. Because the current through the first primary winding 218 is not zero (because the current is i max), so switches 210a, 210b, 212a, 212b do not switch with zero current switching. However, as described above, switches 210a, 210b, 212a, 212b may have a lower voltage rating than switches 214a-216b and therefore may experience lower losses from non-zero current switching.

[0072] During a third time period 524, the voltage across the first primary winding 218 is zero, as shown in the seventh column 314 and the first voltage trace 510. The voltage across the first secondary winding 220 remains at Vdc / 2, as shown in the second voltage trace 512. As shown in the first current trace 508, the current through the first primary winding 218 decreases during the third time period 524 to zero at the end of the third time period 524.

[0073] The time periods 520-524 occur on the positive half cycle of the current through the first primary winding 218. Similar principles apply to the negative half cycle of the current through the first primary winding 218, as shown in the remainder of the first curve 502.

[0074] Turning to the second curve 504, during the first time period 520, the voltage across the second primary winding 222 is -Vdc / 2, as shown in the third voltage trace 516 and the eighth column 316 of the sixth row 328. As shown in the fourth voltage trace 518, the voltage across the second secondary winding 224 is zero. As shown in the second current trace 514, the current through the second primary winding 222 gradually becomes negative during the first time period 520, reaching a maximum negative value of -i max .

[0075] During a second time period 522 that begins immediately after the first time period 520, the primary side converter 110 remains in the sixth state corresponding to the sixth row 328. As shown in the fourth voltage trace 518, the voltage across the second secondary winding 224 transitions from zero to -Vdc / 2 due to switching in the secondary side converter 118b. As shown in the second current trace 514, the current through the second primary winding 222 remains at a maximum negative current -i max .

[0076] During a third time period 524, which begins immediately after the second time period 524, the primary-side converter 110 transitions from the sixth state to the fourth state corresponding to the fourth row 324, as shown in the switch state list 506. As a result, the voltage across the second primary winding 222 transitions from -Vdc / 2 to zero, as shown in the third voltage trace 516 and the eighth column 316 of the fourth row 324. As shown in the fourth voltage trace 518, the voltage across the second secondary winding 224 remains at -Vdc / 2. As shown in the second current trace 514, the absolute value of the current through the second primary winding 222 decreases from the maximum negative current -i maxDecreasing toward zero, the current reaches zero at the end of the third time period 524 .

[0077] Time periods 520-524 occur during the negative half-cycle of the current through the second primary winding 222. Similar principles apply to the positive half-cycle of the current through the second primary winding 222, as shown in the remainder of the second curve 504. As shown in the current traces 508, 514, the current through the first primary winding 218 is offset by 180° relative to the current through the second primary winding 222 throughout the entire cycle of the current.

[0078] In summary, primary-side converter 110 can be implemented as a SANPC converter. Controller 120 may not operate first set of switches 206 of the SANPC with zero current switching, and may operate second set of switches 208 of the SANPC with zero current switching. However, because each of first set of switches 206 may have a lower voltage rating than each of second set of switches 208, hard switching losses are reduced.

[0079] Furthermore, the controller 120 may implement a trapezoidal modulation scheme to control the operation of the SANPC. When implementing the trapezoidal modulation scheme, certain switch states may be prohibited. Specifically, prohibited switch states include switches 214a and 216a being simultaneously closed, and switches 214b and 216b being simultaneously closed. By prohibiting these switch states, the current through the first switch 210a and the second switch 210b can be limited. By limiting the current through the switches 210a and 210b, losses can be minimized due to the non-zero current switching operation of the switches 210a and 210b.

[0080] In addition to high efficiency operation, power converter 200 can serve a variety of load configurations, including symmetrical unipolar and bipolar configurations. Power converter 200 can power at least two loads (e.g., a first load coupled across output connections 104, 106 and a second load coupled across output connections 106, 108) in a symmetrical unipolar configuration, and / or can power at least one load (e.g., a load coupled to output connections 104-108) in a bipolar configuration.

[0081] In various examples, examples of power converter 100 can support any number of loads, including more than two loads. For example, power converter 100 can be implemented with more than two transformers 112, more than two secondary-side converters 114, and more than three output connections 104-108.

[0082] Examples of power converter 100, such as power converter 200, can be configured to provide power to multiple unbalanced loads. Unbalanced loads include loads that draw different amounts of power from power converter 100. For example, power converter 200 can provide power to a first load coupled to outputs 104, 106 at one power rating, and can provide power to a second load coupled to outputs 106, 108 at another power rating. In additional examples of power converter 100, power converter 100 can power any number of loads, which can be balanced or unbalanced.

[0083] Various controllers, such as controller 120, can perform the various operations described above. Controller 120 can also execute one or more instructions stored on one or more non-transitory computer-readable media, which controller 120 may include and / or be connected to, which can generate manipulated data. Non-transitory computer-readable media may include memory and / or storage devices. In some examples, controller 120 may include one or more processors or other types of controllers. In one example, controller 120 is or includes at least one processor. In another example, in addition to or in place of a processor, controller 120 uses an application-specific integrated circuit (ASIC) customized to perform the specific operations to perform at least a portion of the operations described above. As these examples illustrate, many specific combinations of hardware and software can be used to perform the operations described herein according to examples of the present disclosure, and the present disclosure is not limited to any specific combination of hardware and software components. Examples of the present disclosure may include computer program products configured to perform the methods, processes, and / or operations described above. A computer program product may be or include one or more controllers and / or processors configured to execute instructions to perform the methods, processes, and / or operations described above.

[0084] Having thus described several aspects of at least one embodiment, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be a part of this disclosure and are within the spirit and scope of this disclosure. Therefore, the foregoing description and accompanying drawings are merely illustrative.

Claims

1. A DC / DC converter comprising: an input configured to be connected to a DC power source; a sparse active neutral point clamped converter (SANPC) coupled to the input; a plurality of transformers coupled to the SANPC, the plurality of transformers comprising a first transformer and a second transformer; a first AC / DC converter coupled to the first transformer; a second AC / DC converter coupled to the second transformer; and At least one output is coupled to the first AC / DC converter and the second AC / DC converter and configured to provide DC output power to one or more loads.

2. The DC / DC converter of claim 1, wherein the at least one output comprises three output connections. 3 . The DC / DC converter of claim 2 , wherein the three output connections are configured to couple to the one or more loads in a bipolar configuration. 4 . The DC / DC converter of claim 3 , wherein each of the three output connections is configured to couple to at least one of the one or more loads in a bipolar configuration. 5 . The DC / DC converter of claim 2 , wherein the three output connections are configured to couple to the one or more loads in a symmetrical unipolar configuration.

6. The DC / DC converter of claim 5, wherein a first set of two of the three output connections are configured to couple to a first load in a symmetrical unipolar configuration, and a second set of two of the three output connections are configured to couple to a second load in a symmetrical unipolar configuration.

7. The DC / DC converter of claim 1, further comprising at least one controller, wherein the SANPC comprises a plurality of switches, and wherein the at least one controller is configured to operate at least one switch of the plurality of switches with zero current switching.

8. The DC / DC converter of claim 7, wherein the plurality of switches comprises a first group of one or more switches and a second group of one or more switches, and wherein the at least one controller is configured to: operating the first set of one or more switches with zero current switching; and The second set of one or more switches is not operated with zero current switching.

9. The DC / DC converter of claim 8, wherein the switches of the first set of one or more switches have a first rated voltage, the switches of the second set of one or more switches have a second rated voltage, and wherein the first rated voltage is greater than the second rated voltage.

10. The DC / DC converter of claim 8, further comprising a positive input bus and a negative input bus coupled to the input, wherein the SANPC comprises an intermediate positive bus, an intermediate negative bus, and a reference node, and wherein the second set of one or more switches comprises: a first switch coupled between the positive input bus and the intermediate positive bus; a second switch connected between the negative input bus and the intermediate negative bus; a third switch connected between the intermediate positive bus and the reference node; and A fourth switch is connected between the intermediate negative bus and the reference node.

11. The DC / DC converter of claim 10, wherein the first set of one or more switches comprises: a fifth switch connected between the intermediate positive bus and the plurality of transformers; a sixth switch connected between the plurality of transformers and the intermediate negative bus; a seventh switch connected between the intermediate positive bus and the plurality of transformers; and An eighth switch is connected between the plurality of transformers and the intermediate negative bus.

12. The DC / DC converter according to claim 11, wherein: The fifth switch and the sixth switch are coupled to the primary winding of the first transformer; and The seventh switch and the eighth switch are coupled to the primary winding of the second transformer.

13. The DC / DC converter according to claim 11 , wherein the at least one controller is configured to: operating the fifth switch and the seventh switch only in complementary states; and The sixth switch and the eighth switch are operated only in complementary states.

14. The DC / DC converter of claim 1 , further comprising a positive input bus and a negative input bus coupled to the input, wherein the SANPC comprises: Intermediate positive bus; Intermediate negative bus; Reference node; a first switch coupled between the positive input bus and the intermediate positive bus; a second switch connected between the negative input bus and the intermediate negative bus; a third switch connected between the intermediate positive bus and the reference node; and A fourth switch is connected between the intermediate negative bus and the reference node.

15. The DC / DC converter according to claim 14, wherein the SANPC further comprises: a fifth switch connected between the intermediate positive bus and the plurality of transformers; a sixth switch connected between the plurality of transformers and the intermediate negative bus; a seventh switch connected between the intermediate positive bus and the plurality of transformers; and An eighth switch is connected between the plurality of transformers and the intermediate negative bus.

16. The DC / DC converter according to claim 15, wherein: The fifth switch and the sixth switch are coupled to the primary winding of the first transformer; and The seventh switch and the eighth switch are coupled to the primary winding of the second transformer.

17. The DC / DC converter according to claim 15, wherein the at least one controller is configured to: operating the fifth switch and the seventh switch only in complementary states; and The sixth switch and the eighth switch are operated only in complementary states.

18. The DC / DC converter of claim 1 , further comprising at least one controller, wherein the SANPC comprises: a first switch, coupled to the input, a second switch coupled to the first switch and the plurality of transformers, and a third switch coupled to the first switch and the plurality of transformers, wherein the at least one controller is configured to: The second switch and the third switch are operated only in complementary states so that the current passing through the first switch passes through the second switch or the third switch.

19. The DC / DC converter according to claim 18, wherein the SANPC comprises: a fourth switch coupled to the input, a fifth switch coupled to the fourth switch and the second switch, and a sixth switch coupled to the fourth switch and the third switch, wherein the at least one controller is further configured to: The fifth switch and the sixth switch are operated only in complementary states so that the current passing through the fourth switch passes through the fifth switch or the sixth switch.

20. At least one non-transitory computer-readable medium having stored thereon a sequence of computer-executable instructions for operating a DC / DC converter having a sparse active neutral point clamped converter (SANPC), a plurality of transformers coupled to the SANPC, and a plurality of AC / DC converters coupled to the plurality of transformers, the sequence of computer-executable instructions comprising instructions directing at least one processor to: operating the first switch and the second switch of the SANPC with zero current switching; not operating a third switch of the SANPC with zero current switching, the third switch being coupled to the first switch and the second switch; and The first switch and the second switch are operated in complementary states so that the current passing through the third switch passes through the first switch or the second switch.

21. A method of operating a DC / DC converter having a sparse active neutral point clamped converter (SANPC), a plurality of transformers coupled to the SANPC, and a plurality of AC / DC converters coupled to the plurality of transformers, the method comprising: operating the first switch and the second switch of the SANPC with zero current switching; operating a third switch of the SANPC not with zero current switching, the third switch being coupled to the first switch and the second switch; and The first switch and the second switch are operated in complementary states such that the current passing through the third switch passes through the first switch or the second switch.

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