DC to DC Converters

Abstract

A DC to DC converter is disclosed. A bidirectional or unidirectional DC‑DC converter includes a primary and a secondary. The primary is configured to receive or output a first DC voltage. The primary includes a first switch network, which is configured to convert the first DC voltage into a first alternating current (AC) voltage or vice versa. The DC‑DC converter also includes a transformer having a primary winding and a secondary winding. The primary winding is in electrical communication with the first switch network. The transformer is configured to convert between a first AC voltage and a second AC voltage. The DC‑DC converter also includes a secondary having a second switch network. Typically, the second switch network and the transformer operate as an interleaved converter to convert the second AC voltage into an output DC voltage or vice versa. Advantageously, the required series inductance of the interleaved converter is integrated into the transformer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 067,206, filed on August 18, 2020, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] In at least one aspect, a method and apparatus for DC to DC conversion in an electric or hybrid electric vehicle is provided. background

[0004] like Figure 1 As shown, the most common DC-DC power converter is now implemented using the LLC structure. This structure requires L r and C r The resonant tank and isolation transformer that form the buck converter are usually used in these applications. This fact makes this implementation expensive due to the need for two magnetic components and challenging to tune due to the effects of variations in the resonant tank in the final converter operation.

[0005] To address these issues, dual active bridge topologies have been proposed to mitigate the main drawbacks of LLC implementations ( Figure 2A ). In an advantageous implementation, the required series inductance can be integrated into the transformer, resulting in the use of a single magnetic component. A series capacitor like Cr but smaller can be used to further avoid any current DC component reaching the transformer, although typically the DC current is forced to zero by control.

[0006] One of the main challenges of such converters is the need to provide high output current. This usually makes designing the transformer secondary a challenging task. To achieve a proper design, multiple rectifier implementations are usually used ( Figure 2B ) to obtain the required output current. However, this results in increased cost due to the additional power, drive and control equipment and additional control complexity.

[0007] Therefore, there is a need for an improved high to low voltage DC-DC converter having a reduced current drawn at the low voltage level.

[0008] Overview

[0009] In at least one aspect, a bidirectional or unidirectional DC-DC converter applying a dual active bridge rectifier topology is provided. The bidirectional or unidirectional DC-DC converter converts an input DC voltage into an output DC voltage. The bidirectional or unidirectional DC-DC converter includes a first switch network and a second switch network. The first switch network receives or outputs a first DC voltage and a first AC voltage. The first switch network is configured to receive a first DC voltage and convert the first DC voltage into a first AC voltage or convert the first AC voltage into a first DC voltage and output the first DC voltage. The second switch network operates from a secondary side bus voltage. The bidirectional or unidirectional DC-DC converter also includes a transformer having a primary winding and a secondary winding. The transformer is configured to receive a first AC voltage and output a second AC voltage, or to receive a second AC voltage and output a first AC voltage. The secondary winding includes a first end terminal, a second end terminal, and an output terminal located between the first end terminal and the second end terminal. The primary winding is in electrical communication with the first switch network, and the secondary winding is in electrical communication with the second switch network. The second switch network is connected between the first end terminal and the second end terminal of the secondary winding. The secondary winding and the second switch network are configured to convert the second AC voltage into a second DC voltage or convert the second DC voltage into a second AC voltage. The first switch network and the second switch network are operated so that a first current flows between a first end terminal of the secondary winding and an output terminal, a second current flows between a second end terminal of the secondary winding and an output terminal, and a third current flows through the primary winding. Typically, the first current, the second current, and the third current are at least partially established by a mutual inductance between the primary winding and the secondary winding, so that when the first DC voltage is an input DC voltage, the second DC voltage is an output DC voltage, and when the second DC voltage is an input DC voltage, the first DC voltage is an output DC voltage.

[0010] On the other hand, the 400 / 12V DC-DC converter splits the secondary side of the transformer in two (with a midpoint). This design can double the operating voltage at the secondary switching stage, thereby reducing the current through the components therein by half. The design also makes it possible to use lower cost switches or fewer switches (in the case of parallel connection), resulting in reduced cost.

[0011] In another aspect, a DC-DC converter is provided that eliminates low voltage 1 (eg, 12V) filter components. Due to the functional improvements available in this new configuration, the filter components can be eliminated.

[0012] In yet another aspect, a DC-DC converter is provided that eliminates the need for a choke on the secondary side DC output. Instead, the inductance of the secondary side of the transformer is used to provide the DC output. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a further understanding of the nature, objects and advantages of the present disclosure, reference should be made to the following detailed description read in conjunction with the following drawings, wherein like reference numerals represent like elements, and wherein:

[0014] Figure 1 : Schematic diagram of a prior art DC-DC converter.

[0015] Figure 2A : Schematic diagram of a prior art DC-DC converter.

[0016] Figure 2B : Schematic diagram of a prior art DC-DC converter.

[0017] Figure 3 : Schematic diagram of a creative design of a bidirectional or unidirectional DC-DC converter.

[0018] Figure 4A , 4B 4C: Primary side waveforms of a converter receiving an input DC voltage on the primary side and outputting an output DC voltage on the secondary side: primary side bus voltage, half-bridge 1 output voltage (“pVHB1”) and half-bridge 2 output voltage (“pVHB2”), full-bridge output voltage (pVHB1-pVHB2), and current through the transformer primary (I(L3)).

[0019] Figure 5A , 5B , 5C and 5D: Secondary side waveforms of a converter receiving an input DC voltage on the primary side and outputting an output DC voltage on the secondary side: secondary side bus voltage, half bridge 1 output voltage (“sVHB1”) and half bridge 2 output voltage (“sVHB2”), full bridge output voltage (sVHB1-sVHB2), and current through the transformer secondary ( Figure 3 I(L1) and I(L2) in it).

[0020] Figure 6 : Details of the primary side output voltage (pVHB1-pVHB2), the secondary side output voltage (sVHB1-sVHB2) and the current (I(L3)) through the transformer primary of a converter that receives an input DC voltage on the primary side and outputs an output DC voltage on the secondary side.

[0021] Fig. 7A , 7B 7C: Primary side waveforms of a converter that receives an input DC voltage on the secondary side and outputs an output DC voltage on the primary side: primary side bus voltage, half-bridge 1 output voltage (“pVHB1”) and half-bridge 2 output voltage (“pVHB2”), full-bridge output voltage (pVHB1-pVHB2), and current through the transformer primary (I(L3)).

[0022] Fig. 8A , 8B , 8C and 8D: Secondary side waveforms of a converter receiving an input DC voltage on the primary side and outputting an output DC voltage on the secondary side: secondary side bus voltage, half bridge 1 output voltage (“sVHB1”) and half bridge 2 output voltage (“sVHB2”), full bridge output voltage (sVHB1-sVHB2), and current through the transformer secondary ( Figure 3 I(L1) and I(L2) in it). Detailed Description

[0023] Reference will now be made in detail to the currently preferred embodiments and methods of the present invention, which constitute the best mode of practicing the present invention currently known to the inventors. The accompanying drawings are not necessarily drawn to scale. However, it should be understood that the disclosed embodiments are merely examples of the present invention, and the present invention can be implemented in various forms and alternative forms. Therefore, the specific details disclosed herein should not be understood as limiting, but only as a representative basis for any aspect of the present invention, and / or as a representative basis for teaching those skilled in the art to utilize the present invention in various ways.

[0024] It should also be understood that the present invention is not limited to the specific embodiments and methods described below, as specific components and / or conditions may vary of course. In addition, the terminology used herein is used only for the purpose of describing specific embodiments of the present invention and is not intended to be limiting in any way.

[0025] It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, a component mentioned in the singular is intended to include a plurality of components.

[0026] The term "comprising" is synonymous with "including," "having," "containing," or "characterized by." These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps.

[0027] The phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. When the phrase appears in a clause in the body of a claim rather than immediately following the preamble, it limits only the elements recited in the clause; other elements are not excluded from the claim as a whole.

[0028] The phrase "consisting essentially of" limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristics of the claimed subject matter.

[0029] With respect to the terms "comprising," "consisting of," and "consisting essentially of," where one of these three terms is used herein, the presently disclosed and claimed subject matter may include the use of either of the other two terms.

[0030] It should also be appreciated that integer ranges include all intermediate integers explicitly. For example, integer ranges 1-10 include 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 explicitly. Similarly, ranges 1 to 100 include 1, 2, 3, 4 ... 97, 98, 99, 100. Similarly, when any range is required, the difference between the upper and lower limits divided by 10 as the intermediate digit of increment can be regarded as an optional upper or lower limit. For example, if the range is 1.1 to 2.1, the following digits 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 and 2.0 can be selected as the lower or upper limit.

[0031] The term "connected to" means that the electrical components referred to as being connected to are in electrical communication. In one refinement, "connected to" means that the electrical components referred to as being connected to are directly connected to each other with wires. In another refinement, "connected to" means that the electrical components communicate wirelessly or through a combination of wired and wirelessly connected components. In another refinement, "connected to" means that one or more additional electrical components are inserted between the electrical components referred to as being connected to, and that the electrical signal from the originating component is processed (e.g., filtered, amplified, modulated, rectified, attenuated, summed, subtracted, etc.) before being received by the components connected to it.

[0032] The term "electrical communication" means that an electrical signal is sent directly or indirectly from an originating electronic device to a receiving electrical device. Indirect electrical communication may involve processing of the electrical signal, including but not limited to filtering of the signal, amplification of the signal, rectification of the signal, modulation of the signal, attenuation of the signal, addition of a signal to another signal, subtraction of a signal from another signal, subtraction of another signal from a signal, and the like. Electrical communication may be accomplished using wired components, wirelessly connected components, or a combination thereof.

[0033] The term "electrical signal" refers to an electrical output from or input to an electronic device. An electrical signal is characterized by voltage and / or current. An electrical signal can be a fixed signal, or the electrical signal can vary over time.

[0034] The term "DC signal" or "DC voltage" refers to an electrical signal or voltage having a voltage value that is always greater than 0 volts.

[0035] The term "AC signal" or "AC voltage" refers to an electrical signal or voltage having a voltage that varies between positive and negative voltages and crosses 0 volts.

[0036] The term "electronic component" refers to any physical entity in an electronic device or system that is used to affect the state of electrons, the flow of electrons, or the electric fields associated with electrons. Examples of electronic components include, but are not limited to, capacitors, inductors, resistors, thyristors, diodes, transistors, etc. Electronic components can be passive or active.

[0037] The term "electronic device" or "system" refers to a physical entity formed by one or more electronic components to perform a predetermined function on electrical signals.

[0038] It should be understood that in any drawings of electronic equipment, a series of electronic components connected by lines (e.g., wires) indicate that such electronic components are in electrical communication with each other. In addition, when a line directs an electronic component to another electronic component, these electronic components can be connected to each other as described above.

[0039] abbreviation:

[0040] "AC" means alternating current.

[0041] "DAB" means Dual Active Bridge.

[0042] "DC" means direct current.

[0043] Reference now Figure 3, a schematic diagram of a bidirectional or unidirectional direct current / direct current (DC / DC) converter system is provided. A bidirectional or unidirectional DC / DC converter system 10 that converts an input DC voltage into an output DC voltage applies a dual active bridge rectifier topology. In one variation, the DC / DC converter 10 includes a primary 12 and a secondary 14. In this context, the primary 12 and the secondary 14 may also be referred to as a primary side 12 and a secondary side 14. The primary 12 is configured to receive (or output) a first DC voltage VDC1, and the secondary is configured to output (or receive) a second DC voltage VDC2. In one variation, a first switch network 16 receives or outputs a first DC voltage and a first AC voltage VAC1. In an improvement, when the primary receives an input DC voltage (as a first DC voltage VDC1), the secondary outputs an output DC voltage (as a second DC voltage VDC2), and the first switch network 16 is configured to receive an input DC voltage and convert the first DC voltage into a first AC voltage VAC1. In another improvement, when the secondary receives an input DC voltage (as the second DC voltage VDC2), the primary outputs an output DC voltage (as the first DC voltage VDC1), and the first switch network 16 is configured to convert the first AC voltage VAC1 into the first DC voltage and output the first DC voltage. In one improvement, the output DC voltage is less than the input DC voltage. In another improvement, the output DC voltage is greater than the input DC voltage.

[0044] The DC / DC converter system 10 further comprises a transformer 18 having a primary winding 20 and a secondary winding which is divided into a first winding portion 22 1 and the second winding portion 22 2 In one refinement, the primary winding is part of the primary, and the secondary winding is part of the secondary. I(L1) and I(L2) refer to the first winding portion 22 1 and the second winding portion 22 2The current of the primary winding 20, L1 and L2 represent its inductance. I(L3) refers to the current passing through the primary winding 20, L3 represents its inductance. The transformer 18 also includes an iron core 24, and in particular a magnetic iron core. The first current I(L1) and the second current I(L2) are combined to form an output DC current that provides an output DC voltage. In one improvement, the first current is approximately equal to the second current multiplied by -1 plus an offset value. The iron core 24 can provide electrical separation of the primary 12 from the secondary 14. The primary winding is in electrical communication with the first switch network 16, and the secondary winding is in electrical communication with the second switch network 28. In one improvement, when the primary receives an input DC voltage and the secondary outputs an output DC voltage, the transformer 18 is configured to convert the first AC voltage VAC1 into a second AC voltage VAC2. In another improvement, when the secondary receives an input DC voltage and the primary outputs an output DC voltage, the transformer 18 is configured to convert the second AC voltage VAC2 into the first AC voltage VAC1. In one improvement, the peak-to-peak value of the second AC voltage is from about 30 volts to 60 volts. In another refinement, the second AC voltage has a peak-to-peak value of approximately 48 volts.

[0045] The second switch network 28 is connected across the secondary winding (ie, connected between the first winding portion 22) by connecting to the terminal Ts1 and the terminal Ts2. 1 and the second winding portion 22 2 The secondary winding 22 refers to the first winding part 22 1 and the second winding portion 22 2 In one refinement, when the primary receives an input DC voltage (as a first DC voltage VDC1), the secondary 14 outputs an output DC voltage (as a second DC voltage VDC2), and the secondary winding 22 and the second switch network 28 are configured in combination to convert the second AC voltage VAC2 into the second DC voltage VDC2. In another refinement, when the secondary 14 receives an input DC voltage (as a second DC voltage VDC2), the primary 12 outputs an output DC voltage (as a first DC voltage VDC1), and the primary winding 20 and the first switch network 16 are configured in combination to convert the first AC voltage into the first DC voltage.

[0046] Advantageously, the first switch network 16 and the second switch network 28 are operated so that a first current I(L1) flows between a first end terminal of the secondary winding and an output terminal, a second current I(L2) flows between a second end terminal of the secondary winding and an output terminal, and a third current I(L3) passes through the primary winding. Typically, the first current I(L1), the second current I(L2), and the third current I(L3) are at least partially established by mutual inductance between the primary winding 20 and the secondary winding 22, so that when the first DC voltage is an input DC voltage, the second DC voltage is an output DC voltage, and when the second DC voltage is an input DC voltage, the first DC voltage is an output DC voltage. It should be appreciated that the second DC voltage VDC2 is output from or input to a terminal Tm in the secondary winding between terminals Ts1 and Ts2.

[0047] It should also be appreciated that the same magnetic components in the transformer 18 are used to perform the isolation transformer function at the DAB configuration and the series inductor at the buck configuration. Furthermore, the power device at the secondary side performs two tasks: the secondary side of the DAB converter and the interleaved converter. This provides a cost-effective implementation.

[0048] Still reference Figure 3, the first switch network 16 may include a first H-bridge circuit. Therefore, the first switch network 16 includes switches SP1, SP2, SP3 and SP4. The first switch network 16 includes a first H-bridge arm 30 and a second H-bridge arm 32. In the first H-bridge arm 30, the source of the transistor switch SP1 is connected to the first input terminal Tp1 of the primary winding 20 of the transformer 18. The drain of the transistor switch SP1 is connected to the positive side of the primary side voltage bus VPB1, which is electrically in communication with the positive side of the DC input voltage VDCin. The source of the transistor switch SP1 is also connected to the drain of the transistor switch SP2. Therefore, the source of the transistor switch SP1 and the drain of the transistor switch SP2 are both connected to the first input terminal Tp1 of the primary winding 20. The source of the transistor switch SP2 is electrically in communication with the negative side of the primary side voltage bus VPB1, and therefore electrically in communication with the negative side of the DC input voltage DCVin. Similarly, in the second H-bridge arm 32, the source of the transistor switch SP3 is connected to the second input terminal Tp2 of the primary winding 20. The drain of transistor switch SP3 is connected to the positive side of the primary side voltage bus VPB1. The source of transistor switch SP3 is also connected to the drain of transistor switch SP4. Therefore, the source of transistor switch SP3 and the drain of transistor switch SP4 are both connected to the second input terminal Tp2 of the primary winding 20. The source of transistor switch SP4 is in electrical communication with the negative side of the primary side voltage bus VPB1. During operation, when the primary receives a DC input (as a first DC voltage VDC1), the first switch network 16 establishes a first AC voltage VAC1 applied to the transformer 18 by generating positive and negative voltages that are alternately applied to the transformer. When the secondary 14 receives a DC input (as a second DC voltage VDC2), the first switch network 16 converts the first AC voltage VAC1 into the first DC voltage VDC1 which is now the output of the converter.

[0049] Still reference Figure 3, the second switch network 28 may include a second H-bridge circuit. Therefore, the second switch network 28 includes switches SS1, SS2, SS3 and SS4. The second switch network 28 includes a first H-bridge arm 40 and a second H-bridge arm 42. In the first H-bridge arm 40, the source of the transistor switch SS1 is connected to the first input terminal Ts1 of the secondary winding 22 of the transformer 18. The drain of the transistor switch SS1 is connected to the positive side of the secondary side voltage bus VPB2, which is in electrical communication with the positive side of the capacitor C1. The source of the transistor switch SS1 is also connected to the drain of the transistor switch SS2. Therefore, the source of the transistor switch SS1 and the drain of the transistor switch SS2 are both connected to the second input terminal Ts2 of the secondary winding 22. The source of the transistor switch SS2 is in electrical communication with the negative side of the secondary side voltage bus VPB2, and therefore in electrical communication with the negative side of the capacitor C1. Similarly, in the second H-bridge arm 42, the source of the transistor switch SS3 is connected to the first input terminal Ts1 of the secondary winding 22. The drain of transistor switch SS3 is connected to the positive side of the secondary side voltage bus VPB2, which is in electrical communication with the positive side of capacitor C1. The source of transistor switch SS3 is also connected to the drain of transistor switch SS4. Therefore, the source of transistor switch SS3 and the drain of transistor switch SS4 are both connected to the second input terminal Ts2 of transformer 18. The source of transistor switch SS4 is in electrical communication with the negative side of the secondary side voltage bus VPB2, which is in electrical communication with the negative side of capacitor C1. During operation, when the primary receives an input DC voltage (as the first DC voltage VDC1), the second switch network 28 allows the same voltage polarity to be provided to the output terminal Tm of transformer 18 during the positive and negative portions of each cycle of the second AC voltage. When the secondary 14 receives an input DC voltage (as the second DC voltage VDC2), the second switch network 28 is switched to generate a second AC voltage applied to transformer 18. Thus, on the secondary side, transistors SS1 and SS2 form a first secondary side H-bridge, while transistors SS3 and SS4 form a second secondary side H-bridge. For example, when the voltage at terminal Ts1 is positive relative to terminal Ts2, switches SS1 and SS4 are activated (i.e., turned on), while switches SS2 and SS3 are open (i.e., turned off and not conducting). When the voltage at terminal Ts2 is positive relative to terminal Ts1, switches SS2 and SS3 are activated (i.e., turned on or closed), while switches SS1 and SS4 are open (i.e., turned off).

[0050] In one variation, the secondary operates to reduce the output voltage at the secondary bus to obtain the desired output DC voltage. In an improvement, the output DC voltage is half the secondary bus voltage. In a typical 400-12 DC-DC converter implementation, the secondary bus voltage is 24V, and the supplied output voltage is 12V. Due to the increased bus voltage, this conversion stage provides the key benefit of reducing the current passing through the power device. Therefore, the output current capability is greatly enhanced.

[0051] In one variation, the converter 10 further includes a microcontroller 50 configured to control transistor switches in the first switch network 16 and the second switch network 28. In one improvement, the microcontroller 50 can send control signals to the gates of the transistor switches SP1, SP2, SP3, and SP4. At this point, the transistor switches SP1 and SP4 form a first pair, which are activated together and are turned on and off simultaneously by the control signal. Similarly, the transistor switches SP2 and SP3 form a second pair, which are activated together and are turned on and off simultaneously by the control signal. The first pair of transistor switches SP1 and SP4 are alternately activated by the control signal. Therefore, the control signal of the first pair of transistor switches SP1 and SP4 is out of phase (usually 180°) with the second pair of transistor switches SP2 and SP2 (usually 180°). The output is the same signal, and on L3, the first H bridge arm includes transistor switches SS1 and SS2, and the second H bridge arm includes transistor switches SS3 and SS4, and the corresponding midpoint voltages at the first input terminal TP1 and the second input terminal TP2 are out of phase. Finally, the H-bridge output will be the difference between the voltage at TP1 and the voltage at TP2.

[0052] The microcontroller 50 can also send control signals to the gates of transistor switches SS1, SS2, SS3 and SS4. In this regard, transistor switches SS1 and SS4 form a first pair, which are activated together and turned on and off by the control signal at the same time. Similarly, transistor switches SS2 and SS3 form a second pair, which are activated together and turned on and off by the control signal at the same time. The first pair of transistor switches SP1 and SP4 and the second pair of transistor switches SP2 and SP3 are alternately started by the control signal. Therefore, the control signal of the first pair of transistor switches SP1 and SP4 is out of phase (usually 180°) with the second pair of transistor switches SP2 and SP3 (usually 180°). Although the present invention is not limited by the type and frequency of the control signal, a frequency of about 20 to 120kHz can be used. The control signal can be a square wave or any other suitable waveform.

[0053] refer to FIG. 4A to FIG. 6 , provides Figure 3The waveform of the converter is shown in which the primary 12 receives an input DC voltage and the secondary 14 outputs an output DC voltage. In particular, the input DC voltage can be a high voltage DC input (e.g., approximately 360 volts to 920 volts or approximately 170 volts to 470 volts.) and the output DC voltage can be a low voltage DC output (8 volts to 16 volts or 24 volts to 58 volts). In this variation, the first switch network 16 operates the input DC voltage (i.e., the first DC voltage VDC1) to form a first AC voltage VAC1 applied to the transformer 18. The transformer converts the first AC voltage VAC1 into a second AC voltage VAC2. The secondary winding of the transformer 18 and the second switch network are configured to convert the second AC voltage into a second DC voltage, and the current is established at least in part by the mutual inductance as described above. Figure 4A A graph of the primary side bus voltage and the half-bridge 1 output voltage ("pVHB1") is provided. Figure 4B Graphs of the primary side bus voltage and the primary half-bridge 2 output voltage ("pVHB2") are provided. Figure 4C Graphs of the primary side full-bridge output voltage (pVHB1-pVHB2) and the current through the transformer primary (I(L3)) are provided. Figure 5A Graphs of the secondary side bus voltage and the half-bridge 1 output voltage ("sVHB1") are provided. Figure 5B Graphs of the secondary side bus voltage and the half-bridge 2 output voltage ("sVHB2") are provided. Figure 5C Provides a graph of the full-bridge output voltage and the secondary-side full-bridge output voltage (sVHB1-sVHB2), and Figure 5D Provides a pass through Figure 3 The currents in the secondary of the transformer (I(L1) and I(L2)). Figure 6 Graphs of the primary side output voltage (pVHB1-pVHB2), the secondary side H-bridge output voltage, and the current through the transformer primary (I(L3)) are provided.

[0054] refer to 7A to 8D , provides Figure 3 The waveform of the converter is provided, wherein the secondary 14 receives the input DC voltage, and the primary 12 outputs the output DC voltage. In particular, the input DC voltage can be a low voltage DC input (e.g., 8 volts to 16 volts or 24 volts to 58 volts), and the output voltage can be a high voltage DC output (360 volts to 920 volts). In this variation, the input DC voltage is received by the secondary 14 at the terminal Tm of the secondary winding, and the second switch network 28 operated from the secondary side bus voltage converts the input DC voltage into a second AC voltage. The transformer 18 converts the second AC voltage into a first AC voltage. The first switch network 16 is then operated to convert the first AC voltage into an output DC voltage. Fig. 7AA graph of the half-bridge 1 output voltage ("pVHB1") is provided. Figure 7B A graph of the primary half-bridge 2 output voltage ("pVHB2") is provided. Figure 7C Graphs of the primary side full-bridge output voltage (pVHB1-pVHB2) and the current through the transformer primary (I(L3)) are provided. Fig. 8A Graphs of the secondary side bus voltage and the half-bridge 1 output voltage ("sVHB1") are provided. Figure 8B Graphs of the secondary side bus voltage and the half-bridge 2 output voltage ("sVHB2") are provided. Figure 8C A graph of the full-bridge output voltage (sVHB1-sVHB2) is provided. Fig.8D Provides a current through the transformer secondary ( Figure 3 Graph of I(L1) and I(L2)).

[0055] Although exemplary embodiments are described above, this does not mean that these embodiments describe all possible forms of the present invention. On the contrary, these words used in this specification are illustrative rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present invention. In addition, the features of different implementation embodiments can be combined to form other embodiments of the present invention.

[0056] According to an embodiment of the present invention, there is provided:

[0057] Item 1). A bidirectional or unidirectional DC-DC converter, which uses a dual active bridge rectifier topology, the bidirectional or unidirectional DC-DC converter converts an input DC voltage into an output DC voltage, the bidirectional or unidirectional DC-DC converter comprising:

[0058] a first switch network that receives or outputs a first DC voltage and a first AC voltage, the first switch network being configured to receive the first DC voltage and convert the first DC voltage into the first AC voltage or to convert the first AC voltage into the first DC voltage and output the first DC voltage; and

[0059] a second switch network in electrical communication with the secondary-side voltage bus; and

[0060] a transformer having a primary winding and a secondary winding, the transformer being configured to receive the first AC voltage and output a second AC voltage, or to receive the second AC voltage and output the first AC voltage, the secondary winding having a first end terminal, a second end terminal, and an output terminal located between the first end terminal and the second end terminal, the primary winding being in electrical communication with the first switch network, the second switch network being connected between the first end terminal and the second end terminal of the secondary winding,

[0061] wherein the secondary winding and the second switch network are configured to convert the second AC voltage into a second DC voltage or convert the second DC voltage into the second AC voltage, and

[0062] wherein the first switch network and the second switch network are operated so that a first current flows between the first end terminal of the secondary winding and the output terminal, a second current flows between the second end terminal of the secondary winding and the output terminal, and a third current flows through the primary winding, the first current, the second current and the third current being at least partially established by mutual inductance between the primary winding and the secondary winding, so that when the first DC voltage is the input DC voltage, the second DC voltage is the output DC voltage, and when the second DC voltage is the input DC voltage, the first DC voltage is the output DC voltage.

[0063] Item 2). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the first current is approximately equal to the second current multiplied by -1 plus an offset value.

[0064] Item 3). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the first current and the second current are combined to form an output DC current.

[0065] Item 4). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the output DC voltage is less than the input DC voltage.

[0066] Item 5). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the output DC voltage is greater than the input DC voltage.

[0067] Item 6). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the output DC voltage is half of the secondary bus voltage.

[0068] Item 7). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the first switching network is a first H-bridge circuit.

[0069] Item 8). A bidirectional or unidirectional DC-DC converter according to item 7), wherein the second switching network is a second H-bridge circuit.

[0070] Item 9). A bidirectional or unidirectional DC-DC converter according to Item 8), wherein the second switch network includes a first H-bridge arm and a second H-bridge arm, the first H-bridge arm includes a first transistor switch and a second transistor switch, and the second H-bridge arm includes a third transistor switch and a fourth transistor switch.

[0071] Item 10). A bidirectional or unidirectional DC-DC converter according to item 9), wherein, during operation, the same voltage polarity is provided to the output terminals of the transformer during the positive and negative parts of each cycle of the second AC voltage.

[0072] Item 11). The bidirectional or unidirectional DC-DC converter according to item 1) further includes a microcontroller configured to control the first switch network.

[0073] Item 12). A bidirectional or unidirectional DC-DC converter according to Item 11), wherein the microcontroller is further configured to control the second switch network.

[0074] Item 13). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the peak-to-peak value of the second AC voltage is from about 30 volts to 60 volts.

[0075] Item 14). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the peak-to-peak value of the second AC voltage is approximately 48 volts.

[0076] Item 15). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the input DC voltage is approximately 360V to 920V.

[0077] Item 16). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the input DC voltage is approximately 170 volts to 470 volts.

[0078] Item 17). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the output DC voltage is about 8 volts to about 16 volts.

[0079] Item 18). A bidirectional or unidirectional DC-DC converter according to item 1), wherein the output DC voltage is approximately 24 to 58 volts.

[0080] Item 19). A bidirectional or unidirectional DC-DC converter, which uses a dual active bridge rectifier topology, wherein the bidirectional or unidirectional DC-DC converter converts an input DC voltage into an output DC voltage, and the bidirectional or unidirectional DC-DC converter comprises:

[0081] a first switch network that receives or outputs a first DC voltage and a first AC voltage;

[0082] a second switch network in electrical communication with the secondary-side voltage bus; and

[0083] a transformer having a primary winding and a secondary winding, the secondary winding having a first end terminal, a second end terminal and an output terminal located between the first end terminal and the second end terminal, the primary winding being in electrical communication with the first switch network, the second switch network being connected between the first end terminal and the second end terminal of the secondary winding,

[0084] wherein the first switch network and the second switch network are operated so that a first current flows between the first end terminal of the secondary winding and the output terminal, a second current flows between the second end terminal of the secondary winding and the output terminal, and a third current flows through the primary winding, the first current, the second current and the third current being at least partially established by mutual inductance between the primary winding and the secondary winding, so that when the first DC voltage is the input DC voltage, the second DC voltage is the output DC voltage, and when the second DC voltage is the input DC voltage, the first DC voltage is the output DC voltage.

Claims

1. A bidirectional or unidirectional DC-DC converter, which uses a dual active bridge rectifier topology, wherein the bidirectional or unidirectional DC-DC converter converts an input DC voltage into an output DC voltage, wherein the bidirectional or unidirectional DC-DC converter comprises: a first switch network, the first switch network receiving a first DC voltage and outputting a first AC voltage or the first switch network receiving the first AC voltage and outputting the first DC voltage, the first switch network being configured to receive the first DC voltage and convert the first DC voltage into the first AC voltage or convert the first AC voltage into the first DC voltage and output the first DC voltage; a second switch network in electrical communication with the secondary-side voltage bus; as well as A transformer, comprising a primary winding and a secondary winding, the transformer being configured to receive the first AC voltage and output a second AC voltage, or to receive the second AC voltage and output the first AC voltage, the secondary winding comprising a first end terminal, a second end terminal, and an output terminal located between the first end terminal and the second end terminal, the primary winding being in electrical communication with the first switch network, the second switch network being connected between the first end terminal and the second end terminal of the secondary winding, wherein the secondary winding and the second switch network are configured to convert the second AC voltage into a second DC voltage or convert the second DC voltage into the second AC voltage, and wherein the first switch network and the second switch network are operated so that a first current flows between the first end terminal of the secondary winding and the output terminal, a second current flows between the second end terminal of the secondary winding and the output terminal, and a third current flows through the primary winding, the first current, the second current and the third current being at least partially established by mutual inductance between the primary winding and the secondary winding, so that when the first DC voltage is the input DC voltage, the second DC voltage is the output DC voltage, and when the second DC voltage is the input DC voltage, the first DC voltage is the output DC voltage.

2. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The first current is approximately equal to the second current multiplied by -1 plus an offset value.

3. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The first current and the second current combine to form an output DC current.

4. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The output DC voltage is less than the input DC voltage.

5. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The output DC voltage is greater than the input DC voltage.

6. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The output DC voltage is half of a secondary bus voltage of the secondary side voltage bus.

7. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The first switch network is a first H-bridge circuit.

8. The bidirectional or unidirectional DC-DC converter according to claim 7, wherein: The second switch network is a second H-bridge circuit.

9. The bidirectional or unidirectional DC-DC converter according to claim 8, wherein: The second switch network includes a first H-bridge arm and a second H-bridge arm, the first H-bridge arm includes a first transistor switch and a second transistor switch, and the second H-bridge arm includes a third transistor switch and a fourth transistor switch.

10. The bidirectional or unidirectional DC-DC converter according to claim 9, wherein: During operation, the same voltage polarity is provided to the output terminals of the transformer during the positive and negative portions of each cycle of the second AC voltage. 11 . The bidirectional or unidirectional DC-DC converter of claim 1 , further comprising a microcontroller configured to control the first switch network.

12. The bidirectional or unidirectional DC-DC converter according to claim 11, wherein: The microcontroller is further configured to control the second switch network.

13. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The peak-to-peak value of the second AC voltage is from 30 volts to 60 volts.

14. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The second AC voltage has a peak-to-peak value of approximately 48 volts.

15. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The input DC voltage is 360V to 920V.

16. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The input DC voltage is 170V to 470V.

17. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The output DC voltage is 8V to 16V.

18. The bidirectional or unidirectional DC-DC converter according to claim 1, wherein: The output DC voltage is 24 to 58 volts.

19. A bidirectional or unidirectional DC-DC converter, which uses a dual active bridge rectifier topology, wherein the bidirectional or unidirectional DC-DC converter converts an input DC voltage into an output DC voltage, wherein the bidirectional or unidirectional DC-DC converter comprises: a first switch network, wherein the first switch network receives a first DC voltage and outputs a first AC voltage or the first switch network receives the first AC voltage and outputs the first DC voltage; a second switch network in electrical communication with the secondary-side voltage bus; as well as A transformer comprising a primary winding and a secondary winding, wherein the transformer is configured to receive the first AC voltage and output a second AC voltage, or to receive the second AC voltage and output the first AC voltage, the secondary winding comprising a first end terminal, a second end terminal, and an output terminal located between the first end terminal and the second end terminal, the primary winding being in electrical communication with the first switch network, the second switch network being connected between the first end terminal and the second end terminal of the secondary winding, wherein the secondary winding and the second switch network are configured to convert the second AC voltage into a second DC voltage or convert the second DC voltage into the second AC voltage, and wherein the first switch network and the second switch network are operated so that a first current flows between the first end terminal of the secondary winding and the output terminal, a second current flows between the second end terminal of the secondary winding and the output terminal, and a third current flows through the primary winding, the first current, the second current and the third current being at least partially established by mutual inductance between the primary winding and the secondary winding, so that when the first DC voltage is the input DC voltage, the second DC voltage is the output DC voltage, and when the second DC voltage is the input DC voltage, the first DC voltage is the output DC voltage.

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