Ac-DC converter circuit

Abstract

To provide an AC-DC converter circuit for high power charging of a battery.SOLUTION: An AC-DC converter circuit includes: an input rectifier including first and second nodes; a first transistor including a first gate, a source node, and a drain node; a second transistor including a second gate, a source node, and a drain node; and a duty cycle control unit connected to the second gate node to provide a switching waveform to the second transistor. The input rectifier receives an AC voltage at the first node and provides a rectified voltage at the second node. The first drain node is connected to the second node of the input rectifier. The first gate node is connected to a ground node. The second drain node is connected to the first source node. An output rectifier connected to the second or first source node, and an output electron filter connected to the second source node or the output node of the output rectifier are further included.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to circuits and devices for converting alternating current (AC) to direct current (DC). In particular, it relates to AC-DC converter circuits for fast charging of electric vehicles and smartphones. [Background technology]

[0002] Electronic and electrical devices, tools, and vehicles often require batteries to store an electrical charge so that they can be used even when not directly connected to a power grid. Batteries can only be charged with direct current, but the power grid provides alternating current. Electric vehicles are equipped with an on-board charger inside the electric vehicle and can be charged with power, typically 6.6 or 22 kW, by connecting the on-board charger and the electric vehicle (EV) battery to the grid or mains power. To replenish the charge in an EV battery with power from the power grid, the current (or voltage) must first be converted from AC to DC. This conversion can be performed using an AC-DC converter circuit in the on-board charger. Because the size of the on-board charger is limited to fit inside the vehicle, the charging time of an electric vehicle is limited to a maximum of eight hours, a low-power charge. This is much longer than the typical time it takes to refuel a gasoline-powered vehicle. Instead, DC fast charging bypasses the low-power on-board charger, which performs the AC-DC power conversion external to the electric vehicle, at a much higher power (around 50 to 350 kW).

[0003] An AC-DC converter circuit, for example, includes a rectification section that rectifies the current and a buck-boost converter section that stabilizes the rectified current to a nearly constant level. A buck-boost converter typically includes a switching section that includes a switching transistor and a flywheel circuit section that can essentially average the current using the transient behavior of a capacitor and an inductance. The switching transistor typically receives a square wave at its gate, so that the transistor operates as a periodic switch of the rectified current. To achieve a more static output current, faster switching is desirable. However, the parasitic capacitance of the switching transistor reduces the switching speed and requires modifications to the flywheel circuit to achieve the static current. The parasitic capacitance also increases the heat loss per switching cycle and therefore reduces the conversion efficiency. Furthermore, the standard and commonly used silicon (Si)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) are reaching their limits in terms of scaling and switching speed for efficient power conversion. Thus, miniaturization of power electronics for high power applications is limited by typical silicon MOSFETs at slow switching speeds that require large, bulky, expensive, hand-made passive components. Such passive components add significant weight to EVs as well as on-board chargers. The same is true for wall chargers for smartphones and laptops, for example. However, incorporating different types of transistors made from different materials can pose integration challenges. Furthermore, there are issues associated with charging batteries at higher powers that have not yet been adequately fixed, such as battery heating, gas formation, and parasitic irreversible chemical reactions inherent to certain battery chemistries. Thus, there is room for improvement in the technology field to provide efficient and miniaturized power converters for high-power charging of batteries. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above, it is therefore an object of the present invention to alleviate at least some of the above-mentioned and other problems associated with AC-DC conversion. [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided an AC-DC converter circuit for high power charging of a battery. The circuit includes an input rectifier including a first node and a second node. The input rectifier is configured to receive an AC voltage at the first node and provide a rectified voltage at the second node. The circuit further includes a first transistor, the first transistor being a depletion type transistor and including a first gate node, a first source node, and a first drain node. The first drain node is connected to a second node of the input rectifier. The first gate node is connected to a ground node. The circuit further includes a second transistor including a second gate node, a second source node, and a second drain node. The second drain node is connected to the first source node. The second transistor materially corresponds to the first transistor. The circuit further comprises a duty cycle control unit connected to the second gate node for providing a switching waveform to the second transistor. The circuit further comprises an output rectifier connected to the second source node or the first source node. The circuit further comprises an output electronic filter connected to the second source node or the output node of the output rectifier.

[0006] The inventors realized that using a ground gate (first) transistor that is always on (transistor channel open) can reduce the parasitic capacitance of the second drain node (connected to the first source node). The first transistor essentially acts as a resistor with a certain resistance for conduction between the first drain node and the first source node. This can be attributed to a reduction in the effective node size. Thus, there is also an area that contributes to the parasitic capacitance, for example, between the second drain node and the second gate node. Reducing the parasitic capacitance can increase the switching speed of the second transistor. This is because the reduced parasitic capacitance needs to be charged before switching is completed. Also, the smaller the capacitance, the less time it takes to charge at the same voltage. This can also reduce heat losses and improve switching efficiency. Improved switching efficiency can also lead to improved AC-DC conversion efficiency and ultimately faster charging speeds of batteries, for example. Furthermore, high power conversion using switched mode power supplies requires low parasitic capacitance for efficient power conversion at high switching frequencies using the transistors used. The inventors have also realized that high power conversion can be provided by miniaturizing the AC-DC on-board power converter to fit efficiently within an electric vehicle. Increasing the switching frequency allows the size of the switching mode power supply to be reduced by reducing the size of the passive components (inductors, DC link capacitors). The range of an electric vehicle is weight sensitive, and batteries are already a large contributor to this weight. Therefore, any source to reduce that weight is desirable. Furthermore, the inventors have also realized that using similar materials and device designs to form the two transistors may simplify integration and improve the prospects for device downscaling and miniaturization of the AC-DC power converter. For example, devices using the same materials can be manufactured simultaneously with the same processing steps.Devices can also be fabricated in close proximity to one another, since transition, buffer, and / or spacer structures that would otherwise be required to incorporate devices of different materials can be avoided. Ground-gate transistors offer particular advantages when compared to conventional resistors, which can be difficult to realize and integrate efficiently on a microelectronic scale.

[0007] The terms current and voltage can refer to electrical signals between the same nodes in a circuit. In such cases, they need to be understood as being interrelated by applying Ohm's law. The term alternating current (AC) voltage may refer to a peak amplitude voltage (absolute or non-absolute), a peak-to-peak voltage, a root mean square (RMS) voltage, or other ways of referring to an oscillating voltage. Thus, the term direct current (DC) voltage may refer to a voltage level that is substantially static, or at least a voltage level that is free of substantial periodic oscillations. The term rectified voltage may refer to a voltage level that still has periodicity or some sort of transient behavior, but does not switch polarity. AC-DC conversion means that any AC voltage is converted to any DC voltage, i.e. the voltage level can change.

[0008] The term rectifier may refer to any device or circuit that transmits electric current in only one direction. A diode is a simple example of a rectifier device. The term transistor refers to an electrical switch that conducts between a source node and a drain node based on an electrical signal (such as a voltage) at a gate node. There are many different types of transistors, such as the already mentioned MOSFET, bipolar junction transistor (BJT), and high electron mobility transistor (HEMT), also known as heterojunction field effect transistor (HFET). Variations in operation and requirements vary from one type of transistor to another. Generally, transistors are formed by crystalline semiconductor materials that are doped with impurities to achieve conditional conductivity. Transistors are generally based on semiconductor substrates and are integrated together to form advanced electronic digital and analog circuits. Many transistor types, such as MOSFETs and HEMTs, may have drain-source symmetry. This means that what is called the drain and source simply follows convention. For example, reversing the source and drain connections. A regular MOSFET in a circuit may not affect the operation of the circuit. The phrase that transistors correspond materially to each other may be understood as transistors that contain the same materials or are at least based on similar material systems.

[0009] The term duty cycle control unit may refer to a device that outputs a periodic waveform, such as a square wave. The ratio of the duration of the high and low portions of the waveform may be used to control the output DC level. The duty cycle control unit may be adapted to modify the waveform based on a measured DC voltage output by the circuit. Using the duty cycle control unit to switch a second transistor may be advantageous as it may control the DC output to achieve constant current or constant voltage functions, for example. The term electronic filter may refer to a single component or small part of a circuit that serves as a way to filter an electrical signal based on a parameter such as frequency. For example. inductors and capacitors can be used in electronic filters. Because the charging action of inductors and capacitors is temporary, circuits that include them respond differently to changes in frequency signals. This can be used to create low pass, high pass, and band pass filters, for example.

[0010] The term node should be understood to refer to an electrical node in a circuit that is characterized by a charge, a voltage value, or a current flowing through it. Most commonly, a node refers to a metal interconnect node between devices and components in a circuit, although a node can be understood in other ways. For example, a portion or mass of semiconductor material may function as a node in some embodiments.

[0011] According to some embodiments, both the first and second transistors are HEMTs. Alternatively, either the first or second transistor can be a HEMT. However, embodiments in which both transistors are HEMTs allow the two to be integrated simultaneously and adjacently. HEMTs generally provide better electron transport, as the name suggests, and therefore allow higher currents for the same volume of semiconductor material. This can be attributed to HEMTs utilizing a so-called two-dimensional electron gas (2DEG) at the interface between the carrier layer and the barrier layer. Compared to MOSFETs, which use an oxide for the layer closest to the barrier layer, the barrier layer of a HEMT is often a semiconductor with a larger bandgap than the carrier layer. The 2DEG improves electron transport because the essentially two-dimensional plane increases the mean free path (MFP) of charge carriers, e.g., electrons between the source and drain regions of a transistor.

[0012] According to some embodiments, the first and second transistors are gallium nitride transistors. Alternatively, either the first or second transistors can be gallium nitride transistors. The term gallium nitride transistor may refer to various types of transistors, such as MOSFETs or HEMTs, characterized by or based on materials in the gallium nitride (GaN) or III-nitride (III-N) material systems. The term may further refer to the carrier or channel layer of the transistor, including GaN. An embodiment in which both transistors are gallium nitride transistors allows the two to be integrated simultaneously and adjacently. Gallium nitride transistors may be advantageous due to the inherent material properties of GaN. GaN has superior electron mobility compared to silicon, providing more efficient conduction with lower heat loss. GaN devices, such as transistors, can be made smaller than their Si counterparts while still maintaining performance. Thus, GaN devices may be less expensive to manufacture. GaN devices generally exhibit higher breakdown voltages than Si devices, making them suitable for high voltage applications, such as charging electric vehicle batteries at around 400V. GaN devices may enable higher switching frequencies than Si devices. GaN transistors may also offer more efficient switching than Si devices. GaN transistors can be advantageous for high power conversion applications.

[0013] High power conversion is what causes large switching losses at high frequencies in silicon transistors from a thermal standpoint. Higher power during switching with silicon transistors requires larger and bulkier capacitive and inductive components. To achieve fast switching, the parasitic capacitances must be reduced, otherwise there will be delays in the switching time. According to some embodiments, the input rectifier is a half-wave rectifier that includes at least one diode. A half-wave rectifier is a rectifier that transmits half the AC voltage, i.e., either negative or positive. Such a rectifier can be very small and of low complexity.

[0014] According to some embodiments, the input rectifier is a full-wave rectifier including at least two diodes. The input rectifier further includes a third node. The input rectifier is configured to receive an AC voltage between the first node and the third node. A full-wave rectifier is a rectifier that transmits half of the AC voltage as is, converts the other half to the same polarity, and also transmits the converted half. Alternatively, a full-wave rectifier can be considered as outputting the absolute value of the input AC voltage over time. Thus, a full-wave rectifier typically rectifies more of the initial AC voltage. Thus, more electrical energy is also converted. A full-wave rectifier, which is generally larger than a half-wave rectifier, can still be relatively small (e.g., using two or four diodes) and less complex. Full-bridge and diode bridge are alternative nomenclatures related to full-wave rectifiers that use four or more diodes arranged in a bridge circuit.

[0015] According to some embodiments, the AC-DC converter circuit further includes a control circuit for monitoring the output voltage level. The control circuit is configured to provide feedback to the duty cycle control unit based on the monitored output voltage level. Control circuit feedback can be used to set and stabilize the output DC voltage level of the AC-DC converter circuit to a desired fixed voltage level.

[0016] According to some embodiments, the first transistor and the second transistor are monolithically integrated on the same substrate layer structure. Monolithic in this regard refers to the transistors being formed being integrated on the same semiconductor substrate (e.g., wafer), thereby reducing the size and cost of the circuit. Furthermore, the monolithic integration of the two transistors allows for a reduction in the size of the intermediate node (first source node / second drain node), thus further reducing the associated parasitic capacitance.

[0017] According to some embodiments, the substrate layer structure includes a silicon substrate layer. Silicon (Si) substrates, e.g. wafers, are generally cheap and easy to manufacture. Because Si is the baseline for the electronics industry, it would be advantageous to incorporate AC-DC converter circuits onto such substrates for tighter integration with other circuits and electronics. This also applies to non-Si based devices. GaN-based devices, especially conventional GaN devices, require expensive and complex substrate materials such as sapphire (α-Al2O3) or silicon carbide (SiC). According to some embodiments, the output rectifier is a gallium nitride diode. The input rectifier diodes, if present, are gallium nitride diodes. This can be especially advantageous when GaN transistors are used as diodes and the transistors are packed more tightly together. For example, a diode and a transistor may be formed in parallel on the same semiconductor material in this manner.

[0018] According to some embodiments, the first transistor includes a first carrier layer structure over the substrate layer structure and a first barrier layer structure over the first carrier layer structure. A first gate node and a first drain node are disposed over the first barrier layer structure. The nodes are physically separated by spacer structures. Similarly, the second transistor includes a second carrier layer structure over the substrate layer structure and a second barrier layer structure over the second carrier layer structure. A second gate node and a second source node are located over the second barrier layer structure. The nodes are physically separated by spacer structures. The first and second carrier layer structures include a first semiconductor material. The first and second barrier layer structures include a second semiconductor material.

[0019] The carrier and barrier layer structures should be understood to include different semiconductor materials. The term spacer structure should be understood as a substantially non-conductive physical structure, such as a dielectric. By arranging the layer structures, nodes and spacers accordingly, a HEMT or HFET device can be formed.

[0020] According to some embodiments, the first carrier layer structure is physically separated from the second carrier layer structure by a spacer structure. The first barrier layer structure is physically separated from the second barrier layer structure by the same spacer structure. As such, interference and / or leakage between the two devices can be minimized.

[0021] According to some embodiments, the first carrier layer structure is connected to a second carrier layer structure. Similarly, the first barrier layer structure is connected to the second barrier layer structure. The complexity of such devices may be reduced, and the manufacturing complexity may be reduced, for example, as follows. This is because etching of the semiconductor and formation of trenches can be avoided. This is particularly advantageous for GaN-based devices.

[0022] According to a second aspect of the present invention there is provided an AC-DC converter device including an AC-DC converter circuit according to the first aspect. The apparatus further comprises an interface for receiving an AC voltage from an AC voltage source and an interface for providing a DC voltage to the battery. The battery may be an electronic vehicle battery or a mobile electronic device battery.

[0023] Such a device is advantageously suitable for charging batteries. Furthermore, all the above improvements in AC-DC conversion efficiency of the converter circuit are carried over to the AC-DC converter device. Two-phase charging, ie, an initial period of constant current charging followed by a period of constant voltage charging, can be advantageous as it provides fast battery charging without overstressing the battery. Such two-phase charging can be adopted by the proposed AC-DC converter device. The device (and converter circuit) can be configured for two-phase (constant current, constant voltage) charging. The AC input and DC output interface can be understood in its simplest form as an electrical terminal node. The input interface may be suitable for receiving an AC voltage, for example from a power grid.

[0024] AC-DC converter devices can be configured to provide a DC voltage to an electric vehicle battery. Efficient conversion of AC to DC is advantageous for charging electric vehicle (EV) batteries. Improved GaN devices have the potential to provide faster charging with higher power devices. GaN devices are further advantageous because they can be miniaturized, improving on-board charging circuitry in EVs, allowing for faster and more efficient charging using existing power grid infrastructure.

[0025] The AC-DC converter device is configured to provide a DC voltage to a battery of a mobile electronic device. The term mobile electronic device may refer to, for example, a mobile phone, a laptop computer, a tablet, a remote control, a calculator, etc. Those skilled in the art will appreciate that the above list is not exhaustive and similar devices with batteries, for example, data processing capabilities may be considered. We can expect the same benefits as EVs. In particular, the prospect of smaller and / or more efficient devices may be advantageous.

[0026] According to a third aspect of the present invention, there is provided a method for charging a battery of an electric vehicle, the electric vehicle including, in addition to the battery, a traction motor and an AC-DC converter circuit of the first aspect. The method comprises: Slowing down the movement of electric vehicles; generating an alternating current from the traction motor by decelerating the motion of the electric vehicle; Converting the generated alternating current into a direct current by an AC-DC converter circuit; and charging the battery with a DC type current.

[0027] According to a second aspect of the present invention, there is provided a regenerative braking system for an electric vehicle, the regenerative braking system comprising: Batteries and a traction motor adapted to generate an AC type current; a braking system adapted to decelerate the electric vehicle; an AC-DC converter circuit according to the first aspect configured to convert an AC type current from a traction motor to a DC type current for charging a battery; and a DC-AC converter circuit configured to convert a DC type current from the battery to an AC type current to power the traction motor. [Brief description of the drawings]

[0028] The above, as well as additional objects, features and advantages of the present invention will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the invention, with reference to the accompanying drawings. Numbers are used for similar elements. [Figure 1] FIG. 1 shows a basic schematic diagram of an AC-DC converter circuit according to a first embodiment in a step-down configuration. [Diagram 2]FIG. 2 also provides a more detailed schematic diagram of a circuit according to the first aspect configured with some optional features of the embodiments. [Diagram 3] FIG. 3 shows a schematic cross-sectional view of a semiconductor layer structure and device according to an embodiment. [Figure 4] FIG. 4 shows a schematic cross-section of a semiconductor layer structure and device according to a further embodiment. [Diagram 5] FIG. 5 shows a schematic cross-sectional view of a semiconductor layer structure in which transistors are co-located as a dual gate device. [Figure 6] FIG. 6 shows a schematic diagram of an AC-DC converter device according to a second embodiment. [Figure 7] FIG. 7 illustrates a flow chart of a method for charging a battery in an electric vehicle. [Figure 8] FIG. 8 illustrates a block schematic diagram of a regenerative braking system for an electric vehicle. [Figure 9] FIG. 9 shows a basic schematic diagram of an AC-DC converter circuit according to a first embodiment in a boost configuration. [Figure 10] FIG. 10 also presents a more detailed schematic diagram of a circuit according to a first aspect that is boost configured with some optional features of the embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. The systems and devices disclosed herein are described in operation.

[0030] Both Figures 1 and 2 show a schematic diagram of an AC-DC converter circuit 100, although at different levels of detail. 1 and 2 particularly show a step-down AC-DC converter circuit 100. As shown in FIG.

[0031] The circuit 100 can convert an AC voltage (or current) into a stable, substantially static DC voltage (or current). The AC voltage can take the form of a sinusoidal voltage oscillating at 45 to 65 Hz. Preferably, the vibration is substantially at either 50 or 60 Hz. The voltage level may oscillate around 0 V or another fixed (DC) voltage offset. The AC voltage may have an RMS value between 100 and 500 V. Preferably, the AC voltage has an RMS value averaged at substantially or about 110 V, 115 V, 220 V, 230 V, 380 V, or 400 V. For clarity and to avoid tautologies, DC type current may be used to refer to direct current and AC type current may be used to refer to alternating current.

[0032] The circuit 100 includes an input rectifier 110 configured to rectify an AC voltage received at a first node 112. The first node 112 may function as an input node for the input rectifier 110. The input rectifier is connected to an operative third node 116. The AC voltage may be received only at the first node 112 or between the first node 112 and a third node 116. The input rectifier 110 provides a second rectifier voltage (or current) at a node 114, which serves as an output node of the input rectifier 110. The input rectifier 110 may include one or more diodes, more preferably two or more diodes, and most preferably four or more diodes. The input rectifier 110 may be a half-wave or full-wave rectifier. The input rectifier 110 may comprise a diode bridge, i.e., four diodes connected in series. The diodes may be arranged to form two parallel paths, both conducting from the ground node 170 to the second node 114, with the first node 112 and the third node 116 connecting between the diodes of either path. Such an input rectifier is illustrated in FIG. 2.

[0033] 2, if an AC voltage with no DC component is connected between the first node 112 and the third node 116, during the first half of the AC wave cycle, the absolute value of the oscillating current will be transferred through either the top or bottom path of the input rectifier 110. During the second half of the AC wave cycle, the absolute value of the oscillating current will be transferred through the other path of the input rectifier 110. Thus, the voltage may be rectified to have the same polarity when it exits the input rectifier at the second node 114.

[0034] Further alternatives for the input rectifier 110 may include, for example, a center tapped rectifier including two diodes, or a voltage doubler circuit including one or two diodes.

[0035] The diodes of the input rectifier 110 may be gallium nitride (GaN) diodes. The diodes may be based on semiconductor pn junctions. A pn junction is essentially a transition between two semiconductor materials doped with different atomic impurities. Dopant impurities are used to introduce charge carriers (electrons and holes) into the semiconductor material. For silicon (Si) diodes, p-type dopants may include, for example: boron (B) and n-type dopants may include nitrogen (N) or phosphorus (P). For GaN diodes, p-type dopants may include magnesium (Mg) and n-type dopants may include carbon (C) or Si. The diodes referred to herein for the input rectifier 110 may preferably be Schottky diodes. Schottky diodes may alternatively be referred to as Schottky barrier diodes or hot carrier diodes. Schottky diodes differ from normal pn junction diodes by being formed as a semiconductor junction with a metal. Schottky diodes feature low forward voltage drop and very fast switching operation. This low forward voltage requirement allows for higher switching speeds and better system efficiency.

[0036] In some embodiments, the diode may be formed on a GaN-on-Silicon substrate. For Schottky diodes, the substrate consists of a metal-containing AlGaN / GaN / Si heterostructure. On top of the AlGaN / GaN / Si, a Pd / Au Schottky diode contact metal structure can be provided. Ohmic contacts of Ti / AlCu / Ni / Au may also be provided, where AlCu is an aluminum copper alloy. In the case of a pn junction, the substrate comprises a p-GaN / n-GaN homojunction.

[0037] In some embodiments, it is preferred that four Schottky diodes or p-GaN / n-GaN homojunctions are integrated on the same GaN-on-Silicon substrate to form a diode bridge on the substrate.

[0038] The circuit 100 further includes a first transistor 120. The first transistor includes a first gate node 122, a first source node 124, and a first drain node 126. The circuit 100 further includes a second transistor 130. The second transistor includes a second gate node 132, a second source node 134, and a second drain node 136. The first transistor 120 and the second transistor 130 may be collectively referred to as transistors 120, 130. The transistors 120, 130 may be in depletion mode (normally on) or enhancement mode (normally off). The transistors 120, 130 may be Si-based transistors, GaN-based transistors, SiC-based transistors, or any combination of the above.

[0039] The transistors 120, 130 may be MOSFETs. MOSFETs may feature gate oxides including, for example, silicon oxide (SiOx) and / or hafnium oxide (HfOx) and / or aluminum oxide (AlOx). MOSFETs may feature doped semiconductor regions. MOSFETs are either positive channel (PMOS) or negative channel (NMOS) devices. The transistors 120, 130 may also be a HEMT / HFET or any combination of a HEMT and a MOSFET. A HEMT may include a carrier layer and a barrier layer on the carrier layer. 3, 4 and 5 all show schematic cross-sectional views of a transistor that is a HEMT / HFET type device including (first and second) carrier layer structures 224, 234 and barrier layer structures 226, 236 on top of the (first and second) carrier layer structures 224, 234. A 2DEG may be formed on the carrier layer structure side of the interface between the carrier layer structures 224, 234 and the barrier layer structures 226, 236. A thick straight arrow (based on the text orientation) in the upper left corner of each figure indicates the bottom-to-top direction, i.e., the direction of device fabrication starting from the substrate underneath. As with MOSFETs, HEMTs may also have a gate oxide. The gate oxide of the HEMT may be intermediate the gate nodes 122,132 and the barrier layer structures 226,236.

[0040] 3 shows a first transistor 120 comprising a first carrier layer structure 224 disposed on a substrate layer structure 290 and a first barrier layer structure 226 disposed on the first carrier layer structure 224. A first gate node 122, a first source node 124, and a first drain node 126 are shown disposed on the first barrier layer structure 226. The first gate node 122 is shown located between the first source node 124 and the first drain node 126. The nodes are shown physically and spatially separated by a spacer structure 250. The physical spacing imposed by the spacer structure 250 should be in the range of, for example, 1 nm to 1 μm.

[0041] FIG. 3 further illustrates a second transistor 130 comprising a second carrier layer structure 234 disposed on the substrate layer structure 290 and a second barrier layer structure 236 disposed on the second carrier layer structure 234. A second gate node 132, a second source node 134, and a second drain node 136 are shown disposed on the second barrier layer structure 236. The second gate node 132 is shown located between the second source node 134 and the second drain node 136. The nodes are shown physically and spatially separated by a spacer structure 250. The physical spacing should be in the range of, for example, 1 nm to 1 μm, similar to the first transistor 120.

[0042] The substrate layer structure 290 may include a silicon (Si) substrate layer. The Si substrate layer may be substantially single crystalline. The substrate layer structure 290 may be a wafer having a diameter between 1 inch and 20 inches. The transistors 120, 130 may be monolithically integrated on the same substrate layer structure 290. The substrate layer structure 290 may include several sub-layers, such as a buffer layer, a transition layer, and a capping layer. The substrate layer structure 290 may feature layers configured to match material parameters, such as thermal expansion coefficients, and to be lattice-mismatched with the interface between the substrate layer structure 290 and the carrier layer structures 224, 234. One such layer may include a transition layer reinforced with nanowire arrays. The nanowires may be GaN nanowires, and the transition layer may enable improved GaN crystal quality and device performance relative to the carrier layer structures 224, 234 described above.

[0043] The carrier layer structures 224, 234 may include a first semiconductor material. The carrier layer structures 224, 234 may at least partially comprise or substantially comprise a first semiconductor material. The barrier layer structures 226, 236 may include a second semiconductor material. The barrier layer structures 226, 236 may at least partially comprise or substantially comprise a second semiconductor material.

[0044] JPEG2025063182000002.jpg36161

[0045] FIG. 3 shows that the first and second carrier layer structures 224, 234 are physically separated from each other by a spacer structure 250. The figure further shows the first and second barrier layer structures 226, 236, which are physically separated from each other by the same spacer structure 250. The spacer structure 250 between the two transistors can be formed, for example, by etching trenches in the first and second semiconductor materials and depositing a spacer material. The physical spacing imposed by the spacer structure 250 should be, for example, in the range of 1 nm to 1 μm.

[0046] The spacer structure 250 discussed herein may generally refer to a layer of non-conductive (insulating) material that functions as a physical spacer, passivation, and isolation structure. Examples of materials that can be used include dielectric materials and oxides such as SiOx (e.g., SiO2) or silicon nitride Si3N4. Dielectric materials with low κ values, i.e., materials with low relative permittivity or dielectric constant, are desirable. For example, a spacer structure of a low κ material may reduce parasitic capacitance on the spacer structure compared to fabricating the spacer structure with a material with a higher κ value. The spacer structure 250 may be an air gap or vacuum gap to achieve the lowest possible κ value, i.e., approaching 1, thus reducing parasitic capacitance on the spacer structure 250. Parasitic capacitance is the capacitance between the gate node 132 and the source node 134 (C gs ) and / or between the gate node 132 and the drain node 136 (C gd ) and / or between the gate node 132 and the semiconductor bulk (C gb The semiconductor bulk may refer to, for example, the barrier layer structures 226, 236 and / or the carrier layer structures 224, 234 and / or the substrate 290.

[0047] The gate, source and drain nodes of the transistors 120, 130 may be formed of a conductive material, such as a metallic material or a degenerately doped semiconductor material. Examples of node materials include copper (Cu), aluminum (Al), titanium (Ti), nickel (Ni), gold (Au), silver (Ag), wolfram or tungsten (W), and alloys of all of the above. Further examples include polycrystalline Si and titanium nitride (TiN).

[0048] FIG. 4 shows an alternative embodiment that does not have a spacer structure between the first and second carrier and barrier layer structures. Thus, the first carrier layer structure 224 and the second carrier layer structure 234 form a common carrier layer structure 224, 234. Similarly, the first barrier layer structure 226 and the second barrier layer structure 236 form a common barrier layer structure 226, 236.

[0049] FIG. 5 shows a schematic cross-sectional view of two transistors co-located to form a single dual-gate device. In this figure, the intermediate nodes 124, 136 are disposed within combined carrier layer structures 224, 234. Such a device may provide beneficial behavior as the intermediate nodes 124, 136 may be miniaturized with the effect of lower parasitic capacitance.

[0050] The first transistor 120 is coupled to a first gate node 122 and a ground node 170, or another ground node. The circuit does not have to share the same ground node 170, but in many embodiments and figures it does. When the first gate node 122 is connected to ground, the first transistor 120 essentially becomes a passive device. As such, the transistor is always on or off depending on the operation of the transistor. Thus, the first transistor 120 may preferably be a depletion mode (normally on) transistor. The first transistor 120 may then be characterized by a value of on-state resistance (Ron). The on-state resistance may refer to the electrical resistance between the first source node 124 and the first drain node 126. Thus, the first transistor 120 may function as a resistor that may be miniaturized for integration with other passive and active microelectronic components on a chip. The ground node 170 may be set to 0V DC. Alternatively, a static DC voltage offset can be connected to the first gate 122 to make using at least the first transistor 120 in enhancement mode more viable.

[0051] In the circuit 100, the first drain node 126 is connected to the second node 114, which is the output node of the input rectifier 110. The first source node 124 is connected to a second drain node 136. The transistors 120, 130 can be understood to be connected in series.

[0052] The circuit 100 further comprises a duty cycle control unit 140. The duty cycle control unit 140 is connected to the second gate node 132. The duty cycle control unit 140 is configured to provide a switching waveform to the second transistor 130. The switching waveform can be in the form of a square wave transient voltage or an AC voltage. Other waveforms, such as sinusoidal waveforms, can also be used. A square wave should be understood as being substantially square, i.e. having very high frequency edges. A square wave can also be described as having very fast rise and fall times. The waveform may feature various ratios between the duration of high and low levels, which can be used to control the output DC voltage level by step-down conversion. For example, if the waveform has a 1:1 ratio of high to low duration, the voltage may be stepped down to half the input voltage. This is desirable because the direct voltage levels of the grid may be too great for efficient and / or safe and / or practical charging of batteries. Through the duty cycle control unit 140, the DC voltage step-down can be varied throughout the charging process. The ratio of input voltage to output voltage is sometimes called the step-down ratio. The second transistor 130 may be referred to as a switching transistor 130 because it performs switching inversely to the typical operation of the ground-gated first transistor 120 . One or both of the transistors 120, 130 may be nanowire transistors with wrap gate nodes 122, 132.

[0053] The circuit 100 further includes an output rectifier 150 connected to the second source node 134 (buck configuration, see FIGS. 1-2) or the first source node 124 (boost configuration, see FIGS. 9-10). The output rectifier 150 includes at least one diode. The output rectifier 150 may be, more specifically, a GaN diode. The output rectifier 150 may be a Schottky diode. Schottky diodes generally feature a lower forward voltage drop compared to normal pn junction diodes, which may lead to faster recovery times and increased efficiency of the output rectifier 150 and / or the AC-DC converter circuit 100. The same advantages may apply if a Schottky diode is used for the input rectifier 110. The output rectifier 150 can be connected to conduct electricity from the ground node 170 to the second source node 134. It should be noted that when referring to electrical conduction directions herein, they should be understood as the direction opposite to the direction of current flow, i.e., the flow of electrons. By providing a conductive path from the ground node 170 to the second source node 134, the output rectifier 150 prevents potentially destructive charge from building up at the second source node 134 when the switching transistor 130 is switched off.

[0054] The circuit 100 further comprises an output electronic filter 160 connected to the second source node 134 (buck configuration, see Figures 1-2) or to the output node 151 of the output rectifier 150 (boost configuration, see Figures 9-10). The output electronic filter 160 may comprise an inductor and a capacitor as shown in Figure 2. The inductor and capacitor may be connected in series. The output electronic filter 180 may further comprise a resistor or a transistor arranged as a resistor. The inductor and capacitor may be formed by conventional microelectronic fabrication methods, for example during back-end-of-line processing (BEOL).

[0055] The output electronic filter 160 and output rectifier 150 together are sometimes referred to as a flywheel circuit, because of their similarity in function to a mechanical flywheel that maintains momentum in a cycle to which energy is only intermittently added. The transient action of the inductor and capacitor charges when the switching transistor is turned on, and releases charge when the switching transistor is turned off. Thus, an essentially static output DC voltage is achieved.

[0056] The output DC voltage of the circuit 100 can be extracted from the node between the inductor and the capacitor, or the output DC voltage of the circuit can be understood as the voltage across the capacitor and extracted at the terminal nodes on either side of the capacitor.

[0057] The circuit 100 may further comprise an input electronic filter, as shown in Fig. 2. In this figure, the input electronic filter is realized as a capacitor between the second node 114 and the ground node 170. The input electronic filter may function as a reservoir capacitor that functions to smooth the rectified voltage at the second node 114 to a relatively static level. The input electronic filter may further comprise an inductor and / or a resistor. The resistor may be realized as a transistor arranged as a resistor.

[0058] The circuit 100 may further include a control circuit 180 for monitoring the output voltage level. The control circuit 180 may be configured to provide feedback to the duty cycle control unit 140 based on the monitored output voltage level. The control circuit 180 may, for example, provide feedback or instructions to the duty cycle control unit 140 related to the required DC voltage drop.

[0059] In FIG. 2, the control circuit 180 is shown to connect to the DC output terminals of the circuit 100 and to the duty cycle control unit 140. The control circuit 180 may be a feedback circuit, such as a negative feedback circuit. The control circuit 180 may comprise at least one operational amplifier (OP-amp). The control circuit 180 may further include a proportional integral derivative controller (PID controller). Alternatively, the control circuit 180 may include only a portion of a PID controller, such as a P, I, D, PI, ID, or PD controller. The control circuit 180 may be a simple electronic circuit or an integrated circuit with digital computing and / or data processing capabilities.

[0060] The AC-DC converter circuit 100 can be described as a buck converter circuit. Alternatively, the AC-DC converter circuit 100 can be a boost converter circuit. The AC-DC converter circuit 100 can also be a combination of both, i.e., a buck-boost converter circuit.

[0061] Generally, boost and buck converters refer to DC-DC converter circuits with voltage regulation with step-up and step-down functions, respectively. The AC-DC converter circuit 100 can be understood as a DC-DC buck converter with an input rectifier 110, such as a diode bridge composed of four GaN diodes.

[0062] A step-down converter circuit may be preferred for charging smartphone batteries. Such a converter may preferably be configured to step down and convert an input voltage of 230V AC to an output voltage of approximately 9V DC.

[0063] A boost converter circuit may be preferred for charging the batteries of electric vehicles. Such a converter may be preferably configured to boost and convert an input voltage of 230V AC to an output voltage of about 300-400V DC.

[0064] As mentioned above, Figures 1 and 2 show a step-down AC-DC converter circuit. Figures 9 and 10 show a boost converter circuit, characterized in that an output rectifier 150 is connected to nodes 124, 136 intermediate the two transistors 120, 130. An output filter 160 is connected to the output node 151 of the output rectifier in such an embodiment. The second source node 134 may be connected to a ground node 170 in such an embodiment.

[0065] 6 shows the circuit 100 included in an AC-DC converter device 300. The device 300 further comprises an interface for receiving an AC voltage 311 from an AC voltage source 310, and an interface for providing a DC voltage 312 to a battery 320.

[0066] The AC voltage source 310 may be understood as a distribution point for distributing an AC voltage from a power grid, such as an electrical wall outlet. The interface for receiving the AC voltage 311 may be understood as a socket plug connection including at least one, preferably at least two conductive connectors. The interface for supplying the DC voltage 311 may be understood as at least one conductive connector.

[0067] Battery 320 may be understood as any secondary, i.e., rechargeable, battery. Battery 320 may further be understood as any electrochemical device or cell for storing electrical energy in a chemical form, such as a lead-acid battery, a lithium-ion battery, or a nickel-metal hydride battery (NiMH).

[0068] An electrochemical cell consists of three parts, an anode, an electrolyte, and a cathode. An example of an electrochemical cell for a lithium-ion battery can be described as follows: [LiC / / polymer gel / / CoO2+polymer] There are two half-cell reactions at the anode and cathode. Anode: LixC6(s) = xLi + 6C + xe- Cathode: xLi + + CoO2(s) + xe- = LixCoO2(s)

[0069] In the above, x corresponds to an integer variable, for example, Li corresponds to the element lithium, C corresponds to the element carbon, O corresponds to the element oxygen, Co corresponds to the element cobalt, e- corresponds to an electron, and (s) indicates that the compound is a solid.

[0070] The chemical reactions that govern the charging of a battery are described by the Gibbs free energy ΔG. In the case of a battery, the Gibbs free energy is the driving force for the chemical reactions given by the Nernst equation:

number

number

number

[0071] The current density i of a battery half-cell reaction according to the Tafel equation can be written as follows:

number

[0072] In the following, the reduction of heat generation for fast charging of a battery according to the present invention will be described. The heat generated in a battery is mainly due to the capacitive nature of the battery. The Norton equivalent circuit charging impedance model of a battery has an impedance that can be described as:

number

[0073] The charging rate of a battery can be determined from the C rating, which represents the time to charge and discharge the battery taking into account the internal resistance. The charging times for a 1C-rated and a 4C-rated battery are 1 hour and 7.5 minutes, respectively. According to the present invention, this charging time can be further reduced by controlling the DC waveform for charging the battery.

[0074] The AC voltage can take the form of a sinusoidal voltage oscillating at 45 to 65 Hz. Preferably, the oscillation is substantially at either 50 or 60 Hz. The voltage level may oscillate around 0 V or another fixed (DC) voltage offset. The RMS value of the AC voltage is between 100 V and 500 V. Preferably, the AC voltage has an RMS value of substantially or on average about 110 V, 115 V, 220 V, 230 V, 380 V, or 400 V.

[0075] The DC voltage may preferably be a static voltage in the range 0-500V. The DC voltage may more preferably be in the range 1-100V. The DC voltage may most preferably have a value substantially equal to or around 1.5, 3, 3.7, 4, 5, 6, 12, 24, 48 or 96V. However, for applications significantly higher voltages may be considered, e.g. AC voltages up to 30kVRMS or 5kVDC for electrified railway applications. The DC voltage must be understood as a transient voltage and can be varied with different step-down ratios to optimize charging. DC voltages may be pulsed. Pulsed DC voltages (or currents) are distinguishable from AC voltages (or currents) because they have very short rise and fall times. A pulsed DC signal over time is ideally exemplified by, for example, a near discrete Heaviside step function.

[0076] The device 300 may be configured to provide a DC voltage to a battery 320 of an electric vehicle (EV) or mobile electronic device. An EV may be a personal transportation vehicle, such as a car, motorcycle, scooter, moped, bicycle, or similar vehicle. Alternatively, an EV may be a commercial vehicle, such as a truck, delivery vehicle, or similar vehicle. Alternatively, an EV may be an industrial character, such as a mobile machine, industrial equipment, construction vehicle, tractor, or similar vehicle. Alternatively, an EV may be understood as an alternative form of transportation, such as a watercraft, aircraft, or rail vehicle (e.g., train). To charge an EV, the control circuit 180 may be configured to regulate the output current for constant current operation (i.e., the current level is constant and the voltage level is transient) or constant voltage operation (i.e., the voltage level is constant and the current level is transient). These two types of operation may be utilized for two-phase charging of a battery, which is further described elsewhere herein. The output current of the AC-DC converter circuit 100 may be configured to be in the range of 300-500 A when charging the battery 320 of the EV. The circuit 100 may further be configured for a single-phase AC input as well as a multi-phase AC input, such as a two-phase (not to be confused with two-phase) and / or three-phase AC input. A three-phase AC input is recommended for EV charging.

[0077] The mobile electronic device is, for example, a mobile phone, a smart phone, a laptop computer, a tablet, a remote control, a calculator, or a similar device equipped with a battery 320 and, for example, digital computing and / or data processing capabilities. For charging a mobile electronic device, the control circuit 180 may be configured to adjust the output current according to the specifications of the UV-C Power Delivery (USB-CPD) to support charging of the mobile electronic device up to 100W. The output current of the AC-DC converter circuit 100 may be configured to be in the range of 3-10A when charging the battery 320 of the mobile electronic device. Single-phase AC input charging is recommended for charging the mobile electronic device.

[0078] Alternatively, the AC-DC converter circuit 100 may be utilized in a fixed device or installation, such as a High Voltage DC (HVDC) converter or transformer station that converts AC voltage to DC voltage for transmission over HVDC transmission lines.

[0079] 7 illustrates a method for charging a battery in an electric vehicle that, in addition to the battery, includes a traction motor and AC-DC converter circuit 100. The method includes: Slowing down the movement of electric vehicles 1001 and generating 1002 an AC type current from the traction motor by decelerating the motion of the electric vehicle; converting 1003 the generated AC type current into a DC type current by an AC-DC converter circuit 100; and charging the battery with a DC type current 1004.

[0080] The DC type current may be a pulsed DC type current. This can be advantageous as it reduces impedance and minimizes charge losses. The pulsed DC type current may preferably have pulses in the range of 1 to 10 milliseconds, more preferably in the range of 1 to 5 milliseconds.

[0081] The method may further include cooling the battery, so that heat generation in the battery can be addressed.

[0082] FIG. 8 shows a regenerative braking system 2100 of an electric vehicle 2000. The regenerative braking system 2100 includes: A battery 320; A traction motor 2300 adapted to generate an AC type current; a braking system 2400 adapted to decelerate the electric vehicle 2000; an AC-DC converter circuit 100 configured to convert an AC type current from the traction motor 2300 to a DC type current and charge the battery 320; and a DC-AC converter 3000 configured to convert a DC type current from the battery 320 into an AC type current to power the traction motor 2300.

[0083] The traction motor 2300 may be an induction-based electric motor including a rotor and a stator. The traction motor 2300 may be configured to provide torque to the wheels of the electric vehicle 2000 to accelerate and decelerate the electric vehicle 2000. The braking system 2400 may be integrally formed with the traction motor 2300. The braking system 2400 may also be actuated by induction.

[0084] Preferred Embodiments A preferred embodiment of the present invention is an on-board charger for fast charging of a battery, comprising an input rectifier 110 including a first node 112 and a second node 114, the input rectifier configured to receive an AC voltage at the first node and provide a rectified voltage at a second node, a first transistor 120 including a first gate node 122, a first source node 124, and a first drain node 126, the first drain node being connected to a second node of the input rectifier and the first gate node being connected to a ground node 170, and a second gate node 132, a second source node 134, and a first drain node 136, the first transistor 120 including a first gate node 122, a first source node 124, and a first drain node 126, the first drain node being connected to a second node of the input rectifier and the first gate node being connected to a ground node 170. 134 and a second transistor 130 including a second drain node 136, the second drain node being connected to the first source node and materially corresponding to the first transistor; a duty cycle control unit 140 connected to the second gate node for providing a switching waveform to the second transistor; an output rectifier 150 connected to the second source node; and an output electronic filter 160 connected to the second source node. The first transistor may be a high electron mobility transistor, HEMT, and the second transistor may be a HEMT. The first transistor may be a gallium nitride transistor, and the second transistor may be a gallium nitride transistor. The input rectifier may be a half-wave rectifier including at least one diode. The input rectifier may be a full-wave rectifier including at least two diodes, the input rectifier further including a third node 116, the input rectifier configured to receive an AC voltage between the first node and the third node. All diodes are preferably GaN Schottky diodes. The AC-DC converter circuit may include a control circuit 180 for monitoring an output voltage level, and the control circuit is configured to provide feedback to the duty cycle control unit based on the monitored output voltage level. The first transistor and the second transistor may be monolithically integrated on the same substrate layer structure 290. The substrate layer structure may include a silicon substrate layer. The output rectifier may be a gallium nitride diode, and any diodes of the input rectifier, if present, may be gallium nitride diodes. The first transistor comprises a first carrier layer structure 224 on a substrate layer structure 290 and a first barrier layer structure 226 on the first carrier layer structure, a first gate node and a first drain node disposed on the first barrier layer structure, the nodes being physically separated by a spacer structure 250, the second transistor comprises a second carrier layer structure 234 on the substrate layer structure and a second barrier layer structure 236 on the second carrier layer structure, a second gate node and a second source node disposed on the second barrier layer structure, the nodes being physically separated by a spacer structure 250, the first and second carrier layer structures comprising a first semiconductor material, and the first and second barrier layer structures comprising a second semiconductor material. The first carrier layer structure may be physically separated from the second carrier layer structure by a spacer structure 250, and the first barrier layer structure may be physically separated from the second barrier layer structure by the same spacer structure 250. The first carrier layer structure may be connected to the second carrier layer structure, and the first barrier layer structure may be connected to the second barrier layer structure.

[0085] A preferred embodiment of the present invention is a smartphone wall charger for fast charging of a battery, the smartphone wall charger comprising an input rectifier 110 including a first node 112 and a second node 114, the input rectifier configured to receive an AC voltage at the first node and provide a rectified voltage at a second node, a first transistor 120 including a first gate node 122, a first source node 124, and a first drain node 126, the first drain node being connected to a second node of the input rectifier and the first gate node being connected to a ground node 170, and a second gate node 132, a second source node 134, and a first drain node 136, the first transistor 120 including a first gate node 122, a first source node 124, and a first drain node 126, the first drain node being connected to a second node of the input rectifier and the first gate node being connected to a ground node 170. a second transistor 130 substantially corresponding to the first transistor, the second transistor including a first source node 134 and a second drain node 136, the second drain node being connected to the first source node, a duty cycle control unit 140 connected to the second gate node for providing a switching waveform to the second transistor, an output rectifier 150 connected to the second source node, and an output electronic filter 160 connected to the second source node. The first transistor may be a high electron mobility transistor, HEMT, and the second transistor may be a HEMT. The first transistor may be a gallium nitride transistor, and the second transistor may be a gallium nitride transistor. The input rectifier may be a half-wave rectifier including at least one diode. The input rectifier may be a full-wave rectifier including at least two diodes, the input rectifier further including a third node 116, the input rectifier configured to receive an AC voltage between the first node and the third node. Preferably, all diodes are GaN Schottky diodes. The AC-DC converter circuit may include a control circuit 180 for monitoring the output voltage level, the control circuit being configured to provide feedback to the duty cycle control unit based on the monitored output voltage level. The first transistor and the second transistor may be monolithically integrated on the same substrate layer structure 290. The substrate layer structure may include a silicon substrate layer. The output rectifier may be a gallium nitride diode, and any diodes in the input rectifier, if present, may be gallium nitride diodes. The first transistor includes a first carrier layer structure 224 on a substrate layer structure 290 and a first barrier layer structure 226 on the first carrier layer structure, a first gate node and a first drain node are disposed on the first barrier layer structure, and the nodes are physically separated by a spacer structure 250; the second transistor includes a second carrier layer structure 234 on the substrate layer structure and a second barrier layer structure 236 on the second carrier layer structure, a second gate node and a second source node are disposed on the second barrier layer structure, and the nodes are physically separated by a spacer structure 250; the first and second carrier layer structures include a first semiconductor material; and the first and second barrier layer structures include a second semiconductor material. The first carrier layer structure may be physically separated from the second carrier layer structure by a spacer structure 250, and the first barrier layer structure may be physically separated from the second barrier layer structure by the same spacer structure 250. The first carrier layer structure may be connected to the second carrier layer structure, and the first barrier layer structure may be connected to the second barrier layer structure.

[0086] Another preferred embodiment of the present invention is an AC-DC converter device 300 including an AC-DC converter circuit 100 as claimed in any of claims 1 to 12, further comprising an interface for receiving an AC voltage 311 from an AC voltage source 310 and an interface for providing a DC voltage 312 to a battery 320, the battery being a battery of an electronic vehicle or a battery of a mobile electronic device.

[0087] A preferred method according to the present invention is a method for charging a battery of an electric vehicle, which in addition to the battery comprises a traction motor and an AC-DC converter circuit, the method comprises: decelerating the motion of the electric vehicle 1001, generating an AC type current from said traction motor due to the deceleration of the motion of the electric vehicle 1002, converting the generated AC type current into a DC type current by the AC-DC converter circuit 1003, and charging the battery with the DC type current 1004, the DC type current further comprising a DC waveform having pulses in the range of 1-10 ms, preferably the pulses are 1-5 ms. The battery can also be cooled to reduce the heat generation of the battery.

[0088] Another preferred embodiment of the present invention is a regenerative braking system 2100 for an electric vehicle 2000, comprising: a battery 320; a traction motor 2300 adapted to generate an AC type current; a braking system 2400 adapted to decelerate the electric vehicle; an AC-DC converter circuit 100 as claimed in claims 1 to 13 configured to convert the AC type current from the traction motor into a DC type current and charge the battery; and a DC-AC converter circuit 3000 configured to convert the DC type current from the battery into an AC type current and power the traction motor.

[0089] The disclosed embodiments and advantages are merely exemplary and should not be construed as limiting the scope of the present disclosure. The current teachings of AC-DC converter circuits can be easily applied to other types of faster charging by reducing the impedance for charging. This description is for illustrative purposes only and does not limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. It should also be understood that the above-described embodiments should not be construed as being limited to any of the details of the preceding description, unless otherwise specified, since the features can be embodied in several forms without departing from the characteristics thereof. Within the scope broadly defined in the appended claims. Although modifications and variations may be suggested by those skilled in the art, it is the intention of the inventors that the scope of the present invention includes all changes and modifications that reasonably fall within the scope of their contributions to the state of the art. Features of the different embodiments may be combined with other embodiments described herein mutatis mutandis. The scope of the present invention is limited only by the appended claims.

Claims

1. 1. An AC-DC converter circuit for high power charging of a battery, comprising: The AC-DC converter circuit is an input rectifier including a first node and a second node, the input rectifier configured to receive an AC voltage at the first node and provide a rectified voltage at the second node; a first transistor, the first transistor being a depletion type transistor and including a first gate node, a first source node, and a first drain node, the first drain node being coupled to the second node of the input rectifier, and the first gate node being coupled to a ground node; a second transistor including a second gate node, a second source node, and a second drain node, the second drain node being connected to the first source node and materially corresponding to the first transistor; a duty cycle control unit connected to the second gate node for providing a switching waveform to the second transistor; an output rectifier; an output electronic filter; the output rectifier and the output electronic filter are both connected to the second source node to configure a buck topology, or the output rectifier is connected to the first source node and the output electronic filter is connected to the second source node and an output node of the output rectifier to configure a boost topology. AC-DC converter circuit.

2. 2. The AC-DC converter circuit of claim 1, wherein the first gate node of the first transistor is always placed in an on state.

3. 2. The AC-DC converter circuit of claim 1, wherein the first transistor is a high electron mobility transistor (HEMT) and the second transistor is a HEMT.

4. 2. The AC-DC converter circuit of claim 1, wherein said first transistor is a gallium nitride transistor and said second transistor is a gallium nitride transistor.

5. 2. The AC-DC converter circuit of claim 1, wherein the input rectifier is a half-wave rectifier including at least one diode.

6. the input rectifier is a full-wave rectifier including at least two diodes, the input rectifier further including a third node; 6. The AC-DC converter circuit of claim 5, wherein the input rectifier is configured to receive an AC voltage between a first node and a third node.

7. a control circuit for monitoring the output voltage level; 2. The AC-DC converter circuit of claim 1, wherein the control circuit is configured to provide feedback to the duty cycle control unit based on the monitored output voltage level.

8. 2. The AC-DC converter circuit of claim 1, wherein the first transistor and the second transistor are monolithically integrated on the same substrate layer structure.

9. 9. The AC-DC converter circuit of claim 8, wherein the substrate layer structure includes a silicon substrate layer.

10. the output rectifier is a gallium nitride diode, and the input rectifier, if any, is a gallium nitride diode.

2. The AC-DC converter circuit of claim 1.

11. the first transistor includes a first carrier layer structure over a substrate layer structure and a first barrier layer structure over the first carrier layer structure; the first gate node and the first drain node are disposed over the first barrier layer structure, the nodes being physically separated by a first spacer structure; the second transistor includes a second carrier layer structure overlying a substrate layer structure and a second barrier layer structure overlying the second carrier layer structure; the second gate node and the second source node are disposed over the second barrier layer structure, the nodes being physically separated by a second spacer structure; the first and second carrier layer structures comprise a first semiconductor material; the first and second barrier layer structures comprise a second semiconductor material; 2. The AC-DC converter circuit of claim 1.

12. a third spacer structure physically separating the first carrier layer structure from the second carrier layer structure and physically separating the first barrier layer structure from the second barrier layer structure; 12. The AC-DC converter circuit of claim 11.

13. the first carrier layer structure is connected to the second carrier layer structure, 2. The AC-DC converter circuit of claim 1, wherein the first barrier layer structure is connected to the second barrier layer structure.

14. 1. An AC-DC converter device comprising: A power supply circuit comprising the AC-DC converter circuit according to claim 1, The AC-DC converter device further comprises: an interface for receiving an AC voltage from an AC voltage source; an interface for providing a DC voltage to a battery, the battery being a battery of an electronic vehicle or a battery of a mobile electronic device; An AC-DC converter device comprising:

15. 10. A method for charging a battery in an electric vehicle comprising, in addition to the battery, a traction motor and an AC-DC converter circuit as claimed in claim 1, said method comprising: slowing the motion of the electric vehicle; and generating an AC type current from the traction motor by decelerating the motion of the electric vehicle; converting the generated AC type current into a DC type current by an AC-DC converter circuit; charging a battery with said DC type current; A method comprising:

16. A regenerative braking system for an electric vehicle, comprising: Batteries and a traction motor adapted to generate an AC type current; a braking system adapted to decelerate the electric vehicle; 13. An AC-DC converter circuit as claimed in claim 12 configured to convert AC type current from a traction motor to DC type current for charging said battery; and a DC-AC converter circuit configured to convert a DC type current from the battery to an AC type current to power the traction motor.

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