Electric vehicle battery charger

Abstract

To provide a home battery charging system used in an electric vehicle.SOLUTION: Provided is a battery charger that receives a single-phase AC power and can feed a power storage battery with both AC power and DC power, the AC input receiving a single-phase power from a power feeding part. The AC input is connected with a switch, and the switch is further connected with any one of an AC output and a power converter. The power converter converts power into power for a DC load depending on a charge voltage value and a desired charge current value to obtain a variable DC voltage with a variable current within a range not exceeding a desired charge current. The power converter has at least one high-voltage capacitor for storing power stepped up to a voltage more than a peak voltage of the AC input.SELECTED DRAWING: Figure 1

Description

Related Applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 660,530, filed April 20, 2018, the specification of which is incorporated herein by reference. [Technical Field]

[0002] The present application relates to the field of battery charging systems, for example used in electric vehicles, and also to the field of power converters, such as rectifiers, operating at domestic voltages and power. [Background technology]

[0003] This section is intended to provide a background and premise for the claimed invention. The descriptions in this section may contain patentable concepts, which have not necessarily been conceived or patented. Therefore, unless expressly stated otherwise, nothing in this section constitutes or is admitted to be prior art to the present disclosure and claims by virtue of its inclusion in this section.

[0004] Current electric vehicles (EVs) typically include a battery bank and a battery charging system. Battery banks typically use direct current (DC) as input to charge the battery. For this reason, vehicles are equipped with a charging circuit that converts household AC power into DC input for the battery bank. Battery charging systems, commonly known as "Level 1" and "Level 2" charging, receive household AC power and convert it to DC to power the battery bank. Level 1 and Level 2 charging differ primarily in the amount of power supplied and, in some cases, the voltage.

[0005] "Level 3" charging is generally DC charging, and uses a high voltage of over 350V and a high-power DC current, for example, and can supply a charging power of typically over 15kW, up to a maximum of 160kW. Level 3 charging stations are commercial charging stations that aim to charge EVs in the shortest possible time. Current EV batteries can be charged fairly quickly up to about 75% to 80% of their charge capacity. Depending on the EV battery, high-power charging for 15 to 20 minutes can bring the battery to a remaining capacity of 15%. Some EVs can be charged from 100% to 80% capacity. However, charging beyond this point is very slow, and it can take hours to charge from, say, 80% to 99% capacity. Charging station users are typically asked to stop charging at this stage to allow other users to charge their vehicles. While fast charging is convenient for commercial charging station operations, high-power charging can shorten the useful life of some EV batteries. From a battery life perspective, it is desirable to charge from 15% to 80% capacity over two hours, rather than 20 minutes, for example.

[0006] The DC power used for such charging comes from a three-phase power supply, which is typically found in commercial facilities and not in homes. Three-phase AC power can be efficiently converted to DC. Furthermore, this type of charging is typically not available in homes, as the available power for homes is limited to less than 60 kW. In some areas, the power supply to home distribution panels is capped at, for example, 240V (RMS) and 200A, meaning the total available power for a home is 48 kW. While overload conditions can occur when too many homes draw too much power, home distribution transformers are typically sized for "oversubscription," and manufacturers often limit the available power to 48 kW. Power limiting using power circuit breakers protects distribution transformers from such overload conditions based on statistical considerations. Additionally, Level 3 charging from a single-phase AC current source requires a rectifier circuit, which is not commonly installed in homes due to cost and other reasons.

[0007] Current home vehicle charging systems behave essentially like high-power appliances, drawing power from, for example, a clothes dryer plug. In Level 2 charging, power is typically limited to approximately 7 kW or less, a load similar to that of a clothes dryer (30 amps at 240V, or 7.2 kW). The charging unit installed in the home connects the mains AC power to the vehicle via a breaker circuit, and charges the vehicle battery using an on-board AC-to-DC converter.

[0008] Many electric vehicles are configured for "fast" DC charging, in which case the AC-DC converter is external to the EV. DC charging has the advantage that the charging power is greater than the capacity of the on-board AC-DC converter, and the conversion efficiency does not depend on the converter installed by the manufacturer when the vehicle is built. If DC charging can be done efficiently at home, there is no need to install heavy and expensive Level 2 charging equipment on the vehicle.

[0009] For Level 2 power consumption, it is highly unlikely that charging a car would cause a home's electrical entry or main circuit board to draw more power than its power budget (thus tripping the main breaker and disconnecting the circuit board from the distribution transformer). However, with most home electrical panels, adding a load of more than 7kW for many hours increases the risk of exceeding the total power budget set for the home electrical panel. Summary of the Invention

[0010] This patent application provides complementary improvements, which can be applied separately or in combination. The first improvement relates to an improved rectifier for use in a DC charger. In one aspect, the improved rectifier includes a high-voltage capacitor module that is easily replaceable in the charger. In another aspect, the charger includes a backplane-branch configuration that allows AC-to-DC conversion to be distributed across multiple low-power branch modules, thereby enabling branch modules, each with a power draw of less than approximately 5 kVA, to be combined to convert single-phase AC power of more than 10 kVA (preferably more than 20 kVA) to a DC power output for charging. The second improvement relates to a battery charging system that allows a level of power to be used for battery charging that would exceed the nominal power capacity if all other loads were connected and drawing power from the power source simultaneously. Accordingly, the second improvement provides time-of-day prediction of power consumption by non-charging loads based on modeling and / or historical monitoring of power consumption by non-charging loads. A third improvement relates to a power converter having a charging power program module, the charging power program module having a user input interface for receiving user input for setting a charging aggression parameter. The power converter includes a power source and controls the current level over time according to a charging priority parameter. A fourth improvement relates to a socket-type connector that allows a high-voltage capacitor to be attached or detached from the power converter. A fifth improvement relates to a power converter having a circuit that can operate bidirectionally. In other words, the power converter functions not only as a rectifier that charges DC from AC input, but also as an inverter that converts DC voltage / current to AC, thereby enabling AC output to be supplied from the DC battery of an electric vehicle.

[0011] In some implementations, the battery charger converts single-phase AC power to provide DC power to the storage battery. The AC input receives single-phase power from a power source. The power converter The charger circuit is connected to an AC input and converts power to a DC load in response to a charging voltage and a desired charging current, resulting in a variable DC voltage with a variable current not exceeding the desired charging current. The power converter includes at least one high-voltage capacitor for storing power boosted to a voltage above the peak voltage of the AC input. In some embodiments, the charger circuit is bidirectional; that is, it functions as both a rectifier to convert AC voltage / current to DC and an inverter to convert DC to AC. This allows an AC output to be provided from the electric vehicle's DC battery.

[0012] In one embodiment of the present disclosure, the charging circuit functions as a unidirectional charger that operates in only one direction as a rectifier to convert AC voltage to DC, which can be achieved by replacing the two high-voltage switches connected between the first terminal and both ends of the high-voltage capacitor in the charging circuit with two diodes.

[0013] In this regard, a battery charge converter operating in rectifier mode may be referred to as a battery charge rectifier, and a battery charge converter operating in inverter mode may be referred to as a battery charge inverter.

[0014] In some embodiments, the battery charger of the present disclosure includes a housing having an AC input for receiving single-phase power from a power source, an AC output, and a DC output, the AC input and the AC output being connected by a switch. The switch is also connected to a backplane having one or more module connectors configured to accept one or more DC power converter modules. In AC mode, the switch is closed, connecting the AC input to the AC output, thereby providing AC current to the storage battery. In DC mode, the switch is open, connecting the AC input to the DC power converter module, thereby providing DC current to the DC output.

[0015] In one embodiment, the charger has a modular connector configured to accept one or more DC power converter modules, but the charger does not include a built-in DC power converter, providing the user with a Level 2 EV AC battery charger. DC power converter modules can be retrofitted to the charger, thereby upgrading the charger to Level 3 EV DC charging.

[0016] In another aspect, the present invention provides a portable DC charging unit for an electric vehicle, the portable DC charging unit comprising a housing having a connector backplane having a plurality of sockets configured to accept at least one module including a battery rectifier circuit, an AC input for receiving AC current from an AC source, and a DC output for connection to the electric vehicle via a DC cable.

[0017] In another broader aspect, the present disclosure provides a power converter coupled to an AC input for converting power from the AC input to DC, the power converter including at least one high-voltage capacitor for storing power boosted to a voltage higher than the peak voltage of the AC input and a rectifier circuit. The rectifier includes an inductor connected in series with the AC input, a low-voltage capacitor, either two diodes or two high-voltage switches connected between a first AC input terminal and both ends of the high-voltage capacitor, two intermediate low-voltage power switches connected between both ends of the high-voltage capacitor and both ends of the low-voltage capacitor, and two end low-voltage power switches connected between both ends of the low-voltage capacitor and a second AC input terminal. A DC load can be connected across the high-voltage capacitor. The power converter further includes at least one sensor for sensing current and / or voltage in the rectifier circuit and connected to gate inputs of the two intermediate low-voltage power switches and the two end low-voltage power switches. Includes a controller.

[0018] In some embodiments, the controller operates the rectifier circuit in a boost mode, where the voltage on the high-voltage capacitor is higher than the peak voltage of the AC input, and the two middle low-voltage power switches and the two end low-voltage power switches are switched in redundant switching states responsive to a measurement of the low-voltage capacitor voltage, such that the low-voltage capacitor is maintained at a predetermined percentage of the desired voltage on the high-voltage capacitor, thereby maintaining the high-voltage capacitor at the desired high voltage, and the rectifier circuit acts as a five-level active rectifier to supply DC loads and absorb power while suppressing harmonics of the AC input.

[0019] In some embodiments, the power converter includes a bidirectional rectifier / inverter circuit instead of a rectifier circuit, and two controllers instead of one controller that functions bidirectionally as both a rectifier and an inverter. The bidirectional rectifier / inverter circuit includes an inductor connected in series with the AC port, a low-voltage capacitor, two high-voltage power switches connected between the first AC terminal and both ends of the high-voltage capacitor, two intermediate / low-voltage power switches connected between both ends of the high-voltage capacitor and the low-voltage capacitor, and two terminal low-voltage power switches connected between both ends of the low-voltage capacitor and the second AC input terminal. A DC load can be connected across the high-voltage capacitor. The power converter further includes a first controller for the rectifier mode. The first controller has at least one sensor for sensing current and / or voltage in the bidirectional rectifier / inverter and is connected to gate inputs of the two high-voltage power switches, the two intermediate / low-voltage power switches, and the two terminal low-voltage power switches to operate the rectifier circuit in boost mode. The voltage of the high-voltage capacitor is higher than the peak voltage of the AC input. The two high-voltage power switches are controlled to switch on and off at the frequency of the AC input. The two middle low-voltage power switches and the two end low-voltage power switches are switched in redundant switching states in response to a measurement of the low-voltage capacitor voltage, thereby maintaining the low-voltage capacitor at a predetermined percentage of the desired voltage of the high-voltage capacitor, thereby maintaining the high-voltage capacitor at the desired high voltage. The rectifier circuit acts as a five-level active rectifier to supply power to the DC load and absorb power while suppressing harmonics of the AC input. The power converter further includes a second controller for inverter mode.The second controller is connected to the two high-voltage power switches, the two intermediate-low-voltage power switches, and the two terminal low-voltage power switches, and is configured to generate a signal waveform including a first control signal and a signal waveform including a second control signal and apply them to the two high-voltage power switches, the two intermediate-low-voltage power switches, and the two terminal low-voltage power switches, where the first control signal is a signal that connects the low-voltage capacitor in series to the DC port and the AC port and charges the low-voltage capacitor to a predetermined value proportional to the voltage of the DC port, and the second signal is a signal that disconnects the low-voltage capacitor from the DC port and connects it in series to the AC port, thereby discharging the low-voltage capacitor.

[0020] In one aspect, the present disclosure provides a battery charger for converting single-phase AC power to supply DC power to a storage battery. The charger includes an AC input for receiving single-phase power from a power source, a battery charge controller interface for communicating with the storage battery to receive a charging voltage value and a desired charging current value, and a power converter connected to the AC input for converting power from the AC input to DC in accordance with the charging voltage value and the desired charging current, to provide a DC output for a DC load with a variable voltage depending on the charging voltage value and a variable current not exceeding the desired charging current. The power converter includes at least one high-voltage capacitor for storing power boosted to a voltage exceeding the peak voltage of the AC input. The charger may further include one of the following features:

[0021] In some embodiments, the power converter comprises a feed-in power sensor for measuring the power drawn by the power source from a distribution transformer, and a draw power increase prediction module having an input for receiving a value of the draw power and an output for providing a value of a maximum increase predicted in the power source's power draw, the power converter being configured to limit a current level output by the power converter when the maximum increase predicted in the power draw occurs to prevent the power source's power draw from exceeding a predetermined limit.

[0022] In some embodiments, the power converter includes a charging power program module having a user input interface for receiving user input defining a charging priority parameter, the charging power program module controlling the current level over time in response to the charging priority parameter.

[0023] In some embodiments, the power converter further comprises a socket-style connector for removing and replacing the high-voltage capacitor from the power converter.

[0024] In some embodiments, the power converter includes a rectifier circuit including an inductor connected in series with an AC input, a low-voltage capacitor, two high-voltage power switches each connected between a first AC terminal and both ends of the high-voltage capacitor, two intermediate low-voltage power switches each connected between the ends of the high-voltage capacitor and the ends of the low-voltage capacitor, and two end low-voltage power switches connected between the ends of the low-voltage capacitor and a second AC input terminal, and a DC load can be connected across the high-voltage capacitor. The power converter further includes a controller having at least one sensor for sensing current and / or voltage in the rectifier circuit, the controller connected to gate inputs of the two high-voltage power switches, the two intermediate low-voltage power switches, and the two end low-voltage power switches, and configured to operate the rectifier circuit in a boost mode. The voltage of the high-voltage capacitor is higher than the peak voltage of the AC input, the two high-voltage power switches are controlled to switch on and off at the frequency of the AC input, and the two intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in redundant switching states according to the measured voltage of the low-voltage capacitor, thereby maintaining the low-voltage capacitor at a voltage that is a predetermined percentage of the desired voltage of the high-voltage capacitor, and thereby maintaining the high-voltage capacitor at a desired high voltage.The rectifier circuit serves as a five-level active rectifier and supplies power to the DC load while suppressing harmonics of the AC input.The power supply further includes a buck converter circuit that converts the DC power from both ends of the high-voltage capacitor into a low DC output voltage set by the charging voltage value.

[0025] In some embodiments, the charger features a power converter that includes both: a power converter comprising: a feed-in power sensor for measuring the power drawn by the power source from a distribution transformer; and a power draw increase prediction module having an input for receiving a value of the draw power and an output for providing a value of a maximum predicted increase in the power draw of the power source, the power converter being configured to limit a current level output by the power converter in the event of the maximum predicted increase in power draw to prevent the power draw of the power source from exceeding a predetermined limit.

[0026] a) an inductor connected in series with an AC input, a low-voltage capacitor, two high-voltage power switches respectively connected between a first AC terminal and both ends of the high-voltage capacitor, and two intermediate switches respectively connected between the both ends of the high-voltage capacitor and both ends of the low-voltage capacitor; a middle low-voltage power switch and two terminating low-voltage power switches respectively connected between both ends of the low-voltage capacitor and a second AC input terminal.

[0027] b) a controller having at least one sensor for sensing current and / or voltage of the rectifier circuit and connected to gate inputs of the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches, for operating the rectifier circuit in a boost mode, wherein the voltage of the high-voltage capacitor is higher than a peak voltage of the AC input, the two high-voltage power switches are controlled to switch on and off at a frequency of the AC input, the two intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in redundant switching states in response to the measured voltage of the low-voltage capacitor, thereby maintaining the low-voltage capacitor at a voltage that is a predetermined percentage of the desired voltage of the high-voltage capacitor, thereby maintaining the high-voltage capacitor at a desired high voltage, and the rectifier circuit acts as a five-level active rectifier to supply power to the DC load and absorb power while suppressing harmonics of the AC input.

[0028] c) A buck converter circuit that converts the DC power from both ends of the high-voltage capacitor into a low DC output voltage set by the charging voltage value.

[0029] In some embodiments, the charger includes a network interface for receiving user input, the network interface comprising a remote device user interface connected to the network interface.

[0030] In one embodiment, the power converter includes the charging power program module, and the charging priority parameter defines an upper limit for the charging current for charging the vehicle. In one example, the charging power program module records a history of the charging current so that battery degradation can be evaluated.

[0031] In some embodiments, the charger is characterized in that the power converter comprises: a power draw sensor for measuring power drawn by the power source from a distribution transformer; a power draw increase prediction module having an input for receiving the value of the power draw and an output for providing a value of a maximum predicted increase in the power draw of the power source, the power converter configured to limit a current level output by the power converter when the maximum predicted increase in power draw occurs to prevent the power draw of the power source from exceeding a predetermined limit; and a load shedding switch, the power draw increase prediction module coupled to the load shedding switch and configured to temporarily disconnect at least one shiftable load connectable to the load shedding switch when the upcoming predicted maximum increase in power draw poses a risk of exceeding the predetermined limit, and to reconnect the shiftable load when the power draw increase prediction module determines that the upcoming risk of exceeding the predetermined limit has been averted.

[0032] This disclosure provides systems, methods, and more broadly techniques, as described herein and in the claims. [Brief explanation of the drawings]

[0033] Embodiments of the present disclosure may be better understood with reference to the accompanying drawings, which are listed below.

[0034] [Figure 1] Schematic diagram showing the physical installation of a home EV charging system including a pole-mounted transformer, a residential power feed with load sensors and a main circuit breaker panel, a 240V AC power line connecting the panel to a charger, and a charging cable connecting the charger to an electric vehicle (EV), with a CAN bus connection between the EV and the charger. [Figure 2A] 1 is a circuit diagram of a battery charge converter having a five-level topology circuit and operating in rectifier mode in accordance with certain example embodiments. [Figure 2B] 2B is a circuit diagram of the five-level topology circuit of the battery charger of FIG. 2A, showing the connections in the "State 2" switching configuration. [Figure 2C] 2B is a circuit diagram of the five-level topology circuit of the battery charger of FIG. 2A, showing the connections in the "State 3" switching configuration. [Figure 2D] FIG. 1 is a circuit diagram of a 5-level topology circuit for a one-way / rectifier charger, in accordance with certain example embodiments. [Figure 2E] FIG. 1 is a circuit diagram of an embodiment of a battery charge converter having a five-level topology circuit and operating in inverter mode. [Figure 3A] FIG. 2 is a block diagram of a modulator with voltage balancing control for the battery charge converter of FIG. 1 operating in rectifier mode. [Figure 3B] 3B is a signal graph illustrating the four-carrier pulse width modulation scheme used in the modulator of FIG. 3A. [Figure 3C] FIG. 2 is a circuit diagram showing elements of the controller in the battery charge converter of FIG. 1 operating in rectifier mode. [Figure 3D]FIG. 2F is a circuit diagram showing elements of the controller in the battery charge converter of FIG. 2E operating in inverter mode. [Figure 3E] Both the modulator and state selection circuit logic elements are shown using both voltage and current feedback to provide eight signals, each representing a different state. [Figure 4] 2 is a block diagram illustrating the battery charge converter 1 of FIG. 1 operating in rectifier mode, including a controller circuit. [Figure 5] 2 is a signal graph illustrating the steady state results of the battery charge converter of FIG. 1 operating in rectifier mode at 1 kW. [Figure 6] 2 is a screenshot of a power analyzer showing some parameters measured by the power analyzer for the battery charge converter of FIG. 1 operating in rectifier mode. [Figure 7] 2 is a signal graph illustrating the performance during a 50% DC load change, Transition I, for the battery charge converter of FIG. 1 operating in rectifier mode. [Figure 8A] FIG. 1 is a block diagram illustrating a modular converter battery charging system. [Figure 8B] FIG. 1 is a block diagram illustrating a charger with both an AC and modular converter battery charging system. [Figure 8C] FIG. 1 is a block diagram illustrating an embodiment of a charger having a switch connected to a backplane and providing an AC output. [Figure 8D] FIG. 8D is a block diagram illustrating an embodiment in which the switch of FIG. 8C is replaced with a modular converter battery charging system. [Figure 9] FIG. 2 is a block diagram showing a charging energy amount controller. [Figure 10] FIG. 1 is a schematic diagram illustrating a power converter module according to one embodiment. [Figure 11] FIG. 1 is a schematic diagram illustrating an AC charging module according to one embodiment. [Figure 12]FIG. 1 is a schematic diagram showing the physical installation of a portable EV charging system including a charging cable connecting the charger to an electric vehicle (EV), with a battery rectification unit between the EV and the charger. [Figure 13] FIG. 13 is a block diagram illustrating the portable EV charging system of FIG. 12. [Figure 14A] FIG. 1 is a schematic diagram illustrating components for storing a portable EV charging system with a receptor, in accordance with certain example embodiments. [Figure 14B] FIG. 1 is a schematic diagram illustrating components for storing a portable EV charging system with a receptor, in accordance with certain example embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0035] As used herein, the phrases "in one embodiment," "an embodiment," or similar expressions mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment," "an embodiment," or similar expressions in this specification are not necessarily all referring to the same embodiment.

[0036] In addition, the features, structures, or properties described in the present invention may be combined in any manner with one or more other embodiments. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible without departing from the scope of the present invention. Therefore, the present invention is intended to encompass modifications and variations that fall within the scope of the claims and their equivalents. Preferred embodiments of the present invention are described in detail below.

[0037] In this application, the term "Level 2 EV charger" refers to a single-phase AC EV charger, and the term "Level 3 EV charger" refers to a single-phase DC EV charger.

[0038] Figure 1 illustrates the physical configuration of an embodiment in which three-wire, single-phase split mains power is distributed from a pole-mounted transformer, the most common form of power distribution in North America. The transformer receives single-phase power, typically 14.4 kV or 25 kV, from the distribution line. The transformer can also handle approximately 50 kVA to 167 kVA of power from three-wire, single-phase 240 V AC for distribution to a small number of homes, or feeders. Each feeder is typically configured to handle between 100 A and 200 A at 240 V AC, or approximately 24 kVA to 48 kVA (1 kVA is generally considered to be equivalent to 1 kW).

[0039] It should be noted that the embodiments are not limited to three-wire, single-phase, 240V AC power systems; embodiments of the present disclosure are applicable to any existing single-phase AC voltage power network distributed to a home or business power supply.

[0040] A power source typically includes a usage meter, a main breaker rated for the total allowable load (e.g., 100 A or 200 A), and a panel with circuit breakers for each household circuit that can receive 240V AC or 120V AC from a three-wire, single-phase, 240V AC input. Most circuit breakers have a capacity between 15 A and 30 A, but smaller capacity breakers (e.g., 10 A) and larger capacity breakers (e.g., 40 A) are also available for larger appliances. In some countries, the power source capacity may be as small as 40 A to 60 A, and in countries where all household circuits are 240V AC, the power is not three-wire, single-phase, but rather conventional two-wire, single-phase, 240V AC power (the voltage levels used vary from approximately 100 V to 250 V).

[0041] As shown in FIG. 1 , the charger is connected to the main panel's circuit breaker via a breaker with a higher current rating, such as 40 A to 80 A. However, the charger of the present disclosure can consume more than 100 A if necessary. Whether a specific circuit breaker is required for the charger is determined by electrical regulations. The cable connecting the charger to the panel is rated appropriately for such high current. The connection to the power panel can be a direct hardwired connection, or a high-voltage socket can be provided and connected to the electrical panel. In this case, the charger can be connected to the panel with a cable and plug, similar to those used for appliances such as ovens and clothes dryers. The illustrated charger is connected to a single load sensor that senses the load drawn by the entire panel, including the charger. The charging cable can be a plug-type charging cable conventionally known in the industry.

[0042] FIG. 2A illustrates an electric vehicle battery charging converter 100 according to certain example embodiments. The circuit features a 5-level packed U-cell topology, forming an active rectifier with power factor correction. The charger offers several notable advantages over other types of converters and features boost mode operation, which allows for output power exceeding AC peaks while reducing or eliminating current harmonics at the input.

[0043] The battery charge converter 100 includes an AC input 105, an inductive filter 110 connected in series with the AC input 105, and a 5-level topology circuit 115.

[0044] In this example, the inductive filter 110 is a 2.5 mH inductor, although not limited thereto. For typical power supplies in the 1-3 kW range (throughout all states of charge, from full power to underpower), a 1 mH wire inductor provides good results consistent with existing standards. For higher power ranges, the inductance is smaller, so for example, a 500 μH inductor may be used for the inductive filter 110 for higher wattage power ratings (e.g., greater than 2 kW, preferably greater than 3 kW, and more preferably greater than about 5 kW). The design of the present disclosure advantageously allows for a smaller overall footprint for the battery charge converter 100, in part due to the small size of the inductive filter 110. The design of the inductive filter 110 is selected based on the application, power rating, utility voltage harmonics, switching frequency, etc. The filter can be varied to suit various applications. While a single inductor is the simplest such filter, in alternative embodiments, the inductive filter 110 may combine an inductor and a capacitor, such as an inductor (e.g., 2 mH) connected to a capacitor (e.g., 30 μF) connected to ground. The choice of filter is a factor that affects the overall size and losses of the design. The larger the filter, the larger the overall design size and generally the higher the losses.

[0045] The five-level circuit includes a high-voltage capacitor 120, at least one low-voltage capacitor 125, two high-voltage power switches 130a, 130b connected between a first terminal 135 and both ends 145a, 145b of the high-voltage capacitor 120, respectively, and two intermediate low-voltage power switches 145a, 145b connected between both ends 145a, 145b of the high-voltage capacitor 120 and both ends 155a, 155b of the low-voltage capacitor 125, respectively. 140a, 140b, and two terminal low voltage power switches 150a, 150b connected between the second input terminal 160 and both ends 155a, 155b of the low voltage capacitor 125, respectively.

[0046] These capacitors are so named because, in use, the voltage across high voltage capacitor 120 is higher than the voltage across low voltage capacitor 125. In particular embodiments, the voltage V across high voltage capacitor 120 is o is the voltage V of the low-voltage capacitor 125 c In this embodiment, the high-voltage capacitor 120 and the low-voltage capacitor 125 are separate devices, with the high-voltage capacitor 120 having a capacitance of 2 mF and the low-voltage capacitor having a capacitance of 50 μF. To provide a typical power range of 1 to 3 kW (throughout the full charge state from full power to underpower), a combination of a 2 mF capacitor as the high-voltage capacitor 120 and a 100 μF capacitor as the low-voltage capacitor 125 provides good results that meet existing standards. This configuration allows for a sampling time for voltage balancing. A 20µs capacitor has been found to work well. For a 5kW power device, a 4mF capacitor as the high voltage capacitor 120 and a 200µF capacitor as the low voltage capacitor 125 are suitable. However, using smaller capacitors It is also possible to increase the sampling rate of the voltage balance control to perform calculations for the voltage balance control more accurately. This can be achieved by using a faster microprocessor. Each capacitor may be an electrolytic capacitor or a film capacitor. In this embodiment, a film capacitor with a long life is used for the low-voltage capacitor 125, which is not connected to the load. The high-voltage capacitor 120 has a shorter life, and is therefore often the cause of circuit failure. For this reason, in the embodiment shown in FIG. 10, the high-voltage capacitor is configured as a replaceable component. This will be described in detail with reference to FIG. 10.

[0047] Of course, it is economical to use a capacitor that does not exceed the necessary requirements, but there is no problem in using the same capacitor for both high-voltage capacitor 120 and low-voltage capacitor 125. However, in this case, the low-voltage capacitor 125 would have a higher specification than necessary.

[0048] The intermediate low-voltage power switches 140a, 140b and the terminal low-voltage power switches 150a, 150b collectively constitute auxiliary power switches. Similar to the capacitors, the high-voltage power switches 130a, 130b and the low-voltage power switches are so named because, in use, the high-voltage power switches 130a, 130b operate at a higher voltage than the auxiliary power switches. Additionally, in accordance with the design of the present disclosure, the low-voltage power switches are high-frequency power switches, and the high-voltage power switches 130a, 130b are low-frequency power switches. Again, these switches are so named because, in use, the high-frequency power switches are operated / switched at a higher frequency than the low-frequency power switches. In practice, it is possible to use the same switches for all of these applications, provided they are suited to the highest switching frequency of the high-frequency switches and the highest voltage applied to the high-voltage switches. However, using switches suited to each application is desirable for cost and, in some cases, size and weight savings. These switches may all be of the FET, JFET, IGBT, MOSFET, or other types.

[0049] The low voltage capacitor 125 of the five-level circuit 115 can be considered an auxiliary capacitor, and together with the auxiliary power switch, constitute the auxiliary circuit 116 of the five-level circuit 115. Note that in alternative embodiments, additional auxiliary capacitors and switch pairs may be added to the auxiliary circuit 116.

[0050] The switching states of the five-level circuit 115 include redundant states. Research has shown that this can facilitate balancing of the auxiliary capacitor voltage. Balancing the capacitor voltage can generate five voltage levels at the input of the rectifier, reducing voltage harmonics that directly affect the harmonic content of the current. The voltage at the output terminals is also regulated and supplied to the DC load. Experimental results are presented here to demonstrate the dynamic performance of the proposed rectifier, operating at unity power factor and reducing harmonics in the AC current drawn from the utility power supply.

[0051] As shown in FIG. 2A, the five-level circuit 115 operating in rectifier mode generates five voltage levels using only six switches. This configuration provides a useful feature of redundant switching states, which facilitates balancing of voltages across the DC link. The proposed five-level rectifier operates in boost mode, allowing it to operate at unity power factor and reject harmonics in the input AC current. The low THD of the five-level voltage waveforms from the five-level rectifier directly impacts line current harmonics, allowing for smaller inductive filters than those of two-level rectifiers, resulting in smaller product sizes. Because the auxiliary DC capacitor voltage is balanced using only redundant switching states, the voltage / current of the five-level rectifier is: Similar to a full-wave rectifier with a single DC output terminal, it can be regulated by a cascaded PI controller.

[0052] Next, the configuration and switching states of the five-level rectifier are described. A switching method based on voltage balance control is presented. The described design has been tested in practice under various conditions, including load changes and AC power fluctuations. The test results show that the battery charging converter 100 in rectifier mode exhibits good dynamic performance.

[0053] The five-level circuit 115 has two DC links. The main DC link includes a high-voltage capacitor 120 that provides a regulated voltage to the DC load. Here, the voltage of the high-voltage capacitor 120 is V o The other DC link is an auxiliary capacitor (low-voltage capacitor 12 5). Here, the voltage of the low-voltage capacitor 125 is V c V c is the voltage amplitude at the main terminal (V o ) and the voltage amplitude of the rectifier input voltage ( V in ) to generate a 5-level quasi-sine wave. Therefore, V c = E, V o =2E, and the five voltage levels are 0, ±E, and ±2E.

[0054] Note that operating in boost mode means that the DC output voltage is higher than the peak value of the AC input. In this embodiment, this is as follows:

number

[0055] Based on the peak value of the system AC, the DC voltage was selected to be 200V, where V c teeth , V o Since this is half of the equation, the following relationship is obtained:

number

[0056] Therefore, the output terminal voltage V o The voltage is adjusted to 200V and supplied to the DC load. In the example, the DC load is a battery bank for an EV. In addition, the auxiliary capacitor voltage V c is V inIt is balanced at 100V to generate a five-level voltage waveform.

[0057] Based on the voltages selected above, the two high-voltage power switches 130a, 130b are selected to withstand a voltage of 200 V. The auxiliary power switch is supplied with only about half the voltage of the high-voltage power switches 130a, 130b, i.e., 100 V in this embodiment.

[0058] Table 1 shows the switching states of the five-level circuit 115. This embodiment includes a pair of high-voltage power switches 130a, 130b, a pair of middle low-voltage power switches 140a, 140b, and a pair of end low-voltage power switches 150a, 150b, and in each switch pair, the switches operate in a complementary manner, i.e., when one is open, the other is closed, and vice versa. [Table 1]

[0059] Each switch configuration shapes the current path through the converter and creates voltage levels at the input, resulting in a five-level voltage waveform. A smoother waveform results in lower total harmonic distortion (THD), which directly affects the harmonic content of the current drawn (harmonics in the voltage waveform carry over to the current waveform; smaller harmonics in the voltage waveform result in smaller harmonics in the current waveform). The resulting reduced amount of THD allows for smaller filters in the AC line to achieve acceptable performance compared to the larger filters typically used in two-level converters.

[0060] As can be seen from Table 1, the high-voltage power switches 130a, 130b are actually only switched twice per cycle. However, the auxiliary power switches switch much more frequently, for example, switching between redundant states (e.g., states 2 and 3) multiple times before transitioning to the next non-overlapping state (e.g., state 4). In certain embodiments, the low-voltage power switches have a high switching frequency, at least 1 kHz or greater, such as greater than 10 kHz. In this particular example, the switching frequency is, for example, 48 kHz.

[0061] Next, we will explain the voltage balancing control of the battery charging rectifier 100. As can be seen from Table 1, there are some overlaps in the switching states. That is, there are some overlaps in the switching states, such as states 2 and 3, or states 6 and 7, that result in the same V in The main output includes a switching state where the voltage is V o and is controlled by an external PI controller Therefore, having redundant switching states provides several advantages. One advantage of redundant switching states is that V o The voltage error of the external In addition, the load on the controller can be reduced by reducing the auxiliary capacitor voltage V c Balun By using phase control, it is possible to provide 5 identical voltage levels to generate a quasi-sine wave with low THD.

[0062] 2B and 2C show the current paths 205, 210 corresponding to redundant State 2 and State 3, respectively, more clearly illustrating the effect of the redundant switching states on the voltage balancing of both DC links. The polarity of the DC links is assumed to be as shown, and can be charged or discharged depending on the current sign. In State 2, assuming the current is positive, the high-voltage capacitor 120 is charged and the low-voltage capacitor 125 is discharged, with the opposite polarity. Thus, Vo increases, and V c In contrast, in state 3, the low voltage capacitor 125 is charged by a current that becomes positive in state 3. Note that the sign of the current is In the case of an inverter, these conditions work in reverse. Also, when not connected to an AC source, the discharge of the load causes V o is always decreasing.

[0063] Table 2 shows the effect that each switching state has on the high voltage capacitor 120 and the low voltage capacitor 125, and provides useful information for designing a balance control. [Table 2]

[0064] The proposed converter is connected to the power network, and the corresponding controller already includes a current sensor, eliminating the need for additional sensors and the associated costs. The same line current sensor feedback signal can also be used for voltage balancing control. Two voltage sensors can be used for DC voltage feedback, and the switching strategy includes multi-carrier PWM driven by the voltage effects listed in Table 2. According to this switching strategy, redundant switching states are selected based on feedback from the current and voltage sensors.

[0065] 2D, in some embodiments, the five-level unidirectional rectifier may be configured as a unidirectional charger that only converts AC voltage to DC by replacing the high voltage power switches 130a, 130b with two diodes 132a, 132b. Those skilled in the art will appreciate that the use of a five-level unidirectional rectifier does not affect the functionality of the present invention and may be used as an alternative to the five-level circuitry of any of the embodiments described herein.

[0066] In some embodiments, the five-level circuit is bidirectional, meaning that it can convert voltage / current from AC to DC in rectifier mode as shown in Figure 2A, and from DC to AC in inverter mode as shown in Figure 2E. When operating in rectifier mode, the present invention has a DC output.

[0067] In inverter mode, the high-voltage capacitor (V o ) can be used for, for example, isolated DC sources, batteries, The 5-level circuit can generate AC voltage / current from such a DC input. The AC current can be fed into the network when operating in network-tied mode, or used as a power source to power normal AC loads. The inverter mode can be used in vehicle-to-grid applications to supply power from a vehicle to a power grid, to cover peak loads on the grid, or to supply power to important loads in a home during a power outage.

[0068] 2E, a topology 200 of a five-level power converter operating in inverter mode is shown, according to one embodiment. The circuit includes only switching elements, and an AC load 202 is connected between a first terminal 135 and a second terminal 160, which represent the only node in the circuit. The voltage developed between the first terminal 135 and the second terminal 160 is the inverter output voltage (V), e.g., a five-level pulse-width modulated (PWM) waveform.

[0069] Although PWM has been mentioned herein in describing the control scheme for implementing the proposed five-level inverter, it will be understood that other control schemes may be used, such as, but not limited to, Selective Harmonics Elimination PWM and An Optimized Harmonics Stepped Waveform is available. In addition, phase difference PWM (Shift PWM), pure sine wave PWM (Sinusoidal Natural PWM), and PWM modulation schemes such as Programmed PWM and Open Loop are also available. Open loop and closed loop schemes are also available. Examples of open loop schemes include Space Vector and Sigma Delta. Examples of closed loop schemes include Hilbert Hysteresis Current Controller, Linear Current Controller Linear Current Controller, DDB Current Controller ), and an Optimized Current Controller.

[0070] In an exemplary embodiment, the five-level inverter circuit 200 can generate five different output voltages using various combinations of on / off switch states. The six switches 130a, 130b, 140a, 140b, 150a, and 150b are implemented using bipolar junction transistors (BJTs). Parasitic diodes inherent in BJTs are also shown to indicate the direction of biasing, specifically reverse biasing, of the transistors, allowing them to function as switches without shorting. However, the switches can be implemented using other means, such as thyristors, such as gate turn-off thyristors (GTOs) or integrated gate commutated thyristors (IGCTs), relays, insulated gate bipolar transistors (IGBTs), metal-oxide semiconductor field-effect transistors (MOSFETs), or other suitable controllable switches.

[0071] Circuit 200 further includes elements 206 and 208 connected in a closed loop, with elements 206 and 208 respectively connected to four of switching devices 130a, 130b, 140a, 140b, 150a, and 150b. Element 206 is, for example, a DC source (i.e., a battery or a solar panel), while element 208 is a dependent voltage source, for example, an energy storage device such as a capacitor (shown) or a combination of capacitors (not shown), used as an auxiliary power source.

[0072] Although circuit 200 is described as including one element 208, forming a five-level inverter, additional elements 208 may be added to form additional inverter output levels, as will be described in more detail below.

[0073] FIG. 3A is a schematic diagram illustrating voltage balancing control implemented in a modulator 305 with voltage balancing functionality. As shown, in this embodiment, a modulator 310 that performs 5-level PWM is used. In this embodiment, a 4-carrier PWM scheme is used to modulate a reference signal 320 as shown in FIG. 3B. Therefore, the reference signal 320 is modulated by a control circuit 305, which will be described later. The output of modulator 310 is provided by a state selection circuit 315, which applies the logic shown in Tables 1 and 2 to generate signals S1, S2, S3, and their inverted (NOT) forms S4, S5, and S6 as inputs to the switches. State selection circuit 315 allows for fast voltage balancing to be integrated into the switching scheme, allowing for the appropriate use of small capacitors as auxiliary capacitors. Figure 3C shows a schematic diagram of the algorithm used. It shows the logic elements of both modulator 310 and state selection circuit 315, which use voltage feedback to provide eight signals indicating different states. Figure 3E shows the same logic elements when both current and voltage feedback are used.

[0074] FIG. 3D shows an alternative configuration in which both the modulator 310 and the state selection circuit 315 logic elements provide five signals representing different states without using any feedback.

[0075] These signals are used by the pulse generator module 325 to generate pulse outputs to the switches. In one embodiment, the pulse generator 325 may be a switch table programmable in a microcontroller.

[0076] Those skilled in the art will appreciate that the digital switching signals pass through gate drivers before reaching the switches.

[0077] 3A shows that the voltage balancing unit uses voltage feedback. However, the voltage balancing unit may use either voltage feedback or current feedback. Using both feedbacks allows for more reliable balancing of the capacitor voltages.

[0078] A schematic diagram of one algorithm that can be used is shown in Figure 3E, which shows the logic elements of both the modulator 310 and the state selection circuit 315 using voltage and current feedback to provide eight signals representing different states. This configuration also provides relatively good performance.

[0079] In one embodiment, block 315 selects an optimal switching state number (see Table 1) and notifies module 325. Based on the state number, switching pulses (S1 to S6) are generated. For example, if block 315 selects state 1, based on Table 1, S1, S5, and S6 are turned on, and complementary S2, S3, and S4 are turned off.

[0080] In one embodiment, the reference signal 320 in FIG. 4 is V refcan be considered to be . The controller 410 of the system is a cascade proportional-integral (PI) controller. This controller will be described below. As described above, according to the configuration of this embodiment, the auxiliary capacitor voltage is balanced and controlled by the switching state, making it possible to use it as a single DC power inverter. While some of the proposed topologies use two DC capacitors for rectification, in this embodiment, the auxiliary capacitor voltage is controlled by the proposed switching method, eliminating the need for an additional voltage regulator. Therefore, the output of the DC terminal can be fixed at a desired level using only one external voltage controller. In this embodiment, the desired level is 200V. As a result, a simple cascade PI controller can be used to not only regulate the DC output voltage, but also control the input current to maintain the same voltage as the grid voltage. The controller 410 can synchronize the V o and i s Adjust.

[0081] In some embodiments of the present disclosure, the controller (block 405) shown in FIG. 4 includes a current loop and a voltage loop. The voltage loop is responsible for fixing the C1 voltage to a reference voltage. A proportional-integral (PI) controller minimizes the voltage error and provides its output as a current reference to the current loop. The current loop is responsible for controlling the grid voltage (v s ) and v s and i s To adjust the phase shift of the current, the current error is sent to another PI controller (called PFC). (For power factor correction, a phase shift of 0 degrees is desired, but this can be adjusted to any value for reactive power exchange with the power network.) Because the two loops are in series, this is called a linear cascade PI controller. The output of the controller is a reference signal (320) that is sent to modulator 305 to balance the second capacitor voltage (C2), generating switching pulses based on the redundant state.

[0082] However, as will be appreciated by those skilled in the art, other types of controllers may be used in the present disclosure, such as nonlinear, model predictive control, sliding mode control, or any other suitable controller known in the art.

[0083] The controller may consist of a processor-based microcontroller running control software that utilizes inputs from sensors and outputs gate control signals to a digital system according to the logic described herein. The controller may also include analog circuitry using active and passive elements that may incorporate a portion of the system voltage and current feedback to provide a reference signal to the modulator.

[0084] 3D is a schematic diagram illustrating an algorithm used in some embodiments of the present disclosure, in which the state selection circuit 315 provides eight signals representing different states in a sensorless configuration. Additionally, FIG. 3D illustrates the logic elements of the switching section 340 used in one embodiment of the present disclosure when the charging converter operates in inverter mode. Those skilled in the art will appreciate that the generation of switching pulses and voltage balancing control for the auxiliary capacitor (low-voltage capacitor) in a five-level configuration is applicable when the converter operates in both rectifier and inverter modes, and is not limited to operation in only one mode.

[0085] 10, it can be seen that the controller 410 also controls a DC-DC buck or boost converter depending on the desired DC output voltage requested by the BMS. In FIG. 10, this is a simple buck or boost converter, controlled by switch S7 using feedback of the DC output voltage measured by a sensor.

[0086] Furthermore, those skilled in the art will understand that any type of buck converter or boost converter, or buck-boost converter, known in the art may be used without affecting the practice of the present invention. Two important topologies are known as buck-boost converters, which can generate output voltages ranging from a voltage significantly greater in amplitude (in absolute value) than the input voltage to a voltage that is nearly zero.

[0087] The first topology is an inverting topology, which generates an output voltage with the opposite polarity to the input. This corresponds to a switching power supply, and the circuit topology is similar to boost and buck converters. The output voltage varies depending on the duty cycle of the switching transistor. It can be adjusted based on the

[0088] The second topology is a combination of a buck converter and a boost converter, where the output voltage has the same polarity as the input, but can be lower or higher than the input. This non-inverting buck-boost converter uses a switch instead of a diode, allowing a single inductor to be used in both buck and boost inductor modes.

[0089] In the embodiment shown in FIG. 4, the controller 410 o Voltage was received as input Reference Level V ref and adjusts to the grid current i sto eliminate or reduce harmonics in the grid current and to align the grid current phase with the grid voltage, thereby providing unity or near unity power factor (e.g., PF=99.99%) operation. A schematic diagram of an exemplary embodiment of a controller 410 is shown in Figure 4, where the current and / or voltage from the sensors are sampled by the controller 410 as needed (e.g., approximately every 20 microseconds).

[0090] The voltage regulator generates a reference current (i s *) By adjusting the amplitude of V o In this embodiment, the PFC mode is guaranteed by taking unit samples of the grid voltage to generate the reference current shape. The controller output 320 is modulated using a standard four-carrier PWM scheme and sent out as the desired pulses.

[0091] Next, we describe the results of experiments conducted on the battery charging rectifier 100. In one example, a silicon carbide (SiC)-based five-level converter was actually tested. Six SCT2080KE SiC MOSFETs with a breakdown voltage of 1.2 kV and a capacity of 40 A were used as active switches. The proposed voltage balancing control was incorporated into the switching scheme, and a cascade controller was implemented in dSpace1103. This sent switching pulses to the five-level switches. The system parameters used in the test are listed in Table 3. [Table 3]

[0092] In an alternative embodiment, the AC input (mains) voltage may be approximately 240V RMS and the DC load may be greater than 350V, which is supplied by boost mode rectification as described herein.

[0093] At 1 kW, a stable condition was observed, as shown in Figure 5. As shown, the output voltage 3 at the DC terminals was adjusted to 200 V (curve 1, with the reference point shown as 0 V2 corresponding to point 1 on the vertical axis). Also, as shown at the bottom of the graph, the 50.0 V unit was used. The voltage ripple was less than 10%, which is an acceptable level. c Due to the balance control effect of V in teeth , 0, ±100, and ±200 V, and harmonic pollution was also smaller than that of the two-level voltage waveform. In addition, the PFC operation of the battery charging rectifier 100 was s (The reference point on curve 3, designated as 0V, corresponds to point 4 on the vertical axis. Also, as shown at the bottom of the graph, each represents 100.0 V.) and the input current waveform i s (The reference point on curve 4, designated 0A2, corresponds to point 4 on the vertical axis. As shown at the bottom of the diagram, each represents 10.0 A. l (The reference point of curve 2, designated as 0A2, is the point on the vertical axis. 2. Also, as shown at the bottom of the figure, the current (representing 10.0 A each) was measured to be approximately 5 A. This shows the effectiveness of the 1 kW operating system.

[0094] Figure 6 shows some other parameters measured by the AEMC® power analyzer. As will be appreciated, the battery charging rectifier 100 was tested at 1 kW with a power factor of maximum (close to unity). This significantly reduces reactive power and ensures good performance of the controller that synchronizes the line current to the grid voltage. In addition, the multi-level voltage waveform produced by the five-level rectifier has low harmonic pollution, which also results in low THD of the current (IEEE 519 and IEC 61000 standards require the line current THD to be less than 5%).

[0095] In this test, the load magnitude was intentionally changed by 50% (from 38 Ω to 75 Ω) to test the dynamic performance of the controller. As shown in Figure 7, the load current was reduced to approximately half its original amplitude. This resulted in a change in the amount of energy delivered to the load, which in turn caused a change in V o (The reference point on curve 1, designated 0V2, corresponds to point 1 on the vertical axis. As shown at the bottom of the graph, each scale represents 50.0 V.) fluctuations were observed, but they were sufficiently stabilized by the controller and voltage balance control, and no unexpected overshoot or undershoot occurred. In addition, the AC input current remained synchronized with the grid voltage even while its amplitude was changing in the stage before transitioning to stable mode. It can also be seen that current harmonics were also eliminated during this transition period. In other words, a 50% reduction in the DC load (load current i l (Curve 2) is reduced to 50%: Reference point 0A2 is the vertical The DC voltage is controlled to a desired level while the point (corresponding to point 2 on the axis) is observed.

[0096] As can be seen from the actual results of the battery charging rectifier 100, the controller and voltage balancing control incorporated in the modulation process exhibited good dynamic performance. The auxiliary capacitor voltage was regulated to the desired level with low voltage ripple, in part due to the fast and accurate voltage balancing control, which produces a five-level quasi-sine wave with low harmonic content at the rectifier input. Such a multi-level waveform allows for the use of smaller filters to remove line current harmonics. Therefore, the battery charging rectifier 100 is suitable for use in traction systems or other applications for EVs. is suitable for industrial rectifiers used in battery chargers and is a strong choice.

[0097] The voltage balancing control is designed to generate five uniform voltage levels at the rectifier input by adjusting the auxiliary capacitor voltage within the switching pattern, resulting in a smooth five-level voltage waveform with minimal harmonic content. The proposed rectifier implements a standard cascaded PI controller, which is possible in part because it has only one DC terminal and no split capacitors on the output side. Actual testing of the battery charging rectifier 100 incorporating the voltage balancing control and controller under steady-state and varying load conditions demonstrated good dynamic performance, making it a promising product for the PFC rectifier market.

[0098] To achieve a 7-level / 3-capacitor configuration, two switches and one low-voltage capacitor must be added. The modulation block must also be modified to accommodate six carriers. The voltage balancing section must also be modified because the number of switching states for capacitor charging / discharging and voltage adjustment has increased.

[0099] As shown in FIG. 8A, the battery charger includes battery charging rectifier 100 and other similarly configured battery charging rectifier circuits in parallel, operating in parallel to provide DC power to a load. To this end, the battery charger includes a housing with a connector backplane having multiple sockets. These sockets are configured to accommodate multiple battery charging rectifier modules of the type described herein, although a common controller may be used, as shown in FIG. 8A. An advantage of this modular design is that while initial installation of the backplane may be performed by a professional electrician, modules 100 can be added or replaced by the end user as needed. The modular design described does not limit the number of modules 100. However, applicants have found that a 5 kW rectifier module is effective, particularly with the rectifier design described above. Six such rectifiers can provide a total of approximately 30 kW of DC charging power. This amount of power is suitable for fast battery charging and is within the power capacity limits of most conventional single-phase power supplies.

[0100] In actual implementation, a battery charger including the battery charging rectifier 100 may include a user-interchangeable DC vehicle charging cable and charging plug, for example, a compatible type that can use a standard plug / socket (i.e., SAE J1772, ChaDeMo, etc.). It may also be one of the following.

[0101] FIG. 8A also shows how a battery and charge controller (also known as a battery management system, or BMS) 810 is connected to a battery charge controller interface 820 and controller 830 by a charging cable 815. The charging cable 815 provides a data path for the interface 820 and a high-voltage DC conductor connected to a backplane 840. The interface 820 may be any interface known in the art for EV DC chargers and receives data or signals from the BMS indicating information regarding charging voltage and / or current parameters. The interface 820 may be associated with a computer that provides the controller 830. The computer 830 may provide V and V for one or more rectifier circuits 100. ref Value of back play The computer 830 may be part of the circuit 100 or may use sensors that are part of the backplane 840, and in either case may receive the current provided to the battery 810. The data interface, AC input, and DC output connections of the module 100 are shown in FIG. 10 and described in more detail below. The computer 830 may be any suitable processor with program memory for managing charging control.

[0102] In some embodiments of the present invention, as shown in Figure 8B, AC current from the power receiving panel enters a connector, such as a switch, which directs the AC current to a battery and charge controller to provide the user with a Level 2 AC charger for the EV battery, or to a rectifier circuit to provide a Level 3 DC charger for the EV, providing a DC output, so the user can select between a Level 2 AC charger for the EV or a Level 3 DC charger for the EV.

[0103] FIG. 8C shows the backplane directly attached to the connectors or switches, or 1 shows an embodiment that can be attached via a module connector. When the switch is connected to the backplane, the charger's AC output is supplied to the battery, providing the user with a Level 2 EV AC charger.

[0104] Figure 8D shows the same embodiment as Figure 8C, except that the switch has been physically removed by a user from the module connector, thereby interrupting AC current to the AC output. The switch has then been replaced with one or more battery charging rectifiers, such as module 100, thus upgrading the charger to a Level 3 DC EV charger. This configuration allows a user to install a universal, relatively inexpensive Level 2 EV AC battery charger, although it may not provide fast and efficient vehicle charging, assuming it can be easily upgraded to a fast and efficient Level 3 DC EV charger.

[0105] 11, the switch may have a branch 200 that includes a surcharge prevention module, and this branch may be configured to connect to the backplane directly or via a module connector, similar to the rectifier branch 100. In this embodiment, the user must remove the branch 200 when replacing it with the rectifier branch 100.

[0106] Those skilled in the art will appreciate that any type of connector can be used as the backplane, and the module connector is merely intended to aid and simplify the installation process for the user. Additionally, in some embodiments, the switch and backplane may be a single element that performs the function of interrupting the AC output and allowing current to be sent to the rectifier circuit.

[0107] Furthermore, as will be apparent to those skilled in the art, although different from the above description, the controller 830 and / or battery charge controller interface 820 and other elements of the charger, like the rectifier branch 100, may be add-on modules or load branches that can be retrofitted to the device. In other words, the original charger may simply be a backplane with inputs and outputs, and can be upgraded to a DC charging station by simply adding a few modules or branches.

[0108] Additionally, as will be appreciated by those skilled in the art, the AC and DC outputs may be physically separate outlets or cables, or may be the same, and in some embodiments, the outlets may be in communication with the vehicle's charger controller.

[0109] FIG. 9 is a block diagram illustrating a battery charger for a storage battery. The power source is connected to a local distribution transformer of a power network via a sensor and a main breaker with a predetermined current threshold. The sensor indicates the current drawn by the power source. A battery charge controller interface communicates with the storage battery to receive a charging voltage and a desired charging current. A rectifier circuit is connected to the power source to receive single-phase AC power and can output a stepped-down or stepped-up DC voltage using, for example, a DC buck-boost converter circuit. The buck converter has control inputs that define the DC output voltage and current. As shown in FIG. 10, a controller 410 can control the buck-boost converter to output the desired DC voltage and current.

[0110] In another broader aspect, the present disclosure provides a power converter for connecting to an AC input and converting power from the AC input to DC, the power converter including at least one high voltage capacitor for storing power boosted to a voltage higher than the peak voltage of the AC input. The power converter includes an inductor connected in series with the AC input, a low-voltage capacitor, either two diodes or two high-voltage switches connected between the first AC input terminal and both ends of the high-voltage capacitor, two intermediate low-voltage power switches connected between both ends of the high-voltage capacitor and both ends of the low-voltage capacitor, and two end low-voltage power switches connected between both ends of the low-voltage capacitor and the second AC input terminal. A DC load can be connected across the high-voltage capacitor. The power converter further includes a controller having at least one sensor for sensing current and / or voltage in the rectifier circuit and connected to gate inputs of the two intermediate low-voltage power switches and the two end low-voltage power switches.

[0111] In some embodiments, the controller operates the rectifier circuit in a boost mode, where the voltage on the high-voltage capacitor is higher than the peak voltage of the AC input, and the two middle low-voltage power switches and the two end low-voltage power switches are switched in redundant switching states responsive to a measurement of the low-voltage capacitor voltage, such that the low-voltage capacitor is maintained at a predetermined percentage of the desired voltage on the high-voltage capacitor, thereby maintaining the high-voltage capacitor at the desired high voltage, and the rectifier circuit acts as a five-level active rectifier to supply DC loads and absorb power while suppressing harmonics of the AC input.

[0112] In some embodiments, the power converter includes a bidirectional rectifier / inverter circuit instead of a rectifier circuit, and two controllers instead of one controller that functions bidirectionally as both a rectifier and an inverter. The bidirectional rectifier / inverter circuit includes an inductor connected in series with the AC port, a low-voltage capacitor, two high-voltage power switches connected between the first AC terminal and both ends of the high-voltage capacitor, two intermediate / low-voltage power switches connected between both ends of the high-voltage capacitor and both ends of the low-voltage capacitor, and two end low-voltage power switches connected between both ends of the low-voltage capacitor and the second AC input terminal. A DC load can be connected across the high-voltage capacitor. The power converter further includes a first controller for the rectifier mode, the first controller having at least one sensor for sensing current and / or voltage of the bidirectional rectifier / inverter and connected to gate inputs of the two high-voltage power switches, the two intermediate / low-voltage power switches, and the two end low-voltage power switches, for operating the rectifier circuit in boost mode. The voltage of the high-voltage capacitor is higher than the peak voltage of the AC input. The two high-voltage power switches are controlled to switch on and off at the frequency of the AC input. The two middle low-voltage power switches and the two end low-voltage power switches are switched in redundant switching states in response to a measurement of the low-voltage capacitor voltage, thereby maintaining the low-voltage capacitor at a predetermined percentage of the desired voltage of the high-voltage capacitor, thereby maintaining the high-voltage capacitor at the desired high voltage. The rectifier circuit acts as a five-level active rectifier to supply power to the DC load and absorb power while suppressing harmonics of the AC input. The power converter further includes a second controller for inverter mode.The second controller is connected to the two high-voltage power switches, the two intermediate-low-voltage power switches, and the two terminal low-voltage power switches, and is configured to generate a signal waveform including a first control signal and a signal waveform including a second control signal and apply them to the two high-voltage power switches, the two intermediate-low-voltage power switches, and the two terminal low-voltage power switches, where the first control signal is a signal that connects the low-voltage capacitor in series to the DC port and the AC port and charges the low-voltage capacitor to a predetermined value proportional to the voltage of the DC port, and the second signal is a signal that disconnects the low-voltage capacitor from the DC port and connects it in series to the AC port, thereby discharging the low-voltage capacitor.

[0113] 9, a network interface 902 may be a conventional data interface such as Ethernet, Wi-Fi, etc., and is associated with a computer 830. A logging module 904, a power amount controller 906, an available power Available power predictor 908 and charging power program module 9 10 can be implemented by software stored in the memory of the computer 830, and when executed by the processor of the computer 830, can realize the processes described below.

[0114] The logging module stores in its memory at least one parameter derived from the current draw measured by the sensor. It also stores all power drawn by the rectifier circuit during various times of day. For non-charging loads, this parameter may indicate the maximum expected increase in that load during that time period. A sudden increase in load can occur when one or more appliances are turned on. For example, AC motors, such as those in heat pumps and air conditioners, typically require at least twice their normal current during startup. Naturally, the increase in power draw can be limited to a desired probability, e.g., within 97%.

[0115] The available power prediction calculator receives the draw current value and the logging module parameters and calculates a maximum charging load value as a function of a predetermined power source maximum power load. The power source maximum load value can be set using a user interface (not shown). The energy controller receives the maximum charging load value, as well as a desired charging voltage value and a desired charging current value from the power management interface, and provides a control input to the rectifier circuit.

[0116] In one embodiment, the greatest probable increase is determined based on long-term observational data. Until this data is available, the power availability forecaster makes more conservative forecasts, and as the accuracy of the forecasts improves, the forecasts become more aggressive.

[0117] In another embodiment, fluctuations in power consumption are analyzed to identify the number and quantity of major household loads. Then, behavioral patterns of these loads are detected. Simply turning off loads estimated to be on can eliminate the possibility that these loads will increase the total load. The likelihood that a load will be turned on depends on the status of other loads, the time of day, and the time of year. For example, if a water heater is turned off, the likelihood that the water heater will be turned on is higher between 7:00 AM and 8:00 AM than between 11:00 PM and 6:00 AM, given water usage. In addition, in summer, heating electric loads are less likely to be turned on, but air conditioning loads are more likely to be turned on, and vice versa in winter. The available power forecasting unit can predict the maximum expected increase in power that may occur in the near future based on the behavioral patterns of the loads to be turned on and the current forecast.

[0118] The power controller determines the power that the charger can consume, taking into account the risk of the maximum expected increase in power, and if the requested power is too high, the power controller controls the rectifier circuit and / or the DC-DC down converter to adjust the DC power supplied to the EV.

[0119] Furthermore, the power controller can determine the charging rate by taking into account battery degradation, using a predetermined maximum charging current or maximum power value, or by referring to a charging priority level selected by the user, as described below.

[0120] When the available power prediction module predicts that a power increase exceeding the power capacity (power draw limit) is likely to occur, an optional sheddable load switch is used to prevent large loads from drawing power, thereby preventing the power capacity from being exceeded. This allows the power source to delay or shift the added load and prevent it from exceeding its power capacity. The system may include a line voltage power switch connected between one or more electrical loads, such as a water heater, and the power panel to prevent the load from drawing current from the power panel, thereby preventing the load from increasing and potentially exceeding the power capacity. Preferably, the load switch includes a sensor, such as a current sensor, to measure whether the load is currently drawing current. In this configuration, the energy controller can detect whether the load is currently drawing power. In an open state, the load limit switch may include a sensor to detect whether the disconnected load is requesting power, in which case the energy controller may determine whether to reconnect the load after reducing the DC charging power.

[0121] Some high-current loads have standby load requirements of less than about 100 watts, for example. In this case, low AC power may be diverted to supply the limitable load while the load-shedding switch is open. An example of a connection that diverts low AC power is an isolation transformer configured to provide tens to tens of watts of power to the limitable load. When the load is turned on, the load-shedding switch module detects the power draw on the load side of the isolation transformer and sends a signal to the energy controller to determine whether to reduce DC charging power and reconnect the limitable load to allow full AC power, or to continue DC charging at the same rate. When the load demand for DC charging ends, the limitable load is allowed to reconnect.

[0122] The embodiment shown in FIG. 9 includes a charging power program module that, in response to user input, reduces the charging rate when the user is not in a hurry to charge the EV. While the EV is configured for fast charging, embodiments of the present disclosure also allow charging at approximately 25 kVA of power. Fast charging can shorten the battery's lifespan. Additionally, the charging power program module can be used to select charging timing settings, specifically, to delay charging timing and / or adjust it to time-varying energy costs and / or available power on the grid. The charging connector can provide a user interface for selecting, for example, charging priorities, specifically, variable charging rates when the battery requires a higher charging rate. Alternatively, a network interface can be provided to serve as a remote user interface for setting charging power program parameters.

[0123] In some embodiments, a user can redirect AC current drawn from the power panel to an AC output using a switch or other connector, which can then feed AC current directly to the battery charge controller, bypassing the rectifier circuit. This allows the user to choose between AC and DC charging modes. In an alternative embodiment, the battery charger does not include a rectifier circuit, but has a backplane that allows for a rectifier circuit to be added later. This provides the user with a Level 2 EV AC battery charger that can be upgraded to a Level 3 EV DC charger capable of powering a storage battery.

[0124] As will be appreciated by those skilled in the art, the backplane of the present disclosure can be realized by a simple connector if it incorporates control units such as a power controller, available power prediction unit, network interface, and charging power program module, or it can be realized by a backplane having a module connector to which such control units can be additionally connected.

[0125] Figure 10 shows a schematic representation of one "branch" 100 of the modular system shown in Figure 8A. In the embodiment shown, a printed circuit board is provided, along one edge of which are provided a high voltage AC connector, a high voltage DC connector, and a connector for a data interface. Branch 100 contains the power switches of the power converter, in this embodiment six switches S1 to S6 arranged in a five-level active rectifier and one switch S7 arranged in a buck-boost converter for DC-DC step-down or step-up conversion.

[0126] The capacitors 120 are mounted in a small module with a socket for connecting to the branch 100 plug. The performance of the high-voltage capacitors 120 is important for the proper and safe operation of the rectifier. Therefore, timely replacement is recommended. The socket may include an identification circuit readable by the controller 410 to determine various information. First, the circuit is used to determine whether a new capacitor has been installed as needed. Second, the circuit is used to determine whether the capacitor has been previously installed. This can be determined in various ways. For example, the controller 410 identifies each capacitor 120 with a unique ID and reports its usage to an external database. This database can be queried when a new capacitor is plugged in. Alternatively, the identification circuit may be mounted in the capacitor plug module and usage information may be stored in a non-volatile memory readable by the controller 410. In this way, when a new capacitor module is connected to the branch 100, the controller 410 can determine whether the capacitor 120 is new, has been used for some time, or has expired. If the capacitor 120 has expired, the controller 410 can stop supplying power and issue a warning to replace the capacitor 120 .

[0127] The branch module 100 may be connected via a cable rather than at the end as shown. The capacitor module sockets may be located on the branch 100 as shown in Figure 10, or may be located elsewhere, such as on another part of the backplane (see Figure 8A).

[0128] The socket includes a switch that detects whether the capacitor plug module has been removed or is exposed for removal, so that the capacitor module 120 can be safely removed and replaced by cutting off power to one or more branches 100. Each branch 100 shown in Figure 10 has its own controller 410, although a common controller 410 that controls the switches of multiple branches may be provided on a backplane.

[0129] The sensor block shown in Figure 10 is connected to measure the voltage across the low voltage capacitor, the DC output current, and the DC output voltage. Other values ​​can also be measured if desired. The measured values ​​are sent to the controller 410.

[0130] 11 is a schematic diagram of an alternative embodiment of the present invention, in which an AC charging branch 1100 includes an over-power prevention module 1102. AC current enters the branch from the AC input and passes through the over-power prevention module 1102 to the AC output. The over-power prevention module is also capable of communicating with the charging controller interface and uses a data port to set the AC output current and voltage required by the EV.

[0131] 12, in one embodiment of the present invention, a portable DC charging unit 1200 is provided. The portable DC charging unit has a housing 1202 including an AC input 1204 and a DC output 1208, where the AC input is connected to an AC source 1204 via cable 1206 and the DC output is connected to an EV via cable 1210. The portable DC charging unit 1200 includes one or more five-level rectifier circuits.

[0132] In one embodiment, the portable DC charging unit 1200 includes multiple identical 5-level battery charging rectifier circuits in parallel, as shown in FIG. 13, with each rectifier circuit operating in parallel. To this end, the battery charger housing 1202 includes a connector backplane 1302 containing a plurality of sockets 1304, each configured to receive a respective branch module 1306 that comprises a five-level battery rectifier circuit of the type described.

[0133] Such a modular configuration allows a portable charger to be sold with only one 5-level rectifier circuit installed, with the end user being able to add or replace modules 1306 as needed. The number of modules 1302 in the described modular configuration is not particularly limited.

[0134] In some embodiments, the portable charging unit operates in a bidirectional mode or a unidirectional mode. In the bidirectional mode, the portable charger functions as both an inverter and a rectifier. In the unidirectional mode, the converter functions as a rectifier, as previously described in other embodiments of the present invention.

[0135] A unidirectional mode five-level rectifier circuit can be configured with two diodes instead of the two high-voltage switches shown in Figure 2D.

[0136] Unlike on-board charging units, the portable charging unit 1200 has the advantage of drawing AC current with a near-unity power factor and low harmonic content from the utility power source. Furthermore, in some embodiments, the portable charging unit 1200 can implement any of the features of other non-on-board charging units, such as higher KW transfer, more advanced battery management systems, battery thermal management, communication with building / home / power networks, energy management systems, and higher energy transfer rates. The portable charging unit 1200 of the present disclosure also allows EV manufacturers the option of not including a charging unit on the vehicle, thereby reducing vehicle weight, and offering the portable charging unit 1200 as an option for vehicle charging.

[0137] 14A and 14B, in some embodiments, an electric vehicle may include a receptor 1402 in the trunk for the connector 1212 with a sensor (not shown) connected to a driver display that indicates whether a portable DC charging unit is present in the trunk of the vehicle. This prevents the user from leaving the portable charging unit behind after charging or when traveling. The sensor may be a simple mechanical switch that is depressed when the connector is plugged into the receptor 1402, or any other type of mechanical, electrical, or electronic sensor known in the art may be utilized.

[0138] In some embodiments, the electric vehicle may have a separate receptor instead of receptor 1402 to which the housing and cable of portable DC charging unit 1200 can be attached, thereby achieving similar display functionality.

[0139] In one embodiment, the portable charging unit 1200 may include, for example, a radio frequency identification (RFID) sensor or a Bluetooth sensor instead of the receptor 1402. (registered trademark) A wireless presence indicator, such as a sensor, may be provided to indicate that a portable DC charger is near the vehicle.

[0140] It should be understood by those skilled in the art that circuits such as the five-level rectifier circuits described herein may be applied to any AC-DC conversion system, such as a DC power supply, other EV chargers, other types of battery chargers, or other configurations requiring AC-DC conversion.

[0141] Although the above description refers to specific embodiments, this is for purposes of illustration only and is not intended to be a limitation of the present invention.

Claims

1. A battery charger for supplying power to a storage battery, an AC input for receiving power from a power source; a battery charge controller interface for communicating with the storage battery and receiving a charging voltage value; a power converter connected to the AC input, converting power from the AC input into DC in accordance with the charging voltage value, and outputting a variable voltage for a DC load in accordance with the charging voltage value; The power converter comprises: at least one high voltage capacitor for storing power boosted to a voltage exceeding the peak voltage of the AC input; a rectifier circuit; The rectifier circuit comprises: an inductor connected in series with the AC input; A low-voltage capacitor two diodes respectively connected between the first AC input terminal and both ends of the high-voltage capacitor; at least one of two high-voltage switches connected between the first AC input terminal and both ends of the high-voltage capacitor; two intermediate low-voltage power switches connected between the ends of the high-voltage capacitor and the ends of the low-voltage capacitor; two terminating low-voltage power switches connected between the two ends of the low-voltage capacitor and a second AC input terminal; a DC load can be connected across the high-voltage capacitor; The power converter further comprises: a controller that receives as input the charging voltage value, at least one reference signal from the AC input, and a voltage of the at least one high-voltage capacitor, and outputs a gate control signal, the output of which is connected to one of the two high-voltage switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches, or the two intermediate low-voltage power switches and the two terminal low-voltage power switches; and a processor and a non-volatile memory that stores instructions that are executable by the processor, the instructions causing the controller to set the output of the gate control signal to comply with the charging voltage value according to the reference signal and the voltage of the at least one high-voltage capacitor.

2. 2. The charger of claim 1, wherein the controller is operative to operate the rectifier circuit in a boost mode, wherein a voltage on the high-voltage capacitor is greater than a peak voltage of the AC input, the two intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in redundant switching states responsive to a measurement of the low-voltage capacitor voltage, whereby the low-voltage capacitor is maintained at a predetermined percentage of a desired high-voltage capacitor voltage, thereby maintaining the high-voltage capacitor at a desired high voltage, and the rectifier circuit acts as a five-level active rectifier to supply the DC load and absorb power while suppressing harmonics of the AC input.

3. 3. The charger of claim 1, wherein the battery charge controller interface is further in communication with the storage battery to receive a desired charging current value, and the power converter is further configured to convert power from the AC input to DC in response to the desired charging current value, and to provide a DC output for a DC load with a variable current not exceeding the desired charging current value.

4. The charger according to any one of claims 1 to 3, further comprising a buck converter circuit that converts DC power from both ends of the high-voltage capacitor into a low DC output voltage set by the charging voltage value.

5. 5. The charger according to claim 1, further comprising a boost converter circuit that boosts and converts DC power from both ends of the high-voltage capacitor to a high DC output voltage set by the charging voltage value.

6. 6. The charger of claim 1, further comprising a socket-type connector for removing and replacing the high-voltage capacitor from the rectifier circuit.

7. 7. The charger of claim 6, wherein the high-voltage capacitor is incorporated into a plug-in module that includes at least one electronic identification component and an interface for connecting the electronic identification component to the controller, and the controller is configured to inhibit operation when the electronic identification component is missing or when the controller is unable to properly identify the plug-in module.

8. A charger according to any preceding claim, wherein the two intermediate low-voltage power switches and the two terminal low-voltage power switches are switched at a frequency exceeding 3 kHz.

9. 9. The charger of claim 1, wherein the AC input voltage is about 240V RMS and the DC output power voltage is greater than 350V.

10. 10. The charger of claim 1, wherein the charger comprises a housing including a connector backplane having a plurality of module sockets and at least one module connected to the module sockets, each of the modules comprising the rectifier circuit, and the modules operate in parallel to supply DC power to the load.

11. 11. The charger of claim 10, wherein the high-voltage capacitor in each of the modules has a capacitance of approximately 4 millifarads.

12. The rectifier circuit is a bidirectional rectifier / inverter circuit including an inductor connected in series with an AC port, a low-voltage capacitor, two high-voltage power switches respectively connected between a first AC terminal and both ends of the high-voltage capacitor, and two intermediate low-voltage power switches respectively connected between the ends of the high-voltage capacitor and both ends of the low-voltage capacitor. and two terminating low-voltage power switches respectively connected between the two ends of the low-voltage capacitor and a second AC input terminal, and a DC port can be connected to the two ends of the high-voltage capacitor; The processor and the non-volatile memory storing instructions executed by the processor configure the controller to one of the following: a) a rectifier mode in which the output of the gate control signal is set to comply with the charging voltage value according to the reference signal and the voltage of the at least one high-voltage capacitor; and b) Inverter mode, which sets the output of the gate control signal according to the desired AC output voltage.

12. The battery charger according to claim 1, wherein the battery charger is set to one of the above states.

13. 12. The charger according to claim 10 or 11, wherein the charger is a portable charger and further comprises an AC cable, a DC cable, and a housing, each of the modules comprises the rectifier circuit, and the modules operate in parallel to supply DC power to the load.

14. The DC output is a DC port, and the AC input is an AC port; 14. The charger of claim 13, which is bidirectional and converts DC power from the DC port to an AC load with an AC voltage at the AC port.

15. 15. The charger of claim 14, wherein the AC cable is selected based on a desired AC voltage of the AC input or the AC load.

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