EV Charger with an Adaptable Charging Protocol

Abstract

The present disclosure provides a charger comprising an AC port, a variable voltage DC power supply comprising a controller connected to the AC port and having an input for receiving charging parameters, a charging cable connector connectable to a battery, and an interface connectable to the connector and the input of the DC power supply, the interface either converting battery management system voltage commands relating to charging parameters of the battery received via the charging cable connector to the input for the variable voltage DC power supply, or generating the input for the variable voltage DC power supply defining the charging parameters for the battery from measured information about the battery.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 820,474, filed on Mar. 19, 2019, which is incorporated herein by reference.

[0002] The subject matter of this application generally relates to the field of power management systems, and more particularly, to power management systems that work with power converters, such as EV chargers.

Background Art

[0003] This section provides the background or context of the invention as recited in the claims. The description herein may include concepts that, while they may be pursued, are not necessarily concepts that were previously conceived or pursued. Thus, unless otherwise defined herein, what is described in this section is not prior art to the description and claims in this application and is not to be recognized as prior art merely by virtue of its inclusion in this section.

[0004] As more and more people become interested in using renewable and environmentally friendly energy resources, the use of solar panels and electric vehicles becomes more widespread. Such technologies typically need to be connected to and work with the power grid or household electrical wiring. Further, in areas where electricity tariffs vary at different times of the day, it can be more attractive for consumers to use electric vehicles and / or solar energy if they can manage their energy consumption and generation in order to benefit from lower energy tariffs.

[0005] A solar panel or a photovoltaic (hereinafter "PV") system generally has certain advantages as an energy source that generates DC power and produces no pollution or emissions. To use this energy for household appliances, an inverter is usually used. An inverter is a type of electrical converter that converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into commercial frequency alternating current (AC) that can be supplied to the commercial electrical grid or used by a local off-grid electrical network. There are several types of inverters used with solar panels, such as stand-alone inverters, grid-tie inverters, battery backup inverters, and intelligent hybrid inverters.

[0006] When there is no solar power generation, the power generation amount from the solar panel fluctuates and may not be easily synchronized with the electrical consumption of the load. Therefore, in order to manage energy storage and consumption using an intelligent hybrid (smart grid) inverter, it is necessary to store energy for later use, for example, in a battery or other storage system.

[0007] Furthermore, electric vehicles ("EVs") are becoming increasingly popular. As disclosed by the applicant in an international PCT patent application having serial number PCT / CANADA(CA) / 2018 / 051291, published on April 18, 2019 as International Publication (WO) No. 2019 / 071359, new "Level 3" charging systems, such as chargers, can provide DC power for a household charging unit in addition to AC power. It must be said that despite generating DC power, the PV panel output cannot be directly supplied to an EV vehicle to charge the vehicle's battery.

[0008] Since they can rapidly charge an EV using the household electrical network, they can impose a huge load on the household electrical network and potentially more loads on the entire grid. This means that when a Level 3 charger operates, it brings a new load to the household wiring system, and as a result, the wiring system may be overloaded.

[0009] Similarly, using several AC units or frequently used electrical appliances can impose a significant burden on the household electricity budget.

[0010] Therefore, an energy management system is needed that enables a user to manage their energy consumption, including charging their electric vehicle, based on the user's priorities, without overloading the user's home electrical network and without exceeding the budget set for the home.

[0011] On the other hand, despite the fact that an EV's battery and solar panels are good sources of energy, it is currently difficult to use the EV's battery and solar panels to reduce the power load and / or to benefit from lower possible energy tariffs.

[0012] Therefore, a power management system is needed that can manage the power between different loads and sources in order to minimize the household's energy expenditure and / or to assist the power grid as needed.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] The present disclosure provides, among other things, novel and revolutionary solutions for the above-mentioned needs in the art that will be apparent to those skilled in the art when the present disclosure is provided.

Means for Solving the Problem

[0015] The present disclosure provides a charger capable of adapting different communication protocols used by different electric vehicles (EVs) and their battery management systems by using an interface for converting the protocol received from the battery management system (BMS) before sending it to the controller unit of the charger.

[0016] The present disclosure is further advantageous in that it provides a charger having the function of supplying power to two EVs simultaneously using different communication protocols and separately using interfaces.

[0017] In one broad aspect, the present disclosure provides a charger comprising an AC port, a variable voltage DC power source connected to the AC port and having an input for receiving charging parameters, a charging cable connector connectable to a battery, and an interface connectable to the connector and the DC power source input, the interface performing one of the following two jobs. First, converting a battery management system voltage command regarding the charging parameters of the battery received via the charging cable connector into an input for the variable voltage DC power source. Second, generating an input for the variable voltage DC power source that defines the charging parameters for the battery from the measured information about the battery.

[0018] In some embodiments, the interface may be replaceable for converting different types of communication protocols. These communication protocols can be any protocol available in the art, such as the CHAdeMO or Tesla protocol.

[0019] It will be appreciated by those skilled in the art that the interface is designed to provide flexibility to the charger and its functions by operating any other type of protocol and can be programmed.

[0020] In some embodiments, the charger may have two or more interfaces that each operate using a different communication protocol, enabling the charger to simultaneously charge multiple vehicles with different protocols. For example, one connector can be connected to a Tesla cable and used to charge an EV using the Tesla protocol, while the other connector can be connected to a CHAdeMO cable and used to charge an EV using the CHAdeMO protocol. In one embodiment, having multiple interfaces of the charger be the same may enable the charger to charge multiple EVs.

[0021] In some embodiments, the charger may have an interface that is modular and can be selected according to the battery type or BMS protocol. This can be done by having a backplane onto which the modular interface can be added, or alternatively, by direct attachment onto the charger chassis.

[0022] In some embodiments, the charger may be powered from a three-phase power mains and provide DC charging to the EV. Alternatively, the charger may be powered from a single-phase AC power source.

[0023] In some embodiments, the variable voltage DC power supply has at least one conversion module. The conversion module includes at least one high voltage capacitor for storing power at a boosted voltage and a circuit. The circuit includes at least one inductor connected in series with the AC port, a low voltage capacitor, two diodes or high voltage switches connected between the first AC input terminal and the opposing end of the high voltage capacitor, two intermediate low voltage switches connected between the opposing ends of the high voltage capacitor and the opposing ends of the low voltage capacitor, and two terminal low voltage switches connected between the opposing ends of the low voltage capacitor and the second AC terminal. A DC load may be connected to the opposing ends of the high voltage capacitor. The circuit has at least one sensor for sensing current and / or voltage in the circuit and further includes a controller connected to the gate inputs of the two intermediate low voltage switches and the two terminal low voltage power switches.

[0024] In one embodiment, the controller of the circuit may be operable to operate the circuit in a boost mode where the voltage of the high voltage capacitor is higher than the peak voltage of the AC input, and the two intermediate low voltage power switches and the two terminal low voltage power switches are switched in a redundant switching state in response to a measurement of the voltage present on the low voltage capacitor to maintain the low voltage capacitor at a predetermined ratio of a desired voltage for the high voltage capacitor, thus maintaining the high voltage capacitor at a desired high voltage, and the rectifier circuit feeds and absorbs power to the DC load as a 5-level active rectifier with low harmonics on the AC input.

[0025] In one embodiment, the variable voltage DC power supply includes a chassis for storing a plurality of conversion module sockets, each of the modules includes a circuit, and the modules operate in parallel to provide DC power.

[0026] In one embodiment, the circuit can be a bidirectional rectifier / inverter circuit comprising an inductor connected in series with an AC port, a low-voltage capacitor, two high-voltage power switches connected between a first AC terminal and opposing ends of a high-voltage capacitor, two intermediate low-voltage power switches connected between opposing ends of the high-voltage capacitor and opposing ends of the low-voltage capacitor, and two terminal low-voltage power switches connected between opposing ends of the low-voltage capacitor and a second AC terminal. A DC port can be connected to opposing ends of the high-voltage capacitor. The controller is a first controller for the rectifier mode having at least one sensor for sensing current and / or voltage in the bidirectional rectifier / inverter. To operate the rectifier circuit in boost mode, it is connected to the gate inputs of the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches. 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 intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in a redundant switching state in response to a measurement of the voltage present in the low-voltage capacitor to maintain the low-voltage capacitor at a predetermined ratio of a desired voltage for the high-voltage capacitor, thus maintaining the high-voltage capacitor at a desired high voltage. The rectifier circuit feeds and absorbs power from a DC load as a 5-level active rectifier with low harmonics on the AC input. The power converter further comprises a second controller for the inverter mode connected to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches. The second controller generates a signal waveform including a first control signal for connecting the low-voltage capacitor in series with the DC port and the AC port and charging it to a predetermined value proportional to the voltage of the DC port, and a second control signal for disconnecting the low-voltage capacitor from the DC port and connecting it in series with the AC port, thereby discharging the low-voltage capacitor, and is configured to apply the signal waveform to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches.

[0027] In one broad aspect, the present disclosure provides a method for using a converter having a first communication protocol with an electric vehicle (EV). The method includes receiving EV communication from the EV in a second communication protocol at a connector interface of the converter, converting the EV communication from the second communication protocol to the first communication protocol, and in response, controlling the converter to respond to the converted EV communication.

[0028] In some examples of the method, converting the communication from the second communication protocol to the first communication protocol may include determining whether the second communication protocol conforms to the first communication protocol of the converter. If the second communication protocol conforms to the first communication protocol of the converter, relay the EV communication without conversion. If the second communication protocol does not conform to the first communication protocol of the converter, convert the EV communication from the second communication protocol to the first communication protocol.

[0029] In some examples of the method, converting the EV communication from the second communication protocol to the first communication protocol may be performed at a connector interface of the converter.

[0030] In some examples of the method, converting the EV communication from the second communication protocol to the first communication protocol may be performed at a controller of the converter.

[0031] In some other examples, the method may also include sending converter communication in a first communication protocol, converting the converter communication from the first communication protocol to a second communication protocol, and sending the converter communication to the EV. In one example, converting the communication from the first communication protocol to the second communication protocol may include determining whether the first communication protocol conforms to the second communication protocol of the EV. If the first communication protocol conforms to the second communication protocol, relay the converter communication without conversion; if the first communication protocol does not conform to the second communication protocol, convert the converter communication from the first communication protocol to the second communication protocol.

[0032] In some other examples, converting the converter communication from the first communication protocol to the second communication protocol may be performed at the connector interface of the converter.

[0033] In one example, converting the converter communication from the first communication protocol to the second communication protocol may be performed at the controller of the converter.

[0034] This example may be better understood with reference to the following accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

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Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0036] References throughout this specification to "one embodiment", "an embodiment", or similar language mean that the particular features, structures, or characteristics described in connection with that embodiment are included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment", "in an embodiment", and similar language throughout this specification may all refer to the same embodiment, but do not necessarily all refer to the same embodiment.

[0037] Furthermore, the features, structures, or characteristics described in the present invention can be combined in any suitable manner in one or more embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope of the present invention. Therefore, the present invention is intended to cover those modifications and variations provided that they fall within the scope of the appended claims and their equivalents. Next, preferred embodiments of the present invention will be described in detail.

[0038] In one broad aspect, the present disclosure provides a charger comprising an AC port, a variable voltage DC power supply connected to the AC port and having an input for receiving charging parameters, a charging cable connector connectable to a battery, and an interface connectable to the connector and the input of the DC power supply, the interface performing one of the following two jobs. First, converting a battery management system voltage command regarding the charging parameters of the battery received via the charging cable connector into an input for the variable voltage DC power supply. Second, generating an input for the variable voltage DC power supply that defines charging parameters for the battery from measured information about the battery.

[0039] As shown in FIG. 1, the present disclosure provides a charger 100 capable of adapting different communication protocols used by different EVs and their battery management systems by using an interface 102 to convert the protocol received from the BMS104 before sending it to the controller unit of the charger.

[0040] Figure 4 shows the flowchart of the charger shown in Figure 1. The Battery Management System (BMS) 104 communicates with the interface 102 via the connector 108. The connector 108 is connected to a charging cable that carries current and a data cable that carries charging parameters (CP) among other information. The connector 108 transmits the data received in the BMS communication protocol to the interface 102. The interface converts the charging parameters and sends those charging parameters to the controller 110 that controls the variable voltage DC power supply 112. The DC power supply converts the power received from the power supply 106 accordingly and sends that power to the connector 108, and that power is sent directly from the connector 108 to the EV battery 118.

[0041] The present disclosure is further advantageous because it can provide a charger 100 having the function of supplying power to two EVs simultaneously using different communication protocols and using separate interfaces at the same time. Figure 2 is a schematic diagram of such an embodiment. Here, the charger has two interfaces 102 and 102' that communicate individually with BMSs 104 and 104', enabling it to charge two vehicles that may have the same or different communication protocols simultaneously.

[0042] Figure 3 shows a block diagram of a charger 100 having only one interface 102 that receives current from the power supply 106 via the AC port 502.

[0043] Similarly, Figure 5 shows a block diagram of an embodiment of the charger disclosed herein having two connectors 108 and 108' and two interfaces 102 and 102' that provide independent charging to EV batteries 1 and 2.

[0044] In some embodiments, the interface may be replaceable to convert between different types of communication protocols. These communication protocols can be any protocol available in the art, such as CHAdeMO, Combined Charging System (CCS), or Tesla protocol.

[0045] It will be appreciated by those skilled in the art that the interface can be designed and programmed to provide flexibility to the charger and its functionality by operating with any other type of protocol.

[0046] In some embodiments, the charger may have two or more interfaces 102, each operating with a different communication protocol, enabling the charger to simultaneously charge multiple vehicles with different protocols. For example, one connector can connect to a Tesla cable and charge an EV using the Tesla protocol, while the other connector can connect to a CHAdeMO cable and charge an EV using the CHAdeMO protocol. In one embodiment, the charger may be able to charge multiple EVs by having multiple identical interfaces.

[0047] FIG. 6 shows a flowchart of a charger 100 in one embodiment having two interfaces and charging two vehicles, independent of those protocols.

[0048] In some embodiments, the charger may have an interface that is modular and can be selected according to the battery type or BMS protocol. This can be done by having a backplane onto which the modular interface can be added, or alternatively, by direct attachment onto the charger chassis.

[0049] Figure 7 shows a charger 100 with only one interface for charging battery 702. In this scenario, interface 102 can determine the charging parameters required for battery 702 based on the different information it can receive. The information required for interface 102 can be received through a user interface that defines, for example, the battery type and the desired charging voltage rate.

[0050] Alternatively, interface 102 can receive information such as temperature, voltage, current, etc. via a measurement tool or sensor and calculate the charging parameters accordingly. As is known in the art, battery temperature can be used to adjust the charging speed.

[0051] In another example, the battery having an electronic circuit for accommodating charging parameters or other information regarding the battery can enable the interface to determine or convert those charging parameters.

[0052] Figure 8 shows a flowchart used by the charger when interface 102 is used to charge battery 702.

[0053] Next, referring to Figure 9, an example of the method used for communication between a converter having a first communication protocol and an EV having a second communication protocol is shown. Box S902 indicates that communication is received at interface 102. In some examples, this can occur in both directions, meaning that the converter and the EV can communicate with each other through interface 102. The communication is then converted to another communication protocol and relayed, as in the case of box 906.

[0054] In some examples, interface 102 may determine whether the communication protocol is compliant, as in the case of box S904. This would help avoid unnecessary conversion of communication from one communication protocol to another. In this example, communication is only converted if it is not compliant with the other communication protocol, and in other cases, it is only relayed, as in the case of box S908.

[0055] In some other examples, the interface is pre - defined for communication between two specific communication protocols and is installed with connector 108. However, in some embodiments, the interface may be a general - purpose interface capable of receiving different protocols.

[0056] Despite being described as separate elements in different figures, it will be understood by those skilled in the art that it may be an integrated part of the converter's controller.

[0057] In some embodiments, the converter is powered from a three - phase power source and can provide DC charging to the EV. Alternatively, the converter can be powered from a single - phase AC power source using a suitable rectifier circuit.

[0058] In some embodiments, the variable - voltage DC power source has at least one conversion module. The conversion module can be a switched - power - conversion module that draws power from an AC power source, for example, split - phase 240V AC, in the vicinity of a power factor of 1.

[0059] The conversion module may comprise at least one high-voltage capacitor for storing power at a certain voltage and a circuit. The circuit may include at least one inductor connected in series with the AC port, a low-voltage capacitor, two diodes or high-voltage switches connected between the first AC input terminal and the opposite end of the high-voltage capacitor, two intermediate low-voltage switches connected between the opposite ends of the high-voltage capacitor and the opposite ends of the low-voltage capacitor, and two terminal low-voltage switches connected between the opposite ends of the low-voltage capacitor and the second AC terminal. A DC load may be connected to the opposite end of the high-voltage capacitor. The circuit has at least one sensor for sensing current and / or voltage in the circuit and further includes a controller connected to the gate inputs of the two intermediate low-voltage switches and the two terminal low-voltage power switches.

[0060] In one embodiment, the controller of the circuit may be operable to operate the circuit in a boost mode in which the voltage of the high-voltage capacitor is higher than the peak voltage of the AC input. The two intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in a redundant switching state in response to a measurement of the voltage present on the low-voltage capacitor to maintain the low-voltage capacitor at a predetermined ratio of a desired voltage for the high-voltage capacitor, thus maintaining the high-voltage capacitor at the desired high voltage. The rectifier circuit feeds and absorbs power to the DC load as a 5-level active rectifier with low harmonics on the AC input.

[0061] In one embodiment, the variable voltage DC power supply comprises a chassis storing a plurality of conversion module sockets. Each of the modules comprises a circuit and the modules operate in parallel to provide DC power.

[0062] In one embodiment, the circuit can be a bidirectional rectifier / inverter circuit comprising an inductor connected in series with an AC port, a low-voltage capacitor, two high-voltage power switches connected between a first AC terminal and opposing ends of a high-voltage capacitor, two intermediate low-voltage power switches connected between opposing ends of the high-voltage capacitor and opposing ends of the low-voltage capacitor, and two terminal low-voltage power switches connected between opposing ends of the low-voltage capacitor and a second AC terminal. A DC port can be connected to opposing ends of the high-voltage capacitor. The controller is a first controller for the rectifier mode having at least one sensor for sensing current and / or voltage in the bidirectional rectifier / inverter. To operate the rectifier circuit in boost mode, it is connected to the gate inputs of the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches. 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 intermediate low-voltage power switches and the two terminal low-voltage power switches are switched in a redundant switching state in response to a measurement of the voltage present on the low-voltage capacitor to maintain the low-voltage capacitor at a predetermined ratio of a desired voltage for the high-voltage capacitor, and thus maintain the high-voltage capacitor at the desired high voltage. The rectifier circuit feeds power to and absorbs power from a DC load as a 5-level active rectifier with low harmonics on the AC input. The power converter further comprises a second controller for the inverter mode connected to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches. The second controller generates a signal waveform comprising a first control signal for connecting the low-voltage capacitor in series with the DC port and the AC port and charging it to a predetermined value proportional to the voltage of the DC port, and a second control signal for disconnecting the low-voltage capacitor from the DC port and connecting it in series with the AC port, thereby discharging the low-voltage capacitor, and is configured to apply the signal waveform to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches.

Claims

1. An AC port, A variable voltage DC power supply comprising a controller connected to the AC port and having an input for receiving battery charging parameters, A charging cable connector for receiving a charging cable and connectable to a charger for the battery, An exchangeable interface connected to the charging cable connector, configured to communicate with the battery via the charging cable and connected to the input of the controller of the DC power supply, A charger comprising: wherein the interface is Converting a voltage command of a battery management system (BMS) regarding the charging parameters of the battery received via the charging cable connector to the input of the controller of the variable voltage DC power supply; Generating the input for the variable voltage DC power supply for defining the charging parameters for the battery from the measured information about the battery; Configured to perform one of the above; The charging cable connector comprises at least first and second charging cable connectors connectable to chargers for different batteries, The interface comprises at least a first interface and a second interface for communicating according to a first communication protocol and a second communication protocol respectively used for each of the different batteries, The charger, wherein the first and second interfaces are modular and selected according to the battery type or the communication protocol used by the BMS.

2. The charger according to claim 1, wherein the interface communicates with a battery management system (BMS) of the battery to execute converting a voltage command of the battery management system regarding the charging parameters of the battery received via the charging cable connector to the input of the controller for the variable voltage DC power supply.

3. The charger according to claim 1, wherein the first communication protocol and the second communication protocol are the same protocol.

4. The charger according to claim 1, wherein the first communication protocol and the second communication protocol are different.

5. The charger according to claim 1, further comprising a chassis, wherein the first and second interfaces are mounted on the chassis.

6. The charger according to any one of claims 1 to 5, wherein the charger is powered from a three-phase power supply.

7. The charger according to any one of claims 1 to 5, wherein the charger is powered from a single-phase AC power supply.

8. The variable voltage DC power supply has at least one conversion module, and the conversion module includes at least one high voltage capacitor for storing power at a first voltage, a circuit and the circuit includes at least one inductor connected in series with the AC port, a low voltage capacitor for storing power at a second voltage, the second voltage being lower than the first voltage, two diodes connected between the first AC input terminal and the opposing end of the high voltage capacitor, and two high voltage power switches connected between the first AC input terminal and the opposing end of the high voltage capacitor one of two intermediate low voltage power switches connected between the opposing end of the high voltage capacitor and the opposing end of the low voltage capacitor, two terminal low voltage power switches connected between the opposing end of the low voltage capacitor and the second AC terminal and is provided with a DC load can be connected to the opposing end of the high voltage capacitor, the circuit includes a controller having at least one sensor for sensing current and / or voltage in the circuit, the controller being connected to the gate inputs of the two intermediate low voltage power switches and the two terminal low voltage power switches The charger according to any one of claims 1 to 7.

9. The controller is operable to operate the circuit in a boost mode in which the voltage of the high voltage capacitor is higher than the peak voltage of the AC input, and the two intermediate low voltage power switches and the two terminal low voltage power switches respond to a measurement of the voltage present in the low voltage capacitor to maintain the low voltage capacitor at a predetermined ratio of a desired voltage for the high voltage capacitor, and thus maintain the high voltage capacitor at a desired high voltage, and are switched in a redundant switching state, and the circuit powers and absorbs power from the DC load as a five-level active converter with low harmonics on the AC input. The charger according to claim 8.

10. The charger according to claim 8 or 9, wherein the variable voltage DC power supply comprises a chassis for storing a plurality of conversion module sockets, each of the modules comprises the circuit, and the conversion module sockets operate in parallel to supply DC power to the DC load.

11. The circuit comprises 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 the opposing ends of the high voltage capacitor, two intermediate low voltage power switches connected between the opposing ends of the high voltage capacitor and the opposing ends of the low voltage capacitor, and two terminal low voltage power switches connected between the opposing ends of the low voltage capacitor and the second AC terminal, and is a bidirectional rectifier / inverter circuit, and a DC port can be connected to the opposing ends of the high voltage capacitor. The controller is a first controller for the rectifier mode having at least one sensor for sensing current and / or voltage in the bidirectional rectifier / inverter, and is connected to the 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 in boost mode. The voltage of the high voltage capacitor is higher than the peak voltage of the AC input, and the two high voltage power switches are controlled to switch on and off at the frequency of the AC input. The two intermediate low voltage power switches and the two terminal low voltage power switches are switched in a redundant switching state in response to the measurement of the voltage present in the low voltage capacitor to maintain the low voltage capacitor at a predetermined ratio of a desired voltage for the high voltage capacitor, thus maintaining the high voltage capacitor at the desired high voltage. The rectifier supplies power to and absorbs power from the DC load as the five-level active rectifier having low harmonics on the AC input. The circuit further comprises a second controller for an inverter mode connected to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches, the second controller generating a signal waveform including a first control signal for connecting the low-voltage capacitor in series with the DC port and the AC port and charging it to a predetermined value proportional to the voltage of the DC port, and a second control signal for disconnecting the low-voltage capacitor from the DC port, connecting it in series with the AC port, and thereby discharging the low-voltage capacitor, and configured to apply the signal waveform to the two high-voltage power switches, the two intermediate low-voltage power switches, and the two terminal low-voltage power switches, the battery charger according to claim 9 or claim 10 which cites claim 9.

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