A dynamic DC bus system and method for connecting different electrical power elements with different characteristics thereto

Abstract

A dynamic DC bus system for connecting N electrical power elements is presented. The system comprises one or more voltage stabilization elements, one or more controllers and N power control devices (PCD), each of the N PCDs is connected to one of the N electrical power elements, and comprises two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to one or more of the N electrical power elements. The switching mode of the switches is controlled by control signals generated by the one or more controllers such that the switching mode of the switches controls the one or more inductor's current and the loading of the electrical power elements and the switching mode of one or more PCDs controls the voltage of the one or more voltage stabilization elements.

Description

[0001] A DYNAMIC DC BUS SYSTEM AND METHOD FOR CONNECTING DIFFERENT ELECTRICAL POWER ELEMENTS WITH DIFFERENT CHARACTERISTICS THERETO

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to dynamic DC bus systems and methods for connecting electrical power elements.

[0004] BACKGROUND

[0005] With the emerging concept of smart grid, a customer's building facility can consume, generate, and store energy. The demand for high power systems, especially due to the emerging use of Electric Vehicles (EVs) and the demand for fast charging, emphasizes the need for connecting electrical power elements such as energy banks or energy sources and loads, in parallel. The most common form of energy banks / sources is of a large size Battery Energy Storage System (BESS) with high energy and power capabilities.

[0006] The common approach today for connecting electrical power element such as Electronic Energy Banks (EB) or Electronic Energy Sources (ES) or electronic load (EL) is to serially connect strings of EB or ES or EL and then connect these strings in parallel to achieve higher energy and power, while maintaining a reasonable and safe level of voltage, (since in a parallel connection the voltage stays constant and just the current increases it allows to achieve higher energy). This approach is limited to connecting only identical energy banks or energy sources in parallel with similar performances condition. When it comes to batteries, similar state of charge (SOC) is an additional constraint. In addition, during the system lifetime, the characteristics or performances of the energy banks or energy sources are changing, and the characteristic of the whole system is determined by the part with the lower performing characteristics.

[0007] A common way to overcome the drawbacks of directly parallel connected electrical power elements such as EB or ES or EL is to use DC-DC converters on every electrical power element (i.e., on each ES or EB or EL ) or to use DC-DC converters on every string of electrical power elements (string of ESs or string of EBs or ELs).

[0008] In addition in sites that contain ES, EB and EL with different electrical characteristics the common approach is to use converter on every ES, EB and EL (or group of them). Then connecting the outputs of the DC-DC converters together in parallel.

[0009] This solution dramatically increases the overall cost and size of the system, in addition it reduces the system efficiency due to high conversion losses.

[0010] There is therefore a need to provide systems and methods for connecting different electrical power elements with different characteristics providing the features of parallel connection, which are cost effective, small size and yet keeping system efficiency.

[0011] SUMMARY

[0012] The present disclosure relates generally to dynamic DC bus systems and methods for connection of different electrical power elements such as energy sources or energy banks or strings with different voltages and current characteristics. Advantageously, the systems presented herein may improve performance of paralleled connection of identical energy banks and sources by enabling different current characteristics as well as enabling changing the structure of the system during the operation of the system such that ES or EB with weak characteristics can be bypassed out of the system or loaded in its optimal loading characteristics so the system will not be dependent on the weakest electrical power element and would not significantly affect the overall performance of the system.

[0013] Advantageously, according to some embodiments, the systems and methods of the present disclosure dramatically reduces the cost, size and conversion losses while keeping the simplicity and reliability of the system, compared to the traditionally used solution of DC-DC converters.

[0014] According to some embodiments, advantageously, the system presented herein controls the output voltage and / or current of every electrical power element, for example, ES or EB or a string of serially connected ESs or EB. The control is achieved by a switching system and an inductor that switches between the different electrical power elements (ES or EB or a string of serially connected ESs or EB), or between the electrical power element / s and a capacitor or capacitors. In case of capacitors, the system also regulates the voltage over the capacitors to a desired optimal value. The use of the switching system with the inductor in the specific connection configuration enables to switch the differential voltage between the different electrical power elements, instead of switching the whole voltage of the electrical power element in traditional use of DC-DC converters, enables dramatic reduction of the cost and size and dramatic improvement of the efficiency. Advantageously, the presented system allows to keep the flexibility in the type of the electrical power elements as ES or EB which are being used in the system and enables reconfiguration of the inner electrical power elements (which supply energy) of the system during operation.

[0015] According to some embodiments, a dynamic DC bus system for connecting N electrical power elements, is presented. The system comprises: one or more voltage stabilization elements; one or more controllers; and

[0016] N power control devices (PCD), each of the N PCDs is connected to one of the N electrical power elements, and comprises two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to one or more of the N electrical power elements; wherein the switching mode of the two or more switches is controlled by control signals generated by the one or more controllers such that: the switching mode of the two or more switches controls the one or more inductor’s current and the loading of the N electrical power elements and the switching mode of one or more PCDs controls the voltage of the one or more voltage stabilization elements.

[0017] According to some embodiments, the first outlet connects the one or more inductors to the first bus or each of the two or more switches to the first bus, and the second outlet connects the one or more inductors to the second bus or each of the two or more switches to the second bus, and the one or more outlets connected to one or more of the N electrical power elements connects the one or more inductors to the one or more of the N electrical power elements bus or each of the two or more switches to the one or more of the N electrical power elements.

[0018] According to some embodiments, the PCD comprises one or more current sensors and / or a voltage sensor.

[0019] According to some embodiments, the electrical power elements characteristics are identical or different.

[0020] According to some embodiments, the controller is inside the PCD. According to some embodiments, the control signals are Pulse Width Modulation (PWM) or a frequency modulation signals or a phase modulation signals and wherein the control signals are complementary or not complementary.

[0021] According to some embodiments, the PCD further comprising outlets for connecting to one or more additional buses.

[0022] According to some embodiments, the one or more voltage stabilization elements are capacitors or electrical power elements.

[0023] According to some embodiments, electrical power elements comprises one or more members of the following: electrical energy sources and / or bank and / or loads and / or converters and / or Photo Voltaic sources and / or a generator and / or a battery and / or an electrical vehicle and / or AC\DC inverter and / or fuel cell and / or turbine and / or energy harvesting element or capacitor or supercapacitor or parallel connection or string connection of any combination thereof or any combination thereof.

[0024] According to some embodiments, the N electrical power elements comprising groups of electrical power elements connected through a switching system such that each electrical element power of the group can be bypassed and / or switched out.

[0025] According to some embodiments, a first terminal of the N electrical power elements is connected to the PCD and a second terminal of the N electrical power elements is connected to a mutual connection point.

[0026] According to some embodiments, the electrical power elements comprises electrical vehicle batteries.

[0027] According to some embodiments, for PV sources, the controller and PCD provide / uses as a Max Power Point tracking (MPPT).

[0028] According to some embodiments, the electrical energy sources are voltage sources or current sources.

[0029] According to some embodiments, the PCD comprising two switches and an inductor.

[0030] According to some embodiments, the voltage of the electrical power elements connected to the PCD is higher than the voltage of the bus with the lower voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is lower than the voltage of the bus with the higher voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is between the voltage of the first and second bus. According to some embodiments, the system further comprising an electrical management system (EMS) for measuring the parameters of the electrical power elements and receives requirements from an external interface, to determine the optimal loading or operation of each electrical power element in the system. For example, in case of a battery a battery management system is used to determine the optimal loading of each battery in the system.

[0031] According to some embodiments, a method for connecting N electrical power elements to a dynamic DC bus system is presented herein. The method comprising the steps of: connecting each electrical power elements to one or more controllers and to a Power Control Device (PCD) comprising two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to the one or more of the N electrical power elements, wherein one or more voltage stabilization elements are connected between the first bus and the second bus and / or between one of the first or second buses and a mutual connection point; controlling current or loading of each electrical power element by generating control signals by the one or more controllers, which control the two or more switches switching mode such that: the switching mode of the two or more switches controls the one or more inductor’s current and the loading of the electrical power elements and the switching mode of two or more PCDs controls the voltage of the one or more voltage stabilization elements.

[0032] According to some embodiments, differential voltage between the electrical power elements and / or the power stabilization elements is created and / or used for controlling the current or loading of every electrical power element.

[0033] According to some embodiments, the switches only switch the differential voltage between the electrical power elements and / or the power stabilization elements.

[0034] According to some embodiments, the first bus voltage is higher than the voltage of the electrical power elements connected to the PCD and the voltage of the electrical power elements connected to the PCD is higher than the second bus voltage. According to some embodiments, the voltage of the electrical power elements connected to the PCD is higher than the voltage of the bus with the lower voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is lower than the voltage of the bus with the higher voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is between the voltage of the first and second bus.

[0035] According to some embodiments, a method for connecting two electrical power elements with different electrical characteristics to a bidirectional converter or load is presented. The method comprising the steps of: connecting the two electrical power elements to an inductor and the bidirectional converter or load via two complementary switches, wherein a first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2; and controlling the complementary switches by a PWM signal provided by a controller, such that the switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enabling controlling the current or loading of each electrical power element.

[0036] According to some embodiments, a system for connecting two electrical power elements with different electrical characteristics to a third electrical power element is presented. The system comprising: an inductor; and two complementary switches controlled by a PWM signal from a controller; wherein a first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2; and wherein the two switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enable controlling the current or loading of each electrical power element.

[0037] According to some embodiments, a system for connecting a plurality of electrical power elements with different electrical characteristics as presented above is presented. According to some embodiments, the system is used as an electrical power element, enabling cascade connection of further systems as electrical power elements.

[0038] BRIEF DESCRIPTION OF THE FIGURES

[0039] Some embodiments of the disclosure are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments may be practiced. The figures are for the purpose of illustrative description and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the disclosure. For the sake of clarity, some objects depicted in the figures are not drawn to scale. Moreover, two different objects in the same figure may be drawn to different scales. In particular, the scale of some objects may be greatly exaggerated as compared to other objects in the same figure.

[0040] In the figures:

[0041] FIG. 1 schematically shows a flowchart of a method 100 for connecting two electrical power elements with different electrical characteristics to a third electrical power element, according to some embodiments;

[0042] FIG. 2 schematically shows a circuit of system 200 for connecting two electrical power elements with different electrical characteristics to a third electrical power element, according to some embodiments;

[0043] FIG. 3 schematically shows a circuit of a system 300 for connecting N electrical power elements, according to some embodiments;

[0044] FIG. 4 schematically shows an example of a Power control device (PCD) 400 and outlet connections, according to some embodiments; FIG. 5A schematically shows an example of an additional configuration of a PCD 500 and outlet connections, according to some embodiments;

[0045] FIG. 5B schematically shows an example of a system 550 which includes five PCDs, each PCD with a different configuration and different outlet connection, according to some embodiments;

[0046] FIG. 6 schematically shows a flowchart of a method for connecting N electrical power elements, according to some embodiments; and

[0047] FIG. 7 schematically shows an example for the use of a system for connecting N electrical power elements and the advantages of using said system, according to some embodiments.

[0048] DETAILED DESCRIPTION

[0049] The principles, uses, and implementations of the teachings herein may be better understood with reference to the accompanying description and figures. Upon perusal of the description and figures present herein, one skilled in the art will be able to implement the teachings herein without undue effort or experimentation. In the figures, same reference numerals refer to same parts throughout.

[0050] In the description and claims of the application, the words “include” and “have”, and forms thereof, are not limited to members in a list with which the words may be associated.

[0051] As used herein, the term “about” may be used to specify a value of a quantity or parameter (e.g., the length of an element) to within a continuous range of values in the neighborhood of (and including) a given (stated) value. According to some embodiments, “about” may specify the value of a parameter to be between 80 % and 120 % of the given value. For example, the statement “the length of the element is equal to about 1 m” is equivalent to the statement “the length of the element is between 0.8 m and 1.2 m”. According to some embodiments, “about” may specify the value of a parameter to be between 90 % and 110 % of the given value. According to some embodiments, “about” may specify the value of a parameter to be between 95 % and 105 % of the given value.

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise.

[0053] It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0054] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0055] It will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and the claims.

[0056] As used herein the term electrical power element / s refers to any electrical element which supplies power, voltage or current for example, an energy source may be a voltage source or a current source, and energy bank may be an energy storage source such as a battery or a rechargeable battery which may be consuming energy. The electrical power element / s may be strings of serially connected energy sources or strings of serially connected energy banks, a combination of energy sources and energy banks serially connected or any combination thereof. In addition, a bidirectional load / s or converter / s or capacitor or supercapacitor may also be used as an electrical power element.

[0057] As used herein the term switch refers to one or more transistors (for example: filed effect transistor (FET), bipolar junction transistor (BJT), insulated gate bipolar transistor (IGBT)) or a diode or a contactor or a relay or any element that blocks current or presents high resistance to one current direction or to both current directions or any element that blocks current to one direction or to both directions and its blocking current characteristics are changing upon receiving logic or current or voltage signals.

[0058] As used herein the term loading refers to the power an electrical element draws or provides, by controlling the current and or voltage. For example, in a case where the current is constant the voltage is controlled, in a case where the voltage is constant the current is controlled and / or in case the power is constant, the current and / or voltage are controlled.

[0059] As used herein the term bus refers to a terminal to which two or more electrical elements are connected. For example, a PCD, a capacitor, an inductor and the like.

[0060] According to some embodiments, presented herein are systems and methods for connecting electrical power elements.

[0061] According to some embodiments, a method for connecting two electrical power elements with different electrical characteristics to a third electrical power element, is presented and includes the steps of: connecting the two electrical power elements to an inductor and the third electrical power element via two complementary switches, wherein a first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2; and controlling the complementary switches by a PWM signal provided by a controller, such that the switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enabling controlling the current or loading of each electrical power element.

[0062] According to some embodiments a system for connecting two electrical power elements with different electrical characteristics to a third electrical power element, is presented. The system includes an inductor and two complementary switches controlled by a PWM signal from a controller. A first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2, and wherein the two switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enable controlling the current or loading of each electrical power element.

[0063] According to some embodiments, a system, for connecting N electrical power elements, is presented. The system includes one or more voltage stabilization elements, one or more controllers and N power control devices (PCD). Each of the N PCDs is connected to a first port of one of the electrical power elements, and comprises two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to one or more of the N electrical power elements, wherein the switching mode of the two or more switches is controlled by control signals generated by the one or more controllers such that: the switching mode of the two or more switches controls the one or more inductor’s current and / or voltage of the one or more voltage stabilization elements, and controls the loading of the electrical power elements.

[0064] According to some embodiments, a method for connecting N electrical power elements, is presented, the method includes the steps of: connecting each electrical power element to one or more controllers and to a Power Control Device (PCD) which includes switches, one or more inductors, a first outlet (of the PCD) connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to one or more of the N electrical power elements, wherein one or more voltage stabilization elements are connected between the first bus and the second bus and between one of the first or second buses and a mutual connection point, and controlling current or loading of each electrical power element by generating control signals by the one or more controllers, which control the switching mode of the two or more switches such that: the switching mode of the two or more switches controls the one or more inductor’s current and / or voltage of the one or more voltage stabilization elements and controls the loading of the electrical power elements.

[0065] Reference is now made to FIG. 1, which schematically shows a flowchart of a method 100 for connecting two electrical power elements with different electrical characteristics to a third electrical power element, according to some embodiments. At step 101 the two electrical power elements are connected to an inductor and to the third electrical power element via two complementary switches. A first switch is connected to the first electrical power element providing voltage Vsl and a second switch is connected to the second electrical power element providing voltage Vs2. At step 102 the complementary switches are controlled by a PWM signal provided by a controller, such that the switches switch only the differential voltage Vsl- Vs2 and control the current of each of the two electrical power elements, as a function of the duty cycle of the PWM signal and enabling controlling the current or loading of each electrical power element. Reference is now made to FIG. 2, which schematically shows a circuit of system 200 for connecting two electrical power elements with different electrical characteristics to a third electrical power element, according to some embodiments. System 200 includes an inductor 201, two switches 202 and 203 and a controller 206 which controls switches 202 and 203. According to some embodiments, system 200 is configured to connect electrical power elements 204 and 205 to a third electrical power element 207, through switches 202 and 203 and inductor 201. G1 is a mutual connection point, which in this case is considered as a zerovoltage point of system 200. The negative voltage terminal of electrical power element 204 is connected to zero-voltage point G1 and the positive voltage terminal of electrical power element 204 is connected to switch 202.

[0066] The negative voltage terminal of electrical power element 205 is connected to zerovoltage point G1 and the positive voltage terminal of electrical power element 205 is connected to switch 203. Switches 202 and 203 are connected to each other and are connected to a first terminal of inductor 201 at point 208. A third electrical power element 207 is connected to a second terminal of inductor 201 and to zero-voltage point Gl. According to some embodiments, electrical power element 207 may be for example, a load, a bidirectional load or a converter. According to some embodiments controller 206 may be a Microcontroller Unit (MCU). According to some embodiments, electrical power elements 204 and 205 may be voltage sources or current sources. According to some embodiments electrical power elements 204 and 205 may be any one of the following: electrical energy sources and / or bank and / or loads and / or converters and / or Photo Voltaic (PV) sources and / or a generator and / or a battery and / or an electrical vehicle and / or AC\DC inverter and / or fuel cell and / or turbine and / or energy harvesting element or capacitor or supercapacitor or parallel connection or string connection of any combination thereof, or any combination thereof.

[0067] According to some embodiments, a capacitor may be connected between switch 202 and switch 203 (not shown). According to some embodiments, switches 202 and 203 are complimentary switches, such that when switch 202 is conducting, switch 203 is not conducting, and when switch 203 is conducting, switch 202 is not conducting. Generally, it can be said that the total time period of the switching system is T=T202on+T203on where T202011 denotes the time switch 202 is conducting and T203011 denotes the time 203 is conducting, excluding a negligible period of time where both switches 202 and 203 may be not conducting. According to some embodiments, switches 202 and 203 are controlled by controller 206, which generates a Pulse Width Modulation (PWM) signal which controls the conducting times of switches 202 and 203.

[0068] According to some embodiments, electrical power element 205 provides voltage Vsl and electrical voltage 204 provides voltage Vs2. According to some embodiments, switches 204 and 205 switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enable controlling the current or loading of each electrical power element.

[0069] A mathematical representation of the deferential voltage switching operation is described herein:

[0070] Assuming the analysis is in steady state, meaning the average current \voltages are constant.

[0071] The analysis is called “volt second” over the inductor, meaning that the average voltage over the inductor is zero every switching period.

[0072] According to the steady state assumption:

[0073] 1. A / L= 0 the average cuurent on the inductor is not changing)

[0074] According to the inductor voltage equation:

[0075] 2. VL= LIL

[0076] The integral form of equation 2 is: therefore the average current is received by where Tonis the time where only switch 202 is conducting

[0077] Toff is the time switch 202 is off and only switch 203 is conducting.

[0078] In addition the inductor voltage is:

[0079] 5- ^Lon Ksl—^out where Vsl is the voltage provided by electrical power element 202, and Vs2 is the voltage provided by electrical power element 203.

[0080] The total switching period T is defined:

[0081] Defining:

[0082] 8. 0 = —

[0083] T substituting equations 4 and 5 in equation 2, it is received: dividing by T it is received:

[0084] Substituting equations 7 and 9 it is received:

[0085] 13.

[0086] From equation 13 it can be seen that output voltage may be controlled by changing the Duty cycle (D), using Kirchhoffs voltage law (KVL) it can be seen that the voltage over the switches is only FS1— VSz. In addition, the voltage over the the inductor at the TOff becomes VS2-Vout. In comparison, for example in a traditional buck converter (a DC-DC converter) the inductor voltage at the off time is (-Vout), and the voltage on the switches is Vsi. This shows that in system 200 the volage over the inductor is lower and the voltage over the switches is lower such that the induction of the inductor may be lower so that its price and size are smaller and the switches become cheaper. In addition, according to some embodiments, the current of each electrical power elements is controlled by the switches and inductors, which may be useful in various applications, for example in batteries array-based application where sometimes it is desired to provide a controlled low current from a low battery (low state of health (SOH) or state of charge (SOC)). According to some embodiments, the PWM signal controls the conducting times of switches 202 and 203 and therefore controls the currents received from each electrical power element 204 and 205. According to some embodiments, the time that switch 202 is conducting all the current to the third electrical power element 207 is received from electrical power element 205. In addition, during the time switch 203 is conducting all the current to the third electrical power element 207 is received from electrical power element 204. This way, according to some embodiments, by controlling the Duty Cycle of the complementary PWM signals a control on the current density of each electrical power element is achieved.

[0087] A mathematical representation of this operation is described herein:

[0088] 14- IESI = D * lioad

[0089] 15- IES2 = (1 — D) * lioad

[0090] 16. D =;and

[0091] Hoad

[0092] 17. D = 1 hoad

[0093] Where:

[0094] 1ES1denotes the average current flow received from electrical power element 205 (ESI)

[0095] 1ES2denotes the average current flow received from electrical power element 204 (ES2) lioad represents the average current flow into the third electrical power element 207.

[0096] According to some embodiments the current lioad is not directly controlled, but it is a current that may be controlled by changing other electrical characteristics of the system (e.g., IESI and IESI) or it may be a given current controlled by power element 207.

[0097] According to some embodiments, system 200 may be used as an electrical power element, enabling cascade connection of further systems (similar to system 200) as electrical power elements, thereby allowing connection of a plurality of electrical power elements with different electrical characteristics.

[0098] According to some embodiments, a method and system for connecting N electrical power elements are presented.

[0099] FIG. 3 schematically shows a circuit of a system 300 for connecting N electrical power elements, according to some embodiments. System 300 includes one or more voltage stabilization elements 309, one or more controllers 306, N power control devices (PCDs)310i, 3102, 3103, . . ., 310N, two buses 315 and 316 and an additional PCD 310N+I. PCDS 310I-310N are used to connect the N electrical power elements and the additional PCD 310N+I is used to connect a bidirectional load or converter 307 to the system. Each PCD is connected to the first and second buses 315 and 316. According to some embodiments, voltage stabilization elements 309a, 309b may be one or more capacitors or an additional electrical power element. The voltage stabilization elements are used to ease the stabilization of the system. The one or more controllers 306 may be a single controller which controls all N PCD’s or alternatively, it may include N controllers where each controller is connected to one PCD and controls it separately. According to some embodiments, the controller may be inside the PCD.

[0100] According to some embodiments, each of the N PCDs is connected to a first port of one of the N electrical power elements 31 li, 3112, 3113. . .31 IN such that one PCD is connected to at least one electrical power element.

[0101] Reference is now made to FIG. 4 which schematically shows an example of a configuration of a PCD (Power control device) 400 and outlet connections, according to some embodiments. PCD 400 includes two or more controlled switches 402 and 403, and one or more inductors 401. PCD 400 may optionally include one or more sensors 404 which may be a current sensor and / or a voltage sensor.

[0102] According to some embodiments, PCD 400 also includes outlets which are configured to connect PCD 400 to a system for connecting N electrical power elements such as system 300. PCD 400, includes a first outlet 405 connected or connectable to a first bus 315 in system 300, a second outlet 406 connected or connectable to a second bus 316 in system 300 and one or more outlets 407 connected or connectable to one or more of the N electrical power elements or load / s 311I-311N. According to some embodiments, PCD 400 optionally includes an outlet 408 which is connected or connectable to the one or more controllers 306, when the controller is outside of PCD 400. According to some embodiments, one or more controllers 306 may be included in PCD 400. According to some embodiments, the switching mode of the two or more switches in PCD 400 is controlled by control signals generated by the one or more controllers 306, such that the switching mode of the two or more switches controls the one or more inductor’s current and the loading of the electrical power elements connected to said PCD and the switching mode of one or more PCDs controls the voltage of the one or more voltage stabilization elements309a and 309b in system 300.

[0103] According to some embodiments, a second port of the N electrical power elements in system 300 is connected to a mutual connection point, which may be for example a zero-voltage point such as point G1 or another mutual connection point.

[0104] According to some embodiments, PCD 400 may further include outlets for connecting one or more additional buses (for example a third bus, a fourth bus and so on).

[0105] PCD 400 may be controlled by receiving direct Pulse Width Modulation (PWM) signals from an external controller or by receiving a set point (operation mode parameters) and generating the PWM signals. In any of these cases the calculation of the PWM signals is considering upon the current measurement in addition to another measurements and information such as voltage measurements and set point. According to some embodiments, the controller may be inside the PCD.

[0106] According to some embodiments, in some of the operation modes PCD 400 is connected to an electrical power element and regulates the current of the electrical power element by controlling the PWM signals. For example, in case that the voltage of the first bus is higher than the voltage of the second bus PCD 400 will increase the conduction time of switch 403 which leads to increase of current on inductor 401 and on the electrical power element.

[0107] According to some embodiments, the current to or from the electrical power elements is divided between the first bus and the second bus. In a system such as system 300, PCD 310N+I which is connected to the bidirectional load or converter collects or divided the current from or to the first bus and the second bus.

[0108] According to some embodiments, the system disclosed herein (such as system 300) enables the conversion of energy from two or more different electrical power elements (e.g., sources, batteries and the like) by using the voltage difference between the first and second buses for controlling the current or voltage of each electrical power elements individually. System 300 with the use of PCDs as PCD 400 enables to reduce the voltage over the converting components i.e., the switches and the inductor which leads to a simpler process of conversion, with higher efficiency, and lower costs in comparison to the use of conventional DC-DC converter, in addition to a smaller size and dimension. According to some embodiments, PCD 400 may include two switches and an inductor as a half H bridge configuration.

[0109] According to some embodiments, PCD 400 may include four switches and an inductor for example as in a full H bridge configuration.

[0110] FIG. 5A schematically shows an example of an additional configuration of a PCD 500 and outlet connections, according to some embodiments. PCD 500 includes an inductor 501 and four switches 502, 503, 504, 505. The positive terminal of inductor 501 is connected between switches 502 and 503. The negative terminal of inductor 501 is connected between switches 504 and 505. Switch 502 is connected or connectable to an electrical power element, switch 505 is connected or connectable to a first bus (such as bus 315), and switches 503 and 504 are connected or connectable to a second bus (such as bus 316). According to some embodiments, the use of this configuration at the PCD, enables to the voltage of the electrical power elements which are connected to the PCD being higher than the voltage of the first and second bus voltages. Moreover, another possible connection of the outlets may be in case switches 502 and 505 are connected to the first bus, switch 503 is connected to an electrical power element and switch 504 is connected to the second bus, it enables to the voltage of the electrical power elements which are connected to the PCD being lower than the voltage of the first and second bus voltages.

[0111] According to some embodiments, the characteristics of electrical power elements 31 li, 3112, 3113,..., 31 IN may be identical or different.

[0112] According to some embodiments, the control signals may be Pulse Width Modulation (PWM) or a frequency modulation signals or phase modulation signals. In addition, the control signals are complementary.

[0113] According to some embodiments, electrical power elements 3111, 3112, 3113, ... ,311N may be one or more members of the following: electrical energy sources and / or bank and / or loads and / or converters and / or Photo Voltaic sources and / or a generator and / or a battery and / or an electrical vehicle and / or AC\DC inverter and / or fuel cell and / or turbine and / or energy harvesting element or capacitor or supercapacitor or parallel connection or string connection of any combination thereof or any combination thereof.

[0114] FIG. 5B schematically shows an example of a system 550 which includes five PCDs, each PCD with a different configuration and different outlet connection, according to some embodiments. As can be seen, according to some embodiments, PCDs 551, 552, 553, 554 and 555 are connected each to a different type of electrical power element.

[0115] According to some embodiments, PCD 551 is connected to an electrical vehicle (EV). PCD 552 is connected to a string of switchable second life batteries, i.e., a string of used batteries which may be bypassed (switched off) when they are out of use (or for any other reason). PCD 553 is connected to an AC / DC inverter or a DC / DC converter. PCD 554 is connected to a Photo Voltaic (PV) cell, and PCD 555 is connected to a voltage source.

[0116] According to some embodiments, the configuration of PCD 551 is a full H bridge configuration where outlet 565a which is connected to first bus 556 from its first end, is connected to the two top switches 570a and 571b from its second end. outlet 565b is connected to the second bus from its first end, and is connected to the down switch 571a from its second end, and outlet 565c is connected to electrical power element 558 from its first end and is connected to down switch 570b from its second end.

[0117] According to some embodiments, the configuration of PCD 552 is a full H bridge configuration where outlet 566a which is connected to first bus 556 from its first end, is connected to switch 572a from its second end. outlet 566b is connected to the second bus from its first end, and is connected to the two down switch 573a and 572b from its second end, and outlet 566c is connected to electrical power element 559 from its first end and is connected to switch 573b from its second end.

[0118] According to some embodiments, the configuration of PCD 553 is a half H bridge configuration where outlet 567a which is connected to the first bus, is connected to inductor 575 from its second end. Outlet 567b which is connected to the second bus from its first end, is connected to the switch 574a from its second end, and outlet 567c which is connected to electrical power element 560, is connected to switch 574b from its second end.

[0119] According to some embodiments, the configuration of PCD 554 is a half H bridge configuration where outlet 568a which is connected to the first bus, is connected to switch 576a from its second end. Outlet 568b which is connected to the second bus from its first end, is connected to inductor 577 from its second end, and outlet 568c which is connected to electrical power element 561, is connected to switch 576b from its second end.

[0120] According to some embodiments, the configuration of PCD 555 is a half H bridge configuration where outlet 569a which is connected to the first bus, is connected to switch 578a from its second end. Outlet 569b which is connected to the second bus from its first end, is connected to switch 578b from its second end, and outlet 569c which is connected to electrical power element 562, is connected to inductor 579 from its second end.

[0121] According to some embodiments, each of the PCD configurations above, with the connection possibilities provides different advantages.

[0122] The configuration of PCD 555 and outlet connections requires the voltage of the power element that is connected to this PCD to be higher than the voltage of bus 557 and lower than the voltage of bus 556.

[0123] The configuration of PCDs 551 and 554 and outlet connections enables the voltage of the power elements that is connected to these PCDs to be any value that is lower than the voltage of bus 556.

[0124] The configuration of PCDs 552 and 553 and outlet connections enables the voltage of the power element that is connected to these PCDs to be any value that is higher than the voltage of bus 557.

[0125] According to some embodiments, first bus 556 and second bus 557 may also be directly connected to an electrical power element. For example, first bus 556 is directly connected to electrical power elements 564, and second bus 557 is directly connected to electrical power elements 562.

[0126] According to some embodiments, the system may include an electrical management system (EMS) for measuring the parameters of the electrical power element / s, and receives requirements from an external interface, to determine the optimal operation of each electrical power element in the system.

[0127] According to some embodiments, the electrical power elements may include electrical vehicle batteries. According to some embodiments, in case the electrical power elements includes one or more batteries or an electrical vehicle battery, system 300 may further include a battery management system (BMS) for measuring the batteries parameters to determine the optimal loading of each battery in system 300.

[0128] According to some embodiments, for Photo Voltaic (PV) sources, the controller and PCD provide / uses as a Max Power Point tracking (MPPT). According to some embodiments, a method for connecting N electrical power elements is presented herein.

[0129] FIG. 6 schematically shows a flowchart of a method for connecting N electrical power elements, according to some embodiments. At step 601 of method 600, each electrical power element of the N electrical power elements is connected to one or more controllers and to a Power Control Device (PCD) (such as PCD 400). According to some embodiments, each electrical power element may be an energy source for example a current source or a voltage source, or an energy bank for example a battery. The electrical power element may also be a string of energy sources or energy banks serially connected. In addition, it may be a string of a combination of energy sourced and energy banks serially connected. Each electrical power element may also be a generator or a photo voltaic (PV) source, a load or a bidirectional load or a converter or an electrical vehicle or an ACVDC inverter or a fuel cell or a turbine or an energy harvesting element, or capacitor or supercapacitor or a combination of any of the electrical power elements mentioned above. According to some embodiments each of the N electrical power elements has two terminals. A first terminal of the N electrical power elements is connected to the PCD and a second terminal of the N electrical power elements is connected to a mutual connection point.

[0130] The PCD includes two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to the one or more of the N electrical power elements. According to some embodiments, one or more voltage stabilization elements may optionally be connected between the first bus and the second bus and / or between one of the first or second buses and a mutual connection point. At step 602, according to some embodiments, current or loading of each electrical power element is controlled by generating control signals by the one or more controllers, which control the two or more switches switching mode such that the switching mode of the two or more switches controls the one or more inductor’s current and / or voltage of the one or more voltage stabilization elements and controls the loading of the electrical power elements. According to some embodiments, the control signals may be Pulse Width Modulation (PWM) or frequency modulation signals or phase modulation signals. According to some embodiments, the control signals are complementary signals such that the switches are complementary.

[0131] According to some embodiments, differential voltage between the electrical power elements and the power stabilization element is created and / or used for controlling the current or loading of every electrical power element. According to some embodiments, the two or more switches only switch the differential voltage between the electrical power elements and the power stabilization element.

[0132] According to some embodiments, the first bus voltage is higher than the voltage of the electrical power elements connected to the PCD and the voltage of the electrical power elements connected to the PCD is higher than the second bus voltage.

[0133] According to some embodiments, the PCD may include four switches and an inductor, enabling the voltage of the electrical power elements connected to the PCD being higher than the first and second bus voltage.

[0134] According to some embodiments, the N electrical power elements may include groups of electrical power elements connected through a switching system such that each electrical power element of the group may be bypassed and / or switched out.

[0135] FIG. 7 schematically shows an example for the use of a system for connecting N electrical power elements and the advantages of using said system, according to some embodiments.

[0136] In FIG. 7 three electrical power elements are connected to a system 700 for connecting three electrical power elements to a bidirectional converter / load. Each electrical power element is a string of three batteries serially connected. Each battery is connected to a bypass / converter element, allowing to bypass the battery in case the battery is out of use for example due to a low battery condition. When no battery is bypassed the voltage of the three strings is equal and the three strings may be connected in parallel. However, in case one battery in one string, for example battery 705 is bypassed such that the rest of the string may continue working and conducting, the total voltage of the string is reduced, and becomes unequal to the voltage of the two other strings. In this case a parallel connection of the three strings is impossible. According to some embodiments, in this case connecting the three strings (three electrical power elements) via system 700 enables to connect all of the three strings and allows string 710 with the reduced voltage to contribute to the load.

[0137] According to some embodiments, another case for using the system 700 may be when the bypass mechanism is used as a converter, meaning that the switching of battery 705 is done in high frequency in PWM. In this case, instead of bypassing battery 705, and receiving no contribution from it, the connection to the PCD which contains the inductor allows to receive from battery 705, an average contribution of the voltage of battery 705 duplicated by the duty cycle value of the PWM signal .

[0138] It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the disclosure. No feature described in the context of an embodiment is to be considered an essential feature of that embodiment, unless explicitly specified as such.

[0139] Although stages of methods, according to some embodiments, may be described in a specific sequence, the methods of the disclosure may include some or all of the described stages carried out in a different order. In particular, it is to be understood that the order of stages and sub-stages of any of the described methods may be reordered unless the context clearly dictates otherwise, for example, when a later stage requires as input an output of a former stage or when a later stage requires a product of a former stage. A method of the disclosure may include a few of the stages described or all of the stages described. No particular stage in a disclosed method is to be considered an essential stage of that method, unless explicitly specified as such.

[0140] Although the disclosure is described in conjunction with specific embodiments thereof, it is evident that numerous alternatives, modifications, and variations that are apparent to those skilled in the art may exist. Accordingly, the disclosure embraces all such alternatives, modifications, and variations that fall within the scope of the appended claims. It is to be understood that the disclosure is not necessarily limited in its application to the details of construction and the arrangement of the components and / or methods set forth herein. Other embodiments may be practiced, and an embodiment may be carried out in various ways.

[0141] The phraseology and terminology employed herein are for descriptive purpose and should not be regarded as limiting. Citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the disclosure. Section headings are used herein to ease understanding of the specification and should not be construed as necessarily limiting.

Claims

CLAIMS1. A dynamic DC bus system for connecting N electrical power elements, comprising: one or more voltage stabilization elements; one or more controllers; andN power control devices (PCD), each of the N PCDs is connected to one of the N electrical power elements, and comprises two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to one or more of the N electrical power elements; wherein the switching mode of the two or more switches is controlled by control signals generated by the one or more controllers such that: the switching mode of the two or more switches controls the one or more inductor’s current and the loading of the N electrical power elements and the switching mode of one or more PCDs controls the voltage of the one or more voltage stabilization elements.

2. The system of claim 1, wherein the first outlet connects the one or more inductors to the first bus or each of the two or more switches to the first bus, and the second outlet connects the one or more inductors to the second bus or each of the two or more switches to the second bus, and the one or more outlets connected to one or more of the N electrical power elements connects the one or more inductors to the one or more of the N electrical power elements bus or each of the two or more switches to the one or more of the N electrical power elements.

3. The system of claim 1, wherein the PCD comprises one or more current sensors and / or a voltage sensor.

4. The system of claim 1, wherein the electrical power elements characteristics are identical or different.

5. The system of claim 1, wherein the controller is inside the PCD.

6. The system of claim 1, wherein the control signals are Pulse Width Modulation (PWM) or a frequency modulation signals or a phase modulation signals and wherein the control signals are complementary or not complementary.

7. The system of claim 1, wherein the PCD further comprising outlets for connecting to one or more additional buses.

8. The system of claim 1, wherein the one or more voltage stabilization elements are capacitors or electrical power elements.

9. The system of claim 1, wherein electrical power elements comprises one or more members of the following: electrical energy sources and / or bank and / or loads and / or converters and / or Photo Voltaic sources and / or a generator and / or a battery and / or an electrical vehicle and / or AC\DC inverter and / or fuel cell and / or turbine and / or energy harvesting element or capacitor or supercapacitor or parallel connection or string connection of any combination thereof or any combination thereof.

10. The system of claim 1, wherein the N electrical power elements comprising groups of electrical power elements connected through a switching system such that each electrical element power of the group can be bypassed and / or switched out.

11. The system of claim 1, wherein a first terminal of the N electrical power elements is connected to the PCD and a second terminal of the N electrical power elements is connected to a mutual connection point.

12. The system of claim 9, wherein the electrical power elements comprises electrical vehicle batteries.

13. The system of claim 9, wherein for PV sources, the controller and PCD provide / uses as a Max Power Point tracking (MPPT).

14. The system of claim 9, wherein the electrical energy sources are voltage sources or current sources.

15. The system of claim 1, wherein the PCD comprising two switches and an inductor.

16. The system of claim 1, wherein the voltage of the electrical power elements connected to the PCD is higher than the voltage of the bus with the lower voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is lower than the voltage of the bus with the higher voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is between the voltage of the first and second bus.

17. The system of claims 9 and 12, further comprising an electrical management system (EMS) for measuring the parameters of the electrical power elements and receives requirements from an external interface, to determine the optimal loading or operation of each electrical power element in the system of claims 9 and 12.

18. A method for connecting N electrical power elements to a dynamic DC bus system, comprising the steps of: connecting each electrical power elements to one or more controllers and to a Power Control Device (PCD) comprising two or more switches, one or more inductors, a first outlet connected to a first bus, a second outlet connected to a second bus and one or more outlets connected to the one or more of the N electrical power elements, wherein one or more voltage stabilization elements are connected between the first bus and the second bus and / or between one of the first or second buses and a mutual connection point; controlling current or loading of each electrical power element by generating control signals by the one or more controllers, which control the two or more switches switching mode such that: the switching mode of the two or more switches controls the one or more inductor’s current and the loading of the electrical power elements and the switching mode of two or more PCDs controls the voltage of the one or more voltage stabilization elements.

19. The method of claim 18, wherein differential voltage between the electrical power elements and or the power stabilization elements is created and / or used for controlling the current or loading of every electrical power element.

20. The method of claim 18, wherein the switches only switch the differential voltage between the electrical power elements and or the power stabilization elements.

21. The method of claim 18, wherein the first bus voltage is higher than the voltage of the electrical power elements connected to the PCD and the voltage of the electrical power elements connected to the PCD is higher than the second bus voltage.

22. The method of claim 18, wherein the voltage of the electrical power elements connected to the PCD is higher than the voltage of the bus with the lower voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is lower than the voltage of the bus with the higher voltage among the first and second bus voltage or the voltage of the electrical power elements connected to the PCD is between the voltage of the first and second bus.

23. A method for connecting two electrical power elements with different electrical characteristics to a bidirectional converter or load, comprising the steps of: connecting the two electrical power elements to an inductor and the bidirectional converter or load via two complementary switches, wherein a first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2; and controlling the complementary switches by a PWM signal provided by a controller, such that the switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enabling controlling the current or loading of each electrical power element.

124. A system for connecting two electrical power elements with different electrical characteristics to a third electrical power element, comprising: an inductor; and two complementary switches controlled by a PWM signal from a controller; wherein a first switch is connected to a first electrical power element providing voltage Vsl and a second switch is connected to a second electrical power element providing voltage Vs2; and wherein the two switches switch only the differential voltage Vsl-Vs2 and control the current of each electrical power element, as a function of the duty cycle of the PWM signal and enable controlling the current or loading of each electrical power element.

25. A system for connecting a plurality of electrical power elements with different electrical characteristics as in claims 1 or 24, wherein the system of claims 1 or 24 is used as an electrical power element, enabling cascade connection of further systems as in claims 1 or 24 as electrical power elements.

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