Patent Application
20250088070
The following is a tabulation of some prior art that presently appears relevant:
Plugin Electric Vehicle (EV) fast charging and discharging is currently performed by off-board Direct Current (DC) Electric Vehicle Supply Equipment (EVSE), which are bulky and high in cost. In fact, because of their size, weight, and volume, the DC EVSE cannot be integrated onboard the EVs. Current EV's onboard technology does not support fast charging and discharging directly from the grid.
Depending on the EV 102 model/brand, the Bidirectional Inverters 110 and Motors 108 are capable of handling high power and the ESD 112 are capable of storing high energy.
A parked EV 102 can be connected through Connector 114 to an off-board Electric Vehicle Supply Equipment (either AC EVSE 202 or DC EVSE 302) to charge its ESD 112. Power between AC EVSE 202, or DC EVSE 302, and EV 102 can be delivered as AC or as DC through the Connector 114. The charging time is determined by the ESD 112 capacity, its max charging rate, the power of the AC Isolated Charger 118, and the available charging power from AC EVSE 202 or DC EVSE 302.
The communication protocol, physical interconnection, and electrical limits between the off-board EVSE, 202 or 302, and EV 102 are defined by SAE (J2836 and J2847), IEC/ISO (15118-1 and 15118-2), and IEC (62196-1, 62196-2, and 62196-3). In addition to the conductive coupling device Connector 114, the charging and discharging energy can be transferred by other types of coupling devices, including inductive, radiative, and capacitive. SAE J2954 defines the inductive coupling for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology.
The AC EVSE Contactors and Filters 208 connects the onboard AC Isolated Charger 118 to the AC Power Grid 210 and is controlled by the AC EVSE Controller 206. This subsystem 206 also communicates with the AC Isolated Charger 118 on-board the EV 102 through the AC Cable 204 according to SAE or IEC protocol standards depending on brand and model of the EV 102. Simultaneously, 206 communicates with the remote Server 212 though the Network 214. Remote signals of Demand Response (DR) can be sent to the AC Isolated Charger 118 from the Power Utility managing the grid 210 supplying the AC EVSE 202 through the Server 212, the Network 214, and the AC EVSE 202. Thus, DR signals can control the charging power to curtail load on the AC Power Grid 210 as demanded by the Power Utility.
The on-board AC Isolated Charger 118 charges the ESD 112 with charging power typically limited to 20 kW by the weight and size of its isolation transformer mounted within 118 to guarantee isolation between EV 102 and grid. In fact, regardless if the charger is on or off-board, safety standards and codes require isolation between the EV ESD and the grid. This mandates that an isolation transformer is mounted in the on-board charger or in the off-board EVSE between the grid lines and the EV 102 ESD. Electromagnetism laws state that size and weight of an isolation transformer are directly proportional to its power and inversely proportional to its operative frequency. Thus, current practice mandates fast charging with high power chargers that can be located only off-board because of the weight and size of their isolation transformer operating at the low frequency of the grid (50 or 60 Hz).
The DC EVSE 302 includes:
The DC EVSE Controller 306 communicates with the ESD 112 on-board the EV 102 through the DC Cable 304 and Connector 114 according to SAE, IEC, or CHAdeMO protocols depending on brand and model of the EV 102. This subsystem 306, in coordination with the ESD 112, controls the direction and the power of the Isolated Bidirectional Charger/Discharger 308. Simultaneously, 306 communicates with the remote Server 212 though the Network 214.
The DC EVSE 302 is off-board, thus the weight and size of its Isolation Transformer are not constrained and the EVSE power can be high enough to fast or ultra-fast charge (and optionally discharge) the EV 102. DC EVSE of 1,000 pounds (or more) can charge the ESD battery at ultra-high power (250 KW, or above) in a short time. The DC EVSE can be capable only of charging or of charging and discharging the ESD. In the latter case, the EVSE can be also remotely controlled to supply energy to the grid and the EV 102 operates as a Distributed Energy Resource.
Remote signals of Demand Response (DR) and Distributed Energy Resource (DER) can be sent to the ESD 112 from the Power Utility managing the grid 210 supplying the DC EVSE 302 through the Server 212, the Network 214, the DC EVSE 302, and the Connector 114. Thus, DR and DER signals can control the charging and discharging power to curtail load on, or deliver energy to, the AC Power Grid 210.
Power density of power electronic converters has roughly doubled every 10 years since 1970. This trend is due to the continuous advancement of power semiconductor devices, which has allowed an increase in the converter switching frequencies by a factor of 10 every decade. Standard charger technology is approaching the limits of the law of physics: isolated, high efficiency (>96%), high power (>200 kW), high switching frequency (>200 kHz), and water-cooled power converters available on the market have power density and specific power higher than 10 kW/dm3 and 5 kW/kg, respectively. The minimum size and weight of the heat sink (air or liquid cooled) for the electronic components is limited by thermodynamic laws. They are proportional to the power and inversely proportional to their efficiency.
Thus, with the current state of the art, high frequency switching electronics are not a problem. What prevents the integration of a fast charger on-board a vehicle is the weight and size of the isolation transformer. In fact, the isolation required by electric vehicle safety standards does not allow isolation implemented by simple diodes and capacitors circuits.
Combining the motor and the transformer structures in a transmotor device is known in the prior art. The transmotor structure offers space and cost savings and other advantages over the use of separate transformers and motors used in combination in certain applications. In fact, transformers and motors utilize large quantities of ferromagnetic material for the magnetic circuit and conductive material for the windings to accomplish their respective functions. For example, a transmotor device, of particular utility in a microwave oven, drives a fan and, at same time, supplies a stepped down voltage to the oven controller and display.
Transmotors have been used for the application of traction and isolated charging/discharging of electric vehicles by adding magnetic material, e.g. iron, and electric conducting material, e.g. copper, to the motor. However, transmotors operate at grid frequency that is very low (50/60 Hz) compared to the operating frequency of EV motors (several kHz), therefore transmotors are bulkier and heavier than grid isolation transformers.
Currently, electric vehicles employ the on board AC electric charger of low power to limit the weight and size of its isolation transformer. Thus, limiting the onboard battery charging speed. This problem has been addressed by the implementation of transmotors without and with isolation, but these had and still have significant problems. Transmotors without isolation do not meet safety standards. Transmotors with isolation do not significantly increase the overall power density, therefore subject to the same limitations of charging speed for the same weight and volume of the AC electric charger on board the electric vehicle.
An Integrated Charging (IC) system integrates battery charging functionality with a vehicle's onboard electric drive system and power electronics. While charging using IC, the EV may be stationary and the terminals of the stationary motor may be connected to the utility grid to enable fast charging. The fundamental current flowing through the phases of a motor/generator would have a frequency of the grid. Rotating magnetic fields produced by the current in the air gap between motor stator and the locked rotor can cause problems, particularly in permanent magnet (PM) machines commonly used in the prior art. Such problems include: a) asymmetry in the phase voltage waveforms depending on the motor type and phase inductances; b) torque oscillation and hence, mechanical vibration; c) copper, core, magnet losses and temperature rise of varied levels depending on the PM motor type due to current, magnetic field and harmonics; and d) irreversible demagnetization of the magnets, if the motor is not optimally designed for both integrated charging and traction applications.
In accordance with one embodiment an Electric Vehicle comprises an Integrated Powertrain System and bidirectional coupling devices to the grid.
In accordance with another embodiment an Integrated Powertrain System comprises a MotorTransformer with a Matrix Converter and a Bidirectional Inverter, other power devices, and a controller.
In accordance with another embodiment a MotorTransformer device and method comprises multiple mechanical and electrical ports, multiple field coils, multiple magnetic circuits, and multiple electrical switches.
Other embodiments are envisioned and some are described in the following.
Thus several advantages of one or more aspects of the embodiments are as follows: to provide an EV 102 that transfers kinetic and electrical energy bidirectionally amongst onboard, electrical and/or mechanical devices, ESD 112 and off-board grids, to provide an Integrated Powertrain System that is on-board, that does not add weight and size to the EV 102, that can act as a motor for traction of the EV 102, that can act as a generator when the EV 102 motor is braking and the kinetic energy of the EV 102 flows back into the ESD 112 or to the AC Power Grid 210, that can act as an isolation transformer, that enables the EV 102 to be plugged directly into the AC Power Grid 210, that can charge and discharge the on-board ESD 110 extremely fast from and to the off-board AC Power Grid 210, that can be coupled to the off-board AC Power Grid 210 by electrical coupling conductive, capacitive, inductive, and radiative devices, that makes the off-board DC EVSE 302 unnecessary and thus overcomes the above-mentioned deficiencies in the art, reducing charging time and range anxiety, reducing the infrastructure complexity and cost, thus creating multiple standard interoperability, that can modulate intensity and direction of the energy flow between the ESD 110 and the grid 210, that enables the EV 102 to operate as energy storage for the grid 210 according to DR and DER signals from Power Utilities becoming a distributed energy resource (and not just grid load), that enables a new approach of using energy stored in EV 102, for example in case of emergency events and used for demand response and emergency situations for critical facilities (e.g. hospitals, fire stations, etc.) during blackouts. Other advantages of one or more aspects will be apparent from a consideration of the drawings and ensuing description.
FIG. Abstract shows a block diagram of the Integrated Powertrain System.
In accordance with one embodiment the Electric Vehicle 102 with the Integrated Powertrain System 402 (IPS) and coupling devices to the AC Power Grid.
Comparing
While the vehicle is braking, its kinetic energy can be transferred from the IPS 402 to its in-vehicle electric and/or mechanical ESD 112 and/or transferred to the external power grid 210 through EV WiFi Coupler 406. During vehicle acceleration, the electrical energy is transferred from the onboard ESD 112, and, or, from the electric grid 210 through EV WiFi Coupler 406, into the kinetic energy of the vehicle, and vice versa during braking.
The IPS 402 therefore provides both traction and energy regeneration functions, as well as fast charging and discharging to and from the electric power grid when parking or driving. The detailed description and operation of IPS 402 is in the following embodiments.
In accordance with another embodiment such IPS 402 comprising a MotorTransformer device MT 502, and other devices. Such IPS 402 bidirectionally transforms and transfers electric and kinetic energy among the grid, the ESD 112, and the electric vehicle. Thus, the IPS 402 provides for the propulsion of the electric vehicle and ultra fast charging and discharging of its ESD 112 from/to the off-board grids while stationary or driving.
Comparing
A variant of the IPS 402 with a high level of integration is illustrated in
The Controller 512 controls the MT 502, the BI 506, the MC 508, and HVC 510 switching signals.
CSS 504 can interconnect the Field Coils 503 in at least two hardware configurations. In a “Motor” configuration of the CSS 504, the MT 502 acts as a motor and, simultaneously, as an autotransformer for the “Driving” and “Driving and WiFi Vehicle to Grid” modes. In a “Transformer” configuration of the CSS 504, the MT 502 acts as an isolation transformer for the “Conductive Vehicle to Grid” mode.
In “Isolation Transformer” configuration, one, or more, groups of multi-phase coils, namely primary and secondary coil groups, operate the MT 502 as such isolation transformer with an alternating, non rotating magnetic field, so that the moving parts of the MT 502 are magnetically blocked (e.g. the motor rotor is blocked).
The BI 506 converts the DC power from/to the ESD 112 into AC power to/from the MT 502. The MC 508 converts the AC power from/to the MT 502 into AC power, or DC power, to/from the AC Power Grid 210.
Such IPS is coupled to the grids through the Connector 114 and/or the EV WiFi Coupler 406. The HV Contactors 510 (High Voltage Contactors, HVC) connects the MC 508 to the conductive coupler Connector 114 when EV 102 is parked to transfer energy directly from/to the AC Power Grid 210. The EV WiFi Coupler 406 can transfer energy by means of inductive, capacitive, or irradiation electromagnetic waves while the vehicle is parked or is driving.
A prototype of the IPS 402 with a low level of integration was constructed using a standard EV Motors 108.
The stator was removed from the motor and its housing. The stator windings were removed from the stator and rewound as illustrated in the simplified diagrams of
In this example, used to demonstrate the performance of the embodiment, the MT 502 is made up of six coils FC 503 and a triple-pole double-throw CSS 504. The FC 503 is made up of a brushless rotor mounting a number of permanent magnets and a stator with six poles mounting six coils; the MT 502 is connected to a 3-phase BI 506 and a 3-phase to 3-phase MC 508. Other configurations with multiple poles and coils (on stator and/or rotor) are envisioned and are part of the current embodiment, however, the basic 6-pole configuration of this example is used to illustrate the Integrated Powertrain System 402 concept and operation.
As is well known, the pole configuration of the EV Motors 108 can be designed in a number of different ways depending on the Torque/Speed required for the specific EV 102 as well as other parameters (form factor, cooling, inverter maximum operating frequency current, ESD 112 voltage, etc.). Depending on the number P of MT 502 phases, the BI 506 inverts from DC to P-phase and the MC 508 converts from P-phase to 3-phase, or from P-phase to single phase, (when connected to the 3-phase or single-phase grid), or from P-phase to DC when connected to an off board DC power source or load.
The switch positions of the CSS determine the operating Modes of MT 502. In this embodiment, the two positions of CSS 504 determine the interconnections of the two coil-sets, primary and secondary, of the MT 502. Thus, the primary and secondary magnetic circuits depend on interconnections of the coil-sets.
The CSS position of
In
Thus, in “Driving” mode the MT 502 is operating as a standard Motors 108. The ESD 112 energy is bidirectionally transferred through the 3-phase BI 506 to the MT 502. In this embodiment, the BI 506 converts the ESD 112 DC voltage to 3-phase AC voltage, or vice versa, during the driving, or braking.
The Controller 512 modulates the frequency and phases of voltages and currents applied to MT 502 in order to control the torque and the speed of the motor under the driver's control. The BI 506 can also operate with reversed energy flow, charging the ESD 112 during regenerative braking of the vehicle. When the MT 502 works as Motors 108, the EV Connector 114 is disconnected by the HV Contactor 510, and the MC 508 can operate with the AC-WiFi EVSE 404 while driving.
The neutral line M of the Primary FC 503 is connected to the midpoint of the fourth leg of BI 506, as shown in
In the configuration of
In
The IPS 402 is bidirectional, thus it can charge, or discharge, the ESD 112 from/to the AC Power Grid 210. The EV Connector 114 can be connected to an AC or DC source/load. When the EV Connector 114 is connected to an AC source/load (grid or microgrid) 210, the MC 508 generates 3-phase AC in phase with the off board AC power lines voltage with amplitude depending on direction and intensity of energy flow as defined by user needs and DR/DER signals. Similarly, when Connector 114 is connected to an off board DC source/load, the MC 508 generates a DC voltage with amplitude similar to that of the off board source, and Controller 512 controls current direction, and thus, energy flow direction and intensity.
In accordance with other embodiments such Integrated Powertrain System 402 is implemented with a high level of integration with a multi-port Matrix Converter 601 including two isolated circuits: a bidirectional inverter section and a matrix converter section, electrically isolated and controlled by the same Controller 512. Wherein the improvement comprises the matrix converter section of 601 functioning as matrix converter or as bidirectional inverter. When the matrix converter section of 601 functions as bidirectional inverter, this section works in parallel with the bidirectional inverter section of 601. The two sections can transfer power to/from MT 502, functioning as motor, from/to the DC battery of ESD 112, and at the same time.
In
In the embodiment illustrated in the example of
In
In
This embodiment is not limited to MT 502 devices having six field coils in the Wye connection. MT 502 can be implemented as a polyphase induction or as a permanent magnet machine, with multiple poles and coils on stator and/or rotor, with or without variable reluctance, and other electric motor schemes and technologies, in the Wye and/or Delta connections. However, these variants do not change the scope of the embodiment.
In the embodiment illustrated in
Based on the teachings in this disclosure, one skilled in the art can optimize the number of rotor poles and stator coils, the interconnections, and magnetic circuits in various modes, for the operating characteristics desired. For example, in
In accordance with another embodiment such MotorTransformer comprising one, or more, mechanical axes and two, or more, electrical ports, multiple field coils and configuration switches. Such MotorTransformer multiple electrical ports and mechanical axes transfer kinetic and electrical energy bidirectionally, amongst onboard electrical and mechanical energy storage devices, electric vehicle kinetics, and off-board grids.
In this embodiment an example of three phase MT 502 is shown in
In the “Transformer” configuration of
The circuit shown in
CSS 504 configuration of
CSS 504 position of
In accordance with another embodiment of such MotorTransformer comprising one or more mechanical axes, two or more electrical ports, multiple field coils, and configuration switches with at least two circuit configurations. One circuit configuration establishes a physical circuit and current paths through the field coils connected to the electrical ports generating a rotating magnetic field used to drive the mechanical moving parts. Another circuit configuration establishes a different physical circuit and current paths through the field coils generating an alternating, but not rotating, magnetic field coupled with two or more sets of electrically isolated field coils connected to the electrical ports of the MotorTransformer.
Such MotorTransformer multiple electrical and mechanical ports transfer kinetic and electrical energy bidirectionally, amongst onboard electrical and mechanical energy storage devices, electric vehicle kinetics, and off-board grids.
A peculiar characteristic of this embodiment of the MT 502 is that the rotation of its electromagnetic field can be controlled by the CSS 504 switches. In the first mode of CSS 504, the Field Coils 503 are connected in such a way that the electromagnetic field is rotating and the MT 502 works as a motor. This circuit configuration can serve for the “Driving” mode. In another circuit configuration of CSS 504, the Field Coils 503 are connected in such a way as to generate an alternating electromagnetic field, but not rotating, oriented along a stationary axis. In this circuit configuration the rotor of MT 502 does not rotate and the FC 503 forms a circuit such that MT 502 functions as a 3-phase isolation transformer between the two 3-phase ports (A, B, C) and (a, b, c). Therefore, in this circuit configuration of CSS 504, the MT 502 is usable for the “Conductive V2G” mode.
The circuit shown in
MT 502 comprises three sets of Field Coils 503 (FC-A, FC-B and FC-C) and three sets of Configuration Switch-Set 504 (CSS-A, CSS-B and CSS-C).
The three sets of FC 503 form three pairs of poles respectively oriented at 0, 120 and 240 degrees in the plane orthogonal to the rotating mechanical axis (rotor) of MT 502 as normally assembled in three-phase motors.
Each set of Field Coils 503 consists of four coils, each wound with the same number M of turns, therefore having the same inductance value L. The coils of each set are assembled on the same magnetic circuit in such a way as to be magnetically tightly coupled. Therefore the coupling coefficient (coupling factor) between the four coils of each set is equal to one. Consequently, the mutual induction coefficient between any pair of Field Coils 503 in each set equals the inductance L of a single coil. Thus, when the four coils of a set of Field Coil 503 are connected in parallel, by connecting the terminals having the same polarity, the inductor equivalent of the parallel set has inductance value L, identical to the inductance of a single coil.
Each set of CSS 504 is wired with one phase of the 3-phase system and has two possible positions for the formation of two different electromagnetic circuits defining the operation and functionality of MT 502.
In the first circuit configuration of the CSS 504 shown in
In the circuit configuration of the CSS 504 shown in
In this circuit configuration the four coils of each phase are connected in two isolated circuits which form the primary and secondary of the transformer. Each circuit is made up of two coils in series. Three sets of two isolated circuits form the electromagnetic circuits of the primary and secondary windings of a three-phase transformer.
Considering the circuits of the three phases it is possible to observe that the circuit of phase A is different from those of phases B and C, while the circuits of phases B and C are identical.
Considering the phase A circuit in the “Conductive V2G” mode of
Considering the circuits of phases B and C it can be observed that the four pairs of Field Coil 503 (B1, B2), (B3, B4), (C1, C2) and (C3, C4) are connected in parallel in pairs connecting together terminals with the same polarity. Since the coils of each pair are tightly coupled magnetically, the mutual inductance between coils of each pair is equal to L, the inductance value of a single coil. Thus, the inductor equivalent to each pair of coils has the same inductance value L of a single coil.
The positive terminals of the four pairs are connected to the phase lines B, C, b, c, while the negative terminals to the neutral lines M and N. In particular, the parallels (B1, B2) and (C1, C2) are connected between phases B and C and the neutral line M. Similarly, the pairs (B3, B4) and (C3, C4), associated with the second electrical port of MT 502, are connected between the two phases b and c and the neutral line N.
Phase A is applied to the series of the two inductors (A1, A2); the inductor equivalent of this series has a number of turns equal to twice those of a single coil, thus, an inductance value four times as great. Thus, the magnitude of the magnetic induction vector in the equivalent inductor is equal to half that of a single coil. Furthermore, due to the inverted polarity of this inductor series connection, the orientation of the magnetic induction vector in the magnetic poles of phase A is inverted.
As opposed to the circuit of phase A, in the circuits of phases B and C the inductors are connected in parallel. In particular the inductances B1 and B2 are connected in parallel through phase B and neutral line M. Similarly, for the inductances C1 and C2. Since the inductances in parallel are tightly magnetically coupled, the inductor equivalent to the parallel has an inductance value L equal to that of a single coil, therefore the number of turns of the equivalent inductor equals that of a single coil.
Therefore, the magnetic induction field vector in the poles A of MT 502 in the “Conductive V2G” mode of
The total magnetic induction in MT 502 is determined by the vector sum of the three magnetic induction field vectors generated by the three sets of poles associated with the three phases. The three vectors are parallel to the mechanical axes of the three sets of poles that are physically at 0, 120 and 240 degrees relative mechanical angles defined in a plane orthogonal to the axis of the MT 502 rotor. The amplitude and direction of the three magnetic induction field vectors vary over time according to the value of the three-phase voltages applied, which are out of phase in time with phase angles θ, 120 and 240 degrees.
In the circuit configuration of
In the “Conductive V2G” mode of
The circuits of
In this example the transformer has a one-to-one transformation ratio, therefore the three-phase voltages at the output from one electric port of MT 502 have the same values as those placed in input on the other port.
Other variants are possible. For example, by changing the number of phases, poles and coils, or by having a different number of turns for each coil, so as to allow different transformation ratios both in operation as a transformer for the “Conduction V2G” mode and for operation as an autotransformer for “Driving and WiFi V2G” mode adding additional taps in the coils to be connected to the (a, b, c) port.
Considering the generic case of MT made up of equally spaced sets of identical Field Coils (503) of N turns each, each one connected to a phase of a P-phase polyphase system, with P the number of phases, the MT magnetic field is rotating. This can be switched from rotating to alternating by changing the magnetic field of the Field Coils (503) connected to one phase (phase ALT), where ALT may be randomly selected amongst the P phases. Defining Bm the magnetic field amplitude of one single set of coils connected to one phase, the magnetic field Bac that applied to ALT generates the linearly polarized alternating magnetic field in MT may be calculated as the Bm value minus the product of P and half of Bm. Changing the magnetic field in ALT from Bm to Bac the magnetic field in MT switches from rotating to alternating. Vice versa, switching from Bac to Bm, the alternating field switches to rotating.
For example, with P equal to three, then Bac is minus half B, that means a field with half amplitude and reversed polarity. The Bm and Bac may be created in the ALT by two arrangements of Field Coils (503) circuits (or two electrically equivalent circuits of multiple field coils) having number of turns N and Nac and inverted polarity connection. The Nac may be calculated as the absolute value of the product of N by Bm divided Bac. Following the preceding example with P equal three, then Nac is half N.
Despite the immense variety of possible combinations of FC 503 and CSS 504 that can produce multitudes of different working MT 502 schemes, all of them generating one, or more, rotating field, useful for “Driving” mode, and one, or more, alternating field, useful for “Conductive V2G” mode, as described in the examples of this embodiment.
In accordance with other embodiments such MT 502 can be optimized to operate at different maximum power levels for the different operative modes.
Driving mode optimization defines the MT 502 layout configuration and sets its engineering parameters (number of poles, magnetic and electric circuits, wire and magnetic material type, rotor type, etc.) specific for each EV 102 design. Therefore, there is a V/Hz level that corresponds to the maximum MT 502 flux level for each design. An MT 502 Torque Corner Point (TCP) is defined by the optimization of MT 502 as a traction motor alone. However, TCP also defines the electric frequency for operating the MT 502 at its nominal maximum power. As the driving mode optimization does not take into account the grid frequency, the TCP's rotation speed is determined by the EV 102 dynamic and constraints on weight and size.
Thus, the overall optimization of IPS 402 is a tradeoff of engineering parameters depending on the maximum power required in the two operating modes “Driving” and “V2G”.
In case the MT 502 optimization as a motor leads to a TCP's frequency that is lower than the grid's frequency, the MT 502 can be connected directly to the grid without the need of the MC 508. In this case, the BI 506 operates at the grid's frequency, controlling its voltage and phase according to the grid's voltage and phase. In this condition, the maximum charging/discharging power and the maximum motor power of MT 502 are the same.
In other cases, the MT 502 optimization as motor could lead to a TCP's frequency higher than the grid's frequency and the MC 508 must be used to avoid magnetic saturation, otherwise, the max power of MT 508 operating as a transformer at power grid frequency could be much lower than the nominal max power of MT 508 operating as motor. The MT 508 optimization as a transformer for “V2G” modes could lead to an electric and magnetic circuit modification to decrease the TCP frequency, however, this would lead to an increase in weight, size, and cost. In order to maintain the same MT 502 size/weight/cost, and power of the two modes, the IPS 402 must include the MC 508.
In V2G mode the IPS generates 3-phase voltages to be delivered to the grid, and an important aspect to be considered is the harmonic content of the generated voltages. In driving mode the MT operates at full flux from start to beyond the TCP in order to obtain high current (torque) at low speed and reduced current/torque at higher speed. In this region the Controller 512 operates the BI 506 in PWM to control frequency, voltage, and current of the MT 502 polyphase voltages; therefore, in these conditions the sinusoidal voltages are produced with low distortion. However, at higher speed the inverter produces sinusoidal voltages with high harmonic content.
When the MT 502 is configured as an isolation transformer, the chain BI 506, MT 502, and MC 508, generates the 3-phase voltages at frequency, voltage and phase of the grid.
EV applications require high torque, high power, and low motor weight. Thus, the TCP frequency is higher than the grid frequency. This means that at grid frequency the available power of MT 502 in transformer configuration is lower than maximum power of the same MT 502 in motor configuration. Therefore, to operate the MT 502 as said isolation transformer at full power, without increasing its weight/size, the 3-phase bidirectional MC 508 must be used.
The MC 508 operates bidirectionally as a frequency converter between MT 502 and AC Power Grid 210, decoupling BI 506 and utility grid frequencies. Using the MC 508, the MT 502 can operate in the PWM area at maximum power regardless of the TCP frequency. This optimal operational area “MT-Transformer zone” is indicated in green in
Thus, the controller 512 coordinates the BI 506, MT 502 and MC 508, operating at TCP power in both directions for driving and V2G modes. With appropriate software the controller 512 operates the MC 508 as a frequency converter between the P-phase sinusoidal voltages of the BI 506 and the 3-phases, or single phase, and frequency of the grid, or DC microgrid. Using the frequency conversion feature of the MC 508, the BI 506 can operate MT at the TCP frequency (at or near an optimal frequency to track the grid's voltage phase) and the IPS 402 operates as a bidirectional AC isolated charger and discharger at MT 508 max nominal power. In V2G mode the MT 502 is configured as an isolation transformer. When energy flows from the battery to the grid, the MC 508 synthesizes the three-phase power at voltage, frequency, and phase of the grid, starting from the polyphase voltages, at the TCP frequency, supplied from the secondary of MT 502. The primary of MT 502 is powered by the polyphase voltages synthesized by BI 506 at TCP frequency from the DC battery energy.
In the same V2G mode, when the battery is to be charged and energy flows from the grid to the battery 514, the MC 508 synthesizes the polyphase system at TCP frequency from the three-phase grid. The polyphase is transformed by MT 502 and supplied to BI 506 which charges the battery.
The BI 506 and MC 508 can be implemented by means of matrices of IGBT (or other modern fast switching semiconductors) sets, while HV Contactors 510 and CSS 504 can be implemented with contactors or other equivalent devices.
Another embodiment of this invention is a MotorTransformer with variable reluctance. Controlling the reluctance of the MT 502 enables the possibility to tune the speed/frequency of the TCP.
The MT 502 with variable reluctance may be implemented with different shapes and profiles of rotor and/or stator, with or without permanent magnets. The reluctance may be set by controlling the relative angle between the magnetic field defined by the polyphase system angle and the rotor angle position acquired from an angular sensor. The relative angle may be controlled in a closed loop by voltage, current, and phase of the polyphase system supplying MT 502.
In motor configuration, the MT 502 reluctance is controlled according to the angular speed of the rotor to optimally extend the torque-speed range behind TCP.
In transformer configuration, the MT 502 reluctance may be controlled to tune the TCP angular speed at an exact multiple of the utility grid frequency.
The present invention is not limited to connecting the EV 102 to the 3-phase AC Power Grid, or microgrid, 210 by a cable. In other embodiments of the invention charging and discharging can be in AC single phase, or DC, and the connection between the EV 102 and the off board WiFi-AC EVSE 404 can be wireless. Depending on the number of phases, voltages, and available power and load from the grid, or microgrid, 210 the Controller 512 controls the switching sequences of the BI 506, CSS 504, MC 508, or the multi-port Matrix Converter 601. For example, when the embodiment of
Although the invention has been described in detail with respect to preferred embodiments thereof, it will be apparent, to those skilled in the art, that variations and modifications can be effected in these embodiments without departing from the spirit and scope of the invention. For example, the rotor magnets may be formed from either permanent magnets or electromagnets, the stator may have beveled edges for the stator windings, the directional rotation of rotor may be altered (e.g., by rotating the rotor ninety degrees), or the windings may be electrically commutated to allow for more windings. This invention is not restricted to rotary motors only, other motor configurations are possible, e.g. linear motors.
Further, multiple stators and rotors can be integrated in one single MT 502 and Flywheel 516 can be part of the ESD 112 without departing from the spirit and scope of the invention.
Accordingly, it can be seen that the EV of the various embodiments can ultra-fast charge and discharge its battery directly from/to the AC Power Grid and without the need of off-board, bulky and expensive, DC EVSE. Any EV equipped with the proposed technology is capable of recharging, and discharging, its battery from/to any energy source, without the need of dedicated infrastructure. This feature is enabled by the novel MotorTransformer device coupled with a Matrix Converter, utilizing the EV motor hardware as an isolation transformer when the vehicle is parked. With the current state of the art, electric motors are powered off and not used when the vehicle is parked and recharging. Thus, the reutilization of the motor hardware, magnetic and conductive material like iron and copper, for the functionality of fast charging and discharging creates additional economic value for vehicle owners and the society at large. Furthermore, the MotorTransformer has the additional advantages in that:
While the above description contains many specificities, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of various embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. For example, the MT 504 can be implemented with a number of different phases and coil turns even if the few examples show only specific cases selected to convey the concepts.
Thus the scope of this invention should be determined by the appended claims and their legal equivalents, and not solely by the examples given.
This PCT patent application claims the benefit of the U.S. Provisional Patent Application Ser. No. 63/286,982, filed 2021 Dec. 7 by the present inventor. The entire disclosure of the application being considered part of the disclosure of this application, and hereby incorporated by reference. The present invention relates to a bidirectional plug-in electric vehicle with an onboard device capable of working as a motor with regenerative braking for driving or as an isolated fast charger and discharger for energy transfer with an off-board power grid.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/052170 | 12/7/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63286982 | Dec 2021 | US |
