WO2021165653A1 - Système d'alimentation à deux bus - Google Patents

Système d'alimentation à deux bus Download PDF

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Publication number
WO2021165653A1
WO2021165653A1 PCT/GB2021/050323 GB2021050323W WO2021165653A1 WO 2021165653 A1 WO2021165653 A1 WO 2021165653A1 GB 2021050323 W GB2021050323 W GB 2021050323W WO 2021165653 A1 WO2021165653 A1 WO 2021165653A1
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WO
WIPO (PCT)
Prior art keywords
switches
sub
voltage
pack
bus
Prior art date
Application number
PCT/GB2021/050323
Other languages
English (en)
Inventor
Stephen Greetham
Original Assignee
Dyson Technology Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dyson Technology Limited filed Critical Dyson Technology Limited
Priority to CN202180015701.0A priority Critical patent/CN115152114A/zh
Publication of WO2021165653A1 publication Critical patent/WO2021165653A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/22—Balancing the charge of battery modules
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/08—Three-wire systems; Systems having more than three wires
    • H02J1/082—Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/18—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules
    • B60L58/21—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries of two or more battery modules having the same nominal voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
    • H02J7/0025—Sequential battery discharge in systems with a plurality of batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
    • H02J2310/40—The network being an on-board power network, i.e. within a vehicle
    • H02J2310/48—The network being an on-board power network, i.e. within a vehicle for electric vehicles [EV] or hybrid vehicles [HEV]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the invention relates to a power system having a dual bus, used by way of example in an electric vehicle.
  • the operating voltage range of a battery pack can be relatively wide.
  • the battery pack may have an operating voltage of around 900 V when fully charged and 600 V when fully discharged.
  • the battery pack may be required to power auxiliary systems at a much lower voltage.
  • the auxiliary power supply unit responsible for stepping down the voltage of the battery pack, is often complex, expensive and less efficient.
  • the present invention provides a power system comprising a first battery sub-pack, a second battery sub-pack, a primary bus, an auxiliary bus, and a plurality of switches, wherein the first battery sub-pack and the second battery sub-pack are connectable in series to the primary bus to provide a first voltage at the primary bus, and the switches are configurable to selectively connect one only of the first battery sub-pack and the second battery sub-pack to the auxiliary bus to provide a second voltage at the auxiliary bus.
  • the power system therefore comprises two voltage buses: a primary bus and an auxiliary bus.
  • the primary bus may be used to deliver high power to primary systems. In the case of an electric vehicle, this may include the traction drive units responsible for generating motive power.
  • the auxiliary bus may be used to deliver low power to auxiliary systems. Again, in the case of an electric vehicle, this may include a 12 V power supply unit.
  • the primary bus is held at a relatively high voltage, i.e. the sum of the voltages of the two sub-packs. This then has the advantage that a given power may be delivered to the primary systems at a lower current, which in turn reduces losses.
  • the auxiliary bus by contrast is held at a relatively low voltage, i.e. the voltage of just one of the sub-packs.
  • the width of the operating voltage range of the auxiliary bus is narrower than that of the primary bus.
  • the auxiliary systems which are typically required to operate over the full voltage range of the sub-packs, may be simpler, cheaper, smaller and/or lighter.
  • the power system is able to provide two different voltages on the buses simultaneously without any step-down power conversion.
  • the power system may comprise a controller for configuring the switches.
  • the switches may be configurable into a first configuration in which the first battery sub pack is connected to the auxiliary bus, and a second configuration in which the second battery sub-pack is connected to the auxiliary bus.
  • the controller then repeatedly switches or reconfigures the switches between the first configuration and the second configuration. This then has the advantage that the two sub-packs discharge and/or charge at a more even rate.
  • the controller may reconfigure the switches at a prescribed frequency or when a difference in the voltages of the battery sub-packs exceeds a threshold. As a result, a relatively good balance in the state-of-charge of the two sub-packs may be maintained during discharging and/or charging.
  • the prescribed frequency or the threshold may be defined in accordance with a voltage of one or both of the battery sub-packs. This then has the advantage that a lower switching frequency may be used whilst also ensuring that both sub-packs reach full discharge and/or full charge at the same time.
  • a lower switching frequency or a higher threshold may be used when the voltages of the sub-packs are relatively high during discharging and/or relatively low during charging
  • a higher switching frequency or a lower threshold may be used when the voltages of the sub-packs are relatively low during discharging and/or relatively high during charging.
  • the prescribed frequency or the threshold may be defined in accordance with a power drawn from the power system via the auxiliary bus. In particular, a higher frequency or a lower threshold may be used in response to a higher power draw. As a result, a good balance in the states of charge of the sub-packs may be achieved without the need to continually operate at a high switching frequency.
  • the switches comprise a first pair of switches and a second pair of switches connected in series across the primary bus
  • the auxiliary bus may comprise a positive rail connected to a first node located between the first pair of switches, and a negative rail connected to a second node located between the second pair of switches.
  • the present invention also provides an electric vehicle comprising the power system as described in any one of the preceding paragraphs.
  • the electric vehicle may comprise one or more traction drive units and one or more auxiliary systems.
  • the traction drive units are then connected to the primary bus, and the auxiliary systems are connected to the auxiliary bus.
  • the traction drive units may additionally be connected to the auxiliary bus, and the traction drive units may comprise one or more switches for selecting either the first voltage or the second voltage. As a result, the efficiency and thus the driving range of the vehicle may be increased.
  • the traction drive units may select the first voltage or the second voltage according to a desired or commanded speed and/or torque value. For a given voltage, there is typically a single point in the torque-speed characteristic of the traction drive unit where the efficiency is greatest. Consequently, by selecting a different voltage according to a desired speed and/or torque of the traction drive unit, the efficiency of the electric vehicle, and thus the driving range, may be improved.
  • Each traction drive unit may comprise a first pair of further switches and a second pair of further switches connected in series across the primary bus.
  • the auxiliary bus may then comprise a positive rail connected to first node located between the first pair of further switches and the second pair of switches, and a negative rail connected to a second node located between the first pair of further switches and the second pair of switches.
  • Figure l is a schematic diagram of an electric vehicle
  • Figure 2 shows a traction drive unit of the electric vehicle
  • Figure 3 is a circuit diagram of a battery pack of the electric vehicle
  • Figure 4 is a circuit diagram of an embodiment of the electric vehicle comprising a multilevel traction drive unit
  • Figure 5 is a circuit diagram of an alternative embodiment of the electric vehicle comprising an alternative multilevel traction drive unit
  • Figure 6 is a circuit diagram of a further embodiment of the electric vehicle comprising a combination of the embodiments of Figures 3 and 5.
  • the electric vehicle 1 of Figure 1 comprise a battery pack 10 connected to a pair of traction drive units 20.
  • Each traction drive unit 20 is coupled to a pair of wheels 50 via a pair of drive shafts 60.
  • the battery pack 10 supplies electrical power to the traction drive units 20, which in turn drive the wheels 50 of the vehicle 1.
  • each traction drive unit 20 comprises an electric motor 21, an inverter module 22, and a gearbox 23.
  • the electric motor 21 is a three-phase motor and comprises three phase windings 25 (see Figures 4 to 6).
  • the inverter module 22 is coupled to the windings 25 of the motor 21 and comprises a plurality of switches SW21- SW26 and a controller 26 for controlling the switches. In use, the inverter module 22 converts the DC voltage supplied by the battery pack 1 into an AC voltage which is applied to windings 25.
  • the gearbox 23 is coupled to the motor 21 and to the drive shafts 60. Torque generated by the motor 21 is then transferred to the wheels 50 via the gearbox 23 and drive shafts 60.
  • the battery pack 10 comprises a first sub-pack 11, a second sub-pack 12, a primary bus 14 having a pair of terminals 15,16, an auxiliary bus 17 having a pair of terminals 18,19, a first set of switches SW1-SW6, a second set of switches SW1 1-SW15, and a battery controller 13 for controlling the switches.
  • Each sub-pack 11,12 comprises a plurality of cells arranged into strings connected in series, with each string comprising a number of cells connected in parallel.
  • the two sub packs have an identical arrangement of cells.
  • each sub pack has a maximum voltage of 462 V (4.2V/cell) and a minimum voltage of 330 V (3.0V/cell).
  • the primary bus 14 is connected to and is used to supply electrical power to each of the traction drive units 20. More specifically, the primary bus 14 is connected to the inverter module 22 of each traction drive unit 20.
  • the auxiliary bus 17 is connected to and is used to supply electrical power to auxiliary systems (not shown) of the vehicle 1.
  • the auxiliary bus 17 may be connected to a 12 V power supply unit that steps down the voltage of the auxiliary bus 17 and outputs a 12 V supply.
  • the first set of switches SW1-SW6 are used to connect the two sub-packs 11,12 to the primary bus 14.
  • the first set of switches SW1-SW6 can be configured into a first configuration in which the two sub-packs 11,12 are connected in series across the primary bus 14 (i.e.
  • Switch SW6 forms part of a primary pre-charge circuit along with resistor R1.
  • the first set of switches SW1-SW6 When discharging the battery pack 11, the first set of switches SW1-SW6 are configured into the first configuration. As a consequence, the voltage of the primary bus 14 is between 924 V (fully charged sub-packs) and 660 V (fully discharged sub-packs). In order to charge the battery pack 10, a charge voltage is applied to the terminals 15,16 of the primary bus 14.
  • the battery pack 2 may be charged at a high voltage (e.g. 1000 V) or at a low voltage (e.g. 500 V).
  • the first set of switches SW1-SW6 When charged at a high voltage, the first set of switches SW1-SW6 are again configured into the first configuration. Conversely, when charged at a low voltage, the first set of switches SW1-SW6 are configured into the second configuration.
  • the second set of switches comprises a first pair of switches SW11,SW12 and a second pair of switches SW13,S14 connected in series across the primary bus 14.
  • a node 40 located between the two pairs of switches is connected to a node 43 located between the two sub-packs 11,12 when connected in series.
  • the positive terminal 18 of the auxiliary bus 17 is then connected via a positive rail to a node 41 located between the first pair of switches SW11,SW12, and the negative terminal 19 is connected via a negative rail to a node 42 located between the second pair of switches SW13,SW14.
  • the second set of switches further comprises switch SW15, which forms part of an auxiliary pre-charge circuit along with resistor R11.
  • the second set of switches SW 11-SW15 are used to connect one or both of the two sub packs 11,12 to the auxiliary bus 17.
  • the second set of switches are configurable into a first configuration in which the first sub-pack 11 only is connected across the auxiliary bus 17 (i.e. by closing SW11, SW13 and SW15), and a second configuration in which the second sub-pack 12 only is connected across the auxiliary bus 17 (i.e. by closing SW2, SW4 and SW5).
  • the sub-packs 11,12 are connected in parallel across the primary bus 14 (i.e.
  • the second set of switches are configurable into a third configuration in which the first sub-pack 11 and the second sub-pack 12 are connected in parallel across the auxiliary bus 17 (i.e. by closing SW11, SW14 and SW15). Accordingly, when the two sub-packs 11,12 are connected in series, the first and second configurations are used to connect one only of the sub-packs 11,12 to the auxiliary bus 17. And when the two sub-packs 11,12 are connected in parallel, the third configuration is used to connect both sub-packs 11,12 to the auxiliary bus 17.
  • the controller 13 configures the second set of switches SW11-SW15 into the first configuration or the second configuration such that only one of the sub-packs 11,12 is connected to the auxiliary bus 17 at any one time.
  • the voltage of the auxiliary bus 19 is between 462 V (fully charged sub-pack) and 330 V (fully discharged sub-pack).
  • the voltage of the auxiliary bus 19 is therefore half that of the primary bus 14.
  • the size or width of the operating voltage range of the auxiliary bus 17, which in this instance is 132 V (i.e. 462 V - 330 V) is also half of that of the primary bus 14.
  • the auxiliary systems may be rated for a lower maximum voltage and a narrower voltage range. As a result, the complexity, cost, size and/or mass of one or more of the auxiliary systems may be reduced.
  • the controller 13 repeatedly switches or reconfigures the second set of switches SW11- SW15 between the first configuration and the second configuration. As a result, the two sub-packs 11,12 discharge at a more even rate.
  • the controller 13 may switch between the first and second configuration at a prescribed frequency.
  • the prescribed frequency may be set such that, when the power demanded by the auxiliary systems is at a maximum, a relatively good balance in the state-of-charge of the two sub-packs 11,12 is nevertheless maintained. If the prescribed frequency is fixed at this value, a potential disadvantage arises when the power demanded by the auxiliary systems is relatively low. In this instance, switching between the two configurations would occur at a higher frequency then that required to maintain a good balance in the states of charge. Accordingly, the prescribed frequency may be defined according to the power drawn by the auxiliary systems. In particular, a higher prescribed frequency may be used in response to a higher power draw.
  • the controller 13 may instead switch between the two configurations whenever a difference in the voltages of the two sub-packs 11,12 exceeds a threshold. This then has the advantage that, irrespective of the power drawn by the auxiliary systems, switching between the two configurations occurs at the lowest possible frequency that ensures a good balance in the states of charge.
  • the controller 13 may define the prescribed frequency or the difference threshold according to the voltage of one or both of the sub-packs 11,12. More particularly, as the voltage(s) decreases, the controller 13 would use a higher prescribed frequency or a lower difference threshold.
  • the controller 13 When charging the battery pack 10 at a high voltage (i.e. when the sub-packs 11,12 are connected in series), the controller 13 again configures the second set of switches SW11- SW15 in the manner described above. That is to say that the controller 13 repeatedly switches or reconfigures the second set of switches SW11-SW15 between the first configuration and the second configuration. As a consequence, the voltage of the auxiliary bus 17 continues to be held at a voltage of between 426 V (fully charged sub packs) and 330 V (fully discharged sub-packs).
  • the controller 13 may use a prescribed frequency or a difference threshold, as described above, in order to control the switching.
  • the controller 13 would in this instance use a higher prescribed frequency or a lower difference threshold as the voltage(s) increases. This is in contrast to the situation described above for discharging, in which the controller 13 uses a higher prescribed frequency or a lower difference threshold as the voltage(s) decreases.
  • the controller 13 configures the second set of switches SW11- SW15 into the third configuration.
  • the auxiliary bus 17 is held at the same voltage as that of the primary bus 14.
  • the auxiliary bus 17 is therefore held at the charge voltage of 500 V.
  • the battery pack 10 comprises two voltage buses: a primary bus 14 for delivering high power to the primary systems of the vehicle 1, including the traction drive units 20; and an auxiliary bus 17 for delivering low power to the auxiliary systems of the vehicle 1.
  • the primary bus 14 is held at a relatively high voltage (e.g. between 660 V and 924 V). As a result, a given power may be delivered to the primary systems at a lower current. This then has the advantage that losses may be reduced, and electrical components of the primary systems, such as the switches SW21-SW26 of the inverter module 22 of the traction drive units 20, may be rated for lower current.
  • the auxiliary bus 17 by contrast is held at a relatively low voltage. Moreover, the width of the operating voltage range is narrower than that of the primary voltage bus.
  • the auxiliary systems which are typically required to operate over the full voltage range of the battery pack, may be simpler, cheaper, smaller and/or lighter.
  • the battery pack 10 is able to provide two different voltages on the buses 14,17 simultaneously without any step-down power conversion.
  • the battery pack 10 comprises an auxiliary pre-charge circuit SW15, Rl l.
  • the controller 13 were to switch or reconfigure the second set of switches SW11-SW14 between the first configuration and the second configuration at a sufficiently high frequency or if the controller 13 used a different threshold that was sufficiently small, the pre-charge circuit may be omitted. Pre-charge would then be required only on initial power up of the electric vehicle 1. However, this could be handled by momentarily operating the switches SW 11- SW14 in linear mode.
  • Each of the first set of switches SW1-SW6 is a contactor.
  • each of the second set of switches SW11-SW15 is a power device (i.e. a semiconductor switch).
  • Contactors have the advantage that they are simple, robust, cheap and easy to control. However, contactors have a relatively limited number of open-and-close cycles, and have a relatively slow response time. As such, contactors are unsuitable for the second set of switches SW11-SW15. Contactors also suffer from the problem that they may open inadvertently in response to vibration or a mechanical impulse, such as that which may arise when the vehicle 1 hits a pothole.
  • one or more of the switches may alternatively be a power device.
  • power devices are not susceptible to opening in response to vibration or a mechanical impulse, and they are generally more compact and lighter than contactors.
  • the auxiliary bus 17 and the second set of switches SW11-SW15 form part of the battery pack 10.
  • the auxiliary bus 17 and the second set of switches SW11-SW15 may be located outside of the battery pack 10 and may form a separate stage of the power system of the vehicle 1.
  • the battery pack 10 would then comprise a midpoint terminal 42, such as that shown in Figure 5, in order to provide a connection between the midpoint node 40 of the second set of switches SW 11 -SW 15 and the midpoint node of the two sub-packs 11,12.
  • the vehicle 1 may be said to comprise a power system having a first sub-pack 11, a second sub-pack 12, a primary bus 14, an auxiliary bus 15, and a plurality of switches SW11- SW14.
  • the first sub-pack 11 and the second sub-pack 12 are then connectable in series to the primary bus 14 to provide a first voltage at the primary bus 14.
  • the switches SW 11-SW14 are configurable to selectively connect one only of the first sub-pack 11 and the second sub-pack 12 to the auxiliary bus 17 to provide a second voltage at the auxiliary bus 17.
  • the auxiliary bus 17 may be used to supply power to one or more of the primary systems.
  • the auxiliary bus 17 may be used to supply power at a lower voltage to the traction drive units 20
  • the driving range of the vehicle 1 may be increased.
  • the higher voltage of the primary bus 14 e.g. 924 V
  • the lower voltage of the auxiliary bus 17 e.g. 462 V
  • the motor 21 when operating at low torque conditions (e.g. when coasting).
  • Figure 4 shows an alternative embodiment of the electric vehicle 1.
  • the inverter module
  • the inverter module 22 continues to comprise a pair of terminals 27,28 connected to the primary bus 14, a link capacitor C926 connected across the primary bus 14, a set of switches SW21-SW26 coupled to the windings 25 of the motor 21, and an inverter controller 26 for controlling the switches SW21-SW26.
  • the inverter module 22 additionally comprises a second set of terminals 30,31 connected to the auxiliary bus 17, a second link capacitor C462 connected across the auxiliary bus 17, and a second set of switches SW31-SW34 for selectively coupling the first set of switches SW21-SW26 to one of the primary bus 14 and the auxiliary bus 17.
  • the second set of switches SW31-SW34 are configurable into a first configuration (i.e.
  • SW31,SW34 are closed and SW32,SW33 are open) in which the first set of switches SW21-SW6 are connected to the primary bus 14, and a second configuration (i.e. SW32,SW33 are closed and SW31,SW34 are open), in which the first set of switches SW21-SW26 are connected to the auxiliary bus 17.
  • the controller 26 then configures the second set of switches SW3 1-SW34 into the first configuration or the second configuration as required.
  • the controller 26 may execute a vector control algorithm to generate a voltage vector, which is then used to determine the configuration of the second set of switches SW31-SW34.
  • the controller 26 may configure the second set of switches SW31-SW34 into the first configuration such that the voltage of the primary bus 14 is applied to the windings 25. Conversely, if the amplitude of the voltage vector is less than the threshold, the controller 26 may configure the second set of switches SW31-SW34 into the second configuration such that the voltage of the auxiliary bus 17 is applied to the windings 25.
  • a traction drive unit 20 having a dual bus may be achieved without the need for the auxiliary bus 17, as will now be described with reference to Figure 5.
  • FIG. 5 illustrates a further embodiment of the electric vehicle 1.
  • the battery pack 10 no longer comprises an auxiliary bus 17 or the second set of switches SW11-SW15.
  • the battery pack 10 comprises an additional terminal 44 and a further switch SW7.
  • the additional terminal 42 is connected via switch SW7 to the node 41 located between the two sub-packs 11,12 when connected in series.
  • this additional terminal 42 will be referred to as the midpoint terminal, since it is connected to the midpoint between the two sub-packs 11,12.
  • Switch SW7 forms part of the first set of switches SW1-SW6 and is provided only to ensure that the midpoint terminal 42 can by isolated from the first sub-pack 11 when the battery pack 10 is powered off.
  • the inverter module 22 again comprise a pair of terminals 27,28 connected to the primary bus 14, a first set of switches SW21-SW26 coupled to the windings 25 of the motor 21, and an inverter controller 26 for controlling the switches SW21-SW26.
  • the inverter module 22 additionally comprises a single mid-point terminal 32, a second set of switches SW31-SW34, and a pair of link capacitors C462-1, C462-2.
  • the second set of switches comprises a first pair of switches SW31,SW32 and a second pair of switches SW33,S34 connected in series across the primary bus 14.
  • a node 33 located between the two pairs of switches is connected to the midpoint terminal 32 via a midpoint rail.
  • the first set of switches SW21-SW26 may be said to be connected between a positive or upper rail and a negative or lower rail.
  • the positive rail is then connected to a node 34 located between the first pair of switches SW31,SW32, and the negative rail is connected to a node 35 located between the second pair of switches SW33,SW34.
  • the two link capacitors C462-1, C462-2 are connected in series across the primary bus 14. Moreover, a first link capacitor C462-1 is connected in parallel with the first pair of switches SW31,SW32 between the positive rail of the primary bus 14 and the midpoint rail, and the second link capacitor C462-2 is connected in parallel with the second pair of switches SW33,SW34 between the midpoint rail and the negative rail of the primary bus 14.
  • the second set of switches SW31-SW34 of the inverter module 22 are similar to the second set of switches SW11-SW14 of the battery pack 10 of Figures 3 and 4, both in terms of their arrangement and their operation, as will now be described.
  • the second set of switches SW31-SW34 are used to connect one or both of the two sub packs 11,12 to the first set of switches SW21-SW26. Let us assume that the two sub packs 11,12 are connected in series across the primary bus 14 (i.e. SW1, SW3, SW5 are closed), and that the midpoint terminal 42 is connected to the midpoint between the two sub-packs (i.e. SW7 is closed).
  • the second set of switches SW31-SW34 are then configurable into a first configuration in which the first sub-pack 11 only is connected to the first set of switches SW21-SW26 (i.e. by closing SW31 and SW33), a second configuration in which the second sub-pack 12 only is connected to the first set of switches SW21-SW26 (i.e.
  • the inverter controller 26 configures the second set of switches SW31-SW34 such that either a first voltage or a second voltage is supplied to the first set of switches SW21- SW26.
  • a first voltage or a second voltage is supplied to the first set of switches SW21- SW26.
  • the first voltage or the second voltage is applied to the windings 25 of the motor 21 by the first set of switches SW21-SW26.
  • the first voltage corresponds to the combined or series voltage of the two sub-packs 11,12
  • the second voltage corresponds to the voltage of just one of the sub-packs 11,12.
  • the second voltage is there half that of the first voltage.
  • the first voltage is between 924 V (fully charged sub-packs) and 660 V (fully discharged sub-packs)
  • the second voltage is between 462 V (fully charged sub-pack) and 330 V (fully discharged sub pack).
  • the first sub-pack 11 would discharge quicker than the second sub-pack 12. As a result, the first sub-pack 11 would reach a state of full discharge before the second sub-pack 12, which is undesirable.
  • the inverter controller 26 therefore repeatedly switches or reconfigures the second set of switches SW31-SW34 between the first configuration and the second configuration. As a result, the two sub-packs 11,12 discharge at a more even rate.
  • the inverter controller 26 may switch between the first and second configuration at a prescribed frequency.
  • the prescribed frequency may be fixed or it may be defined according to the power drawn by the motor 21, a desired speed/or torque of the motor 21, or by some other parameter.
  • the controller 26 may execute a vector control algorithm to generate a voltage vector. The voltage vector may then be used to determine whether the first voltage or the second voltage should be applied to the windings 25. Additionally, the voltage vector may be used to define the frequency at which the second set of switches SW31-SW34 are switched between the first configuration and the second configuration.
  • the controller 26 may instead switch between the two configurations whenever a difference in the voltages of the two sub-packs 11,12 exceeds a threshold.
  • the controller 26 may define the prescribed frequency or the difference threshold according to the voltage of one or both of the sub-packs 11,12. In particular, as the voltage(s) of the sub-pack(s) decreases, the controller 26 may use a higher prescribed frequency or a lower difference threshold.
  • a cost-effective multilevel inverter module 22 is provided.
  • Multilevel inverters are known, but they typically comprises a large number of switches and the required control is relatively complex.
  • a multilevel inverter can be achieved with the addition of just four switches, namely SW31-SW34.
  • control of the switches SW31-SW34 is relatively straightforward.
  • the switches must be carefully controlled and/or additional diodes must be provided in order to provide the necessary paths back to the link capacitors.
  • the battery pack 10 comprises sub-packs 11,12 having the same number and configuration of cells.
  • the two sub-packs 11,12 have the same nominal voltage and capacity.
  • the battery pack 10 may comprise sub-packs 11,12 having different nominal voltages.
  • the inverter module 22 would then be capable of supplying the electric motor 21 with three voltage levels rather than two.
  • the inverter module 22 would supply the voltage of the first sub-pack 11.
  • the inverter module 22 would supply the voltage of the second sub-pack 12.
  • the inverter module 22 would supply the sum of the voltages of the first and second sub-packs 11,12. It will be appreciated that when operating in this mode, the inverter controller 26 would not repeatedly switch or reconfigure the switches SW31-SW34 between the first configuration and the second configuration.
  • a multilevel inverter module 22 is achieved without the need for the auxiliary bus 14 of the battery pack 10 of Figure 3.
  • the two embodiments of Figures 3 and 5 are not mutually exclusive, and the vehicle 1 may comprise the combination of the two embodiments, as illustrated in Figure 6.
  • the embodiment of Figure 6 has at least two advantages over that of Figure 4.
  • First the total capacitance requirement of the inverter module 22 is smaller, and thus the size and cost of the capacitors are reduced.
  • the second set of switches SW11-SW15 of the battery pack 10 are not required to carry the relatively high currents drawn by the traction drive unit 20. As a result, cheaper switches rated for lower current may be used for the second set of switches SW 11 -SW 15 of the battery pack 10.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

Système d'alimentation comprenant un premier sous-bloc de batterie, un second sous-bloc de batterie, un bus primaire, un bus auxiliaire et une pluralité de commutateurs. Le premier sous-bloc de batterie et le second sous-bloc de batterie peuvent être connectés en série au bus primaire pour fournir une première tension au niveau du bus primaire, et les commutateurs sont configurables pour connecter sélectivement et uniquement un élément parmi le premier sous-bloc de batterie et le second sous-bloc de batterie au bus auxiliaire pour fournir une seconde tension au niveau du bus auxiliaire.
PCT/GB2021/050323 2020-02-21 2021-02-11 Système d'alimentation à deux bus WO2021165653A1 (fr)

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CN202180015701.0A CN115152114A (zh) 2020-02-21 2021-02-11 具有双总线的电力系统

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GB2002439.4A GB2592245A (en) 2020-02-21 2020-02-21 Power system with dual bus
GB2002439.4 2020-02-21

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US11655024B1 (en) * 2022-05-25 2023-05-23 Kitty Hawk Corporation Battery systems with power optimized energy source and energy storage optimized source

Citations (2)

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Publication number Priority date Publication date Assignee Title
US20160318411A1 (en) * 2015-04-30 2016-11-03 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Battery system with battery control
DE102018207263A1 (de) * 2018-05-09 2019-11-14 Ford Global Technologies, Llc Elektrisches Bordsystem eines Kraftfahrzeugs mit zwei mit unterschiedlichen Spannungen betriebenen Teilnetzen

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Publication number Priority date Publication date Assignee Title
JP2003095039A (ja) * 2001-09-25 2003-04-03 Fuji Heavy Ind Ltd 自動車用電源システム
JP2014011917A (ja) * 2012-07-02 2014-01-20 Mitsubishi Heavy Ind Ltd 充電率均等化装置及び電池システム
WO2015105923A1 (fr) * 2014-01-07 2015-07-16 Utah State University Commande de batterie
DE102014006772A1 (de) * 2014-05-08 2015-11-12 Daimler Ag Batteriesystem für ein Kraftfahrzeug mit zwei Spannungskreisen
US10214111B2 (en) * 2016-08-16 2019-02-26 Ford Global Technologies, Llc Electrified vehicle power conversion for low voltage bus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160318411A1 (en) * 2015-04-30 2016-11-03 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Battery system with battery control
DE102018207263A1 (de) * 2018-05-09 2019-11-14 Ford Global Technologies, Llc Elektrisches Bordsystem eines Kraftfahrzeugs mit zwei mit unterschiedlichen Spannungen betriebenen Teilnetzen

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CN115152114A (zh) 2022-10-04
GB202002439D0 (en) 2020-04-08
GB2592245A (en) 2021-08-25

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