BACKGROUND OF THE INVENTION
Embodiments of the invention relate generally to an isolation and feedback
system for an electrical energy storage system that, in one embodiment, is applicable to
electric drive systems including hybrid and electric vehicles.
Hybrid electric vehicles may combine an internal combustion engine and an
electric motor powered by an energy storage device, such as a traction battery, to propel
the vehicle. Such a combination may increase overall fuel efficiency by enabling the
combustion engine and the electric motor to each operate in respective ranges of
increased efficiency. Electric motors, for example, may be efficient at accelerating from
a standing start, while internal combustion engines (ICEs) may be efficient during
sustained periods of constant engine operation, such as in highway driving. Having an
electric motor to boost initial acceleration allows combustion engines in hybrid vehicles
to be smaller and more fuel efficient.
A purely electric vehicle (EV) uses stored electrical energy to power an
electric motor, which propels the vehicle and may also operate auxiliary drives. Purely
electric vehicles may use one or more sources of stored electrical energy. For example,
a first source of stored electrical energy may be used to provide longer-lasting energy
(such as a low-voltage battery) while a second source of stored electrical energy may be
used to provide higher-power energy for, for example, acceleration (such as a highvoltage
battery or an ultracapacitor).
Plug-in electric vehicles (PHEV), whether of the hybrid electric type or of the
purely electric type, are configiured to use electrical energy from an external source to
recharge the energy storage devices. Such vehicles may include on-road and off-road
vehicles, golf carts, neighborhood electric vehicles, forklifts, and utility trucks as
examples. These vehicles may use either off-board stationary battery chargers, onboard
battery chargers, or a combination of off-board stationary battery chargers and
on-board battery chargers to transfer electrical energy from a utility grid or renewable
energy source to the vehicle's on-board traction battery. Plug-in vehicles may include
circuitry and cormections to facilitate the recharging of the traction battery from the
utility grid or other external source, for example.
Thus, hybrids and EVs in general typically include at least one, and
oftentimes several, low or high voltage storage devices or other sources of power.
Known devices include but are not limited to a power battery that operates at 400 V or
greater, an energy battery operating optimally at 120 V, or an auxiliary power imit
(APU) that may include an internal combustion engine (ICE), a permanent magnet
generator (PMG), or a fiiel cell (FC). The APUs for use in an electric vehicle may have
their own unique operating voltage which may be at 400 V or greater as well. For
instance, at a desired operating condition an ICE may output a voltage that is different
from that of, for instance, a power battery or from other operating voltages of high
voltage devices in an EV. Or, a PMG may itself operate at an operating voltage that is
different from other devices within a system. Further, EVs often include high voltage
devices that vary from manufacturer to manufacturer and from one type to another. For
instance, one manufacturer may fabricate an ICE that outputs optimally 400 V while
another manufacturer may fabricate an ICE that outputs 380 V optimally. As such,
components and sub-systems may be designed into a hybrid or an EV having a wide
variety of operating voltages.
During the design cycle of a hybrid or an EV, it is often desirable to be able
to swap out different high voltage sub-systems in order to test the sub-system for
eventual inclusion in the final design. That is, APUs that include ICEs, PMGs, or FCs
may be tested and swapped out with other devices any number of times before settling
on the final unit(s) to be used. Similarly, different high voltage power batteries and
relatively low voltage energy batteries may likewise be tested during a lengthy and
rigorous design and testing stage. As is known in the art, it is desirable to enable simple
and quick connection and discoimection of such sub-systems during the design and test
stage (i.e., during the experimental stage) of a hybrid vehicle or EV. Oftentimes the
connection/disconnection fimctionality is provided by use of electro-mechanical
contactors that are all controlled by a main processing unit.
Electro-mechanical contactors are used in a variety of environments for
turning on and off a power source to a load electrically. The contactors include
movable contacts and fixed contacts. The movable contacts are connected to an
electromagnet and are controlled to selectively turn on or off power from the source to
the load. The contacts are typically maintained in an open position by way of a spring
and are caused to translate to a closed position when power to the electromagnet's coil
is applied.
The contactors for high voltage operation typically include specific design
parameters in order to provide the necessary operation capability. In systems where
high voltage energy storage devices are being used, contactors are often included for
safety purposes. It is often desirable for safety purposes to monitor voltages and
currents in order to provide quick and safe shutdown m the event of a voltage or current
excursion. In order to provide the safety features in early experimental hybrid and EV
designs, it is therefore often necessary to provide supporting hardware to operate the
contactors and monitor the currents and voltages particular to each voltage device.
Thus, one set of contactors and supporting hardware may have hardware and control
settings specific to a 400 V operation of a power battery, another set of contactors and
supporting hardware may have control settings specific to a 120 V operation of an
energy battery, and another set of contactors may be specific to a voltage of an auxiliary
power unit. Subsequently, when it is desired to continue testing of the design by
swapping out components, the 400 V power battery may be changed out for another
power battery having a different operating voltage, or perhaps for a different energy
storage device type altogether (such as, for instance, an ultracapacitor).
Because each device being tested may have unique performance capability
and/or operating voltage, when components are swapped the contactors or their control
settings may prove to be inadequate, as well as the additional hardware used to provide
current and voltage monitoring. As such, each swap of a hardware component can
result also in a need to swap out the contactors, to swap out the current and voltage
monitoring, and/or to alter the control parameters for contactor operation.
When preparing a test setup of a hybrid or an EV, it is often necessary to
include hardware coimections and feedback monitoring capability of the specific
devices being tested. That is, each device (storage, APU, etc..) typically includes its
own contactors and feedback system that is specific to the device being tested. Thus,
whenever re-arranging components, swapping out components, or adding new
components, additional contactors and feedback monitoring capability is also included
in order to provide the necessary fimctionality specific to each component. Because this
functionality may be so specific, a significant amount of additional work is necessary
when changing out components. That is, control schemes (overall current, rate of
ciurent change, contactor voltage, etc..) may change based on the type of component
being used. Because the control scheme for testing the unit is typically implemented in
a main control unit, changing out components can result in a need to make costly and
time-consuming changes to both hardware and software control schemes.
In fact, more generally, when testing experimental systems having multiple
energy storage and supply devices therein, such problems are also encoimtered as well.
That is, in general when experimental systems are being tested in order to determine
optimal system performance, and when such systems include potentially multiple
different types of energy storage and supply systems, often the experimental stage is
hindered because of the costly and time-consuming need to monitor and provide
feedback firom the sub-systems being tested. Such systems may include but are not
limited to trains, aircraft, ships, wind-power systems, solar photovoltaic systems, to
name but a few. Thus, the problem is not limited to hybrid vehicles or EVs, but
includes any system that may require complex experimental systems having multiple
energy storage and generating sub-systems associated therewith.
It would therefore be desirable to provide a contactor that is independently
controllable without a need to change out hardware and control schemes when swapping
out devices in a system having one or more devices that are selectively isolated.
BRIEF DESCRIPTION OF THE INVENTION
The present invention provides a system and method for enabling isolation of
electrical energy storage components and for providing feedback in a compact device.
In accordance with one aspect of the invention, a contactor unit includes an
input lead connectable to a first lead of an energy output device, an output lead
connectable to a first lead of a voltage bus, a contactor that connects and disconnects the
input lead fi-om the output lead, a driver configured to operate the contactor, a serial
data link connectable to a system controller that is external to the contactor unit, and an
integrated circuit (IC) positioned within the contactor imit and configured to output a
control command to the driver to open the contactor based on at least one of a current in
either the input lead or the output lead and a voltage differential across the contactor,
and output a contactor control status via the serial data link.
In accordance with another aspect of the invention, a method of operating an
isolation contactor comprising attaching an input lead of the isolation contactor to a first
lead of an energy output device and an output lead of the isolation contactor to a voltage
bus, measuring a current passing through one of the input lead and the output lead,
measuring a voltage across a switch that is positioned within a housing of the isolation
contactor and coupled to the input lead and the output lead, the switch configured to
disconnect the input lead fi"om the output lead, conveying signals that are representative
of the measured current and the measured voltage to an integrated circuit (IC) that is
positioned within the housing of the isolation contactor, controlling a driver based on
the signals conveyed to the IC, the driver configured to operate the switch, and
outputting a status of the switch to a computing device external to the housing via a
serial link.
In accordance with yet another aspect of the invention, a system for isolating
a first voltage device from a second voltage device, the system includes an isolating unit
having at least furst and second leads external thereto and connectable to leads of
respective energy devices, a switch positioned within a housing of the isolating unit and
coupled to the furst and second leads such that the first and second leads are selectively
engageable via the switch, a driving unit positioned within the housing and configured
to engage and disengage the switch, an integrated circuit (IC) positioned within the
housing and configured to output a control command to the driving unit to open the
switch based on at least one of a current in either the first lead or the second lead and a
voltage differential across the switch, and output a system control status via a serial data
link.
Various other features and advantages of the present invention will be made
apparent from the following detailed description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrate preferred embodiments presently contemplated for
carrying out the invention.
In the drawings:
FIG. 1 illustrates a two-pole isolation contactor with feedback control
according to an embodiment of the invention.
FIG. 2 illustrates two single-pole isolation contactors, each with feedback
control according to an embodiment of the invention.
FIG. 3 illustrates a single pole isolation contactor, similar to one of the singlepole
contactors of FIG. 2, and further illustrates internal components thereof according
to an embodiment of the invention.
FIG. 4 illustrates a two-pole isolation contactor, similar to that illustrated in
FIG. 1, and further illustrates internal components thereof according to an embodiment
of the invention.
FIG. 5 illustrates an electric vehicle as an exemplary system that can benefit
from embodiments of the invention.
DETAILED DESCRIPTION
Embodiments of the invention set forth herein relate to a contactor isolation
feedback method and apparatus. A core unit includes a contactor that isolates a voltage
supply from its circuit that based on internally provided thresholds and other operating
parameters specific to the voltage supply. The core unit receives power to operate the
contactors and other internal components, and the core unit outputs operating
information to a main system controller via a signal interface.
Referring to FIG. 1, isolation contactor 10 includes input leads 12 and output
leads 14. Input leads 12 are connectable to respective positive 16 and negative 18 leads
of an energy source 20 and output leads 14 are cormectable to leads of a voltage bus of,
for instance, an energy storage system. Energy soiu-ce 20 may include but is not limited
to a power battery that operates at 400 V or greater, an energy battery operating
optimally at 120 V, or an auxiliary power unit (APU) that may include an internal
combustion engine (ICE), a permanent magnet generator (PMG), or a fuel cell (FC).
Operating voltages or voltage differentials between input leads 12 in fact can be in any
range of voltage, from 10 V or below to 400 V or greater.
Isolation contactor 10 also includes a power supply line 22 to carry power for
operation of one or more contactors in isolation contactor 10, as will be further
discussed. Isolation contactor 10 also includes a signal or serial interface line 24 that
includes digital commimication to and from isolation contactor 10. That is, signal
interface line 24 may be used to provide feedback information regarding the operation
of contactor 10 to a computer or other control system that is external to isolation
contactor 10, as well as to provide control signals for operation therof, as will also be
discussed. However, as will also be illustrated, isolation contactor 10 is a compact
device and acts as a standalone unit that can be programmed with threshold values in
order to provide functionality to a system independent of what components are provided
to the system. That is, operating thresholds for currents and voltages may be preprogrammed
into isolation contactor 10 and specific to desired operating characteristics
specific to the device selected, such as energy source 20. Further, the thresholds may be
re-programmed, using signal interface 24 in one embodiment, in order to provide
flexibility of operation flexibility of system design.
In addition, FIG. 1 illustrates that both leads 16 and 18 of energy source 20
are coupled to isolation contactor 10 and, as will be described, isolation contactor 10
may be coupled to one of the leads such as positive lead 16, the other lead such as
negative lead 18, or both leads 16, 18. That is, in one embodiment of the invention,
one, the other, or both of leads 16, 18 may be isolated and controlled, having feedback
to each or both as well via signal interface line 24.
Referring now to FIG. 2, isolation control may be provided separately to
leads 16 and 18 of energy source 20. That is, a fu-st isolation contactor 26 may be
coupled to positive lead 16, and a second isolation contactor 28 may be coupled to
negative lead 18, in order to provide separately controllable isolation and feedback to
the separate leads 16, 18 of energy source 20. Further, each isolation contactor 26, 28
may include its own respective power supply line 30, 32, and each isolation contactor
26, 28 may include its own signal interface 34, 36. Thus, complete system flexibility
may be provided by enabling isolation and control of one pole or both poles 16, 18, by
providing isolation control by using a single device 10 coupled to both poles 16, 18
(FIG. 1), or by separate contactors 26, 28 (FIG2).
FIG. 3 illustrates internal components of an isolation contactor, according to
an embodiment of the invention. Isolation contactor 100 is connectable to a single pole,
such as positive pole 16 of energy source 20. However, it is understood that isolation
contactor 100 may equally be coupled instead to negative pole 18 of energy source 20
as well. Thus, isolation contactor 100 represents one of the isolation contactors 26, 28
as illustrated in FIG. 2. Isolation contactor 100 includes components contained therein
that enable isolation and feedback between leads 16 and 14. The components include a
current shunt 102 and a switch or contactor 104 that is activated or operated by a driver
106. Driver 106 is coupled to an integrated circuit 108 via a driver control line 110.
Integrated circuit 108, in one embodiment, is an application specific integrated circuit
(ASIC). Isolation contactor 100 includes an analog/digital (A/D) converter 112 that, as
10
commonly known in the art, converts incoming analog signals, such as a voltage, to a
digital representation thereof The core unit is thereby a data conversion and data
framing integrated circuit that, in one embodiment, is an ASIC that processes single bit
sigma-delta bit streams and frames the data into a proprietary or standard serial protocol
to transmit values upstream. Also, it receives commands to configure data processing
performance and includes simple commands to perform contactor actions.
Isolation contactor 100 includes a first lead 114 that, as illustrated, is
coupleable to a high voltage device, such as energy source 20, via positive lead 16.
First lead 114 includes current shunt 102 which, as is commonly known in the art,
enables a current in a lead to be measured by including a known resistance therein.
Because the resistance of current shunt 102 is known, by taking an accurate
measurement of the voltage drop to either side of current shunt 102 the current can be
determined with the well known Ohm's Law: Voltage (V) = Current (I) X Resistance
(R). The voltage drop across current shunt 102 is determined between a first voltage
measurement point 116 and a second voltage measurement point 118 by using a twisted
pair 120 that extracts the voltages and feeds them 122 to A/D converter 112.
A voltage differential across contactor 104 is also determined by extracting
voltage VI 124 and voltage V2 126 and feeding the voltages 128, as well, to A/D
converter 112. A/D converter 112 receives the incoming voltages for current shxmt 102
and contactor 104 via twisted pair 120, determines current in current shunt 102, and
sends current and voltage information as a digitized signal to integrated circuit 108 via
one or more data stream and control interface lines 130. Integrated circuit 108 receives
continuous current data regarding the current in first lead 114 and also receives voltage
data across contactor 104. As stated, integrated circuit 108 includes threshold
information related to at least the current in first lead 114 and also related to the voltage
drop across isolation contactor 104. That is, integrated circuit 108 is programmed with
desired operating thresholds for both current in first lead 114 and for the voltage drop
between VI point 116 and V2 point 118, and such information may be specific to the
type of energy device or specific to a manufacturer, as it pertains to energy source 20.
11
Accordingly, isolation contactor 100 is a compact device that combines the
function of isolation via contactors 104, and provides control of contactors 104 while
sensing current and voltages at different sensing points. In systems wherein high
voltage energy storage devices are being used, the contactor operation as well as the
monitored voltages and currents provide an opportunity for enhancing safe operation of
an overall system. That is, because isolation contactor 100 includes a separately
programmable device such as integrated circuit 108, different thresholds and operating
characteristics can be pre-programmed specific to a device such as energy source 20.
Thus, when energy source 20 is swapped out during the design and test phase of a larger
overall system, the functionality of isolation contactor 100 can be simply and safely
maintained by merely changing out operating parameters specific to the swapped out
device without the need for costly and time-consuming changes to hardware. That is,
high voltage isolation and voltage monitoring can be added to an electrical system at
any point in time and does not need to be fully designed in the early planning stage. In
other words, isolation contactor 100 provides an opportunity to defer a decision on what
energy system 20 will be included in a final design, providing the opportunity to test
and experiment during the design stage of system development, without having to make
early decisions regarding energy system 20 that are later much more difficult to change
or undo.
The number of electronic components is relatively small, which therefore
means that the components can all be included within a single housing of isolation
contactor 100. That is, isolation contactor 100 can be made small and compact and
have a limited number of input and output leads. For instance, referring still to FIG. 3,
isolation contactor 100 simply includes input lead 12, output lead 14, power leads 132
(for operating driver 106, A/D converter 112, and integrated circuit 108), and serial
interface leads 134. Isolation contactor 100 may therefore be simply 'dropped into' a
system that is or will be undergoing further design and experimental testing, while
deferring the decision on what energy system 20 (or type of system) will be tested
during the experimental phase. Isolation contactor 100 may be included in line with a
single pole of an energy system as illustrated in FIG. 3, or two isolation contactors 26,
12
28 may be included with separate poles 16, 18 of an energy system as illustrated in FIG.
2.
Or, as illustrated in FIG. 1, a single isolation contactor may be used to isolate
two poles of an energy device. FIG. 4 illustrates internal components of an isolation
contactor according to an embodiment of the invention. Isolation contactor 10, as
illustrated in FIG. 1, includes positive and negative leads 16, 18 of energy system 20
that are connectable to leads 12. Output leads 14 are connectable as positive and
negative leads to a DC bus, corresponding to positive lead 16 and negative lead 18.
Much like FIG. 3, isolation contactor 10 of FIG. 4 includes current shunt 102 and a
contactor 104 that is controllable via integrated circuit 108 and driver control line 110,
and via driver 106. However, in this embodiment, negative lead 18 is separately
controlled via a second contactor 136 and a second driver 138 and a second control line
140. In this embodiment, because each contactor 104, 136 is separately controllable,
each may have its own control parameters and thresholds of operation, enabling yet
additional control of the contactors for each lead 16, 18 of energy system 20. Thus, in
this embodiment, should current surges or voltage spikes occur in lead 16 is quickly and
detectable, and energy system 20 may be controlled, via either or both contactor 104,
136.
The embodiment illustrated in FIG. 4 illustrates one current shxmt 102.
However, the invention is not so limited, and current shunt 102 may be included also on
second lead 142. In yet another embodiment, a separate current shunt may be included
on each line 114 and 142. Thus, according to the invention, both leads 16, 18 may be
controlled in a single unit, such as isolation contactor 10 having two contactors 104, 136
therein. Or, both leads 16, 18 may be separately controllable in two separate units, each
having only one contactor therein, such as illustrated in FIG. 2.
In operation, the embodiments illustrated in FIGS. 1 - 4 provide system
isolation and feedback to a controller during an experimental stage of system
development. As one example, referring to FIG. 4, input leads 12 are connected to
poles 16 and 18 of energy soiu-ce 20, and output leads 14 are connected to respective
13
positive and negative leads of a DC bus (not shown). Power is provided to isolation
contactor 10 via power leads 132, and serial interface leads 134 are connected to a
system controller or computer (not shown). A/D converter 112 receives voltage
differential measurement data via twisted pair 120 and also receives voltage information
(VI, V2, V3, and V4) from each contactor 104, 136. A/D converter 112 converts the
received voltages to digital signals and outputs the signals to integrated circuit 108.
Integrated circuit 108 monitors the current and voltages and compares them to
thresholds that are established that are particular to the device(s) to which isolation
contactor 10 is connected, in this case energy source 20. When voltage or current
excursions are detected that exceed the respective threshold, integrated circuit 108
subsequently sends a command signal to open one or both isolation contactors 104, 136
and also sends out a control status or signal corresponding to the command signal. In
such fashion isolation contactor 10 monitors the leads, compares voltage therein to
threshold values, opens one or both contactors of the leads based on a comparison of the
voltages to the threshold values, and outputs a digital signal as feedback that is
indicative of the status of the leads (open or closed). In addition, integrated circuit 108
outputs, in embodiments of the invention, the measured voltages as well in order to
continuously monitor not only the status of the contactors but also the voltages and/or
current in the leads as well.
Embodiments of the isolation contactor disclosed herein may be used in any
system in which it is desirable to provide electrical isolation and feedback to one or
more poles or leads that is configured to carry electrical power. As stated, one such
application includes for use in a high voltage device such as a hybrid vehicle or an
electric vehicle. Such systems may also include but are not limited to trains, aircraft,
ships, wind-power systems, solar photovoltaic systems, to name but a few. Thus, the
problem is not limited to hybrid vehicles or EVs, but includes any system that may
require complex experimental systems having multiple energy storage and generating
sub-systems associated therewith. That is, when setting up an experimental system that
is going through rigorous design and testing, it may be desirable to include one or more
14
isolation contactors that can have control thresholds, for current and voltages, as
disclosed in embodiments herein.
Using embodiments of the invention, high voltage isolation and voltage
monitoring and feedback can be added to an electrical system at any point in time and
does not need to be fully considered in the early planning stage. That is, a system can
be buih in which various voltage supply units will be tested in order to validate a
design, qualify a manufacturer, or test a new device, as examples. Thus, although the
following illustration in FIG. 5 is specific to a 4-port energy management system for
charging various energy storage devices and energy sources of a hybrid vehicle, it is
contemplated that the embodiments disclosed herein may be used in any system in
which it is desirable to provide the flexibility of operation during a design and testing
phase, in order to provide feedback and control of one or more electrical leads.
Referring now to FIG. 5, according to the invention, a hybrid or electric
vehicle 200 includes a power battery 202 and one or more energy batteries 204 and a
source inverter 206 for inverting DC power from batteries 202, 204 in order to drive
motor 208. Motor 208 is coupled to a differential 210 via a gear unit 212 in order to
drive wheels 214. Energy batteries 204 may include relatively low voltage devices such
as conventional batteries, or ultracapacitors, as examples, operating at approximately
120 V, which provide high energy storage capability for, as one example, long-range
cruising of vehicle 200. Power battery 202 may include a relatively high voltage device
to provide high power capability, operating at approximately 400 V or greater, which
provide high power acceleration of vehicle 200, as another example. Vehicle 200 may
include an energy storage management system (ESMS) 216 for charging batteries 202,
204. ESMS 216 may include a number of buck-boost converters 218 that can buck, or
drop, a voltage when current is passing in one direction, and boost, or increase, a
voltage when current is passing in another direction. That is, buck-boost converters 218
may be operated in conjimction with one another in order to adjust incoming charging
voltages to match a desired operating voltage of a device to be charged, depending on
the design of the system. Thus, as one example, one of the storage systems 204 may be
15
charged at 120 V, and power battery 202 may be charged at 400 V. Thus, by selectively
bucking and boosting voltage from a charge or supply 220 (AC or DC source), energy
systems 204, 202 may be charged by properly directing cixrrent to flow through one or
more of buck-boost converters 218.
However, in a system such as hybrid or electric vehicle 200 of FIG. 5, it may
be desirable to develop an auxihary power unit (APU) 222 that is positioned on vehicle
10 that enables energy storage system re-charge as well as providing power for vehicle
operation. Vehicle 200 in this embodiment includes an APU 222 that may be
controUably engaged through a charging port 224. Thus, vehicle 200 may include an
APU that provides auxiliary power to electric motor 26 via ESMS 216. APU 222 may
include an internal combustion engine (ICE), a permanent magnet generator (PMG), or
a fuel cell (FC), as examples. That is, in conjunction with charger 220, during
development of hybrid or electric vehicle 200 it may be desirable to test one or multiple
types of APU in order to optimize the overall design. Thus, during the experimental
stage, multiple APU types may be swapped in and out. In order to avoid costly and
time-consuming swapping of hardware that is specific to each type of APU, according
to the invention an isolation contactor 226 may be included that enables both isolation
and feedback to a broader system control unit 228 that may be external to hybrid or
electric vehicle 200.
Further, although isolation unit 226 is shown to be positioned in parallel with
port P3 224, isolation units according to the embodiments disclosed herein may be
included in any or all of the other ports 230 of hybrid or electric vehicle 200, as well.
Further, as can be seen in FIG. 5, isolation contactor 226 includes isolation control of
each lead 232 of APU 222, similar to that disclosed in FIG. 1 and in FIG. 4, it is
contemplated that only one of leads 232 may be separately isolated using single line
isolation such as that disclosed in FIG. 3, or that both leads 232 may be separately
isolated using a single lead isolation system on each lead, as disclosed with respect to
FIG. 2.
16
A technical contribution for the disclosed method and apparatus is that it
provides for an isolation and feedback system for an electrical energy storage system.
Therefore, according to one embodiment of the present invention, a contactor
unit includes an input lead cormectable to a first lead of an energy output device, an
output lead connectable to a first lead of a voltage bus, a contactor that connects and
disconnects the input lead from the output lead, a driver configured to operate the
contactor, a serial data link coimectable to a system controller that is external to the
contactor unit, and an integrated circuit (IC) positioned within the contactor imit and
configured to output a confrol command to the driver to open the contactor based on at
least one of a current in either the input lead or the output lead and a voltage differential
across the contactor, and output a contactor control status via the serial data link.
According to another embodiment of the present invention, a method of
operating an isolation contactor comprising attaching an input lead of the isolation
contactor to a first lead of an energy output device and an output lead of the isolation
contactor to a voltage bus, measuring a current passing through one of the input lead
and the output lead, measuring a voltage across a switch that is positioned within a
housing of the isolation contactor and coupled to the input lead and the output lead, the
switch configured to disconnect the input lead from the output lead, conveying signals
that are representative of the measured current and the measured voltage to an
integrated circuit (IC) that is positioned within the housing of the isolation contactor,
controlling a driver based on the signals conveyed to the IC, the driver configured to
operate the switch, and outputting a status of the switch to a computing device external
to the housing via a serial link.
According to yet another embodiment of the present invention, a system for
isolating a first voltage device from a second voltage device, the system includes an
isolating unit having at least first and second leads external thereto and connectable to
leads of respective energy devices, a switch positioned within a housing of the isolating
unit and coupled to the first and second leads such that the first and second leads are
selectively engageable via the switch, a driving unit positioned within the housing and
17
configured to engage and disengage the switch, an integrated circuit (IC) positioned
within the housing and configured to output a control command to the driving imit to
open the switch based on at least one of a current in either the first lead or the second
lead and a voltage differential across the switch, and output a system control status via a
serial data link.
The present invention has been described in terms of the preferred
embodiment, and it is recognized that equivalents, alternatives, and modifications, aside
from those expressly stated, are possible and within the scope of the appending claims.
18

CLAIMS
What is claimed is:
1. A contactor unit comprising:
an input lead connectable to a first lead of an energy output device;
an output lead connectable to a first lead of a voltage bus;
a contactor that connects and disconnects the input lead from the output
lead;
a driver configured to operate the contactor;
^ a serial data link connectable to a system controller that is external to the
contactor unit; and
an integrated circuit (IC) positioned within the contactor unit and
configured to:
output a control command to the driver to open the contactor
based on at least one of:
a current in either the input lead or the output lead; and
a voltage differential across the contactor; and
output a contactor control status via the serial data link.
2. The contactor unit of claim 1 wherein the IC is configured to:
receive voltage readings measured across the contactor and calculate the
™ voltage differential based thereon;
compare the voltage differential to a voltage threshold value;
receive a current reading in either the input lead or the output lead;
compare the current reading to a current threshold value; and
output the control command to the driver based on at least one of:
the comparison of the voltage differential to the voltage
threshold; and
19
the comparison of the current reading to the current threshold
value.
3. The contactor unit of claim 2 wherein the IC is an application specific
integrated circuit (ASIC) that is programmable such that operating variables of the
contactor unit may be programmed, wherein the operating variables include the voltage
threshold value and the current threshold value.
4. The contractor imit of claim 3 wherein the ASIC is programmable via the
serial link from a computer that is external to the contactor unit.
5. The contactor unit of claim 2 comprising a current shunt positioned to
provide the current reading, the current shunt having a first voltage measurement point
to one side of the current shxmt and a second voltage measurement point to another side
of the current shunt, wherein the current reading is determined based on voltages
measured at the furst voltage measm-ement point and the second voltage measurement
point.
6. The contactor unit of claim 5 comprising an analog/digital (A/D)
converter configured to receive voltage values from a first voltage tap point and from a
second voltage tap point, wherein the first voltage tap point is positioned to measure a
voltage to one side of the contactor, and the second voltage tap point is positioned to
^ measure a voltage to the other side of the contactor, wherein the IC is configured to:
determine the current reading based on the voltages measured at the first
voltage measurement point and the second voltage measurement point; and
calculate the voltage differential across the contactor based on the
voltage measurements at the first and second voltage tap points.
7. The contactor unit of claim 1 comprising:
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a second input lead connectable to a second lead of the energy output
device;
a second output lead connectable to a second lead of the voltage bus;
a second contactor that connects and disconnects the second input lead
from the second output lead;
a second driver configured to operate the second contactor;
wherein the IC is fiirther configiured to:
output a second control command to the second driver to open the
second contactor based on at least one of:
a second current in either the second input lead or the
^H second output lead; and
a second voltage differential across the second contactor;
and
output a second contactor control status via the serial data link.
8. A method of operating an isolation contactor comprising:
attaching an input lead of the isolation contactor to a first lead of an
energy output device and an output lead of the isolation contactor to a voltage bus;
measiuing a current passing through one of the input lead and the output
lead;
measuring a voltage across a switch that is positioned within a housing of
the isolation contactor and coupled to the input lead and the output lead, the switch
^ ^ configured to disconnect the input lead from the output lead;
conveying signals that are representative of the measured current and the
measured voltage to an integrated circuit (IC) that is positioned within the housing of
the isolation contactor;
controlling a driver based on the signals conveyed to the IC, the driver
configured to operate the switch; and
outputting a status of the switch to a computing device external to the
housing via a serial link.
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9. The method of claim 8 comprising:
measuring the cxirrent and the voltage with an analog/digital (A/D)
converter that is positioned within the housing; and
outputting the conveyed signals as digital signals from the A/D
converter.
10. The method of claim 8 comprising:
comparing, in the IC, the current passing through the one of the input
lead and the output lead to a current threshold value;
^ ^ comparing, in the IC, the voltage across the switch to a voltage
differential threshold value; and
controlling the driver based on the comparison of the current to the
current threshold value, and based on the comparison of the voltage across the switch to
the differential threshold value.
11. The method of claim 10 wherein the integrated circuit is an application
specific integrated circuit (ASIC), the method further comprising programming the
ASIC such that operating variables of the contactor unit may be programmed, wherein
the operating variables include the voltage differential threshold value and the current
threshold value.
W 12. The method of claim 11 comprising programming the ASIC via the serial
link.
13. The method of claim 8 wherein measuring the current comprises
measuring the current across a current shunt that is in series with one of the input lead
and the output lead.
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14. A system for isolating a first voltage device from a second voltage
device, the system comprising:
an isolating imit having at least first and second leads external thereto
and connectable to leads of respective energy devices;
a switch positioned within a housing of the isolating unit and coupled to
the fu:st and second leads such that the first and second leads are selectively engageable
via the switch;
a driving unit positioned within the housing and configured to engage
and disengage the switch;
an integrated circuit (IC) positioned within the housing and configured
output a control command to the driving unit to open the switch
based on at least one of:
a current in either the first lead or the second lead; and
a voltage differential across the switch; and
output a system control status via a serial data link.
15. The system of claim 14 wherein the IC is configured to:
receive voltage readings measured in the first and second leads and
calculate the voltage differential based thereon;
compare the voltage differential to a voltage threshold value;
receive a current reading from either the first lead or the second lead;
compare the current reading to a current threshold value; and
output the control command to the driving unit based on at least one of:
the comparison of the voltage differential to the voltage threshold
value; and
the comparison of the current reading to the current threshold
value.
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16. The system of claim 15 wherein the IC is an application specific
integrated circuit (ASIC) that is programmable such that operating variables of the
contactor unit may be programmed, wherein the operating variables include the voltage
threshold value and the current threshold value.
17. The system of claim 16 wherein the ASIC is programmable via the serial
link from a computer that is external to the contactor unit.
18. The system of claim 15 comprising a current shunt positioned to provide
the current reading and coupled to one of the first lead or the second lead, the current
g^ shunt having a first voltage measurement point to one side of the current shunt and a
second voltage measurement point to another side of the current shunt, wherein the
current reading is determined based on voltages measured at the first voltage
measurement point and the second voltage measurement point.
19. The system of claim 18 comprising an analog/digital (A/D) converter
positioned within the housing and configured to receive voltage values fi-om a first
voltage tap point and fi-om a second voltage tap point, wherein the first voltage tap point
is positioned to measiu-e a voltage to one side of the switch, and the second voltage tap
point is positioned to measure a voltage to the other side of the switch, wherein the IC is
configured to:
determine the current reading based on the voltages measured at the first
^ ^ voltage measurement point and the second voltage measurement point; and
calculate the voltage differential across the switch based on the voltage
measurements at the first and second voltage tap points.
20. The system of claim 14 comprising:
third and fourth leads external to the isolating unit and connectable to
leads of respective energy devices;
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a second switch positioned within the housing of the isolating unit and
coupled to the third and fourth leads of the respective energy devices;
a second driving unit positioned within the housing and configured to
engage and disengage the second switch;
wherein the IC is further configured to:
output a second control command to the second driving unit to
open the second switch based on at least one of:
a second current in either the third or fourth leads; and
a second voltage differential across the second switch; and
output a second system control status via the serial data link.