U.S. patent application number 09/770650 was filed with the patent office on 2001-10-04 for hybrid car power supply apparatus.
Invention is credited to Furukawa, Tadashi, Toya, Shoichi.
Application Number | 20010026142 09/770650 |
Document ID | / |
Family ID | 18547836 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010026142 |
Kind Code |
A1 |
Furukawa, Tadashi ; et
al. |
October 4, 2001 |
Hybrid car power supply apparatus
Abstract
The hybrid car power supply apparatus is provided with a battery
system having a driving battery to run an electric motor to drive
the vehicle, an inverter to drive the electric motor with the
driving battery, and an automotive battery. The battery system
houses a charging circuit to charge the driving battery with the
automotive battery. The charging circuit charges the driving
battery with the automotive battery when remaining driving battery
capacity becomes low. The charged driving battery runs the electric
motor to start the engine.
Inventors: |
Furukawa, Tadashi; (Hyogo,
JP) ; Toya, Shoichi; (Hyogo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18547836 |
Appl. No.: |
09/770650 |
Filed: |
January 29, 2001 |
Current U.S.
Class: |
320/103 ;
180/65.29; 320/130; 903/903 |
Current CPC
Class: |
B60W 10/08 20130101;
B60W 10/06 20130101; Y10S 903/903 20130101; B60W 20/10 20130101;
Y02T 10/7072 20130101; B60W 20/40 20130101; B60L 1/003 20130101;
B60W 20/00 20130101; B60L 2240/545 20130101; B60W 10/26 20130101;
Y02T 10/70 20130101; H02J 7/342 20200101; B60L 58/20 20190201; Y02T
10/62 20130101; B60W 2510/244 20130101; B60L 58/26 20190201; B60L
2210/40 20130101; B60W 20/13 20160101; B60L 58/18 20190201; Y02T
10/72 20130101; B60L 3/0046 20130101; B60L 50/16 20190201; B60L
2210/12 20130101 |
Class at
Publication: |
320/103 ;
320/130; 180/65.3 |
International
Class: |
H02J 007/00; B60L
011/18 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2000 |
JP |
021425/2000 |
Claims
What is claimed is:
1. A hybrid car power supply apparatus comprising: (a) an
automotive battery used as a power source for automobile electrical
equipment; (b) a battery system; and this battery system including
(1) a driving battery to run an electric motor for driving the
vehicle; (2) a battery control circuit to control charging and
discharging of the driving battery; (3) a charging circuit to
charge the driving battery with power from the automotive battery
when remaining battery capacity of the driving battery drops below
a specified value; and (c) an inverter to supply the electric motor
with output from the driving battery contained in the battery
system.
2. A hybrid car power supply apparatus as recited in claim 1
wherein the charging control circuit computes remaining battery
capacity of the driving battery by subtracting discharged capacity
from charged capacity.
3. A hybrid car power supply apparatus as recited in claim 1
wherein the charging control circuit determines remaining battery
capacity of the automotive battery by detecting automotive battery
voltage.
4. A hybrid car power supply apparatus as recited in claim 1
wherein the charging control circuit uses power supplied by the
driving battery as a power source by stepping down the voltage.
5. A hybrid car power supply apparatus as recited in claim 1
wherein the charging control circuit suspends supply of power from
the driving battery and supplies power from the automotive battery
when remaining battery capacity of the driving battery drops below
a specified value
6. A hybrid car power supply apparatus as recited in claim 1
wherein the battery control circuit of the battery system detects
remaining battery capacity of the driving battery and the
automotive battery, when remaining battery capacity of the driving
battery is below a specified value, and remaining battery capacity
of the automotive battery is greater than a specified value, the
automotive battery charges the driving battery.
7. A hybrid car power supply apparatus as recited in claim 1
wherein the charging circuit of the battery system contains a
circuit to charge the automotive battery with the driving
battery.
8. A hybrid car power supply apparatus as recited in claim 7
wherein the battery control circuit of the battery system detects
remaining battery capacity of the driving battery and the
automotive battery, when remaining battery capacity of the driving
battery is greater than a specified value, and remaining battery
capacity of the automotive battery is below a specified value, the
driving battery charges the automotive battery.
9. A hybrid car power supply apparatus as recited in claim 1
wherein when remaining battery capacity of the driving battery
drops below a specified value and the driving battery cannot turn
over the electric motor and start the hybrid car engine, the
battery control circuit uses the charging circuit to charge the
driving battery with the automotive battery.
10. A hybrid car power supply apparatus as recited in claim 9
wherein the capacity to which the automotive battery charges the
driving battery is a battery capacity allowing the driving battery
to run the electric motor and start the hybrid car engine.
11. A hybrid car power supply apparatus as recited in claim 1
wherein the charging circuit contains an inverter circuit to step
up the DC voltage of the automotive battery to a DC voltage capable
of charging the driving battery.
12. A hybrid car power supply apparatus as recited in claim 1
wherein the charging circuit begins charging the driving battery
with the automotive battery when the automobile ignition switch is
turned on.
13. A hybrid car power supply apparatus as recited in claim 12
wherein the charging circuit suspends charging when the driving
battery has been charged enough to start the engine with the
electric motor.
14. A hybrid car power supply apparatus as recited in claim 1
wherein the charging circuit charges the driving battery with the
automotive battery when the ignition switch is in the off position
and remaining battery capacity of the driving battery drops below a
specified value.
15. A hybrid car power supply apparatus as recited in claim 1
wherein the charging circuit contains a circuit to convert driving
battery output to the automotive battery charging voltage.
16. A hybrid car power supply apparatus as recited in claim 1
wherein the battery system is provided with a cooling fan for the
driving battery and this cooling fan is driven by the automotive
battery.
Description
[0001] This application is based on application No. 021425 filed in
Japan on Jan. 31, 2000, the content of which incorporated hereinto
by refernce.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a power supply apparatus to drive
a hybrid car.
[0003] A hybrid car runs by driving wheels with an engine and an
electric motor. A driving battery is installed as the power source
to drive the electric motor. This driving battery is charged by a
generator. The generator is driven by the engine or by regenerative
braking which uses inertial force to drive the generator when the
automobile is stopping. The amount of charge and discharge for the
driving battery is controlled by a battery control circuit, and the
remaining battery capacity is regulated within a specified range.
This is because over-charging and over-discharging cause rapid
degradation in the electrical characteristics of the driving
battery. The battery control circuit, which controls charging and
discharging of the driving battery is contained along with the
driving battery within the battery system.
[0004] In this power supply apparatus, over-discharge of the
driving battery will not occur as long as the automobile is
operated under normal conditions. However, if the vehicle is not
used for a long period, the driving battery may discharge and not
be able to drive the electric motor. Since the electric motor which
drives the wheels of a hybrid car serves a dual purpose as starter
motor for the engine, the engine cannot be started if the driving
battery is discharged.
[0005] This situation can be corrected by charging the driving
battery from an external source. However, since the driving battery
contains more than 1000 rechargeable batteries to attain a
substantially high voltage, it is necessary to charge the driving
battery with a special-purpose battery charger. Inability to drive
the vehicle due to discharge of the driving battery is an extremely
rare event. Therefore, it is impossible from a practical standpoint
to provide a special-purpose battery charger to correct this rare
event.
[0006] This dilemma can be solved by starting the engine with an
automotive electrical system battery. However, since the output
voltage of automotive electrical system batteries is almost without
exception 12V, either a special starter motor must be used to start
the engine, or an inverter is necessary to raise the voltage from
12V DC to the voltage of the electric driving motor. In providing a
starter motor, it is necessary to equip the engine with a starter
motor which is almost never used, and increase manufacturing cost.
In providing an inverter, it is necessary to make inverter output
extremely high, and this also has the drawback of excessively high
manufacturing cost.
[0007] The present invention was developed to resolve these types
of problems Thus it is a primary object of the present invention to
provide a hybrid car power supply apparatus which can charge the
driving battery with an automotive electrical system battery and a
low cost system, and which can start the engine when the driving
battery has been over-discharged.
[0008] The above and further objects and features of the invention
will more fully be apparent from the following detailed description
with accompanying drawings.
SUMMARY OF THE INVENTION
[0009] The hybrid car power supply apparatus of the present
invention is provided with a battery system, an inverter to supply
power output from a driving battery inside the battery system to
the electric motor, and an automotive battery used as power source
for standard automobile electrical equipment. The battery system is
provided with a driving battery for powering the vehicle driving
motor and a battery control circuit to control charging and
discharging of the driving battery. Further, the battery system
contains a charging circuit for charging the driving battery with
the automotive electrical system battery. When the remaining
battery capacity of the driving battery drops below a set value,
the charging circuit charges the driving battery with power from
the automotive electrical system battery. The charged driving
battery drives the electric motor to start the engine.
[0010] The hybrid car power supply apparatus described above has
the characteristic that a low cost system allows the vehicle to be
started when the driving battery has been over-discharged This is
because the battery system which houses the driving battery also
contains a charging circuit. This charging circuit charges the
driving battery via the automotive electrical system battery.
Namely, the charging circuit within the battery system charges the
driving battery with power from the automotive battery and the
charged driving battery operates the electric motor to start the
engine. This configuration has the characteristic that the charging
circuit can be made at low cost and with high reliability. This is
because the driving battery can be charged by the automotive
battery over a given length of time. Therefore, charging circuit
output current can be relatively small and still charge the driving
battery to operate the electric motor.
[0011] When remaining driving battery capacity becomes low, the
electric motor could alternatively be directly powered by the
automotive battery to start the engine without relying on the
system above. However, in this case, an extremely high output
special-purpose inverter is required to drive the electric motor
with the automotive battery. Since extremely high current must flow
at the instant the electric motor is turned over, this inverter
must be designed for high power output and becomes an expensive
item.
[0012] However, the inverter provided in the hybrid car for running
the electric motor via the driving battery can be used to avoid
driving the electric motor directly with the automotive battery.
This is possible by charging the driving battery with the
automotive battery and running the electric motor via the driving
battery. A charging circuit to charge the driving battery from the
automotive battery is required, but it is not necessary to
instantaneously charge the driving battery and the charging circuit
can be a low current, low cost device. Further, since there is no
high current flow over short periods, reliability is improved,
operating life extended, and maintenance simplified.
[0013] This system has the characteristic that simply by connecting
an automotive battery to the hybrid car, the driving battery can be
charged and the engine started by the electric motor even when
remaining battery capacity becomes low. This is because the battery
system is equipped with a charging circuit to charge the driving
battery via the automotive battery.
[0014] In this battery system, it is preferable to detect remaining
battery capacity of the driving battery and the automotive battery
via the battery control circuit. When remaining driving battery
capacity drops below a specified level, and remaining automotive
battery capacity is above a specified level, the automotive battery
charges the driving battery.
[0015] In addition, the battery system charging circuit can also
house a circuit to charge the automotive battery from the driving
battery. In this battery system, the battery control circuit
detects remaining battery capacity of the driving battery and
automotive battery. When remaining driving battery capacity is
above a specified level, and remaining automotive battery capacity
is below a specified level, the driving battery charges the
automotive battery.
[0016] Since the driving battery of this power supply apparatus can
charge the automotive battery, power from the driving battery taken
during forced discharge of the driving battery can be efficiently
used to charge the automotive battery. The driving battery is
actually many rechargeable batteries connected together. Therefore,
the driving battery has the property that battery capacity
differences between individual batteries become large through
repeated charge-discharge cycles, upsetting the balance of battery
capacities. If a driving battery having rechargeable batteries with
unbalanced capacities is charged and discharged, some battery may
over-charge or some battery may over-discharge. Further, to extend
driving battery life as much as possible, shallow charging and
discharging is repeatedly performed. As a result, depending on
battery type, effective usable battery capacity can decrease due to
the "memory effect". A driving battery in these conditions can be
forcibly discharged to recover from battery capacity imbalance and
"memory effect". At these times, if discharge power is used to
charge the automotive battery, driving battery discharge is not
wasted and the automotive battery can be efficiently charged.
[0017] Further, the battery system can be provided with a driving
battery cooling fan powered by the automotive battery to avoid
driving battery over-heating. Still further, the automotive battery
can also be used as back-up power for the battery control
circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a block diagram showing an embodiment of the
hybrid car power supply apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The hybrid car power supply apparatus of FIG. 1 is provided
with a battery system 1 equipped with a driving battery 2 to run an
electric motor 3 to drive the vehicle, an inverter 4 to supply
output from the driving battery 2 contained in the battery system 1
to the electric motor 3, and an automotive electrical system
battery 5 used as a power source for automobile electrical
equipment.
[0020] The battery system 1 is provided with a driving battery 2, a
battery control circuit 6 to charge and discharge the driving
battery 2 while avoiding over-charge and over-discharge, a charging
circuit 7 to charge the driving battery 2 via the automotive
electrical system battery 5, and a driving battery 2 cooling fan
10.
[0021] The driving battery 2 comprises many battery modules
connected in series. A battery module contains one or a plurality
of rechargeable batteries. The rechargeable batteries of a battery
module are nickel-cadmium batteries, nickel-hydrogen batteries, or
lithium-ion rechargeable batteries.
[0022] The battery control circuit 6 detects driving battery 2
voltage, current flow, and temperature. Battery temperature is
detected by temperature sensors. Temperature sensors are provided
either in close proximity to each battery module or in contact with
each battery module. Battery current flow is detected by amplifying
the voltage generated across a current detecting resistor (not
illustrated) in series with the battery. Since the
positive/negative polarity of the voltage generated across the
current detecting resistor is opposite for charging and
discharging, charging and discharging can be distinguished by the
positive/negative polarity of the voltage. For a driving battery 2
comprising a plurality of rechargeable batteries connected in
series, the voltage and temperature is detected independently for
each rechargeable battery. Otherwise, voltage and temperature is
detected for a battery module taken as one unit comprising a
plurality of rechargeable batteries connected in series.
[0023] The battery control circuit 6 subtracts discharged capacity
from charged capacity to compute remaining battery capacity of the
driving battery 2. Charged capacity is computed by taking the
product of charging efficiency and integrated charging current.
Discharged capacity can be computed from the integrated discharge
current. The battery control circuit 6 is controlled by the
automobile control unit 11. The battery control circuit 6 controls
charging and discharging to keep the remaining battery capacity of
the driving battery 2 within a specified range.
[0024] Further, the battery control circuit 6 detects the voltage
of the automotive electrical system battery 5 and determines the
remaining battery capacity of the automotive battery 5. The
remaining battery capacity of the automotive battery 5 is not
determined from the difference between charge and discharge
capacities, but rather is determined from the battery voltage. When
the voltage of the automotive battery 5 drops below a set voltage,
remaining battery capacity is judged to be smaller than a
prescribed value.
[0025] The battery control circuit 6 uses power supplied by the
driving battery 2 with voltage stepped down via an inverter (not
illustrated) as a power source. However, if the remaining battery
capacity of the driving battery 2 drops below a prescribed value,
power from the driving battery 2 is suspended and power from the
automotive battery 5 is supplied to the battery control circuit 6
as a back-up. In this circuit, the battery control circuit 6 can
operate on the automotive battery 5 even when remaining driving
battery capacity has become low.
[0026] The battery control circuit 6 also controls the charging
circuit 7 to charge the driving battery 2 with the automotive
battery 5 and to charge the automotive battery 5 with the driving
battery 2. When remaining battery capacity of the driving battery 2
drops below a prescribed value and the driving battery 2 can no
longer turn the electric motor 3 to start the engine 8, the battery
control circuit 6 uses the charging circuit 7 to charge the driving
battery 2 with the automotive battery 5. The capacity to which the
driving battery 2 is charged at this time is that necessary to run
the electric motor 3 and start the engine 8. Consequently, when the
remaining battery capacity of the driving battery 2 reaches a
capacity capable of starting the engine 8, charging of the driving
battery 2 is suspended. Further, when remaining automotive battery
5 capacity becomes low, and remaining driving battery 2 capacity is
greater than a prescribed value, the driving battery 2 charges the
automotive battery 5 until driving battery 2 voltage and remaining
battery capacity reach prescribed values.
[0027] The charging circuit 7 converts voltage to allow the
automotive battery 5 to charge the driving battery 2. Compared to
the automotive battery 5, the driving battery 2 is a higher voltage
battery. Consequently, the charging circuit 7 contains a voltage
step-up inverter to increase the DC voltage of the automotive
battery 5 to a DC voltage capable of charging the driving battery
2.
[0028] It is preferable for the charging circuit 7 to be capable of
quickly charging the driving battery 2. However, it is not
necessary to charge the driving battery 2 in the short period
typical of starting an engine with a starting motor in a standard
automobile, for example, in several seconds. Charging circuit
charging current must be increased to shorten charging time.
Further, if an automotive battery is discharged with large current
over a very short time interval, its actual output capacity
decreases. To efficiently charge the driving battery with
automotive battery output, it is advantageous to set the charging
circuit output current low.
[0029] Charging circuit 7 output current is set to an optimum value
considering the timing involved in charging the driving battery
with the automotive battery. In a power supply apparatus which
begins charging the driving battery with the automotive battery
when the automobile ignition switch is turned on, charging circuit
output current is made high. This is because the engine is started
after waiting for the driving battery to charge. In this type of
system, when the ignition switch is turned on and it is detected
that the remaining driving battery capacity is below the prescribed
value and the electric motor cannot be turned over, charging of the
driving battery from the automotive battery is started. When the
driving battery has been charged enough to start the engine with
the electric motor, charging is suspended, the electric motor is
operated with the driving battery, and the engine is started.
[0030] In this type of system, the electric motor is not operated
from the time the ignition switch is turned on until the driving
battery is charged. Since the driver is required to wait during
that period, charging circuit output current is increased to
shorten the charging time. However, the time to charge the driving
battery with the automotive battery is set considerably longer than
the time for a starter motor to start an engine. In this type of
system, when the ignition switch is off, even if remaining driving
battery capacity drops below the prescribed value, the automotive
battery does not charge the driving battery.
[0031] In contrast, in a system which charges the driving battery
with the automotive battery when remaining driving battery capacity
drops below the prescribed value even when the ignition switch is
off, charging circuit output current can be made extremely small.
Even if it takes some time to charge the driving battery, the
driver is not required to wait for the engine to start.
Consequently, this type of system has the characteristic that the
driving battery can be charged with a charging circuit having an
extremely small output current.
[0032] Further, the charging circuit 7 contains a circuit to
convert driving battery 2 output to a voltage for charging the
automotive battery 5. For example, when automotive electrical
equipment is used and remaining automotive battery 5 capacity
becomes low, the charging circuit 7 charges the automotive battery
5 with the driving battery 2. The circuit for charging the
automotive battery 5 with the driving battery 2 is an inverter
which steps down driving battery 2 voltage to the charging voltage
of the automotive battery 5. This system has the characteristic
that it can charge the automotive battery 5 much more efficiently
than an alternator installed in a standard automobile. This is
because the charging circuit 7 can charge the automotive battery 5
extremely efficiently compared to an alternator.
[0033] In a standard automobile, a dedicated alternator is turned
by a belt connected to the engine crankshaft to charge the
automotive battery. Since this system charges the automotive
battery with a high output alternator, charging efficiency is
extremely low. At low output levels, alternator efficiency drops
remarkably.
[0034] A cooling fan 10 cools the driving battery 2 with controlled
air flow when driving battery 2 temperature becomes abnormally
high. Consequently, the battery control circuit 6 controls
operation of the cooling fan 10. The cooling fan 10 is supplied
power from the automotive battery 5. This cooling fan 10 can use an
off-the-shelf motor operated by the automotive battery 5. However,
the cooling fan 10 can also be driven by the driving battery 2.
[0035] The inverter 4 converts DC power from the driving battery 2
to, for example, three-phase alternating current (AC) to drive the
electric motor 3 with the driving battery 2. In addition, the
inverter 4 converts power from the generator 9 to DC at the driving
battery charging voltage to charge the driving battery 2 with the
generator 9. Therefore, the inverter 4 is connected between the
driving battery 2 and the electric motor 3 and is also connected
between the generator 9 and the driving battery 2.
[0036] The automotive battery 5 is a 12V lead storage battery.
However, in the present invention, the automotive battery is not
limited to this type of battery and, for example, a battery with an
output voltage of 24V, or a rechargeable battery other than a lead
storage battery can be used. Regardless of what type of battery is
used, there is no requirement for the automotive battery 5 to
output very high power. Therefore, a battery with considerably
lower output voltage than the driving battery 2 is used.
[0037] As this invention may be embodied in several forms without
departing from the spirit of essential characteristics thereof, the
present embodiment is therefore illustrative and not restrictive,
since the scope of the invention is defined by the appended claims
rather than by the description preceding them, and all changes that
fall within the meets and bounds of the claims or equivalence of
such meets and bounds thereof are therefore intended to be embraced
by the claims.
* * * * *