Electricity: motive power systems – Induction motor systems – Primary circuit control
Reexamination Certificate
2002-04-18
2004-11-09
Martin, David (Department: 2837)
Electricity: motive power systems
Induction motor systems
Primary circuit control
C318S132000, C318S432000, C318S434000, C318S254100, C318S811000
Reexamination Certificate
active
06815927
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to vehicular air conditioning apparatus. More particularly, the invention relates to circuits for driving compressor motors of vehicular air conditioning apparatus.
2. Description of Related Art
Referring to
FIG. 1
, a known drive circuit
2
for driving a known compressor motor
100
, e.g., a brushless D.C. motor, of a vehicular air conditioning apparatus, such as the drive circuit described in Japanese Patent Publication No. HEI 8-98581, is depicted. An input side of drive circuit
2
is connected to a DC power supply
1
of the air conditioning apparatus, e.g., a battery, such as a forty-two (42) Volt vehicular battery, via a switching mechanism
9
of the air conditioning apparatus, e.g., a switch. Moreover, an output side of drive circuit
2
is connected to compressor motor
100
. Drive circuit
2
comprises a smoothing capacitor
30
and an inverter
3
. Inverter
3
comprises a plurality of switching elements
3
a
, e.g., a plurality of switches, and inverter
3
and capacitor
30
are each connected to a positive terminal of DC power supply
1
via switching mechanism
9
. The connection between inverter
3
and the positive terminal of DC power supply
1
via switching mechanism
9
forms a first positive electrical path
7
p
. Moreover, inverter
3
and capacitor
30
are each directly connected to a negative terminal of DC power supply
1
. The direct connection between inverter
3
and the negative terminal of DC power supply
1
forms a first negative electrical path
7
n
, and a main electrical path
7
comprises first positive electrical path
7
p
and first negative electrical path
7
n.
Drive circuit
2
also comprises a DC to DC converter
6
. A positive input of DC to DC converter
6
is connected to the positive terminal of DC power supply
1
via first positive electrical path
7
p
and switching mechanism
9
, and a negative input of DC to DC converter
6
is connected to the negative terminal of DC power supply
1
via first negative electrical path
7
n
. The connection between the positive input of DC to DC converter
6
and first positive electrical path
7
p
forms a second positive electrical path
8
p
. The connection between the negative input of DC to DC converter
6
and first negative electrical path
7
n
forms a second negative electrical path
8
n
, and a secondary electrical path
8
comprises second positive electrical path
8
p
and second negative electrical path
8
n
. Drive circuit
2
also comprises a switching element circuit
4
for selectively activating, i.e., placing in a closed position, and selectively deactivating, i.e., placing in an open position, each of the plurality of switching elements
3
a
of inverter
3
, and a feedback circuit
5
for controlling switching element circuit
4
.
In operation, an operator or a passenger of a vehicle, i.e., a user of the air conditioning apparatus, may turn on an air conditioning apparatus control circuit
200
, e.g., by moving a switch of air conditioning apparatus control circuit
200
from a first position to a second position, and air conditioning apparatus control circuit
200
may activate switching mechanism
9
. When switching mechanism
9
is activated, i.e., when switching mechanism is in a closed position, and for so long as at least one switching element
3
a
of inverter
3
also is activated, the amount of current flowing through first positive electrical path
7
p
and first negative electrical path
7
n
may be about one-hundred (100) amps. In contrast, when switching mechanism
9
is deactivated, or when switching mechanism
9
is activated and each of switching elements
3
a
are deactivated, the amount of current flowing through first positive electrical path
7
p
and first negative electrical path
7
n
may be about zero (0) amps. Moreover, when switching mechanism
9
is activated, regardless of whether each of switching elements
3
a
are activated or are deactivated, i.e., regardless of whether drive circuit
2
is activated or deactivated, the amount of current flowing through second positive electrical path
8
p
and second negative electrical path
8
n
may be about twenty-four (24) milli amps.
In operation, DC to DC converter
6
may convert voltage from DC power supply
1
to a lower voltage and may deliver the converted voltage to switching element circuit
4
and feedback circuit
5
. For example, when DC power supply
1
is a forty-two (42) Volt vehicular battery, DC to DC converter
6
may convert the forty-two (42) volts from DC power supply
1
into five (5) Volts, and also may deliver five (5) Volts to switching element circuit
4
and feedback circuit
5
. When switching element circuit
4
and feedback circuit
5
receive the converted voltage, switching element circuit
4
and feedback circuit
5
selectively activate or deactivate switching elements
3
a
of inverter
3
.
When at least one of switching elements
3
a
is activated, for so long as switching mechanism
9
is activated, current flows to compressor motor
100
, such that a drive shaft (not shown) of compressor motor
100
rotates. When the drive shaft of compressor motor
100
rotates, an electromotive force signal is generated between the terminals of compressor motor
100
. The electromotive force signal includes information related to the angular position of a rotor (not shown), and is delivered to feedback circuit
5
, such that feedback circuit
5
may process the electromotive force signal in order to determine the angular position of the rotor. When feedback circuit
5
determines the angular position of the rotor, if the angular position of the rotor is different than a predetermined angular position, switching element circuit
4
and feedback circuit
5
change the position of at least one of switching elements
3
a
in order to adjust the angular position of the rotor. When the user turns air conditioning apparatus control circuit
200
off, e.g., by moving the switch of air conditioning apparatus control circuit
200
from the second position to the first position, switching mechanism
9
may be deactivated.
When switching mechanism
9
is activated and switching elements
3
a
are deactivated, the amount of current flowing through first positive electrical path
7
p
and first negative electrical path
7
n
may be about zero (0) amps, and the amount of current flowing through second positive electrical path
8
p
and second negative electrical path
8
n
still may be about twenty-four (24) milli amps. As such, when switching mechanism
9
is activated, the amount of current flowing through second positive electrical path
8
p
and second negative electrical path
8
n
may be about twenty-four (24) milli amps regardless of whether switching elements
3
a
are activated or are deactivated, i.e., regardless of whether drive circuit
2
is activated or deactivated.
Moreover, because inverter
3
is connected to the positive terminal of DC power supply
1
via switching mechanism
9
, such the amount of current flowing through first positive electrical path
7
p
and first negative electrical path
7
n
may be about one-hundred (100) amps, in order to prevent damage to switching mechanism
9
during operation, switching mechanism
9
must be of a size sufficient to handle one-hundred (100) amps. Consequently, switching mechanism
9
may be a relay or a field effect transistor having an Ampere rating of at least one-hundred (100) amps. Further, because when switching mechanism
9
is activated the amount of current flowing through second positive electrical path
8
p
and second negative electrical path
8
n
may be about twenty-four (24) milli amps regardless of whether drive circuit
2
is activated or deactivated, DC power supply
1
may lose power in a short period of time.
SUMMARY OF THE INVENTION
Therefore, a need has arisen for air conditioning apparatus which overcome these and other short comings of the related art. A technical advantage of the present invention is that an air condi
Baker & Botts L.L.P.
Martin David
Sanden Corporation
Smith Tyrone
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