Electricity: motive power systems – Battery-fed motor systems
Reexamination Certificate
2000-03-06
2002-11-05
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Battery-fed motor systems
C318S245000, C318S254100, C318S132000, C320S118000, C320S118000, C320S118000, C322S046000, C322S028000, C322S090000, C322S094000, C180S065100, C180S065230, C307S064000, C307S066000
Reexamination Certificate
active
06476571
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multiple power source system that includes both a high tension electric system driven by high tension electric energy and a low tension electric system driven by lower tension electric energy. More specifically the invention pertains to a multiple power source system that compensates for an insufficiency of electric energy in a certain electric system, as well as to an apparatus and a vehicle with the multiple power source system mounted thereon.
2. Description of the Related Art
Electric energy is usable in a wide range of technical fields including thermal, optical, power-driven, and data communication, and is used as the energy power source of various industries. Each apparatus utilizing the electric energy has predetermined ratings and ensures the normal operations under predetermined rated voltage and power. A typical industrial apparatus includes a plurality of devices having different rated voltages and a plurality of power sources having different line voltages for these devices. By way of example, an electric vehicle has a high voltage motor used for driving the vehicle and a low tension electric system used for, for example, a computer, which controls the output torque of the motor, lamps, controllers, and auxiliary machines.
With the advance of semiconductor technology, the use of semiconductor elements, such as power transistors and thyristors, desirably simplifies the structure of a power converter unit like an inverter, a converter, or a chopper circuit. These power converters are controlled with a high accuracy by the computer. The recently developed industrial apparatus includes a charge-discharge unit that enables charge and discharge of electric energy, for example, a battery or a power capacitor, as at least one of the plural power sources. For the purpose of energy saving, non-required mechanical energy is regenerated as electric energy and charged into the charge-discharge unit. An auxiliary power source is provided as a back-up power source in the case of a failure of the main power source.
In the apparatus having the plurality of power sources, contacts and diodes are generally required to connect the plurality of power sources with the devices. This makes the structure of the apparatus rather complicated. For example, a device with a contact, such as a relay, is required to selectively connect a power source of interest with an actuator. A diode having the rectifying function may be used to prevent the electric current from flowing from the high voltage power source to the low voltage power source. The structure of switching the relay or another contact may be replaced with a structure having duplicate motor windings, where each coil is independently connected to the power source. These structures, however, make the apparatus undesirably bulky.
The apparatus having the plurality of power sources may not work properly when either one of the high voltage power source and the low voltage power source has an insufficiency of electric power. In order to solve this problem, a voltage step-up and step-down circuit is provided to enable the electric energy to be supplied to the electric system having an insufficiency of electric energy. This structure enables one electric system having sufficient electric energy to give the excess electric energy to another electric system having insufficient electric energy This effectively reduces the possible malfunction of the industrial apparatus.
In this case, however, a separate circuit is required to step up and down the voltage between the plurality of power sources. This undesirably increases the required number of electric parts and makes the power source circuit rather complicated, thereby increasing the manufacturing cost and lowering the reliability. The voltage step-up and step-down circuit uses a reactor for converting the electric energy to magnetic energy and reconverting the magnetic energy to electric energy. A large reactor is required to accumulate a sufficiently large magnetic energy. Even the step-up and step-down circuit, which is provided only for the emergency purpose to compensate for the insufficient electric power in a power source system, thus occupies a relatively large space and increases the total weight of the industrial apparatus.
SUMMARY OF THE INVENTION
The object of the present invention is thus to simplify the structure of a multiple power source system having a plurality of power sources for driving a three-phase motor, and also to simplify the structure of an apparatus, for example, a hybrid vehicle, with the multiple power source system mounted thereon.
At least part of the above and the other related objects is attained by a multiple power source system that supplies an electric power to a three-phase motor, which has Y-connected windings. The multiple power source system includes: a first direct current power source; a power control circuit that is disposed between the first direct current power source and the Y-connected windings of the three-phase motor and has switching elements, which are switched on and off to supply an electric power output from the first direct current power source to the three-phase motor; and a second direct current power source that is different from the first direct current power source. In the multiple power source system, one terminal of the second direct current power source is connected with a terminal of the first direct current power source having an identical polarity. The other terminal of the second direct current power source is connected with a neutral point of the Y-connected windings in the three-phase motor.
The multiple power source system of the present invention enables the two direct current power sources to be connected with each other by a simple arrangement of connection without using any contacts or diodes.
The multiple power source system of the present invention has a variety of possible applications. In accordance with one possible application, the first direct current power source is chargeable with a higher voltage than the second direct current power source. The multiple power source system of this application further includes a charge unit that controls switch-on and -off operations of a specific switching element, which is connected to a specific winding selected among the Y-connected windings of the three-phase motor, so as to step up a voltage using the specific winding, thereby causing the first direct current power source to be charged with an electric power output from the second direct current power source. This arrangement significantly simplifies the structure of charging the first direct current power source with the second direct current power source. This accordingly reduces the size and the manufacturing cost of the whole system and improves the reliability. This structure does not require any semiconductor elements or reactors (windings) for the voltage step-up circuit.
In the multiple power source system of the present invention, the windings of the three-phase motor and the switching elements of the power control circuit are utilized as the constituents of the voltage step-up circuit of the charge unit. This ensures the effective use of the electric parts.
In accordance with one preferable embodiment of the present invention, the power control circuit includes a pair of the switching elements that are provided for each of the windings of the three-phase motor and are interposed between a positive power line and a negative power line of the first direct current power source. Each of the switching elements is connected with a protection diode. A connection point of each pair of the switching elements is connected to the corresponding winding. The charge unit switches on a switching element that is selected among the pairs of the switching elements and is included in a closed circuit including the second direct current power source and the corresponding winding, and subsequently turns off the selected switching element, so as
Nappi Robert E.
Smith Tyrone
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Multiple power source system and apparatus, motor driving... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiple power source system and apparatus, motor driving..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiple power source system and apparatus, motor driving... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2988401