Prime-mover dynamo plants – Electric control – Engine control
Reexamination Certificate
2000-09-01
2002-10-08
Waks, Joseph (Department: 2834)
Prime-mover dynamo plants
Electric control
Engine control
C310S114000
Reexamination Certificate
active
06462430
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a hybrid-type electric vehicle. More particularly, the invention relates to an electric rotary machine for driving the hybrid drive type vehicle and generating an electric power, and a control method therefor. Further particularly, the invention relates to an electric rotary machine, in which a rotor of the electric rotary machine is constructed with a first field magnet and a second field magnet, and which is variable of effective flex amount depending upon a direction of torque.
DESCRIPTION OF THE RELATED ART
As a conventional hybrid drive type vehicle, there are (1) a series hybrid type driving a generator by an output torque of an engine as an internal combustion engine for obtaining an electric power and driving a electric rotary machine connected to a wheel axle by the electric power for driving a vehicle by a driving torque generated by the electric rotary machine, and (2) a parallel hybrid type, in which a part of the output torque of the engine is converted into an electric power and remaining output torque is transmitted to the wheel axle as driving torque for driving the vehicle by a driving torque of the electric rotary machine using the generated electric power and the wheel axle driving torque of the engine.
In the recent trend, in view point of sizes and costs for the motor and/or battery, attention is attracted to (2) the parallel hybrid driving type vehicle. For example, as disclosed in Japanese Patent Application Laid-Open No. 9-132042 (1997), a parallel hybrid drive type vehicle of the type wherein the engine and two electric rotary machines are connected to respective shafts of a planetary gear mechanism and a driving force is distributed depending upon load and revolution speed of the engine and respective electric rotary machines (this type will be hereinafter referred to as “two motor system”), has already marketed.
However, such prior art requires two electric rotary machines and two inverter circuits for driving the electric rotary machines and newly arranging the planetary gear mechanism and thus requires significant reconstruction of the vehicle to cause significant increase of the cost associating therewith.
Therefore, as shown in Japanese Patent Application Laid-Open No. 7-298696 (1995), there has been proposed a system, in which an electric rotary machine is directly connected to a crankshaft of the engine for switching driving mode and generating mode in one electric rotary machine (this system will be referred to as “single motor system”). This single electric rotary machine system is advantageous in view point of cost and capability of add-on the existing vehicle.
In both of single motor system and two motor system, as the electric rotary machine, a permanent magnet field type electric rotary machine arranged a permanent magnet on a rotor or a squirrel cage induction electric rotary machine, in which a secondary conductors made of aluminum alloy or copper alloy are arranged on the rotor in cage-like fashion, may be employed.
As set forth above, the single motor system is more advantageous than the two motor systems in viewpoint of the cost. However, the following constraints are present even in the single motor system.
(1) It has to be achieved both of a high torque characteristics in low revolution speed range upon starting-up of the engine and high-power generation characteristics in high revolution speed range.
(2) A revolution speed to generate a torque (maximum torque to be generated by the motor) upon starting-up of the engine is less than or equal to one tenth for a motor revolution speed at the allowable maximum revolution speed of the engine.
(3) The present invention is directed to the electric rotary machine mounted on the vehicle, and as a power source, a battery charging and discharging within a voltage variation range centered at a certain voltage, is employed. Therefore, if a voltage far beyond a charging voltage of the battery is charged, it is possible to damage the battery in the worst case.
SUMMARY OF THE INVENTION
The present invention has been worked out in view of the shortcoming in the prior art as set forth above. It is therefore an object to provide a hybrid drive type vehicle having a permanent magnet type synchronous motor obtainable of high torque characteristics in low revolution speed range of the engine and high power generation characteristics at high revolution speed range of the engine.
According to one aspect of the present invention, a hybrid drive type vehicle comprises:
an internal combustion engine driving a vehicle;
a battery charging and discharging an electric power;
an electric rotary machine mechanically connected with a crankshaft of the internal combustion engine for starting up the internal combustion engine as driven by the electric power supplied from the battery, and driven by revolution of the internal combustion engine for performing generation for charging the battery;
an inverter for controlling driving and generating of the electric rotary machine;
a controller controlling the inverter;
revolution speed detecting means for detecting a revolution speed of the internal combustion engine or the electric rotary machine;
the electric rotary machine being formed with a stator having a primary winding and a rotor having a field magnet, the field magnet being constituted of a first field magnet alternately arranged mutually opposite magnetic poles in sequentially in circumferential direction and a second field magnet capable of causing relative angular displacement relative to the first field magnet and alternately arranged mutually opposite magnetic poles in sequentially in circumferential direction, the first and second field magnets being opposing with a magnetic pole of the stator and having a mechanism for varying a phase of a magnetic pole resulting from combination of the first and second field magnets relative to the magnetic pole of the first field magnet depending upon direction of a torque of the rotor,
the mechanism for varying the magnetic pole depending upon the direction of the torque including means for aligning centers of the same magnetic poles of the first and second field magnets by balance between torque direction generated in the rotor and magnetic action between the first and second magnetic and means for causing offset of the center of the same magnet poles of the first and second field magnetic associating with generation of the torque generated in the rotor in the opposite direction.
Operation of one aspect of the invention as set forth above will be discussed.
In
FIG. 6
, the characteristics of an effective flux relative to a rotational angular velocity of the permanent magnet type synchronous electric rotary machine, an induced electromotive force, and a terminal voltage are shown.
An induced electromotive force E
O
of the permanent magnet type synchronous electric rotary machine is determined by a constant magnetic flux &PHgr; generated by the permanent magnet and rotational angular velocity &ohgr; of the electric rotary machine. Namely, as shown in
FIG. 6
, when the rotational angular velocity &ohgr; of the electric rotary machine (revolution speed) is increased, the induced electromotive force E
O
of the electric rotary machine is proportionally increased. However, as an essential condition in mounting on the vehicle is charging of the battery. In order to charge the battery, the induced electromotive force to be generated in the electric rotary machine has to be suppressed to be lower than or equal to a battery charge voltage so as not to damage the battery. Therefore, in the permanent magnet type synchronous electric rotary machine, it requires to perform weakening field control for reducing magnetic flux generated by the permanent magnet in range of the revolution speed higher than or equal to a predetermined value.
Since the induced electromotive force is increased in proportion to the rotational angular velocity, current for weakening field control has to be increased. Therefore, a large
Ajima Kou
Hanyu Tomoyuki
Hino Noriaki
Innami Toshiyuki
Joong Kim Houng
Hitachi , Ltd.
Waks Joseph
LandOfFree
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