Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1998-09-01
2001-04-03
Enad, Elvin (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S216055, C310S216055, C310S254100, C310S256000, C310S256000, C310S261100
Reexamination Certificate
active
06211595
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to an armature structure of a toroidal winding type electric rotating machine, in which a plurality of coils are attached at a predetermined space to an annular core portion of a laminated core.
b) Description of the Related Art
Generally, a rotating electric machine that needs sine waveform magnetic field in an air gap portion employs a distributed winding for a winding method. For example, in a three-phase inductance motor illustrated in
FIG. 19
, a stator S is arranged to surround an outer circumference of a rotor R, and a coil SL is wound about a laminated core SC of an armature constituting a stator S such that the coil SL is superposed, shifting slots. This method in which the coil SL is superposed shifting the slots, however, makes it difficult to wind the coil as well as requires longer winding. Thus, the winding height H
1
may be higher.
On the other hand, a toroidal winding method is known in which a coil is wound about a core annular portion. The toroidal winding method has excellent features in that winding is easy and short because each wound coil is not superposed, and thus the winding height remains low.
In conventional toroidal winding type rotating electric machines, except a flat type, most of the properties of the toroidal winding may be inferior to those of the general distributed winding. Therefore, this method cannot be adopted in some technical fields.
In addition, global environmental issues have become serious recently, requiring energy-saving and power-saving as a first priority. Especially environmental issues are dominated by the issue of power consumption these days, and motors consumes more than half of the available power. For this reason, it is very important to increase motor efficiency and decrease loss (of power) as much as possible. Also, the same consideration is given to generators that generate electric power.
OBJECT AND SUMMARY OF THE INVENTION
A primary object of the present invention is to provide an armature structure of a rotating electric machine in which an armature structure of a toroidal winding type rotating electric machine, excellent in winding, is modified for higher efficiency (enhanced property) so that the efficiency value is greatly improved.
The present invention relates to a property-improved structure of the rotating electric machines including motors and generators. Motors convert electrical energy to mechanical energy; generators convert mechanical energy to electrical energy. Therefore, motors and generators are basically the same in structure and configuration. It is, therefore, possible to use a motor as a generator, and vice versa. For this reason, all the following description will be referred to a motor although the improvement applies equally well to a generator.
Generally, output and torque are used as index of the motor's property. However, the motor's property cannot be expressed in an absolute value by the above indices because the output and torque vary depending on applied voltage, the number of windings, radiating condition, design, etc. The efficiency value is another index of the motor's property which properly expresses the relationship between the output and the loss. However, efficiency value also varies depending on loads or the number of rotations, and therefore, with the initial zero output, the efficiency value is also zero. This also cannot be an absolute index to express the motor's property.
To improve the efficiency value of a motor, it is a basic to understand what the motor's property is, what the efficiency is, and how they are determined. As a result of studies done by the present inventor, the following was understood.
The absolute index of the motor's property is a proportional constant that expresses (determines) the relationship between the torque generated and the loss (copper loss) caused. In a motor without magnets, the proportional constant equals torque/copper loss; in a motor having magnets, the proportional constant is (torque)
2
/copper loss. In other words, the proportional constant that expresses the relationship between the torque and the copper loss caused when the current is applied never changes even when the applied voltage, the number of windings (with the same space factor), and the load condition are changed. Thus, it is understood that this proportional constant is an absolute index that expresses the motor's property.
Also, the efficiency value is output/input=output/(output+loss), where the output is the number of rotation×torque, the number of rotations can be expressed by the applied voltage and the loss, and the loss mainly means the copper loss. Therefore, it is understood that the efficiency value is mostly determined by the proportional constant.
To enhance the motor's property (to increase the efficiency), various attempts have been made, such as making large motors, employing magnets having high energy product, and increasing the space factor of the winding. However, the motor's property is enhanced by changing the condition of factors that determine the proportional constant.
Next described are the reasons why this proportional constant value determines the absolute index of the motor's property and the factors that determine this proportional constant value.
The magnitude of the motor torque depends on the amount of the change in magnetic energy caused by relative move between the primary and secondary sides (currents) which are placed opposite one another. There are two kinds of magnetic energies: one generated and retained by a self-inductance L between the primary and secondary sides (currents); the other generated and retained by a mutual-inductance M between the primary and secondary sides (currents). Which magnetic energy is used for driving depends on the type and structure of the motor. Inductance motors, DC motors, and brushless motors use the magnetic energy caused by M while reluctance motors use the magnetic energy caused by L.
When the configuration such as the number of magnet poles is set, the magnitude of the torque generated at primary and secondary currents I
1
and I
2
is mostly determined by the maximum value of the magnetic energy, that is, the magnitude of the self-inductance L or the mutual-inductance M. The magnitude of the magnetic energy by the self-inductance L is expressed by (½)×L×I
2
; the magnitude of the magnetic energy generated by the mutual-inductance M is expressed by M×I
1
×I
2
. Most of the normal motors other than reluctance motors employ the mutual-inductance M for driving. In many of the motors that do not use magnets, such as inductance motors and universal motors, the first current I
1
is proportional to the secondary current I
2
. Therefore, the magnetic energy can be expressed by M×I
1
×I
2
=M×I
2
where I represents the total current. When a magnet is used for only one side (assuming, it is the primary side), because the magnet is an electromagnet of steady current, the current I
1
is constant and M×I
1
=&phgr; (effective magnetic flux). Therefore, the magnetic energy thereof can be expressed by M×I
1
×I
2
=&phgr;×I.
Since the copper loss is a resistance loss, it can be expressed by R×I
2
. In a motor without magnets, the proportional constant that determines the relationship between the torque and the copper loss is torque/copper loss. Consequently, the proportional constant can be expressed by L/R or M/R. With a motor having magnets, the proportional constant is (torque)
2
/copper loss, bringing M
2
/R as a result.
Considered next is the factors that determine L, M, and R. Eliminating the factor, the number of winding turns of coil, which affects equally L, M, and R, L and M can be mainly expressed by the primary-secondary-sides facing surface S and the air gap length, g. For the motor having magnets, material characteristics, size, and shape of the ma
Dinh Le Dang
Enad Elvin
Reed Smith LLP
Sankyo Seiki Mfg. Co. Ltd.
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