FIELD OF THE INVENTION:

The present invention is generally related to the electrical machines and in particular to a permanent magnet motor cum permanent magnet generator. More particularly, the invention is related to the utilization of two flux streams i.e., radial flux and axial flux in an electrical machine.

BACKGROUND AND PRIOR ART:

Fans are being used in electrical machines mainly to obtain air flow across the frame or windings to decrease the temperature there by increasing the power density. In addition to exploiting the purpose of fan mounted over the shaft in an electrical machine, the fan can also be used in generating electricity if fan is constructed with a ferromagnetic material there by making fan, a component in electromagnetic energy conversion.

Therefore, an object of the invention is to integrate a permanent magnet generator in the permanent magnet motor by making required modifications to the fan structure and end plate of stator frame. Thus in the present invention, a hybrid flux PM motor cum PM generator using both the radial and axial flux permanent magnet technologies is proposed.

In US3809995 patent, a multiple output alternator having separate sets of power coils mounted on the stator adapted to be magnetically excited by a rotor having a direct current field coil is proposed. The multiple output alternator proposed in US3809995 patent can provide two different voltage levels as two separate sets of power coils are mounted on the stator but the frequency of the two voltages will be same. The power electronic equipment is very much needed if the multiple output alternator proposed in US3809995 patent has to provide the voltages with different frequencies.

Therefore, another object of the invention is to provide an alternator two AC outputs of different voltages and different frequencies which can be realized by the proposed hybrid flux PM motor cum PM generator.

OBJECTS OF THE INVENTION:

An object of the invention is to integrate a permanent magnet generator in the permanent magnet motor for developing a hybrid flux PM motor cum PM generator.

Another object of the invention is to propose the machine such that it outputs two different voltages at different frequencies when it is used as a generator completely.

Further object of the invention is to increase the power density of the proposed hybrid flux PM motor cum PM generator.

SUMMARY OF THE INVENTION:

According to the aspect of the invention, a hybrid flux PM motor cum PM generator utilizing both the radial flux permanent magnet technology and axial flux permanent magnet technology is proposed by suggesting modifications to the fan structure and modifications to the end plate of the stator frame.

The hybrid flux PM motor cum PM generator is also significant in that the axial stator core is integrated to outside of end plate of stator frame such that the axial stator core faces the fan carrying axial flux permanent magnets as shown in Fig. 1.

The hybrid flux PM motor cum PM generator is significant in that it is based on both the utilization of radial flux permanent technology and axial flux permanent magnet technology with one rotor carrying radial flux permanent magnets and another rotor, which is actually a modified fan structure, carrying axial flux permanent magnets as shown in Fig. 2.

The hybrid flux PM motor cum PM generator is also significant in that the fan structure having blades must be sufficiently thick enough to avoid losses in the magnetic circuit. The rim of fan over which its blades are present must also be sufficiently thick enough to provide the path for magnetic flux as shown in Fig. 3.

The advantages of the present invention will become apparent from the following detailed description of embodiments with reference to the accompanying drawings, in which:

Fig. 1: is a view of 3D model of axial stator core integrated to end plate of stator frame of hybrid flux PM motor cum PM generator.
Fig. 2: is a view of 3D model of hybrid flux PM motor cum PM generator utilizing radial flux permanent magnet technology and axial flux permanent magnet technology.
Fig. 3: is a view of 3D model of ferromagnetic fan structure carrying axial flux

permanent magnets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:

According to the aspect of the invention, an approach for utilizing both the radial flux technology and axial flux technology is proposed in the hybrid flux PM motor cum PM generator by suggesting modifications to the fan structure and modifications to the end plate of the stator frame. The use of both the radial and axial flux permanent magnet technologies in the present invention also results in the increase of the power density of hybrid flux PM motor cum PM generator.

The hybrid flux PM motor cum PM generator is also significant in that the axial stator core 101 is integrated to the end plate 102 of stator frame 103. The axial stator core is fixed outside the endplate of stator frame such that it faces the fan 104 carrying axial flux permanent magnets 105 as shown in Fig. 1.

The hybrid flux PM motor cum PM generator is significant in that it has one rotor 201 carrying radial flux permanent magnets 202 and another rotor 203, which is actually a modified fan structure, carrying axial flux permanent magnets 204 as shown in Fig. 2. The radial flux permanent magnets are inserted in the slots made along the length of the rotor core circumferentially as shown in Fig. 2. Though the rotor structure shown in Fig. 2 is of insertion type for the radial flux permanent magnets for illustration of concept, the rotor structure of surface mounted type or other rotor structure can also be used.

The hybrid flux PM motor cum PM generator is also significant in that the fan structure is made of ferromagnetic material. The fan blades 301 must be sufficiently thick enough to avoid losses in the magnetic circuit. The rim 302 of ferromagnetic fan over which its blades are present must also be sufficiently thick enough to provide the path for magnetic flux as shown in Fig. 3.

The power electronic equipment is very much required when the alternator, capable of providing certain voltage level with certain frequency, has to supply power to the load

that needs voltage level or frequency other than the rated voltage and rated frequency of alternator. At the same time, the power electronic circuit will also become complex if the alternator is to be provided with multiple outputs of different voltages with different frequencies.

The proposed hybrid flux PM motor cum PM generator can also be operated as a generator completely with two AC outputs of different voltages and frequencies. Though 10 radial permanent magnet poles over the circumference of the rotor and 8 axial permanent magnet poles on ferromagnetic fan are taken in the 3D model of hybrid flux PM motor cum PM generator along with 45 slots in the radial and 36 slots in the axial stator cores, the number of poles and slots can be varied as per the design requirement in order to have different voltage and frequency levels. Thus the proposed hybrid flux PM motor cum PM generator can be made to provide two AC outputs of different voltage levels and frequencies by appropriate selection of number of poles and number of turns in the stator winding and other parameters.

Though the 3D model of hybrid flux PM motor cum PM generator shown in Fig. 2 is fractional slot type, it can also be designed as integral slot type and even concentrated windings can also be used instead of distributed winding. In the proposed machine, the motor need not be a PM motor but also any other motor like induction motor, dc motor etc. The proposed machine can also have axial flux PM generators at either end of shaft

such that the ferromagnetic fan at one end aids the air flow of the ferromagnetic fan at the other end.

The axial flux permanent magnet generator developed by utilizing the fan itself as a rotor with permanent magnets can provide reasonable amount of auxiliary power for various auxiliary equipment. The generated power can also be utilized for charging the batteries by using a suitable rectifier.

Thus in the present invention, an approach for utilizing both the radial flux permanent magnet technology and axial flux permanent magnet technology in the hybrid flux PM motor cum PM generator is proposed in order to have PM generator integrated with PM motor. Alternatively the proposed hybrid flux PM motor cum PM generator can be operated as a generator completely with two AC outputs of different voltages and frequencies. As an additional consequence of the present invention, the proposed multiple output hybrid PM alternator has got increase in the power density.

WE CLAIM

1) A hybrid permanent magnet (PM) motor cum generator, having the axial stator core (101) fixed outside the end plate (102) of stator frame (103), wherein the said core facing the fan (104), carrying axial flux permanent magnet (105); rotor (201) carrying radial flux permanent magnets (202), another rotor (203), a modified fan structure in particular, carrying axial flux permanent magnets (204).

2) The fan (104), (203) as claimed in claim 1, having the blades (104, 301) and rim of thick ferromagnetic material providing the path for maximum magnetic flux.

3) The fan (104) blades (301) as claimed in claim 2, having two teeth such that the distance between two teeth decreases as the radial distance increases.

4) The hybrid flux PM motor cum PM generator as claimed in claim 1, characterized by utilization of both radial and axial flux permanent magnets, operates as a generator with two AC outputs of different voltages and frequencies.

5) The hybrid flux motor cum generator as claimed in claim 4, wherein desired voltage levels and frequencies can be achieved through appropriate selection of no. of poles and no. of turns in the stator winding.

6) The hybrid flux motor cum generator as claimed in claim 5, wherein the axial flow PM generator can operate at either end of the shaft such that the ferromagnetic fan at one end aids the air flow of the ferromagnetic fan at the other end.
Abstract
In order to increase the power density of permanent magnet motor, fans are used to develop air cooled machines. The fans that are used in the air cooled machines are made of aluminium to exploit the advantage of light weight. The objective of the invention is to generate electricity while the permanent magnet motor is running without altering much its size and the performance of the fan. Therefore in the present invention, a hybrid flux permanent magnet motor cum permanent magnet generator is proposed by utilizing the axial flux technology along with the radial flux technology. Alternatively, the proposed hybrid flux PM motor cum PM generator can also be utilized as hybrid flux PM generator with two outputs of different voltages and different frequencies.