DESC:FIELD OF INVENTION

The present invention relates to double slotted lamination design with toroidal winding for single phase induction motor. More particularly, the present invention addresses a particular winding design which significantly reduces overhang and cost require for winding. Further, the design of toroidal winding arranges the conductor layer to layer thereby reducing copper consumption, stator copper loss, motor length and it eliminates the need of phase separator.

BACKGROUND ART

In conventional winding approach, stator lamination design is having simple slots on stator inner diameter with same or variable slot geometry (refer Fig.1). The concentric type of winding used to have separate winding for Main and Auxiliary phase. With concentric winding, overhang portion appears due to bending radius and extension of coil than the motor core length is significant and contributes to larger coil length, motor length and consumption of copper material. In Single Phase Induction motor mostly concentric type of winding is used, coils of required no. of turns are made by using former or bobbin is used to give proper shape and size to motor. After making, these coils are inserted into stator slot.

As per magnetic design of the motor, the length of conductor required to generate output should be equal to stack length of the motor which is termed as active length of conductor in Electrical Design. The coils in winding consist of number of individual conductors, which in combined situation forms apparently larger conductor. This diameter of coil depends on no. of turns in coil. Because of this, coil has large bending radius and need extended length of conductor to complete its path from one slot to another slot (Coil Span). This extended part is termed as overhang of the motor, which consumes copper but does not play any significant role in motor output. Overhang portion of winding also increases the winding resistance, copper loss, leakage reactance and material cost for the motor.

While inserting these coils into slot there are also the chances of getting wire enamel or slot insulation damaged and which increase the chances of insulation failure.

In the prior art, a Japanese Patent application JP2004173366A (D1), discusses the inventions helpful to increase the efficiency of Single-Phase Induction Motor by using coils with different cross-sectional Area. Variable Slot Depth is used to increase the cross-sectional area of main winding and shallowed slots for Auxiliary winding, amount of copper consumed kept same. In Fig. 7 the applicant illustrate Tooth Portion 104 which is projected evenly in circumferential direction from slot Bottom. Slot 108 with dimensions L holds the main winding deeper slot 112 with dimensions M holds Auxiliary winding shallower. With deeper slots for main winding, cross sectional area has been increased which reduced main winding resistance same has reduced its copper loss. Due to this variation in slot geometry stator core back width (102) has been reduced, results in increased magnetic resistance which increases the magnetizing current drawn by the motor.

The Fig. 8 of D1 shows the motor consist of 24 SLOT and 6 Pole, considering the motor symmetry half cross section has been given here. Main and Auxiliary winding are placed in adjacent slots. 24 Tooth portions 16a to 16d projected from inner circumference. In the stator core 18, 24 slots 24 and 26 are formed between the 24 tooth portions 16a to 16d. In the case of this embodiment, since the winding is distributed, the main coil 20 and the auxiliary coil 22 are housed in two slots each. First, as shown in Fig. 8, the intervals between the tips of the 24 tooth portions 16a to 16d on the inner peripheral side are all protruding at equal intervals with a gap of the same dimension e. The tooth portion (hereinafter, abbreviated as the main tooth portion) 16a that separates the slot (hereinafter, abbreviated as the main slot) 24 in which the main coil 20 is housed from the main slot 24 is the shaft core O of the stator core 18. It protrudes toward.

In another prior art, a Japanese Patent application JP2004222353 (D2), discloses single phase induction motor were discussed with conventional type of lamination and toroidal winding. 16 slot laminations were used to realize 2 pole, 4 pole, 8 pole. 16 slot which is not suitable for 6 pole and concentric winding, hence toroidal winding method is used to wind stator for 6 poles. The use of Toroidal winding has increased the degree of freedom to use same lamination for 2 Pole, 4 Pole, 8-Pole along with 16 Slots. The cost of molding was reduced as same mold used for different polarities and with required performance. There were 5 aspects were discussed to wind 16 Slot rotor with 6 Pole.

In another prior art, a Japanese Patent application JP2013219906A (D3), discuss the conventional type of laminations stator with In and Out type winding orientation used in concentric type of winding. The lamination design with 70 and 80 frames were discussed with different stator ID and Tooth geometries. The stator is made of iron and includes a rotating portion including a shaft and a rotor core, a stationary portion including a stator, and a bearing portion that rotatably supports the rotating portion with respect to the stationary portion about a central axis. An annular core back, a plurality of iron stator teeth extending inward in the radial direction from the core back, and a plurality of coils mounted on each of the plurality of stator teeth in a centralized winding manner are provided. The rotor core includes a back yoke and a plurality of rotor teeth, and the plurality of rotor teeth extend radially outward from the back yoke and are arranged at equal intervals in the circumferential direction, and the rotor teeth are arranged in the axial direction. In the range overlapping with the existence range of the plurality of stator teeth, the sum of all the plurality of stator teeth of the cross-sectional area at the portion where the cross-sectional area is the minimum in each of the plurality of stator teeth overlaps with the existence range of the stator teeth in the axial direction. A single-phase induction motor that is greater than the sum of the cross-sectional areas of all the plurality of rotors in the range where the cross-sectional area is minimized in each of the plurality of rotors.

In yet another prior art, a Japanese Patent application Japanese Patent JPH09312946A (D4), relates to a winding technology for a motor used in an air conditioner or the like, and more particularly specifically, a motor winding method for making stator core of a condenser motor usable for both Brushless Motor and Three-Phase Induction Motor. Considering the phases, this patent discusses the Three phase BLDC and Induction Motor, whereas we are discussing Single Phase Induction motor stator with Toroidal winding.

Therefore, there is an utmost need is to reduce all problems because of overhang. The inventors herein have generated totally new and innovative method to make stator winding design. This method is known as “Toroidal Winding” This way will reduce waste copper by considerable amount (up to 30%) without affecting any performance/reliability/usage related issue. Most of induction motor winding done by coil making, coil insertion, lasing, varnishing. In case of toroidal winding coil making and lasing is eliminated, and stator can be directly wound as per required design. There’s no existing solution to reduce significant copper content without affecting performance & reliability of product.

SUMMARY OF INVENTION

The most of Single-Phase induction motors are made with concentric type of winding on stator. In conventional windings method, we were using coil making process with phase separator. Overhang for such motor is very high and significant if compare to stack length of the Motor. In this approach, we have designed the double slotted stator lamination with 24 slots which have slots on outer surface of lamination as well as the inner diameter (refer Fig. 4). These slots are wounded with Toroidal type winding method for Single Phase Induction Motor. In this method we can directly perform winding on stator slot manually or with winding machine, which significantly reduces overhang and cost require for winding. In case of performance, this winding creates working flux same as conventional winding and keeps motor performance unaltered. The design of toroidal winding arranges the conductor layer to layer and reduced overhang of the motor. It is also providing additional advantages such as reducing copper consumption, stator copper loss, motor length and it eliminates the need of phase separator.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 illustrates a conventional Induction Motor Winding as known prior art;

Figure 2 illustrates final Stator with Double Slotted lamination and Toroidal Winding in accordance with the present invention;

Fig. 3 illustrates simulation Model for 24 Slot Toroidal Winding Single Phase Motor Lamination in accordance with the present invention;

Fig. 4 illustrates double Slotted Lamination for Toroidal Winding with 24 Slots in accordance with the present invention;

Figure 5 illustrates Flux Density Plot for Single Phase Induction Motor with Toroidal Winding in accordance with the present invention;

Figure 6 illustrates Flux Line Distribution for Single Phase Induction Motor with Toroidal Winding in accordance with the present invention;

Figure 7 illustrates the lamination diagram used in Japanese Patent JP2004173366A

Figure 8 illustrates the Variable Slots for Main and Auxiliary in Japanese patent JP2004173366A

DETAILED DESCRIPTION

The most of Single-Phase induction motors are made with concentric type of winding on stator. In conventional windings method, we were using coil making process with phase separator. Overhang for such motor is very high and significant if compare to stack length of the Motor. In this approach, we have designed the double slotted stator lamination with 24 slots which have slots on outer surface of lamination as well as the inner diameter (refer Fig. 4). These slots are wounded with Toroidal type winding method for Single Phase Induction Motor. In this method we can directly perform winding on stator slot manually or with winding machine, which significantly reduces overhang and cost require for winding. In case of performance, this winding creates working flux same as conventional winding and keeps motor performance unaltered. The design of toroidal winding arranges the conductor layer to layer and reduced overhang of the motor. It is also providing additional advantages such as reducing copper consumption, stator copper loss, motor length and it eliminates the need of phase separator.

As discussed in conventional winding approach, stator lamination design is having simple slots on stator inner diameter with same or variable slot geometry (refer Fig.1). The concentric type of winding used to have separate winding for Main and Auxiliary phase. With concentric winding, overhang portion due to bending radius and extension of coil than the motor core length is significant and contributes to larger coil length, motor length and consumption of copper material.

In order to solve these issues and maintain motor performance same as conventional motor, we have designed the double slotted stator lamination (refer Fig. 4). Toroidal winding method is used with 2 coil slot pitch and for two phase winding (refers Fig.2 and Fig. 3). The using double slotted lamination also helped to separate each coil side of winding as one coil side is passing through the lower slot and second layer is through upper slot. Due to this we don’t have to use coil separator and possible fault condition get eliminated. Motor has given improved performance, reduced material and size than conventional winding method. Simulation method and achieved parameters are discussed below in detail

In Double Slotted lamination design (refer Fig. 4), having slots on outer surface and inner surface of the stator lamination. With toroidal winding, one coil side passes through the inner slot present at lamination inner diameter and another coil side passes through the outer slot at outer surface of lamination design. Single Phase Motor with double slotted lamination and suitable winding has been simulated (refer figure 3) to achieve desired parameters and analyze the critical design parameters such as Rated Torque, Current, Starting Torque, motor part Flux Densities and Flux paths through the various motor part.

Toroidal windings are relatively short and wound in a closed magnetic field. It will have a lower secondary impedance which will improve motor efficiency, electrical performance and reduce stator copper losses. The advantage of the a toroidal shape is that, due to its symmetry, the amount of magnetic flux that escapes outside the core (leakage flux) is low, therefore it is more efficient compare to conventional design.

Below Figure 5 shows the Flux density variation along the motor surface of motor with Toroidal Winding, pole generation is found same as conventional winding. If we analyze the flux lines (refer fig. 6), flux path is symmetrical and like conventional type of 2 Pole Induction Motor.

Output Parameters With
Conventional Winding With Toroidal Winding
Voltage (V) 220 220
Rated Current (A) 1.15 1.38
Rated Torque (Nm) 0.7288 0.8278
Speed (rpm) 2692 2703
Starting Current(A) 2.97 2.9
Starting Torque (Nm) 0.122 0.387

Table 1: Simulation Output Results for Motor

Output Parameters With
Conventional Winding With Toroidal Winding % Change
Copper Weight (Kg) 0.440 Kg 0.3 Kg Approx. 32% reduced
Length of Overhang (mm) 30 mm 5 mm Approx. 80 % Reduction

Table 2: Comparison for achieved Parameter

Both the prototype with conventional concentric and Toroidal winding has been tested for their performance, Table 1, represents the simulation output result for Rated Torque, Rated Current, Speed, Starting Torque and Starting Current. If we compare the simulation outputs, we can see that motor with double slotted lamination and toroidal achieves the improved performance compare to Conventional Motor.
Comparison for practically achieved parameters has been given in Table 2, parameters like Copper Weight, Reduction in length of Overhang and Cost saving. We can see the significant improvement in same.
This method of winding can be used with any of available lamination material grade, also considering winding material combinations can be done as mentioned in Table No.3:
Winding Material
Sr. No Main Winding Auxiliary Winding
1 Copper Copper
2 Copper Aluminium
3 Aluminium Copper
4 Aluminium Aluminium

Table 3: Combinations for Main & Auxiliary winding material

Therefore there is provided multiple external slots available in outer surface of stator lamination. The present invention uses inner outer slot stamping design, which helps to separate both coil sides without separation paper. It improves the slot fill factor and results in increased motor efficiency. The design prevent coil short circuit due to external slots available on surface of stamping. The possibility of damage of winding enamel failure in winding as slot separation is not available on external surface is greatly reduced.

Example :-
In present Invention, we are using Double slotted lamination having slots on outer and inner stator periphery to accommodate main and auxiliary winding (Refer Fig.4). Outer slots are termed as 1U to 24U which represents Upper slots and Inner slots are termed as 1L to 24L which represents Lower slot. Main winding starts from slot 1L and returns from 1U to make one coil with required no. of turns. Main winding will be accommodated in slot 1L to 4U with same winding orientation. From Slot 5L to 8U there will be auxiliary winding, same pattern will be followed in next half part of stator. Out of 24, total 16 Slots will be filled with Main winding and 8 slots will be filled with Auxiliary winding.

Further, we have used double slotted lamination geometry to realize the toroidal winding. Our main objective was to reduce material consumption, cost without affecting the motor performance.

7. Advantages and Disadvantages for Toroidal Winding:

Advantages:
1. It gives improved performance compared to conventional Winding.
2. It reduces Copper Weight, Length of Overhang and Overall length of the motor.
3. Material cost reduction due to reduction in material consumption.

Disadvantage’s:
1. Time required for winding has been increased, it can be reduced by using suitable automatic winding machine.

Inventive step

1. This method of Toroidal Winding uses double slot lamination i.e. Slots on both at Outer Surface and Inner diameter of stator lamination.
2. Single Phase Induction motor has been wounded with Toroidal Winding method along with designed stampings to get rated output with reduced overall dimension. Winding was designed to achieve same rated performance as conventional Motor with reduced physical dimensions.
3. Motor performance was found improved compare to conventional winding approach.
4. Using double slotted lamination and Toroidal winding has resulted into reduction of consumption of copper material (Up to 30%), material cost, overhang and overall size of the motor. Winding time of these motor can be taken down significantly with proper fixture and winding mechanism.

Many modifications may readily be contemplated by those skilled in the art to which the invention relates. Many further modifications may readily be contemplated. The description set out above is particularly applicable to high rate clarification applications. However, in conventional clarification where the upstream or downstream processes herein described are not used, the teachings according to the invention may have considerable merit and are also applicable. The specific embodiments described, therefore, should be taken as illustrative of the invention only and not as limiting its scope as defined herein

,CLAIMS:

1. A single phase induction motor comprising of :
a double slotted stator lamination which have slots on outer surface of lamination as well as the inner diameter; wherein
the said slots are wounded with Toroidal type winding method for said Motor.

2. The single phase induction motor as claimed in claim 1, wherein the said toroidal winding method is used with 2 coil slot pitch; and
wherein double slotted lamination is adapted to accommodate separate each coil side of winding as one coil side is passing through the lower slot and second layer is through upper slot.

3. The single phase induction motor as claimed in claim 1, wherein the double slotted stator lamination is with 24 slots.

4. The single phase induction motor as claimed in claim 3, wherein for said 24 slots, total 16 Slots is filled with Main winding and 8 slots is filled with Auxiliary winding.

5. The single phase induction motor as claimed in claim 1, wherein said toroidal winding arranges the conductor layer to layer and reduce overhang of the motor.

6. The single phase induction motor as claimed in claim 1, wherein said toroidal winding is configured for reducing copper consumption, stator copper loss, motor length and eliminates the need of phase separator.

7. The single phase induction motor as claimed in claim 1, wherein the main and auxiliary winding is made from either of copper or aluminium.

8. The single phase induction motor as claimed in claim 1, wherein with said toroidal winding, one coil side passes through the inner slot present at lamination inner diameter and another coil side passes through the outer slot at outer surface of lamination design.