This invention relates to a high frequency motor system for use, inter alia, with a submersible pump.
Generally, a single phase motor operates on a voltage of 210 volts and a supply frequency of 50 Hz. The motor develops speeds depending on the number of poles of the motor.
The performance of these motors depends on the speed of operation. The speed is proportional to the frequency.
This invention converts the line frequency of 50 Hz to a range between 81 Hz to 92 Hz by means of frequency width modulation. This invention also furnishes a 3 phase supply from a single phase supply source, whereby a single phase motor is made to work as a three phase motor.
The high frequency motor system , according to this invention, comprises a single phase motor; a controller for increasing the frequency of the single phase supply to the motor and for converting the said single phase to three phase, for operation of the motor as a three phase motor.
The single Figure in the accompanying drawings illustrates, schematically, by way of example, and not by way of limitation, one of possible embodiments of this invention, wherein a single phase supply source is indicated by S, the controller by C, the motor by M and the pump by P.

In this invention the input power is maintained constant and within the capacity of the motor although there is a 32% higher output (head)
According to a preferred embodiment the invention has the
following advantages:
A single phase 1 HP motor is made to work as a 3 phase 1 HP motor.
An increase in total head - 32 % more than the conventional with
reduced stages is achieved.
There is better insulation and there are better stampings.
There is reduced length of the pump set.
An aluminium die cast rotor is provided for the motor. The aluminium
rotor results in cost saving apart from better performance.
The line frequency in India is 50 Hz with a variation of plus or minus 3 % and all conventional motors work under 50 Hz frequency. However the motor according to this invention operates at a frequency of 81 - 92 Hz. Thus the performance of a 1 HP 8 stage pump set is equalled or exceeded by a 4 stage pump. The head developed by a 1 HP 8 stage pump set is 63.0 meters whereas the high frequency motor coupled to a 4 stage pump according to this invention develops a head of 83.0 meters. The head per stage of the conventional 8 stage pump set is 7.9 m/stage whereas in the proposed high frequency motor pump set it is 20.75 m/stage, an increase of almost 3 times. The total head developed by the proposed high frequency pump set is about 32 % more.
Another feature of the proposed high frequency motor-pump set is that the power input remains constant throughout the entire operation with little variation.

The controller used in accordance with this invention, taking supply from a single phase source, converts the line frequency through pulse width modulation and raises the frequency from 50 Hz to 81 - 92 Hz frequency. Through a system of variable frequency controller the single phase is converted to 3 phase and supplied to the motor from the controller.
The motor according to this invention has to withstand high stress due to the increased frequency. The insulation has to be safe against this high stress. For the 3 phase voltage generated by the controller in a series of sharp pulses, by pulse width modulator in the controller, a winding wire to withstand this stress has been provided. The wire has 4 layers, the first layer enamel coated copper wire, the second layer Bopp (biaxially oriented polypropylene), the third layer Bopp and the fourth layer Bopp. This wire can withstand very high frequency without the insulation getting damaged.
The core length of the stator is kept at 120 mm and the stamping is M43 grade as against 155 mm core length and M 47 grade stamping in conventional 1 HP motor.
The motor and pump according to this invention will work with a motor controller, such as ? of the Tribi type.
One of the notewrorthy features of this invention is that the 1 HP single phase motor, by suitable conversion of th frequency, from normal supply frequency of 50 Hz to a range from 81 Hz to 92 Hz operates as a 3 phase motor.

Hence the invention proposed herein results in direct increase in the discharge by 1.62 times and the head by 2.62 times and the power by 4.25 times. As a large amount of power cannot be handled by a 1 HP motor, it is proposed to keep the discharge substantially equal to a conventional pump set keep the input power constant and allow a permissive increase in head. To keep the discharge substantially equal to the conventional 1 HP 8 stage pump set the impeller outer diameter is reduced to 76 mm from 78 mm. This has resulted in a material saving in the impeller and the assembly. Again as the head increases by 2.62 times at the same 8 stage the number of stages has been reduced to 4 from 8 of the conventional pump. The proposed high frequency motor-pump develops a head of 83.0 meters which is 1.32 times that of a conventional 1 HP 8 stage pump as against 2.62 times to keep the power input within limits.
The head developed by the motor-pump proposed herein is almost equal to the head developed by a conventional 1.5 HP submersible pump set, while the cost of the former and the latter is almost the same.
The terms and expressions herein are of description and not of limitation, having regard to the scope and ambit of this invention.

We Claim:
1. A high frequency motor system comprising a single phase motor coupled to a pump; a controller for increasing the frequency of the single phase supply to the motor and for converting the said single phase to three phase, for operation of the motor as a three phase motor.
2. A high frequency motor system as claimed in Claim 1 wherein the increase in frequency of the single phase supply to the motor is from 50 Hz to 81-92 Hz.
3. A high frequency motor system as claimed in Claim 1 or Claim 2 wherein the motor has an aluminium die cast rotor.
4. A high frequency motor system as claimed in any one of the preceding Claims wherein the motor is of 1 HP rating.
5. A high frequency motor system as claimed in any one of the preceding Claims wherein the core length of the stator of the motor is 120 mm.
6. A high frequency motor system as claimed in any one of the preceding Claims wherein the stamping of the motor is of M43 grade.
7. A high frequency motor system as claimed in any one of the preceding Claims wherein the winding wire is of the 4 wrap polyester submersible type, the first layer enamel coated copper wire, the second layer Bopp (biaxially oriented polypropylene), the third layer Bopp and the fourth layer Bopp.

8. A high frequency motor system as claimed in any one of the
preceding Claims wherein the impeller outer diameter is 76
mm.
9. A high frequency motor system wherein the pump is of the 4
stage type.
10.A high frequency motor system substantially as herein described and illustrated.