US 5,883,489 A · High speed deep well pump for residential use

Abstract

A power control system in combination with a three-phase AC motor coupled to a water pump enables the operation of the motor at speeds up to 10,800 RPM so as to provide improved pumping capacity with a smaller motor and smaller pump. The control system supplies AC power to the motor with a frequency of the power being increased at a first high rate up to a frequency at which pump pressure is about equal to a value at which water is being pumped from the outlet pipe of the pump. Thereafter, AC power frequency is increased to the second, slower rate up to a maximum operating frequency of the motor. During the time that frequency of the AC power is being increased, motor current is continuously monitored and compared to a maximum allowable current. If monitored current exceeds allowable current, the frequency of operation is decreased until monitored current is less than the allowable current. Thereafter, frequency is again increased so long as monitored current is less than allowable current. Preferably, the allowable current is set to maintain operation of the motor at about its pullout torque level throughout the range of operation.

Claims26

Dependent claims

A method for controlling torque of an alternating current (AC) electric motor driving a variable load in a system including a controllable, variable frequency source of AC electric power coupled to the motor, the method comprising the steps of:

applying AC power to the motor from the variable frequency source while incrementing the frequency of the AC power from about zero Hertz to a first preselected frequency at a relatively fast rate;
incrementing the AC power frequency at a second slower rate above the first preselected frequency;
and
during each step of applying and incrementing the AC power frequency, monitoring and comparing current in the motor to a predetermined magnitude and, if motor current exceeds the predetermined magnitude, decrementing the AC power frequency by a selected increment.

1 more element

A water supply system comprising:

a water pump and electric motor assembly for placement in a water source in which the pump comprises a centrifugal pump having a plurality of stacked impellers on a common shaft and the motor comprises a three-phase, AC induction motor having a rotor adapted for rotation at speeds up to about 10,800 revolutions per minute, the rotor having a shaft connected for direct drive of the pump impeller shaft;
a rectifier assembly having input terminals for connection to a source of AC electric power and having a pair of output terminals for providing a rectified DC output onto a pair of relatively positive and relatively negative voltage busses;
a filter capacitor connected across the pair of voltage busses;
a three-phase electric power inverter connected to the pair of voltage busses and including a plurality of electronically controllable switching devices for producing a controlled frequency, three-phase power output at output terminals thereof, the inverter output terminals being connected to corresponding input terminals of said motors;
a microcontroller for developing switching signals for application to the controllable switching devices in the inverter, the microcontroller including a microcomputer operating a program for computing the start and duration of the switching signals;
a pressure switch coupled to the water system and adapted for producing a first signal when water pressure is at a first upper limit value and for producing a second signal when water pressure is at a second lower limit value;
apparatus for producing an increasing DC voltage in response to the second signal, said microcontroller being coupled to receive said increasing DC voltage and for generating said switching signals at a frequency proportional thereto;
current sensing means coupled for providing a current signal representative of motor current;
and
mean is responsive to said current signal for varying said increasing DC voltage in a manner to control the frequency of said switching signals to prevent said motor current from exceeding a selected maximum value.

7 more elements

Dependencies are inferred from the claim text.

High speed deep well pump for residential use

Life of this patent

High speed deep well pump for residential use

Life of this patent

Abstract

Claims26