Drive circuit for electric motors

Patent metadata

Field	Value
Publication number	US-10840830-B2
Application number	US-201816500741-A
Country	US
Kind code	B2
Filing date	Apr 3, 2018
Priority date	Apr 4, 2017
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A drive circuit for an electric pump motor is provided. The drive circuit includes an inverter and a contactor. The inverter is configured to supply variable frequency current to the electric motor. The contactor is configured to supply the line frequency current to the electric motor.

First claim

What is claimed is:

1. An electric pump system, comprising:
a pump configured to be disposed in fluid communication with a volume of fluid, said pump and the volume of fluid together defining a load;
an electric motor comprising a rotor and a stator, said rotor coupled to said pump; and
a drive circuit coupled to said stator, said drive circuit comprising:
an inverter configured to supply an alternating current (AC) power to said stator when the load is a full load; and
a contactor configured to supply a line frequency power from an AC source to said stator when the load is a low load that is less than the full load.

2. The electric pump system of claim 1 , wherein said drive circuit further comprises a rectifier stage configured to convert the line frequency power to a direct current (DC) power that is supplied to said inverter.

3. The electric pump system of claim 1 , wherein said stator comprises a main winding coupled across a first phase output and a second phase output of said inverter, and a start winding coupled across a the second phase output and a third phase output of said inverter when operating said electric motor using said inverter.

4. The electric pump system of claim 3 , wherein said stator comprises said main winding coupled to a first phase output of said contactor, and said start winding coupled to the first phase output of said contactor through a capacitor.

5. The electric pump system of claim 4 further comprising a switch device configured to couple and decouple the capacitor from said start winding.

6. The electric pump system of claim 1 further comprising a system controller configured to control operation of said contactor.

7. The electric pump system of claim 1 further comprising a semiconductor switch coupled in parallel with said contactor and between the AC source and said stator, said semiconductor switch configured to couple said stator to the line frequency power when transitioning from operating said electric motor with said inverter to operating said electric motor with line frequency power.

8. The electric pump system of claim 1 , wherein the full load is characterized by a high speed and a high fluid flow rate demand.

9. The electric pump system of claim 1 , wherein the low load is characterized by a variable speed and a variable fluid flow rate demand.

10. A method of operating an electric pump system to drive a pumping load, said method comprising:
operating an inverter to supply an alternating current (AC) power to a stator of an electric motor when the pumping load on the electric motor is a low load;
disabling the inverter; and
closing a contactor coupled between the stator and an AC source to supply line frequency power to the stator when the pumping load is a full load.

11. The method of claim 10 further comprising rectifying the line frequency power to produce a direct current (DC) power to supply the inverter.

12. The method of claim 10 , wherein operating the inverter to supply AC power to the stator comprises coupling windings of the stator across three phases of output from the inverter in line-to-line configuration.

13. The method of claim 12 further comprising coupling, by a switch, a start winding of the stator to a phase of the line frequency power through a capacitor when the inverter is disabled and the contactor is closed.

14. The method of claim 10 , wherein operating the inverter further comprises generating the AC power having a variable frequency and a variable amplitude to meet a variable pumping load.

15. The method of claim 14 further comprising closing a semiconductor switch coupled in parallel with the contactor and between the AC source and the stator, wherein closing the semiconductor switch couples the stator to the line frequency power when transitioning from operating the electric motor with the inverter to operating the electric motor with line frequency power.

Assignees

• Regal Beloit America Inc

Inventors

• Chretien Ludovic Andre
• Richardson Howard R
• Gross Gregory Lewis
• Reynolds Jevon D
• Carnes Joseph Stephen
• Stauffer Zachary Joseph
• Magyar Justin Michael
• Osborne Kenneth L
• Snell Nathan E

Classifications

• F04D13/06 Primary

  the pump being electrically driven · CPC title

• H02P1/44 Primary

  by phase-splitting with a capacitor · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P25/04

  Single phase motors, e.g. capacitor motors · CPC title

• H02P25/26

  with arrangements for controlling secondary impedance · CPC title