Power supply derived from motor winding

• US 5,604,387 A
• Filed: 05/11/1994
• Issued: 02/18/1997
• Est. Priority Date: 12/19/1990
• Status: Expired due to Term

• Current Assignee: Fisher & Paykel Limited
• Original Assignee: Fisher & Paykel Limited
• Inventors: Cheyne, Neil G.
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US08/241,067
• Time in Patent Office: 1,014 Days
• Field of Search: 318/244, 318/245, 318/293, 318/434, 307/96, 307/98, 307/116, 307/48, 307/117, 307/87, 307/125, 307/66, 307/130, 307/154, 307/99, 307/100, 307/104, 363/89, 323/905, 323/282, 323/324, 323/351, 327/530, 327/544, 361/159
• US Class Current: 307/125
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control

Abstract

A low voltage power supply which uses a low voltage transistor in conjunction with a winding of an electric motor and the high voltage motor commutation transistors. The motor winding is energised by the commutation transistors for example during use of the motor, and the low voltage transistor is used to divert current from the energised motor winding at desired intervals to provide the low voltage power supply. The low voltage supply may be used in an appliance such as a laundry machine for supplying the motor control circuitry and auxiliary devices for example, a drainage pump and water supply control valves.

Claims

1. A method of producing a low voltage direct current for supplying a low voltage load from an electronically commutated motor system, which system comprises a high voltage direct current supply, a plurality of motor windings each having an inductance, and commutation switches which periodically connect said windings to said high voltage direct current supply to produce a current therein, said method comprising the steps of:

connecting at least one motor winding to said high voltage direct current supply;

diverting the current flowing through said at least one winding through said low voltage load using current diversion means;

controlling the current diversion means in accordance with the requirements of said low voltage load; and

providing a return path through said low voltage load so that current due to the winding inductance in said at least one winding will flow in said low voltage load whenever said high voltage direct current supply is disconnected from said at least one winding by one of said commutation switches.

2. A method as claimed in claim 1, which further includes the step of supplying some of said current flowing through said at least one winding to an energy storage means in electrical connection with said low voltage load so that power is substantially continuously supplied to said low voltage load.

3. A method as claimed in claim 1 or claim 2, which further includes the steps of:

sensing that power is required to be supplied to said low voltage load with sensing means; and

using activating means to activate said current diversion means if said sensing means indicate that power is not required to be supplied to said low voltage load and to deactivate said current diversion means if said sensing means indicate that power is required to be supplied to said low voltage load.

4. A method as claimed in claim 1 or claim 2, which includes the steps of controlling said commutation switches to energize and deenergize said at least one winding intermittently to commutate power to said electronically commutated motor system.

5. A method as claimed in claim 1 or claim 2, further including the step of using activating means to activate or deactivate said current diversion means to cause current flowing through said at least one winding to be diverted into said low voltage load on demand.

6. A method as claimed in claim 5, which further includes the step of supplying power to a control means, which controls said commutation switches and said activating means, such that said control means comprises part of said low voltage load.

7. A method as claimed in claim 5, which further includes the step of initially supplying power to a control means, which controls said commutation switches and said activating means, using a starting power supply means to start operation of said control means.

8. A method of producing a low voltage direct current for supplying a low voltage load in a laundry machine having a washing container, an agitator and a spin tub within said washing container, said agitator being connected so as to be rotated back and forth by an electronically commutated motor system and to be rotated with said spin tub when driven continuously in one direction, said electronically commutated motor system comprising a high voltage direct current supply, a plurality of motor windings each having an inductance, and commutation switches which periodically connect said windings to said high voltage direct current supply to produce a current therein, and said method comprising the steps of:

connecting at least one motor winding to said high voltage direct current supply;

diverting the current flowing through said at least one winding through said low voltage load using current diversion means;

controlling the current diversion means in accordance with the requirements of said low voltage load; and

providing a return path through said low voltage load so that current due to the winding inductance in said at least one winding will flow in said low voltage load whenever said high voltage direct current supply is disconnected from said at least one winding by one of said commutation switches.

9. An electronically commutated motor system which produces a low voltage direct current for supplying a low voltage load comprising:

a high voltage direct current supply;

a plurality of motor windings each having an inductance;

commutation switches which periodically connect said windings to said high voltage direct current supply to produce a current therein;

a series circuit in series with at least one of said windings which includes current diversion means and means in parallel with said current diversion means to supply said low voltage load;

activating means for activating and deactivating said current diversion means to cause current flowing through said at least one motor winding to be diverted into said low voltage load on demand; and

unidirectional current means connected across said at least one winding and said series circuit which allow current due to the winding inductance in said at least one winding to flow from said at least one winding through said series circuit when one of said commutation switches disconnects said at least one motor winding from said high voltage direct current supply.

10. A switched mode power supply as claimed in claim 9, wherein said means in parallel with said current diversion means includes a reservoir capacitor in parallel with said low voltage load so that power is substantially continuously supplied to said low voltage load.

11. A switched mode power supply as claimed in claim 9 or claim 10, including sensing means for sensing the power demanded by said low voltage load and supplying signals to said activating means to activate said current diversion means if said sensing means indicate that power is not required by said low voltage load and to deactivate said current diversion means if said sensing means indicate that power is required by said low voltage load.

12. A switched mode power supply as claimed in claim 9 or claim 10, further including control means to control said commutation switches to energize and de-energize said at least one winding intermittently to commutate power to said at least one winding.

13. A switched mode power supply as claimed in claim 12, wherein said control means, which include said commutation switches and said activating means, comprise part of said low voltage load.

14. A switched mode power supply as claimed in claim 9 or claim 10, including control means to control said power supply and starting means for providing an initial supply of power to said control means sufficient to allow said control means to cause said commutation switches to energize said at least one winding to supply power to said low voltage load.

15. A laundry machine having a washing container, an agitator and a spin tub within said washing container, said agitator being connected so as to be rotated back and forth by an electronically commutated motor system and to be rotated with said spin tub when driven continuously in one direction, wherein said electronically commutated motor system comprises:

a high voltage direct current supply;

a plurality of motor windings each having an inductance;

commutation switches which periodically connect said windings to said high voltage direct current supply to produce a current therein;

a series circuit in series with at least one of said windings which includes current diversion means and means in parallel with said current diversion means to supply said low voltage load;

activating means for activating and deactivating said current diversion means to cause current flowing through said at least one motor winding to be diverted into said low voltage load on demand; and

unidirectional current means connected across said at least one winding and said series circuit which allow current due to the winding inductance in said at least one winding to flow from said at least one winding through said series circuit when one of said commutation switches disconnects said at least one motor winding from said high voltage direct current supply.