Switch assembly, electric machine having the switch assembly, and method of controlling the same

• US 7,042,192 B2
• Filed: 03/16/2005
• Issued: 05/09/2006
• Est. Priority Date: 07/09/2003
• Status: Expired due to Fees

• Current Assignee: Regal Beloit America, Inc.
• Original Assignee: A. O. Smith Corporation
• Inventors: Mehlhorn, William L.
• Primary Examiner(s): IP, SHIK LUEN PAUL
• Application Number:
  US11/081,165
• Publication Number:
  US 20050156557A1
• Time in Patent Office: 419 Days
• Field of Search: 318/809, 318/798, 318/727, 318/799, 318/802, 318/785, 318/751, 318/781, 318/788, 318/779, 327/310, 327/110
• US Class Current: 318/806
• CPC Class Codes: F04D 15/0218 the condition being a liquid level or a lack of liquid supply
• CPC Class Codes: G01F 23/266 measuring circuits therefor
• CPC Class Codes: H02P 1/42 for starting an individual single-phase induction motor H02P27/04 takes precedence
• CPC Class Codes: H02P 1/44 by phase-splitting with a capacitor
• CPC Class Codes: H03K 17/08 Modifications for protecting switching circuit against overcurrent or overvoltage
• CPC Class Codes: H03K 17/292 in thyristor, unijunction transistor or programmable unijunction transistor switches
• CPC Class Codes: H03K 17/305 in thyristor switches
• CPC Class Codes: H03K 17/725 for ac voltages or currents H03K17/722, H03K17/735 take precedence

Abstract

A compressor having a winding circuit and a driven member being driven in part by a winding of the winding circuit. The compressor further includes an auxiliary circuit connected in a parallel relationship with the winding circuit. The auxiliary circuit has an auxiliary circuit element and an electronic switch assembly connected in a series relationship such that the electronic switch assembly controls the current through the auxiliary circuit element.

Claims

1. A compressor comprising:

a winding circuit comprising a winding;

a driven member driven in part by the winding;

an auxiliary circuit connected in a parallel relationship with the winding circuit, the auxiliary circuit comprising an auxiliary circuit element and an electronic switch assembly connected in a series relationship such tat the electronic switch assembly controls the current through the auxiliary circuit element, the electronic switch assembly comprising

an electronic switch, and

a controller connected to the electronic switch to control the electronic switch, the controller comprising a current sensor that senses a current through the electronic switch, a scalar that generates a threshold based on the sensed current, and decision logic that controls the electronic switch based on the sensed current and the threshold; and

wherein the scalar generates a threshold having a relation to the sensed current such that the decision logic detects when the sensed current flares.

2. A compressor as set forth in claim 1 wherein the current sensor comprises a resistor, wherein the scalar comprises a capacitor that charges to a voltage having a relation to the current through the resistor, the charged voltage having a relation to the threshold, and a switch that provides a signal to the decision logic when the voltage drop across the resistor is greater than the threshold.

3. A compressor as set forth in claim 1 wherein the auxiliary circuit element comprises a capacitor.

4. A compressor as set forth in claim 1 wherein the auxiliary circuit comprises first, second, and third circuits connected at a node, the first circuit comprising an auxiliary capacitor, the second circuit comprising an auxiliary winding, and the third circuit comprising the electronic switch assembly and the auxiliary circuit element connected in the series relationship, wherein the auxiliary circuit element comprises a boost capacitor.

5. A compressor as set forth in claim 4 wherein the driven member comprises a rotor coupled to a piston.

6. A compressor as set forth in claim 4 wherein the compressor is a hermetically sealed compressor comprising a housing, wherein the piston, rotor, winding, and auxiliary winding are supported within the housing, and wherein the auxiliary capacitor, boost capacitor, and electronic switch assembly are supported outside the housing.

7. A compressor as set forth in claim 1 wherein the electronic switch assembly further comprises a power supply connected to the controller, the power supply being configured to receive power from a power source and controllably power the controller, the power supply comprising a circuit clamp that obstructs power from powering the controller when the voltage of the received power is greater than a threshold, thereby preventing current through the auxiliary circuit element.

8. A compressor as set forth in claim 1 wherein the controller further comprises a generator that provides a signal, and wherein the decision logic controls the electronic switch further based on the generated signal.

9. A compressor as set forth in claim 8 wherein the electronic switch comprises a triac, and wherein the generated signal comprises a plurality of pulses.

10. A compressor comprising:

a winding circuit comprising a winding;

a driven member driven in part by the winding; and

an auxiliary circuit connected in a parallel relationship with the winding circuit, the auxiliary circuit comprising an auxiliary circuit element and an electronic switch assembly electrically connected in a series relationship such that the electronic switch assembly controls the current through the auxiliary circuit element, the electronic switch assembly comprising

a triac,

a pulse generator that provides a first signal comprising a plurality of pulses,

a current sensor that senses a current trough the switch, the current sensor providing a second signal based on the sensed current,

a timer that provides a third signal, and

decision logic connected to the pulse generator, the current sensor, the timer, and the triac, the decision logic generating a control signal that selectively controls the triac based on the first second, and third signals.

11. A compressor as set forth in claim 10 wherein the electronic switch assembly further comprises a circuit control comprising the current sensor and the timer, wherein the circuit control provides a fourth signal based on the second and third signals, and wherein the decision logic generates the control signal based on the first and fourth signals.

12. A compressor as set forth in claim 11 wherein the circuit control further comprises a voltage sense circuit comprising a sensor that senses the voltage across the triac.

13. A compressor as set forth in claim 12 wherein the pulses have a relation to the zero crossings of the sensed voltage.

14. A compressor as set forth in claim 11 wherein the circuit control comprises a delay preventing the opening of the triac during a second time period.

15. A compressor as set forth in claim 10 wherein the auxiliary circuit comprises first, second, and third circuits connected at a node, the first circuit comprising an auxiliary capacitor, the second circuit comprising an auxiliary winding, and the third circuit comprising the electronic switch assembly and the auxiliary circuit element connected in the series relationship, wherein the auxiliary circuit clement comprises a boost capacitor.

16. A compressor as set forth in claim 10 wherein the driven member comprises a rotor coupled to a piston.

17. A compressor as set forth in claim 16 wherein the compressor is a hermetically sealed compressor comprising a housing, wherein the piston, rotor, winding, and auxiliary winding are supported within the housing, and wherein the auxiliary capacitor, boost capacitor, and electronic switch assembly are supported outside the housing.

18. A compressor as set forth in claim 10 wherein the auxiliary circuit element comprises a capacitor.