MOTOR START CIRCUIT

• US 20080018293A1
• Filed: 07/11/2007
• Published: 01/24/2008
• Est. Priority Date: 07/19/2006
• Status: Active Grant

• Current Assignee: Secop GmbH (Nidec Corporation)
• Original Assignee: Danfoss Compressors, Spol. S R.O. (AURELIUS Equity Opportunities SE & Co. KGaA)
• Inventors: Schmidt, Claus, Kristensen, Hans Peter
• Granted Patent: US 7,777,438 B2
• Time in Patent Office: Days
• US Class Current: 318/786
• CPC Class Codes: H02P 1/445 by using additional capacitors switched at start up

Abstract

Motor start circuit for an induction motor, particularly a single phase AC induction motor, with a main winding (4) and an auxiliary winding (5) having two end connections (6, 7) supplied with current, mainly AC, via current supply connections (34, 35), and with a start circuit device (15) serving the purpose of stopping the current flow through the auxiliary winding (5) after the start of the motor, and being connected via a conductor (18) to a control device (20) connected between the current supply connections (34, 35), and with a preset timer device interacting with the start circuit device (15) to stop the current flow through the auxiliary winding (5), as soon as a predetermined period after the start of the current flow has lapsed. With the purpose of optimising the motor start circuit, a voltage presetting device (60), with which a predetermined voltage value can be set, the start circuit device (15) being disconnected if this value is exceeded, and a period duration presetting device (70), by means of which the predetermined period can be set, after the lapse of which the start circuit device (15) is turned off by means of the control device (20), are connected to or integrated in the control device (20).

Claims

1. A motor start circuit for an induction motor, particularly a single phase AC induction motor, with a main winding and an auxiliary winding having two end connections supplied with current, mainly AC, via current supply connections, and with a start circuit device serving the purpose of stopping the current flow through the auxiliary winding after the start of the motor, and being connected via a conductor to a control device connected between the current supply connections, and with a preset timer device interacting with the start circuit device to stop the current flow through the auxiliary winding, as soon as a predetermined period after the start of the current flow has lapsed, wherein a voltage presetting device, with which a predetermined voltage value can be set, the start circuit device being disconnected if this value is exceeded, and a period duration presetting device, by means of which the predetermined period can be set, after the lapse of which the start circuit device is turned off by means of the control device, are connected to or integrated in the control device.

2. The motor start circuit according to claim 1, wherein the voltage presetting device comprises at least two resistors.

3. The motor start circuit according to claim 1, wherein the period duration presetting device comprises at least one resistor and/or a capacitor.

4. The motor start circuit according to claim 1, wherein the motor start circuit comprises a control circuit, in which the two end connections of the auxiliary winding are connected to the control device.

5. The motor start circuit according to claim 1, wherein a first end connection of the auxiliary winding is connected to a first current supply connection and the control device via at least one conductor.

6. The motor start circuit according to claim 1, wherein the first end connection of the auxiliary winding and the first current supply connection are connected to the control device via a conductor.

7. The motor start circuit according to claim 6, wherein a further conductor branches off from the conductor, said further conductor being connected to the control device and comprising a resistor of the voltage presetting device.

8. The motor start circuit according to claim 1, wherein a second end connection of the auxiliary winding is connected to the control device via at least one conductor.

9. The motor start circuit according to claim 8, wherein a further conductor branches off from the conductor, said further conductor being connected to the second current supply connection and comprising an run capacitor.

10. The motor start circuit according to claim 8 wherein a further conductor branches off from the conductor, said further conductor being connected to the second current supply connection and comprising a series connection of a start capacitor and the start circuit device.

11. The motor start circuit according to claim 8, wherein a further resistor of the voltage presetting device is located in the conductor.

12. A circuit board with a motor start circuit according to claim 1.

13. The circuit board according to claim 12, wherein the circuit board comprises a programmable chip.

14. A method for starting an induction motor, in particular a single phase AC induction motor, with a motor start circuit according to claim 1, wherein the predetermined voltage value is preset by means of the voltage presetting device and the predetermined period duration is preset by means of the period duration setting device.

15. The method according to claim 14, wherein the voltage over the auxiliary winding is monitored by means of the control device.

16. The method according to claim 15, wherein the start circuit device is turned off by means of the control device, as soon as the voltage over the auxiliary winding exceeds the predetermined value.

17. The method according to claim 16, wherein the predetermined voltage value is between 100 and 1000 Volts, in particular between 400 and 600 Volts.

18. The method according to claim 16 wherein the start circuit device is turned off by means of the control device, as soon as the predetermined period duration after the beginning of the current flow has lapsed and the voltage over the auxiliary winding has not exceeded the predetermined value.

19. The method according to claim 18, wherein the predetermined period duration is between 1 and 10 seconds, in particular between 2 and 6 seconds.