REGULATED BOOTSTRAP POWER SUPPLY

• US 20130119965A1
• Filed: 07/30/2010
• Published: 05/16/2013
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Marvin, Daryl J., Millett, Steven M.
• Granted Patent: US 9,804,612 B2
• Time in Patent Office: Days
• US Class Current: 323/312
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H03K 17/567 Circuits characterised by the use of more than one type of semiconductor device, e.g. BIMOS, composite devices such as IGBT
• CPC Class Codes: H03K 17/6871 the output circuit comprising more than one controlled field-effect transistor
• CPC Class Codes: H03K 2217/0081 Power supply means, e.g. to the switch driver

Abstract

An exemplary power supply includes a low side switch and a high side switch. A driver controls operation of the high side switch. A bootstrap capacitor supplies power to the driver. An energy storage portion is in parallel with the bootstrap capacitor to provide control over whether a voltage of the bootstrap capacitor drops below a desired voltage. A voltage regulator is in parallel with the bootstrap capacitor for limiting current provided to the bootstrap capacitor and for regulating a voltage of the bootstrap capacitor.

Claims

1. A power supply, comprising:

a low side switch;

a high side switch;

a driver that controls operation of the high side switch;

a bootstrap capacitor that supplies power to the driver;

an energy storage portion in parallel with the bootstrap capacitor; and

a voltage regulator in parallel with the bootstrap capacitor for limiting current provided to the bootstrap capacitor and for regulating a voltage of the bootstrap capacitor.

2. The power supply of claim 1, wherein the energy storage portion comprises a second capacitor

3. The power supply of claim 2, wherein the second capacitor prevents a voltage of the bootstrap capacitor from dropping below a desired voltage until after the second capacitor voltage drops below the voltage of the bootstrap capacitor.

4. The power supply of claim 1, wherein the voltage regulator comprises a linear voltage regulator.

5. The power supply of claim 4, wherein the voltage regulator comprises a zener diode having a breakdown voltage selected so that the voltage source charges the bootstrap capacitor.

6. The power supply of claim 5, wherein the zener diode breakdown voltage is higher than a desired voltage of the bootstrap capacitor.

7. The power supply of claim 6, wherein the zener diode breakdown voltage is approximately 0.7 volts higher than the desired voltage of the bootstrap capacitor.

8. The power supply of claim 5, wherein the voltage regulator comprises a transistor having a base in series with the zener diode and wherein the transistor and the zener diode are in parallel with the bootstrap capacitor.

9. The power supply of claim 1, comprising a DC bus coupled with the low side switch and the high side switch such that the switches control power supply to the DC bus.

10. The power supply of claim 9, wherein the DC bus comprises a high voltage DC bus.

11. A method of controlling power supply from a bootstrap capacitor to a driver that controls a high side switch, comprising the steps of:

providing an energy storage in parallel with the bootstrap capacitor, the energy storage providing control over whether a voltage of the bootstrap capacitor drops below a desired voltage used to power the driver; and

regulating the voltage of the bootstrap capacitor using a linear regulator in parallel with the bootstrap capacitor.

12. The method of claim 11, comprising using the linear regulator for limiting an amount of current supplied to the bootstrap capacitor.

13. The method of claim 11, wherein the energy storage comprises a capacitor and the method comprises preventing the voltage of the bootstrap capacitor from dropping below the desired voltage until the energy storage capacitor voltage drops below the voltage of the bootstrap capacitor.

14. The method of claim 11, comprising using the high side switch for controlling power delivered to a DC bus.

15. The method of claim 14, wherein the DC bus comprises a high voltage DC bus.