Method for consuming regenerated power for elevators

• US 5,420,491 A
• Filed: 12/02/1992
• Issued: 05/30/1995
• Est. Priority Date: 12/02/1992
• Status: Expired due to Fees

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Yamada, Koji, Kanzaki, Yuji
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Masih, Karen
• Application Number:
  US07/984,648
• Time in Patent Office: 909 Days
• Field of Search: 318/727, 318/812, 318/376
• US Class Current: 318/727
• CPC Class Codes: B66B 1/30 effective on driving gear , e.g. acting on power electronics, on inverter or rectifier controlled motor
• CPC Class Codes: H02P 23/06 Controlling the motor in four quadrants

Abstract

An analog DC link bus voltage in an induction motor drive is converted to a digital DC link bus voltage so that if the DC link bus voltage exceeds an ON voltage threshold of a switch and this condition exists a holding time later, the switch closes, thereby allowing regenerated power in the DC link to be dissipated in a resistor connected across the DC link. And if the DC link bus voltage falls below an OFF voltage threshold and that condition exists a latching time later, the switch is opened so that no regenerated power may be dissipated through the resistor.

Claims

1. A method for dissipating power regenerated from an induction motor, comprising the steps of:

detecting the voltage on a DC bus linking an AC-to-DC converter to a DC-to-AC inverter that drives said motor, and providing a voltage signal indicative thereof;

filtering said voltage signal to provide a control signal when said voltage signal exceeds a predetermined ON threshold magnitude for a predetermined holding time and to cease providing said control signal when said DC link bus voltage falls below a predetermined OFF threshold magnitude for a predetermined latching time; and

connecting said voltage on said DC bus to a power dissipating resistor in response to said control signal.

2. Apparatus for dissipating regenerated power generated from an induction motor back through an inverter, comprising:

means for detecting the voltage on a DC bus linking an AC-to-DC converter to said inverter and providing a voltage signal indicative thereof;

a resistor;

a switch for connecting said resistor to said bus; and

a switch drive means, including a filter responsive to said voltage signal for closing said switch when said voltage signal exceeds a predetermined ON threshold magnitude for a predetermined holding time T_H, thereby causing the power in said DC link to be dissipated through said resistor and for opening said switch when said voltage signal falls below a predetermined OFF threshold magnitude for a predetermined latching time T_L such that no regenerated power is dissipated through said resistor.