Elevator drive fault detector

• US 5,765,664 A
• Filed: 01/30/1997
• Issued: 06/16/1998
• Est. Priority Date: 10/05/1995
• Status: Expired due to Fees

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Zemke, Wolfgang, Herkel, Peter, Blechschmidt, Gunter
• Primary Examiner(s): NAPPI, ROBERT E
• Application Number:
  US08/791,693
• Time in Patent Office: 502 Days
• Field of Search: 187/289, 187/277, 187/393, 187/391, 318/801, 361/31
• US Class Current: 187/393
• CPC Class Codes: B66B 5/0018 Devices monitoring the operating condition of the elevator system
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: H02H 7/0844 Fail safe control, e.g. by comparing control signal and controlled current, isolating motor on commutation error

Abstract

An elevator drive fault detector for detecting operational faults in an elevator drive having an inverter and only one circuit breaker includes a current sensor, a monitoring device, a control device and an operational control system. The current sensor provides a current sensor signal. The monitoring device determines if an operational fault exists in response to the current sensor signal and provides an operational signal. The monitoring device disables the operational signal if the monitoring device determines that an operational fault exists or if the elevator drive fault detector performs a system check operation. The operational control system provides both the run command and an operational check signal and is responsive to the operational signal such that if the operational signal is disabled then the operational control system opens the one circuit breaker and disables the run command such that the control device disables a PWM signal. If the operational signal was disabled during a system check operation then the operational control provides the operational check signal to the monitoring device such that if the monitoring device does not receive the operational check signal within a predetermined time then the monitoring device continues to disable the operational signal and the drive is elevator shutdown.

Claims

1. An elevator drive fault detector for detecting faults in an elevator drive having an inverter and a circuit breaker, said elevator drive fault detector comprising:

a current sensor for providing a current sensor signal indicative of an input current of the inverter;

a monitoring device for determining if a fault exists in response to the current sensor signal and for providing an operational signal, said monitoring device disables the operational signal if said monitoring device determines that a fault exists or if said elevator drive fault detector performs a system check operation;

a control device for controlling a PWM signal to the inverter in response to a run command; and

an operational control system for providing the run command and for controlling the circuit breaker in response to the operational signal such that if the operational signal is disabled said operational control system opens the circuit breaker and disables the run command so that electric power to the motor is interrupted and the elevator drive is shutdown.

2. The elevator drive fault detector as recited in claim 1 wherein said control device disables the PWM signal in response to the disabled run command.

3. The elevator drive fault detector as recited in claim 1 wherein if the operational signal was disabled during the system check operation then said operational control provides an operational check signal to said monitoring device such that if said monitoring device does not receive the operational check signal within a predetermined time then said monitoring device continues to disable the operational signal and the drive is elevator shutdown.

4. The elevator drive fault detector as recited in claim 3 wherein said control device disables the PWM signal in response to the disabled run command.

5. A method for fault detection of an elevator drive having a circuit breaker, said method comprising the steps of:

providing a current signal to a monitoring device, the current signal being indicative of an input current of an inverter of the elevator drive;

providing an operational signal to an operation control system in response to the current signal, the operational signal being indicative of a normal operating condition;

determining if a fault exists based upon the current signal;

disabling the operational signal in response to determining that a fault exists in said determining step;

opening the circuit breaker in response to said disabling step;

disabling the operational signal during a system check operation;

checking for an operational check signal provided by the operational control system in response to the disabling step;

enabling the operational signal in response receiving the operational check signal;

resuming normal operation in response to receiving the operation check signal; and

performing a drive shutdown in response to not receiving the operation check signal.

6. A method for determining the integrity of an elevator drive fault protection device of an elevator drive having a circuit breaker, said method comprising the steps of:

providing a current signal to a monitoring device, the current signal being indicative of an input current of an inverter of the elevator drive;

providing an operational signal to an operation control system in response to the current signal, an enabled operational signal being indicative of a normal operating condition and a disabled operational signal being indicative of a fault condition;

disabling the operational signal during a system check operation;

waiting for an operational check signal provided by the operational control system to the monitoring device in response to said disabling the operational signal step;

enabling the operational signal in response to the operational check signal provided by the operational control system; and

performing a drive shutdown in response to not receiving the operation check signal, wherein said shutdown includes maintaining the operational signal disabled and opening the circuit breaker of the elevator drive.