Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes control for power source of drive-means
Reexamination Certificate
1999-12-09
2001-07-24
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes control for power source of drive-means
C187S296000
Reexamination Certificate
active
06264005
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for an elevator car to perform an emergency operation at a state of emergency such as power failure, and in particular to a method for controlling a rescue operation of an elevator car which can rescue passengers by performing an emergency operation with an electric power generating of a permanent magnet-type synchronous motor when an emergency such as power failure takes place in an elevator system employing the synchronous motor as a lifting motor.
2. Description of the Background Art
When a permanent magnet-type synchronous motor is employed as a lifting motor in an elevator system, a permanent magnet is used as a magnetic field source, and thus a magnetic component current is not necessary. In addition, in general, the permanent magnet-type synchronous motor is more efficient than an induction motor, and accordingly improves efficiency of the whole elevator system and reduces energy consumption. Therefore, the permanent magnet-type synchronous motor has been used in the elevator system. In the elevator system using the permanent magnet-type synchronous motor as the lifting motor, a conventional apparatus for controlling an operation of an elevator car at a state of emergency, such as power failure, and a method therefor will now be described with reference to FIG.
1
.
As illustrated in
FIG. 1
, the conventional apparatus for controlling the operation of the elevator car (hereinafter referred to as ‘car’) includes: a converter
102
converting an alternating current from a three-phase alternating current power source
101
to a direct current; a condenser
103
charging and smoothing a direct current outputted from the converter
102
; an inverter
104
for inverting a direct current outputted from the condenser
103
to an alternating current by switching of a switching device; a synchronous motor
105
driven by an output from the inverter
104
; a contactor
105
A closed during the power failure for grounding a three-phase output terminal of the synchronous motor
105
through a ground resistance
105
B; a current detector
106
detecting a current supplied from the inverter
104
to the synchronous motor
105
; a speed and position detector (such as a rotary encoder outputting a pulse signal corresponding to a rotation speed of the synchronous motor) connected to the synchronous motor
105
, and detecting a rotation speed of the synchronous motor
105
and a moving position of the car
110
; a traction machine
108
receiving a rotation force from the synchronous motor
105
, and driving the car
110
and a balance weight
111
in opposite directions; a brake
109
of the traction machine
108
; a power failure detector
112
detecting a state where the three-phase alternating current power source
101
is abnormally inputted or interrupted; a controller
113
outputting a speed command driving the synchronous motor
105
during a normal operation, and outputting a corresponding speed command when the power failure or abnormality detection signal is outputted from the power failure detector
112
; an inverter controller
114
receiving an output signal from the current detector
106
and the speed and position detector
107
, and outputting a pulse width modulation signal according to a control command of the controller
113
; and a gate driving unit
115
receiving the pulse width modulation signal, amplifying it to a predetermined level, and outputting it to the inverter
104
. The operation of the conventional apparatus for controlling the operation of the elevator car will now be explained.
In the normal operation, the three-phase alternating current power source
101
is converted into the direct current through the converter
102
, and smoothed by the condenser
103
. The smoothed direct current is inputted into the inverter
104
.
In this state, when the controller
113
transmits the speed command to the inverter controller
114
, the inverter controller
114
outputs the pulse width modulation signal having a predetermined pattern which is a gate driving signal to the inverter
104
through the gate driving unit
115
. Accordingly, the switching devices in the inverter
104
are switched, and thus a three-phase driving voltage is supplied to the synchronous motor
105
.
The synchronous motor
105
rotates at a speed corresponding to the inputted three-phase driving voltage, the rotation force thereof is transmitted to the traction machine
108
, and thus the car
110
starts to move to a designated floor.
On the other hand, when the emergency such as the power failure is detected by the power failure detector
112
, and when the detection signal is inputted to the controller
113
, the driving of the inverter
104
is interrupted. At the same time, the brake
109
of the traction motor
108
is operated, and thus the car
110
stops at a current position. An auxiliary power source which is prepared for the emergency state such as the power failure, namely a battery (not shown) is supplied to the controller
113
, the contactor
105
A is closed according to the control of the controller
113
, and thus an output terminal of the synchronous motor
105
is connected to the ground through the contactor
105
A and the ground resistance
105
B.
In this state, when the brake
109
is released, the car
110
starts to move towards a heavier side between the car
110
and the balance weight
111
, and thus the synchronous motor
105
is rotated. Accordingly, a electric power is generated by the synchronous motor
105
, that is the synchronous motor
105
operates as a power generator. A generated current flows through the contactor
105
A and the ground resistance
105
B, and a braking torque is generated in the synchronous motor
105
.
Accordingly, in a state where the driving of the inverter stops, the car
110
moves at such a speed that the braking torque of the synchronous motor
105
and the torque by the weight difference between the car
110
and the balance weight
111
could be balanced. When the car
110
reaches to a door zone of the nearest floor, the brake
109
of the traction motor
108
is driven, and thus the movement of the car
110
stops. At this time, the door is opened, and the passengers are rescued.
However, the conventional apparatus for controlling the operation of the elevator car includes the contactor and the resistor in the circuit of synchronous motor and the inverter, and further includes a control circuit in order to short the output terminal of the synchronous motor to the ground by controlling the contactor during the emergency operation, thereby incurring additional expenses. Moreover, the operational speed of the car is determined merely by the weight difference between the car and the balance weight, and the ground resistance value. Accordingly, there is a disadvantage in that the operational speed is varied according to a load status of the car, namely the number of the passengers and cargo.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a method for controlling a rescue operation of an elevator car during a power failure by controlling a speed and a torque of a permanent magnet-type synchronous motor with an electricity generating power thereof, not by operating the car with a battery power and a balance of a braking torque and a torque by a weight difference between the car and a balance weight
It is another object of the present invention to provide a method for controlling a rescue operation of an elevator car during a power failure, without using a contactor and a ground resistance.
In order to achieve the above-described objects of the present invention, there is provided a method for controlling a rescue operation of an elevator car during a power failure by using an elevator system including: a rope; an elevator car connected to one end portion of the rope for transferring passengers or cargo; a balance car connected to the other end portion of the rope for keeping the balance
Han Gueon Sang
Kang Seog Joo
LG Industrial Systems Co. Ltd.
Salata Jonathan
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