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
2001-01-30
2002-08-27
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, C318S376000, C318S801000
Reexamination Certificate
active
06439347
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elevator control apparatus utilizing a power storage unit.
2. Description of the Related Art
A conventional elevator control apparatus will be described with reference to an accompanying drawing.
FIG. 19
shows a construction of a conventional elevator control apparatus disclosed, for example, under a title of “Redesigned medium-to-low speed passenger elevator, Grandy” on page 9 of Mitsubishi Denki Giho (written by Ando, Kimura, and Mori, Vol. 70, No. 11 issued in 1996).
The conventional elevator control apparatus shown in
FIG. 19
includes a commercial three-phase AC power source
1
, a motor
2
, such as an induction motor IM, a hoisting machine
3
, a rope
4
, an elevator car
5
, a counterweight
6
, an encoder
7
, a controller
8
, a converter
9
formed of a diode or the like, a capacitor
10
, a current detector
11
, such as a current transformer (CT), an inverter
12
, an inverter control circuit
13
, a gate drive circuit
14
, a regenerative resistor
15
, and a switching means
16
, such as an IGBT.
An operation of the aforesaid conventional elevator control apparatus will now be described with reference to the drawing.
The hoisting machine
3
is driven by the motor
2
to move the elevator car
5
and the counterweight
6
connected to both ends of the rope
4
, thereby carrying passengers in the car to a predetermined floor.
The converter
9
rectifies AC power supplied from the commercial power source
1
to convert it into DC power, which is stored in the capacitor
10
. The DC power is converted into AC power of a variable voltage and a variable frequency by the inverter
12
.
The controller
8
controls starts and stops of the elevator and also creates commands regarding start and stop positions and speed. Based on a speed command supplied by the controller
8
, the inverter control circuit
13
rotationally drives the motor
2
by reflecting current feedback from the current detector
11
and speed feedback from the encoder
7
mounted on the hoisting machine
3
, thereby implementing the position and speed control of the elevator. At this time, the inverter control circuit
13
controls output voltages and frequencies of the inverter
12
via the gate drive circuit
14
.
The counterweight
6
of the elevator is set such that it is balanced when the car
5
is loaded with a moderate number of passengers. For example, when the elevator travels in a balanced state, it is possible to increase the speed of the elevator while consuming electric power in an acceleration mode, and to turn accumulated speed energy back into electric power in a deceleration mode. In typical elevators, however, the regenerative electric power is consumed by being converted into heat energy by the regenerative resistor
15
by controlling the switching means
16
.
The conventional elevator control apparatus described above operates the elevator by constantly supplying electric power from the commercial power source. This has been posing a problem in that the electric power generated during a regenerative mode of the elevator is thermally consumed mainly by the regenerative resistor rather than being effectively used.
SUMMARY OF THE INVENTION
The present invention has been made with a view toward solving the foregoing problem, and it is an object of the present invention to provide an elevator control apparatus that permits energy saving by effectively utilizing electric power generated during a regenerative mode of an elevator.
To this end, according to one aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a required power computing circuit for computing required power of the elevator based on a speed command of the controller; a charge/discharge control circuit which conducts control by changing charge current, which is to be supplied to the power storage unit, based on regenerative electric power, and issues a drive signal for charging the power storage unit with the regenerative electric power if required power of the elevator is negative, that is, if the regenerative electric power is available; and a charge/discharge circuit for charging the power storage unit with the regenerative electric power in accordance with the drive signal.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a required power computing circuit for computing required power of the elevator based on a speed command of the controller; a charge/discharge control circuit which carries out control such that a bus voltage between the converter and the inverter stays constant at a preset voltage that is not less than a voltage obtained by rectifying the AC power, and issues a drive signal for charging the power storage unit with the regenerative electric power if required power of the elevator is negative, that is, if the regenerative electric power is available; and a charge/discharge circuit for charging the power storage unit with the regenerative electric power in accordance with the drive signal.
According to yet another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a required power computing circuit for computing required power of the elevator based on a speed command of the controller and issuing a regenerative operation signal if the required power is negative; a charge/discharge control circuit that starts charge control of regenerative electric power and issues a drive signal for charging the power storage unit with the regenerative electric power upon receipt of the regenerative operation signal; and a charge/discharge circuit for starting charging the power storage unit with the regenerative electric power in accordance with the drive signal.
According to still another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable frequency so as to operate an elevator; a power storage unit for storing the DC power; a charge/discharge control circuit that stops charge control of regenerative electric power and issues a drive signal for stopping charging the power storage unit with the regenerative electric power upon receipt of an elevator stop signal from the controller; and a charge/discharge circuit for stopping charging the power storage unit with the regenerative electric power in accordance with the drive signal.
According to a further aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of the variable voltage and the variable freque
Araki Hiroshi
Kobayashi Kazuyuki
Suga Ikuro
Tajima Shinobu
Leydig Voit & Mayer Ltd
Mitsubishi Denki & Kabushiki Kaisha
Salata Jonathan
LandOfFree
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