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
2001-04-26
2002-10-29
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
06471013
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on Application No. 2000-342082 filed in Japan on Nov. 9, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an energy-saving type of elevator controller to which a secondary battery is applied.
2. Description of the Related Art
FIG. 7
is a diagram showing the system configuration of a conventional elevator controller.
The elevator controller shown in
FIG. 7
uses an ordinary utility power supply
1
for supplying a three-phase alternating current or the like, and an electric motor
2
, such as an induction motor. The electric motor
2
rotates to drive a hoist machine
3
, which moves, along a vertical direction, a car
5
and a counterweight
6
connected to two ends of a rope
4
to transport passengers in the car to a designated floor.
AC power supplied from the utility power supply
1
is rectified by a converter (CNV)
11
constituted of diodes, or the like, and converted into dc power. The dc power is supplied to a dc bus
9
. The dc power is converted into variable-voltage variable-frequency ac power by an inverter (INV)
15
constituted of ordinary transistors, insulated gate bipolar transistors (IGBTs), or the like.
A controller
8
constituted of a microcomputer, or the like, controls the entire elevator system. The controller
8
prepares elevator start and stop commands and elevator position and speed commands. An inverter control circuit
13
drives and rotates the electric motor
2
on the basis of information on current feedback from a current sensor
12
and speed feedback from a speed sensor
7
mounted on the hoist machine
3
and constituted of an encoder, or the like, and on the basis of commands from the controller
8
, thereby achieving position and speed control of the elevator. For this control, the inverter control circuit
13
controls the output voltage and output frequency of the inverter
15
through a gate drive circuit
14
.
The counterweight
6
of the elevator is set to a weight such as to be balanced with the car
5
with a moderate load (ordinarily half the rated load). Ordinarily, therefore, the operation is in a power-drive mode in which electric power is consumed when the car moves downward without a load, and in a regenerative mode in which kinetic energy is converted into electric power when the car moves upward without a load. Conversely, the operation is in the regenerative mode when the car moves downward with the rated load, and in the power-drive mode when the car moves upward with the rated load. In ordinary elevators, electric power regenerated in the regenerative mode is consumed by being converted into thermal energy in a regeneration resistor
16
controlled by a regeneration resistance control circuit
17
.
Ordinarily, an energy-saving type of elevator to which a secondary battery is applied has a power accumulator
21
using a lead-acid battery or a nickel metal hydride battery as a secondary battery, a charging and discharging circuit
22
constituted of a DC-DC converter, etc., a charging and discharging control circuit
23
for controlling electric power charged or discharged by the charging and discharging circuit
22
, and a required-power computation circuit
24
for computing necessary power for the elevator and controlling the charging and discharging control circuit
23
so that the power accumulator
21
is discharged to supply a deficiency in the necessary power not fully supplied from the utility power supply
1
.
In general, for the purpose limiting the size and price of the controller, the number of cell units of the secondary battery is set to a small number, so that the output voltage of the batteries is lower than the voltage of the dc bus
9
. The voltage of the dc bus
9
is ordinarily controlled so as to be maintained generally at a voltage obtained by the converter
11
rectifying the current from the utility power supply
1
. Therefore, it is necessary to increase the busside output voltage of the charging and discharging circuit
22
to the bus voltage during discharging of the battery, and to reduce the bus-side input voltage of the charging and discharging circuit
22
below the converter output voltage during charging of the battery. For this reason, a DC-DC converter is used as charging and discharging circuit
22
. Discharging gate and charging gate control of this DC-DC converter is performed by the charging and discharging control circuit
23
.
FIG. 8
is a block diagram showing an example of the above-described charging and discharging control circuit
23
.
The charging and discharging control circuit
23
shown in
FIG. 8
has a charging power control circuit comprised of a voltage controller
31
, a charging current controller
32
, a pulse-width modulation (PWM) signal circuit
33
, and a gate drive circuit
34
, and a discharging power control circuit comprised of a discharging current controller
41
, a PWM signal circuit
42
, a gate drive circuit
43
, and a divider
44
.
In the charging power control circuit, the voltage controller
31
computes, by proportional integration, for example, a deviation of a voltage feedback signal of the dc bus
9
from a voltage command from the controller shown in
FIG. 7
, and outputs the deviation as a charging current command value. The charging current controller
32
computes, by proportional integration, for example, a deviation of a current feedback signal from the current sensor
10
provided between the power accumulator
21
and the charging and discharging circuit
22
shown in
FIG. 7
from the charging current command from the voltage controller
31
, and outputs the deviation as a charging control command value. The PWM signal circuit
33
forms a control signal for PWM control of the charging and discharging circuit
22
comprised of a DC-DC converter on the basis of the charging control command value from the charging current controller
32
, and outputs the control signal. The gate drive circuit
34
controls the charging gate of the charging and discharging circuit
22
on the basis of the control signal from the PWM signal circuit
33
.
When electric power is regenerated from the electric motor
2
, the voltage of the dc bus
9
is increased by the regenerated electric power. When the voltage of the dc bus
9
becomes higher than the output voltage from the converter
11
, power supply from the utility power supply
1
is stopped. When the voltage of the dc bus
9
is further increased to reach a predetermined voltage, the polarity of the charging current command value from the voltage controller
31
is inverted and the power accumulator
21
is charged with the regenerated power under the control of the charging and discharging control circuit
23
.
On the other hand, in the discharging power control circuit, the divider
44
outputs, from the output of the required power computation circuit
24
, which computes the necessary power for the elevator, a discharging current command value so that the power accumulator
21
discharges and supplies the necessary power not fully supplied from the utility power supply
1
. That is, this discharging current command value is obtained by dividing a power deviation value by the battery voltage of power accumulator
21
. The power deviation value can be obtained from the utility power corresponding to the command value from the controller
8
designating the maximum supply of the utility power supply and the output power from the required power computation circuit
23
. The discharging current controller
41
computes, by proportional integration, for example, the difference between the discharging current command value and the current feedback signal from the current sensor
10
, which is connected between the power accumulator
21
and the charging and discharging circuit
22
, as shown in FIG.
7
. The discharging current controller
41
outputs the difference as a discharging control command value. The PWM signal circuit
42
Araki Hiroshi
Banno Hirokazu
Tajima Shinobu
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
Salata Jonathan
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