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
2001-02-21
2002-07-09
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
06415892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a controller of an elevator of an energy saving type to which a secondary battery such as a nickel hydrogen battery, a nickel cadmium battery, a lithium ion battery, etc. is applied.
2. Description of the Related Art
FIG. 4
is a view showing the basic construction of a controller for controlling the operation of an elevator by applying a conventional secondary battery thereto.
In
FIG. 4
, reference numerals
1
and
2
respectively designate a three-phase AC power source and a converter constructed by a diode, etc. and converting AC power outputted from the three-phase AC power source
1
to DC power. The DC power converted by the converter
2
is supplied to a DC bus
3
. The operation of an inverter
4
is controlled by a speed controller for controlling a speed position of the elevator and described later. A direct current supplied through the DC bus
3
is converted to an alternating current of predetermined desirable variable voltage and variable frequency and an AC motor
5
is driven so that a hoisting machine
6
of the elevator directly connected to the AC motor
5
is rotated. Thus, a rope
7
wound around the hoisting machine
6
controls elevating and lowering operations of a car
8
and a counterweight
9
connected to both ends of this rope
7
and passengers within the car
8
are moved to a predetermined stage floor.
Here, weights of the car
8
and the counterweight
9
are designed such that these weights are approximately equal to each other when passengers half a number limit ride in the car
8
. Namely, when the car
8
is elevated and lowered with no load, a power running operation is performed at a lowering time of the car
8
and a regenerative operation is performed at a elevating time of the car
8
. Conversely, when the car
8
is lowered in the number limit riding, the regenerative operation is performed at the lowering time of the car
8
and the power running operation is performed at the elevating time of the car
8
.
An elevator control circuit
10
is constructed by a microcomputer, etc., and manages and controls an entire operation of the elevator. A power accumulating device
11
is arranged between DC buses
3
and accumulates power at the regenerative operation time of the elevator, and supplies the accumulated power to the inverter
4
together with the converter
2
at the power running operation time. The power accumulating device
11
is constructed by a secondary battery
12
and a DC—DC converter
13
for controlling charging and discharging operations of this secondary battery
12
.
Here, the DC—DC converter
13
has a voltage lowering type chopper circuit and a voltage raising type chopper circuit. The voltage lowering type chopper circuit is constructed by a reactor
13
a
, a gate
13
b
for charging current control connected in series to this reactor
13
a
, and a diode
13
c
connected in reverse parallel to a gate
13
d
for discharging current control described later. The voltage raising type chopper circuit is constructed by the reactor
13
a
, the gate
13
d
for discharging current control connected in series to this reactor
13
a
, and a diode
13
e
connected in reverse parallel to the above gate
13
b
for charging current control operations of the gate
13
b
for charging current control and the gate
13
d
for discharging current control are controlled by a charging-discharging control circuit
15
on the basis of a measuring value from a charging-discharging state measuring device
14
for measuring charging and discharging states of the power accumulating device
11
and a measuring value from a voltage measuring instrument
18
. A current measuring instrument arranged between the secondary battery
12
and the DC—DC converter
13
is used as the charging-discharging state measuring device
14
in this conventional example.
A gate
16
for regenerative current control and a regenerative resistor
17
are arranged between DC buses
3
. The voltage measuring instrument
18
measures the voltage of a DC bus
3
. A regenerative control circuit
19
is operated on the basis of regenerative control commands from a speed control circuit described later. The gate
16
for regenerative current control is constructed such that an ON pulse width is controlled on the basis of control of the regenerative control circuit
19
when a measuring voltage provided by the voltage measuring instrument
17
is equal to or greater than a predetermined value at the regenerative operation time. Regenerated power is discharged in the regenerative resistor
17
and is converted to thermal energy and is consumed.
An encoder
20
is directly connected to the hoisting machine
6
. The speed control circuit
21
controls a position and a speed of the elevator by controlling an output voltage and an output frequency of the inverter
4
on the basis of speed commands and a speed feedback output from the encoder
22
based on commands from the elevator control circuit
10
.
An operation of the controller having the above construction will next be explained.
At a power running operation time of the elevator, power is supplied to the inverter
4
from both the three-phase AC power source
1
and the power accumulating device
11
. The power accumulating device
11
is constructed by the secondary battery
12
and the DC—DC converter
13
, and an operation of this power accumulating device
11
is controlled by the charging-discharging control circuit
15
. In general, the number of secondary batteries
12
is reduced as much as possible and an output voltage of each secondary battery
12
is lower than the voltage of the DC bus
3
so as to make the controller compact and cheaply construct the controller. The voltage of the DC bus
3
is basically controlled near a voltage provided by rectifying a three-phase AC of the three-phase AC power source
1
. Accordingly, it is necessary to lower the bus voltage of the DC bus
3
at a charging time of the secondary battery
12
and raise the bus voltage of the DC bus
3
at a discharging time of the secondary battery
12
. Therefore, the DC—DC converter
13
is adopted. Operations of the gate
13
b
for charging current control and the gate
13
d
for discharging current control in this DC—DC converter
13
are controlled by the charging-discharging control circuit
15
.
FIGS. 5 and 6
are flow charts showing controls of the charging-discharging control circuit
15
at its discharging and charging times.
The control of the charging-discharging control circuit
15
at the discharging time shown in
FIG. 5
will first be explained.
A current control minor loop, etc. are constructed in voltage control of a control system and the control operation may be more stably performed. However, for simplicity, the control of the charging-discharging control circuit
15
is here explained by a control system using the bus voltage.
First, the bus voltage of the DC bus
3
is measured by the voltage measuring instrument
17
(step S
11
). The charging-discharging control circuit
15
compares this measuring voltage with a predetermined desirable voltage set value and judges whether the measuring voltage exceeds the voltage set value or not (step S
12
). If no measuring voltage exceeds the set value, the charging-discharging control circuit
15
next judges whether the measuring value of a discharging current of the secondary battery
12
provided by the charging-discharging state measuring device
14
exceeds a predetermined value or not (step S
13
).
When the measuring voltage exceeds the set value by these judgments, or when the measuring value of the discharging current of the secondary battery
12
exceeds the predetermined value even if no measuring voltage exceeds the set value, an adjusting time DT is subtracted from the present ON time to shorten an ON pulse width of the gate
13
d
for discharging current control and a new gate ON time is calculated (step S
14
).
In contrast to this, when it is judged in the above step S
13
that no mea
Araki Hiroshi
Kobayashi Kazuyuki
Suga Ikuro
Tajima Shinobu
Mitsubishi Denki & Kabushiki Kaisha
Salata Jonathan
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