TECHNICAL FIELD
[0001] The present invention relates to an elevator control system that controls movement
of a car.
BACKGROUND ART
[0002] Conventionally, in order to prevent predetermined elevator components from becoming
overloaded, elevator control devices have been proposed that predict continuous temperature
conditions of the components by computation, and control elevator operation based
on those predicted temperature conditions. In these conventional elevators, elevator
operation is performed in a range in which component temperature limits will not be
exceeded, by switching between high-speed and low-speed speed patterns (See Patent
Literature 1).
DISCLOSURE OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
[0004] However, maximum speed and acceleration of the speed pattern are set low so as to
allow for detection errors, etc., in car internal load, for example. Consequently,
if elevator operation is performed in accordance with a speed pattern that has been
set low in this manner, the car is moved well below hoisting machine driving capacity,
and hoisting machine driving capacity cannot be utilized efficiently. Thus, elevator
operating efficiency deteriorates.
[0005] The present invention aims to solve the above problems and an object of the present
invention is to provide an elevator control system that can prevent temperature of
predetermined subject equipment that includes a driving machine from reaching an abnormally
high temperature, and that can also suppress deterioration of elevator operating efficiency.
MEANS FOR SOLVING THE PROBLEM
[0006] In order to achieve the above object, according to one aspect of the present invention,
there is provided an elevator control system including: a control apparatus that controls
supply of electric power to a motor of a driving machine that moves a car; and a temperature
signal generating apparatus that sends a temperature warning signal to the control
apparatus if a temperature of predetermined subject equipment that includes the driving
machine reaches a predetermined temperature reference value, the control apparatus
performing speed priority control in which a maximum value of rotational speed of
the motor is kept to a predetermined speed by passing a field weakening current to
the motor when receipt of the temperature warning signal is stopped, and performing
torque priority control in which a maximum value of rotational speed of the motor
is kept lower than the predetermined speed within a range in which output torque is
at a maximum relative to the supply of electric power of the motor by lowering the
field weakening current to the motor further than during the speed priority control
when the temperature warning signal is received.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007]
Figure 1 is a structural diagram that shows an elevator according to Embodiment 1
of the present invention;
Figure 2 is a flowchart for explaining decision operations of a speed limiting portion
from Figure 1;
Figure 3 is a graph that shows relationships between time and a speed command, acceleration
that corresponds to the speed command, a voltage command, a field weakening current,
presence or absence of a temperature warning signal, and presence or absence of a
speed limiting command, respectively, when output of a temperature warning signal
from a temperature signal generator from Figure 1 is stopped;
Figure 4 is a graph that shows relationships between time and a speed command, acceleration
that corresponds to the speed command, a voltage command, a field weakening current,
presence or absence of a temperature warning signal, and presence or absence of a
speed limiting command, respectively, when the temperature warning signal is output
from the temperature signal generator from Figure 1; and
Figure 5 is a flowchart for explaining a speed command calculating operation by a
speed command generating portion from Figure 1.
BEST MODE FOR CARRYING OUT THE INVENTION
[0008] Preferred embodiments of the present invention will now be explained with reference
to the drawings.
Embodiment 1
[0009] Figure 1 is a structural diagram that shows an elevator according to Embodiment 1
of the present invention. In the figure, a car 2 and a counterweight 3 are suspended
inside a hoistway 1 by a main rope 4. A hoisting machine (a driving machine) 5 for
moving the car 2 and the counterweight 3 is disposed in an upper portion of the hoistway
1. The hoisting machine 5 has: a motor 6; and a driving sheave 7 that is rotated by
the motor 6.
[0010] The motor 6 is constituted by a permanent magnet motor. The driving sheave 7 is rotated
by supplying electric power to the motor 6. The supply of electric power to the motor
6 is performed by a power converting device 8. The main rope 4 is wound around the
driving sheave 7. The car 2 and the counterweight 3 are moved inside the hoistway
1 by the rotation of the driving sheave 7.
[0011] A car operating panel 9 is disposed inside the car 2. A plurality of car call buttons
10 for performing call registration are disposed on the car operating panel 9. Landing
operating panels 11 are disposed on landings of respective building floors. A plurality
of landing call buttons 12 for performing call registration are disposed on the landing
operating panels 11.
[0012] A speed detector (an encoder, for example) 13 for detecting rotational speed of
the driving sheave 7 is disposed on the motor 6. A value for electric current that
is supplied to the motor 6 (motor current) from the power converting device 8 is detected
by an electric current detector (CT) 14 as a motor current value.
[0013] Electric power is supplied from a commercial power supply to the power converting
device 8 through a circuit breaker (not shown). Overcurrent to the power converting
device 8 is prevented by the circuit breaker. The power converting device 8 is constituted
by a pulse-width modulation (PWM) control inverter that adjusts output voltage by
generating a plurality of direct-current voltage pulses within a fundamental frequency
of an alternating-current voltage (bus voltage). In other words, output voltage of
the power converting device 8 is controlled by adjusting a voltage switching duty
ratio to the motor 6.
[0014] A temperature detector 15 is disposed on the motor 6. The motor 6 thereby constitutes
subject equipment for which temperature is measured by the temperature detector 15.
A predetermined temperature reference value is preset in the temperature detector
15. The temperature detector 15 outputs a temperature warning signal if the temperature
of the motor 6 reaches the predetermined temperature reference value, and stops outputting
of the temperature warning signal if the temperature of the motor 6 is lower than
the predetermined temperature reference value. In other words, the temperature detector
15 decides whether to not to output the temperature warning signal by comparing the
temperature of the motor 6 with the predetermined temperature reference value.
[0015] The temperature warning signal from the temperature detector 15 is captured by a
receiver 16. The temperature warning signal that has been captured by the receiver
16 is output without modification by the receiver 16. Moreover, a temperature signal
generating apparatus 17 includes the temperature detector 15 and the receiver 16.
[0016] Respective information from the car operating panel 9, the landing operating panels
11, the speed detector 13, the electric current detector 14, and the temperature signal
generating apparatus 17 is sent to a control apparatus 18 that controls elevator operation.
The control apparatus 18 controls the power converting device 8 based on the respective
information from the car operating panel 9, the landing operating panels 11, the speed
detector 13, the electric current detector 14, and the temperature signal generating
apparatus 17. Moreover, the control apparatus 18 performs computational processing
once every computational period ts.
[0017] The control apparatus 18 has a running control portion 19, a speed command generating
portion 20, a movement controlling portion 21, and a speed limiting portion 22.
[0018] The running control portion 19 prepares running management information for elevator
operation (information concerning destination floors and run commands, etc., for the
car 2, for example) based on respective information from the car operating panel 9
and the landing operating panels 11.
[0019] The speed command generating portion 20 finds a speed command for controlling speed
of the car 2 based on the running management information from the running control
portion 19.
[0020] The movement controlling portion 21 controls the supply of electric power to the
motor 6 based on the speed command from the speed command generating portion 20. The
movement of the car 2 is thereby controlled. Control of the supply of electric power
to the motor 6 is performed by the movement controlling portion 21 controlling the
power converting device 8. The movement controlling portion 21 has a speed controller
23 and an electric current controller 24.
[0021] The speed controller 23 finds a difference between the speed command from the speed
command generating portion 20 and information from the speed detector 13 concerning
the rotational speed as speed deviation information, and outputs the speed deviation
information that is found to the electric current controller 24.
[0022] The electric current controller 24 generates a control command that controls the
power converting device 8 based on both the speed deviation information from the speed
controller 23 and the information concerning the motor current from the electric current
detector 14. Specifically, the electric current controller 24 finds a motor current
target value based on the speed deviation information from the speed controller 23,
and controls the power converting device 8 such that the motor current value that
is detected by the electric current detector 14 matches the motor current target value.
[0023] An electric current command for adjusting the motor current that is supplied to the
motor 6, and a voltage command for adjusting the voltage that is imparted to the motor
6 are included in the control command. Information concerning the voltage switching
duty ratio to the motor 6 is also included in the voltage command.
[0024] Moreover, the bus voltage, the motor current value, an electric current command value,
a voltage command value, and the voltage switching duty ratio relative to the motor
6 of the power converting device 8 constitute driving information that corresponds
to the output from the motor 6, since they relate to output from the motor 6.
[0025] The speed limiting portion 22 can output a speed limiting command for suppressing
the rotational speed of the motor 6 to the speed command generating portion 20. The
speed limiting portion 22 receives information from the temperature signal generating
apparatus 17 (the temperature warning signal), information from the electric current
controller 24 (the voltage command), and information from the speed command generating
portion 20 (the speed command). The speed limiting portion 22 further decides whether
or not to output the speed limiting command based on the respective information from
the temperature signal generating apparatus 17, the electric current controller 24,
and the speed command generating portion 20. Specifically, the speed limiting portion
22 outputs the speed limiting command to the speed command generating portion 20 if
all conditions are satisfied, namely that the speed of the car 2 is increasing at
a constant acceleration, that the temperature warning signal is being received, and
that the value of the voltage command exceeds a preset limiting value Vlim (i.e.,
command output conditions), and stops outputting the speed limiting command when the
command output conditions are not satisfied.
[0026] Now, if a terminal voltage Vt of the motor 6 is high, the maximum voltage that can
be generated by the power converting device 8 may be exceeded, giving rise to distortion
in the motor voltage. As a result, noise may also be generated due to distortion also
arising in the motor current, and in the worst cases, the motor may also become uncontrollable.
Consequently, it is necessary to lower the terminal voltage Vt of the motor 6 to control
the rotational speed of the motor 6 at higher speeds.
[0027] Adjustment of the motor current is performed by adjusting an effective component
that generates torque (q-axis component), and a reactive component which does not
contribute to the generation of torque (d-axis component). A normal voltage equation
on the d-q coordinates of a permanent magnet motor can be expressed by Formula (1).
[0028]
[0029] Here, id and iq are d-axis and q-axis components of motor armature current, vd and
vq are d-axis and q-axis components of motor armature voltage, Ra is armature winding
resistance, ω is electrical angular speed, Ld and Lq are winding d-axis and q-axis
inductances, and ϕa is armature interlinked flux from the permanent magnets on the
d-q coordinates.
[0030] From Formula (1), the terminal voltage Vt of the motor 6 can be expressed by Formula
(2).
[0031]
[0032] From Formula (2), the terminal voltage Vt of the motor 6 can be lowered by passing
a negative d-axis electric current (a field weakening current). Consequently, the
maximum value of the rotational speed of the motor 6 can be increased by performing
control of the supply of electric power to the motor 6 while passing a field weakening
current to the motor 6 (i.e., performing field weakening control).
[0033] On the other hand, when a field weakening current is passed to the motor 6, power
factor of the motor 6 deteriorates. In other words, the electric current required
to generate identical torque is larger when performing field weakening control than
when not performing field weakening control. Consequently, heat that is generated
by the motor 6 is greater when performing field weakening control than when not performing
field weakening control.
[0034] A set speed maximum value Vmax that is calculated based on the running management
information is set to a speed that is achievable by the car 2 by performing field
weakening control on the motor 6. In other words, the set speed maximum value Vmax
that is based on the running management information is set to a speed that is unachievable
by the car 2 when field weakening control on the motor 6 is stopped.
[0035] The speed command generating portion 20 calculates a speed command that conforms
to the set speed that is based on the running management information when receipt
of the speed limiting command is stopped, and calculates a speed command that lowers
the maximum value of the speed of the car 2 below the set speed maximum value Vmax
that is based on the running management information when receiving the speed limiting
command. The speed command generating portion 20 calculates a speed command that stops
acceleration of the car 2 on receiving a speed limiting command.
[0036] When a speed command that conforms to the set speed is calculated, control of supply
of electric power to the motor 6 is field weakening control due to the speed of the
car 2 being within a predetermined range that includes the set speed maximum value
Vmax. On the other hand, a speed command that is calculated upon the speed command
generating portion 20 receiving a speed limiting command is a speed command that lowers
the field weakening current to maximize output torque relative to the supply of electric
power to the motor 6. In this example, a speed command that stops supply of the field
weakening current to the motor 6 is calculated by the speed command generating portion
20. On the speed command generating portion 20 receiving the speed limiting command,
accelerative operation of the car 2 is stopped, and the maximum value of the speed
of the car 2 becomes lower than the set speed maximum value Vmax.
[0037] In other words, when receipt of the temperature warning signal from the temperature
signal generating apparatus 17 is stopped, the control apparatus 18 performs speed
priority control in which a field weakening current is passed to the motor 6 to make
the maximum value of the rotational speed of the motor 6 a predetermined speed (i.e.,
a rotational speed value of the motor 6 that corresponds to the set speed maximum
value Vmax), and when the temperature warning signal is received, the control apparatus
18 performs torque priority control in which the field weakening current to the motor
6 is made lower than during speed priority control to make the maximum value of the
rotational speed of the motor 6 lower than the predetermined speed in a range in which
torque output from the motor 6 is at a maximum.
[0038] Next, operation will be explained. When call registration is performed, by operating
the car operating panel 9 or at least one of the landing operating panels 11, information
concerning the call registration is sent to the control apparatus 18. When a starting
command is subsequently input into the control apparatus 18, supply of electric power
to the motor 6 from the power converting device 8, and release of a brake that stops
rotation of the driving sheave 7 are performed by control from the control apparatus
18. Movement of the car 2 is thereby commenced. The speed of the car 2 is subsequently
adjusted by control of the power converting device 8 by the control apparatus 18,
and the car 2 is moved to the destination floor for which call registration was performed.
[0039] Next, operation of the control apparatus 18 will be explained. Whether or not to
output the speed limiting command is decided by the speed limiting portion 22 in the
control apparatus 18 based on the respective information from the temperature signal
generating apparatus 17, the electric current controller 24, and the speed command
generating portion 20.
[0040] When call registration information is input into the control apparatus 18, running
management information is prepared by the running control portion 19 based on the
call registration information. If receipt of the speed limiting command from the speed
limiting portion 22 by the speed command generating portion 20 is subsequently stopped,
a set speed that is found using a predetermined calculating formula based on the running
management information is calculated by the speed command generating portion 20 as
the speed command. If the speed command generating portion 20 receives the speed limiting
command from the speed limiting portion 22, a speed that is lower than the set speed
is calculated by the speed command generating portion 20 as the speed command. The
calculation of the speed command by the speed command generating portion 20 is performed
once every computational period ts.
[0041] The power converting device 8 is subsequently controlled by the movement controlling
portion 21 in accordance with the calculated speed command. The supply of electric
power to the motor 6 is thereby controlled such that the speed of the car 2 is controlled.
[0042] Next, decision operations of the speed limiting portion 22 will be explained. Figure
2 is a flowchart for explaining the decision operations of the speed limiting portion
22 from Figure 1. As shown in the figure, the speed limiting portion 22 decides whether
or not the car 2 is accelerating constantly based on the information from the speed
command generating portion 20 (S1). If the car 2 is not moving at a constant acceleration,
a decision is made to stop outputting the speed limiting command (S2).
[0043] If the car 2 is moving at a constant acceleration, the speed limiting portion 22
decides whether or not a temperature warning signal has been received based on the
information from the temperature signal generating apparatus 17 (S3). If a temperature
warning signal has not been received, a decision is made to stop outputting the speed
limiting command (S2).
[0044] If a temperature warning signal has been received, the speed limiting portion 22
decides whether or not the value of the voltage command has exceeded the limiting
value Vlim based on the information from the electric current controller 24 (S4).
If the voltage command value is less than or equal to the limiting value Vlim, a decision
is made to stop outputting the speed limiting command (S5). If, on the other hand,
the voltage command value has exceeded the limiting value Vlim, a decision is made
to output the speed limiting command (S6).
[0045] Next, a speed command by the speed command generating portion 20 when output of the
temperature warning signal from the temperature signal generating apparatus 17 has
been stopped will be explained. Figure 3 is a graph that shows relationships between
time and a speed command, acceleration that corresponds to the speed command, a voltage
command, a field weakening current, presence or absence of a temperature warning signal,
and presence or absence of a speed limiting command, respectively, when output of
a temperature warning signal from the temperature signal generator 17 from Figure
1 is stopped.
[0046] Moreover, in the figure, a state in which there is no input of the starting command
and the speed command is 0 (a rest state) has been designated MODE = 1, a state in
which acceleration > 0 and jerk > 0 has been designated MODE = 2, a state in which
acceleration > 0 and jerk = 0 has been designated MODE = 3, a state in which acceleration
> 0 and jerk < 0 has been designated MODE = 4, a state of constant speed has been
designated MODE = 5, a state in which acceleration < 0 and jerk < 0 has been designated
MODE = 6, a state in which the acceleration < 0 and jerk = 0 has been designated MODE
= 7, and a state in which acceleration < 0 and jerk > 0 has been designated MODE =
8. Furthermore, acceleration in MODE = 3 is assumed to be preset maximum acceleration
αa, and acceleration in MODE = 7 is assumed to be preset maximum deceleration αd.
[0047] In this case, as shown in Figure 3, the speed limiting portion 22 has decided to
stop outputting the speed limiting command in every MODE = 1 through 8. Consequently,
the speed command generating portion 20 does not receive a speed limiting command.
Thus, the set speed that is found by the preset calculating formula is calculated
as a speed command by the speed command generating portion 20 without modification.
In other words, the speed command that is calculated by the speed command generating
portion 20 is an unmodified value that has been calculated based on the running management
information, and is not limited by the decision of the speed limiting portion 22.
In this case, when the voltage command has exceeded the limiting value Vlim in MODE
= 3, control of the supply of electric power to the motor 6 is set to field weakening
control in order to raise the speed of the car 2 further.
[0048] Next, the speed command by the speed command generating portion 20 when the temperature
warning signal from the temperature signal generating apparatus 17 is being output
will be explained. Figure 4 is a graph that shows relationships between time and a
speed command, acceleration that corresponds to the speed command, a voltage command,
a field weakening current, presence or absence of a temperature warning signal, and
presence or absence of a speed limiting command, respectively, when the temperature
warning signal is output from the temperature signal generator 17 from Figure 1.
[0049] In this case, as shown in Figure 4, the speed limiting portion 22 outputs the speed
limiting command when the voltage command exceeds the limiting value Vlim in MODE
= 3. Thus, a speed command that is lower than the set speed that is based on the running
management information is calculated by the speed command generating portion 20. In
this case, field weakening control on the motor 6 is also stopped.
[0050] Next, the speed command calculating operation by the speed command generating portion
20 will be explained. Figure 5 is a flowchart for explaining a speed command calculating
operation by the speed command generating portion 20 from Figure 1. As shown in the
figure, the speed command generating portion 20 first decides whether or not a starting
command has been input into the control apparatus 18 (S11). If a starting command
has not been input, acceleration α is set to 0, the speed V to 0, and MODE to 1 (S12).
The speed command generating portion 20 subsequently calculates a speed command V
by substituting acceleration α = 0 and speed V = 0 into Formula (3) (S13).
[0051]
[0052] The speed command generating portion 20 subsequently outputs the calculated speed
command V to the speed controller 23 (S14), completing computation for the period
in question.
[0053] If a starting command has been input, the speed command generating portion 20 decides
whether or not MODE = 1 (S15). If MODE = 1, MODE is set to 2 because this is the first
computation after the starting command has been input. Here, acceleration α is set
using Formula (4), and also transition speed Va when transferring to MODE = 4 from
MODE = 3 is set using Formula (5) (S16).
[0054]
[0055] Here, j is jerk, and Vmax is the set speed maximum value.
[0056] Next, the speed command generating portion 20 calculates a new speed command V by
substituting the acceleration α and the speed command V from the previous computation
into Formula (3) (S13). The speed command generating portion 20 subsequently outputs
the calculated speed command V to the speed controller 23 (S14), completing computation
for the period in question.
[0057] If, on the other hand, MODE is not 1, the speed command generating portion 20 decides
whether or not MODE = 2 (S17). If MODE = 2, the speed command generating portion 20
decides whether or not the acceleration α is at the maximum acceleration αa (S18).
If not at the maximum acceleration αa, acceleration α is set using Formula (4), and
a transition speed Va is also set using Formula (5). Here, MODE = 2 is kept unchanged
(S16).
[0058] If the acceleration α is at the maximum acceleration αa, the acceleration α and the
transition speed Va are maintained without modification, and MODE is set to 3 (S19).
[0059] Next, the speed command generating portion 20 calculates a speed command V by substituting
the acceleration α and the speed command V from the previous computation into Formula
(3) (S13). The speed command generating portion 20 subsequently outputs the calculated
speed command V to the speed controller 23 (S14), completing computation for the period
in question.
[0060] If MODE is not 2, the speed command generating portion 20 decides whether or not
MODE = 3 (S20). If MODE = 3, the speed command generating portion 20 decides whether
or not either of the following is applicable: that the speed command V is the transition
speed Va; or that a speed limiting command has been received (S21). If neither is
applicable, the acceleration α and the transition speed Va are maintained, and MODE
= 3 is kept unchanged.
[0061] If it is applicable that either the speed command V is the transition speed Va or
the speed command generating portion 20 has received a speed limiting command, the
acceleration α is set using Formula (6), and MODE is set to 4 (S22).
[0062]
[0063] Next, the speed command generating portion 20 calculates a speed command V by substituting
the acceleration α and the speed command V from the previous computation into Formula
(3) (S13). The speed command generating portion 20 subsequently outputs the calculated
speed command V to the speed controller 23 (S14), completing computation for the period
in question.
[0064] If MODE is not 3, the speed command generating portion 20 decides whether or not
MODE = 4 (S23). If MODE = 4, the speed command generating portion 20 decides whether
or not the absolute value of the acceleration α is less than or equal to the absolute
value of the product of the jerk j and the computational period ts. In other words,
the speed command generating portion 20 decides whether or not Formula (7) is satisfied
(S24).
[0065]
[0066] If Formula (7) is not satisfied, the acceleration α is set using Formula (6), and
MODE = 4 is kept unchanged (S22). If Formula (7) is satisfied, the acceleration α
is set to 0, and MODE is set to 5 (S25).
[0067] Next, the speed command generating portion 20 calculates a speed command V by substituting
the acceleration α and the speed command V from the previous computation into Formula
(3) (S13). The speed command generating portion 20 subsequently outputs the calculated
speed command V to the speed controller 23 (S14), completing computation for the period
in question.
[0068] If MODE is not 4, the speed command generating portion 20 decides whether or not
MODE = 5 (S26). If MODE = 5, the speed command generating portion 20 decides whether
or not the car 2 is at a deceleration commencing position (S27). If the deceleration
commencing position has not been reached, the acceleration α is kept unchanged at
0, and MODE = 5 is kept unchanged (S25). If the deceleration commencing position has
been reached, the acceleration α is set using Formula (6), and MODE is set to 6 (S28).
[0069] Next, the speed command generating portion 20 calculates a speed command V by substituting
the acceleration α and the speed command V from the previous computation into Formula
(3) (S13). The speed command generating portion 20 subsequently outputs the calculated
speed command V to the speed controller 23 (S14), completing computation for the period
in question.
[0070] If MODE is not 5, the speed command generating portion 20 decides whether or not
MODE = 6 (S29). If MODE = 6, the speed command generating portion 20 decides whether
or not the acceleration α is at the maximum deceleration αd (S30). If not at the maximum
deceleration αd, the acceleration α is set using Formula (6), and MODE = 6 is kept
unchanged (S28). If at the maximum deceleration αd, the acceleration α is set to the
maximum deceleration αd, and MODE is set to 7 (S31).
[0071] Next, the speed command generating portion 20 calculates a speed command V by substituting
the acceleration α and the speed command V from the previous computation into Formula
(3) (S13). The speed command generating portion 20 subsequently outputs the calculated
speed command V to the speed controller 23 (S14), completing computation for the period
in question.
[0072] If MODE is not 6, the speed command generating portion 20 decides whether or not
MODE = 7 (S32). If MODE = 7, the speed command generating portion 20 decides whether
or not the car 2 is at a floor alignment commencing position (S33). If the floor alignment
commencing position has not been reached, the acceleration α is kept unchanged at
the maximum deceleration αd, and MODE = 7 is kept unchanged (S31). Next, the speed
command generating portion 20 calculates a speed command V by substituting the acceleration
α and the speed command V from the previous computation into Formula (3) (S13). The
speed command generating portion 20 subsequently outputs the calculated speed command
V to the speed controller 23 (S14), completing computation for the period in question.
[0073] If the floor alignment commencing position has been reached, the speed command generating
portion 20 calculates a speed command V based on distance to a floor alignment position
of the car 2, and MODE is set to 8 (S34). The speed command generating portion 20
subsequently outputs the calculated speed command V to the speed controller 23 (S14),
completing computation for the period in question.
[0074] In an elevator control system of this kind, because a temperature warning signal
is sent to a control apparatus 18 from a temperature signal generating apparatus 17
if the temperature of a motor 6 reaches a predetermined temperature reference value,
and the control apparatus 18 performs speed priority control in which a maximum value
of rotational speed of the motor 6 is set to a predetermined speed by field weakening
control over the motor 6 when receipt of the temperature warning signal is stopped,
and performs torque priority control by lowering a field weakening current to maximize
output torque relative to the supply of electric power to the motor 6 when receiving
the temperature warning signal, even if the temperature of the motor 6 increases and
reaches a high temperature, heat generation in the motor 6 can be suppressed efficiently
without lowering the maximum speed of the car 2 significantly. Consequently, the temperature
of the motor 6 can be prevented from reaching abnormally high temperatures, and deterioration
in the elevator operating efficiency can be suppressed.
[0075] Because a speed limiting portion 22 compares a voltage command and a limiting value
and outputs a speed limiting command to a speed command generating portion 20 if the
temperature warning signal has been received and the voltage command exceeds the limiting
value when the car 2 is accelerating, and the speed command generating portion 20
calculates a speed command that stops acceleration of the car 2 on receiving the speed
limiting command, a reactive current value that does not contribute to torque output
from the motor 6 can be reduced. Consequently, the temperature of the motor 6 can
be prevented from reaching abnormally high temperatures, and deterioration in the
elevator operating efficiency can be suppressed.
[0076] Moreover, in the above example, a voltage command is compared with a limiting value,
but is not limited to a voltage command, and any of the bus voltage of the power converting
device 8, a terminal voltage value of the motor 6, a motor current value that represents
a value of electric current to the motor 6, an electric current command value that
is output to the power converting device 8 from the control apparatus 18 in order
to adjust the motor current, or the voltage switching duty ratio to the motor 6 can
also be compared with a limiting value. Because any of this information constitutes
a deciding indicator as to whether or not the terminal voltage of the motor 6 is saturated
compared to the bus voltage, operation in which the reactive current value is reduced
can be performed by comparing this information with the limiting value and deciding
whether or not to output the speed limiting command. Consequently, the temperature
of the motor 6 can be prevented from reaching abnormally high temperatures, and deterioration
in the elevator operating efficiency can be suppressed.
[0077] in the above example, the subject equipment for which the temperature detector 15
measures the temperature is the motor 6, but is not limited to the motor 6, and because
it may be any equipment that generates heat due to the supply of electric power by
the power converting device 8, the power converting device 8 or the speed detector
13, etc., may also be designated as subject equipment, for example.
[0078] In the above example, the temperature of the motor 6 is measured directly by the
temperature detector 15, but the temperature of the motor 6 may also be estimated
based on temporal changes in the electric current that has been detected by the electric
current detector 14. In other words, a temperature estimator that estimates the temperature
of the motor 6 based on the temporal changes in the electric current to the motor
6, and that outputs a temperature warning signal to the speed limiting portion 22
if the estimated temperature of the motor 6 reaches the predetermined temperature
reference value may also be connected to the electric current detector 14.