Abstract:
This invention provides a controller of an elevator for reducing the number of execution times of uniform charging of a power accumulating device and having higher energy saving effects. Therefore, the controller has a converter  2,  an inverter  4,  a power accumulating device  11  arranged between DC buses  3,  a charging-discharging control circuit  15 A for controlling charging and discharging operations of the power accumulating device, and a charging-discharging state measuring device  14 A for measuring at least one of a temperature, charging and discharging currents, and charging and discharging voltages of the power accumulating device. The charging-discharging control circuit  15 A sets the execution of uniform charging of the power accumulating device on the basis of an output of the charging-discharging state measuring device, and executes only the required uniform charging. Thus, an elevator with the power accumulating device having larger energy saving effects is constructed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a controller of an elevator of an energy saving type to which a secondary battery is applied.  
           [0003]    2. Description of the Related Art  
           [0004]    [0004]FIG. 11 is a view showing the basic construction of a controller for controlling the operation of an elevator by applying a conventional secondary battery thereto.  
           [0005]    In FIG. 11, 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.  
           [0006]    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 .  
           [0007]    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 .  
           [0008]    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.  
           [0009]    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.  
           [0010]    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 .  
           [0011]    An operation of the controller having the above construction will next be explained.  
           [0012]    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 .  
           [0013]    [0013]FIGS. 12 and 13 are flow charts showing controls of the charging-discharging control circuit  15  at its discharging and charging times.  
           [0014]    The control of the charging-discharging control circuit  15  at the discharging time shown in FIG. 12 will first be explained.  
           [0015]    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.  
           [0016]    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 ).  
           [0017]    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 ).  
           [0018]    In contrast to this, when it is judged in the above step S 13  that no measuring value of the discharging current of the secondary battery  12  provided by the measuring device  14  exceeds the predetermined value, a new gate ON time is calculated by adding the adjusting time DT to the present ON time so as to lengthen the ON pulse width of the gate  13   d  for discharging current control (step S 15 ). Thus, ON control of the gate  13   d  for discharging current control is performed on the basis of the calculated gate ON time, and the calculated gate ON time is stored to a built-in memory as the present ON time (step S 16 ).  
           [0019]    Thus, a more electric current flows from the secondary battery  12  by lengthening the ON pulse width of the gate  13   d  for discharging current control. As a result, supply power is increased and the bus voltage of the DC bus  3  is increased by the power supply. When the power running operation is considered, the elevator requires the power supply and this power is supplied by discharging from the above secondary battery  12  and power supply from the three-phase AC power source  1 . When the bus voltage is controlled such that this bus voltage is higher than an output voltage of the converter  2  supplied from the three-phase AC power source  1 , all power is supplied from the secondary battery  12 . However, the controller is designed such that all power is not supplied from the secondary battery  12 , but is supplied from the secondary battery  12  and the three-phase AC power source  1  in a suitable ratio so as to cheaply construct the power accumulating device  11 .  
           [0020]    Namely, in FIG. 12, the measuring value of the discharging current is compared with a supply allotment corresponding current (predetermined value). If this measuring value exceeds the predetermined value, the ON pulse width of the gate  13   d  for discharging current control is lengthened and a supply amount is further increased. In contrast to this, when no measuring value of the discharging current exceeds the predetermined value, the ON pulse width of the gate  13   d  for discharging current control is shortened and the power supply is clipped. Thus, since power supplied from the secondary battery  12  is clipped among power required in the inverter  4 , the bus voltage of the DC bus  3  is reduced so that the power supply from the converter  2  is started. These operations are performed for a very short time so that a suitable bus voltage is actually obtained to supply required power of the elevator. Thus, power can be supplied from the secondary battery  12  and the three-phase AC power source  1  in a predetermined desirable ratio.  
           [0021]    The control of the charging-discharging control circuit  15  at the charging time shown in FIG. 13 will next be explained.  
           [0022]    When there is power regeneration from the AC motor  5 , the bus voltage of the DC bus  3  is increased by this regenerated power. When this voltage is higher than an output voltage of the converter  2 , the power supply from the three-phase AC power source  1  is stopped. When there is no power accumulating device  11  and this stopping state is continued, the voltage of the DC bus  3  is increased. Therefore, when a measuring voltage value of the voltage measuring instrument  17  for detecting the bus voltage of the DC bus  3  reaches a certain predetermined voltage, the regenerative control circuit  19  is operated and closes the gate  16  for regenerative current control. Thus, power flows through the regenerative resistor  17  and the regenerated power is consumed and the elevator is decelerated by electromagnetic braking effects. However, when there is the power accumulating device  11 , this power is charged to the power accumulating device  11  by the control of the charging-discharging control circuit  15  with a voltage equal to or smaller than a predetermined voltage.  
           [0023]    Namely, as shown in FIG. 13, if the measuring value of the bus voltage of the DC bus  3  provided by the voltage measuring instrument  17  exceeds the predetermined voltage, the charging-discharging control circuit  15  detects that it is a regenerative state, and increases a charging current to the secondary battery  12  by lengthening the ON pulse width of the gate  13   b  for charging current control (step S 21 →S 22 →S 23 ). When the regenerated power from the elevator is reduced in a short time, the voltage of the DC bus  3  is also correspondingly reduced and no measuring value of the voltage measuring instrument  17  exceeds the predetermined voltage. Accordingly, the ON pulse width of the gate  13   b  for charging current control is shortly controlled and charging power is also reduced and controlled (step S 21 →S 22 →S 24 ).  
           [0024]    Thus, the bus voltage is controlled in a suitable range and a charging operation is performed by monitoring the bus voltage of the DC bus  3  and controlling the charging power. Further, energy is saved by accumulating and re-utilizing power conventionally consumed in the regenerated power.  
           [0025]    For example, the power accumulating device  11  executes uniform charging of the secondary battery  12  once per one day in the nighttime, etc.  
           [0026]    [0026]FIG. 14 is an explanatory view showing the uniform charging in which a charging current is shown on an axis of ordinate and a passing time is shown on an axis of abscissa. Since this uniform charging requires a long time, the uniform charging is generally executed when a traffic flow is small as in the nighttime, etc. The uniform charging utilizes that a charging voltage is raised together with an increase in a charging SOC (State Of Charge) as a value obtained by normalizing and accumulating a product of a charging-discharging current and a charging-discharging voltage by a capacity with a full charging state of the power accumulating device  11  as a reference even when the secondary battery is charged by the same charging current. The secondary battery is charged by a constant current and charging until a terminal voltage for terminating this constant current charging is performed at stages shown in FIG. 14.  
           [0027]    Namely, in the uniform charging, as shown in FIG. 14, the constant current charging is first executed by a charging current A 1 . The charging current is reduced to A 2  after a time t 1  at which the voltage of the secondary battery  12  is raised to a first terminal voltage although this time depends on a temperature, etc., during the charging. The charging is further executed. After a time t 2  at which the voltage of the secondary battery  12  is raised until a second terminal voltage in the same current, the charging is performed slightly excessively by a low current for a constant time until a time t 3 .  
           [0028]    A charging reception property of the secondary battery  12  is improved in this uniform charging. Further, when the secondary battery  12  is constructed by plural batteries, there is a merit in that the dispersion between the respective batteries is uniformed, etc. However, just after the uniform charging, the excessive charging is performed by the uniform charging and a SOC level is high. Therefore, there is a bad influence of a reduction in energy saving effects such as a reduction in reception property of regenerative power of the elevator.  
         SUMMARY OF THE INVENTION  
         [0029]    To solve the above problems, this invention provides a controller of an elevator for reducing the number of executing times of uniform charging and providing higher energy saving effects by monitoring a state of a power accumulating device. To achieve this object, a controller of an elevator in this invention comprises a converter for rectifying AC power from an AC power source and converting the AC power to DC power; an inverter for converting the DC power from the converter to AC power of a variable voltage and a variable frequency and driving an electric motor and operating the elevator; a power accumulating device arranged between DC buses between the converter and the inverter, and accumulating DC power from the DC buses at a regenerative operation time of the elevator, and supplying the accumulated DC power to the DC buses at a power running operation time; charging-discharging control means for controlling charging and discharging operations of the power accumulating device with respect to the DC buses; and charging-discharging state measuring means for measuring at least one of a temperature, charging and discharging currents, and charging and discharging voltages of the power accumulating device; the controller being characterized in that the charging-discharging control means sets the execution of uniform charging of the power accumulating device on the basis of an output of the charging-discharging state measuring means.  
           [0030]    Further, the charging-discharging control means has a table setting a judging voltage of the uniform charging with respect to the charging current of the power accumulating device, and calculates the judging voltage from the table on the basis of a measuring value of the charging current from the charging-discharging state measuring means, and sets the execution of the uniform charging of the power accumulating device on the basis of the comparison of a measuring value of the charging voltage from the charging-discharging state measuring means and the judging voltage.  
           [0031]    Further, the charging-discharging control means has plural tables according to a charging degree as a value obtained by normalizing and accumulating a product of a charging-discharging current and a charging-discharging voltage by a capacity with a full charging state of the power accumulating device as a reference, and selects a table according to the charging degree.  
           [0032]    Further, the charging-discharging control means has a table setting a changing amount of a judging voltage of the uniform charging with respect to the charging current of the power accumulating device, and calculates the changing amount of the judging voltage from the table on the basis of a measuring value of the charging current from the charging-discharging state measuring means, and sets the execution of the uniform charging of the power accumulating device on the basis of the comparison of a voltage changing amount of a measuring value of the charging voltage from the charging-discharging state measuring means and the changing amount of the judging voltage.  
           [0033]    Further, the charging-discharging control means judges whether a running speed of the elevator is a constant speed or not on the basis of a command speed from speed control means for controlling the speed of the elevator, and sets the execution of the uniform charging of the power accumulating device on the basis of the comparison of the voltage changing amount of the measuring value of the charging voltage from the charging-discharging state measuring means and the changing amount of the judging voltage when it is judged that the running speed of the elevator is a constant speed.  
           [0034]    Further, the charging-discharging control means accumulates an operating time of the elevator, and determines execution timing of the uniform charging of the power accumulating device when the uniform charging of the power accumulating device is set while the elevator is not operated, or when an accumulating time of the operating time of the elevator exceeds a set time while the elevator is not operated.  
           [0035]    Further, the charging-discharging control means determines the execution timing of the uniform charging of the power accumulating device when a charging degree as a value obtained by normalizing and accumulating a product of a charging-discharging current and a charging-discharging voltage by a capacity on the basis of a measuring value from the charging-discharging state measuring means with a full charging state of said power accumulating device as a reference exceeds a predetermined value.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0036]    [0036]FIG. 1 is a block diagram showing the construction of a controller of an elevator in this invention.  
         [0037]    [0037]FIG. 2 is an explanatory diagram of a table T 1  arranged in a speed control circuit  21 A in an embodiment 1 of this invention in which a judging voltage with respect to a charging current is set.  
         [0038]    [0038]FIG. 3 is a flow chart showing control of the speed control circuit  21 A in the embodiment 1 of this invention.  
         [0039]    [0039]FIG. 4 is an explanatory diagram of plural tables T 1   a,  T 1   b,  . . . arranged every charging degree SOC in a speed control circuit  21 A in an embodiment 2 of this invention.  
         [0040]    [0040]FIG. 5 is a flow chart showing control of the speed control circuit  21 A in the embodiment 2 of this invention.  
         [0041]    [0041]FIG. 6 is an explanatory diagram of a table T 2  arranged in a speed control circuit  21 A in an embodiment 3 of this invention in which a changing amount of a judging voltage with respect to a charging current is set.  
         [0042]    [0042]FIG. 7 is a flow chart showing control of the speed control circuit  21 A in the embodiment 3 of this invention.  
         [0043]    [0043]FIG. 8 is a flow chart showing the control of a speed control circuit  21 A in an embodiment 4 of this invention.  
         [0044]    [0044]FIG. 9 is a flow chart showing the control of a speed control circuit  21 A in an embodiment 5 of this invention.  
         [0045]    [0045]FIG. 10 is a flow chart showing the control of a speed control circuit  21 A in an embodiment 6 of this invention.  
         [0046]    [0046]FIG. 11 is a block diagram showing the construction of a controller of an elevator in a conventional example.  
         [0047]    [0047]FIG. 12 is a flow chart showing the control of a charging-discharging control circuit  15  shown in FIG. 11 at its discharging time.  
         [0048]    [0048]FIG. 13 is a flow chart showing the control of the charging-discharging control circuit  15  shown in FIG. 11 at its charging time.  
         [0049]    [0049]FIG. 14 is an explanatory diagram showing uniform charging.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0050]    This invention provides a controller of an elevator having a charging-discharging control device for reducing the number of uniform charging times and having high reliability and high energy saving effects by measuring an operating state of a power accumulating device and judging a period for executing the uniform charging.  
         [0051]    The characteristics of a secondary battery arranged in the power accumulating device are different in accordance with kinds of the battery such as a lead battery, a nickel hydrogen battery, etc. However, in general, when these characteristics are considered at the same temperature, a charging voltage at that time is increased as a charging current is increased. When a charging reception property becomes worse, the charging voltage tends to be notably increased when a large charging current particularly flows through the secondary battery. When this increase is detected, it is necessary to dissolve this tendency by executing the uniform charging. Such a problem is not notably caused when the uniform charging is once executed and the battery is then discharged in many cases and is again charged in the next nighttime as in an electric automobile. In the elevator, the number of uniform charging times is reduced as mentioned above to increase the energy saving effects. Accordingly, it is necessary to know the above tendency of the charging voltage.  
         [0052]    [0052]FIG. 1 is a block diagram showing the construction of a controller of the elevator in this invention. In FIG. 1, the same portions as the conventional example shown in FIG. 11 are designated by the same reference numerals and their explanations are omitted here. New reference numerals  14 A and  15 A respectively designate a charging-discharging state measuring device and a charging-discharging control circuit in the present invention. The charging-discharging state measuring device  14 A has each of measuring instruments for measuring charging and discharging currents, charging and discharging voltages and a temperature of a power accumulating device  11 , and outputs each of these measuring values and a charging degree SOC to the charging-discharging control circuit  15 A. The charging-discharging control circuit  15 A controls charging and discharging operations of the power accumulating device  11  on the basis of a measuring value from the above charging-discharging state measuring device  14 A and a command speed from a speed control circuit  21 .  
         [0053]    Concrete embodiments will next be explained.  
       Embodiment 1  
       [0054]    In this embodiment mode 1, the charging-discharging control circuit  15 A has a table T 1  in which a judging voltage for judging the execution of uniform charging is set with respect to a charging current to a secondary battery  12  of the power accumulating device  11  as shown in FIG. 2. A measuring value of the charging current of the power accumulating device  11  is inputted from the charging-discharging state measuring device  14 A to the charging-discharging control circuit  15 A. The charging-discharging control circuit  15 A calculates the judging voltage corresponding to a measuring value of the inputted charging current from the above table T 1 . Further, the charging-discharging control circuit  15 A controls execution timing of the uniform charging by setting the execution of the uniform charging of the power accumulating device  11  on the basis of the comparison of a measuring value of the charging voltage from the above charging-discharging state measuring device  14 A and the judging voltage.  
         [0055]    Control of the charging-discharging control circuit  15 A in the embodiment mode 1 of this invention will next be explained with reference to a flow chart shown in FIG. 3.  
         [0056]    The charging-discharging control circuit  15 A first judges whether charging is performed or not on the basis of a measuring value of the charging current from the charging-discharging state measuring device  14 A at a charging time in a regenerative operation of the elevator (step S 101 ). When the charging is performed, the charging-discharging control circuit  15 A reads measuring values of the charging current and the charging voltage from the charging-discharging state measuring device  14 A (step S 102 ). The charging-discharging control circuit  15 A also reads a judging voltage for judging the execution of uniform charging from the table T 1  shown in FIG. 2 on the basis of the measuring value of the charging current (step S 103 ).  
         [0057]    The measuring value of the charging voltage is then compared with the judging voltage. When the measured charging voltage exceeds the judging voltage, it is judged that the uniform charging is required. Thus, the uniform charging is set and this setting is stored in a built-in memory, and the uniform charging is executed for a set time such as the nighttime. (steps S 104 , S 105 ).  
         [0058]    In the controller of the elevator constructed in this way, the uniform charging which reduces energy saving efficiency is executed only at a necessary time. Accordingly, the number of uniform charging times is reduced as a whole so that an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
       Embodiment mode 2  
       [0059]    Characteristics of the secondary battery  12  of the power accumulating device  11  are different in accordance with kinds of the battery such as a lead battery, a nickel hydrogen battery. However, in general, when these characteristics are considered at the same temperature and the secondary battery  12  is charged by the same charging current, the charging voltage of the battery at a charging time becomes a function of a charging degree SOC. Namely, the charging voltage is high in a high state of the charging degree SOC (in a state close to full charging). In contrast to this, the charging voltage is low in a low state of the charging degree SOC. In the elevator, the charging current provided by regenerative power is considerably greatly changed at a load state time of the elevator than the charging current used in the uniform charging. When a charging reception property of the secondary battery becomes worse, the charging voltage tends to be notably increased when particularly a large charging current flows through the secondary battery. Accordingly, when this increase is detected, it is necessary to dissolve this tendency by executing the uniform charging as mentioned above.  
         [0060]    In this embodiment mode 2, the charging-discharging control circuit  15 A has plural tables T 1   a,  T 1   b,  . . . in which a judging voltage for judging the execution of the uniform charging is set with respect to the charging current to the secondary battery  12  of the power accumulating device  11  every charging degree SOC as shown in FIG. 3. The charging-discharging control circuit  15 A selects a table according to the charging degree SOC as a value obtained by normalizing and accumulating a product of a charging-discharging current and a charging-discharging voltage by a capacity with a full charging state of the power accumulating device as a reference. Similar to the embodiment mode 1, the charging-discharging control circuit  15 A calculates the judging voltage corresponding to a measuring value of the charging current from the selected table. The charging-discharging control circuit  15 A then controls execution timing of the uniform charging by setting the execution of the uniform charging of the power accumulating device  11  on the basis of the comparison of a measuring value of the charging voltage from the charging-discharging state measuring device  14 A and the judging voltage.  
         [0061]    Control of the charging-discharging control circuit  15 A in the embodiment mode 2 of this invention will next be explained with reference to a flow chart shown in FIG. 4.  
         [0062]    The charging-discharging control circuit  15 A first judges whether charging is performed or not on the basis of a measuring value of the charging current from the charging-discharging state measuring device  14 A at a charging time in a regenerative operation of the elevator (step S 201 ). When the charging is performed, the charging-discharging control circuit  15 A reads measuring values of the charging current and the charging voltage from the charging-discharging state measuring device  14 A, and also reads the present charging degree SOC by accumulating measuring values of the charging current, the charging voltage, a discharging current and a discharging voltage (step S 202 ) (this charging degree SOC may be monitored by the charging-discharging control circuit  15 A, but is monitored by the charging-discharging state measuring device  14 A since the same effects are obtained).  
         [0063]    The charging-discharging control circuit  15 A then selects a table according to the present charging degree SOC from plural tables shown in FIG. 3, and reads a judging voltage for executing the uniform charging and corresponding to the measuring value of the charging current from the selected table (step S 203 ). The measuring value of the charging voltage is then compared with the judging voltage. When it is judged that the measured charging voltage exceeds the judging voltage, it is judged that the uniform charging is required. Thus, the uniform charging is set and this setting is stored in a built-in memory and the uniform charging is executed for a set time such as the nighttime. (steps S 204 , S 205 ).  
         [0064]    Thus, if the charging degree SOC is used to judge the uniform charging, timing of the uniform charging can be more finely set. Further, the number of uniform charging times is reduced as a whole by executing the uniform charging which reduces energy saving efficiency only at a necessary time. Thus, an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
       Embodiment mode 3  
       [0065]    In this embodiment mode 3, the charging-discharging control circuit  15 A has a table T 2  in which a changing amount of the judging voltage for judging the execution of the uniform charging is set with respect to the charging current to the secondary battery  12  of the power accumulating device  11  as shown in FIG. 5. The charging-discharging control circuit  15 A calculates the changing amount of the judging voltage corresponding to a measuring value of the charging current from the table T 2 . The charging-discharging control circuit  15 A then sets the execution of the uniform charging of the power accumulating device  11  on the basis of comparison of the changing amount of the judging voltage and a changing amount of a measuring value of the charging voltage from the charging-discharging state measuring device  14 A with respect to the previous measuring value. Thus, the charging-discharging control circuit  15 A controls execution timing of the uniform charging.  
         [0066]    Control of the charging-discharging control circuit  15 A in the embodiment mode 3 of this invention will next be explained with reference to a flow chart shown in FIG. 5.  
         [0067]    The charging-discharging control circuit  15 A first judges whether charging is performed or not on the basis of a measuring value of the charging current from the charging-discharging state measuring device  14 A at a charging time in a regenerative operation of the elevator (step S 301 ). When the charging is performed, the charging-discharging control circuit  15 A reads the measuring value of the charging current from the charging-discharging state measuring device  14 A, and also reads measuring values of the charging current and the charging voltage, and calculates a changing amount with respect to the charging voltage at a previous measuring time stored in a built-in memory (step S 302 ). The charging-discharging control circuit  15 A then reads a changing amount of the judging voltage for executing the uniform charging and corresponding to the measuring value of the present charging current from the table shown in FIG. 5 (step S 303 ).  
         [0068]    When the changing amount of the charging voltage and the changing amount of the judging voltage are compared and it is judged that the measured changing amount of the charging voltage exceeds the changing amount of the judging voltage, it is judged that the uniform charging is required. Thus, the uniform charging is set and this setting is stored in a built-in memory. The uniform charging is executed for a set time such as the nighttime, and the present charging voltage is stored in the built-in memory to prepare for the next measuring time (steps S 304 , S 305 ).  
         [0069]    Thus, the changing amount of the charging voltage is used to judge the uniform charging so that timing of the uniform charging can be more finely set. Further, the number of uniform charging times is reduced as a whole by executing the uniform charging which reduces energy saving efficiency only at a necessary time. Thus, an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
       Embodiment mode 4  
       [0070]    In this embodiment mode 4, similar to the embodiment mode 3, the charging-discharging control circuit  15 A has a table T 2  in which a changing amount of the judging voltage for judging the execution of the uniform charging is set with respect to the charging current to the secondary battery  12  of the power accumulating device  11  as shown in FIG. 5. The charging-discharging control circuit  15 A calculates the changing amount of the judging voltage corresponding to a measuring value of the charging current from the table T 2 . The charging-discharging control circuit  15 A then judges whether the elevator is operated or not at a constant speed on the basis of the input of a command speed from the speed control circuit  21 . When the speed is judged as a constant speed, similar to the embodiment mode 3, the execution of the uniform charging of the power accumulating device  11  is set on the basis of the comparison of a changing amount of the charging voltage and the changing amount of the judging voltage. Thus, the charging-discharging control circuit  15 A controls execution timing of the uniform charging.  
         [0071]    Control of the charging-discharging control circuit  15 A in the embodiment mode 4 of this invention will next be explained with reference to a flow chart shown in FIG. 7.  
         [0072]    The charging-discharging control circuit  15 A first judges whether charging is performed or not on the basis of a measuring value of the charging current from the charging-discharging state measuring device  14 A at a charging time in a regenerative operation of the elevator (step S 401 ). When the charging is performed, the charging-discharging control circuit  15 A reads the measuring value of the charging current from the charging-discharging state measuring device  14 A, and also reads measuring values of the charging current and the charging voltage, and calculates a changing amount with respect to the charging voltage at a previous measuring time stored in a built-in memory (step S 402 ).  
         [0073]    The charging-discharging control circuit  15 A then judges whether the elevator is operated or not at a constant speed on the basis of a change in command speed outputted from the speed control circuit  21  (step S 403 ). If the speed is a constant speed, the charging-discharging control circuit  15 A reads a changing amount of the judging voltage for executing the uniform charging and corresponding to the measuring value of the present charging current from the table shown in FIG. 5 (steps S 403 , S 404 ). The charging-discharging control circuit  15 A then compares the changing amount of the charging voltage and the changing amount of the judging voltage. When it is judged that the measured changing amount of the charging voltage exceeds the changing amount of the judging voltage, it is judged that the uniform charging is required. Thus, the uniform charging is set and this setting is stored in the built-in memory, and the uniform charging is executed for a set time such as the nighttime, and the present charging voltage is stored in the built-in memory to prepare for the next measuring time (steps S 405 , S 406 ).  
         [0074]    Thus, the constant speed of the elevator is detected and the changing amount of the charging voltage is used to judge the uniform charging so that timing of the uniform charging can be more finely set. Further, the number of uniform charging times is reduced as a whole by executing the uniform charging which reduces energy saving efficiency only at a necessary time. Thus, an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
       Embodiment mode 5  
       [0075]    [0075]FIG. 9 is a flow chart showing control contents for executing the uniform charging of the charging-discharging control circuit  15 A in the embodiment mode 5 of this invention.  
         [0076]    Control of execution timing of the uniform charging in the charging-discharging control circuit  15 A will next be explained in accordance with the flow chart shown in FIG. 9.  
         [0077]    The charging-discharging control circuit  15 A first accumulates an operating time of the elevator (step S 501 ). For example, this operating time is accumulated by counting a sending-out period of a command speed from the speed control circuit  21 . Next, for example, it is judged whether the elevator is out of operation or not by judging whether or not the command speed is outputted from the speed control circuit  21  (step S 502 ).  
         [0078]    If the elevator is out of operation, it is judged whether the uniform charging is set or not as in setting processings of the uniform charging shown in the above embodiment modes 1 to 4. If the uniform charging is set, the uniform charging is immediately executed (steps S 503 , S 504 ). In contrast to this, if no uniform charging is set, the accumulated operating time calculated in the step S 501  is compared with a set time. When the accumulated operating time exceeds the set time, the uniform charging is executed (step S 503 →S 505 ).  
         [0079]    Thus, the uniform charging is executed on the basis of the accumulated operating time of the elevator and existence of setting of the uniform charging. The number of uniform charging times is reduced as a whole by executing the uniform charging which reduces energy saving efficiency only at a necessary time. Thus, an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
       Embodiment mode 6  
       [0080]    [0080]FIG. 10 is a flow chart showing control contents for executing the uniform charging of the charging-discharging control circuit  15 A in an embodiment mode 6 of this invention.  
         [0081]    Control of execution timing of the uniform charging in the charging-discharging control circuit  15 A will next be explained in accordance with the flow chart shown in FIG. 10.  
         [0082]    The charging-discharging control circuit  15 A accumulates an operating time of the elevator (step S 601 ). For example, this operating time is accumulated by counting a sending-out period of a command speed from the speed control circuit  21 . The charging-discharging control circuit  15 A also calculates a charging degree SOC from the charging-discharging state measuring device  14 A (step S 602 ). Next, for example, it is judged whether the elevator is out of operation or not by judging whether or not the command speed is outputted from the speed control circuit  21  (step S 603 ).  
         [0083]    If the elevator is out of operation, it is judged whether the uniform charging is set or not as in setting processings of the uniform charging shown in the above embodiment modes 1 to 4. If the uniform charging is set, the uniform charging is immediately executed (steps S 604 , S 605 ). In contrast to this, if no uniform charging is set, the accumulated operating time calculated in the step S 501  is compared with a set time. When the accumulated operating time exceeds the set time, the uniform charging is executed (step S 604 →S 606 ). The uniform charging is also executed when no accumulated operating time exceeds the set time but the charging degree SOC calculated in the above step S 602  exceeds a set value (steps S 606 , S 607 ). After processing of the uniform charging, the charging degree SOC and the accumulated operating time are stored in a built-in memory to prepare for the next control, and it is terminated (step S 608 ).  
         [0084]    Thus, the uniform charging is executed on the basis of the accumulated operating time of the elevator, the charging degree SOC and existence of setting of the uniform charging. The number of uniform charging times is reduced as a whole by executing the uniform charging which reduces energy saving efficiency only at a necessary time. Thus, an elevator with the power accumulating device having higher energy saving efficiency can be constructed.  
         [0085]    As mentioned above, in accordance with this invention, it is possible to construct an elevator with a power accumulating device having larger energy saving effects by executing only required uniform charging.