JPH08157152A - Control device of elevator - Google Patents

Abstract

PURPOSE: To speedily detect reduction in capacitance of a smoothing capacitor when an electric induction motor to hoist an elevator is driven by an inverter. CONSTITUTION: A DC voltage detecting circuit 17 detects DC voltage smoothed by a smoothing capacitor 3, and sends it out to a control circuit 5. The control circuit 5 judges that capacitance of the smoothing capacitor 3 is reduced when ripple voltage contained in the DC voltage becomes large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling an elevator driven by an induction motor via an inverter.

[0002]

2. Description of the Related Art An alternating current supplied from an alternating current power source is converted into a direct current by a converter, this is smoothed by a smoothing capacitor, and this smoothed direct current is converted into an alternating current of an arbitrary voltage and frequency by an inverter to form an induction motor. There is one that is driven to raise and lower the elevator car. FIG. 8 is a block diagram showing the conventional elevator control device disclosed in, for example, Japanese Patent Publication No. 62-60349.

In the figure, R, S and T are three-phase AC power supplies,
(1) is a power switch that turns on or off the AC power supplies R, S, T, (2) is a converter that is connected to the power switch (1) and is composed of a thyristor and that converts AC to DC, and (3) is a converter (2 ) Is a smoothing capacitor connected to the DC side, (4) is an inverter that is connected to the smoothing capacitor (3) and is composed of a transistor and a diode, and converts DC to AC of an arbitrary voltage and frequency, and (5) is a converter (2 ) And an inverter (4).

(6) is a three-phase induction motor for hoisting connected to the AC side of the inverter (4), (7) is a drive sheave driven by the electric motor (6), and (8) is a drive sheave. A main rope wound around (7), with a basket (9) and a counterweight (10) on each end.
Are combined.

Reference numeral (11) is a rectifier circuit connected to the power switch (1), one side of which on the direct current side is connected to one end of the smoothing capacitor (3). (12) is a resistor connected to the other DC side of the rectifier circuit (11), and (13) is a resistor (12) and a smoothing capacitor.
A magnetic contactor contact that is connected to the other end of (3) and closes for a certain time after the power switch (1) is turned on, and (14) is connected to both ends of the smoothing capacitor (3) and the smoothing capacitor (3) Is a charging time measuring circuit that measures the charging time of and outputs the corresponding output to the control circuit (5).

The conventional elevator controller is constructed as described above, and when the power switch (1) is turned on, the AC of the AC power supplies R, S, T is converted into DC by the converter (2), and the smoothing capacitor Inverter smoothed by (3) (4)
Is supplied to. The inverter (4) converts the supplied direct current into an alternating current having a variable voltage and a variable frequency, and supplies it to the electric motor (6). These are controlled by the control circuit (5). This drives the electric motor (6) and raises and lowers the car (9).

On the other hand, when the power switch (1) is turned on,
The contact (13) is closed for a certain time (time until the smoothing capacitor (3) is charged). With this, the smoothing capacitor (3) starts charging through the resistor (12), and its charging voltage gradually increases according to the time constant determined by the capacitance of the smoothing capacitor (3) and the resistance value of the resistor (12). During this time, the converter (2)
The inverter (2) and the inverter (4) are not operated.

Here, the charging time measuring circuit (14) measures the charging time of the smoothing capacitor (3). The control circuit (5) monitors the charging time and issues an abnormal signal when it is detected that the charging time is shorter than the predetermined time. This abnormal signal allows the smoothing capacitor (3) to be replaced before the car (9) cannot perform normal service.

[0009]

The conventional elevator control device as described above starts charging of the smoothing capacitor (3) by turning on the power switch (1). To detect the decrease in capacitance of 3), maintenance personnel turn on the power switch (1) during the periodic inspection of the elevator. Therefore, there is a problem that it is not possible to promptly detect a decrease in the electrostatic capacitance of the smoothing capacitor (3).

Therefore, after the periodic inspection, the smoothing capacitor
In case (3) causes a rapid decrease in electrostatic capacity, it adversely affects the operation control of the elevator and, in the worst case, may trap passengers in the car.

The present invention has been made in order to solve the above problems, and an elevator in which a decrease in the electrostatic capacity of a smoothing capacitor can be promptly detected and safety can be ensured without operating a power switch. It is an object of the present invention to provide a control device of.

[0012]

A control device for an elevator according to a first aspect of the present invention includes a DC voltage detecting circuit for detecting a smoothed DC voltage, and a magnitude of a ripple voltage included in the detected DC voltage. And a capacitance decrease determining means for determining a decrease in the electrostatic capacitance of the smoothing capacitor.

In addition to the control apparatus for an elevator according to the second aspect of the present invention, in addition to the control apparatus for the first aspect of the present invention, a restart for preventing a restart of the car after the car is stopped when the capacity decrease determining means operates during operation of the car. It is provided with a blocking means.

The elevator control device according to a third aspect of the present invention is the elevator control device according to the first aspect of the present invention, wherein initial ripple voltage storage means for storing the magnitude of the ripple voltage included in the DC voltage detected immediately after installation of the elevator, It is provided with a capacity drop determining means for comparing the stored magnitude of the ripple voltage with the magnitude of the ripple voltage included in the currently detected DC voltage to determine whether the capacitance of the smoothing capacitor is lowered.

The elevator control apparatus according to the fourth aspect of the present invention is a direct-current energizing means for energizing a load connected to the direct-current side or alternating-current side of the inverter with direct current, a direct-current voltage detection circuit and a capacity decrease determination according to the first aspect of the invention. And means.

In the elevator controller according to the fifth aspect of the present invention, the direct-current energizing means of the fourth aspect of the invention is configured to energize the induction motor with direct current.

In the elevator controller according to the sixth aspect of the present invention, a resistor for consuming regenerative power from the induction motor is connected to the direct current side of the inverter, and the direct current energizing means of the fourth aspect of the invention is used to apply direct current to the resistor. It is configured to do.

Further, the elevator control apparatus according to the seventh aspect of the present invention detects a voltage on the AC side and a voltage on the DC side of the converter, and calculates a subtraction value of both of the voltages, and a subtraction value calculated. And a capacitance decrease determination means for determining a decrease in the electrostatic capacitance of the smoothing capacitor based on the above.

Further, the elevator control device according to the eighth aspect of the present invention includes a DC voltage component detection circuit for detecting a voltage component in a frequency band determined by the frequency of the AC power supply from the detected DC voltage, and a smoothed voltage component by the detected voltage component. It is provided with a capacitance decrease determination means for determining a decrease in the capacitance of the capacitor.

The elevator control apparatus according to the ninth aspect of the present invention is the elevator control apparatus according to the first aspect of the present invention, wherein a load detector for detecting the load in the car is provided, and the capacity decrease determining means detects that the load detector detects no load. The configuration is such that a decrease in the electrostatic capacitance of the smoothing capacitor is determined according to the magnitude of the ripple voltage included in the DC voltage detected by the DC voltage detection circuit.

[0021]

In the first aspect of the present invention, the DC voltage is detected, and the decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the magnitude of the ripple voltage contained in the DC voltage. It is determined that the electric capacity has decreased.

In the second aspect of the invention, when it is determined that the electrostatic capacitance of the smoothing capacitor has decreased during the operation of the car, the restart of the car is stopped and then restarted. Therefore, before the abnormality becomes apparent. The car is blocked from running.

Further, in the third invention, the magnitude of the ripple voltage included in the DC voltage immediately after the installation of the elevator is compared with the magnitude of the ripple voltage included in the DC voltage detected at present, and the electrostatic capacitance of the smoothing capacitor is compared. Since the decrease in capacitance is determined, the decrease in capacitance can be determined without being affected by the power source impedance.

In the fourth aspect of the invention, a load connected to the inverter is energized with a direct current to detect a direct current voltage, and a decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the magnitude of the ripple voltage included in the direct current voltage. As a result, the decrease in capacitance is determined without running the car.

Further, in the fifth aspect of the invention, the induction motor is energized with direct current to detect the direct current voltage, and the decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the magnitude of the ripple voltage included in the direct current. A decrease in capacitance is determined without running the car.

Further, in the sixth aspect of the invention, a direct current is passed through a resistor for consuming regenerative power to detect a direct current voltage, and a decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the magnitude of the ripple voltage included in the resistance. As a result, the decrease in capacitance is determined without running the car.

Further, in the seventh aspect of the invention, since the decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the subtracted value of the AC power supply voltage and the DC voltage, the subtracted value is the ripple voltage included in the DC voltage. It changes depending on the increase or decrease.

In the eighth aspect of the invention, the voltage component in the frequency band determined by the frequency of the AC power supply is detected from the DC voltage to determine the decrease in the capacitance of the smoothing capacitor. Changes with the increase or decrease of the ripple voltage included in the DC voltage.

Further, in the ninth aspect of the invention, when there is no load in the car, the decrease in the electrostatic capacitance of the smoothing capacitor is determined by the magnitude of the ripple voltage included in the detected DC voltage. A decrease in capacitance is determined under load conditions.

[0030]

【Example】

Example 1. 1 and 2 are views showing one embodiment of the first invention of the present invention. FIG. 1 is a configuration diagram, FIG. 2 is a voltage waveform diagram, and the same parts as those of the conventional device are indicated by the same reference numerals (hereinafter The same applies to the examples). In FIG. 1, (15) is a power switch (1)
Power factor improving reactor connected to, (16) is reactor (15)
A converter for connecting AC to DC, (17) a DC voltage detection circuit connected across the smoothing capacitor (3), (18) a resistor for regenerative power consumption, and (19) a semiconductor element for switching. Then, both are connected in series and the converter
It is connected to the DC side of (4).

Next, the operation of the first embodiment will be described. When the power switch (1) is turned on, the AC of the AC power supplies R and S is converted into DC by the converter (16), smoothed by the smoothing capacitor (3), and supplied to the inverter (4). The inverter (4) converts the supplied direct current into alternating current and supplies it to the electric motor (6). These are controlled by the control circuit (5). This drives the electric motor (6) and raises and lowers the car (9).

On the other hand, the DC voltage detection circuit (17) detects the DC voltage smoothed by the smoothing capacitor (3) and sends it to the control circuit (5). The electric power regenerated during the regenerative operation of the electric motor (6) is converted into direct current by the inverter (4) by the operation of the control circuit (5). At this time, the control circuit (5) turns on the semiconductor element (19) to consume the regenerative power through the resistor (18).

The DC voltage smoothed by the smoothing capacitor (3) has a ripple voltage as shown by the voltage Vd shown in FIG. 2 when the car (9) is stopped and almost no DC power is consumed. It is maintained at a DC voltage that does not include it. next,
When the DC power is consumed by the traveling of the car (9), the DC voltage becomes a waveform including a ripple voltage like the voltage Vd _{1 due to} the impedance of the reactor (15) and the smoothing capacitor (3). Here, when the electrostatic capacitance of the smoothing capacitor (3) decreases, the ripple voltage further increases, and the voltage V
The waveform is as shown by d ₂ . The values with the lowest voltage of these waveforms are referred to as V ₁ and V ₂ , respectively.

Here, since the magnitude of the ripple included in the DC voltage varies depending on the running condition of the car (9), that is, the magnitude of the consumed power, the smoothing capacitor (3 It is possible to detect the decrease in the capacitance of). That is, when the output of the inverter (4) is a specific value, the voltage Vd of FIG.
_The voltage V ₂ that has dropped the most is detected from the waveform ₂ and it is determined whether the value has dropped below the specified value. If it has dropped, it is determined that the capacitance of the smoothing capacitor (3) has dropped. .

In this way, it is possible to promptly determine the decrease of the electrostatic capacity without any manual operation and monitor the change of the electrostatic capacity of the smoothing capacitor (3) constantly or at a relatively short time interval. It will be possible. Here, the control circuit (5) constitutes a capacity decrease determination means. Further, in the first embodiment, the decrease in the electrostatic capacity of the smoothing capacitor (3) is determined, but it is also easy to configure to issue an alarm according to the result.

Example 2. Embodiment 2 shows an embodiment of the second invention of the present invention, and shares FIG. 1 and FIG.
In this embodiment, when the control circuit (5) determines that the capacitance of the smoothing capacitor (3) has decreased during operation of the car (9), the car (9)
After the stop, the control circuit (5) controls the inverter (4) to prevent the car (9) from restarting.

That is, the decrease in the electrostatic capacity of the smoothing capacitor (3) is a precursor of the failure of the smoothing capacitor (3).
It is possible to prevent the passengers from being trapped in the car (9) by preventing the car (9) from traveling before the abnormality becomes apparent. Here, the control circuit (5) constitutes a restart prevention means.

Example 3. The third embodiment shows an embodiment of the third invention of the present invention and shares FIG. 1 and FIG.
In this embodiment, immediately after the installation of the elevator, the DC voltage Vd in the state where the electrostatic capacity of the smoothing capacitor (3) is not lowered is stored in the control circuit (5) as the most lowered voltage V ₁ . After that, the voltage V ₂ which is appropriately detected is compared with the difference voltage V ₁
When −V ₂ exceeds a specified value, it is determined that the electrostatic capacity of the smoothing capacitor (3) has decreased.

That is, since the secular change of the electrostatic capacity of the smoothing capacitor (3) is monitored in consideration of the conditions peculiar to the installed building, it is not affected by the power source impedance which is different for each elevator installation place. , It is possible to accurately determine the decrease in the electrostatic capacity of the smoothing capacitor (3),
It is possible to monitor the secular change of the smoothing capacitor (3) in consideration of the conditions peculiar to the building. Where the control circuit (5)
Constitutes an initial ripple voltage storage means and a capacity drop determination means.

Example 4. Example 4 shows an example of the fourth and fifth aspects of the present invention and shares FIG. 1 and FIG. In this embodiment, the inverter (4) is controlled by the operation of the control circuit (5), a direct current is supplied to the electric motor (6), a ripple is generated in the direct current voltage, and the electrostatic capacitance of the smoothing capacitor (3) is generated. Is determined.

That is, the determination of the decrease in the electrostatic capacity of the smoothing capacitor (3) is made without rotating the electric motor (6).
Since it can be carried out during the stop of, the direct current value can be set to an arbitrary value. Further, the service of the elevator is not deteriorated due to the detection operation or the like. Here, the control circuit (5) constitutes a direct current conducting means and a capacity reduction determining means.

Example 5. Embodiment 5 shows an embodiment of the sixth invention of the present invention, which shares FIG. 1 and FIG. 2 and in which Embodiment 4 energizes the electric motor (6) with direct current, (18) is made to be energized. That is, the semiconductor element (19) is turned on by the operation of the control circuit (5), a direct current is applied to the resistor (18), and the smoothing capacitor (3)
The determination is made as to whether or not the electrostatic capacitance is reduced.

Also in this embodiment, since the operation can be performed while the car (9) is stopped without rotating the electric motor (6), the direct current value can be set to an arbitrary value. Further, the elevator service will not be deteriorated due to the detection operation or the like.

Example 6. 3 and 4 show a seventh embodiment of the present invention.
FIG. 3 is a diagram showing an embodiment of the invention, FIG. 3 is a configuration diagram, and FIG. 4 is a voltage waveform diagram. In FIG. 3, (20) is a voltage subtraction circuit connected to the AC side and the DC side of the converter.

Next, the operation of the sixth embodiment will be described. The normal elevator operation is as described in the first embodiment.
At this time, the voltage subtraction circuit (20) subtracts the AC voltage input to the converter (16) from the DC voltage smoothed by the smoothing capacitor (3) and sends it to the control circuit (5). That is, in FIG. 4, the difference voltage Vb obtained by subtracting the full-wave rectified voltage Va of the AC voltage input to the converter (16) from the voltage Vd ₂ smoothed by the smoothing capacitor (3).
Will be sent to the control circuit (5).

Here, since the value of the difference voltage Vb changes depending on the magnitude of the ripple voltage included in the DC voltage, it becomes possible to determine the decrease in the electrostatic capacitance of the smoothing capacitor (3). Further, since the subtracted value of the voltage on both sides of the converter (16) is obtained, the subtracted value is not affected even if the power supply voltage changes, and the detection accuracy is improved.

Example 7. 5 and 6 show the eighth aspect of the present invention.
FIG. 5 is a diagram showing an embodiment of the invention, FIG. 5 is a configuration diagram, and FIG. 6 is a voltage waveform diagram. In FIG. 5, (21) is a smoothing capacitor
An AC component detection circuit connected to both ends of (3) to detect an AC component contained in the smoothed DC voltage.

Next, the operation of the seventh embodiment will be described. The normal elevator operation is as described in the first embodiment.
At this time, the AC component detection circuit (21) is the smoothing capacitor (3)
The AC voltage component included in the DC voltage smoothed by is detected and sent to the control circuit (5). For example, a DC voltage obtained by full-wave rectification of a single-phase power supply is twice the commercial frequency, and a DC voltage obtained by full-wave rectification of a three-phase power supply is an AC with a frequency component six times the commercial frequency. It will include a lot of voltage.

That is, as shown in FIG. 6, as the DC voltage increases from the voltage Vd to the voltages Vd ₁ and Vd ₂ and the ripple voltage included in the DC voltage, the DC voltage becomes twice the commercial frequency included in the DC voltage. The AC voltage value of the frequency component is also the voltage V
Since it changes to a ₁ and Va ₂ , it becomes possible to determine the decrease in the electrostatic capacitance of the smoothing capacitor (3). Further, since the determination is made based on the fundamental wave component, even if the waveforms of the power supplies R and S are slightly distorted, the determination can be accurately performed.

Example 8. FIG. 7 is a block diagram showing an embodiment of the ninth invention of the present invention. In this embodiment, the load detector (2) for detecting the load in the car (9) is added to the car (9) in FIG.
2) is installed and connected to the control circuit (5). That is, the load detector (22) detects the load in the car (9) and sends a load detection signal to the control circuit (5). When the load detector (22) detects no load, the control circuit (5) determines whether or not the electrostatic capacitance of the smoothing capacitor (3) has decreased, as described in the first embodiment.

The ripple voltage included in the DC voltage changes depending on the decrease in the electrostatic capacity of the smoothing capacitor (3) and the magnitude of the load current. Therefore, when determining the decrease in capacitance while the car (9) is running, the load current, that is, the car (9)
It is necessary to keep the load conditions in the same. With no load in the car (9), the above conditions can be set most easily.

In each of the above-mentioned embodiments, the AC power supplies R and S use single-phase power supplies, but they can also be applied to three-phase power supplies.

[0053]

As described above, in the first invention of the present invention, the DC voltage is detected, and the decrease of the electrostatic capacitance of the smoothing capacitor is determined by the magnitude of the ripple voltage included in the DC voltage. It is possible to determine the decrease in the capacitance of the smoothing capacitor without any operation, and quickly detect the decrease in the capacitance of the smoothing capacitor, and it is possible to monitor the change in the capacitance of the smoothing capacitor constantly or at relatively short time intervals. , There is an effect that can improve the safety of the elevator.

In the second aspect of the invention, when it is determined that the capacitance of the smoothing capacitor has decreased during the operation of the car, the restart of the car is stopped and then restarted. Therefore, before the abnormality becomes apparent. It is possible to prevent the traveling of the car and prevent the passengers from being trapped in the car.

In the third invention, the magnitude of the ripple voltage contained in the DC voltage immediately after the elevator is installed is compared with the magnitude of the ripple voltage contained in the DC voltage detected at present, and the electrostatic capacitance of the smoothing capacitor is calculated. Since the decrease is determined, the decrease in the capacitance is determined without being affected by the power source impedance, and there is an effect that the secular change of the smoothing capacitor can be monitored in consideration of the condition peculiar to the building.

According to the fourth aspect of the invention, the load connected to the inverter is energized with a direct current to detect the direct current voltage, and the decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the magnitude of the ripple voltage included in the direct current voltage. Therefore, it is possible to prevent a decrease in the electrostatic capacity without causing the car to travel, and to prevent deterioration in service of the elevator, and it is possible to improve the detection accuracy.

In the fifth aspect of the invention, the induction motor is energized with a direct current to detect the direct current voltage, and the decrease in the electrostatic capacitance of the smoothing capacitor is determined by the magnitude of the ripple voltage contained in the direct current. It is determined that the capacitance has decreased without running the car, and the same effect as the fourth aspect of the invention is obtained.

Further, in the sixth aspect of the present invention, a direct current is passed through a resistor for consuming regenerative power to detect a direct current voltage, and a decrease in the electrostatic capacitance of the smoothing capacitor is determined by the magnitude of the ripple voltage included in this. Therefore, it is determined that the electrostatic capacitance is reduced without running the car, and the same effect as the fourth aspect of the invention is obtained.

Further, in the seventh aspect of the invention, since the decrease in the electrostatic capacitance of the smoothing capacitor is determined based on the subtracted value of the AC power supply voltage and the DC voltage, the subtracted value is the ripple voltage included in the DC voltage. The subtraction value is not affected even if the power supply voltage changes due to increase / decrease, and the decrease in the capacitance of the smoothing capacitor can always be determined with high accuracy.

In the eighth aspect of the invention, the voltage component in the frequency band determined by the frequency of the AC power source is detected from the DC voltage to determine the decrease in the capacitance of the smoothing capacitor. There is an effect that the decrease in the electrostatic capacitance of the smoothing capacitor can be accurately determined even if the ripple voltage included in the DC voltage changes due to increase / decrease and is determined by the fundamental wave component and the power supply waveform is slightly distorted.

Further, in the ninth aspect of the invention, when there is no load in the car, the decrease of the electrostatic capacitance of the smoothing capacitor is judged according to the magnitude of the ripple voltage included in the detected DC voltage. There is an effect that a decrease in capacitance is determined under the load condition and the load condition can be easily set.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

2 is a voltage waveform diagram of FIG.

FIG. 3 is a configuration diagram showing a sixth embodiment of the present invention.

FIG. 4 is a voltage waveform diagram of FIG.

FIG. 5 is a configuration diagram showing a seventh embodiment of the present invention.

FIG. 6 is a voltage waveform diagram of FIG.

FIG. 7 is a configuration diagram showing an eighth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a conventional elevator control device.

[Explanation of symbols]

R, S AC power supply, 3 smoothing capacitors, 4 inverters, 5 capacity reduction determination means, restart prevention means, initial ripple voltage storage means, DC energization means (control circuit), 6 induction motors, 9 cages, 16 converters, 17 DC Voltage detection circuit, 18 regenerative power consumption resistor, 19 switching semiconductor element, 20 voltage subtraction circuit, 21 AC voltage component detection circuit, 22 load detector.

Claims (9)

[Claims] 1. A converter for converting an alternating current supplied from an alternating current power source into a direct current, a capacitor for smoothing the converted direct current, and a converter for driving the car by converting the smoothed direct current into an alternating current of an arbitrary frequency. In a control device having an inverter that controls an induction motor, a DC voltage detection circuit that detects the DC voltage, and a decrease in the electrostatic capacitance of the smoothing capacitor is determined by the magnitude of the ripple voltage included in the detected DC voltage. An elevator control device, comprising: 2. The elevator control device according to claim 1, further comprising restart preventing means for preventing the restart of the car after the car is stopped when the capacity decrease determining means operates during the operation of the car. . 3. An initial ripple voltage storage means for storing the magnitude of the ripple voltage included in the DC voltage detected immediately after the installation of the elevator is provided, and the capacity drop determining means detects the magnitude of the stored ripple voltage and the current detection. The elevator control device according to claim 1, wherein the control device for an elevator according to claim 1 is configured to determine a decrease in the electrostatic capacitance of the smoothing capacitor by comparing the magnitude of the ripple voltage included in the DC voltage. 4. A converter for converting an alternating current supplied from an alternating current power source into a direct current, a capacitor for smoothing the converted direct current, and a car for driving the smoothed direct current into an alternating current of an arbitrary frequency. In a control device having an inverter for controlling an induction motor, a DC energizing means for energizing a load connected to a DC side or an AC side of the inverter with a DC current, and a DC voltage detection circuit for detecting the DC voltage,
An elevator control device, comprising: a capacitance decrease determination unit that determines a decrease in electrostatic capacitance of the smoothing capacitor according to a magnitude of a ripple voltage included in the detected DC voltage. 5. The elevator control apparatus according to claim 4, wherein the direct-current energizing means is configured to energize the induction motor with direct current. 6. A direct-current energizing means is connected to the direct-current side of the inverter by connecting a resistor for consuming regenerative electric power from the induction motor.
The elevator control apparatus according to claim 4, wherein a direct current is applied to the resistor. 7. A converter for converting an alternating current supplied from an alternating current power source into a direct current, a capacitor for smoothing the converted direct current, and a car for driving the smoothed direct current into an alternating current of an arbitrary frequency. In a control device having an inverter for controlling an induction motor, a voltage subtraction circuit that detects a voltage on the AC side and a voltage on the DC side of the converter and calculates a subtraction value of both voltages, and based on the calculated subtraction value An elevator control device, comprising: a capacity decrease determination means for determining a decrease in electrostatic capacity of the smoothing capacitor. 8. A converter for converting an alternating current supplied from an alternating current power source into a direct current, a capacitor for smoothing the converted direct current, and a converter for driving the car by converting the smoothed direct current into an alternating current of an arbitrary frequency. In a control device having an inverter for controlling an induction motor, a DC voltage detection circuit for detecting the DC voltage, and an AC voltage component detection for detecting a voltage component in a frequency band determined by the frequency of the AC power supply from the detected DC voltage. An elevator control device comprising: a circuit; and a capacitance decrease determination unit that determines a decrease in electrostatic capacitance of the smoothing capacitor based on the detected voltage component. 9. A load detector for detecting a load in the car is provided, and when the load detector detects no load, the smoothing capacitor is detected according to the magnitude of the ripple voltage included in the DC voltage detected by the DC voltage detection circuit. 2. The elevator control device according to claim 1, further comprising a capacitance decrease detection means, which is configured to determine a decrease in electrostatic capacitance.