Elevator control apparatus

In an elevator control apparatus, a DC-DC converter including a first switching element and a second switching element is configured to generate power for driving an elevator brake by alternately operating each of the first switching element and the second switching element. A first photocoupler and a second photocoupler are configured to independently operate the first switching element and the second switching element, respectively. A first calculation unit and a second calculation unit are configured to independently control power supply voltages of the first photocoupler and the second photocoupler, respectively.

TECHNICAL FIELD

The present invention relates to an elevator control apparatus for controlling a power supply to an elevator brake.

BACKGROUND ART

In general, for an elevator hoisting machine brake, a braking force is produced by cutting the power supply to a brake coil by an electromagnetic switch. When there is only one electromagnetic switch, in a case where an ON failure of the electromagnetic switch occurs, the brake cannot perform a braking operation. Therefore, in order for the brake to reliably perform a braking operation, a plurality of electromagnetic switches are needed.

Hitherto, an elevator brake safety control apparatus has been proposed in which operation of a semiconductor switch in a primary-side circuit of a direct current (DC)-DC converter for supplying power to a brake coil is controlled by a pulse-width modulation controller so that the power supply of the pulse-width modulation controller is cut at a plurality of safety relay contact points when an abnormality occurs in the elevator (refer to Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, with a related-art elevator brake safety control apparatus, the cutting of the power supply of the pulse-width modulation controller is performed at the safety relay contact points, and hence a contact failure may occur at the safety relay contact points. In this case, it is more difficult to correctly control operation of the brake. Further, operating noise is produced by operation of the safety relay contact points, and hence it is more difficult to reduce unwanted noise. In addition, due to the presence of the safety relay contact points, it is more difficult to reduce circuit size.

The present invention has been created in order to solve the above-mentioned problems. It is an object of the present invention to provide an elevator control apparatus capable of controlling operation of a brake more reliably, capable of preventing production of unwanted noise, and that is more compact.

Solution to Problem

An elevator control apparatus according to one embodiment of the present invention includes: a DC-DC converter including a first switching element and a second switching element, for generating power for driving an elevator brake by alternately operating each of the first switching element and the second switching element; a first photocoupler and a second photocoupler for independently operating the first switching element and the second switching element, respectively; and a first calculation unit and a second calculation unit for independently controlling power supply voltages of the first photocoupler and the second photocoupler, respectively.

Advantageous Effects of Invention

According to the elevator control apparatus of the one embodiment of the present invention, the operation of the brake may be controlled more reliably, the production of unwanted noise may be prevented, and the size reduction may be achieved.

DESCRIPTION OF EMBODIMENTS

Now, exemplary embodiments of the present invention are described with reference to the drawings.

First Embodiment

FIG. 1is a configuration diagram for illustrating an elevator according to a first embodiment of the present invention. InFIG. 1, a car2and a counterweight3are suspended by a main cable4in a hoistway1. As the main cable4, for example, a rope, a belt, or the like is used. At an upper portion of the hoistway1, a hoisting machine5for producing a driving force for moving the car2and the counterweight3is arranged.

The hoisting machine5includes a hoisting machine main body6including a motor, a drive sheave7rotatably arranged on the hoisting machine main body6, and a brake8for applying a braking force on the drive sheave7.

The main cable4is wound around the drive sheave7. The drive sheave7is rotated by a driving force of the motor in the hoisting machine main body6. The car2and the counterweight3are moved in up and down directions in the hoistway1by the rotation of the drive sheave7.

The brake8includes a rotating body9configured to rotate integrally with the drive sheave7, and a plurality of brake main bodies10(in this example, two). The brake main bodies10are arranged separated from each other in the rotational direction of the rotating body9, and each of the brake main bodies10is configured to apply a braking force on the rotating body9.

Each brake main body10includes a brake shoe (braking body)11capable of being brought into contact with and separated from the rotating body9, a pressing spring (urging member) (not shown) for urging the brake shoe11in a direction for contacting the rotating body9, and a brake coil (electromagnetic coil)12for producing from a power supply an electromagnetic force in a direction for separating the brake shoe11from the rotating body9.

The brake shoe11is configured to separate from the rotating body9in resistance to the urging force of the pressing spring when power is supplied to the brake coil12, and to be pressed against the rotating body9in conformity with the urging force of the pressing spring when power to the brake coil12is cut. A braking force is applied to the car2and the drive sheave7by the brake shoe11being pressed against the rotating body9. Further, the braking force on the car2and the drive sheave7is released by the brake shoe11separating from the rotating body9.

A control apparatus21for controlling operation of the elevator is arranged in the hoistway1. The control apparatus21includes an operation control device22, a power conversion device23, a brake control device24, a brake power supply device25, and a safety control device26.

The operation control device22is configured to send an operation control signal for controlling operation of the motor in the hoisting machine main body6to the power conversion device23, and send an operation control signal for controlling operation of the brake8to the brake control device24.

The power conversion device23is configured to control the power supply to the motor in the hoisting machine main body6based on the operation control signal from the operation control device22. Operation of the motor in the hoisting machine main body6is controlled by controlling the power supply from the power conversion device23.

The brake control device24is configured to individually control the power supply to each brake coil12based on the operation control signal from the operation control device22. Operation of each brake shoe11is individually controlled by controlling the power supply to each brake coil12by the brake control device24.

The brake power supply device25is configured to supply to the brake control device24electric power for the power supply to each brake coil12(i.e., electric power for operating the brake8).

The safety control device26is configured to output a control signal to the power conversion device23and to the brake power supply device25. The power supply to the motor in the hoisting machine main body6by the power conversion device23is enabled by the power conversion device23receiving the control signal. Further, the power supply to the brake control device24by the brake power supply device25is enabled by the brake power supply device25receiving the control signal.

The power conversion device23and the brake power supply device25are each configured to output, when the control signal from the safety control device26is received, a monitoring signal based on the control signal to the safety control device26. The safety control device26is configured to determine whether or not an abnormality has occurred in each of the power conversion device23and the brake power supply device25by monitoring the monitoring signal from each of the power conversion device23and the brake power supply device25.

Further, the elevator includes a safety circuit having a plurality of detection devices connected in series thereto. Examples of the detection devices include a plurality of door switches for detecting an open/closed state of a car entrance of the car2and an open/closed state of a landing entrance13at each floor, an emergency stop switch for detecting operation of an emergency stop device mounted to the car2, and a speed governor switch for detecting overspeed of the car2. When all of the detection devices are normal, an electric safety chain signal S is input from the safety circuit to the safety control device26. When an abnormality has occurred in at least any one of the detection devices (e.g., when the door is detected as being open by the door switch of the car2while the car2is moving), the safety circuit is cut, and the input of the electric safety chain signal S to the safety control device26is stopped. The safety control device26is configured to determine whether or not an abnormality has occurred in the state of the elevator based on whether or not the electric safety chain signal S is being input.

The safety control device26is configured to stop output of the control signal to each of the power conversion device23and the brake power supply device25when an abnormality has occurred in at least any one of the state of the elevator based on the electric safety chain signal S, the power conversion device23, and the brake power supply device25. When output of the control signal to each of the power conversion device23and the brake power supply device25is stopped, the power supply to the motor in the hoisting machine main body6and the power supply to each brake coil12are stopped.

FIG. 2is a configuration diagram for illustrating the brake control device24, the brake power supply device25, and the safety control device26illustrated inFIG. 1. The brake control device24includes the same number of transistors (switching elements)30as the number of brake coils12(in this example, two). Further, the brake control device24is configured to individually perform an ON/OFF operation of each transistor30based on the operation control signal from the operation control device22. The brake control device24is capable of individually supplying output power of the brake power supply device25to each brake coil12by individually performing an ON operation of each transistor30.

The brake power supply device25includes a power conversion unit31for converting commercial alternating-current power into direct-current power, a half-bridge DC-DC converter32for converting direct-current power from the power conversion unit31into direct-current power for supply to each brake coil12, and first and second photocouplers33and34each for outputting a drive signal for operating the DC-DC converter32. The brake power supply device25also includes first and second power supply control circuits35and36for controlling power supply voltages of the first and second photocouplers33and34, respectively, and a converter control device37for controlling operation of each of the first and second photocouplers33and34.

The DC-DC converter32includes a transformer (high-frequency transformer)43including a primary-side coil41and a secondary-side coil42, a primary-side circuit44for converting direct-current power from the power conversion unit31into alternating-current power and supply the converted alternating-current power to the primary-side coil41, and a secondary-side circuit45for converting alternating-current power induced in the secondary-side coil42into direct-current power for supply to each brake coil12.

The primary-side circuit44includes a first transistor (transistor on an upper arm (positive electrode) side)46, which is a first switching element, and a second transistor (transistor on a lower arm (negative electrode) side)47, which is a second switching element. The first and second transistors46and47are field-effect transistors (FETs).

The first transistor46is configured to perform an ON/OFF operation under the control of the drive signal (gate drive signal) from the first photocoupler33. The second transistor47is configured to perform an ON/OFF operation under the control of the drive signal (gate drive signal) from the second photocoupler34. The primary-side circuit44is configured to convert direct-current power from the power conversion unit31into alternating-current power to be supplied to the primary-side coil41by alternately performing the ON/OFF operations of the first and second transistors46and47. When the drive signal of anyone of the first and second photocouplers33and34has stopped (has been cut), operation of the DC-DC converter32is stopped, and direct-current power stops being generated in the secondary-side circuit45.

The first and second photocouplers33and34each include a light-emitting element and a light-receiving element. Further, the first and second photocouplers33and34are each configured to produce a drive signal by allowing the conduction of the light-receiving element with light emitted by the light-emitting element.

The converter control device37is configured to control operation of each of the first and second photocouplers33and34so that the drive signals from the first and second photocouplers33and34are alternately output by alternately emitting light and extinguishing light from the light-emitting elements of the first and second photocouplers33and34to repeat conduction and non-conduction of the light-receiving elements.

The first and second power supply control circuits35and36are configured to independently control the power supply voltages of the first and second photocouplers33and34, respectively. In other words, the circuit configuration for controlling the power supply voltage of each of the first and second photocouplers33and34has a dual circuit configuration. Therefore, operation of the DC-DC converter32is stopped by cutting the power supply of at least any one of the first and second photocouplers33and34.

The safety control device26includes a first safety control central processing unit (CPU) (first calculation unit)51and a second safety control CPU (second calculation unit)52. The electric safety chain signal S is independently input to each of the first and second safety control CPUs51and52. As a result, the first and second safety control CPUs51and52are each configured to independently detect an abnormality in the elevator state when input of the electric safety chain signal S is stopped.

The first and second safety control CPUs51and52are configured to independently output to the first and second power supply control circuits35and36a periodically varying signal as a control signal. The first and second safety control CPUs51and52are configured to independently control the respective power supply voltages of the first and second photocouplers33and34by controlling operation of the first and second power supply control circuits35and36based on the control signals.

The first power supply control circuit35is configured to control the power supply voltage of the first photocoupler33based on the control signal from the first safety control CPU51. Further, the first power supply control circuit35is configured to periodically vary a value of the power supply voltage of the first photocoupler33based on the control signal from the first safety control CPU51while maintaining the value of the power supply voltage of the first photocoupler33at a higher value than a threshold at which operation of the first photocoupler33stops (i.e., a value at a level at which there is no hindrance to operation of the first photocoupler33).

The second power supply control circuit36is configured to control the power supply voltage of the second photocoupler34based on the control signal from the second safety control CPU52. Further, the second power supply control circuit36is configured to periodically vary a value of the power supply voltage of the second photocoupler34based on the control signal from the second safety control CPU52while maintaining the value of the power supply voltage of the second photocoupler34at a higher value than a threshold at which operation of the second photocoupler34stops (i.e., a value at a level at which there is no hindrance to operation of the second photocoupler34).

The power supply voltage of each of the first and second photocouplers33and34is input as a monitoring signal to both the first and second safety control CPUs51and52. As a result, each of the first and second safety control CPUs51and52monitors the power supply voltage of the first photocoupler33and the power supply voltage of the second photocoupler34. The first and second safety control CPUs51and52are each configured to monitor the first and second power supply control circuits35and36and monitor the other of the first safety control CPU51or the second safety control CPU52by monitoring whether or not the power supply voltage of each of the first and second photocouplers33and34is periodically varying based on the control signals.

FIG. 3is a graph for showing changes over time during normal operation in the control signals of the first and second safety control CPUs51and52, the power supply voltages of the first and second photocouplers33and34, and the output voltage of the DC-DC converter32, illustrated inFIG. 2, respectively. The control signal from the first safety control CPU51is a signal repeating at a period T1a change that stops output for a time T3. The control signal from the second safety control CPU52is a signal that, after the control signal of the first safety control CPU51has restarted, stops output for the time T3after a defined time T2, which is a shorter time than the period T1. In other words, the control signal from the second safety control CPU52is a signal that offsets the change period by the time T2with respect to the control signal from the first safety control CPU51.

The time T3during which the control signals from the first and second safety control CPUs51and52are stopped is set as a short time during which the power supply voltages of the first and second photocouplers33and34do not fall below a threshold L at which operation of the first and second photocouplers33and34stops.

During normal operation, the first and second safety control CPUs51and52are each configured to constantly monitor that the first and second power supply control circuits35and36are operating normally based on the fact that the power supply voltage of each of the first and second photocouplers33and34varies in synchronization with the control signals. As a result, during normal operation, output of the periodically varying control signals is continued by the first and second safety control CPUs51and52, and the output voltage of the secondary-side circuit45of the DC-DC converter32is produced normally.

FIG. 4is a graph for showing changes over time in the control signals of the first and second safety control CPUs51and52, the power supply voltages of the first and second photocouplers33and34, and the output voltage of the DC-DC converter32, respectively, when an abnormality is detected based on stoppage of the electric safety chain signal S illustrated inFIG. 2. The first and second safety control CPUs51and52are configured to independently stop the control signal to each of the first and second power supply control circuits35and36when an abnormality is detected based on stoppage of the electric safety chain signal S.

As a result, after control of the power supply voltages of the first and second photocouplers33and34by the first and second power supply control circuits35and36is stopped, and a fixed time T4has elapsed, the value of the power supply voltages of the first and second photocouplers33and34decreases to a level lower than the threshold L, and operation of each of the first and second photocouplers33and34stops. Consequently, the signal of the converter control device37stops being transmitted to the first and second transistors46and47of the DC-DC converter32, operation of the primary-side circuit44stops, and the output voltage of the secondary-side circuit45decreases to zero. As a result, the power supply to each brake coil12is stopped, and a braking operation by the brake8is performed.

FIG. 5is a graph for showing changes over time in the control signals of the first and second safety control CPUs51and52, the power supply voltages of the first and second photocouplers33and34, and the output voltage of the DC-DC converter32, respectively, when the first power supply control circuit35illustrated inFIG. 2has suffered from an ON failure. When an ON failure occurs in the first power supply control circuit35, the power supply voltage of the first photocoupler33becomes a fixed value regardless of the control signal of the first safety control CPU51. At this stage, the power supply voltage of the first photocoupler33does not vary in synchronization with the control signal of the first safety control CPU51, and hence the first and second safety control CPUs51and52monitoring the power supply voltage of the first photocoupler33each detect an abnormality.

The first and second safety control CPUs51and52are each configured to immediately stop output of the control signal when an abnormality is detected. Because the first power supply control circuit35has suffered from an ON failure, the power supply voltage of the first photocoupler33is maintained as is without decreasing even though the control signal is stopped. However, the power supply voltage of the second photocoupler34falls below the threshold after the fixed time T4has elapsed, and operation of the second photocoupler34stops. As a result, the signal of the converter control device37stops being transmitted to the second transistor47of the DC-DC converter32, operation of the primary-side circuit44stops, and the output voltage of the secondary-side circuit45decreases to zero. Consequently, the power supply to each brake coil12stops, and a braking operation by the brake8is performed.

Even when an ON failure has occurred in the second power supply control circuit36, each of the first and second safety control CPUs51and52is configured to detect an abnormality and stop output of the control signal, which causes the power supply voltage of the first photocoupler34to fall below the threshold, and operation of the first photocoupler33to stop. As a result, the signal of the converter control device37stops being transmitted to the first transistor46of the DC-DC converter32, operation of the primary-side circuit44stops, and the output voltage of the secondary-side circuit45decreases to zero. Consequently, the power supply to each brake coil12stops, and a braking operation by the brake8is performed.

With such an elevator control apparatus21, the first and second transistors46and47of the half-bridge DC-DC converter32are independently operated under the control of the first and second photocouplers33and34, and the respective power supply voltages of each of the first and second photocouplers33and34are independently controlled by the first and second safety control CPUs51and52. As a result, operation of the DC-DC converter32can be stopped by stopping only one of any one of the first and second photocouplers33and34, which allows operation of the brake8to be more reliably controlled. Further, using the first and second photocouplers33and34allows contact points to be eliminated, and as a result, the occurrence of unwanted noise due to operation of the first and second photocouplers33and34can be prevented. In addition, using the first and second photocouplers33and34allows the size of the brake power supply device25to be reduced, and hence the size of the control apparatus21can be reduced.

Further, the first safety control CPU51is configured to perform a control for periodically varying the power supply voltage of the first photocoupler33so that operation of the first photocoupler33is not hindered, and to monitor the power supply voltage of each of the first and second photocouplers33and34. Further, the second safety control CPU52is configured to perform a control for periodically varying the power supply voltage of the second photocoupler34so that operation of the second photocoupler34is not hindered, and to monitor the power supply voltage of each of the first and second photocouplers33and34. As a result, an abnormality in the power supply voltage of each of the first and second photocouplers33and34can be detected more reliably, which allows the soundness of operation of the brake8to be even more reliably ensured.

Second Embodiment

FIG. 6is a configuration diagram for illustrating the main parts of an elevator control apparatus according to a second embodiment of the present invention. InFIG. 6, in this example, the DC-DC converter32is a full-bridge DC-DC converter. In other words, the primary-side circuit44of the DC-DC converter32includes a pair of first transistors (transistors on the upper arm (positive electrode) side)46, and a pair of second transistors (transistors on the lower arm (negative electrode) side)47. The first and second transistors46and47are the same as the first and second transistors46and47in the first embodiment.

Further, the brake power supply device25includes a pair of first photocouplers33for outputting drive signals (gate drive signals) to the pair of first transistors46in synchronization with each other, and a pair of second photocouplers34for outputting drive signals (gate drive signals) to the pair of second transistors47in synchronization with each other.

The pair of first transistors46are configured to perform an ON/OFF operation under the control of the drive signals (gate drive signals) from the first photocouplers33. The pair of second transistors47are configured to perform an ON/OFF operation under the control of the drive signals (gate drive signals) from the second photocouplers34. The primary-side circuit44is configured to convert direct-current power from the power conversion unit31into alternating-current power to be supplied to the primary-side coil41by alternately performing the ON/OFF operations of the pair of first transistors46and the ON/OFF operations of the pair of second transistors47. When the drive signal of at least any one of the first and second photocouplers33and34has stopped (has been cut), operation of the DC-DC converter32is stopped, and direct-current power stops being generated in the secondary-side circuit45.

The converter control device37is configured to control operation of each of the first photocouplers33and each of the second photocouplers34so that the drive signals from each of the pair of first photocouplers33and the drive signals from each of the pair of second photocouplers34are alternately output.

The first and second power supply control circuits35and36are configured to independently control the power supply voltages of the pair of first photocouplers33and the power supply voltages of the pair of second photocouplers34. In other words, the circuit configuration for controlling the power supply voltages of the pair of first photocouplers33and the power supply voltages of the pair of second photocouplers34has a dual circuit configuration. Other parts and operations are the same as in the first embodiment.

Thus, even when the DC-DC converter32is a full-bridge DC-DC converter, the same advantageous effects as in the first embodiment can be obtained by providing the same number of first and second photocouplers33and34as the number of first and second transistors46and47of the DC-DC converter32. In other words, operation of the brake8can be controlled more reliably, the occurrence of unwanted noise due to operation of the first and second photocouplers33and34can be prevented, and the size of the control apparatus21can be reduced.