Elevator device and brake torque measurement method

Abstract

To restrict a reduction in the life of a power source, resulting from a brake torque inspection.SOLUTION: An elevator control device according to an embodiment includes a power source that supplies electric power to a motor that drives lifting / lowering of a car of an elevator device. The power source performs a switching operation at a first frequency when a car for carrying a user is lifted / lowered, and performs a switching operation at a second frequency lower than the first frequency when the car is lifted / lowered during brake torque measurement of a brake that restricts rotation of a motor.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] An embodiment of the present invention relates to an elevator apparatus, a brake torque measuring method, and a life estimation method. [Background technology]

[0002] Brake torque inspections are periodically conducted on the brakes used in elevator systems to check whether the desired torque is being obtained. In conventional inspections, the brake torque is measured by measuring the current of the motor that drives the elevator car to ascend and descend, the braking distance of the elevator car, etc.

[0003] This measurement is performed by making the motor generate a torque larger than that during normal elevator operation, which places a large load on the power supply that drives the motor, and therefore reduces the life of the power supply that drives the motor.

[0004] Various methods have been proposed for detecting the deterioration of the lifespan of components used in power supplies. However, there are no proposals for suppressing the reduction in the lifespan of power supplies caused by brake torque inspections. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7171832 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to suppress the reduction in the life span of a power supply caused by a brake torque inspection. [Means for solving the problem]

[0007] An elevator control device according to an embodiment for solving the above problems includes a power supply that supplies power to a motor that drives the lifting and lowering of a car of an elevator device. The power supply performs switching operation at a first frequency when the car is lifting and lowering to transport passengers, and performs switching operation at a second frequency lower than the first frequency when the car is lifting and lowering while measuring the brake torque of a brake that suppresses the rotation of the motor. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view of an elevator apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a control system of the elevator apparatus according to the present embodiment. [Diagram 3] FIG. 2 is a block diagram of a drive unit according to the embodiment. [Figure 4] FIG. 2 is a configuration diagram of an inverter according to the present embodiment. [Diagram 5] FIG. 2 is a configuration diagram of an oscillator circuit according to the present embodiment. [Figure 6] FIG. 2 is a physical block diagram of a control unit according to the present embodiment. [Figure 7] FIG. 2 is a functional block diagram of a control unit according to the present embodiment. [Figure 8] 5A and 5B are diagrams for explaining heat generation of switching elements of the inverter according to the embodiment. [Figure 9] 5A and 5B are diagrams for explaining heat generation of switching elements of the inverter according to the embodiment. [Figure 10] 5 is a flowchart for explaining a brake torque measurement process according to the present embodiment. [Figure 11] 6 is a flowchart for explaining a lifespan estimation process according to the embodiment. [Figure 12] 5 is a diagram for explaining a current waveform measured in brake torque measurement according to the embodiment. FIG. [Figure 13]5 is a diagram for explaining a current waveform measured in brake torque measurement according to the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the present embodiment will be described with reference to the drawings. In the description, an XYZ coordinate system consisting of mutually orthogonal X-axis, Y-axis, and Z-axis will be used as appropriate. The drawings and flowcharts used in the description of the present embodiment are merely examples.

[0010] The elevator system according to this embodiment includes a power supply (inverter) that supplies power to a motor that drives the elevator system's car to ascend and descend. The power supply performs switching operation at a first frequency during normal ascending and descending operation of the car, and performs switching operation at a second frequency lower than the first frequency during brake torque measurement. In addition, the elevator system according to this embodiment measures the on-voltage of the switching element and the current flowing through the switching element when the switching element is in the on-state while the power supply is performing switching operation with a clock of the second frequency, calculates the on-resistance of the switching element based on the measured current and voltage values, and estimates the time until the switching element reaches its end of life based on the calculated on-resistance value.

[0011] Fig. 1 is a perspective view of an elevator system 10 according to this embodiment. The elevator system 10 is disposed inside a hoistway 100 provided in a building such as a commercial facility or a residential facility. As shown in Fig. 1, the elevator system 10 includes a car 31, a counterweight 50, an elevator motor 40, guide rails 21 to 24, and a control panel 70 (elevator control device).

[0012] Each of the guide rails 21 to 24 is a member whose longitudinal direction is the Z-axis direction. The guide rails 21 and 22 are a pair of members for guiding the car 31 so as to be able to rise and fall freely. The guide rails 23 and 24 are a pair of members for guiding the counterweight 50 so as to be able to rise and fall freely. The guide rails 21 and 22 are arranged spaced apart from each other in the Y-axis direction. Similarly, the guide rails 23 and 24 are arranged spaced apart from each other in the Y-axis direction. In FIG. 1, the guide rails 23 and 24 of the counterweight 50 are arranged spaced apart from each other in the X-axis direction with respect to the guide rails 21 and 22 of the car 31. The arrangement of the guide rails 21 to 24 is not limited to the arrangement shown in FIG. 1.

[0013] The car 31 is a unit that accommodates passengers and moves them up and down the elevator shaft 100. The car 31 is disposed between the guide rails 21 and 22, and is attached to the guide rails 21 and 22 so as to be movable in the up and down direction.

[0014] An opening 31a for entering and exiting the interior is formed on the side surface on the +X side of the car 31. The opening 31a is closed or opened by a pair of doors 32 that move along the side surface of the car 31. The doors 32 are opened and closed by an opening / closing motor (not shown in FIG. 1).

[0015] The counterweight 50 is attached so as to be movable up and down relative to the guide rails 23 and 24. The weight of the counterweight 50 is adjusted to be a predetermined ratio to the weight of the car 31.

[0016] The lift motor 40 is a motor for lifting and lowering the car 31. The lift motor 40 is disposed at the upper part of the elevator shaft 100 such that the rotation axis is parallel to the Y axis. A pulley 42 is fixed to the rotation axis of the lift motor 40.

[0017] A wire 43 is wound around the pulley 42 of the lift motor 40. One end of the wire 43 is fixed to the car 31, and the other end is fixed to the counterweight 50.

[0018] The control panel 70 is disposed in the elevator shaft 100. The control panel 70 houses a control device for controlling the elevator motor 40, the equipment provided in the car 31, and the like.

[0019] 2 is a block diagram showing a control system of the elevator apparatus 10. The control system includes a control unit 80 and a drive unit 91 housed in a control panel 70, and an operation panel 36 provided in the car 31.

[0020] The operation panel 36 is provided on the inner wall surface of the car 31. The operation panel 36 is an interface for receiving destination floors and the like from users of the car 31. Users can register destination floors and the like of the car 31 and open and close the door 32 by operating the operation panel 36. The operation panel 36 is connected to a control unit 80 housed in the control panel 70 via a cable 44 shown in FIG. 1.

[0021] 2 drives the lift motor 40 by supplying power to the lift motor 40. The drive unit 91 drives the lift motor 40 based on an instruction from the control unit 80.

[0022] The control unit 80 controls the drive unit 91 based on input from the operation panel 36 or the call panel of each floor. For example, when the control unit 80 rotates the lift motor 40 in the forward direction via the drive unit 91, the car 31 rises and the counterweight 50 descends. When the control unit 80 rotates the lift motor 40 in the reverse direction via the drive unit 91, the car 31 descends and the counterweight 50 rises.

[0023] FIG. 3 is a block diagram of the drive unit 91. The drive unit 91 has a converter 11 and an inverter 13. The converter 11 is a power supply device that converts an AC voltage supplied from the commercial power supply 1 into a DC voltage. The converter 11 is configured with a switching regulator. In this embodiment, the converter 11 supplies a voltage that is positive and a voltage that is negative with respect to the earth potential to the inverter 13. The inverter 13 is a power supply device that converts the DC voltage supplied from the converter 11 into an AC voltage of a predetermined voltage at a predetermined frequency, and supplies power to the lift motor 40. The inverter 13 is configured with a switching regulator.

[0024] FIG. 4 is a circuit example of the inverter 13. The inverter 13 has a switching element 132 and an oscillation circuit 134. FIG. 4 is a circuit example of a three-phase full-bridge inverter, and therefore has six switching elements 132. The switching elements 132 are composed of transistors, FETs (Field Effect Transistors), insulated gate bipolar transistors (IGTBs), or the like. The oscillation circuit 134 supplies a clock of a predetermined frequency to the bases (gates in the case of FETs) of the switching elements 132. A direct current voltage output by the converter 11 is applied between the terminals P1 and P2. The switching element 132 is in an ON state during a period when the clock supplied to the base is at a high level, and in an OFF state during a period when the clock is at a low level. The inverter 13 controls the output power (output current) by changing the duty (time ratio of high level to low level) of the clock applied by the oscillation circuit 134 to the bases of the switching elements 132. The oscillator circuit 134 changes the duty of the clock it outputs based on the control of the control unit 80. A three-phase AC current (three-phase AC voltage) is output to terminals P3, P4, and P5. The terminals P3, P4, and P5 are connected to the lift motor 40.

[0025] When monitoring the current supplied from the inverter 13 to the lift motor 40, the output of the inverter 13 is monitored using a current monitor 137. The current monitor 137 is disposed on the output side of the inverter 13 shown in FIG. 4, and measures the output current of each of the three phases. For example, a current probe is used as the current monitor 137. When monitoring the voltage between the source and emitter of each of the switching elements 132, a voltage monitor 138 is used to monitor the voltage between the source and emitter of each of the switching elements 132. The current monitor 137 and the voltage monitor 138 are attached only during measurement and are removed when the elevator system is in operation.

[0026] FIG. 5 is a configuration diagram of the oscillation circuit 134. The oscillation circuit 134 includes a first oscillation circuit 1341, a second oscillation circuit 1342, and a switching circuit 1343. The first oscillation circuit 1341 outputs a clock of a first frequency. The first frequency is, for example, 8 kHz. The second oscillation circuit 1342 outputs a clock of a second frequency lower than the first frequency. The second frequency is, for example, 1 kHz. For example, the second oscillation circuit 1342 outputs a clock of a second frequency lower than the first frequency by dividing the clock output by the first oscillation circuit 1341 by 8. When the switching circuit 1343 receives a signal indicating that it is time to measure the brake torque from the control unit 80, it switches from the output of the first oscillation circuit 1341 to the output of the second oscillation circuit 1342 and outputs the clock. The control unit 80 outputs a control signal for selecting a clock of a first frequency to the switching circuit 1343 during normal ascending and descending operation of the car 31, and outputs a control signal for selecting a clock of a second frequency to the switching circuit 1343 during brake torque measurement. Therefore, the switching element 132 performs switching operation at the first frequency during normal ascending and descending operation of the car 31, and performs switching operation at the second frequency lower than the first frequency during brake torque measurement.

[0027] 6 is a physical block diagram of the control unit 80. The control unit 80 is a computer having a CPU (Central Processing Unit) 81, a main memory 82, an auxiliary memory 83, and an interface 84, which are interconnected via a bus 85. The CPU 81 executes the processes described below according to a program stored in the auxiliary memory 83. The main memory 82 has a RAM (Random Access Memory) and the like. The main memory 82 is used as a working area for the CPU 81. The auxiliary memory 83 has a non-volatile memory such as a ROM (Read Only Memory) and a semiconductor memory. The auxiliary memory 83 stores the programs executed by the CPU 81, various parameters, and the like.

[0028] The interface unit 84 has a serial interface, a parallel interface, a wireless LAN interface, etc. The operation panel 36 and the drive unit 91 are connected to the CPU 81 via the interface unit 84. In addition, an input / output device 93 composed of a keyboard, a display, etc. is connected to the interface unit 84.

[0029] 7 is a functional block diagram of the control unit 80. The control unit 80 includes a brake torque measuring section 72 and a life estimation device 76.

[0030] The brake torque measurement unit 72 measures the brake torque of the brake that suppresses the rotation of the lift motor 40 by changing the current supplied to the lift motor 40 while the switching frequency of the inverter 13 is switched to the second frequency. Specifically, the brake torque measurement unit 72 monitors the signal output from the rotation sensor 17 that detects the rotation of the lift motor 40, and measures the brake torque based on the current value received from the current monitor 137 when the signal indicating that the lift motor 40 has rotated is received. The output torque of the lift motor 40 when the lift motor 40 rotates is the value of the brake torque. It is known that the output torque of the lift motor 40 is proportional to the value of the current supplied to the lift motor 40. The value of the output torque of the lift motor 40 with respect to the value of the current supplied to the lift motor 40 is measured in advance and stored in the storage unit as, for example, a table. The brake torque measurement unit 72 acquires the value of the brake torque corresponding to the value of the current supplied to the lift motor 40 by referring to the table. Then, the brake torque measurement unit 72 outputs the acquired value of the brake torque to the input / output device 93.

[0031] The life estimation device 76 has an on-resistance calculation unit 77 and a life estimation unit 78. The on-resistance calculation unit 77 calculates the on-resistance of the switching element 132 based on the on-voltage of the switching element 132 and the current flowing through the switching element 132 when the switching element 132 is in an on-state while the inverter 13 is performing a switching operation at the second frequency. The life estimation unit 78 estimates the time until the switching element 132 reaches the end of its life based on the on-resistance value of the switching element 132 calculated by the on-resistance calculation unit 77. Then, the life estimation unit 78 outputs the determination result as to whether the switching element 132 has reached its life to the input / output device 93.

[0032] Here, the amount of heat generated by the switching element 132 will be described with reference to Figs. 8 and 9. Fig. 8 shows a clock supplied to the base (gate in the case of an FET) of the switching element 132. The switching frequency fsw is the inverse of the time T shown in Fig. 8 (fsw=1 / T). The current Ic shown in Fig. 9 is the current flowing from the collector to the emitter (drain to source in the case of an FET) of the switching element 132. The voltage V CE is the voltage between the collector and emitter (drain and source in the case of a FET). When the clock is at a high level, the switching element 132 is turned on, and a current flows between the collector and emitter (drain and source in the case of a FET).

[0033] When a high-level signal is applied to the base, the base voltage gradually rises as charge accumulates in the stray capacitance of the base (period t1 in Figure 9). As the base voltage rises, the voltage V between the collector and emitter CE gradually decreases, and the current Ic flowing from the collector to the emitter gradually increases. During the period t2 in FIG. 9, the switching element 132 is in the ON state. The voltage V CE is the on-voltage of the switching element 132, and the current Ic during the period t2 in FIG. 9 is the on-current of the switching element 132. When the signal applied to the base goes to a low level, the charge stored in the stray capacitance of the base is discharged, and the base voltage gradually drops (period t3 in FIG. 9). As the base voltage drops, the voltage V between the collector and emitter CE gradually increases, and the current Ic flowing from the collector to the emitter gradually decreases. During a period t4 in Fig. 9, the switching element 132 is in the off state, and the current Ic flowing from the collector to the emitter becomes zero.

[0034] The amount of heat generated by the switching element 132 is determined by the voltage V CE and the current Ic. Therefore, the switching element 132 does not generate heat during the period t4 in FIG. 9. The voltage V CEis, for example, about 0.1 V, so the amount of heat generated by the switching element 132 during the period t2 in FIG. 9 is small. However, during the periods t1 and t3 in FIG. 9, CE Since both the current Ic and the switching element 132 have large values, the amount of heat generated by the switching element 132 is large.

[0035] Here, the relationship between the switching frequency of the switching element 132 and the amount of heat generated by the switching element 132 will be described. The rate of change of the base voltage of the switching element 132 is determined by the driving capability of the switching element 132 and the circuit that supplies a clock to the base. Therefore, the period t1 and the period t3 (rise time and fall time) in FIG. 9 are the same regardless of the switching frequency. If the switching frequency is lowered, the period t2 and the period t4 in FIG. 9 become longer, and if the switching frequency is increased, the period t2 and the period t4 in FIG. 9 become shorter. Therefore, the value of (t1+t3) / T changes depending on the switching frequency. The smaller the value of (t1+t3) / T, the shorter the time during which heat is generated per unit time becomes, so the amount of heat generated by the switching element 132 becomes smaller. Therefore, the temperature rise of the switching element 132 also becomes smaller. The greater the amount of heat generated by the switching element 132, the higher the temperature becomes. Since the higher the temperature, the greater the thermal acceleration when calculating the lifespan, the higher the temperature becomes, the greater the degree of lifespan reduction of the switching element 132 becomes.

[0036] Next, the brake torque measurement process will be described with reference to the flowchart shown in Fig. 10. The following control is performed based on a program stored in the auxiliary storage unit 83, and is mainly controlled by the control unit 80 (CPU 81). A current monitor 137 is arranged on the output side of the inverter 13 as shown in Fig. 4. The arranged current monitor 137 measures the current supplied from the inverter 13 to the lift motor 40, and notifies the control unit 80 of the measurement value. In addition, the rotation sensor 17 measures the rotation of the lift motor 40, and notifies the control unit 80 of the measurement value.

[0037] The control unit 80 outputs a control signal to the switching circuit 1343 to select a clock of the first frequency during normal ascending and descending operation of the car 31. The control unit 80 outputs a control signal to the switching circuit 1343 to select a clock of the second frequency during brake torque measurement (step S11). During brake torque measurement, a current larger than that during normal ascending and descending operation of the car 31 is supplied to the lift motor 40. The amount of heat generated by the switching element 132 of the inverter 13 also increases according to the current supplied to the lift motor 40. In order to suppress this temperature increase, during brake torque measurement, the switching frequency of the switching element 132 is set to a second frequency (e.g., 1 kHz) lower than the first frequency (e.g., 8 kHz), which is the switching frequency during normal ascending and descending operation of the car 31.

[0038] The control unit 80 also sets the brake setting of the lift motor 40 to the one-side closed setting (step S12). The brake is, for example, a disc brake, and the brake is applied by pressing the rotating shaft of the lift motor with the disc brake. The car 31 is provided with two brakes for safety. The one-side closed setting refers to a setting in which one of the two brakes is enabled and the other brake is not applied. After measuring the brake torque for one brake, the brake torque for the other brake is also measured.

[0039] Next, the control unit 80 controls the inverter 13 so that the current supplied to the lift motor 40 gradually increases (step S13). The control unit 80 controls the inverter 13 so that the current supplied to the lift motor 40 gradually increases, for example, by increasing the duty (proportion of time during which the clock is at a high level) of the clock output by the second oscillation circuit 1342.

[0040] Next, the control unit 80 determines whether the lift motor 40 (hoist) has rotated (step S14). The rotation of the lift motor 40 is detected by a rotation sensor 17 that detects the rotation of the lift motor 40. The control unit 80 determines whether the lift motor 40 has rotated by monitoring a signal output from the rotation sensor 17.

[0041] If the control unit 80 does not detect that the lift motor 40 has rotated (step S14: No), it continues to increase the current supplied to the lift motor 40 (step S13). On the other hand, if the control unit 80 detects that the lift motor 40 has rotated (step S14: Yes), it proceeds to the process of step S15.

[0042] The control unit 80 records the current measurement value by the current monitor 137 when it is detected that the lift motor 40 has rotated (step S15).

[0043] Next, the control unit 80 refers to the table stored in the storage unit and obtains a brake torque based on the value of the current supplied to the lift motor 40 when the lift motor 40 rotates (step S16). The output torque of the lift motor 40 when the lift motor 40 rotates is the value of the brake torque. It is known that the output torque of the lift motor 40 is proportional to the value of the current supplied to the lift motor 40. The value of the output torque of the lift motor 40 relative to the value of the current supplied to the lift motor 40 is measured in advance and stored in the storage unit as, for example, a table. The control unit 80 refers to the table to obtain the value of the brake torque corresponding to the value of the current supplied to the lift motor 40.

[0044] Next, the control unit 80 judges whether or not the calculated brake torque value satisfies a predetermined reference value, and outputs the judgment result whether or not the brake torque value satisfies the reference value to the input / output device 93 (step S17).

[0045] The control unit 80 outputs a control signal for selecting the clock of the first frequency to the switching circuit 1343 (step S18), and ends the brake torque measurement process.

[0046] Next, the life estimation process will be described with reference to Fig. 11. Here, a case will be described where the life estimation of the inverter 13 is performed by estimating the life of the switching element 132, which has the largest MTBF (Mean Time Between Failure) among the components constituting the inverter 13. When measuring the on-voltage of the switching element 132 and the current flowing through the switching element 132 when the switching element 132 is in the on-state in the life estimation process, a current monitor 137 is arranged on the output side of the inverter 13 as shown in Fig. 4. In addition, a voltage monitor 138 is arranged so as to monitor the voltage between the source and emitter of each of the switching elements 132.

[0047] During normal ascending and descending operation of the car 31, the control unit 80 outputs a control signal for selecting a clock of the first frequency to the switching circuit 1343. During life estimation processing, the control unit 80 outputs a control signal for selecting a clock of the second frequency to the switching circuit 1343 (step S31). The processing of step S31 can also be the processing of step S11 in Fig. 10. Therefore, the life estimation processing can be performed simultaneously with the brake torque measurement processing.

[0048] Next, the on-resistance calculation unit 77 of the life estimation device 76 calculates the value of the current Ic flowing through each of the switching elements 132 and the voltage V CE The value of the current Ic flowing through each of the switching elements 132 is supplied to the life estimation device 76 by the current monitor 137. In addition, the value of the voltage V CE The value of Ic is supplied to the life estimation device 76 by the voltage monitor 138. The on-resistance calculation unit 77 calculates the value of the current Ic and the voltage V at, for example, an intermediate timing between (t1+t2) and (t3+t4) shown in FIG. CEThe current monitor 137 and the voltage monitor 138 acquire the value of the current Ic and the value of the voltage V by synchronizing with the clock output by the second oscillation circuit 1342. CE The timing for acquiring the value of may be acquired.

[0049] FIG. 12 shows the voltage V of the switching element 132 that performs a switching operation at the second frequency. CE This is an example of a waveform. Voltage V CE When the waveform transitions from low to high, it often exhibits ringing as shown in the figure. Although not shown in Figure 12, the voltage V CE The waveform may also ring when it transitions from a high level to a low level. The current Ic waveform often rings as well. During the period when the waveform has ringing, the value of the current Ic and the voltage V CE When the value of Ic is acquired, the data varies widely and the measurement accuracy decreases. The on-resistance calculation unit 77 calculates the current Ic and the voltage Vc at the intermediate timing between (t1+t2) and (t3+t4) shown in FIG. CE The timing Pm shown by the black circle in Figure 12 is the voltage V CE 1 shows an example of the timing for acquiring the value of the voltage V. Since the switching element 132 is switched at the second frequency during the brake torque measurement, CE The ringing of the current Ic does not continue until the intermediate timing of (t3+t4) shown in Fig. 12. Also, although not shown in the figure, the ringing of the current Ic does not continue until the intermediate timing of (t1+t2).

[0050] FIG. 13 shows the voltage V of the switching element 132 that performs a switching operation at the first frequency. CE 12 is an example of a waveform. For example, the first frequency (8 kHz) is eight times the second frequency (1 kHz). Note that the time axes in FIG. 12 and FIG. 13 are not the same. When switching element 132 at the first frequency, ringing may continue up to the middle of the waveform. Therefore, when switching element 132 is switched at the first frequency, the value of current Ic and voltage V CEIf values ​​of this magnitude are obtained, there is a risk that the data will vary significantly and the measurement accuracy will be reduced.

[0051] Next, the on-resistance calculation unit 77 calculates the on-resistance of the switching element 132 (step S33). When changing the current supplied to the lift motor 40, the control unit 80 controls the duty of the clock supplied to the switching element 132 of the inverter 13 so that the current value changes stepwise, for example, every second. The on-resistance calculation unit 77 calculates, for example, the average value of the on-resistance of the switching element 132 acquired during the same duty period (one second) (step S34). The on-resistance calculation unit 77 calculates the average value of the on-resistance of the switching element 132 every time the duty is changed and the current Ic changes. Note that when the life estimation process is performed in parallel with the brake torque measurement process, the current is gradually increased in steps S13 and S14, so the on-resistance of the switching element 132 is calculated for each increased current.

[0052] Next, the life estimation unit 78 estimates the time until the switching element 132 reaches the end of its life based on the obtained on-resistance value. The life estimation unit 78 sets a first threshold value and a second threshold value, and compares the obtained average on-resistance value with the first threshold value and the second threshold value. The first threshold value is an on-resistance value close to the on-resistance value at which the switching element 132 has not yet reached its life but is determined to have reached its life. The second threshold value is an on-resistance value at which the switching element 132 has reached its life. The value of the second threshold value of the on-resistance at which the switching element 132 has reached its life is set based on the specifications and design values ​​of the parts. The first threshold value is set so that the time it takes for the on-resistance to reach the second threshold value from the first threshold value is, for example, about two months.

[0053] First, the lifetime estimation unit 78 judges whether the calculated average value of the on-resistance is equal to or less than the first threshold value (step S35). If the calculated average value of the on-resistance is equal to or less than the first threshold value (step S35: Yes), the lifetime estimation unit 78 judges that the switching element 132 has time before reaching the end of its life (step S39).

[0054] On the other hand, if the calculated average value of the on-resistance is equal to or greater than the first threshold (step S35: No), the lifetime estimation unit 78 determines whether the calculated average value of the on-resistance is equal to or less than the second threshold (step S36). If the calculated average value of the on-resistance is equal to or less than the second threshold (step S36: Yes), the lifetime estimation unit 78 determines that the switching element 132 is nearing the end of its life (step S38).

[0055] The life estimation unit 78 estimates the time until the switching element 132 reaches the end of its life based on data indicating the increase characteristic of the on-resistance of the switching element 132 with respect to the operation time of the switching element. Specifically, data indicating the increase characteristic of the on-resistance of the switching element 132 with respect to the operation time of the switching element 132 is created in advance as a table and stored in a storage unit. The time until the on-resistance of the switching element 132 reaches a predetermined value is the remaining life of the switching element 132. The life estimation unit 78 refers to the table to calculate the remaining life corresponding to the measured on-resistance of the switching element 132. Then, the life estimation unit 78 displays the remaining life of the switching element 132 on the input / output device 93.

[0056] On the other hand, if the calculated average value of the on-resistance is equal to or greater than the second threshold value (step S36: No), the life estimation unit 78 determines that the switching element 132 has reached the end of its life (step S37). Then, the life estimation unit 78 displays a warning such as "The switching element 132 has reached the end of its life, so please replace the inverter 13" on the input / output device 93. This concludes the explanation of the life estimation process.

[0057] The current flowing through the switching element during brake torque measurement is larger than that during normal operation, and the amount of heat generated by the switching element is also large. The larger the amount of heat generated by the switching element, the larger the temperature acceleration coefficient for degradation. Therefore, the reduction in the lifespan of the switching element due to brake torque measurement cannot be ignored. The elevator device according to the embodiment switches the switching element 132 of the inverter 13 at a first frequency during the ascending and descending operation of the car for transporting passengers, and switches at a second frequency lower than the first frequency during brake torque measurement. The amount of heat generated by the switching element 132 is suppressed as the switching frequency is lower. Therefore, the elevator device according to the embodiment can suppress the reduction in the lifespan of the switching element 132 due to brake torque measurement.

[0058] The absolute rating of the switching element is determined taking into consideration the current during brake torque measurement, when the largest current flows, and the amount of heat generated by that current. Since the elevator apparatus according to the embodiment can reduce the amount of heat generated during brake torque measurement, switching elements with a small absolute rating can be selected as switching elements to be used in the inverter 13. Furthermore, since the amount of heat generated by the switching elements is small, the heat dissipation circuit for cooling the switching elements can be simplified. This allows the inverter 13 to be made smaller, leading to cost reductions.

[0059] Furthermore, the life estimation unit 78 of the elevator system according to the embodiment calculates the on-resistance of the switching element 132 based on the on-voltage when the switching element 132 is on and the current flowing through the switching element 132 when the inverter 13 is performing switching operation with a clock of the second frequency, and estimates the time until the switching element 132 reaches the end of its life based on the calculated on-resistance value. The second frequency is set taking into consideration the duration of ringing. Therefore, when the switching element 132 is switched at the second frequency, the ringing does not continue until the middle of the waveform. Therefore, when the switching element 132 is switched at the second frequency, the value of the current Ic and the voltage V CEBy acquiring the value of , the measurement accuracy of the on-resistance of the switching element 132 can be improved.

[0060] Moreover, the above-mentioned brake torque measurement process and life estimation process can be performed simultaneously. Therefore, the elevator apparatus according to the embodiment can improve the efficiency of maintenance work. In the brake torque measurement process, the current supplied to the hoist motor 40 is gradually increased from zero to the maximum current and measured. Therefore, the on-resistance of the switching element 132 can be measured in the entire current range, including the drive current during normal operation, so that the life estimation process can be performed accurately.

[0061] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. For example, in the above description, in steps S35 and S36, a case has been described in which the lifespan of the switching element 132 is judged based on the absolute value of the on-resistance of the switching element 132. However, the lifespan judgment of the switching element 132 does not need to be limited to this. For example, the time until the end of the lifespan of the switching element 132 may be estimated based on the degree of increase in the on-resistance at the time of measurement relative to the on-resistance at the start of use of the inverter 13 (initial on-resistance). Also, the time until the end of the lifespan of the switching element 132 may be estimated based on the degree of increase in the on-resistance measured this time relative to the on-resistance measured last time. This is because the switching element 132 has a characteristic that the on-resistance increases rapidly as the end of its lifespan approaches.

[0062] Alternatively, a graph may be created with the horizontal axis representing the current supplied to the lift motor 40 and the vertical axis representing the on-resistance of the switching element 132, and the graph at the time when the inverter 13 was first used or the graph at the time of the previous measurement may be compared with the graph at the time of the current measurement, and it may be determined that the switching element 132 has reached the end of its life, for example, when the degree of correlation becomes equal to or lower than a predetermined threshold. A threshold value may be set to a value corresponding to the degree of correlation in steps S35 and S36 of Fig. 11. This method evaluates the switching element 132 based on the degree of change in the on-resistance relative to an increase in current, and has the effect of being able to evaluate the characteristics of the switching element 132 including a current range (outside the range of acquired data) exceeding the current value at the time of the brake torque measurement.

[0063] In the above description, the first frequency for switching the switching element 132 is 8 kHz, and the second frequency is 1 kHz. However, the first frequency and the second frequency do not have to be limited to these frequencies. For example, the first frequency may be 50 kHz, 80 kHz, or other frequencies higher than those in the above embodiment. The second frequency may be any frequency that is not affected by ringing due to switching at timing Pm, which is the measurement timing of the current and voltage and is indicated by a black circle in FIG. 12. In the above description, the second oscillation circuit 1342 creates a clock of the second frequency by dividing the clock output by the first oscillation circuit 1341. However, the second oscillation circuit 1342 may create a clock of the second frequency without dividing the clock output by the first oscillation circuit 1341.

[0064] In the above description using Fig. 12, the voltage and current are measured once per switching cycle, but measurements may be performed multiple times per switching cycle. The acquired waveform may be converted into an analog-to-digital converter, and the average value of the data for which the voltage and current values ​​are within a predetermined range may be calculated. The variance of the data may be calculated, and the on-resistance may be calculated using data from the intermediate time during which the variance value is equal to or less than a predetermined value.

[0065] In the above description, the brake torque measurement process and the life estimation process are performed simultaneously. However, the brake torque measurement process and the life estimation process may be performed independently.

[0066] In the above explanation, the voltage monitor 138 and the current monitor 137, which monitor the voltage between the source and emitter of each switching element 132, are installed only during measurement and are removed when the elevator system is in operation. However, the current monitor 137 and the voltage monitor 138 may also be placed in the inverter 13 when the elevator system is in operation.

[0067] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0068] 1 Commercial power supply 10 Elevator equipment 11 Converter 13 Inverter 132 Switching element 134 Oscillator Circuit 1341 First Oscillator Circuit 1342 Second oscillator circuit 1343 Switching Circuit 137 Current Monitor 138 Voltage Monitor 17 Rotation Sensor 21~24 Guide rail 31 Car 31a opening 32 Door 36 Operation Panel 40 Lifting motor 42 Pulley 43 Wire 44 Cable 50 Counterweight 70 Control Panel 76 Life estimation device 77 ON resistance calculation section 78 Life estimation section 80 Control Unit 81 CPU 82 Main memory 83 Auxiliary storage 84 Interface section 85 Bus 91 Drive unit 93 Input / Output Devices 100 Hoistway

Claims

1. An elevator system including a power source for supplying power to a motor that drives the elevation and lowering of a car of the elevator system, The power source performs a switching operation at a first frequency when the elevator car is ascending or descending to transport users, and performs a switching operation at a second frequency lower than the first frequency when the elevator car is ascending or descending while measuring a brake torque of a brake that suppresses rotation of the motor. Elevator equipment.

2. The power source includes: a first oscillation circuit that outputs a clock having the first frequency; a second oscillation circuit that outputs a clock having a second frequency lower than the first frequency; a switching circuit that switches between an output of the first oscillation circuit and an output of the second oscillation circuit; a switching element that performs a switching operation in response to a clock selected by the switching circuit; having the switching circuit switches from the output of the first oscillation circuit to the output of the second oscillation circuit when receiving a signal indicating that it is time to measure brake torque.

2. The elevator system of claim 1.

3. a life estimation unit that calculates an on-resistance of the switching element based on an on-voltage when the switching element is in an on-state and a current flowing through the switching element while the power supply is performing a switching operation with a clock of the second frequency, and estimates a time until the switching element reaches the end of its life based on the calculated on-resistance value; 3. The elevator system of claim 2.

4. the life estimation unit estimates a time until the switching element reaches the end of its life based on data indicating an increase characteristic of an on-resistance of the switching element with respect to an operating time of the switching element; 4. The elevator system of claim 3.

5. a frequency switching step of switching a switching frequency of a power source that supplies power to a motor that drives the lifting and lowering of a car during brake torque measurement from a first frequency during the lifting and lowering operation of the car to transport passengers to a second frequency that is lower than the first frequency; a brake torque measurement step of measuring a brake torque of a brake that suppresses rotation of the motor by changing a current supplied to the motor while the switching frequency of the power supply is switched to the second frequency; A brake torque measuring method comprising:

6. a measuring step of measuring an on-voltage of the switching element and a current flowing through the switching element when the switching element is in an on-state with the switching frequency of the power supply switched to the second frequency; determining an on-resistance of the switching element based on the measured current and voltage; a lifetime estimation step of estimating a time until the end of the lifetime of the switching element based on the obtained on-resistance value; The brake torque measuring method according to claim 5 , further comprising:

7. a frequency switching step of switching a switching frequency of a power source that supplies power to a motor that drives the lifting and lowering of a car from a first frequency during the lifting and lowering operation of the car to transport passengers to a second frequency that is lower than the first frequency; a measuring step of measuring an on-voltage of the switching element and a current flowing through the switching element when the switching element is in an on-state with the switching frequency of the power supply switched to the second frequency; determining an on-resistance of the switching element based on the measured current and voltage; a lifetime estimation step of estimating a time until the end of the lifetime of the switching element based on the obtained on-resistance value; A life estimation method including:

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