Motor drive device

Abstract

To sufficiently cool a braking resistor while suppressing an increase in power consumption.SOLUTION: The motor drive device 1 includes an invertor unit 14, a regenerative power consumption unit 16 including a switch 15 and a braking resistance 5 connected in series between DC power source lines L1 and L2, a fan 8 capable of blowing air to the braking resistance 5, an invertor device 9 that drives the fan 8, a regenerative power detection unit 21 that detects generation of regenerative power, a regenerative power consumption control unit 22 that executes regenerative power consumption control at the time of regenerative power detection, and a regenerative power consumption control unit 23 that executes regenerative power consumption control. The inverter device 9 generates a driving power supply for driving the fan 8 by using the regenerative power, and generates the driving power supply by using other power when the regenerative power is not generated. The cooling control unit 23 executes the cooling control at the time of regeneration detection, and thereafter continues the execution of the cooling control for a certain period even if the generation of regenerative power is no longer detected by the regeneration detection unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a motor drive device. [Background technology]

[0002] For example, when a motor is used as a drive source for an elevator, crane, centrifuge, etc., there are periods of regenerative operation in which the motor is driven by a load, such as when the elevator or crane is descending, or when the centrifuge is decelerating to a stop, and regenerative power is generated during these periods. In motor drive devices that use an inverter or the like to drive such motors, the regenerative power generated during regenerative operation is consumed by a braking resistor, but there is a problem in that the heat released when the regenerative power is consumed causes the temperature of the braking resistor and the surrounding area to rise.

[0003] Therefore, in the motor drive device configured as described above, a blower such as an auxiliary fan is used to blow air onto the braking resistor to cool it. However, this requires additional power to drive the auxiliary fan, which creates another problem: increased power consumption. To solve this problem, a method of using regenerative power to drive the auxiliary fan to cool the braking resistor is conceivable. However, this method does not allow the auxiliary fan to be driven during periods when regenerative power is not being generated. If the braking resistor can only be cooled during periods when regenerative power is being generated, the braking resistor may not be sufficiently cooled because heat changes more slowly than power changes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-111109 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the present invention provides a motor drive device that can sufficiently cool a braking resistor while suppressing an increase in power consumption. [Means for solving the problem]

[0006] The motor drive device of this embodiment controls the drive of a motor and includes an inverter unit that converts direct current supplied from a pair of DC power supply lines into alternating current and supplies it to the motor, a regenerative power consumption unit including a switch and a braking resistor connected in series between the pair of DC power supply lines, a blower configured to be able to blow air toward the braking resistor, a blower drive unit that drives the blower, a regeneration detection unit that detects the generation of regenerative power, a regenerative consumption control unit that can perform regenerative consumption control to consume the regenerative power by controlling the on / off of the switch at the time of regeneration detection, which is when the generation of regenerative power is detected by the regenerative detection unit, and a cooling control unit that can perform cooling control to cool the braking resistor by controlling the operation of the blower drive unit to drive the blower.

[0007] The fan drive unit generates a drive power supply for driving the fan using regenerative power generated when the motor decelerates, and generates the drive power supply using other power when the regenerative power is not being generated. The cooling control unit executes the cooling control when the regeneration is detected, and continues to execute the cooling control for a certain period of time even if the generation of the regenerative power is no longer detected by the regeneration detection unit. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating a configuration of a motor drive device according to a first embodiment. [Figure 2] FIG. 1 is a functional block diagram illustrating the configuration of a control device according to a first embodiment. [Figure 3] FIG. 10 is a diagram showing an example of specific content of processing executed by the control device according to the first embodiment during regenerative operation. [Figure 4]FIG. 10 is a functional block diagram illustrating the configuration of a control device according to a second embodiment. [Figure 5] FIG. 10 is a diagram showing an example of specific content of processing executed by a control device according to a second embodiment during regenerative operation. [Figure 6] FIG. 10 is a diagram showing an example of specific content of processing executed by a control device according to a modified example of the second embodiment during regenerative operation. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments will be described with reference to the drawings. Note that substantially the same components in the respective embodiments will be denoted by the same reference numerals, and the description thereof will be omitted. (First embodiment) The first embodiment will be described below with reference to FIGS.

[0010] 1, motor drive device 1 of this embodiment controls the driving of motor 2 and includes inverter device 3, control device 4, braking resistor 5, power storage device 6, changeover switch 7, fan 8, and inverter device 9. Motor 2 is used as a drive source in, for example, elevators, cranes, and centrifuges.

[0011] The inverter device 3 functions as a main inverter device that drives the motor 2, and converts power input from a three-phase AC power supply 10 via terminals P1, P2, and P3 and outputs the converted power to the motor 2. The inverter device 3 includes a converter section 13 having a rectifier circuit 11 and a capacitor 12, an inverter section 14, and a switch 15. The rectifier circuit 11 is configured, for example, with diodes connected in a bridge configuration, and rectifies three-phase AC voltage, for example, R phase, S phase, and T phase.

[0012] The high-potential side output terminal of the rectifier circuit 11 is connected to the DC power supply line L1, and the low-potential side output terminal is connected to the DC power supply line L2. The capacitor 12 is connected between the pair of DC power supply lines L1 and L2, and smoothes the output of the rectifier circuit 11. With this configuration, the converter unit 13 converts the AC supplied from the AC power supply 10 into DC and outputs it via the pair of DC power supply lines L1 and L2.

[0013] Inverter unit 14 is configured with bridge-connected switching elements such as IGBTs and power MOS transistors. Each switching element of inverter unit 14 is driven by a drive circuit (not shown) that operates in accordance with a control signal output from control device 4. Inverter unit 14 converts the DC voltage applied via DC power supply lines L1 and L2 into a three-phase AC voltage having a predetermined frequency, for example, U-phase, V-phase, and W-phase, and supplies the AC voltage to motor 2, which is the target to be driven by motor drive device 1, via terminals P4, P5, and P6.

[0014] In this case, the DC power supply line L1 is connected to a terminal P7, and the DC power supply line L2 is connected to a terminal P8. The switch 15, together with a braking resistor 5 provided outside the inverter device 3, constitutes a regenerative power consumption unit 16. The switch 15 is formed of a semiconductor switching element such as an IGBT or a power MOS transistor. The on / off of the switch 15 is controlled by the control device 4.

[0015] One main terminal of the switch 15 is connected to one terminal of the braking resistor 5 via the terminal P9. The other main terminal of the switch 15 is connected to the DC power supply line L2. The other terminal of the braking resistor 5 is connected to the terminal P7. That is, the switch 15 and the braking resistor 5 are connected in series between the pair of DC power supply lines L1, L2. In this way, the regenerative power consumption unit 16 includes the switch 15 and the braking resistor 5 connected in series between the pair of DC power supply lines L1, L2.

[0016] The power storage device 6 is configured to store regenerative power generated as the motor 2 decelerates, and includes, for example, a battery, a capacitor, etc. Terminals P7 and P8 of the inverter device 3 are connected to the input terminals of the power storage device 6. With this configuration, the power storage device 6 can charge the battery, capacitor, etc. with DC power provided via the DC power supply lines L1 and L2 of the inverter device 3, and ultimately with the regenerative power described above. The operation of the power storage device 6 is controlled by the control device 4.

[0017] One input terminal of the changeover switch 7 is connected to terminals P7 and P8 of the inverter device 3. The other input terminal of the changeover switch 7 is connected to the output terminal of the power storage device 6. The changeover switch 7 is configured to be able to select one of two input terminals therein and connect it to the output terminal. In the following, the state in which one input terminal of the changeover switch 7 is connected to the output terminal will be referred to as a first changeover state, and the state in which the other input terminal is connected to the output terminal will be referred to as a second changeover state. The operation of the changeover switch 7 is controlled by the control device 4. The output terminal of the changeover switch 7 is connected to a power supply terminal of the inverter device 9.

[0018] The fan 8 is an example of a blower and is configured to be able to blow air to the braking resistor 5. In this case, the fan 8 is normally used to cool the inverter unit 14. The inverter device 9 is an example of a blower drive unit that drives the fan 8. The inverter device 9 generates a drive power supply that is a power source for driving the fan 8 using power supplied through a power supply terminal.

[0019] In this case, the inverter device 9 generates drive power using regenerative power generated as the motor 2 decelerates, and when the regenerative power is not being generated, generates drive power using other power, specifically power stored in the power storage device 6. When the selector switch 7 is switched to the first switching state, the inverter device 9 generates drive power using DC power provided through the DC power supply lines L1, L2 of the inverter device 3, and thus the regenerative power described above. When the selector switch 7 is switched to the second switching state, the inverter device 9 generates drive power using power stored in the power storage device 6.

[0020] The control device 4 is mainly configured with a microcomputer equipped with, for example, a CPU, RAM, ROM, etc., and controls the overall operation of the motor drive device 1 including the inverter device 3. In FIG. 1, the control device 4 is shown as being separate from the inverter device 3, but it may also be configured such that at least a portion of the configuration is included in the inverter device 3.

[0021] 2, the control device 4 includes functional blocks such as a regeneration detection unit 21, a regeneration consumption control unit 22, a cooling control unit 23, and a power storage control unit 24. Each of these functional blocks is realized by a CPU included in the control device 4 executing a computer program stored in a ROM or the like to perform processing corresponding to the computer program, that is, by software. Note that at least a portion of each functional block may be configured to be realized by hardware.

[0022] The regeneration detection unit 21 detects the generation of regenerative power and includes a voltage detection unit that detects the main INV DC voltage V1, which is the voltage between the DC power supply lines L1 and L2. In the following description, the main INV DC voltage V1 may be abbreviated as voltage V1. In this case, the regeneration detection unit 21 is configured to detect the generation of regenerative power when the detected value of voltage V1 is equal to or greater than a predetermined first threshold value Vth1 or equal to or greater than a predetermined second threshold value Vth2 during deceleration of the motor 2.

[0023] The first threshold Vth1 is set to a value higher than the steady-state value of the voltage V1 by a predetermined value and corresponds to a charge start voltage for starting execution of the power storage control described below. The second threshold Vth2 is set to a value higher than the first threshold Vth1 by a predetermined value and corresponds to a resistor drive start voltage for starting execution of the regenerative consumption control described below. The regenerative consumption control unit 22 can execute regenerative consumption control to consume regenerative power by controlling the on / off of the switch 15 upon regeneration detection, which is when the regenerative detection unit 21 detects the generation of regenerative power.

[0024] In this case, when the detected value of voltage V1 becomes equal to or greater than second threshold Vth2 during deceleration of motor 2, regenerative consumption control unit 22 executes regenerative consumption control. In regenerative consumption control, switch 15 of regenerative power consumption unit 16 is turned on. This places braking resistor 5 between DC power supply lines L1 and L2, and regenerative power generated during deceleration is consumed by braking resistor 5. After starting execution of regenerative consumption control, regenerative consumption control unit 22 stops execution of regenerative consumption control when the detected value of voltage V1 becomes less than second threshold Vth2.

[0025] The cooling control unit 23 can execute cooling control to cool the braking resistor 5 by controlling the operation of the inverter device 9 and driving the fan 8. In this case, the cooling control unit 23 executes cooling control when regeneration is detected, and continues executing cooling control for a certain period of time even after the generation of regenerative power is no longer detected by the regeneration detection unit 21. Specifically, the cooling control unit 23 executes cooling control when the detected value of the voltage V1 becomes equal to or greater than the second threshold value Vth2 during deceleration of the motor 2. In the cooling control, drive power is supplied from the inverter device 9 to the fan 8. This causes the fan 8 to blow air toward the braking resistor 5, cooling the braking resistor 5 and its surroundings.

[0026] The cooling control unit 23 controls the operation of the changeover switch 7 as follows. That is, when the detected value of the voltage V1 becomes equal to or greater than the second threshold value Vth2 during deceleration of the motor 2, the cooling control unit 23 switches the changeover switch 7 to the first switching state. As a result, the inverter device 9 generates drive power for driving the fan 8 using regenerative power generated as the motor 2 decelerates.

[0027] Furthermore, after starting the execution of cooling control, when the detected value of voltage V1 becomes less than second threshold Vth2, cooling control unit 23 switches selector switch 7 to the second switching state for the fixed period Ta from that point on. As a result, inverter device 9 generates drive power for driving fan 8 using the power stored in power storage device 6 for the fixed period Ta from the point on which the detected value of voltage V1 becomes less than second threshold Vth2. Note that the fixed period Ta may be set appropriately to a value that allows braking resistor 5 to be sufficiently cooled, taking into consideration the specifications of motor drive device 1 as a whole.

[0028] When regeneration is detected, the power storage control unit 24 can execute power storage control to store the regenerated power in the power storage device 6. In this case, the power storage control unit 24 executes power storage control when the detected value of the voltage V1 becomes equal to or greater than the first threshold value Vth1 during deceleration of the motor 2. In the power storage control, the operation of the power storage device 6 is controlled so that a battery, a capacitor, etc. are charged with regenerated power generated as the motor 2 decelerates.

[0029] Next, the specific contents of the processing executed by the control device 4 configured as above during regenerative operation will be described with reference to FIG. When the operation of the motor 2 is started, the control device 4 of the motor drive device 1 executes a series of processes as shown in Fig. 3. In step S101, it is determined whether the detected value of the voltage V1 is equal to or greater than a first threshold value Vth1 corresponding to a charging start voltage. If the detected value of the voltage V1 is less than the first threshold value Vth1, the result in step S101 is "NO," and step S101 is executed again.

[0030] On the other hand, if the detected value of voltage V1 is equal to or greater than the first threshold Vth, the result in step S101 is "YES" and the process proceeds to step S102. In step S102, execution of power storage control is started. After execution of step S102, the process proceeds to step S103. In step S103, it is determined whether the detected value of voltage V1 is equal to or greater than the second threshold Vth2. Here, if the detected value of voltage V1 is less than the second threshold Vth2, the result in step S103 is "NO" and the process returns to step S101. On the other hand, if the detected value of voltage V1 is equal to or greater than the second threshold Vth2, the result in step S103 is "YES" and the process proceeds to step S104.

[0031] In step S104, the execution of regenerative consumption control is started. Also in step S104, the selector switch 7 is switched to the first switching state, and the execution of cooling control is started. After step S104 is executed, the process proceeds to step S105. In step S105, it is determined whether the detected value of voltage V1 is less than the second threshold value Vth2. Here, if the detected value of voltage V1 is equal to or greater than the second threshold value Vth2, the result in step S105 is "NO," and step S105 is executed again. On the other hand, if the detected value of voltage V1 is less than the second threshold value Vth2, the result in step S105 is "YES," and the process proceeds to step S106.

[0032] In step S106, the execution of the regenerative consumption control is stopped. Also, in step S106, the selector switch 7 is switched to the second switching state, and the execution of the cooling control is continued. After step S106 is executed, the process proceeds to step S107. In step S107, it is determined whether or not the fixed period Ta has elapsed. Here, if the fixed period Ta has not elapsed, the result in step S107 is "NO," and step S107 is executed again. On the other hand, if the fixed period Ta has elapsed, the result in step S107 is "YES," and the process proceeds to step S108. In step S108, the execution of the cooling control is stopped. After step S108 is executed, the process returns to step S101.

[0033] According to the present embodiment described above, the following effects can be obtained. When regeneration is detected, the cooling control unit 23 controls the operation of the inverter device 9 to drive the fan 8, thereby executing cooling control to cool the braking resistor 5. At this time, the inverter device 9 generates a driving power supply for driving the fan 8 using regenerative power generated as the motor 2 decelerates. In this way, it is possible to effectively use the regenerative power that would otherwise be consumed by the braking resistor 5 to drive the fan 8 and cool the braking resistor 5, thereby suppressing an increase in power consumption.

[0034] Furthermore, the cooling control unit 23 continues to execute the cooling control for a certain period of time even if the regenerative power detection unit 21 no longer detects the generation of regenerative power after the execution of the cooling control has started. At this time, the inverter device 9 generates drive power using power other than the regenerative power. In this way, the braking resistor 5 can be cooled even during periods when no regenerative power is being generated. Therefore, according to this embodiment, the braking resistor can be sufficiently cooled while suppressing an increase in power consumption.

[0035] The motor drive device 1 of this embodiment includes a power storage device 6 that can store regenerative power generated as the motor 2 decelerates, and a power storage control unit 24 that can execute power storage control to store the regenerative power in the power storage device 6 when regeneration is detected. When no regenerative power is being generated, the inverter device 9 generates drive power using the power stored in the power storage device 6 as other power. In this way, even when no regenerative power is being generated, it is possible to effectively use previously generated regenerative power to drive the fan 8 and cool the braking resistor 5, further suppressing an increase in power consumption.

[0036] According to this embodiment, as described above, it is possible to reduce the power consumed by the braking resistor 5 and to sufficiently cool the braking resistor 5, so that it is possible to employ a braking resistor 5 having a relatively small rated power, heat capacity, etc., compared to braking resistors in the prior art, thereby enabling the downsizing of the braking resistor 5. Furthermore, in this embodiment, the fan 8 is a fan that is normally used to cool the inverter unit 14. Therefore, according to this embodiment, the number of parts can be reduced compared to a configuration in which a dedicated fan is provided for cooling the braking resistor 5, thereby enabling the device to be downsized.

[0037] (Second embodiment) A second embodiment in which the configuration of the control device is modified from that of the first embodiment will be described below with reference to FIGS. As shown in FIG. 4, the control device 31 of this embodiment differs from the control device 4 in that a temperature detection unit 32 is added and that a cooling control unit 33 is provided instead of the cooling control unit 23.

[0038] The temperature detection unit 32 detects a temperature T1 of the braking resistor 5 or its surroundings. The cooling control unit 33 executes cooling control, taking into consideration the value of the temperature T1 detected by the temperature detection unit 32. Specifically, the cooling control unit 33 executes cooling control when the value of the temperature T1 detected is equal to or higher than a predetermined threshold temperature Tth.

[0039] Next, the specific contents of the process executed by the control device 31 of this embodiment during regenerative operation will be described with reference to FIG. As shown in Figure 4, the specific processing content in this embodiment differs from the specific processing content in the first embodiment shown in Figure 3 in that step S201 is provided instead of step S104, steps S202 and S203 are added, and step S204 is added instead of step S107.

[0040] In step S201, only the execution of regenerative consumption control is started. After step S201 is executed, the process proceeds to step S202. In step S202, it is determined whether the detected value of temperature T1 is equal to or greater than threshold temperature Tth. If the detected value of temperature T1 is less than threshold temperature Tth, step S202 becomes "NO" and step S202 is executed again. On the other hand, if the detected value of temperature T1 is equal to or greater than threshold temperature Tth, step S202 becomes "YES" and the process proceeds to step S203.

[0041] In step S203, the selector switch 7 is switched to the first switching state, and the execution of cooling control is started. After step S203 is executed, the process proceeds to step S105. In step S204, it is determined whether the detected value of temperature T1 is less than threshold temperature Tth. If the detected value of temperature T1 is equal to or greater than threshold temperature Tth, the result in step S204 is "NO," and step S204 is executed again. On the other hand, if the detected value of temperature T1 is less than threshold temperature Tth, the result in step S204 is "YES," and the process proceeds to step S108.

[0042] According to the present embodiment described above, in addition to the same effects as those of the first embodiment, the following effect is also obtained. In this embodiment, the cooling control unit 33 executes cooling control while taking into consideration the detected value of the temperature T1 of the braking resistor 5 or its surroundings. Therefore, according to this embodiment, it is possible to cool the braking resistor 5 only at appropriate times when cooling is required, improving the efficiency of driving the fan 8 and contributing to a reduction in power consumption.

[0043] <Modification of the process executed by the control device 31 during regenerative operation> The processing executed by the control device 31 during regenerative operation can be modified as follows. That is, as shown in Fig. 6, the specific processing content in this modification differs from the specific processing content in the first embodiment shown in Fig. 3 in that step S204 is added instead of step S107. In this case, after step S106 is executed, the process proceeds to step S204.

[0044] In step S204, as described above, it is determined whether the detected value of temperature T1 is less than threshold temperature Tth. If the detected value of temperature T1 is equal to or greater than threshold temperature Tth, step S204 returns "NO" and step S204 is executed again. On the other hand, if the detected value of temperature T1 is less than threshold temperature Tth, step S204 returns "YES" and the process proceeds to step S108. According to this modification, the temperature of braking resistor 5 can be reduced to the target temperature.

[0045] (Other embodiments) The present invention is not limited to the embodiments described above and illustrated in the drawings, but can be modified, combined, or expanded as desired without departing from the spirit of the invention. The numerical values ​​and the like shown in the above embodiments are examples and are not limited to these.

[0046] When no regenerative power is being generated, the inverter device 9 generates a driving power supply by using the power stored in the power storage device 6 as other power, but this is not limited to this, and the other power may be, for example, power from the AC power supply 10. The blower driving section that drives the fan 8, which is an example of a blower, is not limited to the inverter device 9, and can be changed as appropriate depending on the specifications of the blower.

[0047] In each of the above embodiments, the fan 8 that is normally used to cool the inverter unit 14 is used as the blower, but this is not limitative and a dedicated blower for cooling the braking resistor 5 may also be provided.

[0048] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied 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 within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0049] 1...motor drive device, 2...motor, 3...inverter device, 5...braking resistor, 6...energy storage device, 8...fan, 9...inverter device, 14...inverter section, 15...switch, 16...regenerative power consumption section, 21...regeneration detection section, 22...regenerative consumption control section, 23, 33...cooling control section, 24...energy storage control section, L1, L2...DC power supply line.

Claims

1. A motor drive device that controls the drive of a motor, an inverter unit that converts DC supplied from a pair of DC power supply lines into AC and supplies the AC to the motor; a regenerative power consumption unit including a switch and a braking resistor connected in series between the pair of DC power supply lines; a blower configured to be able to blow air toward the braking resistor; a blower driving unit that drives the blower; a regeneration detection unit that detects generation of the regenerative power; a regeneration consumption control unit that can execute regeneration consumption control to consume the regenerative power by controlling the on / off of the switch at the time of regeneration detection, which is when the generation of the regenerative power is detected by the regeneration detection unit; a cooling control unit that controls the operation of the fan driving unit to drive the fan, thereby performing cooling control to cool the braking resistor; Equipped with the fan driving unit generates a driving power supply that is a power supply for driving the fan using regenerative power generated when the motor is decelerated, and generates the driving power supply using other power when the regenerative power is not being generated, The cooling control unit executes the cooling control when the regeneration is detected, and continues to execute the cooling control for a certain period of time even if the regeneration detection unit no longer detects the generation of regenerative power.

2. a power storage device capable of storing regenerative power generated as the motor decelerates; a power storage control unit that can execute power storage control to store the regenerated power in the power storage device when the regeneration is detected; Furthermore, 2. The motor drive device according to claim 1, wherein the blower drive unit generates the drive power supply by using the electric power stored in the electric storage device as the other electric power when the regenerative electric power is not being generated.

3. 3. The motor drive device according to claim 1, wherein the fan is normally used to cool the inverter unit.

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