Power converter, control method for power converter, and elevator

Abstract

To provide a power conversion device capable of reducing thermal stress in a semiconductor device constituting a main circuit, a control method for the power conversion device, and an elevator driven by the power conversion device.SOLUTION: A power conversion device (10, 11) includes a power conversion circuit (12) that includes a semiconductor device and supplies power to a load, and further includes a cooling device (50) that cools the semiconductor device, and a control device (9) that controls the power conversion circuit and the cooling device, and the control device operates the cooling device when operating the load or equipment driven by the load, and the control device reduces cooling by the cooling device before starting a transition from operation to stop of the load or the equipment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device in which the main circuit is composed of semiconductor devices, a control method for such a power conversion device, and an elevator in which the power conversion device is used. [Background technology]

[0002] When a power converter is in operation, semiconductor devices such as power semiconductor modules that make up the main circuit of a power converter experience a temperature increase due to the heat generated by the power semiconductor elements they contain.

[0003] In power conversion devices, semiconductor devices are mounted on heat sinks and equipped with cooling systems such as air cooling or water cooling to dissipate heat from the semiconductor devices. This prevents the junction temperature of the power semiconductor elements contained within the semiconductor device from exceeding acceptable limits. Furthermore, when the power conversion device stops operating, the temperature of the semiconductor device drops rapidly. As a result, thermal stress is generated in the semiconductor device due to the temperature difference between when the power conversion device is operating and when it is not.

[0004] When a load powered by a power converter repeatedly starts and stops, such as the motor in a hoisting machine that drives an elevator car, thermal stress is repeatedly generated in the semiconductor device. This thermal fatigue affects the lifespan of the semiconductor device.

[0005] As conventional techniques for mitigating thermal stress generated in semiconductor devices that constitute the main circuit of a power conversion device, the techniques described in Patent Documents 1 and 2 are known.

[0006] In the technology described in Patent Document 1, a heat dissipation plate is arranged on a heat sink, and a transistor and a diode in an inverter are fixed to an insulating substrate fixed to the heat dissipation plate. Cooling water supplied to the inverter flows through a pipe in the heat sink. When the inverter is driven and controlled, a valve provided in the pipe is opened to circulate the cooling water between the inverter and the radiator. When the inverter stops, the valve is closed to cut off the circulation of the cooling water. Thereby, a sudden temperature drop of the transistor and the diode is suppressed.

[0007] In the technology described in Patent Document 2, a cooling fan for cooling a switching element mounted on an inverter is installed near an inverter device that outputs AC power to an elevator drive motor. When starting the elevator, the elevator control device starts the operation of the inverter and drives the cooling fan. Further, when the operation of the elevator stops, that is, when the operation of the inverter stops, the elevator control device stops the cooling fan. Thereby, it is possible to prevent sudden temperature stress from being applied to the switching element heated by current conduction.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the above prior art, although the temperature change of the semiconductor element after the inverter stops becomes gentle, the temperature change when the inverter transitions from the operating state to the stop state is large. Therefore, it is difficult to effectively relieve the thermal stress.

[0010] Therefore, the present invention provides a power conversion device capable of relaxing thermal stress in a semiconductor device constituting a main circuit, a control method for the power conversion device, and an elevator driven by the power conversion device.

Means for Solving the Problems

[0011] In order to solve the above problems, a power conversion device according to the present invention includes a semiconductor device and is provided with a power conversion circuit for supplying power to a load, and includes a cooling device for cooling the semiconductor device, and a control device for controlling the power conversion circuit and the cooling device. When the load or a device driven by the load is in operation, the control device operates the cooling device, and before the load or the device starts to transition from operation to stop, the control device weakens the cooling by the cooling device.

[0012] In order to solve the above problems, a control method for a power conversion device according to the present invention is a control method for a power conversion device including a semiconductor device and provided with a power conversion circuit for supplying power to a load. When the load or a device driven by the load is in operation, the semiconductor device is cooled, and before the load or the device starts to transition from operation to stop, the cooling of the semiconductor device is weakened.

[0013] In order to solve the above problems, an elevator according to the present invention includes a car and a counterweight, a main rope for suspending the car and the counterweight in a hoistway, a hoisting machine for driving the main rope, an electric motor for driving the hoisting machine, and a power conversion device including a semiconductor device for supplying power to the electric motor. The power conversion device includes a cooling device for cooling the semiconductor device, and a control device for controlling the power conversion circuit and the cooling device. When the electric motor is in operation, the control device operates the cooling device, and before the electric motor starts to transition from operation to stop, the control device weakens the cooling by the cooling device.

Advantages of the Invention

[0014] According to the present invention, since the temperature change of the semiconductor device is suppressed, the thermal stress of the semiconductor device is relaxed.

[0015] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram showing the overall configuration of an elevator as an embodiment. [Figure 2] This is a cross-sectional view showing an example of an IGBT module that constitutes the power conversion circuit in the embodiment. [Figure 3] This is a flowchart showing the operation of the control device in the embodiment. [Figure 4] This waveform diagram shows the correspondence between the elevator car's speed curve and the operation of the cooling device in the embodiment. [Figure 5] This waveform diagram shows the time-dependent changes in heat sink temperature and fan speed during deceleration and stopping of the elevator car in the embodiment. [Modes for carrying out the invention]

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings, using the following examples.

[0018] In each figure, elements with the same reference number represent the same or similar functional components.

[0019] Figure 1 is a diagram showing the overall configuration of an elevator according to one embodiment of the present invention.

[0020] In elevator 1, the elevator car 6 and counterweight 7 are connected to one end and the other end of the main rope 5, respectively. The main rope 5 is wound around a traction sheave on a hoisting machine driven by a three-phase synchronous motor 105. As a result, the elevator car 6 and counterweight 7 are suspended within the hoistway. When the hoisting machine is driven by the three-phase synchronous motor 105, the traction sheave rotates, and the main rope 5 is frictionally driven, causing the elevator car 6 and counterweight 7 to move in opposite directions within the hoistway. For example, a permanent magnet synchronous motor is used as the three-phase synchronous motor 105.

[0021] The three-phase synchronous motor 105 is supplied with three-phase AC power of variable voltage and variable frequency by the following power conversion device.

[0022] This power conversion device includes a forward converter 10 (AC / DC converter) and a reverse converter 11 (DC / AC converter), each equipped with a power conversion circuit 12.

[0023] The forward converter 10 receives three-phase AC power from the commercial three-phase AC power supply 2 via the filter circuit 3. The forward converter 10 converts the input three-phase AC power into DC power and outputs this DC power.

[0024] The inverse converter 11 receives DC power from the forward converter 10. The inverse converter 11 converts the input DC power into three-phase AC power and outputs this three-phase AC power.

[0025] The three-phase AC power output by the inverter 11 is supplied to the three-phase synchronous motor 105 via the filter circuit 4.

[0026] The operation of the elevator car 6 is controlled by the control device 9, which controls the power converter and the brake device 30. The control device 9 detects the travel speed of the elevator car 6 based on the detection signal from the rotation detector 300, which detects the rotation of the three-phase synchronous motor 105, and controls the three-phase synchronous motor 105 by controlling the power converter so that the detected travel speed matches a predetermined speed command value.

[0027] The control device 9 generates a current command value to match the detected travel speed to a predetermined speed command value. Furthermore, the control device 9 generates a control command to the converter drive unit 40 so that the motor current detected by the current detectors 125, 126, and 127 (in Figure 1, for convenience, the three current detectors for the three phases are shown as one current detector) matches the current command value. The converter drive unit 40 switches and drives the power conversion circuit 12 according to the control command. In this way, the power conversion device is controlled.

[0028] In this embodiment, the power conversion circuit 12 has an arm in which an insulated-gate bipolar transistor (hereinafter referred to as "IGBT") and a freewheeling diode are connected in parallel, and this arm is connected in a three-phase bridge configuration. In this embodiment, one arm, or one phase of the upper and lower arms, is composed of one semiconductor device, i.e., a so-called IGBT module. In addition to the IGBT, other power semiconductor switching elements such as power MOSFETs may be used.

[0029] In this embodiment, the power conversion device includes a power conversion circuit 12 in which both the forward converter 10 and the reverse converter 11 are composed of an arm in which a power semiconductor switching element and a freewheeling diode are connected in parallel, thereby enabling the regeneration of power to the commercial three-phase AC power supply 2.

[0030] When the destination floor is registered by the operation command S, the control device 9 generates a speed curve (speed pattern) as the operating curve of the elevator car from the current stopping floor to the destination floor. The speed curve represents the time change of the elevator car's speed, i.e., the states of acceleration, rated speed operation, and deceleration operation of the elevator car. For example, the control device 9 generates a speed curve based on predetermined acceleration and deceleration values, as well as a rated speed value. Based on the generated speed curve, the control device 9 generates a speed command value.

[0031] The operation command S is, for example, a car call or a landing call. Alternatively, the control device 9 may generate a speed curve for the three-phase synchronous motor 105 that corresponds to the car speed curve, instead of the car speed curve.

[0032] When the moving elevator car 6 comes to a stop, the control device 9 transitions the brake device 30 from the released state to the braking state. The braking state of the brake device 30 is maintained while the elevator car 6 is stopped. When the stopped elevator car 6 starts moving, that is, when the elevator car 6 starts up, the control device 9 transitions the brake device 30 from the braking state to the released state.

[0033] When the elevator car 6 is started, the control device 9 performs so-called starting torque compensation control from the time the doors of the elevator car 6 begin to close until the brake device 30 transitions from the braking state to the release state. In the starting torque compensation control, the control device 9 calculates an unbalanced torque due to the weight difference between the elevator car 6 and the counterweight 7, based on the load of the elevator car 6 detected by the load sensor 200 provided on the elevator car 6. Furthermore, the control device 9 controls the power converter so that the three-phase synchronous motor 105 generates a motor torque that balances the calculated unbalanced torque. As a result, when the elevator car 6 is started, the sudden movement of the elevator car 6 when the brake device 30 transitions from the braking state to the release state is prevented.

[0034] The IGBT modules constituting the power conversion circuit 12 are mounted on a heat sink 51 to dissipate the heat generated by the IGBTs and freewheeling diodes from the IGBT modules to the outside. Furthermore, the power conversion device of this embodiment is equipped with an air cooling device 50 to improve the efficiency of heat dissipation from the IGBT modules. In this way, the embodiment ensures that the junction temperature of the IGBTs and freewheeling diodes does not exceed an allowable value while the power conversion device is operating.

[0035] In this embodiment, the cooling device 50 includes a blower fan and a fan motor that rotates the blower fan. The fan motor is driven by a fan drive unit 41, which includes a power supply for the motor. The control device 9 gives control commands to the fan drive unit 41 to control the rotation and stopping of the fan motor. In this way, the control device 9 controls the on / off operation of the cooling device 50. As will be described later, the control device 9 turns off the cooling device 50 before decelerating the moving elevator car 6. This improves the lifespan of the power converter.

[0036] The temperature sensor 53, shown by the dashed line in Figure 1 and Figure 2 (described below), will be described later as a modified example of the embodiment.

[0037] Figure 2 is a cross-sectional view showing an example of an IGBT module that constitutes the power conversion circuit 12 (Figure 1) in the embodiment.

[0038] The IGBT module has a copper metal base 501 that is in contact with the heat sink 51, and a resin case 502 that covers the metal base 501 and is bonded to the metal base 501 with an adhesive.

[0039] Inside the resin case 502, a ceramic insulating substrate 503 is placed on a metal base 501. A copper metal foil 504, patterned for wiring, is joined to one surface of the insulating substrate 503 by brazing or the like. A copper metal foil 505 is joined to almost the entire other surface of the insulating substrate 503 by brazing or the like.

[0040] The insulating substrate 503 is joined to the metal base 501 via a metal foil 505 using solder 509. Multiple semiconductor chips 506, 507, on which IGBTs and diodes are formed, as well as terminal electrodes 508, are joined to the metal foil 504 using solder 509. Furthermore, the multiple semiconductor chips 506, 507 and terminal electrodes 508 are wired to each other using aluminum metal wires 510.

[0041] The metal base 501 of the IGBT module, which is mounted on the heatsink 51, is in close contact with the heatsink 51 via thermal grease 550, which acts as a thermal compound. The IGBT module is fixed to the heatsink 51 by screws (not shown).

[0042] In Figure 2, the dashed line indicates the outer diameter of the fan provided by the cooling device 50. Thus, the cooling device 50 is positioned relative to the heat sink 51 such that airflow is generated in the spaces between the multiple fins 52 provided by the heat sink 51.

[0043] When the power converter operates to move elevator car 6 toward the destination floor, semiconductor chips 506 and 507 generate heat due to power loss. As a result, the junction temperature of semiconductor chips 506 and 507 rises, but the heat dissipation by the heat sink and cooling device 50 prevents the junction temperature from exceeding the allowable limit.

[0044] When the power converter stops to bring the elevator car 6 to its destination floor, power loss in the semiconductor chips 506 and 507 ceases, causing the junction temperature of the semiconductor chips 506 and 507 to decrease. At this time, due to the differences in thermal expansion coefficients of the multiple components constituting the IGBT module as described above, thermal stress is generated in the components and at the junctions between components, depending on the temperature difference of each component of the IGBT module as the elevator car 6 travels and stops. Therefore, as the elevator car 6 repeatedly travels and stops, thermal fatigue occurs, and if the thermal fatigue becomes excessive, the IGBT module will fail.

[0045] In contrast, in this embodiment, the point at which the cooling device 50 is turned off, i.e., the point at which the rotational drive of the blower fan is stopped, is controlled to be earlier than the point at which the elevator car 6 is decelerated, thereby reducing the temperature difference of the IGBT module when the elevator car 6 is in motion and when it is stopped. As a result, thermal stress in the IGBT module is alleviated, and the lifespan of the IGBT module is improved.

[0046] Figure 3 is a flowchart showing the operation of the control device 9 (Figure 1) in the embodiment. Refer to Figure 1 as appropriate.

[0047] When the control device 9 starts processing, it first inputs the operation command S in step S1.

[0048] Next, in step S2, the control device 9 calculates the speed curve (speed pattern) of the elevator car 6 from the current stopping floor to the destination floor, according to the destination floor registered by the driving command input in step S1.

[0049] Next, in step S3, the control device 9 sets the time to stop the fan of the cooling device 50 based on the speed pattern calculated in step S2. In this embodiment, the control device 9 sets the time at which it commands the fan drive unit 41 to stop the fan motor to a predetermined time before the time at which the speed curve transitions from rated speed to deceleration.

[0050] This predetermined time is set based on factors such as the time from when the fan drive unit 41 receives a stop command for the fan motor from the control device 9 until the fan stops rotating, and the temperature rise of the IGBT module during the period from when the fan drive unit 41 receives a stop command for the fan motor from the control device 9 until the deceleration of the elevator car 6 begins. Regarding the temperature rise of the IGBT module, the predetermined time is set so that the junction temperature of the semiconductor chips 506 and 507 does not exceed an allowable value.

[0051] This predetermined time is, for example, only a few seconds.

[0052] Next, in step S4, the control device 9 starts the elevator car 6 by using the converter drive unit 40 to start and control the operation of the power converter, and accelerates the elevator car 6 according to the speed curve.

[0053] Next, in step S5, the control device 9 drives the fan using the fan drive unit 41.

[0054] Next, in step S6, the control device 9 operates the elevator car 6 at the rated speed by controlling the operation of the power converter using the converter drive unit 40.

[0055] Next, in step S7, the control device 9 commands the fan drive unit 41 to stop the fan at the time set in step S3.

[0056] Next, in step S8, the control device 9 uses the converter drive unit 40 to control the operation of the power converter, thereby decelerating the elevator car 6 according to the speed curve.

[0057] Next, in step S9, the control device 9 commands the converter drive unit 40 to stop the operation of the power converter and to transition the brake device 30 from the open state to the braking state, thereby stopping the operation of the elevator car 6 according to the speed curve. After executing step S9, the control device 9 stops the series of processes.

[0058] Figure 4 is a waveform diagram showing the correspondence between the speed curve of the elevator car 6 and the operation of the cooling device 50 in the embodiment. The magnitude of the output current of the power converter and the temperature of the heat sink are also indicated.

[0059] In Figure 4, each waveform diagram, from top to bottom, represents the velocity curve, i.e., the velocity V of elevator car 6. car Time variation, magnitude I of the output current of the power converter S Time change, temperature T of heatsink 51 h The change over time, the operation of the cooling device 50, i.e., the wind speed V of the blower fan. fan This shows the time evolution.

[0060] Note T h and V fan In each waveform diagram, dashed lines indicate examples, and solid lines indicate comparative examples.

[0061] As the velocity curve shows, the elevator car 6 starts at time t0 and travels at a predetermined acceleration. At time t1, V carAfter reaching the rated speed, until time t3, the car 6 travels at the rated speed. At time t3, the car 6 shifts to decelerated travel, travels at a predetermined deceleration, and then stops at the destination floor at time t4. When the destination floor is registered during the stop, the car 6 starts at time t5 and travels at a predetermined acceleration. At time t6, V car After reaching the rated speed, the car 6 travels at the rated speed. Thereafter, the car 6 shifts to decelerated travel, travels at a predetermined deceleration, and stops at the destination floor.

[0062] When the car 6 is running (t0~t4), the power conversion device outputs a three-phase alternating current to the three-phase synchronous motor 105 that drives the hoist. Output current I S increases transiently and exceeds the peak value when the car 6 is accelerating (t0~t1). When the car 6 is running at the rated speed (t1~t3), I S becomes a constant value. When the car 6 shifts to decelerated travel (t3~t4), I S decreases. When the car 6 stops (t4), that is, when the power conversion device stops, I S becomes zero.

[0063] When the power conversion device outputs a three-phase alternating current to the three-phase synchronous motor 105, current flows through the IGBT module that constitutes the power conversion circuit 12. Therefore, since the IGBT module generates power loss, it generates heat. For this reason, as shown in the waveform diagram of T h when the car 6 is accelerating and running at the rated speed (t0~t3), the temperature of the IGBT module rises, and as shown in the waveform diagram of T h the temperature of the heat sink 51 rises.

[0064] When the car 6 decelerates (t3~t4), since I S decreases, the temperature of the IGBT module decreases, and as shown in the waveform diagram of T h the temperature of the heat sink 51 decreases. Note that the difference in T h between the examples and the comparative examples will be described later.

[0065] As described above (Figure 2), in this embodiment, a cooling fan is provided as a cooling device to prevent the junction temperature of the semiconductor chips 506 and 507 of the IGBT module from exceeding the permissible value. fan As shown by the dashed line in the waveform diagram, the cooling system 50 is turned off at time t2, before the moving elevator car 6 is decelerated.

[0066] Therefore, I S Due to the reduction of T h When the pressure begins to decrease (t3), the airflow from the cooling device 50 stops. As a result, heat dissipation from the heatsink 51 slows down.

[0067] V fan As shown in the waveform diagram (solid line), in the comparative example, the cooling device 50 is turned off at point t4 when the moving elevator car 6 decelerates and comes to a stop. Therefore, air is continuously blown by the cooling device while the elevator car 6 is decelerating. For this reason, S Due to the reduction of T h When the pressure begins to decrease (t3), heat dissipation from the heatsink 51 in the comparative example is as rapid as when the vehicle is running at its rated speed.

[0068] Comparing this example with the comparative example, the difference in heat dissipation from the heat sink 51 is evident. h As the waveform diagram shows, in the embodiment (dashed line), the period from when the elevator car 6 starts decelerating until it starts up (t3~t5), i.e., T h Examples (dashed line) of T during the period when it is reduced h The change in ΔTh is smaller than in the comparative example (ΔTh'). Therefore, in this embodiment, the temperature change of the IGBT module is reduced. As a result, thermal stress in the IGBT module is relieved.

[0069] Figure 5 is a waveform diagram showing the time variation of heat sink temperature and fan airflow velocity during deceleration and stopping of the elevator car in the embodiment. Note that Figure 5 is a partially enlarged view of the waveform diagram shown in Figure 4, before and after time point t3.

[0070] As shown in Figure 5, in the embodiment (dashed line), the heat sink temperature T is lower than in the comparative example (solid line) during the period from when the elevator car starts to decelerate until it stops (t3~t4). h The change is gradual.

[0071] Here, the heatsink temperature T h When T decreases, h The change ΔT is expressed by equation (1).

[0072]

number

[0073] In equation (1), T0 is the heat sink temperature T h This is the initial value of , and τ is the thermal time constant of the heatsink.

[0074] In this embodiment, the fan is stopped from the time the elevator car starts to decelerate until it comes to a complete stop (t3~t4) (V fan (=0). Therefore, the thermal time constant of the heatsink is larger compared to when the fan is running (comparative example). Consequently, in the embodiment, the heatsink temperature T is higher than in the comparative example. h (=T0e -t / τ The change in ) becomes gradual. Therefore, as can be seen from equation (1), the heat sink temperature T h Change ΔT(=T0-T) h ) becomes smaller than in the comparative example.

[0075] During the period from when the elevator car stops until it starts up (t4~t5 (Figure 4)), the fan is also stopped in the comparative example, therefore the heatsink temperature T in the embodiment is different. h The amount of change is equivalent to that of the comparative example. However, as mentioned above, during the period from when the elevator car starts to decelerate until it stops (t3~t4), the heat sink temperature T h The change in ΔT is smaller than in the comparative example, and as a result, in the embodiment, as shown in Figure 4, T h T in t3~t5 where T is reduced hThe change in temperature ΔT is reduced. In this case, the change in temperature of the IGBT module is also reduced. As a result, thermal fatigue in the semiconductor devices that make up the main circuits of the forward and reverse converters is alleviated, and the lifespan of the semiconductor devices is improved.

[0076] In this embodiment, as shown in Figures 4 and 5, the fan is stopped at time t2 before the elevator car 6 begins to decelerate. That is, the current I flowing through the power converter S The size begins to decrease, and the heatsink temperature T h The fan stops before point t3, when the voltage begins to decrease. h When the temperature begins to decrease, it is certain that the thermal time constant of the heatsink is increasing. Therefore, the temperature change of the IGBT module can be reliably reduced.

[0077] The fan is stopped at the time t3 when the elevator car 6 begins to decelerate, that is, when the current I flowing through the power converter is stopped. S The size begins to decrease, and the heatsink temperature T h It may also be at point t3 when the deceleration begins to decrease. In this case, when the speed command value transitions from the rated speed value to a predetermined deceleration value, the control device 9 commands the fan drive unit 41 to stop the rotation of the fan motor.

[0078] Next, we will describe a modified example of the above-described embodiment.

[0079] As shown in Figures 4 and 5, in this embodiment, if the cooling device 50 is turned off and the fan stops at time t2, which is before time t3 when the vehicle transitions to deceleration, the heat sink temperature T will be lowered between t2 and t3. h It rises. In the embodiment, T h t2 is set to a predetermined value so that t3 does not exceed the allowable junction temperature of the semiconductor chips 506 and 507 (Figure 2) provided by the IGBT module (step S3 in Figure 3).

[0080] If the surrounding environment of the power conversion device (in the embodiment, inside the elevator shaft or machine room) becomes hot due to the influence of ambient temperature, T hAs the temperature increases, the temperature of the IGBT module also increases. In contrast, in the modified example, the timing of turning off the cooling device 50 is controlled according to the ambient temperature to prevent the junction temperature of the semiconductor chips 506 and 507 (Figure 2) from exceeding an acceptable value.

[0081] In a modified example, as shown in Figures 1 and 2, the power converter is affected by the ambient temperature, and the external temperature of the IGBT module is T h It is equipped with a temperature sensor 53 that detects temperature. The control device 9 controls temperature based on the temperature detection signals Sa,Sb from the temperature sensor 53. h If it is determined that the temperature has exceeded a preset high-temperature threshold, the timing t2 for turning off the cooling device 50 is delayed from the setting value for normal temperature to the setting value for high temperature, which is later in time than the setting value for normal temperature.

[0082] As a result, the period from t2 to t3 is shortened, and the rise in the junction temperature of semiconductor chips 506 and 507 (Figure 2) during this period is suppressed. Therefore, it is prevented that the junction temperature of semiconductor chips 506 and 507 (Figure 2) exceeds the allowable value.

[0083] Alternatively, the temperature sensor 53 may directly detect the temperature of the surrounding environment of the power converter. In this case, the temperature sensor is installed in the surrounding environment (for example, in the machine room or elevator shaft), or inside the housing that houses the power converter.

[0084] According to the above-described embodiment and its modifications, when operating a load to which power output from a power conversion circuit 12 composed of an IGBT module, which is a semiconductor device, is supplied or equipment driven by the load, namely a three-phase synchronous motor 105 or elevator car 6, the cooling device 50 is operated, and the cooling device 50 is stopped before the transition from operation to stopping of the three-phase synchronous motor 105 or elevator car 6 begins, that is, before deceleration begins.

[0085] This suppresses temperature changes in the IGBT module, thereby easing thermal stress in the IGBT module. Consequently, the thermal fatigue life of the IGBT module is improved. Therefore, the reliability of power converters including IGBT modules, and elevators equipped with power converters, is improved.

[0086] Preferably, the point at which the cooling device is stopped is set based on the speed curve, which is the operating curve of the three-phase synchronous motor 105 or the elevator car 6. This makes it possible to suppress temperature changes in the IGBT module without the temperature of the IGBT module exceeding the allowable temperature (the maximum allowable value of the junction temperature).

[0087] In the embodiments and modifications described above, the fan is stopped at time t2 as shown in Figures 4 and 5, thereby stopping the cooling device 50. However, the invention is not limited to this, and the fan may be kept running by reducing its airflow speed. By reducing the cooling provided by the cooling device 50, including stopping the cooling device 50, temperature changes in the IGBT module can be suppressed. If the cooling operation is continued without stopping the cooling device 50, the temperature rise of the IGBT module between time t2 and t3 (Figures 4 and 5) can be suppressed.

[0088] It should be noted that the present invention is not limited to the embodiments and modifications described above, but includes various modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. In addition, it is possible to add, delete, or replace some of the configurations in the embodiments with other configurations.

[0089] For example, the following transformations are possible.

[0090] The cooling system may be a liquid-cooling system such as water cooling, or it may be equipped with heat pipes.

[0091] The semiconductor device that makes up the power conversion circuit may be a resin-molded power module, an IPM (Intelligent Power Module), or the like.

[0092] The power converter may be any of the following: an AC / DC converter, a DC / AC converter, a DC / DC converter, or an AC / AC converter (e.g., a matrix converter), or a combination of these.

[0093] The system equipped with a power conversion device is not limited to elevators; it may also include electric vehicles (automobiles, trains), etc.

[0094] The elevator may have a machine room, or it may be a so-called machine room-less elevator.

[0095] The semiconductor material of the power semiconductor element in the semiconductor device may be silicon (Si), or it may be a wide-bandgap semiconductor such as silicon carbide (SiC) or gallium nitride (GaN). [Explanation of symbols]

[0096] 1 Elevator 2 Commercial three-phase AC power supply 3,4 Filter Circuit 5 Main rope 6. 7 Counterweight 9 Control device 10. Forward conversion device 11 Inverse converter 12 Power Conversion Circuit 30 Brake system 40 Converter drive unit 41 Fan drive unit 50 Cooling device 51 Heatsink 52 fins 53 Temperature Sensor 105 Three-phase synchronous motor 125, 126, 127 Current detector 200 Load Sensor 300 RPM detector 501 Metal base 502 Resin Case 503 Insulating substrate 504, 505 Metal foil 506,507 Semiconductor chips 508 Terminal electrode 509 Solder 510 Metal Wire 550 Thermal grease

Claims

1. In a power conversion device that includes a semiconductor device and a power conversion circuit that supplies power to a load, A cooling device for cooling the semiconductor device, A control device that controls the power conversion circuit and the cooling device, Equipped with, The control device operates the cooling device when operating the load or the equipment driven by the load. The control device is characterized in that it reduces the cooling by the cooling device before initiating the transition from operation to shutdown of the load or equipment.

2. In the power conversion device according to claim 1, The control device controls the power conversion circuit based on the operating curve of the load or the equipment. The control device is characterized by setting a point in time to reduce the cooling by the cooling device based on the operating curve.

3. In the power conversion device according to claim 1, The aforementioned load is an electric motor, The control device is a power conversion device characterized by reducing the cooling by the cooling device before starting the deceleration of the electric motor.

4. In the power conversion device according to claim 2, The aforementioned load is an electric motor that drives the elevator car. A power conversion device characterized in that the aforementioned operating curve is the speed curve of the elevator car.

5. In the power conversion device according to claim 1, The aforementioned load is an electric motor that drives the elevator car. The control device is a power conversion device characterized by reducing the cooling by the cooling device before the elevator car starts to decelerate.

6. In the power conversion device according to claim 1, A power conversion device characterized in that the cooling device is equipped with a fan for blowing air.

7. In the power conversion device according to claim 1, A power conversion device characterized in that the semiconductor device is mounted on a heat sink.

8. In the power conversion device according to claim 1, The control device is characterized in that it reduces the cooling by the cooling device before the temperature of the semiconductor device begins to decrease in accordance with the transition from operation to shutdown of the load or the equipment.

9. In the power conversion device according to claim 1, A temperature sensor is provided outside the aforementioned semiconductor device. The control device is characterized by adjusting the timing at which the cooling by the cooling device is reduced according to the temperature detected by the temperature sensor.

10. A control method for a power conversion device that includes a semiconductor device and a power conversion circuit that supplies power to a load, When the aforementioned load or the equipment driven by the aforementioned load is in operation, the semiconductor device is cooled. A control method for a power conversion device, characterized in that the cooling of the semiconductor device is reduced before the load or equipment begins the transition from operation to shutdown.

11. A riding cage and counterweight, Within the elevator shaft, the main rope suspends the elevator car and the counterweight, A hoisting machine that drives the main rope, The electric motor that drives the hoisting machine, A power conversion device that supplies power to the motor, including a semiconductor device and a power conversion circuit that supplies power to the motor, In an elevator equipped with, The aforementioned power converter is A cooling device for cooling the semiconductor device, A control device that controls the power conversion circuit and the cooling device, Equipped with, The control device operates the cooling device when the electric motor is in operation. The elevator is characterized in that the control device reduces the cooling by the cooling device before initiating the transition from operation to stop of the electric motor.

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