Method for cooling a device, and device for carrying out the cooling method

Abstract

The invention relates to a method for cooling an apparatus, such as a motor drive or a universal power converter, the apparatus comprising a heat sink, electronics connected to the heat sink, a heat pipe connected to the heat sink, an intake air temperature measuring device and a cooling fan. According to the method, the driver determines whether the intake air temperature is below a first temperature threshold and operates the cooling fan in a low intake air temperature velocity state if the intake air temperature is below the first temperature threshold. The invention also relates to a device for carrying out the cooling method, such as a motor drive or a universal power converter.

Description

[0001] This application is a divisional application of a patent application with the invention name of "Method for Cooling Equipment and Equipment for Implementing the Cooling Method", application number 2022104781349, and application date April 29, 2022, filed by the applicant "Vacon Plc". Technical Field

[0002] The present invention relates to a method for cooling an equipment such as a motor drive or a general-purpose power converter, the equipment including a radiator, electronic devices connected to the radiator, heat pipes connected or integrated into the radiator, an intake air temperature measuring device, and a cooling fan. According to the method, the drive determines whether the intake air temperature is lower than a first temperature threshold, and if the intake air temperature is lower than the first temperature threshold, operates the cooling fan in a low intake air temperature speed state. The present invention also relates to an equipment for implementing the cooling method, such as a motor drive or a general-purpose power converter. Background Art

[0003] Forced air cooling is generally used to prevent overheating of electronic equipment. Usually, the heat-generating components of an electronic equipment (such as a motor drive or a general-purpose power converter) are connected to a radiator, and a fan is used to force air through the radiator. To make such a cooling system more effective, the radiator can be equipped with heat pipes. Since the thermal conductivity of a heat pipe is significantly better than that of a typical radiator material (such as aluminum), heat can be dissipated more effectively to the radiator and the surrounding air.

[0004] A heat pipe is a sealed container from which all the air has been removed and in which a vacuum or a partial vacuum is formed. The heat pipe is partially filled with a working fluid, which can be water. Water can be used because of its low cost and suitable heat transfer capacity. However, a disadvantage of water is that it freezes when the ambient temperature drops below zero degrees Celsius. Although the freezing of the heat pipe itself is not a major problem because the thermal energy dissipated from the heat source usually thaws the heat pipe, problems may occur when combining a forced cooling fan with a heat pipe at low ambient temperatures. Such cooling fans are usually controlled such that their fan speed is determined experimentally and represents a compromise value. While the fan speed must be high enough to keep the device cool, it must be low enough to prevent the heat pipe from freezing under cold ambient conditions. The fan speed (especially the predetermined lower speed limit of the fan) can depend on the characteristics of the cooling system, that is, on the characteristics of the fan, radiator, heat pipe, cooling channels, and / or loss-generating components of the equipment.

[0005] Under adverse conditions, forced cooling may accelerate the freezing of the heat pipe and counteract the thawing effect of the heat source. Once the fluid within the heat pipe is frozen, the cooling efficiency of the radiator is significantly reduced, and the device cooled by the radiator may overheat and / or cause an overheat trip. As a result, the performance of the motor drive may deteriorate, or the drive may be damaged. SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide improved methods and improved devices, such as motor drives or general power converters, which overcome the above problems. This object is achieved by the method according to claim 1 and the device according to claim 12.

[0007] The present invention provides a method for cooling a device such as a motor drive or a general power converter. The device includes a radiator, electronic components connected to the radiator, a heat pipe connected or integrated into the radiator, an intake temperature measuring device, and a cooling fan. The electronic components may include any hardware required to provide a fully functional motor drive or general power converter. The connection between the radiator on one side and the electronic components and the heat pipe on the other side may be direct or indirect contact between the components. The fan is arranged to blow ambient air from the outside of the drive, causing the air to pass through the inlet and flow towards the heat pipe and the outlet. According to the method, the drive determines whether the intake temperature is lower than a first temperature threshold. If the intake temperature is lower than the first temperature threshold, the drive operates the cooling fan in a low intake temperature speed state. The drive may include a certain controller and / or software implementation for performing the required method steps.

[0008] The present invention can identify cold ambient temperatures and accordingly limit the fan speed, such that even under ambient temperature conditions below zero degrees Celsius, the power loss of the cooling device can keep the fluid within the heat pipe in a liquid state. As a result, the present invention can avoid the adverse situation of the drive suffering from overheating failures at low ambient temperatures. When the drive operates at low ambient temperatures, the present invention prevents the heat pipe at the radiator from freezing.

[0009] In a preferred embodiment of the present invention, the first temperature threshold is close to the freezing temperature of the working fluid of the heat pipe, for example, 0°C ± 5°C.

[0010] In another preferred embodiment of the present invention, the driver determines whether the intake air temperature is higher than a second temperature threshold, and if the intake air temperature is higher than the second temperature threshold and the driver was previously operating in a low intake air temperature speed state, the driver operates the cooling fan in a high intake air temperature speed state. The high intake air temperature speed state may be characterized by a higher operating speed of the fan than in the low intake air temperature speed state. The second temperature threshold may be a temperature higher than the first temperature threshold. According to this embodiment, if the driver was previously operating in a low intake air temperature speed state, the fan may be operated in the low intake air temperature speed state at an ambient temperature between the two temperature thresholds. This means that if the heat pipe is exposed to low temperatures, the fan will operate at a lower speed even if the ambient temperature has risen above the first temperature threshold. Therefore, within the temperature range between the two thresholds, only a limited amount of energy is transferred from the heat pipe to the surrounding environment, and the risk of the heat pipe freezing can be further reduced. The two threshold temperatures are used as a hysteresis amount to avoid a situation where the fan mode constantly switches from one mode to another, and thus causes annoying audible noise from the fan.

[0011] In another preferred embodiment of the present invention, the second temperature threshold is higher than the first temperature threshold, specifically 5 °C higher. Therefore, according to this embodiment, within a temperature range such as between 0 °C and 5 °C, the fan can be operated in a low intake air temperature speed state to avoid freezing of the heat pipe. The actual temperature thresholds may vary by ±2 °C from the temperature thresholds currently mentioned. This example can be applied to a heat pipe filled with water as the working fluid. In the case where another working fluid is filled in the heat pipe, the temperature values may vary significantly from this example. The actual temperature thresholds depend on the freezing temperature of the working fluid used.

[0012] In another preferred embodiment of the present invention, the fan is operated at a predetermined low speed. The predetermined low speed may correspond to the fan being stationary or a certain low rotational speed of the fan.

[0013] In another preferred embodiment of the present invention, in the high intake air temperature speed state, the fan is operated according to a request from at least one of the electronic devices. The request from the electronic device may be a function of the temperature of the device, and the temperature may be measured by a controller of the driver. The request may generate a signal for controlling the fan speed, thereby achieving the required cooling of the electronic device.

[0014] In another preferred embodiment of the present invention, the working fluid of the heat pipe includes water, methanol, and / or acetone. Although water represents an inexpensive working fluid for the heat pipe, other suitable fluids may be used as alternatives.

[0015] In another preferred embodiment of the present invention, the ambient temperature measuring device is an external or internal thermometer.

[0016] In another preferred embodiment of the present invention, a plurality of cooling fans and a plurality of associated temperature measuring devices are provided, wherein if the intake air temperature measured by one of the temperature measuring devices is lower than a first temperature threshold, the driver operates all the cooling fans in a low intake air temperature speed state; and / or, if the intake air temperature measured by one of the temperature measuring devices is higher than a second temperature threshold and if the driver previously operated in a low intake air temperature speed state, the driver operates all the cooling fans in a high intake air temperature speed state; and / or, the fan speeds of the plurality of cooling fans are controlled independently of each other. The controller of the driver can be connected to the cooling fans and the temperature measuring devices such that it can evaluate the measurements of all the temperature measuring devices. The controller can control all the fans such that the first temperature measuring device indicating a temperature exceeding the threshold will trigger a change in the speed state of the fans.

[0017] In another preferred embodiment of the present invention, the heat pipe is partially filled with a working fluid and air has been removed from the heat pipe; and / or, the working fluid in the heat pipe can be at least partially frozen in the area near the fan.

[0018] The present invention also relates to a device, such as a motor driver or a general power converter, which includes a radiator, electronics connected to the radiator, a heat pipe connected to the radiator, an intake air temperature measuring device, and a cooling fan. The device is designed to perform the method currently described. Description of the Drawings

[0019] Other features, details, and advantages of the present invention are given in the claims and the following description of the drawings. The drawings show:

[0020] Figure 1 : The operating model of a heat pipe for cooling a motor driver according to the prior art when the ambient temperature is higher than 0 °C;

[0021] Figure 2 : The operating model of the heat pipe according to the prior art when the ambient temperature is lower than 0 °C and the cooling fan operates at full speed;

[0022] Figure 3 : The operating model of the heat pipe for cooling a motor driver operating according to the present invention; and

[0023] Figure 4 : The basic block diagram of the method currently described. Detailed Description

[0024] Figure 1Shows an operating model of a heat pipe 2 for cooling an electric motor drive when the ambient temperature is higher than 0°C. The heat pipe 2 is a sealed container from which air has been removed and in which a vacuum or near-vacuum has been formed. The heat pipe 2 is partially filled with a working fluid such as water. Water can be used because of its low cost and good heat transfer ability. However, when the ambient temperature drops below 0°C, the water may freeze. The freezing of the heat pipe 2 itself is not a problem because power loss from the heat source will generally thaw the heat pipe 2 or keep it thawed. However, problems occur when forced cooling, such as by a fan 3, is employed at low ambient temperatures. This forced cooling will accelerate the freezing of the heat pipe 2 and prevent the thawing of the heat pipe 2.

[0025] The heat pipe 2 can be part of an electrical application such as an electric motor drive. The evaporator 21 side of the heat pipe 2 can be in thermal contact with a heat sink 1 or other type of heat energy receiving substrate. At high ambient temperatures above 0°C, water can freely circulate within the heat pipe 2 between the evaporator 21 shown on the left side in the figure and the condenser 22 of the heat pipe 2 shown on the right side. The circulation is indicated by the arrows inside the heat pipe 2. The arrows outside the heat pipe 2 indicate the heat transferred to and from the heat pipe 2. A fan 3 can be provided to create forced convection at the condenser 22 side of the heat pipe 2, thereby increasing the heat transferred from the heat pipe 2 and into the surrounding ambient air.

[0026] Figure 2 Shows the heat pipe 2 under temperature conditions below 0°C and with the fan 3 operating at full speed. As shown inside the heat pipe 2, the working fluid of the heat pipe 2 freezes and restricts heat transfer between the evaporator 21 and the condenser 22. The restricted heat transfer may cause damage to overheated devices that need to be cooled. The high-speed fan 3 pushes cold ambient air towards the heat pipe 2 and further cools it, exacerbating the problem.

[0027] Figure 3 Shows an operating model of a heat pipe 2 for cooling an electric motor drive operating under temperature conditions below 0°C and according to the present invention. The drive includes a heat sink 1, electronic devices connected to the heat sink 1, a heat pipe 2 also connected to the heat sink 1, an intake temperature measuring device, and a cooling fan 3. The drive can include a certain controller or computer for determining whether the intake temperature is below a first temperature threshold T inletAirLow1 and, if the intake temperature is below the first temperature threshold T inletAirLow1 , for operating the cooling fan 3 in a low intake temperature speed state. The first temperature threshold T inletAirLow1 can be 0°C, especially when water is used as the working fluid of the heat pipe 2.

[0028] As indicated by the decrease in the number of arrows pointing from the fan 3 towards the condenser 22, the speed of the fan 3 has been reduced by the driver. Consequently, the forced convection induced by the fan 3 and the additional cooling effect on the heat pipe 2 are diminished.

[0029] The driver can determine whether the intake air temperature is higher than a second temperature threshold T inletAirLow2 , and if the intake air temperature is higher than the second temperature threshold T inletAirLow2 and the driver was previously operating in a low intake air temperature speed state, then operate the cooling fan 3 in a high intake air temperature speed state. The second temperature threshold T inletAirLow2 can be 5°C. As a result, in the present embodiment, if the intake air temperature has previously reached sub-zero conditions, the driver can operate the fan in a low intake air temperature speed state at temperatures up to 5°C. This feature can ensure that the heat pipe 2 does not freeze under conditions where the driver operates at a temperature close to the freezing temperature of the working fluid of the heat pipe 2.

[0030] In the low intake air temperature speed state, the fan 3 can be operated at the lowest speed, which can correspond to the fan 3 being stationary or some lowest possible speed that the fan 3 can be controlled by the driver.

[0031] Conversely, in the high intake air temperature speed state, the fan 3 can be operated in response to a request from at least one of the electronics in the driver.

[0032] The ambient temperature measuring device can be an external or internal thermometer. The internal thermometer can be any temperature measuring device provided at or inside the driver that is capable of providing a reading indicating the temperature of the surrounding air or the intake air of the driver. The external thermometer can refer to any external temperature measuring device that can be connected to the driver and provide a corresponding reading.

[0033] In an embodiment not shown in the figures, multiple cooling fans 3 and multiple associated temperature measuring devices can be provided. If the intake air temperature measured by one of the temperature measuring devices is lower than a first temperature threshold T inletAirLow1 , then the driver can operate all the cooling fans 3 in a low intake air temperature speed state. Additionally or alternatively, if the intake air temperature measured by one or all of the temperature measuring devices is higher than a second temperature threshold T inletAirLow2 and if the driver was previously operating in a low intake air temperature speed state, then the driver can operate all the cooling fans 3 in a high intake air temperature speed state.

[0034] The present invention also relates to an electric motor drive, which includes a radiator 1, electronic devices connected to the radiator 1, a heat pipe 2 connected to the radiator 1, an intake air temperature measuring device, and a cooling fan 3. Among them, the drive is designed to execute the method currently described. In particular, the drive may include additional hardware devices and / or the drive may be programmed such that the method steps currently described can be executed by the drive.

[0035] Figure 4 A basic block diagram of the method currently described is shown. When starting to execute this method, the drive can be set to operate the fan 3 in the normal mode as the default setting (i.e., in the high intake air temperature speed state). The operation mode of the drive is designated as the variable FanControl. In this mode, the fan speed can be controlled based on the temperature and the corresponding cooling requirements of insulated gate bipolar transistors, rectifiers, and / or other devices of the drive.

[0036] The drive can monitor the intake air temperature sensor T used as the intake air temperature measuring device inletAir . This intake air temperature sensor T inletAir can have a resolution selected to be ≤1 °C, and it can measure in the range of -40 to 100 °C. If it is found that the intake air temperature is lower than the first temperature threshold T inletAirLow1 (for example, 0 °C), then the FanControl variable can be set to 0, and the drive will control the fan to operate at a predetermined low speed. This method can continuously and / or at a given time point verify whether the intake air temperature remains below zero.

[0037] If it is found that the intake air temperature is no longer lower than 0 °C, then the FanControl variable can remain 0 until the intake air temperature is higher than the second temperature threshold T inletAirLow2 (for example, 5 °C).

[0038] The present invention changes the topology of the main fan 3 speed control of the drive according to the intake air temperature of the fan 3. In parallel power units, multiple intake air measurements are made at the inlets of multiple fans 3, and all power units can measure their own intake air temperatures. The fan 3 can be controlled, for example, according to the first measurement value that reaches the fan 3 control temperature threshold.

[0039] All the features and advantages described in the claims, the specification, and the drawings (including structural details, spatial arrangements, and process steps) can act on the present invention individually and in all possible combinations.

[0040] List of reference numerals

[0041] 1 Radiator

[0042] 2 Heat pipe

[0043] 3 fans

[0044] 21 evaporator

[0045] 22 condenser

[0046] T inletAir Intake air temperature sensor

[0047] T inletAirLow1 First temperature threshold

[0048] T inletAirLow2 Second temperature threshold.

Claims

1. A method for cooling a device such as a motor drive or a general power converter, the device comprising a heat sink, electronic components thermally connected to the heat sink, heat pipes thermally connected to the heat sink, an intake temperature measuring device, and a cooling fan, characterized in that: - the device dynamically adjusts the cooling fan speed based on a multi-threshold temperature control strategy; - When the intake air temperature is lower than the first temperature threshold (T inletAirLow1 ), the cooling fan operates at a reduced speed to prevent overcooling of the heat pipe; - When the intake air temperature is higher than the second temperature threshold (T inletAirHigh1 ), the cooling fan operates in the high-speed state to ensure sufficient cooling of the electronic device; - the cooling fan speed is gradually adjusted between a first temperature threshold and a second temperature threshold to maintain the thermal stability of the heat pipes and the electronic components.

2. The method according to claim 1, wherein, The first temperature threshold (T inletAirLow1 ) is set within the range of 0°C ± 3°C, and the second temperature threshold (T inletAirHigh1 ) is set within the range of 5°C to 10°C above the first temperature threshold.

3. The method according to claim 1, wherein, the cooling fan speed is dynamically adjusted based on the real-time temperature gradient between the evaporator section of the heat pipe and the condenser section of the heat pipe.

4. The method according to claim 1, further comprising the steps of: temporarily increasing the cooling fan speed when a sudden increase in the heat dissipation requirement of the electronic components is detected, and if necessary, canceling the low-temperature fan speed state.

5. The method according to claim 1, further comprising: monitoring the temperature of the heat pipe at multiple points and adjusting the cooling fan speed to ensure that the heat pipe remains within the operating thermal range to prevent freezing or overheating.

6. The method according to claim 1, wherein, when the intake temperature is below the first temperature threshold, an auxiliary heating element is activated to supplement heat and prevent the heat pipe from freezing in an extremely cold environment.

7. The method according to claim 1, wherein, the device uses machine learning-based temperature prediction to anticipate freezing conditions and actively adjusts the cooling fan operation.

8. A device for implementing the cooling method according to claim 1, the device comprising: - a heat sink; - electronic components thermally connected to the heat sink; - heat pipes thermally connected to the heat sink; - an intake temperature measuring device; - a cooling fan; and - a control unit configured to perform the steps of the method according to claim 1.

9. The device according to claim 8, wherein, the control unit includes a microprocessor programmed to dynamically adjust the fan speed based on the intake temperature, the heat pipe conditions, and the electronic component heat load.

10. The device according to claim 8, wherein, a plurality of cooling fans are provided and each fan is independently controlled based on local intake temperature measurements to optimize the cooling efficiency across different parts of the device.

11. The device according to claim 8, further comprising: an ambient temperature compensation module that adjusts the fan operation based on external temperature trends to prevent the heat pipe from becoming too cold.

12. The device according to claim 8, wherein, the heat pipe contains a mixture of working fluids optimized for sub-zero operation to reduce the risk of freezing while maintaining efficient heat transfer characteristics.

13. The device according to claim 8, wherein, the control unit is configured to enter a fail-safe mode under extremely cold conditions by disabling the cooling fan or activating an auxiliary heating mechanism to maintain operational safety.

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