Patent Application
20160238284
1. Field of the Invention
The present invention relates generally to temperature control systems and more particularly, to an adaptive temperature control system for cooling working fluid.
2. Description of the Related Art
Upon testing electronic elements or electronic devices composed of electronic elements, such as wafers, integrated circuits, printed circuits, and so on, it is often important to obtain endurable temperatures of a device under test (hereinafter referred to as the “DUT”). This means the DUT has to be tested at various temperatures throughout a specific temperature range. Therefore, a temperature control system is necessary in the aforesaid testing process to control the temperature of the DUT as accurately as possible.
In a conventional temperature control system, a probe head controllable in temperature is adapted to directly contact a DUT disposed on a test socket so as to control the temperature of the DUT. However, only one surface of the DUT is contacted with the probe head, which is usually the top surface of the DUT; therefore, the temperature control system is difficult to provide a uniform temperature to the whole DUT.
In another conventional temperature control system, an airstream controllable in temperature is directed to the surrounding of a DUT so as to adjust the temperature of the DUT. Such temperature control system can provide not only a uniform temperature to the whole DUT, but also high stability and accuracy in temperature control, which is resulted from a temperature sensor located close to the DUT for obtaining the ambient temperature of the airstream to feedback control the output temperature of the airstream. However, in such temperature control system a cooling device driven by an AC generator is utilized to cool working fluid, i.e. the airstream, and an electric power with a frequency of 50 or 60 Hz is constantly applied to the cooling device. The electric power is usually not monitored in any parameter or unchangeable in any parameter even if it is monitored. Therefore, it often happens that the refrigerating capacity outputted from the cooling device is higher than demand, thereby causing energy waste. For example, the temperature control system may output working fluid with temperature of −60° C. under the frequency of 60 Hz of the electric power. If a required working temperature of the working fluid is set −20° C., the working fluid with the temperature of −60° C. will need to be heated up by a heater. This consumes much energy.
The present invention has been accomplished in view of the above-noted circumstances. It is an object of the present invention to provide an adaptive temperature control system for cooling working fluid (gas or liquid), which can cool down the working fluid at a target temperature accurately so as to control the temperature of a DUT accurately and uniformly by means of the working fluid, or be applied in another process or system that requires the working fluid with accurate temperature.
To attain the above object, the present invention provides an adaptive temperature control system for cooling a working fluid, which flows in a pipe, at a target temperature set by a user. The adaptive temperature control system comprises a cooling device and a controller. The cooling device has a compressor, a condenser, an expander (ex. capillary), an evaporator, a coolant cyclically passing through the compressor, the condenser, the expander and the evaporator in order, and an inverter. The compressor has a motor. The condenser has a fan which helps dissipating heat of the coolant. The motor is electrically connected with the inverter. The coolant in the evaporator is functioned to thermally exchange with the working fluid, thereby cooling the working fluid. The controller has a plurality of input ports for receiving a plurality of system parameters respectively, and a first output port electrically connected to the inverter for enabling the controller to transmit a signal for controlling a rotary speed of the motor of the compressor to the inverter according to the system parameters. The system parameters may comprise the target temperature, a temperature in the evaporator, a mass flow of the working fluid in the pipe, an inlet pressure of the compressor, and an outlet pressure of compressor.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Referring to
The adaptive temperature control system 10 is adapted for cooling the working fluid 60, which is gas or liquid flowing in a pipe 70 and directed to a DUT 80, at a target temperature set by a user. In other words, the working fluid 60 is adapted to adjust the temperature of the DUT 80 after being cooled by the adaptive temperature control system 10. However, the adaptive temperature control system of the present invention is not limited to be adapted for controlling the temperature of the DUT, but may be applied in another process or system that requires the working fluid with accurate temperature.
The cooling device 20 has similar fundamental principle to a conventional refrigeration sys and primarily comprises a compressor 21, a condenser 22, an expander 3, an evaporator 24, a coolant 25 cyclically passing through the compressor 21, the condenser 22, the expander 23 and the evaporator 24 in order, and two inverters 26, 27. For the coolant 25, commercially available coolants or a mixture of at least two of commercially available coolants can be used depending on usage requirements.
The compressor 21 has a motor 212 electrically connected with the inverter 26 and controllable in rotary speed by the inverter 26. In this embodiment, the inverter 26 is electrically connected with the power source 50 through the PFC 40. For the PFC 40, a commercially available integrated circuit capable of correcting power factor can be used. The PFC 40 is capable of receiving input AC power having a wide voltage range, operating in a wide frequency range, and outputting DC power having constant voltage. The PFC 40 is adapted to receive AC power from the power source 50, which may be, but not limited to, public supply mains used in worldwide areas, and output DC power to the inverter 26 so as to drive the motor 212.
The compressor 21 is powered by the motor 212 to compress gaseous coolant 25 with low temperature and low pressure, thereby outputting gaseous coolant 25 with high temperature and high pressure and driving the coolant 5 to flow cyclically. The condenser 22 is adapted to dissipate heat of the gaseous coolant 25 with high temperature and high pressure by means of a cooling medium, e.g. air, thereby outputting liquid coolant 25 with moderate temperature and high pressure. Besides, the condenser 22 has a fan 222 which helps dissipating the heat of the coolant 25. The expander 23, e.g. capillary, is adapted Co depressurize the liquid coolant 25 with moderate temperature and high pressure, thereby outputting liquid coolant 25 with moderate temperature and low pressure, so that the coolant 25 can absorb heat when passing through the evaporator 24 and thereby be vaporized to become gaseous coolant 25 with low temperature and low pressure. The coolant 25 in the evaporator 24 is functioned to thermally exchange with the working fluid 60 passing by the evaporator 24 in the pipe 70, thereby cooling the working fluid 60.
The controller 30 has a first output port 31, a second output port 32, and a plurality of input ports 33. The input ports 33 are adapted to receive a plurality of system parameters, respectively. The first output port 31 is electrically connected to the inverter 26 for enabling the controller 30 to transmit a signal for controlling the rotary speed of the motor 212 according to the received system parameters to the inverter 26, The second output port 32 is electrically connected to the inverter 27 for enabling the controller 30 to transmit a signal for controlling the rotary speed of the fan 222 according to the received system parameters to the inverter 27. It is to be understood that the cooling device 20 may be configured without having such inverter 27. In this case, the fan 222 that is switchable between several stages of rotary speed may be used. It is to be understood that the controller 30 may be allocated in the inverter 26 and/or the inverter 27.
The system parameters may optionally comprise the target temperature set by the user, a temperature in the evaporator 24, a mass flow of the working fluid 60 in the pipe 70, and inlet and outlet pressures of compressor 21. The usage of the system parameters quantity depends on the actual demand in use of the adaptive temperature control system 10, and it may be more than or less than and is not limited to the aforesaid system parameters. By means of the system parameters, the controller 30 can adjust the rotary speeds of the motor 212 of the compressor 21 and the fan 222 of the condenser 22 according to the instantaneous situation of the adaptive temperature control system 10, so that the working fluid 60 can be cooled at the target temperature accurately, and therefore the temperature of the DUT 80 can be accurately and uniformly controlled. The correlation between the aforesaid system parameters and the temperature of the working fluid will be specified in the following contents.
The target temperature is the temperature of the working fluid demanded to be outputted from the system to the DUT 80. If the temperature of the working fluid outputted from the cooling device 20 is close to the target temperature, it needs only a little additional adjustment by a heater (not shown), thereby causing relatively less energy waste to the heater. The optimal condition is that the temperature of the working fluid to be outputted from the cooling device 20 is lower than but very close to the target temperature after a transmission loss, and then the temperature of the working fluid is further adjusted to the target temperature by the heater when the working fluid is outputted.
The working fluid is thermally exchanged primarily when passing by the evaporator 24. Theoretically, after the working fluid passes by the evaporator 24, the temperature thereof is usually adjusted to be close to the temperature of the evaporator 24. Thus, the temperature in the evaporator 24 (internal temperature of the evaporator 24) should be included in the system parameters to be received by the controller 30 for controlling the temperature of the working fluid 60. For example, the controller shall speed up the motor 212 of the compressor 21 and the fan 222 of the condenser 22 when the target temperature is lower than the temperature in the evaporator 24 and slow down the motor 212 and the fan 222 when the target temperature is higher than the temperature in the evaporator 24.
When the working fluid outputted from the system is stable in temperature, it will have an increase in its temperature in the event that the mass flow of the working fluid increases because the heat taken away from the working fluid by the evaporator 24 maintains constant. In this condition, the motor 212 of the compressor 21 needs to be speeded up if the temperature of the working fluid outputted from the system is to be maintained to the former level, and vice versa. Thus, the mass flow of the working fluid 60 should be included in the system parameters to be received by the controller, so that the controller 30 can change the rotary speeds of the motor 212 of the compressor 21 and the fan 222 of the condenser 22 subject to the variation of the mass flow of the working fluid 60 so as to achieve the target temperature quickly.
When the cooling device 20 is just started, the inlet pressure of the compressor 21 is usually very close to the outlet pressure of the compressor 21, thereby causing a very large loading to the compressor 21 since the compressor 21 has a specific compression ratio. Therefore, the motor 212 of the compressor 21 should run in a low rotary speed when the cooling device 20 is just started, and be speeded up until the inlet pressure of the compressor 21 drops to a specific value. Thus, the inlet pressure of the compressor should be included in the system parameters so as to prevent the compressor 21 from overload when the system is just started.
In general, the cooling device is increased in cooling efficiency and lowered in output temperature of the working fluid subject to the increasing of the rotary speed of the motor of the compressor. However, the cooling device usually has a maximum pressure limitation on safety consideration, and the system is usually shut down automatically when reaching the maximum pressure for safety. Therefore, the outlet pressure of the compressor should be monitored when the motor of the compressor is speeded up. In general, the rotary speed of the motor is increased to a certain level and then kept at that level for a period of time to enable that the outlet pressure of the compressor is stable again or lower than a specific value, and then the motor is continuously speeded up to another level. Thus, the outlet pressure of the compressor should be included in the system parameters so as to enable the system to output working fluid having relatively lower temperature quickly without exceeding a safe operating pressure.
A temperature difference between the target temperature and the temperature of the working fluid having passed by and then cooled down by the evaporator 24 may exist. Further, the aforesaid temperature difference may vary according to variation of the mass flow of the working fluid. Thus, the temperature of the working fluid obtained after the working fluid has passed by the evaporator in the pipe should be included in the system parameters so that the working fluid can have a temperature very close to the target temperature when arriving at the DUT 80.
In order to control the temperature of the working fluid 60 more accurately, the system parameters received by the input ports 33 of the controller 30 may, but not limited to, further comprise a temperature of the working fluid 60 obtained after the working fluid 60 has passed by the evaporator 24 in the pipe 70, such as the temperature obtained at a sense position 72, a downstream in the pipe 70 relative to the evaporator 24 as shown in
If the compressor inlet temperature of the coolant 25, i.e. the temperature of the coolant 25 at the inlet of the compressor 21, is too low, a liquid phase compression might occur in the compressor, thereby decreasing the lifetime of the compressor. The compressor inlet temperature of the coolant is usually lowered when the motor of the compressor has a relatively higher rotary speed. Thus, the compressor inlet temperature of the coolant 25 may be included in the system parameters and monitored when the motor of the compressor runs in a relatively higher rotary speed in a fast cooling process.
If the compressor outlet temperature coolant 25, i.e. the temperature of the coolant 25 at the outlet of the compressor 21, is too high, a failure in heat dissipation might happen to the compressor, and a protective shutdown of the compressor might be even adopted by the system. This issue may happen especially when the compressor is in high speed operation. Thus, the compressor outlet temperature of the coolant 25 may be included in the system parameters for controlling purpose, so that the compressor 21 of the cooling device 20 is capable of running in high speed without the problem of overheat.
When the cooling device 20 is in operation, the current of the motor 212 of the compressor 21 can't exceed a rated value so as to prevent the system from overload. Thus, the current of the motor 212 of the compressor 21 may be included in the system parameters so as to prevent the working current of the motor 212 from exceeding the rated value when the motor of the compressor and the fan of the condenser are running in high speed operation.
The inlet temperature of working fluid 60, which means the temperature of fluid at the inlet of the cooling device 20, may influence the temperature of the working fluid outputted from the system. In general, the temperature of the working fluid outputted from the system is increased subject to the increasing of the inlet temperature of working fluid 60, and vice versa. Thus, the inlet temperature of working fluid 60 may be included in the system parameters so that the controller can adjust the rotary speed of the motor of the compressor according to the inlet temperature of working fluid. This means the motor is controlled to be speeded up when the inlet temperature of working fluid 60 is increased and slowed down when the inlet temperature of working fluid 60 is decreased.
When the condenser outlet temperature of the coolant 25, i.e. the temperature of the coolant 25 at the outlet of the condenser 22, is relatively lower, i.e. the coolant 25 stays in an overcooled phase, the coolant will be capable of taking away more heat when passing through the evaporator 24. In this condition, the motor of the compressor can run in a relatively slower speed while the system maintains a same cooling efficiency. Thus, the condenser outlet temperature of the coolant 25 may be included in the system parameters so that the controller can correspondingly adjust the rotary speed of the motor of the compressor quickly.
When the ambient environment temperature around the system is lowered, the thermal exchange of the coolant in the condenser is increased, so that the coolant will be cooled at a relatively lower temperature after passing through the condenser, thereby bringing away more heat when passing through the evaporator 24. Thus, the ambient environment temperature may be included in the system parameters so that the controller can correspondingly adjust the operation of the system quickly. For example, when the ambient environment temperature is lowered, the rotary speed of the motor of the compressor can be also lowered.
In brief, the adaptive temperature control system of the present invention can cool down the working fluid at the target temperature accurately so as to control the temperature of the DUI accurately and uniformly by means of the working fluid. In addition, the present invention has high stability in the temperature of the working fluid outputted from the cooling device, high energy efficiency and thereby low energy waste. Besides, the present invention can provide the required temperature to the working fluid in a relatively shorter time, prevent the compressor from exceeding safe temperature and pressure ranges, and operate under an AC input voltage and a frequency in wide ranges.
It is to be understood that the present invention is not limited to the disclosure of the above-mentioned first embodiment. Various modifications and/or improvements may be adopted without departing from the technical features of the present invention. For example,
In this way, after the coolant 25A is cooled down by the condenser 22, the coolant 25A can be further cooled down again by the additional condenser 91, such that the coolant 25A may have a relatively lower temperature when flowing through the evaporator 24, thereby enabling to cool the working fluid 60 to a relatively lower temperature. Besides, the coolant 25B flowing backwards from the evaporator 24 to the compressor 21 can be functioned to thermally exchange with the coolant 25A when flowing through the additional condenser 91, thereby further cooling down the coolant 25A, so that the cooling device 20′ has relatively better cooling efficiency. Resulted from the aforesaid thermal exchange between the coolant 25A flowing to the evaporator 24 and the coolant 25B flowing backwards from the evaporator 24, the coolant 25B is raised in its temperature before flowing back into the compressor 21, which helps the liquid in the coolant 25B to be transformed into gas before the coolant 25B flows into the compressor 21, so that the compressor 21 is prevented from liquid phase compression.
In addition, the working fluid 60 flowing in the pipe 70 can be arranged to pass by the additional condenser 91 before passing by the evaporator 24. In this way, the coolant 25B in the additional condenser 91 is functioned to thermally exchange with the working fluid 60 passing by the additional condenser 91, so that the working fluid 60 is pre-cooled before passing by the evaporator 24, and therefore the working fluid 60 can be further cooled to the required temperature more quickly when passing by the evaporator 24.
Referring to
Because of being re-cooled by the additional condensers 92, 95, the coolant 25A in this embodiment may have a relatively lower temperature when flowing through the evaporator 24, and therefore the coolant 25A is able to cool down the working fluid 60 to a relatively lower temperature. On the other hand, the coolant 25B flowing backwards from the evaporator 24 to the compressor 21 has a very low temperature (usually below −10° C. in the first additional condenser 92 and below −40° C. in the second additional condenser 95), such that when the coolant 25B flows through the second additional condenser 95 and the first additional condenser 92, it can be functioned to thermally exchange with the coolant 25A (the temperature of the coolant 25A at the outlet of the condenser 22 is usually a little bit higher than the ambient environment temperature). Resulted from the aforesaid thermal exchange between the coolant 25A flowing to the evaporator 24 and the coolant 25B flowing backwards from the evaporator 24, the coolant 25A is further cooled down and therefore the cooling device 20″ has relatively better cooling efficiency; besides, the coolant 25B is raised in temperature before flowing back into the compressor 21, which helps the liquid in the coolant 25B to be transformed into gas before the coolant 25B flows into the compressor 21, so that the compressor 21 is prevented from liquid phase compression.
In addition, the working fluid 60 flowing in the pipe 70 can be arranged to pass by the first additional condenser 92 and the second additional condenser 95 before passing by the evaporator 24. In this way, the coolant 25B in the first and second additional condensers 92, 95 and the coolant flowing backwards from the additional expander 94 to the second additional condenser 95 are functioned to thermally exchange with the working fluid 60 passing by the additional condensers 92, 95, so that the working fluid 60 is pre-cooled before passing by the evaporator 24, and therefore the working fluid 60 can be further cooled to the required temperature more quickly when passing by the evaporator 24.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 104105133 | Feb 2015 | TW | national |
| 105102396 | Jan 2016 | TW | national |
