Electricity: motive power systems – Automatic and/or with time-delay means – Responsive to thermal conditions
Reexamination Certificate
1999-09-20
2001-03-06
Ip, Paul (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
Responsive to thermal conditions
C318S472000, C702S132000, 36, C361S195000, C361S695000
Reexamination Certificate
active
06198245
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to thermal management for systems, and more specifically to look-ahead, closed-loop system temperature control.
DESCRIPTION OF THE PRIOR ART
Presently, the performance of various different types of systems, particularly portable systems such as laptop or notebook computers, depends crucially upon effectively exploiting electrical energy for the system's operation, such as may be stored in rechargeable batteries. To extend as much as practicable the time which laptop and notebook computers may operate without recharging the batteries, conventional laptop and notebook computers typically possess several power-down operating modes. Usually, such devices can be powered down so a central processing unit (“CPU”) included in a laptop or notebook computer is almost completely turned-off, with the state of the CPU saved on a hard drive. To resume operation, a very low power portion of the CPU or an auxiliary circuit (e.g. keyboard controller) is typically responds to pressing of a key. The system then reactivates normal power to allow the CPU to retrieve the stored machine state from the hard drive thereby restoring the computer into an operating mode. Some well known power saving modes are called sleep mode, suspend mode and the like.
To effect changes between different operating modes, a power management routine (“PMR”) executed by the CPU periodically monitors peripheral devices to assess whether a peripheral device's operation may be suspended. Similarly, if it becomes necessary to access a peripheral device whose operation has been suspended, the PMR must restore that peripheral device to an operating state.
Not only does designing a laptop or notebook computer present problems in electrical power management such as those outlined above, the compact size, tight packaging, and limited ventilation of laptop and notebook computers also pose problems in thermal management. To effect active, as contrasted with passive, thermal management, laptop and notebook computers usually include one or more devices for sensing the temperature of various system components as well as one or more temperature control devices, such as an electrically powered heater or fan, that may be activated responsive to the sensed temperature for altering the component's temperature. Either the PMR, a comparable computer program executed by the CPU, or a comparable system hardware component periodically monitors temperature within the system and then appropriately activates or deactivates the temperature control device(s).
As is readily apparent, higher performance of portable systems, such as laptop or notebook computers, is usually accompanied by increased electrical power consumption and corresponding heat generation within the system. However, since operation of critical system components fail outside of some pre-established temperature range, at some point the need to control the system's temperature dominates system performance and/or electrical power conservation goals. Consequently, for high-performance, battery powered portable systems trade-offs exists between the system's performance, the duration of battery powered operation, and the system's temperature.
The conventional strategy for balancing competing demands among improved performance, longer battery powered operation and system temperature is simply activating one or more temperature control devices, e.g. turning on a fan or a heater, if the temperature sensed for a system component is outside some pre-established range. One difficulty with the preceding thermal management strategy is the size of the thermal protection margin required for critical system components. Because the temperature sensing devices included in the system, e.g. thermistors, are not located at the source of heat generation and also because of the component's packaging, a lag occurs between an increase or decrease in a system component's temperature and a corresponding increase or decrease in the sensing device's temperature. Analogously, a lag also occurs between activating a temperature control device, e.g. turning on a fan or a heater, and a temperature change within a system component.
Consequently, ensuring an adequate thermal protection margin requires that a temperature control device be activated for a system component at a temperature further from the component's temperature limit than would be required if it were possible to predict a thermal trend for the system component, or for the entire system. In practical terms, ensuring an adequate thermal protection margin employing the strategy described above wastes electrical power by requiring that a temperature control device be activated temperature further from the system component's temperature limit than may, in fact, truly be necessary. Moreover, activating an electrically powered cooling device when it is not truly required is doubly wasteful because, not only does its operation consume electrical power, it's operation also generates addition heat within a system. Furthermore, the conventional strategy for thermal management may also increase system manufacturing cost by requiring an excessive number of temperature sensing devices, temperature control devices, and thermal control devices for activating the temperature control devices responsive to the sensing devices' temperature.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an improved strategy for a system's thermal management that reduces electrical power consumption by the system's temperature control devices while ensuring the system's operability.
An object of the present invention is to reduce the thermal protection margin required for system components without increasing the likelihood of system component failure due to operation outside of a pre-established temperature range.
An object of the present invention is to reduce unnecessary consumption of electrical power by systems.
An object of the present invention is to permit construction of simpler systems that employ thermal management.
Briefly, the present invention in one embodiment is a method for thermal management within an electrically powered systems. Implementation of the method requires monitoring from time-to-time both electrical power consumption and temperature within the system. The power consumption and temperature data thus obtained permits developing over time a thermal model for the system. After a thermal model for the system has been thus developed, the model together with the presently sensed electrical power consumption, and the system temperature are used to predict a thermal trend for the system. The predicted thermal trend thus obtained for the system is then used in effecting a temperature control strategy within the electrically powered system.
These and other features, objects and advantages will be understood or apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiment as illustrated in the various drawing figures.
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Du Sterling
Kuo Chuan Chiung
Shyr You-Yuh
Yeh Shih Ping
Ip Paul
O
Schreiber, Esq. Donald E.
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