Power Supply Fan Speed Control for Thermal Stress Reduction
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Solution Overview
Problem
Power semiconductor devices in power supply apparatuses experience reduced lifespan due to frequent temperature fluctuations, and existing cooling methods either cause thermal stress or excessive cooling when the apparatus is deactivated.
Innovation Solution
A power supply apparatus with a fan that alternates between powered and pausing states, using temperature measurement and control to maintain a stable temperature difference between operating and non-operating states, preventing thermal stress and extending device life by continuously rotating at a controlled rate during the pausing period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fan is stopped at the same time as the power supply apparatus activation switch is turned off, then energy consumption is reduced, but thermal stress is given to components around the heat sink
Solution Approach 1:
The fan rotation rate is dynamically adjusted based on the operating state of the power supply apparatus. During the powered state, the fan rotates at a first rotation rate to provide adequate cooling. During the pausing period, the rotation rate is changed to a second rotation rate (lower than the first) to maintain cooling while reducing energy consumption. This dynamic adjustment resolves the contradiction between energy savings and thermal stress prevention.
Solution Approach 2:
The invention changes the operational parameters of the fan by adjusting its rotation rate according to different operating conditions. The control means modifies the fan's rotation rate parameter - using a higher rate during powered state and a lower rate during pausing period - to optimize both energy efficiency and thermal management, preventing thermal stress while reducing power consumption.
2Object-affected harmful factors
If the fan is continued to be driven after the power supply activating switch is turned off, then thermal stress on components is avoided, but the temperature of power semiconductor devices is lowered too much
Solution Approach 1:
The fan rotation rate is dynamically adjusted based on the operating state. During the powered state, the fan operates at a first rotation rate. During the pausing period, the control means changes the rotation rate to a second rate that is lower than the first but maintains sufficient cooling to prevent excessive temperature drop, thereby avoiding thermal stress while preserving device temperature.
Solution Approach 2:
The invention implements temperature feedback control where temperature measuring means continuously monitors the temperature of heat-generating components and provides feedback to the control means. The control means uses this feedback information to adjust the fan's rotation rate appropriately - maintaining higher rotation when temperatures are high and reducing rotation when temperatures are acceptable, thus preventing both thermal stress and excessive cooling.
3Temperature
If the fan rotates at rated rotation rate during powering period, then cooling effectiveness is maximized, but energy consumption increases
Solution Approach 1:
The fan operates at different rotation rates depending on the operating state. During the powered state when cooling demand is high, the fan rotates at a first (higher) rotation rate to maximize cooling effectiveness. During the pausing period when cooling demand is reduced, the fan switches to a second (lower) rotation rate to reduce energy consumption while maintaining adequate cooling.
Solution Approach 2:
The fan operates in a periodic manner, alternating between a first rotation rate during the powering period and a second rotation rate during the pausing period. This periodic operation allows the system to optimize cooling effectiveness during active operation while minimizing energy consumption during idle periods, resolving the contradiction between cooling performance and energy use.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces temperature differences between operating and non-operating states, preventing thermal stress and extending the lifespan of power semiconductor devices while ensuring components around the heat sink are not thermally stressed.
Implementation Method 1
A fan is used to cool the heat-generating components. The fan is driven during the powering period for cooling the heat-generating components including the power semiconductor devices.
Implementation Method 2
Temperature measuring means measures the temperature of the heat-generating components and develops a measured-temperature representative signal representative of the measured temperature of the heat-generating components.
Implementation Method 3
the power semiconductor devices are mounted, in many cases, on a heat sink in the power supply apparatus
Data Source
AI summary
A power supply unit includes an input-side rectifying circuit (4), an inverter (8) and an output-side rectifying circuit (12), which include power semiconductor devices. The power supply unit is powered during a powering period, and the powering is interrupted during a pausing period. The powering and pausing periods alternate. A fan (18) is driven during each powering period to cool the power semiconductor devices. A temperature detector (30) measures the temperature of the power semiconductor devices and develops a measured-temperature representative signal. A setter (38) produces a reference value, which decreases over the pausing period from the measured-temperature representative signal at the beginning of the pausing period to an intended-temperature representative signal representing the temperature to be attained by the power semiconductor devices at the end of the pausing period. The reference value is prepared from the measured-temperature representative signal at the beginning of the pausing period, the intended-temperature representative signal, and the length of the pausing period. An error amplifier (36) and a fan control unit (22) control the rotation rate of the fan (18) to make the measured-temperature representative signal track the reference value.