DC-DC Converter Pulse Width Period Control for Power Reduction
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Solution Overview
Problem
Existing devices for converting DC power to battery charging power, such as those used in solar cell or fuel cell-powered appliances, face inefficiencies in power consumption, particularly during low power output periods, as the power controller consumes a significant portion of the total power used for conversion and control.
Innovation Solution
The method involves adjusting the pulse width period of the pulse width modulator (PWM) to reduce power consumption, achieved by extending the PWM period and deriving it from the clock frequency of the microprocessor, which also reduces the clock frequency and supply voltage of the power controller, thereby optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the PWM period is fixed at normal boundaries, then the converter efficiency is optimized, but the controller power consumption increases substantially during low power output periods
Solution Approach 1:
The patent applies dynamics by making the PWM period adjustable rather than fixed. The controller dynamically adapts the PWM period based on operating conditions, extending it during low power output periods to reduce controller power consumption while maintaining adequate converter efficiency. This is achieved through means for adjusting the pulse width period that are controllable for influencing power consumption of the controller.
Solution Approach 2:
The patent applies parameter changes by modifying the PWM period parameter to optimize overall system performance. By changing the PWM period from fixed to variable, the system can adjust this critical parameter to reduce controller power consumption during low power output periods while maintaining acceptable converter efficiency levels.
2Use of energy by moving object
If the clock frequency is reduced to extend PWM period, then the controller power consumption decreases, but the control and switching speed decreases
Solution Approach 1:
The patent applies dynamics by enabling dynamic adjustment of the clock frequency based on operating conditions. The microprocessor can operate at higher frequencies during high power output periods requiring fast control response, and at lower frequencies during low power output periods to reduce power consumption. This dynamic frequency adjustment reconciles the trade-off between speed and energy consumption.
Solution Approach 2:
The patent applies periodic action by utilizing the natural periodic nature of PWM control to adjust the period duration. By extending the PWM period through clock frequency reduction, the system performs control actions less frequently during low power periods, reducing microprocessor activity and power consumption while still maintaining periodic control necessary for converter operation.
Data Source
AI summary
A method is described wherein DC power is converted into battery charging power by means of an inductor carrying a current which is controlled by a power controller during an adjustable part of a pulse width period. The pulse width period is made adjustable in order to influence the power consumption of the controller which consumes a substantial amount of the total power consumed for controlled DC-DC conversion. Several additional features are provided to improve the efficiency and to further reduce the power consumed by both the converter and the power controller, which provides new uses for a variety of products and appliances having solar cells, such as road studs.