Adaptive DC-to-DC Converter Control for Light-Load Efficiency
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Solution Overview
Problem
DC-to-DC converters in electrical trains or trams experience efficiency drops under light-load or no-load conditions due to persistent switching losses, despite reduced power transfer, as the fixed switching frequency and duty cycle do not adapt to varying power ratings.
Innovation Solution
A method for controlling a DC-to-DC converter that measures input and output voltages to generate adaptive switching signals, blocking pulses when conditions are not met, and adjusting the number and shape of switching pulses based on load conditions to maintain efficient operation, thereby reducing switching losses across varying power ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed switching frequency and 50% duty cycle are used, then zero voltage switching and low current switching are achieved, but switching losses remain high under light-load or no-load conditions
Solution Approach 1:
The patent applies dynamics by making the switching frequency and duty cycle variable rather than fixed. The control unit adapts these parameters based on the actual power rating and load conditions, allowing the converter to optimize its switching behavior dynamically. This resolves the contradiction by enabling the system to maintain reliable switching performance at nominal power while reducing switching losses under light-load conditions through adaptive parameter adjustment.
Solution Approach 2:
The patent changes the switching parameters (frequency and duty cycle) based on operating conditions. Instead of using fixed parameters, the control unit modifies these parameters according to the power rating and load level. This allows the system to achieve zero voltage switching and low current switching at nominal power while reducing switching losses under light-load conditions by adjusting parameters appropriately.
2Device complexity
If fixed switching frequency is used, then simple control is maintained, but efficiency decreases under varying power ratings
Solution Approach 1:
The patent implements dynamic control where the switching frequency and duty cycle are adjusted based on power rating and load conditions. The control unit receives signals about the operating state and adapts the switching parameters accordingly. This dynamic approach improves efficiency under varying power ratings while keeping the control structure relatively simple through automated feedback mechanisms.
Solution Approach 2:
The patent uses feedback by having the control unit monitor the power rating and load conditions, then adjust the switching parameters based on this information. The control unit adapts the switching behavior according to the actual operating state, creating a closed-loop system that optimizes efficiency while maintaining manageable control complexity through automated decision-making.
3Reliability
If circulating current is maintained for ZVS, then zero voltage switching is achieved, but switching losses persist under no-load conditions
Solution Approach 1:
The patent applies dynamics by adaptively controlling the circulating current based on load conditions. Under nominal power, the system maintains sufficient circulating current to achieve zero voltage switching. Under light-load or no-load conditions, the control unit reduces or blocks switching pulses, thereby reducing the circulating current and associated switching losses while maintaining switching quality when needed.
Solution Approach 2:
The patent changes the circulating current parameter based on operating conditions. The control unit adjusts the amount of circulating current according to the power rating and load level. This allows the system to maintain zero voltage switching capability when needed while reducing switching losses under light-load conditions by adapting the circulating current parameter appropriately.
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
This adaptive control method ensures energy-efficient operation under light-load or no-load conditions, maintaining stable DC voltages and reducing switching losses, thus enhancing the efficiency of the DC-to-DC converter, especially at nominal and varying power ratings.
Implementation Method 1
a resonant DC-to-DC converter, in which a DC-to-AC converter on the line side is connected via a resonant transformer with an AC-to-DC converter on the motor side
Implementation Method 2
This may provide zero voltage switching (ZVS) during turn-on of the semiconductor switches
Implementation Method 3
a resonant DC-to-DC converter, in which a DC-to-AC converter on the line side is connected via a resonant transformer with an AC-to-DC converter on the motor side
Data Source
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AI summary
A DC-to-DC converter (42) comprises a DC-to-AC converter (52) and an AC-to-DC converter (56) connected in series with a transformer (54), both the DC-to-AC converter and the AC-to-DC converter comprising semiconductor switches (58, 62). A method for controlling a DC-to-DC converter (42) comprises the steps of: determining a DC input voltage (82) and a DC output voltage (84) of the DC-to-DC-converter (42); determining whether a switching condition (C) based on the DC input voltage (82) and the DC output voltage (84) is fulfilled; and generating a switching signal (98, 100) with switching pulses (140, 142) for switching the semiconductor switches (58, 82) of at least one of the DC-to-AC converter (52) and the AC-to-DC converter (56), wherein the generation of switching pulses (140, 142) is blocked, when the switching condition (C) is not fulfilled.