DC Power Supply Return Line Ground Loop Suppression
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Solution Overview
Problem
Existing power supply arrangements with multiple DC consumers suffer from circulating ground loop currents, leading to unintended voltage drops and electromagnetic interference, with solutions like transformers being bulky and diodes causing power losses.
Innovation Solution
Incorporating a combination of capacitors and diodes in parallel in the return lines of DC-DC switching power converters to block circulating currents, allowing high-frequency currents to pass while preventing low-frequency and DC currents, thereby preventing ground loop currents without the disadvantages of transformers or diodes alone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a transformer is used in the power conversion to provide galvanic isolation, then ground loop currents are prevented, but the device becomes heavy and bulky
Solution Approach 1:
The patent changes the electrical parameters of the return line by introducing a capacitor, transforming it from a purely resistive/conductive path to one with capacitive reactance. This parameter change allows the return line to block DC ground loop currents while passing AC signals, eliminating the need for heavy transformers.
Solution Approach 2:
The invention extracts the ground loop current blocking function from the traditional transformer and implements it separately using a capacitor in the return line. This separation allows the power conversion to use lighter non-isolated converters while the capacitor handles the isolation function for low-frequency currents.
2Object-affected harmful factors
If diodes are placed in the return lines to prevent ground loop currents, then circulating currents are blocked, but voltage drop and power losses occur
Solution Approach 1:
The patent changes the impedance characteristics of the return line by adding a capacitor, creating a frequency-dependent path. At DC and low frequencies, the capacitor blocks ground loop currents, while at high frequencies (switching signals), the capacitor's reactance decreases, allowing signals to pass with minimal loss.
Solution Approach 2:
The capacitive reactance dynamically adapts to different frequencies: high impedance at DC/low frequencies to block ground loops, and low impedance at high frequencies to pass switching signals. This dynamic behavior eliminates the need for diodes that cause constant voltage drops.
3Object-affected harmful factors
If diodes are arranged in each power supply line to prevent ground loop currents, then circulating currents are blocked, but power losses increase
Solution Approach 1:
The invention extracts the ground loop prevention function from the power supply lines and places it in the return line using a capacitor. This relocation eliminates the need for diodes in each power supply line, reducing the number of active components and their associated power losses.
Solution Approach 2:
By changing the return line's electrical parameters through capacitor addition, the system achieves ground loop blocking without the continuous voltage drops inherent in diode-based solutions. The capacitor only affects DC/low-frequency currents while being transparent to high-frequency switching signals.
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 solution effectively blocks circulating ground loop currents, reducing power losses and maintaining stable potential, resulting in a lightweight, compact, and efficient power supply arrangement with minimal weight and size increase.
Implementation Method 1
Said first unit is a combination of a capacitor and a diode which are connected in parallel... The currents flows from positive to negative potential and said first and second units arranged in the return line of the switching power converters, such as switching step-down converters, causes blocking of currents that circulate via a ground or a chassis ground.
Implementation Method 2
Said first unit is a combination of a capacitor and a diode which are connected in parallel... said first electrical device has a diode function... causes blocking of currents that circulate via a ground or a chassis ground.
Data Source
Figure 1~2
AI summary
Power supply arrangement for distribution of power from a DC power source having a positive terminal and a negative terminal to at least a first and a second DC power consumer, comprising: a first DC power consumer connected to said negative terminal of said DC power source by means of at least a first return line, a first DC-DC switching power converter connected to said first DC power consumer, and connected to said positive terminal of said DC power source,a second DC power consumer connected to said negative terminal of said DC power source by means of at least a second return line, a second DC-DC switching power converter connected to said second DC power consumer, and connected to said positive terminal of said DC power source,wherein a unit comprising a capacitor connected in parallel with an electrical device is arranged in each of said first and second return lines, wherein said electrical device has a diode function, whereby circulating ground loop currents are prevented.