Adjustable Current Source for Floating Potential Charge
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Solution Overview
Problem
Existing circuits for supplying a load with varying DC voltage face inefficiencies due to constant current sourcing, leading to unnecessary consumption when the load does not draw maximum current, and require modifications to measure load consumption, which can affect its operation.
Innovation Solution
A power supply circuit with an adjustable current source controlled by a servo circuit using MOS transistors and a Zener diode, where the current source is adjusted based on the current flowing through the Zener diode, optimizing consumption without direct measurement of load current or modification to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current source is dimensioned according to the maximum consumption of the load, then the Zener diode is permanently in avalanche mode guaranteeing fixed voltage, but unnecessary consumption occurs when the load does not draw maximum current
Solution Approach 1:
The current source is transformed from a static constant current source to a dynamic adjustable current source that adapts its output current based on load conditions. The control circuit continuously monitors the Zener diode current and adjusts the current source output accordingly, enabling the system to maintain reliable voltage fixing while minimizing power consumption when full current is not needed
Solution Approach 2:
A feedback control mechanism is implemented where the actual current through the Zener diode is measured and used to control the current source. The control circuit compares the actual Zener current with the required minimum avalanche current and adjusts the current source output to maintain proper Zener operation only when necessary, eliminating wasteful consumption during normal load operation
2Loss of energy
If a control circuit is added to adjust the current source, then power consumption is optimized, but the device complexity increases
Solution Approach 1:
The control circuit is designed to be self-regulating, using the Zener diode's own current as the feedback signal. The system automatically adjusts the current source based on the Zener diode's operating conditions without requiring external control signals or complex monitoring of the load itself. This self-service approach minimizes circuit complexity while achieving power optimization
Solution Approach 2:
The control circuit acts as an intermediary between the current source and the Zener diode, mediating the current flow to ensure proper operation. Rather than directly controlling the load or using complex measurement circuits, the intermediary control circuit uses simple current sensing and adjustment to achieve both power savings and reliable voltage regulation
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 optimizes power supply circuit consumption by dynamically adjusting the current source based on load demand, reducing overall losses and maintaining constant voltage supply without altering the load, thus addressing inefficiencies in existing circuits.
Implementation Method 1
The role of the Zener diode is to limit (fix) the voltage across the load
Implementation Method 2
the servo circuit comprises a first MOS transistor, mounted as a diode and as a current mirror on a second MOS transistor
Data Source
Figure 1~2
Figure 3~4
AI summary
The circuit has a current source (N4) connected with a load (1) between two terminals (21, 22) of application of a first direct current (DC) voltage (Vbat). An element (3) is coupled to limit the voltage across the load. A control circuit controls value of current in the current source with the current flowing to the element. The element comprises a zener diode that is connected to a junction point between the load and the current source. A first metal-oxide-semiconductor (MOS) transistor (P1) is assembled as a diode and as a current mirror on a second MOS transistor (P2).