MOS Transistor Drive Control Using Drain-Source Current Sensing
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Solution Overview
Problem
Existing drive control devices for motors consume power and generate heat due to the use of resistors for detecting excitation current, leading to decreased efficiency and increased costs for accurate current control.
Innovation Solution
A drive control device that includes MOS transistors, voltage measuring circuits, a correction circuit, and a control circuit to accurately control excitation current without the need for resistors by measuring voltages between the drain and source of the MOS transistors during forward and reverse current flows, correcting the current setting voltage level based on detected voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resistor is used to detect excitation current, then current detection accuracy is improved, but power consumption increases and heat is generated
Solution Approach 1:
The patent extracts the current detection function from the resistor-based method and relocates it to the MOS transistor's intrinsic voltage measurement capability. By measuring the voltage between drain and source of the MOS transistor during current flow, the system eliminates the need for separate detection resistors, thereby reducing power consumption while maintaining detection accuracy.
Solution Approach 2:
The MOS transistor serves dual purposes: it acts as the switching element for current control and simultaneously serves as the sensing element for current detection. The voltage developed across the MOS transistor during operation is utilized for both control and measurement functions, making the system self-sufficient and eliminating additional power-consuming components.
2Measurement precision
If a resistor is used to detect excitation current, then current detection is enabled, but heat generation increases
Solution Approach 1:
The patent removes the resistor component that causes heat generation and extracts the detection function to the MOS transistor itself. By utilizing the voltage drop across the MOS transistor's channel during current flow, the system achieves current detection without the I²R heating losses inherent in resistor-based methods.
Solution Approach 2:
The MOS transistor's channel resistance during operation naturally produces a voltage signal that is directly proportional to the current flowing through it. This self-generated voltage signal is used for detection purposes, eliminating the need for external resistors that would generate additional heat.
3Measurement precision
If a highly accurate resistor is provided for current detection, then current control accuracy is improved, but cost increases
Solution Approach 1:
The patent extracts the precision measurement function from expensive high-accuracy resistors and implements it using the MOS transistor's inherent electrical characteristics. The voltage measurement across the MOS transistor provides sufficient accuracy for current control without requiring costly precision components, thereby reducing manufacturing costs while maintaining control accuracy.
Solution Approach 2:
The patent replaces expensive, high-precision resistors with standard MOS transistors that are already present in the circuit for switching operations. This substitution uses readily available, low-cost components to achieve the required measurement precision, significantly reducing component costs.
4Measurement precision
If voltage measurement during reverse current flow is performed, then current control accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the voltage measurement function into the existing MOS transistor structure and control circuitry. By measuring voltage during both forward and reverse current flow phases and integrating these measurements into a unified control algorithm, the system achieves enhanced accuracy without adding separate measurement circuits or increasing overall device complexity.
Solution Approach 2:
The patent implements a feedback mechanism where voltage measurements during both forward and reverse current flow are fed back to the control circuit. This dual-phase feedback provides more comprehensive information about the actual current state, enabling more accurate control decisions while utilizing the existing circuit infrastructure.
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
Enables high-accuracy control of excitation current, reducing power consumption and heat generation, and lowering costs by eliminating the need for resistors in current detection.
Implementation Method 1
a first voltage measuring circuit for measuring a voltage between a drain and a source of the MOS transistor when a forward drain current flows through the MOS transistor, and a second voltage measuring circuit for measuring a voltage between the drain and the source of the MOS transistor when a reverse drain current flows in the MOS transistor
Data Source
AI summary
A drive control device includes a MOS transistor, voltage measuring circuits, a correction circuit, and a control circuit. The voltage measuring circuits measure a drain-to-source voltage when a forward drain current flows through the MOS transistor and when a reverse drain current flows in the MOS transistor. The correction circuit sets a current setting voltage level when the reverse drain current flows, where the current setting voltage level is proportional to the voltage between the drain and the source when a predetermined reverse setting current flows in the MOS transistor. The control circuit controls ON/OFF of the MOS transistor in response to a control signal reflecting a measured value of the first voltage measuring circuit when the forward drain current flows through the MOS transistor and the current setting voltage level that is set by the correction circuit when the reverse drain current flows in the MOS transistor.