Semiconductor Device Terminal Configuration for Magnetic Coupling Control
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Solution Overview
Problem
High drive frequencies in power switching elements lead to magnetic coupling issues between control and main terminals, causing voltage variations and delayed response speeds due to induced electromotive forces, particularly in insulated gate bipolar transistors (IGBTs).
Innovation Solution
A semiconductor device design with specific terminal configurations and parasitic inductance management, where the coupling coefficient k is controlled within the range of −3% to 2%, minimizing magnetic coupling between control and main current paths by optimizing the arrangement of terminals and parasitic inductances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive frequency of the power switching element is increased, then the productivity is improved, but magnetic coupling between terminals causes voltage variations and oscillations that worsen the reliability
Solution Approach 1:
The patent extracts and separates the control current path from the main current path by providing dedicated control terminals (gate terminal and Kelvin emitter terminal) that are physically and electrically separated from the main terminals. This extraction eliminates the magnetic coupling between control and main currents, allowing high drive frequencies to be used without causing voltage variations or oscillations in the control circuit.
2Speed
If the voltage to be applied to the gate terminal increases to turn on the element, then the switching speed is improved, but the main current increases more than the desired current value due to induced electromotive force
Solution Approach 1:
The patent introduces the Kelvin emitter terminal as an intermediary that provides a dedicated reference potential for the gate terminal. This intermediary terminal allows the control circuit to accurately sense and control the gate-emitter voltage without being affected by the induced electromotive force from the main current, thereby maintaining precise current control while achieving fast switching speeds.
3Reliability
If a feedback circuit is used to keep a constant voltage of the gate terminal, then the voltage control is improved, but the main current oscillates while repetitively increasing and decreasing due to induced electromotive force
Solution Approach 1:
The patent extracts the control current path from the main current path by providing separate control terminals (gate terminal and Kelvin emitter terminal). This separation removes the source of induced electromotive force that causes oscillations in feedback-controlled systems, allowing the feedback circuit to maintain stable gate terminal voltage without causing main current oscillations.
4Loss of energy
If the voltage to be applied to the gate terminal decreases to turn off the element, then the power loss is reduced, but a sufficient main current is not obtained and the response speed is delayed
Solution Approach 1:
The patent introduces the Kelvin emitter terminal as an intermediary that provides a stable reference potential during switching operations. This intermediary ensures that the gate-emitter voltage is accurately controlled during both turn-on and turn-off transitions, eliminating delays in obtaining sufficient main current while maintaining low power loss when the element is off.
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 design effectively suppresses overshooting and delays in main current responses, ensuring stable and efficient operation of power switching elements by reducing magnetic coupling and maintaining a controlled voltage at the gate terminal.
Implementation Method 1
a magnetic flux is induced around a current path of a main current flowing between the collector lead and the emitter lead. An induced electromotive force is generated between the gate terminal and the Kelvin emitter terminal so as to restrict a change in the magnetic flux
Data Source
AI summary
A semiconductor device includes: a semiconductor chip having a switching element and multiple pads electrically connected to the switching element; and multiple lead terminals electrically connected to the respective pads. The multiple lead terminals include a control terminal used for control of on/off operation of the switching element, and a main terminal into which a main current flows when the switching element is in an on state. A coupling coefficient k falls within a range of −3%≦k≦2%, where the coupling coefficient k is defined by a parasitic inductance Lg in a current path of a control current flowing in the control terminal, a parasitic inductance Lo in a current path of the main current, and a mutual inductance Ms of the parasitic inductances Lg and Lo.