Series-Stacked Inverter Voltage Balancing Across Internal Transistors
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Solution Overview
Problem
Inverters with series-connected transistors face instability due to unbalanced cross voltages across N-type transistors, leading to potential transistor breakdown and system instability when operating with high voltages.
Innovation Solution
Incorporating voltage drop impedance elements in parallel with N-type transistors, with impedances lower than the transistors when turned off, to balance cross voltages, and optionally adjusting channel width-to-length ratios of transistors to manage voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If more series-connected transistors are used to increase voltage handling ability, then the inverter can operate with high voltages, but unbalanced cross voltages cause transistor damage and system instability
Solution Approach 1:
The patent changes the impedance parameter of parallel elements (voltage drop impedance elements) to control voltage distribution. By setting the impedance of these parallel elements to be smaller than the off-state impedance of N-type transistors, the voltage is redistributed to achieve balanced cross voltages across all transistors, resolving the reliability issue while maintaining high voltage handling capability
Solution Approach 2:
The patent introduces voltage drop impedance elements as intermediary components connected in parallel with N-type transistors. These intermediary elements act as mediators to redistribute the voltage across the transistor stack, ensuring that cross voltages are balanced and preventing any single transistor from bearing excessive voltage stress
2Power
If series-connected transistors are used for high voltage operation, then voltage handling increases, but some transistors endure high cross voltages for long time causing damage
Solution Approach 1:
The patent modifies the electrical parameters by introducing parallel impedance elements with specific impedance values. This parameter change ensures that the voltage distribution across series-connected transistors is balanced, preventing any transistor from enduring harmful high cross voltages for extended periods
Solution Approach 2:
The patent applies prior cushioning by pre-configuring voltage drop impedance elements in parallel with transistors before operation. These elements provide a protective pathway that cushions the transistors from excessive voltage stress, preventing damage before it occurs by distributing the voltage burden evenly across all devices
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
Mitigates system instability by ensuring balanced cross voltages across transistors, reducing the risk of transistor breakdown and maintaining inverter stability under high voltage conditions.
Implementation Method 1
The impedance of the first voltage drop impedance element is smaller than the impedance of the first N-type transistor when the first N-type transistor is turned off
Data Source
AI summary
An inverter includes a first system voltage terminal, a second system voltage terminal, an output terminal, a plurality of P-type transistors, a plurality of N-type transistors, and a voltage drop impedance element. The first system voltage terminal receives a first voltage, and the second system voltage terminal receives a second voltage. The plurality of P-type transistors are coupled in series between the first system voltage terminal and the output terminal. The plurality of N-type transistors are coupled in series between the output terminal and the second system voltage terminal. The voltage drop impedance element is coupled in parallel with a first N-type transistor of the plurality of N-type transistors, and the impedance of the voltage drop impedance element is smaller than the impedance of the first N-type transistor when the first N-type transistor is turned off.