Drive Circuit Segmentation for Power Device Stability
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Solution Overview
Problem
Existing drive circuits for power devices experience operational instability and signal errors due to negative voltage generation at nodes, affecting the stability and accuracy of control signals, particularly when the voltage at these nodes becomes negative.
Innovation Solution
A drive circuit design that includes set-side and reset-side pulse generation circuits, level shift circuits, and a control circuit to ensure stable operation of power devices by generating level-shifted signals and ensuring the correct state of the power device based on logic input signals, using internal and external power supplies to manage voltage levels and prevent overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the node voltage is allowed to become negative during power device switching, then the power device can be turned on and off efficiently, but the preceding-stage circuit operation becomes unstable and control signals become erroneous
Solution Approach 1:
The drive circuit is divided into separate high-side and low-side control circuits with independent power supplies. The high-side control circuit uses a first power supply while the low-side uses a second power supply, isolating the control stages from the negative voltage effects at the power device node
Solution Approach 2:
Level shift circuits are introduced as intermediary components between the preceding-stage logic circuits and the high-side control circuit. These level shift circuits translate logic level signals to the high-voltage domain while being isolated from negative voltage effects through proper circuit design
2Power
If a level shift circuit is used to shift logic levels for high-side control, then the power device can be driven at high voltage, but the circuit becomes more complex and sensitive to voltage fluctuations
Solution Approach 1:
The level shift function and the high-side drive function are merged into a single integrated high-side control circuit that handles both voltage level translation and power device driving, reducing overall circuit complexity while maintaining high-voltage capability
3Device complexity
If the same power supply is used for both high-side and low-side control circuits, then the circuit design is simplified, but negative voltage at the node affects the stability of the entire control system
Solution Approach 1:
The power supply system is segmented into multiple independent sources: a first power supply for the high-side control circuit and a second power supply for the low-side control circuit. This segmentation prevents negative voltage propagation from affecting the entire control system
Solution Approach 2:
Each control circuit is provided with power supply characteristics suited to its specific requirements. The high-side control circuit receives power filtered and regulated to prevent negative voltage effects, while the low-side control circuit uses appropriate power supply design for its operating conditions
Data Source
AI summary
A drive circuit of a power device, including an internal power supply, a set-side pulse generation circuit and a reset-side pulse generation circuit that are connected to the internal power supply, for generating a set signal and a reset signal respectively upon detecting that a logic input signal changes from a first logic level to a second logic level, or changes from the second logic level to the first logic level, a set-side level shift circuit and a reset-side level shift circuit that respectively level-shift the set signal and the reset signal, a control circuit that turns on and off the power device respectively responsive to the level-shifted set signal and the level-shifted reset signal, and an ensuring circuit that ensures a first state and a second state, in which the power device is respectively off and on, when the logic input signal is at the first logic level and the second logic level.