Intelligent Power Switch Current Protection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing current protection circuits for intelligent power switches are ineffective in quickly responding to short circuits, leading to high currents that can destroy the power device due to long response times and potential oscillations, especially when the power device is already ON.
Innovation Solution
A current protection circuit with a second comparator and latch mechanism that monitors voltage across a resistance and resets a latch to enable a second transistor circuit after a delay, allowing for a higher shutdown current limit and rapid power switch turn-off without oscillations, ensuring the power switch is turned OFF before high currents are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single comparator with gate voltage limit is used for current protection, then the circuit is simple, but the response time is too long and oscillations occur during short circuits
Solution Approach 1:
The current protection function is segmented into two independent circuits: a first circuit with comparator COMP1 for normal overcurrent protection (limiting gate voltage to 3V), and a second circuit with comparator COMP2 for short circuit protection (immediate shutdown). Each circuit operates independently with its own threshold and response characteristics, allowing optimized protection for different fault conditions without compromising overall system reliability
Solution Approach 2:
The second circuit with higher reference voltage REF2 is prepared in advance to detect severe short circuit conditions. The latch circuit is pre-configured to immediately turn off the power switch when the short circuit threshold is exceeded, eliminating the delay associated with gradual gate voltage reduction in normal protection scenarios
2Productivity
If the gate voltage is limited to 3 volts in overcurrent condition, then the current is reduced, but the response time is too long allowing high currents to reach saturation level
Solution Approach 1:
The system changes the reference voltage parameter dynamically based on fault severity. For normal overcurrent, COMP1 uses REF1 (3V gate limit). For severe short circuits, COMP2 uses REF2 (higher threshold) to detect the condition and trigger immediate shutdown. This parameter change enables faster response to catastrophic faults while maintaining gentle limitation for minor overloads
Solution Approach 2:
The latch circuit acts as an intermediary between COMP2 and the gate driver. When COMP2 detects a short circuit condition, the latch immediately latches the shutdown state and forces the gate voltage to zero, serving as a fast-acting mediator that bypasses the slower gradual reduction mechanism of the first circuit
3Loss of time
If a fast protection loop is implemented, then the response time is reduced, but the circuit becomes unstable and oscillates with certain loads
Solution Approach 1:
The protection function is divided into two stable segments: COMP1 provides slow, stable current limiting for normal operation, while COMP2 provides fast shutdown for severe faults. Each segment is independently stable because they operate at different thresholds and with different response characteristics, eliminating the oscillation problem that plagues single-loop fast protection systems
Solution Approach 2:
The system dynamically selects which protection circuit to activate based on the severity of the fault condition. Under normal overcurrent, the first circuit operates with gradual gate voltage reduction. Under severe short circuit, the second circuit activates with immediate shutdown. This dynamic adaptation allows optimal response for each condition without sacrificing stability
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
The solution enables fast and stable current limitation during short circuits, preventing damage to the power device by ensuring the power switch turns OFF quickly and reliably, reducing electromagnetic interference and peak currents, and allowing for a slow turn ON and OFF in normal operation.
Implementation Method 1
A first circuit to measure a current in the power switch, determine a first difference between a first voltage and a first reference voltage
Implementation Method 2
a second circuit to measure the current in the power switch and determine a second difference between the first voltage and a second reference voltage
Implementation Method 3
a gate terminal of the power switch being controlled by a first control signal generated by a gate driver
Data Source
AI summary
An intelligent power switch (IPS) circuit providing current protection for a power switch, a gate terminal of the power switch being controlled by a first control signal generated by a gate driver. The IPS circuit includes a first circuit to measure a current in the power switch, determine a first difference between a first voltage and a first reference voltage, and reduce the first control signal if the first difference exceeds a first predetermined limit; and a second circuit to measure the current in the power switch and determine a second difference between the first voltage and a second reference voltage, wherein if the second difference exceeds a second predetermined limit the first control signal is set to turn OFF the power switch.