IGBT Gate Drive Circuit for Parallel Current Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing drive devices for parallel-connected insulated-gate semiconductor elements face challenges in evenly driving multiple elements with constant current, leading to potential thermal breakdown due to current concentration and temperature imbalances, especially when there are three or more elements connected in parallel.
Innovation Solution
A drive device that regulates drive voltages based on temperature detected by a temperature detecting element, using a constant current source and current mirror circuit to supply a constant current to each semiconductor element, ensuring balanced current flow and preventing thermal breakdown by adjusting drive voltages in response to temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a plurality of insulated-gate semiconductor elements are connected in parallel and driven with constant current, then the current flow speed and switching performance are improved, but current concentration occurs due to individual differences in gate threshold voltages, leading to thermal breakdown risk
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the drive voltage based on temperature feedback. The control circuit modifies the gate drive voltage parameter in response to temperature variations, ensuring that each parallel-connected semiconductor element operates within safe thermal limits while maintaining high current flow speed. This prevents current concentration and thermal breakdown by adapting the drive parameters to real-time temperature conditions.
Solution Approach 2:
The patent implements feedback control by using temperature detecting elements to monitor the temperature of each semiconductor element and feeding this information back to the control circuit. The control circuit then adjusts the drive voltage accordingly, creating a closed-loop system that prevents current concentration and thermal breakdown while maintaining optimal switching performance. This feedback mechanism ensures reliable operation even with individual differences in gate threshold voltages.
2Stability of the object's composition
If the gate threshold voltages of parallel-connected insulated-gate semiconductor elements are equalized, then current balance is improved, but the device complexity increases due to additional control circuits
Solution Approach 1:
The patent uses feedback control to maintain current balance without requiring complex pre-calibration circuits. Temperature detecting elements monitor each semiconductor element, and the control circuit adjusts drive voltages in real-time based on temperature feedback, automatically compensating for individual differences in gate threshold voltages. This approach achieves current balance through dynamic adjustment rather than static equalization, avoiding excessive device complexity.
Solution Approach 2:
The patent enables self-service operation where each parallel-connected semiconductor element's temperature is independently monitored and its drive voltage is automatically adjusted by the control circuit based on its own temperature feedback. This decentralized control approach achieves current balance without requiring complex centralized control, reducing overall device complexity while maintaining stable current distribution.
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 ensures balanced current distribution among multiple insulated-gate semiconductor elements, preventing thermal breakdown and reducing noise and losses by dynamically adjusting drive voltages based on temperature, thus maintaining consistent operation regardless of individual differences in gate threshold voltages.
Implementation Method 1
a temperature detecting element for detecting a temperature of the insulated-gate semiconductor element
Implementation Method 2
supplying a constant current to each of the parallel-connected IGBTs to turn the IGBTs ON raises the possibility that the current flows intensively to an IGBT of low gate threshold voltage
Implementation Method 3
the switching circuit 7 activates the discharge circuit 6 to cause the discharge circuit 6 to connect the gate of the IGBT 2a to the ground and discharge the electric charge accumulated in the gate
Data Source
Figure 1
Figure 2
AI summary
An object of the present invention is to drive a plurality of parallel-connected insulated-gate semiconductor elements in parallel in a balanced manner. When turning one of a plurality of parallel-connected IGBTs (2a) ON, while a constant current circuit (5) including a constant current source (8) and a current mirror circuit (9) performs constant current drive on the gate of the IGBT (2a), the voltage control circuit (10) outputs, to the constant current source (8) and the current mirror circuit (9), a voltage that fluctuates in response to a voltage difference ΔV between a diode voltage (Vf) and a reference voltage (Vref0), as a drive voltage (Vo1) for driving the gate of the IGBT (2a), the diode voltage (Vf) being output as a value corresponding to the temperature detected by a temperature detecting diode (12) contained in the IGBT (2a). As a result, the loss and noise that occur when the IGBT is turned ON can be reduced by the constant current drive. In addition, the turn-on timings and the current values of the flowing currents can be matched regardless of the variations in the gate threshold voltages caused by the individual difference among the plurality of IGBTs (2a).