Current Detection Circuit for Power Semiconductor Devices
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Solution Overview
Problem
Conventional current detection methods for power semiconductor devices, such as those using DCCTs and shunt resistors, face issues with size, loss, and precision, particularly in inverter applications, where high precision is required for efficient and compact power conversion.
Innovation Solution
A current detection circuit that employs a sense function in power semiconductor devices with divided regions, utilizing a current-voltage conversion circuit, output level regulator, current direction detection circuit, and variable voltage sources to correct for differences in characteristics between main and sense regions, enabling digital control and high precision detection with a reduced circuit scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DCCTs are used for current detection, then current detection function is achieved, but device size increases
Solution Approach 1:
The invention extracts the current detection function from external devices (DCCTs) and integrates it directly into the power semiconductor device by utilizing a sense region within the device structure itself, thereby eliminating the need for separate detection devices and reducing overall size
Solution Approach 2:
The power semiconductor device is designed to perform multiple functions: the main region handles power switching while the sense region performs current detection, allowing a single device to serve both power conversion and measurement purposes without requiring separate components
2Measurement precision
If shunt resistors are used for current detection, then current detection is achieved, but power loss increases
Solution Approach 1:
The sense region utilizes the natural voltage drop that occurs during normal operation of the power semiconductor device to generate the detection signal, eliminating the need for additional power-dissipating shunt resistors and achieving energy-efficient current measurement
3Volume of stationary object
If sense function is integrated into power semiconductor device, then device size is reduced, but detection precision decreases due to characteristic differences between main and sense regions
Solution Approach 1:
The control circuit receives the detection signal from the sense region and uses feedback mechanisms to compensate for characteristic differences between the main and sense regions, thereby maintaining high detection precision despite the integrated structure
Solution Approach 2:
The control circuit adjusts detection parameters and applies correction based on the detected signal to account for manufacturing variations and characteristic differences between regions, ensuring accurate current measurement
4Adaptability or versatility
If separate detection circuits are provided for IGBTs and FWDs, then detection coverage is complete, but circuit complexity increases
Solution Approach 1:
The invention merges the detection circuits for IGBTs and FWDs into a single integrated detection system that processes signals from both device types, reducing circuit complexity while maintaining complete detection coverage for all power semiconductor devices in the inverter
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 achieves high precision current detection with reduced size and loss, allowing for compact and efficient power conversion systems by correcting linearity between main and sense currents and eliminating the need for separate detection circuits for IGBTs and FWDs.
Implementation Method 1
a current-voltage conversion circuit (24) which converts the current into a voltage signal
Data Source
AI summary
A current detection circuit for a power semiconductor device utilizes a sense function of the power semiconductor device. The magnitude of current flowing in power semiconductor devices 1, 11 is detected by a current-voltage conversion circuit 24 connected to sense terminals S, S of the power semiconductor devices. The detected signal is delivered to a current direction detection circuit 27, which detects the direction of the current and delivers the detected current direction signal to an external CPU 3, which in turn gives gain-setting and offset-setting signals corresponding to the current direction signal. An output gain adjuster 221 adjusts the magnitude of gain and an output offset adjuster 231 adjusts the magnitude of offset to correct for differences between the characteristics of the sense regions and the main regions of the power semiconductor devices.