Double pulse testing is a technique to measure the switching performance of power semiconductor devices (SiC, MOSFETs, IGBTs, etc.). Following a normal switching pulse, a second pulse is applied at a short interval to examine the response time and transient characteristics of the device. Double pulse testing is a very important role in growing the power conversion efficiency of power electronics.
Purpose of the test
The main characteristics of the test are as follows
- Measurement of switching parameters such as turn-on and turn-off times
- Measurement of switching losses (On Energy: EON, OFF Energy: EOFF)
- Assessments of reverse recovery characteristics (reverse recovery charge: QRR, etc.) of body diodes
- Observation of overshoot of voltage and current
- Analysis of device operation under different voltage and current conditions
Double pulse test setup
In addition to a high-voltage or DC power supply, an engineer needs a pulse generator such as a function generator and an oscilloscope to perform a double-pulse test. Inductive loads and appropriate probes are also required.
For a typical double-pulse test, a half-bridge circuit with two power devices under test is prepared. A gate driver circuit is also required.
Double pulse test procedure
- The first pulse is applied to the gate to accumulate current in the inductor.
- Turn off the device to measure turn-off characteristics. (Measurement of EOFF)
- A second pulse is applied to measure the turn-on characteristics. (EON and QRR measurements)
By adjusting the pulse width, switching characteristics can be tested at different current levels.
Main Measurements
In the double pulse test, the following parameters are measured
- Drain-Source voltage (VDS)
- Drain current (ID)
- Gate-Source voltage (VGS)
From the waveform, the following parameters can be measured
- Switching time (turn-on and turn-off)
- Switching energy loss
- dv/dt and di/dt rates
- Reverse recovery characteristics
Applications
- Characterization of power semiconductors (SiC, GaN, etc.)
- Gate drive circuit optimization
- EMI performance evaluation
- Validation of device models for simulation
The double pulse test provides detailed parameters on the switching operation, enabling the design of more efficient and reliable power electronics systems.
Considerations for Accurate Double Pulse Testing
To maximize the performance of power devices, it is important to obtain accurate device characteristics results through double pulse testing.
Accurate measurement requires an appropriate evaluation board, measuring instruments, and measurement environment. Testing with attention to the following items will improve the efficiency and reliability of application development.
Considerations for accurate test results
- Use of appropriate probes (e.g. differential probes for high-side measurements)
- Minimize parasitic inductance in measurement setups
- Consideration of thermal effects in high current/high voltage testing
- Refer to relevant standards (JEDEC, IEC, etc.) for parameter definitions.
- Keywords:
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- double pulse test
- power semiconductor
- switching characteristics
- turn-on parameters
- turn-off parameters
- Reverse recovery parameters
- recovery characteristics
