Infineon's latest generation IGBT technology platform enables precise control of speed and position

As Infineon's latest generation IGBT technology platform, the performance comparison between IGBT7 and IGBT4 has always been a concern for engineers. This article tests FP35R12W2T4 and FP35R12W2T7 in the same platform servo drive, and obtains the junction temperature comparison between IGBT4 and IGBT7 under the same working conditions. The experimental results show that in the comparison test of continuous high-power load conditions and inertia disk load conditions, the junction temperature of IGBT7 is lower than that of IGBT4.

The servo drive system has a fast response speed, high overload multiples, and the trend of miniaturization and high power density has put forward more stringent requirements on power devices. Infineon's star product IGBT7 perfectly meets all the needs of servo drives with its ultra-low on-state voltage drop, controllable dv/dt, and 175℃ overload junction temperature. Infineon, Jingchuan, and Maixin jointly developed a complete servo drive solution based on IGBT7, which can significantly improve power density. The driver chip uses Infineon's coreless transformer 1EDI20I12MH. Because of the unique capacitor structure of IGBT7, it is not easy to parasitic conduction, so a single power supply design can be used, which simplifies the drive design to the greatest extent. The main control MCU uses XMC4700/4800, and the motor position detection uses TLE5109 to achieve precise control of speed and position.

In order to compare the performance of IGBT4 and IGBT7 in servo drive, we used two servo drives on the same platform, equipped with FP35R12W2T4 and FP35R12W2T7 with the same PIN pin layout, and tested them under the same dv/dt conditions (dv/dt=5600V/us).

We designed two typical working condition comparison schemes to compare the junction temperature of IGBT4 and IGBT7 under the same working conditions, namely continuous large load comparison test and inertia load comparison test. The IGBT chip in the IGBT module to be tested is pre-embedded with a thermocouple. By connecting the thermocouple to the data acquisition instrument, the junction temperature of the IGBT chip can be directly read.

Continuous large load comparison test

Two motors are used for loading, the motor system under test works in the electric state, and the load motor system works in the power generation state;

The motor under test is driven by a driver based on IGBT4 and IGBT7 respectively. The switching frequency and output current/power of the two drivers are the same each time they are loaded.

Use a power analyzer to test the input power and output power of the driver and calculate the loss and efficiency of the driver.

The figure below is a comparison of the junction temperatures of IGBT4 and IGBT7 under continuous high load conditions.

It can be seen that after loading for 13 minutes at 8K switching frequency, the junction temperature difference between IGBT7 and IGBT4 is 17°C. As the loading time increases, the junction temperature difference is still on an upward trend.

We also compared the temperature rise of IGBT7 and IGBT4 under different switching frequencies and the same output power (5.8KVA), as shown in the figure below. The horizontal axis is the switching frequency of the IGBT; the vertical axis on the left is the temperature rise of the NTC temperature compared to the initial temperature. The vertical axis on the right is the temperature rise difference between IGBT4 and IGBT7. As the switching frequency increases, the NTC temperature rise of IGBT7 and IGBT4 becomes larger; at a switching frequency of 10K, the NTC temperature rise of IGBT7 is 19°C lower than that of IGBT4. As you can see. Since IGBT7 can operate at a higher junction temperature, it can achieve a higher output power and realize power jump.

Inertia load comparison test

The two motors are equipped with IGBT4 and IGBT7 respectively. The motors have the same inertia disk load. The time from 1500 rpm to -1500 rpm is 250 milliseconds, and the steady-speed operation time is 1.2 seconds. Under the steady-speed operation condition, the phase output current is less than 0.5A; therefore, the average power of this test condition is relatively small.

The motor heat dissipation conditions are the same, and the switching frequency is 8kHz.

Inertia load test platform

Inertia disc load test conditions

The measured junction temperature curve is as follows:

It can be seen that under the acceleration and deceleration operation condition with inertia disk, the junction temperature of IGBT7 is lower than that of IGBT4. After 13 minutes of operation, the temperature rise of the driver has not reached the equilibrium state, and the junction temperature difference is about 7°C.

Finally, we make a summary of this part of the test:

With the same output power, the junction temperature of the driver using IGBT7 is significantly lower, allowing the size of the heat sink to be reduced, and thus the size of the driver can be reduced;

If the heat dissipation conditions are the same, IGBT7 can output greater power and achieve power jump;

In addition, IGBT7 can operate at a higher junction temperature and therefore can output greater power.