IMWTEK UP006N08CT and Infineon OptiMOS ™ LLC resonance current sharing and high-frequency efficiency breakthrough of 6
1、 Application scenarios and technical challenges
The on-board charger (OBC) for electric vehicles needs to efficiently convert AC power into high-voltage DC power (such as 400V/800V), and the synchronous rectification MOSFET in its LLC resonant topology faces the following challenges:
High frequency requirements: In order to reduce the volume of magnetic components, the switching frequency needs to be increased to 80-100kHz, but high frequency will increase switching losses and drive difficulty.
Multi chip parallel current sharing: A single MOSFET is difficult to carry>30A current, and when multiple MOSFETs are connected in parallel, current imbalance occurs due to differences in parasitic parameters.
Vehicle reliability: requires AEC-Q101 certification and can withstand temperature cycling (-40 ° C to 150 ° C) and mechanical shock (50G).
The TOLL (TO Leadless) package is an ideal choice for high-frequency OBC due to its low parasitic inductance (<2nH) and bottom heat dissipation pads.
2、 Product comparison: IMWTEKUP006N08CT vs. Infineon OptiMOS ™ 6 BSC010N06LS6
Advantage analysis of parameter IMWTEK UP006N08CT Infineon BSC010N06LS6
Encapsulation TOLL-8 TOLL-8 with packaging benchmarking
Voltage level: 80V, 60V, 80V, suitable for 800V battery system's remaining capacity requirements
RDS (on) @ 10V 0.95m Ω 1.1m Ω reduces conduction loss by 13.6%
Qg (total) 32nC 38nC reduces driving loss by 15.8%
Thermal resistance R θ JA 25 ° C/W 30 ° C/W, with the same power consumption, the junction temperature is 5-7 ° C lower
Reverse recovery charge Qrr 20nC 35nC dead time loss reduced by 42%
3、 Practical testing: Verification of 11kW OBC LLC resonant module
Testing Platform:
Input/Output: AC 220V/50Hz → DC 800V/14A
Topology: Two phase interleaved LLC resonance+synchronous rectification
Switching frequency: 80kHz (full load)/40kHz (light load)
Cooling conditions: Liquid cooled plate (coolant flow rate 2L/min, inlet temperature 65 ° C)
Test project:
Efficiency and temperature rise: overall efficiency and MOSFET junction temperature distribution.
Current sharing performance: current imbalance degree (Δ I/I2 avg) when 4 wires are connected in parallel.
EMC compliance: CISPR 25 Class 5 radiated noise test.
Test results:
Efficiency performance:
IMWTEK UP006N08CT： The peak efficiency is 96.8% (Infineon solution 95.5%), and the difference in full load efficiency has widened to 1.8%.
Loss decomposition (Figure 1): The switching loss (Psw) of IMWTEK decreased by 28%, and the Qrr related loss decreased by 50%.
Current sharing performance:
IMWTEK UP006N08CT： When 4 are connected in parallel, Δ I/I2 avg is less than 4% (Infineon's solution is 7%), thanks to the symmetrical pin layout of the TOLL package.
Current waveform (Figure 2): The current overlap of each channel in IMWTEK reaches 95%, and Infineon experiences phase shift due to differences in parasitic inductance.
EMC testing:
IMWTEK UP006N08CT: Noise in the 30-100MHz frequency band is 6dB below the limit (Infineon's solution only meets the limit).
Spectrum comparison (Figure 3): The dV/dt of IMWTEK is suppressed to 20V/ns (compared to 35V/ns for competitors).
4、 Design suggestion: TOLL package parallel current sharing and heat dissipation optimization
Uniform current layout design:
Star shaped symmetrical wiring (Figure 4): Lead the driving signal out from the center point, ensuring that the length difference of the gate paths of each tube is less than 1mm.
Source Kelvin detection: Add independent sampling lines (with a line width of 0.5mm) to monitor the current of each MOSFET in real-time.
Drive circuit optimization:
Active Miller Clamp: Integrated UCC27611 driver, clamp the Miller platform voltage to below 2V to prevent false triggering.
Dynamic gate resistance: Use a 10 Ω resistor for light load (noise reduction), switch to 2 Ω for full load (acceleration).
Liquid cooling heat dissipation scheme:
The TOLL bottom pad is directly soldered to a copper aluminum composite substrate (thickness 3mm), reducing the thermal resistance to 18 ° C/W.
Channel design (Figure 5): The serpentine channel covers the MOSFET area, with a voltage drop of<0.2 Bar, to avoid local boiling.
5、 Cost and reliability analysis
BOM cost:
The price of a single TOL-80B40 is 12% lower than that of the Infineon BSC010N06LS6, and the efficiency improvement can reduce the power of the liquid cooling pump.
Based on a scale of 100000 sets of OBC, the annual cost savings are approximately $300000.
Reliability verification:
Temperature shock test:- Cycle 1000 times from 40 ° C to 125 ° C, and the shear force of the solder joint remains>4kgf (reduced to 3.2kgf in the Infineon solution).
Corrosion resistance test: After 1000 hours of testing with a mixture of 85 ° C/85% RH and 3.5% salt spray, the pins showed no corrosion.
6、 Industry Trends and Competitive Strategies
With the popularization of the 800V platform, the demand for OBC power density has increased from 3kW/L to 5kW/L. IMWTEKUP006N08CT has entered the supply chains of BYD and Tesla through TOLL packaging and copper clip bonding technology.
