SLUP412 February 2022 LMG3522R030-Q1
- 1 Introduction
- 2 Comparing Different Technologies
- 3 Advantages of Integrating the Driver With GaN FETs
- 4 The GaN-Based 6.6-kW OBC Reference Design
- 5 PFC Stage
- 6 DC/DC Stage
- 7 DC/DC Topology Selection
- 8 Frequency Selection
- 9 Core Loss
- 10Loss of ZVS
- 11Dead Time
- 12ISR Bandwidth
- 13Overall
- 14Resonant Tank Design
- 15Thermal Solution
- 16Layout Best Practices
- 17Control-Loop Considerations
- 18Conclusions
- 19References
- 20Important Notice
4 The GaN-Based 6.6-kW OBC Reference Design
The GaN-Based 6.6-kW Bidirectional Onboard Charger Reference Design [2] supports operation from a universal single-phase input off the AC grid and provides full output power (6.6 kW) to the load at an input voltage of 208 VAC and above. Below this input voltage level, the output power is linearly derated. The main target of this reference design is to deliver the maximum possible power to the battery, with a power density level greater than 60 W/inch3 (3.66 kW/L) and a battery voltage range between 250 V and 450 V. Additionally, this OBC design supports bidirectional operation. Table 4-1 lists the power-supply specifications.
| Parameter Description | Minimum | Typical | Maximum | Units |
|---|---|---|---|---|
| AC input voltage | 90 | 220 | 264 | VRMS |
| AC input current | 32 | ARMS | ||
| DC output voltage | 250 | 400 | 450 | V |
| DC output current (CC mode) | 20 | A | ||
| DC output power (CP mode) | 6.6 | kW | ||
| Power density | 60 | W/inch3 | ||
| EMI compliance level | CISPR 32, Class B [9] | |||
| AC line frequency | 47 | 63 | Hz | |
| Power factor (full load) | 0.99 | |||
| Cold-plate coolant temperature | 65 | 85 | °C |
Figure 4-1 is a block diagram of the 6.6-kW OBC reference design.
Figure 4-1 Block diagram of the 6.6-kW
OBC reference design.Both the PFC stage and the DC/DC converter leverage 30-m? automotive-qualified 650-V LMG3522R030-Q1 GaN FETs for control by a single C2000? TMS320F28388D real-time microcontroller (MCU). In total, the converters use 12 GaN FETs; the low-frequency FETs for the bridgeless input rectifier are regular silicon MOSFETs.