The PMP22650 reference design is a 6.6-kW, bidirectional, onboard charger. The design employs a two-phase totem pole PFC and a full-bridge CLLLC converter with synchronous rectification. The CLLLC utilizes both frequency and phase modulation to regulate the output across the required regulation range. The design uses a single processing core inside a TMS320F28388D microcontroller to control both the PFC and CLLLC. Synchronous rectification is implemented via the same microcontroller with Rogowski coil current sensors. High density is achieved through the use of high-speed GaN switches (LMG3522). The PFC is operating at 120 kHz and the CLLLC runs with a variable frequency from 200 kHz to 800 kHz. A peak system efficiency of 96.5% was achieved with an open-frame power density of 3.8 kW/L.
While the design calculations were done for a 6.6-kW output power, the design represents a suitable starting point for a 7.x-kW (for example, 7.2-kW to 7.4-kW) rated OBC operating from a 240-V input with a 32-A breaker.
Parameter | Min | Typ | Max | Units |
---|---|---|---|---|
AC Input Voltage | 90 | 240 | 264 | V |
AC Input Current | 32 | A | ||
DC Output Voltage | 250 | 400 | 450 | V |
DC Output Current (Constant Current mode) | 20 | A | ||
DC Output Power (Constant Power mode), VIN > 210 VRMS | 6.6 | kW |
Total volume: 105.8 in3
The power density achieved in this design is 3.8 kW/L (62.5 W/in3). The total system efficiency is 96.5%. The PFC has an efficiency of 98.5% and the CLLLC is 98%.
Efficiency data is provided in the following graphs with and without 12-V bias power. The bias supplies power to control, isolators, and gate drive. The graph in Figure 3-1 was taken under the following conditions:
The graph in Figure 3-2 was taken under the following conditions:
The graph in Figure 3-3 was taken under the following conditions:
The following figures summarize the total system efficiency, system losses, total harmonic distortion (THD), and the normalized output voltage regulation accuracy.
The power density achieved in this design is 3.8 kW/L (62.5 W/in3). This comes with a total system efficiency of 96.5%. Loads above 1.5 kW have a THD < 5% and the regulation accuracy of the output voltage is roughly within ±0.06%.
The graphs in Figure 3-4 use the following conditions:
The following bode plots were acquired using the onboard software frequency response analyzer inside the TMS320F28388D microcontroller. The load used in the tests was configured as a constant current sink. The microcontroller is configured to regulate a constant output voltage. The bandwidth is roughly from 1 kHz to 2.5 kHz with a phase margin in excess of 45°.
The following bode plots were acquired using the onboard software frequency response analyzer inside the TMS320F28388D microcontroller. The load used in the tests was configured as a constant voltage. The microcontroller is configured to regulate a constant output current. The bandwidth is roughly from 1 kHz to 2.5 kHz with a phase margin in excess of 60°.
The following table shows efficiency and regulation data.
VOUT (V) |
IOUT (A) |
POUT (W) |
VIN (V) |
IIN (A) |
PIN (W) |
VBIAS (V) |
IBIAS (A) |
PBIAS (W) |
Eff (%) No Bias |
Eff (%) With Bias |
---|---|---|---|---|---|---|---|---|---|---|
352.76 |
0.5 |
177.35 |
240.12 |
1.17 |
215.36 |
11.92 |
1.24 |
14.73 |
82.35 |
77.08 |
352.74 |
1 |
354.12 |
240.05 |
1.79 |
391.84 |
11.92 |
1.23 |
14.67 |
90.37 |
87.11 |
352.72 |
1.5 |
530.65 |
239.98 |
2.49 |
572.25 |
11.92 |
1.24 |
14.8 |
92.73 |
90.39 |
352.71 |
2 |
706.27 |
239.91 |
3.23 |
753.97 |
11.92 |
1.24 |
14.78 |
93.67 |
91.87 |
352.7 |
2.5 |
882.52 |
239.84 |
3.97 |
936.83 |
11.92 |
1.24 |
14.76 |
94.2 |
92.74 |
352.7 |
3 |
1058.9 |
239.76 |
4.72 |
1118.95 |
11.92 |
1.23 |
14.71 |
94.63 |
93.41 |
352.7 |
3.5 |
1235.3 |
239.69 |
5.48 |
1301.58 |
11.92 |
1.23 |
14.65 |
94.91 |
93.85 |
352.69 |
4 |
1411.74 |
239.62 |
6.23 |
1484.44 |
11.92 |
1.23 |
14.61 |
95.1 |
94.18 |
352.69 |
4.5 |
1587.99 |
239.55 |
6.99 |
1667.43 |
11.92 |
1.22 |
14.57 |
95.24 |
94.41 |
352.69 |
5 |
1763.62 |
239.47 |
7.75 |
1849.94 |
11.92 |
1.22 |
14.51 |
95.33 |
94.59 |
352.69 |
5.5 |
1939.96 |
239.4 |
8.51 |
2031.56 |
11.93 |
1.21 |
14.48 |
95.49 |
94.82 |
352.69 |
6 |
2116.85 |
239.32 |
9.27 |
2212.59 |
11.93 |
1.21 |
14.48 |
95.67 |
95.05 |
352.68 |
6.5 |
2293.18 |
239.25 |
10.02 |
2392.72 |
11.93 |
1.21 |
14.46 |
95.84 |
95.26 |
352.68 |
7 |
2469.51 |
239.17 |
10.78 |
2572.43 |
11.93 |
1.21 |
14.4 |
96 |
95.46 |
352.67 |
7.5 |
2645.17 |
239.1 |
11.53 |
2751.5 |
11.93 |
1.19 |
14.16 |
96.14 |
95.64 |
352.68 |
8 |
2821.8 |
239.02 |
12.29 |
2931.48 |
11.94 |
1.16 |
13.85 |
96.26 |
95.81 |
352.69 |
8.5 |
2998.24 |
238.95 |
13.04 |
3111.5 |
11.94 |
1.14 |
13.56 |
96.36 |
95.94 |
352.71 |
9 |
3174.78 |
238.87 |
13.8 |
3292.5 |
11.95 |
1.11 |
13.26 |
96.43 |
96.04 |
352.72 |
9.5 |
3350.46 |
238.79 |
14.56 |
3472.6 |
11.95 |
1.09 |
12.99 |
96.48 |
96.12 |
352.76 |
10 |
3527.33 |
238.71 |
15.33 |
3654.7 |
11.95 |
1.07 |
12.76 |
96.51 |
96.18 |
352.79 |
10.5 |
3704.19 |
238.63 |
16.09 |
3837.2 |
11.96 |
1.05 |
12.52 |
96.53 |
96.22 |
352.84 |
11 |
3881.08 |
238.54 |
16.87 |
4020.3 |
11.96 |
1.03 |
12.37 |
96.54 |
96.24 |
352.91 |
11.5 |
4058.4 |
238.46 |
17.64 |
4204.2 |
11.96 |
1.02 |
12.24 |
96.53 |
96.25 |
352.92 |
12 |
4235 |
238.37 |
18.42 |
4387.9 |
11.96 |
1.02 |
12.16 |
96.51 |
96.25 |
352.93 |
12.5 |
4411.3 |
238.28 |
19.2 |
4571.5 |
11.96 |
1.01 |
12.08 |
96.5 |
96.24 |
352.96 |
13 |
4588.2 |
238.18 |
19.98 |
4756 |
11.96 |
1 |
12 |
96.47 |
96.23 |
352.99 |
13.5 |
4765.1 |
238.09 |
20.77 |
4940.9 |
11.96 |
1 |
11.92 |
96.44 |
96.21 |
353 |
14 |
4941.9 |
237.99 |
21.55 |
5125.8 |
11.97 |
0.99 |
11.86 |
96.41 |
96.19 |
353.02 |
14.5 |
5118.9 |
237.89 |
22.34 |
5311.4 |
11.97 |
0.99 |
11.79 |
96.38 |
96.16 |
353.02 |
15 |
5294.8 |
237.79 |
23.13 |
5496.4 |
11.97 |
0.98 |
11.73 |
96.33 |
96.13 |
353.02 |
15.5 |
5471.6 |
237.68 |
23.92 |
5682.4 |
11.97 |
0.98 |
11.69 |
96.29 |
96.09 |
353.03 |
16 |
5648.3 |
237.62 |
24.71 |
5868.9 |
11.97 |
0.97 |
11.64 |
96.24 |
96.05 |
353.05 |
16.5 |
5825.2 |
237.51 |
25.51 |
6056.1 |
11.97 |
0.97 |
11.59 |
96.19 |
96 |
353.02 |
17.5 |
6176.6 |
237.26 |
27.13 |
6432.3 |
11.97 |
0.96 |
11.52 |
96.03 |
95.85 |
353.02 |
18 |
6353.2 |
237.14 |
27.94 |
6621.6 |
11.97 |
0.96 |
11.49 |
95.95 |
95.78 |
353.03 |
18.5 |
6529.8 |
237.01 |
28.76 |
6812.2 |
11.97 |
0.96 |
11.47 |
95.85 |
95.69 |
353.05 |
19 |
6706.8 |
236.87 |
29.59 |
7004.3 |
11.97 |
0.96 |
11.44 |
95.75 |
95.6 |
The following image is taken under full load operation. All of the significant heat generation components are connected to the cold plate on the bottom side of the board. The hottest components visible in this image come from the common-mode inductors in the EMI filter. These parts have no access to the cold plate and receive all their cooling via the ambient air.
GaN FET temperatures are provide by means of the onboard temperature sensors inside the LMG3522 devices. Under full load conditions, all FET temperatures are less than 75°C.
Table 3-1 lists the GaN FET temperature measurements under the following conditions:
GaN FET | Temperature (°C) |
---|---|
PFC | 66.8 |
CLLLC Primary (350 V/19 A) | 58.1 |
CLLLC Secondary (350 V/19 A | 59.5 |
CLLLC Primary (300 V/19 A) | 61.0 |
CLLLC Secondary (300 V/19 A) | 74.0 |
Figure 3-8 shows the critical transformer temperatures under the following conditions:
Figure 4-1 shows the PFC input voltage and input current waveform measured at the following parameters:
Figure 4-2 shows the PFC GaN drain voltage waveform measured at the following parameters:
A zoom-in of the GaN switch drain-to-source voltage transition is shown to be approximately 20 ns in Figure 4-3. This rapid transition comes from the low COSS of the LMG3522.
The waveform in Figure 4-3 was measured using the following parameters:
Figure 4-4 shows CLLLC operation at 19 A (6.6 kW) under the following parameters:
Figure 4-5 shows CLLLC operation at 10 A and the following parameters:
A zoom-in of the GaN switch drain-to-source voltage transition is shown to be approximately 40 ns in Figure 4-6. This rapid transition comes from the low COSS of the LMG3522.
The waveform in Figure 4-6 is measured using the following parameters:
The waveform in Figure 4-7 is measured using the following parameters:
A zoom-in of the GaN switch drain-to-source voltage transition is shown to be approximately 75 ns in Figure 4-8. This rapid transition comes from the low COSS of the LMG3522. The slightly longer transition time in this image comes from the lighter load condition and the resulting reduced current flow.
The waveform in Figure 4-8 is measured using the following parameters:
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATASHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS. |
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable standards, and any other safety, security, or other requirements. These resources are subject to change without notice. TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these resources. |
TI’s products are provided subject to TI’s Terms of Sale (www.ti.com/legal/termsofsale.html) or other applicable terms available either on ti.com or provided in conjunction with such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for TI products. |
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2021, Texas Instruments Incorporated |