SPRACN0F October 2021 – March 2023 F29H850TU , F29H859TU-Q1 , TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378D , TMS320F28378S , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S , TMS320F28384D , TMS320F28384S , TMS320F28386D , TMS320F28386S , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1
Power transfer in single phase shift DAB is related to the coupling inductance (L) value and the switching frequency (Fs) and the phase (θ).
where
For improved power density (smaller overall physical dimensions of the design), both lower inductance and higher switching frequency are necessary. A reference example is TIDA-010054, which is a 10kW DC-DC DAB converter: 100 kHz PWM switching frequency is used along with a 35 μH for the leakage inductor. A three phase PFC with 800 V bus such as Vienna Rectifier (TIDM-1000), or T-Type PFC (TIDA-010039) is used as the front end. Finally, for an output voltage of 400V at 10kW we can then determine the resultant output steps in the voltage the phase shift causes and check if it allows it to be within the ± 1% of our ripple requirement.
As shown in #GUID-5C65AC8D-92BC-449A-874A-5EAA71040ACF/GUID-97F41F90-5C7F-4EB1-B207-CF278D9AD650, the voltage cannot be regulated to 1% accuracy about 400 V by using typical PWM generation logic that is clocked at MCU clock rate. Assuming a 100 MHz CPU clock, would result in 10 ns step changes that is too large for our output ripple tolerance. Using the HRPWM module it is possible to modulate the phase shift to within 150 ps, regardless of the main MCU clock. More so, exceeding the phase step requirement represents the ability to modulate at a 13x step size within those bounds providing capability to find tune the output to more closely match the ideal.
Vin=800V, Pout=10kW, Fs=100kHz | Vout (V) | Required Phase Shift (ns) |
---|---|---|
θ = 19.032 deg | 400 | 528.66 |
θ = 18.9249 deg | 402 | 525.69 |
θ = 18.7662 deg | 405 | 521.11 |
θ = 18.5077 deg | 408 | 517.10 |