Dead zone adjustment control method suitable for soft start of dual active bridge

Abstract

The invention belongs to the converter control technical field and relates to a dead zone adjustment control method suitable for the soft start of a dual active bridge. The method can achieve wide-range starting surge current limiting. According to the technical schemes of the invention, the method includes the following steps that: 1) a switching frequency is selected, a system starts working, and initial dead zone time is selected according to the parameters of the system; 2) the voltage of a bus-bar capacitor is collected and fed back to the primary side of the DAB (dual active bridge); 3)time dt is calculated according to a formula described in the descriptions of the invention; and 4) dead zone time is adjusted, charging is continuously carried out until pre-charging is terminated.

Description

Technical field: [0001] The invention belongs to the technical field of converter control, and in particular relates to a dead zone regulation control method suitable for soft start of dual active bridges. Background technique: [0002] Isolated bidirectional full bridge DC / DC converter, also known as dual active bridge DAB (Dual Active Bridge). Due to the electrical isolation of the front stage and the back stage, the system has higher reliability. And based on the leakage inductance of the transformer between the input and output of the converter, the bidirectional flow of energy can be realized. The converter has been widely used in bidirectional AC / DC chargers. The AC / DC topology in the bidirectional AC / DC charger can not only realize the function of charging Grid-to-Vehicle (G2V), but also complete the function of grid-connected V2G (Vehicle-to-Grid). When the PWM signal phase of the Mosfet at the primary end of the DAB is ahead of the secondary end, the grid-connecte...

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Problems solved by technology

When the system works in the V2H state, the voltage at both ends of the bus capacitor is 0 due to complete discharge. The problem is that when the system is powered on after the capacitor is fully discharged, the secondary side of the transformer can be considered to be in a short circuit state because the voltage at both ends of the capacitor is 0. , which is equivalent to a short circuit on the primary side of the transformer, so its current can reach tens or hundreds of amperes in the first few cycles of DAB work, which can directly burn out the switching device or cause the system to be paralyzed; Both the switching frequency and the phase-shifting method have certain defects in limiting the start-up inrush current: (1) By increasing the switching frequency, when the bus capacitor is completely discharged, the equivalent impedance of the input voltage in the first few working cycles of the DAB is Z=2 *π*f*L (f is the switching frequency, L is the leakage inductance of the transformer), from this formula, it can be seen that when the switching frequency increases, the inrush current can be reduced due to the increase of the impedance

But at the same time, due to the increase of the switching frequency f, the power consumption of the driver chip of the switch tube increases, and the power consumption of the gate-level drive resistor increases. Too high switching frequency can cause damage to the gate-level resistor or the driver chip and make the system paralyzed

(2) The phase-shift control method is based on the dual-phase-shift DAB control method, and its control strategy is relatively complex. Compared with the single-phase-shift control method, the stability and controllability of multiple systems with voltage and current sampling points are lower

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