Three-level bidirectional direct-current converter and pulse width control method thereof

Abstract

The invention discloses a three-level bidirectional direct-current converter and a pulse width control method thereof and relates to the technical field of power conversion of power electronics. A first filter capacitor and a second filter capacitor on the high-voltage direct-current side of the three-level bidirectional direct-current converter disclosed by the invention can realize self-balance control within a carrier cycle under a pulse width control method, so that the voltage fluctuations of the capacitors can be reduced effectively; the voltage stress of a power device can be equalized to beone half of the voltage on the high-voltage direct-current side, and pulse width voltage amplitudes outputted by two half-bridges are one half of the voltage on the high-voltage direct-current side, so that a filter inductance value and the capacities of the capacitors can be reduced, and dv / dt (change in voltage over change in time) is also reduced; and compared with the traditional three-level bidirectional direct-current converter, the three-level bidirectional direct-current converter disclosed by the invention does not need a transformer while realizing energy conversion with large conversion ratio between the high-voltage direct-current side and the low-voltage direct-current side and can further prevent a power switch from working in an extreme duty cycle state.

Description

Technical field [0001] The invention relates to the technical field of power electronic power conversion, to a power conversion device in a DC power conversion system, and in particular to a three-level bidirectional DC converter and a pulse width control method thereof. Background technique [0002] With the continuous development and utilization of renewable energy, the generated electricity needs to be transmitted or stored in a reasonable way. For example, in photovoltaic power generation and fuel cell power generation technology, the direct current generated by the power generation end can be more stable through the direct current converter On the one hand, the DC bus voltage can be converted into AC power by an inverter to supply power to the AC load; on the other hand, it can also be used directly or again to supply power to the DC load through a DC converter. In order to store the excess energy, and in the case of insufficient light or fuel, the energy storage unit can pr...

AI Technical Summary

Problems solved by technology

[0005] Traditional two-level bidirectional DC converters have outstanding problems such as large power switch voltage stress, large switching losses, large filter volume, and high dv / dt in high-voltage conversion applications. The existing three-level bidirectional DC converters solve the above problems , but in special occasions with large conversion ratios, the power switch will be difficult to respond to extremely narrow pulse driving signals, and the power switch is prone to extreme duty cycle problems

Images