Development Of 15kW Hybrid Clamped Five-level Topology

The multilevel inverter has become one of the most active technologies in recent years because of its low THD, low switching frequency and low switch stress. The diode clamped topology and the flying capacitor clamped topology can't balance their capacitor voltage in open loop because of the unbalance of the DC-link capacitors when they are extended into the five level or higher level. The hybrid clamped topology achieve the balance of all the capacitors in open loop by changing the parallel connections of the DC-link capacitors and the flying capacitors.The hybrid clamped multilevel inverter has been widely applied recently. A new method for choosing the values of the DC-link capacitor and auxiliary capacitors which is based on switching transitions principle is proposed in the paper. The traditional way of capacitor choice in the hybrid clamped multilevel topology was mainly depended on engineering experience and estimate. The new method can not only ensure that the system run steadily, but also save superabundant resource spending. The feasibility and correctness of this new method is validated by theoretic calculation, simulation analysis and experiments. Furthermore, the proposed method can be easily expanded and applied for other multilevel topologies.The power loss of the IGBTs and diodes is calculated by analyzing the PWM, then the thermal design of the whole system is given and the temperature of the IGBTs and the diodes is calculated. Then the work of current test is given, and the numerical value of stray inductance in every down-lead is calculated. The total numerical value of stray inductance in every current switching loop is calculated. Several new hybrid clamped topologies are proposed, their feasibility is validated by simulation.