Power conversion system

A power conversion system comprising:

• a fixed pulse pattern modulation unit configured to refer to tables storing therein pulse patterns that determine respective command voltage levels corresponding to phase information for each modulation ratio and to generate a gate signal on the basis of a command modulation ratio and a control phase, wherein the power conversion system drives a power converter on the basis of the gate signal, wherein
• the fixed pulse pattern modulation unit has:
• a transition index search unit configured to output a transition table index on the basis of the command modulation ratio;
• a transition switch configured to input the transition table index and a table index previous value and output, as a table index, the transition table index in a case of presence of the transition and the table index previous value in a case of absence of the transition;
• a table comparison unit configured to perform a table comparison on the basis of the table index and the control phase and output the gate signal;
• and
• a buffer configured to delay the table index by one control period and output the delayed table index as the table index previous value, and
• the fixed pulse pattern modulation unit is further configured to, when performing a pulse pattern transition, search for a proper post-transition table reference position and make a command voltage level follow a command voltage level of a post-transition pulse pattern.

A power conversion system comprising:

• a fixed pulse pattern modulation unit configured to refer to tables storing therein pulse patterns that determine respective command voltage levels corresponding to phase information for each modulation ratio and to generate a gate signal on the basis of a command modulation ratio and a control phase, wherein the power conversion system drives a power converter on the basis of the gate signal, wherein
• the fixed pulse pattern modulation unit has:
• a transition index search unit configured to output a transition table index on the basis of the command modulation ratio;
• a transition judgment unit configured to output a transition judgment result on the basis of the control phase and a control phase previous value;
• a transition switch configured to input the transition table index and a table index previous value and output, as a table index, the transition table index in a case of presence of the transition by the transition judgment result and the table index previous value in a case of absence of the transition by the transition judgment result;
• a table comparison unit configured to perform a table comparison on the basis of the table index and the control phase and output the gate signal;
• and
• a buffer configured to delay the table index by one control period and output the delayed table index as the table index previous value,
• transition timing of the pulse pattern is each vicinity of 0 rad, π/3 rad, 2π/3 rad, π rad, 4π/3 rad and 5π/3 rad of the control phase, and
• the fixed pulse pattern modulation unit is further configured to, when performing a pulse pattern transition, search for a proper post-transition table reference position and make a command voltage level follow a command voltage level of a post-transition pulse pattern.