Patent ID: 11923759
Assignee: TOSHIBA MITSUBISHI—ELECTRIC INDUSTRIAL SYSTEMS CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 5:
6. A driving method for a power conversion device, the power conversion device including
an inverter which includes switching elements, and which performs PWM control for ON/OFF driving the switching elements on the basis of an output voltage command value and an output frequency command value, thereby converting received DC voltage of a DC voltage source to variable-voltage variable-frequency AC voltage and outputting the AC voltage to a load, and
a series unit of a positive-side capacitor and a negative-side capacitor, the series unit being connected on an input side of the inverter between a positive side and a negative side of the DC voltage,
the inverter having, as output potentials, at least a positive-side potential and a negative-side potential of the DC voltage source and a potential of a neutral point which is a connection point between the positive-side capacitor and the negative-side capacitor,
the driving method comprising:
calculating a modulation factor for the inverter on the basis of the DC voltage of the DC voltage source and the output voltage command value;
calculating a number of pulses per half cycle of a fundamental wave in the PWM control on the basis of the output frequency command value;
in accordance with the calculated number of pulses, calculating and determining a switching pattern for specifying switching phases which are timings of ON/OFF driving the switching elements, so as to satisfy conditions for
ensuring the calculated modulation factor,
eliminating harmonic components for respective orders of output voltage of the inverter,
ensuring a predetermined value for a phase difference between predetermined adjacent ones of the switching phases, and
balancing voltage of the positive-side capacitor and voltage of the negative-side capacitor; and

driving the switching elements by the determined switching pattern.