CONTROL OF PWM CONTROL CURRENT-TYPE POWER CONVERTER

摘要

PURPOSE: To reduce a switching loss and to prevent the size enlargement of the equipment by allowing current to flow continuously when a period wherein a residual-phase conduction current is zero is shorter than the specified value and by letting each semiconductor switching element conduct on/off operation to allow reverse-polarity current to flow. ;CONSTITUTION: When comparing the magnitude of an R-phase sine wave signal 11 and of a first carrier wave signal 12 and comparing the magnitude of a T-phase sine wave signal 13 and a second carrier wave signal 14, a current zero period is generated in an S-phase PWM current pattern. However, when the current zero period is shorter than the specified value, current is allowed to flow continuously. While the S-phase PWM current is allowed to flow in a part, the R-phase PWM current and the T-phase PWM current are allowed to flow to maintain the condition that the sum of instant values of three-phase ac input current is zero, and the S phase PWM current is allowed to flow continuously to reduce the number of the current zero periods. As a result, the number of operations of the semiconductor switching elements can be reduced and thereby a switching loss is reduced and at the same time, the power converter is not required to be a large-size one.;COPYRIGHT: (C)1993,JPO&Japio