Abstract: A charge mode pulse-width modulation control method and apparatus includes setting up a detector at a primary side of a transformer to detect a current and feeding back the detected current to a current apparatus to provide a current output; an integrator providing charge output with a voltage mode, where the charges are supplied by the integrator which takes the output current of current source to implement mathematical integration, and produce an output voltage and providing the output voltage to a main controller as a reference for deciding whether or not to switch a switch. The control system can prevent the transformer from reaching magnetic saturation and the feedback control current signal from generating noises.

Abstract: A current detection method for a direct-current (DC) to three-phase alternating-current (AC) converter can utilize only a single DC sensor to detect and calculate the three-phase alternating currents. The method can detect a direct current value of one phase at each of six different gate states of three pairs of transistors in the DC to three-phase AC converter by means of the DC sensor. In the two-level pulsewidth modulation control, the control signal includes a plurality of carrier periods each being subdivided into three intervals. The three pairs of transistors are switched to the zero state in one interval of each carrier period, and to two different gate states respectively in the two other intervals. The method can detect two current values of different phases respectively in the two other intervals of each carrier period, and then calculate the current value of the other phase in accordance with the principle that the sum of the three-phase currents is always equal to zero.