CHARGING DEVICE FOR CAPACITOR

PROBLEM TO BE SOLVED: To provide a charging device for a capacitor which eliminates the need of a snubber circuit by cutting off a zero current of a semiconductor switching element and reduces a switching loss during current cutoff.SOLUTION: When a charge signal outputted from a charge signal generation part 14 rises, On control is simultaneously performed on a semiconductor switching elements 2 and 7, a current is made flow through a route that is shown as (1) in the figure, and energy is stored in a reactor 3. Next, OFF control is performed only on the semiconductor switching element 7, a current flows through a route that is shown as (2) in the figure, and charging is performed by shifting the stored energy in the reactor 3 to a capacitor 6. An arithmetic circuit 26 calculates a current flowing time ΔT in the route (1) and a time T from the end of the period ΔT to the current of the reactor 3 in the route (2) becoming zero. The OFF control is performed on the semiconductor switching element 2 during a time from a time (ΔT+T end time) in which the current of the reactor 3 becomes zero by completing charge of the capacitor 6, to the end of an ON period of the charge signal.SELECTED DRAWING: Figure 1 【課題】半導体スイッチング素子の零電流遮断によってスナバ回路を不要とし、電流遮断時のスイッチング損失を低減させたコンデンサの充電装置を提供する。【解決手段】充電信号発生部１４が出力する充電信号の立ち上がりで半導体スイッチング素子２、７を同時にオン制御し、図示（１）の経路で電流を流し、リアクトル３にエネルギーを蓄積する。次に半導体スイッチング素子７のみをオフ制御すると図示（２）の経路で電流が流れ、リアクトル３の蓄積エネルギーがコンデンサ６に移行し充電が行われる。演算回路２６は、前記経路（１）における電流通流時間ΔＴと、ΔＴ期間が終了してから前記経路（２）におけるリアクトル３の電流が零になるまでの時間Ｔとを演算しておく。コンデンサ６の充電完了によりリアクトル３の電流が零となる時刻（ΔＴ＋Ｔ終了時刻）から充電信号のオン期間が終了するまでの間の時刻に半導体スイッチング素子２をオフ制御させる。【選択図】図１