# Misunderstanding from the author saying,about the current flowing path

The author show the working process of this schematic

1.The proposed system waits until the PZT device stores the energy vibrations produce during the positive half of vibration period $T_{VIB}$ before engaging switches $S_I$ and $S_N$ to discharge $C_{PZT}$ into off-chip harvesting inductor $L_H$

2.The inductor current $i_L$ rises to reach the peak, then the switches $M_{P1}$ and $S_I$ de-energize $L_H$ into the battery via $i_{BAT}^+$

3.The system again waits for the transducer to energize $C_{PZT}$ (in the negative direction) through the negative half of $T_{VIB}$ before prompting $S_I$ and $S_N$ to discharge $C_{PZT}$ into $L_H$, after which $M_{P2}$ and $S_N$ deenergize $L_H$ into the battery

I sort out what the author said:

1.the PZT will produce energy first,then $S_I$ and $S_N$ be "on" to let the current flow from $C_{PZT}$ to $L_H$

2.$M_{P1}$ and $S_I$ disconnect,and let the $i_{BAT}^+$ flow from the $L_H$ to the battery

3.when the PZT produce the negative part voltage,$S_I$ and $S_N$ are "on",and the negative current flow from the $C_{PZT}$ to $L_H$(this current direction is the oppsite of 1. current direction in the $L_H$ ),then $M_{P2}$ and $S_N$ disconnect to let the current flow from the $L_H$ to the battery

Hold on a second,i have a question about the 2. and 3.,if the $M_{P1}$ and $S_I$ disconnect,why can the $i_{BAT}^+$ flow from the $L_H$ to the battery?why can $M_{P2}$ and $S_N$ disconnect to let the current flow from the $L_H$ to the battery?It seems that i misunderstand something from the author saying,but i don't know which part do i misunderstand,can anyone correct my mistake?