Abstract: This application discloses a protection circuit associated with a battery management system (BMS). The protection circuit includes a first protection module and a freewheeling module. The first protection module is connected in parallel to a first switch module of the BMS, and the freewheeling module is connected in parallel to a load module of the BMS. The first protection module switches to a charging state when the first switch module is turned off to stabilize a voltage between a first terminal of the first switch module and a second terminal of the first switch module. The freewheeling module is turned on when the first switch module is turned off to stabilize a voltage between the first switch module and the second switch module. The protection circuit mitigates risks of breakdown of the first switch module, and prevents a parasitic inductance from limiting a switching frequency of the first switch module.

Abstract: A method for preparing a high molecular weight furan polyamide includes the following steps: 1) charging dimethyl furan dicarboxylate and aliphatic diamine into a reaction container at equal molar weight, and increasing the temperature to 60-120° C. under inert gas; 2) adding a catalyst when the reaction system becomes transparent liquid, increasing the temperature to 140-150° C., and keeping at an atmospheric pressure or a pressure of 41-61 kPa for 0-1 h; and then increasing the temperature to 190-200° C. and reacting for 1-3 h; and 3) depressurizing the system to 3-16 kPa for 0-3 h; and finally, reducing the pressure to 0.003-0.100 KPa for 1-3 h to obtain the high molecular weight furan polyamide.

Abstract: A method for preparing a high molecular weight furan polyamide includes the following steps: 1) charging dimethyl furan dicarboxylate and aliphatic diamine into a reaction container at equal molar weight, and increasing the temperature to 60-120° C. under inert gas; 2) adding a catalyst when the reaction system becomes transparent liquid, increasing the temperature to 140-150° C., and keeping at an atmospheric pressure or a pressure of 41-61 kPa for 0-1 h; and then increasing the temperature to 190-200° C. and reacting for 1-3 h; and 3) depressurizing the system to 3-16 kPa for 0-3 h; and finally, reducing the pressure to 0.003-0.100 KPa for 1-3 h to obtain the high molecular weight furan polyamide.