The high-voltage power tool harness mainly provides high-voltage and strong power supply for new energy vehicles, so the design and layout of the harness is particularly important, mainly following the following principles:

1) Direction design of electric tool harness: double-track system is adopted for high-voltage harness design. As the high pressure has exceeded the safe voltage of the human body, the human body cannot be used as an iron spot for vehicles. Therefore, when designing the high-voltage wiring harness in the package, the DC high-voltage circuit must strictly implement the dual-track system, and the high-voltage wiring harness in the package can be divided into positive and negative poles.
2) Selection of high-voltage connector for power tool harness: High-voltage connector is mainly responsible for the safety of high-voltage circuit, connection and transmission of high-voltage and high-current. Therefore, high-voltage harness connector currently adopts the functions of high-voltage resistance, loop interlocking, high waterproof level and shielding layer connection.
3) Electric tool harness shielding design: shield the high-voltage line, wrap the shielding net inside the high-voltage line, and connect the connectors to realize the connection of shielding layers. Considering the electromagnetic interference, the whole high-voltage wiring harness system is completely covered by the shielding layer.
4) High-voltage cable layout: considering safety and electromagnetic interference, the high-voltage wiring harness and the low-voltage wiring harness are arranged separately.

Design scheme of low-voltage harness for battery pack
According to the working principle and design structure of the battery, the internal power tool harness is divided into:

1)BMU(BMS single board) power tool harness: mainly responsible for actuator control, thermal management strategy, battery state estimation (SOC, SOP, SOH, etc.), fault diagnosis, high-voltage safety, and other BMS main control functions;
2)LMU(BMS standby board) wiring harness: its main function is to collect and monitor the voltage and battery temperature of a single unit;
3)HCU(BMS High Voltage Board) information acquisition power tool harness: insulation monitoring and high voltage acquisition;
4) High-voltage relay coil control harness: responsible for controlling the on-off of high-voltage circuit;
5) Electric tool harness of current sensor: mainly responsible for collecting current information, Hall sensor or shunt;
6)PTC controller: controlling PTC heating;
7) Solenoid valve: controlling the on-off of the battery pack air conditioning pipeline;
8) Interlocking plug of each high-voltage connector: high-voltage circuit interlocking signal transmission.

The above wiring harness is arranged separately from the high-voltage wiring harness in the battery pack, which can effectively avoid EMC interference. Low-voltage harness fixing and buckle selection of battery pack: due to the limitation of battery pack environment and structure, the harness fixing mainly adopts the way of miniaturization, easy assembly and simple fixing structure.

Shielding design of electric tool harness;
The low-voltage power tool harness is responsible for the function realization of the high-voltage control unit module and the transmission of related signals. In the design and layout of low-voltage wiring harness, the interference protection of high-voltage electric tool wiring harness is considered. Different signal sources use different low-voltage shielded wires.

High frequency signal: the power tool harness is twisted pair, and the shielding layer is shielded by foil;
Low-frequency signal: Twisted-pair bundle, braided shield layer.
Shielding grounding form:
Single point grounding: low frequency signal single point grounding;
Multi-point grounding: Multi-point grounding is adopted for high-frequency signals.
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