1. Product Overview
Eight core components integrated in the 8‑in‑one assembly and their functions:
| No. |
Component |
Function Description |
| ① |
Drive Motor (Motor) |
Permanent‑magnet synchronous motor with hairpin flat‑wire winding |
| ② |
Motor Control Unit (MCU) |
IGBT/SiC‑based power inverter for motor drive |
| ③ |
Reducer |
Single‑stage parallel‑axis reduction gear and differential gear set |
| ④ |
On‑Board Charger (OBC) |
AC‑to‑DC power conversion; rated power: 6.6 kW / 11 kW |
| ⑤ |
DC‑DC Converter |
High‑voltage to 12 V / 48 V low‑voltage power conversion |
| ⑥ |
Power Distribution Unit (PDU) |
High‑voltage relays, fuses and pre‑charging circuit |
| ⑦ |
Battery Management System (BMS) |
Battery signal sampling, cell balancing and safety protection |
| ⑧ |
Vehicle Control Unit (VCU) |
Vehicle‑level logic control and torque distribution |
2. Detailed Technical Specifications
Quick‑reference parameters for the reducer, MCU, OBC and DC‑DC converter
Reducer
- Reduction configuration: Single‑stage parallel‑axis helical gear
- Reduction ratio: approx. 11.5:1
- Differential: Open‑type bevel‑gear differential
- Lubrication: Combined splash and forced‑feed oil lubrication
- Gear material: 20CrMnTi carburized and quenched steel
- Bearing arrangement: Combined deep‑groove ball bearings and tapered roller bearings
- NVH indicator: Noise＜75 dB(A)
Motor Control Unit (MCU)
- Power module: IGBT5 (SiC upgrade available for premium configurations)
- Switching frequency: 8–10 kHz
- Peak rated current: approx. 600 A rms
- DC‑Link capacitor: BYD self‑developed film capacitor (≈800 μF)
- Control algorithms: Maximum Torque Per Ampere (MTPA), field‑weakening control and Field‑Oriented Control (FOC) vector control
OBC & DC‑DC Converter
- On‑Board Charger (OBC)
- Input: 220 V / 380 V AC; Output high‑voltage range: 200–750 V
- Standard 6.6 kW power rating, 11 kW as optional upgrade
- Peak efficiency＞94%
- Topology: Interleaved LLC resonant converter
- DC‑DC Converter
- Input high‑voltage range: 250–750 V; Output: 12 V low‑voltage
- Rated power: 2.2 kW
- Peak efficiency＞93%
- Topology: Buck plus isolated‑boost circuit
3. Physical Structure and Layout
3.1 Housing Structural Features
- Housing material: ADC12 die‑cast aluminium alloy
- Chamber layout: Three‑cavity partition (motor chamber, gear chamber and electronic‑control chamber)
- Oil passage: Oil galleries integrally cast into the housing
- Weight‑optimised design: Wall thickness controlled between 2.5 mm and 4 mm with rationally‑distributed reinforcing ribs
- EMC shielding: Fully‑sealed metallic shielding for the MCU cavity fitted with conductive rubber gaskets
3.2 Thermal‑Management Architecture
Oil‑cooling circulation route
Mechanical / electric oil pump → Oil filter → Water‑cooled oil cooler
├─ Stator end‑section oil spray via 8 oil nozzles of the drive motor
├─ Rotor centrifugal oil flinging toward the stator
├─ Temperature‑equalised baseplate oil passages for MCU IGBT modules
├─ Oil‑cooled cold plate for the OBC and DC‑DC converter
└─ Oil return to the oil sump for repeated circulation
Key oil‑cooling parameters
- Dual‑pump configuration combining mechanical and electronic oil pumps
- Lubricant: ATF transmission fluid (kinematic viscosity: 4‑6 cSt at 100 °C)
- Total oil capacity: 1.8–2.2 L
- Rated heat‑dissipation capacity: 8–12 kW
