Battery Management for Hybrid and Electric Vehicles
The production of electric cars and hybrid vehicles is increasing rapidly. Both types of vehicles need high current capability batteries to run the 50 kW or more motors, and these use high voltage systems that demand precise current measurement for safe operation.
Three Sensing Technologies for BMS
Shunt technology is the preferred choice because of its simplicity of use and excellent linearity. Fluxgate technology brings better accuracy, especially on the offset. Open loop Hall effect sensors offer a cost-effective solution for redundant functions.
HSU – Hybrid Supervising Unit for EVs and PHEVs
The Hybrid Supervising Unit (HSU) is a hybrid battery current sensor designed for both DC and AC measurement of battery packs in electric and hybrid vehicles. It features two current measurement channels: one using the shunt effect and the other using the Hall effect, both supporting a primary current measuring range of up to ±2000 A.
HSU Series
- Open Loop transducer using Hall effect channel + Shunt channel
- High insulation level
- Primary current measuring range up to ±2000 A (10 s)
- Unipolar +5 V DC power supply for Hall effect channel
- Operating temperature: −40 °C to +125 °C
- Fully ratio-metric output (sensitivity and offset)
HSU Key Benefits
- Excellent accuracy and very good linearity
- Very low thermal offset drift and sensitivity drift
- Combines shunt + Hall in a single component — first on the market
- Ideal for battery management in EV, Hybrid, and utility vehicles
CAB – Fluxgate BMS Sensors
LEM possesses distinctive expertise in fluxgate technology, recognized as a leading solution for high-performance battery management. The CAB series provides contactless solutions with best-in-class accuracy.
CAB Series
- Fluxgate-based measurement with automotive quality standards
- Best-in-class accuracy: up to 0.5% over full temperature range after endurance tests
- Offset at 50 mA for precise current sensing
- ASIL readiness: ASIL B (CAB-SF 500), ASIL C (CAB-SF 1500)
- Compatible with 800V systems; integrates within BDU or battery pack
- Choice of range: ±500 A or ±1500 A
- Flexible mounting: panel or busbar
- Output signal: high speed CAN (500 kbps)
- Functional safety capability up to ASIL C (ISO 26262-2018 Ed.2)
CAB Typical Applications
- Hybrid and electric vehicle battery pack
- Hybrid and electric vehicle battery disconnect unit
- Conventional lead-acid batteries
- Accurate current measurement for SOC, SOH, SOF
SMU – Single Monitoring Unit
The SMU is LEM’s latest current sensor designed for DC measurement in high-voltage automotive applications (400V, 800V). It provides galvanic isolation between the primary (high voltage) and secondary (electronic) circuits, offering measurement ranges up to ±1500 A using open loop Hall effect technology.
SMU Series
- Open Loop using Hall effect sensor
- High insulation level
- Unipolar +12V DC power supply
- Primary current measuring range up to ±1500 A
- Operating temperature: −40 °C to +125 °C
- Digital output: LIN or UART protocol
SMU Key Benefits
- Accurate State of Charge (SOC) estimation
- High insulation between primary and secondary circuits
- Temperature resilience: -40°C to +125°C
- No insertion losses
- Ideal for battery management, EV/Hybrid/utility vehicles, and battery storage
Technical Specifications Comparison
| Product | Nominal Value | Accuracy | Op. Temperature | Mounting |
|---|---|---|---|---|
| HSU00 / HSU01 | 2000 A | 5% | -40 to 125°C | On primary fastening |
| CAB 1500 | 1500 A | 0.50% | -40 to 85°C | Busbar / Panel |
| CAB 500 | 500 A | 0.50% | -40 to 85°C | Busbar / Panel |
| SMU | 1500 A | — | -40 to 125°C | +12V supply |
