With the development of new energy vehicles, the Battery Management System (BMS) plays a crucial role in monitoring battery health, controlling charging and discharging, and ensuring safety. In practical applications of BMS, metal push button switches serve as essential human-machine interface components and are widely used in emergency power-off during maintenance, high-low voltage switching, and signal control. This article explores the specific applications of metal push button switches in the BMS of new energy vehicles and analyzes their safety design and technical challenges.

I. Emergency Power-Off Switch in Maintenance Mode

1. The Necessity of Emergency Power-Off

The high-voltage battery system of new energy vehicles may encounter hazards such as short circuits, overloads, or thermal runaway during operation. To ensure the safety of maintenance personnel, vehicles are typically equipped with emergency power-off switches. When the vehicle enters maintenance mode, this switch can quickly cut off the high-voltage power supply to prevent electric shock accidents.

2. Application of Metal Push Button Switches in Emergency Power-Off

Due to their high durability and clear tactile feedback, metal push button switches are widely used in emergency power-off functions and typically feature the following characteristics:

High visibility design: Red or orange color for easy identification by maintenance personnel.

Self-locking mechanism: Maintains power-off status after being pressed to prevent accidental reactivation.

High protection rating (IP67/IP69K): Resistant to harsh maintenance environments such as dust, moisture, or high temperatures.

II. Safety Protection Design for High-Low Voltage Switching

1. Importance of High-Low Voltage System Switching

The battery management system of new energy vehicles involves both high-voltage (e.g., 400V, 800V power batteries) and low-voltage (e.g., 12V, 24V auxiliary systems) circuits. During maintenance, debugging, or fault diagnosis, BMS needs to safely switch between high and low voltage systems to prevent high voltage from being mistakenly connected to low-voltage circuits, which could damage components or cause safety incidents.

2. Safety Design of Metal Push Button Switches

To ensure the safety of high-low voltage switching, metal push button switches must meet the following requirements:

Mechanical anti-misoperation mechanism: Uses a rotary press combination switch that requires turning before pressing to switch, preventing accidental high-voltage connection to low-voltage systems.

Dual confirmation mechanism: Integrated with the CAN or LIN bus to ensure the ECU detects the appropriate switching conditions before executing the command.

High-voltage and impact-resistant materials: The button housing is made of aluminum alloy or stainless steel to enhance electromagnetic shielding and mechanical strength.

III. Impact of EMC Electromagnetic Interference on Switch Signal Stability

1. EMC Challenges in BMS Systems

When the BMS of a new energy vehicle operates, high-voltage wiring, inverters, and DC/AC converters generate strong electromagnetic interference (EMI). This interference can lead to instability in the signals of metal push button switches, such as:

Signal jitter: Interference causes unintended triggering or signal failure.

Communication interruption: Affects CAN, LIN communication buses, leading to delayed or lost switch feedback signals.

Erroneous switch activation: High-frequency electromagnetic waves may cause relays to misoperate, resulting in control logic confusion.

2. EMC Mitigation Strategies

To ensure the stability of metal push button switches in high-electromagnetic environments, the following measures are adopted:

Shielding materials: Aluminum alloy or nickel-plated stainless steel housing effectively blocks electromagnetic interference.

Filtering circuits: RC filter circuits added to switch signal ports reduce the impact of high-frequency noise.

Optocoupler isolation: Optical couplers isolate high and low voltage signals, preventing common-mode interference from affecting switch signals.

Differential signal transmission: Adopts differential transmission in CAN/LIN communication to minimize external electromagnetic interference.

Metal push button switches play a crucial role in the BMS of new energy vehicles, particularly in emergency power-off, high-low voltage switching, and electromagnetic interference resistance, providing reliable safety protection. As new energy vehicle technology advances, metal push button switches will continue to evolve toward intelligent and high-reliability solutions, such as integrated touch sensing and wireless communication, further enhancing vehicle safety and user experience.

In the future, as autonomous driving and intelligent battery management technologies develop, the role of metal push button switches may also transform from traditional mechanical pressing to intelligent electronic control, bringing safer and more efficient solutions to the new energy vehicle industry.