The power battery, akin to the heart of new energy vehicles, serves as the energy storage and supply device for electric vehicles. It determines the vehicle’s range, charging efficiency, safety, and other characteristics. Integral to the power battery system are high-voltage components, such as various circuit contactors and fuses, all housed within the battery pack. In this context, Eaton Bussmann provides critical components like DC fuses, high-voltage DC contactors, and smart fuses. Below, we focus on the key parameters to consider when selecting these products.

1. Key Factors for Selecting EV DC Fuses

To ensure fuses function correctly and protect the vehicle’s electrical systems, it is crucial to choose the appropriate type and specifications. The selection of DC fuses for electric vehicles involves several factors: the current and voltage characteristics applied to the fuse, ambient temperature, installation size limitations, and the application circuit. Given fixed external voltage and installation size, fuse selection primarily depends on current characteristics, ambient temperature, and the application circuit.

Rated Voltage (Un): The fuse's rated voltage should not be lower than the system's operating voltage. Electric vehicles and fast charging stations must use DC fuses to ensure safety under all operating conditions. For instance, 500VDC fuses are suitable for small cars and passenger vehicles, while 750VDC to 1000VDC fuses are appropriate for trucks and buses.

Rated Current (In): Calculate the correct rated current based on the system’s maximum continuous load current. The selected fuse's rated current should be slightly higher than the normal operating current of the electric vehicle circuit but must ensure rapid fusing during overload or short-circuit conditions. Typically, small cars and passenger vehicles require around 400A, and trucks and buses need approximately 600A.

Size: Determine the appropriate size and installation method. The physical size of the fuse should fit the installation location in the electric vehicle and allow for easy maintenance and replacement. Automotive fuses are usually mounted on bolts.

Cable Overload Capacity: Determine if additional cable protection is necessary. Auxiliary circuit protection should match cable protection to ensure system safety under overload conditions.

Ambient Temperature: Consider the fuse's operating environment temperature, as it affects the fuse’s performance. Ensure the fuse can operate normally within the vehicle's temperature range.

Application Circuit: Based on the application circuit, the vehicle's circuits can be divided into high-voltage high-current protection areas and medium-low-voltage low-current protection areas. Typically, an electric vehicle uses 4-5 high-voltage fuses for devices like the motor controller, air conditioning circuit, DC/DC, and battery heater. Medium-low voltage fuses are used for central control box circuits, including lighting, audio, and wiper circuits.

Breaking Capacity: The fuse must have sufficient breaking capacity to handle the maximum fault current that may occur in the electric vehicle battery system.

Time-Current Characteristics: Select appropriate time-current characteristics based on the specific needs of the electric vehicle circuit to ensure rapid response during overload and short-circuit situations.

Certifications and Standards: Choose fuses that comply with relevant international and national standards (e.g., ISO, IEC, SAE) to ensure safety and reliability.

Eaton Bussmann offers several common fuse series in the electric vehicle field, such as the EV series Fuse with a voltage rating of 500VDC and a maximum current of 1000A. Additionally, the EVK Fuse and EVKR Fuse both have a voltage rating of 1000VDC. The EVK series Fuse, with a maximum current of 600A, has been widely used due to its excellent performance. The EVKR series Fuse, also rated at 1000VDC, offers a maximum current of 700A, lower power consumption, and better current-carrying capacity, making it an upgraded version of the EVK series Fuse.

2. Key Factors for Selecting High Voltage DC Contactors

High voltage DC contactors are low-voltage control high-voltage switching components, playing roles in circuit conversion and safety protection in new energy vehicles. They are especially crucial in disconnecting circuits to protect people and the vehicle body during system or circuit anomalies. Eaton Bussmann's high voltage DC contactors are mainly used in battery pack main circuits, fast charging circuits, slow charging circuits, boosting, and other auxiliary applications.

Main Circuit Contactors: 

Focus on parameters like conduction capability, impact resistance, breaking capacity, and short-circuit resistance during selection.

Fast and Slow Charging Circuit Contactors: 

Focus on conduction capability, breaking capacity, and short-circuit resistance during selection.

Boosting Contactors: 

Focus on conduction capability and vibration resistance (especially when placed near the motor) during selection.

3. Key Factors for Selecting Pyrofuse

Pyrofuse provide short-circuit and overcurrent protection for power batteries, acting as the last line of defense within the battery pack. Eaton Bussmann's pyrofuses are primarily used in the main circuit and fast charging circuit of battery packs. When the main circuit and fast charging circuit are parallel, both circuits require the protection of pyrofuses.

Eaton Bussmann's Pyrofuse, part of the EBPS Series, is available in two voltage ratings: 500VDC and 1000VDC, both with a rated current of 400A. There are two types: single-trigger Pyrofuse (EBPS65F40 for 500VDC & EBPS100F40 for 1000VDC) and dual-trigger Pyrofuse (EBPS50F40A for 500VDC & EBPS100F40A for 1000VDC). The Pyrofuse can be used not only in electric vehicles but also in energy storage systems and EV Charger.

To enhance the safety of high-voltage circuits in electric vehicles and reduce the difficulty of system design matching, Eaton Bussmann developed an innovative dual-trigger pyrofuse. The Bussmann dual-trigger pyrofuse (Pyro switch) integrates intelligent design principles to automatically trigger during overcurrent events, providing additional reinforced protection and enhancing system reliability. The robust construction of the Bussmann Pyrofuse ensures it can withstand the harshest conditions in electrical systems, with high reliability verified through rigorous testing.

When selecting pyrofuse, focus on the following parameters:

· Product Size

· Conduction Capability

· Passive Cut-off Trigger Current

· Maximum Breaking Capacity

· Maximum Impact Current and Duration

· Action Time

· Resistance After Triggering

By considering these factors comprehensively, you can ensure that the selected components effectively protect the electric vehicle's electrical system, avoiding potential safety hazards.