On May 1, 2026, the new national standard for electric vehicles was fully implemented. Besides the well-known revisions to vehicle plastic parts and flame-retardant materials, the controller has undergone even more significant changes. To prevent tampering, the overall hardware design logic of controllers has been revised, and corresponding adjustments are also required for electronic components such as MOSFETs. This article elaborates on the mandatory requirements of the new national standard for electric vehicle controllers and the changes in MOSFET selection criteria.

Three Mandatory Requirements of the New National Standard for Controllers

The new national standard sets three mandatory anti-tampering regulations for controllers.First, controller functions shall not be modified by cutting wires or adding jumper wires. In the past, controllers were usually reserved with debugging ports or learning wires, which could be cut to remove speed limits; this practice is now explicitly prohibited.

Second, controllers shall not be compatible with multiple input voltage modes and must be equipped with an overvoltage lockout function. The previous method of increasing speed by replacing batteries with larger capacity is no longer feasible.

Third, no hidden loopholes shall be reserved in current-limiting devices to prevent refitting via decoders.Combined, these three regulations mandate a full hardware redesign of controllers; software-only modifications cannot pass official compliance inspection.

Updated MOSFET Selection Logic for Controllers

Driven by the new national standard, the selection logic of MOSFETs used in controllers has also changed.Previously, MOSFET selection for electric vehicle controllers prioritized high voltage withstand capability. Taking a 48V system as an example, the fully charged battery voltage may reach 54.6V. When the MOSFET is turned off, the motor coil acts as an inductor and generates voltage spikes. The actual withstand voltage equals the bus voltage plus spike voltage, ranging from approximately 70V to 80V under standard design, and up to 85V–105V with poor design. For this reason, engineers typically adopt 100V or even 120V MOSFETs in 48V systems to avoid spike risks with sufficient voltage margin.

However, this approach brings a side effect: the controller can still operate normally even if illegally replaced with 60V or 70V batteries, leaving room for unauthorized refitting. The new national standard forbids compatibility with multiple input voltage modes. A 100V withstand voltage far exceeds the actual demand of a 48V system and may be deemed to have refitting potential, resulting in failure to pass CCC certification.

Under the new selection logic, MOSFET voltage rating must be precisely specified. With a well-designed controller absorption circuit, 60V–80V devices are recommended for 48V systems.In addition, the overvoltage lockout function is made mandatory by the new standard. In design, TVS diodes can be adopted for fast clamping against transient voltage spikes. Meanwhile, the MCU detects overvoltage signals and turns off MOSFETs to achieve sustained overvoltage protection. The combination of the two effectively eliminates hazards caused by voltage spikes.

Revisions to Drive Circuit Design

Drive circuits also require structural modifications.In old-style controllers, external independent speed limit modules must now be integrated inside the controller and cannot be detached separately. Reserved ports for debugging wires or learning wires are no longer allowed. The speed limiting function must be embedded in the MCU firmware, with no redundant pads or jumper positions reserved on the PCB. Drive signals for MOSFETs in the drive circuit shall be routed through inner PCB layers.

Conclusion

The new national standard for electric vehicles specifies clear requirements covering detailed product design, impacting controllers from software logic down to hardware structure. MOSFET voltage ratings need precise matching; TVS overvoltage lockout is indispensable; and no hidden interface loopholes are allowed in drive circuits. All these revisions require re-selection of electronic components.

Heketai’s medium and low voltage MOSFETs cover a voltage range of 20V to 100V, while its TVS product lineup spans 5V to 440V. A full range of other electronic components is also available. If you are designing circuits for new national standard compliant controllers, you may contact Heketai to obtain product selection guides and realize one-stop component sourcing.