ISO 21782-5:2021

Overview

ISO 21782-5:2021 defines operating load tests and acceptance criteria for the motor system of electrically propelled road vehicles designed to voltage class B. Part 5 of the ISO 21782 series focuses on the combined motor‑and‑inverter assembly (paired system) and specifies test procedures to evaluate mechanical and electrical durability under repeated high‑stress operating conditions. Key test areas include endurance cycling, surge voltage measurement, and over‑speed assessment, with requirements for instrumentation, test conditions and reporting.

Key Topics

• Scope and test setup
  • Applies to motor systems as voltage class B electric propulsion systems for road vehicles.
  • Tests are performed on the paired motor + inverter with a defined test bench (DC supply, load, torque/speed and power measurement).
• Endurance test
  • Alternating maximum torque and maximum speed modes are cycled to evaluate fatigue of components such as motor shaft key, rotor fixture, stator fixtures, power semiconductor chips and DC bus capacitors.
  • Cycle ranks and counts: S = 2,000,000; A = 1,000,000; B = 500,000; C = 300,000 (start at rank C unless otherwise agreed).
  • Energizing checks after cycles include back‑EMF, position sensor origin, torque‑speed characteristics and vibration.
  • Acceptable limits: back‑EMF within 5%, torque within 5%, position sensor within 5° electrical angle.
  • Optional disassembly criteria check for mechanical wear and electrical parameter drift (e.g., semiconductor resistance and capacitor characteristics within 10%).
• Surge voltage measurement test
  • Verifies that motor input terminal voltage remains below manufacturer’s withstand voltage limits considering temperature, humidity and pressure.
  • Uses storage oscilloscope and monitored case voltage to capture transient surges.
• Over‑speed test
  • Procedures and ranks for verifying safe mechanical and electrical behavior beyond rated speed (annex provides ranking methods).

Applications

• Manufacturers and suppliers use ISO 21782-5:2021 to qualify motor systems and demonstrate durability of propulsion components.
• Test laboratories and OEMs apply the standard for component acceptance, R&D validation, supplier audits and warranty testing.
• Regulatory and homologation bodies can reference the standard when assessing safety and reliability claims for electrically propelled vehicles.
• Practical benefits include reduced field failures, clearer supplier–customer test agreements, and consistent reporting for procurement decisions.

Related Standards

• ISO 21782-1:2019 - General test conditions and definitions for electric propulsion components.
• ISO 21498-1 - Specification of voltage sub‑classes for voltage class B.

Using ISO 21782-5:2021 helps ensure consistent, repeatable operating load testing for motor systems in electric vehicles, improving reliability and enabling clearer supplier–OEM verification.