Electric Motor Control with sensorless algorithms: How it works and why it matters

Electric motors are at the core of many modern technologies, from electric vehicles and home appliances to industrial machinery and robotics. For these motors to function efficiently and reliably, they require precise control of speed, torque, and rotor position. Traditionally, this has been achieved using physical sensors. However, recent advancements have made it possible to control motors using sensorless algorithms, which can estimate motor state without relying on physical sensors.

What is electric motor sensor-based control?

Electric motor control systems are responsible for delivering the right voltage and current to the motor at the right time. To do this well, the system must continuously monitor and adjust according to the motor’s speed, torque demand, and rotor position. This information is crucial for optimizing performance, efficiency, and safety.

In conventional motor control systems, this data is collected using hardware sensors. Position sensors like encoders, resolvers, and Hall-effect sensors provide real-time information about the motor's internal state. These sensor-based systems are accurate and reliable, especially in applications that require precise movements or feedback. However, they add cost, increase complexity, and may be vulnerable to damage in challenging environments.

What is electric motor sensorless control?

Sensorless motor control provides an alternative approach. Rather than using physical sensors, it uses advanced mathematical models and algorithms to estimate the motor's position and speed based on measurable electrical quantities such as current and voltage. These estimations are made using techniques like back-EMF (electromotive force) detection, observer models, or flux linkage analysis. The result is a control system that can operate with similar precision in many scenarios, but without relying on hardware sensors.

Sensorless control brings several advantages, especially in cost-sensitive or reliability-critical applications:

• Lower cost: Eliminates the need for physical sensors, reducing the bill of materials.
• Improved reliability: Fewer components mean fewer potential points of failure.
• Simplified wiring and design: With no sensors to connect, the system is easier to assemble and maintain.
• Compact system layout: Especially important in small devices or applications with limited space.
• Better tolerance to harsh environments: Works well where temperature, vibration, or contamination might damage physical sensors.
• Scalable Across Applications: From 2-wheel electric scooters to heavy-duty industrial pumps, sensorless control scales to meet a wide range of use cases.

A smarter path to electrification

As the shift toward electrification accelerates, manufacturers face increasing pressure to innovate while managing cost and complexity. Sensorless motor control provides a smart, software-driven solution – enabling high-performance systems without the high-maintenance baggage of traditional sensors.

And with the rise of AI-enhanced estimators and model-based predictive controls, sensorless algorithms are becoming more precise, more adaptive, and more capable than ever before.

How Ricardo can support you

Our global experience with a wide range of electric motor applications helps OEMs quickly develop and validate both sensor-based and sensorless motor control systems. 

We offer a range of options, including widely adopted industry standards, advanced innovative approaches, and our own patented technologies for sensorless control. And whether the solution is customized for a specific application or provided as an open ‘white box’ platform, we will ensure full transparency at every stage - from defining initial requirements and developing core algorithms to final motor control validation.