An elevator drive is an application-specific Variable Frequency Drive (VFD) used to control motor speed, torque, acceleration and deceleration in a lift system. It uses the same basic power-electronic principles as other AC drives, but elevator service introduces additional requirements such as very-low-speed torque, accurate floor approach, mechanical-brake sequencing, encoder feedback, anti-rollback behaviour and carefully shaped ride profiles.

An important distinction is that the elevator drive is not the complete elevator controller. The lift controller decides where the car should travel, supervises doors and handles system logic. The drive converts the motion command into controlled motor torque and speed.

Some modern integrated lift controllers combine both functions in one product, but the logical functions of lift control and motor drive control remain different.

What makes an elevator drive different from a general-purpose VFD?

A small speed deviation that is unimportant on a fan can be very noticeable in an elevator. The car must accelerate smoothly, approach the landing in a controlled way, avoid rollback when the mechanical brake opens and stop at the landing with good repeatability.

Important elevator-drive functions therefore include low-speed torque control, encoder feedback, mechanical-brake sequencing, S-curve ride shaping, anti-rollback, floor approach and regenerative-energy management.

Which motors are used in elevators?

Traditional traction lifts have widely used geared induction motors. Modern machine-room-less and high-efficiency systems commonly use gearless permanent-magnet synchronous motors (PMSM).

These motor technologies do not use identical commissioning data or control algorithms. An induction-motor drive relies heavily on rated motor data and the induction-machine model, while PMSM control also requires correct rotor-position and magnetic-machine information.

For this reason, elevator-drive selection cannot be based on motor kW alone. The drive must explicitly support the installed motor technology and feedback system.

Why is encoder feedback important?

An encoder reports actual motor speed and, depending on feedback technology, rotor position to the drive. The controller can therefore work with the motor's real mechanical response rather than relying entirely on an estimated response.

This becomes particularly useful at low speed, during brake release and while approaching a landing.

An encoder is nevertheless not a lift safety device by itself. It does not replace the mechanical brake, overspeed governor or the elevator safety circuit.

Encoder resolution also does not determine landing accuracy on its own. Motor control, feedback setup, mechanical backlash, sheave and rope mechanics, the lift controller, shaft-position references and tuning all contribute to final performance.

How does an elevator stop accurately at a landing?

An elevator should not travel at full speed and then suddenly command zero speed at the target floor. The controller and drive reduce speed in advance.

A practical motion profile may contain start → acceleration → rated speed → deceleration → leveling speed → stop.

The motor encoder reports motor motion, while landing or shaft-position systems provide the elevator controller with references related to the actual position of the car in the hoistway. These are related signals, but they are not the same measurement.

Why is S-curve control important for ride comfort?

Passenger comfort depends not only on acceleration time but also on how quickly acceleration itself changes. The rate of change of acceleration is called jerk.

An S-curve smooths the transition into and out of acceleration and deceleration. This can reduce the feeling of a sudden kick at departure or a sharp body movement during stopping.

Excessive S-curve time is not automatically better. It increases travel time and can become impractical on short floor distances.

How does the mechanical brake work with the drive?

The mechanical brake is a critical part of a traction elevator system. It should not simply be treated as a contact that opens whenever the drive receives RUN.

During a typical start sequence, the drive develops the required motor holding torque before the brake is released. Once suitable conditions are established, the brake can open and the car begins controlled movement.

During stopping, motor speed and torque are brought to the appropriate condition, the mechanical brake closes and motor torque is then removed according to the designed sequence.

If the brake opens too early, the car can move in the direction of the unbalanced load. If it opens too late, the motor can produce torque against a closed brake.

Safe Torque Off and a mechanical holding brake do not perform the same job.

What is anti-rollback?

The car and counterweight are not perfectly balanced under every loading condition. When the mechanical brake opens, gravity can create a net torque on the machine.

If the drive has not already developed suitable motor torque, the car can briefly move in the wrong direction. This can be felt as a bump or rollback.

Anti-rollback and related elevator-drive functions attempt to establish the correct torque around brake release. Their effectiveness depends on correct motor data, encoder feedback, brake sequence and the mechanical system.

Why can an elevator need a braking resistor or regenerative drive?

An elevator motor does not always consume power from the mains. Depending on car load, counterweight and direction of travel, the mechanical system can drive the motor and make it operate regeneratively.

That energy flows back toward the drive's DC link. A conventional dynamic-braking system uses a brake chopper and a correctly sized braking resistor to convert the excess energy into heat.

A regenerative drive or active front end can instead return suitable energy to the electrical supply.

Braking-resistor selection must therefore consider the real elevator duty cycle, travel speed, load imbalance, braking duration, repetition rate, DC-link limits and thermal capacity—not motor kW alone.

Does an elevator VFD automatically save energy?

A controlled drive can improve the way energy is used and reduce unnecessary mechanical stress, but elevator energy consumption cannot be reduced to a single VFD percentage.

Car loading, counterweight balance, direction of travel, motor technology, standby consumption, drive losses and whether regenerative energy is dissipated in a resistor or returned to the supply all influence overall efficiency.

Universal claims such as “an elevator VFD always saves X percent” should therefore be avoided.

Elevator-drive educational simulation

The existing OtomasyonAVM simulation below is retained because it usefully illustrates floor approach, speed reduction and encoder feedback. It is an educational model only; it is not a lift safety system, drive-sizing tool or commissioning program.

What should be checked when selecting an elevator drive?

Motor rated current: Continuous drive current must match the real motor requirement.

Motor technology: Induction and PMSM motors require compatible drive-control modes.

Overload capability: Starting, brake-release and low-speed torque can require substantial temporary current reserve.

Feedback type: Incremental, Sin/Cos, absolute or other encoder technology must be compatible with the drive interface.

Rated speed and floor spacing: Short-floor operation can demand a carefully designed motion profile.

Mechanical-brake interface: Brake release, brake feedback and torque-proving functions must fit the complete lift architecture.

Regenerative energy: The project may require a brake resistor, braking unit or regenerative front end.

Safety functions: Any STO or other safety-related drive functions have to be validated as part of the complete lift safety system.

STO, emergency stopping and the mechanical brake are different functions

Safe Torque Off (STO) is a safety-related drive function that prevents the drive power stage from producing motor torque when correctly integrated.

It does not physically hold a gravity-loaded elevator car. The mechanical brake and complete elevator safety architecture remain separate requirements.

An ordinary VFD STOP command is also not equivalent to STO or the elevator's safety circuit.

Elevator safety circuits should never be bypassed or replaced with a normal programmable input simply to make a drive run.

Standards and the drive

The elevator drive is one subsystem within the complete lift. The IEC 61800 family covers adjustable-speed power drive systems, while IEC 61800-5-2 addresses functional-safety aspects of safety-related drive systems.

For the complete elevator, the applicable lift standard and local legislation depend on jurisdiction and project date. In the European framework, EN 81-20 and EN 81-50 are central references. Internationally, ISO 8100-1:2026 is the current ISO safety standard for new passenger and goods-passenger lifts within its scope.

A standard number printed on a VFD does not make the complete elevator compliant. Drive, controller, braking system, doors, mechanical components and safety functions have to be assessed as a system.

For the wider subject, continue to the OtomasyonAVM Industrial Standards knowledge section.

Editor's Note – what I look at first on an elevator drive

I do not approach an elevator inverter like a normal fan or pump drive. My first questions are not about the large kW figure on the label. I want to know the motor type, encoder system, brake sequence and low-speed torque requirement.

Most drives can make a motor rotate at normal speed. The quality of an elevator drive becomes obvious at departure and during the final part of the landing approach.

If the car rolls slightly in the wrong direction when the brake opens, I look at torque establishment, brake timing, encoder direction and motor tuning before randomly changing speed parameters.

If the car hunts around the floor level, simply reducing a “stopping tolerance” parameter may hide the real issue. Encoder feedback, mechanical backlash, brake timing, leveling sensors and the reference coming from the elevator controller all need to agree.

Another rule I keep in mind is that a stopped motor does not automatically mean a secured elevator car. Motor torque, mechanical holding brake and the actual safety chain are separate parts of the design.

And with counterweighted systems, I ask about energy in both directions. In some operating quadrants the mechanical system drives the motor. That means DC-bus and braking-energy management are part of the drive selection from the beginning.

What should you read next?

For feedback and low-speed control, continue with Encoders and the VFD control-method pages. For ride shaping, read S-Curve Control.

For regenerative energy, continue with Braking Resistors. For drive safety functions, continue with Safe Torque Off.

Related OtomasyonAVM sections

For drive products, see AC Drives / VFDs. For braking resistors, filters and surrounding equipment, use VFD Accessories. For feedback hardware, continue into the Sensors and Encoders section. For higher-precision closed-loop motion systems, the Servo Systems section provides useful related background.

External technical reference note

Useful manufacturer and standards references for this subject include the Yaskawa L1000A AC Drive Technical Manual for Elevator Applications, the ABB ACL30 Elevator Drive User's Manual, IEC 61800-5-2, EN 81-20 / EN 81-50 and ISO 8100-1:2026.