Glossary · Motion control and drives
Direct torque control (DTC)
Also known as: DTC
German: Direkte Drehmomentregelung
In drive control, direct torque control (DTC) is a control method for AC motors that estimates stator flux and torque from measured currents and voltages and switches the inverter directly to keep both within hysteresis bands, without a separate current loop or modulator.
- Motion control
In one sentence
Direct torque control regulates an AC motor's torque and flux by switching the inverter directly from flux and torque estimates.
Example
A drive for a paper machine winder uses direct torque control for fast torque response when the web tension changes.
How it applies
- Engineering: DTC gives fast torque response and works without an encoder in many applications. It is associated in particular with ABB's drives; other manufacturers use related methods under other names.
- Commissioning: An identification run measures motor parameters for the flux and torque models. Accurate motor data matter for accuracy at low speed.
- Operation: DTC typically produces a variable switching frequency, which can affect noise and filter design.
- Documentation: Use the manufacturer's term for the control mode in parameter descriptions, and explain in plain language what the user selects and when. Don't claim a control mode improves safety; safety functions such as Safe Torque Off (STO) are separate.
Direct torque control vs. field-oriented control
Field-oriented control (FOC) transforms currents into flux and torque components and controls them with PI current loops and pulse-width modulation. DTC controls flux and torque directly with hysteresis comparators and a switching table. Both aim at decoupled torque and flux control.