Antti Piippo

Analysis of an Adaptive Observer for Sensorless Control of Interior Permanent Magnet Synchronous Motors

This paper deals with a speed and position estimation method for the sensorless control of permanent magnet synchronous motors. The method is based on a speed-adaptive observer. The dynamics of the system are analyzed by linearizing both the motor model and the observer, and the observer gain is selected to give improved damping and noise suppression. At low speeds, the observer is augmented with a signal injection technique, providing stable operation down to zero speed. The experimental results, obtained using a 2.2-kW interior magnet motor, are in agreement with the results of the analysis.

Sensorless control of PMSM drives using a combination of voltage model and HF signal injection

This paper presents a method for the rotor speed and position estimation of permanent magnet synchronous motors in a wide speed range including standstill. The proposed method is based on a modified voltage model at high speeds, and combines the modified voltage model with a high-frequency signal injection technique at low speeds. The fast dynamic response of the voltage model is thus augmented with the steady-state accuracy of the high-frequency signal injection technique. The stability and robustness of the combined observer are confirmed by simulations and experiments.

Signal Injection in Sensorless PMSM Drives Equipped With Inverter Output Filter

This paper proposes a hybrid observer for sensorless control of permanent-magnet synchronous motor drives equipped with an inverter output LC filter. An adaptive full-order observer is augmented with a high-frequency signal injection method at low speeds. The only measured quantities are the inverter phase currents and the dc-link voltage. The effects of the LC filter on the signal injection are investigated, and it is shown that the filter is not an obstacle to using signal injection methods. The proposed method allows sensorless operation in a wide speed range down to zero speed. Experimental results are given to confirm the effectiveness of the proposed method.

Adaptive observer combined with HF signal injection for sensorless control of PMSM drives

The paper presents a speed and position estimation method for the sensorless control of permanent magnet synchronous motors. The method is based on a speed-adaptive flux observer that is augmented with a high-frequency signal injection technique at low speeds and standstill. In the adaptive observer, a flux model is used as the reference model and a voltage model as the adaptive model. At low speeds, the estimation is further corrected with an error signal from the signal injection method by influencing the direction of the estimated stator flux. The fast dynamic response of the adaptive observer is thus combined with the steady-state accuracy of the high-frequency signal-injection method. According to simulations and experiments, the proposed approach is stable and robust, and can cope with stepwise changes in the speed or position reference. The capability of rejecting load torque transients is also good

Sensorless Vector Control of PMSM Drives Equipped With Inverter Output Filter

The paper presents a sensorless vector control method for a permanent magnet synchronous motor when the output voltage of the PWM inverter is filtered by an LC filter. The dynamics of the LC filter are taken into account in the design of the controller and adaptive full-order observer. The use of the output filter does not require additional current or voltage measurements. The speed adaptation is based on the estimation error of the inverter output current. Linearization analysis is used to design an observer that enables a wide operation region. Simulation and experimental results show the functionality of the proposed control method

Analysis of an adaptive observer for sensorless control of PMSM drives

The paper deals with a speed and position estimation method for the sensorless control of permanent magnet synchronous motors. The method is based on a speed-adaptive flux observer augmented with a high-frequency signal injection method at low speeds. The dynamics of the adaptive observer are analyzed by linearizing both the motor model and the observer, and the observer gain is selected to give improved damping and noise suppression. The experimental results are in agreement with the results of the analysis.

Adaptation of Motor Parameters in Sensorless PMSM Drives

The paper proposes an on-line method for the estimation of the stator resistance and the permanent magnet flux in sensorless permanent magnet synchronous motor drives. An adaptive observer augmented with a high-frequency signal injection technique is used for sensorless control. The observer contains excess information that is not used for the speed and position estimation. This information is used for the adaptation of the motor parameters. At low speeds, the stator resistance is estimated, whereas at medium and high speeds, the permanent magnet flux is estimated. Steady-state analysis and small-signal analysis are carried out to investigate the parameter estimation, and adaptation mechanisms are defined for the parameters. The convergence of the parameter estimates is shown by simulations and laboratory experiments. The stator resistance adaptation works down to zero speed in sensorless control.

Torque Ripple Reduction in Sensorless PMSM Drives

The paper proposes a method for the compensation of the torque ripple that is caused by motor unidealities in sensorless permanent magnet synchronous motor drives. The sensorless control of the interior-magnet motor is based on a speed-adaptive observer augmented with a pulsating high-frequency signal injection technique at low speeds. The harmonics in the permanent magnet flux and stator inductances are taken into account in the estimation, and a torque ripple compensator is developed for suppressing the harmonics in the estimated electromagnetic torque. The high-bandwidth current control required for torque ripple reduction is based on additional PI controllers implemented in reference frames rotating at the harmonic frequencies. Simulations and laboratory experiments show the effectiveness of the proposed method

Sensorless PMSM Drive with DC-link Current Measurement

The paper proposes a motion-sensorless control method for permanent magnet synchronous motor drives when only the DC-link current is measured instead of the motor phase currents. A two-phase pulse-width modulation method is used, allowing the DC-link current to be sampled twice in a switching period at uniform intervals during active voltage vectors. A method is proposed for obtaining the current feedback for vector control, and an adaptive observer is used for estimating the rotor speed and position. The estimation is augmented with a high- frequency signal injection method at low speeds; a modified high- frequency excitation voltage is proposed for better performance. The proposed method enables stable operation of the permanent magnet synchronous motor drive in a wide speed range and under various loads. The effectiveness of the proposed method is demonstrated both by simulations and laboratory experiments.