Noriya Nakao

Suppressing pulsating torques: Torque ripple control for synchronous motors

This article proposes a novel control technique for suppressing pulsating torques in permanent magnet synchronous motors (PMSMs) and synchronous reluctance motors (Syn-RMs). This torque-control system is based on instantaneous torque estimation with a rigorous analytical model that can account for spatial harmonics. Using this novel analytical model, the produced torque can be accurately estimated from simple preknowledge and some measurable online information. Ultimately, superimposed currents obtained from the torque estimation can smooth out the pulsating torque. The effectiveness of the proposed technique is evaluated by performing both simulations and experiments.

Torque ripple control for synchronous motors using instantaneous torque estimation

This paper presents a new control technique for minimizing torque ripple in permanent magnet synchronous motors (PMSMs) and synchronous reluctance motors (Syn.RMs). This control technique is based on instantaneous torque estimation with a new mathematical model. The model can accurately take into account the spatial harmonics and it requires some machine parameters and a small amount of offline data. With the new mathematical model, the active control for smooth torque is possible at low cost with existing drive platforms. In this paper, the proposed control technique is evaluated by performing both simulations and experiments.

Vector control specialized for switched reluctance motor drives

A vector controlled-switched reluctance motor (SRM) drive system is proposed in this paper. As the unipolar excitation current, the sinusoidal current with a DC offset is applied to each circuit in the proposed technique. The excitation current consists of the DC and AC components. These components generate the (virtual) rotor flux and rotating stator field, hence, the vector control system for the SRM drive can be developed in the same way as conventional AC machines. The proposed technique provides the precise instantaneous torque control, linear torque-current control, and maximum torque per ampere (MTPA) control methods. The SRM drive can be easily controlled by a single parameter under the MTPA condition. The proposed vector control is verified by performing some experimental tests on a three-phase SRM.

Investigation of Locked Rotor Test for Estimation of Magnet PWM Carrier Eddy Current Loss in Synchronous Machines

The measurement method on the basis of locked rotor tests has been developed for the estimation of magnet PWM carrier eddy current loss in synchronous machines. In the measurement, the magnet eddy current loss is separated from the other losses by subtracting the loss of the machine without the magnets from that with the magnets under the appropriate control of armature currents and voltages. The 3-D finite element analysis is also carried out in order to confirm the validity of the proposed measurement method. The measured and calculated results are found to be in good agreement. It is clarified that the magnet eddy current loss of the machine can be predicted from the results of the proposed measurement method.

A New Control Method for Torque Ripple Compensation of Permanent Magnet Motors

This paper presents a new control method for a torque ripple compensation of permanent magnet synchronous motors (PMSMs). The control method is based on a new equation to estimate the instantaneous torque. The equation can accurately take into account variations of both a magnetic energy and a magnetic co-energy. To achieve a stable and an effective torque ripple reduction, a feedforward control and a feedback control are applied to the proposal system. In this paper, the simulation results show that the instantaneous torque estimation result is more accurate than the conventional method. In addition, the effectiveness of the control method is verified by both the simulation and the experiment.

Torque ripple compensation based on instantaneous torque estimation in permanent magnet synchronous motors

This study presents a new torque ripple compensation for permanent magnet synchronous motors (PMSMs). The proposed method is based on instantaneous torque estimation by a mathematical model. The model is described in a new expression to estimate the torque with low volume offline data. The offline data is constructed by only a magnetic flux and a cogging torque. Therefore, the new model makes the torque ripple compensation possible at low cost within existing drive platforms. In this paper, the proposed method is evaluated by both simulations and experiments. These results show the proposed method has excellent performances.

A single phase SRM driven by commercial AC power supply

This paper presents a novel single phase switched reluctance motor (SRM) which can be directly driven by commercial AC power supply without any switching circuit and sensor. This proposed SRM is optimized based on a simple design technique. The optimized machine has aimed to be higher motor efficiency than conventional induction motors (IMs). In addition, the novel SRM can achieve the start-up with directly connecting commercial AC power supply. In this paper, the performance of the prototype single phase SRM is verified by performing simulations and experiments.

Torque/current ratio improvement and vibration reduction of switched reluctance motors using multi-stage structure

This paper presents a multi-stage Switched Reluctance (SR) motor. In this proposed machine, the numbers of stator and rotor poles are equal in each stage. Because of the structure the proposed SR motor can achieve high torque/current ratio in operation. Also, the low-vibration operation is possible by shifting the excitation firing angle. Effectiveness of the proposed SR motor is verified by performing some simulations and experiments.

Motor control methods with a behavior model based on FEA results

In this paper, some motor control methods by using a behavior model which is created by the FEA results are proposed. A real time simulator with the behavior model is worked with the real time motor control, especially the torque ripple control and the current sensorless control are performed and verified by the experiments.

Torque control of a switched reluctance motor by using torque estimation and excitation angle control

This paper presents a novel torque control technique of a switched reluctance (SR) motor. This control scheme is a combination of proposed techniques including torque estimation and excitation angle control. Due to the proposed torque control, a unipolar excitation of the SR motor is automatically optimized, and not only smooth torque production but also the highest possible efficiency drive can be achieved without preliminary tuning. In addition, it is easy to implement the control algorithm on a drive platform which has a limited memory capacity because it requires storing simple pre-knowledge and detecting measurable online information. The effectiveness of the proposed techniques are evaluated by performing simulations and experiments on a 1kW 8/12 SR motor in this paper.