Shinji Shinnaka

A New Speed-Varying Ellipse Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors With Pole Saliency—New PLL Method Using High-Frequency Current Component Multiplied Signal

This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. With regard to phase estimation, the sensorless vector control method is featured by a new high-frequency voltage injection method (i.e., carrier modulation method), which is distinguished from the conventional ones by a unique ellipse shape of spatially rotating high-frequency voltage, and by a new phase-locked-loop method as a demodulation method whose input is a high-frequency current component multiplied signal. The new vector control method established by two innovative technologies for modulation/demodulation can have the following high-performance and attractive characteristics. 1) It can allow 250% rated torque at standstill. 2) It can operate from zero to the rated speed under the rated motoring or regenerating load. 3) It accepts instant injection of the rated load even for zero-speed control. 4) Phase estimation is robust against inverter dead time, and proper phase estimate can be obtained even under circumstances where stator current crosses the zero at high frequency. 5) Computational load for estimating rotor phase is very small. Usefulness of the proposed new vector control method is verified through extensive experiments.

New sensorless vector control using minimum-order flux state observer in a stationary reference frame for permanent-magnet synchronous motors

This paper proposes a new sensorless vector control method that can be applied to both of salient-pole and nonsalient-pole permanent-magnet synchronous motors (PMSMs). The proposed method estimates the phase of a rotor flux by a newly developed state observer in a stationary reference frame for sensorless vector controls of PMSMs. The flux state observer has the following attractive features: 1) it requires no steady-state conditions for the dynamic mathematical model of the motor; 2) its order is the minimum second; 3) a single observer gain is simply constant over a wide operating range and can be easily designed; 4) it utilizes motor parameters in a very simple manner; and 5) its structure is very simple and can be realized at a very low computational load. The proposed speed-estimation method, which exploits the inherent physical relation of integration/derivation between phase and speed, is very simple and can properly estimate rotor speed. The usefulness of the proposed method is examined and confirmed through extensive experiments.

New Optimal Current Control Methods for Energy-Efficient and Wide Speed-Range Operation of Hybrid-Field Synchronous Motor

This paper proposes new practical optimal current control methods for a newly emerging class of synchronous motors with hybrid rotor fields by both permanent magnet and winding. In a practical situation with limited voltage, the extensively used permanent-magnet synchronous motor hardly achieves an ideal performance in an energy-efficient manner due to its constant magnet field, which simultaneously allows both low-speed high-torque and wide speed-range operations. The hybrid-field synchronous motors (HFSMs) are potential candidates that can achieve the ideal performance as practical motors with controllable hybrid rotor field. HFSMs can dynamically control the rotor flux according to the operation requirements by the low-speed, high-torque, and wide speed-range operations, etc. For the HFSMs, the same torque can be produced by a variety of stator and rotor currents due to the nonlinearity between the torque and the currents. Produced losses and required voltages depend upon the associated currents. Consequently, in the situation that current control systems are well constructed, appropriate determination of a set of stator and rotor current commands plays a key role to achieve the ideal performance in an energy-efficient manner. The proposed methods determine the current commands corresponding to a given torque command such that the total winding copper losses due to the stator and rotor currents can be minimized if the exact currents associated with the torque command exist; the best approximate torque can be produced if no exact associated currents exist, which is, of course, under the circumstance of a voltage limitation. The determined current commands are optimal in the sense of energy efficiency or degree of approximation under voltage limitation. New recursive algorithms searching the optimal current solution in real-time are also given as parts of the methods. The proposed methods are analytical but practical, whose usefulness is verified through experiments.

A Novel Fast-Tracking D-Estimation Method for Single-Phase Signals

The phase, frequency, and amplitude of single-phase voltages are the most important and basic information required for single-phase microgrid connected applications. This paper proposes a new “D-estimation method” for instantly estimating the phase, frequency, and amplitude of frequency-varying single-phase signals in such applications. The D-estimation method has the following attractive features: 1) it is a new filtering method using the D-filters; 2) it involves the use of only filters and can be easily designed; 3) it is inherently stable and robust in hostile envelopments caused by a frequency variation, a phase jump, amplitude sag/swell, harmonic distortion, and/or contaminated noise; 4) even in the hostile envelopments, good instant estimates of the phase, frequency, and amplitude can be obtained; 5) it is simple, but can exhibit fast-tracking performance comparable to the “robust PLL method.” This paper presents the D-estimation method together with the design rules in detail; the usefulness of the method is verified by performing extensive numerical experiments.

A New Speed-Varying Ellipse Voltage Injection Method for Sensorless Drive of Permanent-Magnet Synchronous Motors with Pole Saliency: -- New PLL Method Using High Frequency Current Auto-Correlated Signal --

This paper proposes a new sensorless vector control method for salient-pole permanent-magnet synchronous motors. With regard to phase estimation, the sensorless vector control method is featured by a new high frequency voltage injection method distinguished from the conventional ones by a unique ellipse shape of the spatially rotating high frequency voltage, and by a new PLL method whose input is a high frequency current auto-correlated signal. The new vector control method established by two innovative technologies can have the following high-performance and attractive characteristics: 1) it can allow 250% rated torque at standstill; 2) it can operate from zero to the rated speed under the rated motoring or regenerating load; 3) it accepts instant injection of the rated load even for zero-speed control; 4) it accommodates a load with huge moment of inertia; 5) phase estimation is robust against inverter dead time; 6) computational load for estimating rotor phase is very small. Usefulness of the proposed new vector control method is verified through extensive experiments.

Frequency-hybrid vector control for sensorless induction motor and its application to electric vehicle drive

As one of most useful sensorless vector control schemes for an induction motor drive, the frequency-hybrid (FH) vector control scheme has been proposed by one of the authors, which has the following high performance attributes: (1) it can make machines to produce more than 200% rated torque at standstill; (2) in both motoring and regenerating modes, rated torque can be produced even in very slow speed range including zero-speed and zero-frequency; (3) it accepts inertia larger than 200 times of rotor; (4) it has high tracking ability to variable speed command; (5) it can accept zero-speed command and settles the machines at a stable standstill with no vibration; and (6) it accepts instant injection of rated load even for zero-speed control. Most of the above performance is required for realization of a sensorless electric vehicle (EV). This paper presents design, realization and field test results of a radical new sensorless EV based on the EH vector control scheme, and clarifies its usefulness.

New optimal current control methods for energy-efficient and wide speed-range operation of hybrid-field synchronous motor

This paper proposes new practical optimal current control methods for a newly emerging class of synchronous motors with hybrid rotor fields by both permanent-magnet and winding. In practical situation with limited voltage, the extensively used permanent-magnet synchronous motor hardly achieves an ideal performance that allows simultaneously both low-speed high-torque and wide speed-range operations, due to its constant magnet field. The hybrid field synchronous motors (HFSM) can achieve the ideal performance as practical motors with controllable hybrid rotor field. For HFSM, the same torque can be produced by a variety of currents due to nonlinearity between torque and currents. Consequently, appropriate determination of a set of stator and rotor current commands plays a key role to achieve possible energy-efficient and wide speed-range operation. Proposed methods determine the current commands corresponding to a given torque command such that total winding copper loss due to stator and rotor currents can be minimized if the exact solution exists, the best approximate torque can be produced if no exact solution exists. The determined current commands are the optimal in sense of energy-efficiency or degree of approximation in wide speed-range operation under voltage limitation. New real-time recursive algorithms searching the optimal current solution are also given. The proposed methods are analytical but practical, whose usefulness is verified through experiments

Elliptical Trajectory-Oriented Vector Control for Energy-Efficient/Wide-Speed-Range Drives of Sensorless PMSM

This paper proposes a new sensorless vector control method for energy-efficient and wide-speed-range drives of permanent-magnet synchronous motors. The proposed sensorless method has the following features: 1) wide-speed-range drive under voltage limit; 2) current limitation; and 3) high efficiency. These features are realized in a very simple manner and can operate adaptively in all sensorless driving modes, including motoring/regenerating and steady/transient states. The usefulness of the proposed method is verified by extensive experiments.

New Dynamic Mathematical Model and New Dynamic Vector Simulators of Hybrid-Field Synchronous Motor

This paper proposes a new dynamic mathematical model and new dynamic vector simulators for a newly emerging class of hybrid-field synchronous motors (HFSMs) that has rotor fields by both permanent magnet and winding. The proposed new mathematical model has the following completeness and generality: 1) it consists of three consistent basic equations such as circuit, torque evolution, and energy-transmission equations; 2) it deals with pole saliency and contains nonsaliency as a special case; 3) it is a dynamic model and contains static one as a special case; and 4) it is established in the general reference frame including the stator and rotor reference frames as special cases. The proposed new dynamic vector simulators are established in form of vector block diagram based on the new model. They have the following attractive features: 1) they succeed in realizing clear configurations with physically meaningful vector signals, which clearly show motor electromagnetic mechanism; 2) vector signals utilized as transfer signals between blocks are defined in the general reference frame; consequently, the simulators in the frame can be directly and easily reduced to the ones in the stator and rotor reference frames; and 3) they are compact. Two typical and compact but sufficiently general dynamic vector simulators are newly presented

A new norm-based current control method for energy-efficient/wide-speed-range drive of salient-pole permanent-magnet synchronous motors

This paper proposes a new current control method for energy-efficient and/or wide speed-range drive of salient-pole permanent magnet synchronous motors. The proposed method is distinguished from conventional ones by the following features: 1) the original command is a signed current-norm; 2) the exact d-axis and q-axis current commands that perform energy-efficient and/or wide-speed-range drive are analytically and simply determined from the singed current norm command; 3) for speed control mode, the system turns out to be nonlinear, but its stability can be guaranteed based on Popovs stability theorem; 4) it can be applied for a mode similar to torque control; 5) current limit operation can be carried out accurately but very simply. Concrete analytical d-axis and q-axis current commands are presented, which satisfy exactly optimum current control strategies such as maximum torque/current strategy, maximum power factor strategy, and voltage limit strategy. A design method for PI speed controller that guarantees system stability is also presented.