High Frequency Voltage Injection Research Articles

Research on PMSM Low-speed Sensorless Control Strategy based on Rotating High Frequency Injection Method

In this paper, by studying the Permanent Magnet Synchronous Motor (PMSM) position sensorless control strategy, a method for error compensation of current responsed by high frequency error signal is proposed. Since the high-frequency carrier current contained in the stator current causes the erroneous adjustment of the current regulator, the control system contains a high-frequency error signal, which affects the motor rotor position and speed estimation accuracy. The high-frequency error voltage signal is extracted in the stationaryα − β coordinate system, and the high-frequency error response current in the stator current is estimated, and the estimation system is compensated. The PMSM position sensorless control system based on the rotating high frequency voltage injection method and the Matlab-Simulink system model of the error compensation are established. The results show that the speed and position estimation are more accurate after error compensation, and the steady-state error is smaller, which improves the smoothness of the motor at low speed.

Initial Rotor Position Detection Method of SPMSM Based on New High Frequency Voltage Injection Method

A novel initial position detecting strategy of sensorless control for the surface-mounted permanent magnet synchronous motor is proposed, the scheme combines the virtual high frequency (HF) voltage pulsating injection method with the carrier frequency component method. In order to improve the sensorless control performance, this method adds the virtual HF rotation frame based on the traditional HF pulsating injection method. At the same time, the carrier frequency component signals are utilized to detect a magnetic pole. The simulation and experimental results show that the proposed method does not require proportion-integration (PI) regulation. The novel magnetic pole judgment method can effectively improve the detecting performance of sensorless control in the long algorithm execution time, complex process, etc. The experimental results verified the correctness of the strategy.

Automatic Tuning for Sensorless Commissioning of Synchronous Reluctance Machines Augmented With High-Frequency Voltage Injection

Sensorless control of synchronous reluctance motors (SyRMs) relies on the knowledge of the machine current-to-flux maps. Previous work demonstrated the feasibility of sensorless identification of the flux maps, performed by exciting the machine with square-wave voltage pulses at standstill, and without the need of rotor locking. The rotor position was initially estimated and then used throughout the identification, in open-loop fashion. In some cases, rotor oscillation and eventually position drift led to stop the identification before the programmed $dq$ current domain was covered entirely. In this paper, the rotor position is closed-loop tracked during the motor commissioning to counteract the occurrence of rotor movement. The hysteresis-controlled excitation voltage is augmented with an high-frequency (HF) square-wave voltage component, and the position is tracked through demodulation of the current response to such HF component. The proposed approach is experimentally verified on a 2.2-kW SyRM prototype. The results show that the $i_d, i_q$ commissioning domain is substantially extended, resulting in more accurate flux maps. Moreover, self-tuning of the method is addressed and possible causes of error are analyzed and commented.

Comparative Evaluation of a Permanent Magnet Machine Saliency-Based Drive with Sine-Wave and Square-Wave Voltage Injection

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection signal can be sine-wave or square-wave alternating current (AC) voltage manipulated by the inverter’s pulse width modulation (PWM). Due to the PWM dead-time effect, these HF voltage injection signals might be distorted, leading to secondary harmonics on the saliency signal. In addition, the flux saturation in machine rotors also results in other saliency harmonics. These nonlinear attributes cause position estimation errors on saliency-based drives. In this paper, two different voltage signals are analyzed to find a suited voltage which is less sensitive to these nonlinear attributes. Considering the inverter dead-time, a sine-wave voltage signal reduces its influence on the saliency signal. By contrast, the flux saturation causes the same amount of error on two injection signals. Analytical equations are developed to investigate position errors caused by the dead-time and flux saturation. An interior PM machine with the saliency ratio of 1.41 is tested for the experimental verification.

Sensorless Torque Control of an Induction Motor through Quadrature Voltage Injection

A previously reported sensorless torque control method for induction motors uses a high-frequency voltage injection signal on the direct axis and a demodulation based on the root-mean-square filter to estimate the rotor flux angle. Further investigations evidence that the quadrature voltage injection has advantages over the direct axis voltage injection due to the high-frequency characteristics of the motor's magnetic circuit. In this paper, the previously proposed method is further developed, using a post-processing low-pass filter to eliminate the need of root-mean-square filters. It is shown that the response of the changes of high-frequency impedances to the injected signal behave like an amplitude modulation, and the design of the post-processing is briefly discussed. Practical experiments comparing the reference and the measured torques are presented.

High-Frequency Voltage Injection Sensorless Control Technique for IPMSMs Fed by a Three-Phase Four-Switch Inverter With a Single Current Sensor

This paper proposes a sensorless control strategy using sine-wave high-frequency (HF) voltage injection for interior permanent magnet synchronous motors (IPMSMs) fed by a three-phase four-switch (TPFS) inverter, with a single current sensor. Three-phase currents are reconstructed by a single current sensor with modification of the inverter topology. The principle of the phase current reconstruction strategy in TPFS inverter is analyzed and the topology of the proposed drive system is illustrated. Then, the normal areas and the dead zones for current reconstruction are investigated in detail, and the vector synthesis method is also explained. Furthermore, the zero vector synthesis strategy and the pulse width modulation (PWM) generation method are also presented, where two current sampling points are applied in each PWM cycle for phase current reconstruction. Finally, an HF voltage injection based sensorless control strategy in the proposed drive system is realized by voltage projection on the proposed k – l axis coordinate system. The reconstructed phase currents track the actual ones accurately, and the estimation error of the rotor position by using the reconstructed phase currents is within ±0.1 rad. The effectiveness of the proposed scheme is verified by simulation and experimental results on a 5-kW IPMSM prototype.

Improved High-Frequency Voltage Injection Based Permanent Magnet Temperature Estimation for PMSM Condition Monitoring for EV Applications

Permanent magnet (PM) temperature is critical to ensure high-performance and reliable control of permanent magnet synchronous machines (PMSMs) for electric vehicle (EV) applications. High-frequency (HF) voltage injection based approach has been shown to be capable of PM temperature estimation under all-speed range with simple implementation. This paper improves existing HF voltage injection based PM temperature estimation approach by considering the cross-coupling effect. The key to PM temperature estimation is the temperature-dependent HF resistance estimated from the injected HF voltage and the current response. It is found that the cross-coupling effect has a great influence on the HF resistance estimation. This paper firstly improves the HF voltage injection model by considering the cross-coupling effect. Then, a comparative numerical investigation is conducted to analyze the estimation errors induced by the cross-coupling effect. A novel HF resistance estimation approach is derived from the proposed improved model and the PM temperature is calculated from the HF resistance with a linear thermal model. The influence of inverter nonlinearity is also analyzed. Experimental investigations demonstrate that the proposed approach is able to improve the performance of PM temperature estimation.

High Frequency Impedance Analysis for Sensorless Starting of Wound Rotor Synchronous Machines

In sensorless control for synchronous machines at low speed and standstill, the position estimation can be sensitive to the choice of the carrier frequency of the injection method. Moreover, electromagnetic saturation or temperature variation in the machine might also affect the estimation error. In order to better describe the high-frequency (HF) behaviour of the machine, the effective HF inductances and resistances are presented in this paper. Then, the analytical expression for the carrier frequency dependent error is explained using the calculated HF-equivalent model and is proposed to be integrated into the sensorless control scheme when a rotating HF voltage injection is employed. Numerical simulations highlight the frequency dependent error and prove the satisfactory operation of the compensation.

On the Proprieties of the Differential Cross-Saturation Inductance in Synchronous Machines

The cross-saturation inductance is a mutual inductance due to the saturation of portions of the magnetic circuit of one axis caused by the current of the other axis. In sensorless drives, the differential cross-saturation inductance causes an error in the estimation of the rotor position when it is performed by means of the high frequency signal injection methods. The knowledge of the properties of cross-saturation inductance is therefore essential to minimize any distortion effect on the position estimation. This paper aims to describe the properties of the cross-saturation inductance for different types of synchronous machine, such as reluctance, interior permanent-magnet, and surface-mounted permanent-magnet machines. Information is also given to predict the error in the estimated position for any stator currents, useful for implementing an error compensation technique or to detect the feasible operating regions using the high frequency voltage injection technique. The analysis is supported by finite element simulations and experimental measurements.

センサレス永久磁石同期モータのための離散時間搬送高周波電圧印加法

This paper presents a new sensorless vector control method for permanent-magnet synchronous motors (PMSMs) that employs discrete-time high-frequency voltage injection. The frequency range of the injected voltage is almost the same as that of the pulse width modulation (PWM) carrier of the voltage command. This allows high-speed phase estimation and a high-performance drive, and possibly low acoustic noise caused by the injected voltage. The high-frequency current corresponding to the injected voltage is analyzed in discrete time. Conventional phase estimation methods that employ continuous-time voltage injection are reconstructed by means of the analyses. The reconstructed methods are characterized by high-speed phase estimation, high-performance drive, and high robustness against motor parameter variation. The usefulness of the proposed method is verified through extensive experiments.

Harmonic Analysis of the Effects of Inverter Nonlinearity on the Offline Inductance Identification of PMSMs Using High Frequency Signal Injection

Offline inductance identification of a permanent magnet synchronous motor (PMSM) is essential for the design of the closed-loop controller and position observer in sensorless vector controlled drives. On the base of the offline inductance identification method combining direct current (DC) offset and high frequency (HF) voltage injection which is fulfilled at standstill, this paper investigates the inverter nonlinearity effects on the inductance identification while considering harmonics in the induced HF current. The negative effects on d-q axis inductance identifications using HF signal injection are analyzed after self-learning of the inverter nonlinearity characteristics. Then, both the voltage error and the harmonic current can be described. In addition, different cases of voltage error distribution with different injection conditions are classified. The effects of inverter nonlinearities on the offline inductance identification using HF injection are validated on a 2.2 kW interior PMSM drive.

A Speed Sensor Fault-Tolerant Control of the CPPM Machine for Electric Vehicle

A speed sensor fault-tolerant control (FTC) strategy for electric vehicle is proposed in electric vehicles using a consequent-pole permanent-magnet (CPPM) machine. In order to obtain good FTC performance at low speed region, a HF voltage injection method is proposed to detect the rotor position from the magnetic saliency. This magnetic saliency of a CPPM machine is analysed by the finite-element analysis (FEA), and the high-frequency (HF) impedances are measured to confirm the saliency. At high speed range, the extended-electromotive force (EMF) method is applied when the failure of the speed sensor is detected. The speed sensor FTC strategy is verified effective by experimental results on a 25kW CPPM machine at different operating conditions. The reliability is enhanced and smooth transition to the fault-tolerant operation is realized. DOI: http://dx.doi.org/10.5755/j01.eee.20.7.5087

Определение углового положения ротора cинхронного двигателя в режиме векторно-импульсного пуска

This article discusses a method for sensorless determining the angular position rotor synchronous motors. It is known that there are difficulties in determining the angular position of the rotor in low speed range. Method using a high-frequency voltage injection, which allows to solve this problem is proposed in this article. The high-voltage signal processing circuit is examined and described in detail. A comparative analysis of the angular position of the rotor of a synchronous motor and the proposed sensorless method using a mechanical encoder is made. The obtained results suggest the possibility of using this method in the various systems of the drive.

Sensorless Control of Permanent Magnet Synchronous Motor Using Voltage Signal Injection

A successful application of vector control is subject to knowing the position of the rotor and, in synchronous machines, the knowledge of the initial position for a problem-free startup. The ability to read rotor position and perform the vector control algorithm without a position sensor is typically referred to as sensorless vector control. Traditional feedback from the rotor position sensor, or the sensor of mechanical angular velocity of the motor, is typically replaced with a computational block or an algorithm that uses the measured voltage and current to indicate the actual position of the motor. The article presents a sensorless control of the permanent magnet synchronous motor using an injection of high frequency voltage for rotor position estimation. DOI: http://dx.doi.org/10.5755/j01.eee.19.6.1583

Surface permanent magnet synchronous machine position estimation at low speed using eddy-current-reflected asymmetric resistance

This paper proposes an alternative position estimation method of surface permanent magnet (SPM) machines at low speed using high frequency (HF) voltage injection. SPM machines traditionally do not have enough spatial saliency signals because of their symmetric rotors. The proposed solution is to track the HF eddy-current-reflected asymmetric resistance for position estimation. It is shown that the spatial variation of resistance can be enhanced when an HF voltage is superimposed. Finite element analysis is performed to investigate the asymmetric resistance in different SPM machines. By superimposing a d-axis pulsating vector HF voltage, SPM machines can achieve the position estimation performance with reduced degradation at high load conditions. Implementation methods are developed to track the resistance-based saliency signal for speed and position closed-loop control. An SPM machine prototype with a ring magnet rotor is used for the experimental evaluation.

Optimized High Frequency Signal Injection Based Permanent Magnet Synchronous Motor Rotor Position Estimation Applied to Washing Machines

Problem statement: This study investigates a novel optimized scheme of a High Frequency Signal Injection (HFSI) based sensor less technique in order to carry out a precise and robust rotor position error estimation of a Permanent Magnet Synchronous Motor (PMSM) drive designed for washing machines. The study was carried out for standstill condition, where precise position information was required for this application. Approach: In order to get rotor position error information, a PMSM high frequency model was considered in the estimated rotor reference frame (d,q). The impact of the HFSI technique parameters choice on the PMSM rotor position estimation performance was studied and experimentally tested, under various injection conditions. Results: The experimental results show that the amplitude of the high frequency current, resulting from injection, was not significant to carry out high performance rotor position estimation. In order to improve rotor position estimation performance and robustness, a modified demodulation of the high frequency current resulting from injection was proposed by using a high pass filter amplifier applied to PMSM measured currents. The novel proposed rotor position error extraction scheme was implemented on a dsPIC30F6010A and was experimentally validated on a 1kW washing salient pole PMSM. Conclusion: This study presents an improved high frequency voltage injection based sensor less control for Permanent Magnet Synchronous Motor (PMSM) designed for washing machines. The optimal parameters choice of the HFSI technique and the use of a high pass filter amplifier have allowed to take the most of the high frequency injected signal for extracting the rotor position error at standstill, compared to a conventional scheme.

Experimental Verification of Positive Correlation Characteristics by Generalized High-frequency Voltage Injection Method

Through experiments, this paper newly validates analytical correlation characteristics between rotor and major-axis phases of high-frequency current trajectory caused by injection of the generalized high-frequency ellipse voltage.

Versatile High-Frequency Current Correlation Method with High-Frequency Integral-Type PLL for Sensorless Drive of PMSMs

This paper proposes a new high-frequency current correlation method with a high-frequency integral-type PLL as a versatile rotor-phase estimation method using stator current caused by high-frequency voltage injection for sensorless drive of salient-pole permanent-magnet synchronous motors. The proposed method has the following advantages. 1) It can be applied for the voltage injection under various conditions. 2) In principle, it can be used for the accurate estimation of rotor phase over a wide speed range. 3) The high-frequency integral-type PLL is extended to higher order for versatility. 4) An analytical method for designing the PLL has been established. 5) It guarantees stable phase estimation. 6) It ensures that the high-frequency noises do not appear in the estimated rotor phase.

A Generalized Heterodyne Method Incorporating a High-Frequency Integral-Type PLL for Sensorless Drives of PMSMs

This paper proposes a new generalized heterodyne method that incorporates a high-frequency integral-type phase-locked loop (PLL) as a versatile rotor-phase estimation method from stator current caused by high-frequency voltage injection for sensorless drive of salient-pole permanent-magnet synchronous motors. The proposed method has the following characteristics that are in direct contrast to those of conventional heterodyne methods. 1) In principle, it can be applied to almost all voltage injection methods. 2) In principle, it can properly estimate the rotor phase over a wide range of speed. 3) It employs a new simple estimation structure based on the high-frequency integral-type PLL method, which does not require any additional filters. 4) An analytical method for designing the components of the structure has been established and no trial and error method is required for selecting the parameters for the components. 5) The stability of the phase-estimation system of the structure is guaranteed. 6) The high-frequency noises generated in the heterodyne process do not appear on the estimated rotor phase.

A self-sensing technology of active magnetic bearings using a phase modulation algorithm based on a high frequency voltage injection method

Conventional AMB(active magnetic bearings) systems consist of electromagnetic coils, position sensors, power amplifiers and a feedback controller. This hardware configuration can lead to a structural complexity, problems of space limitations for the installation, and position control difficulties due to the non-collocation of actuators and sensors. In this paper, a self-sensing mechanism is proposed to resolve such limitations of the general AMB system. The proposed self-sensing scheme uses a phase difference of the injected current of two opposite electromagnetic actuators while an object is levitating between the actuators. The relationship between the phase difference of injected currents and the position of a levitated object was theoretically derived and linearized. In order to realize the proposed self-sensing scheme, a signal processing algorithm was developed. The frequency response of the estimator was measured to verify the performance of the proposed self-sensing scheme. In addition, a magnetic levitation and a disturbance rejection response were experimentally obtained to verify the feasibility of the proposed self-sensing mechanism. Experimental results showed that the developed self-sensing technique has similar performance as a practical gap sensor.