Carrier Signal Injection Method Research Articles

IPMSM Sensorless Control by Injecting Bidirectional Rotating HF Carrier Signals

Rotating high frequency (HF) carrier signal injection method is commonly used in interior permanent magnet synchronous machines’ (IPMSMs) sensorless control due to its simple principle. However, the accuracy of the rotor position estimation will decrease because of some adverse impacts, such as system delays, stator resistance, cross coupling effect, and inverter nonlinearities. In order to solve these problems, a strategy to inject bidirectional rotating HF carrier signals into the machine is proposed in this paper. Differing from those conventional methods, the proposed method injects simultaneously two HF carrier voltages with different rotational frequencies and directions. Four independent equations are constructed and obtained by demodulating every frequency components in the response currents. By solving these four equations, the rotor position can be calculated directly, which effectively minimizes the effects of the stator resistance, system delays, and inverter nonlinearities. In addition, the compensation of the cross coupling effect on the rotor position estimation is analyzed and deduced in detail to improve the estimation accuracy. Finally, the experimental results on an IPMSM demonstrate that the rotor position with good steady-state and dynamic performance can be obtained accurately by using the proposed sensorless control strategy.

Analysis of parasitic effects in carrier signal injection methods for sensorless control of PM synchronous machines

This study presents the parasitic effects on different carrier signal injection methods with alternative sensing signals for the sensorless control of permanent magnet synchronous machines (PMSMs). The different carrier injection methods are the rotating injection in the stationary reference frame with carrier current sensing and with zero-sequence carrier voltage sensing, the pulsating injection in the estimated synchronous reference frame with carrier current sensing, and pulsating injection in the anti-rotating reference frame with zero-sequence carrier voltage sensing, respectively. The parasitic effects, e.g. the magnetic saturation, inverter non-linearity, iron and PM losses, torque ripple etc. will be fully analysed and compared for these different injection methods. All the theoretical analyses are validated by either finite-element analyses or experiments on a laboratory PM machine.

PMSM Sensorless Control by Injecting HF Pulsating Carrier Signal Into Estimated Fixed-Frequency Rotating Reference Frame

For permanent-magnet synchronous machines (PMSMs) sensorless control, the widely employed high-frequency (HF) pulsating carrier signal injection method is based on tracking the rotor saliency. It may face the problems of long convergence time, potential start-up failure, and limited system stability. Different from the conventional schemes, the proposed strategy is a direct estimation method. In which, a HF pulsating carrier voltage is injected into the estimated fixed-frequency rotating reference frame other than the estimated synchronous reference frame (SRF). With this approach, spatial saliency tracking observer, which is necessary in the conventional sensorless control, is removed to simplify the control structure and improve the system stability. Furthermore, the rotor position information is directly obtained from the response of injected HF pulsating carrier signal, which can avoid potential convergence failure of tracking observer. In addition, the compensation of system delays existing in the proposed sensorless control strategy is deduced to improve the accuracy of rotor position estimation. For magnetic polarity detection, a new method which has the advantages of high signal-to-noise ratio and low vibration is also investigated. Finally, the experimental results on a PMSM indicate that the rotor position with good steady state and dynamic performance can be obtained accurately with the proposed sensorless control strategy.

Novel Carrier Signal Injection Method Using Zero Sequence Voltage for Sensorless Control of PMSM Drives

In this paper, a novel pulsating carrier signal injection strategy utilizing zero-sequence voltage is proposed for sensorless control of permanent-magnet synchronous machine (PMSM) drives. Different from the conventional zero-sequence carrier voltage sensing method using rotating signal injection in the stationary reference frame, the proposed pulsating injection is based on the estimated reference frame, which rotates anticlockwise at twice estimated rotor electrical angular speed. Then, the rotor position estimation is fulfilled via enabling the zero-sequence carrier voltage to zero. Compared with conventional rotating injection using zero-sequence voltage, the proposed strategy is simpler for signal demodulation and more robust to signal processing delays due to the fact that it is amplitude modulated by machine saliency and phase shifts of saliency position due to signal processing delays are intrinsically cancelled, which is the same as the classical pulsating injection in the estimated synchronous reference frame with carrier current sensing. Therefore, the proposed method can combine the synergies of zero-sequence method (i.e., high bandwidth and stability) and pulsating injection (i.e., increased accuracy and fast dynamic response). Furthermore, the cross-coupling magnetic saturation effects on zero-sequence voltage sensing-based sensorless control are discussed in detail. All the theoretical analyses are validated by experiments on a laboratory surface-mounted PM (SPM) machine.

Novel Sensorless Control Strategy With Injection of High-Frequency Pulsating Carrier Signal Into Stationary Reference Frame

In this paper, a novel sensorless control strategy with the injection of a high-frequency pulsating carrier signal into a stationary reference frame is proposed. Differing from the two most commonly used conventional high-frequency carrier signal injection methods, i.e., the injection of a rotating carrier voltage into a stationary reference frame and the injection of a pulsating carrier voltage into an estimated synchronous reference frame, the new proposed strategy injects a pulsating high-frequency carrier voltage into a stationary reference frame, which is as stable as the rotating carrier signal injection method. Then, the rotor position information can be retrieved from the carrier current response that is amplitude-modulated by the machine saliency, which is as simple as the pulsating carrier signal injection method. The signal demodulation process, the compensation of the cross-saturation effect, and magnetic polarity detection are also discussed and analyzed in detail. The experimental results on an interior permanent-magnet synchronous machine demonstrate that the new proposed strategy has a robust magnetic polarity detection and that it can achieve an accurate rotor position estimation with good steady-state performance and dynamic performance.

Sensorless Control Strategy by Square-Waveform High-Frequency Pulsating Signal Injection Into Stationary Reference Frame

In this paper, a new sensorless control strategy based on the square-waveform high-frequency pulsating voltage signal injection into the stationary reference frame is proposed. Similar to the sinusoidal-waveform injection method, by injecting the high-frequency square-waveform pulsating voltage carrier voltage into the α- (or β-) axis of the stationary reference frame, the response carrier current will fluctuate with the position-dependent saliency, and then the rotor position information can be retrieved without any filtering. Furthermore, with higher frequency, the bandwidth of the position estimation can be significantly improved compared with all the sinusoidal-waveform injection strategies, and the influence of the winding resistance can also be fully eliminated. Meanwhile, the proposed new strategy injects a pulsating high-frequency carrier voltage into the stator stationary reference frame as stable as the rotating carrier signal injection method. Then, the rotor position information can be retrieved from the carrier current response, which is amplitude modulated by the machine saliency as simple as the pulsating carrier signal injection method. The experimental results validate that this strategy can achieve accurate rotor position estimation with good steady-state and dynamic performances by considering the cross-saturation effect even when there exhibits some noise in the estimated rotor position.

Study on Wavelet De-Noising of High Frequency Current Signal for Rotor Position Self-Sensing of PMSM

Self-sensing control of permanent magnet synchronous motor has been a hot research topic of motor control technology, which has the advantages of low cost and high reliability. The use of a high-frequency carrier signal superimposed on the fundamental excitation of PMSM has established itself in recent years as a viable means of eliminating position sensors in ac drives for applications. In the carrier signal injection methods, the rotor position can be estimated by using the carrier signal current resulting from the interaction between the carrier signal voltage and the spatial saliency. The existing sampling error and random noise of high frequency current signal were uncertain to the rotor position self-sensing, that may affect the rotor position self-sensing precision. This paper describes a new wavelet de-noising method of the high-frequency current signal, improving the de-noising results significantly.