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Servo Feedback Devices and Motor Sensors
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
Resolvers are well suited to harsh environments such as high temperature, high humidity, vibration, and shock load. Because resolvers are analog devices, their high voltage range makes them less susceptible to noise. However, as a type of magnetic field-based sensor, when they are used in applications of electromagnetic actuator control, the sensors can be affected by the magnetic field generated by the actuator. Hence, resolvers require magnetic shields in order to work correctly [8.22]. Furthermore, since some resolvers are little slow to respond to dynamic changes, one must be careful when using them to close a high-speed positioning control loop.
Sensors and Transducers
Published in Felix Alberto Farret, Marcelo Godoy Simões, Danilo Iglesias Brandão, Electronic Instrumentation for Distributed Generation and Power Processes, 2017
Felix Alberto Farret, Marcelo Godoy Simões, Danilo Iglesias Brandão
Resolvers are a rotary type of sensors that act as a synchronous AC servomotor or generator with two delayed fields. Brushless resolvers (brushless DC motor, BLDC) are economical and very accurate [12–14].
High-accuracy resolver-to-linear signal converter
Published in International Journal of Electronics, 2018
W. Petchmaneelumka, P. Mano, K. Songsuwankit, V. Riewruja
A resolver is a type of inductive transducer that is useful for measurements of angular displacement, position and speed. The resolver is known for high reliability and can be operated in harsh environments. Many applications of the resolver can be found in robots, military equipment, medical equipment, electric vehicles, aerospace industry and radar (Attaianese & Tomasso 2007; Wang, Zhu, & Zuo, 2015). The structure of a resolver comprises two secondary windings configured at right angles from each other as the stator and the primary winding as the rotor. The primary winding is forced by the excitation signal in sinusoidal form. Two output signals of the resolver from the secondary windings are the amplitude modulation with suppressed carrier (AMSC), where the amplitudes are proportional to the sine and cosine function of the shaft angle of the rotor. Traditionally, the output signals of the resolver are demodulated by the synchronous demodulators based on an analogue multiplier and a low-pass filter to extract the shaft-angle signals in sine and cosine terms. The disadvantage of this technique is that the reference signal for the synchronous demodulator is usually provided from the excitation signal. Practically, the phase shift between the output signal of the resolver and the excitation signal is caused by the transfer characteristic of the resolver itself. In addition, the dominant pole caused by the low-pass filter in the synchronous demodulator produces a phase shift in the demodulated signal or shaft-angle signal. These phase shifts contribute to error in the shaft-angle signal. There are several techniques to convert the shaft-angle signal to a linear signal (Al-Emadi, Ben-Brahim, & Benammar, 2014; Attaianese & Tomasso, 2007; Benammar, Ben-Brahim, & Alhamadi, 2004, 2005; Ben-Brahim, Benammar, Alhamadi, Al-Emadi, & Al-Hitmi, 2008; Ben-Brahim, Benammar, & Alhamadi, 2009; Hwang, Kim, Kim, Liu, & Li, 2011; Sarma, Agrawal, & Udupa, 2008; Wang et al., 2015). Previously, the quotient of two quadratic signals, sine and cosine, was provided for the inverse tangent to determine the shaft angle (Han, Zhang, He, & Shang, 2009; Mienkina, Pekarek, & Dobes, 2005; Staebler, 2000). The closed-loop approaches based on the angular tracking observer (ATO) receive the most attention for use in commercial devices (Szymczak, O’Meara, Gealon, & De La Rama, 2014). However, both the inverse tangent technique and the ATO require a high-speed digital signal processing (DSP) system, resulting in increased complexity and large configuration. Alternately, the pseudo-linear segment and phase-locked loop (PLL) techniques were reported in Benammar et al. (2004), Benammar et al. (2005), Benammar, Khattab, Saleh, Bensaali, and Touati (2017), Benammar and Gonzales (2016a, 2016b), Lukić, Živanović, and Denić (2015), Wang et al. (2015) and Yim, Ha, and Ko (1992). The use of the PLL technique provides a loop filter that deteriorates the response time and stability of converter. Note that the aforementioned approaches require two resolver signals with equal amplitude. Practically, the two output signals of the resolver exhibit the amplitude imbalance due to the non-ideal structure of the resolver. Therefore, an error is found for the determination of the shaft angle.