Rotary voice coil actuators (RVCAs) are commonly used for precision servo drive systems working within limited angle range in some fields including aerospace. In this paper, expressions of RVCAs' peak torque and peak loss are derived based on a simple magnetic circuit model, and influences of wire diameter and equivalent area on peak torque and peak loss are analyzed. Especially, two unique influences of installing dimension and environment temperature for this type of motor are researched as well. Armature reaction and its restraining for this type of actuator are also studied. Finally, several effective measures of improving RVCAs' torques are summarized, which are of important value in practical engineering applications.INDEX TERMS armature reaction, peak torque, peak loss, rotary voice coil actuator, structure parameters. I. INTRODUCTIONVoice coil actuators (VCAs) are special electrical machines which operate only within a range of stroke lengths or angles. Compared with traditional electrical machines, VCAs have many outstanding advantages, such as small volume, direct driving without gears, high precision and low inertia[1]-[5], and so used for driving light weight and low inertia loads. VCAs can be classified into single magnetic circuit VCAs and dual magnetic circuit VCAs from aspect of magnetic circuit structure; or classified into linear VCAs (LVCAs) and rotary VCAs (RVCAs) from aspect of motion type[6], [7]. In this paper, dual magnetic circuit RVCAs are mainly studied, whose typical applications include scanning mirror drive in space cameras, mirror positioning in laser technique and swing type valve brake, etc [8].Generally, the main performance of a RVCA includes peak torque, peak loss, angular stroke, electrical time constant, torque sensitivity, thermal resistance of coil, etc., among which peak torque of the actuator is most important [9]-[11]. The factors influencing peak torque in this type of motors need to be further studied, because there is a significant difference between the structures of RVCAs and general motors.

Rotary voice coil actuator (RVCA) is mainly used for reciprocating drive of small inertia loads in a limited range of angle, which is widely used in aerospace and other fields. Thermal resistance is one of the most important parameters of RVCAs, which is directly related to the steady‐state temperature rising and operation reliability. Because the thermal resistance cannot be measured directly, the analytical method is usually used to calculate the thermal resistance of the RVCA. However, due to the particularity of the thermal circuit calculation, the calculation is complicated and the result is not accurate. It is not conducive for engineering applications of this kind of actuator. In this paper, a series of rotary voice coil motor is selected as the research object. Through analytical calculation and thermal simulation, a more accurate thermal resistance calculation correction model and thermal resistance value of RVCAs are obtained, and the accuracy of the estimation results is verified by experiments. On this basis, the effective volume of the coil frame of the RVCA is selected as the variable, and the concise variation law of the series thermal resistance data is obtained. This paper provides a fast and accurate estimation method for the thermal resistance of RVCA, which has an important reference value for expanding the engineering applications of RVCAs.