DC brushless motors are widely adopted for their simplicity of control, even in sensorless configuration, and their high torque density. On the other hand, induction motors are very economical due to the absence of permanent magnets; for the same reason they can easily be driven in the flux-weakening region to attain a wide speed range. Nevertheless, high dynamic induction motors drives, based on field-oriented (FOC) or predictive control, require large amounts of computing power and are rather sensitive to motor parameter variations. This paper presents a simple DTC induction motor control algorithm based on a well-known BLDC control technique, which allows to realize a high dynamic induction motor speed control with wide speed range. The firmware implementation is very compact and occupies a low amount of program memory, comparable to volt-per-Hertz- (V/f-) based control algorithms. The novel control algorithm presents also good performance and low current ripple and can be implemented on a low-cost motion control DSP without resorting to high-frequency PWM. 1. Introduction DC brushless (BLDC) motors are widely employed in industry and transportation due to their high performances and reliability. Since such motors have no brushes, they need a solid-state commutation circuit in order to supply the stator windings according to rotor position. Rotor position, therefore, must be determined, and this measurement is typically performed using Hall sensors or incremental encoders (at an additional cost) or sensorless techniques. If rotor position information can be achieved without additional hardware complexity, the cost can be reduced. Sensorless techniques are widely used especially in low-cost BLDC applications, such as fans and compressors [1, 2]. Such techniques usually rely on the measurement of electrical variables such as currents and back electromotive forces (BEMFs), which can be performed with the same DSP or microcontroller used for drive control [3]. Induction motor speed control represents a widely studied topic in industrial applications. The simplest control schemes are based on V/f (volt per Hertz) operation, while on the high side of the spectrum there are many algorithms, roughly separable in two groups: field-oriented control (FOC) based and predictive Control (PC) based. Direct Torque control (DTC) is a hysteresis control which belongs to the latter category; it was first developed as a cheaper alternative to FOC when the processing power required by FOC was too expensive [4]. It allows dynamic performances comparable or superior to
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