Synthesis of Direct Torque and Rotor Flux Control Algorithms by Means of Sliding-Mode Theory

Combining the principles of variable structure, direct torque control, and space vector modulation for induction motor fed by matrix converter

“…There are many different ways to control the parameters of each structure and to define the switching logic [15][16][17][18][19][20]. In this paper, the strategy is based on torque and square of stator flux variable structure controllers, the block diagram of the proposed strategy is shown in Fig.…”

“…In this paper, the time-derivative terms of the system states are designed according to "reaching law". The "reaching law" is a differential equation which specifies the dynamics of a system states [20]. The form of the "reaching law" used is…”

“…It can be seen from Table 2 that the switching status selection of matrix converter is 9, 7, 3 and 1 when k v = 1 and k i = 1, the values of δ 1 and δ 4 are positive while the values of δ 2 and δ 3 are negative calculated by (20)- (23), so the final switching status selection is +9, −7, −3 and +1 which can be seen in Table 1.…”

“…However, the conventional DTC algorithm using hysteresis comparators has some drawbacks: it generates large torque, flux and current ripples especially in a low speed range; the input filters are difficult to design because of the variable switching frequency. There exist several methods which are designed to improve the performance of the classic DTC for a conventional inverter drive system, but there are few methods to improve the performance for the matrix converter drive system [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The small voltage vectors of matrix converter were used in the direct torque control scheme for matrix converter drives to reduce the electromagnetic torque ripples [21], the torque hysteresis comparator is modified in order to distinguish between large and small torque errors, then a new look-up table for direct torque control using small vectors and large vectors of matrix converter is adopted.…”

“…The variable-structure control (VSC) is an effective method to overcome these problems. It features robustness to parameter variations of load disturbances, fast dynamic response, and simplicity of design and implementation [15][16][17][18][19][20]. In this paper, a novel method of the direct torque control using a variable structure control scheme with the space-vector pulsewidth modulation is derived, which is characterized by a constant switching frequency, a fast dynamic torque response and low torque ripples.…”