Patent ID: 9391546
Filing Date: 2016-07-12
CPC Classification: H02P

Claim Text:
1. A direct torque control method for inhibiting torque ripples, comprising the following steps: step 1: establishing an MC voltage vector switching table visually displaying degrees of change in torque and flux a spatially rotational coordinate system x-y is established and a stator flux ψ in formulae (1) and (2), v a voltage vector V in formulae (3) and (4), V a torque evaluation function τ, a flux evaluation function λ and a counter electromagnetic force evaluation function e are defined as below: formula (3) and formula (4) are substituted into formula (5) and formula (6) respectively, to obtain torque and flux evaluation functions τ similarly, torque and flux evaluation functions of all voltage vectors of the MC are obtained; both the torque evaluation function τ and the flux evaluation function λ are binary periodic functions; within one of θ the average value of each of the regions is used to represent the value of the torque evaluation function τ and the value of the flux evaluation function λ of this region, and thus functions for calculating the average value of the torque evaluation function τ and the average value of the flux evaluation function λ are defined as: in formulae (10) and (11), I α ={1,2,3 . . . 12}, I θ ={1,2,3 . . . 12}; and round( ) denotes proximity rounding function, p τ denotes a torque evaluation value, and p λ denotes a flux evaluation value; if k=10, the torque evaluation value p τ and the flux evaluation value p λ are integers between −9 and +9; formula (5), formula (6) and formula (7) are substituted into formula (1) and formula (2) to obtain a function relational expression between the torque evaluation function τ, the flux evaluation function λ, the counter electromagnetic force evaluation function e, and a rate of change in torque and a rate of change in flux of the motor: from formula (10), formula (11), formula (12) and formula (13), a function relational expression between the MC torque evaluation value p in formulae (14) and (15), the left part of symbol ∝ denotes an average value of the rate of change in torque and the rate of change in flux of the motor within a region, wherein the average value of the counter electromagnetic force evaluation function is: it can be seen from formula (14) and formula (15) that the torque evaluation value p the p the torque evaluation function τ and the flux evaluation function λ are products of the two functions, wherein the term containing α the torque evaluation functions τ and flux evaluation functions λ of 18 effective vectors of the MC have the following situations: situation 1: τ and λ of a same vector have a same temporal expression, and the spatial expression of λ is π/2 lagged behind the spatial expression of τ; situation 2: τ situation 3: τ τ τ situation 4: the values of negative vectors τ In the situation 1-4, τ+1 to τ+9 and λ+1 to λ+9 respectively represent torque and flux evaluation functions of the +1 to +9 switching combination, τ−1 to τ−9 and λ−1 to λ−9 respectively represent torque and flux evaluation functions of the −1 to −9 switching combination; according to situation 2 and situation 3, the vertical header, i.e., the stator voltage sector, and the horizontal header, i.e., the stator flux sector, of the switching table showing the effect of the vector V after translating the vertical header, i.e., the stator voltage sector, and the horizontal header, i.e., the stator flux sector, an MC voltage vector switching table visually displaying degrees of change in torque and flux is formed; and step 2: inquiring the torque evaluation value p according to a conventional MC-DTC control method, a voltage vector of a matrix converter is selected from the MC voltage vector switching table; the number of a sector of the stator flux vector is calculated; the number of a sector of the input voltage vector is calculated; the torque evaluation value p In formulae (17), T