SU847477A1 - Device for converting coordinates of electric performance parameters of ac electric drive - Google Patents

Description

(54) DEVICE FOR TRANSFORMING WORKERS'S COORDINATES

ELECTRICAL PARAMETERS OF AC ELECTRIC DRIVE The invention relates to electrical engineering and can be used in a frequency-controlled AC drive for converting the phase parameters of an AC motor. A device for converting the coordinates of an electric drive is known, comprising a block of phase-sensitive rectifiers, a block of modulators, frequency generators and adders D3. A device is also known that implements a method of generating a frequency-variable multiphase voltage, which contains logic devices and two adjustable frequency generators. This device solves the problem of forming switching functions, the harmonic composition of which is such that it can be used as a sinusoidal multiplier | 2J. The disadvantage of this device is that it does not directly solve the problem of converting the coordinates of the electric drive. The closest technical solution to the invention is a device for converting the coordinates of the working electric parameters of an electric drive, containing N units for converting coordinates and two generators that are adjustable for 1x frequencies. In these devices, the coordinate conversion unit contains modulators, an adder, phase-sensitive rectifiers and an HRS filter. The disadvantages of the known device are low conversion accuracy and complexity. The purpose of the invention is to simplify the device while improving the accuracy of the coordinate transformation of the electric drive. This goal is achieved by the fact that the device for converting the coordinates of an AC electric drive, containing N coordinate conversion blocks (by the number of output coordinates) and two variable frequency generators, is equipped with logic blocks whose inputs are connected to the outputs of variable frequency generators, and the outputs of each of the N logic blocks are connected to inputs for reference signals of one of the N coordinate conversion units, the other inputs of which are the inputs to the device for converting the coordinates of the electric drive . In addition, in each of the coordinate transformation blocks containing modulators by the number of sensors for the coordinates of the electric drive, the adder and filter whose input is through su, the mater is connected to the outputs of the modulators whose inputs are connected to the sensors of the coordinates of the electric drive, the inputs for the modulators reference signals form the inputs of the reference signal block transform} W coordinates and connected to the outputs of the corresponding logic block.

FIG. shows a diagram of the device for converting the coordinates of the working electrical parameters; Fig, 2 - graphs of signals at the outputs of individual nodes of the device.

The device for converting the coordinates of the electric parameters of the electric drive consists of two blocks 1 and 2 of the coordinate transformation according to the number of output coordinates, of two logical blocks 3 and 4 and the block 5 of the control-1 converter.

Blocks 1 and 2 consist of modulators, adders 12 and 13, and filters 14 and 15, and the Conversion control block 5 consists of two oscillators 16 and 17 of the reference frequencies.

Transformable coordinates (phase points, voltage and other parameters) are fed to the inputs of modulators 6-8 and 9-11, the inputs for whose reference signals are connected to the outputs of logic blocks 3 and 4. The outputs of these modulators are connected to filters 14 and 15 respectively. The inputs of logic blocks 3 and 4 are connected to the outputs of both generators 16 and 17.

FIG. 2 denotes; .x-, xL, Xg, Xrt, x, x, y, and logical cone, characterizing the signals at the outputs of generators 16 and 17, respectively; angle d — angle of the coordinate system relative to the axes of the stator winding of the variable-frequency electric motor current.

The device converts the signals, proportional to the instantaneous values of the phase magnitudes (for example, stator currents or voltages) of the motor, to signals proportional to the projections of the current vector (gain) of the stator in the rotating coordinate system.

The device works as follows.

Signals proportional to the instantaneous value of the currents are fed to the inputs of the modulators 6-8 and 9-11. The inputs for the reference signals of these modulators receive signals from the output of logic blocks 3 and 4. The result of the conversion of modulators 6-11 are signals

T f i-ise T

 i (i ii5cPf-i where K-const is the proportionality coefficient;

F -F - switching functions L 11

modulators defined by the corresponding output signals of logic blocks 3 and

For this particular device Fg. - P have the following form:

B-, Fg-V4., - V ,,

..a .1-% а., - V.a

The components of the switching functions and .a are formed by the logical transformation of the signals from the output of the generators 16 and 17. For example, to implement the switching functions Fg - FQ of the modulators 6-8, logic circuit 3 performs the following logical operations:

1G with “-HAUU XC,

(4-pXox;, vy) r ,, xivy

, vS-.XaXi, vv

Claims (3)

where XD, Xg, x ,, Xd, Xg, x and y, y.logical variables characterizing the signals at the outputs of the generators 16 and 17, respectively (figure 2). The switching functions Fg - F are different from the switching functions P Fg, respectively, by a phase shift of 90 electrical degrees. Formation. Fg - F is implemented by logic circuit 4. As a result of the conversion of input signals by modulators 6-8 and 9-11, the subsequent summation of the modulated signals U JL / Q and Ug- U by adders 12 and 13 at the output of filters 14 and 15 receive signals proportional to the projection m of the stator current vector in the rotating coordinate system. The connection between the input and output signals of the device for the main harmonics of the switching functions of the modulators corresponds to the well-known transformation formulas J. (Sa 30-% S - n0), (where Kl is snoop-proportional aspect ratio. By introducing logical devices, the coordinate conversion is carried out directly by single modulation. As a result, the device as a whole simplifies and reduces the coordinate conversion error, which contributes to an increase in the quality of control of AC electric drives with a wide range 8.7 The invention claims a device for converting the coordinates of the working electrical parameters of an AC drive, comprising two variable frequency generators and N coordinate conversion units, each of which is composed of modules according to the number of coordinates of the actuator, an adder and a filter, whose input is through an adder associated with the outputs of modulators, which are distinguished by the fact that, for the sake of simplicity, it is equipped with logic blocks whose inputs are connected to the outputs of the generators and is adjustable x frequencies, the outputs of each of the N logical blocks are connected to the inputs for the reference signals of one of the N coordinate conversion blocks, the other inputs of which form the inputs of the device for converting the coordinates of the electric drive, and the inputs for the reference signals of each block are formed by the inputs for the reference signals of the corresponding modulators . Sources of information taken into account in the examination 1. Actuating devices with multiphase AC motors. Technical cybernetics, devices and elements of automatic control systems of the management system. M., Mashinostroenie, 1976, p.201-205. 2. USSR author's certificate number 230271, cl. H 02 R 7/42, 1968. 3. USSR author's certificate number 699639, cl. H 02 P 5/34, 1979.