Frequency-adjusted electric drive

FIELD: electric engineering and force industrial electronics, namely - powerful high voltage frequency-adjusted electro-drives.

SUBSTANCE: in frequency-adjusted electric drive, containing force transformer with at least four three-phased secondary windings, group of rectifier-inverter frequency transformers and driving electric engine with 2P number of poles, connected serially, in accordance to invention, winding of driving electric engine is made of 2P identical coil groups, each one of which is connected to separate three-phased rectifier-inverter frequency transformer, each one of which in its turn is connected to appropriate secondary windings of force transformer with transformation coefficient, equal to 2P.

EFFECT: high reliability of proposed frequency-adjusted electric drive due to decreased working voltages of driving electric engine and decreased total number of rectifier-inverter frequency transformers.

2 cl, 2 dwg

The invention relates to power industrial electronics, namely, frequency-regulated drives (CRA).

Known CRE [1], which contains high-voltage three-phase rectifier and inverter variable frequency.

The disadvantages of such CRA are the complexity of the power part and low reliability due to the high operating voltage of the motor and power section rectifier-inverter Converter.

Closest to the invention to the technical essence and the achieved result is CRA [2], which was the prototype, which contains the input transformer is used to convert a high input voltage low output, then it is low voltage with three-phase rectifiers is rectified and single-phase bridge inverters is converted into a voltage variable frequency, and then these inverters again looped and again in high-voltage three-phase type are connected to high-voltage three-phase motor.

The disadvantage of this variable frequency drive is the large number of single-phase inverters, voltage are sequentially formed, and their sum is applied to the motor windings, which significantly reduces the reliability of his work.

Object of the invention is the improving reliability of CRA by lowering the operating voltage of the motor and transducers, as well as reducing the total number of converters.

This task is achieved by the fact that in CRE containing a power transformer, at least four three-phase secondary windings, a group of 2P three-phase rectifier-inverter frequency converters connected to the engine with 2P number of poles, the motor winding is made of 2P identical coil groups and each of these coil groups connected to a separate three-phase rectifier-inverter of the frequency Converter, each of which, in turn, connected to respective secondary windings of the power transformer with voltage, 2P times less full supply voltage of the engine.

In CRA with electric motors with one pair of poles of its winding may be made of N identical successive coil groups, and these coil groups are combined into N identical three-phase system and then these N three-phase system connected to N rectifier-inverter units, which, in turn, connected to the corresponding windings 12-phase power transformer with a transformation ratio equal to N.

Figure 1 shows schematic diagram of the proposed CRA with 2P coil groups drive motor, and figure 2 shows the schematic diagram of CRA THE N three-phase converters, connected to the motor with one pair of poles, made of N identical successive coil groups.

CRE (figure 1) contains the power transformer 1 having a primary winding 2 and, for example, 4 three-phase secondary windings 3-6 offset one against the other, for example, 15 electrical degrees, 2P rectifier-inverter three-phase frequency converters 7 (7-1-7·2P) and the AC motor 8, in which the 1st, 2nd and 3rd phases are broken down into individual coil groups, respectively (8·1·1; 8·1·2; 8·1·3)÷[(8·2P·1); (8·2P·2); (8·2P·3)], and these coil groups for its basis (or ends) are connected to the corresponding three-phase inverters 7 (7·1···7·2P), and the corresponding opposite end (or beginning) of the groups of windings shorted and form the corresponding zero point.

Thus reduced supply working voltage of the motor 2P times, and each coil group of the engine is connected to the operating synchronously and in phase three phase inverters, each of these inverters via the rectifiers are connected to respective secondary windings 3-6 power transformer with 1 to 2P times less voltage than the rated voltage of the drive motor 8, which is 3 times reduced the total number in premetalco-inverter units and, accordingly, significantly increases the reliability of all CRA in General.

CRE (figure 2) also contains a power transformer 1 having a primary winding 2 and also, for example, 4 three-phase secondary windings 3-6 offset one against the other, for example, 15 electrical degrees, N rectifier-inverter three-phase frequency converters 7 (7·1÷7·N) and AC motor 8, in which the 1st, 2nd, and 3rd phases are broken down into individual coil groups (8·1·1; 8·1·2; 8·1·3)÷[(8·N·1); (8·N·2); (8·N·3)], and these coil groups its beginnings connected to the corresponding three-phase inverters 7 (7·1÷7·N), a corresponding opposite ends of the groups of windings shorted and form the corresponding zero point.

Thus, also in N times reduced operating voltage and converters and motor and, accordingly, increases the reliability of the engine.

The present invention operates as follows.

Served the supply voltage to the primary winding 2 (1) (or 2) of the power transformer 1, reduced to 2P times (or N times) the voltage from the secondary windings 3, 4, 5, 6 of the power transformer to the input of the rectifier-inverter 7 (7·1÷7·2P) (or 7 (7·1÷7·2N) ), ibid rectified napryagayutsya on three-phase inverters 7 (7-1-7-2P) (or 7 (7· 1÷7·2N) ). Control signals for these inverters are served simultaneously in accordance with the selected control law of the engine 8. In all phases of the inverters are formed of the same magnitude and phase currents and the motor operates in the same way as when the supply of these windings in a high voltage version of the same current magnitude and phase.

Thus, in the present invention in comparison with the prototype, while maintaining all the quality indicators of the Converter unit and the drive motor turns in low voltage shirokougolnyimi system. This increases the reliability, reduced weight and dimensions and, accordingly, the value of all currently very expensive conversion system frequency control powerful synchronous and asynchronous drives usually run high voltage. Such a powerful high-voltage motors are often multi for which the operation of splitting windings on separate groups is not large expenses, and in the manufacture of new models of engines, where the findings will be provided in advance, it is the fulfillment of a controlled system, in General, will greatly simplified by discovolante proposed CRA. Reduced and the cost of the engine. This operation rasdale the Oia possible for two-pole motors 2, when a pre-winding is divided into N consecutive sections. Performing a conversion unit for low voltage, especially on industrial voltage 380 V, 50 Hz, much easier than the high-voltage equipment. Thus, the task of lowering the operating voltage for the drive motor of CRE in 2P or N times, while reducing the overall number of rectifier-inverter units 3 times and, as a consequence, a significant increase in reliability for all CRA, is fully.

Sources of information

1. Tolstov YG high-Voltage thyristor converters for variable frequency drive //Automatic electric, power semiconductor devices, Converter equipment (Actual problems). - M.: Energoatomizdat, 1983. - S-409.

2. The energy-saving and high-voltage frequency converters // news drive technology, 2002. No. 9. - C.2-3.

1. Variable frequency drive (CRE)containing a power transformer, at least four three-phase secondary windings, a group of rectifier-inverter frequency converters and drive motor with 2P number of poles connected in series, characterized in that the winding of the drive motor is made of 2P identical coil groups to which each of which is connected to a separate three-phase rectifier-inverter of the frequency Converter, each of which, in turn, connected to respective secondary windings of the power transformer with a transformation ratio equal to 2P.

2. Variable frequency drive (CRA) according to claim 1, wherein when performing CRA with one pair of poles of its drive motor are made winding of N identical coil groups in N-phase system, which is connected to N three-phase rectifier-inverter the inverters, which, in turn, connected to the corresponding windings, for example, a 12-phase power transformer with a transformation ratio equal to N.