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An electric drive has been developed for various transportation systems which is not inferior to the best world analogues in the basic technical parameters, but excels them in the key technical parameter: its cost is lower. The electric drive proposed may be applied basically in the field of electric transport serving passengers traffic.

The last achievements in the field of technology of manufacturing power integral semiconductor technique enable to solve a number of new problems in overall designing the regulated alternating current electric machines and static frequency transformers, and thereby to create a principally new type of regulated electric motors with built-in transformers and microprocessor controls.

The unification of all the set of functional elements (power units, microprocessor-controlled and diagnostic components) in one semiconductor module in combination with the cooling system united with the motor enables to place them compactly in the construction of the electric machine. Any type of multiphase electric machine - asynchronous with a short-circuit rotor, synchronous with excitation from constant magnets, inductor, and other types of contacts machines - can be used as motors.

In Figure 1 the appearance (with the casing removed) is presented of the pilot model of the multiphase regulated asynchronous electric motor with a short-circuit rotor having a power of 18,5 kW with a built-in transformer on optron power modules and a control unit ensuring smooth sinusoidal currents in the motor.

The power range of the motors under consideration is determined by technical possibilities of the integral power modules applied. In particular, for IGBT (Siemens produced modules, Germany), this range lies within 5 kW to 500 kW, the range of regulation is 1/100.

The fields of application include: pumping units, load-lifting and towing transportation mechanisms, in robotics and machine-tool construction, in chemical and textile industry, as well as in public utilities.

The economic effect is determined by higher operating characteristics and by the lower cost involved (approximately by 20%) as compared to a set consisting of a motor separately and a transformer separately.

An industrial series of regulated alternating current electric motors on optron modules has been developed for ship mechanisms. The regulated electric motors have been developed on the basis of the general purpose industrial asynchronous motors with a short-circuit rotor having a height of the rotation axis of 132, 160, 180 mm. The specifications of the mentioned motors are presented in the table attached.

No	Parameter	Value
1	Nominal input voltage, V	380
2	Number of input voltage phases	3
3	Nominal input frequency, Hz	50
4	Height of rotation axis, mm	132, 160, 180
5	Nominal input current, A	25, 40, 63
6	Nominal power on shaft, kW	11,0 18,5 30
7	Nominal rotation frequency, rev/min	1550, 3000
8	Working range of rotation frequency regulation, rev/sec	1/1...1/10
9	Efficiency in nominal conditions, per cent	not less than 88
10	Preciseness of maintaining established rotation frequency magnitude, percent	ą 1

The development of the electric drive proposed has reached the stage of operational tests of working pilot models. The tramway car with a tractive asynchronous electric driver and the transformer for feeding ventilators of calorifers of tramway car cabs are in the process of operating on line with passengers.

The algorithm of controlling tractive transformation plants and forming rotation frequency of tractive motors are protected by patents.

The present publication is designated to promote the search of investors and customers for completing works on the preparation of serial production output and the distribution of the subject electric drive, as well as for carrying out works on re-equipping the existing rolling-stock park of electric transport.