The inverter drive for ship electric propulsion system because of its wide speed range, large driving torque, small volume, flexible layout, easy to change, easy installation, easy maintenance, good dynamic performance, the advantages of low noise, has become a major branch to foreign and domestic military civilian electric propulsion.
Through scientific experiments, accurate measurement and scientific evaluation to promote the performance of the motor and the propulsion frequency converter, and for scientific research, production and quality inspection to provide scientific data support, it is the basic work of marine electric propulsion system.
Due to the high voltage and large current of the ship electric propulsion system, the conventional test scheme is realized by using a single sensor and two meters. A sensor is usually used Holzer voltage, current sensor, the two meter is usually imported power analyzer.
Test principle of electric propulsion system for imported power analyzer
1.High power, high reliability, so the general use of multi-phase motor and inverter, the current number of more than fifteen phase. General power analyzer can only achieve 6 phases synchronous measurement.
2.The output fundamental frequency is low, the harmonic content is high, the general power analyzer under the condition of the nominal measurement accuracy is low, can not achieve the test requirements.
3.The electromagnetic environment is very complex, it is difficult to exclude the influence of the electromagnetic interference in the field of general power analyzer.
4.High voltage, general power analyzer can not be measured directly, the external voltage sensor (represented by LEM) bandwidth, amplitude accuracy and phase accuracy can not meet the test requirements of the test.
5.The fundamental frequency of low harmonic, high frequency, high frequency harmonic (with fundamental frequency is 5Hz, the switching frequency of 2.5kHz as an example, the harmonic mainly concentrated in the more than 500 times), the general power can not achieve the requirements of the analysis of harmonic analyzer.
6.The power of the electric propulsion system is large, the cost of a single test is high, the batch is small, and the test process often has strong research. The ideal test scheme is to make a comprehensive record of the original data, and to obtain the necessary data support according to the original data. However, imported instruments generally do not provide raw data, resulting in a large number of repeated tests.
Under the combined influence of the above factors, the measurement data is often deviated from the actual situation, and the test results and the design results of a military academy in the process of testing have been deviated.
A ship electric propulsion system model of fifteen phase induction motor test system with three WP4000 frequency conversion power analyzer, three sets of WP4000 using synchronous optical synchronization measurement, front-end measurement using 15 SP variable frequency power sensor with WP4000 through optical fiber communication, synchronous measurement of 15 phase induction motor all electrical parameters. The extended WP4000 can achieve the need of synchronous test for any phase motor and frequency converter.
WP4000 measurement of a ship propulsion system 15 phase motor schematic diagram
1.The synchronization of all the sensors connected by any power analyzer is realized by using synchronous optical fiber in the multi power analyzer, which can achieve the needs of the synchronous test of any phase motor and frequency converter.
2.In the full frequency range of the electric propulsion system, the system accuracy of 0.2% is maintained.
3.The front-end digital and optical fiber transmission technology, cut off the main transmission routes of electromagnetic interference, greatly enhance the electromagnetic compatibility.
4.Using the independent research and development of the inverter power sensor, the 10kV voltage can still maintain more than 30kHz bandwidth, maintaining 0.2% amplitude accuracy and the typical frequency of phase error of 0.02 degrees. (LEM voltage sensor is currently the highest test voltage of 6400V, bandwidth of 700Hz, amplitude accuracy of 1%, not the important phase of the index is not important. )
5.The harmonic analysis is only affected by the bandwidth, and is not affected by the number of harmonics. When the fundamental frequency is lower than 1Hz, it can be analyzed up to 100000 harmonics.
6.All the original data recorded during the test, after the original data to fully reproduce the experimental process, any parameters at any time, want to know from the reproducing process, avoid repeated test, reduce the test cost, improve test efficiency.