Control method for frequency-conversion starting of diesel engine of alternating-current diesel locomotive

Abstract

The invention discloses a control method for frequency-conversion starting of a diesel engine by utilizing a synchronous generator in an alternating-current diesel locomotive. The control method comprises the following steps of carrying out no-load pre-excitation according to a calculated no-load exciting current ifb; judging whether an exciting current reaches ifb, if the exciting current does not reach ifb, returning and continuously carrying out the pre-excitation; otherwise, carrying out initial positioning according to a preset initial position angle; judging whether the initial positioning is finished, if the initial positioning is finished, selecting a torque command curve according to a preset starting time; otherwise, returning and continuously positioning; carrying out torque loop control according to the torque command curve; judging whether the rotating speed of a motor reaches a preset ignition speed, if the rotating speed of the motor reaches the preset ignition speed, stopping the motor; otherwise, returning and continuously controlling. According to the control method, an air-gap field control strategy, in which the power factor is accurate to 1, of the synchronous generator is realized, and meanwhile, by designing an off-line calculation method for planning the torque command curve according to a preset starting finishing time, the output current of the motor required in a starting system is better optimized.

Description

technical field [0001] The invention relates to the technical field of frequency conversion starting of diesel engines of AC diesel locomotives, and more specifically relates to a control method for frequency conversion starting of diesel engines of AC diesel locomotives. Background technique [0002] In occasions such as AC diesel locomotives, its own traction inverter can be used to drive the synchronous generator in the diesel engine-synchronous generator set to run electrically, and then the diesel engine can be started, which can save investment in special starter motors and gearboxes and space arrangement. [0003] The existing synchronous generator frequency conversion starting diesel engine scheme can be divided into two types: series excitation and shunt excitation according to the connection mode of synchronous generator excitation circuit and armature circuit. In the series excitation scheme, the synchronous generator works as a DC motor without a commutator in t...

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Problems solved by technology

In the series excitation scheme, the synchronous generator works as a DC motor without a commutator in the motoring state, and the excitation winding needs to be connected in parallel with a shunt resistor to realize series excitation control. This control scheme has been widely used in practice. Its principle is simple, but it requires additional The excitation is controlled by a resistor, and the control range of the excitation is narrow, the effect of motor torque control is relatively extensive, and the output current of the system is relatively large

Regarding the shunt excitation scheme, although some schemes have been proposed in terms of the circuit topology of the drive inverter and the control of the synchronous generator, there is still a lack of real practical high-performance system solutions.

And the power factor in the variable frequency starting control method in the existing scheme can only be approximately 1, wherein, the d-axis leakage inductance L is ignored sδ , but actually for the synchronous generator in the diesel generator set, the d-axis leakage inductance L sδ and d-axis armature reaction inductance L md Compared with , the proportion is still quite large, and if it is ignored directly, it will bring a considerable control error

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