Auxiliary power supply (APS) Hossein Harimi 2014 hossin.harimi@yahoo.com

introduction audible noise less heavy equipment Recent developments in power electronic devices have allowed the design : manufacture and maintenance costs audible noise less heavy equipment auxiliary converters to be significantly reduced.

Discription Figure The HT input may be AC or DC with various ranges, typically 15kV to 25kV for AC supply and 400V to 3000V for DC supply. The controlled rectifier may be a PMCF bridge and could be used for power factor correction. The surge protection circuit may be a controlled crowbar or surge arrester. The Input filter usually consists of an inductor and capacitor.

continue The three phase inverter converts the DC input voltage into a pwm voltage pattern. This is controlled to regulate the AC output voltage The high frequency bridge inverter is a separately controlled unit to regulate the DC output voltage. The isolation transformers are used to provide: 1. Galvanic isolation between the HT input and theoutputs. 2. Step-up or stepdown voltage functions to ensure that the outputs are maintained over the full range of input voltage.

The DC rectifier merely rectifies the transformer output voltage waveform. The output filters are used to smooth the output waveforms to meet The AC output may typically be 3OkVA three phase, 415V rms, 50Hz. The DC output may typically be 11O V DC, 15kW. continue

TARGETS WHICH INFLUENCE THE DESIGN Low size and weight. Low cost to build (component cost, assembly time, testing time). Low cost of ownership (maintenance, reliability, spare parts). Short delivery time (from order placement to receipt of equipment).

continue Multiple supply voltages (e.g. Europe - 750V DC, 150QV DC, 3QOOV DC,150QV AC). Multiple outputs (customer dependant). Low audible noise. Electro-Magnetic-Compatibility.

NEW POWER ELECTRONICS TECHNIQUES WHICH HAVE HELPED TO MEET THESE TARGETS Thyristor Chopper + Thyristor Inverter GTO Chopper + GTO Inverter GTO Chopper + IGBT Inverter Inverter IGBT (direct on line) High Frequency IGBT Inverter (direct on line) High Frequency Intellgent Power Module (direct on line)

DeveloDments in IGBT Technoloay Due to the increase in IGBT current and voltage ratings, a "step-down" chopper between the HT input filter and three phase inverter is no longer required. The three phase inverter block connected direct to the HT input filter. When operating from an AC supply, the bridge rectifier may also make full use of the improved IGBT ratings. Thus IGBT devices now replace old devices such as thyristors and GTOs

It is therefore apparent that these improvements ensure a reduction in: Cost Cost of ownership Assembly time Equipment size and weight Audible noise

Increased Switching Frequency The possibilities of increasing the IGBT switching frequency means that the output filters may be reduced in size and weight. This ensures the following advantages: Reduced audible noise Reduced size and weight of complete equipment

continue However, if the frequency is too high, the filter components and transformers will need to be specifically constructed to cope with high frequency current harmonics. optimum solution found when comparing reduced size and weight with cost.

Ensuring High Levels of Safety and Reliability 1.Compact and Lightweight 2.High Efficiency 3.Excellent Output Voltage Control

High-redundancy Design (Option) Compatible with AC output parallel synchronous operation No interruption ofpower supply to loads even if one APS unit stops due to a loss of contact between the pantograph and contact wire

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