Q. No.1: For each of the following application, choose the best power switches a
ID: 2248207 • Letter: Q
Question
Q. No.1: For each of the following application, choose the best power switches and reason out why.– An inverter for the light-rail train (LRT) locomotive operating from a DC supply of 750 V. The locomotive is rated at 150 kW. The induction motor is to run from standstill up to 200 Hz, with power switches frequencies up to 10KHz.
– A switch-mode power supply (SMPS) for remote telecommunication equipment is to be developed. The input voltage is obtained from a photovoltaic array that produces a maximum output voltage of 100 V and a minimum current of 200 A. The switching frequency should be higher than 100kHz.
– A HVDC transmission system transmitting power of 300 MW from one ac system to another ac system both operating at 50 Hz, and the DC link voltage operating at 2.0 kV. (Cont…)
- The project manager has seen an advert for a BJT with the appropriate voltage and current ratings. The price is very attractive. You are under pressure to abandon the IGBT or MOSFET you have chosen, both of which are more expensive than the BJT. Set out the arguments you could use in favour of retaining the IGBT or MOSFET you have chosen.
NOTE : Kindly give a brief Reason , ThankYou so much ! Q. No.1: For each of the following application, choose the best power switches and reason out why.
– An inverter for the light-rail train (LRT) locomotive operating from a DC supply of 750 V. The locomotive is rated at 150 kW. The induction motor is to run from standstill up to 200 Hz, with power switches frequencies up to 10KHz.
– A switch-mode power supply (SMPS) for remote telecommunication equipment is to be developed. The input voltage is obtained from a photovoltaic array that produces a maximum output voltage of 100 V and a minimum current of 200 A. The switching frequency should be higher than 100kHz.
– A HVDC transmission system transmitting power of 300 MW from one ac system to another ac system both operating at 50 Hz, and the DC link voltage operating at 2.0 kV. (Cont…)
- The project manager has seen an advert for a BJT with the appropriate voltage and current ratings. The price is very attractive. You are under pressure to abandon the IGBT or MOSFET you have chosen, both of which are more expensive than the BJT. Set out the arguments you could use in favour of retaining the IGBT or MOSFET you have chosen.
NOTE : Kindly give a brief Reason , ThankYou so much ! Q. No.1: For each of the following application, choose the best power switches and reason out why.
– An inverter for the light-rail train (LRT) locomotive operating from a DC supply of 750 V. The locomotive is rated at 150 kW. The induction motor is to run from standstill up to 200 Hz, with power switches frequencies up to 10KHz.
– A switch-mode power supply (SMPS) for remote telecommunication equipment is to be developed. The input voltage is obtained from a photovoltaic array that produces a maximum output voltage of 100 V and a minimum current of 200 A. The switching frequency should be higher than 100kHz.
– A HVDC transmission system transmitting power of 300 MW from one ac system to another ac system both operating at 50 Hz, and the DC link voltage operating at 2.0 kV. (Cont…)
- The project manager has seen an advert for a BJT with the appropriate voltage and current ratings. The price is very attractive. You are under pressure to abandon the IGBT or MOSFET you have chosen, both of which are more expensive than the BJT. Set out the arguments you could use in favour of retaining the IGBT or MOSFET you have chosen.
NOTE : Kindly give a brief Reason , ThankYou so much !
Explanation / Answer
PE switches works in two states only:
– Fully on (conducting);
– Fully off (blocking)
Can be categorised into three group
– Diode : on and off states controlled by power circuit only
– Thyristor (SCR) : Latched on by low-power control signal but must be turned off by power circuit. Cannot be turned off by control signal.
– Controllable switches: Can be turned on and off by low-power control signals (e.g. BJT, MOSFET, IGBT, GTO)
a)We can use MOSFET in an inverter for the light-rail train (LRT) locomotive.The obvious advantage of a MOSFET is its very low drain-source on state voltage drop because of a very low drain-source on state resistance (RDSON). For a BJT, the collector-emitter saturation voltage may vary with the level of the base current and the collector current or simply the load.
b)FOR SMPS we use IGBT.They're displacing MOSFETs in many SMPS applications up to and sometimes exceeding 200 kHz.IGBTs have higher transconductance than high-voltage MOSFETs, due to minority carrier injection. With this, they benefit more from higher gate voltage in terms of minimizing conduction loss.
c)Thyristors are used as switches for HVDC transmission system and thus the valve becomes controllable. The thyristors are made of highly pure monocrystalline silicon. The high speed of innovation in power electronics technology is directly reflected in the development of the thyristor. The high performance thyristors installed in HVDC plants today are characterized by silicon wafer diameters of up to 5.
d)MOSFET is better.
When both device types are tested in hard-switching applications, measurements show that the MOSFETs exhibit lower losses.Recent advances, though, have given the advantage back to MOSFETs. The lower-charge MOSFETs now available have reduced the losses at high frequency. They have, therefore, reasserted MOSFETs' dominance in hard-switching applications above 50 kHz.
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