Air conditioning and heating system for the Škoda 39T Ostrava and 40T Plzeň trams

ABOUT THE PROJECT: Customer: ŠKODA TRANSPORTATION a.s., Year of implementation: 2020 – 2021 and still continues, Number of vehicles: 2 + 2, Place of operation: Czech Republic, Ostrava, Plzeň

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The air conditioning and heating system for the Škoda 39T and 40T trams (FCx concept) is designed for cooling, ventilation, heating and conditioning the air supplied to the passenger compartment and for the driver's cabin in the tram.

This is the third generation of POLL air conditioning units. The units have been completely redesigned with regard to reducing weight and increasing capacity. New is the concept of cooling power converters, where the heat loss does not reduce the cooling capacity of the air conditioning system, but is dissipated to the environment using condenser fans.

 

System concept: the system consists of three main devices:

  • passenger compartment air conditioning units of the KLM-T2520.PLZ01 type
  • driver’s cabin air conditioning units of the KLM-T0507.PLZ01 type
  • new generation heating units of the KVA-03 type

 

The interior heating units contain a contactless switch and its own control unit with a CAN line, which has improved control of thermal comfort in the vehicle. Newly, temperature sensors are also used on the side of air intake into the units. Thanks to this, we know the temperature distribution in the whole vehicle, which is an important parameter for improvement of the control of thermal comfort.

The passenger compartment and driver’s cabin air conditioning units are equipped with integrated compact semiconductor power supplies and use galvanically isolated DC/DC converters and inverters. The units can be powered directly from the 600 V or 750 V DC traction network, of positive or negative polarity depending on the place of operation. The cooling of the converters of the passenger compartment air conditioning unit is active, using the same fans as the condenser exchanger. The driver’s cabin unit contains converters with silicon carbide (SiC) semiconductors, which can be used to significantly reduce power losses, and consequently, the power electronics can be cooled passively; such cooling is robust, maintenance-free and economical. For the first time, we used a fully resonant topology with advanced control to stabilize the contact voltage.

The driver’s cabin unit converters: contain an input circuit + DC/DC + 2xDC/AC

 

The control units in this type of air conditioning system have also undergone significant innovation, reduction in size and simplification.

Key features of the power electronics of the KLM-T0507.PLZ01 unit

  • SiC-based semiconductors (DC/DC)
  • IPMs (DC/AC)
  • High efficiency, passive cooling outside the container (power dissipation does not heat the HVAC exhaust air, which would reduce the efficiency of cooling of the driver’s cabin)
  • Low installation height
  • Minimum wired connections, high reliability

 

Electrical parameters

  • Input voltage: 400-1200V
  • Output voltage: 720V, stabilized, adjustable in the range of 580V÷750V
  • Input power: 5.4kW, by replacing the resonant set and changing the fitting of the units up to 14kW
  • Efficiency (version 5.4kW): 96-98% @5.4kWout, 400-1200Vin
  • Galvanic isolation: 4kVAC
  • High switching frequency: 50-150kHz

 

Resonant topology adapted to a wide range of input voltages

  • Zero voltage switching (ZVS) and discharge of transistors when switching off (practically negligible dynamic losses)
  • Absence of overvoltage peaks on power semiconductors, lossless snubber
  • Low EMI
     

Characteristics of the air conditioning units

  • Control via vehicle Ethernet
  • Internal CAN line for the heating units
  • Compatible with TST (Tuning and Service Tool)
  • Advanced diagnostics, event logger and operational data recorder
  • Integrated converters
  • Continuous speed control of fans and compressor
  • Contactless heating system control
  • Power supply from overhead line
     

Technical parameters of the KLM-T2520.PLZ01 unit

Rated cooling capacity of the unit

25 kW

Rated heating capacity

20 kW

Rated power supply voltage

750 V DC

Operating range of the supply voltage

400 V – 1000 V DC, full capacity from 620V

Rated control voltage

24V DC

Refrigerant in the compressor circuit

R134a

Weight of cooling circuit components

400 kg

Maximum air supply

3000 m3 per hour

Operating temperature range

-40°C to +45°C

Communication interface

Ethernet, CAN

 

Technical parameters of the KLM-T0507.PLZ01 unit

Rated cooling capacity of the unit

5 kW

Rated heating capacity

7 kW

Rated power supply voltage

750 V DC

Operating range of the supply voltage

400 V – 1000 V DC

Rated control voltage

24V DC

Refrigerant in the compressor circuit

R134a

Weight of cooling circuit components

150 kg

Maximum air supply

650 m3 per hour

Operating temperature range

-40°C to +45°C

Converter cooling

Passive

Communication interface

Ethernet, CAN

Fotogalerie

POLL, s.r.o.

Výpadová 1676/4a
Praha 16
153 00

IČO: 62967754