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Variable Speed Drive (VSD) Frequency Inverter Application - General BITZER Kühlmaschinenbau GmbH 2013.

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Presentation on theme: "Variable Speed Drive (VSD) Frequency Inverter Application - General BITZER Kühlmaschinenbau GmbH 2013."— Presentation transcript:

1 Variable Speed Drive (VSD) Frequency Inverter Application - General BITZER Kühlmaschinenbau GmbH 2013

2 BITZER // Climatechno 2013// Page 2 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with integrated FI

3 BITZER // Climatechno 2013// Page 3 The Use of Frequency Inverters with BITZER Compressors – General Why Frequency Inverter?  Possibility for infinite speed modulation with 3-phase asynchronous motors Pros: /Infinite capacity control  Higher part load energy efficiency  Without additional pressure fluctuation  Steady suction pressure and TX valve operation  Smaller temperature differences at HX (higher suction pressure, lower discharge pressure) /Trans-synchronous operation  Smaller compressor  Enhanced capacity control range /Soft start function  Reduced starting current with full motor torque  No start unloader required  Reduced mechanical load  Minimized danger of liquid slugging during start-up

4 BITZER // Climatechno 2013// Page 4 The Use of Frequency Inverters with BITZER Compressors – General Speed control of compressor Energy savings: 15% Page 113 (of 270)

5 BITZER // Climatechno 2013// Page 5 The Use of Frequency Inverters with BITZER Compressors – General average evap. temp. with fixed speed compressor VSD VSD with suction pressure control - vs.- fixed speed // Example 0.1 bar Source: FrigoPack (www.frigokimo.com)

6 BITZER // Climatechno 2013// Page 6 - 4°C -18°C to - 12C Δt14 K The Use of Frequency Inverters with BITZER Compressors – General Why Frequency Inverter? /Fixed frequency rack system Setpoint

7 BITZER // Climatechno 2013// Page 7 The Use of Frequency Inverters with BITZER Compressors – General Why Frequency Inverter? /Infinite capacity control to - 12°C Δt 4K Setpoint

8 BITZER // Climatechno 2013// Page 8 The Use of Frequency Inverters with BITZER Compressors – General Cons: /Power consumption at 50 Hz slightly higher compared to direct operation (losses in power electronics, compressor motor) /Due to wide speed range risk of resonances and vibrations in pipe work /Higher efforts in projecting and selection of components /Very often higher installation costs (higher investments)

9 BITZER // Climatechno 2013// Page 9 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI

10 BITZER // Climatechno 2013// Page 10 Frequency Inverter – Basic Principle Rectifier Transition Circuit Inverter (IGBT’s) Control Circuit Motor 3~ Control Voltage L1 L2 L3 Pulse Width Modulation Sine wave throttles (depending on FI output quality) Net work throttles (recommended due to EMC) (Capacitors)

11 BITZER // Climatechno 2013// Page 11 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI

12 BITZER // Climatechno 2013// Page 12 The Use of Frequency Inverters with BITZER Compressors – General n Motor = f x 60 Number of pole pairs – n Slip Function of Frequency Inverter Frequency Modulation U / f - Operation: Inverter must control voltage and frequency in a constant ratio  Motor torque required remains constant with positive displacement compressors Consequences if no voltage adaptation  Increased motor current  Risk of motor overheating  Decrease of motor torque

13 BITZER // Climatechno 2013// Page 13 Requirements on Motor Characteristics and Layout of Frequency Inverter With Positive Displacement Compressors (Recips, Scroll, Screws)  Torque remains “constant" with speed change  Power absorbed changes approx. proportional to the speed M = [Nm] P = U x I x  3 x cos  [W] P x 9,55 n (1/min) Mechanical side: Electrical side:

14 BITZER // Climatechno 2013// Page 14 Requirements on Motor Characteristics and Layout of Frequency Inverter Above max. voltage (without voltage adaption):  Ratio U/f declines  Absorbed current rises  Danger of motor (temperature) overload! ~ constant M = [Nm] U x I x  3 x cos  x 9,55 n Mechanical side and electrical side combined: „Demanded“ torque (M) = remains constant from mechanical side U/n ~ U/f = constant (by inverter controller)  Current “I” remains (almost) constant (with constant operating conditions, e.g. SST, SCT)

15 BITZER // Climatechno 2013// Page 15 Frequency Inverter − Voltage & Frequency with Constant Torque (Supply 400V-3-50 Hz) Voltage Frequency [Hz] 87 [V] Nominal Motor Voltage: A A: 400 V-3-50 Hz 40P / 40D B B: 380 V-3-60 Hz 35P / 35D C C: 230 V-3-50 Hz 40S Examples Speed range limit for standard recips)

16 BITZER // Climatechno 2013// Page 16 Frequency Inverter – Power & Torque with Motor Winding Layout for 230V-3-50Hz Frequency[Hz] Torque M Power P [%] Voltage [V] Current I Speed range limit for standard recips)

17 BITZER // Climatechno 2013// Page 17 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI

18 BITZER // Climatechno 2013// Page 18 The Use of Frequency Inverters with BITZER Compressors – General General Selection Criteria Frequency and Speed Ranges /Depending on compressor technology and application Reciprocating, scroll, screw compressor Open drive, semi-hermetic, hermetic Motor layout & power supply Operating conditions, refrigerant, thermal load Inverter selection for max. operating current, see technical data (e.g. KP-100) Increased starting torque during starting phase /Example for piston compressors depending on number of cylinders (2 // 4 // 6)  factors (2 // 1,6 // 1,5)

19 BITZER // Climatechno 2013// Page 19 The Use of Frequency Inverters with BITZER Hermetics & Semi-hermetics Special Requirements on Frequency Inverter and Connection Wires Critical Frequency and Speed Ranges /Dependent on operating conditions resonances may occur in certain frequency (speed) ranges /Examination by tests under real conditions critical frequency ranges must be skipped by adequate programming of the inverter Note of Voltage Magnitude /Consider length of wire in manufacturer's documentation!! /Possible problems: motor noise / insulation failures Screened wires (incl. grounding) from inverter to motor (Electro Magnetic Compatibility)

20 BITZER // Climatechno 2013// Page 20 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI

21 BITZER // Climatechno 2013// Page 21 The Use of Frequency Inverters with BITZER Compressors – General Issues Selection Criteria for Motor and Inverter Motor selection according to manufacturer's requirements Special Criteria: /Air flow is not in proportion to the motor speed increased power with trans-synchronous operation possibly insufficient cooling with sub-synchronous operation Motor Selection / Application Range /dependent on inverter design and quality of sine wave additional spare capacity for the motor may be required Inverter selection according to specification of motor and inverter manufacturers Open Drive Compressors

22 BITZER // Climatechno 2013// Page 22 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI

23 BITZER // Climatechno 2013// Page 23 NEW ECOLINE VARISPEED KP CE4 Varispeed Series

24 BITZER // Climatechno 2013// Page 24 25Hz30Hz 25Hz 87Hz NEW ECOLINE VARISPEED

25 BITZER // Climatechno 2013// Page 25 NEW ECOLINE VARISPEED Special Design Features (1) Solidly flanged FI // no vibrations Suction gas cooled FI // no air filter (service) needed // no load restrictions at high ambient temp. Shielded motor cable // short and preassembled

26 BITZER // Climatechno 2013// Page 26 NEW ECOLINE VARISPEED Special Design Features (2) Easy commissioning // FI completely parameterized Full torque up to 87Hz // motor delta connected (230V-50Hz  400V-87Hz) Up to 70% more capacity // compared to fixed speed version // infinite control range more than 3:1

27 BITZER // Climatechno 2013// Page 27 NEW ECOLINE VARISPEED Compressor Installation (Example with CE3-F1) /Shielded connection cable between inverter and compressor is pre-assembled /Power supply has to be connected to frequency inverter /Check suction and discharge line for resonances under real operating conditions

28 BITZER // Climatechno 2013// Page 28 NEW ECOLINE VARISPEED Compressor Installation Operation and control // Frequency inverter F1 The compressor/ inverter unit is controlled by an external controller. It can be operated with factory defaults, no parameterization is required. There are two characteristic curves preprogrammed within the inverter. Depending on the control line connection on terminal a voltage (0..10 V) or current (4..20 mA) dependent characteristic curve can be used. Terminals 1 & 8: mA Terminals 2 & 8: V

29 BITZER // Climatechno 2013// Page 29 NEW ECOLINE VARISPEED Failure Analysis /Generally no additional adjustment by manual control unit required Inverter is pre-programmed to its assigned compressor /If required, pre-programmed parameter can be changed – especially in case of vibrations within the installation Multiple frequency ranges can be masked out

30 BITZER // Climatechno 2013// Page 30 NEW ECOLINE VARISPEED Payback Period (following example based on previous compressor models, but results based on NEW ECOLINE expected to be similar)

31 BITZER // Climatechno 2013// Page 31 VARISPEED Compressors // Payback Period (1) Example: Cooling capacity 37kW + 5kW reserves Conditions: R404A; t o = -8 °C; t c = 20°C … 45°C; Δt oh = 20K;  t cu =10K Installation place:Berlin Rack3x 4DC-7.2Y2x 4EC-6.2Y + 1x 4EC-6.F1Y Number of comp.33 Capacity max.42,4 kW43,9 kW Capacity min.14,1 kW5,6 kW Control range33 / 66 / 100 %12,8 … 100 % Control typestepsinfinite

32 BITZER // Climatechno 2013// Page 32 Type Qo [kWh] P in [kWh] Annual COP 4DC-7.2Y Rack (steps) ,84 4EC Rack (infinite) ,08 Results:6 % higher annual COP (system)!  Payback period below 2 years! VARISPEED Compressors // Payback Period (3) Annual energy consumption To be considered: /Comparison based on constant load – variable load requirements lead to additional COP weakness of fixed speed compressor applications / Winter operation leads to additional COP weakness of fixed speed application

33 BITZER // Climatechno 2013// Page 33 Variable Speed Drive // Frequency Inverter Application - General Contents /Pros & cons /Basic principle & function /Requirements on motor characteristics and layout of frequency inverter /Selection criteria (inverter, cables) /Special considerations for open drive compressors /Semi-hermetic compressor with Integrated FI Any Questions? √ √ √ √ √ √

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