Matrix Technology for next generation Variable Speed Electric Motor Control

Transcription

1 Matrix Technology for next generation Variable Speed Electric Motor Control

2 First.Why do we need variable speed control of electric motors? Soft starting of electric motor Multiple starts and stops without limit Adapting driven load to capacity demands of the process Energy Savings

3 Flow, Speed (RPM), Torque & Power Affinity Laws Flow - Torque - Output Power 50% RPM = 50% Flow 80% RPM = 80% Flow 50% RPM = 25% Torque 80% RPM = 64% Torque 50% RPM = 12.5% Power 80% RPM = 51.2% Power % of % 10% 20% 30% 40% 50% 60% Speed (RPM) 70% 80% 90% Flow Rate Torque (Pressure) Output Power 100%

4 Pumps & Power Throttle Valve vs VFD % Energy Consumed % Flow Rate Throttle Valve VFD

5 Key Issues for Specifying Variable Speed Motor Controllers Upstream effects to power grid Downstream effects to electric motor, thus motor reliability Controller reliability Controller Size, weight, cost Controller efficiency Control room infrastructure costs Affect on motor cost Torque and Speed control performance of electric motor for the specific application

6 Affects of Traditional VFDs in the System Fluid Analogy Picture a 10 inch pipe containing water at 4160 PSI Gate valve operates in the center of the pipe opening and closing at 1000 times per second Water hammer travels in both directions from the valve Upstream effects Downstream effects

7 Affects of Traditional VFDs in the System A VFD in the electrical supply system acts like the valve, creating disturbances upstream and downstream The VFD switches at up to 15,000 times per second! Instead of pressure and flow, affects are on voltage and current Upstream Affects Downstream Affects VFD

8 Upstream Affects of Input Voltage and Current Waveform Distortion? Reduced power factor-circulating currents that tax electrical l system capacity, but do no work (Those who do not maintain good power factor build cogen plants and buy larger generators) Adverse affects on transformers, conductors, circuit breakers, and generators Higher heating losses in power delivery equipment Spurious CB and fuse trips

9 Why be Concerned About Voltage and Current Waveform Distortion? Inefficient use of available capacity from the utility grid will limit plant expansion or force development of expensive cogeneration capacity Generators have high impedance and can lose regulation due to the harmonic voltage drop across the stator. In addition, the excess heating in the windings can force derating of the generator, and in severe conditions can trip the generator When generators are used as back up power supplies, the effect of the harmonic content in the electrical distribution ib tio system must be analyzed both under normal utility power and under standby generator power. Typical generators will have 15% to 20% internal reactive impedance, whereas utility transformers will typically have between 2% to 5% internal reactive impedance

10 Downstream Affects-Bearings The output of the traditional 2 level voltage source PWM type VFD causes a voltage potential to build on the shaft of the AC motor Arcing occurs that will pit the bearing races as this voltage seeks ground Motors with electrically isolated bearings should be specified Brush rig shaft ground kit is alternate solution

11 Downstream Affects-Bearings

12 Downstream Affects- Voltage Stress on Motor Insulation Caused by High dv/dt Present VFD technology poses a documented threat t to motor insulation life Each VFD output pulse results in a voltage spike potentially as high as 3 times nominal motor voltage AC motors must have a sufficiently high Corona Inception Voltage (CIV) to survive voltage spikes (dv/dt) Special motor designs (inverter duty)

13 Downstream Affects Downstream Affects Voltage Stress on Motor Insulation

14 Downstream Affects 3 level low voltage inverter = ½ dv/dt P V 0 V PN N

15 Downstream Affects Reduction of dv/dt levels on the output Multi-level control eliminates motor surge voltage issue (Reflected Wave Phenomenon) The output waveform is nearly sinusoidal. No surge voltage to negatively affect the motor Low torque ripple - good for load Audible noise as low as commercial power supply operation Existing motors and motor cables can be used Output Voltage Waveforms 2-Level Inverter Multi-level Inverter Matrix 4.16kV output waveform.

16 Present Medium Voltage (MV) Inverters begin to solve Downstream Affects Medium Voltage Distribution ib ti Range 2.4 to13.8kv 3.3, 3 6.6, 6 and 13.8kV class are common standards 4.16kV dominant in US, some 2.4kV in US and Canada Traditional Medium Voltage Inverter Types Current Source (CSI) Rockwell Power Flex 7000 (ca late 70s) 3 Level Voltage Source (VSI) - ABB ACS1000 (ca early 90s) 5 Level VSI ABB ACS5000, Toshiba T300MV (ca mid 90s) Multi level VSI Yaskawa MV1S, Siemens Robicon Perfect Harmony, others (ca mid 90s)

17 Traditional VFD (Voltage Source Type) The inverter changes AC power to DC power and then changes it back to AC power AC DC AC

18 Fourier Analysis of the waveforms found in a three phase diode rectifier shows low order harmonics including the 5th, 7th, th, 13th, etc. Harmonic Distortion-the Unsolved Upstream Affect Calculation of true power factor -700 Figure 18.1 considers the energies contained on these additional frequencies % Figure 6-2 shows the resulting harmonic spectrum based on Fourier analysis of the current 30.38% waveform shown in figure Ma agnitude (as % of Funda amental Three phase diode rectifier, line voltage/current Voltage Current Normalized Harmonic Spectrum 5.55% 7.16% 4.83% 4.32% 3.59% Harmonic Order Figure 18.2

19 How Harmonics Lower Efficiencyi True power factor is greatly affected by THD. Consider VFD below with no filters. True power factor is improved, when current distortion is corrected (including filters or active switching front ends) Figure Figure 19.1 Power Factor Considering 92.8% I THD pf = kw/kva I THD = 92.8% pf = 1/Sqrt( ) pf = 73.3% Figure 19.2 Power Factor Considering 52.6% I THD pf = kw/kva I THD = 52.6% pf = 1/Sqrt( ) pf = 88.5% Figure 19.2

20 What is a Matrix Converter? Generates variable AC voltage and frequency directly from AC power supply AC-AC direct conversion without DC link Energy saving (low switching losses), Long product life, Space saving Detail of bi-directional switch No DC bus capacitor Matrix Converter (Single cell) S1 S2 S3 Power Source S4 S5 S6 Bi-directional semiconductor switching device Motor Motoring Power Regenerative Power

21 One Bidirectional Cell 635V

22 Configuration of the Medium Voltage Matrix Power Cells Configuration of MxC power cell section (4.16kV class: 4 cells in series for each phase) Configuration of an Matrix power cell (Bi-directional IGBT switch) U Input Output t U1 2402V Phase Voltage U2 U3 U4 4160V Line Voltage W W2 W1 W3 W4 V4 V3 V2 V1 V Multi-level control is the optimum configuration for existing AC motors

23 Configuration of a Medium Voltage Matrix Converter The Matrix uses PWM control with multiple outputs connected in series, using 4 MxC cells per phase (for 4.16kV). Main circuit Cell control circuit (Fiber optic) AC 4.16kV Input (Primary) MxC CELL MxC CELL MxC CELL MxC CELL Output (Secondary) U4 U3 U2 U1 U N MxC CELL MxC CELL MxC CELL MxC CELL V M V4 V3 V2 V1 W MxC CELL MxC CELL MxC CELL MxC CELL W4 W3 W2 W1 Controller MxC Cell

24 Panel Configuration kV 1250HP Transformer - Dry type, multiple winding with high reliability Class H insulation Power Cells - No DC Link capacitors - Modular, draw out type for simple replacement - Easy access for circuit board and fuse Control -Visible arrangement -Low voltage -High reliability PCB Control section Transformer section Power cell section

25 Solution for Upstream Affects Minimal Input Harmonics Multi-level control virtually eliminates input harmonics Input Current Waveforms Compliant with International Standards for Power Quality 6-pulse rectifier No harmonics filter or active filter is required Matrix

26 Solution for Downstream Affects Sinusoidal Output Voltage The output waveform is nearly sinusoidal. Multi-level control eliminates motor surge voltage issue (Reflected Wave Phenomenon) Low torque ripple - good for load. Audible noise as low as commercial power supply operation Existing AC motors and motor cables can be used Output Voltage Waveforms 2-Level Inverter Multi-level Inverter Matrix output waveform.

27 Matrix Converter How does it solve the issues? Upstream effects to power grid Downstream effects to electric motor, thus motor reliability Controller reliability Controller Size, weight, cost Controller efficiency Control room infrastructure costs Affect on motor cost Torque and Speed control performance of electric motor for the specific application Minimal Input and Output harmonics No filters required Power factor at input is.97+ regardless of buss characteristics thus efficient use of supplied power 13 level output waveform at 3.3kV 3kV and 26 level at 6.66 kv, thus close to sinusoidal output Converts input AC to output AC without a DC bus, thus no capacitors-this vastly improves reliability and reduces size Improved Efficiency over existing designs; from 94 to 97+%. With thermal losses cut in half and with smaller physical footprint, there is less cost impact on control room HVAC

28 Matrix Converter How does it solve the issues? Upstream effects to power grid Downstream effects to electric motor, thus motor reliability Controller reliability Controller Size, weight, cost Controller efficiency Control room infrastructure costs Affect on motor cost Torque and Speed control performance of electric motor for the specific application Special motors not required; can be applied to existing motors (and cables) without addition of filters Fully regenerative to power line-full control of electric motor in all four quadrants of operation, without dynamic braking circuitry Precise torque control, even at zero speed without derating of the duty cycle of the power transistors Control of motor in velocity or torque mode

29 Matrix, the perfect electric valve? Matrix Architecture represents transformational technology, a long awaited advance in motor control design that enables complete control of electric motor speed and torque performance, without mistreating the power grid or the electric motor. As such when total cost of the motor control As such, when total cost of the motor control system is considered, Matrix technology will become the dominant design moving forward.

30 Thank you from Yaskawa and Atlas Copco JC Carter

31 Yaskawa Electric Corporation Founded: 1915 Sales: $4.0 billion Associates: 8,000 Headquarters: Kitakyushu, Fukuoka, Japan

32 Worldwide Locations United States New Berlin Chicago Portland Canada Toronto UK Glasgow West Carrollton Troy Columbus Sweden Torsas Germany Schwalbach Israel Tel Aviv Japan Yukuhashi Kokura Yahata Iruma China Beijing Shanghai Malaysia Kuala Lumpur Brazil Sao ~ Paulo

33 YEC Yaskawa Electric Corp. - Japan Established in s Motors & Controllers 1950 s Motors / Applications 1960 s Industrial Electronics 1970 s Industrial Automation 1980 s to Present Factory Automation & Mechatronics 4 Billion Dollars in sales worldwide Worlds Largest AC Drive Manufacturer

34 Power Quality Topics What are Harmonics? What is Harmonic Distortion? Differences between current and voltage distortion Possible effects of Harmonics Harmonics are important to understand the What Guidance is there in the relationship between Power Quality and switch Industry mode power supplies! What Solutions does Yaskawa Offer?

35 Definition iti of Harmonics Harmonics are defined as currents or voltages with frequencies that are integer multiples of the fundamental power frequency SIMPLY PUT - Harmonics are used to mathematically describe the shape of a curve that is not sinusoidal.

36 What is Harmonic Distortion? Harmonic Distortion is a mathematical way of describing how non-sinusoidal a wave shape appears Fourier Analysis - Sum of the Squares TVD = V 2 h h= z THD = 78.3% THD = 1.2% Every Wave shape has Harmonic Distortion!

37 Types of Harmonics DC Drive - SCR Based AC Drive - Diode Rectifier SCR Rectification - Line Notching, Increases Voltage Distortion Diode Rectification - Pulsed Current, Increases Current Distortion New Technology May Solve Old Power Quality Problems

38 Possible Effects of Harmonics Increased Transformer Heating recommended d K-Factor of 4 to 13 on new installations Increased Conductor Heating larger gauge wire run two wires in parallel l Electromagnetic Equipment PLCs - more sensitive to Voltage Notching PFTrue = PFTotal = Power Real / ( PowerRe al + Power Re act. + PowerHarmonics ) System resonance - Power Factor Correction Harmonic Distortion most likely will have no effect on Power Distribution Performance utilize input reactors to reduce likelihood f

39 How Harmonics Lower Efficiencyi Consider estimating power factor at the terminals of an AC Drive in a system with low source impedance (high available short circuit current) with no input line reactor or DC bus choke. True power factor is improved, when current distortion is limited by system impedance. (Including reactors, or bus chokes.) Figure Figure 39.1 Power Factor Considering 92.8% I THD pf = kw/kva I THD = 92.8% pf = 1/Sqrt( ) pf = 73.3% Figure 39.2 Power Factor Considering 32.6% I THD pf = kw/kva I THD = 32.6% pf = 1/Sqrt( ) pf = 95.08! Figure 39.2

40 Power Factor When Harmonics Exist From IEEE Std : Power is the product of inphase current times the voltage or: P 60 =V 60 *I 60 cos θ In the case of harmonics: P h = V h * I h cos θ or S = (Sqrt(P 2 + Q 2 +D 2 )) {R1] Where P = Real Power, Q = Reactive Power and D = Distortion Power. True Power Factor Representation - Expanded Q Reac ctive Power X (kvar r) P Real Power (kw) Figure 40.1 System losses will be higher due to the harmonic components, than with equivalent 60 kva. P h = I 2 h * R h

41 The Risk of Parallel Resonance H p - the harmonic order (per-unit frequency) at parallel resonant frequency MVA sc - the system short-circuit capacity MVAr c - the power factor improvement capacitor H p -Sqrt(MVA sc / MVAr c ) Power Factor Capacitors Relieve Load [R2] X X c L i h i h Per IEEE Red Book (Std ): 1993): If the SCR (short circuit ratio is less than 20), and there is a parallel resonance condition near a characteristic harmonic of the non-linear load, there will be a problem. Figure 41.1 Resonance occurs when: X c = X L Parallel Resonance Since all power systems have inductance and capacitance, they will resonate at a given frequency. When an exciting energy at that frequency, in a quantity that is large enough to offset the natural Current measured at the capacitor, showing 660Hz, (11th harmonic resonance) Figure 41.2

42 of Harmonic Mitigation Devices Figure 42.2 Assumptions: 10,000 installed base cost of 6- pulse drive. Values will vary for lower HP drives.

43 MTBF Ratings Calculating MTBF: Total Hours of Operation = 3,128,068 = 1,564,034 Hrs Number of failures 2 To put this in terms of years instead of hours, divide by 8760 hours/year: ~= MTBF= 1,564, ,760 Interpretation: if you had 178 drives running 24/7, you could expect one failure per year! 43 of 7