Microwave Generator Technology for the 21 st Century Microwave Heating & Processing of Materials Seminar Paul Burleigh Overview History Applications Generation technology Need for improvement New markets Issues arising from scale Solution Concept Development models Initial product Next steps Benefits Summary Slide 2 Microwave Processing - Applications An expensive form of power! Used to: Deliver transformational economics Enabling Rubber vulcanisation Butter tempering Bacon cooking Artificial diamond Slide 3 1
896 / 915 / 922MHz Up to 100kW 88 90% conversion efficiency 50Hz operation High stored energy (in transformer core) leads to magnetron damage Not compliant to utility regulations above 100kW Unsuitable to large scale (MW) processing Slide 4 Pedigree and Emerging Markets e2v has a 40 year history in industrial RF & microwave processing. Originally the designer of the 900MHz CW magnetron, e2v is now a major supplier of vacuum electron tubes into professional applications. Emerging markets in Mineral processing Food processing Oil and gas exploration Oils and gas production Oil refining Polymer chemistry Pharmaceuticals Slide 5 Emerging Market Drivers Throughput Operational flexibility Infrastructure reduction Energy efficiency Slide 6 2
T 0 T 1 T 2 T 3 T 4 T 5 T 0+ 1 Duty 100% Pulses blend into each other one pulses of 120 o per half cycle Duty 66% two pulses per half cycle each of 40 o Duty 33% two pulses per half cycle each of 20 o 0 60 o 120o 180o 240o 300o 360o Machine Bridge P1-P2 output waveform P2-P3 ad P3-P1 shifted 120 o and 240 o respectively Emerging Market Requirements Use destined to be at heart of major process plant Comminution plant Oil rig Well head Refinery Chemical plant. Arising issues: Operation will be critical to continued process output Must deliver very high reliability High levels of up-time and often difficult site accessibility for maintenance Must be effectively supported Equipment must comply to Utility Regulations (grid supply) A large power cluster will become the sites major power usage - so will be seen by utility supplier Slide 7 Solution: Inverter Driven Magnetron PSU Basic idea is to operate magnetron directly with rectified, unsmoothed pulses Builds on the way domestic ovens work Not CW but pulsed as use ½ wave rectified mains Ch1 Cathode voltage 1kV/Div Ch4 Cathode current 0.5A/Div Ch2 Transformer output voltage Slide 8 Proof of Principle Demonstrator Basis of Control DC level sets the peak voltage hence the magnetron peak power 220V 50Hz Mains Supply Mains Supply Interface and Relays Boost DC Converter Link Heater Relay T2 s T2 p and softstart Microwave Oven Blocking Capacitors ~ _ T1 p T1 s ~ P1 6 arm Magnetron 3 phase Bridge P2 ~ + P3 TRU BR1 Module Pulse duty cycle sets the average power input to the magnetron fixed pulse frequency, variable pulse width 2f Sync Drive Set Boost Decode & Reference Protection Current Overload R1 Computer Interface DSP Module with Optical Interface Figure 2 Slide 9 3
Proof of Principle Demonstrator - Front Slide 10 Proof of Principle Demonstrator Top View 6 Switch Bridge 3-Phase TRU DSP with optical interface Front End Boost Converter Slide 11 Proof of Principle Demonstrator - Waveforms Ch 1 magnetron current 0.2A/div Ch2 Magnetron voltage 1kV/div Ch3 Vp1 to Vp2 Ch4 Integral of Ch3.. and it warms the coffee Slide 12 4
High Power Prototype Based around Converteam mains & machine bridge combination operating at 2.5kHz; uses patented custom software Magnetron unit includes: High voltage transformer rectifier Digitally controlled heater PSU Digitally controlled solenoid PSU PLC controller with touch screen user interface Services (electrical distribution, water & air cooling) Slide 13 High Power Prototype 100kW Output Slide 14 High Power Prototype Mains and machine bridge combination Slide 15 5
HVTRU Assembly Weight: 250kg c.f. 50Hz system: 1300kg Air cooled Modular construction 75 single layer toroids 5 PCB rectifier assemblies Integrated over voltage and over current circuits Slide 16 Heater Supply Weight only 3kg c.f. 50Hz system: 100kg Output: 120A at 12V 25kV isolation Synchronous rectifier with choke smoothing for DC output High frequency SMPS actively monitoring heater resistance to deliver optimal magnetron stability Slide 17 Operating Waveforms 90kW output Ch1 Heater inverter primary current (5A/div) Ch2 Magnetron current (2A/div) Ch3 Magnetron voltage (5kV/div) Slide 18 6
Initial Product 100kW Microwave output IP55 rated Fully compliant to relevant standards including EMC emissions Slide 19 Technology Scalability to High Powers Exploit motor drive capability to operate multiple magnetrons for higher powers; Magnetron 1 Magnetron 2 Mains & Machine Bridge Magnetron 3 Magnetron 4 Magnetron 5 Magnetron 6 Power rating determined by rating of bridges and number of magnetrons operating Slide 20 Scaling Economics Single front-end and multiple magnetron units underpins favourable cost curve: Makes the technology the natural & economic choice for high power applications Slide 21 7
Summary New high power applications for microwave power are emerging Traditional 50Hz systems will struggle to satisfy these Compliance issues Inadequate reliability Inadequate supply chain Inadequate support A new modern scalable solution exists Compliant at all levels Credible supply chain Globally supported New technology & supply chain removes major barrier to growth or new applications. Slide 22 8