Power Electronics for Active Magnetic Bearings Introduction Electromag nets + Mechanics Power Circuits Displacement Sensors ConditionersA/D converter D/A converterController Reference Digital Control Introduction Power Electronics Applications Compressor Gas Turbine Motor Turboexpander Offshore AMB axis control total : 6 freedom degrees machine torque control AMB control system Analog Circuits R = resistor, L = inductance, C = capacitor. Transistors operating in the active mode. I amb = K * I b1 Analog Circuits Push Pull circuit: Vpos= V+ Vneg= V- Bipolar Output Currents Analog Circuits Improved Push Pull circuit: Vpos= V+ Vneg= V- Bipolar Output Currents Analog Circuits Operational Amplifiers Vout = Gain * [(+v) (-v)] Ideal Gain = infinite Input Impedance = infinite Using auxiliary passive components, different transfer functions can be implemented, by instance: Kp, Kp(1 + Td*s), Kp(1+Ti/s), Analog Circuits Digital Circuits Combinational circuits: logical gates, encoders, multiplexers, etc Sequential circuits: flip-flops, counters, memories, etc Hybrid circuits: Analog-Digital converter Digital-Analog converter Power Circuits Linear Type: Use of opamps and power transistors: BJT,Mosfet,IGBT Switched Type: two states of operation: on (short) and off (open) Switched Power Circuits To be continued Application in compressors HP=High pressure, LP=Low pressure