This application note proposes a time optimized algorithm for three-phase induction drive control by the Siemens microcontroller C504. Three sinewave phase currents can easily be generated and controlled by the on-chip Capture Compare Unit (CCU), requiring very few CPU computing time (about 30% at 20 kHz PWM frequency in open-loop mode). 1 Introduction .....3 2 Fundamentals of Operating4 2.1 Controlling Three-Phase Induction Motors 4 2.2 Generating Variable Motor Currents by Using Pulse Width Modulation (PWM).5 2.3 Power Amplification of Controller Output Signals by Semiconductor Bridges 6 2.4 Sinusoidal Weighted PWM ...7 2.5 Half Bridge Driving with Dead Time Control .8 2.6 Principle of Generating Sinusoidal Weighted PWM Signals with the C504....9 3 Hardware Description .11 3.1 Three-Phase Motor ...11 3.2 Motor Interface 12 3.3 Open Loop Motor Control....13 4 C504 Controller Software Description..14 4.1 Calculation of Period- and Offset-Values for Compare Timer 114 4.2 Considerations concerning the Resolution for the Sine Table Pointers14 4.3 Changing the Amplitude without using any Multiplication-Instruction .17 4.4 Generating the Memory Sine Tables .20 4.5 Compare Timer 1 Interrupt Service Routine Tasks.22 4.6 Main Program Task...23 4.7 Flow-Charts.....24 4.8 Conclusion 29