Dspmicroprocessor flexible lower bandwidth compared

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DSP/microprocessor – flexible, lower bandwidth compared to the digital circuit. DSPs perform faster operation than microprocessors (multiplication in a single cycle). With a DSP/microprocessor, complex estimations and observers can be easily implemented. Inverter (PWM) control DC-DC converter control Inverter (six-step) control DC-DC Converter control Controlled Rectifier control Inverter (six-step) control Diode Rectifier control Inverter (PWM) Matrix Converter control DC DC AC DC AC DC DC AC DC AC AC DC AC AC AC
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5 Most of the time, the control unit has to be electrically isolated from the power converters using opto-coupler or pulse transformers, for the following reasons: Malfunction in power circuit may damage control circuit if no electrical isolation is present. Safety for the operator – the high voltage and/or high current faulty condition in the power circuit can be conducted to the control circuit normally maintained by an operator/user Avoid conduction of harmonic to control circuit. Power electronic converters generate harmonics that can conduct to the control circuit thus interfering with its operation. d) Source Electrical sources or power supplies provide the energy to the electrical motors. Power sources can be of AC or DC in nature and normally are uncontrollable, i.e. their magnitudes and frequencies are either fixed or varying, depending on the sources of energy such as battery, power utility, fuel cell, etc. Fixed frequency and fixed magnitude AC source is normally obtained from power utility and can be either three-phase or single-phase; 3-phase sources are normally for high power applications. In order to efficiently control the motor, regardless of whether it is a DC or AC source (and depending on the type of the motor), it has to be regulated using power electronics converters before being fed to the motor. Power electronics converters typically have poor input power factor and it is sometimes necessary for the power converters to be operated with high power factor; if this is needed, power factor correction circuit has to be introduced. e) Sensors Sensors for voltage, current, speed or torque are required for closed-loop operation and protections in electrical drive systems. Signals from these sensors have to be isolated from the control unit for the same reasons as explained before. Electrical isolation in voltage and current sensors are obtained using, for example, Hall-ffect sensors/devices. For high performance drive system, the speed is obtained from high-resolution speed encoders or resolvers. The terms ‘sensorless drive’ is normally referred to a drive system that does not need a mechanical speed sensor but rather the speed is estimated using motor terminal variables i.e. voltages and currents.
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  • Fall '16
  • Idris
  • Electric motor

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