Controlled-Rectifier Fed Drive Armature Field ECE 442 Power Electronics
Chopper-Fed Drive Armature Field ECE 442 Power Electronics
Equivalent Circuit of a Separately-Excited DC Motor ECE 442 Power Electronics
ECE 442 Power Electronics
ECE 442 Power Electronics
Solve for the motor speed ECE 442 Power Electronics
Control of the motor speed Control armature voltage, Va Voltage control Control the field current, If Current control Control the armature current, Ia ECE 442 Power Electronics
Magnetization Characteristic ECE 442 Power Electronics
Characteristics of Separately-Excited Motors Use armature voltage control Use field-current control Rated speed ECE 442 Power Electronics
Equivalent circuit of a DC Series Motor ECE 442 Power Electronics
ECE 442 Power Electronics
Controlling the Motor Speed Control the armature voltage, Va Control the armature current, Ia ECE 442 Power Electronics
Characteristics of DC Series motors ECE 442 Power Electronics
Operating Modes In variable-speed applications, a dc motor may be operating in one or more of the following “Modes” Motoring Regenerative braking Dynamic braking Plugging ECE 442 Power Electronics
Motoring Mode “Back emf”, Eg is < supply voltage Va Both Ia and If are positive Developed torque meets load demand ECE 442 Power Electronics
Regenerative Braking Mode Motor acts as a Generator Eg becomes > supply Voltage Va Ia becomes negative Kinetic energy of the motor is returned to the supply ECE 442 Power Electronics
Dynamic Braking Replace the supply voltage with a resistor Power dissipated in the resistor rather than given back to the source ECE 442 Power Electronics
Plugging Reverse the armature terminals while running Va and Eg act in the same direction Ia is reversed, producing “braking” torque ECE 442 Power Electronics
Four-Quadrant Operation ECE 442 Power Electronics
Single-Phase DC Drive Change Va by changing firing angle Inductor Lm is a “smoothing” Inductor to prevent discontinuous current ECE 442 Power Electronics
Armature Reversal ECE 442 Power Electronics
Field Reversal ECE 442 Power Electronics
Single-Phase Half-Wave Converter Drive ECE 442 Power Electronics
Quadrant of Operation ECE 442 Power Electronics
Waveform Summary ECE 442 Power Electronics
Single-Phase Semiconverter Drives ECE 442 Power Electronics
Quadrant(s) of Operation Semiconverter – one quadrant converter One polarity of output voltage and current ECE 442 Power Electronics
Waveform Summary ECE 442 Power Electronics
Single-Phase Full-Converter Drives ECE 442 Power Electronics
Quadrant(s) of Operation Full converter – two quadrant converter Output voltage polarity can be positive or negative Output current has one polarity ECE 442 Power Electronics
Waveform Summary ECE 442 Power Electronics
Single-Phase Dual-Converter Drives Dual converter can operate in all four quadrants Output voltage and current can be positive or negative ECE 442 Power Electronics