Load Commutated Chopper Circuit: In this method of Load Commutated Chopper Circuit, the load current flowing through the thyristor is made to become zero while the motor current is conducted by the free-wheeling diode. Figure 10.36(a) shows the circuit of a Load Commutated Chopper. The thyristor pairs Th1Th2 and Th3Th4 alternatively conduct the load current. …
Current Commutated Chopper Circuit: Figure 11.34 shows a Current Commutated Chopper Circuit. The main thyristor Th1 of the chopper is commutated by a current pulse generated in the commutation circuitry. The sequence of operation is given below, and various significant waveforms are shown in Fig. 11.35. It is to be noted that this charging of …
Voltage Commutated Chopper Circuit: This Voltage Commutated Chopper Circuit comprises an auxiliary thyristor Th2, a diode D, inductor L and capacitor C as shown in Fig. 11.32 wherein the total chopper circuitry has been outlined with a dotted box. To start the Voltage Commutated Chopper Circuit, capacitor C is initially charged by firing the thyristor …
What is TRIAC? | Symbolic Representation | VI Characteristics of TRIAC: What is TRIAC? – The full form of TRIAC is Triode for Alternating Current (TRIAC) or Triode for AC. It is a bilateral switch with three terminals—anode, cathode and a single gate. It conducts in either direction being equivalent to two SCRs connected in …
Vector Control of Induction Motor: The sole idea behind the vector control of induction motor is to have an electrical drive which must offer superior performance than widely used separately excited dc motor in industry. Further such a drive should also emerge as a robust, reliable, maintenance free and cheaper alternative of dc drive. Few …
Types of Forced Commutation: It was observed from the discussion on choppers and inverters that in thyristor systems fed from dc supply, the forward current does not pass through zero naturally and must therefore be forced to become zero at appropriate instants by means of auxiliary circuitry, called the commutation circuit. Apart from forcing the …
What is Sinusoidal Pulse Width Modulation?: In Sinusoidal Pulse Width Modulation the pulse-width instead of being uniform as in the waveform of Fig. 11.55 is a sinusoidal function of its angular position with respect to a reference sine wave resulting in a reduction in the harmonic content. The control function consists of a sinusoidal wave …
What is PWM Inverter?: What is PWM Inverter? – In presenting the arguments here attention will be focused on a single-phase inverter. Instead of the single rectangular pulse output of Figs 11.46 and 11.48 during each half-cycle, a commutation circuitry can be devised to produce a series of short duration pulses as output in each …
Voltage and Harmonic Control of Inverters: Voltage and Harmonic Control of Inverters – In applying Inverters for motor control both V and f (keeping V/f constant) need to be varied. Further, the inverters apply essentially nonsinusoidal ac voltage to the motor. External filter circuits cannot be employed due to the difficulty in operating inverters over …
Three Phase Bridge Inverter | Working Principle: The basic three phase bridge inverter is a six-step inverter. A step is defined as a change in the firing sequence. A 3-phase thyristor bridge-inverter is shown in Fig. 11.49. Th1 to Th6 are the six load-carrying thyristors while D1 to D6 are the free-wheeling diodes. Each pair …
