Inverter Current source

Voltage source inverter (VSl) using IGBTs 6/125 Current source inverter (CSl) 6/126 Cyclo converters (frequency converters) 6/127 The regenerative schemes 6/127... 

The inverter may be a current source inverter, rather than a voltage source inverter (.Section 6.9.4) since it will be the rotor current that is required to be vtiried (equation (1.7)) to control the speed of a wound rotor motor, and this can be independently varied through the control of the rotor current. The speed and torque of the motor can be smoothly and steplessly controlled by this method, without any power loss. Figures 6.47 and 6.48 illustrate a typical slip recovery system and its control scheme, respectively. 

The inverters are either voltage source or current source (see Figure 7-7a and b). There are other variations, but they apply to drivers smaller than the ones used with compressors. However, pulse-width-modulated (PWM) (see Figure 7-7c), transistorized units are less complicated and are relatively maintenance-free with reliable units available to at least 500 hp. For all but the smaller compressors, the current source inverter is the one typically used. With a six-step voltage source, a rule of thumb has been to size the motor at two-thirds of its rating so as not to exceed the insulation temperature rise. For current source motors, the output torque is not constant with decreased speed, which fortunately is compatible with most compressors, as torque tends to follow speed. For current source drives, one needs to upsize the motor captive transformer by approximately 15% to account for harmonic heating effects. 

Figure 7-9. Schematic of the rectifier and inverter circuit for a current source inverter.

Table 15.6. Harmonic rms currents and voltages in a star-wound induction motor that is fed from a current source inverter...

B. C. Ghosh and S.N. Bhadra. Bond graph simulation of a current source inverter driven induction motor (csi-im) system. Electric Machines and Power Systems, 21(l) 51-67, 1993. B. Umesh Rai and L. Umanand. Bond graph model of doubly fed three phase induction motor using the axis rotator element for frame transformation. Simulation Modelling Practice and... 

Introduction Voltage-Source Inverters Current-Source Inverters (CSI) Voltage Control in Inverters Harmonic Reduction Three-Phase Inverters... 

Inverters can be broadly classified as (1) voltage-source inverters (VSI), and (2) current-source inverters (CSI). 

FIGURE 10.69 A current-source inverter (a) circuit diagram, (b) load circuit usedacrossAandB forparallel resonant inverter, (c) typical operating waveforms. 

FIGURE 10.70 A single-phase current-source inverter using thyristors. 

Current source inverters Inverters having a constant DC current input. 

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