TUTORIAL Electric Mchine Modeling October 206
Electric Mchine Modeling One cn crete electric chine odels using the bsic unction blocks in PSIM. In this tutoril, we will illustrte how to crete the odel or dc chine. Creting the odel involves the ollowing steps: Derive the electricl nd echnicl equtions o the chine; Iplent the electricl equivlent circuits o the equtions in PSIM; nd Pckge the circuit in the or o subcircuit.. Deriving the Equtions The electricl nd echnicl equtions o dc chine cn be derived s ollows: v t E v i R di L d R L E T d k k i T where v t, v, i, nd i re the rture nd ield voltges nd currents; R, L, R, nd L re the rture nd ield winding resistnces nd inductnces; E is the bck ; is the oent o inerti, is the echnicl speed; is the ield lux; nd T nd T L re the developed torque nd lod torque, respectively. I the gnetic sturtion is neglected, the bck nd the developed torque cn lso be expressed s: E T L L where L is the utul inductnce between the rture nd the ield windings. It cn be clculted bsed on the rted operting conditions s: 2. Iplenting the Equivlent Circuits L i T i i I R I Once the equtions re obtined, they cn be represented nd iplented in the or o equivlent circuits. For exple, the rture winding eqution (Eqn. ()) cn be represented by resistor R, in series with n inductor L nd controlled voltge source E. The ield winding eqution cn be represented in siilr wy. The echnicl eqution, Eqn. (5), cn be represented by either n inductor in series with two voltge sources, or cpcitor in prllel with two current sources. In PSIM, the cpcitor L () (2) (3) (4) (5) (6) (7) (8) 2
Electric Mchine Modeling convention is used to iplent echnicl equtions. Eqn. (), (2), nd (5), thereore, cn be represented by the equivlent circuits s shown below: i Eqn () Eqn (5) i W R L E T W i k=l k=l TL Eqn (2) V R L The equivlent circuit consists o three prts, with ech prt representing one o the equtions. Current controlled voltge sources re used to obtin the rture current i nd the ield current i. Nonliner voltge sources with ultipliction re used to represent the bck E nd the developed torque T. For the circuit representing Eqn. (5), torques re represented by currents, the echnicl speed is represented by the node to ground voltge, nd the oent o inerti is represented by cpcitnce. Lbels re used insted o physicl wires in the circuit or better lyout. Note tht the lod torque T L, represented by current source, coes ro outside the chine, nd is not prt o the dc chine odel itsel. 3. Pckging the Model in Subcircuit The circuit tht represents the dc chine cn be pckged in the or o subcircuit or esy use nd preter speciction. This involves the ollowing steps: Deine the subcircuit size; Plce the interce ports; nd Crete nd edit the subcircuit ige, necessry. 3
Electric Mchine Modeling The subcircuit size is the size o the subcircuit block s it ppers in the in circuit. It is set by selecting Subcircuit > Set Size in PSIM. The size should be lrge enough to llow the proper plcent o the interce ports. In this circuit, we set the subcircuit size with the wih o 6 nd the height o 6. Once the subcircuit size is set, the next step is to plce the interce ports. Interce ports re ports tht interce with externl circuits. In this exple, there will be two interce ports or rture winding terinls, two interce ports or ield winding terinls, nd one interce port or the echnicl sht. To plce n interce port, go to Subcircuit > Plce Bi directionl Port in PSIM. In PSIM, the echnicl sht o n electricl chine only connects to nother echnicl sht or other echnicl elents. In order to connect the echnicl equivlent circuit o the odel to other echnicl shts or elents, n Electricl Mechnicl Interce block needs to be connected to the speed node, with the electricl side o the interce block connected to the speed node nd the echnicl side o the interce block connected to n interce port. The circuit looks like the ollowing ter the ports re plced. i i R L E k=l k=l T W i W sht E M lg_ster_slve V R L Furtherore, the preters in the odel will be deined s vribles nd will be specied t the in circuit level. In the circuit, deine the rture/ield winding resistnces nd inductnces s R, L, R, nd L, the cpcitnce representing the oent o inerti s, nd the gin o the sources or E nd T s L. Then, in PSIM, go to Subcircuit > Edit Deult Vrible List, nd dd the vribles nd the deult vlues to the list. The dilog window o the deult vrible list is shown below ter the vribles re dded: 4
Electric Mchine Modeling Finlly, the subcircuit ige cn be odied or edited by going to Subcircuit > Edit Ige. Use the utility tools to crete the desired ige. The igure below shows n ige creted or the dc chine odel. 5