BInduction Motor Drive.docVIP

Ｂ　Induction Motor Drive 感应电机传动装置　　　　　　　　　　　　　　　　　　　　　　 The?speed?of?an?induction?motor?is?determined?by?the?synchronous speed?and?slip?of?the?motor.?The?synchronous?speed is related?to?the?supply?frequency?and?the?slip?can?be? controlled?by?the?regulation?of?voltage?or?curtent?supplied to the 1motor.?There?are?several?mechanisms?for?controuing the speed of?induction?motor.?These?are?:(1)variable-voltage? constant-frequency?or?stator?voltage?control,?(2)?variable-voltage?variable-frequency?control,?(3)?variable-c101ent?variable-frequency control,?and.?(4)?regulition?of?slip?power.?One?of?these viczrzabfe-fTieqz￠enry?colztTol,?is?described?as?follows. 感应电机的转速由电机的同步速和转差决定。同步速与电源频率有关，转差由供给电机的电压或电流调节控制。 为控制感应电机的转速，存在几个机理，它们是： (1) 变电压恒频率或定子电压控制 ，(2) 变电压变频率控制， (3) 变电流变频率控制，和 (4) 转差功率调节。这些方法之一，变电压变频率控制可被描述如下。 Square-Wave Inverter Drive 方波逆变器驱动 The?voltage-fed?inverters?(also?called?Voltage?Source?Inverters,?VSI)?are?generally?classified two?sqrware-wave?inve?rter?and?pulse-wi?dth?modulati?on?This?type?of?inverter?was?introduced?from?begiruting?nineteen-sixties?when?elegant?force-comnmtation?techniques?introduced.?were?introduced.Fig.1-6B-1showstheonventional?power?circuit?of?a?square-wave?inverter?drive.?A?three-phase?bridge?rectifier?convens?AC?to?variable-voltage?DC,?which?is?impressed?at?the?input?of?a?force-commutated?bridge?inverter.?The?inverter?generates?a?variable-voltage?variable-frequency?power?supply?to?control?the?speed?of the?motor.?The?inverter?is?called?voltage-fed?because?a?large?filter?capacitor?provides?a?stiff?voltage?supply?to?the?inverter?and?the?inverter?output?voltage?waves?are?not?affected?by?the?nature-of?the?load.?Nomnally,?each?thyristor?of?an?inverterleg?conducts?for?180°to generate a? square-wave?;?voltage?at?the?machine?phase?with?respect to the?fictitious?center?point?of?the?DC?supply.The?line to? line?voltage?can?be?shown?to?be?a six-stepped wave as shown in The figure.?Since?the?induction,?motor,constitutes?a lagg