3.1Introduction1 The role of dc-ac Inverters :To convert DC energy sources into AC energy sources.2Applications:Asapartofcompositeconverter（组合变换器）V AC-DC-AC freguency converter (变频器) (forAC motor drive)V AC-DC-AC constant-voltage constant-freguency converter(恒循频变换器(foruninterruptibleac power supplies)V AC-DC-AC Converters for induction heatingV AC-DC-AC-DC switching power supplies
3.1 Introduction 1 The role of dc-ac Inverters : To convert DC energy sources into AC energy sources. 2 Applications: As a part of composite converter (组合变换器) ✓AC-DC-AC frequency converter (变频器) (forAC motor drive) ✓AC-DC-AC constant-voltage constant-frequency converter (恒 压恒频变换器) (for uninterruptible ac power supplies) ✓ AC-DC-AC Converters for induction heating ✓ AC-DC-AC-DC switching power supplies
An example: ac motor driveLineACacmotorDiodeFilterSwitch-modecapacitorinverterrectifierThe powerflow is unidirectional.The energy recovered during the braking of the acmotor can be dissipated in a resistor
An example: ac motor drive The power flow is unidirectional. The energy recovered during the braking of the ac motor can be dissipated in a resistor. LineAC ac motor + Vd - Diode rectifier Filter capacitor Switch-mode inverter
In applications where the braking is performed frequently, abetteralternativeregenerativebraking(再生制动、回馈制动)The energy recovered during the braking of the ac motor isfed back to the utility gridLineACacmotorFilterSwitch-modeSwitch-moderectifiercapacitorinverterA detailed discussion of switch-mode rectifieris deferred toChapter 18. In this Chapter, we will discuss inverters.especially voltage source inverters (VSl)
In applications where the braking is performed frequently, a better alternative regenerative braking(再生制动、回馈制动). The energy recovered during the braking of the ac motor is fed back to the utility grid. LineAC ac motor + Vd - Switch-mode rectifier Filter capacitor Switch-mode inverter A detailed discussion of switch-mode rectifier is deferred to Chapter 18. In this Chapter, we will discuss inverters, especially voltage source inverters (VSI)
3ClassificationofInverters(1) Yoltage Source Inverter (VSl) (discussed in this Chapter本D3本D,木D·DC side is constant voltage, low impedance (voltagesource, or bulk cap)·AC side voltage is square wave or quasi-square wave.· AC side current is determined by the load·Anti-parallel diodes are necessary toprovide energyErfeengh.ckp.ath (freewheeling diodes , feedback diodes)
3 Classification of Inverters ☆ (1) Voltage Source Inverter (VSI) (discussed in this Chapter) + - •DC side is constant voltage, low impedance (voltage source, or bulk cap) • AC side voltage is square wave or quasi-square wave. • AC side current is determined by the load. • Anti-parallel diodes are necessary to provide energy E-mailf : exjehuda bnga@cb kjtu.pedau t .c hn . (freewheeling diodes , feedback diodes) C R Ud T1 T2 T3 T4 D1 D2 D3 D4 uo io L
L3(2) Current Source Inverter (CSl)YYY13(discussed in Chapter 14 and 15)VT,VT.CRRLVTu.·DC side is constant current, high impedance (currentsource, or large inductor)·AC side current is quasi-square wave.·AC side voltage is determined by the load·No anti-parallel diodes are needed. sometimes seriesdiodes are needed to block reverse voltage for otherpower semiconductor devices
(2) Current Source Inverter (CSI) (discussed in Chapter 14 and 15) •DC side is constant current, high impedance (current source, or large inductor) • AC side current is quasi-square wave. • AC side voltage is determined by the load. •No anti-parallel diodes are needed. sometimes series diodes are needed to block reverse voltage for other power semiconductor devices