Nowadays, hybrid/full electric vehicles are of great interest in the automotive industry because of their low carbon-dioxide missions. Unlike conventional vehicles, they include an electrical drive system as an alternative to the traditional internal-combustion engine. Vehicle electrification involves the use of inverters with fast-switching power electronics devices, operated at their physically maximum slew rate to: a) reduce current ripple for low inductance motors, b) enable use of smaller DC bus capacitors, c) reduce acustic noise. Such high slew rates result in conducted electromagnetic emissions in a broad frequency range extending up to 100 MHz. Noise propagates along cables, from the inverter (in the front compartment) toward the battery (in the rear compartment) along the high-voltage DC power bus of the vehicle. Although shielded cables are used to reduce interference effects, such a conducted electromagnetic noise can efficiently couple susceptible circuits through crosstalk, or it can turn into radiated emissions. Finally, as a consequence of field-to-wire coupling effects, radiated emissions may imply radiated-immunity problems to signal interconnects in the relatively small volume of a car, having densely-packed arrangement of power/signal equipment. Therefore, assessment of electromagnetic compatibility in hybrid and full electric vehicles is an issue of greater and greater concern for the automotive industry. The availability of models to predict CE propagation in long HV DC power bus is a key ingredient for the integration of new electrical drive systems with data-handling subsystems. In this work, an accurate circuit model of the electrical power system is developed and implemented in a SPICE simulation environment. All the components of the electrical drive system (battery, inverter, permanent-magnet synchronous motor, and the shielded cables involved in the DC and AC power buses) are modeled to correctly represent both the functional (i.e., low frequency) aspects and the high-frequency behavior determined by parasitic effects. Concerning subsystem parts devoted to represent the battery, the inverter, and the motor, suitable circuit models are selected from the state-of-the-art inferred from the recent technical literature, and are modified ed and optimized to meet the aims of the proposed work. Concerning models of the DC and AC power buses, involving shielded cables, a distributed-parameter circuit model bases on transmission-line theory is entirely developed and validated here by comparison with measurements performed in an ad-hoc test setup. The model has been implemented in Cadence PSPICE and used to investigate the role played by circuit topology, high-frequency parasitics, and the operating point of the motor in the generation of conducted emissions.
Negli ultimi anni i veicoli elettrici hanno destato notevole interesse nel settore automobilistico grazie alle basse emissioni di anidride carbonica, infatti, differiscono dai veicoli convenzionali poiché possiedono un sistema di trazione elettrico in alternativa al tradizionale motore a combustione interna. La crescente elettrificazione dei veicoli prevede l'utilizzo di inverter, al cui interno si trovano dispositivi elettronici (di potenza) a rapida commutazione, i quali, vengono impiegati alla loro massima frequenza per: a) ridurre le oscillazioni di corrente per motori a bassa induttanza, b) consentire l'utilizzo di condensatori di capacità minore ai morsetti di ingresso dell'inverter, c) ridurre il rumore acustico. Queste elevate frequenze di commutazione producono emissioni elettromagnetiche condotte in un'ampia gamma di frequenze che si estende no a 100 MHz, da cui ne conseguono disturbi elettromagnetici che si propagano lungo i cavi, dall'inverter (nello scomparto anteriore)verso la batteria (nel vano posteriore), ovvero, si propagano sulla linea di alimentazione DC che attraversa l'intero veicolo. Sebbene vengano impiegati dei cavi schermati per ridurre gli e etti di interferenza, i disturbi elettromagnetici condotti possono trasferirsi su circuiti adiacenti tramite diafonia, oppure possono trasformarsi in emissioni radiate. Queste, tramite accoppiamento tra campi elettromagnetici e cablaggi possono implicare problemi di immunità radiata per circuiti di segnale, poichè sia i circuiti di potenza che i circuiti di segnale sono, per necessità, distribuiti insieme nel volume relativamente piccolo del veicolo. L'analisi della compatibilità elettromagnetica dei veicoli ibridi ed elettrici è quindi un problema di interesse sempre maggiore per l'industria automobilistica. La creazione di modelli per prevedere la propagazione delle emissioni condotte lungo la linea di alimentazione in alta tensione (continua), è un elemento fondamentale per l'integrazione di nuovi sistemi di azionamento elettrici che presentano sottosistemi di gestione dati. In questo lavoro, un modello accurato del sistema di trazione elettrico è stato sviluppato e implementato in un ambiente di simulazione SPICE, dove tutti i componenti (batteria, inverter, motore sincrono a magneti permanenti ed i cavi schermati di alimentazione sia sul lato in corrente continua che sul lato in corrente alternata) sono stati modellizati per rappresentare al meglio entrambi gli aspetti, ovvero, quello funzionale (cioè in bassa frequenza) e quello in alta frequenza, determinato da eff etti parassiti. Per quanto riguarda i sottosistemi rappresentanti la batteria, l'inverter ed il motore, i modelli circuitali sono stati dedotti dalla recente letteratura tecnica e sono stati quindi modificati ed ottimizzati per soddisfare gli obiettivi del lavoro proposto. Per quanto riguarda i modelli delle linee di trasmissione (di potenza) in continua ed in alternata, che coinvolgono cavi schermati, modelli di circuito a parametri distribuiti (basati sulla teoria della linea di trasmissione) sono stati sviluppati e convalidati tramite confronto con misure effettuate durante prove di laboratorio svolte a regola d'arte. Il modello è stato implementato nel programma Cadence PSPICE ed utilizzato per studiare il ruolo svolto dalla topologia circuitale, dai parassitismi in alta frequenza, e dalle condizioni di funzionamento del motore nella generazione di emissioni condotte.
A spice model for conducted emission analysis in electric vehicles
BELTRAMELLI, ALESSANDRO
2013/2014
Abstract
Nowadays, hybrid/full electric vehicles are of great interest in the automotive industry because of their low carbon-dioxide missions. Unlike conventional vehicles, they include an electrical drive system as an alternative to the traditional internal-combustion engine. Vehicle electrification involves the use of inverters with fast-switching power electronics devices, operated at their physically maximum slew rate to: a) reduce current ripple for low inductance motors, b) enable use of smaller DC bus capacitors, c) reduce acustic noise. Such high slew rates result in conducted electromagnetic emissions in a broad frequency range extending up to 100 MHz. Noise propagates along cables, from the inverter (in the front compartment) toward the battery (in the rear compartment) along the high-voltage DC power bus of the vehicle. Although shielded cables are used to reduce interference effects, such a conducted electromagnetic noise can efficiently couple susceptible circuits through crosstalk, or it can turn into radiated emissions. Finally, as a consequence of field-to-wire coupling effects, radiated emissions may imply radiated-immunity problems to signal interconnects in the relatively small volume of a car, having densely-packed arrangement of power/signal equipment. Therefore, assessment of electromagnetic compatibility in hybrid and full electric vehicles is an issue of greater and greater concern for the automotive industry. The availability of models to predict CE propagation in long HV DC power bus is a key ingredient for the integration of new electrical drive systems with data-handling subsystems. In this work, an accurate circuit model of the electrical power system is developed and implemented in a SPICE simulation environment. All the components of the electrical drive system (battery, inverter, permanent-magnet synchronous motor, and the shielded cables involved in the DC and AC power buses) are modeled to correctly represent both the functional (i.e., low frequency) aspects and the high-frequency behavior determined by parasitic effects. Concerning subsystem parts devoted to represent the battery, the inverter, and the motor, suitable circuit models are selected from the state-of-the-art inferred from the recent technical literature, and are modified ed and optimized to meet the aims of the proposed work. Concerning models of the DC and AC power buses, involving shielded cables, a distributed-parameter circuit model bases on transmission-line theory is entirely developed and validated here by comparison with measurements performed in an ad-hoc test setup. The model has been implemented in Cadence PSPICE and used to investigate the role played by circuit topology, high-frequency parasitics, and the operating point of the motor in the generation of conducted emissions.| File | Dimensione | Formato | |
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2014_07_Beltramelli.pdf
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https://hdl.handle.net/10589/94481