Application of Soft Switching Technology in Inverter and Its Influence on Electromagnetic Interference
This paper analyzes the electromagnetic interference (EMI) source and spread path of traditional PWM inverter. To reduce the EMI it puts forward a new soft switching PWM inverter, and expounds the inverter’s working principle. It applies soft switching te
- PDF / 465,308 Bytes
- 7 Pages / 439.37 x 666.142 pts Page_size
- 98 Downloads / 176 Views
Abstract This paper analyzes the electromagnetic interference (EMI) source and spread path of traditional PWM inverter. To reduce the EMI it puts forward a new soft switching PWM inverter, and expounds the inverter’s working principle. It applies soft switching technology to traditional inverter. It measures the turn-on voltage spike and the EMI conductive noise of AC inverter system through experiment. It also analyzes and compares under hard switching condition and soft switching condition respectively. It proves that soft switching inverter can reduce EMI effectively. Keywords Soft switching • Inverter • EMI • Noise spectrum
1 Introduction At present, switching frequency of the traditional PWM inverter becomes higher and higher. The higher frequency makes inverter output more pulses during per period, so the equivalent voltage wave closes to sine wave much more. Then it can reduce harmonic output and improve speed regulation performance. However, the traditional inverter runs under hard switching condition, namely the switches of inverter turn on and turn off under non-zero voltage switching (NZVS) condition or non-zero current switching (NZCS) condition. It causes problems such as switching loss, diode reverse recovery, inductive turn-off, capacitive turn-on and electromagnetic interference (EMI) [1]. When the inverter is working, it causes EMI to other devices, which get more severe with higher
Y. Yang (*) • H. Gao • X. Wang • J. Tang Navy Submarine Academy, Qingdao, China e-mail: [email protected] J. Li • Y. Tian Military Delegate Office of 8357 Research Institute, Tianjin, China W. Wang (ed.), Mechatronics and Automatic Control Systems, Lecture Notes in Electrical Engineering 237, DOI 10.1007/978-3-319-01273-5_59, © Springer International Publishing Switzerland 2014
533
534
Y. Yang et al.
frequency. It involves mighty conductive EMI caused by high du/dt and di/dt of power devices. It also causes great electromagnetic radiation, which can cause mistake to itself and EMI to other equipments and affect their performance.
2 Electromagnetic Interference Source and Spread Route of PWM Inverter In motor drive system high du/dt and di/dt occur with performance of power device because of PWM modulation. Harmonic waves of the voltage and current range from several kHz to hundreds of MHz. These high frequency factors shape leaking current through parasitical capacity and common impedance and produce conductive EMI. There are two spread routes of leaking current of motor drive system. One is coupling of the parasitical capacity between power electronic device and radiator, the other is coupling of the distributive capacity between motor winding and stator enclosure. Coupling of the distributive capacity between cable and the earth should be taken into account if the inverter output cable is very long. The return route of leaking current is mainly neutral point grounding wire of system transformer. The EMI spread route of motor PWM drive system is shown in Fig. 1 [2, 3]. In Fig. 1 Csg is the distributive capac
Data Loading...
