In this paper, we describe a method of generating gate signals of the PWM rectifier section of the converter without DC link components, which is able to remove snubber circuits In the snubber circuits, losses have been dissipated every time the switches of the rectifier section are turned on and off The commutation strategy of the proposed method consists of four steps during the switching process The proposed method is verified by experimental tests on an induction motor drive It is concluded that it decreases losses in the rectifier section

Four-step commutation strategy of PWM rectifier of converter without DC link components for induction motor drive

A voltage source inverter without DC link components is an AC-to-AC converter having dual bridges such as a PWM rectifier and a PWM inverter without DC link components, therefore, a PWM rectifier and a PWM inverter can be controlled independently. Conventional matrix converters have disadvantages such as a complicated commutation scheme and necessity of a large sized clamp circuit, but commutation and protection of this inverter can be implemented easily. In order to control the PWM rectifier and the PWM inverter independently, snubber circuits for the PWM rectifier are required to assure the path of load current during dead time. In this paper, analytical method of a snubber circuit and operating characteristics of an induction motor are described when a 0.75 kW induction motor driven by this inverter.

A study of dead-time of PWM rectifier of voltage- source inverter without DC link components and its operating characteristics of induction motor

Chapter 6 References

Technical Trends of Direct AC/AC Converters

This paper proposes a novel control method for an interface converter using an indirect matrix converter with three power supplies, which consist of two AC and one DC supplies. An active snubber circuit in the indirect matrix converter is used as an interface with the DC power supply. The proposed control method is based on the indirect control method with a triangular carrier wave [10]. Therefore the proposed method can be easily applied to a DC/DC converter. In addition, this paper proposes reducing the number of switching during one carrier period for the inverter stage converter. In the proposed method, the inverter stage carrier is controlled asymmetry to reduce the switching times in the inverter stage. To apply the proposed method, the switching loss of the inverter stage can be decreased to 2/3 times in comparison with a conventional method. The validity of the proposed method is confirmed by simulation and experimental results.

/pdf/control-method-for-a-three-port-interface-converter-using-an-4b71n03aj6.pdf

Control method for a three-port interface converter using an indirect matrix converter with an active snubber circuit

The voltage-source inverters are normally equipped with an electrolytic capacitor in their DC link. The electrolytic capacitor has several disadvantage such as increasing size, limitting converter life and reliability. Therefore, several approaches for removing the DC link capacitor have been studied. This paper proposes a new strategy of the voltage source inverter without DC link components. To restrain the current resonance caused by LC filter of AC source side, rectifier of this inverter is controlled by current closed loop with di/dt feedback (di/dt; differenciation of AC source current). To improve AC source current waveform, feedback gain of di/dt and LC parameters are investigated by calculation for a 0.75kW induction motor driven by this inverter. Both the calculated and measured waveforms of AC source currents maintain nearly sinusoidal waveforms with a unity power factor.

https://www.jstage.jst.go.jp/article/ieejias1987/119/2/119_2_133/_pdf

Characteristics of New Current Controlled PWM Rectifier-Voltage Source Inverter without DC Link Components for Induction Motor Drive

A converter without DC Link components needs snubber circuits, in order to assure the path of the load current during the dead-time period of the PWM rectifier section. In the snubber circuits, losses have been dissipated every time the switches of the rectifier section are turned on and turned off. During the zero voltage vector period of the inverter section, the load current does not flow in the PWM rectifier section. So if each switching operations of the PWM rectifier section are done in the zero voltage vector period, it is not necessary to assure the path of the load current. Therefore, snubber circuits are not necessary in the PWM rectifier section. In this paper, we describe a zero current switching strategy of the PWM rectifier section during zero voltage vector periods of the inverter section. The proposed strategy is verified by computer simulation and experimental test on an induction motor drive.

A Zero current Switching Strategy of PWM Rectifier of Converter without DC Link Components for Induction Motor Drives

The voltage-source inverters are normally equipped with an electrolytic capacitor in their DC link, however, the electrolytic capacitor has several disadvantages such as increasing size, limiting converter life and reliability. Therefore, several approaches for removing the DC link capacitor have been studied by the authors. This paper proposes a new voltage-source inverter without DC link components. To reduce waveform distortion of the AC source current, the current-controlled PWM-rectifier with di/dt feedback is introduced. The di/dt feedback gain and LC parameters are investigated by calculation for a 0.75kW induction motor driven by this inverter. The calculated AC source currents maintain nearly sinusoidal waveforms with a unity power factor.

Mitsuhiro Muroya

Papers

Characteristics of New Current Controlled PWM Rectifier-Voltage Source Inverter without DC Link Components for Induction Motor Drive

A Zero current Switching Strategy of PWM Rectifier of Converter without DC Link Components for Induction Motor Drives

CURRENT-CONTROLLED PWM-RECTIFIER WITH di/dt FEEDBACK/VOLTAGE-SOURCE INVERTER WITHOUT DC LINK COMPONENTS FOR INDUCTION MOTOR DRIVE

Characteristics of New Current Controlled PWM Rectifier-Voltage Source Inverter without DC Link Components for Induction Motor Drive