Search

This paper presents an analysis of Class D inverter when irregular driving patterns are given to the gate drive of the switch devices. The analysis has been carried out with focusing on the waveforms, harmonics, low-frequency components, output power, and equivalent dc resistance, which are numerically analyzed and discussed. Class D inverters with six different Q factors from 0.1 to 20 are analyzed about 216 driving patterns for each Q. Superior four models of the six inverters are built and tested in circuit experiments. The calculated waveforms are compared to the experimental results. Both of them are agreed well in time domain and frequency domain. Analytical results show a possibility of a novel control method with irregular driving patterns. In spite of discontinuous control, the output power or voltage can be strictly changed as if continuous using the selected driving patterns in some ranges

This paper presents a new control scheme for a Class DE inverter, that is, frequency modulation/pulsewidth modulation (FM/PWM) control. Further, the FM/PWM controlled Class DE inverter is analyzed and we clarify performance characteristics. Since the FM/PWM controlled inverter has two control parameters, namely, the switching frequency and the switch-on duty ratio, it has one more degree of freedom for the control than the inverter with the conventional control scheme. The increased degree of freedom is used to minimize the switching losses. Therefore, it is possible to control the output power with high power-conversion efficiency for wide-range control. Carrying out the circuit experiments, we confirm that the experimental results agree well with the theoretical predictions quantitatively. For example, the proposed controlled inverter can control the output voltage from 56% to 191% of the optimum one, which is designed for 1.8 W at 1.0 MHz, with maintaining over 90% power-conversion efficiency.

In this paper, a simple input current waveform shaping method for a rectifier with a high power factor using the induced voltage of a flyback transformer is proposed. The duty ratio of the present shaping circuit is obtained by comparison of the integration signal of the rectified induced voltage and the ramp carrier waveform with a negative slope. By means of the proposed method, the input voltage sensor, current control loop, multiplier, and inductance current sensor can be eliminated, simplifying the control circuit. In order to confirm the proposed method, a flyback rectifier circuit for 100 W is fabricated for an experimental investigation. The results confirm that the input current waveform of the rectifier becomes closer to a sinusoidal shape and harmonic components become smaller by the use of the present shaping method. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(10): 26–35, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10188