Fujio Kurokawa

Improvement of Dynamic Characteristics of Digitally Controlled Switching Power Converter

This paper presents the dynamic characteristics of the switching dc-dc power converter using the digital PID control method, FIR filter method and IIR filter method, and then the design criterion to improve the dynamic characteristics is discussed. As a result, it is seen in the simulation and experimental results that 11 R filter method has superior transient response and suppressed oscillation deriving from limit cycle. The undershoot is less than 200 mV and the transient time is less than 0.4 ms. This result suggests the design criterion of digitally controlled switching dc-dc power converter.

A New Model Control DC-DC Converter to Improve Dynamic Characteristics

We have already reported the novel digital control method Static Model Reference which is the improved smart digital reference of output voltage. In this case, the VCO (voltage controlled oscillator) is used as A/D signal converter because it has superior response and is low cost. However, prior attempts to improve the transient response have been inconclusive because this model depends on the steady-state analysis. This paper presents a new model control method of switching dc-dc converter to improve the dynamic characteristics. Furthermore, the relationship between the parameters of control circuit and the dynamic characteristics is discussed. As a result, it is seen that the dc-dc converter with a new model control has a superior transient response compared with that of the conventional control. Especially, the overshoot of the reactor current is suppressed to within 34% and this result is approximately 30% smaller than that of the conventional static model reference control.

A New Fast Digitally Controlled DC-DC Converter

The purpose of this paper is to present a new fast digitally controlled dc-dc converter using multi-phase operation of VCOs. In this proposed digital control circuit, the low power consumption is realized because the digital control circuit uses the low frequency VCO and the low synchronized clock. In 1 MHz digitally controlled DC-DC converter, the proposed method is useful and it is revealed in the simulation that the quantization width of the output voltage is less than 10 mV, the undershoot of the output voltage is within 4% and the convergence time that the output voltage is settled within 1% is 16.4 mus. Moreover, the low power consumption and low cost are expected because the operation frequency of all VCOs and the synchronized clock of the peripheral circuit are less than 25 MHz.

A new digital control DC-DC converter with peak current -injected control

This paper presents a new digital control circuit which is able to detect the peak switch current of the high frequency switching dc-dc converter. In this proposed digital control circuit, the peak current-injected control is realized using the combination of the simple dual pulse width modulation analog-to-digital signal converter and the programmed delay circuit. In 100 kHz digitally controlled dc-dc converter, it is seen in simulation that the proposed method has no overshoot of the output voltage and the convergence time that the output voltage is settled to steady-state is only 30 mus. The difference between the transient time of the proposed circuit and that of the conventional method is an order of magnitude. Furthermore, the ratio of resolution of the DPWM generator against the output voltage is 0.27% and is satisfied to apply the commercial power supply unit.

A new fast response digital filter control DC-DC converter

A fast and expensive analog to digital signal converter is necessary to realize the fast switching performance in the digitally controlled DC-DC converter. We have already reported the method to use a cheap VCO (voltage controlled oscillator) as an analog to digital converter. However, it has been recognized that this technique is difficult to apply the general digital filter control DC-DC converter because the VCO is useful only for the P-I-D control techniques. So, there has been no study that tried to use both the digital filter control and VCO. This paper presents a new fast response digital filter control DC-DC converter using VCO. Further, the comparison of transient response characteristics of the digital control methods using VCO and the conventional analog to digital signal converter are discussed. As a result, it is revealed that the proposed method has the superior transient response and can suppress the oscillation phenomenon driving from limit cycle.

A new high performance digitally controlled dc-dc converter with peak current-injected control

The current mode dc-dc converter is useful in order to perform the superior dynamic characteristics. However, these studies have focused on sensing the average value of the switch/reactor current because it is very difficult to sample the data of accurate peak point of switch/reactor current in the digitally controlled high switching converter. Therefore, it has been reported that the peak point is estimated from the slope of reactor current, but there has been no study that tried to detect the peak value of reactor/switch current in the fast switching dc-dc converter. This paper presents a new digital control circuit which is able to detect not only the average output voltage but also the peak switch current of the high frequency switching dc-dc converter. In this proposed digital control circuit, the peak current-injected control is realized using the combination of the simple dual pulse width modulation analog-to-digital signal converter and the programmed delay circuit. In 100 kHz digitally controlled dc-dc converter, it is seen in simulation that the proposed method has no overshoot of the output voltage and the convergence time that the output voltage is settled to steady-state is only 30 mus. The difference between the transient time of the proposed circuit and that of the conventional method is an order of magnitude.

Improvement of dynamic characteristics of digitally controlled DC-DC converter

We have already reported the novel digital control method ldquostatic model referencerdquo which is the improved smart digital reference of output voltage. However, prior attempts to improve the transient response have been inconclusive because this model depends on the steady-state analysis. This paper presents a new model control method of the switching dc-dc converter using both the static and dynamic functions to improve the dynamic characteristics. Furthermore, the relationship between the parameters of control circuit and the dynamic characteristics is discussed. As a result, it is seen that the DC-DC converter with a new model control has a superior transient response compared with that of the conventional control. Especially, the overshoot of the reactor current is suppressed to within 34% and this result is approximately 30% smaller than that of the conventional ldquostatic model referencerdquo control.

Static and dynamic characteristics of dc-dc converter using a digital filter

This paper presents the regulation and dynamic characteristics of the dc-dc converter with the digital PID control, the minimum phase FIR filter or the IIR filter. Further, we discuss the comparison of these performance characteristics. As a result, it is clarified that the variable rate of the regulation is within 1.3%, the undershoot is less than 200 mV and the transient time is less than 0.4 ms in the IIR filter method.