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A digitally controlled current-mode quadrature oscillator (DCC-MQO) is proposed. The circuit consist of four cascaded log-domain first order low-pass filter and a digitally programmable current division network. The lossy log-domain integrator gain and time constant can be adjusted using the bias currents of the logarithmic and exponential building blocks. The programmable current division network...
A circulating current is a major problem introduced by directly connecting voltage source inverter (VSI) in parallel. This circulating current occurs as a zero-sequence current between the inverters by specic switch states. Its alternatives were presented by hardware and software methods in many papers. When coupled inductor (CI) are employed for the high frequency circulating current, a circulating...
A digital frequency synthesizer is proposed to support the burst-frequency switch for a motion controller. The proposed digital frequency synthesizer consists of a phase-locked loop (PLL) generating a 63-phase clock with a frequency of 128 MHz and a programmable open-loop fractional divider. It generates an output clock with a frequency resolution of 0.1% over a frequency range from 0.5 kHz to 32...
A simple and effective method is proposed to eliminate double-line frequency component in the outer voltage control loop of rectifiers with power factor correction (PFC). An adaptive notch filter based on the internal model principle (IMP) of control theory is introduced between the feedback error ADC and the digital PI voltage loop controller of the rectifier. It effectively identifies the exact...
A new generator control unit (GCU) must be designed to work in a wide frequency range in order to obtain better control performance in variable frequency AC power system. Control algorithms make improvements in terms of determining the control parameters and analyze the influence of the controller parameters on system stability, and compensate for the loss of signals generated in the conditioning...
The boost type dc-dc converter is used for compensation of dc bus voltage in the dc power feeding system such as the renewable energy system. It should be operated stably to improve reliability of the system. The peak current mode control is applied to operate stably because the boost type dc-dc converter tends to be unstable. However, a peak value of reactor current cannot be captured in the digital...
This paper presents the control method of an LCL filter implemented for a three-phase, voltage-source, grid-connected inverter for not only offering better attenuation of switching harmonics but also for highly damping the resonance. A discrete-time deadbeat current controller with tuned state-feedback gains is proposed to realize the time optimum responses with high control accuracy. In addition,...
In recent years, it is desired that the bandwidth of a class-D amplifier is widened using sampling frequencies as low as possible. For example, it is expected in the application of the power amplifier of vibration generator that the bandwidth is kept 5[kHz] within the load impedance ∞∼2 [Ω]. In this paper, it is shown that this demand to the class-D amplifier can be attained by an A2DOF (Approximate...
In this paper, an adaptive synchronous rectifier (SR) driving scheme for the LLC resonant converters using the ripple counter concept is proposed, along with two methods of implementation. With the proposed scheme, the SR drain to source voltage is sensed to detect the body diode conduction, based on which the SR on-time can be well tuned to eliminate the body diode conduction. One proposed implementation...
Energy Harvesting is gaining more attention nowadays due to the urge to have self-powered systems. the biggest challenge when designing the system is having a control unit that does not consume too much power as well as capable of providing a stable and accurate performance. In this work, 2 different implementation approaches for the same control unit logic are investigated and compared to each other...
This paper presents a consideration about miniaturization of buck-boost dc-dc converter with the fast P control. From frequency characteristics, it is identified that fast P control method is useful to suppression of output capacitance and circuit miniaturization.
The purpose of this paper is to present the performance characteristics of the digital PID based two-compensator for the dc-dc converter. Authors have already presented a fast PD control method, which can reduce the influence of the delay time. In this paper, the transient characteristics of output voltage are confirmed in the simulation when the sampling frequency of the PID control is slowed down...
This paper presents the comparison of three different fully digital, oversampled, large bandwidth inverter current controllers: a proportional integral controller, a predictive controller, and a non-linear hysteresis controller. The purpose is to determine which one allows to achieve the highest final performance when adopted as the inner current control loop in a microgrid utility interface converter...
This paper presents an analytical development for the Nyquist trajectory of the closed loop system of a Voltage Source Inverter with resonant control strategy. Both inner current loop and outer voltage loop are taken into account, and the interaction between them is studied. The stability boundaries depending on different parameters are determined. Firstly, the system is modelled and analysed in continuous...
The light load efficiency has drawn more and more attention for the LLC resonant converters. And the high frequency LLC converters are emerging in recent years. The conventional burst mode control cannot fix to the efficiency-optimal state during the burst-on time. Optimal Trajectory Control (OTC) for burst mode can solve this problem by using fixed 3-pulse pattern; however, the burst operation range...
A variety of applications using ultrasonic transducer is operating at high power in a low frequency range in industry. The resonance frequency shift and electrical impedance change is a common phenomenon in the application of high-power ultrasonic transducer. In order to achieve a stable or consistent results, it is important to track the resonance frequency. To solve these problems, various electrical...
Shunt active power filters are proved as useful elements to correct the distorted currents caused by nonlinear loads in power distribution systems. This work presents an all digital approach, based on the repetitive control technique, for their control. The design is performed for the particular case of singlephase shunt active filter with a full-bridge boost topology. Several simulation results are...
The purpose of this paper is to reveal the effect of control gain in the proposed fast PD control method. A bode diagram is described using a loop transfer function. The variation tendency of frequency characteristics for different values of fast proportional gain and fast differential gain is discussed. Moreover, the frequency characteristics of proposed method are compared with the conventional...
The paper presents a reconfigurable fully differential all pass filter based on CMOS differential voltage current conveyor. The proposed topology uses two differential voltage current conveyors along with two resistors and two capacitors. The phase angle of the realized fully differential all pass filter can be controlled through an n-bit digital control word. Thus the proposed filter topology provides...
This paper introduces a digital multi-mode boost converter with wide range of input voltage for an energy recycling load system. The boost converter is controlled digitally with constant off- time/constant frequency hybrid pulse width modulation (PWM) control. Constant off-time control is to avoid the limit cycle oscillation and gain a high gain when the input voltage is far less than the output voltage...
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