Input Voltage Feedforward Research Articles

A Forward-Type Single-Stage Multi-Input Inverter With Series-Time-Overlapping Power Supply

A Forward type single-stage multi-input inverter with series-time-overlapping power supply is proposed. The circuit structure and topological family, energy management control strategy (EMCS), high frequency (HF) switching process analysis, the relationship between multiple duty cycles and power decoupling, common mode interference suppression between multiple inputs are fully studied. The circuit structure is composed of multi-input selection switches in series and an isolated bidirectional Forward type single input single output inverter. This topological family includes 6 circuits such as full-bridge type. A master-slave energy management SPWM compound control strategy with independent control of input source power based on input voltage feedforward and output voltage feedback is proposed. It realizes the energy management of the input source by controlling the instantaneous value of the output voltage and the output power ratio of the multiple inputs and achieves the smooth switching between the two power supply modes. The designed and developed 3kVA inverter prototype has excellent performances such as single-stage power conversion, HF electrical isolation, high conversion efficiency, small size and weight, wide duty cycle adjustment range, high output waveform quality, and strong load adaptability.

Robust fixed-order [formula omitted] controller synthesis for multi-phase converters with input voltage feed-forward

Generated DC voltages of batteries, fuel cells, or supercapacitors as power sources connected in series with DC-DC converters change according to operating conditions. In such cases, the output voltage stability of the multi-phase DC-DC converters is an issue, particularly being subject to noises in the input voltage and load current disturbances. Input voltage feed-forward (IVFF) compensation approaches can improve the output voltage stability of the DC-DC converters in such scenarios. This paper proposes a robust fixed-order H∞ based IVFF control framework by considering sensor noise, input voltage, and load current disturbances to improve output voltage stability and reference tracking performance. The mismatched disturbance transfer functions depending on parasitic resistances are derived to include in the controller synthesis process. An iterative convex-concave optimization-based robust fixed-order controller design algorithm is proposed to optimize the feedback and feed-forward controllers under the stability and performance constraints. This algorithm allows the designing of the controllers simultaneously. The feed-forward controller, whose structure is independent of the system transfer functions, is optimized without any model inversion or extra design steps. The performance of the proposed controller is compared with an integral linear quadratic regulator controller, a sliding mode PID controller augmented with a nonlinear disturbance observer, and a fixed-order robust controller designed with non-smooth techniques. Real-time implementation of the fixed-order control systems is performed on a 2-leg 200 W interleaved boost converter. The performances are discussed under external disturbance effects to show the validity of the proposed control approach.

A Novel Variable On-Time Control Scheme for Boundary Conduction Mode SEPIC PFC Converter

Power factor correction (PFC) can be achieved by a single-ended primary inductor converter (SEPIC) operating in boundary conduction mode (BCM) with conventional constant on-time (COT) control, but it is challenging to achieve low total harmonic distortion (THD) and high-power factor (PF), particularly at high input voltage. A variable on-time (VOT) control strategy for BCM SEPIC PFC converter without input voltage feedforward and multiplier circuits is proposed to realize unity PF in this paper. By using a variable slope sawtooth generator whose slope is controlled by the duty cycle of the main switch to adjust the conduction time of the main power switch of the converter, the proposed VOT control scheme can use a simple and easy-to-implement circuit to enhance the PF and decrease the THD significantly, especially at high input voltage. The simulation model and 100W experimental prototype are built to verify the feasibility of the suggested control method. Simulation and experiment results demonstrated that the novel VOT control scheme remarkably enhances PF and decreases THD without affecting the efficiency by contrast with the conventional COT control.

Synchronous Control Strategy with Input Voltage Feedforward for a Four-Switch Buck-Boost Converter Used in a Variable-Speed PMSG Energy Storage System

The four-switch Buck-Boost (FSBB) converter can produce voltage conversion within a wide input voltage range, which is suitable for variable-speed permanent magnet synchronous generator (PMSG) energy storage systems with AC inputs and DC outputs. To reduce the interference of input voltage fluctuation on the performance of the FSBB converter, an input voltage feedforward (IVFF) compensation method is proposed in this paper. The switching synchronization strategy is simple. Using the switching average model, the small signal model of a non-ideal FSBB converter in all working modes is established. The effects of input voltage, load current, damping coefficient and right half plane (RHP) zero on the stability of the control system are analyzed in detail. The transfer function of the IVFF of the FSBB converter is derived, and the relationship between input voltage, load current and duty cycle is analyzed. Finally, the design of the parameters of the converter control system is presented. The simulation and experimental results show that this FSBB converter has high efficiency and a good transient response.

Unified Closed-Loop Control and Parameters Design of Buck–Boost Current-Fed Isolated DC–DC Converter With Constant Power Load

The bidirectional buck–boost current-fed isolated dc–dc converter suffers from the instability when feeding the constant power load (CPL). The mathematical models of buck and boost subsystems of the converter with CPL are derived. It is proven that CPL leads to the instability of the both subsystems and the system cannot be stabilized by the single output voltage closed-loop control. The active damping method is introduced to ensure the closed-loop stability of the converter. An optimal design method of the active damping feedforward coefficient is proposed to keep the open-loop stability of the two subsystems and ensure a good dynamic response. An input voltage feedforward is used to overcome the influence of nonminimum-phase characteristics between dynamic response and the stability of the boost mode. The unified design method of the closed-loop controller parameters based on Hurwitz criterion and frequency response is proposed to keep the closed-loop stability of the two subsystems. The correctness and feasibility of the parameter design method are verified by detailed experimental results.

Input Voltage Feedforward Control Technique for DC/DC Converters to Avoid Instability in DC Grids

DC grids are becoming more popular due to the penetration of renewables and storage systems that work at dc. In dc grids, most of the loads are connected through dc/dc converters, when their power does not change they behave as constant power loads (CPLs). It is known that CPLs have a small-signal negative resistance which can produce instabilities in dc grids. Methods to mitigate instabilities include damping (or lossy) elements in the input port of the dc/dc converters, and parallel converters to mitigate potential oscillations. In this article, a new feedforward technique from the input port is included in the control signal to modify the load-end dc/dc converter input admittance. Thus, CPL behavior is only canceled in the potential unstable frequency range with a small impact on the input-to-output voltage rejection. This article explains in a comprehensive way, how to cancel the negative impedance using a simple feedforward technique. The proposal mitigates oscillations in the dc grid without increasing the complexity of the system or adding dissipative elements. Simulations in complex dc grids with several devices validate the results. Finally, experimental results in a 2000-W test bench verify the proposal.

Inductor Current Step Control with Input Voltage Feedforward for Fast Load Transient of Energy Recycling DC Electronic Load

Electronic load requires high input current slew rate for the dynamic test. An inductor current step (ICS) control (nonlinear control) cooperating with input voltage feedforward (linear control) during the transient is proposed to realize fast input current step response. The ICS control pushes the inductor current and the duty cycle to the target quiescent point within minimum time. Starting from the target quiescent point, the linear control with input voltage feedforward takes over. The advantage of proposed control is that the ICS control is able to break the low bandwidth in discontinuous conduction mode current loop, improving the input current slew rate. The input voltage feedforward can compensate the input capacitance current diversion, further improving the input current transient response. Compared with the conventional linear control, the maximum slew is increased from 32.9 to 699 A/ms, the settling time is decreased from 1.42 ms to 236 μ s, increased by 21.2 times and decreased by six times respectively, when the input current steps from 1 to 24 A at 200-V input voltage in a 5-kW prototype.

Design Method of Double-Boost DC/DC Converter with High Voltage Gain for Electric Vehicles

Direct current to direct current (DC/DC) converters are required to have higher voltage gains in some applications for electric vehicles, high-voltage level charging systems and fuel cell electric vehicles. Therefore, it is greatly important to carry out research on high voltage gain DC/DC converters. To improve the efficiency of high voltage gain DC/DC converters and solve the problems of output voltage ripple and robustness, this paper proposes a double-boost DC/DC converter. Based on the small-signal model of the proposed converter, a double closed-loop controller with voltage–current feedback and input voltage feedforward is designed. The experimental results show that the maximum efficiency of the proposed converter exceeds 95%, and the output voltage ripple factor is 0.01. Compared with the traditional boost converter and multi-phase interleaved DC/DC converter, the proposed topology has certain advantages in terms of voltage gain, device stress, number of devices, and application of control algorithms.

Design of Fast Transient Response Voltage-Mode Buck Converter With Hybrid Feedforward and Feedback Technique

For a voltage-mode buck converter, to improve the transient response and reduce the size of the proportional-integral-differential (PID) compensation network, a hybrid feedforward and feedback technique (HFFT) is presented in this article. First, the HFFT utilizes the input voltage feedforward, the output voltage feedback, and the duty-ratio feedback to achieve fast line and load transient responses simultaneously. Second, the converter system is comprised of two feedback loops. One outer loop employs a voltage feedback control and provides a phase lead (PD) element. The other inner loop uses a duty-ratio feedback control and produces a phase lag (PI) element. Then adopting the PD and PI elements, a proposed implementation of PID compensation with small on-chip components can also be obtained. A buck converter chip with the HFFT has been fabricated in 0.18- $\mu \text{m}$ 1.8/5-V CMOS technology. Measurement results show that the output voltage of the buck converter is almost invariant under a line voltage step of 1.5 V and settled within $4.5~\mu \text{s}$ for a load current step of 500 mA.

Performance Comparison of PI and P Compensation in DSP-Based Average-Current-Controlled Three-Phase Six-Switch Boost PFC Rectifier

In this paper, it is shown that in the three-phase six-switch boost power factor correction rectifier with average-current control with mismatched input-voltage and input-current sensing gains as well as offset errors in input-voltage and input-current sensing, the current controller with proportional (P) compensation exhibits lower total harmonic distortion (THD) and higher power factor compared with that of proportional and integral compensation. It is also shown that P compensation with input-voltage feedforward is effective in improving output-voltage transient response with respect to input-voltage changes only if duty-cycle feedforward is also implemented. Finally, it is shown that zero-sequence-signal injection, in addition to enabling the output-voltage regulation in a wider input-voltage range, also improves the THD of the input currents.

Solar Panel for House Hold application with Input Voltage Feed Forward for the Two Switch Buck Boost DC DC Converter

Solar Panel for House Hold application with Input Voltage Feed Forward for the Two Switch Buck Boost DC DC Converter

Automatic Mode-Shifting Control Strategy With Input Voltage Feed-Forward for Full-Bridge-Boost DC–DC Converter Suitable for Wide Input Voltage Range

Full-bridge (FB)-boost converter is suitable for applications with wide input voltage range and galvanic isolation requirement, and a two-mode phase-shift (PS)-two-edge modulation (TEM) control scheme based on two modulation signals and one carrier can be used to achieve automatic mode shifting and high efficiency. In order to reduce the influence of the input voltage disturbance on the output voltage, the small-signal model of FB-boost converter is built and the input voltage feed-forward (IVFF) functions under different operating modes are derived in this paper. In view of the small-signal and large-signal control laws of the derived IVFF functions, the two-mode PS-TEM control schemes with small-signal and large-signal IVFF compensations are proposed, respectively. Both of them can realize automatic selection of operating modes and the corresponding IVFF compensations, and thus high efficiency and improved input transient response can be guaranteed. Besides, the IVFF function in boost mode is simplified for easy implementation, and the comparisons among the two-mode PS-TEM control schemes with small-signal, large-signal, and without IVFF compensations are presented in this paper. Finally, a 250-500-V input, 360-V output, and 6-kW-rated power prototype demonstrates the effectiveness of the proposed control schemes.

A Two-Mode Control Scheme With Input Voltage Feed-Forward for the Two-Switch Buck-Boost DC–DC Converter

The two-switch buck-boost (TSBB) converter is suitable for wide input voltage applications. In order to achieve high efficiency over the entire input voltage range, the TSBB converter is operated in buck mode at high input voltage and boost mode at low input voltage. Such operation is called the two-mode control scheme. The objective of this paper is to propose an input voltage feed-forward (IVFF) method to reduce the influence of the input voltage disturbance on the output voltage. The small-signal models of the TSBB converter are built, and based on which, the IVFF functions under different operating modes of the TSBB converter are derived. The IVFF function in boost mode is simplified for easy implementation. The two-mode control scheme with IVFF compensation is then proposed for the TSBB converter, which realizes automatic selections of operating modes and the corresponding IVFF functions. Besides, nearly smooth switching between buck and boost modes is also guaranteed. For exhibiting the advantages of the proposed control scheme clearly, comparisons between the two-mode control with and without IVFF compensation have been presented in this paper, including the output signal of the voltage regulator and input-to-output voltage transfer function. Finally, a 250−500-V input, 360-V output, and 6-kW-rated power prototype is fabricated to validate the effectiveness of the proposed control scheme in the laboratory, and the experimental results show that the TSBB converter has an improved input transient response and high efficiency over the entire input voltage range with this proposed control scheme.

Passivity-Based PFC for Interleaved Boost Converter of PMSM drives

Abstract In this paper a sensorless passivity-based control with input voltage feedforward has been designed for a boost AC-DC interleaved converter to increase the Power Factor (PF) in Permanent Magnet Synchronous Motor (PMSM) drives. A robust current observer has been adopted. The proposed solution has been experimentally tested on a commercial PMSM drive equipped with a control system based on a microcontroller (MCU) of the Texas Instrument (TI) family C 2000 ™.

Dynamic Linearizing Modulator for Large-signal Linearization of a Boost Converter

Various methods to linearize the control-to-output behavior of a boost converter are discussed. Most of the previously reported linearizing techniques are not suitable when the reference input amplitude or frequency is large. In this paper, a dynamic linearizing modulator for the boost converter is proposed, which transforms the open-loop converter into a linear amplifier with an operating frequency as high as one-fifth the switching frequency. The modulator generates a duty ratio by comparing the nonlinear part of the boost converter dynamic equation with a sine wave reference voltage on a cycle-to-cycle basis. The technique exhibits superior audio susceptibility due to the feedforward of input voltage. The formulation, implementation, and verification of this technique are discussed. Experimental results show the validity of the technique for a reference input frequency up to one-fifth the switching frequency.

Multimode Digital Controller for Synchronous Buck Converters Operating Over Wide Ranges of Input Voltages and Load Currents

This paper describes a digital pulsewidth modulation/pulse-frequency modulation (PWM/PFM) controller with input-voltage feedforward (IVFF) for synchronous buck dc-dc converters. The controller includes automatic PWM/PFM mode switching and effective synchronous operation with a minimum number of active components and without the need for current sensing in PFM mode of operation. IVFF improves efficiency and dynamic performance over a wide range of input voltages. Controller parameters, including the PWM switching frequency, the PFM pulse period, and the mode transition point are programmable, which enables efficiency optimization. Experimental results are shown for a synchronous buck converter with 5-12 V input voltage, and 1.3 V, 0-10 A output.

Input-Voltage Feedforward (IVFF) Circuit Minimizing Current Stress of Voltage-Doubler Rectified Asymmetrical Half-Bridge (VDRAHB) Converter

A new input-voltage feedforward (IVFF) circuit for a voltage-doubler rectified asymmetrical half-bridge (VDRAHB) converter is proposed in this letter. The proposed circuit regulates output voltage not by reducing duty ratio but by increasing switching frequency as input voltage increases. Therefore, by employing the proposed IVFF circuit into the VDRAHB converter, the peak currents of the overall components can be greatly reduced, and also, efficiency can be improved at high input voltages.

Dynamical Characterization of Input-Voltage-Feedforward-Controlled Buck Converter

The use of input-voltage-feedforward (IVFF) control has become a popular method to implement a low-cost bus converter in the telecommunications distributed power architectures because the IVFF control can provide adequate output-voltage accuracy in respect to the variations in the input voltage even at open loop, when applied to a buck converter. The method in itself is well known from the 1980s, but the dynamical features that the method would provide have not been fully investigated and reported. The results of the investigations made in this paper show that the IVFF control would provide input-noise attenuation comparable to the peak-current-mode control, voltage-loop gain largely independent of input voltage, and highly reduced input-filter interactions as compared to the voltage-mode control. The main disadvantage is the reduced output-voltage-load-transient response due to the input-voltage-dependent maximum duty ratio. The observations are supported with comprehensive experimental measurements

Modeling, control, and design of input-series-output-parallel-connected converter for high-speed-train power system

In this paper, a charge control with an input voltage feedforward is proposed for an input-series-output-parallel-connected converter configuration for the high-speed-train power system application. This control scheme accomplishes the output current sharing. For the output-parallel-connected modules as well as the input voltage sharing for the input-series-connected modules for all operating conditions including the transients. It also offers the robustness for the input voltage sharing control according to the component value mismatches among the modules. This configuration enables the usage of a MOSFET for a high-voltage system allowing a higher switching frequency for a lighter system weight and smaller size. The performance of the proposed scheme is verified through the experimental results.

Controlling a DC-DC converter by using the power MOSFET as a voltage controlled resistor

Most converter designs assume that a closed power switch has zero volts across it. In general, this is a valid assumption that reduces the design complexity. However the fact that a power switch does have a finite resistance means that there will be a nonzero voltage across it during its on time. This voltage can be taken advantage of. This paper proposes a simple control technique that utilizes the variable resistance of the power MOSFET in a dc-dc converter. This is the first switched mode power supply that uses the power switch in more than two states or operating points. It is also the first switched mode power supply that uses the power switch as a variable control device as well as a power device. A 48-5-V 20-W forward converter is implemented to confirm the theory and demonstrate its practicality. The proposed technique provides self oscillation, self overload protection, zero voltage switching (ZVS), input voltage feedforward, and a reduced component count and cost.