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Showing papers on "Forward converter published in 1995"


Journal ArticleDOI
TL;DR: In this article, the authors introduce the family of quasi-direct converters, i.e., forced-commutated AC/DC/AC power converters including small energy storage devices in the DC link.
Abstract: The paper introduces the family of quasi-direct converters, i.e., forced-commutated AC/DC/AC power converters including small energy storage devices in the DC link. In particular, the case of the three-phase to three-phase quasi-direct power converter is considered. Since energy storage minimization calls for instantaneous input/output power balance, a proper control strategy is needed. The paper describes a simple and effective control technique which also provides high-power factor and small distortion of the supply currents. After a discussion of the general properties of quasi-direct power converters, design criteria of both power and control sections are given, and experimental results of a 2-kVA prototype are reported. >

212 citations


Patent
28 Sep 1995
TL;DR: In this article, a simple low-cost technique for charge equalization of a series connected string of battery cells is provided, where a single power converter applies a charging signal to the primary of the transformer, inducing a charging current in each secondary which is inversely related to the charge on the battery cells to be equalized.
Abstract: A simple, low-cost technique for charge equalization of a series connected string of battery cells is provided. The secondary windings of a transformer having a single primary winding and multiple secondary windings are connected across each battery cell to be equalized. A single power converter applies a charging signal to the primary of the transformer, inducing a charging current in each secondary which is inversely related to the charge on the battery cells to be equalized. The transformer is preferably implemented as a coaxial winding transformer having low secondary-to-secondary winding coupling. The power converter is preferably implemented as a forward converter supplied with DC power from an adjustable DC power source. A source voltage provided by the DC source may preferably be adjusted during the course of charge equalization to preferentially direct charge to weaker cells. The charge equalization system may be used in combination with a bulk charging system to provide for both rapid charging of a battery string as well as equalization of the battery cells within the string.

142 citations


Proceedings ArticleDOI
18 Jun 1995
TL;DR: In this paper, a multilevel voltage-source converter system is proposed for high-voltage, high-power applications such as back-to-back interconnection of power systems, large induction motor drives, and electrical traction drives.
Abstract: In this paper, a multilevel voltage-source converter system is proposed for high-voltage, high-power applications such as back-to-back interconnection of power systems, large induction motor drives, and electrical traction drives. Multilevel voltage-source converters have a voltage unbalance problem in the DC capacitors. The problem may be solved by use of additional voltage regulators or separate DC sources. However, these solutions are found not to be practicable for most applications. The proposed converter system can solve the voltage unbalance problem of the conventional multilevel voltage-source converters, without using any additional voltage balance circuits or separate voltage sources. The mechanism of the voltage unbalance problem is analyzed theoretically in this paper. The voltage unbalance problem of multilevel converters in the DC capacitors has been solved by the proposed internal connections of the AC/DC and DC/AC converters. The validity of the new converter system is demonstrated by simulation and experiment. >

140 citations


Patent
22 Dec 1995
TL;DR: In this paper, a soft-switching DC to DC power converter which minimizes switching losses from a no load condition to a full load condition while operating at fixed frequency is proposed.
Abstract: A soft-switching DC to DC power converter which minimizes switching losses from a no load condition to a full load condition while operating at fixed frequency. Output voltage control is achieved by controlling the phase angle between the two switching networks. High frequency transformer primaries are always excited with a square wave input voltage equal to ##EQU1## The power converter can be implemented with a single transformer. Moreover, the switch voltage never increases the input DC voltage from no load to full load. The power converter can be used in both low voltage high current applications and high voltage low current applications.

120 citations


Proceedings ArticleDOI
05 Mar 1995
TL;DR: In this paper, a buck-boost bi-directional DC-DC power converter topology for electric vehicles with axial-flux PM motor drives is presented. But the experimental results taken from a 20 kW water-cooled prototype of the proposed power converter were evaluated.
Abstract: In brushless DC motor drives devoted to electric vehicles (EVs) a bi-directional DC-DC power converter can be used to control suitably both motoring and regenerative braking operations in order to improve the motor drive performance. In consideration of such an application, this paper deals with the experimental study of a buck-boost bi-directional DC-DC power converter topology which has been conceived for the use in EVs propelled by means of wheel-direct-coupling axial-flux PM motor drives. The paper discusses the power converter modes of operation and reports experimental results taken from a 20 kW water-cooled prototype of the proposed power converter topology. >

106 citations


Patent
24 Feb 1995
TL;DR: In this article, a high efficiency high power DC to DC power converter and controller system for a CD ignition system with a simple converter controller (8) for controlling a power switch (2) of a transformer (1) operated as a flyback which includes a lossless snubber (6) and simple current sensor (8a) for sensing and controlling the power converter current, and further including ignition trigger conditioner (9) and phase conditioner(10) for operating a trigger output circuit (11) based on an octal counter (67) for triggering ignition coil circuits
Abstract: A high efficiency high power DC to DC power converter and controller system for a CD ignition system with a simple converter controller (8) for controlling a power switch (2) of a transformer (1) operated as a flyback which includes a lossless snubber (6) and simple current sensor (8a) for sensing and controlling the power converter current, and further including ignition trigger conditioner (9) and phase conditioner (10) for operating a trigger output circuit (11) based on an octal counter (67) for triggering ignition coil circuits of a preferred distributorless ignition circuit of the hybrid ignition system type.

89 citations


Patent
22 May 1995
TL;DR: In this paper, a high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source.
Abstract: A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360°/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

78 citations


Proceedings ArticleDOI
18 Jun 1995
TL;DR: In this paper, the half-bridge complementary control power converter has been proposed as a low-output voltage DC-to-DC power converter due to its excellent features (efficiency around 90% at as low an output voltage as 33 volts) and a study of the statics and dynamics of this power converter is proposed.
Abstract: The half-bridge complementary-control power converter has been recently proposed as a low-output voltage DC-to-DC power converter due to its excellent features (efficiency around 90% at as low an output voltage as 33 volts) A study of the statics and dynamics of this power converter is proposed in this paper Thus, DC voltage conversion ratio both in continuous and discontinuous conduction mode, the boundary between both modes, the DC current level in the transformer and a small-signal average model have all been obtained From the latter, transfer functions between duty cycle and output voltage and between input and output voltages have been also obtained, and some simplifications and design rules have been proposed to facilitate the design of the feedback loop >

78 citations


Patent
03 Feb 1995
TL;DR: In this article, a PWM-controlled flyback converter with a single transformer and a primary side resonant subcircuit is proposed to minimize reverse recovery losses, where the primary windings are connected in series, the first transformer having substantially greater inductance than the second transformer.
Abstract: Resonant DC to DC power converter topologies include a PWM-controlled flyback converter having a single transformer and a primary side resonant subcircuit that is optimally controlled to minimize reverse recovery losses. A second transformer may be added wherein the primary windings are connected in series, the first transformer having substantially greater inductance than the second transformer to more efficiently transfer energy over a wide range of output load conditions. A combined forward-flyback resonant converter utilizing a load-side buck loop for increased power delivery performance and start-up circuitry for initial power connection of the converter to a voltage source utilizing a hysteresis protection circuit are also disclosed.

75 citations


Patent
Walter Zeitler1, Ernst Gabriel1
18 Aug 1995
TL;DR: In this article, the authors present a control circuit for fluorescent lamps, which includes a pulse width modulator, a multivibrator and a start/stop controller, which varies the duty cycle of a control signal supplied to the DC-to-DC converter based on a feedback signal from the DC to DC converter and halts the operation of the power output stage if a failure is detected.
Abstract: A device for operating lamps, such as fluorescent lamps includes an input protection circuit, a filter, a DC to DC converter, a power output stage, a lamp connecting circuit and a control circuit. The control circuit includes a pulse width modulator, a multivibrator and a start/stop controller. The pulse width modulator varies the duty cycle of a control signal supplied to the DC to DC converter based on a feedback signal from the DC to DC converter. The multivibrator assists in the control of the DC to DC converter. The start/stop controller initiates the operation of the power output stage when an output of the DC to DC converter reaches a predetermined level and halts the operation of the power output stage if a failure is detected.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the state variables of the LC filter connected to the AC side of the converter are fed back to the PWM pattern generator, thereby eliminating a DC offset of the AC input currents as well as oscillations of the DC output current during transients.
Abstract: This paper presents a new state feedback based control strategy for a PWM AC to DC voltage type converter with phase and amplitude control. In this control strategy the state variables of the LC filter connected to the AC side of the converter are fed back to the PWM pattern generator, thereby eliminating a DC offset of the AC input currents as well as oscillations of the DC output current during transients. Computer simulation of the converter system with the proposed control strategy shows that the transient waveforms of AC input and DC output currents are improved greatly even if the damping effect of the AC side resistance can not be expected. The DC voltage regulation with good dynamic response is also achieved even if DC capacitance is substantially reduced. Experimental results from a low power laboratory model are also included to confirm the simulated results and to demonstrate the effectiveness of the proposed control strategy. >

Patent
19 Sep 1995
TL;DR: In this article, a transient over-voltage protection circuit is proposed to protect the DC to DC converter from input voltages that exceed the converter's operational limits by partially opening a switch connected between a rectifier circuit and a DC-to-DC converter.
Abstract: A transient over-voltage protection circuit includes a normally closed switch connected between a rectifier circuit and a DC to DC converter. This switch is caused to partially open when the voltage input to the DC to DC converter exceeds a predetermined value, thereby protecting the DC to DC converter from input voltages that exceed the converter's operational limits. The switch is returned to its normally closed state when the level of voltage input to the converter drops below a predetermined lower value. A capacitor connected across the input terminals of the converter is charged up when the switch is closed and functions to supply power to the DC to DC converter when the switch is in its partially opened or current limit state.

Proceedings ArticleDOI
05 Mar 1995
TL;DR: In this paper, a three-switch HV converter derived from the Cuk converter is presented, which offers simpler structure and control, higher efficiency, reduced EMI, size and weight savings than traditional switched-mode regulated voltage multipliers.
Abstract: A novel three-switch HV converter derived from the Cuk converter is presented. This converter can operate into a capacitor-diode voltage multiplier, which offers simpler structure and control, higher efficiency, reduced EMI, size and weight savings than traditional switched-mode regulated voltage multipliers. Two significant advantages are the continuous input current and easy isolation extension. The new converter is experimentally verified. Both the steady state and dynamic theoretical models are correlated well with the experimental data. >

Patent
Kyung-Sang Lee1
14 Jul 1995
TL;DR: In this paper, a power-supply controller of a computer can minimize power-consumption as shown in the following description, which is composed of a power supply, a power controller, and a powermode controller.
Abstract: The power-supply controller of a computer can minimize power-consumption as shown in the following description. The operation mode will convert to a sleep-mode reducing the power-consumption below a constant voltage if there is no input to operate a computer system for a predetermined period of time. If the condition of no input for operating a computer system persists, the power supply controller cuts off the power-supply once again. In order to achieve this object, this invention is composed of a power-supply, a power-controller, and a power-mode-controller. The power-supply includes a first rectifier that converts an AC voltage to a DC voltage, a DC/AC converter which converts a DC voltage into an AC voltage, a switching mechanism which outputs a pulse signal used to operate the DC/AC converter, a second rectifier which converts to a DC voltage from an AC voltage received from the DC/AC converter, and a driver which provides an operation voltage to operate the switching mechanism. The power-controller outputs a power-supply signal used to change from the sleep-mode into a power-off mode if there is no input for a predetermined period during the sleep-mode, and which outputs a power-supply signal to change from the power-off mode into a resume-mode if there is an input. The power-mode-controller also includes a power-mode control circuit that varies the output from the power-controller and varies an operation voltage to operate the switching mechanism and a charger which charges a battery with AC voltage and provides the power-controller with a power-supply.

Proceedings ArticleDOI
05 Mar 1995
TL;DR: In this article, a small-signal model of soft-switched asymmetrical half-bridge DC/DC converter operating in a continuous inductor conduction mode is proposed.
Abstract: A small-signal model of soft-switched asymmetrical half-bridge DC/DC converter operating in a continuous inductor conduction mode is proposed. The analysis of this model is applicable to converters with any type of output rectifier (full-wave or half-wave). Based on the proposed model, the feedback compensation network for a prototype converter was designed. An open loop frequency response and voltage ripple attenuation of the converter with closed feedback loop were calculated. The experimental results validated all theoretical predictions. >

Journal ArticleDOI
TL;DR: In this article, a three element resonant converter capable of driving a voltage type load with load independent operation is analyzed using a state-space approach, and closed-form solutions are obtained under steady state conditions.
Abstract: A three element resonant converter capable of driving a voltage type load with load independent operation is analyzed using a state-space approach. Pulse width modulation is employed to control and regulate the output voltage. Closed-form solutions are obtained under steady state conditions. The experimental study of a prototype converter reveals complete agreement with the analytical and SPICE simulation results. Typical experimental oscillograms are given to verify the basic principles. >

Patent
Ogawa Yoshio1
15 May 1995
TL;DR: In this paper, a control apparatus for controlling a motor of an air conditioner includes a converter (2), having switching means (2a) for improving an input power factor, for converting an AC power to a DC power and an inverter (4) for converting the DC power supplied from the converter to the AC power and supplying to a compressor.
Abstract: A control apparatus for controlling a motor of an air conditioner includes a converter (2), having switching means (2a) for improving an input power factor, for converting an AC power to a DC power and an inverter (4) for converting the DC power supplied from the converter to the AC power and supplying to a compressor (3). The output DC voltage of the converter is detected by a DC voltage detecting circuit. An input alternating current is detected by a current detecting circuit (11). A microcomputer (13) for controlling the inverter calculates a current command from data stored on the basis of the detected voltage. The detected current is compared with the current command, an ON percentage of a PWM signal to control the switching means is obtained, and the PWM signal is generated.

Proceedings ArticleDOI
18 Jun 1995
TL;DR: In this paper, a half-bridge DC/DC power converter with complementary control and self-driven synchronous rectification is described, which is shown to have high efficiency for low output voltage, soft-switching for primary and secondary switches and very small output filter.
Abstract: A half-bridge DC/DC power converter with complementary control and self driven synchronous rectification is described in this paper. Zero voltage switching is analyzed taking into account the effect of the parasitic capacitances of the synchronous rectifiers of the secondary side. The main advantages of this power converter, which are high efficiency for low output voltage, soft-switching for primary and secondary switches and very small output filter, are shown in an actual prototype. >

Patent
25 Sep 1995
TL;DR: In this article, a power converter includes a transformer for receiving bipolar electrical input power from a power source, the power substantially free of dead time and a hybridge rectifier coupled to the transformer and including first and second output inductors of independently selectable, differing inductance.
Abstract: A power converter and a method of operating a power converter. The power converter includes: (1) a transformer for receiving bipolar electrical input power from a power source, the power substantially free of dead time and (2) a hybridge rectifier coupled to the transformer and including first and second output inductors of independently selectable, differing inductance, the hybridge rectifier receiving the input power from the transformer and rectifying the input power to produce an output power substantially free of ripple current at a predetermined duty cycle operating point of the converter, the first and second output inductors being of independently selectable, differing inductance thereby to allow the predetermined duty cycle operating point to be adjustable.

Proceedings ArticleDOI
05 Mar 1995
TL;DR: In this article, a general-purpose fuzzy controller for DC-DC converters is investigated, based on a qualitative description of the system to be controlled, and fuzzy controllers are capable of good performances even for those systems where linear control techniques fail, e.g. when a mathematical description is not available or in the presence of wide parameter variations.
Abstract: In this paper, a general-purpose fuzzy controller for DC-DC converters is investigated. Based on a qualitative description of the system to be controlled, fuzzy controllers are capable of good performances even for those systems where linear control techniques fail, e.g. when a mathematical description is not available or in the presence of wide parameter variations. The presented approach is general and can be applied to any DC-DC converter topologies. Controller implementation is relatively simple and can guarantee a small-signal response as fast and stable as for other standard regulators and an improved large-signal response. Simulation results of buck-boost and Sepic converters show control potentialities. >

Patent
24 Aug 1995
TL;DR: An onboard electric vehicle charger is provided in this paper which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries.
Abstract: An onboard electric vehicle charger is provided which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries plus small size (approximately 15" by 9" by 6") and weight (less than 15 kilograms) and a power factor correcting boost preregulator with dynamic adjustment of its compensation networks which produces full correction to substantially unity (99.9+%) for power factor with current total haromonic distortion (THD) of 2% to 3% over the entire power range of 100 watts to 5,000 watts. The same boost preregulator circuit allows operation from power sources of 95 to 145 VAC or 200 to 275 VAC. The combination of the boost converter, (boost preregulator) and forward converters with the invention's control scheme enables constant throughput (in watts) during each step of the charging process and a constant pulse width modulation (PWM) duty cycle near maximum at all power levels by varying the output voltage of the boost preregulator in direct relation to the power level. A second forward converter, using the same dynamic balancing of primary currents utilized in the main forward converter described, works with the boost preregulator described to permit integration of a DC to DC converter function with 1 KW (75 A @ 14 VDC) capability plus full safety isolation between the high voltage propulsion batteries and the auxiliary (12 volt) electrical system of the vehicle.

Journal ArticleDOI
TL;DR: A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model.
Abstract: Because of lower voltage levels and smaller power ratings, the R/X ratio of commutation impedance in industrial AC/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects of commutation impedance on converter operations and to precisely relate the fundamental line current and DC output current of the converter, a detailed model of the bridge converter with commutation impedance for use of Newton-Raphson power flow studies in industrial AC/DC power systems is derived in this paper. A coal mine power system and a DC electrified transit railway system with regenerative braking function, a part of Taipei Rapid Transit Systems under planning, have been analyzed to show the improved accuracy and good convergence characteristics of the developed Newton-Raphson power flow formulation with the proposed converter model. >

Journal ArticleDOI
08 Oct 1995
TL;DR: In this paper, a three-phase DC-to-DC series-parallel resonant converter is proposed and its operating modes for a 180/spl deg/ wide gating pulse scheme are explained.
Abstract: A three-phase DC-to-DC series-parallel resonant converter is proposed and its operating modes for a 180/spl deg/ wide gating pulse scheme are explained. A detailed analysis of the converter using a constant current model and the Fourier series approach is presented. Based on the analysis, design curves are obtained and a design example of a 1-kW converter is given. SPICE simulation results for the designed converter and experimental results for a 500-W converter are presented to verify the performance of the proposed converter for varying load conditions. The converter operates in lagging power factor (PF) mode for the entire load range and requires a narrow variation in switching frequency, to adequately regulate the output power.

Journal ArticleDOI
TL;DR: This paper introduces, analyzes, and experimentally verifies a novel DC/DC converter called the current-source parallel-resonant converter, which consists of a large choke inductor, two switches, and a parallel- Resonant circuit.
Abstract: This paper introduces, analyzes, and experimentally verifies a novel DC/DC converter called the current-source parallel-resonant converter. The converter consists of a large choke inductor, two switches, and a parallel-resonant circuit. Each switch consists of a MOSFET in series with a diode. It has a nonpulsating input current with a very low AC ripple. The MOSFETs are driven with respect to ground and, therefore, have a simple gate-drive circuit. The analysis of the converter is carried out in the frequency domain using Fourier series techniques. Analytical expressions are derived for performance parameters of the converter. A prototype of the converter circuit was designed, built, and tested. The theoretical results were in good agreement with the experimental results. >

Patent
14 Jul 1995
TL;DR: In this article, a modified DC-to-AC power converter accomplishes power transfer to a load with electrical isolation, zero-voltage and zero-current switching, using a transformer core resetting mechanism.
Abstract: A modified DC-to-AC power converter accomplishes power transfer to a load with electrical isolation, zero-voltage and zero-current switching, using a transformer core resetting mechanism. The power converter contains two switching devices, a main device connected in parallel and a secondary device connected in series with a transformer primary winding. A secondary winding of the transformer is connected through a two-port resonant link circuit to a resistive load. Zero-voltage switching and proper transformer-core resetting are achieved from the resonance that exists between the parasitic capacitance of the secondary switching device and the magnetization inductance of the transformer. A transformer leakage inductance facilitates zero-current switching; thus, reducing the turn-on switching loss in the conventional main switching device. The switching converter contains a lossless clamping circuit, to limit the voltage stresses across both of the power switching devices to the reflected output voltage appearing across the primary.

Patent
13 Feb 1995
TL;DR: In this paper, a continuous mode full wave power converter topology which integrates the buck-boost (flyback) and buck converter properties is presented. But the voltage transfer function is not characterized.
Abstract: A continuous mode full wave power converter topology which integrates the buck-boost (flyback) and buck converter properties. The voltage transfer function is M = (D/(1-D)), characteristic of the buck-boost (flyback) converter. Characteristic of the full wave buck converter, the inductor current is source continuous during the alternate D intervals, source discontinuous during the simultaneous (1-D) intervals, and load continuous during both the D and (1-D) intervals. A continuous mode full wave power converter topology which integrates the buck-boost (flyback) and buck converter properties. The voltage transfer function is Eout = Ein (D/(1-D)), characteristic of the buck-boost (flyback) converter. Characteristic of the buck converter, the inductor current is source continuous during the alternate D intervals, source discontinuous during the simultaneous (1-D) intervals, and load continuous during both the D and (1-D) intervals.

Patent
27 Apr 1995
TL;DR: In this paper, an analog-to-digital converter calibration method for a charge redistribution analog to digital converter is presented, that includes adjusting an input offset of an input of the analog to the digital converter and adjusting a gain offset of the ADC.
Abstract: A charge redistribution analog-to-digital converter. This converter includes an offset correcting circuit operatively connected in parallel with a capacitor array and responsive to a sampling input of the analog-to-digital converter, and a gain correcting circuit operatively connected in parallel with a sampling capacitor and responsive to the sampling input of the analog-to-digital converter. In another general aspect, an analog-to-digital converter calibration method for a charge redistribution analog-to-digital converter, that includes adjusting an input offset of an input of the analog-to-digital converter and adjusting a gain offset of the analog-to-digital converter. The steps of adjusting are then repeated until a predetermined level of error is achieved for the analog-to-digital converter.

Patent
09 Nov 1995
TL;DR: In this article, a bi-directional converter for transferring electrical energy between a high voltage AC power grid and a DC energy storage/supply (such as a battery or a series of photovoltaic or fuel cells) is presented.
Abstract: A bi-directional converter (i.e., AC- > DC or DC- > AC) for transferring electrical energy between a high voltage AC power grid (12) and a DC energy storage/supply (22) (such as a battery or a series of photovoltaic or fuel cells). The converter includes a PWM inverter (20) coupled to the grid (12), and a DC-DC chopper (21) coupled between the PWM inverter (20) and a DC energy storage/supply (22). The PWM inverter (20) includes a switching circuit (26) having high speed electrical switches arranged in pairs coupled between the AC grid phase voltage rails and DC-DC chopper voltage rails. An inverter control unit (24) includes a DC bus voltage regulator (40) to regulate the voltage on the DC side of the PWM inverter (20), and a reactive power controller (42). A DC control unit (23) includes a real power controller (41) that controls the real power flow by controlling the current flow of the DC energy storage/supply (22). By modulating the DC switches (25) in the DC-DC chopper (21), the DC current to the DC energy storage/supply (22) is controlled to provide a desired real power flow through the DC-DC chopper (21), independent of the voltage (VDC) of the energy storage/supply (22).

Patent
30 Oct 1995
TL;DR: In this article, a multi-channel single-stage high power factor AC to DC converter comprising a pair of input terminals for connecting to an a.c. supply voltage, a bridge rectifier connected across the input terminal, and a D.C. output voltage thereacross.
Abstract: A multi-channel single stage high power factor AC to DC converter comprising a pair of input terminals for connecting to an a.c. supply voltage, a bridge rectifier connected across the input terminal, for converting the a.c. supply voltage to a d.c. voltage, and a D.C. to D.C. converter connected to the bridge rectifier and including a high frequency switch for converting the d.c. voltage to high frequency intermittent pulses, a transformer having a primary winding connected to the high frequency switch and having at least two secondary windings each connected to a respective rectifier for producing a d.c. output voltage thereacross. A pair of capacitors are connected in the input of the DC to DC converter so that when the switch is OPEN a first one of the capacitors receives energy from the a.c. supply and a second one of the capacitors receives energy from the transformer, whilst when the switch is CLOSED the first capacitor restores energy to the transformer and the second capacitor restores charge to the a.c. supply. Such a configuration avoids the need to split the energy transfer capacitor between the input and output of the DC to DC converter and thus avoids duplication of part of the energy transfer capacitor in each output channel when multiple outputs are provided.

Journal ArticleDOI
TL;DR: How the necessity of using a Tri-Level PWM strategy in the current source inverter can be turned into an advantage by producing a voltage boost so that transformers are no longer required is described.
Abstract: The peak line-to-line inverter AC voltage, in general, cannot exceed the supply DC voltage and transformers have to be used when voltage step-up is required. This paper describes how the necessity of using a Tri-Level PWM strategy in the current source inverter can be turned into an advantage by producing a voltage boost so that transformers are no longer required. During the frequent occurrence of the "shoot-through" states, which is the characteristic of the Tri-Level PWM-controlled inverter, magnetic energy builds up in the DC link inductor. At the end of these periods, the L/sub dc/dI/sub dc//dt voltage across the inductor augments the inverter output voltage in the same way as in the basic boost type DC/DC power converter. The paper describes the circuitry required to ensure linear control. Analytical, simulation, and experimental results are given. Applications are found in all instances where the AC voltage is higher than the available supply DC voltage. >