Interphase Reactor Research Articles

Process intensification of heterogeneous dehydrochlorination of β-chlorohydrins by using n-propanol as co-extractant

The synthesis of terminal epoxides, which are vital components in pharmaceuticals and resins, often involves dehydrochlorination of β-chlorohydrins. Although intrinsic kinetics indicate that the dehydrochlorination reaction in the presence of sodium hydroxide could be very rapid, the practical implementation could always be hindered by long reaction time and low conversion rate. Extended contact between the product and the alkaline solution can lead to hydrolysis of the epoxy group, thus necessitating the process intensification to realize higher production efficiency and selectivity. Here, by characterizing thermodynamic equilibrium data and in-situ recording of the reaction that proceeded in a constant interphase reactor, the heterogeneous dehydrochlorination is demonstrated to occur primarily in the organic phase, and the overall reaction rate depends on the equilibrium concentration of sodium alkoxides. This finding, which is fundamentally different from the traditional view that chlorohydrin is first dissolved in the aqueous phase and then reacts with NaOH, leads us to use inert alcohols to assist in the extraction of NaOH. Based on this method, the reaction time can be reduced over 80 % both in batch and continuous reactors. Besides, the method is demonstrated to be effective in the dehydrochlorination of five different long-chain β-chlorohydrins.

A 40-Pulse Autotransformer Rectifier Based on New Pulse Multiplication Circuit for Aviation Application

In this paper, a new simple pulse multiplication circuit (SPMC) with low current stress is proposed, in order to upgrade a normal 20-pulse autotransformer rectifier (20PAR) to a 40PAR. The proposed SPMC comprises two tapped inter-phase reactors (TIPRs) and two additional diodes with lower conduction losses. The proposed SPMC does not require a zero-sequence blocking transformer (ZSBT) compared to conventional pulse multiplication circuits, which leads to simplicity in implementation. Simulation and experimental results show that the total harmonic distortion (THD) of the input current using 40PAR is less than 3%, which meets the DO-160G requirements for aviation applications.

A Simple 24-Pulse Star Rectifier Combining Two Different Tap Converters

To further improve the harmonic mitigation capability of the double-star rectifier, a simple 24-pulse star rectifier using a conventional tap converter (CTC) and an improved tap converter (ITC) is proposed. The proposed rectifier comprises two double-star rectification units, a CTC, an ITC and an interphase reactor (IPR). The CTC and ITC first expand the double-star rectifiers into 12-pulse rectifiers, and provide a phase shift of 15°, then connect through an IPR to achieve the effect of quadrupling the number of pulses. This configuration solves the problem of limited pulse multiplication capability (pulse multiplication number≤3) of the existing passive tap converter, and upgrades the double-star rectifier to a novel 24-pulse star rectifier. The resulting rectifier shows an approximately sinusoidal input current with the absence of the 5th, 7th, 17th and 19th harmonics. The proposed scheme has the advantages of simple structure, small size, and being economically justified because the proposed scheme does not change the structure of the double-star transformer, and the capacity of CTC and ITC is only 3.49% and 6.29% of the output power, respectively. An experimental prototype with an output power of 1 kW is built to verify the correctness of the theoretical analysis.

Input Current Step-Tripling for 12-Pulse Rectifier Using a Passive Four-Tap Changer

To effectively suppress the input line current harmonics of a 12-pulse rectifier under slightly complex hardware, this article proposed an input line current step-tripling scheme for a 12-pulse rectifier using a novel passive four-tap changer (FTC). The proposed FTC consists of a retrofitted four-tap interphase reactor (RFT-IPR) and four auxiliary diodes. Two auxiliary diodes are connected to the inner taps of the RFT-IPR, but the other two auxiliary diodes are connected to the outer taps of the RFT-IPR. The inner and outer auxiliary diodes modulate and increase the output current states of the rectifier bridges together first; then, the FTC extends the 12-step to 36-step input line current, and the near sinusoidal input current with 3% THD is obtained. The proposed FTC not only has a very low capacity (2.6% of the output power) but also does not require any active switching device aside from four auxiliary diodes; thus, the proposed scheme is a cost-effective, reliable, and efficient solution to harmonics pollution. An experimental prototype with an output power of 2.4 kW is built, and the correctness of the theoretical analysis is verified by the experimental results.

Research on the DC-Side Passive Harmonic Reduction Methods of the Ultramultiphase Parallel-Connected Multipulse Rectifier

The interphase reactor (IPR) is one of the most important components of the passive harmonic reduction circuit (HRC), and the optimum turns ratio design of the IPR is of great significance to ensure the effect of the passive HRC. In combination with the pulse number multiplication methods, the configuration of the multipulse rectifiers (MPRs) with single/dual/triple-passive HRCs are constructed, respectively. The general optimum turns ratio design method for the IPRs is proposed, which contains most of the realizable combinations of the HRCs. The relationship between the turns ratio of the IPR and the phase number of the bridge rectifier in the main circuit is established, the influence of the turns ratio selection on the power quality of the MPRs is presented. In addition, this article takes <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> equal to five as an example to verify the effectiveness of the proposed general optimum turns ratio design method of IPR. The power quality of the MPRs with different HRCs or phase number are compared. All the research can provide a useful guideline and theoretical foundation for the MPR selection and the HRC design under the specific occasions.

A Parallel-Connected 24-Pulse Rectifier Using Hybrid Harmonic Reduction Method at DC Side

This letter proposes a parallel-connected 24-pulse rectifier using a hybrid harmonic reduction method at the dc side. The proposed rectifier contains an unconventional interphase reactor (UIPR) with a double-tapped primary winding and secondary winding connected pulsewidth modulation converter. The proposed method is a combination of the passive and active harmonic method. From the viewpoint of total harmonic distortion (THD) of the input line current, ripple load voltage, and kilovoltampere rating of the active auxiliary circuit, the UIPR and active injecting current are optimally designed. An experimental prototype is developed to verify the theoretical analysis. The experimental THD is about 2.87%, which shows good performance of harmonic reduction.

Input Current Step-Doubling for Autotransformer-Based 12-Pulse Rectifier Using Two Auxiliary Diodes

To significantly decrease the input line current total harmonic distortion (THD) under simple circuit configuration conditions, this article propose an input current step doubling scheme for autotransformer-based 12-pulse rectifier using two auxiliary diodes. The auxiliary diodes are installed between the two retrofitted double-tap interphase reactors, and they inject specific square wave currents to increase the output current states of the rectification bridges. This modification extends the 12-step input line current to a 24-step input line current, and the near sinusoidal input line current with THD below 5% is obtained. As the proposed scheme only requires two low current stress (3.4% <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) auxiliary diodes, it achieves high-cost performance, is easy to implement and has a simple circuit configuration. A 2.2 kW simulation and experimental prototype is built to verify the theoretical analysis.

Multi-Pulse Rectifier Based on an Optimal Pulse Doubling Technique

This paper presents pulse multiplication technology based on an optimal Pulse Doubling Technique (PDT) to upgrade a 28-Pulse Rectifier (28-PR) to a 56-PR. The optimal PDT comprises a Tapped Interphase Reactor (TIPR) with a low kVA-rating and two diodes. The number of pulses can be increased from 28 to 56 using the PDT so that the input current harmonics are reasonably mitigated. Additionally, the 14-phase Polygon-Connected Autotransformer (PCA) is designed in such a way that it can be used for retrofit applications. A detailed simulation analysis in the MATLAB/Simulink environment is carried out, and the results show that the improved quality indices of the final AC input and DC output power are equivalent to the IEEE 519-2014 standard and meet sensitive industrial application requirements with an input current Total Harmonic Distortion (THD) lower than 3%. Moreover, the power factor also maintained unity for a wide operating range. The optimal PDT scheme is affordable and easy to implement as only a small-capacity PDT (only 1% of the output power) is needed to double the pulse number. An experimental prototype is developed to verify the simulation results.

A Simple 18-Pulse Star Rectifier Using Two Passive Auxiliary Circuits at DC Link

In this article, a simple 18-pulse star rectifier using two new passive auxiliary circuits at dc link is proposed for reducing the harmonics content in ac line current. The proposed rectifier combines a double-star rectifier and four-tapped interphase reactor (FTIPR) with four diodes. Passive auxiliary circuits increase the state of the output voltage and current of the double-star rectifier, thereby increasing the pulse number of the load voltage and step number of the input line current. When FTIPR is optimally designed, passive auxiliary circuits convert double-star rectifier to 18-pulse star rectifier. Tap ratios of the FTIPR are determined based on minimum total harmonic distortion (THD) of the input line current and minimum ripple of the output voltage. The proposed rectifier simultaneously reduces ripple of the output voltage and THD of the input line current. A prototype is developed to verify the theoretical analysis through experimental results. Theoretical THD of the input line current is about 10.1%, whereas experimental THD is about 5.44%.

A Novel Parallel Configured 48-Pulse Auto-Transformer Rectifier for Aviation Application

To satisfy the ever-growing stringent requirement on the power quality of on-board electric power system, a novel parallel configured 48-pulse rectifier, which is formed by two 24-pulse rectifiers connected in parallel through a tapped and coupled interphase reactors respectively, is proposed. Through the comprehensive harmonic analysis on the proposed rectifier, it is revealed that the 23rd and 25th harmonics generated by the two 24-pulse rectifiers are equal in magnitude while opposite in direction, which evidently enables the 48-pulse operation. To better understand the performances of the proposed rectifier, its input current, output voltage, kVA rating, and power losses of magnetic devices are analyzed in detail. Afterward, the validity of the theoretical analysis is verified by simulation and experiment. The results confirm that the proposed 48-pulse rectifier has superior harmonic reduction ability, high reliability, and high power density. More importantly, due to the parallel structure, it also features high fault-tolerant ability, which makes it very suitable for aviation or aerospace applications.

A Simple 36-Pulse Diode Rectifier With Hybrid Pulse Multiplication Interphase Reactor at DC Side

A simple and robust 36-pulse diode rectifier which consists of a conventional 12-pulse rectifier and a hybrid pulse multiplication interphase reactor (HPM-IPR) is proposed in this article. The HPM-IPR includes a modified interphase reactor (M-IPR), an auxiliary single-phase full-bridge rectifier (ASFBR), and an auxiliary single-phase full-wave rectifier (ASFWR). The ASFBR is connected in series with the load to modulate the output current of the rectifier bridges directly. The ASFWR is connected in parallel to shape the output current of the rectifier bridges indirectly. The conjoint modulation of ASFWR and ASFBR significantly increases the number of output current states of the rectifier bridge, which in turn extends the conventional 12-pulse operation to 36-pulse operation. The proposed 36-pulse diode rectifier draws near the sinusoidal input line currents with THD less than 5%. The kVA ratings of ASFBR and ASFWR are only 1.1% and 1.8% of the output power of the proposed rectifier, respectively, which indicates that the proposed method is suitable for high-power industrial applications. Since only one ASFWR and one ASFBR are adequate, the proposed scheme is low cost, highly reliable, and simple. The detailed analysis is presented, and some experimental results are provided to verify the proposed method.

Comparative analysis of two different interphase reactors applied in 36‐pulse diode rectifier

This study presents a comparative analysis of two different interphase reactors (IPRs) applied in a 36-pulse diode rectifier. One is traditional triple-tapped IPR; the other is unconventional IPR (UIPR) composed of the primary winding and secondary winding. The primary winding is double-tapped conventionally and the secondary winding is connected with a single-phase full-wave rectifier. The operation modes and optimal parameters of both IPRs are analysed. The effect of different operation modes on output currents of the two three-phase diode-bridge rectifiers, input currents and load voltages is also analysed. Under the optimal parameters, both rectifiers operate as 36-pulse diode rectifiers and reduce the total harmonic distortion of input line currents to be 5%. Especially, the proposed rectifier using UIPR is easy and simple to implement. Some experiments are provided to validate the theoretical analysis.

Dual Passive Harmonic Reduction at DC Link of the Double-Star Uncontrolled Rectifier

This letter proposes a novel multipulse rectifier. The proposed rectifier is a combination of a novel dual-passive-harmonic-reduction method and a traditional double-star uncontrolled rectifier. The proposed method contains a multiwinding interphase reactor (IPR) and the corresponding auxiliary circuit. From the viewpoint of minimizing the total harmonic distortion (THD) of the input line current, the turn ratio of the multiwinding IPR is optimally designed. Under the optimal turn ratio, the proposed rectifier operates as an 18-pulse rectifier. Its theoretical THD of the input line current is about 10.1%, and its experimental THD is 6.58%. The proposed method is simple and easy to realize.

A 36-Pulse Diode Rectifier with an Unconventional Interphase Reactor

This paper proposes a simple 36-pulse diode rectifier with an unconventional interphase reactor (IPR) and single-phase full-wave rectifier (SFR). The primary winding of the unconventional IPR is double tapped and the secondary winding is connected with SFR. The operation mode of the unconventional IPR is analyzed, and the optimal tap ratio and turn ratio of the unconventional IPR are designed from both viewpoints of input line current and load voltage. With the optimal parameters of the unconventional IPR, the proposed rectifier extends the conventional 24-pulse rectifier operation to 36-pulse operation and draws near sinusoidal input line currents, the total harmonic distortion (THD) of which is about 5.035%. The kVA rating of the unconventional IPR is about 2.6% of the output power. Compared with the conventional 36-pulse rectifier with triple-tapped IPR, the proposed 36-pulse rectifier is easy and simple to implement instead of using control circuits. Experiment results are provided to verify the theoretical analysis.

A 36-Pulse Diode-Bridge Rectifier Using Dual Passive Harmonic Reduction Methods at DC Link

In order to simultaneously reduce the harmonics of input line current and ripple of load voltage in multipulse diode-bridge rectifier, this paper proposes a 36-pulse rectifier using dual passive harmonic reduction methods at dc link. The proposed rectifier combines a 12-pulse rectifier and a multiwinding interphase reactor (IPR). The primary winding of the multiwinding IPR and two diodes constitute the double-tapped IPR, which is named as the first harmonic reduction method; the secondary winding of the multiwinding IPR and a single-phase diode-bridge rectifier formulate the second harmonic reduction method. When the multiwinding IPR is designed optimally, the pulse number of load voltage and step number of input line current can be increased from 12 to 24 by using the first method and from 24 to 36 by using the second method. The operation of the multiwinding IPR is analyzed, and the optimal turn ratio of the multiwinding IPR is obtained from the perspective of minimizing the total harmonic distortion of input line current. When the multiwinding IPR is designed optimally, both the pulse number of load voltage and step number of input line current are 36 per power supply cycle. Compared with the 12-pulse rectifier, in the proposed rectifier, the harmonics of input line current and ripple of load voltage are reduced significantly. The proposed rectifier is simpler and easier to realize than other methods. Some simulation and experiments are carried out to validate the theoretical analysis.

Optimum Design of 48-Pulse Rectifier Using Unconventional Interphase Reactor

In order to simultaneously reduce the harmonics of input line current and ripple of load voltage in multipulse rectifier, this paper proposes a 48-pulse rectifier using the unconventional interphase reactor (IPR) with an auxiliary single-phase diode-bridge rectifier at the dc link. The primary winding of the unconventional IPR is triple-tapped, and the secondary winding is connected with a single-phase diode-bridge rectifier. The operation mode of the unconventional IPR is analyzed, and the optimal tap ratio and turn ratio are designed. With the optimal parameters of the IPR and the optimal conduction time sequence of power devices, the proposed rectifier extends the conventional 36-pulse rectifier operation to a 48-pulse operation and draws near sinusoidal input line currents, the total harmonic distortion (THD) of which is about 3.81%. The proposed 48-pulse rectifier is easy and simple to implement, and it is more suitable for high-voltage and large-current application. Some simulation and experiments are provided to validate the theoretical analysis.

A Simple Harmonic Reduction Method in Multipulse Rectifier Using Passive Devices

This paper proposes a novel and passive harmonic reduction method at dc link of multipulse rectifier (MPR). The proposed method uses a single-phase diode-bridge rectifier to generate circulating current, which can shape the input line current of MPR. The input side of the single-phase diode-bridge rectifier is connected with the secondary winding of interphase reactor (IPR), and its output side is connected with load, which can recycle the harmonic energy and feed to load. The operation mode of the single-phase diode-bridge rectifier is analyzed, and the turn ratio of the IPR is designed optimally. Under ideal condition, the proposed MPR operates as a 24-pulse rectifier, and its total harmonic distortion (THD) of input line current is about 7.6%. Most of all, the proposed method is easy to be used in different 12-pulse rectifier topologies, and its conduction losses are far less than that of the conventional double-tapped IPR. Simulation and experiment results show that the THD of input line current is less than 5%.

Effects of leakage inductance on the input current of double star diode rectifier with active inter-phase reactor

An active inter-phase reactor（AIPR）is often employed to inject triangle current to improve the input current quality of double star diode rectifier. Due to the existed leakage inductance of transformer, the input current harmonics suppression ability of the injected triangle current would be weaken. In this paper, the current commutation process of the double star diode rectifier with AIPR is analyzed initially. Then, according to the relation between the input current and output current of the double star transformer, the relation between the leakage inductance and the input line current of double star diode rectifier with AIPR is established. Such factors like the input current THD, the input current lag angle and power factor of the double star diode rectifier with AIPR, their relations with the leakage inductance are also obtained. The theoretical analysis demonstrate that the leakage inductance increase the input current THD and lag angle. It indicates that the leakage inductance decrease the displacement factor and power factor. To ensure the input current THD is less than 5% and the power factor is more than 0.998, the leakage inductance factor KLs should be less than 0.22. Simulation results verify the theoretical analysis.

Delta/Fork-Connected Transformer-Based 72-Pulse AC–DC Converter for Power Quality Improvement

ABSTRACTThis paper presents a delta/fork-connected transformer-based 72-pulse AC–DC converter feeding direct torque-controlled induction motor drives (DTCIMDs) for improving power quality. The proposed converter consists of two paralleled 18-pulse AC–DC converters along with pulse-doubling circuit at DC bus. The pulse-doubling circuit is used in achieving the pulse multiplication in a 36-pulse AC–DC converter. The Thirty-six pulse topology is obtained via two paralleled 18-pulse AC–DC converters each of them consisting of a 9-phase (9-leg) diode-bridge rectifier. The design of proposed magnetics shows the flexibility in varying the voltage ratio of the delta/fork-connected transformer for making it suitable for retrofit applications where a 6-pulse diode-bridge rectifier is being utilized. Independent operation of paralleled diode-bridge rectifiers, i.e. DC-ripple re-injection methodology, requires a Zero Sequence Blocking Transformer (ZSBT). Finally, a tapped interphase reactor is connected at the output of ZSBT to double the pulse numbers of output voltage up to 72 pulses. The proposed 72-pulse AC–DC converter with the DTCIMD has been implemented and simulated using Matlab/Simulink software. Simulation results confirmed the significant improvement of the power quality indices on input AC mains and on DC bus (consistent with the IEEE-519 standard requirements) at the point of common coupling. Also, a laboratory prototype is implemented using the proposed design and the experimental results confirm the simulation results at various loads. Results show that input current total harmonic distortion (THD) is less than 3% for the proposed 72-pulse topology at variable loads. Furthermore, near unity power factor is obtained for a wide operating range of the drive.

Active Current Sharing Control Method for Rotating Thyristor Rectifiers on Brushless Dual-Star Exciters

A new high-speed-response dual-star brushless rotating exciter has been recently proposed, which utilizes two rotating thyristor rectifiers in a hybrid-mode topology. However, dissymmetries tend to occur in large-scale apparatus, which ultimately results in an undesired unbalanced loading of the topology. Moreover, the topology provides a possibility for compensation via asymmetrical firing, which serves as a promising solution to be investigated. This letter proposes an active current sharing adjustment method between the parallel thyristor bridges. The method improves controllability and performance compared with the alternative “skip firing” approach, and it can replace the interphase reactors in large direct current applications.