PaperlayerView exact revision on arXiv

Source-linked AI summary

A Three-phase and Single-phase Compatible Dual-Mode EV On-Board Charger with Integrated Active Power Decoupling

Bitan Joydhar, Shimul K. Dam

arXiv:2609.00822v1eess.SY

TL;DR

Single-phase OBC operation creates double-frequency DC-link ripple and can require bulky capacitance. The paper proposes a dual-mode rectifier that reuses the third leg for active power decoupling, with simulations showing much smaller capacitance and faster response.

  • Problem

    Single-phase OBCs experience double-line-frequency ripple, requiring bulky DC-link capacitance that reduces power density and lifetime.

  • Method

    The proposed dual-mode OBC uses one relay and a small capacitor to repurpose the redundant third half-bridge for active power decoupling during single-phase operation.

  • Results

    3 mF DC-link capacitance is required without APD, versus a 100 µF DC-link capacitor with APD in the reported single-phase simulation.

  • Takeaways & Limitations

    The proposed topology offers a smaller dual-mode OBC while supporting both three-phase and single-phase charging.

Abstract

from arXiv · show

Onboard charger (OBC) is essential part of Electric Vehicle (EV). High-performance EVs are preferring three phase charging to achieve higher power level. However, the ability to charge from a single phase supply is also required. A dualmode OBC for EVs is proposed, which is capable of operating from both three-phase supply and single-phase supply. The single phase charging comes with the requirement of bulky DC link capacitance due to double frequency current in DC link. The proposed topology eliminates this by achieving Active Power Decoupling (APD) using only one additional relay switch and a small capacitor. The proposed topology is verified under different conditions in a detailed simulation, which shows more than an order of magnitude reduction in DC link capacitance during single phase operation.

I. INTRODUCTION

The paper motivates a dual-mode OBC that supports both three-phase and single-phase charging while addressing the bulky DC-link capacitance required by single-phase operation.

  • The work focuses on the front-end converter, whose power-factor correction function influences overall efficiency and power density; the isolated DC-DC stage is outside scope.
  • Single-phase OBCs experience double-line-frequency power pulsation that produces 100 Hz DC-link ripple.
  • Electrolytic capacitors used to reduce this ripple decrease OBC power density and shorten lifetime.
  • Three-phase charging provides higher power and nearly constant instantaneous input power, but single-phase compatibility remains necessary where three-phase supply is unavailable.
  • Existing dual-mode OBCs may require separate circuits, additional switches or auxiliary circuits, and different modulation and control strategies.
  • The proposed OBC uses the redundant third half-bridge for active power decoupling during single-phase charging, requiring only one relay switch and a small capacitor.

II. PROPOSED TOPOLOGY

The proposed topology modifies a conventional three-phase voltage-source boost rectifier with a relay-connected auxiliary capacitor to enable single-phase active power decoupling.

  • II. PROPOSED TOPOLOGY: The topology combines a conventional three-phase rectifier with a small modification for active power decoupling during single-phase operation.
  • II. PROPOSED TOPOLOGY: The rectified DC voltage feeds a DC/DC converter that charges the EV battery, while this work focuses on the rectifier circuit.
  • II. PROPOSED TOPOLOGY: An additional capacitor, CAPD, connects to one phase input terminal through a relay or contactor.
  • II. PROPOSED TOPOLOGY: The modified rectifier can operate as a single-phase rectifier with active power decoupling and can be retrofitted to an existing three-phase rectifier.

B. Proposed OBC in Three-Phase Mode

The converter uses all three half-bridge legs for conventional three-phase rectification, while single-phase operation repurposes the third leg for active power decoupling.

  • B. Proposed OBC in Three-Phase Mode: In three-phase mode, all three half-bridge legs connect to the three-phase supply and relay K remains open.
  • B. Proposed OBC in Three-Phase Mode: All six semiconductor switches participate in the three-phase rectification process.
  • C. Proposed OBC in Single-Phase Mode: In single-phase mode, two converter legs form the AC-DC rectifier while the unused third leg becomes the APD circuit.
  • C. Proposed OBC in Single-Phase Mode: The APD circuit consists of the third leg, input inductor, relay, and additional capacitor, diverting double-line-frequency ripple energy from Cdc to CAPD.

III. OPERATIONS AND MODULATION

The paper describes SPWM-based operation and component design for the three-phase PWM rectifier, including modulation, inductance, and DC-link capacitance selection.

  • A. Three Phase Operation: The three-phase PWM rectifier uses sinusoidal PWM with third-harmonic injection.
  • A. Three Phase Operation: The modulation index is selected from the required AC input voltage and DC output voltage.
  • A. Three Phase Operation: Input inductance is designed from the desired current ripple and switching frequency.
  • A. Three Phase Operation: The DC-link capacitor is designed according to the permissible DC-link voltage ripple.
  • A. Three Phase Operation: The modulation-index relation defines m using Vm as peak input voltage and Vo as required output voltage.
  • A. Three Phase Operation: The boost-operation duty ratio is denoted by D.

B. Single phase rectifier without Active Power Decoupling Circuit

In single-phase mode, the shared converter uses two legs for rectification, but double-line-frequency power pulsation requires substantially more DC-link capacitance.

  • B. Single phase rectifier without Active Power Decoupling Circuit: The same hardware and sinusoidal PWM control are used for single-phase operation, with fixed input inductance inherited from three-phase design.The two input inductors are effectively connected in series in single-phase mode.
  • B. Single phase rectifier without Active Power Decoupling Circuit: Double-line-frequency power pulsation makes the required single-phase DC-link capacitance much larger than in three-phase operation.The existing three-phase DC-link capacitor remains connected, but the single-phase ripple requirement makes it bulky.
  • B. Single phase rectifier without Active Power Decoupling Circuit: The instantaneous-power and capacitance equations relate ripple power and allowable DC-link voltage ripple to the minimum bus capacitance.The equations assume sinusoidal input voltage and current with unity power factor.
  • B. Single phase rectifier without Active Power Decoupling Circuit: An active power decoupling circuit is proposed to reduce the capacitance needed to absorb double-line-frequency output power.The unused converter leg is assigned the APD function in single-phase operation.

C. Single phase rectifier with Active Power Decoupling Circuit

The APD branch uses the otherwise unused third converter leg to buffer double-line-frequency ripple energy in an auxiliary capacitor, reducing stress on the main DC-link capacitor.

  • C. Single phase rectifier with Active Power Decoupling Circuit: The APD circuit operates bidirectionally, transferring excess instantaneous input energy to the auxiliary capacitor and returning it to the DC link later.The main DC-link capacitor therefore primarily supports average-power transfer and DC-link-voltage regulation.
  • C. Single phase rectifier with Active Power Decoupling Circuit: The ripple-energy formulation determines the auxiliary capacitor’s required energy-buffering capability.The APD capacitor voltage varies between defined maximum and minimum values.
  • C. Single phase rectifier with Active Power Decoupling Circuit: The APD capacitor-voltage dynamics connect capacitor voltage, converter modulation, and ripple power for control design.The maximum APD-capacitor voltage is denoted Vmax, while Vdc denotes nominal DC-link voltage.
  • C. Single phase rectifier with Active Power Decoupling Circuit: The duty ratio of the third converter leg is determined from the APD capacitor-voltage equations.The selected duty cycle controls the auxiliary branch’s power-buffering operation.

IV. SIMULATIONS

PLECS simulations evaluate the proposed converter under specified design parameters and three-phase operating conditions, including output regulation, input waveforms, and switch stresses.

  • IV. SIMULATIONS: The proposed topology is simulated in PLECS using converter specifications listed in Table I.The simulation study uses the stated design parameters and ratings as its operating basis.
  • IV. SIMULATIONS: 26µF bus capacitance meets the specified 1% output-voltage ripple with a 1mH grid-side inductor.A 36 Ω load resistance is connected at the output to draw rated power.
  • IV. SIMULATIONS: Three-phase simulations present output power, output voltage/current, and three-phase input voltage/current waveforms.The corresponding waveform set is shown in Fig. 7.
  • IV. SIMULATIONS: Switch voltage and current stresses during three-phase operation are shown in Fig. 8.The figure focuses on semiconductor stress under the simulated operating condition.

B. Single phase rectifier without APD

Without APD, single-phase operation requires a bulky 3mF DC-link capacitor and produces slower transient response, while maintaining unity power factor in simulation.

  • B. Single phase rectifier without APD: 3mF is the minimum bus capacitance required for the specified single-phase operating condition without APD.The unused third converter leg remains unavailable for power decoupling in this case.
  • B. Single phase rectifier without APD: The single-phase input-voltage and current waveforms verify unity power factor operation without APD.Fig. 9 reports 3.5% input-current THD.
  • B. Single phase rectifier without APD: The single-phase transient response is considerably slower, delaying output-power convergence to its steady-state value.A 109 Ω output resistance is used to draw the specified power.
  • B. Single phase rectifier without APD: The output-voltage waveform without APD has 6V ripple under the 3mF DC-link-capacitance condition.This condition is represented in Fig. 10.

C. Single phase rectifier with APD

Simulation of single-phase APD operation uses small capacitances while maintaining power-quality and output-voltage performance. APD also substantially accelerates the output-power response.

  • Single-phase APD performance: 82µF APD capacitance and 100µF DC-link capacitance produce 3.6% input-current THD and 6V output-voltage ripple.The simulation verifies unity power factor under single-phase APD operation.
  • Single-phase APD performance: The APD output-power response reaches steady state significantly faster than the approximately 4s response without APD.Figure 14 compares the slower no-APD response with the faster APD response.
  • Simulation conditions: Single-phase input voltage and current are simulated with Cdc = 100µF and CAPD = 82µF.The corresponding simulated input-current THD is 3.6%.
  • Simulation conditions: The simulated output voltage during APD operation has Cdc = 100µF, CAPD = 82µF, and ∆Vo = 6V.These parameters define the output-voltage simulation condition.

V. CONCLUSIONS

The proposed OBC supports both three-phase and single-phase charging using a relay, a small capacitor, and the redundant third leg for active power decoupling. Simulations meet the stated performance criteria with far less DC-link capacitance than operation without APD.

  • Conclusions: 10kW three-phase and 3.3kW single-phase charging are designed for a 600V dc bus.A PLECS simulation model verifies converter operation and the control strategy.
  • Conclusions: 1% output-voltage ripple and maximum 5% input-current THD are achieved using 100µF DC-link and 82µF APD capacitances.These results are reported for the proposed simulated converter.
  • Conclusions: The proposed topology enables dual-mode charging with one relay switch and a small capacitor added to a conventional three-phase rectifier.The redundant third leg provides active power decoupling during single-phase charging.
  • Conclusions: The required DC-link capacitance is drastically lower than 3mF without APD for the same performance criteria.The paper concludes that this produces a significantly smaller dual-mode OBC.
Loading 2609.00822v1…