Jin-Woo Jung

Induction heating (IH) is emerging as a transformative, sustainable, and eco-friendly solution for energy transfer, offering rapid heating, enhanced safety, cleanliness, and automatic pot detection, particularly in domestic induction heating (DIH) appliances. However, the dynamic nature of IH loads poses significant challenges for accurate load parameter identification (LPI) and robust controller design for power management. This review presents a systematic and comprehensive analysis of the LPI and power management techniques in DIH appliances, highlighting recent advancements, challenges, future research opportunities, and recommendations. Unlike existing review literature, which is relatively limited and generally addresses IH, this paper provides a DIH-focused review and organizes DIH control into two major categories: load parameter identification (LPI), which models IH loads (e.g., resistance R_e and inductance L_e) using both online and offline methods; and power management techniques for ferromagnetic appliances (FMAs), non-ferromagnetic appliances (NFMAs), and all-metal appliances (AMAs), differentiated by distinct behaviors they exhibit. By using systematic classification, this paper addresses key gaps and provides a smooth roadmap for readers to understand existing methods and guide future developments in DIH control.

This paper proposes a deadbeat load torque observer (DB-LTO)-based deadbeat direct torque and flux control (DB-DTFC) technique to obtain an enhanced and stable transient response of surface-mounted permanent-magnet synchronous motor (SPMSM) drives. Different from the existing DTFC approaches which control only torque and flux, the proposed DB-DTFC incorporates the speed dynamics for improving the transient control performance. Notably, a DB-LTO is proposed for fast and accurate load-torque estimation while helping to efficiently cope with the system parameter discrepancies and nonlinearities. A mathematical proof of the stability of the proposed DB-LTO-based DB-DTFC strategy is presented via eigenvalue analysis of the closed-loop system. The overall control stability is also verified by appropriately selecting the control design parameters of the proposed observer and controller gains. The proposed strategy is evaluated via extensive experimental investigations using a prototype SPMSM drive equipped with TI-TMS320F28335 digital signal processor (DSP). The improved performance is verified regarding reduction in steady-state error (SSE, from 17% to negligible), less torque ripple up to 67%, overshoot and undershoot elimination (from 25% and 16% to almost 0%), and faster transient response up to 25%, primarily resulting from the proposed DB-LTO and achieved through the enhanced DB-DTFC design under critical load-torque and motor-speed variations with inaccurate model parameters.

This article presents an efficient burst mode control algorithm (BMCA) designed to reduce the turn-on switch current spike in the power control of a single-ended induction heater (SE-IH). Modern SE-IH uses two control modes: square wave control at heavy loads and burst mode control at light loads to effectively control power flow to the induction heating load. First, the former achieves soft switching, i.e., zero voltage switching, at higher load conditions by properly controlling the switching frequency or duty ratio. Second, the latter often encounters inefficiencies and potential hazards due to current spikes at the switch turn-on instant, caused by the sudden discharge of the dc-link capacitor through the resonant capacitor at lower load conditions. These current spikes result in significant power loss and thermal stress, which can ultimately cause the power switch to burn out. This article proposes a novel BMCA that optimizes burst mode operation to significantly reduce current spikes and enhance system reliability and overall power efficiency. The proposed algorithm, thoroughly tested, demonstrates superior performance compared to conventional commercial SE-IHs. Experimental results from a 2.6 kW SE-IH prototype using a TMS320F28377D control board validate the proposed solution’s efficacy under various load conditions.

This article presents a high step-down ripple-free resonant dc/dc converter. By incorporating the stacked T-type half-bridge and center-tapped rectifier structure, it achieved high step-down capability without using a high-turns ratio transformer. By using voltage fluctuation across a T-type half-bridge circuit, hard-switched components are turned off with nearly zero-voltage-switching. Soft-switching capability realizes high switching frequency operation, which brings down the size of the magnetic components. The interleaved active-clamped circuit and corresponding switching modulation with a duty ratio fixed at 0.5 generate ripple-free output current. This aspect ensures no use of extra filter inductor. The use of secondary-side switching hinders the magnetizing current from flowing through the resonant inductor; the core size of the resonant external inductor can remain compact. As a result, the proposed converter features high-voltage step-down, high efficiency, and ripple-free characteristic. To confirm the viability of the design concept, a 1-kW laboratory built prototype is implemented with the input voltage of 400–600 V and the output voltage of 48 V.

This article presents an improved nonlinearities compensation-based control of a single-stage dual transformer-driven resonant ac/dc topology with enhanced reliability. The designed control law incorporates feedforward and feedback terms, whereas the former is designed using state-plane trajectory (SPT) theory to effectively mitigate the system nonlinearities. Likewise, a simple feedback control term handles slowly varying external perturbations, thus realizing excellent steady-state and transient control performances. The primary-side control ensures ripple-free grid current by achieving fully interleaved operation. Next, the secondary-side features a dual rectifier structure with series resonance for improving the efficiency. Power factor correction (PFC) and output voltage regulation, both are performed via the designed control law which is applied on the secondary control switches. The unique controlled operation of the designed topology results in a uniform voltage/heat stress distribution over all the resonant capacitors, the primary-side switches, and the secondary-side switches, thus greatly enhancing the operational reliability. Extensive experimental investigation via 1 kW prototype design and a TMS320F29377D control board corroborates the theoretical findings under practical operating conditions.

This article proposes a bidirectional dual quasi-resonant dc/dc converter (BQRC) that aims to achieve high efficiency and cost-effectiveness with a high-conversion ratio. When transferring the power in the backward direction, the existing converter with conventional switching modulation does not work because single-diode rectification at the primary side disrupts the expected power flow mechanism. To solve this problem, the diagonal pairs of primary-side switches and secondary-side bidirectional switches were modulated complementarily with a fixed duty ratio of 0.5 and the secondary-side half-bridge switches with a variable duty ratio. This approach enables power delivery in the backward direction while achieving a high-conversion ratio, low-component count, and almost zero voltage switching turn-off, which makes the converter highly efficient and cost-effective. Furthermore, in this topology, no magnetizing current flows through the external resonant inductor during backward operation, so the core size of the resonant inductor can be reduced. Consequently, even though the primary-side and secondary-side circuit structures differ, symmetric operations are achieved for power flow in both directions. To demonstrate the viability of this approach, a 400-W prototype was designed and tested, capable of converting a 40–60-V input voltage to a 380-V output.

Fuel cell electric vehicles (FCEVs) offer a promising solution for environment-friendly and sustainable future transportation, thanks to their remarkable features (e.g., zero-carbon emission, high-power capacity, long driving range, etc.). This article extensively reviews all power electronic systems in FCEVs with special emphasis on current implementation status, recent breakthroughs, existing industrial practices, challenges, and prospects. Different from conventional studies, this article provides a more comprehensive, systematic, and organized review of all FCEV systems that can be categorized into three systems: first, fuel cell systems, including fuel cell stack and its nonisolated high-voltage (HV) dc/dc power converter; second, power backup systems, including HV battery and ultracapacitor along with their bidirectional dc/dc power converter and energy management system; and finally, driving systems, including dc/ac inverter, traction motor, regenerative braking system, and low-voltage dc/dc power converter. Finally, future challenging issues, development trends, and prospects are comprehensively discussed.

This paper presents the design, analysis, and control of a dual transformer-based bidirectional DC/DC resonant converter featuring balanced voltage stress across all the resonant capacitors. Compared to existing topologies, the proposed converter has a dual-rectifier structure on the secondary side, which allows operation over a wide load range with balanced voltage stress across all resonant components. The transformer stress is greatly reduced by employing two small transformers, thus greatly lowering thermal as well electrical stresses on the transformers’ windings. Furthermore, by operating the primary-side interleaved converter at a fixed 50% duty, input current ripples are significantly reduced. The proposed controller consists of a feedforward control part for effective system uncertainty compensation and a feedback control part for the convergence of system error dynamics. Notably, state-plane trajectory theory is employed to derive accurate feedforward compensation terms. Additionally, the effect of resonant elements’ parameter mismatch is analyzed in detail. The designed controller was implemented using the TI TMS320F28377D DSP on a 3.3 kW prototype hardware board. Detailed experimental investigations under tough, practical operating conditions corroborate an effective bidirectional power transfer operation with a balanced voltage stress distribution in each resonant element.

This article proposes an improved duty control-based resonant bidirectional dc–dc converter (BDC) to remarkably minimize input-current ripple for battery energy storage systems. The proposed converter offers a resonant-boost operation using a pulsewidth-modulation (PWM) full-bridge circuit with a push-pull transformer under the forward mode. Whereas, in the backward mode, a resonant-buck operation is implemented with a PWM neutral-point-clamped (NPC)-type. Unlike conventional current-fed BDCs, the most appealing characteristic of the proposed converter is the NPC-type structure with a push-pull transformer, which can significantly mitigate the input-current ripple without using extra input-inductors. Moreover, the proposed BDC minimizes the conduction loss of the low-voltage side bottom switches by alleviating unbalanced dc offset-currents via proposed duty-compensation control under mismatched magnetizing inductances of the transformer's primary windings. The designed circuit operation is analyzed in detail and its practicability has been fully confirmed with the proportional-integral and spider-monkey-optimization control techniques-based experimental verifications using a prototype 1-kW test bed.