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Hardware‑simulator development and implementation of battery charger for personal mobility devices
Yeongsu Bak 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2
Recently, research on personal mobility devices (PMDs) such as electric motorcycles, electric bikes, electric scooters, and electric wheelchairs has been globally proceeded. However, PMDs have a disadvantage since the required battery voltage is different depending on the type of PMD. Therefore, to charge the battery of a PMD, an individual battery charger should be used depending on type of PMD which reduces industrial usability and availability of PMDs. To solve this problem, a battery charger capable of responding to various battery voltages is required. In this paper, the hardware-simulator development of a battery charger that can respond to the various battery voltages of PMDs is proposed, and it consists of a boost converter, a half-bridge series resonant converter, and a buck converter. Additionally, this paper presents a control strategy for use in the proposed hardware simulator. The effectiveness of the proposed hardware simulator and its control strategy are verified by experimental results.
Yeongsu Bak,Yun Jang,이교범 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
This paper presents an improved torque predictive control (TPC) for permanent magnet synchronous motors (PMSMs) using an indirect matrix converter (IMC). The IMC has characteristics such as a high power density and sinusoidal waveforms of the input-output currents. Additionally, this configuration does not have any DC-link capacitors. Due to these advantages of the IMC, it is used in various application field such as electric vehicles and railway cars. Recently, research on various torque control methods for PMSM drives using an IMC is being actively pursued. In this paper, an improved TPC method for PMSM drives using an IMC is proposed. In the improved TPC method, the magnitudes of the voltage vectors applied to control the torque and flux of the PMSM are adjusted depending on the PMSM torque control such as the steady state and transient response. Therefore, it is able to reduce the ripples of the output current and torque in the low-speed and high-speed load ranges. Additionally, the improved TPC can improve the dynamic torque response when compared with the conventional TPC. The effectiveness of the improved TPC method is verified by experimental results.
Restarting Method for Hydraulic Turbine Generation Systems Applied PMSG Sensorless Control
Yeongsu Bak,Kyo-Beum Lee 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper presents a restarting method for hydraulic turbine generation systems applied permanent magnet synchronous generator (PMSG) sensorless control. The hydraulic turbine generation systems replace a differential pressure control valves (DPCVs) in order to utilize an unused differential pressure (DP) energy in the heat transmission network. The DP control of high-pressure fluids in the heat transmission network is performed through the sensorless control of the PMSG connected to the hydraulic turbine, which is consistently rotated by the high-pressure fluids flowing into the heat transmission network. In these systems, the rotor frequency and position of the PMSG are required for the restarting method. In this paper, the restarting method for the hydraulic turbine generation systems is proposed and it is performed by estimating the rotor frequency and position of the PMSG using the shortcircuit current vectors. The effectiveness of the proposed restarting method is verified by simulation results.
Bak, Yeongsu,Lee, Kyo-Beum The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4
This paper proposes a power conversion system (PCS) to utilize the differential pressure (DP) energy in district heating systems with reduced DC-link voltage variation. A differential pressure control valve (DPCV) is usually used to regulate pressure for heat transmission to remote areas in district heating systems. However, there is a high probability of malfunctions and failures of the DPCV, due to cavitation, since high-pressure fluids are used in district heating systems. Therefore, a PCS for utilizing DP energy in the district heating system replacing the DPCV is proposed in this paper. In addition, the DC-link voltage of the PCS greatly fluctuates when a sudden change occurs in a hydraulic turbine. It is effectively relieved by using the feed-forward control method. The effectiveness of the PCS for utilizing the DP energy in district heating systems with reduced DC-link voltage variation is verified by simulation and experimental results.
Reducing Switching Losses in Indirect Matrix Converter Drives
Yeongsu Bak,Kyo-Beum Lee 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5
This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.
Reducing Switching Losses in Indirect Matrix Converter Drives: Discontinuous PWM Method
Bak, Yeongsu,Lee, Kyo-Beum The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5
This paper presents a discontinuous pulse width modulation (DPWM) method to reduce switching losses in an indirect matrix converter (IMC) drive. The IMC has a number of power semiconductor switches. In other words, it consists of a rectifier stage and an inverter stage for AC/AC power conversion, which are composed of 12 and 6 switching devices, respectively. Therefore, the switching devices of the IMC suffer from high switching losses in the IMC drives. Various topologies to reduce switching losses have been studied by eliminating a number of switches from the rectifier stage. In this study, in contrast to prior research, a DPWM method is presented to reduce the switching losses of the inverter stage. The effectiveness of the proposed method to reduce switching losses in IMC drives is verified by simulations and experimental results.
Bak, Yeongsu,Jang, Yun,Lee, Kyo-Beum The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6
This paper presents an improved torque predictive control (TPC) for permanent magnet synchronous motors (PMSMs) using an indirect matrix converter (IMC). The IMC has characteristics such as a high power density and sinusoidal waveforms of the input-output currents. Additionally, this configuration does not have any DC-link capacitors. Due to these advantages of the IMC, it is used in various application field such as electric vehicles and railway cars. Recently, research on various torque control methods for PMSM drives using an IMC is being actively pursued. In this paper, an improved TPC method for PMSM drives using an IMC is proposed. In the improved TPC method, the magnitudes of the voltage vectors applied to control the torque and flux of the PMSM are adjusted depending on the PMSM torque control such as the steady state and transient response. Therefore, it is able to reduce the ripples of the output current and torque in the low-speed and high-speed load ranges. Additionally, the improved TPC can improve the dynamic torque response when compared with the conventional TPC. The effectiveness of the improved TPC method is verified by experimental results.
Reverse matrix converter control method for PMSM drives using DPC
Bak, Yeongsu,Lee, Kyo-Beum Informa UK (TaylorFrancis) 2018 International journal of electronics Vol.105 No.5
<P>This paper proposes a control method for a reverse matrix converter (RMC) that drives a three-phase permanent magnet synchronous motor (PMSM). In this proposed method, direct power control (DPC) is used to control the voltage source rectifier of the RMC. The RMC is an indirect matrix converter operating in the boost mode, in which the power-flow directions of the input and output are switched. It has a minimum voltage transfer ratio of 1/0.866 in a linear-modulation region. In this paper, a control method that uses DPC as an additional control method is proposed in order to control the RMC driving a PMSM in the output stage. Simulations and experimental results verify the effectiveness of the proposed control method.</P>