Jun Asakura

State-of-Charge (SOC)-Balancing Control of a Battery Energy Storage System Based on a Cascade PWM Converter

Renewable energy sources such as wind turbine generators and photovoltaics produce fluctuating electric power. The fluctuating power can be compensated by installing an energy storage system in the vicinity of these sources. This paper describes a 6.6-kV battery energy storage system based on a cascade pulsewidth-modulation (PWM) converter with focus on a control method for state-of-charge (SOC) balancing of the battery units. A 200-V, 10-kW, 3.6-kWh (13-MJ) laboratory system combining a cascade PWM converter with nine nickel metal hydride (NiMH) battery units is designed, constructed, and tested to verify the validity and effectiveness of the proposed balancing control.

Fault-Tolerant Operation of a Battery-Energy-Storage System Based on a Multilevel Cascade PWM Converter With Star Configuration

This paper focuses on fault-tolerant control for a battery-energy-storage system based on a multilevel cascade pulsewidth-modulation (PWM) converter with star configuration. During the occurrence of a single-converter-cell or single-battery-unit fault, the fault-tolerant control enables continuous operation and maintains state-of-charge balancing of the remaining healthy battery units. This enhances both system reliability and availability. A 200-V, 10-kW, 3.6-kW·h laboratory system combining a three-phase cascade PWM converter with nine nickel-metal-hydride battery units is designed, constructed, and tested to verify the validity and effectiveness of the proposed fault-tolerant control.

A transformerless battery energy storage system based on a multilevel cascade PWM converter

Renewable energy sources such as wind turbine generators and photovoltaics produce a fluctuating electric power. A battery energy storage system (BESS) should be installed in the vicinity of these sources. The fluctuating power is compensated by appropriately controlling an active power stored in the battery. This paper describes a feasible circuit configuration of a 6.6-kV transformerless battery energy storage system based on a multilevel cascade PWM (pulse-width-modulation) converter, with focus on a control method for active power and SOC (state-of- charge) balancing. A 200-V, 10-kW, 3.6-kWh (13-MJ) laboratory system combining a multilevel cascade PWM converter with nine NiMH (nickel metal hydride) battery units is designed, constructed, and tested to verify the viability and effectiveness of the 6.6-kV system.