Provided is a new control method that causes no time lag or hunting when a power conversion direction is reversed. The power conversion apparatus includes switching elements (S1 and S2) that alternately perform switching and are capable of reversing the power conversion direction without suspension, and an up/down counter register (RT) that has two different thresholds and selects counting up at a smaller threshold, counting down at a larger threshold, and holding of the value between the two thresholds. According to the value of the up/down counter register (RT), a gate pulse is generated to control the switching of the switching elements (S1 and S2).

A stacked voltage source inverter having separate DC sources is described herein. This inverter is applicable to low or medium voltage, low to medium power applications such as photovoltaic utility interface systems, battery storage application such as peak shaving with renewables, motor drive applications and for electric vehicle drive systems. The stacked inverter consists of at least one phase wherein each phase has a plurality of low voltage full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with fast switching and small low pass AC output filter. A system controller controls operating parameters for each inverter. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

A stacked voltage source inverter having separate DC sources is described herein. This inverter is applicable to low or medium voltage, low to medium power applications such as photovoltaic utility interface systems, battery storage application such as peak shaving with renewables, motor drive applications and for electric vehicle drive systems. The stacked inverter consists of at least one phase wherein each phase has a plurality of low voltage full bridge inverters equipped with an independent DC source. This inverter develops a near sinusoidal approximation voltage waveform with fast switching and small low pass AC output filter. A system controller controls operating parameters for each inverter. The inverter may have either single-phase or multi-phase embodiments connected in either wye or delta configurations.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.

A circuit for minimizing energy provided to a ground fault includes a source, a multiple switches, an output filter, and a controller. The switches include a first side pair of switches and a second side pair of switches configured to provide an output signal based on the source. The output filter includes one or more energy storage elements coupled to the first side pair of switches or the second side pair of switches. The controller is configured to receive a ground fault signal that indicates a fault has occurred and configured to generate a switch signal for the switches for a minimum energy state of the output filter and in response to the ground fault signal.

A circuit for minimizing energy provided to a ground fault includes a source, a multiple switches, an output filter, and a controller. The switches include a first side pair of switches and a second side pair of switches configured to provide an output signal based on the source. The output filter includes one or more energy storage elements coupled to the first side pair of switches or the second side pair of switches. The controller is configured to receive a ground fault signal that indicates a fault has occurred and configured to generate a switch signal for the switches for a minimum energy state of the output filter and in response to the ground fault signal.

A bidirectional power supply includes an alternating current (AC) port as a source in a first mode and as a load in a second mode and a line-frequency rectifier/inverter to function as a rectifier in the first mode and a set of switches to function as an inverter in the second mode. A bidirectional resonant converter is coupled to a direct current (DC) port with primary-side switches and secondary-side switches respectively arranged on a primary and secondary side of a transformer. A controller controls the primary-side switches and the secondary-side switches by controlling switching frequency based on a determined value while setting time delay between control of the primary-side and the secondary-side switches to be a predefined time delay or by controlling the time delay between control of the primary-side and the secondary-side switches based on a determined value while setting the switching frequency to be a predefined switching frequency.

A voltage converter system includes a first DC-AC voltage converter that converts a first DC voltage signal to a first AC voltage signal. A DC link converts the first AC voltage signal to a second DC voltage signal. A second DC-AC voltage converter converts the second DC voltage signal to a second AC voltage signal. In another configuration a DC-AC voltage converter converts a DC voltage signal to a first AC voltage signal. An AC-AC voltage converter converts the first AC voltage signal to a second, lower-frequency AC voltage signal. In yet another configuration a first voltage converter portion converts a DC voltage signal to pulses of DC voltage. A second voltage converter portion converts the pulses of DC voltage to a relatively low-frequency AC voltage signal. The voltage converter system is selectably configurable as a DC-AC voltage converter or an AC-DC voltage converter.

A voltage converter system includes a first DC-AC voltage converter that converts a first DC voltage signal to a first AC voltage signal. A DC link converts the first AC voltage signal to a second DC voltage signal. A second DC-AC voltage converter converts the second DC voltage signal to a second AC voltage signal. In another configuration a DC-AC voltage converter converts a DC voltage signal to a first AC voltage signal. An AC-AC voltage converter converts the first AC voltage signal to a second, lower-frequency AC voltage signal. In yet another configuration a first voltage converter portion converts a DC voltage signal to pulses of DC voltage. A second voltage converter portion converts the pulses of DC voltage to a relatively low-frequency AC voltage signal. The voltage converter system is selectably configurable as a DC-AC voltage converter or an AC-DC voltage converter.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.