A control method of a three-phase multi-level inverter includes: determining a modulation ratio based on output of the three-phase multi-level inverter, where the modulation ratio indicates a ratio of an amplitude value of a sinusoidal modulation wave in pulse width modulation to an amplitude value of a carrier; generating, based on the modulation ratio and a modulation ratio threshold, a common-mode voltage regulation signal for regulating a common-mode voltage in phase voltages of the three-phase multi-level inverter; adding the common-mode voltage regulation signal and a differential-mode voltage regulation signal for regulating a differential-mode voltage in the phase voltages of the three-phase multi-level inverter to obtain a composite regulation signal, where the composite regulation signal is presented as a modulation wave for discontinuous pulse width modulation (DPWM); and generating, based on the composite regulation signal, drive signals for controlling switches of phases of the three-phase multi-level inverter.

A control method of a three-phase multi-level inverter includes: determining a modulation ratio based on output of the three-phase multi-level inverter, where the modulation ratio indicates a ratio of an amplitude value of a sinusoidal modulation wave in pulse width modulation to an amplitude value of a carrier; generating, based on the modulation ratio and a modulation ratio threshold, a common-mode voltage regulation signal for regulating a common-mode voltage in phase voltages of the three-phase multi-level inverter; adding the common-mode voltage regulation signal and a differential-mode voltage regulation signal for regulating a differential-mode voltage in the phase voltages of the three-phase multi-level inverter to obtain a composite regulation signal, where the composite regulation signal is presented as a modulation wave for discontinuous pulse width modulation (DPWM); and generating, based on the composite regulation signal, drive signals for controlling switches of phases of the three-phase multi-level inverter.

Systems and methods of this disclosure use low voltage energy storage devices to supply power at a medium voltage from an uninterruptible power supply (UPS) to a data center load. The UPS includes a low voltage energy storage device (ultracapacitor/battery), a high frequency (HF) bidirectional DC-DC converter, and a multi-level (ML) inverter. The HF DC-DC converter uses a plurality of HF planar transformers, multiple H-bridge circuits, and gate drivers for driving IGBT devices to generate a medium DC voltage from the ultracapacitor/battery energy storage. The gate drivers are controlled by a zero voltage switching (ZVS) controller, which introduces a phase shift between the voltage on the primary and secondary sides of the transformers. When the primary side leads the secondary side, the ultracapacitor/battery discharges and causes the UPS to supply power to the data center, and when the secondary side leads the primary side, power flows from the grid back to the UPS, thereby recharging the ultracapacitor/battery.

Systems and methods of this disclosure use low voltage energy storage devices to supply power at a medium voltage from an uninterruptible power supply (UPS) to a data center load. The UPS includes a low voltage energy storage device (ultracapacitor/battery), a high frequency (HF) bidirectional DC-DC converter, and a multi-level (ML) inverter. The HF DC-DC converter uses a plurality of HF planar transformers, multiple H-bridge circuits, and gate drivers for driving IGBT devices to generate a medium DC voltage from the ultracapacitor/battery energy storage. The gate drivers are controlled by a zero voltage switching (ZVS) controller, which introduces a phase shift between the voltage on the primary and secondary sides of the transformers. When the primary side leads the secondary side, the ultracapacitor/battery discharges and causes the UPS to supply power to the data center, and when the secondary side leads the primary side, power flows from the grid back to the UPS, thereby recharging the ultracapacitor/battery.

A power converter includes an unfolder connected to a three-phase source and has an output connection with three output terminals. A three-input converter connected to the unfolder produces a quasi-sinusoidal output voltage across converter output terminals. Switches of the converter selectively connect each of the three output terminals across the converter output terminals. A pulse-width modulation controller controls a first duty ratio and a second duty ratio for the converter based on a phase angle of the source and a modulation index generated from an error signal related to a control variable. The duty ratios are time varying at a rate related to a fundamental frequency of the source. The modulation index relates to output voltage of the converter, peak voltage or current of the source and/or peak current at the output terminals.

A power converter module includes power transistors and a substrate having a first surface and a second surface that opposes the first surface. A thermal pad is situated on the second surface of the substrate, and the thermal pad is configured to be thermally coupled to a heat sink. The power converter module also includes a control module mounted on a first surface of the substrate. The control module also includes control IC chips coupled to the power transistors. A first control IC chip controls a first switching level of the power converter module and a second control IC chip controls a second switching level of the power converter module. Shielding planes overlay the substrate. A first shielding plane is situated between the thermal pad and the first control IC chip and a second shielding plane is situated between the thermal pad and a second control IC chip.

A power converter module includes power transistors and a substrate having a first surface and a second surface that opposes the first surface. A thermal pad is situated on the second surface of the substrate, and the thermal pad is configured to be thermally coupled to a heat sink. The power converter module also includes a control module mounted on a first surface of the substrate. The control module also includes control IC chips coupled to the power transistors. A first control IC chip controls a first switching level of the power converter module and a second control IC chip controls a second switching level of the power converter module. Shielding planes overlay the substrate. A first shielding plane is situated between the thermal pad and the first control IC chip and a second shielding plane is situated between the thermal pad and a second control IC chip.

A power-control device comprises an energy-import portion and an energy-export portion. The power-control device may additionally include a general processing and power supply circuit providing linear control of the power-control device's production of power to the load. The energy-import portion is coupled between a V.sub.LINE terminal and a load terminal, and is capable of importing energy to the load terminal during a first portion and a third portion of an alternating voltage V.sub.AC waveform. The energy-export portion is coupled between the load terminal and a NEU terminal, and is capable of exporting energy from the load terminal during a second portion and a fourth portion of the alternating voltage V.sub.AC waveform. The first, second, third and fourth portions of the alternating voltage V.sub.AC waveform are equal to a period of the alternating voltage V.sub.AC waveform and respectively are consecutive during the period of the alternating voltage V.sub.AC waveform. The power-control device provides variable power control to the load terminal in response to a variable on/off time of a PWM control signal.

A power-control device comprises an energy-import portion and an energy-export portion. The power-control device may additionally include a general processing and power supply circuit providing linear control of the power-control device's production of power to the load. The energy-import portion is coupled between a V.sub.LINE terminal and a load terminal, and is capable of importing energy to the load terminal during a first portion and a third portion of an alternating voltage V.sub.AC waveform. The energy-export portion is coupled between the load terminal and a NEU terminal, and is capable of exporting energy from the load terminal during a second portion and a fourth portion of the alternating voltage V.sub.AC waveform. The first, second, third and fourth portions of the alternating voltage V.sub.AC waveform are equal to a period of the alternating voltage V.sub.AC waveform and respectively are consecutive during the period of the alternating voltage V.sub.AC waveform. The power-control device provides variable power control to the load terminal in response to a variable on/off time of a PWM control signal.

A stimulation circuit generates magnetic stimulation for application to a body organ using a coil arrangement. A DC supply is provided and supplied to a DC/AC inverter that comprises abridge inverter stage comprising plural switch modules connected in a bridge arrangement between input terminals and output terminals for supplying the stimulation signal. A driver circuit supplies pulse width modulation control signals to the switch modules that are selected to control the DC/AC inverter to generate the stimulation signal with pulse width modulation of voltage, thereby providing for a high degree of control of the form of the stimulation.