A single-phase voltage source inverter including a first stage configured to be connectable to a DC source, and a second stage configured to be connectable to an AC load, the first stage including a bridge leg including first and second decoupling switches, the bridge leg connected through an inductor to a decoupling capacitor, where the decoupling capacitor is in series with the DC source when the inverter is connected to the DC source, and the second stage including a bi-directional H-bridge inverter including first, second, third and fourth switches. The decoupling capacitor can be a small film capacitor. The first and second decoupling switches are the only decoupling switches in the bridge leg. The first controller can use pulse width modulation and the second controller uses sinusoidal pulse width modulation. The first controller can use pulse width modulation and the second controller uses pulse energy modulation.

Apparatus and methods for controlling a jitter buffer are described. In one embodiment, the apparatus for controlling a jitter buffer includes an inter-talkspurt delay jitter estimator for estimating an offset value of the delay of a first frame in the current talkspurt with respect to the delay of a latest anchor frame in a previous talkspurt, and a jitter buffer controller for adjusting a length of the jitter buffer based on a long term length of the jitter buffer for each frame and the offset value.

Apparatus and methods for controlling a jitter buffer are described. In one embodiment, the apparatus for controlling a jitter buffer includes an inter-talkspurt delay jitter estimator for estimating an offset value of the delay of a first frame in the current talkspurt with respect to the delay of a latest anchor frame in a previous talkspurt, and a jitter buffer controller for adjusting a length of the jitter buffer based on a long term length of the jitter buffer for each frame and the offset value.

Apparatus and methods for controlling a jitter buffer are described. In one embodiment, the apparatus for controlling a jitter buffer includes an inter-talkspurt delay jitter estimator for estimating an offset value of the delay of a first frame in the current talkspurt with respect to the delay of a latest anchor frame in a previous talkspurt, and a jitter buffer controller for adjusting a length of the jitter buffer based on a long term length of the jitter buffer for each frame and the offset value.

A power converter includes an alternating-current-side circuit, a direct-current-side inductor, an alternating-current-side inductor, a direct-current-side circuit, a controlling unit, a transformer, a direct-current-side capacitor, and an alternating-current-side capacitor. The alternating-current-side circuit includes an alternating-current-side buffer circuit and a bridge circuit, and is connected to an alternating-current-side winding of the transformer via the alternating-current-side capacitor. The direct-current-side circuit includes a direct-current-side buffer circuit and a rectification switching element, and is connected to a direct-current-side winding of the transformer via the direct-current-side capacitor. The controlling unit controls switching of the switching elements.

A converter arrangement connects to a DC source or load and to a plurality of AC terminals. Each converter arrangement includes a DC part with two capacitors arranged in parallel to the DC source or DC load and a neutral DC point between them. At least one AC leg is connected to a neutral AC point via an AC leg capacitor. A pre-charge unit is arranged at each leg of the AC terminal. The method includes opening a decoupling switch and all second AC switches; loading the pre-charge unit; sequentially closing each second AC switch; measuring at each closing step a voltage between each AC leg of the second converter arrangement; and determining the stuck AC switch of the second converter arrangement based on the measured voltage.

A converter arrangement connects to a DC source or load and to a plurality of AC terminals. Each converter arrangement includes a DC part with two capacitors arranged in parallel to the DC source or DC load and a neutral DC point between them. At least one AC leg is connected to a neutral AC point via an AC leg capacitor. A pre-charge unit is arranged at each leg of the AC terminal. The method includes opening a decoupling switch and all second AC switches; loading the pre-charge unit; sequentially closing each second AC switch; measuring at each closing step a voltage between each AC leg of the second converter arrangement; and determining the stuck AC switch of the second converter arrangement based on the measured voltage.

The present invention relates to a circuit arrangement (100) for operating an electrical machine (101) in a motor vehicle, having a first electrical drive train (103-1) in which a first battery direct converter (105-1) can be connected to the electrical machine (101) via a first switching device (107-1); a second electrical drive train (103-2) in which a second battery direct converter (105-2) can be connected to the electrical machine (101) via a second switching device (107-2); a third electrical drive train (103-3) in which a third battery direct converter (105-3) is connected to the electrical machine (101), one converter connection of which can be connected to the second drive train (103-2) via a third switching device (107-3) and the other converter connection of which can be connected to the second drive train (103-2) via a fourth switching device (107-4); a DC voltage section (109) for providing a DC voltage for a vehicle electrical system, which DC voltage section is connected to the first, second and third drive trains (103-1, 103-2, 103-3) via a rectifier (111-1, 111-2, 111-3) in each case; and a charging section (113) for supplying a charging current to the first, second and third battery direct converters (105-1, 105-2, 105-3), which charging section is connected to the first drive train (103-1) and to the third drive train (103-3).

A control device includes: a phase generation unit to generate a phase of a voltage command for the power converter; a voltage control unit to generate a voltage value of the voltage command; and a command unit to output the voltage command having the phase and the voltage value to the power converter. The voltage control unit includes: a voltage compensator unit to compute a compensation voltage value, based on a voltage deviation of a point-of-interconnection voltage from a reference voltage; a droop calculator unit to compute a first droop value in accordance with a magnitude of a point-of-interconnection current, when the AC power system is an isolated system, the isolated system being the AC power system not connected to a generator; and a calculation unit to calculate the voltage value of the voltage command, based on a difference between the compensation voltage value and the first droop value.

A control device includes: a phase generation unit to generate a phase of a voltage command for the power converter; a voltage control unit to generate a voltage value of the voltage command; and a command unit to output the voltage command having the phase and the voltage value to the power converter. The voltage control unit includes: a voltage compensator unit to compute a compensation voltage value, based on a voltage deviation of a point-of-interconnection voltage from a reference voltage; a droop calculator unit to compute a first droop value in accordance with a magnitude of a point-of-interconnection current, when the AC power system is an isolated system, the isolated system being the AC power system not connected to a generator; and a calculation unit to calculate the voltage value of the voltage command, based on a difference between the compensation voltage value and the first droop value.