An AC-DC conversion device that includes a major circuit portion and a control circuit is provided. The major circuit portion includes a converter in which multiple switch portions in a bridge connection include separately-excited switching elements and snubber circuits connected in parallel with the switching elements; and the major circuit portion is connected to an alternating current power supply and a direct current circuit and applies, to the direct current circuit, an alternating current voltage applied from the alternating current power supply by an ON of the multiple switch portions. The control circuit controls the voltage applied to the direct current circuit by controlling the ON timing of the multiple switch portions by inputting a control pulse to each of the multiple switch portions.

A high voltage direct current power transmission series valve group control device, is used for regulating a series circuit having two or more valve groups provided with controllable power semiconductors respectively. Each valve group is provided with a current regulation unit and a voltage regulation unit. The current regulation unit controls a direct current current flowing through a valve group corresponding thereto, and the voltage regulation unit controls a voltage across two ends of a valve group corresponding thereto. One valve group is selected from the series valve group as a master control valve group, while the others are taken as slave control valve groups. The master control valve group selects a trigger angle output by the current regulation unit to control same, and the slave control valve group selects a trigger angle obtained after the trigger angle transmitted from the master control valve group and an output value of the voltage regulation unit pass through a subtractor to control same.

A high voltage direct current power transmission series valve group control device, is used for regulating a series circuit having two or more valve groups provided with controllable power semiconductors respectively. Each valve group is provided with a current regulation unit and a voltage regulation unit. The current regulation unit controls a direct current current flowing through a valve group corresponding thereto, and the voltage regulation unit controls a voltage across two ends of a valve group corresponding thereto. One valve group is selected from the series valve group as a master control valve group, while the others are taken as slave control valve groups. The master control valve group selects a trigger angle output by the current regulation unit to control same, and the slave control valve group selects a trigger angle obtained after the trigger angle transmitted from the master control valve group and an output value of the voltage regulation unit pass through a subtractor to control same.

In one aspect, an electric vehicle (EV) charging system includes: a plurality of first converters to receive grid power at a distribution grid voltage and convert the distribution grid voltage to at least one second voltage; at least one high frequency transformer coupled to the plurality of first converters to receive the second voltage and electrically isolate a plurality of second converters. The EV charging system may further include the plurality of second converters coupled to the output of the at least one high frequency transformer to receive and convert the at least one second voltage to a third DC voltage. At least some of the plurality of second converters are to couple to one or more EV charging dispensers to provide the third DC voltage as a charging voltage or a charging current.

A voltage source converter has director valve phase legs in parallel with waveshaper phase legs between two DC terminals. The director valve and waveshaper phase legs include upper and lower phase arms alternately operated to form waveshapes on AC terminals of the converter, thereby allowing a number of waveshaper phase arms to be available for use for other purposes. At least one of the available phase arms is controlled to contribute to other aspects of converter operation than waveshaping.

A voltage source converter has director valve phase legs in parallel with waveshaper phase legs between two DC terminals. The director valve and waveshaper phase legs include upper and lower phase arms alternately operated to form waveshapes on AC terminals of the converter, thereby allowing a number of waveshaper phase arms to be available for use for other purposes. At least one of the available phase arms is controlled to contribute to other aspects of converter operation than waveshaping.

In one example, a circuit includes an alternating current (AC) voltage source, a voltage rail, a reference rail, a first capacitor, a second capacitor, and a switching unit. The AC voltage source is configured to supply voltage in a first direction during a first half of a cycle and supply voltage in a second direction during a second half of the cycle. During a first state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the first capacitor. During a second state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the second capacitor.

In one example, a circuit includes an alternating current (AC) voltage source, a voltage rail, a reference rail, a first capacitor, a second capacitor, and a switching unit. The AC voltage source is configured to supply voltage in a first direction during a first half of a cycle and supply voltage in a second direction during a second half of the cycle. During a first state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the first capacitor. During a second state of the circuit, the voltage in the first direction supplied by the AC voltage source charges the first capacitor and the voltage in the second direction supplied by the AC voltage source charges the second capacitor.

There is provided an electrolyser power system comprising: a transformer arrangement having: at least one primary winding connectable to an AC power source; and a plurality of secondary windings; a first rectifier arrangement comprising: an AC input connected to a first secondary winding of the transformer arrangement; and a first DC output; a second rectifier arrangement comprising: an AC input connected to a second secondary winding of the transformer arrangement; and a second DC output; and a plurality of discrete electrically coupled electrolyser modules, wherein each electrolyser module is electrically connected between the first and second DC outputs.

A voltage source converter has director valve phase legs in parallel with waveshaper phase legs between two DC terminals. The director valve and waveshaper phase legs include upper and lower phase arms alternately operated to form waveshapes on AC terminals of the converter, thereby allowing a number of waveshaper phase arms to be available for use for other purposes. At least one of the available phase arms is controlled to contribute to other aspects of converter operation than waveshaping.