Abstract: Power conversion systems, methods and precharge systems are disclosed to charge a DC bus capacitor, including thyristors and reverse diodes coupled in AC circuit paths between AC input lines and a rectifier, a precharge resistor coupled in one or more of the AC circuit paths, and a controller to turn all the thyristors off to allow the DC bus capacitor to charge through the precharge resistor, and to turn all the thyristors on when the DC bus voltage reaches a non-zero threshold value.

Abstract: Power conversion systems, methods and precharge systems are disclosed to charge a DC bus capacitor, including thyristors and reverse diodes coupled in AC circuit paths between AC input lines and a rectifier, a precharge resistor coupled in one or more of the AC circuit paths, and a controller to turn all the thyristors off to allow the DC bus capacitor to charge through the precharge resistor, and to turn all the thyristors on when the DC bus voltage reaches a non-zero threshold value.

Abstract: A load control device includes an input and an output connectable to an AC source and an AC load, respectively, with one or more supply lines each corresponding to a phase in the load connecting the input and output. Line-side switches are connected between a line terminal and load terminal, and floating-neutral side switches are connected to the load terminal at one end and at a common neutral connection at another end. A controller determines a direction of current flow on each of the supply lines, determines a switching pattern for each of the line-side switches and each of the floating-neutral side switches based on the determined direction of current flow, and causes each of the line-side switches and floating-neutral side switches to operate in an On condition or an Off condition according to the determined switching pattern, such that a controlled uninterrupted current is provided to the AC load.

Abstract: A load control device to control current flow to an AC load includes a circuit having line-side switches and floating-neutral side switches, along with a controller connected to the circuit that is programmed to control the circuit so as to cause each of the line-side switches and each of the floating-neutral side switches to switch between an On condition or an Off condition to selectively operate the circuit in an active mode and a free-wheeling mode. A full phase voltage is provided to the AC load during the active mode and a zero voltage is provided to the AC load during the free-wheeling mode. The controller applies a modulating function to the circuit, so as to modulate a supply voltage to control a frequency and an average of a load voltage present across terminals of the AC load, thereby enabling variable frequency operation of the AC load.

Abstract: A load control device to control current flow to an AC load includes a circuit having line-side switches and floating-neutral side switches, along with a controller connected to the circuit that is programmed to control the circuit so as to cause each of the line-side switches and each of the floating-neutral side switches to switch between an On condition or an Off condition to selectively operate the circuit in an active mode and a free-wheeling mode. A full phase voltage is provided to the AC load during the active mode and a zero voltage is provided to the AC load during the free-wheeling mode. The controller applies a modulating function to the circuit, so as to modulate a supply voltage to control a frequency and an average of a load voltage present across terminals of the AC load, thereby enabling variable frequency operation of the AC load.

Abstract: A load control device includes an input and an output connectable to an AC source and an AC load, respectively, with one or more supply lines each corresponding to a phase in the load connecting the input and output. Line-side switches are connected between a line terminal and load terminal, and floating-neutral side switches are connected to the load terminal at one end and at a common neutral connection at another end. A controller determines a direction of current flow on each of the supply lines, determines a switching pattern for each of the line-side switches and each of the floating-neutral side switches based on the determined direction of current flow, and causes each of the line-side switches and floating-neutral side switches to operate in an On condition or an Off condition according to the determined switching pattern, such that a controlled uninterrupted current is provided to the AC load.