Abstract: A switch includes a first terminal, a second terminal, and a third terminal. The switch includes an output node coupled to the second terminal and the third terminal. The switch includes a contactor coupled to the first terminal and movable between at least a first position and a second position. The first terminal is coupled to the second terminal when the contactor is in the first position. The first terminal is coupled to the third terminal when the contactor is in the second position. When the contactor is in the first position, the switch is configured to provide direct current power at the output node. When the contactor is in the second position, the switch is configured to provide alternating current power at the output node.

Abstract: In certain embodiments, a system includes a welding-type system including circuitry configured to receive direct current (DC) power directly from a distributed DC bus, to generate a current using the received DC power, and to isolate the welding-type system from the distributed DC bus.

Abstract: Various embodiments of the teachings herein include a charging circuit for a vehicle-side electrical energy store comprising: an alternating current terminal; at least two smoothing capacitors; a configuration device; and a rectifier connecting the alternating current terminal to the configuration device. The configuration device connects the rectifier to the smoothing capacitors, and the configuration device is programmed to connect the smoothing capacitors to one another in a first parallel connection and a second series connection. The alternating current terminal comprises a neutral conductor terminal connected to the configuration device via a diode circuit. The configuration device comprises a first switch connecting the smoothing capacitors to one another in parallel when closed. The configuration device comprises a diode connecting the smoothing capacitors to one another in series when closed.

Abstract: In an example embodiment a power adapter includes a shell, a plug assembly, an electronic assembly and a protective shield, wherein the plug assembly comprises a plug and a connector electrically connected to the plug. The electronic assembly comprises a transformer and an electronic element; and the protective shield is located inside a receiving cavity and encloses a protective cavity together with a cavity wall of the receiving cavity, the connector is located inside the protective cavity, the electronic assembly is located outside the protective cavity, and the protective shield is a protective shield made of an insulating material. The power adapter reduces the influence of strong electrical interference generated by the connector on the electronic assembly, so that the space in the receiving cavity can be fully utilized, thereby realizing the small volume setting of the shell.

Abstract: A power-factor corrected AC/DC converter has three half-bridge legs, electrically coupled with each other in parallel, each leg having a pair of switches. Each switch of the pair is electrically coupled to the other in series via a respective node that is electrically coupled through an inductor to an AC line. The converter has a fourth half-bridge leg electrically coupled with the other legs to form an electrically parallel circuit. The fourth leg has a pair of switches electrically coupled to each other in series via a fourth node, which is selectively electrically coupleable to a neutral or a second AC line. The converter has a controller that operates the three legs as a 3-channel interleaved AC/DC boost converter and couples the fourth node to the neutral or second AC line if the input is single-phase, and as a 3-phase AC/DC boost converter if the input is three-phase.

Abstract: Various embodiments include a charging circuit for a vehicle-side electrical energy store comprising: an alternating current terminal; at least two smoothing capacitors; a configuration device; and a rectifier via which the alternating current terminal is connected to the configuration device. The configuration device connects the rectifier to the at least two smoothing capacitors and is configured to connect the smoothing capacitors to one another in a first parallel arrangement and a second series arrangement. The alternating current terminal comprises a neutral conductor terminal connected via a diode circuit to the configuration device.

Abstract: A switch-mode power supply circuit includes a feedback terminal, a control circuit, a comparator, and a switch. The comparator includes a first input terminal coupled to a reference voltage source, and an output terminal coupled to an input terminal of the control circuit. The switch includes a first terminal coupled to the feedback terminal, a second terminal coupled to a second input terminal of the comparator, and a third terminal coupled to an output terminal of the control circuit.

Abstract: A surge protection circuit comprises a bridge rectifier having two input terminals coupled to an input source of electricity that may experience highly positively or negatively biased over-voltage and/or over-current, and two output terminals respectively coupled to a voltage surge blocking stage via a first bus line and to a return bus; a current surge protection stage that is series coupled in the first bus line between the voltage blocking stage and a voltage surge detection stage that is disposed between the first bus line and the return bus; two output terminals respectively coupled to the first bus line and the return bus, after the current surge protection stage. Embodiments can protect circuits or apparatus, such as DC-DC converters, that are sensitive to highly positively or negatively biased voltage/current surges by inverting negative pulses associated with a surge and outputting the inverted or rectified over-voltage/over-current to other protection circuitry.

Abstract: A system and method for operation of an uninterruptible power supply using redundant control systems to prevent UPS failure due to a control system failure are described. The system includes multiple control modules for each UPS of a data center operating in parallel, with a primary control board controlling operations and a secondary control board monitoring data values monitored as part of the operation by the primary control board. In the event of discrepancies between the data values at the primary and secondary control boards, the control boards may be swapped such that the secondary board becomes primary, and the faulty control board may be hot-swapped to prevent downtime of the UPS.

Abstract: A switch includes a first terminal, a second terminal, and a third terminal. The switch includes an output node coupled to the second terminal and the third terminal. The switch includes a contactor coupled to the first terminal and movable between at least a first position and a second position. The first terminal is coupled to the second terminal when the contactor is in the first position. The first terminal is coupled to the third terminal when the contactor is in the second position. When the contactor is in the first position, the switch is configured to provide direct current power at the output node. When the contactor is in the second position, the switch is configured to provide alternating current power at the output node.

Abstract: An equipment shelf includes at least one power supply unit (PSU) positioned in an upper region of the equipment shelf. The equipment shelf also includes at least one battery backup unit (BBU) positioned in a lower region of the equipment shelf. An airflow path extends through the equipment shelf between the upper region and the lower region. The airflow path separates the upper region of the equipment shelf from the lower region of the equipment shelf and thermally isolates the at least one PSU in the upper region from the at least one BBU in the lower region when air flows through the airflow path. Other example equipment shelves are also disclosed.

Abstract: The grid-connected inverter system according to one embodiment of the present invention may convert direct current supplied from a direct current source into alternating current, receive a control command from an upper level controller and a power electronics building block group comprising a plurality of power electronics building blocks for supplying the converted alternating current to a grid, determine the number of power electronics building blocks which will operate according to the control command, and transmit a control signal for operating the determined number of power electronics building blocks to corresponding power electronics building blocks.

Abstract: An integrated circuit includes: a primary supply stage including a primary supply node, the primary supply stage being configured to deliver a primary supply voltage to the primary supply node; a secondary supply stage including a secondary supply node, the secondary supply stage being configured to deliver a secondary supply voltage to the secondary supply node; a supply-switching circuit; a pre-charging circuit controllably coupled to the secondary supply node via the supply-switching circuit; and a volatile memory circuit controllably coupled to the primary supply node and the secondary supply node via the supply-switching circuit, wherein the switching circuit is configured to connect a supply of the volatile memory circuit either to the primary supply node in a primary supply mode, or to the secondary supply node in a secondary supply mode.

Abstract: An uninterruptible power supply with DC output includes an AC-to-DC conversion circuit coupled to an AC power source for outputting a first DC power source, a charging and discharging module for outputting a second DC power source, at least one power module coupled to the AC-to-DC conversion circuit and the charging and discharging module, a user operation interface disposed between the at least one power module and at least one load, and the user operation interface includes at least one operation unit, the power required for each load is selected by each operation unit so that at least one power module uninterruptedly supplies power to each load.

Abstract: A momentary-voltage-drop compensation apparatus interconnecting a power system and a DC power supply to a load. The apparatus includes a system interconnection switch connected between the power system and the load, a first power converter that performs DC-AC conversion to DC power of the DC power supply, a second power converter that includes a first terminal connected to the first power converter and the DC power supply, and a second terminal connected between the system interconnection switch and the power system, for performing AC-DC conversion to the AC power supplied from the power system, and a control unit that is connected to the first power converter, and is configured to control, in response to a voltage drop in the power system, the first power converter to output a zero-phase current, a current value of which is no larger than that of a current flowing through the system interconnection switch.

Abstract: A system includes a clamp circuit configured to regulate a converter input supply voltage based on control signals. The system also includes a converter configured to the adjust the converter input supply voltage to a converter output supply voltage. The system also includes a controller configured to adjust the control signals for the clamp circuit using a first mode based on the converter output supply voltage and a second mode based on the converter input supply voltage.

Abstract: A wiring device includes a housing that encloses a line voltage port and/or a low voltage port for providing power to at least one removable load. The housing has an intake opening and an exhaust opening for drawing cooling air into the housing and for exhausting heated air. A fan is disposed within the housing and operates to move the air through the housing. A thermal load such as a heat sink or a transformer is positioned within the housing and receives cooling air to reduce the temperature of the load. The fan is energized when a sensed temperature in the housing exceeds a first predetermined threshold. Power to the line and/or low voltage port is reduced or shut off if the sensed temperature in the housing exceeds a predetermined value that is greater than the first predetermined threshold.

Abstract: A circuit includes a controller to communicate with a sink device and communicate a plurality of power sources that are available to the sink device. A plurality of switch devices switch power from one of the plurality of power sources to the sink device in response to a control signal from the controller. A policy engine in the controller defines policies for the operation of the controller during different communications phases between the controller and the sink device.

Abstract: A power adapter is disclosed herein. The power adapter includes an AC-DC converter, at least one output port, at least one DC transmission cable and at least one connector. The AC-DC converter is configured to convert an input AC voltage to an intermediate DC voltage. The output port is configured to output the intermediate DC voltage. A second terminal of the DC transmission cable is connected to the output port and configured to receive and transmit the intermediate DC voltage. The connector is connected to a first terminal of the DC transmission cable and configured to output an output voltage. The connector includes a first housing, a DC-DC converter and an output terminal. The DC-DC converter is enclosed in the first housing and configured to convert the intermediate DC voltage to the output voltage. The output terminal is enclosed in the first housing and configured to transmit the output voltage.

Abstract: The present invention relates to a power supply apparatus and, more particularly, to a power supply apparatus for sub-modules of a MMC (Modular Multilevel Converter), the apparatus stably supplying power to the sub-modules of the MMC connected to an HVDC (High Voltage Direct Current) system.

Abstract: An overvoltage detection circuit for a power converter a current augmentation circuit coupled to receive a sense signal representative of an output voltage of the power converter only during a portion of an off time of a power switch of the power converter. The current augmentation circuit is further coupled to output an augmented signal. A detection circuit is coupled to receive the augmented signal from the augmentation circuit and a power signal representative of a rectified version of the sense signal at a same input terminal. The detection circuit is operable to output an overvoltage detection signal based at least in part on the augmented signal, the overvoltage detection signal being representative of an overvoltage condition in the output voltage of the power converter.

Abstract: An Input-Series-Output-Parallel (ISOP)-type partial power converter circuit comprises: an isolated, unregulated DC-to-DC converter configured to generate a first output voltage at a first output voltage node; and a regulated DC-to-DC converter coupled with the unregulated DC-to-DC converter and configured to generate a second output voltage at a second output voltage node, the regulated DC-to-DC converter comprising a resonant forward-flyback converter configuration; wherein the first output voltage node is coupled in parallel with the second output voltage node.

Abstract: A high-voltage power supply includes: a first high-voltage output circuit having a first output connected to a first load, and a second output, and capable of outputting a first voltage having a first polarity to the first load; a voltage clamping element connected to the second output and configured to clamp a voltage at the second output to a second voltage having a second polarity opposite to the first polarity; a second high-voltage output circuit having a third output connected to the second output and a fourth output, and capable of outputting a third voltage having the first polarity; and an output circuit connected to the fourth output and a second load, and configured to produce a voltage having the first polarity and a voltage having the second polarity using the third voltage and a voltage derived from the second voltage and output the produced voltages to the second load.

Abstract: A method of operating a printing device during a power loss event includes, with a power loss detection device, detecting an power loss to a number of high voltage devices. The method further includes, with a voltage regulator coupled to printhead fire control circuitry, maintaining a power loss protection supply voltage (VDD_plp) to the printhead fire control circuitry.

Abstract: Power generation and storage system and/or solar power generation and storage packaged panels and storage functions in a device and their installment of Signal UPS system device and this power equipment Station combined with various electric power generators. The first aspect of his invention relates to Intelligent function installing Power generation and storage system, involving a control system of Charge-Discharge, Power storage and supplemental charge-discharge functions, packaging lithium ion rechargeable battery (LIB) (1) sole or a combination of LIB and capacitor-condenser as battery units, Charge-Discharge Control Unit (2) containing Charge-Discharge controller.

Abstract: According to a first aspect of the present invention, reducing electrical energy stored in a load or in one or more leads for connecting a power supply with the load is achieved by plasma process power circuitry including a switch in operative connection with at least one of the leads for enabling/interrupting power to the load; a first electrical nonlinear device; an energy storing device arranged in series with the first electrical nonlinear device; and a pre-charging circuit in operative connection with the energy storing device, the pre-charging circuit configured to charge the energy storing device to a pre-determined energy level while power to the load is enabled.

Abstract: A system connected to an AC power grid having an AC phase signal includes an inverter module including a first inverter coupled to a DC voltage, actuated based on the AC phase signal. The first inverter provides a first voltage signal having predetermined harmonic components. A second inverter includes second switch elements coupled to the DC voltage and actuated by a second set of control signals phase delayed with respect to the first control signals. A transformer module has first and second primary windings coupled to the first and second inverters. The transformer module further includes a secondary winding coupled to first primary winding, the second primary winding, and the AC power grid. The secondary winding is configured to provide a secondary output voltage to the AC power grid by combining the first voltage signal and the second voltage signal such that the predetermined harmonic components are substantially cancelled.

Abstract: A multi-function charger is provided. The multi-function charger includes a main body, a first plug, a first base, a second base, and a linkage element. The main body has a first surface having a recess and a second surface opposite thereto. The first plug having a first connector, a second connector, and a third connector is arranged in the main body and exposed on the first surface. The first base is connected to the first and second connectors, and the second base is connected to the third connector. The linkage element is pivotally connected to the first and second bases so that the first connector, the second connector, and the third connector are capable of rotating in the same direction until to be arranged in the recess. The linkage element is located in a connecting region defined between the central section of the first base and the second base.

Abstract: A diode control device include a first terminal for receiving a first power supply voltage and a second terminal for receiving a second power supply voltage. A circuit of the diode control device applies a regulated voltage on the anode of the diode in response to a control voltage. The control voltage is equal to a preset voltage when a reference voltage is less than or equal to zero. Conversely, when the reference voltage is greater than zero, the control voltage is equal to the sum of the present voltage and a difference between cathode voltage of the diode and the reference voltage.

Abstract: An electric motor vehicle main circuit system includes an AC-DC switching circuit switching a supply destination of electric power according to a type of supplied power from an overhead wire, a transformer, a tap changer switching tap positions of the transformer, a CNV converting an output of the tap changer into a direct-current voltage, an AC contactor opening and closing a power supply path between the tap changer and the CNV, an FC accumulating an output of the CNV or the overhead wire, a CH stepping up an output of the FC, an FC accumulating an output of the CH, an INV converting an output of the FC into a desired alternating-current voltage, a DC contactor opening and closing a power supply path between the AC-DC switching circuit and the CH, and a control section controlling the tap changer, the AC contactor, the DC contactor, the CNV, and the CH.

Abstract: A portable power station system for providing access to electrical power and mechanical energy in from stored and renewable sources comprising a housing containing a battery, a brushless DC motor, an inverter, a gear system, an AC motor, an alternator, a rectifier, a reservoir capacitor, a charge controller, sequentially connected with the charge controller connected back to the battery. Solar panels and a wind power generator are additionally connected to the charge controller. A plurality of grounds are also provided. The portable power station system works to convert stored energy from the battery into other forms of energy and provide access to the various forms of energy through various discrete outputs accessible from the exterior of the housing. To account for the inevitable energy losses from its operation, the portable power station system utilizes renewable forms of energy to continually introduce additional energy.

Abstract: A reconfigurable battery pack power system with interchangeable accessories has at least one modular, portable, rechargeable battery module having a first side, the first side having a first contour and a mounting port and a power output port, and at least one accessory module configured to receive power from the battery module. The accessory module has a second side with a second contour that mates with the first contour on the battery module, and has a power coupling connector and a fastener. The accessory module is interchangeably mateable with the battery module with the first and second contours nested together, and with the power output port engaged with the power coupling connector and with the fastener engaged with the mounting port, so that the battery module and the accessory module form a single integrated and substantially rigid structure.

Abstract: A sensor device has a sensor unit, a control unit; and multiple power supply paths from a power supply to the sensor unit and the control unit. The multiple power supply paths are configured to be switched in accordance with an operation status of the sensor unit. The sensor device further has a wireless communication device for transmitting a measurement result of the sensor unit. The multiple power supply paths are provided to supply power from the power supply to the wireless communication device. The multiple power supply paths are configured to be switched in accordance with an operation status of the wireless communication device.

Abstract: A parallel power supply includes a built-in test switch and a control and determination unit. The built-in test switch is arranged to generate a first detection signal. The control and determination unit is coupled to the built-in test switch. When receiving the first detection signal, the control and determination unit is operative for enabling a detection mechanism according to the first detection signal in order to detect an operation of the parallel power supply, and accordingly generating a detection result. A power detection method for a parallel power supply includes: disposing a built-in test switch inside the parallel power supply; and when receiving a first detection signal generated from the built-in test switch, enabling a detection mechanism according to the first detection signal in order to detect an operation of the parallel power supply, and accordingly generating a detection result.

Abstract: Single and multiphase regenerative voltage doubler rectifiers, sag/swell corrector apparatus, and operating methods are presented in which rectifier switching devices are selectively pulse width modulated for regenerative load conditions and for regenerating power during input voltage swell circumstances.

Abstract: A client connection device for a UPS system includes a frame on which a main input distribution unit, a bypass input distribution unit, a battery distribution unit, and an output distribution unit are provided, in which the main input distribution unit and the bypass input distribution unit are arranged on the frame with being opposite to each other up and down, the output distribution unit and the battery distribution unit are arranged on the frame on different sides of the main input distribution unit and the bypass input distribution unit, and the battery distribution unit is side placed near the main input distribution unit and the bypass input distribution unit. A client connection device for a UPS system is provided which can be of a compact structure, be space saving, and be convenient for space operation.

Abstract: This invention concerns an electrical energy distribution system. The system incorporates ‘ride-through’ capability, comprising: a supply side for supplying energy in the form of direct current at a supply voltage, a delivery side for delivering energy, having plural connection ports for selective connection to respective electrical energy loads. Wherein each connection port includes electricity conditioning circuitry to deliver and vary electrical power supply to a load connected at the port. And further comprising a bank of charge storage devices arranged in series and connected across the supply voltage.

Abstract: A transformer for connecting a 50 A RV normally wired for 110 volts of electricity to foreign receptacles providing 220 volts of electricity. The transformer employs two cords on the input side of the transformer that can be connected to the two receptacles normally provided between side-by-side campsites in a campground. The transformer also employs a separate circuit breaker in each hot lead on the secondary side of the circuit employed in the transformer.

Abstract: The embodiments provide a powerline network adapter that allows network communications over power lines while also being configurable to provide other features. In the embodiments, the network adapter can provide a first power outlet, a powerline network adapter, and a wireless access point. The first power outlet serves as a replacement for the outlet consumed by the powerline network adapter and is filtered to reduce or prevent interference with network communications being carried over the powerline. The network adapter is also configurable to provide, among other things, a powerline wired Ethernet interface and a wireless access point that is coupled to the powerline. Furthermore, the network adapter may be configured to provide a second power outlet for a device, such as an external drive. For example, the second power outlet may be an AC/DC 12-Volt power adapter. In some embodiments, this second power outlet is also filtered from the first power outlet.

Abstract: Systems and methods (“utility”) are provided for reducing the no-load (standby) power of power devices such as chargers for electronic devices and power converters for electronic devices. The utility may include a controllable switch that is operative to decouple circuitry of the power device from a power source under certain no-load conditions. In one embodiment, the utility provides a switch control module that is operative to sense when an electronic device is coupled to the power device, and in response, to control the switch to couple the power device to the power source. The switch control module may also be operative to detect a condition when the electronic device is no longer drawing power from the power device, and in response, to control the switch to decouple the power device from the power source.

Abstract: Method and system for enhancing the power efficiency of a first wireless device that includes an energy receiver. In one implementation, the method includes receiving a transmitted signal at the first wireless device, converting the transmitted signal into power through the energy receiver, and providing the power to the first wireless device.

Abstract: Electronic devices require correct power in order to operate correctly. Receiving an incorrect power signal could potentially result in immediate and/or long term harm to the electronic device and/or catastrophic conditions. Certain devices, such as programmable logic controller (“PLC”) modules, may provide variable power to electronic devices, such as field devices comprising sensors and/or actuators. The present inventors have recognized that deciphering between AC and DC input signals before coupling electronic devices to such power sources may advantageously avoid harmful and/or catastrophic conditions. Aspects of the present invention provide an electronic circuit for deciphering between an AC and a DC input signal. Systems and methods are also described.

Abstract: A communication device for use with a power distribution module. The communication device allows multiple different DMX universes to be handled over the same cable that also handles power distribution. A front of house module is provided for powering consoles and receiving DMX inputs from the consoles. Two different consoles can be powered and provide their inputs, and either console can be used to control any or all of the universes.

Abstract: A system and method are provided for increasing and maintaining voltage. A transformer's secondary windings are connected between the hot input line and the hot output line, and are not switched. The secondary windings may be in series for 220/230 Vrms, and in parallel for 120/127 Vrms. Alternatively, the transformer may be a single voltage type specifically for 230 V, 120 V, or any other voltage range. A microprocessor measures incoming voltage and controls an electronic switch on the primary windings side of the transformer to short circuit the primary windings when the transformer is not needed. When voltage boost is needed, the switch may be controlled to connect the primary windings to neutral. When the primary windings are switched to neutral, the secondary voltage adds to the incoming AC line voltage. There may be multiple taps on the primary windings selected by the microprocessor for providing differing boost levels at differing input voltage levels.

Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.

Abstract: A power converter and method of operating the same for use in a power conversion system capable of receiving power from various sources, including renewable sources, for application to a load. Power type detection circuitry is provided for identifying the type of power source at the input of each power detector, based on attributes of the time-varying power received. The power converter is constructed of a boost stage followed by a galvanically isolated DC-DC converter stage. If a renewable input power source is detected, the boost stage is controlled to operate at a maximum power point, and the DC-DC converter stage is operated in an open loop manner. If the AC grid is detected as the input power source, the boost stage is controlled to attain maximum power factor, and the DC-DC converter stage is placed under feedback control of the output voltage. Operating modes are also switched in response to low load demand.

Abstract: According to one embodiment, a power supply circuit includes an input terminal, a rectifier circuit, a power factor improvement circuit, a DC/DC converter, and a control module. The DC/DC converter converts the level of a DC voltage output from the power factor improvement circuit. The control module determines on the basis of the output voltage of the rectifier circuit whether an input power supply supplied to the input terminal is AC or DC. The control module generates a DC power supply by use of the power factor improvement circuit and DC/DC converter when the input power supply is AC and generates a DC power supply by controlling the operation of the power factor improvement circuit and DC/DC converter according to the voltage of input DC power supply when the input power supply is DC.

Abstract: An alternating-current and direct-current conversion apparatus includes a first converter unit, a switching unit electrically connected with the first converter unit, and a second converter unit electrically connected with the switching unit. The switching unit is connected between the first converter unit and the second converter unit and is operated to convert a direct-current power into an alternating-current power or to convert an alternating-current power into a direct-current power so that the direct-current power of the direct-current source is converted into an alternating-current power which can be used by the alternating-current source, and the alternating-current power of the mains power supply is converted into a direct-current power which can be used by the direct-current source.

Abstract: A power supply system for a charge is provided. The power supply system includes a converter connected in input to a current source and in output to a charge, the converter being able to deliver a direct current to the charge and allow the circulation of the current in a single direction, from the current source to the charge and a circulation bus for an electric current, including a first end and a second end. The power supply system further includes a device for injecting an additional alternating voltage and at the second end of the circulation bus, the injection device being connected to the second end and a device for recovering the additional injected alternating voltage, the recovery device being connected between the first end of the bus and the charge, so as to supply the charge with electrical current.

Abstract: An alternating current-to-direct current (AC-to-DC) power supply has a first stage providing a first DC voltage and a second stage providing a second DC voltage. The AC-to-DC power supply has a first efficiency at the first stage and a second efficiency at the second stage that is less than the first efficiency. The second DC voltage is also less than the first DC voltage. A blower is electrically connected to the first stage of the AC-to-DC power supply to receive the first DC voltage from the AC-to-DC power supply to power the blower. Electrical connection of the blower to the first stage of the AC-to-DC power supply instead of to the second stage of the AC-to-DC power supply wastes less power and is more efficient.