Patent application number | Description | Published |
20080219035 | Active Power Filter - An active power filter comprises an energy storage capacitor, an inverter, a filtering circuit and a controller. The inverter is controlled to act as a virtual resister at a fundamental frequency for compensating for the power loss of the active power filter, act as a virtual capacitor at a fundamental frequency for compensating for a fundamental reactive power of the load, and/or generate a harmonic current for suppressing the harmonic currents of specific orders of the load. | 09-11-2008 |
20080253153 | Active Power Conditioner - An active power conditioner includes a first power electronic switch set, a second power electronic switch set, a third power electronic switch set, an input filter and an output filter. The active power conditioner can supply a stable AC voltage to a load when a voltage variation is occurred at an AC power source by controlling either the second power electronic switch set or the third power electronic switch set via high-frequency switching, and the other power electronic switch sets that are not switched in high frequency are controlled to switch in low-frequency switching. | 10-16-2008 |
20090174260 | UPS System having a Function of Parallel Operation - A UPS system includes one or more UPS units with identical or different capacities. A control circuit, used to control a DC/AC inverter of the UPS unit, includes a voltage feedback control circuit and a current feedforward control circuit. The voltage feedback control circuit is used to control the amplitude and the waveform of load voltage. The current feedforward control circuit is used to operate the DC/AC inverter of the UPS unit as a virtual fundamental resistor and a virtual harmonic resistor which are serially connected to an output terminal of the DC/AC inverter such that each UPS unit can be distributed to provide an output current according to the capacity ratio of the UPS system. | 07-09-2009 |
20100072819 | Bi-directional DC to DC power converter having a neutral terminal - A bidirectional DC to DC power converter includes two DC sources, two inductors respectively connected to the two DC sources, a first switch and a second switch respectively connected to the two inductors, two capacitors respectively connected to the two switches, and a third switch connected between the two inductors. The first, second and third switches are respectively connected reversely with a diode in parallel. When the third switch is alternately turned on and off and the first and second switches are always turned off, the power converter operates as a boost power converter and electric energy flows from the two DC sources to the two capacitors. When the third switch is always turned off and the first and second switches are synchronously turned on or off, the power converter operates as a buck power converter and electric energy flows from the two capacitors to the two DC sources. | 03-25-2010 |
20100085784 | Ripple Voltage Suppression Method for DC/DC Converter and Apparatus Thereof - A ripple voltage suppression apparatus includes a DC/DC converter and a control circuit. The DC/DC converter has a power electronic switch. The control circuit has a voltage detector detecting a DC output voltage of the DC/DC converter, a ripple voltage suppression circuit receiving the detected DC output voltage to generate an AC control signal for controlling an AC component of a duty ratio of the power electronic switch, an output voltage regulation circuit receiving the detected DC output voltage to generate a DC control signal for controlling an DC component of a duty ratio, an adder adding the AC and DC control signals to form a combined control signal, and a PWM circuit converting the combined control signal into a PWM signal to control the power electronic switch. Only the DC output voltage of the DC/DC converter has to be detected for the control circuit. | 04-08-2010 |
20100201341 | Three-Leg Power Converter Apparatus - A three-leg power converter apparatus including first, second and third input/output ports, a three-leg bridge converter, a filter circuit, a decoupling circuit and a controller is presented. The three-leg bridge converter has three single-leg circuits, two DC terminals connecting to two terminals of the first input/output port, and three mid-terminals with each of them being formed by a middle point of one of the three single-leg circuits. The controller connects to the three-leg bridge converter for controlling an input or output current passing through each DC terminal and mid-terminal. The filter circuit connects between two of the mid-terminals and the second input/output port. The decoupling circuit has two terminals connecting to the second input/output port and another terminal connecting to a terminal of the third input/output port, with the third input/output port having another terminal connecting to the other mid-terminal that dose not connect with the filter circuit. | 08-12-2010 |
20100254170 | DC to AC inverter - A DC to AC inverter has a DC power input port, a buck converter, a buck/boost converter, an output filter and an AC output port. The DC power input port has a positive input terminal and a negative input terminal, both connected to a DC source. The AC output port is connected to a single-phase utility system. When the single-phase utility system is in positive half cycle, the buck converter generates a positive half-cycle signal of sinusoidal current. When the single-phase utility system is in negative half cycle, the buck/boost converter generates a negative half-cycle signal of sinusoidal current. In either the positive or negative half cycles, only one power electronic switch is switched in high frequency to reduce switching loss. Further, the negative input terminal of the DC power input port of the invention can be connected to a neutral line of the single-phase utility system. | 10-07-2010 |
20110260692 | Estimation Method for Residual Discharging Time of Batteries - An estimation method for residual discharging time of batteries includes the steps of: providing a set of battery-discharge-current intervals and a set of battery-discharge equations, setting discharge time of each battery-discharge-current intervals zero; detecting a discharge current, voltage and time of batteries; judging whether the discharge current exceeding all of the battery-discharge-current intervals; selecting one of the battery-discharge-current intervals and the associated battery-discharge equation according to the detected discharge current; calculating an estimation of residual discharging time; accumulating and recording the discharge time; judging whether the discharge voltage being lower than a predetermined value and calculating an estimation error of the residual discharging time; adjusting parameters of the battery-discharge equation for reducing the estimation error of the residual discharging time if the estimation error is greater than a predetermined error value. | 10-27-2011 |
20130033912 | FIVE-LEVEL DC-AC CONVERTER - A five-level DC-AC converter includes a capacitor set and a full-bridge circuit. The capacitor set contains two DC capacitors, a power electronic switch and two diodes. When the power electronic switch is turned on/off, the two DC capacitors are connected in series/parallel to provide a two-level DC voltage to the full-bridge circuit. The full-bridge circuit further converts the two-level DC voltage to output a voltage with three voltage levels in the positive half cycle and three voltage levels in the negative half cycle. This achieves the goal of using five power electronic switches to convert DC power into AC power with five voltage levels. | 02-07-2013 |
20140301124 | Cascade Bridge-type DC-AC Power Conversion Method and Converter Device Thereof - A cascade bridge-type DC-AC power converter device includes a low-frequency bridge-type power converter including an AC terminal and a DC bus and a high-frequency bridge-type power converter including an AC terminal. A power conversion method includes: serially connecting the AC terminal of the high-frequency bridge-type power converter and the AC terminal of the low-frequency bridge-type power converter; operating frequency of the low-frequency bridge-type power converter synchronized with frequency of an AC source and operating the high-frequency bridge-type power converter with high-frequency PWM to generate a multilevel AC voltage. A DC power source connects to the DC bus of the low-frequency bridge-type power converter. No additional power supply circuit will be required for power supply to a DC bus of the high-frequency bridge-type power converter. Accordingly, the power circuit is simplified and the manufacturing cost is reduced. | 10-09-2014 |