2611results about How to "Reduce switching losses" patented technology

An inverter circuit allowing a single drive circuit to perform both tracking control for tracking resonance frequency fluctuations caused by load fluctuations, and power control, thereby reducing switching loss. An inverter drive circuit part obtains a phase difference between output current and output voltage directed to a load circuit connected to a midpoint of two arm circuits of the inverter circuit, and controls a phase of the driving signal directed to each semiconductor switch such that the phase difference becomes zero or a predetermined value, enabling an operating frequency of the inverter circuit part to track a resonance frequency of the load circuit, and enabling a current phase to be delayed with respect to a voltage phase, thereby achieving ZCS. Since the phase difference is used, an auxiliary circuit is not necessary for measuring a current value in proximity to the semiconductor switches.

The invention discloses a switch voltage-stabilizing circuit which can regulate switching frequency as well as current peak, has high efficiency and has no audio-frequency noise generated in a state of light load, and method thereof. The switch voltage-stabilizing circuit comprises an energy storage component capable of storing energy; a switch electrically coupled to the energy storage component, wherein the energy storage component can store energy when the switch is on, and the energy stored in the energy storage component is transmitted to a load when the switch is off; a control circuit electrically coupled to the switch, wherein the control circuit compares current flowing through the switch with a current threshold, when the current flowing through the switch is more than the current threshold, the switch is off, and the control circuit determines on and off time of the switch according to the load of the switch voltage-stabilizing circuit, when the load becomes big, the on and off time of the switch is reduced, and when the load becomes small, the on and off time of the switch is increased. The current threshold is constant when the circuit has no light load and becomes low with the load reduced when the circuit has light load.

A switching power source comprises a current comparator 27 for comparing a voltage level of signals acquired by a current detector 9 with a reference voltage level VDT to produce detection signals VCP of first or second level L or H; an edge detector 28a for sensing an edge of drive signal VG supplied to a gate terminal of MOS-FET 3 during the period of transition from turning on to off of MOS-FET 3; and a decision means 28b for receiving a current detection signal VCP from current comparator 27 to produce an output signal VLD when edge detector 28a catches an edge of drive signal VG; wherein decision means 28b produces different output signals VLD of respectively first and second voltage levels L and H under the light and heavy load conditions to precisely and certainly detect on the primary side of transformer 2 the load condition on the secondary side of transformer 2 for improvement in conversion efficiency.

A burst mode resonant power converter with high conversion efficiency has a rectifier, a power factor correction circuit, a resonant circuit, a controller, and a burst mode triggering unit. The maximum frequency switching end of the controller is connected to a maximum frequency variable circuit. When the load is medium or heavy, the maximum frequency variable circuit increases the maximum switch frequency of the controller. When the load is in the no-load or the light conditions, it reduces the maximum switch frequency thereof. Therefore, the controller reduces the number of times that the resonant circuit switches the bridge switch circuit. The conduction cycle of the 50% pulse signal output to the bridge switch circuit becomes longer. Larger energy can be transmitted at a time to the secondary coil of the transformer. This increases the overall efficiency.

A circuitry comprises a converter means for generating an alternating current signal from an energy from an energy source, a piezo transformer with an input and an output, wherein the input of the piezo transformer is electrically coupled to the converter means, to receive the alternating current signal as an excitation on the input side from the converter means, and wherein the output of the piezo transformer is designed to provide an output current, and a load, which is coupled to the output of the piezo transformer, so that output current flows through the same. The load is designed to convert at least part of the electrical energy supplied by the output current flowing through the load into another form of energy. The load is further designed such that a useful power provided in the form of useful energy is substantially proportional to the output current. The circuitry is designed to adjust the output current to a predetermined value. The described circuitry allows the supply of a load with particularly high efficiency, low interference emission and good regulation characteristics.

The invention relates to a drive circuit applied to a power switch tube MOSFET, in particular to a drive circuit of a silicon carbide MOSFET, and belongs to the technical field of drive circuits. The drive circuit aims to solve the problem that when an MOSFET in an existing drive circuit is turned off, the reliability is poor. The drive circuit comprises a PWM control circuit, a drive pulse amplifying circuit, a drive resistor Rg, a first diode D1, a resistor R1, a PNP triode Qoff, a second diode D2 and a capacitor C. According to the drive circuit, the PNP triode Qoff, the resistor R1 and the capacitor C form an MOSFET turn-off circuit; when the MOSFET is turned off quickly, a gate pole positive voltage spike caused by Miller currents is effectively suppressed; meanwhile, a gate pole negative voltage spike can also be suppressed through the second diode D2 and the capacitor C, it is guaranteed that the MOSFET is turned off safely and reliably, and the performance advantages of the silicon carbide MOSFET can be given to full play.

This present invention provides a bridge battery voltage equalizer to equalize the voltages of the serially connected battery strings, comprising at least one battery crossing over an energy-transferring circuit. A plurality of the energy-transferring circuits are interconnected in a bridge architecture. Each energy-transferring circuit having four nodes comprises a first semiconductor switch, a first diode, a second semiconductor switch, a second diode, and an inductor. One end of the first element switch is connected to a negative pole of the first diode thereto. A positive pole of the second diode is connected to one end of the second element switch thereto. The inductor is an energy storing element that crosses over between the negative pole of the first diode and the positive pole of the second diode.

Buck converters having a resonant inductor Lr, resonant capacitor Cr, and synchronous switch Q3 that together provide reduced switching loss and soft switching. In operation, the resonant inductor Lr is charged during a time period A. Then, Lr is freewheeling and provides current to an output inductor Lo. Then, Q3 is turned OFF, and energy from the resonant inductor Lr charges the resonant capacitor Cr. Finally, energy from the resonant capacitor Cr is provided to the output inductor and load. The output power can be adjusted by phase control of the operation of switch Q3. In alternative embodiments, the circuit has a pair of coupled inductors L1 L2 or an isolation transformer 40. The coupled inductors have a polarity selected so that the output voltage is reduced, thereby allowing top switch Q1 to have a greater duty cycle. These circuits feature no body diode loss in the switch Q3.

A switching power source comprises a current comparator 27 for comparing a voltage level of signals acquired by a current detector 9 with a reference voltage level VDT to produce detection signals VCP of first or second level L or H; an edge detector 28a for sensing an edge of drive singal VG supplied to a gate terminal of MOS-FET 3 during the period of transition from turning on to off of MOS-FET 3; and a decision means 28b for receiving a current detection signal VCP from current comparator 27 to produce an output signal VLD when edge detector 28a catches an edge of drive signal VG; wherein decision means 28b produces different output signals VLD of respectively first and second voltage levels L and H under the light and heavy load conditions to precisely and certainly detect on the primary side of transformer 2 the load condition on the secondary side of transformer 2 for improvement in conversion efficiency.

The present invention relates to a method and to a device for adapting the alternating current generated by a generator (1) and the alternating voltage generated by a generator (1) to a grid (8), whereby the generator (1) has at least one excitation coil (2). The power fed into the grid (8) can be flexibly adapted while entailing low switching losses in that a static frequency converter (9) is employed for the adaptation between the generator (1) and the grid (8), and in that, in order to control the power fed into the grid (8), means (3) are provided with which, on the one hand, the strength of the excitation field generated by the at least one excitation coil (2) is regulated and, on the other hand, the phase angle between the frequency converter voltage and the generator or grid voltage is appropriately controlled.

The invention discloses a submodule topology for a modular multi-level transverter. The submodule topology comprises a first switching module, a second switching module, a direct current capacitor and a third switching module, wherein the first switching module and the second switching module are connected in series, the negative end of the first switching module is connected with the positive end of the second switching module, and the first switching module and the second switching module are formed by connecting full-controlled devices and diodes in an antiparallel mode. The positive electrode and the negative electrode of the direct current capacitor are connected with the positive end of the first switching module and the negative end of the second switching module. The third switching module is electrically connected with the first switching module and the second switching module, so that a full-controlled device of the third switching module applies trigger pulses all the time during normal operation and is in a conducting state all the time, and currents of direct current faults can be blocked by locking the trigger pulses of the third switching module when direct current faults happen. The invention further comprises the transverter comprising a submodule and application of the transverter. By means of the submodule topology for the modular multi-level transverter and application of the modular multi-level transverter, a function of isolating the direct current faults is achieved, quantity and switching losses of switching devices in the submodule are decreased, and requirements on trigger simultaneity are reduced.

A controller for controlling a reactive series compensator serially inserted at compensator terminals into a power transmission line for controlling the line current. The controller includes a current control loop and a voltage control loop. A current controller outputs a control voltage (cc.sub.out) indicating a desired compensator terminal output voltage (u.sub.c). A control method selector means generates, in a low output voltage region, a constant reference voltage (u.sub.DC.sup.ref) for the voltage control loop and a variable modulation index mq of a modulation signal m=m.sub.d cos (.omega.t) -m.sub.q sin (.omega.t). In a high output voltage range, the control method selector outputs a constant modulation index m.sub.q and a variable reference voltage (u.sub.DC.sup.ref). The voltage controller outputs the modulation index m.sub.d of the modulation signal m. Furthermore, the control method selector can include a rate limiter for limiting the change rate of the reference voltage (u.sub.DC.sup.ref). In connection with the control method selection and / or the rate limiter, a decoupling control for making the voltage and current control loops independent from each other can be used. The controllers find particular application in transformerless reactive series compensators for single-phase or three-phase control.