40results about How to "Achieving Zero Voltage Switching" patented technology

The invention relates to a cascade two-way DC-DC converter, composed of two parts: nonisolated two-way DC-DC converter and high-frequency DC transformer, where the former includes circuittopologies such as two-way boost, two-way buck, two-way boost-buck, etc. and the latter is composed of high-frequency inverter/rectifier, high-frequency transformer, and high-frequency rectifier/inverter unit, where the first and fourth ones include push-pull circuit, half-bridge circuit, full-bridge circuit, push-pull forward circuit, double-tube forward circuit, active clamped forward circuit, nonsymmetrical half-bridge circuit, and other circuits. It implements two-way energy flow and electrical isolation, where all its switch tubes are zero-voltage switches, and has the advantage of relatively independent two parts, convenience for control, high conversion efficiency and power density, and simple circuit structure, etc.

A wide load characteristic ZVZCS three-level DC-DC converter relates to a three-level converter. The aim of the invention is to settle the problems of large switching loss, generation of large voltage peak, easily switching tube damage and series electromagnetic interference problem existing in the prior three-level converter. The anode of a voltage source is simultaneously connected with one end of a first capacitor, one end of a fifth capacitor, a drain end of a first insulated-gate type field effect transistor, the cathode of a first diode, the cathode of a fifth diode and the collector electrode end of a fifth triode. The cathode of the voltage source is simultaneously connected with one end of a fourth capacitor, one end of the sixth capacitor, a source end of a fourth insulated-gate type field effect transistor, an anode of a fourth diode, an anode of a sixth diode and the emitter end of a sixth triode (S6). The wide load characteristic ZVZCS three-level DC-DC converter of the invention is also added with an auxiliary rectifying circuit and an active clamp circuit. The wide load characteristic ZVZCS three-level DC-DC converter of the invention has the advantages of high resetting speed of the primary side current, no overshoot voltage of the secondary side, etc. Furthermore the wide load characteristic ZVZCS three-level DC-DC converter of the invention settles the problems of duty ratio loss, primary side circumfluence, parasitic oscillation, etc. The efficiency of the converter is increased. The switching loss and the electromagnetic interference are reduced.

The invention relates to a double-input direct-current converter using a non-isolation type pulse voltage source unit, belonging to the technical field of power electronics. The double-input direct-current converter using the non-isolation type pulse voltage source unit comprises two non-isolation type pulse voltage source units, a blocking capacitor, a transformer, a rectifying circuit and an output filtering circuit. The double-input direct-current converter provided by the invention can utilize two non-isolation type pulse voltage source units with the same structure to separately or jointly supply power to a load and also can utilize the non-isolation type pulse voltage source units with different structures to separately or jointly supply power to the load. In the direct-current converter provided by the invention, a circuit topological structure is simple and the quantity of switching tubes is few; all the switching tubes can realize zero-voltage switching-on/off; and the direct-current converter has the advantages of high efficiency and high power density, so that the direct-current converter is applicable to middle-power and small-power new energy resource joint power supply systems.

The invention relates to an isolation DC-DC power supply module meeting the GJB181 standard. The isolation DC-DC power supply module comprises a fuse tube, an EMI filter circuit, an anti-reverse-connection protection circuit, a transient peak pulse bleeder circuit, a surge current suppression circuit, a Buck-Boost circuit and an LLC resonant conversion circuit which are connected in turn. The self-restoring type fuse tube is selected so that input overcurrent can be avoided; the positive and negative surge peak voltage is controlled to the acceptable degree of the DC-DC switching power supplyby the transient peak pulse bleeder circuit; the problem of excessively high surge current can be solved by the active surge current suppression circuit; the Buck-Boost wide voltage circuit handles the input overvoltage/undervoltage situation; and the LLC resonant converter topology realizes soft switching so that the overvoltage stress of the switch MOSFET can be reduced and the stored electromagnetic energy can be increased, and the switching frequency and efficiency of the converter can be effectively enhanced.

The invention provides a resonant converter based on ON/OFF control. The resonant converter comprises a primary side square wave inversion circuit I, a primary side LLC resonance circuit II, a transformer T, a secondary side full-bridge rectification circuit III and an output resistance load Ro. The resonant converter is characterized in that two auxiliary two-way switches are added to the primaryside square wave inverter circuit I; ON/OFF control is adopted for the auxiliary two-way switches, so that the resonant converter can work in a full-bridge LLC resonant converter mode and can also work in a half-bridge LLC resonant converter mode. Due to the topological structure of the resonant converter and the switching type control mode of the resonant converter, the switching frequency change range of the resonant converter is narrow, ultra-wide-range voltage gain adjustment is achieved, zero-voltage switching of a primary side switching tube is achieved, zero-current switching of a secondary side rectifying diode is achieved, and switching loss is reduced.

The invention discloses a digital soft start method of a full-bridge LLC converter. The method includes the steps of: S1. setting a resonant inductive current upper limit I<rh> and lower limit I<rl> for an initial soft start, and accurately limiting surge current within a range in which a circuit stably works; S2. according to design parameters of the circuit, by solving a differential equation, accurately calculating the switching time of each switching tube; S3. keeping switching frequency f1 unchanged till an output voltage can reach a stable value Vo1 at the switching frequency; and S4. in a fixed time interval, continuously decreasing from the switching frequency of f1 till the output voltage reaches a rated output voltage Vo, or when f1 is smaller than resonant frequency fr, ending a soft start. The digital soft start method performs optimized design of a soft start process, according to the design parameters of the circuit, sets the upper limit and lower limit of a resonant network current, accurately calculates the switching time of each switching tube through the differential equation, and then uses a digital control table look-up method to strictly control the whole soft start process.

The invention provides an auxiliary resonant conversion pole T-type three-level soft switch inversion circuit and a modulation method thereof. The circuit comprises a T-type main inversion circuit, anauxiliary resonant conversion circuit, a filtering circuit and a load, wherein the T-type main inversion circuit comprises four switch tubes and two same support capacitors, the four switch tubes areprovided with diodes which are reversely connected in parallel, the auxiliary resonant conversion circuit comprises two auxiliary switch tubes, four resonant capacitors and a resonant inductor, the two auxiliary switch tubes are provided with diodes which are reversely connected in parallel, and the filtering circuit is an LC filtering circuit. According to the modulation method provided by the invention, zero-voltage on/off of the main switch tube and zero-current on/off of the auxiliary switch tube can be achieved. By the circuit, the T-type three-level hard switch loss can be reduced, thesystem efficiency is improved, and the electromagnetic interference is reduced.

The invention provides an auxiliary resonant pole active clamp three-level soft switching inverter circuit and a modulation method thereof. The circuit includes an active clamp main inverter circuit,an auxiliary resonant commutation circuit, a filter circuit, and a load. The active clamp main inverter circuit comprises six switching tubes with anti-parallel diodes and two identical supporting capacitors. The auxiliary resonant converter circuit comprises two auxiliary switching tubes with anti-parallel diodes, two resonant capacitors and one resonance inductor. The filter circuit is an LC filter circuit. The modulation method provided by the invention can realize the zero voltage switch of the main switch tube and the zero current switch of the auxiliary switch tube. The active clamp three-level hard switching loss is reduced, the system efficiency is improved, and the electromagnetic interference is reduced.

The invention relates to a resonant-pole soft switching inversion circuit for driving of a brushless direct current motor. The inversion circuit is characterized by comprising a direct current power supply, a three-phase pulse width modulation inverter and the brushless direct current motor, wherein an auxiliary resonance circuit is arranged between the direct current power supply and the three-phase pulse width modulation inverter, and comprises a single-phase transformer, three auxiliary switches and two diodes. According to the inversion circuit, a large capacitor used for forming neutral point voltage is not arranged between direct current buses, and no neutral point potential change exists, so that main switches on bridge arms of the inverter can adopt a relatively simple single-side modulation method; an auxiliary circuit of the three-phase inverter is simple in structure, and only comprises three auxiliary switch devices, two auxiliary diodes and a high-frequency transformer; and zero voltage switching of main switch devices of the inverter and zero current switching of the auxiliary switch devices are realized by utilizing resonance between an equivalent inductor of the high-frequency transformer in the auxiliary circuit and a buffer capacitor parallel to the main switches of the lower bridge arm.

The invention discloses a soft switch resonance DC converter reducing the voltage stress of a diode. The soft switch resonance DC converter absorbs a part of leakage inductance of a transformer and takes the part as a resonance inductance, and absorbs a junction capacitance of a switch tube and a junction capacitance of the diode and takes the absorbed junction capacitance as part of the resonanceinductance. The related converter can realize zero-voltage switching ON/OFF of a switch tube and the diode and zero-current switching OFF of the diode, the switching loss of the converter is almost 0, the efficiency of the converter is improved, the voltage stress of the diode is clamped to two times of the output voltage, and the voltage stress is reduced.

The invention discloses a method for asymmetrically controlling a simplified-type three-phase three-level direct-current converter. According to a control timing sequence, the conductive time of a first switching tube, the conductive time of a third switching tube and the conductive time of a fifth switching tube are the same, the variation range of the duty ratio is 0-1/2, the turn-on time of the first switch, the turn-on time of the third switching tube and the turn-on time of the fifth switching tube are separated by 1/3 switching period, and output voltages are controlled by adjusting the duty ratio of the first switching tube, the duty ratio of the third switching tube and the duty ratio of the fifth switching tube. The conductive time of a second switching tube, the conductive time of a fourth switching tube and the conductive time of a sixth switching tube are the same and are correspondingly and complementarily conductive with the fifth switching tube, the first switching tube and the third switching tube respectively, and the certain delay time is reserved between every two complementary switching tubes. According to the method, voltage stresses of all the switching tubes are all a half of input voltages, the current stresses and output filter inductances of the switching tubes can be reduced, the zero voltage switching of the switching tubes can be achieved, and the automatic equalization of input partial pressure capacitor voltages can be achieved.

The invention discloses a dual-active bridge type converter for realizing wide-range soft switching. The converter comprises a full-bridge switching network, an inductance energy storage network, a transformer transmission network and a rectification filter network which are connected in sequence, the input end of the full-bridge switching network is connected with an input direct current source, and the output end of the full-bridge switching network is connected with the input end of the inductance energy storage network; the input end of the rectification filter network is connected with the output end of the transformer transmission network; and the inductance energy storage network comprises a first inductor L1 and a first switch S1, and the first switch S1 is connected with the primary side of a second transformer T2 of the transformer transmission network in parallel to form a second parallel branch. The dual-active bridge type converter is simple in structure, the battery voltage is selected according to the second selector switch S2, then the first switch S1 is switched, and the number of transformers of the inductor energy storage network is changed, so it is guaranteed that even if the load voltage is changed, the input and output voltage transmission ratio k of the dual-active bridge type converter is kept unchanged.

The invention discloses a control strategy of a wide-load-range zero-voltage switch phase-shifted full-bridge converter. The control strategy comprises the following steps: S1, sampling a primary side current i of the wide-load-range zero-voltage switch phase-shifted full-bridge converter; S2, calculating a phase angle theta 1 between a turn-on moment of an auxiliary switching tube Q5 and a turn-off moment of a main switching tube Q1, and a phase angle theta 2 between the turn-on moment of an auxiliary switching tube Q5 and the turn-off moment of the main switching tube Q1; and S3, controlling the turn-on moments of the auxiliary switching tube Q5 and the auxiliary switching tube Q6 according to the theta in the step 2. Primary side current detection is introduced for control, and the auxiliary switching tubes Q5 and Q6 can be automatically switched on according to the relationship with the magnitude of the current, which means that the duty ratios of the auxiliary switching tubes Q5 and Q6 change along with the change of the current. Primary side current detection enables the auxiliary switching tubes Q5 and Q6 to be switched on in a self-adaptive mode in a full-load working condition, and the efficiency and stability of the converter are improved.

The invention relates to a ship-borne power source. The ship-borne power source at least comprises a preceding stage DC/DC (Direct Current) unit which is composed of an input filter, a DC/DC converting circuit, a rectifier filter circuit, a detection loop, a PWM (Pulse-Width Modulation) control circuit and an auxiliary power source, and a DC/AC (Alternating Current) unit. The AC input after passing through the input filter is divided into two paths; one path after being input to the DC/DC converting circuit and the rectifier filter circuit is output to a load while the other path is input to the input end of the auxiliary power source; the auxiliary power source generates a working voltage needed by the PWM control circuit and provides the voltage to the PWM control circuit; the DC output of the rectifier filter circuit is electrically connected to a voltage and current detection loop; the output end of the voltage and current detection loop is electrically connected to the PWM control circuit; the PWM control circuit controls the DC/DC converting circuit to output a constant voltage or constant current output; the output of the DC/DC converting circuit after passing through the rectifier filter circuit inputs DC340V DC voltage to the DC/AC unit. The ship-borne power source has the characteristics of good safety, high reliability and the like.

The invention discloses a capacitor clamping type three-level direct-current converter adopting an asymmetric bidirectional switch. The capacitor clamping type three-level direct-current converter comprises a voltage source Vin, a voltage dividing capacitor Cin1, a voltage dividing capacitor Cin2, a primary side inversion unit and a transformer T. Input high-voltage direct current obtains alternating-current square waves on the primary side of the transformer by controlling on and off of a switch tube, passes through the transformer T, then is connected with a rectifier bridge on the secondaryside of the transformer, and then outputs direct-current voltage through the filter circuit. The problem of unbalanced current existing in an existing three-level circuit is solved. The turn-off current of a switching device in the circuit is reduced. The current stress of the switch tube is reduced. Zero-voltage zero-current turn-on and turn-off of the switch tube are achieved. The loss of the whole circuit is reduced. The reliability of the circuit is enhanced.