Tdk Corporation

Kabushiki Kaisha Toshiba

Min Lin

Ken Matsuura

Kazuaki Yuuki

Akira Miyazaki

Mitsuhiro Numazaki

Manabu Matsuoka

Akihiko Ujiie

Hitoshi Kinoshita

Yosuke Nakazaka

A FET driving circuit includes: inputs into which a DC voltage is inputted; outputs connected to gate and source electrodes of a FET; a switch; a capacitance connected across the switch; and an LC resonance circuit connected in series with the switch across the inputs. A voltage generated across the switch during switching is outputted to drive the FET. The LC resonance circuit has a first connector connected to one input and a second connector connected to the switch, and is configured with a path including an inductance and a path including an inductance and a capacitance. An impedance between the first and second connectors has two resonant frequencies. The impedance has a local maximum at the lower resonant frequency, which is higher than a switching frequency, and a local minimum at the higher resonant frequency, which is around double the switching frequency.

FET driving circuit

A zero current detection circuit includes: one detection winding that is magnetically coupled to a boost inductor of a bridgeless totem pole PFC for converting an AC input voltage to a DC output voltage, has one end connected to ground, and generates a zero current detection signal, which changes in proportion to a boost inductor voltage, at another end; a resistor with one end connected to the other end of the detection winding; a clamp composed of two diodes connected to each other in series with a same forward direction, which clamps the inputted zero current detection signal to the ground potential and a positive power supply voltage to convert to a rectangular signal; and a pulse outputter with a comparator which compares the rectangular signal and a comparison voltage and outputs detection pulses with falling edges that are synchronized with an inductor current reaching zero.

Zero current detection circuit for bridgeless totem pole power factor correction converter and bridgeless totem pole power factor correction converter

A switching power supply includes a power converter with an inductor and first and second switches that converts a voltage Vac to a voltage Vdc, a detector with a winding that detects zero timing of an inductor current, and a driving signal generator that switches on the second switch based on the zero timing and then switches on the first switch. The driving signal generator ends a period Tbefore the zero timing by executing a measuring process for an on period Tof the second switch, a process that calculates the period Tfrom T=T&#xd7;|Vac|/(Vdc&#x2212;|Vac|)&#x2212;Tc using a correction time Tc, a process that switches on the first switch for only the period T, a process that measures an elapsed time between the periods Tand T, and a process that changes the correction time Tc so that the elapsed time becomes a target time.

Switching power supply with a measuring and calculating process for the switching times

A power converter includes: two DC input terminals that input a DC input voltage; two DC output terminals that output a DC output voltage; an isolation transformer with a primary winding and a secondary winding; a switch that is connected across the two DC input terminals in a state where the switch is connected in series to the primary winding and that switches the DC input voltage; an LC resonance circuit that includes an inductance and a capacitance and is connected in parallel to the primary winding; a first resonant capacitance that is connected in parallel to the switch; a second resonant capacitance that is connected in parallel to the secondary winding; and a rectifying and smoothing circuit that rectifies and smoothes a voltage generated across both ends of the second resonant capacitance and outputs as the DC output voltage across the two DC output terminals.

Power converter

A FET driving circuit includes: two inputs for inputting a DC voltage; two outputs respectively connected to gate and source electrodes of a FET; a switch; a resonant capacitance connected between both ends of the switch; and an LC resonance circuit connected between the inputs and both ends of the switch. When the two inputs are shorted, frequency characteristics of an impedance of the LC resonance circuit include, in order from a low to a high-frequency side, first to fourth resonant frequencies. The first resonant frequency is higher than a switching frequency of the switch, the second resonant frequency is around double the switching frequency, the fourth resonant frequency is around four times the switching frequency, and the impedance has local maxima at the first resonant frequency and the third resonant frequency and local minima at the second resonant frequency and the fourth resonant frequency.

A switching power supply device generates a DC output voltage, which is to be outputted to a load and is based on a DC input voltage. The switching power supply device includes n converter units and a control unit. The DC output voltage is compared with a voltage range selected out of a first voltage range and a second voltage range set in advance and the control unit executes one of first driving control to fourth driving control depending on the present driving control and the comparison result for the DC output voltage. By switching between the first to fourth driving control, the control unit changes the number of converter units to be driven.

Switching power supply device comparing first and second voltage ranges

A power converter includes: input terminals for inputting a DC voltage; output terminals for outputting an AC voltage; a switch; a first resonant capacitance connected between both ends of the switch; a first LC resonance circuit connected in series with the switch between the output terminals; and a second LC resonance circuit connected between the input terminals and the switch. The first LC resonance circuit includes an inductance and a capacitance in series. When the input terminals are shorted, frequency characteristics of an impedance of the second LC resonance circuit include first to fourth resonant frequencies. The first resonant frequency is higher than a switching frequency of the switch. The second and fourth resonant frequencies are around double and four times the switching frequency. The impedance has local maxima at the first and third resonant frequencies and local minima at the second and fourth resonant frequencies.

Power converter having resonant frequencies around two and four times the switching frequency

A power conversion apparatus includes: DC input terminals for inputting a DC voltage; AC output terminals for outputting an AC voltage; a switching element; a first resonant capacitance connected across the switching element; a first LC resonance circuit that has an inductance and a capacitance connected in series and is connected together with the switching element between the AC output terminals; and a second LC resonance circuit connected in series together with the switching element between the DC input terminals. The second LC resonance circuit includes a first connector portion connected to one DC input terminal and a second connector portion connected to the switching element, and has a first current path, which includes an inductance, and a second current path, which includes a series circuit with an inductance and a capacitance, formed between the first connector portion and the second connector portion.

DC/AC power conversion apparatus having switchable current paths

A control circuit according to an embodiment of the present invention is configured to control a switching element of a switching power supply. The control circuit includes a comparator having a first input terminal configured to receive an output voltage of the switching power supply. The comparator has a second input terminal that is connectable to a positive terminal of a reference voltage source. The comparator has an output. The output brings the reference voltage to a first voltage while the output signal takes a first voltage level. The output brings the reference voltage to a second voltage while the output signal takes a second voltage level. The constant voltage source has a positive terminal connected to a negative terminal of the reference voltage source and a ground of the comparator.

Control circuit and switching power supply

A switching power supply device generates a DC output voltage based on a DC input voltage, and includes n converter units and a control unit. The control unit executes first driving control that drives k1 (where 0&#x2264;k1&#x3c;n) out of the n converter units when the DC output voltage has risen to an upper limit value of the reference voltage range and second driving control that drives k2 (where k1&#x3c;k2&#x2264;n) out of the n converter units when the DC output voltage has fallen to a lower limit value of the reference voltage range. During the first driving control, if the DC output voltage Vo reaches a first value above the upper limit value, k1 and k2 are decreased by a value k0. During the second driving control, if the DC output voltage Vo reaches a second value below the lower limit value, k1 and k2 are increased by the value k0.

Switching power supply device

According to one embodiment, there is provided an electric-vehicle driving apparatus which consumes regenerative energy by a brake resistor and can decrease harmonic components generated by a brake-chopper switching circuit. Plural brake-chopper switching circuits are provided in parallel for each inverter. Harmonic components generated by the brake-chopper switching circuits are decreased by changing phases or frequencies of triangular carrier waves of the switching circuits, relatively to each other.

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Tokyo, Japan

Min Lin