Sanken Electric Co., Ltd.

Other

Ryuichi Furukoshi

Osamu Ohtake

Akio Iwabuchi

Shinji Aso

Hiroshi Usui

Yoichi Kyono

Mizuki Utsuno

Yukinari Fukumoto

Youichi Terasawa

Yasushi Tasaka

Toshitaka Shiga

Keiichiro Ozawa

An integrated circuit for digitally controlling a critical mode power factor correction (PFC) circuit according to one or more embodiments may include: an output voltage detector and a switching current detector; an A/D converter and a sample and hold circuit that perform analog-to-digital conversion of an output signal of the output voltage detector and the switching current detector; an arithmetic unit that performs calculation based on the output signal of the A/D converter and generates a pulse signal to turn on/off a switching device of the PFC circuit; a correction value calculator that calculates, based on a switching frequency of the PFC circuit, a correction value for linearly correcting the output signal of the A/D converter; and an adder that adds the correction value to the output signal of the A/D converter to correct the output signal of the A/D converter and inputs the corrected output signal to the arithmetic unit.

Integrated circuit and method of digitally controling critical mode power factor correction circuit

A method may include detecting an output voltage of the output smoothing capacitor in the bridgeless interleaved power factor correction circuit of a critical mode, comparing the detected output voltage with a reference voltage, controlling the first and the second half-bridge circuits included in the bridgeless interleaved power factor correction circuit of the critical mode to be on and off based on an error signal between the output voltage and the predetermined reference voltage, measuring ON time of a synchronous rectification switch operation of the first half-bridge circuit by measuring a time period between OFF timing of an active switch of the first half-bridge circuit and output of a differentiation signal generated by a differentiation circuit included in the bridgeless interleaved power factor correction circuit of the critical mode; and assigning the measured time to next ON time of the synchronous rectification switch operation of the second half-bridge circuit.

Integrated circuit and method of synchronous rectification control of bridgeless power factor correction circuit

Embodiments of this disclosure provide a control apparatus and method for a current resonance circuit and a current resonance power supply. The control method includes: performing integration on a resonance current of the current resonance circuit or a switching current of one or more switching elements to generate an integration signal; generating a feedback signal of the current resonance circuit; comparing the integration signal with the feedback signal, and generating a measurement signal according to a comparison result; performing digital filtering on the measurement signal; and according to the measurement signal after filtering, generating a pulse width modulation signal controlling the switching elements.

Control apparatus and method for current resonance circuit and current resonance power supply

A device and method for calculating switching time. The device includes: a digital calculator configured to calculate a next on time according to an output voltage signal and an inductor current signal detected during an on period of a switching element and calculate a next off time according to the next on time, an input voltage signal and the output voltage signal; and a signal generator configured to generate a pulse width modulation signal for controlling the switching element, according to the next on time and the next off time. Therefore, a digital controlling manner is provided, not only the number of components and the cost are decreased, but also detection accuracy is improved with a simple structure.

Device and method for calculating switching time

The present invention includes: a series circuit formed of a reactor Lr, a primary winding P of a transformer T, and a capacitor C; a full-wave rectifier/smoothing circuit D, D, Cconfigured to perform full-wave rectification and smoothing on a voltage generated in a secondary winding S of the transformer thereby to extract a DC voltage; a control circuit FFconfigured to set a first ON time of the first switch element Qand a second ON time of the second switch element Qto the same predetermined time thereby to alternately turn on and off the first switch element and the second switch element; and a first ON time controller I, Cconfigured to set one of the first ON time and the second ON time, shorter than the predetermined time, under light-load conditions, based on the DC voltage detected by a detector

Current resonance type power supply device

The present invention includes: a series circuit formed of a reactor Lr, a primary winding P of a transformer T, and a capacitor C; a full-wave rectifier/smoothing circuit D, D, Cconfigured to perform full-wave rectification and smoothing on a voltage generated in a secondary winding S of the transformer thereby to extract a DC voltage; a control circuit FFconfigured to set a first ON time of the first switch element Qand a second ON time of the second switch element Qto the same predetermined time thereby to alternately turn on and off the first switch element and the second switch element; and a first ON time controller I, I, Cconfigured to set one of the first ON time and the second ON time, shorter than the predetermined time, under light-load conditions, based on the DC voltage detected by a detector

A power factor correction circuit includes: an ON time setting unit, which sets an ON time period of the switching element based on the output voltage; a bottom detection unit, which detects a bottom when a voltage between both ends of the switching element is damped-oscillated while the switching element is being turned off; and a bottom skip controller, which causes the switching element to perform quasi-resonant if a ratio of the ON time period set by the ON time setting unit to a regeneration period of a current flowing through the reactor while the switching element is being turned off is less than or equal to a predetermined value, and turns on the switching element at a timing when a next bottom is reached after one bottom skipped from an initial bottom if the ratio is greater than the predetermined value.

Power factor correction circuit having bottom skip controller

A current resonant power source apparatus includes a series circuit (Lr, P, C) connected between switch elements Qand Qand a capacitor C, a full-wave rectifying and smoothing circuit (D, D, C) for providing a DC voltage, a control circuit of Qand Q, a voltage detectorof the DC voltage, a current detector of the primary winding P, a soft-start time constant setting unit, and an ON time controller. If a voltage generated to a time constant is smaller than a set voltage, the ON time controller sets an ON time for Qand Qaccording to the DC voltage and soft-start signal, and if it is equal to or greater than the set voltage, sets one of the first and second ON times according to the current from the current detector.

Current resonant power source apparatus

Embodiments of the invention may include: a series circuit connected to a junction of a first switch element and a second switch element connected in series across ends of a DC power supply, and to one end of the DC power supply, and formed of a primary winding of a transformer and a capacitor; a rectifier/smoothing circuit configured to rectify and smooth a voltage generated in a secondary winding of the transformer thereby to extract a DC voltage; a control circuit configured to alternately turn on and off the first switch element and the second switch element; a voltage detector configured to detect a voltage of the DC power supply; and a duty controller configured to, under a light-load condition, set a duty ratio between the first switch element and the second switch element closer to 50% as a value of the voltage detected by the voltage detector becomes larger.

A drive circuit drives a normally-on high-side switch Qand a normally-off low-side switch Qthat form a series circuit connected in parallel with a DC power source. The drive circuit includes a controllerthat outputs a control signal to turn on/off the high- and low-side switches, a rectifier Dhaving a first end connected to a connection point of the high- and low-side switches, a capacitor Cthat is connected to a second end of the rectifier and a first end of the DC power source and serves as a power source for the controller, and a driver (A, AND, Q, Q) that turns on/off the high- and low-side switches according to the control signal from the controller and a voltage from the capacitor.

Drive circuit

A device for driving switching elements is provided with a potential detectorwhich provides drive circuitwith signals in response to differences among potentials at junctionstoof first and third resistors, third resistorand first control MOS-FET, second and fourth resistorsand fourth resistorand second control MOS-FETso that drive circuitsupplies drive signals to a gate terminal of a first MOS-FETbased on potentials in first and second series circuitsand. When appropriate resistance values are selected for first to fourth resistorsto, potential detectorprecisely detects the potential at each junctiontoto produce detection signals and prevent malfunction of drive circuiteven upon occurrence of abnormal signals or noises resulted from abrupt potential rise.

Device for driving switching elements

A power converter is provided which comprises two main MOS-FETsconnected in series to a DC power source; an oscillatorwhich has two capacitorsconnected in parallel to main MOS-FETs; a primary windingof a transformerconnected between a junction of two main MOS-FETsand a junction of two capacitors; an electricity controllerwhich comprises first and second regulatory MOS-FETsconnected between respectively one and the other ends of a secondary windingof transformerand a speaker; a polarity detectorfor detecting the polarity of AC voltage produced on secondary windingof transformerby the on and off operation of MOS-FETsto generate detection signals; and a drive circuitfor receiving detection signals from polarity detectorto control the on and off operation of first and second regulatory MOS-FETsto simplify the circuit configuration and improve power conversion efficiency in the power converter.

Power converter

There are included an actuation unit supplying an actuation power to a control unit to start a switching operation of a switching element when an alternating-current power sources turned on, and stopping supply of the actuation power to the control unit after the switching operation of the switching element is started; an overheat detection unit being thermally coupled with the actuation unit and detecting an abnormal condition due to overheating of the actuation unit; a latch maintaining an inoperative state of the switching element at the event of an abnormal condition other than the abnormal condition due to overheating of the actuation unit; and an actuation controller configured to discharge an electrical charge of a smoothing capacitor while the latch maintains the inoperative state of the switching operation to speedily reset the latch unit when the alternating-current power source is turned off, and to stop the actuation unit in response to a detection signal from the overheat detection unit.

Switching power supply apparatus

A DC converter includes a time difference detector to detect a time difference between a point around which a main switch provides a minimum voltage after an auxiliary switch turns off and a point at which the main switch turns on, an integrator to integrate the output of the time difference detector, and a first delay circuit to control a turn-on point of the main switch according to the output of the integrator and the output of the time difference detector. The first delay circuit operates to minimize the output of the time difference detector according to the output of the integrator and controls a turn-on point of the main switch in a pulse-by-pulse manner according to a pulse-by-pulse control signal based on the output of the time difference detector.

DC converter

A synchronous commutation DC-DC converter comprises a current detection transformer () for detecting currents (I, I) flowing through the primary circuit, first and second DC bias power sources () generating bias voltages (V, V) larger than the voltage corresponding to the exciting current of a transformer (), and first and second comparators () for driving first and second commutation MOS-FETs () when the detection voltage (V) of a current detection resistor () exceeds the bias voltages (V, V) of the first and second DC bias power sources (). Since each commutation MOS-FET () in the secondary circuit is driven in synchronism with the currents (I, I) of the primary circuit from which the exciting current component of the transformer () is removed, it is possible to minimize switching loss of each commutation MOS-FET () in the secondary circuit and enhance conversion efficiency of the synchronous commutation DC-DC converter.

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Niiza, Japan

Ryuichi Furukoshi