1071 results about "Switching cycle" patented technology

A dual output buck-boost power converter operates with a single inductor to achieve high efficiency with automatic or inherent load balancing. Switches associated with the opposite polarity outputs are driven based on feedback signals, with one feedback signal being a reference voltage and another feedback signal being related to an opposite polarity output. The opposite polarity feedback signal is provided to a comparator with a reversed polarity to achieve a simple balanced control that maintains polarity outputs. The power converter delivers power to each output with each switching cycle and uses a single inductor to achieve high efficiency performance.

A control circuit controlling output current at the primary side of a power converter is provided. A waveform detector generates a current-waveform signal. A discharge-time detector detects a discharge-time of a secondary side switching current. An oscillator generates an oscillation signal for determining the switching frequency of the switching signal. An integrator generates an integrated signal by integrating an average current signal with the discharge-time. The average current signal is generated in response to the current-waveform signal. The time constant of the integrator is correlated with the switching period of the switching signal, therefore the integrated signal is proportional to the output current. An error amplifier amplifies the integrated signal and provides a loop gain for output current control. A comparator controls the pulse width of the switching signal in reference to the output of the error amplifier. Therefore, the output current of the power converter can be regulated.

A dual output buck-boost power converter operates with a single inductor to achieve high efficiency with automatic or inherent load balancing. Switches associated with the opposite polarity outputs are driven based on feedback signals, with one feedback signal being a reference voltage and another feedback signal being related to an opposite polarity output. The opposite polarity feedback signal is provided to a comparator with a reversed polarity to achieve a simple balanced control that maintains polarity outputs. The power converter delivers power to each output with each switching cycle and uses a single inductor to achieve high efficiency performance.

A DC power supply device includes transformers that operate with an enhanced efficiency and can reduce the factors that generate ripples in the output voltage to make it possible to downsize the transformers and the smoothing filters of the device, reduce the loss attributable to the switching elements during its constant power output operation and also downsize the heat sink fins so that the overall dimensions of the power supply device may be reduced. The DC power supply device also comprises a pair of switching changers, two output transformers and two rectifying / smoothing sections for rectifying the respective outputs of the switching changers. Each of the two switching changers has the same switching cycle period and the striking phases of the switching elements of one of the switching changers and those of the switching elements of the other switching changer are made variable. Then, a constant power output level is achieved by utilizing the difference of the striking phases of the two switching changers in order to isolate the switching changers from each other for operation and connect them in series or in parallel for operation.

The present invention relates to a converter and a driving method thereof. The converter uses an input voltage to generate an output voltage by a main switch's switching and applies power to a load, senses the current flowing to the main switch to generate a sense voltage, uses a first voltage corresponding to the current applied to the load and a sawtooth waveform signal having a first frequency to control a group frequency of the burst mode, controls the main switch's turn-on timing, and uses the first voltage and the sense voltage to determine whether to turn off the main switch, thereby controlling the main switch's switching. The converter determines the start and end of the period for switching according to the result of comparing the first voltage and the sawtooth waveform signal. Therefore, a converter for having a constant group frequency, preventing audible noise, and preventing output voltage ripple, and a driving method thereof, are provided.

A method and apparatus to implement parallel current mode control that is suitable for digital and analog implementation. A duty cycle algorithm is composed of a voltage term and a parallel current term which depends on the inductor current change between the inductor current value at the beginning of a switching cycle and the reference inductor current value at the end of that switching cycle. Parallel current mode control can be applied to all DC-DC converters, including both non-isolated and isolated topologies. It can also be applied to AC-DC converters with power factor correction.

A switching power converter and method of controlling an output voltage thereof using predictive sensing of magnetic flux provides a low-cost switching power converter via primary-side control using a primary-side winding. The power converter has improved immunity to parasitic phenomena and other variations within the power converter components. An integrator is used to generate a voltage analog that represents magnetic flux within a power magnetic element via an integration of a voltage on a primary-side winding of the power magnetic element. A detection circuit detects the end of a half-cycle of post-conduction resonance that occurs in the power magnetic element subsequent to the energy level in the power magnetic element reaching zero. The voltage of the integrator is stored at the end of the post-conduction resonance half-cycle and is used to determine a sampling point prior to or equal to the start of post-conduction resonance in a subsequent switching cycle of the power converter (which is the predicted zero-energy storage point of the power magnetic element). The primary-side winding voltage is then sampled at the sampling point, providing an indication of the output voltage of the power converter. By predicting the zero-magnetic-energy storage point, the output voltage of a power converter operating in discontinuous or boundary conduction mode can be accurately controlled without being affected by parasitic phenomena or variations in circuit performance over time, input voltage and temperature.

A synchronous rectifier PWM (SR-PWM) controller controls a MOSFET in response to the value of a secondary current and the status of a synchronous signal for both discontinuous and continuous operation mode. The secondary current is generated in a secondary circuit and is detected by two threshold-detection terminals of the SR-PWM controller. The SR-PWM controller produces the synchronous signal by detecting a switching signal of the transformer via a detection terminal of the SR-PWM controller. Furthermore, a delay-time is inserted after the MOSFET is turned off and before the next switching cycle starts to ensure a proper operation of the MOSFET. In one embodiment, an equivalent series resistance (ESR) of an output capacitor can be used as a sensor to detect the secondary current. Therefore, no additional current sensor is required and the efficiency can be improved.

The invention discloses a PFC circuit which is provided with an average current control module, comprising a first boosting circuit, a second boosting circuit and the average current control module. The average current control module comprises a sampling unit, a difference value operating unit, a proportion integral unit and a duty ratio regulating unit which are connected one by one. The duty ratio regulating unit realizes the average current of the inductance current mean in a switch cycle. The invention also discloses an average current control method used for the PFC circuit, and the method comprises the following steps: A. a reference current is produced; B. the current is sampled and the difference value is operated to obtain the inductance current difference value of two parallel branches; C. control signal one of the first boosting circuit is produced through operation; D. control signal two of the second boosting circuit is produced through operation; E. the duty ratio of the two branches is obtained by regulating the duty ratio.

A synchronous rectifier PWM (SR-PWM) controller controls a MOSFET in response to the value of a secondary current and the status of a synchronous signal for both discontinuous and continuous operation mode. The secondary current is generated in a secondary circuit and is detected by two threshold-detection terminals of the SR-PWM controller. The SR-PWM controller produces the synchronous signal by detecting a switching signal of the transformer via a detection terminal of the SR-PWM controller. Furthermore, a delay-time is inserted after the MOSFET is turned off and before the next switching cycle starts to ensure a proper operation of the MOSFET. In one embodiment, an equivalent series resistance (ESR) of an output capacitor can be used as a sensor to detect the secondary current. Therefore, no additional current sensor is required.

A circuit and method for sensing the inductor current flowing to a load from a switching power supply without using a sense resistor in the path of the inductor current. In a synchronous buck converter topology, the inductor current is derived by sensing the voltage drop across the synchronous MOSFET of the half-bridge and reconstructing the current using a sample and hold technique. A ripple current synthesizer is employed to reconstruct inductor current outside the sample and hold window. The sampled product ILoadxRDSon is used to update the ripple current estimator with dc information every switching cycle. The resulting voltage waveform is directly proportional to the inductor current. The inductor current synthesizer of the present invention can also be used in boost converter, flyback converter and forward converter topologies.

An adjustable compensation offset voltage is applied to a comparator to vary turn-off timing of a synchronous rectifier. A comparator output indicates when current through an inductor coupled to the synchronous rectifier should be approaching zero. If the synchronous rectifier is turned off before the current through the inductor reaches zero, the compensation offset voltage is adjusted to delay the synchronous rectifier turn-off for the next switching cycle. If the synchronous rectifier is turned off after the current through the inductor reaches zero, the compensation offset voltage is adjusted to advance the synchronous rectifier turn-off for the next switching cycle. An up / down counter, in conjunction with a digital to analog converter, may be used to provide the adjustment to the compensation offset voltage. The adjustable compensation offset voltage improves the accuracy of synchronous rectifier turn-off in relation to a zero inductor current, thereby improving power converter efficiency.

A buck switching regulator receives an input voltage and provides a switching output voltage on a switch output node using a minimum on-time, variable off-time feedback control loop. The buck switching regulator includes an on-time control circuit for generating a first signal for turning off the high-side switch at the expiration of a first on-time duration or at the expiration of a maximum on-time. The first on-time duration is at least a minimum on-time and is allowed to expand to a maximum on-time when the feedback voltage remains less than a reference voltage. The maximum on-time includes a first maximum on-time and a second, extended maximum on-time. The second maximum on-time is applied when a minimum off-time was used for the high-side switch during the previous switching cycle. In another embodiment, the second maximum on-time is applied only when the switching regulator is not being current limited.

A switched mode power supply (SMPS) includes a transformer with a primary winding, a secondary winding, an auxiliary winding, and a power switch coupled to the primary winding. During one switching cycle, the auxiliary winding provides a feedback signal which includes a first voltage pulse that is induced after the power switch is turned on and a second voltage pulse that is induced after the power switch is turned off. A control circuit includes a circuit for generating a sampling signal for sampling the second voltage pulse in a switching cycle at a time that is determined based on the first voltage pulse in the same switching cycle. A sample-and-hold circuit is configured for sampling and storing the second voltage pulse in response to the sampling signal. A switching signal generating circuit is configured to generate a switching signal for controlling the power switch based on an output of the sample-and-hold circuit.

An inductor current emulation circuit for a switched-mode power supply (SMPS) which is arranged such that its inductor current (IL) goes to zero at least once per switching cycle. The emulation circuit includes an RC integrator connected in parallel across the inductor, and a zero reset switch (ZRS) connected in parallel across the integrator's capacitor. A control circuit operates the ZRS such that it is opened when IL is non-zero, and is closed for a least a portion of the time during each switching cycle when IL is zero such that the capacitor is substantially discharged. In this way, the ZRS essentially recalibrates the emulation circuit when IL is zero. When so arranged, the voltage (VC) across the capacitor emulates IL. The invention may be implemented with either a discontinuous-inductor-current SMPS, or a continuous-bipolar-inductor-current SMPS.

A main circuit of a three-level active neutral point clamped voltage source converter having a pair of additional main switches provides two paths between an output node and a neutral point in which one of the paths involves only switches of an inner pair of switches that are operated at a high frequency. An auxiliary circuit operating at a high frequency for only a brief period during each high frequency switching cycle selects the path involving only the inner switches and provides operation with zero voltage switching and avoids reverse recovery of diodes connected antiparallel with the main and additional main switches. Accordingly, turn-on switching losses in the main switches is avoided and the voltage source converter can be operated at increased frequency to allow reduction in size of magnetic components and full potential power transfer to be achieved.

The object of providing a non-volatile semiconductor memory that stands out by good scalability and a high retention time as well as ensures low switching voltages at low switching times and achieves a great number of switching cycles at good temperature stability is solved by the present invention with a semiconductor memory whose memory cells comprise at least one silicon matrix material layer with open or disturbed nanocrystalline or amorphous network structures and structural voids which has a resistively switching property between two stable states, utilizing the ion drift in the silicon matrix material layer. The memory concept suggested in the present invention thus offers an alternative to the flash and DRAM memory concepts since it is not based on the storing of charges, but on the difference of the electric resistance between two stable states that are caused by the mobility of ions in the amorphous silicon matrix material with an externally applied electric field.

A power converter nearly losslessly delivers energy and recovers energy from capacitors associated with controlled rectifiers in a secondary winding circuit, each controlled rectifier having a parallel uncontrolled rectifier. First and second primary switches in series with first and second primary windings, respectively, are turned on for a fixed duty cycle, each for approximately one half of the switching cycle. Switched transition times are short relative to the on-state and off-state times of the controlled rectifiers. The control inputs to the controlled rectifiers are cross-coupled from opposite secondary transformer windings.

A control system for an electric machine having a rotor position sensor that generates a rotor position signal, a velocity module that generates an electric angular velocity value based on the rotor position signal, a random pulse width modulation module that generates a switching period and a delay for a current cycle, and a phase angle compensation module that sums a sample rate, one half of the switching period, and the delay of a previous cycle and that outputs a delay time. The phase angle compensation module further multiplies the delay time and the electric angular velocity value and generates a compensating angle.

Operation of a switching power converter having an output capacitor having a small equivalent series resistance (ESR) is stabilized and jitter reduced by sensing capacitor current with gain and combining the resulting signal with the output voltage signal to provide a feedback signal to control switching of the power converter. capacitor current can be sensed without interfering with operation of the filter capacitor by providing a branch circuit having a time constant matched to the output or filter capacitor but an arbitrarily high impedance so as to be effectively lossless. The gain provided in the capacitor current signal can be tuned to provide optimally short settling time after load transients; generally within one switching cycle. Matching of time constants and / or tuning of gain can be performed automatically.

A electric motor drive apparatus comprising a voltage control unit performing voltage control processing that determines alternating-current voltage command values serving as command values of the alternating-current voltages to be supplied to the alternating-current electric motor and generates switching control signals for the inverter; and a control mode selection unit selecting a synchronous control mode in which a cycle of electric angle of the alternating-current electric motor is synchronized with a switching cycle of the inverter, or an asynchronous control mode in which the cycles are not synchronized with each other. Current detection processing is performed to detect currents flowing in coils of the alternating-current electric motor in every standard calculation cycle that is set to a half of a cycle of the carrier.

A power converter is disclosed for receiving an input voltage and converting it to a DC output voltage at a different voltage level than the input voltage. It includes a switching power converter for receiving the input voltage on an input and converting the input voltage to an output as the DC output voltage in response to pulse control signals. A switching controller is provided for generating the pulse control signals during a switching cycle and a processor controls the switching controller to define the length and initiation of the switching cycle. A communication interface interfaces with a first data communication bus for receiving data therefrom and with a second communication bus for receiving timing information therefrom. The processor and the switching controller operate in either a first operating mode to control the switching controller and the generation of the pulse control signals independent of timing information, or in a second operating mode to control the timing of the generation of the pulse control signals generated by the switching controller in response to timing information received from the communication bus.

A controller controls the output current by measuring and controlling the switching current of the power converter. A first circuit generates a first signal in accordance with the switching current. A second circuit detects a discharge-time of the transformer. A third circuit generates a third signal by integrating the first signal with the discharge-time. The time constant of the third circuit is programmed and correlated with the switching period of the switching signal, therefore the third signal is proportional to the output current. A switching circuit generates a switching signal and controls the pulse width of the switching signal in accordance with the third signal and a reference voltage. Therefore, the output current of the power converter can be regulated.

A lighting device (1) comprises a plurality of LEDs (11-14) producing light (21-24) of mutually different colors. The LEDs are driven in switching cycles (63) with a duty cycle controlled supply current of constant magnitude. In each switching cycle, each LED is first switched ON (61) and then switched OFF (62).In a measuring mode, during one switching cycle (63B), all ON phases of all LEDs are briefly interrupted, except for one LED (11), so that a light sensor (70) measures the light from this one LED. This measurement can be used to adapt the duty cycle of this one LED. In the next switching cycle (63C), the interruption of the ON phases is compensated by extending the ON phases of all LEDs except said one LED, the extension having a duration equal to the duration (τD) of the interruption.

An arrangement for measuring current through a phase section of a buck mode DC-DC converter includes an auxiliary integrated circuit containing an auxiliary power MOSFET and a pilot MOSFET coupled in parallel with a current path through a high side MOSFET of a half-bridge of the converter. The pilot MOSFET has a current path coupled to a current measurement terminal. The MOSFETs of the auxiliary circuit are time division multiplexed with the high side MOSFET, whereby a determination of current through the auxiliary high side MOSFET is based upon current through the pilot device and the geometric ratio of the size of the pilot device to that of the high side auxiliary MOSFET. The high side MOSFET is activated for a large number of switching cycles relative to the pilot circuitry, but the pilot circuitry is activated sufficiently often to derive a relatively accurate measure of current flow.

A rectifier circuit for use in an energy harvesting application in which mechanical energy is converted into electrical energy by using an AC generator using an active rectifier bridge with a pair of input terminals adapted to be connected to an output of the AC generator and a pair of output terminals, an inductor connected across the output terminals of the active rectifier bridge and a storage capacitor. A pair of output switches selectively connects the storage capacitor across the inductor. A controller controls the active rectifier bridge and the pair of output switches such that in successive switching cycles within any half wave of AC input voltage from the output of the AC generator the inductor is first loaded by current from the output of the AC generator and then discharged into the storage capacitor. An energy harvesting system which uses an AC generator for generating electrical energy out of mechanical energy, a rectifier circuit which is connected with the input to the output of the AC generator and a low power wireless system as application unit. A method of rectifying an AC output voltage of an AC generator for use in an energy harvesting application.