153 results about "Power factor correction capacitors" patented technology

A new class of Three-Phase Isolated Rectifiers with Power Factor Correction provides a high efficiency, small size and low cost due to direct conversion from three-phase input voltage to output DC voltage.

A centralized device for supply voltage control of a load with power factor correction condensers for lighting engineering applications has an array converter for obtaining a portion of power, with a plurality of switches located between the network sinusoidal supply and the load. The centralized device has controlling and regulating means for managing both the activation and deactivation states of the switches of the array converter so as to avoid sudden voltage changes across the load and provide for control of the load voltage.

A power device is provided for filtering or dampening harmonics and optimizing the power factor in power distributions systems. A device for a 3-phase power system comprises series inductors able to communicate between an AC power source and a non-linear load. Connected in parallel to the series inductors, at the junction with the non-linear load, are shunt inductors used to trap harmonic currents. Power factor correction capacitors are connected to the ends of the shunt inductors. The series inductor and shunt inductor are used to form a coaxial reactor assembly, which further comprises a reactor core. The coaxial reactor assembly is formed by winding a first inductor around the core and then winding a separate second inductor around the perimeter of the first inductor. In another embodiment, the device includes a third inductor to achieve better dampening and power factor performance.

The invention discloses an adaptive control method of a power factor. The adaptive control method comprises the following steps of: generating three voltage reference values by calculating, multiplying the three voltage reference values, taking a product of the three voltage reference values as a current reference value, comparing the current reference value with a direct current bus current, and outputting a calculation result after carrying out current error compensation processing; determining a duty ratio by virtue of the calculation result to form a pulse signal, controlling the make-break operation of a chopper to carry out chopping processing on a direct current voltage rectified and output by a rectifier bridge, generating a smooth direct current bus current and an alternating current input current in a same phase with an alternating current input voltage, improving the power factor, and reducing the current harmonic distortion ratio. A power factor correction method, provided by the invention, can be used for realizing the adaptive control on alternating current power supplies in different frequencies. The adaptive control method of the power factor is applied into variable frequency air conditioner products, and can be suitable for air conditioners based on inputs of 50-Hz and 60-Hz alternating current power supplies; and according to the adaptive control method of the power factor, a design purpose that a development is suitable for multiple types of machines is really achieved, the development period is shortened, and the research and development costs are lowered.

The invention provides a PFC (power factor correction) circuit based on a delta-sigma modulation technique and a duty ratio control method thereof. The PFC circuit comprises an input voltage ADC (analog to digital converter), a duty ratio generation circuit, an output voltage processing circuit and a digital pulse width modulation circuit in electrical connection, wherein the duty ratio generation circuit comprises a switching frequency control circuit, a Ton counting circuit and a delta-sigma modulation circuit in electrical connection; and the output voltage processing circuit comprises an output voltage ADC, a digital PI (proportional integral) compensator and a rapid dynamic response circuit in electrical connection. The delta-sigma modulation technique is utilized in the PFC circuit to realize the duty ratio control method. According to the invention, the response speed of the input voltage change can be improved, the iL waveform of the input inductive current is adjusted, the frequency spectrum of the pulse width signal is shaped, the power factor is improved and the output voltage is stabilized.

A power factor correction controller is utilized for a power factor correction circuit in a critical conduction mode of an electric power converter. The power factor correction controller generates a control voltage according to an output voltage outputted from the electric power converter, and utilizes a first threshold value to detect the control voltage. The power factor correction controller can control the power factor correction circuit to operate in different modes according to various levels of a load. Therefore, an objective according to the present invention for reducing electric power consumption of the electric power converter in a light load or a no-load mode and improving energy transmission efficiency can be attained.

The invention discloses a boost power factor correction (PFC) controller. The switching-on and switching-off of a power switching tube are controlled by switching on and switching off a signal generation circuit, so that the power switching tube is controlled to operate in a constant-frequency or variable-frequency mode. Therefore, when the boost PFC controller is used, the constant operating frequency of the power switching tube can be realized without control of a clock signal, so that the design difficulty of an input electro-magnetic interference (EMI) filter is reduced; moreover, the boost PFC controller can control the variation range of the operating frequency of the power switching tube. Compared with the conventional switching frequency jittering control technology, the invention has the advantages that: the boost PFC controller is quite convenient and has simple control scheme; frequency jittering operation can be realized; meanwhile, in the process of realizing PFC, the waveform of an input voltage is not required to be detected; the number of controller pins and peripheral devices is smaller; and cost is reduced.

The invention provides a PFC (power factor correction) control method with high input power factor and a control circuit thereof. The method comprises the steps of controlling a switching tube to be switched on and switched off according to the principle of leading impulse area to be equivalent, and leading input inductive current and sinusoidal half-wave current to have the equivalent impulse area in each switching period, thereby realizing the high power factor (PF); furthermore, the higher the switching frequency, the closer to 1 the PF value is. In the control circuit, a circuit topological structure of a Boost converter and a control circuit for realizing a variable duty ratio sequence jointly constitute a PFC stage of a commonly used LED (light-emitting diode) driving power supply, the front stage of the PFC stage is connected with the output end of a non-controllable rectifier bridge of a single-phase diode via an input filter capacitor, the back stage of the PFC stage is connected with a DC/DC (direct current/direct current) stage of the commonly used LED driving power supply via an output filter inductor and an output filter capacitor. By adopting the PFC control method, not only the very high input power factor can be realized, but also output voltage ripple can be reduced; furthermore, the control circuit is simple and easy to realize an analog circuit, thereby being conductive to large-scale integration.

A method is directed to providing adaptive digital control for the PFC front-end of a switching mode power supply. The method uses an evaluation model to adjust control loop parameters of a control algorithm used by a controller on the primary side of the power supply. The method performs a series of step adjustments of the control loop parameter values to determine optimized values. In some implementations, the method determines and compares the line current THD corresponding to different control loop parameter values. The method provides simplified digital control loop design, optimizes PFC front-end performance, improves system efficiency by decreasing harmonic ripples, and reduces labor cost and time to market due to shorter research and development phase. System performance optimization is fully adaptive adjusted for changes in operating conditions due to, for example, environmental and temperature variations.

The invention discloses a power factor correction converter with a wide load range. When the converter works in a CCM mode in a full load way, traditional average current control is used as a control strategy; and when the converter works in MCM and DCM modes in a light load way, improved average current control is used as the control strategy. Inductive current sampling correction is increased so that the current obtained by sampling equals to an average value, the feedforward value of duty ratios suitable for CCM and DCM modes undergoes mode discrimination and is then added to a duty ratio calculated by a current loop to obtain a final duty ratio which is used to control a switch tube, and power factor correction is realized. The power factor correction converter with the wide load range overcomes the problems that a traditional PFC converter needs to change a hardware circuit and a control algorithm when working in the light load way, average current control is combined with duty ratio feedwarding to solve the problem that prediction current control is sensitive to circuit parameters, more stable control is easy to realize, and a DCM algorithm based on average current is low in change amount and easy to realize.

The invention discloses a power factor correction circuit and a control circuit and control method of the power factor correction circuit. The PFC circuit comprises a switch circuit comprising a main switch, an analog-to-digital conversion unit, a digital-to-analog conversion unit, a comparing circuit, a calculation control unit and a pulse generating unit, wherein the analog-to-digital conversion unit generates a sampling signal according to an input voltage, an input current and an output voltage; the digital-to-analog conversion unit provides a shutdown current reference signal; the comparing circuit generates a comparing signal according to the shutdown current reference signal and the input current; the calculation control unit provides starting delay time, expected switch-on time duration and a digital shutdown current referent signal according to the sampling signal; the pulse generating unit is coupled to the comparing circuit and the calculation control unit, the switch-on time of the main switch is controlled according to the comparing signal and a switch-on delay signal, and the switch-off time of the main switch is controlled according to the expected switch-on time duration. Calculation of the circuit is convenient to perform, and the circuit is easy to obtain and higher in efficiency and power factor in light loads compared with a traditional continuous current mode control method.

The invention provides a hardware protection circuit for active PFC (power factor correction). Actuation time of a hardware protection circuit is much shorter than that of a software protection circuit, so that overcurrent or overvoltage can be more timely protected. Both the overcurrent of a power device and the overvoltage (including direct-current voltage and alternating-current voltage) of the whole circuit can be protected, trigger protection is performed on both the overvoltage and the overcurrent, an operation protection module stops transmitting PWM (pulse-width modulation) pulse signals to the power device, the power device is disconnected, and accordingly the power device is prevented from being damaged. Even an MCU (microprogrammed control unit) is slow in responding to processing speed, the PWM pulse signals can still be outputted, and the PWM pulse signals are intercepted by the operation protection module; therefore, the overcurrent or the overvoltage in the PFC circuit can be timely and effectively protected by the hardware protection circuit, and the protection is safer and more reliable.

Methods and apparatuses for providing a solution for incompatibility between nonsinusoidal waveform uninterruptible power supply (UPS) systems and active power factor correction (PFC) loads are disclosed. An embodiment of the invention includes generating a nonsinusoidal signal waveform (e.g., a voltage waveform), to be delivered to the load, with a pulse width modulation (PWM) duty width, sampling the nonsinusoidal signal waveform to collect output signal samples, and adjusting the duty width to control the nonsinusoidal signal waveform as a function of the output signal samples to deliver a desired signal characteristic (e.g., RMS signal level) to the load. In embodiments of the invention, the output duty width is adjusted differently in cases of rising and falling power consumption, respectively, by the load. Techniques disclosed herein find broad applicability in UPS systems and inverters and improve efficiency and reliability for end users and utility providers.

The invention provides a power supply device. A front feed module is arranged between a power factor correction (PFC) module and a main power switching converter. The front feed module acquires the output voltage of the PFC module, extracts power frequency ripples from the output voltage of the PFC module, generates a front feed control signal representing the power frequency ripples and feeds the front feed control signal back to the main power switching converter. The main power switching converter controls the change direction of an output gain to be reverse to the fluctuation direction ofthe front feed control signal. Therefore, the problems of power loss and electromagnetic interference caused when an auxiliary load is powered by an auxiliary power supply converter are solved, and the voltage output by the main power switching converter can directly power the auxiliary load. The circuit in the main power switching converter is a soft switching circuit, so that the electromagnetic interference can be reduced and the working efficiency of the whole machine can be improved.

The invention discloses a window control circuit for a power factor correction circuit, which comprises a sinusoidal half-wave voltage sampling circuit, a low-pass filter circuit and a comparison circuit, wherein the output end of the sinusoidal half-wave voltage sampling circuit is connected with the low-pass filter circuit; and the output end of the half-wave voltage sampling circuit and the output end of the low-pass filter circuit are connected with two input ends of the comparison circuit, and different connection ways can be adopted according to whether oscillating capacitance or oscillating resistance is used for deciding switching frequency of a PFC (power factor correction) controller. By adopting the window control circuit, the higher switching frequency is adopted in a region with smaller loss of the power factor correction circuit, that is the regions on two sides of voltage half-waves of an input power grid, the zero-crossing distortion of current of the input power grid can be prevented, and a higher power factor can be ensured; and the lower switching frequency is adopted in the main loss generation region, that is the middle region of the voltage half-waves of the input power grid, thereby reducing switching loss and improving the efficiency of the circuit.

A distributed electrical power generating and utilizing system includes an induction generator driven by a prime mover requiring reactive power to operate for providing electrical power on a bus. The bus has a gross load and is also connectable to a utility power grid by a switch. The gross load includes at least a non-linear electrical load component, typically including a variable speed device and associated diode rectifier front end. The bus includes a harmonic filter having a power factor-correcting capacitor integrated therewith for collectively compensating harmonic distortion caused by the non-linear load component and for correcting power factor to compensate for reactive power required by at least the inductive generator.

A high power battery charger includes a full bridge DC/DC converter as its main converter following a low frequency diode rectifier bridge connected to the power grid and followed by a high frequency diode rectifier bridge to charge the battery. Because the battery negates charging voltage less than that of itself, the conduction angle of the charging current dramatically drops when the battery voltage increases. The small conduction angle of the charger raises peak current and lowers power factor. An active power factor correction circuit for a high power charger consists of a boost DC/DC converter placed in conjunction with the main full bridge DC/DC converter. The present invention is a new charger topology that alters the positioning and control of the power factor correction circuit, minimizing the impact of the required additional power factor correction booster on the high power charger's overall efficiency, cost, weight and size.