A compensating method for a ripple compensation circuit of a power supply is provided. The power supply includes an LLC resonant converter. The LLC resonant converter receives an input voltage and generates an output voltage. Firstly, the output voltage is subtracted from a reference voltage, so that a first error signal is generated. Then, a digital filter is provided to increase a low frequency gain of the first error signal, so that a second error signal is generated. Then, the first error signal and the second signal are added, so that a modulated error signal is generated. Then, a compensation signal is generated to control the LLC resonant converter according to the modulated error signal. Consequently, a low frequency gain of the input voltage is increased and a low frequency ripple of the output voltage is suppressed by an increased voltage loop compensator response.

In one embodiment, a power factor correction (PFC) circuit can include: (i) a rectifier bridge and a PFC converter coupled to an input capacitor; (ii) a harmonic wave compensation circuit configured to shift a phase of a DC input voltage provided from the rectifier bridge, where the harmonic wave compensation circuit comprises a phase of about −45° when a corner frequency is about 50 Hz; and (iii) a PFC control circuit configured to control the PFC converter, where the PFC control circuit comprises a first sampling voltage, and the harmonic wave compensation circuit is configured to control a phase of the first sampling voltage to lag a phase of the DC input voltage by about 45°.

In one embodiment, a power factor correction (PFC) circuit can include: (i) a rectifier bridge and a PFC converter coupled to an input capacitor; (ii) a harmonic wave compensation circuit configured to shift a phase of a DC input voltage provided from the rectifier bridge, where the harmonic wave compensation circuit comprises a phase of about −45° when a corner frequency is about 50 Hz; and (iii) a PFC control circuit configured to control the PFC converter, where the PFC control circuit comprises a first sampling voltage, and the harmonic wave compensation circuit is configured to control a phase of the first sampling voltage to lag a phase of the DC input voltage by about 45°.

A power supply comprises a controller configured to control a power converter by generating drive signals that control the opening and closing of a high side switch and a low side switch. The controller is configured to selectively control the high side switch according to various modes of operation depending on operating conditions such as input voltage and load power consumption. The modes of operation can include, for example, a mode in which the high side switch is closed and then opened once during each of the series of switching cycles and a mode of operation in which the high side switch is closed and then opened two times during each of the series of switching cycles.

An apparatus for converting power includes at least one impedance matching network which receives an electrical signal. The apparatus includes at least one AC to DC converter in communication with the impedance matching network. Also disclosed is a method for powering a load and an apparatus for converting power and additional embodiments of an apparatus for converting power.

An apparatus for converting power includes at least one impedance matching network which receives an electrical signal. The apparatus includes at least one AC to DC converter in communication with the impedance matching network. Also disclosed is a method for powering a load and an apparatus for converting power and additional embodiments of an apparatus for converting power.

An ac-dc power supply includes a dc-dc converter coupled to an input of the ac-dc power supply. The input of the ac-dc power supply is coupled to receive an ac input voltage and an ac input current. The dc-dc converter includes a regulated output and a reservoir output. A controller is coupled to receive sense signals from the dc-dc converter. The controller is coupled to control the dc-dc converter to regulate the regulated output in response to the sense signals. The controller is further coupled to control a waveform of the ac input current to have a substantially same shape as a waveform of the ac input voltage. A regulator circuit is coupled to the regulated output and the reservoir output. The controller is coupled to the regulator circuit to control a transfer of energy from the reservoir output to the regulated output through the regulator circuit.

An integrated circuit configured to switch a transistor in a power supply circuit. The integrated circuit includes a first terminal to which a first resistor is coupled; a first detection circuit configured to detect whether a load of the power supply circuit is in an overload state; a second detection circuit configured to detect whether a current flowing through the transistor is overcurrent; an oscillator circuit configured to output an oscillator signal with a cycle corresponding to a first resistance value of the first resistor; and a driving signal output circuit configured to output a driving signal to turn on the transistor, based on the oscillator signal, and turn off the transistor, based on a feedback voltage corresponding to the output voltage. The driving signal output circuit further outputs the driving signal to turn off the transistor, in response to the current flowing through the transistor reaching overcurrent.

A power harvesting system employs a saturable core transformer having two primary windings and at least one secondary winding. One of the primary windings is a high impedance winding, and the other primary winding is a low impedance winding. The two primary windings are connected with the load (motor). The secondary winding provides power to the circuit components of a replacement electronic thermostat. Relay contacts connects A/C power to either the high impedance primary winding or to the low impedance primary winding. When the relay is de-energized, A/C power is applied to the high impedance winding so that a relatively small amount of current flows through both the high impedance winding. This current is low enough that it does not energize the motor but is sufficient to generate the required voltage to transfer power to the secondary winding and is used to power the electronic thermostat. When the relay is energized, A/C power is applied directly to the low impedance primary winding, energizing the motor. At the beginning of each A/C cycle, the current through the low impedance winding builds up rapidly until the core saturates. The result is that a short pulse is generated in the secondary on both the positive and negative A/C cycle. This pulse has an amplitude determined by the turns ratio of the low impedance winding to the secondary winding and is used to power the electronic thermostat. After the core saturates, the impedance of the low impedance winding is only the resistance of the wire of the winding which is very small and results in negligible impact on the motor operation and also results in very low power dissipation.

A power harvesting system employs a saturable core transformer having two primary windings and at least one secondary winding. One of the primary windings is a high impedance winding, and the other primary winding is a low impedance winding. The two primary windings are connected with the load (motor). The secondary winding provides power to the circuit components of a replacement electronic thermostat. Relay contacts connects A/C power to either the high impedance primary winding or to the low impedance primary winding. When the relay is de-energized, A/C power is applied to the high impedance winding so that a relatively small amount of current flows through both the high impedance winding. This current is low enough that it does not energize the motor but is sufficient to generate the required voltage to transfer power to the secondary winding and is used to power the electronic thermostat. When the relay is energized, A/C power is applied directly to the low impedance primary winding, energizing the motor. At the beginning of each A/C cycle, the current through the low impedance winding builds up rapidly until the core saturates. The result is that a short pulse is generated in the secondary on both the positive and negative A/C cycle. This pulse has an amplitude determined by the turns ratio of the low impedance winding to the secondary winding and is used to power the electronic thermostat. After the core saturates, the impedance of the low impedance winding is only the resistance of the wire of the winding which is very small and results in negligible impact on the motor operation and also results in very low power dissipation.