A zero-crossing detector to be installed in a ceiling fan includes: a first terminal; a second terminal; and a rectifier, an adjustor and a feedback generator that cooperatively generate a current signal based on an AC voltage between the first and second terminals. The current signal has a non-zero magnitude when the AC voltage causes a potential at the first terminal to be greater than a potential at the second terminal, and has a zero magnitude when otherwise. An average of the non-zero magnitude of the current signal is greater when the adjustor is in a working state than when the adjustor is in a power saving state. The feedback generator generates a feedback signal based on the current signal.

During a first mode of operation, a zero current detect (ZCD) signal is asserted in response to detecting a zero current condition at a switch node of a power converter. The power converter enters a light load mode of operation when the ZCD signal is asserted between a beginning point and a trigger point of a period of a PWM signal. A compensator voltage is generated based on a feedback voltage indicative of an output voltage. The compensator voltage is compared to a threshold voltage that represents a limit for the compensator voltage during the light load mode of operation determined over a range of the output voltage. The power converter exits the light load mode back to the first mode of operation in response to the compensator voltage being beyond the threshold voltage.

During a first mode of operation, a zero current detect (ZCD) signal is asserted in response to detecting a zero current condition at a switch node of a power converter. The power converter enters a light load mode of operation when the ZCD signal is asserted between a beginning point and a trigger point of a period of a PWM signal. A compensator voltage is generated based on a feedback voltage indicative of an output voltage. The compensator voltage is compared to a threshold voltage that represents a limit for the compensator voltage during the light load mode of operation determined over a range of the output voltage. The power converter exits the light load mode back to the first mode of operation in response to the compensator voltage being beyond the threshold voltage.

An arithmetic device and a motor drive device including the arithmetic device capable of performing high accuracy motor current calculation, include a control unit performing an arithmetic processing including: acquire a duty ratio; calculate a waiting time according to the duty ratio and a waiting coefficient; detect a shunt current value at a detection timing after lapse of the waiting time; acquire, as a zero-cross current value, the shunt current value; calculate an average value using the shunt current values; and calculate an effective current value by correcting the average value using a correction coefficient.

An arithmetic device and a motor drive device including the arithmetic device capable of performing high accuracy motor current calculation, include a control unit performing an arithmetic processing including: acquire a duty ratio; calculate a waiting time according to the duty ratio and a waiting coefficient; detect a shunt current value at a detection timing after lapse of the waiting time; acquire, as a zero-cross current value, the shunt current value; calculate an average value using the shunt current values; and calculate an effective current value by correcting the average value using a correction coefficient.

A circuit breaker comprises a solid-state bidirectional switch, a switch control circuit, current and voltage sensors, and a processor. The solid-state bidirectional switch is connected between a line input terminal and a load output terminal of the circuit breaker, and configured to be placed in a switched-on state and a switched-off state. The switch control circuit control operation of the bidirectional switch. The current sensor is configured to sense a magnitude of current flowing in an electrical path between the line input and load output terminals and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage on the electrical path and generate a voltage sense signal. The processor is configured to process the current and voltage sense signals to determine operational status information of the circuit breaker, a fault event, and power usage information of a load connected to the load output terminal.

A circuit breaker comprises a solid-state bidirectional switch, a switch control circuit, current and voltage sensors, and a processor. The solid-state bidirectional switch is connected between a line input terminal and a load output terminal of the circuit breaker, and configured to be placed in a switched-on state and a switched-off state. The switch control circuit control operation of the bidirectional switch. The current sensor is configured to sense a magnitude of current flowing in an electrical path between the line input and load output terminals and generate a current sense signal. The voltage sensor is configured to sense a magnitude of voltage on the electrical path and generate a voltage sense signal. The processor is configured to process the current and voltage sense signals to determine operational status information of the circuit breaker, a fault event, and power usage information of a load connected to the load output terminal.

Systems for power factor correction are provided. Aspects include a voltage source connected to a first node, wherein the voltage source is configured to provide a first voltage, a sense resistor connected between the first node and a second node, a load connected to the second node, a power factor correction capacitor connected in parallel with the load, and a controlled voltage source configured to provide a second voltage to the power factor correction capacitor based on a control signal, wherein the control signal is received from a power factor correction circuit configured to determine a time difference between a zero-crossing of a voltage signal and a zero-crossing of a current signal from the voltage source.

A zero-crossing detector to be installed in a ceiling fan includes: a first terminal; a second terminal; and a rectifier, an adjustor and a feedback generator that cooperatively generate a current signal based on an AC voltage between the first and second terminals. The current signal has a non-zero magnitude when the AC voltage causes a potential at the first terminal to be greater than a potential at the second terminal, and has a zero magnitude when otherwise. An average of the non-zero magnitude of the current signal is greater when the adjustor is in a working state than when the adjustor is in a power saving state. The feedback generator generates a feedback signal based on the current signal.

A zero-crossing detector to be installed in a ceiling fan includes: a first terminal; a second terminal; and a rectifier, an adjustor and a feedback generator that cooperatively generate a current signal based on an AC voltage between the first and second terminals. The current signal has a non-zero magnitude when the AC voltage causes a potential at the first terminal to be greater than a potential at the second terminal, and has a zero magnitude when otherwise. An average of the non-zero magnitude of the current signal is greater when the adjustor is in a working state than when the adjustor is in a power saving state. The feedback generator generates a feedback signal based on the current signal.