The power supply apparatus includes a control unit configured to determine a stand-by time period from making a connection of a switch unit to subjecting a second voltage conversion unit to activation according to an input voltage of the alternating current power supply detected by a voltage detection unit.

Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

An electronic device for controlling switching timing is described. The electronic device includes load voltage measuring circuitry configured to measure a load voltage to produce a load voltage measurement. The electronic device also includes a processor coupled to the load voltage measuring circuitry. The processor is configured to determine whether a load voltage spike is indicated by the load voltage measurement. The processor is configured to control switching timing based on whether a load voltage spike is indicated.

An electronic device for controlling switching timing is described. The electronic device includes load voltage measuring circuitry configured to measure a load voltage to produce a load voltage measurement. The electronic device also includes a processor coupled to the load voltage measuring circuitry. The processor is configured to determine whether a load voltage spike is indicated by the load voltage measurement. The processor is configured to control switching timing based on whether a load voltage spike is indicated.

A programmable SCR Firing system that includes modules that work together to manipulate the SCR firing circuitry so that it mimics supply load power signatures. The programmable high speed SCR firing system includes a timing module, a delay module, a zero crossing module, a single phase delay module, a firing pulse delay module, a control interface, and an user interface.

A programmable SCR Firing system that includes modules that work together to manipulate the SCR firing circuitry so that it mimics supply load power signatures. The programmable high speed SCR firing system includes a timing module, a delay module, a zero crossing module, a single phase delay module, a firing pulse delay module, a control interface, and an user interface.

Disclosed are an electromagnetic heating device and a heating control circuit thereof, and a low power heating control method. The heating control circuit comprises: a voltage zero-crossing detection unit for detecting a voltage zero-crossing signal of an alternating current power source; a resonance heating unit; a rectification and filtering unit; a power switch tube; a drive unit, connected to a drive end of the power switch tube to drive the power switch tube to be turned on and off; a drive voltage transformation unit, connected to the drive end of the power switch tube to change a drive voltage of the power switch tube; and a main control unit for controlling the power switch tube to operate under the drive of a first drive voltage according to the voltage zero-crossing signal, thereby reducing the damage risk of the power switch tube and reducing turn-on noises.

Disclosed are an electromagnetic heating device and a heating control circuit thereof, and a low power heating control method. The heating control circuit comprises: a voltage zero-crossing detection unit for detecting a voltage zero-crossing signal of an alternating current power source; a resonance heating unit; a rectification and filtering unit; a power switch tube; a drive unit, connected to a drive end of the power switch tube to drive the power switch tube to be turned on and off; a drive voltage transformation unit, connected to the drive end of the power switch tube to change a drive voltage of the power switch tube; and a main control unit for controlling the power switch tube to operate under the drive of a first drive voltage according to the voltage zero-crossing signal, thereby reducing the damage risk of the power switch tube and reducing turn-on noises.

The present disclosure relates to a clock signal monitoring unit comprising first, second and third flip-flops, first and second XOR gates and a delay element being functionally interconnected in a specific way. The proposed clock signal monitoring unit can detect both a rising edge glitch and a falling edge glitch. In this way there is provided an area saving device, which does not require any trimming efforts, which can save a lot of space and time. Furthermore, the clock signal monitoring unit can have low electric power consumption because it uses as few as four clocked flip-flops implemented via Register Transfer Logic having an already tuned delay element. This makes it useful for designs that use both edges of the clock for correct operation.