Provided is a control unit of a power conversion device configured to select, in each first set cycle, a first target switching element and a second target switching element from a plurality of switching elements connected in parallel to each other. The control unit performs control so that, at a time of a turn-on operation of a switching circuit, a turn-on start time of the first target switching element is earlier by a first set time period than a turn-on start time of another switching element that is not the first target switching element. The control unit performs control so that, at a time of a turn-off operation of the switching circuit, a turn-off start time of the second target switching element is later by a second set time period than a turn-off start time of another switching element that is not the second target switching element.

A microcontroller based multifunctional electronic switch using a detection circuit design to convert external control signal into message carrying sensing signal readable to the microcontroller. Based on a time length of sensing signal and a format of the sensing signal received in a preset instant period of time the microcontroller through the operation of its software program codes is able to recognize working modes chosen by the external control signal generated by user, and thereby selecting appropriate loops of subroutine for execution. The system and method of the present invention may simultaneously be applicable to detection circuit design using infrared ray sensor, electrostatic induction sensor, conduction based touch sensor or push button sensor for performing multifunctions such as controlling on/off switch performance, diming or speed control and delay timer management within the capacity of a single lighting load or an electrical appliance.

A compact solid state relay (7) is provided. Solid state devices (74, 75), such as Triacs or Thyristors are used to implement the relay functionality. The device is at least partially enclosed in a housing that has pins for mounting on an electronics board. A number of “U” shaped jumpers (72) or other jumpers or wires are provided in the housing to act as heat sinks. A sub-miniature fan (70) is positioned to create an air flow over the heat sinks and dissipate heat from the device.

A theory and a technical foundation for building a technical framework of a color temperature tuning technology are disclosed, composing a power allocation algorithm and a power allocation circuitry, wherein the power allocation algorithm is a software for designing a process of dividing and sharing a total electric power between at least a first LED load emitting light with a first color temperature CT1 and a second LED load emitting light with a second color temperature CT2 to generate at least one paired combination of a first electric power X allocated to the first LED load and a second electric power Y allocated to the second LED load to create at least one mingled light color temperature CTapp thru a light diffuser according to color temperature tuning formulas CTapp=CT1.Math.X/(X+Y)+CT2.Math.Y/(X+Y) and X+Y=constant; and the power allocation circuitry is a hardware designed for implementing the process.

A bi-directional switch for an inductive machine is described. The bi-directional switch may include a first power semiconductor transistor with a first source, a first drain, and a first gate. The bi-directional switch may further include a second power semiconductor transistor with a second source, a second drain, and a second gate. The bi-directional switch may include the second source connected to the first source. The bi-directional switch may include a soft-starter device including a control circuit configurable to provide a first control signal to the first power semiconductor transistor and a second control signal to the second power semiconductor transistor.

A fully isolated drive circuit to be used for regulating an output voltage across a load. The isolated drive circuit may charge, discharge, or preserve the load charge using a controller that controls one or more switches. The controller may operate a switch according to an internal/external clock or an external control signal received by the controller. The isolated drive circuit may be an effective solution to simplify the drive design and decrease the amount of energy dissipated by the drive, especially when the load, associated with the drive, requires a high input voltage level.

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.

A resonant power converter controller comprising a control circuit configured to turn on a synchronous rectifier (SR) in response to a count of a number of times a drain voltage of the SR crosses below a turn on threshold based on a stored count and turns off the SR when the drain voltage crosses above a turn off threshold. The control circuit comprises a first comparator configured to generate a first detection signal in response to the drain voltage being less than the turn on threshold. A first turn on detection circuit generates a first turn on signal when the count reaches the stored count. A first turn off signal is generated in response to the drain voltage being greater than the turn off threshold. A drive circuit turns on and off the SR in response to the first turn on signal and the first turn off signal.

A color temperature switching scheme for an LED lighting device is disclosed. The color temperature switching scheme comprises a plurality of different color temperature performances correspondingly generated by a plurality of different paired combinations of a first electric power allocated to a first LED load emitting a light with a first color temperature and a second electric power allocated to a second LED load emitting a light with a second color temperature such that a mingled color temperature between the first color temperature and the second color temperature can be generated thru a light diffuser. For tuning the mingled color temperature of the LED lighting device a reverse yet complementary power adjustment process for distributing a total electric power T between the first LED circuit and the second LED circuit is required such that a total light intensity remains essentially unchanged while the mingled color temperature is being adjusted.

A relay circuit, including a solid state relay switch, connected to a first relay line and to a charging capacitor, and connected to a second relay line. The relay circuit may also include a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may include a voltage detection circuit, having an input coupled to an output of the charging capacitor, and having an output arranged to generate a LOW voltage signal when a voltage level of the charging capacitor is below a low threshold value. The solid state relay control circuit may also include a zero crossing circuit, coupled to the first relay line and the second relay line, and having an output to generate a clock signal when a zero crossing event takes place between the first relay line and the second relay line.