Regulating Controller for Controlled Self-Oscillating Converters Using Bipolar Junction Transistors

A controller for a power converter, the power converter having a BJT as a switch, the base of the BJT being connected to a drive winding, said drive winding being magnetically coupled to a load winding which carries the power converter load current, the controller comprising:

• first and second control winding connections for connection to a control winding magnetically coupled to the load and drive windings;
• a first switch coupled between the first and second control winding connections;
• a current monitoring element for monitoring the current in the load winding;
• and
• a switch controller for selectively closing said first switch to provide a short circuit across the first and second control winding connections, further adapted to open the switch when the current monitoring element determines that the current in the load winding has fallen below a first threshold.

A controller for a power converter, the power converter having a BJT as a switch, the base of the BJT being connected to a drive winding, said drive winding being magnetically coupled to a load winding which carries the power converter load current, the controller comprising:

• first and second control winding connections for connection to a control winding magnetically coupled to the load and drive windings;
• first and second energy store connections for connection to an energy store;
• a first switch coupled between the first control winding connection and said first energy store connection;
• a second switch coupled between the second control winding connection and the second energy store connection;
• a voltage monitor coupled to the first and second control winding connections and arranged to determine when the voltage across the first and second control winding connections exceeds a threshold;
• and
• a switch controller arranged to selectively close the first and second switch;
• wherein
• the switch controller is arranged to close the first and second switch when the voltage monitor determines that the voltage across the first and second control winding connections exceeds said threshold.

A controller for a power converter, the power converter having a BJT as a switch, the base of the BJT being connected to a drive winding, said drive winding being magnetically coupled to a load winding which carries the power converter load current, the controller comprising:

• first and second control winding connections for connection to a control winding magnetically coupled to the load and drive windings;
• a first switch coupled between the first control winding connection and second control winding connection;
• first and second current sensing resistor connections for connection to a current sensing resistor in series with the load winding;
• a monitor coupled to the first and second current sensing resistor connections for monitoring the voltage across the current sensing resistor, adapted to determine when the current in the load winding falls beneath a threshold;
• further comprising
• a switch controller adapted to enter a low power mode when the monitor determines that the current in the load winding has fallen beneath the threshold, wherein
• when in said low power mode, the switch controller closes the first switch to apply a short circuit between the first and second control winding connections for suppressing power conversion in the power converter.