Systems and methods for controlling soft-switching current source converters

A resonant module for use with a soft-switching current source converter, the resonant module comprising:

• a resonant switch;
• a resonant inductor connected in electrical series with the resonant switch;
• a resonant capacitor connected in parallel with the serially connected resonant switch and resonant inductor;
• a control logic circuitry configured to control the resonant switch;
• a first sensing circuit configured to generate a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• and
• a second sensing circuit configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• wherein the control logic circuitry is further configured to turn on the resonant switch when the second sensing signal indicates that the voltage across the resonant capacitor is less than or equal to the predetermined threshold value to initiate a resonance between the resonant inductor and the resonant capacitor.

A resonant module for use with a soft-switching current source converter, the resonant module comprising:

• a resonant switch;
• a resonant inductor connected in electrical series with the resonant switch;
• a resonant capacitor connected in parallel with the serially connected resonant switch and resonant inductor;
• a control logic circuitry configured to control the resonant switch;
• a first sensing circuit configured to generate a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• and
• a second sensing circuit configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• wherein at least one of:
• at least one of the control logic circuitry or a controller of the soft-switching current source converter is configured to increase the predetermined threshold value if the first sensing signal indicates the time derivative of the voltage across the resonant capacitor is negative during a zero voltage switching transition state after a resonance phase of a switching cycle of the soft-switching current source converter for a period of time greater than a predetermined time period;
• or
• at least one of the control logic circuitry or a controller of the soft-switching current source converter is configured to decrease the predetermined threshold value if the first sensing signal indicates the time derivative of the voltage across the resonant capacitor is negative during a zero voltage switching transition state after a resonance phase of a switching cycle of the soft-switching current source converter for a period of time less than a predetermined time period.

A resonant module comprising:

• a resonant switch;
• a resonant inductor connected in electrical series with the resonant switch;
• a resonant capacitor connected in parallel with the serially connected resonant switch and the resonant inductor;
• a first sensing circuit configured to generate a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• and
• a second sensing circuit configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• wherein:
• the first sensing circuit is connected in parallel with the resonant capacitor;
• the first sensing circuit comprises a sensing resistor connected in series with an optocoupler;
• the serially connected sensing resistor and optocoupler are connected in anti-parallel with a Zener diode.

A resonant module for use with a soft-switching current source converter, the resonant module comprising:

• a resonant switch;
• a resonant inductor connected in electrical series with the resonant switch;
• a resonant capacitor connected in parallel with the serially connected resonant switch and the resonant inductor;
• a first sensing circuit configured to generate a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• and
• a second sensing circuit configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• wherein the second sensing circuit is connected in parallel with the resonant capacitor;
• and
• wherein the second sensing circuit comprises a Zener diode providing a voltage reference, an optocoupler sensing circuit, a series sensing resistor, a series diode, and a capacitive voltage divider.

A resonant module for use with a soft-switching current source converter, the resonant module comprising:

• a resonant switch;
• a resonant inductor connected in electrical series with the resonant switch;
• a resonant capacitor connected in parallel with the serially connected resonant switch and the resonant inductor;
• a first sensing circuit configured to generate a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• and
• a second sensing circuit configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• wherein the second sensing circuit is connected in parallel with the resonant capacitor;
• and
• wherein the second sensing circuit comprises a series connection of at least two Zener diodes in opposite orientation, a series sensing resistor, series optocoupler sensing circuit, a capacitive voltage divider, and a resistive voltage divider.

A method of controlling a resonant tank of a soft-switching current source converter, the resonant tank comprising a resonant switch, a resonant inductor connected in electrical series with the resonant switch, and a resonant capacitor connected in parallel with the serially connected resonant switch and the resonant inductor, the method comprising:

• generating a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• generating a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• and
• altering the predetermined threshold value comprising one or both:
• increasing the predetermined threshold value if the first sensing signal indicates the time derivative of the voltage across the resonant capacitor is negative during a zero voltage switching transition state after a resonance phase of a switching cycle of the soft-switching current source converter for a period of time greater than a predetermined time period;
• and/or
• decreasing the predetermined threshold value if the first sensing signal indicates the time derivative of the voltage across the resonant capacitor is negative during a zero voltage switching transition state after a resonance phase of a switching cycle of the soft-switching current source converter for a period of time less than a predetermined time period.

A method of controlling a resonant tank of a soft-switching current source converter, the resonant tank comprising a resonant switch, a resonant inductor connected in electrical series with the resonant switch, and a resonant capacitor connected in parallel with the serially connected resonant switch and the resonant inductor, the method comprising:

• generating a first sensing signal indicative of when a time derivative of a voltage across the resonant capacitor is negative;
• generating a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value;
• and
• turning on the resonant switch to initiate a resonance between the resonant inductor and the resonant capacitor when the second sensing signal indicates that the voltage across the resonant capacitor is less than or equal to the predetermined threshold value.