Electronic switching circuit

Apparatus for providing a current through a load, the apparatus comprising:

• a) means for generating a series of main pulses, the width of each pulse in the series being derived from the instantaneous magnitude of an analog signal,
• b) four main electronic switches, each connected to be controlled by the main pulses, each of the switches being connected between the load and a power supply,
• c) four recovery paths, each recovery path comprising an auxiliary electronic switch and a diode connected in series, each recovery path defining two ends, one end being connected to the load and the other end being connected to the power supply, wherein the recovery paths are not in parallel with any of the main electronic switches, wherein the recovery paths comprise paths for current to flow from the load to the power supply, and
• d) means for actuating the switches in the recovery paths, the actuating means including at least two distinct trains of auxiliary pulses, the auxiliary pulses being derived from the main pulses, wherein the main pulses have leading and trailing edges, and wherein each auxiliary pulse straddles a leading or a trailing edge of one of said main pulses, wherein the distinct trains of auxiliary pulses are applied to distinct switches in the recovery paths, the auxiliary pulses being different from the main pulses.

Apparatus for providing current through an N-phase load, where N is a positive integer, the apparatus comprising:

• a) means for generating a series of main pulses, the width of each pulse in the series being related to the instantaneous magnitude of an analog signal,
• b) a pair of main electronic switches associated with each phase of the load, each pair of main electronic switches connected to be controlled by the main pulses, each of the switches being connected between the load and a power supply,
• c) a pair of recovery paths associated with each phase of the load, each recovery path comprising an auxiliary electronic switch and a diode connected in series, each recovery path defining two ends, one end being connected to the load and the other end being connected to the power supply, wherein the recovery paths are not in parallel with any of the main electronic switches, and
• d) means for actuating the switches in the recovery paths, the actuating means including two distinct trains of auxiliary pulses, the auxiliary pulses being different from the main pulses, the auxiliary pulses being related to the main pulses, wherein the main pulses have leading and trailing edges, and wherein each auxiliary pulse straddles a leading or a trailing edge of one of said main pulses, and wherein the distinct trains of auxiliary pulses are applied to the respective switches in the recovery paths so as to actuate those switches.

Apparatus for providing a current through a load, the apparatus comprising:

• a) means for generating a series of main pulses, the width of each pulse in the series being derived from the instantaneous magnitude of an analog signal,
• b) two main electronic switches, each connected to be controlled by the main pulses, each of the switches being connected between the load and a power supply,
• c) two recovery paths, each recovery path comprising an auxiliary electronic switch and a diode connected in series, each recovery path defining two ends, one end being connected to the load and the other end being connected to the power supply, wherein the recovery path is not in parallel with any of the main electronic switches, and
• d) means for actuating the switches in the recovery paths, the actuating means including at least two distinct trains of auxiliary pulses, the auxiliary pulses being different from the main pulses, the auxiliary pulses being derived from the main pulses, and means for applying the distinct trains of auxiliary pulses to the respective switches in the recovery paths.