Method for operating a circuit arrangement for charging and discharging a capacitive actuator
A method for operating a circuit for charging and discharging a capacitive actuator. The circuit has a series circuit of first and second power transistors with respective parallel-connected diodes connected between the potentials of a supply voltage source. The node between the power transistors is connected via a coil to the capacitive actuator. For charging the actuator, the first power transistor, which connects the capacitive actuator to the positive potential, is periodically turned on during a prescribed time and turned off when a first prescribed threshold value is reached by the current through the actuator, until a lower threshold value is reached by the current. If the actuator current no longer reaches the first prescribed threshold value then the first power transistor is turned off after a time that corresponds to the maximum value reached by the actuator current.
1. A method of operating a circuit arrangement for charging and discharging at least one capacitive actuator,
the circuit arrangement having:
a series circuit including first and second power transistors each with a respective parallel-connected diode and connected by way of a connecting node, said series circuit being connected between potentials of a supply voltage source;
a coil connecting said connecting node between said first and second power transistors to said at least one capacitive actuator;
the method comprising:
charging the capacitive actuator by periodically turning on the first power transistor that connects the capacitive actuator to a positive potential of the supply voltage source during a prescribable period of time and turning off the first power transistor when a first prescribed threshold value is reached by an actuator current through the capacitive actuator, until a second prescribed threshold value, which is lower than the first threshold value, is reached by the actuator current;
if, during a subsequent charging pulse, with the first power transistor turned on for charging the capacitive actuator, the actuator current no longer reaches the first prescribed threshold value, turning off the first power transistor after a period that corresponds to a maximum value reached by the actuator current for that charging pulse and that follows an instant at which the maximum value is reached for that charging pulse.
2. A method of operating a circuit arrangement for charging and discharging at least one capacitive actuator,
the circuit arrangement having:
a series circuit including first and second power transistors each with a respective parallel-connected diode and connected by way of a connecting node, said series circuit being connected between potentials of a supply voltage source;
a coil connecting said connecting node between said first and second power transistors to the at least one capacitive actuator;
the method comprising:
charging the capacitive actuator by periodically turning on the first power transistor that connects the capacitive actuator to a positive potential of the supply voltage source during a prescribable period of time and turning off the first power transistor when a first prescribed threshold value is reached by an actuator current through the capacitive actuator, until a second prescribed threshold value, which is lower than the first threshold value, is reached by the actuator current; and
if, during a subsequent charging pulse, with the first power transistor turned on for charging the capacitive actuator, the actuator current no longer reaches the first prescribed threshold value, turning off the first power transistor after a prescribed period that follows an instant at which a maximum value is reached for that charging pulse.
3. A method of operating a circuit arrangement for charging and discharging at least one capacitive actuator,
the circuit arrangement having:
a series circuit including first and second power transistors each with a respective parallel-connected diode and connected by way of a connecting node, said series circuit being connected between potentials of a supply voltage source;
a coil connecting said connecting node between said first and second power transistors to the at least one capacitive actuator;
the method comprising:
charging the capacitive actuator by periodically turning on the first power transistor that connects the capacitive actuator to a positive potential of the supply voltage source during a prescribable period of time and turning off the first power transistor when a first prescribed threshold value is reached by an actuator current through the capacitive actuator, until a second prescribed threshold value, which is lower than the first threshold value, is reached by the actuator current; and
if, during a subsequent charging pulse, with the first power transistor turned on for charging the capacitive actuator, the actuator current no longer reaches the first prescribed threshold value, turning off the first power transistor after a period of time that is dependent on a maximum value reached by the actuator current for that charging pulse, a period for reaching the maximum value for that charging pulse, and the prescribed threshold value and that follows an instant at which the maximum value is reached for that charging pulse.