Electric circuit with power amplifier for piezoelectric actuators
View Patent ↗An electric circuit with one power amplifier (V 1 ) for at least two piezoelectric actuators (C 1 , C 2 ), said piezoelectric actuators (C 1 , C 2 ) being in preferably antagonist arrangement connected mechanically in series and being connected electrically with each other and operated or clocked by a control circuit, such as a pulse modulator circuit, for time-variant energizing of the piezoelectric actuators (C 1 , C 2 ) in push-pull fashion, said power amplifier (V 1 ) being connected to a junction point between the two piezoelectric actuators (C 1 , C 2 ), characterized in that said power amplifier (V 1 ) is connected to a one directional diode (D 1 ) and in that two buffer capacitors (C 3, C 4 ) and two static resistors (R 3 , R 4 ) are provided downstream the one directional diode (D 1 ) with regard to the power amplifier (V 1 ).
1. An electric circuit with one power amplifier for at least two piezoelectric actuators, the at least two piezoelectric actuators:
being in antagonist arrangement connected mechanically in series and being connected electrically with each other through a first junction point between two first terminals of the piezoelectric actuators;
being operated by the one power amplifier commanded by an input signal of a control circuit for time-variant energizing of the at least two piezoelectric actuators in push-pull fashion, the power amplifier having a first terminal which is grounded and a second terminal connected to the first junction point between such first terminals of the piezoelectric actuators;
the electrical circuit further comprising a one-directional diode whose anode is connected to the first junction point and therefore to the second terminal of the power amplifier and to the first terminals of the at least two piezoelectric actuators;
wherein:
the cathode of the diode is connected to a second junction point to which a first terminal of a first buffer capacitor and a first terminal of a first static resistor, the first buffer capacitor and the first static resistor being connected in parallel to each other, are also connected;
the second terminal of the first buffer capacitor and the second terminal of the first static resistor are connected to a third junction point to which a first terminal of a second buffer capacitor and a first terminal of a second static resistor, the second buffer capacitor and the second static resistor being connected in parallel to each other, are also connected;
the second terminal of the second buffer capacitor and the second terminal of the second static resistor are grounded;
the third junction point is also connected to a first terminal of an at least one protection resistor, whose second terminal is connected to the second terminal of a first one of the at least two piezoelectric actuators, with the second terminal of a second one of the at least two piezoelectric actuators being grounded.
2. The electric circuit according to claim 1 , wherein at least one further protection resistor is provided between the first junction point and the first terminal of the second one of the at least two piezoelectric actuators.
3. The electric circuit according to claim 1 , wherein the power amplifier is based on pulse-width modulation.
4. The electric circuit according to claim 1 , wherein the buffers capacitors are provided with a capacity greater than the capacities of the at least two piezoelectric actuators, by a factor of 10˜100 times, the capacities of the at least two piezoelectric actuators being equal.
5. The electric circuit according to claim 2 , wherein the protection resistors are provided with respective resistances less than the respective resistances of the two static resistors, by a factor of 10˜100 times.
6. An application of the electric circuit according to claim 1 to helicopters, particularly to helicopter rotors with a frequency of actuation in the order of 7 Hz(1/rev) to 35 Hz (5/rev) for four bladed or 42 Hz (6/rev) for five bladed rotors.