Driver for driving an electromechanical device
A driver for driving an electromechanical device having a solenoid and a mechanical switch. The driver includes an input port, a ground port, first and second output ports connectable to the electromechanical device; and two power switches. A controller operates in a first mode to charge the solenoid and close the mechanical switch, a second mode to maintain the mechanical switch closed, and a third mode to discharge the solenoid and open the mechanical switch. In the first and second modes, the low-side power switch is on and the high-side power switch is controlled to switch between an on-state and an off-state by the controller. In the on-state a path is formed between the input port and ground via the high-side and low-side power switches, and the solenoid. In the off-state a path is formed between ground and ground via a ground diode, the solenoid and the low-side power switch.
1 . A driver for driving an electromechanical device comprising a solenoid and a mechanical switch; the driver comprising:
an input port connectable to a battery;
a ground port connected to ground;
a first output port and a second output port connectable to the electromechanical device; wherein the first output port is connected to ground via a ground diode;
a high-side power switch;
a low-side power switch; and
a controller coupled to the high-side power switch and the low-side power switch; the controller being operable in a first mode to charge the solenoid and close the mechanical switch, a second mode to maintain the mechanical switch closed, and a third mode to discharge the solenoid and open the mechanical switch; wherein in the first mode and the second mode, the low-side power switch is on and the high-side power switch is controlled to switch between an on-state and an off-state by the controller, such that in the on-state a path is formed between the input port and ground via the high-side power switch, the solenoid and the low-side power switch; and in the off-state a path is formed between ground and ground via the ground diode, the solenoid and the low-side power switch, and wherein during the third mode the solenoid is discharged through the low-side power switch controlled by a Zener trigger, a clamping trigger path is provided parallel to the low-side power switch, and the clamping trigger path comprises a diode, a Zener diode and a resistor.
2 . The driver as claimed in claim 1 , wherein the first mode comprises a first phase during which the low-side power switch and the high-side power switch are both on until a target current is reached through the solenoid, and a second phase during which the high-side power switch switches between the on-state and the off-state to maintain the target current through the solenoid.
3 . The driver as claimed in claim 1 , wherein the second mode comprises a first phase during which the controller operates in the off-state to drop a current through the solenoid to a second target value, and a second phase during which the high-side power switch switches between the on-state and the off-state to maintain the current through the solenoid at the second target value.
4 . The driver as claimed in claim 1 , wherein the driver is a contactor driver for driving a contactor.
5 . The driver as claimed in claim 1 further comprising a multiplexer.
6 . The driver as claimed in claim 1 further comprising a digital circuit.
7 . The driver as claimed in claim 6 , wherein the digital circuit is adapted to measure a feedback current and update the controller according to a value of the feedback current.
8 . The driver as claimed in claim 1 , wherein the high-side power switch and the low-side power switch have different voltage ratings.
9 . The driver as claimed in claim 1 , wherein the high-side power switch has a voltage rating defined by a battery voltage provided at the input port.
10 . The driver as claimed in claim 1 , wherein the low-side power switch has a voltage rating defined by a clamping voltage of the clamping trigger path.
11 . The driver as claimed in claim 1 , wherein the controller is configured to perform pulse width modulation.
12 . The driver as claimed in claim 1 , wherein the mechanical switch comprises a static contact member and a movable contact member.
13 . An electromechanical system comprising an electromechanical device coupled to the driver of claim 1 .
14 . A method for driving an electromechanical device comprising a solenoid and a mechanical switch; the method comprising:
providing a driver comprising an input port connectable to a battery; a ground port connected to ground; a first output port and a second output port connectable to the electromechanical device; wherein the first output port is connected to ground via a ground diode; the driver further comprising a high-side power switch; a low-side power switch; and a controller coupled to the high-side power switch and the low-side power switch, wherein a clamping trigger path is provided parallel to the low-side power switch, and the clamping trigger path comprises a diode, a Zener diode and a resistor;
operating the controller in a first mode to charge the solenoid and close the mechanical switch;
operating the controller in a second mode to maintain the mechanical switch closed;
wherein in the first mode and the second mode, the low-side power switch is on and the high-side power switch is controlled to switch between an on-state and an off-state by the controller, such that in the on-state a path is formed between the input port and ground via the high-side power switch, the solenoid and the low-side power switch; and in the off-state a path is formed between ground and ground via the ground diode, the solenoid and the low-side power switch; and
operating the controller in a third mode to discharge the solenoid through the low-side power switch controlled by a Zener trigger and open the mechanical switch.
15 . The method of operating the driver as claimed in claim 14 , wherein the second mode comprises a first phase during which the controller operates in the off-state to drop a current through the solenoid to a second target value, and a second phase during which the controller operates to maintain the current through the solenoid at the second target value.