Drive for driving an electromechanical device

Abstract

The present disclosure relates to a driver for driving an electromechanical device having a solenoid and a mechanical switch. The driver comprises an input port, a grounding port, a first output port and a second output port, wherein the first output port and the second output port can be connected to electromechanical equipment. And two power switches. The controller operates in a first mode to charge the solenoid and close the mechanical switch, in a second mode to maintain the mechanical switch closed, and in a third mode to discharge the solenoid and open the mechanical switch. In the first mode and the second mode, the low-side power switch is on and the high-side power switch is controlled by the controller to switch between an on state and an off state. In the on state, a path is formed between the input port and ground via the high-side power switch, the low-side power switch, and the solenoid. In the OFF state, a path is formed between ground and ground via a ground diode, a solenoid, and a low-side power switch.

Description

Technical Field

[0001] The present disclosure relates to a driver for driving an electromechanical device. In particular, the present disclosure relates to a driver for driving a high voltage contactor device. Background Art

[0002] Contactor devices include two contact surfaces that are opened or closed to switch an electrical circuit on or off. They are used in high voltage and high current load applications, such as controlling large motors (e.g., motor vehicles). Typically, contactors are opened or closed using an actuator such as a solenoid that includes a plunger attached to a first surface of the contactor by a spring. The plunger is located within a coil of conductive material.

[0003] The solenoid is coupled to a drive circuit that applies a current through the coil of the solenoid, creating electromagnetic induction. The magnetic force applied to the plunger causes the contact surface to move from the open to the closed position. To open the contactor again, the coil of the solenoid needs to be de-energized to reduce the magnetic force applied to the plunger. For the safety and protection of the equipment, the de-energization process needs to happen quickly. If the de-energization is not done quickly enough, the contact surfaces will be damaged and may be joined together, resulting in a failure to shut off the high voltage creating a dangerous situation.

[0004] Traditionally, for circuits using solenoids, the coil is discharged through a freewheeling path in the circuit. This solution is favored for its simple design, however for high voltage use of contactors, the freewheeling path is disadvantageous because current will still flow through the coil of the solenoid, slowing down the de-energizing process that could bring the contactor together. An alternative solution that has been frequently used is to implement the freewheeling path with a voltage clamp circuit that will discharge the coil once a threshold voltage is reached. Such solutions can be found in the Gigavec application note entitled “Driving Contactors with external PWM” (https: / / www.sensata.com / sites / default / files / a / Sensata-gigavac-driving-contactors-with-external-pwm-app-note.pdf), the Texas Instruments technical material entitled “High-voltage contactor control” presented by David Dong (https: / / www.ti.com / lit / ml / slyp693 / slyp693.pdf?ts=1678105349002&ref_url=https%253A%252F%252Fwww.google.com%252F), and the iC-JE and iC-GE for their iC-Haus datasheets for PWM relay / solenoid drivers (https: / / www.ichaus.de / upload / pdf / JE_datasheet_G3en.pdf; https: / / www.ichaus.de / upload / pdf / GE_datasheet_B1en.pdf).

[0005] Clamping circuits are usually implemented with a low clamping voltage, making them unsuitable for high voltage contactors, and further they usually require the use of multiple power devices, which results in an increase in the area of ​​the drive circuit and an increase in production cost.

[0006] It is an object of the present disclosure to address one or more of the above limitations. Summary of the invention

[0007] According to a first aspect of the present disclosure, a driver is provided, which is used to drive an electromechanical device, the electromechanical device including a solenoid and a mechanical switch; the driver includes: 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 grounding 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 is operable in a first mode to charge the solenoid and close the mechanical switch, in a second mode to maintain the mechanical switch closed, and in 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 turned on and the high-side power switch is controlled by the controller to switch between an on state and an off state, so 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 grounding diode, the solenoid and the low-side power switch.

[0008] Optionally, the first mode includes a first phase and a second phase, during which the low-side power switch and the high-side power switch are both turned on until a target current reaches the solenoid, and during the second phase, the high-side power switch switches between an on state and an off state to maintain the target current through the solenoid.

[0009] Optionally, the second mode includes a first phase and a second phase, during which the controller operates in an off state to reduce the current through the solenoid to a second target value, and during the second phase, the high-side power switch switches between an on state and an off state to maintain the current through the solenoid at the second target value.

[0010] Optionally, during a third mode, the solenoid is discharged through a low-side power switch controlled by a Zener trigger.

[0011] For example, in the third mode, the solenoid is fully discharged to open the mechanical switch.

[0012] Optionally, a clamp trigger path is provided in parallel with the low-side power switch, the clamp trigger path comprising a diode, a Zener diode and a resistor.

[0013] Optionally, the driver is a contactor driver for driving a contactor.

[0014] Optionally, the driver further comprises a multiplexer.

[0015] Optionally, the driver further comprises a digital circuit. For example, the digital circuit or the digital core may be implemented as a state machine.

[0016] Optionally, wherein the digital circuit is adapted to measure a feedback current and update the controller according to a value of the feedback current. For example, the feedback current may be a current through a solenoid.

[0017] Optionally, the high-side power switch and the low-side power switch have different voltage ratings. For example, the high-side power switch may have a voltage rating of 45V, and the low-side power switch may have a voltage rating of 65V.

[0018] Optionally, the high-side power switch has a voltage rating defined by a battery voltage provided at the input port.

[0019] Optionally, the low-side power switch has a voltage rating defined by a clamping voltage of the clamping path.

[0020] Optionally, the controller is configured to perform pulse width modulation.

[0021] Optionally, the mechanical switch includes a fixed contact member and a movable contact member.

[0022] According to a second aspect of the present disclosure, there is provided an electromechanical system comprising an electromechanical device coupled to the driver of the first aspect.

[0023] According to a third aspect of the present disclosure, there is provided a method for driving an electromechanical device, the electromechanical device comprising a solenoid and a mechanical switch; the method comprising:

[0024] A driver is provided, 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 an electromechanical device; wherein the first output port is connected to ground via a grounding 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;

[0025] operating the controller in a first mode to charge the solenoid and close the mechanical switch;

[0026] operating the controller in the second mode to maintain the mechanical switch closed; wherein in the first mode and the second mode, the low-side power switch is conductive and the high-side power switch is controlled by the controller to switch between an on state and an off state, so 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 the ground and the ground via the grounding diode, the solenoid and the low-side power switch;

[0027] The controller is operated in a third mode to discharge the solenoid and open the mechanical switch.

[0028] Optionally, the second mode includes a first phase during which the controller operates in an off state to reduce the 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.

[0029] The options described in relation to the first aspect of the disclosure are also common to the second and third aspects of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present disclosure is described in further detail below by way of examples and with reference to the accompanying drawings, in which:

[0031] Figure 1A A driver for driving a contactor according to the prior art;

[0032] Figure 1B Yes Figure 1A The circuit shows a schematic diagram of a short circuit to ground;

[0033] Figure 2A is a schematic diagram showing the operation of the driver of FIG. 1 in the conduction phase;

[0034] Figure 2B is a schematic diagram showing the operation of the driver of FIG. 1 in the off-freewheeling stage;

[0035] Figure 2C is a schematic diagram showing the operation of the driver of FIG. 1 in a turn-off clamping stage;

[0036] Figure 3 is a schematic diagram of an alternative embodiment of the drive of FIG. 1 ;

[0037] Figure 4 is a flow chart of a method for driving an electromechanical device according to the present disclosure;

[0038] Figure 5A It is used to realize Figure 4 The method of driving;

[0039] Figure 5B is a graph showing the variation of current through a solenoid with time;

[0040] Fig. 6A is a schematic diagram showing the current path of the circuit of FIG. 5 during the conduction phase;

[0041] Figure 6B is a graph showing the current through the solenoid over time, highlighting the on state of operation;

[0042] Figure 6C is a schematic diagram showing the current path of the circuit of FIG5 in the off-freewheeling state;

[0043] Fig.6D is a diagram showing the current through the solenoid, highlighting the off-freezing state;

[0044] Fig. 6E is a schematic diagram showing the current path of the circuit of FIG. 5 in the off-clamp state;

[0045] Fig. 6F is a graph showing the current through the solenoid, highlighting the off clamped state;

[0046] Fig. 7A is a schematic diagram showing the area occupied by the power switch on the circuit chip under different configurations;

[0047] Figure 7B is a schematic diagram showing the area occupied by the power switch in the driver of FIG. 1 compared with the area occupied by the power switch of the driver of FIG. 5 ;

[0048] Fig. 8A is an exploded side view of the contactor;

[0049] Figure 8B yes Fig. 8A A side view of a contactor;

[0050] Fig. 9A is a schematic diagram showing a safety shutdown; and

[0051] Fig. 9B is a schematic diagram illustrating an unsafe shutdown. DETAILED DESCRIPTION

[0052] Figure 1A A driver for driving an electromechanical device such as a contactor according to the prior art is shown. The driver 100 is coupled to a contactor 110 including a solenoid (load) and a mechanical switch. The driver is suitable for driving the solenoid to actuate the mechanical switch. The driver 100 has an input port connected to a battery (having a voltage VBAT); a ground port (CLx) connected to ground; and two output ports marked as CHx and COx connected to the solenoid of the contactor. The first output port CHx is connected to both the battery and the solenoid.

[0053] The driver 100 includes a digital core 140 coupled to a controller 120 that controls high-side HS power switches HS1 and HS2 and a low-side power switch LS (implemented as a field effect transistor (FET)). A Zener trigger 130 is coupled between the high side and the low side of the driver. The Zener trigger turns on the driver in linear mode to provide clamping.

[0054] The driver 100 is a high voltage contactor driver that employs both a high voltage clamp and a freewheeling path. The high voltage clamp is implemented using a Zener trigger 130 including a Zener diode that will only allow current to flow through the clamp path once the voltage at the Zener diode has reached a threshold voltage. Figure 1A In existing implementations of drivers similar to the one presented in , the clamp is limited to less than 50V, but for the case of high voltage contactors (e.g., automotive contactors), clamps up to 60V are required. Figure 1A The freewheeling path for the driver 100 in this embodiment is a switchable freewheeling path on the HS of the driver.

[0055] In this topology, the driver is implemented such that HS1, HS2 and LS are controlled by a controller 120 (implemented as a pulse width modulation PWM controller). The PWM controller 120 operates via a digital core 140, which is adapted to detect feedback currents for both the LS and HS of the driver 100. The values ​​of the feedback currents on the LS and HS of the driver 100 determine the signals sent by the PWM controller 120 to the switches. This particular topology operates in three modes.

[0056] Figure 2A , Figure 2B and Figure 2C 1 is a schematic diagram showing the operation of the circuit of FIG. 1. The driver 100 operates in three phases, namely, a turn-on phase, a turn-off freewheeling phase, and a turn-off clamping phase. Panels 210a, 210b, and 210c show the current through the load over time for each phase, and panels 220a, 220b, and 220c show the current path through the driver 100 and the electromechanical device 110 in each phase.

[0057] In the first stage, if Figure 2A As shown in , a current path is formed from the battery port having voltage VBAT via the electromechanical device 110 and the LS power switch to ground GND. Initially when the driver is turned on, the LS switch is turned on and the switch HS1 and the switch HS2 are turned off. As the current through the solenoid accumulates, the digital core 140 will continue to monitor its value. Once the current exceeds a threshold, the digital core 140 will alert the controller 120 when both the HS switch and the LS switch are controlled by PWM. The point in time when PWM control takes over coincides with the end of the sharp increase in current on the current time diagram in row 210a. After this point in time, the driver 100 then switches back and forth between the first two phases: the conduction phase and the off-conduction phase. In the example shown in FIG. Figure 2BDuring the turn-off freewheeling phase shown in , the PWM control 120 turns the LS switch off and turns the HS1 switch and the HS2 switch on. In this phase, the switchable freewheeling path is on and current flows in a circular path including HS1, HS2 and the electromechanical device 100. The HS freewheeling path allows current to be maintained in the load while the LS is off. The turn-on phase and the turn-off freewheeling phase can be considered as a single phase of operation of the driver 100, which is used to close the contactor and should be referred to as turn-on from now on.

[0058] After the contactor has been closed, it needs to be opened immediately when it is turned off and the driver 100 enters the second stage of operation (such as Figure 2C At the beginning of this phase, both the HS switch and the LS switch are off and the voltage builds up at the Zener trigger 130 until it exceeds a threshold (in this example, the threshold voltage is 60V), at which point the Zener diode begins to conduct and the clamp path is opened to allow discharge to the load. This is when the driver 100 enters the third phase: the off clamp. Once the clamp path is open, the LS switch turns on and begins operating in linear mode, with the output of the circuit clamped to V above the battery. DZ , where V DZ is the threshold voltage of the Zener diode. This clamping allows the power supply to the load to be cut off and the contactor to open. The purpose of the switch HS1 and the switch HS2 in the driver 100 presented in Figures 1 and 2 is to block the freewheeling path during clamping to prevent the current from taking the path of least resistance, which would result in a slow de-energization of the load, which could damage the contactor due to welding the contactor together, which in turn could cause a safety hazard. Therefore, the driver 100 requires three power switches to operate, two of which are coupled in series with each other, which increases the area occupied on the circuit chip and therefore increases the manufacturing cost.

[0059] Figure 1A The topology presented in has the following disadvantages, in case of short connection to ground, such as Figure 1B As shown in FIG. 1 , on the low side of the driver 100 , the electromechanical device 110 will still be activated because the first output port CHx is directly connected to the battery. Therefore, the contactor will be closed when it is not wanted, which presents a safety problem.

[0060] Figure 3 Shows Figure 1AThe driver 300 is approximately identical to the driver presented in FIG1 , and as such, the same reference numerals have been maintained to indicate the same components. In this case, an additional power switch 310 is coupled between the battery port and the first output port CHx to improve the safety of the system. The power switch 310 will shut off the voltage supply from Vbat to CHx in the event of a short to ground at the low side of the driver 100.

[0061] The addition of yet another power switch in the driver 100 further increases the area occupied on the circuit chip. In addition, all power switches (HS1, HS2, LS and 310) must be able to maintain high voltages. During the shutdown (clamping) phase, voltage clamping occurs relative to the path from the battery to ground. In this way, all power switches need to be able to maintain the battery voltage VBAT plus the clamping voltage. In the example of the high voltage contactor case, the required clamping voltage is 60V and the required minimum battery voltage is 18V, so the power switch needs to have a voltage rating of at least 80V. This high voltage rating further increases the area occupied by the circuit. The addition of the power switch 310 to improve the safety of the driver increases the manufacturing cost.

[0062] The present disclosure seeks to address issues of chip real estate, manufacturing cost, and safety concerns while also providing a driver that can quickly cut power to the solenoid to prevent damage to the contactor.

[0063] Figure 4 is a flow chart of a method for driving an electromechanical device according to the present disclosure.The electromechanical device includes a solenoid coupled to a mechanical switch.

[0064] At step 410, a driver is provided. The driver includes: an input port connectable to a battery; a ground port connected to ground; a first output port and a second output port connectable to an electromechanical device. The first output port is connected to ground via a grounding diode. The driver also includes: 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.

[0065] At step 420 , the controller operates in a first mode to charge the solenoid and close the mechanical switch.

[0066] In step 430, the controller operates in the second mode to maintain the mechanical switch closed. In the first mode and the second mode, the low-side power switch is turned on and the high-side power switch is controlled by the controller to switch between the on-state and the off-state. In the on-state, via the high-side power switch, the solenoid and the low-side power switch, a path is formed between the input port and the ground. In the off-state, via the grounding diode, the solenoid and the low-side power switch, a path is formed between the ground and the ground. The off-state can be described as a turn-off freewheeling state, wherein a low impedance path is formed between the ground and the ground.

[0067] At step 440, the controller operates in a third mode to discharge the solenoid and open the mechanical switch.

[0068] Using this method, the solenoid can be demagnetized quickly, thus ensuring fast contact opening of the mechanical switch. This extends the life of the contacts.

[0069] Figure 5A Shown includes for implementing Figure 4 A method of driving an electromechanical system.

[0070] The electromechanical system 500 includes a driver 520 coupled to the electromechanical device 510, such as a contactor for driving the electromechanical device. The electromechanical device has a solenoid 512 coupled to a mechanical switch 514 and a mechanical switch 514. The driver 520 includes: a high-side power switch HS; a low-side power switch LS; and a controller 530 coupled to the high-side power switch and the low-side power switch. The driver 520 has several ports, including an input port VBATx that can be connected to a battery (not shown); a ground port CLx that is connected to ground; a first output port CHx and a second output port COx that can be connected to the electromechanical device 510. The first output port CHx is connected to ground via a ground diode D1 (which can also be integrated into the device, depending on the process technology used).

[0071] The controller 530 may include a digital core 532 coupled to a power switch driver 534 for driving the high-side power switch HS and the low-side power switch LS. The digital core 532 may be a state machine that first controls the current to a pull-in threshold and then controls the current to a low holding current level after the pull-in time expires. For example, the digital core may be configured to operate in a manner similar to Figure 1A The digital current level output of the state machine is the input to a PI controller which uses PWM to regulate the current.

[0072] The power switch can be implemented in different ways, for example, the power switch can be a field effect transistor (FET). In this implementation, a clamp trigger path 550 is provided between the second output port COx and ground, so that the clamp trigger path 550 and the low-side power switch LS are connected in parallel. Although the system 500 can be implemented by adding a diode to VBATx to recirculate the current without a clamp path, the addition of the clamp path is advantageous because it allows the solenoid to be discharged faster.

[0073] The clamp trigger path 550 includes a diode D2, a Zener diode DZ, and a resistor R1. In this example topology, clamping occurs only across the low side of the driver, meaning that the two power switches LS and HS do not need to have the same voltage rating. The high side power switch HS only needs to support the voltage from the battery VBAT, and the switch LS needs to have a voltage rating that can support the clamp voltage.

[0074] For example, the driver 520 may be implemented to operate a high voltage contactor. In this case, a relatively high clamping voltage may be required. In a numerical example, the clamping voltage is 60V and the battery voltage is 40V, resulting in voltage ratings of 45V and 65V for the HS switch and LS switch, respectively. Compared to the driver of FIG. 1 , the driver presented in FIG. 5 occupies a smaller area and is more cost-effective to manufacture due to the lower voltage ratings of the power switches and the reduction in the number of power switches required to safely operate the driver.

[0075] The power switch driver 534 may be a pulse width modulation (PWM) driver. In this example, the PWM driver 534 is operated by a digital core 532, which is adapted to detect a feedback current on the low-side power switch via a sensor 535. For example, the current sensor may be an ADC sensor. The value of the feedback current specifies the signal sent by the PWM controller 5300 to the HS switch.

[0076] Optionally, a multiplexer 540 may be provided. In this example, the multiplexer 540 has a first input coupled to the input port VBATx, a second input coupled to the HS power switch, and an output coupled to the digital core 532 via the ADC 536. The multiplexer 540 provides additional area reduction because it allows one ADC to be used to measure both the VBAT voltage and the high-side current.

[0077] The controller 530 operates in three states or modes: the first mode is a pull-in mode for charging the solenoid and closing the mechanical switch; the second mode is a hold mode for maintaining the mechanical switch closed; and the third mode is an OFF mode for quickly discharging the solenoid to open the mechanical switch.

[0078] Figure 5B is a graph showing the current through the solenoid over time during a first mode (pull-in mode), a second mode (holding mode), and a third mode (shut-off mode).

[0079] When the contactor is first activated, the first mode begins, the driver uses the driver to control the on-state (also known as the on-phase), applying the full battery voltage until the lead-in current threshold is reached. The current is then modulated by PWM to save power, alternatively, switching between the on-state and the off-freewheeling state (also known as the off-state or the off-freewheeling phase). The first mode is maintained for a period of time (known as the lead-in time) to allow the plunger to fully close and enters the second mode (holding mode) after this period.

[0080] The second mode sets the current level to a lower value to keep the contact of the mechanical switch closed while saving power. In this mode, the controller regulates the current at a second target level (referred to as the holding current level) using PWM control to switch between the on state and the off-conduction state (also referred to as the off state).

[0081] The third mode uses the shutdown clamp state to quickly cut power to the load.

[0082] FIG. 6 is a diagram illustrating the operation of the system of FIG. 5 .

[0083] Fig. 6A is a diagram showing the current path in the on-state of the first mode (the pull-in and holding mode of operation). Figure 6B A graph showing the current through the solenoid (also referred to as the contactor current) versus time is shown, highlighting the on phase of operation during the on state.

[0084] The current waveform is labeled from time t0 to time t7. The first (introduction) mode occurs between time t0 and time t4. The second (hold) mode occurs between t4 and t6. The third (turn-off) mode occurs twice in the plot from the beginning to t0, and appears again from t6 to the end of the plot.

[0085] At time t0, both the high-side power switch and the low-side power switch are turned on, and a current path is created between the input port and ground via the HS switch, the solenoid 512, and the LS switch. The current begins to increase, generating a force on the plunger. The plunger begins to move at t1, generating a back electromotive force (EMF), reducing the coil current, and making the local maximum at time t1. The current continues to decrease as the plunger moves until the current suddenly stops decreasing when the plunger reaches the end of its journey (which can be considered as a local minimum at time t2). At this point, the mechanical switch is closed and the plunger is fully introduced. Between time t2 and time t3, the current increases again because the back EMF no longer exists, and it will continue until it is limited by the path resistance or is limited by reaching the first target current value. The first target current value is a predetermined value defined by the characteristics of the contactor to ensure that the introduction is avoided while avoiding unnecessary power consumption. The digital core 532 maintains the current level by sending a signal to the power switch driver 534 to drive the HS power switch through PWM.

[0086] Figure 6C is a diagram showing a current path when operating in an off-freeze state. Fig.6D The current through the solenoid is shown, highlighting the off-freewheeling state. In the off-freewheeling state, a path is formed between ground and ground via the grounded diode, the solenoid, and the low-side power switch.

[0087] During the second mode (holding mode) of operation between time t4 and time t6, the controller switches between the on state and the off freewheeling state to maintain the mechanical switch closed. From t4 to t5, the driver is in the off freewheeling state, and the current is slowly reduced from the first target level to the second target level (also referred to as the holding current level). Once the holding current level is reached, the current is basically maintained constant at the second target value. The holding current level can be maintained using PWM. The second target value can be a predefined value, which is defined by the characteristics of the contactor.

[0088] Via solenoid 512 and low-side power switch LS, a freewheeling path occurs between the branch (D1 and GND) from the diode to ground. This path allows current to flow through the solenoid (load) but via a path with low resistance. The presence of diode D1 means that no additional current is introduced into the circuit path during this mode. PWM driver 534 switches between the on-state and the off-state HS, switching between the on-stage / state and the off (freewheeling) stage / state. The current level in the solenoid (load) is maintained, so that the solenoid is energized and the mechanical switch is closed.

[0089] The electromechanical device 510 then needs to be quickly powered down to safely open the mechanical switch.

[0090] The third mode starts at time t6. At time t6, the controller operates in the off clamp state.

[0091] Fig. 6E is a diagram showing a current path operating in a turn-off clamp state. Fig. 6F The current through the solenoid is shown, highlighting the off clamp condition.

[0092] The clamp trigger path is formed parallel to the low-side power switch. The clamp trigger path includes a diode, a Zener diode and a resistor coupled in series. When the voltage reaches the Zener clamp trigger threshold, the low-side driver is activated in linear mode. During the off clamp state, the current through the solenoid drops faster than during the off freewheeling state because the two current paths generate very different voltages across the coil.

[0093] Initially, both the HS power switch and the LS power switch are off, and voltage accumulates at the Zener diode ZD until it reaches the threshold of VDZ - requiring a 60V clamp in the example of a high voltage contactor. Once this threshold is met, the Zener diode ZD begins to conduct, accumulating voltage across the resistor R1, activating the LS transistor in linear mode, providing a clamp path to allow discharge to the load. The mechanical switch then opens at the following times: shortly after time t6, around time t7, after the current through the solenoid reaches zero.

[0094] In the third mode, the clamp is turned off and the energy in the coil is dissipated through a path formed between ground and ground via a grounded diode, a solenoid, and a low-side power switch activated by a Zener trigger in a linear mode with a high clamping voltage. The high voltage clamp quickly demagnetizes the coil, ensuring fast contact opening, extending the life of the contacts, and avoiding the drawbacks of slow demagnetization caused by using a freewheeling path or a lower clamping voltage.

[0095] The topology presented in FIG5 overcomes the disadvantages of the topology shown in FIG1. ​​In the event that the low side of the driver 520 is shorted to ground, the digital core 532 will disable both the HS power switch and the LS power switch. For the driver 520, unlike in the prior art, the only path from the electromechanical device 510 to the battery is via the HS power switch. Therefore, if the HS is off, no current can flow through the load, and thus the new topology prevents the safety hazards posed by the design presented in FIG1 without the need for an additional power switch.

[0096] The topology shown in FIG5 and the manner in which it operates (as described above) require only two power switches (HS and LS). In the topology of FIG1 , the low side has a single power switch, but the freewheeling path is on the high side of the driver, and the required two power switches connected in series must be switchable as the freewheeling path in this topology. Connecting two power switches in series increases the area occupied by a single power switch by four times, as shown in FIG1 . Fig. 7A Visible in.

[0097] Fig. 7A The area occupied by the power switches on the circuit chip for different configurations is shown. The left-hand panel 710 shows the area occupied for a single power switch with an on-resistance target of only Ron. The right-hand panel 720 shows that when two power switches are connected in series, each power switch requires twice the area to meet the on-resistance target, which is equivalent to four times the area of ​​only a single power device.

[0098] Furthermore, in the original topology of Figure 1, each power switch needs to be able to maintain both the battery voltage as well as the clamp voltage. For a clamp voltage of 60V and a minimum battery voltage of 18V, this would require each power switch to have an 80V voltage rating, which would also increase the area that the power switch would occupy on the circuit die.

[0099] Figure 7B A direct comparison is shown between the area occupied by the power switch in the original topology 810 for the circuit of FIG. 1 and the area occupied by the two power switches in the topology 820 proposed in FIG. 5 . In the driver 520 , the high-side power switch HS only needs to maintain the battery voltage, and the low-side power switch only needs to maintain the clamping voltage. Therefore, for a clamping voltage of 60V and a battery load of 40V, the high-side power switch and the low-side power switch only require ratings of 45V and 65V, respectively. The lower voltage rating for the power switches means that they can be smaller in size and therefore occupy less circuit chip area.

[0100] The proposed topology in FIG5 requires fewer power switches with lower voltage ratings, reducing the area occupied on the chip, and thus also reducing the manufacturing cost of the driver. In addition, the proposed design allows high voltage clamping and fast power-off of the electromechanical device, thus improving safety and preventing damage to the contactor. The driver 520 also has the additional safety benefit that the electromechanical device is not activated in the event of a short to ground.

[0101] Fig. 8A An exploded side view of an electromechanical device including a solenoid and a mechanical switch is shown. The mechanical switch includes a fixed contact member and a movable contact member. The solenoid has a coil within which there is a plunger coupled to a spring (see Figure 8B). A spring connects the plunger to the movable contact member.

[0102] When current flows through the coil, electromagnetic induction occurs, which exerts a force on the plunger. Once this force exceeds the force of the spring and static friction, the plunger will begin to move, bringing the movable contact member closer to the fixed contact member. Eventually, the two contact surfaces will touch and the mechanical switch will be turned on. By releasing the current through the coil, the two contact surfaces can be separated and the mechanical switch is in the open position.

[0103] Figure 8B Shown is a side view of what an electromechanical device would normally appear like when assembled. All that can be seen in this figure is the coil and contact block of the solenoid.

[0104] Fig. 9A and Fig. 9B is a schematic diagram showing the change of current over time. Fig. 9A The safety shutdown implemented by the embodiment described in the present disclosure is shown. Fig. 9B A situation of unsafe shutdown which has been implemented in the prior art is shown.

[0105] exist Fig. 9A In FIG. 1 , it can be seen that when the high voltage clamp circuit is implemented, the energy in the coil is dissipated quickly, as shown by the large and sharp drop when “coil de-energized.” This allows the contact surface of the mechanical switch to be opened as quickly as possible.

[0106] exist Fig. 9B In the case of an unsafe shutdown, only the freewheeling path is used. Current continuously flows through the coil of the solenoid, causing a slow de-energization of the coil. This can result in multiple opening and closing events of the mechanical switch, as the slow movement of the plunger through the coil can reverse the current flow, causing fluctuations in the force applied to the plunger, such as caused by Fig. 9B The oscillation of the lower line is visible.

[0107] The skilled person will appreciate that variations of the disclosed arrangements are possible without departing from the present disclosure. Therefore, the above description of specific embodiments is provided by way of example only and not for purposes of limitation. The skilled person will appreciate that minor modifications may be made without significantly changing the described operation.

Claims

1. A driver, the driver is used to drive an electromechanical device, the electromechanical device includes a solenoid and a mechanical switch; the driver comprises: Input port, which can be connected to the battery; 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 grounding diode; High-side power switch; Low-side power switch; as well as a controller coupled to the high-side power switch and the low-side power switch; The controller is operable in a first mode to charge the solenoid and close the mechanical switch, in a second mode to maintain the mechanical switch closed, and in 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 turned on and the high-side power switch is controlled by the controller to switch between an on state and an off state, so that in the on state, a path is formed between the input port and the 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 the ground and the ground via the grounding diode, the solenoid and the low-side power switch.

2. The driver of claim 1 , wherein the first mode comprises a first phase and a second phase, during which the low-side power switch and the high-side power switch are both on until a target current reaches a value through the solenoid, and during the second phase 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 of claim 1 , wherein the second mode comprises a first phase and a second phase, during which the controller operates in the off state to reduce the current through the solenoid to a second target value, and 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 of claim 1 , wherein during the third mode, the solenoid is discharged through the low-side power switch controlled by a Zener trigger. 5 . The driver of claim 4 , wherein a clamp trigger path is provided in parallel with the low-side power switch, the clamp trigger path comprising a diode, a Zener diode, and a resistor. The driver according to claim 1 , wherein the driver is a contactor driver for driving a contactor.

7. The driver of claim 1 further comprising a multiplexer.

8. The driver of claim 1 further comprising a digital circuit.

9. The driver of claim 8, wherein the digital circuit is adapted to measure a feedback current and to update the controller according to a value of the feedback current.

10. The driver of claim 1, wherein the high-side power switch and the low-side power switch have different voltage ratings.

11. The driver of claim 1 , wherein the high-side power switch has a voltage rating defined by a battery voltage provided at the input port. 12 . The driver of claim 4 , wherein the low-side power switch has a voltage rating defined by a clamping voltage of the clamping path.

13. The driver of claim 1, wherein the controller is configured to perform pulse width modulation.

14. The actuator of claim 1, wherein the mechanical switch comprises a fixed contact member and a movable contact member.

15. An electromechanical system comprising an electromechanical device coupled to the driver of claim 1.

16. A method for driving an electromechanical device, the electromechanical device comprising a solenoid and a mechanical switch; the method comprising: providing a driver including an input port connectable to a battery; Connect to the ground port for earth connection; 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 grounding 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; 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 turned on and the high-side power switch is controlled by the controller to switch between an on state and an off state, so 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, forming a path between ground and ground via the ground diode, the solenoid, and the low-side power switch; The controller is operated in a third mode to discharge the solenoid and open the mechanical switch.

17. The method of operating the driver according to claim 16, wherein the second mode includes a first phase and a second phase, during which the controller operates in the off state to reduce the current through the solenoid to a second target value, and during the second phase, the controller operates to maintain the current through the solenoid at the second target value.

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