Method and system for diagnosing the status of a contactor

Abstract

Method and system for diagnosing the state of a contactor. The system for diagnosing the state of a contactor of an electric vehicle comprises: a contactor (1, 2); a device (3) for detecting a current passing through the device (3), the device (3) being positioned in parallel with the contactor (1, 2); and a controller (14) operably connected to the contactor (1, 2) and the device (3) for detecting a current passing through the device (3). The controller (14) is configured to: communicate with the contactor (1, 2) and record a theoretical state of the contactor (1, 2); receive a signal from the device (3): if current passes through the device (3), the received signal is open, and if current does not pass through the device (3), the received signal is closed; compare the theoretical state of the contactor with the state of the contactor received from the device (3) for detecting a current passing through the device (3).

Description

Technical Field

[0001] The present invention relates to systems and methods for diagnosing the state of contactors in electric vehicles. More specifically, the present invention relates to a battery circuit for an electric vehicle (EV) or a hybrid electric vehicle (HEV) that includes circuit components for determining the state of contactors operating in a voltage range above the diagnostic range. Background Art

[0002] In high voltage systems, power contactors are usually used to ensure current isolation between power devices. For example, in a Cut Off Box known in the prior art, there are two main contactors that isolate the battery from the charger or the load.

[0003] During the drive cycle, the contactor closes to electrically couple the battery to other areas of the powertrain. When the drive cycle is complete, the contactor opens to, for example, protect the battery from relatively high voltages, or to isolate the battery from the rest of the circuit in the event of an isolation resistor failure. If the contactor welds closed, the contactor will not open and the circuit can remain closed.

[0004] The controller is configured to open and close the contactors of the contactor assembly. The contactors are normally closed during the driving cycle. Closing the contactors permits power to circulate to and from the battery. At the end of the driving cycle, when the powertrain is not running, the contactors are opened.

[0005] A disadvantage of the aforementioned system is that the contactor may have a different state than that required by the controller. Summary of the invention

[0006] The object of the present invention is a contactor diagnostic system for an electric vehicle, the system comprising:

[0007] - a contactor, which is movable between a closed state and an open state,

[0008] - means for detecting the current passing through the device, the means being positioned in parallel with the contactor and being operatively connected to a power source, and

[0009] a controller operatively connected to the contactor and to the means for detecting a current through the device, the controller being configured to:

[0010] ○Communicate with the contactor and record the theoretical open state or theoretical closed state of the contactor in the controller,

[0011] o Receiving a signal from a device for detecting current passing through the device:

[0012] ■If current flows through the device, the signal received is that the contactor is disconnected, and

[0013] ■If the current does not flow through the device, the signal received is that the contactor is closed.

[0014] o Compare the theoretical state of the contactor with the state of the contactor received from the device for detecting the current through the device.

[0015] Yet another object of the present invention is a method for detecting the contactor status of an electric vehicle, the method comprising the following steps:

[0016] - enables the controller to communicate with the contactor and records the theoretical open state or theoretical closed state of the contactor in the controller,

[0017] - receiving in the controller a signal from a device for detecting a current through the device:

[0018] ■If current flows through the device, the signal received is that the contactor is disconnected, and

[0019] ■If current is not flowing through the device, the signal received is that the contactor is closed.

[0020] A theoretical state of the contactor is compared in the control device with a state of the contactor received from the device for detecting the current through the device.

[0021] In the present application it is understood that by communicating between a controller and a contactor is a process by which signals comprising information and / or actions can be exchanged between the controller and the contactor, at least from the controller to the contactor, and preferably in both directions, either directly between the two elements, or indirectly via at least a second controller or an intermediate module between the controller and the contactor.

[0022] Therefore, the communication referred to includes the following actions: the controller sends a signal to the contactor to change its state to an open state or a closed state. In addition, the controller records the state as the theoretical state of the contactor.

[0023] Likewise, the communication also includes the alternative of receiving a signal with the state of the contactor in the control unit and recording the state in the control unit as a target state.

[0024] As mentioned above, in different embodiments, the controller can be a single element or multiple elements that receive different signals, thereby ultimately causing the controller of the diagnostic system to perform the above-mentioned comparison. Therefore, the expression communication also includes an alternative mode in which the controller of the diagnostic system indirectly communicates with the contactor in the following manner: the controller receives a signal with the state of the contactor from another controller, which in turn sends a first signal to the contactor to change its state to an open state or a closed state, and sends a second signal with the state of the contactor to the controller of the diagnostic system.

[0025] Thus, the contactors may be configured to be commanded by the controller of the diagnostic system or by another controller.

[0026] In one embodiment, the system includes a power source operably connected to the contactor and means for detecting current flow through the device.

[0027] In one embodiment, the power source is a battery of the electric vehicle and / or a charger of the vehicle, an on-board charger OBC.

[0028] One of the advantages of the system and method of the present invention is that detection is based on current rather than voltage measurement.

[0029] In one embodiment, the means for knowing whether current is passing is an octocoupler. An octocoupler system is often used to avoid interference between circuits of different voltage ranges. Since the detection is current-based and uses an octocoupler, this embodiment avoids interference with other circuits and also reduces the cost of the system.

[0030] In particular, if the contactors are open and the optocouplers are enabled, current should flow through them. When current flows through them, the signal received by the controller from the device, or in the above embodiment from the optocouplers, will be "1", so the contactors are in the open state.

[0031] If the contactor is closed, current will not flow through the optocoupler due to the low impedance of the contactor path and therefore the signal received by the controller from the device or in the above embodiment from the optocoupler will be "0", thus, the contactor is in the closed state.

[0032] According to the above embodiment, the controller is configured to manage the system to diagnose the contactor status by communicating with the following elements:

[0033] Contactors, and

[0034] - An optocoupler or another device for detecting the current passing through it.

[0035] Once the controller has made the above comparison, it can be configured to:

[0036] - signal the status of the contactor, or

[0037] - If there is a difference between the theoretical state of the contactor and the state received from the device, a signal is sent according to the difference, for example, a safety element is operated by opening other switches to isolate the battery or sending a signal to the system to control charging or sending a signal to the driver, etc.

[0038] In addition to diagnosing the status of the contactors, the same system can be used to check whether the relay has been closed correctly during the pre-charging process. The system is able to know the status of any contactor when the relationship between the circuit and the diagnostic voltage is different. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to complete the description and to provide a better understanding of the present invention, the accompanying drawings are provided. The accompanying drawings form an integral part of the specification and illustrate preferred embodiments of the present invention. The accompanying drawings include the following figures.

[0040] Figure 1 An embodiment of the diagnostic system of the present invention is shown.

[0041] Figure 2 Another embodiment of the diagnostic system of the present invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 and Figure 2 An embodiment of the system object of the present invention is disclosed, the system comprising:

[0043] - power supply, in particular the system of embodiments can be fed by a battery (4), or by an on-board charger (15) or by an additional power supply (5) operatively connected to the contactors (1, 2) and to the device for detecting the current passing through the device (3). This additional power supply (5) can be controlled by a controller (14),

[0044] - Two contactors (1, 2) operatively connected to a power source. Figure 1 In the embodiment shown, the first contactor (1) is associated with the positive terminal of the battery (4). The second contactor (2) is associated with the negative terminal of the battery (4). The controller (14) commands the first contactor (1) and the second contactor (2) to an open state and a closed state.

[0045] - means (3) for detecting the current passing through said means, which are positioned in parallel with the contactors (1, 2). In the embodiment shown, said means are two optocouplers. In the disclosed embodiment, each optocoupler comprises two reverse diodes, LS1 and LS2 associated with the negative terminal and HS1 and HS2 associated with the positive terminal (3). The two reverse diodes avoid the problem of unequal currents from the two sides of the system, allowing the optocoupler to work with currents from both sides.

[0046] - a controller (14) operatively connected to a possible additional power source (5), the contactors (1, 2) and the optocoupler (3), and configured to:

[0047] ○ In case the additional power source (5) needs to be operated, the additional power source (5) is changed to an on state,

[0048] ○Change the state of contactors (1, 2) through controller (14),

[0049] ○The theoretical state of the contactors (1, 2) is recorded in the controller (14),

[0050] o Connecting the diagnostic circuit (i.e. the device for detecting the current through the device) in parallel with the contactors (1, 2) by, for example, closing the switches (12, 13). In the embodiment shown, the switches (12, 13) are optomosfets,

[0051] ○ Receive signal from optocoupler (3):

[0052] ■If current flows through the optocoupler (3), the contactors (1, 2) are disconnected, and

[0053] ■If the current does not flow through the optocoupler (3), the contactors (1, 2) are closed.

[0054] o comparing the actual state of the contactors (1, 2) as reflected by the device for detecting the current passing through the device with a theoretical state, the actual state being the state to which the contactors (1, 2) have been changed,

[0055] o emitting a signal of the state of the contactors (1, 2) provided by the optocoupler (3) and / or emitting a signal when there is a difference between a theoretical state and an actual state,

[0056] o Isolating the diagnostic circuit from the contactors (1, 2) by, for example, disconnecting switches (12, 13),

[0057] o If the additional power state (5) has previously been set to on, change it to off.

[0058] According to the above, the controller (14) is configured to manage the system to diagnose the contactor (1, 2) status by controlling the following items:

[0059] Contactor (1, 2),

[0060] switches (12, 13) of two diagnostic circuits (i.e. two optocouplers (3)),

[0061] receiving data from the optocoupler (3) and finally comparing this data with the theoretical state of the contactors (1, 2),

[0062] · Signaling the contactor (1, 2) state and / or signaling the difference between a theoretical state and an actual state.

[0063] In particular, if the contactors (1, 2) are opened and the optocoupler (3) is enabled, current should flow through them until the capacitor (6) is fully charged.

[0064] The switches (12, 13) of the two diagnostic circuits have the added advantage of providing isolation to the contactor (1, 2) poles, and after the diagnostics have been performed, the switches (12, 13) isolate the diagnostic circuits.

[0065] The circuit system can operate using a voltage from a battery (4) or from a power source from a charger (15), and since an additional power source (5) is operably connected to the contactors (1, 2), the system is able to detect the state of the contactors (1, 2) in the absence or presence of a battery (4) and / or a charger (15).

[0066] Therefore, the test can be performed under the following conditions:

[0067] The battery (4) is connected but the charger (15) is not connected.

[0068] The charger (15) is connected but the battery (4) is not connected.

[0069] • Both the battery (4) and the charger (15) are not connected.

[0070] In the embodiment shown, the system comprises a low voltage injection as an additional power source (5), in particular a 20V flyback injection, in order to perform diagnostics in the event of no or insufficient voltage in the system.

[0071] One of the advantages of the system shown in the embodiment is that it works independently of the voltage of the battery (4) and the charger (15) since the system has its own voltage injection. Since the battery (4) and the charger (15) have their own contactors, there are situations where the system has no external voltage at the poles of the contactors (1, 2), so an internal additional power supply (5) is needed to perform the detection.

[0072] In the embodiment shown in the figures, the first contactor (1) is associated with the positive terminal of the additional power source (5) and the second contactor (2) is associated with the negative terminal of the additional power source (5).

[0073] In addition, the embodiment shown in the figure includes the following elements:

[0074] - a resistor (Rw(7)) which limits the current through the diode of the optocoupler (3).

[0075] - A capacitor (Cw(6)) which limits the power dissipation on Rw(7) and avoids a constant power dissipation in the event of a failure of the optocoupler (3).

[0076] - Resistor (RdschgC (8)): required to discharge the Cw capacitor (6).

[0077] - Resistor (Rlimit (9)): It limits the current of the flyback DC-DC converter. In addition, although the battery (4) is in operation, the additional power supply (5) is used, but since the additional power supply (5) provides only 20V, a tension difference needs to exist until the voltage of the battery (4) is reached.

[0078] -Diode (DBlocking (10)): It blocks the battery or OBC voltage.

[0079] -Diode (Dz(11)): Provides a stable voltage under no-load conditions.

Claims

1. A system for diagnosing the state of a contactor of an electric vehicle, characterized in that The system comprises: - a contactor (1, 2) which is movable between a closed state and an open state, - means (3) for detecting current, said means (3) comprising an optical coupler for knowing whether there is current passing through said means (3), said means (3) being connected in parallel with the path of said contactors (1, 2), wherein the path of said contactors (1, 2) has a lower impedance than the path of said means (3), - a controller (14) operatively connected to the contactors (1, 2) and the device (3) for detecting current, the controller (14) being configured to: o communicating with the contactors (1, 2) by changing the state of the contactors (1, 2) and recording the state in the controller (14) as a theoretical state or by receiving a signal with the state of the contactors (1, 2) and recording the state in the controller (14) as a theoretical state, and recording the theoretical open state or theoretical closed state of the contactors (1, 2) in the controller (14), o Receiving a signal from said means for detecting current (3): If current flows through the optocoupler, the signal received is that the contactor (1, 2) is opened, and If no current flows through the optocoupler, the signal received is that the contactor (1, 2) is closed, o comparing the theoretical state of the contactors (1, 2) with the state of the contactors (1, 2) received from the device (3) for detecting the current, - a resistor (7) configured to limit the current through the optocoupler, and - a capacitor (6) configured so that, if the contactors (1, 2) are opened and the optocoupler is enabled, a current flows through the optocoupler until the capacitor (6) is fully charged, the capacitor (6) being configured to limit the power dissipation on the resistor (7) and to avoid a constant power dissipation in the event of a failure of the optocoupler.

2. The system for diagnosing the state of a contactor of an electric vehicle according to claim 1, wherein: The system comprises a power source operatively connected to the contactors (1, 2) and the device (3) for detecting current.

3. The system for diagnosing the state of a contactor of an electric vehicle according to claim 2, wherein: The power source is a battery (4) of the electric vehicle and / or a charger (15) of the vehicle.

4. The system for diagnosing the state of a contactor of an electric vehicle according to claim 3, wherein: The system comprises an additional power source (5) operatively connected to the contactors (1, 2) and to the device (3) for detecting the current.

5. The system for diagnosing the state of a contactor of an electric vehicle according to claim 4, wherein: The controller (14) is configured to control the additional power source (5) to switch it on / off.

6. The system for diagnosing the state of a contactor of an electric vehicle according to claim 4, wherein: The system comprises: - a first contactor and a second contactor, the two contactors being operatively connected to the power source, the first contactor being associated with the positive terminal of the battery (4), the second contactor being associated with the negative terminal of the battery (4), the controller (14) being configured to command the first contactor and the second contactor to an open state and a closed state, - said device (3) for detecting the current passing through said device (3), said device (3) being positioned in parallel with each of said two contactors.

7. The system for diagnosing the state of a contactor of an electric vehicle according to claim 6, wherein: The first contactor is associated with the positive terminal of the additional power source (5), and the second contactor is associated with the negative terminal of the additional power source (5).

8. The system for diagnosing the state of a contactor of an electric vehicle according to any one of claims 1 to 5, wherein: The system also includes a diode (10) configured to block a battery or an on-board charger (OBC) voltage.

9. The system for diagnosing the state of a contactor of an electric vehicle according to claim 8, wherein: The system further comprises: - a resistor configured to limit the current from the additional power source (5), - a resistor configured to discharge the capacitor (6), - A diode configured to provide a regulated voltage in no-load conditions.

10. The system for diagnosing the state of a contactor of an electric vehicle according to any one of claims 1 to 5, wherein: The controller (14) is configured to emit a signal when there is a difference between the theoretical state and the state provided by the means (3) for detecting the current.

11. The system for diagnosing the state of a contactor of an electric vehicle according to any one of claims 1 to 5, wherein: The controller (14) is configured to send a signal to activate the device (3) for detecting electric current.

12. The system for diagnosing the state of a contactor of an electric vehicle according to any one of claims 1 to 5, wherein: The device (3) for detecting current comprises switches (12, 13).

13. A method for diagnosing the state of a contactor of an electric vehicle, the method comprising the steps of: - by changing the state of the contactors (1, 2) and recording the state in the controller (14) as a theoretical state or by receiving a signal with the state of the contactors (1, 2) and recording the state in the controller (14) The state is recorded as a theoretical state in the controller (14), so that the controller (14) communicates with the contactors (1, 2), and the theoretical open state or theoretical closed state of the contactors (1, 2) is recorded in the controller (14), - receiving a signal in the controller (14) from a device (3) for detecting a current passing through based on the current, the device (3) comprising an optocoupler for knowing whether a current passes through the device, the device being connected in parallel with the path of the contactors (1, 2), and wherein the path of the contactors (1, 2) has a lower impedance than the path of the device (3): If current flows through the optocoupler, the signal received is that the contactor (1, 2) is opened, and If no current flows through the optocoupler, the signal received is that the contactor (1, 2) is closed, - in the controller (14), comparing the theoretical state of the contactors (1, 2) with the state of the contactors (1, 2) received from the device (3) for detecting the current, - providing a resistor (7) configured to limit the current through the optocoupler, and - a capacitor (6) is provided, said capacitor (6) making it possible for a current to flow through said optocoupler if said contactors (1, 2) are opened and said optocoupler is enabled until said capacitor (6) is fully charged, said capacitor (6) limiting the power dissipation on said resistor (7) and avoiding a constant power dissipation in the event of a failure of said optocoupler.

14. The method for diagnosing the state of a contactor of an electric vehicle according to claim 13, wherein: The method comprises the additional step of changing the state of an additional power source (5) to an on state to provide voltage to the contactors (1, 2).

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