阅读说明：本技术 用于使电容器放电的电气电路、包含该放电电路的电气系统和机动车辆 (Electrical circuit for discharging a capacitor, electrical system and motor vehicle comprising such a discharge circuit ) 是由 P.洛伊-拉方德 于 2018-02-23 设计创作，主要内容包括：一种放电电路(106),包括：两个接口端子(BA,BB),电容器(C)连接至所述端子,并且在所述端子之间提供电容器电压(uc)；电气电流消耗电路(108),其连接在两个接口端子(BA,BB)之间并被设计为消耗电容器(C)的放电电流(i)；以及电气控制电路(110),用于控制电气电流消耗电路(108),电气控制电路(110)连接在两个接口端子(BA,BB)之间,以接收电容器电压(uc)。电气控制电路(110)被设计为：当电容器电压(uc)高于预定义阈值时,使电气电流消耗电路(108)去激活,并且当两个接口端子(BA,BB)之间的电容器电压(uc)低于预定义阈值时,激活电气电流消耗电路(108)。电气控制电路(110)还被设计为仅经由两个接口端子(BA,BB)接收电力供应。(A discharge circuit (106), comprising: two interface terminals (BA, BB) to which a capacitor (C) is connected and between which a capacitor voltage (uc) is provided; an electrical current consumption circuit (108) connected between the two interface terminals (BA, BB) and designed to consume a discharge current (i) of the capacitor (C); and an electrical control circuit (110) for controlling the electrical current consuming circuit (108), the electrical control circuit (110) being connected between the two interface terminals (BA, BB) to receive the capacitor voltage (uc). The electrical control circuit (110) is designed to: the electrical current consuming circuit (108) is deactivated when the capacitor voltage (uc) is above a predefined threshold value, and the electrical current consuming circuit (108) is activated when the capacitor voltage (uc) between the two interface terminals (BA, BB) is below the predefined threshold value. The electrical control circuit (110) is further designed to receive a supply of electrical power via only two interface terminals (BA, BB).)

1. A discharge circuit (106) for discharging a capacitor (C), comprising:

two interface terminals (B)_A，B_B) A capacitor (C) is intended to be connected to the terminals and to provide a capacitor voltage (u) between the terminals_C)，

-a current consuming electrical circuit (108) connected at the two interface terminals (B)_A，B_B) And is designed to consume a discharge current (i) from said capacitor (C), an

-an electrical control circuit (110) for controlling the current consuming electrical circuit (108), the electrical control circuit (110) being connected at the two interface terminals (B)_A，B_B) To receive said capacitor voltage (u)_C)，

Characterized in that the electrical control circuit (110) is designed to:

-when the capacitor voltage (u)_C) Above a predefined threshold, deactivating the current consuming electrical circuit (108), and

-when said two interface terminals (B) are connected_A，B_B) Said capacitor voltage (u) in between_C) Below the predefined threshold, activating the current consuming electrical circuit (108),

and the electric control circuit (110) is designed to be exclusively via the two interface terminals (B)_A，B_B) Is supplied with electric power.

2. Discharge circuit (106) according to claim 1, wherein the current consuming electrical circuit (108) comprises a first transistor (Q1), the first transistor (Q1) having a current input terminal (C1), a current output terminal (E1) and a control terminal (B1), the discharge current (i) being intended to flow through the first transistor (Q1) by entering via the current input terminal (C1) and exiting via the current output terminal (E1), and wherein the electrical control circuit (110) is connected to the control terminal (B1) of the transistor (Q1) and is designed to deactivate the current consuming electrical circuit (108) by opening the transistor (Q1) and to activate the current consuming electrical circuit (108) by closing the transistor (Q1).

3. The discharge circuit (106) of claim 2, wherein the current output terminal (E1) is connected to the control terminal (B1) to stabilize the first transistor (Q1).

4. The discharge circuit (106) of claim 3, wherein the current consuming electrical circuit (108) comprises a zener diode (D1) connected between the current output terminal (E1) and the control terminal (B1) to stabilize the first transistor (Q1).

5. The discharge circuit (106) of any of claims 2 to 4, wherein the electrical control circuit (110) comprises:

-a second transistor (Q2) having a current input terminal (C2), a current output terminal (E2) and a control terminal (B2), the current input terminal (C2) of the second transistor (Q2) being connected to the control terminal (B1) of the first transistor (Q1), and

-at least one zener diode (D3, D2) connected between the control terminal (B2) and the two interface terminals (B2) of the second transistor (Q2)_A，B_B) One of (B)_A) In the meantime.

6. The discharge circuit (106) of any one of the preceding claims, the circuit being a passive circuit.

7. An electrical system (100) comprising:

-a capacitor (C),

-a discharge circuit (106) for discharging a capacitor (C) according to any of claims 1 to 6,

-a power supply device (102) having two power supply terminals (B)_C，B_D) And is designed to be supplied via the two power supply terminals (B)_C，B_D) The supply of electric power is carried out by supplying,

-a power receiving device (104) connected to the two interface terminals (B)_A，B_B) And is designed to receive the power supplied by the power supply device (102).

8. The electrical system (100) according to claim 7, wherein the power supply device (102) is designed to apply a DC supply voltage (E).

9. The electrical system (100) according to claim 8, wherein the DC supply voltage (E) is higher than 60V, preferably higher than 300V.

10. The electrical system (100) according to claim 8 or 9, wherein the interface terminal (B)_A，B_B) First of (B)_A) Intended to have a larger number of interface terminals than the interface terminals (B)_A，B_B) Another one of (B)_B) A higher potential, and wherein the one or more zener diodes (D3, D2) are connected between the control terminal (B2) and the first interface terminal (B2) of the second transistor (Q2)_A) In the meantime.

11. The electrical system (100) according to any one of claims 7 to 10, wherein the power supply device (102) comprises one of: a battery charger and a battery.

12. The electrical system (100) according to any one of claims 7-11, wherein the power receiving device (104) comprises one of: a battery and an inverter.

13. A motor vehicle (300) comprising an electrical system (100) according to any one of claims 7 to 12.

Technical Field

The present invention relates to a discharge circuit (electrical discharge circuit) for discharging a capacitor, and particularly to the field of electric vehicles.

Background

It is known to connect a resistor to the terminals of a capacitor supplied by a high voltage source. Thus, in the event that the high voltage source is disconnected, the capacitor discharges into the resistor to prevent an electric shock that may occur when the operator touches the capacitor. A disadvantage of this solution is that the passive discharge element continues to consume current even when not needed, i.e. when a high voltage source is connected.

US patent publication US 6204612B1 describes a discharge circuit for discharging a capacitor of the type comprising:

two interface terminals to which a capacitor is intended to be connected and between which a capacitor voltage is intended to be provided,

a current-consuming electrical circuit connected between the two interface terminals and designed to consume a discharge current from the capacitor, an

An electrical control circuit for controlling the current consuming electrical circuit, the electrical control circuit being connected between the two interface terminals to receive the capacitor voltage.

In this publication, the current consuming electrical circuit is designed to be activated by the electrical control circuit in order to consume a substantially constant discharge current when the capacitor is disconnected from the power supply module. More specifically, the power supply module comprises a conductor arranged to short-circuit a controlled switch of the electrical control circuit to deactivate the current consuming circuit. Thus, when the power supply module is disconnected, the conductor is disconnected from the electrically controlled switch, so that the current consuming electrical circuit is activated. This solution has the disadvantage of requiring the presence of mechanical elements (conductors) on the high voltage source side.

It is an object of the present invention to propose a discharge circuit which at least partially overcomes the above-mentioned disadvantages.

Disclosure of Invention

To this end, a discharge circuit for discharging a capacitor of the above-mentioned type is proposed, said circuit being characterized in that the electrical control circuit is designed to:

-deactivating the current consuming electrical circuit when the capacitor voltage is above a predefined threshold, and

-activating a current consuming electrical circuit when the capacitor voltage between the two interface terminals is below a predefined threshold,

also, the electric control circuit is designed to be supplied with electric power exclusively via the two interface terminals.

By means of the invention, the current-consuming electrical circuit is activated when the capacitor voltage drops below a threshold value, so that it is no longer necessary to provide external mechanical elements to activate the discharge of the capacitor. Furthermore, since the electrical control circuit is supplied with power exclusively via the interface terminal, it is supplied with power by the capacitor when the capacitor is no longer connected to the power supply device. Therefore, the reliability of the discharge circuit is improved.

Optionally, the current consuming electrical circuit comprises a first transistor having a current input terminal, a current output terminal and a control terminal, the discharge current being intended to flow through the first transistor by entering via the current input terminal and exiting via the current output terminal, and the electrical control circuit is connected to the control terminal of the transistor and is designed to deactivate the current consuming electrical circuit by opening the transistor and to activate the current consuming electrical circuit by closing the transistor.

Also optionally, the current output terminal is connected to the control terminal to stabilize the first transistor.

Also optionally, the current consuming electrical circuit comprises a zener diode connected between the current output terminal and the control terminal to stabilize the first transistor.

Also optionally, the electrical control circuit comprises: a second transistor having a current input terminal, a current output terminal, and a control terminal, the current input terminal of the second transistor being connected to the control terminal of the first transistor; and at least one zener diode connected between the control terminal of the second transistor and one of the two interface terminals.

There is also provided an electrical system, the system comprising: a capacitor (C); a discharge circuit for discharging a capacitor according to the present invention; a power supply device having two power supply terminals and designed to supply power via the two power supply terminals; a power receiving device connected to the two interface terminals and designed to receive power supplied by the power supply device.

Optionally, the power supply device is designed to apply a DC supply voltage.

Also optionally, the DC supply voltage (E) is higher than 60V, preferably higher than 300V.

Also optionally, a first one of the interface terminals is intended to have a higher potential than another one of the interface terminals, and one or more zener diodes are connected between the control terminal of the second transistor and the first interface terminal.

Also optionally, the power supply device comprises one of: a battery charger and a battery.

Also optionally, the power receiving device includes one of: a battery and an inverter.

Throughout the foregoing text, the discharge circuit for discharging the capacitor may be a passive circuit. The discharge circuit may be supplied with power exclusively via the two interface terminals, in particular through the capacitor to be discharged, when the power supply device is not operating. Furthermore, the discharge circuit may be free of any computational components, that is to say of any components designed to run a computer program, such as a microcontroller or microprocessor.

A motor vehicle comprising an electrical system according to the invention is also proposed.

Drawings

Fig. 1 is a circuit diagram of an electrical system including a discharge circuit for discharging a capacitor according to the present invention.

Fig. 2 is a timing diagram showing changes over time in capacitor voltage and current into the discharge circuit.

Fig. 3 is a diagram illustrating a motor vehicle including at least one discharge circuit as shown in fig. 1.

Detailed Description

An electrical system 100 embodying the present invention will now be described with reference to fig. 1.

The electrical system 100 first comprises a circuit having two power supply terminals B_C、B_DThe power supply device 102. The power supply device 102 is designed to supply power to the two power supply terminals B_C、B_DBetween which a supply voltage E is applied via two supply terminals B_C、B_DSupplying power. For example, the supply voltage E is substantially constant. Further, in the described example, terminal B_DIs connected to the electrical ground of the electrical system 100 and is intended to make the terminal B_CRelative to the terminal B_DAt a positive potential of + E V.

The electrical system 100 further includes a power receiving device 104, and the power receiving device 104 is connected to the power supply terminal B_C、B_DAnd is designed to receive power supplied by the power supply apparatus 102.

The electrical system 100 further comprises a capacitor C connected to the power supply terminal B_C、B_DAnd is for example designed to smooth the supply voltage E. The capacitor C has a capacitor voltage u between its terminals equal to the supply voltage E of the power supply device 102 when in operation_C。

The electrical system 100 also comprises a discharge circuit 106 for discharging the capacitor C, which is specifically intended to discharge the capacitor C when the power supply device 102 is not operating (for example, when it is disconnected).

The discharge circuit 106 firstly comprises two interface terminals B connected to the terminals of the capacitor C_A、B_BTo receive the capacitor voltage u_C。

The discharge circuit 106 further includes a terminal B connected to the interface terminal_A、B_BConsuming electrical circuitry 108.

In the depicted example, the current consuming electrical circuit 108 includes a transistor Q1, the transistor Q1 having a current input terminal C1, a current output terminal E1, and a control terminal B1. In the depicted example, the transistor Q1 is a bipolar transistor having a collector, an emitter, and a base corresponding to the current input terminal C1, the current output terminal E1, and the control terminal B1, respectively. The open or closed state of the transistor Q1 is defined by a control voltage V1 present between the control terminal B1 and the current output terminal E1.

In the depicted example, the current consuming electrical circuit 108 further includes a current input terminal C1 and an interface terminal B connected thereto_AResistor R1 in between.

In the depicted example, the current consuming electrical circuit 108 further includes a current output terminal E1 connected to the interface terminal B_BResistor R2 in between.

In the depicted example, the current consuming electrical circuit 108 further includes two resistors R3, R4 connected in series with each other between the control terminal B1 and the current input terminal C1.

In the depicted example, the current consuming electrical circuit 108 further includes a zener diode D1 connected between the control terminal B1 and the interface terminal B to stabilize the transistor Q1.

The discharge circuit 106 also includes an electrical control circuit 110 for controlling the current consuming electrical circuit 108. The electric control circuit 110 is connected to two interface terminals B_A、B_BIn the meantime.

In the depicted example, the electrical control circuit 110 includes a transistor Q2, the transistor Q2 having a current input terminal C2, a current output terminal E2, and a control terminal B2. In the depicted example, the transistor Q2 is a bipolar transistor having a collector, an emitter, and a base corresponding to the current input terminal C2, the current output terminal E2, and the control terminal B2, respectively. The open or closed state of the transistor Q2 is defined by a control voltage V2 between the control terminal B2 and the current output terminal E2.

In the depicted example, the current output terminal E2 is connected to the interface terminal B_B。

In the depicted example, the electrical control circuit 110 also includes a resistor R5 connected between the control terminal B2 and the current output terminal E2. The connection between the control terminal B2 and the current output terminal E2 via the resistor R5 also makes it possible to stabilize the transistor Q2.

In the depicted example, the electrical control circuit 110 further includes a resistor R6 and at least one zener diode D3, D2 connected in series with each other between the control terminal B2 and the control terminal C1. The zener diodes D3, D2 have a combined breakdown voltage equal to the sum of the individual breakdown voltages of the zener diodes D3, D2.

In the depicted example, the electrical control circuit 110 also includes a resistor R1. Thus, the electrical control circuit 110 receives the capacitor voltage u_CThe capacitor voltage u_CSpecifically between the terminals of the resistor R1, the zener diodes D3, D2 and the resistors R5 and R6.

Also, at least one of the resistors R1, R2, R3, R4, R5, and R6 is preferably a resistor having a resistance that changes little with temperature, for example, 100 ppm at most 1 ohm per degree celsius between 0 ℃ and 150 ℃.

The operation of the electrical system 100 will now be described with reference to fig. 2.

Initially, the power supply device 102 is operational and at its power supply terminal B_C、B_DA supply voltage E is applied in between, the value of which in the example described is 500V. Usually, the supply voltage E is a "high voltage", which means that in the automotive field it has a value of more than 60V, preferably more than 300V.

Thus, the capacitor C is charged with the supply voltage E, so that the capacitor voltage u_CEqual to the supply voltage E.

The capacitor voltage u_CIs received by the electrical control circuit 110 so that the voltage between the terminals of the resistor R1, the zener diodes D3, D2 and the resistors R5, R6 is equal to the supply voltage E.

Now, the combined breakdown voltage of the zener diodes D3, D2 is selected to be lower than the supply voltage E, so that the zener diodes D3, D2 allow a first leakage current to flow, which leakage current flows throughFlow through resistors R1, R6, and R5 from terminal B_AFlows to terminal B_B。

Due to leakage current i_fFlows through the resistor R5, and thus the control voltage V2 is non-zero, so that the transistor Q2 remains in a closed (conducting) state.

Therefore, the transistor Q2 shorts the resistor R3 and the zener diode D1 so that the control voltage V1 is substantially zero.

Therefore, the transistor Q1 is kept in an off (cut-off) state, so that the current-consuming electrical circuit 108 is deactivated and the discharge current i is substantially zero.

Also, since the transistor Q2 is closed (on), the second leakage current i_f' flows from interface terminal a to interface terminal B through resistor R4.

Thus, via the interface terminal B_AIncoming current i_CEqual to leakage current i_f、i_f' of the total.

At time t₀Here, the power supply device 102 is transitioned to the non-operating state, for example, by being disconnected from the rest of the electrical system 100.

Therefore, the capacitor C is discharged into both the resistors R1, R5, and R6 and the zener diodes D3, D2 and the resistor R4, so that the capacitor voltage u_CAnd decreases.

Since the transistor Q2 is stable, the leakage current i_f' is substantially constant (in practice slightly reduced), which enables the capacitor C to discharge rather rapidly.

At time t₁At a voltage u_CBecomes equal to the combined breakdown voltage of the zener diodes D3, D2, which thus transition to the off-state.

Therefore, the leakage current i flowing through the resistor R5_fBecomes zero so that the control voltage V2 becomes zero, and the transistor Q2 transitions to an off (cut-off) state.

Thus, the control terminal B1 receives the leakage current i via the resistors R1, R4, and R3_f', and the control voltage V1 becomes non-zero. Accordingly, the transistor Q1 transitions to a closed (conductive) state, causing the current consuming electrical circuit 108 to be activatedLive and non-zero discharge current i is passed from terminal B via transistor Q1_AFlow direction terminal B_B. The discharge current i is much larger than the leakage current i_f', such that via the interface terminal B_AIncoming current i_CSubstantially equal to the discharge current i.

Moreover, since transistor Q1 is stable, the discharge current i flowing through it is at time t₀And time t₁Is substantially constant (in practice slightly reduced) at a level significantly higher than the leakage current i_fAt the level of' this enables the capacitor C to discharge very rapidly. Preferably, the components are chosen such that the capacitor C is at less than 60s (time t in fig. 2)₂) Is discharged to less than 60V.

According to the foregoing, the discharge circuit 106 is a passive circuit, and thus each of the current consuming electrical circuit 108 and the electrical control circuit 110 is a passive circuit, which means that both: designed exclusively via two interface terminals B when the power supply device 102 is not operating_A、B_BSupplied power, specifically supplied through capacitor C; and it does not comprise any computing components, that is to say any components designed to run a computer program, such as a microcontroller or microprocessor.

An electric vehicle 300 will now be described with reference to fig. 3.

The electric vehicle 300 includes a charger 302, the charger 302 being designed to be connected to a power grid and to supply a DC voltage.

The electric vehicle 300 also includes a high-voltage battery 304 designed to be charged by a charger 302.

The electric vehicle 300 further includes a capacitor C1 interposed between the charger 302 and the high-voltage battery 304.

The electric vehicle 300 further includes an inverter 306, and the inverter 306 is designed to supply an AC voltage based on the DC voltage from the high-voltage battery 304.

The electric vehicle 300 further includes a capacitor C2 interposed between the high-voltage battery 304 and the inverter 306.

The electric vehicle 300 further includes an electric motor 308, and the electric motor 308 is designed to be supplied with electric power by the inverter 306 and to drive wheels of the electric vehicle 300.

The electric vehicle 300 further includes a DC-to-DC converter 310, the DC-to-DC converter 310 being designed to supply a low voltage based on a high voltage supplied by the high-voltage battery 304.

The electric vehicle 300 further includes a capacitor C3 interposed between the high voltage battery 304 and the DC-to-DC converter 310.

The electric vehicle 300 also includes a low-voltage battery 312 designed to be charged by the DC-to-DC converter 310. The low-voltage battery 312 is used, for example, to supply electric power to accessories of the electric vehicle 300.

The discharge circuit 106 described with reference to fig. 2 may be used for each of the capacitors C1, C2, C3. Thus, depending on the capacitors involved, the power supply device 102 therefore comprises one of the following: a charger 302 and a high voltage battery 304, and the power receiving device includes one of: a high voltage battery 304, an inverter 306, and a DC to DC converter 310.

The invention is not limited to the above-described embodiments but is defined by the appended claims. Indeed, it will be apparent to those skilled in the art that modifications may be made.

For example, one or the other of resistors R1 and R2 may be omitted.

Furthermore, the terms used in the claims should not be construed as being limited to the elements in the above-described embodiments, but should be construed to cover all equivalent elements that can be inferred from the common general knowledge of those skilled in the art.

Specifically, the term "electric vehicle" also covers the case of a hybrid vehicle that includes both an electric motor and an internal combustion engine for driving wheels.