Electrical Industrial Equipment with Remote Accessories

Abstract

It limits the heating that would be induced if a remote accessory were to be completely shorted, providing excellent energy efficiency. [Solution] An electrical industrial equipment (1) comprising a main device (3) and a remote accessory (5) of the main device (3), the main device (3) comprising a fluid circuit (7) configured to control at least one element and a central control unit (17) powered by a power grid, the remote accessory (5) being powered by the main device (3) via a power cable (19) connected to an auxiliary power port (17a) of the central control unit (17) of the main device (3), the central control unit (17) comprising a current regulator for limiting current in the event of a short circuit in the remote accessory (5), the current regulator comprising a switching circuit whose switching duty cycle is controlled as a function of the peak input current of the switching circuit.

Description

[Technical Field]

[0001] The present invention relates to electrical industrial equipment having a main unit with a fluid circuit for pumping gas and an electrical remote accessory powered by the main unit. [Background technology]

[0002] Industrial equipment typically includes remote accessories, such as command interfaces, control screens, test probes, and sensors, that control and interact with the master device. These accessories are powered by a connecting cable that connects to the master device. This power is provided by a low-voltage DC power supply, for example, 5V to 48V. This type of power supply eliminates the need to charge the remote accessory's battery, thereby reducing the size and weight of the remote accessory.

[0003] However, if a short circuit occurs in the remote accessory, it may damage the electrical circuitry of the main device, resulting in equipment failure, stopping production lines, manufacturing processes, and processing, and causing significant economic losses. Therefore, the risk of damage associated with a complete short circuit in the remote accessory should be limited. Summary of the Invention [Problem to be solved by the invention]

[0004] For this purpose, it is known to use a current limiting circuit based on a linear regulator, which has the advantage of being simple, therefore cheap, and autonomous (no need to reset after a short circuit occurs).

[0005] However, with such linear current limiting circuits, the voltage delivered to the remote accessory before the current limiting mode is activated can be affected by the internal resistance of the limiter, and this voltage drop can be several volts. Furthermore, in the event of a complete short circuit of the remote accessory, the inductive heating of the linear current limiting circuit can be relatively large, necessitating a solution that can effectively dissipate the generated heat, such as soldering a large copper pad to the electronic board around the linear regulator components. Also, significant energy losses due to the linear mode of operation may be observed.

[0006] It is also known to use a foldback regulator which shuts off the power supply when a current above a predetermined threshold is detected. This type of regulator is simple and inexpensive, yet limits heat generation. However, this type of regulator must be manually reset after the short circuit disappears. Furthermore, this circuit does not tolerate transient currents (accidental tripping) that occur when connected remote accessories are powered on. Solving these problems increases the complexity and cost of the circuit.

[0007] It is therefore one of the objects of the present invention to provide a solution that limits the heating induced in the event of a complete short circuit of a remote accessory, provides excellent energy efficiency, and does not require manual resetting. [Means for solving the problem]

[0008] To this end, the invention provides an electrical industrial device comprising a main unit and at least one remote accessory of said main unit, the main device includes a fluid circuit for delivering gas to an inlet of the main device and a central control unit; the central control unit is configured to control at least one element of the fluid circuit, is configured to be powered by an electrical grid, and further includes an auxiliary power port; the remote accessory is powered by the central control unit of the main device via a power cable connected to the auxiliary power port of the central control unit of the main device; The central control unit includes a current regulator for limiting current in the event of a short circuit in the remote accessory, the current regulator including a switching circuit whose switching duty cycle is controlled as a function of the peak input current of the switching circuit.

[0009] According to another aspect of the invention, the main device is a vacuum pump or a leak detector in which the fluid circuit comprises a pumping device. According to another aspect of the invention, the remote accessory is any one of the elements in the following list: Human-Machine Interface Command Screen Control Screen Control box Sensors and other measuring devices a test probe with a conduit fluidly connectable to the fluid circuit of the main device; or Slave devices for electrical industrial equipment

[0010] According to another aspect of the invention, the central control unit is adapted to supply a DC voltage between 5V and 48V, in particular 24V, to the remote accessory. According to another aspect of the invention, the switching circuit comprises a step-down chopper. According to another aspect of the invention, the current regulator is configured to reduce the duty cycle of the chopper when a peak current at the input of the current regulator reaches a predetermined threshold.

[0011] According to another aspect of the invention, the switching circuit also comprises a measurement stage for measuring a peak current at the input of the switching circuit, the measurement stage being configured to convert the peak current at the input of the switching circuit into a voltage which is an image of this peak current. According to another aspect of the invention, the switching circuit comprises a shaping stage configured to provide a DC voltage which is an image of the peak current at the input of the switching circuit, and an output filter arranged downstream of the chopper and configured to smooth current pulses at the output of the chopper.

[0012] According to another aspect of the invention, the measurement stage comprises a first resistor arranged between an input of the measurement stage and a first output of the measurement stage connected to the chopper, and a first transistor having an emitter connected to the input of the measurement stage via a second resistor; the collector of the first transistor is connected to ground via a third resistor; the base of the first transistor is connected to the collector of the first transistor on the one hand, and the base is connected to the base of a second transistor on the other hand; the emitter of the second transistor is connected to the first output via a fourth resistor, and the collector of the second transistor is connected to ground via a fifth resistor on the one hand and to the base of a third transistor on the other hand; the emitter of said third transistor is connected to the emitter of said first transistor, and the collector of said third transistor is connected on the one hand to ground via a sixth resistor and on the other hand to a second output of said measurement stage, this second output being intended to be connected to an input of a shaping stage; the shaping stage comprises a first diode, the anode of which is connected to the input of the shaping stage and the cathode of which is connected to ground via a first capacitor on the one hand and to the output of the shaping stage via a seventh resistor on the other hand, the output of which is also connected to ground (GND) via an eighth resistor; The chopper includes a controller, the controller comprising: an input voltage terminal configured to be connected to a first output of the measurement stage; a ground terminal configured to be connected to ground; an output terminal configured to be connected to the input of the output filter; a feedback terminal configured to be connected to the output of the shaping stage; and a frequency compensation terminal configured to be connected to the output of the shaping stage via a second capacitor; The output filter includes an inductor having a first terminal connected to the output of the chopper, which is connected to the output terminal of the chopper controller, and a second terminal connected to the cathode of a second diode, the anode of which is grounded, and a second terminal connected to ground via a third capacitor.

[0013] According to another aspect of the invention, the switching circuit is configured to have a 100% duty cycle when there is no short circuit in the remote accessory. Other characteristics and advantages of the invention will appear more clearly on reading the following description and the accompanying drawings, given as illustrative and non-limiting examples. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an electrical industrial device according to an embodiment of the present invention; [Figure 2] FIG. 2 illustrates an electrical circuit diagram of a current regulator, in accordance with one embodiment of the present invention. [Figure 3] FIG. 2 illustrates a predetermined charging curve in accordance with one embodiment of the present invention. [Figure 4] 4 is a diagram showing the relationship between the input and voltage of the current regulator during charging shown in FIG. 3 and the current at the output of the current regulator. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, embodiments of the present invention will be described, in which identical elements are designated by the same reference numerals. The following embodiments are exemplary. Although one or more embodiments are referred to in this specification, this does not necessarily mean that each reference relates to the same embodiment or that each feature applies only to a single embodiment. Furthermore, individual features of various embodiments may be combined or interchanged to form other embodiments.

[0016] The present invention relates to an electrical industrial device 1, as shown in Figure 1, comprising a main device 3 and at least one remote accessory 5 for the main device 3. The main device 3 comprises a fluid circuit 7 for feeding gas to an inlet 3a of the main device 3. The fluid circuit 7 comprises, in particular, a pumping device 9, such as a vacuum pump. The electrical industrial equipment 1 is for example a vacuum pump or a leak detector. The fluid circuit 7 may comprise various elements such as a detector or analyzer 11, a valve 13 or a sensor 15 such as a pressure sensor or a temperature sensor. The main device 3 also comprises a central control unit 17 configured to control at least one element of the fluid circuit 7, such as the pump device 9, and / or the sensor 15, and / or the valve 13, and / or the detector 11.

[0017] The central control unit 17 is arranged to be powered by a power grid external to the main device 3. The central control unit 17 is provided with an auxiliary power port 17a, in particular for powering the remote accessories 5. The remote accessory 5 is an electrical remote accessory that receives power from the central control unit 17 of the main device 3 via a power cable 19 connected to an auxiliary power port 17 a of the central control unit 17 . The power is supplied by a DC voltage of 5 V to 48 V, in particular a DC voltage of 24 V. However, the present invention is not limited to these voltage values.

[0018] The remote accessory 5 is a human-machine interface that combines command and control functions, such as a touch screen, a command screen, etc. For example, a touch screen that allows certain functions of the device 1 to be controlled, or a control screen that allows the values ​​of the parameters of the device 1 to be controlled, or a control box, for example with command buttons that allow to control certain functions of the device 1, or a measuring device, such as a sensor for measuring pressure or vibrations, or A test probe, such as a tracer gas spray gun or a leak detector olfactory probe, has a conduit that is fluidly connectable to the fluid circuit 7 of the main device 3. The remote accessories may be other electrical industrial equipment, called slave industrial equipment, that is powered by a main unit 3 of the electrical industrial equipment 1, called the master industrial equipment.

[0019] The central control unit 17 includes a current regulator configured to limit the current in the event of a short circuit in the remote accessory 5. The current regulator includes a switching circuit whose switching duty cycle is controlled as a function of the peak input current of the switching circuit.

[0020] Figure 2 shows an embodiment of a current regulator with a switching circuit in which switching is performed by a step-down chopper P3, although other types of choppers can also be used. The switching circuit comprises a first stage P1 configured to measure the peak current at the input E of the switching circuit and to convert the peak current at the input E of the switching circuit into a voltage that is an image of said peak current.

[0021] The measurement stage (first stage) P1 includes a first resistor R1, a first transistor T1, a second transistor T2, and a third transistor T3; A first resistor R1 is arranged between an input E1 of this measurement stage P1 and a first output S1 of the measurement stage P1 which is connected to a chopper P3. the emitter of said first transistor T1 is connected via a second resistor R2 to the input E1 of said measurement stage P1, the collector of said first transistor T1 is connected via a third resistor R3 to ground, denoted GND, and the base of said first transistor T1 is connected on the one hand to the collector of this first transistor T1 and on the other hand to the base of said second transistor T2, the emitter of the second transistor T2 is connected to the first output S1 via a fourth resistor R4, and the collector of the second transistor T2 is connected to ground via a fifth resistor R5 on the one hand and to the base of the third transistor T3 on the other hand; The emitter of the third transistor T3 is connected to the emitter of the first transistor T1, and the collector of the third transistor T3 is connected to ground GND via a sixth resistor R6 on the one hand and to the second output S1' of the measurement stage P1 on the other hand.

[0022] The measurement stage P1 therefore corresponds to a current-to-voltage amplifier that measures the peak current at the input E via a first resistor R1 and makes it possible to convert the peak current at the input E of the current regulator into a voltage that is the image of this peak current. The current regulator also comprises a second stage, a shaping stage P2, configured to output a DC voltage which is the image of the peak current at the input E of the switching circuit. The shaping stage P2 has an input E2 connected to the second output S1' of the measurement stage P1. The shaping stage P2 has a first diode D1 whose anode is connected to the input E2 of the shaping stage P2 and whose cathode is connected on the one hand to ground GND via a first capacitor C1 and on the other hand to the output S2 of the shaping stage P2 via a seventh resistor R7, which output S2 is also connected to ground GND via an eighth resistor R8.

[0023] Thus, the shaping stage P2 detects the peak value of the current at the input of the current regulator and converts it into VFB It is possible to convert it into a DC voltage shown by The current regulator comprises a third stage which is a step-down chopper P3, which is equipped with a controller CR, for example the L7985 manufactured by STMicroelectronics.

[0024] However, the operation of the chopper does not depend on this particular controller and can be implemented with other general circuits or circuits based on single-function electronic components. This chopper consists of a switch, a reference voltage V REF , this reference voltage V REF and V FB an error amplifier between them, and a control circuit for controlling the switches, which control circuit makes it possible, among other things, to generate a pulse width modulation (PWM), to detect the maximum current in the switches, and to apply a burst mode.

[0025] The controller CR has an input voltage terminal Vcc connected to the first output S1 of the first stage, the measurement stage P1, a ground terminal GND connected to the ground GND, an output terminal OUT connected to the output S3 of the chopper P3, and a voltage V FB and a frequency compensation terminal COMP connected to the output S2 of the shaping stage P2 via a second capacitor C2. The controller CR also comprises an activation terminal EN, adapted for example to be connected to the input E1 of the measurement stage P1.

[0026] Alternatively, as in the example of FIG. 2, the activation terminal EN may be connected to the output S1 of the measurement stage P1 via a resistor Ra, to the power supply terminal via a resistor Rb, and to ground via a voltage Rc. The current regulator also comprises a fourth stage, corresponding to an output filter P4, located downstream of the third stage associated with chopper P3 and configured to smooth current pulses at the output S3 of chopper P3.

[0027] The fourth stage of the output filter P4 includes an inductor L1 having a first terminal and a second terminal. The first terminal of the inductor L1 is connected to an input E4 of the output filter P4, which is connected to the output S3 of the chopper P3, and the other first terminal is connected to the cathode of a second diode D2, the anode of which is connected to ground GND. The second terminal of the inductor L1 is connected to ground GND via a third capacitor C3, and the other second terminal is connected to an output S4 of the output filter P4, which corresponds to the output S of the current regulator. The fourth stage of the output filter P4 makes it possible to smooth the current pulses and reduce their duty cycle when the chopper P3 is in limiting mode.

[0028] Thus, in operation, the peak current at the input E of the current regulator is measured via the first resistor R1 of the measurement stage P1.

[0029] The image of the peak current and the voltage V shaped by shaping stage P2 FB is applied to the feedback terminal FB of the controller CR of the chopper P3. This voltage V FB is the reference voltage V REF (for example, 0.6V) the duty cycle of chopper P3 is 100% and the voltage V at the output S of the current regulator S is the voltage V at the input E of the current regulator E (V S =V E ).

[0030] The output current I at the output S of the current regulator S (also called load current) has a value I TRIP When it reaches the voltage V FB is the reference voltage V REF Then the current regulator regulates the output current I S As is further increased, the voltage V FB is the reference voltage V REFThe duty cycle is controlled to decrease to keep the output voltage V equal to S decreases, and the constant output current I S The higher the loop gain of chopper P3, the steeper this transition will be.

[0031] Therefore, the output current I S As increases, the duty cycle decreases and approaches 0%, and the peak current in the switch of the controller CR of chopper P3 increases. When this peak current limit is reached, chopper P3 enters burst mode, where chopper P3 operates in bursts to maintain this peak current limit. At that time, the output voltage V S approaches 0V, and the output current I S reaches its limit value. The power delivered to the load is essentially zero and the power consumed by the current regulator remains low.

[0032] Output current I S decreases (value I TRIP ), the current regulator returns to normal operating mode (as opposed to burst mode) without the need for a manual reset.

[0033] The current regulator shown in Figure 2 was supplied with the voltage of 24 V from the remote accessory 5, and a test was conducted to simulate the remote accessory 5 using an electronic load that generated a trapezoidal current of 1.5 seconds duration and 1.5 A amplitude, as shown in Figure 3. Resistor R8 was connected to the current I TRIP was chosen to be 0.65A. Such a trapezoidal load allows the current regulator to operate under all operating conditions, i.e., no load, output current I OUT I TRIP Under normal operating conditions, the output current I OUT I TRIP Higher current limit mode and output current I OUT Again I TRIPThis allows testing in a smaller return to normal operation mode.

[0034] Figure 4 shows the input current I at the input of the current regulator during charging as shown in Figure 3. IN and the output voltage V at the output terminal S of the current regulator OUT、 and output current I OUT FIG. 1 is a timing diagram showing the change over time. The timing diagram can be divided into five distinct phases, 1-5 (separated by dotted lines in Figure 4).

[0035] In phase 1, the output current I is supplied through an electronic load that simulates a remote accessory. OUT In this phase, the output voltage V OUT is the input voltage V at the input E of the current regulator IN is equal to V OUT =V IN =24V.

[0036] In phase 2, the current regulator is in normal operation. At this time, the output current I OUT I TRIP Smaller, V FB is the reference voltage V REF Since V is smaller than V, chopper P3 is inactive (duty cycle is 100%). OUT The drop in is caused by the resistance of the first resistor R1 for current measurement and the resistance of the chopper P3 in the ON state.

[0037] In phase 3, the current consumption I OUT (or output current) is I TRIP , and above which the chopper duty cycle begins to decrease, reducing the output voltage V OUT and the input current of the current regulator, I IN is declining sharply.

[0038] In phase 4, the duty cycle approaches 0%, the chopper enters burst mode, and the input current I INdrops to the minimum value (approximately 80mA), and the output current I OUT The current consumption of the reaches the limit value (approximately 1.1A), and the output voltage V OUT approaches 0V (a dead short). The current regulator can maintain this configuration indefinitely. The input current I IN Lower power consumption and heat generation result in improved energy efficiency and reliability.

[0039] In phase 5, the output current I flows through an electronic load that simulates a remote accessory. OUT decreases, and the output current I drawn through the electronic load OUT In Figure 4, RECOV The threshold (I TRIP Smaller but this I TRIP When the voltage drops below a value close to 0.55V, e.g., 0.55V to 0.6V, the current regulator resumes normal operation. The hysteresis seen in the timing diagram of Figure 4 is due to the capacitor in the output filter P4.

[0040] Thus, the current regulator with the switching circuit of the present invention makes it possible to limit the input current in the event of a short circuit occurring in the remote accessory 5 powered via this current regulator. Such a current regulator makes it possible to limit power consumption and therefore heating of the components of the switching circuit while protecting the central control unit 17. In fact, significant heating could damage the central control unit 17. Furthermore, such a current regulator does not need to be reset when the short circuit disappears, but automatically returns to the nominal operating mode. [Explanation of symbols]

[0041] 1. Electrical Industrial Equipment 3 Main device 5 Remote Accessories 7 Fluid circuit 9. Pumping equipment 11 Detectors or analytical devices 13 Valve 15 sensors 17 Central Control Unit 17a Auxiliary Power Port 19 Power cable E Current regulator input S Current regulator output P1 Measurement stage (first stage) P2 shaping stage (second stage) P3 Step-down chopper (3rd stage) P4 Output filter (4th stage)

Claims

1. An electrical industrial device (1) comprising a main device (3) and at least one remote accessory (5) for said main device (3), The main device (3) comprises a fluid circuit (7) for feeding gas to an inlet (3a) of the main device (3) and a central control unit (17); the central control unit (17) is configured to control at least one element of the fluid circuit (7), is configured to be powered by a power grid, and further comprises an auxiliary power port (17a); The remote accessory (5) is powered by the central control unit (17) of the main device (3) via a power cable (19) connected to the auxiliary power port (17a) of the central control unit (17) of the main device (3); the central control unit (17) includes a current regulator for limiting current in the event of a short circuit in the remote accessory (5); The current regulator comprises a switching circuit whose switching duty cycle is controlled as a function of the peak input current of the switching circuit.

2. 2. Electrical industrial equipment according to claim 1, characterized in that the main device (3) is a vacuum pump or a leak detector and the fluid circuit (7) comprises a pumping device (9).

3. 3. Electrical industrial equipment according to claim 1 or 2, characterized in that the remote accessory (5) is an element of one of the following lists: Human-Machine Interface Command Screen Control Screen Control box Measuring equipment a test probe with a conduit fluidly connectable to the fluid circuit (7) of the main device (3); or Slave device of the electrical industrial equipment

4. 3. Electrical industrial equipment according to claim 1 or 2, characterized in that the central control unit (17) is configured to supply the remote accessory (5) with a DC voltage of 5V to 48V.

5. 3. The electrical industrial equipment according to claim 1, wherein the switching circuit comprises a step-down chopper (P3).

6. The current regulator is configured to reduce the peak current at the input of the current regulator to a predetermined threshold (I ＴＲＩＰ 6. The electrical industrial equipment according to claim 5, wherein the duty cycle of the step-down chopper (P3) is reduced when a voltage drop of 0 V is reached.

7. 6. Electrical industrial equipment according to claim 5, characterized in that the switching circuit further comprises a measurement stage (P1) for measuring a peak current at the input of the switching circuit, the measurement stage (P1) being configured to convert the peak current at the input of the switching circuit into a voltage which is an image of the peak current.

8. 8. The electrical industrial equipment of claim 7, wherein the switching circuit comprises a shaping stage (P2) configured to provide a DC voltage which is an image of the peak current at the input of the switching circuit, and an output filter (P4) arranged downstream of the step-down chopper (P3) and configured to smooth current pulses at the output of the step-down chopper (P3).

9. The measurement stage (P1) comprises a first resistor (R1) arranged between an input (E1) of the measurement stage (P1) and a first output (S1) of the measurement stage (P1) connected to the step-down chopper (P3); a first transistor (T1) whose emitter is connected to the input (E1) of the measurement stage (P1) via a second resistor (R2); The collector of the first transistor is connected to ground (GND) via a third resistor (R3), the base of the first transistor is connected on the one hand to the collector of the first transistor, and the base is connected on the other hand to the base of a second transistor (T2), The emitter of the second transistor is connected to the first output (S1) via a fourth resistor (R4), The collector of the second transistor is connected to ground (GND) via a fifth resistor (R5) on the one hand, and to the base of a third transistor (T3) on the other hand; the emitter of said third transistor is connected to the emitter of said first transistor (T1), and the collector of said third transistor is connected on the one hand to ground (GND) via a sixth resistor (R6) and on the other hand to a second output (S1') of said measurement stage (P1), said second output being intended to be connected to an input (E2) of said shaping stage (P2); the shaping stage (P2) comprises a first diode (D1) whose anode is connected to the input (E2) of the shaping stage (P2) and whose cathode is connected on the one hand to ground (GND) via a first capacitor (C1) and on the other hand to the output (S2) of the shaping stage (P2) via a seventh resistor (R7); The output (S2) is also connected to ground (GND) through an eighth resistor (R8), The step-down chopper includes a controller, the controller comprising: an input voltage terminal (Vcc) configured to be connected to the first output (S1) of the measurement stage (P1); a ground terminal (GND) configured to be connected to ground (GND); an output terminal (OUT) configured to be connected to the input (E4) of the output filter (P4); a feedback terminal (FB) configured to be connected to the output (S2) of the shaping stage (P2); and a frequency compensation terminal (COMP) configured to be connected to the output (S2) of the shaping stage (P2) via a second capacitor (C2); The output filter (P4) includes an inductor (L1), 9. The electrical industrial equipment according to claim 8, characterized in that it has a first terminal connected on the one hand to the output (OUT) of the step-down chopper (P3), which is connected to the output terminal (S3) of the controller of the step-down chopper (P3), and on the other hand to the cathode of a second diode (D2) having an anode connected to ground (GND), and a second terminal connected to ground (GND) via a third capacitor (C3).

10. 3. Electrical industrial equipment according to claim 1 or 2, characterized in that the switching circuit is configured to have the duty cycle of 100% when there is no short circuit in the remote accessory (5).

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